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CROSS-REFERENCE TO RELATED APPLICATION
[0001] Not applicable
BACKGROUND OF THE INVENTION
[0002] Field of the Invention
[0003] The present invention relates to the industrial art of earth-boring and well drilling for the recovery of fluid minerals. More particularly, the invention relates to a carrier for a multiplicity of shaped explosive charges to penetrate well casing with multiple apertures.
[0004] Description of Related Art
[0005] In the oil and gas industry, well plugging operations are often performed to seal wellbores in order to abandon the wells. Eventually, all wells exhaust their purpose and are abandoned. Either the well is a “dry hole”, having no economically viable production, or has depleted the production strata. In either case, a non-productive well is or should be permanently “plugged”. “Plug and abandonment” procedures are required under various state and federal laws and regulations. Plug and abandonment operations performed upon a cased wellbore require that at least a section of the wellbore be filled with cement to prevent the upward movement of fluids toward the surface of the well. To seal the wellbore, a bridge plug is typically placed at a predetermined depth in the wellbore and thereafter, cement is injected into the wellbore to form a column of cement high enough to ensure the wellbore is permanently plugged.
[0006] In addition to simply sealing the interior of a wellbore, plug and abandonment regulations additionally require that an area outside of the wellbore be sufficiently blocked to prevent any fluids from migrating towards the surface of the well along the outside of the casing. Migration of fluid outside of the casing is more likely to arise after a fluid path inside the wellbore has been blocked. Additionally, where multiple strings of casing line a wellbore, the annular area between concentric casing strings can form a fluid path in spite of being cemented into place when the well was completed. Inadequate cement jobs and deterioration of cement over time can lead to flow paths being opened through an otherwise solid cement barrier.
[0007] There are several reasons to line a well borehole with two or more substantially concentric casings. As one example, two or more mineral strata may be produced from the same borehole. In this example, a smaller diameter casing is set within a larger diameter casing. A first mineral stratum of oil, gas or both, may be produced along the flow annulus between the two casings. A second, usually deeper mineral stratum is produced along the flow bore of the smaller or innermost casing. This sequence may be repeated for multiple pay strata and multiple concentric casings.
[0008] Another example of multiple concentric casings is that of extremely deep borings that require a tapered casing string to line an unstable raw borehole along a greater depth than normally expected of a surface casing. In this context, a “tapered” casing string means one in which an inner casing of smaller OD than the ID of an outer casing is secured to the end of the outer casing. Although the surface casing may not penetrate a mineral bearing stratum, the annulus between two concentric casings may carry a flow of gas that has escaped an inner flow bore.
[0009] Many off-shore, deep water wells have extremely large surface casings; in the order of 24″ ID. These large surface casings are set to a bottom hole depth of 3,000′ to 5,000′ below the seafloor. The seafloor may be under an ocean depth of 1,000′ to 5,000′ below a drilling rig floor.
[0010] When a well is abandoned, all of the productive flow channels must be filled with cement to a designated depth below the surface or seafloor. In the case of multiple casings, there are two possible approaches available for sealing all of the annuli present. In one approach, as represented by U.S. Pat. No. 5,472,052 to P. F. Head, all of the upper ends of casings that are interior of the outermost casing are milled away down to the designated depth. Thereafter, a solid core of cement is placed to fill the interior volume of the outermost casing. The annulus between the outermost casing OD and the raw borehole ID is filled with cement when originally set.
[0011] An alternative well plugging procedure is to set a bridge plug within the innermost casing and perforate the inner casing wall above the plug. Cement is pumped down the inner casing and forced out into the annulus between the inner and outer casings. For multiple annuli, this process is repeated by the selective use of shaped charges that will perforate only the desired number of casing walls but not the outermost casing.
[0012] Of the two procedures available for plugging an abandoned well, the latter procedure of casing wall perforation and filling the one or more annuli with cement is more economical by several orders of magnitude. However, deep water offshore wells present unique difficulties for this alternative procedure. When originally drilled, a large drilling platform or drill ship was used to support the immense weights and forces necessary to drill such wells. A “riser” of greater diameter than the largest casing to be set in a particular well links the surface casing to the drilling rig to protect the borehole from invading seawater and as a conduit for the return flow of drilling fluid. When the drilling and well preparation is complete the drilling platform is removed along with the large riser. Smaller and lighter drill ships capable of supporting considerably smaller risers, in the order of 6⅝″, are used for well maintenance. By the time of well abandonment, platforms such as was used for the original drilling, are not economically available. In many deep water wells, however, even the smallest or innermost casing is larger than the riser capacity of most maintenance ships.
[0013] Casing perforations utilized in a cement “squeezing” operation are typically formed with a perforating assembly that includes a number of shaped charges. An apparatus representative of this concept includes resiliently biased members that remain in contact with the casing wall as the apparatus is lowered into the well. The shaped charges are mounted on the inside surface of bars that are resiliently biased to maintain physical contact with the interior casing wall. The shaped charges are secured at a predetermined distance from the inside bar surface as determined by the casing wall thickness and/or the number of casing walls to be penetrated. An example of such a resiliently biased perforating gun is disclosed in U.S. Pat. No. 5,295,544 to D. V. Umphries. However, the radial expansion distance of a prior art resilient bar is insufficient to accommodate the radial difference between a 6⅝″ maintenance ship riser and a 24″ casing.
SUMMARY OF THE INVENTION
[0014] The present perforating tool provides a variable diameter carrier for multiple perforation charges having the functional capacity of descending along a small inside diameter riser pipe into a larger inside diameter casing. As the carrier enters the larger diameter casing, a bias force on shaped charge carrier ribs expands the ribs into contact with the inside wall surfaces of the larger casing.
[0015] The carrier comprises an axially aligned central tube or rod that may be supported at the end of a wire line, tubing or pipe string. Secured to the central rod are two framing discs. Geometric planes respective to the framing discs are typically normal to the central rod axis and are separated by a distance determined by the length of shaped charge carrier ribs.
[0016] Along the central rod length on opposite sides of the framing discs are hinge carriers that are confined to the central tube for axial translation along the tube length. Coil springs confined around the central tube bear upon the hinge carriers to resiliently bias the hinge carriers toward each other.
[0017] One end of a plurality of radius rods has an articulated connection to the hinge carriers. The opposite end of each radius rod is hinged to a respective end of a shaped charge carrier rib. The opposing bias of the coil springs acting upon the hinge carriers and radius rods imposes resilient radial bias on the shaped charge carrier ribs. The shaped charge carrier ribs are shaped to a substantially rigid section modulus to oppose mid-length bending between the hinges. An outer face of each shaped charge carrier rib is substantially straight between the hinges to physically engage the inside surface of the intended casing. A line of shaped charges is secured along the inside length of the charge carrier ribs at predetermined distances inwardly from the rib outside surface as dictated by the perforation mission.
[0018] The shaped charge carrier ribs of an assembled tool are radially compressed against the bias of the coil springs at both ends for transit along the riser bore. As the tool enters a larger ID casing, the coil spring bias expands the charge carrier ribs into contact with the inside casing surface for final placement and discharge of the shaped charges.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The invention is hereafter described in detail and with reference to the drawings wherein like reference characters designate like or similar elements throughout the several figures and views that collectively comprise the drawings. Respective to each drawing figure:
[0020] FIG. 1 is a pictorial view of a prior art apparatus.
[0021] FIG. 2 is a partial section view of the invention in a collapsed assembly mode.
[0022] FIG. 3 is a partial section view of the invention in an expanded assembly mode.
[0023] FIG. 4 is a section view of the invention along cutting plane IV-IV of FIG. 2 .
[0024] FIG. 5 is a section view of the invention along cutting plane V-V of FIG. 3 .
[0025] FIG. 6 is a sectioned detail of a shaped charge carrier rib.
[0026] FIG. 7 is a profile view of a particular utility of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] As used herein, the terms “up” and “down”, “upper” and “lower”, “upwardly” and downwardly”, “upstream” and “downstream”; “above” and “below”; and other like terms indicating relative positions above or below a given point or element are used in this description to more clearly describe some embodiments of the invention. However, when applied to equipment and methods for use in wells that are deviated or horizontal, such terms may refer to a left to right, right to left, or other relationship as appropriate. Moreover, in the specification and appended claims, the terms “pipe”, “tube”, “tubular”, “rod”, “casing”, “liner” and/or “other tubular goods” are to be interpreted and defined generically to mean any and all of such elements without limitation of industry usage.
[0028] In describing a preferred embodiment of the invention illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.
[0029] With reference to FIG. 1 , an example of a prior art casing perforator is shown to comprise six rows of shaped charge carrier ribs 12 . Each charge carrier rib may support six shaped charges 14 , for example. The six shaped charge carrier ribs 12 are supported between upper and lower framing discs, 16 and 17 A framing rod 19 passes centrally through the framing discs 16 and 17 . The framing discs 16 and 17 are secured to upper and lower collars 20 and 21 , respectively, by upper and lower legs 23 and 24 . The upper and lower collars 20 and 21 ring the framing rod 19 . A rigid assembly of collars 20 and 21 , the legs 23 and 24 , the framing discs 16 and 17 and shaped charge carriers 12 is confined along the length of framing rod 19 between upper and lower compression nuts 26 and 27 .
[0030] Distinctive of this prior art tool represented by FIG. 1 is provision for compression load against the shaped charge carriers 12 . Such compression loading is imposed by preloading nuts 29 (only the upper nut 29 is shown) turned against the respective framing discs 16 and 17 . Compression load at opposite ends of the shaped charge carriers 12 effects a resiliently arced position to the carriers thereby forcing a bias on the shaped charges 14 against the inside surface of a surrounding casing.
[0031] Although the prior art tool described by FIG. 1 is effective for use with a casing of known size having direct accessibility, compliance to casing size variation is extremely limited; a limitation the present invention is intended to overcome.
[0032] Referring to the partial sections of FIGS. 2 and 4 , the present invention is shown in a radially constricted mode as configured to traverse the length of a small diameter riser pipe 50 . Central to the tool construction is a framing rod or tube 30 preferably having a hollow bore to carry detonation cord 31 . A bail 36 may secured to the upper end of the framing tube for attachment of a suspension wireline 38 . In a mid-section of the framing tube, upper and lower framing discs, 32 and 33 respectively, are secured at selected axial positions along the framing tube 30 length. The outer perimeter of the framing discs 32 and 33 set constrictive limit stops for a plurality of shaped charge carrier ribs 40 .
[0033] The shaped charge carrier ribs 40 are secured to the central framing tube 30 by a translational linkage that will maintain a substantial parallelism between the ribs 40 as the are translated from a first constricted circumference to greater circumference in abutted engagement with the inner walls of a larger ID casing. Although only two shaped charge carrier ribs 40 are illustrated by FIGS. 2 and 3 as a diametric pair, it should be understood the tool will normally be provided with four to eight such shaped charge carrier ribs. Consequently, the axial separation between the framing discs 32 and 33 should be no greater than the length of the shaped charge carrier ribs 40 but may be somewhat less.
[0034] A preferred embodiment of a suitable translating linkage mechanism may include an articulated joint or hinge 44 secured at opposite distal ends of each shaped charge carrier rib 40 . One distal end of a tie rod 42 is secured to a carrier rib 40 by an articulated joint or hinge 44 and the opposite distal end of the tie rod 42 is secured to an upper or lower hinge carrier 48 or 49 by an articulated joint or hinge 46 . The hinge carriers 49 are radially confined around the framing tube 30 but are freely translated along the tube length. Upper and lower coil springs 52 and 53 , respectively, are compressed between the hinge carriers 48 and 49 and upper and lower base rings 55 and 56 for a passively resilient displacement force on the rib 40 articulation linkage.
[0035] Viewing FIGS. 2 and 3 comparatively, it may be seen that when the tool passes from the smaller diameter bore of the riser 50 into a casing 60 of greater diameter, the expanding bias of springs 52 and 53 displace hinge carriers 48 and 49 along the framing tube 30 in mutually opposite directions. Hinge carrier displacement is transferred to the tie rod hinges 46 which are confined to a fixed radial separation distance from the framing tube 30 . Consequently, the interior ends of the fixed length tie rods 42 , hinged to the shaped charge carrier ribs 40 , displace the shaped charge carrier ribs from contact with the framing discs 32 and 33 and radially out against the inside surface of the greater diameter casing 60 .
[0036] The enlarged detail of FIG. 6 illustrates a representative shaped charge 41 secured within the inside arc of a shaped charge carrier rib 40 having a cross-sectional shape configured to high bending modulus. An aperture 42 is formed in the apex of-the carrier in line with the discharge axis of the shaped charge 41 . The spring driven bias on the shaped charge carrier rib 40 presses the rib apex line into tangent contact with the inside surface of the casing 60 . Shaped charge penetration depth may be adjusted by a controlled separation distance between the contact face of the carrier rib and the discharge face of the shaped charge.
[0037] Those of ordinary skill in the art will also understand that section shapes having a high bending modulus other than the half cylinder arc of carrier rib 40 may also be used. A channel section rib is an example. Box sections, rectangular sections and 90° angle sections may also be used.
[0038] It is important that the casing perforations opened by the present tool are limited to the one or more intended interior casings and exclusive of the outermost well casing. Skilled selection of shaped charge penetration depth, capacity and configuration considers the casing wall thickness and annulus separation between the walls. This selection process is assisted by a controlled separation distance of a shaped charge discharge face from the inside surface of the casing. The present invention facilitates such controlled separation distance.
[0039] Among relevant tool design criteria is the length of the tie rods 42 as it affects the expanded angle of the rods. After discharge, the tool is usually withdrawn from the wellbore back through the riser 50 . As the tool passes through the transition point between the casing and riser, the shaped charge carrier rib ends attached to the upper tie rods 42 are forced inwardly toward the framing tube 30 . Consequently, the upper hinge carrier 48 translates upwardly against the bias of upper spring 52 . Such compressive force on the spring 52 translates to the tensile force drawn on the wireline 38 .
[0040] In a different application, two of the present perforating tools 64 and 66 may be secured at the end of a suspension pipe or tubing string 61 with a bore packer 65 attached between the two as illustrated by FIG. 7 to verify the seal integrity of cement annulus around a casing. A bridge plug 62 is set to seal the bore of a subject casing 60 to be tested for integrity of a cement annulus seal around the subject casing 60 . The FIG. 7 tool assembly is positioned above the bridge plug 62 . The packer 65 is expanded to seal the annulus 69 between the casing 60 ID and the suspension tube 61 OD. The lowermost perforating tool 66 is now confined in a pressure retention zone 68 between the bridge plug 62 and the packer 65 .
[0041] Discharge of the two perforating tools 64 and 66 opens apertures through the casing 60 into the surrounding cement sealing collar. From the surface, fluid is pumped through the suspension tube 61 into the pressure retention zone 68 . Simultaneously, pressure within the annulus 69 between the casing 60 ID and the suspension tube 61 OD above the packer 65 is monitored. An increase in annulus fluid pressure above the packer 65 is an indication of leakage and fluid migration past the cement sealing collar around the subject casing 60 OD,
[0042] Those of ordinary skill will also quickly appreciate a wheeled adaption of the invention for use in deviated or horizontal well bore directions. Such wheeled embodiments may be by directly attached axles or fore and aft accessory carriages.
[0043] The foregoing description of the invention represents a fundamental, self-actuating embodiment having a standing resilient expansion bias on the charge carrier ribs imposed by a pair of identical coil springs 52 and 53 . Hence, the tool has no dependency on remote controls or power sources to engage and disengage inside diameter surfaces of larger casings. However, numerous alternative mechanisms are also well known to the prior art.
[0044] Non-illustrated examples of mechanisms that are generally equivalent to the coil springs 52 and 53 may include pneumatic, oleo-pneumatic and hydraulic piston/cylinder devices operating as direct substitutes for the coil springs 52 and 53 .
[0045] Charge carrier ribs 40 may be expanded by numerous translational mechanisms other than the radius rods 42 described herein. For example, an opposed scissors mechanism similar to a lifting jack may be particularly useful in certain applications to translate the charge carrier ribs radially against a casing ID.
[0046] Another example of the invention may position the radius rods and hinge carriers between the charge carrier ribs and the central tube with a resilient force such as springs between the hinge carriers.
[0047] Although the invention disclosed herein has been described in terms of specified and presently preferred embodiments which are set forth in detail, it should be understood that this is by illustration only and that the invention is not necessarily limited thereto. Alternative embodiments and operating techniques will become apparent to those of ordinary skill in the art in view of the present disclosure. Accordingly, modifications of the invention are contemplated which may be made without departing from the spirit of the claimed invention.
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A shaped charge carrier tool is provided that has particular utility for perforating well casing as a preparation for cement placement. A plurality, four or more elongated shaped charge carrier ribs having a high bending modulus are secured for radially expanded displacement around a central framing tube or rod. Radius rods link the ends of the carrier ribs to top and bottom hinge carriers. The hinge carriers encircle the framing tube and are free for axial translation along the framing tube. Articulating hinges connect the radius rods to the carrier ribs and to the hinge carriers. Opposed compressed coil springs provide a resilient bias on the hinge carriers to translate the carrier ribs radially outward against the interior surface of a well casing as the tool passes from a riser tube into a larger inside diameter well casing.
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FIELD OF INVENTION
This invention relates to a bit attaching arrangement for a power tool, and more particularly to an arrangement that allows the bit to be attached without the use of external wrenches or keys.
BACKGROUND OF THE INVENTION
Power tools, such as routers, often incorporate a collet for holding the shank end of a bit in place on the lower end of the rotating armature/output shaft. In particular, the collet consists of a generally cone-shaped structure having a split end which defines separate prongs which are usually biased slightly radially outwardly. The end of the collet opposite the prongs is generally attached to or formed integrally with the output shaft of the router. A router locking nut is used to secure a bit onto the output shaft. The collet nut has a female thread surface which engages the male thread surface located on the lower end of the output shaft. The collet nut fits over the collet and has a female cone-shaped camming surface for engaging the cone-shaped outer surface of the collet.
In order to attach a bit to a router utilizing this well-known structure, the shank of the bit is positioned between the prongs of the collet with the collet nut in a loosened position on the output shaft. After the shank of the bit is completely disposed within the hollow output shaft, the collet nut is tightened such that the prongs of the collet engage the side surfaces of the shank and firmly hold the bit in place on the lower end of the shaft. In order to sufficiently tighten the collet nut so as to secure the bit, external and separate tools and/or wrenches are typically utilized. In particular, the tightening operation of this prior art structure often involves utilizing a shaft lock arrangement which prevents rotation of the output shaft of the router and thereafter allows manual tightening of the nut using a dedicated individual wrench which is often included with the router when it is sold.
This prior locking arrangement suffers from numerous disadvantages. First, because the tightening wrench is a separate item, it is often lost or misplaced after the router has been used for a period of time. This often results in an operator utilizing a nondedicated wrench or pliers to tighten the collet nut. Use of an incorrect sized wrench or pliers may result in damage to the collet nut and/or locking arrangement. Additionally, use of a nondedicated wrench can also result in the collet nut not being sufficiently tightened causing slippage between the bit and the output shaft.
A further disadvantage is the amount of time it takes to replace a router bit. More specifically, to adequately tighten the collet nut, it requires numerous placement and replacement of the wrench on the collet nut to tighten the nut. This is due to limited access to the attaching arrangement through the guards and support plates of the router. Still further, as mentioned above, to rotate the nut with respect to the output shaft, oftentimes there is a shaft-locking mechanism disposed internally within the assembly. This can result in a further disadvantage because of the possibility of the shaft-locking mechanism malfunctioning and impeding the rotation of the output shaft.
Therefore, a bit-locking arrangement is needed which will overcome the problems discussed above.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a locking arrangement for a power tool which does not require any external wrenches or tools to secure the bit to the output shaft of the power tool.
Another object of the present invention is to provide a locking arrangement which does not require a separate spindle lock for maintaining the outward shaft stationary as the tightening nut of the arrangement is turned.
A still further object of this invention is to provide a bit-locking arrangement which is self-contained within the power tool and which provides for general fixation of the locking member while rotating the output shaft of the power tool to accomplish the tightening and loosening process.
Accordingly, the present invention provides for a bit-attaching arrangement for a power tool wherein the power tool has a rotatably driven shaft onto which a bit is attached and rotated through the use of a collet. The arrangement includes a collet nut threadably engaging the shaft. The collet nut has a plurality of slots positioned on an outer peripheral wall. A first gear is disposed on the shaft so that rotation of the first gear causes rotation of the shaft. An actuating member has a second gear and a slot engaging extension. The actuating member is positionable between a first position and a second position. In the first position, the second gear engages the first gear and the extension engages one of the slots. Upon rotation of the actuating member, the shaft will rotate and the collet will be maintained at a generally fixed rotational location, thus allowing loosening and tightening of a bit. In the second position, the first and second gears do not engage one another, and the extension does not engage one of the slots so that the shaft can be freely rotated during the powered operation of the tool.
The invention further includes the actuating member having a knob for rotation of the second gear. The actuating member is disposed in an aperture formed in the housing of the power tool. A button is disposed on the peripheral surface of the knob and is connected to a flange member that abuts a portion of the housing adjacent the aperture when the actuating member is in its second position. In order to orient the actuating member to its first position, the button is depressed to allow the flange to pass within the aperture, and thus to move the actuating member to its first position.
Additional objects, advantages, and novel features of the invention will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, which form part of this specification and are to be read in conjunction therewith, and in which like reference numerals are used to indicate like parts in the various views:
FIG. 1 is a side elevational view of a router, with a bit-locking arrangement embodying the principles of this invention;
FIG. 2 is a cross-sectional view taken generally along line 2 — 2 of FIG. 1 and showing the pinion shaft in its engaged position to allow rotation of the output shaft and maintain the collet nut at a generally fixed rotational location;
FIG. 3 is a cross-sectional view taken generally along line 3 — 3 of FIG.2;
FIG. 4 is a view similar to FIG. 3, but showing the pinion shaft in its retracted disengaged position and locked in place via the lockout structure of the knob; and
FIG. 5 is a view similar to FIG. 4 showing a bit secured in the bit-locking arrangement, and the pinion shaft in its disengaged position to allow operation of the router; and
FIG. 6 is a view showing an alternative bit-locking arrangement.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings in greater detail, and initially to FIG. 1, a router 10 having a bit-locking arrangement 12 according to the present invention is shown. Router 10 includes a housing 14 mounted to a generally horizontal support plate 16 . Contained within housing 14 is a motor (not shown) which rotates a generally cylindrical armature or output shaft 18 , as shown in FIG. 3 . Shaft 18 is supported in housing 14 by a bearing assembly 20 . Shaft 18 has a cylindrical bit receiving bore 22 formed on an exposed end, as shown in FIG. 5 . Bore 22 is configured to receive a shank portion 24 of a bit 26 . Shaft 18 further has a generally annular receiving area 28 formed on its lower end for maintaining a conical collet 30 thereon. Collet 30 includes connected generally semicircular prongs 32 (as best shown in FIG. 4 ), each having an inclined outer surface 34 . Prongs 32 of collet 30 surround shank 24 of bit 26 , as best shown in FIG. 5, such that the interior surface of prongs 32 engage shank 24 to secure bit 26 in position, as will be more fully described below. Although collet 30 is shown as a separate piece from shaft 18 , it may be desirable, and it is within the scope of this invention to form collet 30 integral with the bottom of output shaft 18 .
Shaft 18 further has outer thread surface 36 located adjacent its lower end, as best shown in FIG. 5 . Thread surface 36 engages female thread surface 38 of a collet nut 40 , such that collet nut 40 can be tightened and loosened on the lower end of shaft 18 to secure bit 26 in place, as will be more fully described below. Nut 40 further has a generally conical inner camming surface 42 for engaging the inclined surfaces 34 of prongs 32 , such that upward movement of nut 40 on shaft 18 results in prongs 32 being forced inwardly to tightly engage shank 24 and secure bit 26 in position, as best shown in FIG. 5 .
With reference to FIGS. 2 and 3, nut 40 further includes an outer peripheral surface 44 on which are formed a plurality of evenly spaced slots or splines 46 . Slots 46 are utilized to hold nut 40 at a generally fixed rotational location during tightening and loosening of bit 26 , as will be more fully described below. Each slot 46 is closed along its bottom and open at the top. Slots 46 are generally rectangular in shape and the sidewalls of the slots provide abutment surfaces that prevent rotation of nut 40 during tightening and loosening, as will be more fully described below.
Arrangement 12 further has an upper gear 50 . Upper gear 50 is secured on an outer surface of shaft 18 , such that rotation of gear 50 will result in rotation of shaft 18 . In particular, gear 50 can be key to shaft 18 in any suitable manner. Gear 50 includes an annular beveled gear surface 52 which will be utilized to rotate shaft 18 , as will be more fully described below. A pinion gear 54 has an annular beveled gear surface 56 for engaging gear surface 52 . Rotation of gear 54 results in rotation of gear 50 and thus results in rotation of shaft 18 . Thus, depending on which direction pinion gear 54 is rotated, such rotation can result in tightening or loosening of bit 26 in collet nut 40 .
Pinion gear 54 can be rotated by a router operator via pinion shaft 58 and actuating knob 60 . In particular, shaft 58 is slidably and rotatably mounted to housing 14 via a generally cylindrical passage 62 , as best shown in FIG. 4 . Passage 62 has an aperture 64 on one end through which pinion shaft 58 extends. Pinion shaft 58 is supported in passage 62 by an upwardly extending support member 66 . Additionally, knob 60 has formed therewith a generally annular cylindrical portion 68 which fits around pinion shaft 58 and snugly fits within aperture 64 .
A coilspring 70 generally surrounds pinion shaft 58 and is positioned between an abutting surface 72 of cylindrical portion 68 of knob 60 and support 66 . Spring 70 serves to bias pinion shaft 58 outwardly away from collet nut 40 and toward a position wherein pinion gear 58 is disengaged from upper gear 50 .
With reference to FIG. 2, located on an end surface 74 of pinion shaft 58 is a generally cylindrical receiving bore 76 . Received in bore 76 is a cylindrical locking pin or extension 78 . Pin 78 is used to engage one of slots 46 to hold collet nut 40 at a generally fixed rotational location during tightening and loosening, as will be more fully explained below. One end of pin 78 has a collar 80 formed therewith which prevents pin 78 from becoming disengaged from bore 76 . In particular, pin 78 can slide telescopically in and out of bore 76 and is biased outwardly away from end surface 74 by a coilspring 82 .
Pin 78 is also received in an aperture 84 formed in a pin bearing member 86 , as best shown in FIG. 5 . Bearing member 86 ensures that pin 78 will be adequately aligned with the appropriate slot 46 .
Pin 78 can engage any one of slots 46 when pinion gear 54 engages upper gear 50 . As pin 78 engages one of slots 46 , rotation of collet nut 40 will be prevented. Thus, rotation of pinion shaft 58 will result in collet nut 40 being fixed and shaft 18 being rotated. This rotational motion of pinion shaft 58 will result in tightening and loosening of collet nut 40 because collet nut 40 will move slightly up and down along thread surface 36 to accomplish the pinching and loosening actions of prongs 32 .
The provision of bore 76 with pin 78 disposed therein and the biasing of spring 82 allows pin 78 to translate only approximately one half the distance that pinion shaft 58 translates to thereby reduce the necessary size of gear 50 . For instance, if pinion shaft 58 were to translate 8 mm, it would be necessary for pilot pin 78 to translate 4 mm. This arrangement of pin 78 slidably coupled to shaft 58 also ensures that pin 78 is always maintained in bearing member 86 during the translation inwardly and outwardly of shaft 58 , as shown in FIGS. 3 and 4. Thus, pin 78 is always within aperture 84 of bearing member 86 and does not have to be realigned with the aperture every time pinion shaft 58 is translated. Still further, the spring loading action of pin 78 allows surface 52 to be at least partially engaged by gear surface 56 prior to pin 78 being disposed in one of slots 46 . More specifically, there may be occasions where an operator wishes to loosen a bit and thus translates pinion shaft 58 inwardly. Depending upon the rotational location of collet nut 40 , pin 78 may not be aligned with one of slots 46 , but instead may be aligned with a peripheral surface segment 90 of collet nut 40 which prevents pin 78 from locking collet nut 40 at a rotational location. If this situation occurs, pin 78 will be compressed in bore 76 against the bias of spring 82 to such an extent to allow gear surface 52 to engage gear surface 56 . An operator can then rotate shaft 58 utilizing knob 60 , thus resulting in rotation of collet nut 40 , until such time as pin 78 “snaps” into an appropriate slot 46 , thus fixing the collet nut at a rotational location.
With reference to FIGS. 3 and 4, a lockout structure 92 is shown. Lockout structure 92 is formed into knob 60 , as will be further described below. More specifically, the outer circumferential surface 94 of knob 60 has a lockout actuating button 96 which can be easily operated by a user gripping knob 60 . Button 96 is integrally connected to a locking flange, and further has a leaf-type biasing member 100 located opposite button 96 which serves to bias button 96 and thus locking flange 98 circumferentially outwardly away from pinion shaft 58 . Still further, portions 60 of knob 60 has a recess 102 formed therein for accommodating locking flange 98 when it is in its disengaged position to allow inward movement of shaft 58 , as best shown in FIG. 3 .
Locking flange 98 is shown in its lockout position in FIG. 4, wherein a front edge 104 of locking flange 98 engages an edge surface 106 of housing 14 adjacent aperture 64 . This engagement prevents shaft 58 from being translated inwardly accidentally until such time as the operator desires to translate shaft 58 inwardly by depressing button 96 , and thus disengaging locking flange 98 from edge surface 106 . After such actuation of button 96 , flange 98 is received in recess 102 and shaft 58 can be pushed inwardly such that flange 98 also slides within aperture 64 . As best shown in FIGS. 3 and 4, it is preferable to have pinion shaft 58 at an angle to the horizontal surface of plate 16 . This horizontal angle ensures that knob 60 is an adequate distance above plate 16 so as to not interfere with workpieces, guard surfaces, or adjusting structures.
In operation, arrangement 12 is first found in its untightened open position shown in FIG. 4 . More specifically, in this position prongs 32 of collet 30 are not yet being forced inwardly by the engagement between inclined surfaces 34 and camming surface 42 of nut 40 . Thus, shank 24 of bit 26 can be inserted through collet 30 and received in bore 22 of shaft 18 . In order to secure bit 26 in place on shaft 18 , an operator first pushes inwardly on button 96 so as to disengage locking flange 98 from edge surface 106 . Thereafter, an operator pushes inwardly on knob 60 such that pin 78 engages one of slots 46 on collet nut 40 and such that pinion gear 58 engages upper gear 50 . As is apparent, this inward movement of shaft 58 is against the bias of coilspring 70 . Shaft 58 slides within passage 62 easily due to the support member 60 , and also the tight fit of portion 68 of knob 60 . After the gears are engaged, pin 78 maintains collet nut 40 at a fixed rotational location, and knob 60 can be rotated such that gear 50 , and thus shaft 18 , are rotated with respect to collet nut 40 . This rotation of shaft 18 with respect to collet nut 40 results in the tightening of bit 26 in bore 22 .
After collet nut 40 has been adequately tightened, the operator releases all inward pressure on knob 60 , and thus pinion gear 54 returns to its nonengaged position due to coilspring 70 expanding from its compressed condition. Further, as shaft 58 moves further outwardly, edge 104 of flange 98 will clear edge 106 of housing 14 such that flange 98 snaps upwardly due to biasing member 100 to automatically lock shaft 58 in its outward nonengaging position. It is apparent that loosening of a bit takes place in the same manner described above except that pinion gear 54 is rotated in an opposite direction to loosen collet nut 40 .
Arrangement 12 offers numerous advantages over prior securing structures. In particular, arrangement 12 is completely self-contained within housing 14 , so that no separate wrenches or tools are required to secure bit 26 to output shaft 18 . Further, pin 78 allows an effective locking mechanism for collet 30 formed with pinion gear 54 . As is apparent, it is necessary that collet nut 40 move slightly vertically along shaft 18 , which is accomplished by the open-ended structure of slots 46 . Thus, pinion gear 54 with pin 78 thereon offers a highly advantageous single structure for accomplishing both the fixation of collet nut 40 and the rotation of shaft 18 . Still further, the spring loaded nature of pin 78 ensures locking of collet nut 40 even if not properly oriented at the beginning of a tightening or loosening action, and further ensures that the pin is adequately supported even as pinion shaft 58 is translated from its engaged to its disengaged position.
As is shown in FIG. 6, it may be possible to modify the bit attaching arrangement by providing the collet nut 40 with a bevel gear 50 instead of the nut having slots 46 and by providing shaft 18 with slots 46 instead of gear 50 . In such an embodiment, shaft 58 with pin 78 and pinion gear 54 will operate in the same manner as described above, except that pin 78 will engage slots 46 on the shaft 18 instead of slots on collet nut and pinion gear 54 will engage gear 54 on collet nut 40 instead of a gear surface on shaft 18 . Thus, in this embodiment shaft 18 is held fixed and collet nut 46 is rotated to tighten and loosen a bit.
From the foregoing, it will be seen that this invention is one well-adapted to obtain all the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.
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A bit attaching arrangement for a power tool has a collet nut threadably engaging a rotatably driven shaft of the power tool. The collet nut has a plurality of slots positioned on an outer peripheral surface. A first gear is disposed on the shaft so that rotation of the first gear causes rotation of the shaft. An actuating member having a second gear associated therewith is attached to the housing of the power tool. The actuating member also has a slot-engaging extension associated therewith. The actuating member is positionable between a first position and a second position. In the first position, the second gear engages the first gear and the extension engages one of the slots of the collet nut such that rotation of the actuating member results in rotation of the shaft while maintaining the collet nut at a generally fixed rotational location. In a second position, the first and second gears do not engage one another and the extension does not engage any of the slots of the collet nut such that the shaft can be freely rotated during operation of the power tool.
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BACKGROUND OF THE INVENTION
The present invention relates to a prosthetic implant device, and more particularly to such implants which include a bearing insert or articulation member attached to a base support or reinforcing member. This invention is particularly suitable for use as a tibial component of a knee implant prosthesis, although is not limited thereto.
Heretofore, numerous ways have been utilized to secure an articulating bearing insert to a base support. One such example is U.S. Pat. No. 4,501,031 to McDaniel et al. which discloses a means of molding the articulating surface onto the base support to permanently secure this surface to the base support. Alternatively, it is noted that bearing inserts may be removably attached to a base support as shown in various ways by the following documents. U.S. Pat. No. 3,958,278 to Lee et al. discloses a tibial component which includes a removable E-shaped portion 25 on the base support which enables insertion or removal of the bearing insert 29. U.S. Pat. No. 4,016,606 to Murray et al. discloses a bearing insert which slides into a base support and is then secured by a locking pin inserted through both the insert and support. U.S. Pat. No. 4,207,627 to Cloutier discloses a replaceable bearing insert which has a lip which interlocks with a recess in the base support. U.S. Pat. No. 4,257,129 to Volz discloses a bearing insert which is slidably received onto a base support and then secured by a removable horizontal clip disposed about a removable vertical pin. U.S. Pat. No. 4,470,158 to Pappas et al. discloses a circular snap-ring (see FIGS. 10, 3-5 and 7-9) to unit prosthetic components. Groove 25 in component 11 retains snap-ring 24 when nonmetallic bearing insert 12 is positioned within component 11. The insert 12 can be removed by spreading the ears 23 apart through aperture 22 in component 11. It is noted that the single snap-ring 24 and corresponding grooves substantially fully encircle or surround the components which have circular attachment configurations. European Pat. No. EP 0 032 828 A2 to Lindstrand et al. discloses a bearing portion which is deformable to provide a releasable snap fit connection to the base support.
OBJECTS OF THE INVENTION
A principle object of this invention is to provide a locking mechanism to engage two mating prosthetic components and secure them together in a manner which is simple and convenient.
Another object of the invention is to preferably provide such a locking mechanism which also allows for subsequent separation of the mating components in a simple and convenient manner.
Another object of the invention is to provide a resilient locking clip disposed at one side of the implant extending between the two components to secure the two components together.
A further object of the invention is to provide such a clip which limits its engagement between the two components so that such clip and engagement of the clip does not completely surround the implant components to provide a compact and robust structure.
A still further object of the invention is to provide a locking mechanism which allows for easy insertion (such as with manual finger pressure) of a bearing insert component into a mating base support component.
Another object of the invention is to provide for easy removal of the bearing insert from the base support via a small opening or notch which allows access to the clip, so that the clip can be moved from a locking engagement position to a recessed position allowing removal of the bearing insert.
SUMMARY OF THE INVENTION
The present invention provides a prosthetic implant for replacement of a portion of natural bone at a point of articulation. The implant includes a base support component and a bearing insert which is to be secured thereto, preferably in a removable manner. The implant includes a first side in which a resilient locking clip is predisposed in a first side of one of the two components with the clip being substantially contained to this first side of the implant. The clip protrudes from the first side of the one component in a first position to extend into the first side of the other of the two components, thus causing an interference interlocking between the two components to securely lock the bearing insert to the base support. The clip has a second position in which it does not extend from the one component in which it is predisposed, but is substantially fully receded within this one component. This enables the bearing insert to be inserted and removed from the base support.
The implant further includes a second side which is oppositely located from the first side. The second side includes a lip protruding from one of the two components and a corresponding cavity aligned with the lip in the other of the two components, the lip extends into the cavity for locating engagement therebetween.
The clip preferably has a length which extends around a portion of the periphery of the bearing insert when operatively engaged therewith. This portion is less than half of the overall periphery of the bearing insert.
The bearing insert is easily secured to the base support by first inserting the protruding lip on the second side into the corresponding cavity or groove. Then the first side of the bearing insert may then be lowered toward the base support until the clip which is disposed in one of the two components contacts the other of the two components. The clip is deflected from its first position to its second position enabling the first side of the bearing insert to be inserted onto the base support, thereby fully seating the insert on the base support. The clip then is able to relax back to its first position to extend between the two components to securely lock the bearing insert to the base support.
The bearing insert may subsequently be removed if desired by applying pressure to the clip to cause it to recede into its second position, enabling the first side of the bearing insert to be removed from the base support. The protruding lip on the second side of the implant is then removed from the corresponding cavity, thus separating the insert completely from the base support.
The removable feature of the insert enables the insert to be replaced, if necessary, or enables a choice of bearing inserts to be available for use on the base support having various heights or thicknesses of inserts or providing inserts having a top articularing surface with varying contours. This modularity approach of being able to select from varying inserts to secure the desired insert to a corresponding base support chosen from a possible variety of sizes/styles of base supports designed to mate therewith helps reduce inventory stocking needs. This locking mechanism also enables the implant to be designed to accommodate varying geometries and component cross-sections as desired.
BRIEF DESCRIPTION OF THE DRAWINGS
These features and objects of the invention, as well as others, will become apparent to those skilled in the art by referring to the accompanying drawings:
FIG. 1 is an exploded perspective view of a tibial component for a knee prosthesis in accordance with the present invention;
FIG. 2 is an assembled perspective view of the tibial component of FIG. 1;
FIG. 3 is a side view of the tibial component of FIG. 1 with the bearing insert partially assembled to the base support;
FIG. 4 is a top view of the tibial component of FIG. 1;
FIG. 5 is an enlarged top view of the base support of the tibial component of FIG. 1;
FIG. 6 is a bottom view of the base support of the tibial component of FIG. 1;
FIG. 7 is a side view of the bearing insert of the tibial component of FIG. 1;
FIG. 7a is a partial bottom view of the bearing insert of the tibial component of FIG. 1;
FIG. 7b is an enlarged partial perspective view of one end of the bearing insert of FIG. 1;
FIG. 7c is an enlarged partial side view of one end of the bearing insert FIG. 1;
FIG. 8 is a top view of the bearing insert of the tibial component of FIG. 1;
FIG. 9 is an enlarged top view of the resilient clip of the tibial component of FIG. 1;
FIG. 10 is a cross-sectional view of the tibial component taken along lines 10--10 of FIG. 4;
FIG. 10a is a cross-sectional view of the tibial component taken along lines 10--10 of FIG. 4 with a removal tool shown pressing the clip toward its recessed second position.
FIGS. 11-13 are each enlarged partial cross-sectional views of the tibial component taken along lines 11--11 of FIG. 4, with FIG. 11 showing the initial insertion of the bearing insert with the clip still in its first protruding position, FIG. 12 showing the partially inserted bearing insert pressing the clip into its second recessed position, and FIG. 13 showing the fully inserted/seated bearing insert with the clip returned to its first protruding position providing interlocking between both the bearing insert and the base support.
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1-13 illustrate a particularly advantageous embodiment of a prosthetic implant including a locking mechanism in accordance with the present invention. The invention will be described with reference to a tibial prosthesis, and is particularly suitable as such. However, it is understood that the principles of the invention are suitable for other implants which include two mating interconnecting components such as a base support and a corresponding bearing member.
The prosthetic implant 1 of FIGS. 1 and 2 includes a base support 60, a bearing insert 20 and a resilient clip 40 for securing the bearing insert 20 to the base support 60. The implant 1 includes a first side 8 and a second side 9. The first and second sides 8 and 9 are oppositely located from each other. The base support 60 includes a first side 78 corresponding to the first side 8 of the implant 1. The base support's first side includes a first cavity 64 disposed therein which is substantially contained to the first side 78. The first cavity 64 is appropriately contoured to accept a resilient clip 40 and hold the clip 40 in place in a first position 43 (see FIGS. 11 and 13) in which the clip has a portion which partially protrudes from the first cavity 64 and a second deflected position 44 (see FIG. 12) in which the clip 40 recedes substantially completely into the cavity. The bearing insert 20 includes a first groove 33 in its first side 30 which is aligned with the first cavity 64 such that when the clip 40 is in its first positio 43 and the bearing insert is operatively positioned on the base support 60, the protruding clip portion is engaged in the first groove 33 of the insert 20, thus, securely locking the insert to the base support. See FIG. 13. The groove 33 is above lip 31.
It is noted that the invention is being described with reference to a particularly advantageous embodiment in which the clip is predisposed in the base support 60 and recedes into the base support 60 to allow for insertion and removal of the bearing insert 20. However, it is understood that the principles of the invention are suitable for the clip 40 to be predisposed in the bearing insert 20 to protrude therefrom into the base support 60 and wherein the clip 40 would recede into the insert 20 to allow for insertion and removal of the insert 20. This alternate design is not shown in the Figs.; however, it is noted that the features of the invention are readily adapted to such an alternate embodiment.
The base support 60 includes a second side 79 which corresponds to the second side of the implant 9. The second side 79 is oppositely located from the first side 78. The second side 79 of the support 60 includes a separate second cavity 65 disposed therein. The second side 39 of the bearing insert 20 includes a lip 32 aligned with the second cavity 65 for locating engagement within the second cavity 65. See FIGS. 10 and 10a.
The base support 60 may include a substantially flat platform 61 with a raised rim 62 about the periphery of the platform 61 creating a receptacle area therewithin. The first cavity 64 is disposed in a first side of the rim 62 on the support's first side 78. The bearing insert 20 includes a corresponding substantially flat bottom surface 35 for seating on the platform 61 of the base support 60 within the receptacle area.
The bottom surface 35 of the bearing insert 20 has a shape which substantially corresponds to the receptacle area of the base support 60.
The second cavity 65 is disposed in a second side of the rim 62 on the support's second side 79 oppositely located from the first cavity 64 and first side of the rim 62.
The clip 40 has a chamfered upper surface 42 and the bearing insert 20 has a corresponding chamfered bottom surface 22 to enable the clip 40 to slide from its first position 43 to its second position 44 upon sliding contact between the two chamfered surfaces 42 and 22 upon application of pressure to effect such sliding, thus enabling insertion of the bearing insert. See FIGS. 11-12. Upon full insertion of the bearing, insert 20 the resilient clip 40 returns to its first position 43 to lock the bearing insert 20 to the base support 60. See FIG. 13.
Although the clp 40 could suitably be a straight, resilient member (such a straight embodiment is not shown), it is noted that the resilient clip 40 as shown in the FIGS. is preferably arcuate in shape. See FIG. 9. The arcuate clip 40 has a first end 48 and a second end 49 interconnected by a middle portion 47. The arcuate clip 40 has an overall width "w" which is larger at the middle portion 47 and which becomes progressively thinner toward the first and second ends 48 and 49. In addition, the chamfer 42 on the clip 40 has a width "cw" which is larger at the middle portion 47 of the clip 40 and which width "cw" of the clip's chamfer 42 tapers to substantially zero toward the first and second ends 48 and 49 of the clip 40.
The chamber 22 on the bearing insert 20 has first and second ends 18 and 19 interconnected by a middle portion 17. The chamfer 22 on the insert 20 has a width "bw" which is larger at the middle portion 17 of the bearing insert's chamfer 22 and which width "bw" tapers to substantially zero toward the first and second ends 18 and 19 of the chamfer 22 of the bearing insert 20.
The clip 40 has an overall thickness "t" which is substantially constant throughout the nonchamfered portion of the clip 40.
The above described clip 40 geometry optimizes the strength of the clip 40 for the deflection it is designed to withstand. The tapering of the mating chamfers 42 on the clip and 22 on the insert is significant in that it forces the sliding action between the insert 20 and the clip 40 to occur toward the ends of the clip 40 where the spring is best supported in the first cavity 64 of the base support 60. The sliding action then migrates toward the center as the process of deflecting the clip from its first position 43 to its second position 44. The thicker middle and thinner sides of the chamfers allows the resilient clip 40 to flex, without permanent deformation.
The clip 40 and base support's clip cavity 64 and bearing insert's clip groove 33 are contained to the first side 8 of the implant, and thus do not extend around the whole periphery of the implant 1. The arcuate resilient clip 40 may be a curved circular segment, the segment being less than a semi-circular segment. Preferably, the length of the arcuate segment may be less than one-third of a circular path and potentially less than one-fourth of a circular path. The clip chamfer 42 is located on the inner radius of the circular segment.
In general, the clip 40 has a length which extends around a portion of the periphery of the bearing insert 20 when operatively engaged therewith, the portion being less than half of the overall periphery of the bearing insert 20. This allows for more flexibility in design considerations and sizes by providing a compact and robust locking mechanism. Since the clip cavity 64 and clip groove 33 do not extend substantially around the overall periphery of the implant, less material needs to be taken out for the clip cavity 64 and groove cavity 33. With the resilient clip 40 contained to one side 8 of the implant 1, this allows for great flexibility in implant design considerations. The combination of the lip 32 engaged in the second cavity 65 at the second side 9 of the implant with the resilient clip arrangement 40 at the oppositely located first side 8 provides a secure, yet simple locking mechanism. This arrangement is particularly suitable for a non-circular bearing insert 20 such as is shown in FIG. 8, although it could also be utilized with a circular insert (not shown).
In addition, the bearing insert 20, although not circular, may include a first half 28 and a second half 29 on either side 43 of center line "CL" (see FIG. 8), so that the first half 28 is a mirror image of the second half 29. The particular tibial component shown is for a unicondylar knee replacement in which the two bone condyles of the tibia of a knee are replaced by separate components instead of by one duocondylar tibial component, as is well known in the art. The mirror image of the first half 28 and second half 29 enables the bearing insert 20 shown to be usable on a base support for both the lateral and medial condyles of a tibia. For example, the base support 60 shown in FIG. 5 would be appreciated for a lateral right knee or medial left knee tibial condyle replacement. The mirror image of base support 60 (not shown) would be appropriate for a medial right knee or lateral left knee tibial condyle replacement. The bearing insert 20 shown in FIG. 8 could be utilized in either base support. It is noted that the features of this invention could also be adapted to a duocondylar tibial component (not shown), as well as to other suitable prosthetic implants which have bearing inserts to be secured to a mating base support.
The bearing insert 20 includes a first notch 27 on the first side 38 of the insert 20 which accesses the first groove 33 and enables a removal tool 10 having a thin distal tip 12 to be inserted into the notch 27 and groove 33 between the clip 40 and the bearing insert 20. Application of pressure of the tool 10 on the clip 40 toward the first cavity 64 causes the clip 40 to be translated from its first position 43 to its second position 44 to enable removal of the bearing insert 20 from the base support 60. See FIG. 10a. Upon removal of the first end 38 of the insert 20 from the base support 60, the clip 40 relaxes and returns back to its original first position. As shown in FIG. 7b, the notch 27 may include a larger upper notch portion 27u and a smaller lower notch portion 27L in the lip 31.
A second notch 27 is located on the second side 39 of the bearing insert 20 which accesses a second groove 34 in keeping with the mirror-image of the first and second halves 28 and 29, so that the bearing insert 20 can be used on the mirror image base support (not shown).
It is noted that the first side 78 of the base support 60 is thicker than the second side 79 to provide more room for the first cavity 64 in which the clip 40 is retained. The rim 62 increases in height at rim ramps 66 and 64 as shown in FIG. 5.
The first cavity 64 at the first side 78 of the base support retains the resilient clip therein. The first cavity 64 includes first and second ends 68 and 69. When the clip 40 is in its first posiion 43, the clip ends 48 and 49 are supported thereagainst. The first cavity 64 is deep enough as shown in FIGS. 11-13 to allow the clip 40 to substantially completely recede into the cavity 64. When the clip is in its relaxed first position, the first cavity 64 supports the clip 40 so that approximately a width of about 1 mm extends from cavity 64 into groove 33. (The overall width "w" of such clip may be approximately 2 mm at the middle portion 47.) The first side 78 of the base support includes a plurality of notches 77 which allow some access to the first cavity 64 and which may be utilized to help release the clip 40 from cavity 64 should this be necessary.
The prosthetic implant 1 may utilize any suitable fixation means for securing the base support to the bone. FIG. 6 shows a suitable fixation means on the bottom surface 63 of the base support 60 which includes a protruding flange and two protruding pegs 74. It is understood that any suitable fixation means may be utilized.
Although any suitable implantable materials may be utilized, the base support 60 may advantageously be made from metal such as titanium, the bearing insert 20 from plastic such as ultra high molecular weight polyethylene and the clip 40 from a plastic such as PEEK (polyaryletherketone) or such as Delrin plastic. The material for the clip 40 should be able to withstand deflection without permanent deformation, thus enabling the resilient clip to perform like a spring. Certain metals may also be suitable for such a spring/clip. The spring/clip 40 is preferably retained in the base support 60 in first cavity 64 in its first position 43 in a relaxed position. It is deflected during insertion and then returns to its first relaxed position. This feature virtually eliminates problems of material creep.
The following will describe the method of securing the bearing insert 20 to the base support 60. First, the lip 32 on the second side 39 of the insert 20 is inserted into corresponding second cavity 65 on the second side 9 of the implant 1. The oppositely located first side 38 of the insert 20 is lowered toward the base support 60 as shown in FIG. 3. The bottom chamfered surface 22 of the insert contacts the clip chamfer 42. See FIG. 11. Application of finger pressure is applied to cause the clip to deflect form its first position 43 to its second position 44 in which the clip 40 is substantially receded into the first clip cavity 64. See FIG. 12. The base insert 20 is then fully seated onto the base support 60 so that the first clip groove 33 is aligned with the first clip cavity 64, enabling the clip 40 to relax back to its first position 43 in which a portion of the clip 40 partially protrudes from the clip cavity 64. The clip 40 now extends between both the cavity 64 and the groove 33, thus securely locking the insert to the base support 60. See FIGS. 10 and 13.
In order to remove the insert, should this be desirable, the thin tip 12 of removal tool 10 is inserted into notch 27 between the insert 20 and clip 40. Pressure is applied to clip 40 to cause it to recede into its second position 44. See FIG. 10a. The first side 38 of the insert 20 can then be lifted off or removed from the support 60. Then the lip 32 is removed from the second cavity 65 on the base support 60, thus easily separating the insert 20 completely from support 60.
The locking mechanism for a prosthetic implant as described herein provides for a simple, but effective means for securing a bearing insert to a base support, and preferably provides a simple means for subsequent removal of the insert. While this invention has been described and exemplified in terms of a particularly advantageous embodiment, those skilled in the art can appreciate that modificatios can be made without departing from the spirit and scope of this invention.
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A mechanism and method for locking or securing a bearing insert to the base of a prosthetic implant. The prosthetic implant is for replacement of a portion of natural bone at a point of articulation. The implant includes a locking mechanism which enables the bearing insert to be removably secured to the base support. The locking mechanism includes a resilient locking clip which is predisposed on one side of either the bearing insert or the base support such that when the bearing insert and base support are assembled together, the clip extends between both the insert and the support to secure the two components together. To insert and/or remove the bearing insert from the support, the clip is caused to substantially fully recede into the component in which it is predisposed. The method of securing the insert to the base includes inserting a lip extending from one side of one of the components into a corresponding cavity in the other component. The resilient clip which is located on the opposite side of one of the components is then deflected to enable the bearing insert to be installed onto the base support. The clip then relaxes back into engagement with both the insert and the base creating an interference therebetween to secure the insert to the base support.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application Ser. No. 13/019,639, filed Feb. 2, 2011, and entitled “Bone Plate Having Combination Locking and Compression Screw Holes,” the disclosure of which is expressly incorporated in its entirety herein by this reference.
FIELD OF THE INVENTION
[0002] The present disclosure is directed to bone plates and, more specifically, to bone plates having fastener holes that may be utilized as locking holes or as compression holes, depending upon the initial placement of the fastener with respect to the fastener hole.
BRIEF DISCUSSION OF RELATED ART
[0003] Bone plates used in conjunction with screws to fix bone fractures often contain locking screw holes and compression slots. Locking screw holes provide additional plate-to-screw fixation to lock bone fragments in place and aid in healing of bone fractures. Compression slots, on the other hand, are used to compress the ends of bone fragments together to aid in primary healing.
[0004] Typically, a bone plate includes at least one locking screw hole and at least one compression slot. The location of the holes and slots dictate the locations on the bone plate where the surgeon can apply locking or compression forces.
INTRODUCTION TO THE INVENTION
[0005] The present invention is directed to bone plates having fastener holes that may be utilized as locking holes or as compression holes, depending upon the initial placement of the fastener with respect to the fastener hole. By providing a single hole that can act as a compression hole or a locking hole, the bone plate provides a surgeon with greater flexibility as to the placement of locking fasteners and compression fasteners in a smaller footprint than in a traditional plate having dedicated space for each type of hole.
[0006] It is a first aspect of the present invention to provide a bone plate including a hybrid through screw hole, where the hybrid through screw hole includes a top opening and a bottom opening, the top opening being generally circular and including a widthwise dimension and a lengthwise dimension normal to the widthwise dimension, where an interior wall of the bone plate extends between the top opening and the bottom opening, where at least a portion of the interior wall proximate the top opening is threaded, and where at least one of the widthwise dimension and the lengthwise dimension is decreased between the top opening to the bottom opening, while the other of the widthwise dimension and the lengthwise dimension does not substantially decrease between the top opening and the bottom opening.
[0007] In a more detailed embodiment of the first aspect, the interior wall includes a first portion having a first circumferential curvature and a second portion having a second circumferential curvature, wherein the first circumferential curvature is larger than the second circumferential curvature. In yet another more detailed embodiment, the second portion does not include threads. In a further detailed embodiment, the first portion is at least one of arcuate and tapered in the vertical direction and, the second portion includes a vertical wall. In still a further detailed embodiment, the interior wall includes a first portion having a first circumferential curvature, a second portion having a second circumferential curvature, and a third portion having a third circumferential curvature, wherein the first circumferential curvature is larger than the second circumferential curvature and the third circumferential curvature. In a more detailed embodiment, the second portion is opposite the third portion. In a more detailed embodiment, the second circumferential curvature is generally the same as the third circumferential curvature. In another more detailed embodiment, the first portion includes threads, the second portion does not include threads and, the third portion does not include threads. In yet another more detailed embodiment, the first portion is at least one of arcuate and tapered in the vertical direction, the second portion includes a vertical wall and, the third portion includes a vertical wall.
[0008] It is a second aspect of the present invention to provide a bone plate comprising a combination compression and locking through hole, where the combination hole includes a first portion having a circular, horizontal cross-section and a second portion having an oblong, horizontal cross-section, where the circular, horizontal cross-section and the oblong, horizontal cross-section lie along differing planes perpendicular to a central axis extending through the combination compression and locking through hole.
[0009] In a more detailed embodiment of the second aspect, the bone plate further includes a plurality of combination compression and locking through holes, where each of the plurality of combination compression and locking through holes includes a first portion including a circular, horizontal cross-section and a second portion including an oblong, horizontal cross-section. In yet another more detailed embodiment, the combination compression and locking through hole is at least partially threaded. In a further detailed embodiment, the first portion is threaded and the second portion is unthreaded. In still a further detailed embodiment, the first portion includes a diameter D, the second portion includes a maximum length L and, the diameter D is approximately equal to the length L.
[0010] It is a third aspect of the present invention to provide a bone plate comprising a through screw hole demarcated by an interior surface of the bone plate that extends between a top opening and a bottom opening, the top opening having a continuous arcuate shape and allowing throughput of a first imaginary cylinder having a circular cross-section with a diameter D 1 , the interior surface having a first segment that is at least partially threaded and tapers to a stopping distance SD to inhibit throughput of the first imaginary cylinder at a location between the top opening and the bottom opening, the interior surface having a second segment adjacent to the first segment, the first segment and the second segment allowing throughput of a second imaginary cylinder having a circular cross-section with a diameter D 2 , where the diameter D 1 is greater than the diameter D 2 , where the stopping distance SD is greater than D 2 , and wherein a maximum horizontal distance across the second segment is greater than 1.3 times D 2 .
[0011] In a more detailed embodiment of the third aspect, the interior surface of the first segment includes a first circumferential curvature and the second segment includes a second circumferential curvature, wherein the first circumferential curvature is larger than the second circumferential curvature. In yet another more detailed embodiment, the second segment does not include threads. In a further detailed embodiment, the first segment is at least one of arcuate and tapered in the vertical direction and, the second segment includes a vertical wall. In still a further detailed embodiment, the interior surface includes a first segment having a first circumferential curvature, the second segment includes a second portion having a second circumferential curvature and a third portion having a third circumferential curvature, wherein the first circumferential curvature is larger than the second circumferential curvature and the third circumferential curvature. In a more detailed embodiment, the second portion lies generally opposite the third portion. In a more detailed embodiment, the second circumferential curvature is generally the same as the third circumferential curvature. In another more detailed embodiment, the first portion includes threads, the second portion does not include threads and, the third portion does not include threads. In yet another more detailed embodiment, the first portion is at least one of arcuate and tapered in the vertical direction, the second portion includes a vertical wall and, the third portion includes a vertical wall.
[0012] It is a fourth aspect of the present invention to provide a method of forming a bone plate comprising: (a) fabricating a bone plate to include a first through hole, where at least one of a width and a length of the hole changes along a depth of the hole; (b) plunge milling an interior surface of the bone plate demarcating the first through hole to remove at least a portion of the bone plate to increase at least one of the width and the length of the through hole; and (c) threading at least a portion of the first through hole.
[0013] In a more detailed embodiment of the fourth aspect, threading at least a portion of the first through hole occurs before the plunge milling act. In yet another more detailed embodiment, threading at least a portion of the first through hole occurs after the plunge milling act. In a further detailed embodiment, the length and width of the through hole at a top surface of the bone plate are identical. In still a further detailed embodiment, the length and width of the through hole at a bottom surface of the bone plate are identical after the fabricating act and, the length and width of the through hole at the bottom surface of the bone plate are not identical after the plunge milling act. In a more detailed embodiment, the plunge milling act includes using an end mill to remove material in a cylindrical swath, a first axis extends through a center of the through hole, a second axis extends through a circular center of the cylindrical swath and, the first axis is parallel with the second axis. In a more detailed embodiment, the plunge milling act includes using an end mill to remove material in a cylindrical swath, the plunge milling act includes applying the cylindrical swath to opposing ends of the through hole to create a first cylindrical swath and a second cylindrical swath, the first cylindrical swath includes a first axis extending through a circular center thereof, the second cylindrical swath includes a second axis extending through a circular center thereof, the first axis is parallel with the second axis and, the first axis is offset from the second axis.
[0014] It is a fifth aspect of the present invention to provide a method of forming a bone plate comprising fabricating a bone plate to include a combination compression and locking hole, where the combination compression and locking hole includes a first portion having a circular cross-section and a second portion having an oblong cross-section, where the circular cross-section and the oblong cross-section lie along differing planes perpendicular to a central axis extending through the combination compression and locking hole.
[0015] In yet another more detailed embodiment of the fifth aspect, the fabricating step includes machining a bone plate from a solid block of material. In still another more detailed embodiment, a first portion of the hole tapers to reduce a cross-sectional area of the hole. In a further detailed embodiment, the fabricating step includes forming threads within an interior surface of the bone plate demarcating the hole. In still a further detailed embodiment, the fabricating step includes removing some of the bone plate to increase at least one of a width and a length of the hole after the hole has been formed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is an elevated perspective view of an exemplary bone plate incorporating at least one combination locking and compression screw hole.
[0017] FIG. 2 is an overhead view of the exemplary combination locking and compression screw hole shown in FIG. 1 .
[0018] FIG. 3 is a cross-sectional view taken along line C in FIG. 2 .
[0019] FIG. 4 is a cross-sectional view taken along line B in FIG. 2 .
[0020] FIG. 5 is an overhead view of a locking screw hole while a portion is bored out using an end mill.
[0021] FIG. 6 is an overhead view of the locking screw hole of FIG. 5 , with an opposing portion being bored out using an end mill to form the combination locking and compression screw hole.
[0022] FIG. 7 is an elevated perspective view of an exemplary locking screw.
[0023] FIG. 8 is a vertical cross-section of the exemplary locking screw of FIG. 7 taken at the middle.
[0024] FIG. 9 is an elevated perspective view of an exemplary compression screw.
[0025] FIG. 10 is a vertical cross-section of the exemplary compression screw of FIG. 9 taken at the middle.
[0026] FIG. 11 is a vertical cross-section of the exemplary bone plate of FIG. 1 in position with respect to a bone, where a compression screw is partially inserted into the combination locking and compression screw hole.
[0027] FIG. 12 is a vertical cross-section of the exemplary bone plate of FIG. 1 in position with respect to a bone, where a compression screw is fully inserted into the combination locking and compression screw hole in order to shift the position of the plate and compress the bone.
[0028] FIG. 13 is a vertical cross-section of the exemplary bone plate of FIG. 1 in position with respect to a bone, where a locking screw is partially inserted into the combination locking and compression screw hole.
[0029] FIG. 14 is a vertical cross-section of the exemplary bone plate of FIG. 1 in position with respect to a bone, where a locking screw is fully inserted into the combination locking and compression screw hole in order to lock the angular position of the screw with respect to the plate and bone.
DETAILED DESCRIPTION
[0030] The exemplary embodiments of the present disclosure are described and illustrated below to encompass bone plates and, more specifically, to bone plates having fastener holes that may be utilized as locking holes or as compression holes, depending upon the initial placement of the fastener with respect to the fastener hole. Of course, it will be apparent to those of ordinary skill in the art that the preferred embodiments discussed below are exemplary in nature and may be reconfigured without departing from the scope and spirit of the present invention. However, for clarity and precision, the exemplary embodiments as discussed below may include optional steps, methods, and features that one of ordinary skill should recognize as not being a requisite to fall within the scope of the present invention.
[0031] Referencing FIG. 1 , an exemplary bone plate 100 comprises a clavicle bone plate. This clavicle bone plate 100 includes an elongated, longitudinal dimension that includes a series of fastener holes 102 , 103 , 102 A distributed in a spaced-apart fashion along the longitudinal length. Each fastener hole 102 , 103 , 102 A extends between the top surface 104 and bottom surface 106 . In this exemplary embodiment, the top surface 104 is generally convex from superior to inferior, while the bottom surface 106 is generally concave from superior to inferior. This shape is operative to form a channel defined by the bottom surface 106 that is adapted to receive a biologic substrate, such as bone. And each fastener hole 102 , 103 , 102 A is generally centered between a superior side 108 and an inferior side 110 .
[0032] In this exemplary embodiment, the fastener holes 102 , 103 , 102 A generally take on three forms. A first form hole 102 includes a generally circular through opening that extends between the top and bottom surfaces 104 , 106 . This first form hole 102 has a horizontal circular cross-section that changes in diameter in order to provide a taper in the hole, with the taper being located proximate the bottom surface. It should be noted, however, that wherever a horizontal cross-section of this first hole 102 is taken, the cross-section will be circular. In order to form this hole, a milling machine (not shown) uses an end mill to remove material from the bone plate in order to form the interior wall that defines the through hole. As part of this first form hole 102 , the milling machine removes material from the hole to create a taper from top to bottom so that the area of the horizontal, circular cross-sections at some point between the top and bottom decreases. After the milling machine has formed the hole, the wall of the hole is relatively smooth. Thereafter, a threading procedure is carried out to form threads on the interior of the hole 102 . These threads, however, do not generally change the circular cross-section of the hole. But the second form hole 103 does not include a horizontal circular cross-section.
[0033] In contrast to the first hole 102 , the second form hole 103 includes an elongated shape having a non-circular cross-section. By way of example, the second form hole 103 includes a longitudinal dimension that is greater than a widthwise dimension (superior to inferior). At the top of the second form hole 103 , proximate the top surface 104 , the longitudinal dimension accommodates multiple longitudinal positions for a screw (such as a locking screw 180 or a compression screw 210 ). But the widthwise dimension is generally uniform and allows for positioning of the screw in only a single widthwise position. In other words, the second form hole 103 allows for positioning the screw in a number of longitudinal positions, but the position of the screw in the superior-to-inferior (i.e., widthwise) direction is generally not amendable to multiple positions. Similarly, the first form hole 102 does not allow for multiple positions of the screw in the inferior-to-superior direction. But, conversely to the second form hole 103 , the first form hole 102 fails to allow multiple positions of the screw in the longitudinal direction.
[0034] The two screw form holes 102 , 103 also differ in that the first form hole 102 is threaded, while the second form hole 103 is not threaded. In order to retain the screw within the second form hole 103 , a circumferential flange 140 (recessed in between the top and bottom surfaces 104 , 106 ) extends into the hole and is operative to decrease the through hole diameter enough so that throughput of the screw head is retarded. Because of the longitudinal position variance provided by the second form hole 103 , compression screws 210 are more commonly inserted into this hole, as opposed to locking screws 180 . As would be expected, the threaded nature of the first form hole 102 results in locking screws 180 being inserted into these holes more commonly than compression screws 210 .
[0035] A third form hole 102 A comprises a hybrid hole that may be utilized as a locking screw hole or as a compression screw hole. In exemplary form, the hybrid fastener hole 102 A includes a circular cross-section at the top surface 104 and an oblong cross-section at the bottom surface 106 . More specifically, the oblong cross-section of the hole 102 A at the bottom surface 106 includes a first, larger dimension 112 running longitudinally along the longitudinal dimension of the hole 102 A, and a second, smaller dimension 114 running inferiorly between the superior and inferior sides 108 , 110 . It should be noted that the larger dimension 112 is approximately the same as the diameter of the hole 102 A at the top surface 104 . In this exemplary embodiment, the larger dimension 112 is 0.205 inches, while the smaller dimension is 0.145 inches. Those skilled in the art will understand that differing dimensions (greater or lesser) are well within the scope of the invention.
[0036] Located between the top and bottom surfaces 104 , 106 for the first and third form holes 102 , 102 A are helical threads 120 that extend from portions of an interior wall 122 to delineate the vertical cross-section of each hole 102 A. The interior wall 122 takes on a general shape that resembles a bowl or a frustum, where portions of the interior wall 122 departing from the bowl or frustum shape may not include the helical threads 120 .
[0037] An exterior of the bone plate 100 includes a number of indentations 130 that are formed into the superior and inferior sides 108 , 110 . Each indentation 130 is located opposite another indentation so that a pair of indentations generally interposes consecutive fastener holes 102 , 102 A. In this exemplary embodiment, each indentation 130 operates to decrease the widthwise dimension (superior 108 to inferior 110 ) of the bone plate 100 , while at the same time cooperating with arcuate depressions 132 to decrease the thickness (top surface 104 to bottom surface 106 ) of the bone plate. Specifically, the arcuate depressions 132 extend along the top surface 104 and terminate just shy of the superior-inferior midline extending longitudinally along the length of the bone plate 100 .
[0038] To fabricate the exemplary bone plate 100 , a solid block of metal (e.g., stainless steel, titanium, etc.) is milled to form the general shape of the bone plate. This includes milling the bone plate 100 to have the requisite length, width, and thickness, in addition to providing a top surface 104 that is convex and a bottom surface 106 that is concave along the longitudinal length. In addition, the milling is operative to form the indentations 130 and remove material from the bone plate 100 in order to form the depressions 132 . After the general shape of the bone plate is finished, the fastener holes of the first and second form 102 , 103 are formed through the bone plate 100 .
[0039] Referring to FIGS. 5 and 6 , in order to form the hybrid holes 102 A, an additional step is taken to modify one or more of the first form holes 102 . Specifically, a milling machine is utilized to carry out a plunge down operation on the first form hole 102 that removes a portion of the internal threads and interior wall in the longitudinal direction to create an oblong opening at the bottom of the hole. As discussed previously, the first form hole 102 has a diameter of 0.205 inches (and a circumferential curvature that matches this 0.205 inch diameter) at the top surface 104 and a diameter of 0.145 inches at the bottom surface 106 prior to the plunge down operation. After the plunge down operation is complete, the diameter of 0.205 inches at the top surface 104 remains unchanged, while the longitudinal dimension of the hole at the bottom surface 106 is changed to create an oblong shape. Specifically, the plunge down operation creates an oblong hole at the bottom surface 106 having a longitudinal dimension of 0.205 inches, while maintaining the widthwise dimension of 0.145 inches.
[0040] The plunge down operation involves using an end mill 150 having an outside diameter of 0.138 inches, where the end mill is oriented in parallel to the through axial center of the hole and is longitudinally offset 0.03 inches from this axial center, but is centered in the superior-to-inferior direction. In a first plunge down operation (see FIG. 5 ), the end mill 150 is longitudinally offset 0.03 inches in the proximal direction and removes a portion of the interior surface to create a wall having a circumferential curvature of a circle having a diameter of 0.138 inches. In a second plunge down operation, the end mill 150 is longitudinally offset 0.03 inches in the distal direction (see FIG. 6 ) and removes another portion of the interior surface to create another wall having a circumferential curvature of a circle having a diameter of 0.138 inches. The result of the plunge down operation is a hole 102 A having hybrid characteristics to accept either a locking or compression screw 180 , 210 without sacrificing the functionality of a locking screw or the functionality of a compression screw.
[0041] Referring to FIGS. 7 and 8 , an exemplary locking screw 180 includes a head 182 and a shaft 184 extending from the head. The head 182 comprises a dome 186 that transitions into an arcuate circumferential surface 188 that includes helical threads 190 adapted to engage the threads 120 of the bone plate holes 102 , 102 A. The circumferential surface 188 transitions into an underneath planar surface 192 at the bottom of the head 182 to take on a frustum profile. Opposite the bottom of the head 182 is an opening 194 formed at the apex of the dome 186 . The opening 194 extends through the head 182 and into a head end 196 of the shaft 184 . In exemplary form, the opening 194 is defined by a series of six alternating semicircular walls 198 and six straight walls 200 that form a hexagonal pattern. At the base of the walls 198 , 200 is a conical wall 202 that defines a conical part of the opening 194 terminating in the head end 196 of the shaft 184 . An exterior surface 204 of the shaft 184 includes helical threads 206 that are adapted to engage a biologic substrate (not shown), such as bone. The threads 206 extend along the shaft until reaching a pointed projection 208 at a far end of the screw 180 .
[0042] Referencing FIGS. 9 and 10 , an exemplary compression screw 210 includes a head 212 and a shaft 214 extending from the head. The head 212 includes a dome 215 that transitions into a rounded or tapered circumferential surface 216 that operates to decrease the cross-section of the head from proximal to distal, where the distal aspect transitions into the shaft. Extending through the dome 215 is an opening 218 that extends through the head 212 and into a head end 220 of the shaft 214 . In exemplary form, the opening 218 is defined by a series of six alternating semicircular walls 220 and six straight walls 222 that form a hexagonal pattern. At the base of the walls 220 , 222 is a conical wall 224 that defines a conical part of the opening 218 terminating in the head end 220 of the shaft 214 . An exterior surface 226 of the shaft 214 includes helical threads 228 that are adapted to engage a biologic substrate (not shown), such as bone. The threads 228 extend along the shaft 214 until reaching a tapered projection 230 at a far end of the screw 210 .
[0043] Referring to FIGS. 11 and 12 , the hybrid holes 102 A of the exemplary bone plate 100 may be utilized to receive a compression screw 210 in order to exert a compressive force on the bone 240 . In exemplary form, a bone or bone fragments 240 is mounted to the bone plate 100 using a combination of compression and locking screws 210 , 180 . Presuming a surgeon finds it desirable to provide compression using the hybrid hole 102 A, a pilot hole may be drilled to receive a compression screw 210 . By way of example, the pilot hole is offset distally with respect the axial center of the hole 102 A, which allows for the compression screw 210 to be axially offset from the center of the hole (see FIG. 11 ). When the compression screw 210 is initially inserted, the smaller diameter threaded shaft 214 is aligned with the pilot hole and extends through the hybrid hole 102 A with the shaft contacting, but not actively engaging the threads on the side of the hole 102 A. A pair of reference lines 242 , 244 denotes the position of the bone 240 with respect to the bone plate 100 prior to compression. As the screw 210 is inserted farther into the bone 240 , the circumferential surface 216 of the head 212 initially comes in contact with the top of the hole 102 A.
[0044] When the circumferential surface 216 of the head 212 comes in contact with the top of the hole 102 A, further insertion of the head is operative to push the head against the distal wall of the hole. This causes the position of the bone plate 100 to shift distally with respect to the bone 240 , thereby creating a compressive force on the bone in the distal direction. As can be seen in FIG. 12 , the reference lines 242 , 244 are no longer aligned, as the reference mark 242 for the plate 100 has shifted distally with respect to the reference mark for the bone 240 .
[0045] Referring to FIGS. 13 and 14 , the hybrid holes 102 A of the exemplary bone plate 100 may be utilized to receive a locking screw 180 , such as a variable angle locking screw, in order fix the position of the bone plate 100 with respect to the bone 240 where screw angles other than perpendicular may be desired. In exemplary form, a bone or bone fragments 240 is mounted to the bone plate 100 using a combination of compression and locking screws 210 , 180 . Presuming a surgeon finds it desirable to mount the plate 100 to the bone 240 using a locking screw at an angle other than perpendicular (perpendicular could also be used as well), a pilot hole may be initially drilled. By way of example, the pilot hole is angled based upon the orientation of the bone or bone fragments 240 . After the hole is drilled, a locking screw 180 is inserted through the hole 102 A so that the smaller diameter threaded shaft 184 is aligned with the pilot hole. Thereafter, the locking screw 180 is rotated to fasten the screw to the bone 240 , while at the same time pulling the head 182 into contact with the bounds of the hole 102 A. Specifically, the threads 190 of the screw head 182 engage the threads 120 on the interior of the hole 102 A in order to lock the angular position of the screw head (and screw) with respect to the bone plate 100 .
[0046] It should be noted that the dimensions set forth for the exemplary embodiments are just that, exemplary. Deviations from these dimensions may be made without departing from the scope and spirit of the instant disclosure. For example, the holes 102 may have an upper diameter larger or smaller than 0.205 inches. Likewise, the holes may not necessarily have a circular cross-section at any point. Moreover, the holes may generally take on any dimensions that provides for dual functionality and use as both a compression hole and a locking hole.
[0047] Following from the above description and invention summaries, it should be apparent to those of ordinary skill in the art that, while the methods and apparatuses herein described constitute exemplary embodiments of the present invention, the invention contained herein is not limited to this precise embodiment and that changes may be made to such embodiments without departing from the scope of the invention as defined by the claims. Additionally, it is to be understood that the invention is defined by the claims and it is not intended that any limitations or elements describing the exemplary embodiments set forth herein are to be incorporated into the interpretation of any claim element unless such limitation or element is explicitly stated. Likewise, it is to be understood that it is not necessary to meet any or all of the identified advantages or objects of the invention disclosed herein in order to fall within the scope of any claims, since the invention is defined by the claims and since inherent and/or unforeseen advantages of the present invention may exist even though they may not have been explicitly discussed herein.
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A method of forming a bone plate comprising fabricating a bone plate to include a first through hole, where at least one of a width and a length of the hole changes along a depth of the hole; plunge milling an interior surface of the bone plate demarcating the first through hole to remove at least a portion of the bone plate to increase at least one of the width and the length of the through hole; and, threading at least a portion of the first through hole.
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BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to gas turbine engines and, more particularly, to rotor disks of such engines.
[0003] 2. Background Art
[0004] Fan rotors can be manufactured integrally or as an assembly of blades around a disk. In the case where the rotor is assembled, the fixation between each blade and the disk has to provide retention against extremely high radial loads. This in turn causes high radial stress in the disk retaining the blades.
[0005] In the case of “swept” fans, the blades are asymmetric with respect to their redial axis. A significant portion of the weight of these blades is cantilevered over the front portion of the fixation, which causes an uneven axial distribution of the radial load on the fixation and disk. This load distribution causes high local radial stress in the front of the disk and high contact forces between the blade and the front of the disk.
[0006] Although a number of solutions have been provided to even axial distribution of stress in blades, such as grooves in blade platforms to alleviate thermal and/or mechanical stresses, these solutions do not address the problem of high local radial stress in the disk supporting the blades.
[0007] Accordingly, there is a need for a disk for a gas turbine engine fan having a smoother axial distribution of radial stress.
SUMMARY OF INVENTION
[0008] It is therefore an aim of the present invention to provide an improved rotor disk for a gas turbine engine.
[0009] It is also an aim of the present invention to provide a method for smoothing an axial distribution of radial stress in a rotor disk.
[0010] Therefore, in accordance with a general aspect of the present invention, there is provided a gas turbine engine rotor disk comprising a disk body having a plurality of blade attachment slots circumferentially distributed about a periphery thereof, and wherein an undercut is provided radially inwardly of said blade attachment slots.
[0011] In accordance with a further general aspect of the present invention, there is provided a gas turbine engine rotor comprising a plurality of blades, each of said blades having a root received in a corresponding blade attachment slot defined in a disk adapted to be mounted for rotation about an axis, and wherein an axial distribution of radial stress in the disk is smoothed by providing an undercut in the disk radially inwardly of the blade attachment slots.
[0012] In accordance with a still further general aspect of the present invention, there is provided a method to smooth out an uneven axial distribution of radial stress in a gas turbine engine rotor disk having a plurality of blade attachment slots in which are retained a corresponding number of blades, the method comprising the step of: providing an undercut radially inwardly of said plurality of blade attachment slots.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Reference will now be made to the accompanying drawings, showing by way of illustration a preferred embodiment of the present invention and in which:
[0014] FIG. 1 is a side view of a gas turbine engine, in partial cross-section; and
[0015] FIG. 2 is a partial side view of a fan, in cross-section, showing a disk according to a preferred embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] FIG. 1 illustrates a gas turbine engine 10 of a type preferably provided for use in subsonic flight, generally comprising in serial flow communication a fan 12 through which ambient air is propelled, a multistage compressor 14 for pressurizing the air, a combustor 16 in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section 18 for extracting energy from the combustion gases.
[0017] Referring to FIG. 2 , part of the fan 12 , which is a “swept” fan, is illustrated. Although the present invention applies advantageously to such fans, it is to be understood is can also be used with other types of radial fans, as well as other types of rotating equipment having a disk requiring a smoother axial distribution of radial stress including, but not limited to, compressor and turbine rotors.
[0018] The fan 12 includes a disk 30 mounted on a rotating shaft 31 and supporting a plurality of blades 32 which are asymmetric with respect to their radial axis. Each blade 32 comprises an airfoil portion 34 including a leading edge 36 in the front and a trailing edge 38 in the back. The airfoil portion 34 extends radially outwardly from a platform 40 . A blade root 42 extends from the platform 40 , opposite the airfoil portion 34 , such as to connect the blade 32 to the disk 10 . The blade root 42 includes an axially extending dovetail 44 , which is designed to engage a corresponding dovetail groove 46 in the disk 30 . Other types of attachments can replace the dovetail 44 and dovetail groove 46 , such as a bottom root profile commonly known as “fir tree” engaging a similarly shaped blade attachment slot in the disk 10 . The airfoil section 34 , platform 40 and root 42 are preferably integral with one another.
[0019] As stated above, the asymmetry of the blade 32 cause a significant portion of the blade weight to be cantilevered over the front portion of the dovetail 44 . This creates an uneven axial distribution of the radial load on the dovetail 44 and disk 30 . Such a load distribution produces unacceptably high local radial stress in the front of the disk 30 and contact forces between the dovetail 44 and the front of the dovetail groove 46 .
[0020] According to an embodiment of the present invention, the axial distribution of the radial stresses in the disk 30 is smoothed by way of a continuous annular undercut 50 provided in the front of the disk 30 , radially inwardly of the dovetail groove 46 . The undercut 50 is preferably rounded and generally slightly curved toward the rotating shaft 31 .
[0021] Although a number of different geometries are possible for the undercut 50 , the geometry must be carefully selected in order to produce a favorable change in the load path of the disk 30 . For example, in the case of a “swept” fan, a simple straight undercut will lower the stress at the leading edge of the disk but cause a sharp peak further back, which is undesirable. By contrast, the undercut 50 having the geometry shown in FIG. 2 will produce a radial stress having a maximum generally constant value along a significant middle portion of the disk 30 , with a generally progressively lower value toward both the leading and trailing edge of the disk. A preferred way of determining the appropriate undercut geometry is through 3D finite element analysis according to methods well known in the art.
[0022] The undercut 50 thus eliminates the unacceptably high local radial stress in the front of the disk 30 and contact forces between the dovetail 44 and the front of the dovetail groove 46 by evening the axial distribution of the radial stresses in the disk 30 .
[0023] The undercut 50 , among other things, allows for a simple way to balance the axial distribution of radial stress in a disk of a “swept” fan, as well as in other types of disks requiring similar balancing of the axial distribution of radial stress.
[0024] The embodiments of the invention described above are intended to be exemplary. Those skilled in the art will therefore appreciate that the foregoing description is illustrative only, and that various alternatives and modifications can be devised without departing from the spirit of the present invention. Accordingly, the present is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.
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An undercut is provided in a gas turbine engine disk to smooth out an uneven axial distribution of radial stress in the disk. The undercut is defined radially inwardly of the blade attachment slots provided at the periphery of the disk.
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RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional Application No. 60/481,103 filed Jul. 17, 2003, the entire disclosure of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] Commercially available pipe typically is manufactured to a nominal outer diameter which varies plus and minus depending on the tolerance range. Collets are used to hold or clamp pipes during, for example, welding of the pipes. Welding can be accomplished with, for example, an orbital weld head of the type shown generally in U.S. Pat. No. 4,379,215, the entire disclosure of which is hereby incorporated by reference. A collet for a given pipe size needs to provide enough compliance to securely hold pipes that have a size anywhere within the given tolerance range for that pipe size. The collet typically must fit certain space constraints. Some prior art pipe collet designs use integrally machined components to provide spring-like compliance, but these designs can be inconsistent and relatively expensive, and can require mating collet components that also are relatively expensive.
[0003] The use of rigid collets for holding the pipe during the welding operation is much preferred as compared to split and/or adjustable collets or similar holding devices. The reason for this is that during the welding operation, thermal stresses tend to cause the pipe to move creating misalignment between the two sections. The movement is greater and/or more likely to happen with the split collets and the adjustable collets or holders. With respect to the solid or rigid collets, however, there are problems in assuring that pipe throughout the range of standard commercial tolerances can be held properly. That is, a typical commercially available pipe used for fluid systems and the like, has, for example, a nominal outside diameter of 3.000 inches which varies ±0.030 inches. It has been difficult to compensate for the diameter variations which result from the tolerance variations and, at times, it has been difficult to properly hold the pipe during the welding operation. Also it has at times been difficult to hold out of round pipes or tubes in the proper position relative to the weld head.
[0004] Some prior art pipe collets, designed to accommodate a significant amount of size variation, use a series of slots that are cut into the base collet material to form resilient fingers. The slots can be cut either radially outward from the theoretical center of the object to be held, or they can be cut tangentially with respect to that theoretical center. The geometry of these slots enable the collet fingers to flex, or bend, in response to the geometry of the pipe that is being clamped within the collet. Where a large amount of compliance is not required, the collets can be left solid, that is, without machined slots. Some manufacturers cut the inside diameters of these collets on the true center of the collet, and some manufacturers offset the ID cut.
SUMMARY OF THE INVENTION
[0005] The present invention relates to work holders and, more particularly, to a collet for holding cylindrical workpieces in alignment with an axis of the collet. The invention is especially suited for use in a pipe clamp for association with an orbital welder and will be described with particular reference thereto. The invention is, however, capable of broader application and could be incorporated in a wide variety of work holders and clamping units for different types of work pieces and tools. For example, the invention may be used with a facing or other finishing tool. The invention may also be used with tubes in addition to pipes, although commercially available tube collets are often sufficient to accommodate the tolerance variation in tube sections.
[0006] In one embodiment, the invention relates to a collet for holding a workpiece having an axis. The collet includes a collet base defining a collet axis. A plurality of contact points that are not integral with the collet base are supported on the collet base for movement relative to the collet base in directions generally toward and away from the collet axis. The collet is self-aligning whereby the contact points help to align the workpiece coaxially with the collet base.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The foregoing and other features of the invention will become apparent from the following description when read in conjunction with the accompanying drawings wherein:
[0008] FIG. 1 is a pictorial view of a pipe clamping fixture including two collets that are a first embodiment of the invention;
[0009] FIG. 2 is an elevational view of a portion of the fixture of FIG. 1 showing the two collets in a closed condition;
[0010] FIGS. 3-5 are views similar to FIG. 2 showing the two collets in a condition clamping pipes of different sizes;
[0011] FIG. 6 is an exploded sectional view of parts of one plunger;
[0012] FIG. 7 is a sectional view of a portion of one collet with a plunger shown in a first position;
[0013] FIG. 8 is a view similar to FIG. 7 showing the plunger shown in a second position;
[0014] FIG. 9 is an exploded perspective view of one collet;
[0015] FIG. 10 is a schematic view of a collet that is another embodiment of the invention;
[0016] FIGS. 11-13 are a series of views of a collet that is another embodiment of the invention; and
[0017] FIGS. 14-15 illustrate another clamping fixture in accordance with the invention.
DETAILED DESCRIPTION
[0018] FIG. 1 shows a pipe clamp fixture 10 which is intended to be used with an orbital welding head. The fixture 10 is designed to hold two pipe sections in aligned relationship with their facing ends abutting so that an electrode of an orbital welding head (for example as shown schematically at 11 ) can rotate about the mating pipe ends to perform a butt weld operation.
[0019] The pipe clamp fixture 10 includes a pair of clamping units 12 and 14 which are joined to opposite sides of an intermediate spacer 16 . The various components are formed from stainless steel, aluminum, or the like and the clamp units 12 and 14 are removably joined to the spacer 16 in any convenient manner such as through the use of machine screws. The clamp units 12 and 14 are joined to the spacer 16 to form a somewhat U-shaped structure with an open welding space 20 adapted to receive the orbital welding head 11 . The fixture 10 may if desired be secured to the welding head 11 by screws, for example.
[0020] In the illustrated embodiment, the clamping units 12 and 14 are of identical construction except that they are mirror images of one another. Therefore, only the clamp unit 14 is described herein.
[0021] As best shown in FIGS. 2 and 3 , the clamp unit 14 comprises a pair of opposed clamp halves 22 and 24 . The clamp halves 22 and 24 are connected with each other by a hinge or hinge mechanism which permits the clamp halves to be moved toward and away from one another between a closed position as shown in FIGS. 1 and 2 and an open position (not shown). The two clamp halves 22 and 24 are releasably connected in their engaged or clamping position by a releasable latch or lock fixture such as the one shown at 28 .
[0022] Each one of the clamp halves 22 and 24 carries a collet 30 . The collets 30 cooperate to define a circular work piece clamping opening 32 ( FIG. 2 ) that is centered on an axis 34 . The collets 30 of the two clamp halves 22 and 24 are identical to each other. The clamp halves 22 and 24 together form a collet holder that holds the two collets 30 .
[0023] Each collet 30 includes a collet base 40 . The collet base 40 as illustrated is a rigid metal member that is secured to the clamp half 22 by a pair of mounting screws (not shown). The collet base 40 has a circumferential extent of about 180 degrees about the axis 34 . The collet base 40 has a cylindrical inner surface or base surface 44 centered on the axis 34 .
[0024] The collet base 40 has one or more plunger openings 46 . The plunger openings are spaces or cavities or chambers or recesses that receive and guide contact points 60 and springs 80 , as described below. The contact points 60 are the portions of the collet 30 that actually contact the workpiece. The contact points 60 are formed separately from and are not integral with the collet base 40 .
[0025] In the illustrated embodiment, the collet base 40 has two plunger openings in the form of recesses 46 . The plunger openings 46 are formed in the base surface 44 of the collet base 40 and extend radially outward.
[0026] Each plunger opening 46 is defined by a cylindrical side surface 48 and a circular bottom end surface 50 both centered on a radially extending plunger axis 52 . A threaded bore 54 extends from the plunger opening 46 . Associated with each plunger opening 46 is a locking screw opening 56 that extends transverse to the bore 54 and that intersects the bore near its bottom end. In the illustrated embodiment, two plunger openings 46 are provided, spaced ninety degrees apart about the axis 34 . A different number of plunger openings 46 could be provided, and different spacing could be provided between the openings. The plunger openings could alternatively be formed or configured in another manner—for example, they might not need to be recessed from the base surface 44 .
[0027] Disposed within each one of the plunger openings 46 is a plunger assembly 58 ( FIG. 6 ). The plunger assembly 58 includes a contact point or plunger 60 ; a mounting screw 70 ; and spring 80 .
[0028] The plunger 60 is a movable member or contact point that) (together with the other plungers 60 ) forms that portion of the collet 30 which the workpiece contacts. The plunger 60 is movable relative to the collet base and to the axis 34 , as described below. The plunger 60 is formed separately from and is not integral with the collet base 40 .
[0029] The plunger 60 in the illustrated embodiment is an open-ended, hollow cylindrical member adapted to fit closely within the plunger opening 46 . The plunger 60 is preferably made from 416 stainless steel, and has a hardness of 36 to 42 on the Rockwell C scale. Parts that are of this hardness have acceptable wear characteristics without being so hard that they would be brittle. The invention is not limited, however, to any particular material for the plungers.
[0030] The plunger 60 has a cylindrical side wall 62 that defines a central opening 64 centered on the axis. The side wall 64 has an annular top end surface 66 and an annular bottom end surface 68 . The plunger 60 has a bottom flange 69 that extends radially inward from the side wall 62 to narrow the central opening 64 at the bottom (radially outer) end of the plunger.
[0031] The mounting screw 70 is an element or assembly that retains the plunger 60 in the plunger opening 46 , that is, that keeps the plunger from moving radially inward past a certain position. In the illustrated embodiment, the retaining screw 70 is a socket head screw with a head 72 and a threaded shank 74 . The head 72 of the retaining screw 70 is smaller in diameter than the central opening 64 of the plunger 60 , but larger in diameter than the bottom flange 69 of the plunger.
[0032] The spring 80 is an element or assembly that biases the plunger 60 radially inward in a direction along the plunger axis 52 . In the illustrated embodiment, the spring 60 is a stack 82 of Belleville washers 84 . Other types of springs 80 could be used, for example, a compression spring. Thus, the term “spring” when used herein could refer to a single member that provides a biasing force or to a plurality of members or elements that act together to provide a biasing force. For example, a coil spring 80 could provide adequate compliance and loading, but not necessarily within the same small space as the Belleville washers 84 . Polymer (as opposed to metal) springs 80 might also be used, but might not be able to withstand the temperatures commonly encountered when welding.
[0033] Each one of the Belleville washers 84 is dished or cupped. In the illustrated embodiment, the washers 84 are stacked in a particular manner so as to increase both load (resistance) and travel (total available deflection). A single Belleville spring 84 has a specific load and deflection. Belleville springs in stacked arrangements provide increased load and/or deflection. Specifically, two springs stacked in parallel (in the same direction or orientation) provide double the load or resistance of the single spring, with no increase in total deflection available. Two springs stacked in series (in the opposite direction or orientation) provide the same load or resistance as the single spring, with double the total deflection available. A parallel-series combination results in the load or resistance of two springs and the total available deflection of two springs.
[0034] In the illustrated embodiment, the washers 84 are stacked in a pattern that repeats three times. The pattern includes two washers 84 cupped down (in parallel with each other) and the next two washers cupped up (in parallel with each other but in series with the first pair). This arrangement provides a total of twelve washers 84 .
[0035] The number and pattern of washers 84 illustrated herein is only exemplary. Different numbers of washers 84 could be provided, and they could be stacked in a different order or pattern. Different types of individual spring elements could be used, also, in the spring 80 .
[0036] When the collet 30 is assembled, the stack 82 of washers 84 is disposed loosely in the plunger opening 46 in the collet base 40 . The side wall surface 48 of the collet base 40 locates the washers 84 and keeps them centered in the plunger opening 46 . The plunger 60 is located over the stack 82 of washers 84 , resting on the uppermost washer. The shank 74 of the retaining screw 70 extends through the plunger 60 and through the stack 82 of washers 84 and is screwed into the threaded lower portion 54 of the plunger opening 46 . The retaining screw 70 is preferably screwed in only until the head 72 of the retaining screw engages the bottom flange 69 of the plunger 60 , taking the play or looseness out of the stack 82 of washers 84 . Attempted further threading in of the retaining screw 70 would begin to compress the washers 84 , which would resist such motion strongly and rapidly. The retaining screw 70 is left in this position where the spring 80 is not compressed by any significant amount.
[0037] A locking screw 88 , which could be a socket set screw, is screwed into the locking screw opening 56 in the collet base 40 and engages the shank 74 of the retaining screw 70 . The engagement of the locking screw 88 with the retaining screw shank 74 helps to hold the retaining screw 70 in the desired position relative to the collet base 40 .
[0038] In the desired position, a portion but not all of the plunger 60 projects from the base surface 44 of the collet base 40 . Up to one third to one half the length of the plunger 60 might project from the base surface 44 . Preferably, no more than about twenty per cent of the plunger 60 projects from the base surface 44 . The side wall surface 48 of the plunger opening 46 helps to guide the plunger 60 and keep it aligned, to minimize skewing. The head 72 of the retaining screw 70 is recessed below the base surface 44 , as are all of the washers 84 . The plungers 60 are the only portions of the collet 30 that contact the workpiece; the collet base 40 , itself, does not.
[0039] When the fixture 10 is fully assembled, it includes four of the collet assemblies 30 , two on each one of the clamping units 12 and 14 . Each one of the clamping units 12 and 14 includes one collet 30 on its upper clamp half and one collet 30 on its lower clamp half.
[0040] FIG. 3 illustrates schematically the clamping unit 12 in use clamping a pipe 90 . The four plungers that are included in the two collets 30 are in engagement with the pipe 90 . Specifically, the top end surface 66 of each plunger 60 is in engagement with the outer side surface 92 of the pipe 90 . Because the plungers 60 are located on opposite sides of the pipe 90 , their combined resistance is averaged out to approximately center the pipe between them. This works for round pipe 90 , as well as for out-of-round pipe, which often, from handling, has an oval outside profile. In this respect, the collet 30 (or a set of collets 30 ) can be considered to be self-aligning or self-centering.
[0041] FIG. 4 shows the fixture 10 in use in clamping a pipe 90 having a relatively larger diameter. FIG. 5 shows the fixture in use in clamping a pipe 90 having a relatively smaller diameter.
[0042] The clamping unit 14 is capable of rigidly and tightly engaging the outer diameter of a pipe of a particular size depending on the diameter of the collet base surface 44 . By changing collet bases 40 , the clamping unit 14 can be made to accommodate tubing or piping of different size ranges. Additionally, by providing different size collets in one clamping unit 14 relative to those in the other clamping unit 12 , it is possible to bring into alignment two workpieces of different sizes such that it is possible to weld various pipe and fitting combinations.
[0043] The upper collet 30 and the lower collet 30 of a clamping unit 12 or 14 are the same and are interchangeable. Some other collet designs are sold as matched sets—if one collet becomes damaged to the point where it can no longer be used, the other collet half must be scrapped, because the new collets must be ordered as a set.
[0044] Another advantage of the collet 30 is cost-effectiveness. A collet in accordance with the present invention can be relatively inexpensive to make, because the majority of machined surfaces are clearance surfaces. Also, wear components of the collet 30 , such as the plungers 60 and the washers 84 , can be replaced very easily, while retaining the collet base 40 itself. This can provide the collet 30 with a very long service life. For example, if the spring 80 begins at some point to lose its temper, it can be easily and inexpensively replaced—in comparison to a collet with integral spring fingers in which case the entire collet must be replaced.
[0045] FIG. 10 illustrates schematically a collet 30 a that is an alternative embodiment of the invention. The collet 30 a functions similarly to a camera aperture. The collet includes a plurality of contact points in the form of plates 92 that slide about a center point. The plates 92 are biased radially inward by springs shown schematically at 94 . The plates 92 open and close equally so as automatically to center a pipe that is captured between them. In this respect, the collet 30 a can be considered to be self-aligning or self-centering.
[0046] FIGS. 11-13 illustrate schematically a collet 30 b that is another alternative embodiment of the invention. The collet 30 b includes a base ring 100 on which are rotatably mounted four contact points in the form of eccentric cams 102 . Rotation of the cams 102 is controlled by a slider ring 104 that engages the cams. Relative rotation of the slider ring 104 about the base ring 100 causes the cams 102 to pivot.
[0047] FIG. 11 shows the eccentric cams 102 fully open. A pipe section 110 is disposed within the collet 30 b in a position not centered in the collet. FIG. 12 shows the cams 102 rotating as the slider ring 104 is rotated relative to the base ring 100 , in a counter-clockwise direction as viewed in FIG. 12 . The cams 102 move radially inward, two of the cams contact the pipe 110 , and the pipe begins to move towards the center of the collet 30 b. FIG. 13 shows all four cams 102 in contact with the pipe section 110 . The pipe section 110 is centered within the collet 30 b. In this respect, the collet 30 b can be considered to be self-aligning or self-centering.
[0048] FIGS. 14 and 15 illustrate still another embodiment of the invention. In this embodiment, a collet includes contact points in the form of plunger assemblies at two axially spaced locations (that is, spaced apart in a direction along the axis of the workpiece being clamped) to help improve clamping accuracy and squareness.
[0049] FIG. 14 shows a clamping fixture 120 with an attached or inserted weld head 122 . The clamping fixture 122 includes four collets (numbered 30 c in FIG. 14 ) like the collet 10 . Each one of the collets is modified by the addition of two additional plunger assemblies.
[0050] In the collet 30 c, the collet base 40 c has an outer side surface 124 to which are attached two cantilever arms 126 . The cantilever arms 126 are attached to the collet base 40 c by mounting screws 128 and pins 130 , or other mounting structure. The arms 126 may be attached to the collet base 40 c at locations that are spaced apart circumferentially from the locations of the plunger assemblies 58 . The arms 126 extend axially away from the collet base 40 c (that is, in a direction along the axis of the workpiece being clamped).
[0051] At the outer end of each arm 126 is a contact point in the form or a plunger assembly 58 c that is preferably similar to or identical to the plunger assemblies 58 . The plunger assembly 58 c is by virtue of its location on the cantilever arm 126 spaced apart axially from the collet base 40 c. As a result, the plunger assembly 58 c is spaced apart axially from the other plunger assemblies 58 that are in the collet base 40 c. The pipe section is thereby clamped at two locations along its length. This can help to increase the clamping accuracy (squareness) of the fixture 120 by an order of magnitude or more. This can be useful when welding on a vertical run of pipe, for example.
[0052] Collets formed in accordance with the subject invention can be used in a variety of structures and clamping assemblies. For example, the collet could be used in a fixture for holding a pipe to be end faced (squared). Also, the collet could be used in a welding fixture for welding a fitting to a pipe, with the two clamp units being of different sizes. Accordingly, applicant intends to include all such modifications and alterations as part of the invention insofar as they come within the scope of the appended claims.
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A collet for holding a workpiece having an axis includes a collet base defining a collet axis. A plurality of contact points that are not integral with the collet base are supported on the collet base for movement relative to the collet base in directions generally toward and away from the collet axis. The collet is self-aligning whereby the contact points help to align the workpiece coaxially with the collet base.
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BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates in general to video cassette recorders and camcorders, which are hereafter referred to as VCRS, and to the videocassettes which these VCRs use for recording and playing back video and audio signals. More specifically the invention relates to VCRs which record and playback in the S-video mode. These S-video compatible VCRs can record in one or more of the standard formats which include VHS, 8 mm and VHS-C. The same S-video compatible VCRs also record and playback in one or more of the S-video modes which include SVHS,Hi8 mm and SVHS-C. Video signals recorded in the standard formats have a horizontal resolution of approximately 240 lines and are recorded as NTSC which is a composite signal where the luminance and chroma signals are combined. Video signals recorded in the S-video formats have a horizontal resolution of approximately 410 lines and are recorded as S-video signals where the luminance and chroma signals are recorded separately and carried on separate conductors. The S-video formats are superior to standard formats in video picture resolution and in signal degradation through successive editing and processing.
The VCR manufacturers who developed S-video format VCRs specified that S-video signals should be recorded on higher quality tape than the standard formats. To this end these same manufacturers designed the S-video VCRs to include a mechanical limit switch which detects the presence or absence of a record enable I.D. hole in the videocassette. Videocassettes which are sold as S-video compatible have an integrally molded the S-video record enable I.D. hole. When a videocassette that has the record enable I.D. h hole is loaded into a S-video compatible VCR the mechanical limit switch actuator pin goes into the same I.D. hole. The limit switch remains unactuated and the VCR's circuitry will allow recording in the S-video mode. Conversely if the I.D. hole is not present in the cassette the same limit switch is actuated when the cassette is loaded and S-video recording is not allowed by the VCR's circuitry.
People who use these S-video VCRs often purchase standard format cassettes (VHS, 8 mm or VHS-C) and add the S-video record enable I.D. hole to these same cassettes to allow these same cassettes to be recorded in the S-video mode (SVHS, Hi8 or SVHS-C). These same people are motivated do this for reasons of convenience and economy since S-video cassettes are less commonly available and more expensive. These same people consider the resulting videotape recordings generally acceptable for their intended use.
The practice of forming the S-video record enable I.D. hole in standard videocassettes by obvious and haphazard methods is inconvenient and inaccurate at best and hazardous at worst. The same practice is hazardous because lack of control may cause damage to the cassette and more importantly because debris which is created when forming the S-video record enable I.D. hole may be forced into the videocassette and ultimately come in harms way with regard to the video tape or the videocassette and VCR mechanisms.
An object of the present invention is to facilitate forming the S-Video record enable ID hole in standard videocassettes while avoiding damaging the cassette or letting loose debris enter the cassette. The present invention in its preferred embodiment can be used to form the S-video record enable hole in any VHS, 8 mm or VHS-C cassette. The same hole is formed by either cutting, piercing or melting through the plastic cassette casting.
A further object of the present invention is to provide accurate and automatic positioning for the hole forming implement when the same hole is being formed. This is accomplished by means of positioning plates one side of which fits to the videocassettes in a specific and singular way. One of these positioning plates is formed such that it provides said positioning for both VHS and 8 mm videocassettes. These same positioning plates contain guide bushings for properly positioning the hole forming implements while the holes are being formed. Said bushings are made of materials appropriate to the hole forming method employed and have a deliberately controlled length through the bore so as to control the depth to which the hole forming implement will penetrate the videocassette.
BRIEF DESCRIPTION OF THE DRAWINGS
The four figures of the drawing are as follows:
FIG. 1 is a diagrammatic view of the assembled parts of the hole making implements and positioning plate which is used for SVHS and Hi8 formats. The videocassettes appear as partial sections in this exploded isometric view.
FIG. 2 is a diagrammatic view of the assembled parts of the hole making implement and positioning plate which is used for SVHS-C format. The videocassette appears as a partial section in this exploded isometric view.
FIG. 3 is an isometric view of the lower side of the positioning plate shown in FIG. 1.
FIG. 4 is an isometric view of the lower side of the positioning plate shown in FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The device consists of two positioning plates 1, 10 and three hole forming implements 3, 5, 7 for making the hole in the plastic cassette shell. The positioning plates 1, 10 are formed so as to fit on the cassette in a specific and singular way providing accurate positioning for the hole forming implements which are pushed through the bushed holes.
The VHS-Hi8 positioning plate 1 which is used for a 8 mm cassette 12 or a VHS cassette 11 fits against VHS or 8 mm cassettes in separate singular and specific manners as follows:
On the lower side of the plate is a recessed area. This recessed area fits against a portion of the bottom side of the videocassette (this same bottom side is the side of the videocassette which is opposite the tape window).
The shoulder formed by the unrecessed area along the longer edge of the plate fits against the long "label" edge of the cassette (this is the cassette edge which is opposite the tape access door).
The shoulder formed by the other unrecessed area along the short edge of the plate fits against the shorter edge of the cassette on the rewind reel side.
On VHS cassettes, the nub created by the small remaining unrecessed area on the bottom of the plate 1 just fits into the molded in groove on VHS cassettes but does not reached the bottom of this groove.
On 8 mm cassettes the shoulder formed by the same nub fits against the shorter edge of the cassette on the take up reel side.
The VHS-C positioning plate 10 fits against a VHS-C cassette 13 in a singular and specific manner as follows;
On the lower side of the positioning plate is a recessed area. The unrecessed areas on this lower side form a rectangular frame which is sized to fit over the whole longer "label" edge of the VHS-C cassette so that the positioning plate 10 will remain in position relative to the cassette while the recessed area is held in contact with this same longer "label" edge.
The upper side of the positioning plate 10 bears markings which indicate which one of two possible ways the positioning plate should be oriented.
Fastened into the VHS- 8 mm positioning plate 1 shall be two identical bushings 2, 14 which are made of steel or other material which will resist cutting and wearing. The length through the bore of these same bushings shall be maintained in a specific relation to the length of the hole making implements 3, 5 which extends from their respective handles 4, 6. This specific relation is necessary to control the hole forming action of these same implements and shall be in concert with the method for forming the holes as described elsewhere in this description.
The various implements for making the hole includes the following:
a 5/32 inch diameter twist drill 5 with an attached handle 6 a 5/32 inch diameter round tapered and hardened steel point 3 with an attached handle 4
a 1/4 inch diameter tubular tip 7 incorporated as a tip on a standard soldering iron 8.
The method of forming the hole which involves cutting out the plastic may be used for either the VHS format or the 8 mm format. The cutting method involves the use of the 5/32 inch diameter twist drill 5 with attached handle 6, hereafter referred to as the drill handle assembly 5, 8. The person operating the invention places the positioning plate 1 on the bottom of the cassette 11 or 12 as applicable. The twist drill 5 is placed in the bushing 2 or 14, as applicable, that is marked for the format being converted. The inscription 16 adjacent to the VHS bushing 2 reads "VHS TO SVHS". The inscription 15 adjacent to the 8 mm bushing 14 reads "8 mm to Hi8". While the cassette and positioning plate are held stationary with respect to each other the person operating the device pushes the drill handle assembly 5, 8 down into the cassette 11 or 12, as applicable, while slowly turning the drill handle assembly 5, 8. The force so introduced will cause the twist drill tip to cut into the plastic material which makes up the cassette shell. Subsequent to this the twist drill tip will go through the cassette shell. Carried by the twist drill flutes the body of the drill will start to enter the interior of the cassette. After the twist drill tip barely enters the cassette the handle 6 of the drill handle assembly 5, 6 will come to rest against the positioning plate bushing 2, 14. At this point the hole formed in the cassette is in the shape of the cross section of the twist drill. As the person operating the invention continues to turn the drill handle assembly 5, 6 the twist drill 5 is prevented from being drawn deeper into the cassette because the drill handle 6 will come to rest against the positioning plate bushing 2, 14 as applicable. As the person operating the invention continues to rotate the drill handle assembly 5, 6 the sharp edges of the drill flutes cut a round hole at the same time that they draw the cut out material up into positioning plate bushing 2, 14.
The exposed length of the 5/32" twist drill 5 and the length through the bore of the positioning plate bushings 2, 14 is such that the cuttings are all drawn away from the cassette and up into the positioning plate bushing bore. These same cuttings being held and adequately contained in the drill flute openings inside the bushing bore. The person operating the invention then withdraws the drill handle assembly 5, 6 from the positioning plate while continuing to hold the positioning plate and cassette together. The plastic cuttings are thereby drawn out of the bushing bore and safely away from the cassette.
The method of forming the hole which involves piercing the plastic cassette shell with the 5/32 inch diameter round hardened and polished tapered point 3, hereafter referred to as the tapered point, may be employed for forming the S-video ID hole in VHS cassettes. This piercing method is especially suited to forming the S-video ID hole in lightweight consumer grade videocassettes which are made out of soft, thin plastic. Aided by the specially formed surface of the positioning plate 1 described previously the person operating the invention positions the positioning plate 1 on the bottom side of the cassette 11. The tapered point 3 is placed in the bushing 2 bore adjacent to the inscription reading "VHS to SVHS" 16. The cassette and positioning plate are held stationary with respect to each other by the person operating the invention. The person operating the invention centers the tip of the tapered point 3 in the bushing 2 bore and then pushes the tapered point 3 down into the cassette while turning the tapered point handle slightly. The force so introduced will pierce the plastic material which makes up the cassette shell. The pliable nature of the cassette shell material will allow it to deform so that the S-video ID hole may be formed without creating any loose plastic debris. The length of the tapered point 3 and the length thru the bore of the positioning plate bushing 2 shall be such as to stop the penetration of the tapered point 3 into the cassette 11 at the proper depth. The shape and size of the tapered point shall be such as to form the hole required with the given amount of penetration. The tapered point 3 goes from a sharp point to its full diameter in 3/4 inch of its length.
The method of forming the hole which involves melting the plastic cassette shell with the 1/4 inch diameter tubular tip 7, hereafter referred to as the tubular tip, may be employed for forming the S-video ID hole in VHS-C (compact) cassettes thereby allowing SVHS-C VCRs and camcorders to record such cassettes in the S-video mode. This method is employed because the VHS-C cassette requires a larger hole and the area on the cassette where it must be formed is close to the tape and internal mechanisms of the cassette. The tubular tip 7 is attached to a soldering iron 8 in place of the soldering tip. The tubular tip is thus heated to approximately 600 degrees Fahrenheit by means of the soldering iron 8 which may be powered by any typical method. Aided by the specially formed surface of the positioning plate 10 the person operating the invention positions the positioning plate 10 on the front edge, this being the edge of the cassette opposite and parallel to the cassette door edge, of the cassette 13. The heated tubular tip 7 is placed in the bore of the heat insulating bushing 9 in the positioning plate 10. The insulating bushing 9 is typically made of ceramic material. The cassette 13 and positioning plate 10 are held stationary with respect to each other by the person operating the invention. Meanwhile the person operating the invention pushes the tubular tip 7 down into the cassette 13 while turning the tubular tip 7 and soldering iron 8 assembly slightly. The tubular tip 7 will melt through the plastic material which makes up the cassette shell. The depth of penetration of the tubular tip 7 into the cassette 13 is controlled by specifying the length of the tubular tip and the length through the bore of the heat insulating bushing. When the tubular tip 7 melts through the cassette wall the unmelted disk which is formed is reliably drawn up into the tubular tip 7 by cohesive capillary action. The tubular tip 7 is then withdrawn from the heat insulating bushing 9. A hole is thereby formed and the cutout material is safely removed from the cassette. A hole through the wall of the tubular tip 7 allows the introduction of a cleaning wire into the inside of the tubular tip 7 so that the unmelted disk can be pushed out of the tubular tip 7. The tubular tip 7 is just small enough to fit into the heat insulating bushing 9 in the positioning plate 10. The heat insulating bushing 9 in the positioning plate 10 fits tightly against the cassette 13 thereby preventing the melted material from flowing to the outside of the tubular tip 7.
The foregoing relates to a preferred exemplary embodiment of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.
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A device and method are disclosed for forming the S-video record enable I.D. Hole in VHS, 8 mm and VHS-C videocassettes. Three specially adapted hole forming implements and their method of use are described. These implements are adapted to avoid forming loose debris from the hole forming process and to prevent such debris which is created from entering the cassette mechanism. The invention provides for automatic positioning of the hole forming implements and for control of their movement by use of positioning plates which are specially adapted to fit on the videocassettes in a singular and specific manner. The invention further provides for controlling the operation and movement of the hole forming implements by use of guide bushings which are integral to the positioning plates. The methods used for forming the hole include cutting, piercing and melting through the plastic cassette shell.
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BACKGROUND OF THE INVENTION
1) Field of the Invention
The field of this invention relates to connectors and more particularly to a connector for an elongated member which is mounted onto an end of the elongated member.
2) Description of the Prior Art
The typical method of mounting an elongated member, such as a rod to a plate, would be by forming a threaded connection on the end of the rod and inserting that threaded connection through a hole in the plate, and then mounting of a fastener nut in conjunction with the threaded end of the rod, thereby securing it to the plate. However, such connections are not easily accomplished in certain environments. For example, a confined quartered environment would be in conjunction with a molding machine where there are utilized a plurality of elongated rods, commonly called ejector rods or knock-out bars, which are used to eject molded parts from the mold. These elongated rods are mounted onto a plate which is commonly termed a butterfly plate. There are numerous points of connection for the elongated rods to the butterfly plate. These numerous points of connection vary according to the individual desires of the person operating the mold. Also, one particular mold might require a certain placement of these rods with another type of mold requiring another type of placement. That means the position of the rods have to be changed on the butterfly plate. In almost every mold machine, the position of the butterfly plate is not readily accessible. It is also dangerous because to change the position of the rods requires that the individuals hands, wrists and arms be positioned within the molding machine and if the molding machine is accidentally activated, the individual could be injured.
Although the structure of this invention has been found to be of particular advantage for the mounting of knock-out bars for molds, it is to be considered to be within the scope of this invention that this invention could be utilized in conjunction with any elongated member where it is desired to remotely secure the elongated member to a separate structure and remotely disconnect the elongated member from the separate structure.
SUMMARY OF THE INVENTION
A connector for an elongated member which utilizes a male part and a female part. The male part could be mounted to the separate structure and the female mounted to the elongated member or vice versa. One of the parts is mounted to one end of the elongated member. When this part is moving in contact with the other part and sufficient force is applied, three in number of different springs are compressed. One of the springs is an external spring which applies a continuous force between the two parts tending to separate the parts. The second spring is to apply force to a fluid actuated piston located internally of the connector with the bias of this spring tending to locate the piston in an extended position which permits separating of the two parts. There is a third spring that applies force to the piston and overrides the second spring which locates the piston in a retracted position. When in the retracted position, a series of balls of the male member are forced outwardly to occupy a position within a groove of the female part thereby achieving the locked relationship between the male part and the female part. When fluid pressure is applied to the fluid piston, the fluid piston will move against the bias of the third spring compressing such and move the fluid piston to the extended position. Separation of the male and female parts is then possible.
The primary objective of the present invention is to construct a connector which achieves a secure connection between an elongated member and a separate structure with it only being required that the elongated member be forcibly moved in conjunction with the connector that is mounted on the separate structure.
Another objective of the present invention is to provide a connector for an elongated member which permits the connector to be disconnected by the application of fluid pressure from a remote source.
Another objective of the present invention is to construct a connector which is constructed of relatively few parts and thereby can be manufactured relatively inexpensively and thereby sold to the ultimate consumer at a relatively inexpensive price.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of the connector of the present invention depicting the typical installation for the connector and showing the connector in the locked position;
FIG. 2 is a back end view of the connector of the present invention taken along line 2--2 of FIG. 1;
FIG. 3 is a front end view, partly in cross-section, of the connector of the present invention taken along line 3--3 of FIG. 1;
FIG. 4 is a longitudinal cross-sectional view through the connector of the present invention taken along line 4--4 of FIG. 1 again showing the connector in the locked position;
FIG. 5 is a cross-sectional view similar to FIG. 4 showing the connector in the unlocked position and depicting partial separation of the connector;
FIG. 6 is a cross-sectional view similar to FIG. 5 but showing the connector in its disengaged position;
FIG. 7 is an enlarged view of a portion of the connector taken along line 7--7 of FIG. 5; and
FIG. 8 is a cross-sectional view through the locking balls utilized in conjunction with the connector of the present invention taken along line 8--8 of FIG. 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring particularly to the drawings, there is shown the connector 10 of this invention. Connector 10 is composed of a male part 12 and a female part 14. The male part 12 includes an elongated exteriorly threaded rod 16 the outer end of which is threadably secured to a nut cap 18. The inner surface of the nut cap 18 has an O-ring 20 mounted about the threaded rod 16. A fitting 22 is fixedly secured to the nut cap 18. Fitting 22 is for connection to a fluid pressure line (not shown). This fluid pressure line is to be connected to a source of fluid pressure which is also not shown. The fluid pressure could comprise hydraulic or pneumatic with generally pneumatic being preferred.
The fluid pressure from the fitting 22 is conducted through hole 24 which is transversely formed through the elongated threaded rod 16. Hole 24 connects to a centrally located passage 26 formed within the elongated threaded rod 16. The outer end of the threaded rod 16 is fixedly mounted to a sleeve 28. The sleeve 28 has an outer surface within which is mounted an O-ring 30 with the O-ring 30 also surrounding the elongated threaded rod 16. The elongated threaded rod 16 is to be threaded within the sleeve 28 until the nut cap 18 and the sleeve 28 are tightly secured against opposite sides of a separate structure in the form of a mounting plate 32. A typical structure for the mounting plate 32 would be a butterfly plate within a plastic molding machine. The O-rings 28 and 30 form a tight seal with the mounting plate 32.
The exterior surface of the sleeve 28 includes an annular relief 34. Located within the annular relief 34 is a coil spring 36. Also mounted within the annular relief 34 is a collar 38. One end of the spring 36 abuts against the sleeve 28 with the opposite end of the spring 36 abutting against the collar 38. The collar 38 is slidably mounted within the annular relief 34. The outer end of the annular relief 34 includes an annular recess 40 within which is mounted an O-ring 41. If annular recess 42 contacts O-ring 41 such will prevent collar 38 from separating from the sleeve 28 and the outer limit of movement of the collar 38 is defined. The inward limit of movement on the collar 38 is shown in FIGS. 1 and 4 of the drawings,
Formed within the sleeve 28 is a series of holes 44 with actually six in number of the holes 44 being shown. The holes 44 are located in an evenly spaced apart relationship concentrically disposed about the longitudinal center axis 46 of the connector 10. Mounted within each hole 44 is a steel ball 48. The inner surface of the balls 48 is supported in an annular groove 50 formed within a piston 52. The piston 52 is slidably mounted within center bore 54. The O-ring 41 also protrudes slightly axially so as to prevent balls 48 from falling out of holes 44 when male part 12 is separated from female part 14.
A coil spring 56 is mounted within the center bore 54 with one end of the coil spring 56 abutting against the front end of the elongated threaded rod 16. The opposite end of the coil spring 56 rides within center cavity 58 of the piston 52. The outer limit of movement of the piston 52 is defined by snap ring 60 which is mounted within the center bore 54. The piston 52 includes a fluid seal in the form of an O-ring 51 to prevent fluid leakage as well as a cam surface 62 which connects to annular shoulder 64. The O-ring 51 sets in annular groove 53 formed in piston 52. The outer end of the piston 52 is formed into a point 66. Mounted about the point 66 is one end of a coil spring 68. The coil spring 68 is positioned and restrained within center bore 70 of the female part 14. The center bore 70 includes an enlarged front portion 72 which includes an annular groove 74. The enlarged front portion 72 terminates in a chamfered front forward section 76. Center bore 70, the enlarged front portion 72, the annular groove 74 and the chamfered forward section 76 are formed within housing 78 which comprises the female part 14. The back end of the housing 78 connects to a cylindrical threaded section 80 which is to be threadably secured to one end of the elongated member 82. Typically the elongated member will comprise a rod such as a ejector rod or what is commonly termed a knock-out bar for a molding machine.
The operation of the connector 10 of this invention is as follows: With the forward end of the sleeve 28 abutting against shoulder 84, balls 48 will be forced outwardly by riding up cam surface 62 with the shoulder 64 preventing inward motion of the balls 48 (FIG. 4). In this position the spring 36 is fully compressed. The spring 68 is of a greater bias than spring 56 which will result in the piston 52 assuming a retracted position with the shoulder 64 preventing inward movement of the balls 48. This is the locked position for the elongated member.
In order to achieve this locked position, it is only necessary to force elongated member 82 and the female part 14 onto the sleeve 28. The chamfered forward section 76 functions as a guide for the entry of the sleeve 28 into the enlarged front portion 72 of the bore 70. The front end of sleeve 28 is also chamfered forming annular inclined surface 75 to further assist in guiding entry of sleeve 28 into enlarged front portion 72. Upon the sleeve 28 coming into contact with the shoulder 84, the balls 48 will be positioned within the annular groove 74. This fixes the position of the elongated member 82 to the mounting plate 32.
Now let it be assumed that it is desired to disengage the elongated member 82 from the mounting plate 32. In order to achieve this, fluid pressure is to be supplied through hole 24 and passage 26 into a center bore 54. This fluid pressure pushes against the back side and seal of the piston 52. This force, coupled with the bias of the spring 56, will override the bias of the spring 68 and cause the piston 52 to be moved forwardly until it comes into contact with the snap ring 60. At this particular time the spring 68 is substantially compressed and the balls 48 are permitted to fall within the annular groove 50 disengaging from the annular groove 74. The housing 78 is now capable of being slid off of sleeve 28 and this sliding movement is facilitated by the bias of the spring 36 which applies force to the collar 38 which pushes against the outer end of the housing 78 of the female part 14. This sliding movement is assisted by spring 68 pushing against female part 14. Spring 68 has a higher spring force than spring 36. This will result in separation of the female part 14 from the male part 12 as is shown in FIG. 6 of the drawings. Once separation has occurred, the fluid pressure applied within the passage 26 is then eliminated at which time the piston 52 will remain in its established position directly against the snap ring 60.
It is important that the piston 52 remain in this established position and it is for that reason that the coil spring 56 is utilized. The spring 56 exerts a bias on the piston 52 to locate the piston 52 in the position shown in FIG. 6 (when male part 12 is disengaged from female part 14) which is with the balls 48 retracted within annular groove 50. If per chance the piston 52 was permitted to be moved back (no spring 56) so that the shoulder 64 was positioned underneath the balls 48 and the balls 48 were located in the outward position, it would make it impossible for the male part 12 to engage with the female part 14 since the balls 48 would already be in the outward extended position and would not be able to pass through the enlarged front portion 72.
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A connector for an elongated member which is composed of a male part and a female part. The female part is fixedly mounted onto an end of an elongated member with the male part being fixed onto a separate structure or vice versa. The male part includes a fluid operated piston which is to be supplied fluid pressure from a remote source. Axially pressing of the female member in contact with the male member will result in the connector being located in a locked relationship. Application of fluid pressure from the remote source will cause the connector to move to an unlocked relationship permitting locating of the female part in a spaced apart relationship from the male part.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority under 35 U.S.C. § 119(e) on U.S. Provisional Application No. 60/285,674 entitled SAMPLE MOUNTING PRESS, filed on Apr. 23, 2001, by Cox et al., the entire disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a mounting press for metallographic samples and particularly to an improved seal structure for the molding chamber.
Mounting presses are employed to mold a thermoplastic or thermosetting material around typically a metallic specimen for ease of handling in subsequent polishing and analyzing processes. Such mounting presses include a cylindrical mold chamber into which an upper closure ram and a lower hydraulically driven ram extend, such that the molding material and sample are held and compressed between the rams.
The standard upper closure ram uses a handle to move a radially sealing upper ram into the bore of the molding cylinder at the top. This mechanism is then locked into place with a quarter turn, bayonet-type device or by using coarse threads. This style of enclosure requires considerable manipulation by the operator especially if they have to turn the mechanism to engage threads. Opening of this type of closure is also difficult since, during the molding process, pressure builds up between the lower ram and the removable, upper closure ram of the mold cylinder. This pressure on the quarter turn device or the threads makes it very difficult for the user to spin the mechanism open. Regularly a length of pipe or some other type of lever must be used to gain a mechanical advantage to open the mold cylinder. Also, blowby flashing tends to make the upper closure ram stick within the mold cylinder. Once open, any residual material or “flashing” left on the upper ram of the closure device must be cleaned prior to sliding the upper ram back into the bore of the mold cylinder.
SUMMARY OF THE INVENTION
The invention is a departure from such traditional mounting press enclosure systems. The hydraulic enclosure system of this invention avoids the cumbersome radial seal altogether and instead utilizes a face seal which engages the top face of the mold cylinder. This face seal is actuated by a hydraulic cylinder which presses a sealing cap piece against a top annular sealing face of the mold cylinder. When this cap piece has formed a face seal, the metallographic mount is molded. When the face seal is removed, the internal pressure of the mold is immediately released and an upper enclosure containing the cap piece is readily moved away from the mold cylinder to expose a mount and specimen contained therein for fast, easy removal. In a preferred embodiment, the hydraulic cylinder and cap piece is mounted to a cylindrical column that allows it to rotate away from the mold cylinder when the mount is complete and rotate into place when a mount is to be made. The column that acts as the rotational device also delivers the hydraulic fluid to the upper hydraulic cylinder so there is no need for a hose or other hydraulic connection. Also, the cap piece and top face of the mold cylinder do not need to be cleaned between mounts. This enclosure system also allows the workable height of the system to be lower and makes it more accommodating for the operator since it minimizes user interaction with the mold process and prevents user exposure to hot mechanism. Further, the hydraulic system in one embodiment combines the hydraulic cylinders, manifold, valving, pump, reservoir, transducers, rotary seal, and accumulator into one assembly eliminating hydraulic hoses and fittings between components, which virtually eliminates hydraulic leak potential.
These and other features, objects and advantages of the present invention will become apparent upon reading the following description thereof together with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a sample mounting press embodying the present invention;
FIG. 2 is a fragmentary right-side perspective view of the upper pivoted section of the assembly shown in FIG. 1 , shown with the upper face sealing cylinder pivoted to a position exposing the mold cylinder assembly and showing a metallographic molded sample in position for removal therefrom;
FIG. 3 is a side elevational view of the sample mounting press;
FIG. 4 is an exploded perspective view of the face seal assembly;
FIG. 5 is a perspective view of the mold cavity subassembly;
FIG. 6 is an exploded lower perspective view of the structure shown in FIG. 5 ;
FIG. 7 is an exploded perspective view of the pivoted hydraulic supply cylinder seen also in FIG. 3 ;
FIG. 8 is a fragmentary vertical cross-sectional view of the sample mounting press; and
FIG. 9 is a perspective view of the mold adapter block shown in FIGS. 3 and 8 .
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring initially to FIG. 1 , there is shown a sample mounting press 10 embodying the present invention which comprises a lower cabinet 12 housing a keypad 14 and display 16 for the operation of the unit. Mounted within cabinet 12 is the mold cylinder assembly 30 ( FIGS. 3 , 5 and 8 ) and a lower ram assembly including a mold adapter block 40 , a hydraulic cylinder 84 , and a manifold 42 coupled to a hydraulic pump 41 providing a hydraulic fluid system pressure of approximately 3000 pounds for operation of the various hydraulic cylinders employed in the system.
Pivotally mounted with respect to cabinet 12 is an upper face seal assembly 20 ( FIGS. 3 , 4 , and 8 ) which, as seen in FIGS. 1 and 2 , is mounted in an upper enclosure 18 which can pivot to the left (shown by arrow A in FIG. 1 ) to expose the top sealing face plate 31 of the mold cylinder assembly 30 , shown in detail in FIGS. 5 and 6 . This exposes the cylindrical mold cavity 32 to allow the operator to remove the metallographic sample encapsulated in a molding material as a unit in disk-shaped sample mount 17 ( FIG. 2 ) as described below.
The upper face seal assembly 20 is shown in FIG. 4 and includes a pancake hydraulic cylinder 25 which is coupled by a thermal gasket 26 and fasteners 22 to a cylindrical flange 24 with the completed assembly shown in FIG. 3 . Cylinder 25 includes a movable piston rod 23 ( FIG. 8 ) having an enlarged end over which the sealing cap piece 27 extends via an undercut slot 29 ( FIG. 4 ). Metal cap 27 is rigid and defines a rigid face seal 28 which sealably engages the top annular sealing surface 31 of mold cylinder assembly 30 , as best seen in FIG. 8 . Flange 24 also includes an undercut slot 21 ( FIG. 4 ) which defines a shoulder 21 ′ that lockably engages circular flange 34 of mold assembly 30 (as also best seen in FIG. 8 ) to lock the face seal assembly 20 to the mold assembly 30 during the molding process. Thus, semi-annular shoulder 21 ′ ( FIG. 4 ) circumscribes an arc which is open sufficiently such that cylindrical flange 34 can be received within slot 21 . When closed as seen in FIG. 8 , the upper surface of shoulder 21 ′ engages the lower surface 35 of the flange 34 of the mold assembly 30 to lock the face seal assembly to the upper end of the mold cavity, thereby allowing the sealing pressure to be applied to effect the face seal by cylinder 25 .
The pancake hydraulic cylinder 25 is sealably coupled to a cylindrical column or pressure rotary coupling 50 ( FIGS. 7 and 8 ), which receives pressurized hydraulic fluid from pump 41 via manifold 42 . The pressure rotary coupling 50 has a generally cylindrical body 52 with a central bore 54 therein capped by sealing cap 56 at its upper end. A radially extending opening 55 is sealably coupled to the input 25 ′ of pancake cylinder 25 by means of an O-ring sealing gasket 56 ′, as best seen in FIG. 8 . The lower end of pressure rotary coupling 50 is rotatably mounted within a mounting plate 60 by means of a sleeve bearing 62 . Hydraulic pressure is applied to the cylindrical bore of rotary coupling 50 at its lower end from manifold 42 via port 43 ( FIG. 8 ). Suitable valves are provided to selectively apply pressure during the sealing and molding process in a conventional manner. The lower end 57 of rotary coupling 50 is sealably mounted within the bushing 52 and block 60 by means of an O-ring seal 58 and back up ring seal 59 ( FIGS. 7 and 8 ), which allows rotation of the upper seal assembly 20 coupled to rotary coupling 50 between a closed position, as shown in FIGS. 1 and 8 , and an open position, shown in FIG. 2 , by the rotation of rotary coupling 50 with respect to the fixed mounting block 60 . Rotary coupling 50 is held in block 60 by an annular flange 57 integral with the body 52 of the rotary coupling and an annular clamp 64 ( FIG. 8 ) secured to block 60 , in turn, suitably secured within cabinet 12 .
Mold cylinder assembly 30 ( FIGS. 5 and 6 ) includes four cartridge heaters 33 ( FIG. 6 ) positioned in radially spaced relationship around the peripheral of the cylindrical body 36 of the mold assembly 30 , which is conventionally surrounded by a cylindrical water jacket 37 sealed by pairs of spaced O-rings 38 . A thermocouple 33 ′ is also inserted into the body 36 of mold cylinder assembly 30 and is employed in connection with a control circuit to provide the desired molding temperature within the cylindrical mold cavity 32 by heaters 33 during the molding process. The mold cylinder assembly 30 includes four radially outwardly extending arcuate flanges 44 spaced at approximately 90° intervals and circumscribing an arc of about 30° to 40° to interlock with the lower mounting block 40 , as seen in FIG. 8 . Block 40 , as best seen in FIG. 9 , includes a base plate 41 which is bolted by bolts 42 ( FIG. 3 ) extending into through apertures 47 into the top of hydraulic cylinder 84 . Cylinder 84 includes a piston 85 , as seen in FIG. 8 , extending upwardly and which is captively held with its enlarged head 86 fitted within an undercut open slot 87 in a lower ram 88 enclosing the lower end of cylindrical mold chamber 32 . The mounting block 40 includes four upwardly extending shoulders 48 , each of which include an undercut 45 which defines shoulders 46 . The arcuate shoulders 46 are spaced at 90° intervals with slots 49 extending between adjacent shoulders 46 to allow the insertion of flanges 44 therein to bayonet-lock mold assembly 30 to block 40 . Shoulders 46 engage and lock flanges 44 of mold assembly 30 into locked engagement with cylinder 84 , such that pressure can be applied to the lower end of the cylindrical mold chamber 32 by ram 88 when actuated by hydraulic pressure from manifold 42 coupled to cylinder 84 by a suitable valve. Hydraulic cylinder 84 is actuated at approximately 3000 psi system pressure during an operating cycle to extend ram 88 upwardly into the chamber 32 of cylindrical mold assembly 30 while the top surface 31 of the mold chamber is sealed by the face seal 28 to compress the polymeric thermosetting material around and onto a metallographic specimen.
During a cycle of operation, the upper assembly 18 is opened to the position shown in FIG. 2 , and ram 88 is raised by the actuation of cylinder 84 to present the top disk-shaped surface 89 of ram 88 to an operator for placing a metallographic sample thereon. Subsequently, cylinder rod 85 and ram 88 are retracted slightly into the cylindrical mold cavity 32 of mold body 36 . Resin is then placed into the mold cavity 32 , and the upper assembly 18 pivoted using rotary coupling 50 to a closed locked position. The pancake hydraulic cylinder 25 is then actuated to form the face seal at the upper end of the mold chamber 32 . Heat and pressure is then applied to the molding material by heaters 33 and compression through lower cylinder 84 to the thermosetting material for a predetermined period of time sufficient to mold the material around the metallographic sample. A conventional thermosetting or thermoplastic resin into which the metallographic sample is encapsulated is melted under an internal mold pressure of from about 2000 psi to about 4200 psi at about 300° F. The molding process takes from 6 to 20 minutes depending upon the material employed, which may include polycarbonate, phenolics, epoxies, or other resins typically employed for molding metallographic samples for use in metallographic analysis equipment. After the heating and pressure steps, mold assembly 30 is cooled either using water applied to the water jacket 37 for cooling the chamber or, in the case of thermoplastic resin, it is air cooled. The pressure on cylinders 25 and 84 is then released by suitable valving to allow the upper unit 18 to again pivot to an open position. The metallographic sample disk-shaped mount 17 is removed from the device by again applying some hydraulic pressure to cylinder 84 to eject the mount 17 , as seen in FIG. 2 . By providing a face seal which is readily moved away from the mold chamber and by activating cylinder 84 , the disk-shaped mount is pushed out of the cylindrical mold chamber 32 , and the prior art difficulties with opening the upper end of the mold cavity is eliminated through the use of the face seal 28 . The body of the mold cavity and the cap piece forming the face seal can be made of metals typically used for sample mounting presses, such as stainless steel, aluminum alloys, or the like. The sealing surfaces 28 and 31 of the respective members are polished to form a leak-free seal when cylinder 25 is actuated by a pressure of about 3000 psi.
It will become apparent to those skilled in the art that various modifications to the preferred embodiment of the invention as described herein can be made without departing from the spirit or scope of the invention as defined by the appended claims.
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A hydraulic sample mounting press utilizes a face seal against the top face of a molding cylinder. The face seal employs a hydraulic cylinder to press a disk-shaped surface of a cap piece against the top annular face of the mold cylinder for a metallographic mounting press. The face seal cylinder is mounted to a hydraulic fluid column that allows the face seal to rotate away from the mold cylinder for access to the molding cylinder and to rotate into place when a metallographic mount is to be molded.
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BACKGROUND OF THE INVENTION
The invention relates to a bar lock for a locking system that is to be used in particular in metal cabinet doors, comprising a lock body having guide slots disposed therein for receiving at least one lock bar that is guided in the lock body, and at least one pinion that is disposed in the lock body and that via its external teeth is in engagement with holes formed in the lock bar along the longitudinal axis thereof in such a way that a rotation of the pinion is converted into a longitudinal displacement of the lock bar, and which pinion has a centrally disposed engagement opening for the positive engagement of an actuating device such as a handle, pivot lever, socket wrench, or the like.
A bar lock having the aforementioned features is known from EP 0 261 267 B2; the known bar lock is preferably used in the switch cabinet industry as a component of a locking system for thin-walled metal cabinet doors that have at least one, in particular rectangular door recess for the mounting of the locking system. In this connection, placed upon the outer side of the door is a base plate having a receiving means for the actuating means such as a handle, pivot lever, socket wrench, or the like, and is screw-connected or otherwise fastened with the lock body that is placed upon the inner side of the door, so that the door panel is fixedly clamped between the base plate and the lock body. With the known bar lock, the lock body is composed of two symmetrically formed lock body halves, whereby the two lock body halves together form the guide slot for the at least one lock bar; preferably two lock bars are simultaneously used. Centrally mounted in the lock body, and encased by and between the lock body halves, is a pinion that via a respective bearing member rotates in an associated mounting bore of each lock body half, and which via its external teeth engage in a single perforation that extends along the longitudinal axis of the pertaining lock bar. The lock body halves are joined together via a plug connection, and the lock body is secured to the base plate via screws that extend through both of the lock body halves and engage the base plate that is disposed on the outer side of the door.
The known bar lock has the drawback that the assembly and mounting of the bar lock is complicated because the pinion is to be placed together with the in particular two lock bars into one of the lock body halves, whereby the lock bars are introduced into the guide slots and at the same time the pinion, with its bearing member, is to be placed into the mounting recess that is provided; subsequently, the two lock body halves must be mounted and then either the two placed-together lock halves must be secured to the base plate via through-bolts, or the lock body halves must be wedged together.
The object of the invention is to embody a bar lock having the aforementioned features in such a way that its assembly is simplified.
SUMMARY OF THE INVENTION
The realization of this object, including advantageous embodiments and further developments of the invention, results from the content of the patent claims that follow this description.
The basic concept of the invention is that the lock body is embodied as a single or monolithic component having the guide slots recessed therein on its oppositely disposed longitudinal sides, and on both sides a respective recessed area is symmetrically arranged between the guide slots for receiving a respective pinion placed into the recessed area, whereby the recessed areas are separated from one another by a central member formed in the lock body, and the guide slots, in the region of the recessed areas, are each provided with a window for the engagement of the teeth of the pinion disposed in the recessed area into the plane of the lock bar disposed in the guide slots, and whereby the pinions, via a connecting body that extends through an opening of the central member, are positively interconnected, and in that the lock bar has two parallel rows of engagement openings for the teeth of the pinion that have the spacing of the pinion that is disposed in the lock body, and first engagement openings disposed at the end of the lock bar that is to be inserted into the lock body are embodied as a laterally open toothing and subsequent engagement openings are embodied as perforations.
The invention has the advantage that the monolithic lock body is easier to handle during the assembly of the bar lock as well as during the mounting of the bar lock on the base plate. For the assembly, the lock bars are inserted into the guide slots of the lock body to such an extent that their open toothing is disposed in the windows of the lock body between the guide slots and the recesses; in this position, the pinions can be placed into the pertaining recesses or recessed areas, whereby the teeth of the respective pinion come to rest in the open toothing of the associated lock bar. The two thus inserted pinions are then interconnected via the connecting body, preferably in the form of a plug, that is to be disposed in the square inner hole of the pinion. If subsequently the lock bars are inserted further into the lock body, the teeth of the pinions engage into the respectively associated perforations of the pertaining lock bar and are also thereby held in the lock body.
Pursuant to one embodiment of the invention, it is provided that the pinions be interconnected via a plug that extends through the opening of the central member and is provided with a square inner hole, whereby it can be provided that on the other side of the plug there be formed a shoulder that conforms to the width of each pinion for the defined fixing of the pinion in place upon the outer periphery of the plug. In particular, the pinions can be placed via a square inner hole upon the plug, which is provided on its outer side with a square shape, whereby the pinion can also be wedged with the plug. To improve the transfer of force between the plug and the pinions, it can be provided that the outer square shape of the plug be provided on two oppositely disposed corners with an extension shoulder that externally spans the respective corner in a right-angled manner, and the square inner hole of the pinion is adapted to the shape of the outer square of the plug, including the extension shoulders. With a view toward an advantageous reduction of the number of individual parts, it can be provided that the plug be monolithically formed with one of the two pinions, and that the other pinion be placeable upon the plug.
In an alternative embodiment of the invention, it can be provided that the pinion, in a symmetrical embodiment, be monolithically formed with a respective peripheral portion of the plug, and the peripheral portions of the plug that are respectively disposed on the two pinions together form the plug when the two pinions are joined together, whereby the peripheral portions respectively extend over a quarter of a circle and can be disposed in the region of the oppositely disposed corners of the square inner hole. With this embodiment, it is expedient if the pinions can be joined together with peripheral portions of the plug via a plug-type connection formed on the peripheral portions.
It can finally be provided that the other recessed area of the lock body, which is not engaged by the actuating device, be adapted to be closed off by means of an insertible protective cover.
BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary embodiments of the invention are shown in the drawings, which will be subsequently described. Shown are:
FIG. 1 An exploded illustration showing details of a bar lock,
FIG. 2 The bar lock of FIG. 1 in the assembled state,
FIG. 3 A detailed view of an embodiment of a pinion for use in the bar lock of FIGS. 1 , 2 ,
FIG. 4 a A detailed view of an embodiment of a plug that is to be placed into the bar lock of FIGS. 1 , 2 ,
FIG. 4 b A front view of the subject matter of FIG. 4 a,
FIG. 4 c A plan view of the pinion pertaining to the plug of FIGS. 4 a, b,
FIG. 5 Another embodiment of the pinion of FIG. 3 .
DESCRIPTION OF PREFERRED EMBODIMENTS
As can be initially seen in FIG. 1 , the bar lock is provided with a one-piece or monolithic lock body 10 having a rectangular cross-section, on the parallel, oppositely disposed longitudinal sides of which guide slots 11 are formed in the lock body 10 into which respective lock bars 12 can be inserted.
With a view toward the use of the bar lock in a locking system, each of the lock bars 12 has an elbow or shoulder 13 as well as attachment means 14 for the mounting of further locking bars; such a locking system is described in detail in the generic EP 0 261 267 B2.
In a symmetrical arrangement, the lock body 10 is provided on both sides, between the guide slots 11 , with a respective recessed area 15 for receiving a pinion 18 ; the two recessed areas 15 are interconnected by a central member 16 that is formed in the lock body 10 and that in turn has an opening 28 .
Each recessed area 15 intersects the two guide slots 11 , and in this region a respective window 17 is formed so that the outwardly disposed teeth 19 of the pinion 18 extend into the plane of the guide slots 11 and can here be brought into engagement with the lock bars 12 that are introduced into the guide slots 11 . The two pinions have a square inner hole 20 , so that the two pinions 18 are interconnected via a plug 21 that is inserted into the square inner holes 20 thereof and that in turn is provided with a square inner hole 22 for the engagement of the actuating device. The actuation, which is not illustrated in the present application, yet is described in detail in the generic EP 0 261 267 B2, can be brought via an associated square-end shaft into engagement with the plug 21 , so that by rotating the plug 21 the pinions 18 are rotated. The outer periphery of the plug 21 is provided with respective shoulders 23 , so that the pinions 18 are to be connected with the plug 21 in a defined position.
Each of the lock bars 12 has two rows of engagement openings for the teeth 19 of the two pinions 18 , whereby the two rows of engagement openings, which are disposed parallel to one another in the longitudinal axes of the lock bars 12 , are coordinated to the position of the pinions 18 that are disposed in the recessed areas 15 . In this connection, the first two engagement openings, which are disposed on those ends of the lock bars 12 that are to be respectively inserted into the lock body 10 , are embodied as a laterally open toothing 29 while the further engagement openings are embodied as perforations 30 .
Finally, that recessed area 15 that is not engaged by the actuating means is to be closed off via a protective cover 24 . The lock body 10 is furthermore provided on its end face with projecting ribs 31 that are intended for engagement in a door recess, as well as with screw holes 32 into which appropriate fastening screws can be inserted for mounting of the bar lock on a base plate.
As can be seen from FIG. 3 , the plug 21 could be monolithically formed with one of the two pinions 18 , so that the other pinion 18 can be placed upon the projecting shoulder 23 of the plug 21 .
The further embodiment of FIGS. 4 a-c illustrates the plug 21 , with the pertaining pinion 18 , and which plug is to be inserted into the bar lock, whereby the external square of the plug 21 , or two oppositely disposed corners of the shoulder 23 thereof, are provided with an extension shoulder 36 that externally spans the respective corner in a right-angled manner. In conformity therewith, as can be seen from FIG. 4 c , the square inner hole 20 of the pinion 18 is adapted to the shape of the external square of the plug 21 or of the shoulder 23 thereof, including the extension shoulders 36 disposed thereon, so that in this way the transmission of torque between the plug 21 and the pinions 18 is improved, and a twisting-off of the plug 21 at high load is prevented.
FIG. 5 illustrates another exemplary embodiment of a pinion 18 with plug 21 , whereby on a pinion 18 two peripheral portions 25 are monolithically formed with the pinion 18 , the peripheral portions respectively extending over a quarter of a circle and being disposed in the region of oppositely disposed corners of the square inner hole 22 of the plug 21 . The pinions 18 , with the peripheral portions 25 disposed thereon, are identically embodied so that the pinions 18 can be mounted together in a position rotated by 90 degrees relative to one another such that the plug 21 results as a consequence of inter-engagement of the peripheral portions 25 . Associated herewith in particular is the advantage of an improved transfer of force between the two individual pinions 18 . It is furthermore provided that the two pinions 18 are to be assembled together via a plug-type connection, whereby the plug-type connection is formed from respectively two guide or insertion pins 26 and two associated receiving openings 27 that engage one another when the two pinions 18 are joined together.
The features of the subject matter of this document disclosed in the preceding description, the patent claims, the abstract and the drawing can be important not only individually but also in any desired combination with one another for realizing the various embodiments of the invention.
The specification incorporates by reference the disclosure of German priority document 200 09 771.7 filed Jun. 2, 2000 and International priority document PCT/DE01/02057 filed 30 May 2001.
The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawings, but also encompasses any modifications within the scope of the appended claims.
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A bar lock for a locking system is provided, and comprises a lock body having guide slots and two recessed areas symmetrically disposed on opposite sides between the guide slots and separated from one another by a central member. Two lock bars are received in the guide slots and have engagement openings. Two spaced apart pinions are received in the recessed areas. Rotation of the pinions is converted into a longitudinal displacement of the lock bars. The pinions are positively interconnected via a plug.
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This is a continuation of co-pending application Ser. No. 07/060,391 filed as PCT/SE86/00430 on Sept. 26, 1986, published as WO87/02091 on Apr. 9, 1987, now abandoned.
FIELD OF INVENTION
The invention relates to a method for drilling deep holes and a device for performing the method. The invention relates more specifically to a method and a device for exchanging drill bits on a drilling rod in situ in a hole when one drill bit is worn out without lifting the whole drilling rod and drill bits up to ground level and, thus, without all drawbacks thereof.
PRIOR ART
Drilling deep holes into the earth is of very great interest today for drilling for oil, natural gas and geothermal energy, on-shore as well as off-shore. Drilling such deep holes is normally done by sinking a drill bit on the bottom of a drilling rod in order to cut or crush the material at the drill bit at the bottom of a hole thus formed. The crushed material, called drilling mud, is washed up to ground level by a drilling fluid, which can be water, a mineral oil, compressed air, etc. As such drilling proceeds downwards, the drilled hole is lined with a steel tube.
One well-known drilling technique uses a roller-type drill bit having, for example, three rollers with hard metal alloy tips evenly distributed on their surfaces. These rollers are pressed with great force against the bottom of the hole and rolled therearound, whereby the hard metal alloy tips break or crush the material at the bottom of the hole. This material is very variable in hardness, because it ranges from primary rocks through unfixed species of stones such as sandstone to gravel and soil. The drill speed depends on the hardness of the material.
Another well-known drilling technique is hammer drilling, wherein a pneumatically driven hammer produces the material cutting in the drill hole. This drilling technique is limited, however, in how deep a hole can be drilled.
In the deep hole drilling, therefore with a roller type bit, however, the drill bit wears out and must be exchanged after drilling a certain, lesser, distance. What wears out in the drill bit is the bearings of the rollers and the hard metal ally tips, which are, ordinarily, inserts. Therefore, bearings of the best quality and hard metal alloy tips of the highest structural strength and quality are used. In some applications, the hard metal alloy tips are even replaced with diamonds, but this makes the drill bit more expensive. As to the roller bearings, they are exposed to a very harsh environment. In deep hole drilling, the pressure of the drilling mud and fluid column in the hole is very high and their sludge abrasive. These facts place extremely high leakage demands on the bearings, because if the sludge enters the bearings, they will be immediately destroyed.
Even though elaborate techniques are used to protect a drill bit from such wear and, thereby, extend its life, however, it will sooner or later wear out. Then, as mentioned above, the drilling rod has to be taken up so the drill bit can be changed at ground level. This operation is very time consuming and, therefore, causes a lengthy drilling interruption. In some cases, too, it can be very difficult or impossible to take up the drilling rod, e.g. when drilled hole has substantial bends.
SUMMARY OF THE INVENTION
An object of the invention is, therefore, to exchange a drill bit underground, without taking up the drilling rod, whereby a long drilling interruption is avoided and the drilling time is considerably shortened.
Another object of the invention is appropriately positioning the worn-out, exchanged drill bit. The drilled hole has a diameter only as big as the drill bit and, therefore, there is no room for lateral exchange between the worn-out drill bit and a new one positioned thereabove.
As to the first end, exchanging the drill bit underground, at the bottom of the hole, the invention provides two or more bits as integral parts of a drilling device used at the bottom of the hole. Thus, when a first, lowermost drill bit wears out, there is another drill bit closely thereabove, ready for use.
As to the second end, positioning the worn-out drill bit, it is well known that a bit can so wedge in the hole that it cannot be disengaged and has to be left in the hole. The new drill bit put on the drilling rod after it has been taken up to ground level is then sunk down the hole, drills a side hole at a small angle near the bottom of the original hole with the wedged-in bit, and then proceeds downwards beside the old wedged-in bit. This technique can also be used with the drilling device of the present invention, but it is still difficult to drill such a side hole and the resulting bending of the drill is a drawback. According to the invention, therefore, a side hole is provided for the worn-out drill bit, to put it out of way. Drilling with the newly-exchanged bit then continues along the original hole axis.
Thus, according to the present invention, there is provided a method of drilling a hole in the ground, and a drilling device to be attached to a driven drilling rod, the drilling device having at least two, axially successive bits, one above the other. When the first drilling bit is worn-out, the bits are exchanged in situ at the bottom of the drilled hole.
For this, the drilling device has a separating device operable in two steps. When the bits are to be exchanged, the first step of the separating device is activated while the worn-out bit continues rotation to cause the drilling device to drill a side hole or pocket. When the worn-out bit has drilled itself into the side hole or pocket, it is released in the second step from the drilling device, and the next bit thereof starts drilling in the original hole.
Preferably, the separating device for each exchangeable bit has two plates and at least two shafts, which connect one plate on the worn-out bit with the second plate on the bit positioned thereabove. The shafts pivot the one plate with the worn-out bit to a predetermined angle, e.g. 80°, to drill the side hole or pocket for the worn-out bit, and then release the shafts from connection with said corresponding second plate positioned thereabove. Then, the first drilling bit with pertaining plate shaft is left in the evacuating pocket thus formed, and drilling in the original hole resumed with the new bit on the second plate. Suitably, each shaft is telescopic, so that the shafts will shorten in length when released from connection with the second plate to be out of the way of the new bit thereon.
According to a preferred embodiment of the invention, the second shaft is connected to the second plate by an axle pin having essentially a rectangular cross section on the second plate and a sleeve with a slit having a width, which corresponds to the narrowest dimension of the axle pin on the second shaft. The shaft and the sleeve disengage from the second plate and axle pin when the shaft has been pivoted radially outwards to said predetermined angle, because the axle pin only then can pass through said slit in said sleeve.
The invention also relates to a drilling device for performing the method according to the invention. The drilling device is attached to and driven by a drilling rod. It comprises at least two drill bits, one axially above the other. An eccentric device adapts it to make a cone-shaped evacuating pocket in the side of the hole at activation with the lowermost worn-out bit. A releasing device disengages the lowest drilling bit to leave it in the cone-shaped evacuating pocket for further drilling in the hole with the second drilling bit positioned thereabove.
During the time when the evacuating pocket is provided, the cut material will sink to the bottom of the hole. Thus, when the bits are so exchanged, the drilled hole must be sufficiently deep, so that the volume of the hole below the drilling lining at least corresponds to the volume of the evacuating pocket.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described below in more detail with reference to a preferred, exemplary embodiment of the invention shown in appended drawings in which:
FIG. 1 is a perspective view of a drilling device according to the invention;
FIG. 2 is a perspective view of the drilling device of FIG. 1, but with drilling bits thereof removed.
FIG. 2a is perspective view of a portion of the drilling device of FIG. 1 in a cross section taken on line II--II in FIG. 2;
FIG. 3 is a perspective view of another portion of the drilling device of FIG. 1 in a different position;
FIG. 4 is a perspective view of the portion of the drilling device of FIG. 3 in different final position;
FIG. 5 is a perspective view of still another, locking and trigging portion of the drilling device of FIG. 1; and
FIG. 6 is a perspective view of the portion of the drilling device of FIG. 5 in a different position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In FIG. 1, the drilling device 1 according to the invention is shown to have an upper portion attached to a drilling rod 2. The drilling rod is driven by a driving device (not shown) positioned at the ground level, e.g. a drilling platform or a ground-based station. Of course, the driving device can also be positioned under ground in a cave, tunnel, etc.
Three roller drill bits or crowns 3a, 3b, 3c are successively aligned with each other, one below the other, and operatively connected to the drilling rod 2, so that the lowermost crown 3a initially performs the drilling work. The crowns are of a well-known construction and, therefore, need not be described in more detail here. The drilling device could also use other types of drill bits or comparable material-cutting devices.
The bits 3a, 3b, 3c are successively arranged one after the other on one side of respective transversal plates 4a, 4b, 4c. The opposite side of one, uppermost plate 4c is connected to the drilling rod 2 and the opposite sides of the two lowermore plates 4a, 4b each have a damping device 6 (FIG. 2) for receiving drilling edges of the preceding uppermore bits 3b, 3c, whereby the bits 3b, 3c space the plates 4a, 4b, 4c as long as they are connected. Each two successive plates 4a, 4b, 4c are respectively interconnected with three telescopic shafts 5a, 5b, 5c, but it is easy to see that the number of shafts can vary depending on the application and demand for structural strength. The plates are interconnected with the shafts, but are maintained at a predetermined distance from each other by drilling bits between the plates and the damping devices.
The damping devices 6 are on the upper sides of the plates 4a, 4b, as appears from FIG. 2. Each has recesses for the three rollers of the bit 3b, 3c positioned thereabove. The operation of the damping devices is to damp the forces, which are exerted in the axial direction of the drilling rod and to transfer a rotation moment between the plates in conjunction with the telescopic shafts.
As appears from FIG. 1, the bits 3b and 3c are positioned within and protected by the border of the plates and the shafts thereabout, so that they are not worn during drilling with bit 3a.
The rotation moment from the drilling rod 2 is transferred by the plates and shafts in conjunction with the bits 3c and 3b to the bit 3a. The drilling fluid flows from the drilling rod to the bits via channels 15 in the plates and inside one, interconnected telescopic shaft 5b (as shown in phantom in FIG. 2) downwards to the then lowermost bit, each bit having holes (not shown) for receiving it. After flowing from the lowermost bit, as known, the drilling fluid with the drilling mud flows up, past indentations in the peripheries of the plates and between the hole lining (not shown) and the drilling rod 2, to the ground. The drilling fluid is powered by a suitable pump device at the ground level.
In FIG. 2, the drilling unit of FIG. 1 is shown without the bits 3a, 3b, 3c to show more clearly other details, such as the damping device already described. Thus, in FIG. 2, it is shown that the shafts 5a are pivotably attached to their respective lower plates 4a, 4b with pins 7. The same shafts 5a are fastened to their respective upper plates 4b, 4c with a pivotable coupling at 11a, which will be described in more detail below. Each one of the two other shafts 5b and 5c are rigidly fastened to their respective lower plates 4a, 4b and releasably connected to upper plates 4b, 4c, the latter by respective telescopic heads at 8 (only one indicated in FIG. 2), as more clearly appears from FIGS. 3 and 4. Each telescopic head is retained in position with a locking pin 9 which is controlled by a piston 23 in a cylinder 10 (only one each indicated). The piston and cylinder are a locking device, which retracts the corresponding locking pin 9 and releases the telescopic head 8 from the corresponding plate 4b, 4c.
According to the present invention, the locking device and a triggering impulse receiver (not shown) therefore are hermetically enclosed in plates 4b, 4c, as shown representatively in FIGS. 5 and 6 for plate 4c and shaft 5b. Accordingly, in order to release a head 21 of the telescopic shaft from a locking profile 28 in the plate 4c receiving it, the impulse receiver triggers a spring-activated punching pin 10a, which then liberates compressed gas from a capsule 10b. The gas is conducted in the channels 10c to the other side of the piston 23, where the locking pin 9 prevents the telescopic head 21 from leaving the profile 28 in plate 4c. The gas pressure and a spring 24 push the piston 23 to pull the locking pin 9 from the head 21. A channel 25 provides the gas pressure to the end of the locking pin 9 in the head 21 to free the pin from the head with the gas pressure, too. At that time, all the forces on the locking pin 9 cooperate in one direction to pull the locking pin 9 form the head. When the locking pin 9 has, thus, passed a channel 26, the gas pressure is also directed around the telescopic head 21, for pressure equalization inside and outside of the locking profile 28. Then, with the locking pin 9 out of its hole in the telescopic head 21, the telescopic head 21 is pulled from its seat in the locking profile 28 by a spring in the telescopic shaft 5b, which pushes the telescoping housings of the shaft into each other to shorten the shaft. The other shafts 5c are shortened in the same way, but not the shafts 5a.
Each entire locking device, which holds the telescopic heads 21 in position, including its impulse receiver is, therefore, hermetically enclosed in a plate. The impulse receiver can be remote controlled in a number of different ways, as by radio waves, microwaves, ultrasonic waves or any other form of impulses which would propagate inside the drilling rod when filled with liquid or evacuated. The locking pin can be driven pneumatically as described, or hydraulically or mechanically, which can be arranged in a suitable way.
As mentioned before, the drilling fluid is automatically shut off to the worn-out drilling bit 3a in the first step of its release. For this, the telescopic head 21 influences a mechanism (not shown), which pulls a flap 15ax in FIG. 2a corresponding flaps in uppermore plates 4b, 4c (not shown) in the channel 15 for the drilling fluid in the way shown by the arrow in FIG. 2a so that the fluid is directed to the drilling bit (not shown in FIG. 2a) presently used. At bit exchanging, when the corresponding telescope head 21 is leaving its seat (locking profile 28) due to the contracting movement of a telescopic shaft, the mechanism so changes the position of the flap, so that the drilling fluid is switched off to the worn-out drilling bit and opens to the next new one. Thus, each bit in the drilling device is associated with at least one shaft 5b provided with a channel cooperative with a channel 15 in the plates having the flap mechanism or valve device designed therefor.
When a worn-out bit, e.g. bit 3a, is to be changed, this takes place according to the invention in the following way.
Firstly, the rotation of the drilling device 1 by the drilling rod 2 is stopped and, possibly, the drilling hole is washed free from cuttings. Then, an impulse signal is sent to the impulse receiver in plate 4b, which activates the two locking devices therein to pull their locking pins 9 from the corresponding telescopic heads at 8 of shafts 5b and 5c. The drilling bit 3a and the plate 4a thereof are now only connected to the plate 4b by the shaft 5a. Each of shafts 5b, 5c is provided with a spring 14, which telescopically shortens the shafts. The drilling device is then put into slow rotation. The worn-out bit 3a, the plate 4a and the shafts 5b and 5c are now eccentrically hung by the shaft 5a, however. This and the rotation forces said elements outwards, towards the wall of the drilled hole. The shafts 5b and 5c no longer prevent such a movement. The shaft 5a is pivotably attached to both the plate 4a and the plate 4b, so it does not prevent such movement outwards, either. The worn-out drilling device thus makes a cone-shaped enlargement in the wall of the hole. This process is schematically shown in FIG. 3, which shows the worn-out bit directly after release of the shafts 5b and 5c. From the same FIG. 3, it also appears how the free ends of the shafts 5b and 5c will cut into the other side of the drilling wall and scratch and wear material out therefrom. However, the most useful work will be performed by the worn-out drilling bit itself.
As the drilling device continues to rotate, the cone-shaped enlargement is made progressively bigger, and the shaft 5a makes a wider angle with the plate 4b. The rotation speed is also slowly increased during the process, so that the centripetal force will increase, and thus, the material cutting of the worn-out bit 3a produces a ring-shaped evacuating pocket. The joint between the shaft 5a and the plate 4b consists of an axle pin 11 in the plate 4b having an obliquely-narrowest cross section at a predetermined angle and a sleeve 12 provided with a slit 13. The oblique narrowest cross section of the axle pin 11 appears from FIGS. 3 and 4, whereas the sleeve 12 is there shown to have a cylindric cross section with the slit 13 having a dimension circumferentially of the cylindric sleeve corresponding to the narrowest cross section of the pin. Thus, the sleeve is released from the pin when the narrowest part of the pin is aligned with the slit as the shaft pivots the sleeve on the pin as the bit progressively produces the evacuation space.
At the starting position, the slit 13 of the sleeve 12 is positioned in its highest position. As the shaft 5a is angled outwards from the vertical line during the later, bit-exchanging rotation thereof, the slit of the sleeve is displaced towards the narrowest cross section of the axle pin. At the predetermined angle of the inclination of this, narrowest cross section of the axis pin, the slit 13 of the sleeve 12 is aligned with the narrowest part of the axle pin. Since the width of the slit 13 is as large as the narrowest part of the axle pin, the sleeve 12 is pulled from the axle pin 11 as its telescopic shaft 5a then shortens as is shown in FIG. 4.
The diameter of the pocket can be further increased in the following way. For the sleeve 12 to leave the axle pin 11, even when aligned, the sleeve must overcome a certain frictional drag of the slit 13 on the pin 11, which is attained by increased rotation speed. During this period, when the rotation speed is increased, the centrifugal force lengthens the telescopic shaft 5a, which is provided with a double spring action for this. The worn-out drilling bit 3a is then wearing material about the hole essentially in the radial direction, increasing the diameter of the pocket, whereby a ring-shaped slit is formed. When the centrifugal force is as large as the friction drag, the sleeve 12 slips over the axle pin 11.
Until this moment, torque for the rotary movement has been transferred by the axle pin 11 to the sleeve 12 of the shaft 5a and from the shaft to the plate 4a and the worn bit 3a for drilling on the side of the hole.
The ring-shaped evacuating pocket thus made has then at least achieved a sufficient dimension to be able to accommodate the worn-out drilling bit 3a with plate 4a and pertaining shafts 5a, 5b, 5c. When the sleeve 12 is released from the axle pin 11, the torque transfer by this joint is discontinued and the bit 3a stops in the evacuating pocket with its plate 4a and telescopic shafts 5a, 5b, 5c forever.
Rotation of the drilling rod is then stopped, and a drilling lining is pressed to the bottom of the drilled hole, whereby the evacuating pocket is sealed off from the hole. As mentioned above, the springs 14 shorten the telescopic shafts 5b, 5c as they pull their telescopic heads 21 from their locking profiles 28, so that the shafts 5b and 5c will be out of the way, in the pocket, for this. Shaft 5a is still elongated during the entire pocket-making process, however, due to gravitation and centrifugal forces. When the sleeve 12 passes off the axle pin 11, the spring 14 in shaft 5a shortens it for final keeping, too. The new drilling bit 3b is then lowermost in the drilling device, too, and drilling the hole can start again therewith.
In FIG. 1, a drilling device having three bits has been shown, but according to the invention, a drilling device can operate with as few as two bits, and the upper limit for the number of bits only depends on the application. Accordingly, for example, six drilling bits can be put in a line.
In FIG. 2, there is shown a channel system 15 for the drilling fluid, but it is only one example of such a channel system.
In FIG. 4, the shaft 5b is shown with another spring 16, which facilitates the removal of the locking pin 9 and the release of the telescopic head 8 from the plate 4b. Instead of springs 14, 16, pneumatic or hydraulic force transducers can be used for telescoping the legs or shafts.
The drilling device according to the present invention can also be adapted to other drilling methods, such as turbo drilling, etc.
The invention is not limited to the embodiments disclosed hereinabove, but can be modified in many respects within the scope of the invention as defined by the appended claims.
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A device for drilling deep holes in the ground has at least two axial drill bits and an equal number of plates each having three shafts axially interconnecting the plates. Two of the shafts are rigidly attached to both plates and the third shaft is pivotably attached to both plates. The two rigid shafts are separable from the upper plate by pulling a locking pin separating a telescopic head of each shaft from the plate. At the separation, the shafts are telescopically shortened by springs and the drilling liquid is automatically shut off to the worn-out drill bit and opened to the new drill bit. The remaining third shaft eccentrically interconnects the plates, whereby the lower worn-out drill bit, at rotation, wears a semicircular evacuation pocket in the wall of the hole. The third shaft is successively pivoted outwards until it forms an angle of e.g. 80deg with the axis of the hole. An axle pin having rectangular cross-section retains the upper end of the third shaft via a sleeve with a slit. The slit has such a dimension that the narrowest cross-section of the axle pin can pass through the slit at said angle for releasing the third shaft from the second plate for placing the worn-out drill bit with three legs and plate in the evacuation pocket thus formed.
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FIELD OF THE INVENTION
The present invention relates to material handling equipment, and more particularly to material handling equipment adapted for manipulating and hammering objects through the use of a robot type manipulator. In greater particularity the invention relates to severe-duty robots for grappling and manipulating objects in a heavy industry environment. In even greater particularity, the invention relates to impactor devices on the heavy duty manipulators for impacting gates and risers on cast objects in a foundry environment and thereby severing the same. Furthermore, the grapple invention incorporates the impactor within the manipulator so that the impactor's hammer rod extends through the robot manipulator's jaws to provide a gate or riser removal apparatus.
BACKGROUND OF THE INVENTION
The foundry industry utilizes robot manipulators in hazardous environments. Robots and robotic arms or manipulators, sometimes called articulated booms, must withstand heat, dust, vibration, and general battering of heavy industry when working in foundry environments. Due to these severe duty requirements, manipulator designs currently internalize hydraulic lines, avoid using telescoping joints, operate at higher speeds, manipulate in a large work envelope, and incorporate customized computer hardware and software to accommodate complex repetitive motions. Typically, robot manipulators are controlled from either a downloaded program initiated from a console, or through manual control via a joystick. Severe-duty manipulators incorporate various types of articulated booms to accommodate a wide range of objects. A manipulator may have a single large arm, or several highly mobile segmented arms to expand the field of operation. Robot manipulators may sometimes move objects weighing several tons, and thus incorporate high pressure hydraulic control systems. Articulated booms incorporate various types of grapples at the end or their arms to accommodate different tasks. A grapple may have a single pair of cooperative jaws, or several pair, or an odd number of jaws. In addition, jaws may be pressure sensitive, have teeth for gripping, or have shear cutting edges.
Foundry operations also utilize heavy duty impactors, sometimes referred to as knock-off hammers or thumpers. In the manufacture of iron castings, such as ductile iron castings, large iron risers are attached to critical areas of the molds to compensate for casting shrinkage during cooling. Remnant risen or gates can be removed manually with a sledge hammer, however many blows may be required to remove the gates at a high level of danger to a worker. In addition, worker training and protection is required in the manual gate removal strategy, thus making the use of labor intensive manual clean-up and de-gating of foundry castings a costly operation. The foundry industry has responded by utilizing pneumatic impactors or hammers to de-gate castings. The industry has also equipped grapples with metal shear type jaws to cut gates off castings during clean-up and sorting.
Some foundry manipulators have knock-off hammers at the end of their booms in place of a grapple. The articulated boom enables an operator to quickly manipulate the hammer into position to break-off a gate. These manipulator knock-off hammers often are used to move foundry castings into position by prodding or pushing castings. However, the Knock-off manipulators are not optimized for moving objects and are inadequate for sorting of castings after clean-up. Sighting indicia are usually provided on the impact tip where the impact rod extends out of the hammer housing to facilitate hammer aiming. An example of such a casting knock-off machine is the Action Impactor model #1060 IM, manufactured by Action Machinery Co. of Helena, Ala., USA. The model 1060 has a highly mobile boom and orientation joints to quickly move into an optimal position to knock-off a casting riser, including sighting indicia to facilitate aiming.
After a knock-off hammer de-gates a foundry casting, typically another type of manipulator will then be used to sort and move foundry pieces to a desired location. Severe duty manipulators, such as Action Manipulator model #960, manufactured by Action Machinery Co., have adaptable grapples and rapid response movement to quickly grasp and move foundry castings. Knock-off manipulators are not equipped to sort and manipulate objects and are therefore of limited specific use. Conversely, robot manipulators are not equipped to de-gate castings. Therefore, there is a great need in the industry for a robotic manipulator with a grapple that can both de-gate a casting using an impact hammer, and rapidly manipulate the de-gated casting into a desired area.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide a material handling device utilizing an articulated boom and grapple that can grip objects and rapidly move them to a desired area.
Another object of the present invention is to provide an impact hammer for removing gates or risers from foundry castings during a clean-up operation.
Still another object of the invention is to provide a power grapple attached to the end of an articulated boom containing an impact hammer for de-gating casting risers and then sorting and rapidly moving the casting articles to a desired area.
Yet another object of the current invention is to provide an impact hammer disposed within a power grapple having an orientation means interposed between the grapple and an articulated boom for de-gating casting risers.
Another object of the invention is to provide a sighting reference along the jaws of the grapple to facilitate impact hammer aiming.
Still yet another object of the present invention is to provide an articulated boom having a power grapple at an end that can grasp objects and impact them with an impact hammer while contained within the jaws of the grapple.
Yet another object of the invention is to provide an articulated boom and power grapple with impact hammer that has a cushioning cylinder on the boom to regulate impact recoil upon hammer rod extension.
Yet another object of the invention is to provide a power grapple and impact hammer apparatus with shearing jaws for cutting and knocking-off of casting risers and gates.
Other features and objects and advantages of the present invention will become apparent from a reading of the following description as well as a study of the appended drawings.
The apparatus may be briefly described as a power grapple attached to an articulated boom. An orientation means is interposed between the grapple and the boom to allow pitch and yaw motion, and the grapple has a pair of gripping jaws mounted on a rotation means to allow 360° jaw rotation thereby giving the grapple full and precise positioning capability. A pneumatic impact hammer is disposed within the rotation means, and an impact rod of the hammer extends through and between the clamping jaws. The jaws allow extension of the impact rod when the jaws are in a closed position along the central axis. The jaw tips have a semi-circular shape to form an opening at the tip of the grapple when the jaws are closed from which the impact rod extends to impact objects. The shape of the grapple in combination with the jaw tips allow an operator to quickly align a targeted object with the opening prior to rod actuation. The recoil shock of impacting a casting article is regulated with a shock absorbing cylinder attached to the orientation means and the boom.
BRIEF DESCRIPTION OF THE DRAWINGS
Apparatus embodying features of my invention are illustrated in the enclosed drawings which form a portion of this disclosure and wherein:
FIG. 1 is an elevational view showing the entire apparatus;
FIG. 1A is an elevational view of the grapple and orientation means with the pitch actuator extended to show pitch adjustment.
FIG. 2 is an elevational view of the grapple and orientation means mounted on the boom end with grapple jaws in closed and open positions.
FIG. 3 is an elevational view of the jaw and jaw timing gears.
FIG. 4 is an elevational view of the jaw rotated 90 degrees from FIG. 3.
FIG. 5 is an elevational view of the jaw on an opposite side from FIG. 4.
FIG. 6 is a perspective view of the jaw with the hammer rod extended.
FIG. 7 is a front elevational view of jaws in a closed position.
FIG. 8 is an elevational view of shear type grapple impactor in a closed position.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings for better understanding of the principles of operation and structure of the invention, it will be seen that FIG. 1 shows an overall layout of the apparatus containing the grapple-impactor invention. Articulated boom 10 is supported by base 11 that includes a turntable 12 for rotation of the boom in 360 degrees. Boom 10 includes a larger first elongated arm 13 and a second elongated arm 14 attached to the first arm 13 through a boom articulation joint 16. Arm 14 includes a free end 21 distal the articulation joint 16, and boom arm 14 supports an attachment head 20 which is attached to the free end 21. The attachment head 20 is also connected to the boom articulation joint 16 through a shock control cylinder 17 and an extension member 18 in coaxial linear alignment. The extension 18 and shock control cylinder 17 are supported in parallel alignment to boom arm 14 with parallelogram linking members 19. Linear actuation means 15 provides power movement to the boom arms as is well known in the art.
Referring to FIG. 2, mounted on the attachment head 20 of the boom is an orientation means 42 having a pitch body 22, a pitch actuator 26 connected to pitch body 22 at 31, and a pivot means 24. Orientation means 42 is pivotally mounted on the attachment head 20 via a rotatable mounting 23. Rotatable mounting 23 many be understood as a ring gear 231 and modified bearing captured between mounting plate 201 affixed to attachment head 20 and plate 221 affixed to pitch body 22, such that pitch body 22 is supported for concomitant rotation with ring gear 231. An actuator 27 which may be understood as a pinion gear driven by a hydraulic motor controls rotation of the ring gear 231 to control the yaw movement of the pitch body 22 relative to the attachment head 20. Grapple 43 has a pitch head 28 connected to pitch body 22 through pivot means 24. Pitch actuator 26 has one end connected to pitch head 28 at 25. As can be seen in FIG. 1A, pitch actuator 26 urges pitch head 28 around pivot means 24, thereby controlling grapple pitch orientation. Pitch head 28 supports impact hammer assembly 29, and a rotation mounting means 33. Rotation mounting means 33 may be understood as a ring gear and motor driven pinion 32 as herein above described, having a continuous aperture therethrough, and mounted to pitch head 28 and a grapple body assembly 35. Impact hammer assembly 29 is disposed within the rotation mounting means 33 so that impact rod 39 extends through the rotation mounting means 33, grapple body assembly 35, and a set of complimentary jaws 34 and 34', along a central axis 41. Jaws 34 and 34' are mounted on grapple body assembly 35 to allow 360 degree rotation of the jaws about the central axis. Pinion 32 is mounted on pivot head 28 to control rotation (roll) of the jaws about the central axis.
As is best seen in FIGS. 3-5, Jaws 34 and 34' each include a pivot end 38, 38' and a jaw tip 37, 37'. Each jaw includes a weldment 45, 45' on the pivot end pivotally connected at 48, 48' to a grapple body assembly 35. A grapple actuation means such as a linear actuator 36 is connected between each respective weldment 45, 45' at 46, 46' and in combination with the pivotal connection 48, 48' allows the jaws to pivot to an open (34a) or a closed position (34b) in response to the grapple actuation means, and thereby also allowing free rotation about axis 41 while opening and closing. Actuator 36 is offset from axis 41 such that it does not interfere with the impact hammer. FIG. 3 shows that each jaw includes a timing gear 44, 44' fixed to the weldment 45, 45' which cooperatively mesh to maintain the jaws in an equal relation with respect to the axis 41 when closing and opening.
Referring again to FIG. 2, the Impact hammer assembly 29, includes a cylindrical housing 52 which is mounted to plate 281 affixed to the pitch head 28 by flange 521 and bolts 522. The appropriate hydraulic circuit is connected to extend impact rod 39 through rotation mounting means 33 and grapple body assembly 35 without interfering with the rotation of the jaws. In a retracted position 39a, the rod will not interfere with the grasping and manipulating of objects by the jaws. The rod extends partially beyond the jaw tips 37, 37' to a position 39b through an opening 53 formed by the cooperative structure of each jaw tip 37, 37' (see FIG. 7). The opening 53 allows the impact rod 39 to impact objects when the jaws are in a closed position 34b. While clamping jaws are shown in FIGS. 1-7, shearing type jaws may be substituted while also allowing rod extension beyond the shearing jaw tips as shown in FIG. 8.
In a typical foundry operation, an operator positions the grapple by maneuvering the boom 10 and orientation means 42 as is well known in the industry. The operator then can rotate the jaws using the rotational mounting means 33 and open the jaws using the grapple actuator 36. A cast object can then be grasped within the jaws and moved as just stated to a desired area and released. Once the object is released, the operator can close the jaws and use the jaw tips and channel opening to aim the impact rod to a desired contact point. In a de-gating procedure, the operator aims the rod to contact the casting gate thereby removing the gate upon impaction. After extension, the rod automatically retracts to position 39a, and the operator can use the grapple as a manipulator to sort castings to a desired area.
It will be appreciated to those familiar with the art that the impactor grapple replaces two individual robotic machines doing the same de-gating task, yet will operate within the same severe-duty foundry environment. It will also be appreciated that the invention can be utilized in mining, demolition, scrap handling, and similar work.
While it has been shown that the invention works in one form, it will be obvious to those skilled in the art that it is not so limited but is susceptible to various changes and modifications without departing from the spirit thereof.
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An improved robotic power grapple having the capability to both manipulate and impact objects. The grapple has a head assembly containing pivotal jaws and an impact hammer disposed within a rotation device to allow the head assembly and jaws to rotate about a central axis. An impact rod extends through the rotation device and through an opening in the tips of the jaws to permit impaction of objects proximate the opening. In combination with an articulated boom and orientation device, the improved grapple may be utilized in severe-duty foundry operations to remove gates and risers from foundry castings.
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FIELD OF THE INVENTION
1. Background of the Invention
This invention relates to a packaging method and to packaging apparatus for performing the method.
2. Description of the Prior Art
GB2100696A discloses a machine for forming, filling and sealing cartons and comprised of eight work stations, namely a straw and sealing tape applicator station, a carton blank wrapping and folding station, a seam and one end bonding station, a carton rotator and conveyor transport station, an other end closure preform station, a filler station, an other end closure sealing station, and a carton ejector station. At the seam and one end bonding station, every carton blank is transferred onto a rotary crossbar mandrel having a horizontal axis, and through a series of operations, a side seam of the carton is sealed, and one end closure of the carton is formed and sealed. At the carton rotator and conveyor transport station, every carton is removed from the crossbar mandrel, turned through a right-angle about its own longitudinal axis, which is horizontal, and inserted upon a conveyor on which the carton remains until ejected from the machine.
U.S. Pat. No. 4,337,059 discloses a packaging machine for forming, filling and sealing cartons, in which machine cartons are indexed in pairs through various work stations to accomplish forming, filling and sealing of the cartons. The forming of the bottom closures of the cartons is performed upon a rotary turret having a vertical axis. The turret is stepped about its axis to bring the cartons into the stations in turn and is of a type which includes two mandrels at each station and which indexes two mandrels from one station to the next station. From the turret, the bottom-closed, open-topped cartons are advanced stepwise linearly by a chain conveyor through various stations in which the cartons are filled and top closures thereof are formed. A difficulty with this machine is that a carton having its top and bottom closures orientated parallelly to each other and a carton having its top and bottom closures orientated perpendicularly to each other require differing machine layouts, especially in respect of the top and bottom closure forming stations.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a packaging method comprising advancing carton sleeves, sealingly closing one end of each carton sleeve at one end closing means to form a carton open at its other end, filling at filling means the cartons open at their other ends, sealingly closing at other end closing means the other end of each carton, advancing further carton sleeves, sealingly closing one end of each further carton sleeve at said one end closing means to form a further carton open at its other end, filling at said filling means the further cartons open at their other ends, and sealingly closing at said other end closing means the other end of each further carton, wherein the improvement comprises, relatively to each first-mentioned carton in its path of advance from said sealingly closing its one end to said sealingly closing its other end, turning each further carton about its longitudinal axis through substantially a right-angle between said sealingly closing its one end and said sealingly closing its other end.
According to another aspect of the present invention, there is provided packaging apparatus, comprising one end closing means arranged sealingly to close one end of each of a plurality of carton sleeves to form a carton open at its other end, filling means arranged to fill the cartons open at their other ends, other end closing means arranged sealingly to close the other end of each carton, and advancing means arranged to advance said carton sleeves and said cartons along a path past said one end closing means, said filling means and said other end closing means, in turn, wherein the improvement comprises turning means arranged to turn each of selected ones of said cartons about its longitudinal axis through substantially a right-angle as the carton passes along said path from said one end closing means to said other end closing means, and selecting means serving to select which of said cartons are turned as aforesaid and thus which of said cartons remain unturned by said turning means.
According to a further aspect of the present invention, there is provided packaging apparatus including mandrel mounting means, and one end closing means arranged to close one end of a carton sleeve encircling a mandrel carried by said mandrel mounting means, wherein the improvement comprises turning means arranged to turn said mandrel mounting means through substantially a right-angle about an axis which substantially coincides with the longitudinal axis of the mandrel.
Owing to the invention, it is possible to turn selected cartons through substantially a right-angle whilst other cartons remain unturned. In a particular application of the invention, the time and trouble needed to change a packaging machine over from filling one design of carton to another design of carton is greatly reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention may be clearly understood and readily carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:
FIG. 1 shows a perspective view of a half-gallon carton sleeve,
FIG. 2 shows a view similar to FIG. 1 of a liter carton sleeve,
FIG. 3 shows a diagrammatic perspective view of a stepping turntable of a liquid packaging machine,
FIG. 4 shows a fragmentary top plan view of one of eight mandrel-mounting devices of the turntable,
FIG. 5 shows a side elevation, partly in vertical section, of the mandrel-mounting device,
FIG. 6 shows a diagrammatic top plan view of the stepping of mandrels carried by the turntable, and
FIG. 7 shows a diagrammatic side elevation of the machine.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, the half-gallon carton sleeve C shown is conventional and has a bottom closure consisting of two major panels 1 which are situated opposite each other and are substantially rectangular, and two minor panels 2 which are also situated opposite each other and are substantially rectangular, and two minor panels 1 which are situated opposite each other and are substantially rectangular, and two minor panels 2 which are also situated opposite each other and are substantially rectangular. However, each minor panel 2 consists of three triangular sub-panels 3, 4 and 5, of which the sub-panels 3 and 5 are disposed at opposite sides of the sub-panel 4, which is of substantially isosceles form. The sleeve C also includes a flat- or gable-top closure which includes two major panels 6 substantially co-planar with the respective panels 1 and of substantially rectangular form, and two minor panels 7 substantially co-planar with the respective panels 2. Again, each minor panel 7 includes three triangular sub-panels 8, 9 and 10, whereof the sub-panel 9 is of substantially isosceles form. In forming the bottom closure, the panels 1 are turned inwardly about their inner horizontal edges, the panels 2 fold either inwardly or outwardly and the free edge zones of the panels 1 and 2 are heat-and pressure-sealed together. Thus, there is formed an open-topped carton which is then filled with a fluid substance, for example milk or orange juice. Then, to form the flat-or gable-top closure, the panels 6 are turned about their innermost horizontal edges, the panels 7 fold inwardly or outwardly, and the outermost horizontal edge zones of the panels 6 and 7 are heat-and pressure-sealed together. It will be noted that the axes of turning of the panels 1 and 6 are parallel to each other.
The liter carton sleeve C' shown in FIG. 2 again has the panels 1, 2, 6 and 7 and the sub-panels 3 to 5 and 8 to 10, but the panels 1, prior to turning, lie in parallel vertical planes substantially perpendicular to those in which lie the panels 6, the axes of turning of the panels 1 being perpendicular to the axes of turning of the panels 6.
Referring to FIG. 7, carton sleeves C are fed in a flat form from a magazine 101, opened to a rectangular form, and bottom-closed on a rotary turret 102, and then top pre-broken at a top closure pre-breaking station 103, filled at one or more filling stations 104, top-heated at a top closure heating station 105, and closed and sealed at a top closure pressure sealing station 106, while being advanced along the machine by a conveyor 107.
Referring to FIGS. 3 to 6, the turret 102 includes a horizontal turntable 20 which rotates stepwise about a vertical axis A and thereby advances eight mandrels 21 through respective stations I to VIII. Flat carton sleeves from a feeder 19 at the station I are opened and placed upwardly over the mandrel 21 at that station. The mandrel in question together with its carton sleeve is then stepped to a bottom closure pre-breaking station II, then to a bottom closure heating station III, thence to a bottom closure pressure sealing station IV, thence to a station V, and to an unloading station VI where the bottom-closed open-topped cartons are advanced by a chain conveyor (not shown) along a horizontal path X through the top closure pre-breaking station 103, the filling station(s) 104, the top closure heating station 105 and the top closure Pressure sealing station 106.
The turning of the bottom closure panels 1 takes place initially in the station II and finally in the station IV, in both of which the turning devices (not shown) act perpendicularly to the tangent to the table 20, i.e. perpendicularly to the tangent to the circular path of the mandrels 21. The turning of the top closure panels 6 takes place initially at the top closure pre-breaking station 103 and finally at the top closure sealing station 106 and the turning devices at these stations act perpendicularly to the path X, which extends radially from the axis A. Because the orientations of the bottom closure and the top closure of the liter carton C' are perpendicular to each other, as already explained with reference to FIG. 2, assuming that the liter carton sleeve C' is correctly orientated upon the mandrel at the loading station I, so that the bottom closure is correctly presented at the stations II and IV, then the top closure will be correctly presented at the top closure pre-breaking station 103 and the top closure sealing station 106. However, this would not apply to the half-gallon carton, because its top and bottom closures are orientated parallelly to each other, as already explained with reference to FIG. 1. Therefore, some means is required to turn the bottom-closed, open-topped, half-gallon carton C through 90 degrees about its own longitudinal (i.e. vertical) axis between the station IV and the top closure pre-breaking station 103. In the example shown in FIGS. 3 to 6, this is achieved by arranging for the mounting of each mandrel 21 to be rotated through 90 degrees about its own vertical axis as it leaves the station IV. Referring to FIGS. 4 and 5, each mandrel 21 (not shown in these FIGURES) is mounted upon the table by a mounting device 22 which includes a mounting bush 23 which extends through a vertical cylindrical bore 24 in the table 20 and which at its lower end includes a flange 25 carrying a lip seal 26 acting against the underneath surface of the table 20. The mandrels 21 are replaceably mounted upon the mounting devices 22 so that the size of the mandrels mounted at any one time can be selected to suit the size of the carton sleeves. To the upper end of the bush 23 is attached a circular, horizontal plate 27 also carrying at its outer periphery an annular lip seal 28 acting against the top surface of the table 20. The plate 27 is centred on the bush 23 by a central pin 36 extending into blind vertical bores in the plate 27 and the bush 23, is releasably attached to the bush and to the mandrel by two diametrically opposite headed screws 29 and is correctly located relative to the bush 23 by a locating dowel 30 extending into blind vertical bores in the bush 23 and the plate 27. Flanged, upper and lower bearing sleeves 31 and 32 rotatably support in the bore 24 the mounting formed by the bush 23 and the plate 27. In a vertical through bore 33 in the plate 27 is mounted a spring device 34 and, below that, a ball 35 which is urged by the spring device 34 to bear against the top surface of the flange 36 of the upper tearing sleeve 31. There are formed in this top surface at respective locations, spaced through 90 degrees about the vertical axis Y of the device 22, two recess-form detents. The spring device 34 bears against a circular cover plate 37 which is co-axial with the plate 27 and is attached thereto by means of screws 38. Mounted upon the top of the plate 27 so as to be rotatable about respective vertical axes spaced apart through 90 degrees around the axis Y are two needle roller followers 39 and 40.
In the zone of the station IV is a cam 41 which is removably fixed in the path of the follower 39, so that, as the follower 39 moves away from the station IV, the follower 39 is turned through 90 degrees about the axis Y and so turns the mounting device 22 and the mandrel 21 through the same angle, bringing the ball 35 from engagement in one detent into engagement in the other detent. This turning of the half-gallon carton C through 90 degrees is illustrated in FIGS. 3 and 6, it being understood that the cam 41 is removed from the path of the followers 39 for the liter cartons C'. After the cartons C have been removed from the turntable 20 at the station VI, the mandrel moves into the station VII and, as it moves from that station, a cam 42 permanently fixed in the path of the followers 40 swings the follower 40 and thus the mandrel 21 tack through 90 degrees about the axis Y. It will be understood that it is not necessary for the cam 42 to be retractable, because its illustrated position is out of the paths of the followers 39 and 40 for liter cartons C'.
If desired, the cover plate 37 can be provided with a bush-form extension 37' shown in dot-dash lines in FIG. 5 to bear upwardly against a support (not shown) at the station IV to absorb the force applied to the base of the mandrel during the pressure-sealing of the bottom closure at the station.
If desired, each mandrel 21 can be arranged to be water-cooled through the mounting device 22.
The apparatus described with reference to FIGS. 3 to 6 has the advantage that, because of the oscillatability of the mandrel, the machine layout for the cartons C and C' with differing closure orientation can remain the same and the machine width is kept to a reasonable size.
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In a packaging system, carton sleeves are sealingly closed at their bottoms while received upon respective mandrels, the open-topped cartons are removed from the mandrels and filled, and the filled cartons are sealingly closed at their tops. Between the bottoms being sealingly closed and the cartons being filled, selected cartons are turned through a right-angle about their own axes to bring their top closure sealing sub-panels into a correct orientation for top-sealing. For enabling such turning the mandrels are turnable about their own axes by a cam displaceable between operative and inoperative positions.
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BACKGROUND OF THE INVENTION
The present invention relates to a radioprotective screen, and more particularly a screen used in medicine or other to protect an operator against ionising radiation emissions, for instance the X or gamma rays.
For certain interventions on patients, such as catheterism type, placement of pacemaker, vascular, neurological or urological tests . . . the operator (technician, doctor, surgeon or other) must be protected against the ionising radiations to which the patient is exposed.
The existing protection structures consist of clothing such as vests, jackets or aprons made of radioprotective material.
There exist also screens made of panels or assemblies of panels of appropriate material placed vertically and directly on the ground or by dint of a supporting skid.
But the clothes of radioprotective material do not ensure optimal protection for the operator, since in particular they do not cover the whole body (head, legs, arms and feet), and also since weight loads to which these clothes are exposed. On the other hand, the current radioprotective screens, for example as described in the documents U.S. Pat. No. 3,308,297 or EP-A-0 345 548, are not adapted to enable an operator to work comfortably and in complete safety.
SUMMARY OF THE INVENTION
The present invention provides a new structure of radioprotective screen which is particularly efficient and interesting for the operator on an ergonomic plane.
The object of the invention provides on the one hand better visibility for the operator, and on the other hand greater comfort when being placed behind the screen, within the framework of his intervention. This operator thus benefits from better working conditions, without wearing heavy clothes, which enables him to intervene with greater accuracy and higher efficiency, and thus in complete safety.
The radioprotective screen according to the present invention consists of a front wall, associated with a side wall which extends at right angle or substantially at right angle from one of the sides of said front wall, and both these walls include transparent panels over a portion at least of the height thereof. The upper section of the front wall is tilted forward, thereby overhanging, for enabling the operator to come closer to the intervention zone, and it is fitted with two orifices for letting through said operator's arms.
Still according to the invention, the front wall of the screen is formed of a lower panel vertical or substantially vertical, prolonged by an upper panel whereof a portion at least is made of transparent material, which upper panel is tilted forward, forming an angle ranging between 10 and 30° with respect to the vertical. Preferably, the corresponding angle ranges between 15 and 20° with respect to the vertical.
According to a particular embodiment, the front wall is formed of a lower panel of opaque material which extends over a height ranging between 60 and 100 cm, prolonged by an upper panel which extends up to a level corresponding at least to the operator's height, i.e. of the order of 2 m.
According to another particularity, one at least of the orifices for letting through the operator's arms is provided with an oversleeve of radioprotective material intended to grip the operator's wrist or forearm for better protection. This oversleeve is advantageously in the form of an <<iris>>, composed of flexible strips mounted on a circular crown. This crown may be associated with the rim of said orifice by any appropriate means, such a push-button for instance; and the strips, four in number for instance, made of leaded rubber-type material, overlap and are preferably maintained by a flexible wristband which is situated outside, close to the external mouthpiece of the oversleeve.
Still according to the invention, one of the orifices for letting through the arms is situated close to the angle formed by the front and lateral walls, and the other orifice is situated on the free edge of said front wall, at the same level as the latter and open laterally to facilitate the movement of the corresponding arm.
According to a first possible embodiment, the upper front panel fitted with orifices for letting through the arms includes a lining system composed of a mobile panel. This mobile panel is fitted itself with orifices for letting through the arms, matching the orifices of the front wall; these latter orifices, oblong in shape and oversized with respect to the orifices of said mobile panel, extend over the whole surface scanned by said orifices of said lining panel. This particularity enables to adjust the height of the orifices for letting through the operator's arms.
Preferably, the mobile lining panel is guided on the front wall by means of rails arranged laterally. This mobile panel is on the other hand lockable on the front wall, according to several positions adapted to the height of the operator, by means of an anchoring finger co-operating with an index arranged on the structure of said front wall.
According to another possible embodiment, and still to enable adjustment in height of the orifices for letting through the arms, the front wall and the side wall form an assembly mounted to slide vertically on a frame or substructure fitted with castor wheels.
The screen then includes advantageously a system for controlling the assembly composed of the front wall and the lateral wall, in the form of actuator(s) driven by a control member such as a pedal or a push-button for instance.
Still according to the invention, the lower section of the screen is in the form of a frame or substructure fitted with castor wheels mounted at the different ridges with, moreover, at least one additional castor wheel mounted to protrude on the front face of the front wall, carried by a console, enabling to increase the sustentation perimeter of said screen, and thereby its stability.
According to another arrangement of the invention, the screen includes, attached to the front and lateral walls, or to the chassis or substructure, flexible strips of radioprotective material, such as leaded rubbed for instance, enabling notably to let through pedals, cables or other accessories connected to the material necessary to certain types of medical interventions or others.
According to still another arrangement, the screen includes, on the external and internal faces of the front wall, small bars or profiles enabling the installation of sterile fields, arranged below the level of the orifices for letting through the arms.
According to still another arrangement of the invention, an additional wall of radioprotective material acting as a ceiling, extends at least partially between the front wall and the side wall of the screen.
According to still other particularities, the screen according to the invention includes a flexible curtain for protecting the operator's back, as well as a removable resting arm for supporting said operator.
BRIEF DESCRIPTION OF THE DRAWINGS
But the invention will be further illustrated, without being limited thereto, by the following description of two particular embodiments, given solely for exemplification purposes and represented on the drawings wherein:
FIG. 1 represents, in perspective and as a front three-quarter view, a first possible embodiment of a radioprotective screen according to the present invention;
FIG. 2 represents the screen of FIG. 1 , still in perspective, showing its inner portion;
FIG. 3 represents, at enlarged scale, a protective oversleeve in the form of iris, adaptable at the circular orifice for letting through an arm, and in particular the left arm of the operator in the example of screen represented on FIGS. 1 and 2 ;
FIG. 4 is a front view of a second possible embodiment of a radioprotective screen according to the invention;
FIG. 5 shows the screen of FIG. 4 , in perspective and as a rear three-quarter view;
FIG. 6 is a perspective, rear three-quarter view, of the screen illustrated on FIGS. 4 and 5 .
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As represented on FIGS. 1 and 2 , the radioprotective screen comprises a front wall 1 and, arranged at right angle or substantially at right angle, a side wall 2 .
The upper section of the screen includes an additional wall acting as a ceiling 3 , which may extend on the space, in all or in part, situated between the upper rims of the front 1 and lateral 2 walls.
This type of screen, intended to protect an operator against ionising radiation emissions, is composed of panels of appropriate radioprotective material. The different panels are supported by a metal skeleton, for instance of aluminium, which integrates a shield enabling continuous radioprotection at all the junctions.
This screen comprises lower panels which are opaque (for instance made of wooden panels shielded with lead sheets), and upper panels which are transparent (for instance of leaded glass or leaded Plexiglas) to provide front and lateral visibility to the operator which intervenes notably in medicine, for operations where the patient is exposed to radiations.
The substructure 4 of the screen is fitted with castor wheels 5 which enable easy displacement thereof. It should be noted that the castor wheels 5 are arranged at each ridge of the lateral and front walls; on the other hand, additional castor wheels 5 ′ are arranged before the front wall 1 , supported by consoles 6 integral therewith, in order to increase the surface of the sustentation perimeter of the screen, and hence the stability thereof. The different castor wheels 5 , 5 ′ are preferably pivoting and fitted with a releasable unlocking brake.
The front wall 1 comprises a lower section 7 composed of a vertical opaque panel, and of an upper section 8 composed of a transparent panel.
This transparent panel 8 is tilted forward, i.e. towards the operating field. Its tilt, of an angle a ranging between 10 and 30° with respect to the vertical, and preferably ranging between 15 and 20°, enables the operator to lean forward during intervention, and thus to come closer to the operating zone, for greater visibility and greater comfort, notably.
The side wall 2 extends vertically sideways; it also includes a lower opaque panel 9 and an upper transparent panel 10 which provides lateral visibility to the operator, in particular for monitoring his patient. This side wall 2 matches the dihedral shape of the front wall 1 ; the transparent panel 10 has substantially trapezoid shape.
The ceiling wall 3 is here made of transparent material, but it might similarly be made of opaque material if greater visibility is irrelevant.
The dimensions of the different walls are selected to enable reception of all operators' heights. Thus, the front wall 1 and the side wall 2 may be of the order of 2 m in height, for instance.
The lower panel 7 of the front wall 1 extends up to a point which corresponds for instance to the operating table; this lower panel may extend over a height ranging between 60 and 100 cm, preferably close to 80 cm.
The upper transparent panel 8 of the front wall 1 extends therefore between the level of the operating table, i.e. environ 80 cm, and a height of the order of 2 m. It includes in its lower section, i.e. above the operating table, orifices 11 and 12 for letting through the operator's arms, to enable the latter to intervene on a patient, and thus practically and reliably.
Particular means are provided on this radioprotective screen to enable to move vertically the orifices 11 and 12 for letting the arms through, to order possibly to adapt their level according to the height of the operator.
Thus, these orifices 11 and 12 are arranged, on the one hand in the panel 8 of the front wall 1 , and on the other hand in a lining panel 13 arranged inside the screen. This internal lining panel 13 is arranged on the internal face of the upper panel 8 of the front wall 1 ; it is provided mobile parallel to said panel 8 , guided into lateral rails 14 and 15 integral with the front wall 1 , and its position is established by means of an index 16 co-operating with an anchoring finger 17 . The indexing finger 16 is composed of several orifices spaced vertically on the lateral rim of the panel 8 ; the anchoring finger 17 is integral with the mobile panel 13 and it is arranged to engage into one of the orifices of the index 16 , relative to the level of positioning requested of the orifices 11 and 12 for letting through the arms.
The orifices 11 and 12 arranged in the mobile panel 13 are advantageously fitted with rings 18 , 19 , which can be disassembled and treated in an autoclave readily, fastened by means of captive screws.
The panel 8 of the front wall 1 includes orifices 11 ′ and 12 ′ oblong in shape, oversized with respect to the orifices 11 and 12 of the mobile panel 13 , and whereof the sizes, shapes and positions are adapted to the travel of said lining panel 13 . These orifices 11 ′ and 12 ′ remain masked permanently by the lining panel 13 , regardless of the positioning thereof.
The lining panel 13 is for instance made of the same radioprotective material as the upper panel 8 of the front wall 1 .
The orifice 11 situated in the mobile panel 13 is a circular orifice; it is situated close to the angle formed by the front 1 and lateral 2 walls. This circular orifice 11 is adapted for letting through the operator's left arm, for the embodiment represented on FIGS. 1 and 2 .
The orifice 12 provided in the mobile panel 13 is arranged towards the free rim of the front wall 1 , and it is open laterally, actually in the form of a horizontal U to enable the operator to remove his arm easily and to keep great freedom of movement.
For increased protection of the operator, the passage of the ionising radiations through the orifice 11 should be limited by fitting said orifice with a protection oversleeve 25 in the form of an <<iris>>. This iris 25 is represented individually on FIG. 3 . It is composed of an assembly of strips 26 , here four in number, which overlap partially and which are attached to a circular crown 27 whereof the diameter correspond substantially to the diameter of the orifice 11 .
These strips 26 are for instance made of leaded rubber-type material; they are preferably retained elastically at their mouthpiece, by means of a wristband 28 .
The oversleeve 25 in the form of iris is fixed in the orifice 11 , on the ring 18 , by dint of its circular crown 27 , by means of a system of push-buttons 29 for instance.
On FIGS. 1 and 2 , it can be noted that the screen according to the invention is fitted with small bars or profiles 30 , on the one hand on the lining panel 13 , and on the other hand on the external face of the panel 8 , intended notably for the attachment of sterile fields. On the internal face of the panel 7 , the presence of two handling grips 31 should also be noted.
At its lower section, i.e. between the frame or substructure 4 on which the castor wheels 5 , 5 ′ are fixed and the ground, the screen includes a flexible protection apron composed of a juxtaposition of strips 32 . These strips 32 may superimpose each other partially; they are made of leaded rubbed, for instance, and they let through accessories such as control cables or pedals useful for certain types of intervention.
These strips 32 are attached by any appropriate means to the lower section of the panels 7 and 9 of the walls 1 and 2 respectively.
FIGS. 4 to 6 show an embodiment variation of a radioprotective screen according to the invention.
In this embodiment variation, the sections common to the previous embodiment keep the same reference signs for easier understanding thereof.
The front wall 1 , the side wall 2 and the ceiling wall 3 supported by a frame or substructure 4 fitted with castor wheels 5 can be seen.
The front wall 1 comprises a lower section 7 composed of a vertical opaque panel, and a upper section 8 tilted forward by an angle ranging between 10 and 30° (and preferably between 15 and 20°) with respect to the vertical. This upper section 8 comprises an opaque zone 34 situated in the alignment of the lower panel 7 , fitted with two orifices 11 and 12 for letting through the operator's arms; this opaque zone 34 is topped with a transparent zone 35 .
The orifice 11 is circular and it is associated with a protection oversleeve 25 protruding outwardly; the orifice 12 is in the form of a horizontal U, open laterally. As for the embodiment described previously, the orifices 11 and 12 are advantageously fitted with dismountable rings.
The side wall 2 extends vertically and it includes a lower opaque section 9 topped with an upper transparent section 10 . In this embodiment, the ceiling wall 3 is opaque.
The front 1 and lateral 2 walls as well as the ceiling 3 are supported by a metal skeleton of shielded aluminium.
This metal skeleton may be adjustable in height with respect to the supporting substructure 4 , in order possibly to adapt the level of the orifices 11 and 12 according to the operator's height. This possibility of adjustment, illustrated by the double arrow 36 of FIG. 4 , is obtained by a sliding assembly of the metal skeleton in question on the substructure 4 . This sliding assembly may for instance be realised by means of guiding slides integral with the substructure, engaging into the vertical stanchions of the metal skeleton; one or several actuators, of hydraulic type or others, form the control system of the movement, driven by a control member such as pedal, push-button, joystick or other.
The corresponding adjustment system does not show on the figures.
As can be seen on FIGS. 4 to 6 , the screen according to the invention includes a flexible curtain 37 enabling the protection of the operator's back. This flexible curtain 37 is advantageously composed of a juxtaposition of flexible strips 38 of leaded rubber, mounted on a supporting arm 39 fixed cantilever to the upper section of the screen, for instance on the free rim of the ceiling wall 3 , or on the upper rim of the side wall 2 .
Preferably, the supporting arm 39 is mounted articulated around a vertical axis to enable placement and retraction of the curtain, or simply for adjusting its position behind the operator.
This flexible curtain 37 forms a kind of mobile wall for efficient and complete radioprotection.
FIG. 5 also shows the presence of an arm 40 which extends horizontally, cantilever from the side wall 2 , substantially halfway up the screen, intended to serve as a resting member for the operator's back or kidneys.
This resting and supporting arm 40 is preferably removable; it may be mounted articulated on the side wall 2 , associated with a retractable cross-bracing rod.
FIGS. 4 to 6 also show the presence of the strips 32 of leaded rubber, supplementing the protection at the lower section, in the alignment of the front 1 and lateral 2 walls. These protection strips 32 may be attached to the substructure 4 and/or on the lower rim des front 1 and lateral 2 walls.
The different accessories described, such as profile 30 , curtain 37 or resting arm 40 may form optional equipment and be arranged individually or in combination on either of both embodiments described, or on neighbouring versions.
The open orifice 12 may possibly include a kind of protection oversleeve, similar to the oversleeve 25 but open laterally. On the other hand, the screen may include two circular orifices for letting the arms through; in such a case, both these orifices will be advantageously fitted with protection oversleeves 25 .
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A protective screen includes a front wall ( 1), connected to a lateral wall ( 2) running perpendicular or essentially perpendicular to the front wall ( 1), the walls ( 1, 2) including transparent panels ( 8, 10) over at least a part of the height thereof. The upper part ( 8) of the front wall ( 1) is inclined forwards, forming an overhang which permits the operator to approach the working region and with two holes ( 11, 12) to permit the passage of the operator's arms.
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BACKGROUND OF THE INVENTION
Printed wiring boards generally have such a structure as shown in FIGS. 1 and 2 of the accompanying drawings. FIG. 1 is a plan view showing a wiring surface 2 of a printed wiring board 1, and FIG. 2 is a sectional view of the printed wiring board shown in FIG. 1, taken along the line II--II. In FIGS. 1 and 2, reference numerals 4 and 5 denote conductor pieces constituting a wiring pattern formed of a conductor foil such as a copper foil, 6 plated through holes for electrically connecting the wiring surface 2 with the back wiring surface 3, 7 an insulating substrate, and 13 and 14 conductor pieces constituting an internal layer pattern used respectively as ground and power layers and formed of a conductor foil such as a copper foil. The wiring pattern shown in FIG. 1 is formed by transferring a pattern which is indicated by solid lines (excepting heavy lines) and dotted lines in FIG. 1, on a copper foil in the form of an etching resist pattern by the use of a photographic plate (or a mask), and by etching the copper foil. When dust adheres to the photographic plate or a flaw is produced therein, there appear on the wiring pattern 2 a fine undesired pattern 8, a fine partial lack of pattern 9, and a fine projection 10. Further, the thickening 11 or thinning 12 of pattern is produced according as the etching operation is performed insufficiently or excessively. Such defects as above give rise to various problems. That is, the fine partial lack of pattern 9 and the thinning of pattern 12 increase the electric resistance of the pattern, decrease the current capacity of the pattern, and give rise to disconnection when the printed wiring board is subjected to slight rubbing. The fine undesired pattern 8, the fine projection 10 and the thickening 11 of pattern give rise to a short circuit, or a solder bridge in soldering process. As a result, a correct (or desired) wiring cannot be formed on the printed wiring board. Specifically, in a recent high density mounting which employs, for example, a pattern width of 0.1 mm, it is required to detect the above-mentioned defects without overlooking them. However, since such detection cannot be made by visual inspection, the apparatus shown in FIG. 3 is employed in which an optical image is formed for each of the printed wiring boards 1 to be inspected and another printed wiring board 1' for comparison and collation to be compared and collated with each other. The conventional method employing the above-mentioned apparatus will be explained below. In FIG. 3 which shows a conventional apparatus for inspection of printed wiring boards, the same structures are arranged on the right and left sides with the exception of electrical-signal collating device 27, and the part on the right side corresponding to each of the parts on the left side is given the same reference numeral with prime. Explanation will not be made on the function and operation of each part on the right side, because the explanation thereof is given by replacing a reference numeral by the same reference numeral with prime in the following explanation made on the function and operation of each part on the left side. Above the wiring surface 2 of the printed wiring board 1 are disposed a half reflecting mirror 23 which reflects the horizontal light from a light source 21 to produce the light incident upon the wiring surface 2, and through which the reflected light from the wiring surface 2 travels upward, a refractor 24 which converges the light having passed through the mirror 23 to form an optical image, and a photodiode array 25 which is placed in an image forming plane and converts a pattern of light and darkness in the formed image into a multiplicity of electrical signals 26. Further, a collating device 27 is provided in which both the electrical signals 26 delivered from the left photodiode array 25 and the electrical signals 26' delivered from a right-hand side photodiode array 25' are recognized as wiring patterns, and are compared and collated with each other to point out the presence or absence of defects or positions where the defects exist. The positioning of each of the printed wiring boards 1 and 1' is made by positioning means (not shown). Now, explanation will be made on a case where, for example, a printed wiring board shown in FIG. 4a is inspected. Referring to FIG. 3, the light emitted from the light source 21 is passed through a refractor 22 to form parallel rays, directed downward by the half reflecting mirror 23, and then incident upon various portions on the wiring surface 2 of the printed wiring board 1 as light rays 31, 32 and 33 shown in FIG. 4a. The light ray 31 is reflected back as the reflected light ray 41 of a low intensity level due to a low reflectivity of the insulating substrate 7, the light ray 32 is reflected back as the reflected light ray 42 of a high intensity level due to a high reflectivity of the wiring pattern 5 made of a metal such as copper, and the light ray 33 does not give rise to reflected light because it goes past to the back wiring surface 3 through the plated through hole 6 or a perforation. The reflected light rays 41 and 42 which are directed upward, are incident upon the surface of the photodiode array 25 through the half reflecting mirror 23 and the refractor 24 to form an optical image. The photodiode array 25 includes a multiplicity of fine photodiodes (or light receiving elements) which are arranged on a straight line. For example, 256 photodiodes are arranged on a straight line as long as 5 mm. FIG. 4b is a waveform chart for showing electrical signals generated by the individual photodiodes when the light rays 41 and 42 form the optical image. In FIG. 4b, the abscissa designates the location of each photodiode of the photodiode array 25, and the ordinate the level of each of the electrical signals. Further, reference symbol I 1 denotes the level of electrical signals corresponding to the position of the plated through hole 6, which is low due to the absence of reflected light, I 2 the level of electrical signals into which the reflected light from the insulating substrate 7 is converted, which level is low but higher than I 1 , and I 3 the level of electrical signals into which the reflected light from the wiring pattern 5 is converted, which level is high. In order to facilitate the comparison of these levels, it is necessary for these three levels to be converted into two kinds of levels (light and dark levels) or binary levels. For this reason, there is provided a binary coder 28 which is formed of, for example, a voltage comparator, and which translates an electrical signal having a signal level higher than a level I s (shown in FIG. 4b) to the light level and an electrical signal of a signal level lower than the level I s to the dark level. Thus, the electrical signals based upon the wiring pattern 5 are translated to the light level (or "1" level of binary code), and those based upon the insulating substrate 7 and plated through hole 6 are translated to the dark level (or "0" level of binary code). That is, the electrical signals delivered from the photodiode array 25 are converted into binary signals. The binary signals thus obtained form linear information (that is, such linear information as viewing the pattern of FIG. 5a across the line V b --V b ), since the light receiving surface of the photodiode array 25 has a form of a line. Accordingly, by storing these binary signals in a memory 29 while displacing the printed wiring board 1 in parallel in the plane containing the wiring surface 2, the plane information can be obtained. Then, the plane information on the wiring surface 2 and that on the wiring surface 2', both of which have been stored in the memory 29, are collated with each other at a pattern comparator 30 to indicate those parts which correspond to but are incongruous with each other, as a defect.
According to the above-mentioned inspecting apparatus, since the light rays 31 and 32 are incident upon the wiring surface 2 from above as shown in FIG. 4a, the reflected light rays 41 and 42 are directed upwardly as far as the wiring surface is flat, and positively converged by the refractor 24 to form an optical image, a light and dark pattern of which is converted to an electrical signal 26 by each photodiode in the photodiode array 25. The plated through holes 6 included in the wiring pattern usually expand at its opening portion on the wiring surface 2 so that the wall defining the hole has a corner 15 rounded at the opening portion, as shown in FIG. 2. As a result, the light incident upon the curved surface of the corner 15 cannot be reflected upwardly pursuant to the law of light ray reflection. Accordingly, the reflected light is not converged by the refractor 24, failing to take part in the production of pattern information and a diameter larger than that of an actual plated through hole is recognized. Therefore, the conventional inspecting apparatus in which light is incident upon the wiring surface from above is disadvantageously invalid for inspecting pattern information concerning the corner of the wall of the plated through hole, which corner is simply referred to as a plated through hole corner hereinafter.
To detail a defect at a plated through hole corner, reference is now made to FIGS. 5a and 5b. FIG. 5a is a plan view showing a wiring surface 2 of a printed wiring board 1, and FIG. 5b is a sectional view of the printed wiring board shown in FIG. 5a, taken along line V b--V b . In fabricating a printed wiring board by using an etching resist in the form of a dry film, a defect 16 at a plated through hole corner as shown in FIG. 5a often takes place when a dry film tent applied over the plated through hole for protecting the same is damaged during the etching treatment. The presence of the defect tends to cause troubles in soldering parts to the printed wiring board and breakage of the plated through hole corner.
SUMMARY OF THE INVENTION
The present invention contemplates elimination of the above drawbacks and has for its object to provide a method and an apparatus for inspecting printed wiring boards which can detect a defect at a plated through hole corner as well as other defects in the wiring pattern.
To accomplish the above object, the present invention is generally featured by, in addition to illuminating a wiring surface of a printed wiring board with light incident upon the wiring surface in the normal direction thereto, illuminating the wiring surface with light directed at a large incident angle to the wiring surface, that is, at an angle near 90° in terms of the incident angle with respect to the normal to the wiring surface, whereby reflected light rays from a curved surface of a plated through hole corner are directed upwardly, positively converged by a refractor to form an optical image, and a light and dark pattern of the optical image is converted to an electrical signal by a photodiode array.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an enlarged plan view showing a part of a general printed wiring board.
FIG. 2 is a sectional view taken along line II--II in FIG. 1.
FIG. 3, FIG. 4a and FIG. 4b are diagrams useful for explaining a conventional apparatus for inspecting printed wiring boards.
FIGS. 5a and 5b are diagrams useful for explaining a defect at a plated through hole corner.
FIG. 6 is a schematic diagrammatic representation showing an embodiment of an apparatus for inspecting printed wiring boards according to the present invention.
FIGS. 7a, 7b and 7c are diagrams showing details of the apparatus shown in FIG. 6.
FIG. 8 is a diagram for explaining the operation of the embodiment shown in FIG. 6.
FIGS. 9a, 9b, 9c, 10 and 11 are graphic representations useful for explaining electrical signals generated in the apparatus shown in FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring first to FIG. 6 showing an apparatus for inspecting printed wiring boards embodying the invention, reference numerals 51 and 51' denote additional sources of light, independent of sources 21 and 21', which are disposed around a wiring surface 2 of a printed wiring board 1 to be inspected and a wiring surface 2' of a reference printed wiring board 1' and which are adapted to emit light for illuminating these wiring surfaces at a small angle with respect thereto that is, at a large incident angle, and 52 and 52' optical glass fibers for guiding the light emitted from the light sources 51 and 51' to inspection areas on the individual wiring surfaces 2 and 2'. A single light source may be provided serving as the sources 21 and 21'. Similarly, another light source may be provided serving as the sources 51 and 51'. Further, the wiring surfaces 2 and 2' may be illuminated at a large incident angle with light travelling through, for example, mirrors 61 and 62 as shown in FIG. 7b or mirror 62 and prism 63 as shown in FIG. 7c, without resort to the optical glass fibers 52 and 52'. Explanation will not be made on elements 21 to 26, 21' to 26', 27, 28, 28', 29 and 30 which correspond to like elements in FIG. 3. In FIG. 7a light from the optical glass fiber 52 is a pencil of light rays having a central light ray (illustrated at chained line) at an incident angle of about 70° and outer light rays 34 and 35 at incident angles of 75° and 60°, and is incident upon the wiring surface 2 of the printed wiring board 1. Similarly, in FIGS. 7b and 7c, the incident light pencils have central light ray at 70° and outer light rays 34', 34" and 35' , 35" at 75° and 60°, respectively. In order to obtain pattern information from as large an area of the plated through hole corner as possible, it is desirable to illuminate the wiring surface 2 with light at an incident angle as close to 90° as possible. But an appreciable gap or space from the wiring surface is required for arranging fixture tools or jigs for the printed wiring board 1 and other elements of the inspection apparatus so that an incident angle of about 70° is exemplified in FIGS. 7a, 7b and 7c.
The operation will now be described with reference to FIG. 8 which illustrates, in enlarged sectional form, the plated through hole corner 15 and its neighbourhood of the printed wiring board shown in FIG. 2 with a metal conductor such as of copper hatched. Incident light rays 34 and 35 which are identical to those shown in FIG. 7a are at angles 75° and 60° as measured from vertical lines shown at dotted lines passing the incident points A and B on the plated through hole corner 15. The light rays 34 and 35 are reflected at the plated through hole corner 15 and reflected light rays 44 and 45 are directed to the refractor 24. It will be appreciated that the reflected light rays 44 and 45 are such as deviating from the vertical lines by an angle of 14° since the refractor 24 being constituted by a lens of 85 mm F/1.0 in the embodiment has a field angle of 14°, when used at a magnification of 1 (one).
In this manner, in contrast to the conventional inspecting apparatus which employs only the incident light normal to the wiring surface and hence permits generation of pattern information regarding only a flat surface portion of the wiring pattern 5 which surface portion terminates at a point C preceding the curved surface of the plated through hole corner 15, generation of pattern information can be extended by the light illumination at a large incident angle of the wiring surface according to the present invention, covering the area including an intermediate point A on the plated through hole corner 15. Accordingly, when the wiring pattern is projected upon a boundary plane between the metal conductor and the insulating substrate 7, it is possible to obtain pattern information covering region L between a point D resulting from projecting point C upon the boundary plane and a point E resulting from projecting point A upon the plane, thereby ensuring that a defect at the plated through hole corner can be detected. Thus, the collating device 27 (FIG. 6) which is positioned on the same side of the printed wiring boards as the illuminating arrangements serves for recognizing a plane configuration of the corner as projected upon the horizontal plane by receiving the reflected light rays.
FIGS. 9a, 9b and 9c are waveform charts for showing electrical signals generated corresponding to optical images formed on the photodiode array 25. In these drawings, the abscissa designates the location of each photodiode of the photodiode array 25 and the ordinate the level of each of the electrical signals. Specifically, FIG. 9a shows an electrical signal generated by the photodiode array 25 when illuminating the wiring surface only with light normal thereto with the conventional inspecting apparatus, FIG. 9b shows an electrical signal generated by the photodiode array 25 in accordance with light illumination at a small angle with respect to the wiring surface (i.e., at a large incident angle) featuring the present invention, and FIG. 9c shows an electrical signal generated by the photodiode array 25 in the inspecting apparatus of the present invention in accordance with the illumination with the normal incident light and the illumination with the lateral light directed to the wiring surface at a large incident angle in combination. Accordingly, the electrical signal shown in FIG. 9c represents a sum of the electrical signals of FIG. 9a and FIG. 9b. Reference symbols I 1 , I 1 ' and I 1 " denote the levels of electrical signals corresponding to the position of the plated through holes, which are identical due to the absence of reflected light and related as,
I.sub.1 =I.sub.1 '=I.sub.1 ".
Reference symbols I 2 , I 2 ' and I 2 " denote the levels of electrical signals to which the reflected light rays from the insulating substrate 7 are converted, and I 2 ' and I 2 " are almost equal, i.e.,
I.sub.2 '≈I.sub.2 ".
The electrical signal level I 2 is lower than the electrical signal levels I 2 ' and I 2 " because the insulating substrate 7 has surface irregularity of the order of 10 to 15 microns so that the incident light rays at a large incident angle are scattered and converged by the refractor 24 so as to be sensed by the photodiode array 25. Reference symbol I 3 denotes the level of electrical signal corresponding to the position of the wiring pattern and I 3 ' the level of electrical signal corresponding to the plated through hole corner. The electrical signal level I 3 ' is higher than the electrical signal level I 3 because the surface irregularity of the plated through hole corner is smaller than that of the wiring pattern so that scattered reflection is suppressed.
FIG. 10 shows dependency of the electrical signal level corresponding to the insulating substrate upon the incident angle of light illuminating the wiring surface. In FIG. 10, the ordinate represents electrical signal level I corresponding to the insulating substrate and the abscissa represents incident angle θ of light illuminating the wiring surface. It will be seen from FIG. 10 that when the wiring surface is illuminated with the light from above, that is, when the incident angle θ of light approximates 0°, the electrical signal level corresponding to the insulating substrate is low but as the incident angle θ increases, the level goes higher and reaches a maximum at 60° and is then lowered. Accordingly, it is understood that when the wiring surface is illuminated with the light at a large incident angle directed thereto, that is, when the incident angle θ of light approximates 90°, the electrical signal level corresponding to the insulating substrate is also low. Since high values of the electrical signal level corresponding to the insulating substrate are indistinguishable from the electrical signal level corresponding to the wiring pattern, for such high levels, the binary-level conversion by the binary coder is invalid wherein the electrical signals based upon the wiring pattern are converted to the light level (or "1" level of binary code) and those based upon the insulating substrate are converted to the dark level (or "0" level of binary code). Therefore, it is necessary to utilize the electrical signal level corresponding to the insulating substrate which is as low as possible and in this sense, the light illumination at a small angle with respect to the wiring surface, preferably, at an incident angle θ of 70° to 90° is advantageous.
FIG. 11 shows the relation between the incident angle of light illuminating the wiring surface and the average gradient with which electrical signals representative of optical images of a wiring pattern rise from the electrical signal level (I 1 , I 1 ') for the plated through hole to the signal level (I 3 , I 3 ') for the wiring pattern. In FIG. 11, the ordinate represents the number N of electrical signals observed for a unit voltage, and the abscissa represents the incident angle θ of light illuminating the wiring surface. Here, reference will be briefly made to "the number of electrical signals observed for a unit voltage". The number of electrical signals means the number of bright spots observed on a display screen such as of a synchroscope and corresponding to individual electrical signals produced by photodiodes of the photodiode array having received optical inputs. The photodiodes are arranged with a fixed spacing of, e.g., 20 μm. The illustration in FIGS. 9a, 9b and 9c results from a collection of such bright spots observed on the screen as mentioned above and the amplitude may represent the output voltage of the photodiodes. Thus, a number of the bright spots can be determined for a unit length of the amplitude, i.e., for a unit voltage and this number of the bright spots or the number of the electrical signals for a unit voltage indicates the gradient of a waveform of the electrical signal corresponding to an optical image of the wiring pattern. If the number for a unit voltage is large the gradient is small while if the number for a unit voltage is small the gradient is large. It will be seen from FIG. 11 that when the wiring surface is illuminated with light from above, that is, when the incident angle θ of light approximates 0°, the number N of electrical signals for a unit voltage is large so that the electrical signal rises with a small gradient whereas as the incident angle of light illuminating the wiring surface ihcreases, the number of the electrical signals for a unit voltage decreases so that the electrical signal rises with a steep gradient. For the case of FIG. 9a, the number of electrical signals for a unit voltage amounts to an average of 5.4 in order that the electrical signal rises from the electrical signal level I 1 for the position of the plated through hole to that I 3 for the wiring pattern. For the case of FIG. 9b, the number of individual electrical signals amounts to an average of 1.9 in order that the electrical signal rises from the electrical signal level I 1 ' for the position of the plated through hole to that I 3 ' for the plated through hole corner. Accordingly, the difference is 3.5, representing information regarding the plated through hole corner and which is obtained based on the light illumination at a large incident angle directed to the wiring surface. This difference is converted to a dimensional length of 20×3.5 =70 μm when the pitch or the spacing between adjacent photodiodes is 20 μm. In the above discussion, electrical conditions are I 1 , I 1 '=0 V, I s =1 V, and I 3 , I 3 '=2 V.
Thus, the detection of the plated through hole corner can be enhanced by 70 μm by the light illumination at a large incident angle directed to the wiring surface, which means that the diameter of the plated through hole detected by the inspecting apparatus of the present invention may be smaller than that detected by the conventional apparatus by 70 μm. thereby ensuring recognition of an approximately actual diameter.
As has been described, the present invention advantageously employs the light illumination at a large incident angle directed to the wiring surface to obtain pattern information from the plated through hole corner so that the approximately actual diameter of the plated through hole can be recognized and the defect at the plated through hole corner can be detected.
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In order to optically inspect wiring patterns on a printed wiring board, laterally travelling light rays are passed through a half reflecting mirror disposed above the printed wiring board so as to be directed downwardly, thereby illuminating a wiring surface of the printed wiring board with the light normal thereto and at the same time light is directed at a large incident angle to the wiring surface through, for example, optical glass fibers to illuminate the wiring surface, whereby a corner which is a part of the wall defining a plated through hole formed in the printed wiring board can be detected as an accurate optical image, thus ensuring a highly accurate inspection of the wiring patterns.
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FIELD OF THE INVENTION
[0001] The present invention relates to a key identification apparatus, and more particularly, to a key tag.
BACKGROUND OF THE INVENTION
[0002] A conventional key tag, generally made by plastic, leather or a metallic material in single-piece structure, allows a user to label with text or symbols thereon with a marker for identification purposes. However, such key tag is usually good for one-time use only. Further, the text or symbols labeled on the conventional key tag are prone to disengagement due to exposure to external abrasions such that the originally intended identification function may be lost.
SUMMARY OF THE INVENTION
[0003] It is an objective of the present disclosure to provide a key tag that allows a user to change a tag sheet thereof for repeated use.
[0004] It is another objective of the present invention to provide a key tag in which a cover sheet and a body are adaptively engaged to protect a tag sheet thereof from external abrasions, thereby maintaining its identification function intact.
[0005] To achieve the objectives above, a key tag according to the present invention comprises: a body, having a recess and a through hole near its one end; a tag sheet received in the recess; and a cover sheet adaptively engaged with the body so as to confine the tag sheet within the recess.
[0006] According to the key tag of the present invention, the key tag further comprises an opening penetrating through the recess.
[0007] According to the key tag of the present invention, the through hole of the key tag is provided with a connecting ring for interlinking with a key ring.
[0008] According to the key tag of the present invention, the body of the key tag further comprises another through hole near the other end of the body.
[0009] According to the key tag of the present invention, the key tag further comprises a ring portion extended from an end portion of the body to form the another through hole.
[0010] According to the present invention, the cover sheet of the key tag is made of a transparent material.
[0011] According to the present invention, the cover sheet of the key tag is made of a partial transparent material.
[0012] Furthermore, a key tag according to the present invention comprises: a body, having a recess and a projecting portion provided in a projecting manner at a surface of the body, wherein the projecting portion is provided with a through hole; a tag sheet received in the recess; and a cover sheet adaptively engaged with the body so as to confine the tag sheet within the recess.
[0013] According to the key tag of the present invention, the key tag further comprises an opening penetrating through the recess.
[0014] According to the key tag of the present invention, the through hole of the key tag is provided with a connecting ring for interlinking with a key ring.
[0015] According to the key tag of the present invention, the body of the key tag further comprises another through hole near one end of the body.
[0016] According to the key tag of the present invention, the key tag further comprises a ring portion extended from an end portion of the body to form the another through hole.
[0017] According to the present invention, the cover sheet of the key tag is made of a transparent material.
[0018] According to the present invention, the cover sheet of the key tag is made of a partial transparent material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:
[0020] FIG. 1 is an elevational view of a key tag according to a preferred embodiment of the present invention.
[0021] FIG. 2 is a front elevational view of the body 10 in FIG. 1 .
[0022] FIG. 3 is a rear elevational view of the body 10 in FIG. 1 .
[0023] FIG. 4 is a rear elevational view of a key tag according to another preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0024] FIG. 1 shows an elevational view of a key tag according to a preferred embodiment of the present invention. As shown in FIG. 1 , a key tag 1 comprises a body 10 , a tag sheet 12 and a cover sheet 14 . The body 10 comprises a recess 11 for accommodating the tag sheet 12 . By adaptively engaging the cover sheet 14 and the body 10 , the tag sheet 12 is confined in the recess 11 . The cover sheet 14 and the recess 11 are of a same or similar shape and area size in order to cooperate with each other. In this embodiment, the cover sheet 14 and the recess 11 are both rectangular. However, it is apparent to a person skilled in the art that, any shape or pattern is suitable as long as the cover sheet 14 and the recess 11 can be adaptively engaged.
[0025] To allow a user to label the tag sheet 12 with text or symbols, the tag sheet 12 may be made of paper, plastic, acrylic, metal, wood and bamboo, preferably a material that allows adhesion of an ink thereon. Since the cover sheet 14 is capable of protecting the tag sheet 12 from external abrasions, a drawback associated with the prior art that the conventional tag being prone to disengagement due to external abrasions is entirely prevented. Preferably, the cover sheet 14 is made of transparent or partial transparent material to facilitate a user to identify text or symbols on the tag sheet 12 .
[0026] Further, an opening 13 is provided at the recess 11 of the body 10 to penetrate through the recess 11 . When the cover sheet 14 is engaged with the body 10 , in the event that a user wishes to change the tag sheet 12 or modify text or symbols on the tag sheet 12 , the user may press through the opening 13 to disengage the cover sheet 14 from the body 10 . Thus, the user is enabled to modify text or symbols on the tag sheet 12 or directly replace an original tag sheet 12 with a new one.
[0027] Further, the body 10 is respectively provided with a first through hole and a second through hole at two ends thereof. The first through hole 15 is provided with a connecting ring 2 for interlinking with a key ring 3 , which further interlinks with a key (not shown in the drawing). Similarly, the key ring 3 may also be directly interlinked with the first through hole 15 .
[0028] According to the embodiment, the second through hole 16 is formed by a ring portion 17 extending from one end of the body 10 . The second through hole 16 is for placing the key tag 1 to a fixed hook.
[0029] FIG. 2 shows a front elevational view of the body 10 , whereas FIG. 3 shows a rear elevational view of the body 10 .
[0030] FIG. 4 shows a rear elevational view of a key tag according to a preferred embodiment of the present invention. A main difference between the embodiment in FIG. 4 and that in FIGS. 1 to 3 is that, a rear side of the body 10 according to the embodiment in FIG. 4 comprises a projecting portion 18 . In other words, the projecting portion 18 is projected on the rear side of the body 10 , while the first through hole 15 of this embodiment is provided on the projecting portion 18 . As described previously, the first through hole 15 is provided with a connecting ring 2 for interlinking with a key ring 3 , which further interlinks with a key. Similarly, the key ring 3 may also be directly interlinked with the first through hole 15 .
[0031] With description of the embodiments, it is illustrated that a user is allowed to change the tag sheet 12 as desired for repeated use. Further, by adaptively engaging the cover sheet 14 and the body 10 , the tag sheet 12 is protected from external abrasions to keep its identification function intact.
[0032] While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not to be limited to the above embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.
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A key tag includes: a body having a recess and a through hole near its one end, a tag sheet accommodated in the recess, and a cover sheet adaptively engaged with the body so as to confine the tag sheet within the recess.
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FIELD OF THE INVENTION
The invention relates generally to threaded inserts for the rigid fixation of bone screws to bone plates having plate holes. The insert is adapted to be introduced into the plate hole, and to anchor the bone screw to the plate.
BACKGROUND OF THE INVENTION
In orthopaedics, stable fixation is a prerequisite for successful treatment of complex deformity, nonunion, and fracture. Bone plates are commonly used to obtain fixation and are commonly secured to the bone by screws. However, osteoporotic bone or bone with abnormally thinned cortices due to failed fixation or previous infection may not allow lasting screw purchase in the bone. Stability of the fractured bone gained by applying compression across the fracture site is quickly lost as the thin bone resorbs around the screws. This loss of compression is rapid, since loosening of the screws in the bone allows early toggling at the plate/screw interface.
As noted, most bone plates used in osteosynthesis are fixed solely by means of bone screws driven into the bone. Since the bone screws are only secured to bone, there is no rigid fixation of the screw to the bone plate. Therefore a loosening of the bone screws in the bone or a resorption of the bone can easily lead to a loosening of the bone plate.
It is known in plate osteosynthesis to use a nut on the cortex opposite a plate to fix the screw, and therefore the plate, to the bone. This method does not produce a direct fixation between bone screws and plate, but only compression of the bone located between the nut and the plate and penetrated by the screw.
In a variety of indications it is desirable to achieve a rigid fixation between bone screws and a bone plate in order to avoid subsequent loosening. For this purpose U.S. Pat. No. 5,053,036 teaches anchoring by frictional adhesion alone a bone screw with a specially designed conical head to a bone plate having corresponding conical holes. In this device both holes and screw heads must have a specific taper to obtain rigid fixation between them.
In U.S. Pat. No. 4,388,921, a bone screw with a specially designed conical or convex head is used in conjunction with a slotted insert having a matching tapered hole for the screw head. The special bone plate for use with this insert has cylindrical or spherical holes for the inserts. Because the insert is not threaded to receive the bone screw, fixation of the bone screw in the bone plate is dependent on the purchase of the bone screw threads in the bone.
U.S. Pat. No. 5,053,036 discloses a bone screw with a specially designed conical head used in conjunction with a slotted spherical insert in a bone plate. This design also requires the conforming tapers discussed above and in addition requires conforming spherical surfaces on the slotted sphere and in the bone plate.
Threaded conical inserts have been used to expand specially designed screw heads in order to lock the bone plate to the bone screw. Examples of this technique are found in U.S. Pat. Nos. 5,053,036 and 4,484,570. This design also requires conforming tapers on specially designed screws and plates.
U.S. Pat. No. 5,269,784 describes a nut interposed between the plate and the bone surface so that the plate is compressed between the head of the bone screw and the nut. An unthreaded bushing may be required in this arrangement between the screw head and the plate if the bone screw has an unthreaded portion near the head. Because the screw nut is installed on the underside of the bone plate, is must be introduced into the plate hole before or during operative placement of the bone plate. The nut must furthermore be retained in the plate by separate means during placement of the plate on the bone.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a means for locking a bone screw to a bone plate at a fixed angle, using standard bone screws and standard bone plates.
It is a further object to provide an insert for locking a bone screw to a bone plate wherein the insert need not be installed before the plate is placed on the bone.
It is a further object of the invention to provide a locking means for bone screws that does not require precision machining of matching tapers or matching spherical surfaces.
It is a further object of the invention to provide an insert for locking a bone screw to a bone plate wherein the locking function of the insert is not dependent on the purchase of the bone screw in the bone.
It is a further object of the invention to provide a locking insert for bone plates that can be snapped into the plate hole and will remain there until snapped out.
It is a further object of the invention to provide a locking insert for a bone screw that has a central hole inclined at an angle other than 90 degrees for use with a buttress plate.
In accordance with the invention, the noted drawbacks of the existing means of attaching bone screws to plates are overcome by an insert having an upper section and a lower section, a central axis extending through both sections, and a central hole extending along the axis through the insert. The central hole is threaded to engage a bone screw at least where the hole extends through the bottom section of the insert.
The lower section of the insert has slots dividing it into a plurality of tabs, each tab having an external projection. The distance between opposite projections is larger than a corresponding diameter of the plate hole opening. The tabs can be deflected to permit insertion of the external projections through the plate hole opening. Because the tabs must be similarly deflected in order to remove the insert from the plate hole, the insert will remain in place unless pressed out of the plate hole. When a bone screw is engaged in the threaded part of the central hole, the tabs can no longer be deflected and the insert cannot be removed from the plate hole.
The upper section of the insert has a cross sectional area larger than the plate hole, a downwardly facing locking shoulder for contacting the upper edge of the plate hole, and a countersunk surface for receiving the head of the bone screw. Slots divide the upper section into a plurality of sectors.
The insert can be pressed into a plate hole in the bone plate either before or after the plate is installed on the bone. When the bone screw is installed and tightened, the head of the screw contacts the countersunk surface of the insert, causing the sectors of the upper section to spread, clamping the bone plate between the downwardly facing locking surface and the external projections. The threads in the lower section collapse under the resultant forces, thereby preventing the bone screw from backing out.
In one embodiment of the invention, the external shape of the insert is configured for an elongated plate hole. This shape prevents the insert from rotating as the bone screw is driven. In an alternative embodiment, an insert may have an external shape for use in a round plate hole. In this case, a special wrench or other instrument may be used to prevent rotation of the insert while driving the screw.
In a further embodiment of the invention, an insert designed for use in round plate holes has a central hole disposed at an angle to the central axis and oriented at an angle other than 90 degrees to the bone plate. The insert can thereby be rotated prior to locking, enabling the user to aim the screw at any position along the cone formed by rotating the axis of the central hole of the insert around the plate hole. This feature is useful in buttress plates where the orientation of the screw must be adjusted.
One advantage of the threaded insert according to the invention resides in its universal applicability, since it can be used together with standard bone plates and screws. The insert can be used advantageously, for example, with the bone plate described in U.S. Pat. No. 4,493,317 to Klaue.
Inserts according to the invention can be installed individually at selected positions on a bone plate, while using standard bone screws without inserts at other locations. Because the inserts are installed in the bone plate from the side opposite the bone, it is possible to install the inserts after the bone plate has been placed on the bone. It is therefore possible to postpone deciding where to use the inserts until after the bone plate is in place, during the operation.
In a standard bone plate mounting, cycled loads will cause the screw to back out. Forces coaxial to the screw shaft cause the screw to loosen due to the effect of loading the inclined plane of the threads. This problem is magnified when the fragment is not fixed securely to the plate because of toggle occurring at the plate/screw interface. The threaded insert of the invention prevents the bone screw from backing out by collapsing and locking the threads of the insert on the screw. The insert also prevents toggling by holding the screw at a fixed angle with respect to the plate.
The insert of the invention is locked within the bone plate hole by compressive forces generated between the screw head and that portion of the screw threads engaged by the insert. Because the locking forces are contained completely within the insert, the insert remains locked in the bone plate hole independent of any degradation of bone screw purchase caused by mechanical or biological factors.
When tightened, the screw is secured to the plate in a fixed, usually orthogonal position, similar to the situation that is present when a pin is clamped to an external fixation frame. With the screw(s) thus fixed to the plate and bone, several advantages become evident. Firstly, in osteoporotic bone or bone with thin cortices, early loosening due to cycled loads is avoided, since the screws are fixed to the plate, rendering them exempt from the effects of toggling at the plate/screw interface.
Secondly, the insert acts as a mechanical cortex substitute in situations where bone is lost at the near cortex due to trauma or disease. Once the bone screw is locked by the insert, any bone fragment held by the bone screw will be fixed in space, since toggle of the screw with the plate will be eliminated. Therefore, if the bone is deficient adjacent to the bone plate, the surgeon can still place a screw through the opposite cortex, allowing fixation to be distributed over a greater portion of the plate.
Thirdly, the insert allows the bone screw to store some of the energy that is used when generating compression at a fracture or osteotomy site. This provides compression that lasts longer than that provided by a plate with screws, since cycled loads can lead to loosening. This effect is analogous to the preload and compression that is achieved with a ninety degree blade plate.
Finally, by using the insert, a surgeon can convert any portion of a plate into a "fixed pin" device, increasing the plate's versatility as an internal fixation device. When a surgeon wishes to immobilize bone fragments located at a distance from the plate, the insert can be used to prevent toggle at the plate/screw interface, increasing overall stability. The insert rigidly fixes the screw so that the bone fragment is held in a more restrained manner. This effect has been loosely termed the "locked lag technique".
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be disclosed more fully in connection with the accompanying drawings in which:
FIG. 1 is a top view of a threaded insert according to the invention for use in an elongated plate hole;
FIG. 2 is a side elevation view in partial cross section along the lines II--II of FIG. 1;
FIG. 3 is a view in vertical section of a threaded insert according to the invention in position to be assembled into a plate hole;
FIG. 4 is a view in vertical section of a threaded insert according to the invention positioned in a plate hole;
FIG. 5 is a view in vertical section of a threaded insert according to the invention partially positioned in a plate hole, and showing a bone screw partially positioned in the insert;
FIG. 6 is a view in vertical section of a fully assembled threaded insert, bone screw and bone plate according to FIG. 5;
FIG. 7 is a top plan view of a threaded insert according to the invention for use in a round plate hole, in which the central hole is inclined at an angle other than 90 degrees to the plane of the bone plate;
FIG. 8 is a side elevation view in partial cross section along lines VIII--VIII of FIG. 7.
DETAILED DESCRIPTION
The threaded insert comprises an elongated body as shown in FIGS. 1 and 2, usually of metal such as stainless steel, or titanium or other biocompatible material. As best seen in FIG. 2, the insert 1 has a top section 2, a bottom section 3, a top surface 5, and a bottom surface 6. A central axis 4 extends through the top section 2 and the bottom section 3.
Extending along central axis 4 is central hole 10. The central hole 10 has threads 11 for receiving a bone screw (not shown). In the embodiment of FIG. 2 there are threads only in lower section 3, although the central hole in the upper section 2 can also be threaded. Central hole 10 has at the top surface 5 a countersunk surface 12 for contact with the underside of a bone screw head (not shown). Where the underside of a bone screw head is spherical, it has been found that an angle of the countersunk surface 12 of approximately 45 degrees to the central axis 4 works well in developing the necessary forces in the top section 2 as discussed below. Other angles may be used to accommodate other screw geometries or other limitations.
The bottom section 3 comprises a plurality of deflectable tabs 20 that extend downward from the top section 2. In the embodiment shown in FIG. 2, two tabs 20 are disposed so that they will be along a long diameter of the elongated plate hole (not shown), and are separated by Y-shaped slots 21. The Y-shaped configuration of the slots 21 reduces the cross-sectional area of the upper portion of the tabs 20, permitting greater deflection of the tabs as described below.
Each tab 20 comprises an external projection 22 protruding from its outer surface 23. A distance D 1 measured over the external projections 22 orthogonal to the central axis 4 of the insert is slightly larger than a corresponding distance across the long diameter of the elongated plate hole in which the insert is to be seated.
FIG. 3 shows insert 1 of FIGS. 1 and 2 in position to be assembled into plate hole 101 in plate 100. Projections 22 on tabs 20 are disposed along the long diameter of plate hole 101. The distance D 1 between the projections 22 is slightly larger than the distance L along the long axis of the plate hole. One skilled in the art will recognize that other configurations are possible. For example, where an odd number of tabs are to be used in a round plate hole, the inscribed circle through the projections 22 must be slightly larger than the diameter of the plate hole.
As best shown in FIG. 2, each tab 20 further comprises an external lead chamfer 24 on the bottom surface 6, adjacent the external projections 22. The chamfer 24 provides a camming surface for compressing the tabs 20 when the insert 1 is pressed into the plate hole 101, as described below.
The upper section 2 comprises a plurality of sectors 30 separated by slots 31 that extend down from the top surface 5 through the upper section 2. In the insert shown in FIG. 1, four sectors 30 are separated by two slots 31. The slots 31 in the upper section 2 are parallel to and pass through central axis 4.
As best seen in FIG. 1, the upper section 2 has outside profile surfaces 34, 35, separated by flats 33. The distances between surfaces 34 and between surfaces 35 are larger than the corresponding diameters in the opening of the plate hole. For example, FIG. 4 shows an insert 1 that has been installed in a plate hole 101 in plate 100. The distance D 2 between outside profile surfaces 34, which lie on the long diameter of the plate hole 101, is larger than the distance L, the narrowest longitudinal dimension along the long diameter of the plate hole.
As best shown in FIG. 2, each sector 30 of the upper section 2 comprises a downward facing locking shoulder 32 adjacent to and facing the lower section 3. The locking shoulder 32 is disposed at an angle to the central axis 4, forming a convex, conical surface. The angle is selected to facilitate locking the insert in the plate, as described below.
FIGS. 3 through 6 illustrate the steps for installation of the insert of FIGS. 1 and 2. The bone plate hole 101 is of standard geometry, having a plate countersunk surface 102 extending from plate top surface 103, and an undercut chamfer 104 extending from the plate bottom surface 105. The intersection of the plate countersunk surface 102 and the undercut chamfer 104 forms lip 106, defining the opening of plate hole 101. Such a bone plate is described in U.S. Pat. No. 4,493,317, for example.
To install the insert 1 in a plate hole 101, the insert is introduced into the plate hole as shown in FIG. 3, with the central axis 4 of the insert coinciding with the center of the plate hole, and the lead chamfer 24 contacting the bone plate 100. More specifically, the insert lead chamfer 24 contacts the plate countersunk surface 102 of the plate hole 101.
The insert 1 is then pushed in the direction of the bone plate 100, whereupon plate countersunk surface 102 exerts a reaction force on lead chamfer 24. This force deflects tabs 20 inward, reducing distance D 1 . The tabs bend at their upper portions, where the Y-shaped slots 21 have reduced the cross sectional area. When distance D 1 is sufficiently reduced by this deflection so that the projections 22 can pass through the opening defined by lip 106, the insert snaps into plate hole 101 in the position shown in FIG. 4. Projections 22 contact undercut chamfer 104 and slide outward and downward along this surface, pulling the insert into the plate hole 101 until the locking shoulder 32 contacts the plate countersunk surface 102. The insert 1 is thereby retained in the plate hole 101 by the projections 22 and the locking shoulder 32.
FIG. 5 shows the insert 1 in the plate hole 101 after a bone screw 200 has been partially threaded into the insert. External bone screw threads 201 engage threads 11 of central hole 10 in the region of tabs 20. This prevents tabs 20 from deflecting inward, locking tab projections 22 in position under bone plate lip 106, and preventing removal of the insert 1 from the bone plate hole 101.
FIG. 6 shows the insert 1, bone plate 100, and bone screw 200 after the bone screw has been fully tightened. The spherical underside 202 of the bone screw head 203 contacts the countersunk surface 12 of the insert, causing the sectors 30 of the insert to spread apart. This spreading of sectors 30 causes locking shoulder 32 to exert a force on the plate countersunk surface 102. The force causes a small displacement of insert 1 in an upward direction, causing forceful contact of the projections 22 with the underside of lip 106. The insert 1 is thereby locked in position in the plate hole 101.
The resultant force on projections 22 causes tabs 20 to be deflected slightly inward, collapsing threads 11 inward to forcibly engage bone screw threads 201. The forcible thread engagement locks bone screw 200 against loosening by rotation.
FIGS. 7 and 8 show an embodiment of the invention with an angled screw hole for use in applications such as buttress plates. As best shown in FIG. 8, insert 301 has a top section 302, a bottom section 303, a central axis 304, and a partially threaded central hole 310. Bottom section 303 comprises a plurality of deflectable tabs 320 separated by Y-shaped slots 321.
As best seen in FIG. 7, the upper section 302 comprises four sectors 330 separated by two slots 331. Distance D 2 is the same between both pairs of outside profile surfaces 334, 335 because the insert 301 is to be used in a round plate hole. Because the insert is used in a round hole, provision for preventing rotation, such as wrench flats or the like (not shown), must be made for use when the screw is driven.
Central hole 310 of insert 301 is inclined at an angle other than 90 degrees to the bone plate plane 110. As shown in FIG. 8, central hole axis 313 is inclined at angle α to the central axis 304. A bone screw (not shown) engaged in central hole 310 of insert 301 is therefore inclined at an angle other than 90 degrees to the bone plate. The direction of inclination of the bone screw can be changed by rotating insert 301 in the bone plate hole, thereby aiming the screw in any position on a cone formed by rotating axis 313 around axis 304. This embodiment of the invention is particularly useful in buttress plates where the fixed angle of the screw must be adjusted.
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A threaded insert is designed to snap into a standard bone plate hole. The insert has an upper section divided into sectors by slots, a lower section having deflectable tabs with external projections, and a central threaded hole. When a standard bone screw is tightened in the insert, the insert rigidly fixes the screw to the plate by collapsing the threads of the insert onto the threads of the screw, and by expanding the sectors of the upper section to clamp the bone plate.
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FIELD OF THE INVENTION
The present invention relates generally to a slide hammer used with a tire spoon. More particularly, the present invention relates to a slide hammer capable of being altered by the addition of additional weights where the slide hammer may also be used on a tire spoon.
BACKGROUND OF THE INVENTION
Slide hammers are tools that include a weight that is attached to a shaft and can be slid up and down the shaft. Usually at at least one location along the shaft, there is a stop that the slide hammer is rammed against to stop the slide hammer and thereby exert a force on the tool.
For various applications it may be desirable to use various levels or degrees of force with the slide hammer. Changing the level of force exerted by the slide hammer can be done by increasing or decreasing the velocity at which the slide hammer hits the stop. However, in some applications it may be desirable to equip a slide hammer to be able to impart a much larger force against the stop that can normally be done with conventional slide hammers. Slide hammers are sometimes limited in the force that can exert against a stop by several factors. These factors may include the length the shaft in which the slide hammer is able to slide and the weight of the slide hammer.
Furthermore, in some instances, it may be desirable to have a slide hammer that can exert force in two directions. This may be accomplished by a tool that has two stops so that the slide hammer can be slid in one direction and then encounter to stop. The slid hammer can also be slid in the other direction along the shaft where it encounters a second stop and thereby allowing the slide hammer to exert forces on tools at either end of the tool depending upon which stop the slide hammer rams into.
In situations where slide hammers are able to exert forces in multiple directions the tools often need to be manufactured with the slide hammer in place before the stops are located on the tools. Otherwise, if the stops are placed on the shaft before the slide hammer has been mounted and placed, there is no way the slide hammer may be mounted on the tool using conventional slide hammer technology.
Accordingly, it is desirable to provide a method and apparatus that may allow a slide hammer to be altered so that it can impart different levels of force and activate it. Further, it may also be desirable to provide a slide hammer that may be constructed in such a manner, that the slide hammer may be mounted on the shaft of the tool after stops or other tool features have been manufactured on tool.
SUMMARY OF THE INVENTION
The foregoing needs are met, to a great extent, by the present invention, wherein in one aspect an apparatus is provided that in some embodiments permits the slide hammer to be modified so that the slide hammer may impart various levels of force when activated.
In some embodiments of the invention, the slide hammer may be constructed in such a manner that the hammer portion may be mounted on the shaft after other shaft features such as a stop or other features have been manufactured into the tool containing the shaft.
In accordance with one embodiment of the present invention, a slide hammer may be provided. The slide hammer may include: a body defining a through hole and a first attaching surface; an auxiliary weight having a second attaching surface configured to attach to the body at the first attaching surface, the auxiliary weight having a through hole located to align with the through hole in the body when the auxiliary weight is attached to the body; and a shaft located in the through holes in the body and auxiliary weight.
In accordance with another embodiment of the present invention, a method of constructing a slide hammer is provided. The method may include: forming a body having a through hole and a first attaching surface; providing an auxiliary weight having a second attaching surface configured to attach to the body at the first attaching surface, the auxiliary weight having a through hole located to align with the through hole in the body when the auxiliary weight is attached to the body; and inserting a shaft in the through holes in the body and auxiliary weight.
In accordance with yet another embodiment of the present invention a slide hammer may be provided. The slide hammer may include: means for hammering defining a through hole and a first attaching surface; an auxiliary weight having a second attaching surface configured to attach to the means for hammering at the first attaching surface, the auxiliary weight having a through hole located to align with the through hole in the body when the auxiliary weight is attached to the means for hammering; and a shaft located in the through holes in the means for hammering and auxiliary weight.
There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded, perspective view of a side hammer in accordance with an embodiment of the invention.
FIG. 2 is a perspective view of a tire spoon having a slide hammer mounted on it in accordance with an embodiment of the invention.
FIG. 3 is a partial cross-sectional view of the slide hammer in accordance with an embodiment of the invention.
FIG. 4 is an exploded, respective view of the slide hammer in accordance with an embodiment of the invention.
FIG. 5 is a cross-sectional view of a slide hammer in accordance with an embodiment of the invention.
FIG. 6 is a cross-sectional view of a slide hammer in accordance with an embodiment of the invention.
DETAILED DESCRIPTION
The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. An embodiment in accordance with the present invention provides a slide hammer that is fit upon a tire spoon. An embodiment in accordance with the invention is shown as an exploded, perspective view in FIG. 1 .
FIG. 1 shows a slide hammer assembly 10 . The slide hammer assembly 10 includes a hammer body 12 . The hammer body 12 may be comprised of two halves 14 and 16 that fit together in a clam shell type manner. The hammer body 12 may be made of steel or other suitable substance for use as a slide hammer. The two halves 14 and 16 define a through hole 18 that extends through the hammer body 12 .
As shown in FIG. 1 , some embodiments may include a chamfered edge 20 located at the through hole 18 . The chamfered edge 20 may be present at both ends of the body 12 . The hammer body 12 may be equipped with exterior threads 22 . Exterior threads 22 are configured to secure additional or auxiliary weights 24 to the hammer body 12 . The exterior threads 22 are located on both halves 14 and 16 . The additional weight 24 has a through hole 26 that aligns with the through hole 18 and the hammer body 12 when the additional weight 24 is attached with its interior threads 28 to the exterior threads 22 of the hammer body 12 .
In some embodiments of the invention, the internal weights 24 may provide several functions. For example, the additional weights 24 may be used to keep the two halves 14 and 16 of the clam shell body 12 together. When the extra weights 24 are secured to the hammer body 12 , the halves 14 and 16 are connected and unable to separate. The auxiliary weights 24 also provide the advantage of adding additional weight to the body 12 of the slide hammer. Adding or not adding the additional weight allows a user to modify and select a weight of the slide hammer.
In some embodiments of the invention, at least one additional weight 24 is needed to secure the two halves 14 and 16 over hammer body together at 12 . However, additional weights 24 can be added to make the mass of hammer body 12 greater in order to increase the force that the slide hammer 12 can impart on to a stop 34 (see FIG. 2 ) when the slide hammer 12 is activated. Not all embodiments in accordance of the invention require that the hammer body 12 be in two halves 14 and 16 . In some embodiments, the hammer body 12 may be a solid piece with a through hole 18 . In such embodiments, the exterior weights 24 primarily provide the function of adding weight to hammer body 12 .
In some embodiments of the invention, various different weights 24 can be used in order to bring the hammer body 12 to a desired weight in order to impart a desired force when side hammer 12 is activated. In some embodiments of the invention, the exterior weights 24 can be steel or may be made of other substances. Not all embodiments require that the exterior weights 24 be of the same material as the hammer body 12 .
Turning to FIG. 2 , a slide hammer assembly 10 is shown mounted onto a tire spoon 30 . The tire spoon 30 includes a shaft 32 upon which the slide hammer assembly 10 may slide between stops 34 . The stops 34 are robust and connected to the tire spoon 30 so that the slide hammer assembly 10 can strike the stops 34 without dislodging stops 34 thereby causing force of the blow of the hammer assembly 10 to be transferred to the tire spoon 30 . In embodiments of the invention where the hammer body 12 is made up of two halves 14 and 16 as shown in FIG. 1 , advantages may be achieved in that the slide hammer assembly 10 can be mounted to the shaft 32 after the tool of which the shaft 32 is a part of may be manufactured. For example, in the case of tire spoon 30 as shown in FIG. 2 , the tire spoon 30 may have the spoons 36 and the stops 34 manufactured on the tire spoon 30 without having the slide hammer assembly 10 being required to be placed on the shaft before the spoons 36 and stops 34 are formed. The two halves 14 and 16 may be mounted to the shaft 32 after the stops 34 and spoons 36 are formed.
In some embodiments of the invention (with reference to FIGS. 1 and 2 ), the through holes 26 on the additional weights 24 may be sized large enough to fit over the features the tool such as the tire spoon 36 and/or stops 34 . Therefore the tire spoon 30 may be manufactured with the stop 34 and the tire spoon 36 without the additional weights 24 located on the shaft 32 . The additional weights 24 may be mounted to hammer body 12 later. The through hole 26 of the additional weight 24 is sized and dimensioned so the additional weight 24 will fit over the tire spoon 36 , the stop 34 and be secured to the hammer body 12 via the exterior threads 22 interacting with the interior threads 28 . If it is a desired to use additional weights 24 of additional size or weight, they may be added or removed as required and fit over the stop 34 and tire spoon 36 . As such, additional weights 24 may be available as an after market items and may or may not be manufactured or sold with the tire spoon 30 .
In some embodiments of the invention, the slide hammer assembly 10 may include a lock mechanism 38 . The lock mechanism 38 may be activated in several different ways, for example, as shown in FIG. 2 , the lock mechanism 38 may include a detent button 40 .
FIG. 3 is a partial cross-sectional of a slide hammer assembly 10 where the lock mechanism 38 includes a detent button 40 . The detent button 40 is mounted to a rocking lever 42 which pivots over a pivot point 44 . The rocking lever 42 is biased by a spring 46 which biases a engaging member 48 against the shaft 32 . The force of the spring 46 is selected such that the engaging member 48 generates sufficient friction against the shaft 32 that the slide hammer assembly 10 does not move with respect to the shaft 32 unless the detent 40 is depressed. In other embodiments, the engaging member 48 may more positively lock with the shaft 32 for example, by fitting into a detent in the shaft 32 .
Depressing the detent button 40 pivots the locking lever 42 , compresses the spring 46 and causes the engaging member 48 to disengage from the shaft 32 , thereby allowing a user to operate the slide hammer assembly 10 . When it is no longer desired to operate the slide hammer assembly 10 , the user releases the detent button 40 , thereby locking the slide hammer assembly 10 in place on the shaft 32 . Such a feature may be useful when it is not desired for the slide hammer assembly 10 to move about the shaft 34 when the tool such as a tire spoon 30 is being manipulated and the use of the slide hammer assembly 10 is not desired.
Another locking mechanism 38 is illustrated in FIGS. 4-6 . In FIGS. 4-6 a slide hammer assembly 10 is shown with a locking mechanism 38 that is activated by twisting the hammer body 12 . In the embodiment shown in FIG. 4 , the hammer body 12 is made up a fore 50 and aft 52 half. The fore 50 and aft half 52 may attach to each other by exterior threads 54 mating with interior threads 56 as shown. Other attaching methods may also be used in accordance with the invention. Attaching the fore 50 and aft 52 halves together traps a lock collet 58 between them. The lock collet 58 is generally C-shaped. The lock collet 58 is a unclosed ring as shown in FIG. 4 and may include locking member 60 which have a greater thickness in axial length than the remainder of the lock collet 58 as shown.
FIG. 5 is a cross-sectional view of a hammer body 12 including the locking mechanism 38 and a lock collet 58 . The lock collet 58 is located in an off center trench 62 . The off center trench 62 may be circular as shown but is located off center from the through hole 18 in a hammer body 12 . Locating the trench 62 off center results in the trench forming a shallow side 64 and a deeper side 66 with respect to the through hole 18 .
In FIG. 5 , the shaft 32 is shown extending through the lock collet 58 . The thick part 68 of the lock collet 58 (also referred to as the locking member 60 ) is located in the deep part 66 of the off center trench 62 . The thin part 70 of the lock collet 58 is located in the shallow side 64 of the off center trench 62 . This results in minimal friction or interference between the lock collet 58 and the shaft 32 . When it is desired to lock the hammer body 12 onto the shaft 32 , the user rotates the hammer body 12 to a locking position as shown in FIG. 6 .
In FIG. 6 , the hammer body 12 has been rotated on the shaft 32 . This rotation has caused the thick part of 68 (one side of the thick part 68 is now compressed and identified in FIG. 6 as reference character 72 ) of the lock collet 58 to move to a more narrow or shallow side 64 of the trench 62 . Moving the lock collet 58 in this manner has caused the lock collet 58 to compress between the shaft 32 and hammer body 12 . In some embodiments the lock collet 58 may be made of nylon or any other suitable substance.
The amount of compression that the thick part 72 of the lock collet 58 or the locking member 60 is the reduction of the diameter of the off center trench 62 . As shown in FIG. 6 , part of the lock collet 58 is a compressed portion 72 . The difference between the compressed portion 72 and the thick part 68 illustrates the reduction in a diameter of the off center trench 62 with respect to the shaft 32 . The compression of the lock collet 58 results in friction and/or interference between the lock collet 58 and the shaft 32 thereby locking the hammer body 12 onto the shaft 32 . When it is desired to unlock the hammer body 12 with respect to the shaft 32 , the user may twist the hammer body 12 back to the position shown in FIG. 5 which allows the locking member 60 or thick part 68 of the lock collet 70 to reside in the deep part 66 of the off center trench 62 and the thin part 70 of the lock collet 58 to reside in the shallow side 64 of the off center trench 62 as shown in FIG. 5 .
The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
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A slide hammer may be provided. The slide hammer may include: a body defining a through hole and a first attaching surface; an auxiliary weight having a second attaching surface configured to attach to the body at the first attaching surface, the auxiliary weight having a through hole located to align with the through hole in the body when the auxiliary weight is attached to the body; and a shaft located in the through holes in the body and auxiliary weight. A method of constructing a slide hammer is provided.
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This application is a continuation of application Ser. No. 08/092,264, filed Jul. 15, 1993, now abandoned.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for vacuum forming from a plastic sheet a stud plate having hollow studs standing up from a base plate at predetermined positions, each hollow stud being provided with an inner wall and an upper circumferential edge with at least one radially protruding projection.
This process serves primarily for producing stud plates which serve for pre-fixing flexible plastic heating tubes for floor heating systems. A flexible heating tube is embedded in a meandering manner in the screed of a floor. The stud plate permits a uniform course of the flexible tube and especially fixes the flexible tube when the still low-viscosity screed is applied. So the tube does not push upwards, it must be locked from above by projections from the hollow studs of the stud plate.
These projections pose problems regarding production. If the mould studs of the positive mould have rigidly formed mould projections, the hollow studs must expand on removal from the positive mould in order to be able to slide over said mould projections. On the one hand, it is often only possible to produce projections protruding to an insufficient extent, on the other hand it is only possible to process a thin plastic sheet of restricted plastics grades. It is also possible to incorporate into the studs movable mould projections which are drawn back or pivoted back after the moulding operation. Although this makes possible the best moulding results, it makes very expensive positive moulds necessary. Such movable mould parts are also subject to faults.
SUMMARY OF THE INVENTION
The object of the invention is to specify a process of the generic type which makes possible the cost-effective and reliable production of stud plates with projections from the hollow studs, sufficiently large projections with a sufficiently stable plastic sheet being obtained.
This object is achieved by the using positive moulds, each having an associated mould stud with a moulding side including an upper end face, on which said hollow studs are formed,
fixing and holding down a center part of a flexible elastic disc in continuous contact with said upper end face on said moulding side of said associated mould stud, by fixing means, said fixing means being accessible from said moulding side of said mould stud to fix and hold down said center part in a direction opposite to the direction in which said plastic sheet is pulled from said mould stud following vacuum forming,
forming said projections(s) by means of said disc, said disc having a flat, lower side and an upper side, said disc being held with a first part of said flat, lower side lying flat and loosely on said upper end face and projecting with a second part of said flat, lower side, contiguous with said first part, beyond a circumferential edge of said upper end face, said disc having a flexural rigidity such that said second part remains extended substantially beyond said circumferential edge of said upper end face when said plastic sheet is drawn over said mould stud, and such that at least said first part bends upwards from said upper end face when said hollow stud is pulled upwards from said mould studs,
drawing said plastic sheet over said mould stud by vacuum to form said projection(s), and pulling said hollow stud upwards from said mould stud, said second part sliding along said inner wall of said hollow stud.
The advantage of the invention lies in the fact that the yielding movement, as in the system of movable mould projections, takes place on the mould side, so that the stud plate is not stressed in a manner which runs counter to its actual function. On the other hand, no complicated actuation and control of the mould projections is necessary, since owing to their design and position on the mould studs, these are sufficiently stiff during the moulding operation and on the other hand yield automatically during demoulding.
The preferred embodiments concerning various flexible elastic discs according to the invention result in various shapes of projections.
The preferred embodiments concerning elastic discs subdivided by edge incisions result in a disc shape which facilities the yielding and bending upwards during demoulding.
Preferred adaptations of the subdivided elastic disc are for the purpose of fixing flexible heating tubes.
In another preferred adoption of the elastic discs according to the invention owing to the arrangement of two identical discs, twice the number of mould projections is obtained, if required.
In this case a preferred adaptation to the fixing of flexible heating tubes results.
The further development of using discs of plastic, particularly silicone elastomer, results in a certain resilience of the mould projections at the exposed corners so that the latter, on the one hand, do not bore through the plastic film during moulding and, on the other hand, slide more easily along the inner wall of the hollow stud during demoulding. Even a relatively large stud plate of, for example, 1 m2 can thus be more easily removed from the positive mould.
According to the further development provision is made to form the disc of metal, such as spring bronze, in particular spring steel. This has the advantage that the disc can be thin with sufficient stiffness, so that the overall height can be kept small. The properties of this material are also insensitive to the operating temperatures during vacuum forming. Finally, metal discs are good heat conductors which thus readily take up the heat from the baseplate and the mould studs, which are also made of metal. The plastic sheet is thus held at the correct temperature, even at the critical corner regions of the projections.
The baseplate of the positive mould is first to be conceived as a flat plate, even though the stud plate formed thereon is intended to be laid on a flat floor.
However, it has been found that a slight curvature of the stud plate (with a radius of for example 1 meter) is practically insignificant, since such a stud plat, because of its elasticity, readily adapts to the floor form.
It is therefore provided in a further development to design the baseplate of the positive mould at least as a cylinder barrel section, from which the mould studs stand up aligned radially outwardly. With a plurality of cylinder barrel sections, a multi-cycle mould can be formed in a spatially compact manner. By means of a baseplate extending over the entire cylinder circumference (which can be composed of a plurality of sections) it is also possible to produce "stud plates" in the form of an endless web or of a web of considerably greater length than width.
Thus, for example, on a cylindrical carrier which is mounted so as to be rotatable there can be arranged three baseplates, distributed around the circumference at a distance from one another, in the form of cylinder barrel sections. In a first rotational position, the plastic sheet is drawn onto the first baseplate and moulded. Then the carrier is rotated further through one operating cycle (120°) so that the second baseplate passes into this position for drawing on a plastic sheet whilst the first baseplate assumes the subsequent position in which it is cooled. With the next operating cycle, the third baseplate passes into the position for the drawing of the plastic film, the second baseplate passes into the cooling position and the first baseplate into a demoulding position in which the moulded stud plate is removed from the positive mould. Finally, with a further rotation of the carrier, a new cycle is commenced.
By means of a baseplate extending without interruption around the carrier, with continuous rotation, a stud plate in the form of a long sheet can be moulded.
The invention is explained in greater detail hereinbelow with the aid of the exemplary embodiments shown in the drawing, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a perspective view of a partial region of a stud plate,
FIG. 2 shows a view in the direction of the arrow 2 of FIG. 1,
FIG. 3 shows a side view of a partial region of the positive mould before the moulding operation,
FIG. 4 shows a view of cross-shaped strips with a fastening means,
FIG. 5 shows a view corresponding to FIG. 3 during the demoulding operation,
FIG. 6 shows a diagrammatically simplified arrangement of a multi-cycle mould,
FIG. 7 shows a diagrammatically simplified arrangement of an endless mould,
FIG. 8-11 shows various diagrammatically simplified disc shapes,
FIG. 12 shows various diagrammatically simplified shapes of the top end face of a mould stud.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 shows, obliquely from above, a partial region of a stud plate 10 having four hollow studs 11, 12, 13, 14 which are positioned at the corner points of a square, within the scope of manufacturing accuracy are identical to one another and project upwards from a baseplate 15. Between the hollow studs, stiffening webs 16 extending in a cross-shaped manner are moulded in the baseplate 15. This general structure repeats itself regularly over the entire stud plate 10 which is produced in various sizes of, for example, 50×100 cm or 100×100 cm.
As a representative, the hollow stud 11 (FIG. 2) is described in greater detail. It has an approximately circular-cylindrical case 17 which connects at the bottom, via a frustoconical case 18, to the baseplate 15. At the top, the hollow stud 11 has a cover surface 19. Uniformly distributed on the upper edge are four projections 21, 22, 23, 24, by means of which the cover surface 19 obtains roughly an approximately octagonal outline. The projections are arranged such that they are in each case directed towards four hollow studs of the more remote vicinity. The hollow studs 12 and 14 are directly adjacent to the hollow stud 11, whereas the hollow stud 13 can be considered as forming part of the more remote vicinity. Accordingly, for example, the projection 23 faces the hollow stud 13.
With the example of FIG. 2, it can be seen how an indicated flexible tube 25 is fixed. The flexible tube 25 is not drawn in FIG. 1: it must be imagined extending diagonally in the direction of the arrow 2. It lies below on the stiffening webs 16 with its left flank against the circular-cylindrical cases 17 of the hollow studs 11 and 13 an with its right flank against the circular-cylindrical case 17 of the hollow stud 12. Furthermore, the projection 22 of the hollow stud 11 and the projection 22, aligned in the same direction, of the hollow stud 13 engage over the flexible tube 25 from one side. From the other side the projection 24 of the hollow stud 12 (not drawn in FIG. 2) engages over the flexible tube 25 which has an external diameter of approximately 10 mm. Since this clamping repeats itself along the flexible tube 25 in the pattern of the stud plate, the flexible tube 25 is fixed on all sides along its entire course, so that it maintains its position with sufficient stability if the screed is then applied.
FIG. 3 shows a partial region, corresponding to the hollow stud 11, of a positive mould 26. It consists of a stable baseplate 27 from which a plurality of mould studs 28 of the same kind project upwards. Each mould stud 28 has an approximately circular-cylindrical case 29 (a square-prismatic or octagonal-prismatic shape would be equally conceivable, however a circular cylinder is more simple to produce) which is connected at the bottom via a frustoconical case 30 to the flat top side 31 of the baseplate 27. The circular-cylindrical case 29 can advantageously be designed tapering slightly conically towards the top.
At the top, the mould stud 28 has a flat end face 32 which is perpendicular to the stud axis and on which a disc 33 lies which is shown in greater detail in FIG. 4. This disc 33 is structured into four strips 34, 35, 36 and 37 which are at right angles to one another and originate radially from a centre part 38 with a central hole 39. A bolt 41 with a moulded-on flat head 42 serves for fastening the disc 33 on the end face 32, in that the bolt 41 crosses the central hole 39 and is driven into an axial hole 43 in the mould stud 28. The head 42 then lies flatly on the centre part 38.
If the end face 32 has a radius of 9 mm, the strips 34-37 are sufficiently long to project approximately 1 to 3 mm, preferably 2 mm, above their circumferential edge. The head 42 has a radius of approximately 5 mm. The strips have a thickness of approximately 0.5 to 1 mm and a width of approximately 5 mm and consist of elastically flexible material, preferably plastic, in particular silicone elastomer which remains sufficiently firm at the moulding temperature, or of elastic metal. The outer corners of the strips are expediently slightly rounded. The disc 33 can be simply punched out from a flat material. It is also possible to produce it with a bolt-like attachment, for example as an injection moulded part, in which case the separate bolt 41 is eliminated.
Each strip 34-37 is, in its installed position (FIGS. 3 and 5), structured into three functional parts, the transitions of which can be fluent. A first part 44 corresponds to its flexible length from the edge of the head 42 to the edge of the end face 32, the flexural movement being possible only upwards, away from the end face 32. A second part 45 corresponds to the region projecting over the edge of the end face 32. A third part is identical to the centre part 38 which is firmly clamped under the head 42.
The flexural rigidity of the strips is determined by the suitable choice of material, thickness and width such that the second part 45 bends away only slightly downwards when a preheated plastic sheet 46 to be formed is drawn under the suctional effect of the vacuum over the mould stud 28, as is indicated in FIG. 3 by the arrows 47. The projections 21-24 (FIG. 1) are thereby moulded. If, after the moulding operation, the stud plate 10 resulting from the plastic sheet 46 is removed from the positive mould 26 in the direction of the arrow 48 (FIG. 5), the strips bend upwards at least in the region of their first part 44 from the end face 32, the second part 45 or its edge sliding along bearing slightly against the inner wall 49 of the hollow stud 11, shown as an example here.
Due to the above-described nature of the positive mould 26 and the production process resulting therefrom, some characteristics of the product, the stud plate 10, can be ascertained, as shown in FIG. 1. On the one hand these are the impressions, visible in the cover surface 19 of the strips 34-37 and, if appropriate, of the head 42. The head impression is dispensed with, however, if the stud 41, as already indicated, is integrally moulded on the disc 33. The strip impressions can be hidden somewhat if the free corners on the end face 32 are covered, that is to say if the cross-shaped disc 33 is embedded in a corresponding cross-shaped recess in the end face 32. However, it is not possible to hide a certain non-uniformity of curvature of the cover surface 19 in the region of the projections 21-24 on the multiplicity of hollow studs of a complete stud plate. This is because the spread-out second parts 45 (FIG. 3) of the multiplicity of strips do not behave exactly identically like absolutely stiff mould projections, but yield to different extents. Even differences in stress in the plastic sheet 46, on account of slight temperature differences for example between centre and edge regions, cause a measurably different curvature.
According to FIG. 6, a cylindrical carrier 61 with for example a radius of an axial length of in each case 1 meter is mounted in a manner not especially illustrated so as to be rotatable about a stationary shaft 62. On the carrier 61, three identical baseplates 63, 64, 65 in the form of cylinder barrel sections are fastened such that the mould studs 28 attached thereon are directed radially outwards and the baseplates are arranged at positions distributed around the circumference in each case at 120° to one another. In the circumferential direction, each baseplate extends over a length of approximately 1 meter.
The baseplate 63 is in the "moulding position" in which a mould frame 66 is placed thereover in the interior of which a plastic sheet is clamped. The latter is drawn over the mould studs 28 by means of subatmospheric pressure at the baseplate 63 side. To this end, suitable air channels in the baseplate 63 are connected via a channel 67 in the carrier 61 to a stationary suction line 68 which leads to a vacuum pump, not illustrated. Within the carrier 61 there is disposed a stationary heating device 69 by means of which the sector of the carrier 61 with the baseplate 63 is heated.
The baseplate 64 is in the "cooling position". On the baseplate with the mould studs standing up from it there is drawn on the finished moulded stud plat 10 which here has the opportunity to cool off and harden.
The baseplate 65 is in the "demoulding position". Here, via a pressure line 70, air is blown into the air channels via the channel 67 which is also formed here, causing the stud plate 10 to be ejected downwards.
The design and arrangement of the baseplates together with air channels is always the same, so that with each operating cycle with which the carrier 61 is rotated through 120° further in the direction of the arrow 71, a cyclical sequence of operating cycles "moulding--cooling--ejection" is effected at each baseplate. It goes without saying that the mould frame 66 is drawn back in the direction of the arrow 72 before each rotary step, so that before the next moulding operation a new sheet can be inserted.
According to FIG. 7, a cylindrical carrier 73 is mounted so as to be rotatable about a stationary shaft 74. On said carrier 73 there is fastened a baseplate 75 in the form of a complete cylinder barrel, such that the mould studs 28 are directed radially outwards. From the point of view of manufacturing, it is expedient to compose the baseplate 76 from at least two shell parts which, in the assembled state, form functionally a continuous cylinder barrel. From a supply roll 76, a plastic sheet with a width of, for example, 1 meter is fed via a pressing device 77 to the exterior side of the baseplate 75. The pressing device 77 has distributed around its circumference a plurality of strips 78 which, with the rotation of the carrier 73, engage in the direction of the arrow 79 in each case into the gaps between the mould studs 28. They press the still-unmoulded sheet in each case towards the baseplate 75 to such an extent that the air suction which is generated, via a suction line 80 and one of the uniformly distributed channels 81 of the carrier 73, in the region of the pressing device 77 can grasp the plastic sheet. The sheet preheated by a heating device 82 is then drawn by the suction over the mould stud 28. The baseplate 75 with the mould studs 28 is heated by means of a heating device 83 arranged fixed within the carrier 73 in the circumferential sector of this "moulding position" 84. The carrier 73 rotates continuously, so that new regions of plastic sheet are constantly fed and moulded.
Already-moulded sheet can cool off on the subsequent circumferential sector, the "cooling position" 85, in order then to be separated from the mould in the lower circumferential sector, the "demoulding position" 86. To this end, compressed air can be blown, via a stationary pressure line 87, into those channels 81 of the carrier 73 lying opposite there. The ready-moulded stud plate 10, which here is present in the form of a long sheet, can be wound up to form a roll until later use.
FIG. 8 shows discs 90 which, with their second parts 91, project in each case circularly around the entire circumferential edge 92 of the end face of the mould stud.
FIG. 9 shows examples according to which the discs 93 project with their second part 96 in each case over only a partial region of the circumferential edge 92.
According to FIG. 10, the discs 95 project with their second parts 96 over a plurality of partial regions, distributed in the circumferential direction, of the circumferential edge 92.
It is common to the preceding examples that discs 90, 93, 95 have a periphery without incisions. The examples according to FIG. 11, by contrast, show discs 97 which, starting from the circular shape, are structured by approximately radial incision 98. Starting from a common first part 99, there thereby results a plurality of second parts 100 which project over partial regions, in each case distributed in the circumferential direction, of the circumferential edge 92.
A form of the subdivision is shown in FIG. 4, according to which four second parts in the form of strips 34-37 result, the disc 33 taking on the form of a cross-shaped structure. However, as shown in the right-handed diagram of FIG. 11, a strip-shaped disc 101 can also be used which, starting from the common central first part 102, has only two diametrically standingout second parts 103, 104. If, nevertheless, it is still desired to obtain four projections, two such strip-shaped discs 101, 105 can be laid crossed one on top of the other. In principle, such a stacked arrangement can also be carried out in the case of other disc shapes, for example those according to FIG. 9.
FIG. 12 shows, diagrammatically in side view, a mould stud 28 on which any of the above-illustrated discs is fastened. The upper end face 32 can be flat or, like the end face 106, concavely curved. This variant has the advantage that the head 42 of the bold is lower than the mould projections 107 and consequently, those projections of the hollow stud formed thereon represent in each case the highest point of the hollow stud.
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A process for producing a stud plate from plastic by vacuum forming uses a positive mold (21) in which these is held on the end face (32) of each stud (28), a flexible elastic disc which protrudes with a part (45) of its flexible length over the edge. A projection (22, 24) of a hollow stud is formed thereon. During demolding a part (44) of the disc lying radially further inwards bends upwards from the end face, so that the protruding part (45) yields and readily slides along the inner wall (49) of the previously molded hollow stud (11).
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BACKGROUND OF THE INVENTION
This invention relates to indexable head diamond dressers and more particularly to an improved means for maintaining the concentricity of the mounted diamond with the axis of the shank portion of the cutting tool. Indexable head diamond dressing tools are known in the prior art and are designed to equalize wear on the diamond cutting element. See for example U.S. Pat. Nos. 2,587,132; 2,761,441; 2,999,493; and 3,452,735. Diamond cutting tools of this type have a tool holding member rotatably cooperating with a supporting shaft. Resilient means urge the two members into tight frictional engagement. The tool holding member may be rotated upon the application of a torque sufficient to overcome the forces holding the tool holding member in its rotative position on the shaft. The use of a rotatable tool holding member eliminates the need for removing the shaft portion from its mounting when a fresh cutting surface portion of the mounted diamond must be positioned for use.
The prior art devices have not, however, eliminated the problem of lateral shifting of the tool holding member with respect to the shaft axis. Previous designs rely on the accuracy and closeness of the fit between the rotating members. After a period of use, however, the confronting surfaces will wear to a degree which will permit the tool holding member to shift radially with respect to the supporting shaft axis with the result that the concentricity of the diamond point with the shaft axis is no longer true. This is a particularly serious problem when, for example, tracer devices which allow no deviation from predetermined datum dimensions are used. In such a device a diamond ground to a specific conical point is mounted concentric with the supporting shaft axis and is required to maintain its original datum point throughout repeated operations. Accurate concentricity of this magnitude cannot be maintained merely by urging rotating member confrontation surfaces such as those disclosed in the prior art together with resilient means. Wear will still result in loss of the diamond point's concentricity with the shaft axis.
SUMMARY OF THE INVENTION
Concentricity of the diamond point with the shaft axis can be maintained over a prolonged period of use only by implementing a dynamic system in which the friction surfaces are permitted to move in wedging engagement upon wear, the movement being initiated by an optimally efficient application of friction surface engaging force, that is, force brought to bear directly on a relatively concentrated surface area. Such a dynamic system, as disclosed herein eliminates the problems associated with indexable head diamond cutting tools of the prior art.
In construction, the diamond dressing tool of the present invention includes a supporting shank which has a conical bearing surface having a predetermined angle with the axis of the shank. The invention further includes a diamond cutting tool having a diamond with a cutting point mounted concentrically at the forward end thereof. A head member mounted on the supporting shank has at one end a second conical bearing surface cooperating with the shank bearing surface. At the opposite end is a recess for securely holding the diamond cutting tool which has side and bottom wall surfaces configured to be received therein. Spring means are operatively disposed between the supporting shank and the head member for exerting engagement force in a direction parallel to the shank and directly against the conical bearing surfaces holding them in tight frictional engagement. The head member is mounted on the shank so that upon wear on the bearing surfaces, the spring means will initiate longitudinal movement of the head bearing surface along the shank bearing surface. This compensates for the wear, thereby preventing lateral movement of the head member with respect to the shank axis and maintaining the concentricity of the diamond therewith. In addition, as the conical bearing engagement surface area is small, the engagement force is concentrated over a limited area thereby insuring optimal use of the resilient force generated by the spring means.
Further, in accordance with the indexable head diamond dresser disclosed herein, the placement of the spring means proximal the conical bearing surfaces also allows the length of the supporting shaft to be varied without effecting the rotational characteristics of the head member. The disclosed device is sturdy, simple to use and maintain, and may be manufactured in a manner to permit the torque required to rotate the head member to be preset at the factory.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view partially in cross section of the assembled diamond dressing tool.
FIG. 2 is a side view partially in cross section of the partially assembled diamond dressing tool.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The diamond dressing tool 1 as shown in FIG. 1 includes a head member 2 and a shank 3. The head member has an outer configuration consisting of multiple facets. This faceted configuration facilitates the rotation of the head with a tool member, not shown, having a complementary gripping surface. The head, at one end, has a front recess 4 defined by recess walls 5 for holding a diamond cutting tool 6. The diamond cutting tool 6 consists of a slug 7 partially encasing a diamond 8 having a cutting point 8' and a diamond slug carrier 9. When the diamond cutting tool 6 is positioned in the recess 4 the diamond point 8' is concentric with the head central axis. The cutting tool 6 is secured in the recess 4 by force fitting in conjunction with a strong adhesive. The opposite rear end of the head member 2 is provided with an annular flange 10, having a front wall 11 and a rear wall 12 which forms a conical bearing surface 12' having an angle with the head central axis of 30° ± 15'. The flange forms a passage connecting the rear end of the head member to the bottom of the front recess 4.
The shank 3 has an elongated rearmost portion having a flat surface 13. The elongated portion is configured for non-rotatable mounting in a holder, not shown, with the flat surface 13 providing a contact point for a set screw. The shank has a conical medial portion forming a conical bearing surface 14. The conical bearing surfaces 12' and 14 also serve as friction confrontation surfaces. The shank conical friction confrontation surface 14 has an angle with the central shank axis of approximately 30° ± 15' and is configured to frictionally engage the head member conical friction confrontation surface 12'.
The shank 3 is further provided with a tubular front extension defining a male fitting 15 which is concentric with the shank axis and comprised of material distortable under predetermined force. A shank shoulder 16 defines the rearmost extent of the shank bearing surface 14.
To assemble the indexable head diamond dresser, the tubular front extension 15 of the supporting shank 3 is inserted through the head member annular flange 10 until the respective conical bearing surfaces 12' and 14 are in engagement, as shown in FIG. 2. In this position the head central axis is coincident with the central shank axis. Spring means, which in the preferred embodiment consists of two Belleville washers 17, and a flat washer 18, are next positioned around the tubular extension 15. The front end of the tubular extension is then subjected to a predetermined rearwardly directed force from a device such as a 120° punch inserted through the empty diamond cutting tool recess 4. This procedure forms the shank spring retaining means 19 which compresses the Belleville washers against the front wall 11 of the head member annular flange 10. The spring means has a predetermined resilient force directed parallel to the shank axis sufficient to urge the conical bearing surfaces 12' and 14 into tight frictional engagement thus preventing rotation of the head member 2 about the shank 3 absent the application of a predetermined torque.
As shown in FIG. 1 when the diamond cutting tool 6 is fitted into the head member recess 4 a space 20 of predetermined size is defined by the rear surface 21 of the tool carrier 9, the side wall surfaces 5 of the tool carrier recess and the front surface 22 of the shank spring retaining means 19.
Prior to the need for replacement, wear on the diamond point 8' is compensated for by rotating the head member by the application of predetermined torque, thus providing a new diamond cutting surface at the point of operational contact. Any wear on the conical bearing surfaces 12' and 14 which would result in lateral movement of the head member is compensated for by the longitudinal movement of the head member bearing surface 12' along the shank member bearing surface 14. This longitudinal movement is permitted by the above defined space 20 and is initiated by the constant pressure exerted by the spring means 17. The concentricity of the diamond point 8' with the shank axis is maintained despite repeated rotative adjustment of the head member about the shank by this dynamic cooperation of the spring means 17 with the conical bearing surfaces 12' and 14.
The above mentioned deforming force applied to the front end of the shank extension in forming the spring retention means 19 also presets the torque required to overcome the spring force holding the head member 2 in its rotative cutting position on the shank 3. When the cutting tool 6 is positioned within its recess 4, access to the shank spring retention means as well as the spring means is prevented absent total removal of the cutting tool from its recess. This assembly insures that the operating characteristics which the dynamic system is designed to preserve will be controlled by the manufacturer. As already stated, the spring means 17 direct engaging force parallel to the shank axis onto the bearing surfaces 12' and 14. Due to the positioning of the spring means proximal the bearing surfaces the distance that the engaging force must travel is kept to a minimum thus insuring that maximum force will be brought to bear on the surfaces 12' and 14.
As shown in FIGS. 1 and 2, the shank is provided with an axial bore 23 extending its entire length. A tool may be inserted through the bore 23 and placed in contact with the rear surface 21 of the tool carrier 9 thus providing easy removal thereof when a replacement tool carrier must be inserted into the head member recess 4.
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A diamond dressing tool including a tool holding head member and supporting shank having cooperating conical bearing surfaces urged together in tight frictional engagement by spring means operatively mounted therebetween. The head member is so mounted on the shank to permit its longitudinal movement along the shank bearing surface.
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FIELD OF THE INVENTION
The present invention is generally related to methods of measuring fracturing and re-opening pressures and stresses in a borehole traversing a subterranean reservoir.
BACKGROUND
In the co-owned U.S. Pat. Nos. 5,353,637 and 5,517,854 to R. A. Plumb and Y. S. Dave much of background relevant to the present invention is set out in great detail and incorporated herein for reference. In the patents, the need for an accurate measurement of formation breakdown and re-opening pressures is highlighted together with methods to derive further parameters from such measurements. Parameters derived from the pressure measurements include for example the magnitude and direction of maximum and minimum horizontal stresses.
As stated in the '637 patent, it is the precise knowledge of differences in stress magnitude that allows engineers to predict the type of fracture treatment that will assure containment in the reservoir beds. However, precise stress magnitude data are rarely obtained, particularly not in shales, which can be very tight. Instead it is commonly assumed that the least principal horizontal total stress in shales is greater than in adjacent reservoir rocks. The '637 patent describes the use of instrumented packers or pairs of packers with hydraulics to pressurize the packers or the volume between packers to measure the important parameters.
Another technical area in oil field technology usually considered as unrelated to the production stimulation as described above is the so-called formation sampling. Various techniques for performing formation evaluation (i.e., interrogating and analyzing the surrounding formation regions for the presence of oil and gas) in open, uncased boreholes have been described, for example, in U.S. Pat. Nos. 4,860,581 and 4,936,139, assigned to the assignee of the present invention. An example of this class of tools is Schlumberger's MDT™, a modular dynamic fluid testing tool. Such a tool may include at least one fluid sample bottle, a pump to extract the fluid from the formation or inject fluid into the formation, and a contact pad with a conduit to engage the wall of the borehole. When the device is positioned at a region of interest, the pad is pressed against the borehole wall, making a tight seal for the pumping operation to begin.
To enable the same sampling in cased boreholes, which are lined with a steel tube, sampling tools have been combined with perforating tools. Such cased hole formation sampling tools are described, for example, in the U.S. Pat. No. 7,380,599 to T. Fields et al. and further citing the U.S. Pat. Nos. 5,195,588; 5,692,565; 5,746,279; 5,779,085; 5,687,806; and 6,119,782, all of which are assigned to the assignee of the present invention. The '588 patent by Dave describes a downhole formation testing tool which can reseal a hole or perforation in a cased borehole wall. The '565 patent by MacDougall et al. describes a downhole tool with a single bit on a flexible shaft for drilling, sampling through, and subsequently sealing multiple holes of a cased borehole. The '279 patent by Havlinek et al. describes an apparatus and method for overcoming bit-life limitations by carrying multiple bits, each of which are employed to drill only one hole. The '806 patent by Salwasser et al. describes a technique for increasing the weight-on-bit delivered by the bit on the flexible shaft by using a hydraulic piston.
Another perforating technique is described in U.S. Pat. No. 6,167,968 assigned to Penetrators Canada. The '968 patent discloses a rather complex perforating system involving the use of a milling bit for drilling steel casing and a rock bit on a flexible shaft for drilling formation and cement.
U.S. Pat. No. 4,339,948 to Hallmark discloses an apparatus and methods for testing, then treating, then testing the same sealed off region of earth formation within a well bore. It employs a sealing pad arrangement carried by the well tool to seal the test region to permit flow of formation fluid from the region. A fluid sampling arrangement in the tool is adapted to receive a fluid sample through the sealing pad from the test region and a pressure detector is connected to sense and indicate the build up of pressure from the fluid sample. A treating mechanism in the tool injects a treating fluid such as a mud-cleaning acid into said sealed test region of earth formation. A second fluid sample is taken through the sealing pad while the buildup of pressure from the second fluid sample is indicated.
In U.S. Patent Application Publication 2009/0255669 tools and methods are described for injecting fluid into the formation surrounding wellbore for various purposes such measuring fluid saturations and other formation parameters.
Methods and tools for performing downhole fluid compatibility tests include obtaining an downhole fluid sample, mixing it with a test fluid, and detecting a reaction between the fluids are described in the co-owned U.S. Pat. No. 7,614,294 to P. Hegeman et al. The tool includes a plurality of fluid chambers, a reversible pump and one or more sensors capable of detecting a reaction between the fluids. The patent refers also to a downhole drilling tool for cased hole applications.
In the light of above known art it is seen as an object of the present invention to improve and extend methods of determining fracture pressures and stresses while reducing requirements for hydraulic and mechanic equipment such as packers.
SUMMARY OF INVENTION
Hence according to a first aspect of the invention there is provided a method of testing a subterranean formation for fracture condition, including the steps of creating a side bore into the wall of a well traversing the formation, sealing the wall around the side bore to provide a pressure seal between the side bore and the well, pressurizing the side bore beyond a pressure inducing formation fracture while maintaining the seal and monitoring the pressure to identify the fracture condition.
The side bore is preferably drilled in direction of the maximum horizontal stress, if this direction is prior knowledge.
The method is furthermore best applied to formations of low permeability, which are believed to confine the spread of a fracture to the desired directions. A formation is considered to be of low permeability if the permeability at the test location is less than 100 mD (millidarcy) or even less than 20 mD or 10 mD.
This invention allows evaluation of stimulation fluids at reservoir (downhole) conditions. The invention is particularly useful for testing and evaluating formations for a subsequent hydraulic fracturing operation.
The method enables fracturing opening and re-opening tests with minimal use of hydraulic fluids.
These and other aspects of the invention are described in greater detail below making reference to the following drawings.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 shows a typically deployment of a formation drilling and sampling tool while performing steps in accordance with an example of the present invention;
FIG. 2 illustrates the step of drilling a side bore to an existing well in accordance with an example of the present invention;
FIGS. 3A and 3B illustrate the step of fracturing the formation in the vicinity of a side bore in accordance with an example of the present invention; and
FIG. 3C reproduces pressure vs time profiles similar to those expected to be measured in accordance with an example of the present invention; and
FIG. 3D are simulated contour plots around an injection point representing the approximate size of the high pressure zone at the well bore.
DETAILED DESCRIPTION
In FIG. 1 , a well 11 is shown drilled through a formation 10 . The well 11 includes an upper cased section 11 - 1 and a lower openhole section 11 - 2 . The lower openhole section is shown with a layer 12 of formation damaged and invaded through a prior drilling process which left residuals of the drilling fluids in the layer surrounding the well.
In this example of the invention, a wireline tool 13 is lowered into the well 11 mounted onto a string of drillpipe 14 . The drill string 14 is suspended from the surface by means of a drilling rig 15 . In the example as illustrated, the wireline tool includes a formation testing device 13 - 1 combined with a formation drilling device 13 - 2 . Such tools are known per se and commonly used to collect reservoir fluid samples from cased sections of boreholes. The CHDT™ open hole drilling and testing tool as offered commercially by Schlumberger can be regarded as an example of such a tool. The connection to the surface is made using a wireline 13 - 3 partly guided along the drill string 14 (within the cased section 11 - 1 of the well 11 ) and partly within the drill string (in the open section 11 - 2 ).
The operation of this combined toolstring in a downhole operation in accordance with an example of the invention is illustrated schematically in the following FIGS. 2-3 .
In the example, it is assumed that the stresses around the well 11 have been logged using standard methods such acoustic or sonic logging. At a target depth, the tool 13 is oriented such that it is aligned in directions of the maximum horizontal stress. It is in this direction that fractures typically open first when the whole well is pressurized in a normal fracturing operation. The mounted tool 13 can be rotated by rotating the drill string 14 and thus assume any desired orientation in the well 11 .
Making use of the conventional operation mode of the CHDT tool 13 , the body 20 of the tool as shown in more detail in FIG. 2 includes a small formation drill bit 210 mounted on an internal flexible drill string 211 . While the tool is kept stationary using the sealing pad 22 and counterbalancing arms (not shown), the flexible drill 210 can be used to drill a small side bore 212 into the formation 10 surrounding the well 11 .
In the example, a 9 mm diameter hole 212 is drilled to an initial depth of 7.62 cm (3-in) before reaching the final depth of 15.24 cm (6-in). The drilling operation is monitored with real-time measurements of penetration, torque and weight on bit. The bit is automatically frequently tripped in and out of the hole to remove cuttings. The bit 210 trips can be manually repeated without drilling if a torque increase indicates a buildup of cuttings.
After the drilling of the side bore 212 , reservoir fluids are produced to clean it of any cuttings that could adversely affect the subsequent injection. After the clean-out, the pressure in the side bore 212 is increased by pumping a (fracturing) fluid either from a reservoir with the tool or from within the well through the tool.
As shown in FIG. 3A , the pump module 230 , which is a positive displacement pump when using the CHDT tool, is activated in reverse after completing the clean-out of the side bore 212 and a fluid is injected from an internal reservoir 231 through an inner flow line 232 of the tool into the side bore 212 . It is important for the present invention that the pad 22 maintains during the injection stages a seal between the well pressure Pw and the formation pressure Pf. The sealing pad in the present example seals an area of 7.3 cm by 4.5 cm. A pressure sensor 233 is used to monitor the pressure profile versus time during the operation. Any loss of seal can be noticed by comparing the pressure in the side bore with the well pressure Pw.
The injection pressure can be increased steps of for example 500 kPa increments, with pressure declines between each increment. Eventually the formation breakdown pressure is reached and a fracture 31 as shown in FIG. 3B develops at the location of the side bore 212 . Typically the initial fracture pressure is the highest pressure shown in the curves of FIG. 3C , which illustrates an initial pressure test and subsequent reopening tests as detailed below.
In the carbonate formation of 1-10 mD of the example the fracture initiation pressure was established as 19080 kPa. From the first fall off after this fracture initiation the instantaneous fracture shut in pressure is 18700 kPa corresponding to the moment the pump is stopped, followed by the fracture closure pressure of 17920 kPa. At the point the fracture closes the pressure decay changes its characteristic. The pressure at fracture closure is known to be a measure of the minimum horizontal stress.
As shown in FIG. 3C , subsequent increases in the injection rate by increasing the hydraulic motor speed from 300 to 1800 rpm do not alter the injection pressure, which fluctuated around the fracture propagation pressure. This insensitivity to injection rate suggests fracture propagation is dominating with little matrix injection. Of the six injection cycles following the fracture initiation and as illustrated in the curves of FIG. 3C , the fracture propagation pressure from the last three of 17500 to 17700 kPa were the most consistent, indicating the micro fracture 31 reaches deep enough into the formation to see far field stress conditions, i.e. the formation parameters unperturbed by the drilling of the main well 11 .
As the unperturbed stress are typically smaller than those dominant in the damaged zone 12 of the well 11 , the measurement is more representative while easier to perform.
There are two natural properties of low permeability formation that have been drilled with high pressure drilling fluid that may favor the application of the above methods. The first is the high pressure gradients that will exist in low permeability rock when subjected to a pressure disturbance. This means the elevated pressure zone surrounding the side bore will not extend far into the formation until a considerable time has elapsed after applying the pressurization to this side bore. The small volume of rock that is pressurized will be covered by the sealing pad that also seals the side bore.
The second natural property is the existence of a stress cage or “supercharged” zone 12 around the original drilled wellbore as shown in FIG. 3B . This zone 12 is created by the hydraulic force of the drilling fluid that supports the original well. The stress cage 12 is an annular volume of elevated stress several wellbore radii thick that surrounds any hole drilled with fluid at a pressure greater than the fluid pressure within the formation itself. The side bore 212 will partially penetrate this stress cage 12 . When the side bore is pressurized up to the breaking strength of the formation, the induced fracture 31 will most likely orientate itself away from this stress cage, propagating away from the main wellbore 11 .
This effect is believed to contribute to the fracture not intersecting the main well bore. And in turn it means that the seal of the pad covering the side bore is sufficient for the type of pressurizing and fracturing operation described above without requiring the use of further packers and the like to isolate the main well from the fracturing pressure.
A simulation of the isobars around the injection point is shown in FIG. 3D . The contours shown are flattened, radial cross-sections of pressure at the wellbore wall for an injection rate of 1 cc/s. The vertical (depth) and horizontal distances are both measured in meters. The contours are drawn at successive multiples of 5 bars above initial reservoir pressure, which is 137 bars in the example. They show for example that the approximate diameter of the pressure-zone of 15 bar or more above reservoir pressure is 6 cm while for the zone of 20 bar or more above reservoir pressure it is 3 cm in agreement with the dimensions of the sealing pad used.
Using the various fracturing and fracture propagation and closing pressures as established by the present method, more parameters can be deduced as described in detail in the co-owned U.S. Pat. Nos. 5,353,637 and 5,517,854. However, it is worth noting that following the present method ensures that a fracture is only generated at one location of the well 11 , whereas in known methods the fracture appears typically in the two equivalent directions of maximal horizontal stress. This change can be assigned to the inhomogeneous application of pressure in the well. Known methods as represented by the '637 and '854 patents generate a homogenous pressure along the circumference of the well. Following the present method, the pressure is confined to the location of the side bore.
By confining the pressure to single location and smaller volume a much smaller volume of fluid is required for the fracturing testing. Conventional fracturing tests on open hole formations with pairs of straddle packers generate fractures by pressurizing the much larger volume of the well between the two packers and create hence much larger fractures. With new method smaller volume of less than for example 100 liters or even less than 50 liters, appear sufficient to perform the tests. For most applications the volume of stored fracturing fluid can be chosen from the range of 5 to 20 liters. These small volumes enable the use of smaller high differential pumps which typically have a slow pump rate without extending the downhole test time. Furthermore dedicated and expensive fluids such as heavy liquids can be applied for testing in accordance with the present invention.
Moreover, while the preferred embodiments are described in connection with various illustrative processes, one skilled in the art will recognize that the system may be embodied using a variety of specific procedures and equipment. Accordingly, the invention should not be viewed as limited except by the scope of the appended claims.
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There is provided a method of testing a subterranean formation for fracture condition, including the steps of creating a side bore into the wall of a well traversing the formation, sealing the wall around the side bore to provide a pressure seal between the side bore and the well, pressurizing the side bore beyond a pressure inducing formation fracture while maintaining the seal and monitoring the pressure to identify the fracture condition.
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FIELD OF THE INVENTION
[0001] This invention relates to a pressure gauge, especially a pressure gauge having a pressure guiding bump, to which a fixed area is pressed to deform when a pressure is applied thereon.
BACKGROUND
[0002] FIGS. 1-6 is a prior art
[0003] FIG. 1 shows a prior art of a pressure gauge
[0004] A section view of the traditional pressure gauge is shown. A piezoresistor is made of a top stack TS and a bottom stack BS. A spacer 15 is inserted in between the two stakes in the periphery to make a center space 16 in between the two stacks.
[0005] The top stack TS includes sequentially from top to bottom: a top substrate 10 , a top metal electrode 11 , and a top piezoresistive layer 12 . The bottom stack BS includes sequentially from top to bottom: a bottom piezoresistive layer 129 , a bottom metal electrode 11 , and a bottom substrate 109 . A spacer 15 is inserted to form a center space 16 in between the top piezoresistive layer 12 and the bottom piezoresistive layer 129 . The top metal electrode 11 electrically couples to a first electrode of the electronic system 13 , and the bottom electrode 129 electrically couples to a second electrode of the electronic system 13 .
[0006] FIG. 2 is an initial status of the prior art
[0007] When a pressure is applied to the pressure gauge 100 initially, the top piezoresistive layer 12 bends down to touch the bottom piezoresistive layer 129 . Just before touching, an initial thickness L 1 is a total thickness of the top piezoresistive layer 12 plus the bottom piezoresistive 129 . An output resistance can be calculated according to ohm's law as: R 1 =τL 1 /A 1 . At initial status, the contact area A 1 at point P 1 approaches zero. Therefore, the output resistance R 1 is calculated to be infinite as follows:
[0000] R 1→∞ when A 1→0.
[0008] FIG. 3 is a stable status under pressure of the prior art
[0009] The pressure gauge 100 is pressed further so that the piezoresistive layers 12 , 129 are compressed and the total thickness L 2 of the two piezoresistive layers 12 , 129 becomes lesser than the initial thickness L 1 . In the meanwhile, the contact area A 2 at area P 2 is larger than the initial contact area A 1 . At this moment, the output resistance is calculated as follows:
[0000] R 2=ρ L 2/ A 2∘
[0010] FIG. 4 is pressure tests of the prior art
[0011] Three different points P 1 , P 2 , and P 3 are chosen to be tested in a prior art pressure gauge 100 . Point P 1 is the center of the pressure gauge 100 , point P 2 is a little far away from the center point P 1 , and point P 3 is even farther away from the center point P 1 . Various pressures are applied to each of the three points for checking the corresponding conductance, the conductance-pressure curves are then made as shown in FIG. 5 .
[0012] FIG. 5 is the conductance-pressure curves for points P 1 , P 2 , and P 3
[0013] The top line is for point P 1 , the middle line is for point P 2 , and the bottom line is for point P 3 . The curve for P 1 has a largest slop, the curve for P 2 has a less slop, and the curve for P 3 has a least slop. The curve slop is lesser as the test point farther away from the center. In other words, the farther a test point is away from the center, the less precision it becomes. Further in other words, different conductance can be obtained when a same pressure is applied at a different point of a traditional pressure gauge 100 . Curve P 1 has the best identification ability, curve P 2 has moderate identification ability, and curve P 3 has the worst identification ability. The position dependent curve-pressure feature makes the prior art pressure gauge 100 unreliable, unless a fixed test position is used. Take an example to see different conductance is obtained for a same pressure: a conductance of 6.5*10exp (−4)/ohm is obtained for curve P 1 at 20 psi; a conductance of 3.5*10exp (−4)/ohm is obtained for curve P 2 at 20 psi; and a conductance of 2.8*10exp (−4)/ohm is obtained for curve P 3 at 20 psi. Serious problems shall be caused if the prior art pressure gauge 100 is designed in a weighing machine with parallel connection. It becomes a big challenge as how to design a correction circuit to modify the deviation in order to obtain a linear output in order for realizing a weighing machine with the traditional pressure gauge 100 .
[0014] FIG. 6 is a pressure test with prior art pressure gauge.
[0015] FIG. 6 shows when a product Wt with a rugged bottom is put on a parallel connected prior art pressure gauges 101 , 102 , 103 which are configured on a substrate 209 . As shown in the figure, the rugged bottom of the product Wt touches point P 1 of the pressure gauge 101 , touches point P 2 of the pressure gauge 102 , and touches point P 3 of the pressure gauge 103 . It is difficult to obtain an accurate weight from the prior art pressure gauge 100 because of the non-consistent conductance-pressure curve for different points P 1 , P 2 and P 3 .
[0016] Now, please refer to FIG. 3 . The basic principle for the prior art follows the Law of Resistance R=ρL/A, the changes of the total thickness L, and the changes of the touching area A between the two piezoresistive layers 12 , 129 are two determinants for the output resistance R. Therefore, the prior art pressure gauge needs to consider the two factors when a pressure is applied, and especially when a pressure is applied on partial area instead of full surface of the pressure gauge 100 . Further more, an anti-pressure of the spacer 15 in the peripheral is another headache problem needs to be overcome for the prior art pressure gauge 100 . A single conductance-pressure curve for a pressure gauge independent of position with a stable and reproducible output is desired for a long time.
BRIEF DESCRIPTION OF THE DRAWING
[0017] FIG. 1˜6 Prior Art
[0018] FIGS. 7˜9 is a first embodiment according to the present invention.
[0019] FIG. 10 is a perspective view of a product according to FIG. 7
[0020] FIG. 11 is a modification design to FIG. 10 .
[0021] FIG. 12 is a constant conductance-pressure curve for a product of either FIG. 10 or FIG. 11
[0022] FIG. 13A is a parallel connection of pressure gauges as shown in FIG. 11
[0023] FIG. 13B is an equivalent circuit for a product of FIG. 13A
[0024] FIG. 14 is a testing example for FIG. 13A
[0025] FIG. 15 is a modification embodiment to FIG. 11
[0026] FIG. 16 is a first application embodiment of the present invention
[0027] FIG. 17 is a second application embodiment of the present invention
[0028] FIG. 18 is a third application embodiment of the present invention
[0029] FIG. 19 is an explosion diagram of FIG. 18
DETAILED DESCRIPTION OF THE INVENTION
[0030] A single conductance-pressure curve for a pressure gauge independent of position with a stable and reproducible output is accordingly devised to overcome the shortcomings of the prior art. The revised pressure gauge has a fixed deformable area which eliminates output deviation of the prior art.
[0031] A guiding bump which can be made of rubber or something similar is configured on top center of the pressure gauge; the guiding bump is a hard piece to press a fixed area independent of the magnitude of an applied pressure and independent of the position of the applied pressure. Because the deformed area A is a constant and therefore the thickness changes L of the deformed piezoresistive layers is the only consideration for the output resistance.
[0032] R=ρL/A, since deformable area A becomes a constant, the resistance is simplified as follows: R=kL
[0033] A pressure gauge with single conductance-pressure curve independent of position is obtained according to the invention. The anti-pressure caused from the spacer can be overcome by the arrangement of the guiding bump in a position of the top center and the guiding bump does not extend to the periphery of the pressure gauge. Since the modified pressure gauge has a single conductance-pressure curve, it is suitable to be designed in parallel connection with each other or one another to form an ideal weighing machine.
[0034] FIGS. 7˜9 is a first embodiment according to the present invention.
[0035] FIG. 7 is a section view of the structure of the first embodiment.
[0036] A guiding bump 21 is configured on the top center of the top substrate 10 of a prior art pressure gauge 100 as shown in FIG. 1 to form revised a pressure gauge 200 according to the present invention. The guiding bump 21 is located in an area not extending to the periphery to avoid the anti-pressure caused by the spacer 15 when a pressure is applied.
[0037] FIG. 8 is an initial status for FIG. 7
[0038] Initially, when a pressure is applied, the guiding bump 21 is downward pressed with a fixed deformable area A 1 , the deformed area A 1 is designed to be in a center area keeping away from the spacer 15 with a clearance A 2 to avoid the anti-pressure from the spacer 15 . The initial total thickness L 3 is the sum of the thickness of both piezoresistive layers 12 , 129 .
[0039] FIG. 9 is a stable status under a pressure for FIG. 7
[0040] A fixed deformable area A 1 is downward compressed. When stable, the total thickness L 4 becomes lesser than the initial total thickness L 3 . Thickness L 4 is a sum of the compressed thickness of the two piezoresistive layers 12 , 129 . Since the deformable area A is a constant, the output resistance R can be calculated according to the simplified formula:
[0000]
R=kL.
[0041] FIG. 10 is a perspective view of a product according to FIG. 7
[0042] A flat guiding bump 21 made of a hard material such as plastic, metal . . . etc is configured on the top center of the pressure gauge 200 . A fixed deformable area A 1 is downward compressed when a pressure is applied on the guiding bump 21 . The compressed area is always the same wherever the pressure is applied on the bump 21 , for example, a same conductance or resistance output is obtained if a same pressure is applied either at point P 4 , point P 5 , or point P 6 . Point P 4 is at the center of the bump 21 , point P 5 is a little far away from point P 4 , and point P 6 is even farther away from point P 4 .
[0043] FIG. 11 is a modification design to FIG. 10 .
[0044] A convex guiding bump 21 B is configured on the top center of the pressure gauge 300 . The structure is similar to the product of FIG. 10 . The feature and effect is the same as that of the product of FIG. 10 .
[0045] FIG. 12 is a constant conductance-pressure curve for a product of either FIG. 10 or FIG. 11
[0046] A single conductance-curve independent of position is shown as FIG. 12 for a product of either FIG. 10 or FIG. 11 . e.g. A same value of 6.0*10 −4 /ohm is obtained when a same pressure is applied either on point P 4 , P 5 , or P 6 to the product of FIG. 10 or FIG. 11 .
[0047] FIG. 13A is a parallel connection of pressure gauges as shown in FIG. 11
[0048] The product of FIG. 11 can be designed in a form of parallel connection so as to form a weighing machine for measuring bigger weights. A first pressure gauge 301 is connected in parallel with a second pressure gauge 302 . A first pressure F 1 and a second pressure F 2 can be added to output through a calculation circuit when the first pressure F 1 is applied on the first pressure gauge 301 and the second pressure F 2 is applied on the second pressure gauge 302 .
[0049] FIG. 13B is an equivalent circuit for a product of FIG. 13A
[0050] The first pressure gauge 301 represents a first variable resistor R 1 , and the second pressure gauge 302 represents a second variable resistor R 2 . Each of the first variable resistor R 1 and the second variable resistor R 2 reveals a same conductance-pressure curve feature. The output resistance R is calculated as: 1/R=1/R 1 +1/R 2 . When an object Wt with a weight WG weighs on a weighing machine of FIG. 13A , the weight WG is calculated as follows:
[0000]
WG
=
F
1
+
F
2
=
α
/
R
1
+
α
/
R
2
=
α
(
1
/
R
1
+
1
/
R
2
)
=
α
/
(
R
1
||
R
2
)
=
α
/
R
[0051] According to Ohm's law R=V/I, the weight WG is further calculated as:
[0000]
WG=α*I/V∘
[0052] Wherein, WG is the weight, F 1 is a force applied on the first gauge, F 2 is a force applied on the second gauge, and α is a constant.
[0053] This embodiment can be realized only when both the variable resistor R 1 and R 2 have a linear output for the resistance. The pressure gauges 200 , 300 according to this invention well satisfies the requirement to have a linear output.
[0054] FIG. 14 is a testing example for FIG. 13A
[0055] A weighing machine is made of three parallel connected pressure gauges 301 , 302 , 303 according to FIGS. 13A , 13 B. The three pressure gauges 301 , 302 , 303 are configured on a substrate 309 which can be a flexible or non-flexible one. Electric wires 308 are configured on top surface of the substrate 309 , and electrically couple each and all of the pressure gauges 301 , 302 , 303 to an electronic system (not shown). An object with a weight Wt has a rugged bottom surface and contacts the three pressure gauges 301 , 302 , 302 at points P 4 , P 5 , and P 6 individually. Point P 4 is on the center of the pressure gauge 301 , point P 5 is a little far away from the center of the pressure gauge 302 , and point P 6 is even farther away from the center of the pressure gauge 303 . A reproducible weight Wt can be obtained according to this invention; however which can not be obtained if made with traditional pressure gauges of FIG. 1 . This is because each of the three pressure gauges 301 , 302 , 303 has a single conductance-pressure curve feature which is independent of position to be pressed on each of the pressure gauges 301 , 302 , 303 .
[0056] FIG. 15 is a modification embodiment to FIG. 11
[0057] Two guiding bumps 21 C are configured on top surface of a pressure gauge 400 . Each of the guiding bumps 21 C is located in a position away from periphery to avoid the anti-pressure from the fringe spacer 15 . The effect for the pressure gauge 400 is similar to the pressure gauge 300 of FIG. 11 .
[0058] FIG. 16 is a first application embodiment of the present invention
[0059] A weighing machine 30 is made of the pressure gauge 300 of FIG. 11 . Each of four pressure gauges 300 is configured on bottom of each of the four corners of a hard plate 309 B. The four pressure gauges 300 are parallel connected and electrically coupling to a electronic system (not shown). A display 31 is configured to show the weight calculated from the electronic system.
[0060] FIG. 17 is a second application embodiment of the present invention
[0061] A flexible substrate 40 is used in this application for carrying a plurality of pressure gauges 300 . The pressure gauges 300 are arranged in a pattern of a matrix; however different pattern such as a pair of feet for standing, or boxing area for boxing games . . . etc., can be also realized. The flexible substrate weighing machine can be folded or rolled up to put away when unused.
[0062] FIG. 18 is a third application embodiment of the present invention
[0063] A flexible top stack TS, spacers 52 , and a flexible bottom stack BS are sandwiched to form a flexible piezoresistor strip. The top stack TS is composed sequentially of a top substrate, a top metal electrode, and a top piezoresistive layer. The bottom stack BS is composed sequentially of a bottom piezoresistive layer, a bottom metal electrode, and a bottom substrate. A plurality of pressure guiding bumps 51 are configured on top surface of the top substrate. Each of the guiding bumps 51 is configured in a position away from a position above spacers 52 .
[0064] FIG. 19 is an explosion diagram of FIG. 18
[0065] Spacers 52 are sandwiched in between the top stack TS and the bottom stack BS to create a predetermined space between the two stacks. The spacers 52 are configured in between top piezoresistive layer and bottom piezoresistive layer.
[0000] While several embodiments have been described by way of example, it will be apparent to those skilled in the art that various modifications may be made without departing from the spirit of the present invention. Such modifications are all within the scope of the present invention, as defined by the appended claims.
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A pressure guiding bump is configured on the center of a pressure gauge to obtain a single "conductivity-pressure" curve feature which is independent from any position wherever a pressure is applied on the guiding bump. When a pressure is applied, the guiding bump guides the pressure against a fixed deformable area to be deformed, whatever the pressure is, the deformed area is nearly a same area. The pressure gauge is extraordinarily adequate to be designed in a weighing machine with parallel connection in between them.
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CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001] This application claims priority from U.S. Provisional Patent Application No. 60/848,431, filed Sep. 29, 2006, herein incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to the field of drilling and specifically to small bore drilling of tubular plumbing components or material.
BACKGROUND OF THE INVENTION
[0003] There exist many applications requiring a hole to be made in a tube. For example, in plumbing systems, there is often a need to add an apparatus, such as a chemical cleaner dispenser, to an existing system requiring a hole to be made in the systems tubing.
[0004] Current systems typically utilize a punching mechanism that concentrates the force in a singular point on the outside wall of the tube. Other systems simply have a continuous rough cutting surface that can tear material from the outside wall, eventually producing a hole. However, such prior art methods and apparatus for creating a hole in thin walled tubing often results in distortion of the tube, the generating of metal burrs, or the generating of other defects in the hole or tubing that make mating of the hole with another tube or device difficult.
[0005] It is preferential for aesthetic purposes, and vandal-resistance purposes or reduction of inadvertent damage that the hole be made on the portion of the tube facing the wall. However, this presents difficulty due to the small clearance space between the tube and the wall. As such, prior art systems either require removal or rotation of the tube to allow the hole to be drilled or the drilling of a hole through both walls of the tube and the subsequent capping of the unneeded hole.
SUMMARY OF THE INVENTION
[0006] The present invention relates to apparatus and methods for cutting a hole in a tube or a tubular plumping component. In one exemplary embodiment, the present invention relates to an apparatus having a saddle clamp and a cutting device. The saddle clamp affixes to a tube and includes a threaded chamber for receiving the cutting device. The cutting device is preferably cylindrical and is likewise threaded to engage the chamber and includes at one end a cutting edge for engaging and cutting the tube and, at the opposite end, an actuation point for rotating the cutting device. In one embodiment, the actual thread pitch is based on the number of cutting edges and their shape. In one embodiment, the cutting edges are of a specific shape on the cutting face, with the cutting edges having a specific relief angle.
[0007] These and other objects, advantages, and features of the invention, together with the organization and manner of operation thereof, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, wherein like elements have like numerals throughout the several drawings described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is an exploded view of one embodiment of the present invention;
[0009] FIG. 2 is a partial cross-sectional view of FIG. 1 along line A-A (without the tool depicted);
[0010] FIG. 3A is a profile illustration of one embodiment of a cutting device of the present invention; and FIG. 3B is a close-up of the cutting teeth;
[0011] FIG. 4 illustrates one embodiment of the present invention for use in a urinal application providing a connection between a primary tube and a secondary tube; and
[0012] FIG. 5A illustrates a side-view of the cutting device of the present invention; and
[0013] FIG. 5B illustrates a side-view of the cutting device of FIG. 5A rotated 60 degrees about line B-B.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] The present invention relates to methods and apparatus for cutting a hole in a tube. In one embodiment, illustrated in FIG. 1 , the present invention relates to a system 101 for cutting a hole (not shown) in a material, such as a tube 103 . A saddle clamp 105 (shown assembled in FIG. 4 ) engages the tube 103 . The saddle clamp 105 comprises a front strap 107 and a rear strap 109 . In one embodiment, the saddle clamp 105 is designed to engage the tube 103 such that the front strap 107 and the rear strap 109 both include a semi-circular curved portion ( 110 , 111 respectively) for receiving the material (tube) 103 . The front strap 107 and the rear strap 109 are engageable with each other to form a ring having an opening in the middle for receiving the tube 103 therethrough. When assembled the saddle clamp 105 , i.e., the front strap 107 and the rear strap 109 , circumscribe the tube 103 . The front strap 107 includes a cutting chamber 113 . The cutting chamber 113 extends through the front strap 107 forming a passage therethrough perpendicular to a tube 103 disposed in the saddle clamp 105 . In one embodiment, the cutting chamber 113 provides a path through the front strap 107 to a portion of the tube 103 . The cutting chamber comprises an inner wall 115 ; and in one embodiment, the inner wall 115 of the cutting chamber 113 is threaded. In one embodiment, the cutting chamber 113 protrudes beyond the front strap 107 forming a cylindrical outcropping 116 having an outer wall 117 and continuing the inner wall 115 . In one exemplary embodiment, the outer wall 117 is threaded.
[0015] The present invention includes as part of the system 101 , a cutting device 120 which is engageable with the saddle clamp 105 . In an exemplary embodiment shown in profile view in FIG. 2 , and in a perspective view in FIG. 3A and front elevations FIGS. 5A and 5B , the cutting device 120 is cylindrical in shape, having a first end 121 and a second end 122 with a sidewall 123 therebetween which is substantially cylindrical in shape. In one embodiment, the sidewall 123 has threads (see FIG. 5A ) on its outer surface to operatively engage the threaded inner wall 115 of the cutting chamber 113 . The first end 121 includes at least one cutting edge 125 , best shown in FIG. 3B . In one embodiment, the cutting edge 125 is positioned at the end of at least one cutting tooth 132 . In an exemplary embodiment, the cutting edge 125 is defined by a plurality of separate cutting edges 125 positioned on a plurality of cutting teeth 132 . In an exemplary embodiment, the cutting edge 125 defines a circular cutting path (not shown), with the cutting teeth 132 rotating about the longitudinal axis A-A ( FIG. 1 ) of the cutting device 120 .
[0016] In the present invention, the cutting edge 125 is discontinuous and is formed on at least one cutting tooth 132 which protrudes from the first end 121 . In an exemplary embodiment, the cutting edge 125 is formed on multiple cutting teeth 132 which serve to stabilize the cutting device 120 during cutting, as each cutting tooth 132 enters the cut, the forces of other ones of the cutting teeth 132 engaged in the cut are counterbalanced.
[0017] To effect a cut, it is required that the cutting forces be concentrated between the cutting device 120 and the tube 103 being cut; thus generating a high local stress point on the tube 103 . It is generally accepted that this condition is difficult to maintain as the cutting device 120 advances into and through the tube 103 as more of the cutting edge 125 comes into contact with the tube 103 . The profile of the tube 103 to be cut can further complicate the process of cutting a hole, thereby making use of the described cutting device 120 more important.
[0018] The at least one cutting edge 125 engages a portion 133 of wall 134 of the tube 103 (see FIG. 1 ), the portion 133 being positioned opposite the passage (the cutting chamber 113 ) through the front strap 107 . In one embodiment, the cutting device 120 is rotated with the threads of its sidewall 123 engaging the threads of the cutting chamber 113 inner sidewall 115 , resulting in movement of the cutting device 120 through the cutting chamber 113 relative to the saddle clamp 105 and the tube 103 . The at least one cutting edge 125 engages the portion 133 and rotates about a longitudinal axis A-A as the cutting device 120 is rotated, thus defining a cutting path (not show). In one embodiment, the cutting path (not shown) is substantially circular. In one embodiment, the rotation of the cutting device 120 results in the threads on the outerwall 123 engaging those of the inner wall 115 , advancing the cutting device 120 along the longitudinal axis A-A. This forces the cutting edge 125 against the portion 133 by gradual movement of the cutting device 120 forward in the cutting chamber 113 as the cutting edge 125 cuts into the wall 134 .
[0019] Several factors that need to be balanced in determining the size and number of cutting teeth 132 . For example, the cutting edge 125 can be designed to cut a range of different tube diameters, for example tubes ranging from ¾-inch to 1½-inch outside diameter with a wall thickness of approximately 1/32-inch. In one embodiment, a thicker wall section of the tube 103 could be cut by making the cutting device 120 longer. In one embodiment, the length of the cutting edge 125 is optimized for the tube wall thickness and the minimum clearance available to access the tube 103 .
[0020] To highlight the challenge in cutting through a wide variety of tube diameters, one can compare the diameter of the hole cut by the cutting device 120 to the diameter of the tube 103 through which the hole is cut. In one embodiment, in the smallest diameter the ratio of cut hole to the tube diameter is 0.333 and in the largest case this ratio is reduced to 0.167. The large tube diameter being two-times larger, and therefore the surface to be cut is flatter.
[0021] In one embodiment, the cutting device 120 comprises a “fishtail” type design having angled cutting edges (see FIGS. 3A and 3B ). In one embodiment, the angled cutting edges are curvilinear in nature such that they substantially define a circulating cutting path. As shown in FIG. 3A and FIG. 3B , the “fishtail” design includes a first angled face 135 and a second angled face 136 . The first angled face 135 has an outer cutting edge 150 and an inner edge 151 . The farthest protruding portion of the first angled face 135 forms a cutting point 137 . In the embodiment shown in FIGS. 3A and 3B , the cutting device is rotated counterclockwise (for a user viewing from the head 127 , along the side wall 123 to the second end 122 , the head 127 would be rotated clockwise). This rotation results in the cutting point 137 forming the leading point of the tooth 132 . The second angled face 136 has an outer edge 152 and an inner edge 153 . In one embodiment, the angled faces 135 and 136 are convex, allowing the edges 152 and 153 to engage the tube rather than the surface of the angled faces 135 and 136 . In one embodiment the angle of the first angled face 135 with respect to a plane formed by a circular cross-section of the cutting device 120 is less than 145 degrees; and the angle of the second angled face 136 is more than 45 degrees.
[0022] The “fishtail” design of one embodiment of the present invention is intended to minimize distortion of the tube 103 by directing forces inward toward the axis of the hole being cut. Material displacement takes place only on the inside of the circular cutting path; and thus the distortion occurs primarily on the discarded slug.
[0023] In one embodiment, the angle of the “fishtail” design is determined primarily by the smallest diameter tube that would be encountered. This allows the “fishtail angle” design to first engage the tube 103 with the outer edge 152 . Moreover, concentration of cutting forces on the cutting point 137 and outer edge 152 also serves to quickly and easily penetrate the tube 103 , of particular importance in applications such as hard-chrome plated plumbing fixtures.
[0024] For embodiments with only one cutting tooth 132 , a moment is generated in the cutting device 120 perpendicular to a longitudinal axis of the cutting device 120 . This moment increases the load on the cutting surface, increasing the potential to fracture the cutting device 120 . Though it does not increase the difficulty to cut, it does seek to deflect the cutting edge 125 and change the course of the cutting edge 125 while exposing it to shear stress along its length. With only one tooth 132 , all of the cutting forces, tensile and torsional, are concentrated in one small area. Adding a second cutting tooth 132 , which is 180° from the first, results in a balanced dispersion of cutting forces, canceling this moment and directing the force axially into the tube 103 . Having both the cutting teeth 132 engaged in the cut simultaneously balances and reduces the tensile and shear loads, but increases the torsional load on the cutting device 120 .
[0025] In other embodiments, the cut being made is an interrupted cut increasing the chance of fracturing the cutting tooth 132 . In one embodiment, three cutting teeth 132 are used to maintain a balance of the forces and manufacturability. With three cutting points there is always at least one point in contact with the tube 103 ; particularly in the critical early phase of starting the cut. In one embodiment, four or more cutting teeth are utilized. Four or more cutting teeth would be an improvement by reducing the feedrate or depth of cut per the cutting teeth 132 , but more difficult from the perspective of cutting device manufacture.
[0026] The pitch of the threads (sidewall 123 of the cutting device 120 and inner wall 115 of the cutting chamber 113 ) is chosen to achieve an appropriate advance of the cutting device 120 through the cutting chamber such that the cutting device 120 would advance at such a rate so as to not damage the cutting edges, 150 , 151 , the cutting point 137 or the surface to be cut. Advancing too quickly could break the cutting device 120 rendering it unusable. However, an aggressive feedrate is required to penetrate some material, such as nickel chrome plating used in plumping fixtures. Advancing too slowly will allow the hard chrome to distort and dull the cutting edges, 150 , 151 . which also leads to the cutting device 120 . In one embodiment, a standard pitch thread of, 124 threads per inch, is utilized.
[0027] In one embodiment, the cutting device 120 includes an actuation mechanism, such as the head 127 for rotating the cutting device 120 , causing the cutting device 120 to pass axially through the cutting chamber 113 . In an exemplary embodiment shown in FIG. 1 , the saddle clamp 105 is removably affixed to the tube 103 with a portion of the tube 103 exposed via the cutting chamber 113 . The cutting device 120 is engageable with the cutting chamber 113 such that the cutting edge 125 engages the tube 103 . In one embodiment shown in FIG. 3A , the actuation mechanism comprises a shaped head 127 at the second end 122 opposite the at least one cutting edge 125 for engagement by a tool 130 . For example, the head 127 may be shaped to correspond to a tool 130 (see FIG. 1 ) allowing for engagement of the cutting device 120 by the tool 130 . One of ordinary skill in the art will appreciate the multitude of ways to engage the cutting device 120 ; and thus, the head 127 could, for example, include without limitation a Philips type slot, a straight slot, or a hex-head design.
[0028] In a further embodiment, the present invention relates to a method of cutting a hole in the tube 103 . The rear strap 109 and the front strap 107 of the saddle clamp 105 are positioned on the tube 103 and affixed to each other with the tube 103 disposed therebetween. The cutting device 120 is inserted into the threaded cutting chamber 113 , such that the at least one cutting edge 125 is proximate the tube 103 . The cutting device 120 is turned so as to interact the threads of its sidewall 123 with the threads of the inner wall 115 of the cutting chamber 113 . Rotation of the cutting device 120 draws the cutting device 120 into the cutting chamber 113 , and the cutting edge 125 approaches the portion 133 of the tube wall 134 . As the cutting point 137 contacts the portion 133 of the tube wall 134 , the cutting edge 125 traverses a circular path, cutting into the tube wall 134 . The cutting edge 125 cuts a hole through the tube wall 134 as the cutting device 120 is rotated. The interaction of the threaded sections 115 and 123 advances the cutting edge 125 forward (along A-A) as the cutting device 120 is rotated. One of ordinary skill in the art will appreciate that a plurality of revolutions of the cutting device 120 may be necessary to completely cut a hole into the tube wall 134 , depending in large part on the thickness of the tube wall 134 .
[0029] In one embodiment, the system 101 of the present invention is engagable with a secondary tube 104 providing a connection between the secondary tube 104 and the primary tube 103 . For example, in one embodiment the tube 103 is a part of a water closet fixture. After the hole is cut in the tube 103 , as described above, a secondary tube 104 is inserted into the cutting chamber 113 . In an exemplary embodiment shown in FIG. 4 , the secondary tube 104 includes a threaded nut 144 which corresponds to threads on the outer wall 117 of the cutting chamber 113 . The nut 144 can be drawn down to fix the secondary tube 104 to the saddle clamp 105 , providing fluid communication between the tubes 103 and 104 . In one embodiment, a seal 142 is provided between saddle clamp 105 and the tube 103 ( FIG. 1 ). The seal 142 assists in sealing the tube 103 and the secondary tube 104 .
[0030] In another embodiment (shown in FIGS. 1 and 2 ), the tool 130 ( FIG. 1 ) is provided which comprises at a first end an opening for engaging the actuation mechanism of the cutting device 120 and at a second end an opening for engaging the nut 144 of the secondary tube 104 ( FIG. 2 ). In one embodiment, the tool 130 is provided with a slot for insertion of a leverage device (not shown).
[0031] The foregoing description of embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the present invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the present invention. The embodiments were chosen and described in order to explain the principles of the present invention and its practical application to enable one skilled in the art to utilize the present invention in various embodiments, and with various modifications, as are suited to the particular use contemplated.
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A device for creating a hole in a tube. The tube includes a saddle clamp positioned thereon. The saddle clamp has a threaded cutting chamber, and the cutting device is insertable and engageable with the threaded saddle clamp, the cutting device having a cutting edge. The cutting device is engageable with the cutting chamber to axially move therethrough towards the tube as the blade device is rotated.
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FIELD OF THE INVENTION
The present invention relates to a clasp suitable for use on an article of jewellery such as a bracelet or necklace to hold opposite ends thereof together.
BACKGROUND OF THE INVENTION
A clasp is already known from British patent specification No. 540913 of the kind comprising a link member in the form of a jump ring and, for engagement therewith, a clasp part in the form of an open ring member which effectively constitutes a hook having a barb terminating the hook inwardly of the ring. In connecting the two parts of the clasp, the jump ring needs to be negotiated over the barb before the jump ring becomes hooked in position.
However, this clasp can accidentally be released and this could lead to loss or damage to the article being worn.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a clasp of the kind described above, in which the link member can only be fully engaged and then disengaged from said clasp part by a predetermined series of movements such that inadvertent disengagement of the two parts of the clasp is highly improbable, while retaining a clasp of simple design.
It is a further object of the present invention to provide a clasp of the kind described above, in which said clasp part provides a slot to receive a part of the link member such as to require first a change in the orientation of the two parts of the clasp before the link member can be disengaged.
It is a still further object of the present invention to provide a clasp of the kind described above, in which said clasp part provides a slot to receive a part of the link member such that a part of the slot requires the link member to be passed therealong with an orientation other than the one it assumes in use of the clasp.
It is a still further object of the present invention to provide a clasp of the kind described above, in which said clasp part provides a slot to receive a part of the link member and comprises members effectively to hid the slot from view.
SUMMARY OF THE INVENTION
Briefly, in one aspect, the present invention provides a clasp of the kind comprising a clasp part and, for engagement therewith, a complementary link member; the clasp part being such that said member needs to be negotiated thereinto to assume the position it occupies in use of the clasp, wherein said clasp part comprises a body and a slot formed in said body; the slot following the path of a labyrinth and being open at a surface of the body to permit the link member to be passed along the labyrinth to lodge therein remote from the place on the body at which the slot starts (hereinafter called the mouth) with part of said member lying externally of the body; the labyrinth of said clasp part being dimensioned so that, with said member and the clasp part in the positions they occupy in use, said member can be removed from the clasp part only by a relative movement between said member and clasp part which first entails a change in the orientation of said member and clasp part relatively to one another.
The present invention also provides said clasp part for use with a complementary link member therefor. Preferably, the change in orientation is a relative rotation of the two parts through substantially 90°. It is also preferred that the slot be such as then further to require a relative rectilinear movement between the two parts in at least two directions which are substantially mutually perpendicular to one another. In one embodiment, the further movement therefore takes the form of the two parts relatively describing a general "L" shape, and in another embodiment it takes the form of the two parts relatively describing a general "S" shape.
In one embodiment, the slot follows a generally "U" shaped path; and the limb thereof remote from the mouth is of shorter length than the other limb thereof, and it is also at its remote extremity inturned. Said clasp part may comprise a substantially planar plate of circular or other e.g. rectangular shape; and the invagination may be formed in it by stamping. The plate may be made of metal or plastics or any other suitable material.
In a further aspect, the present invention provides a clasp of the kind comprising a clasp part and, for engagement therewith, a complementary link member; said clasp part being such that said member needs to be negotitated thereinto to assume the position it occupies in use of the clasp, wherein said clasp part comprises a body and a slot formed in said body; said slot following the path of a labyrinth, and being open at a surface of the body to permit said member to be passed along the labyrinth to lodge therein remote from the place on the body at which the slot starts (hereinafter called the mouth) with part of said member lying externally of the body; the slot at least in the part thereof immediately preceding the place said member assumes in use in the slot, being of cross sectional dimension such, and the cross sectional dimension and shape of the portion of said member to pass within the slot, being such, as to prevent any substantial rotation of said member when that portion thereof lies in said part of the slot; and the slot providing a following enlarged portion to permit a relative rotation of the two parts to be effected to the position they assume in use of the clasp.
In a further aspect of the present invention a clasp comprises members spaced from the surfaces of the body at which the slot opens, otherwise than at the mouth thereof, effectively to hide the slot from view. The members may be formed integrally with the body or they may be separately formed and attached thereto. The members may be such or be so treated as to have a decorative appearance at least on the surfaces thereof not facing the body. In the presently preferred embodiment, the members are in the form of substantially planar walls of the same shape as the plate constituting the body.
DESCRIPTION OF PREFERRED EMBODIMENTS
Other features and advantages of the present invention will become apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which like reference numerals indicate like parts and in which:
FIG. 1, consisting of FIGS. 1a, b, c and d, each showing a front elevation of a clasp part according to the present invention, illustrates how the clasp part is united with a complementary part (being a chain link) to form a clasp;
FIG. 2 is a view of the clasp parts in the direction of arrow "X" in FIG. 1;
FIGS. 3 and 4 are respectively a front elevation and side elevation of a modified complementary part;
FIG. 5 is a front view of modified form of the clasp part of FIG. 1;
FIGS. 6, 7 and 8 are views of a further form of clasp in accordance with the present invention, being respectively a front elevation thereof, a plan view thereof showing the complementary part in one position and a plan view thereof showing the complementary part in another position;
FIGS. 9 and 10 are perspective views of modified forms of the clasp part of FIG. 1;
FIGS. 11 and 12 are respectively a front elevation and plan view of a still further form of clasp in accordance with the present invention.
It is here pointed out that in all the Figures of the drawings, the parts are shown on an enlarged scale in the intersects of clarity; the actual size being approximately half that shown.
Referring now to the drawings, the clasp part shown in FIG. 1 comprises a link member 2 and a clasp part for mutual engagement; the latter comprising a body in the form of a substantially planar disc generally indicated at 1 formed with a slot 3 following the path of a labyrinth or maze; the start of which opens at the periphery of the disc to define the mouth 7 of the slot. The path, in this instance, has the general shape of a "U" with the limb 9 remote from the mouth being shorter than the opposite limb 11 and being somewhat inturned inwardly of the "U" at the remote extremity 13 thereof.
The disc is formed with a flat 8 at the peripheral edge of the disc extending from one side of the slot so that part of the peripheral edge of the disc is substantially parallel with the course of the bridge 12 of the "U", the bridge having a cross-sectional dimension slightly greater than the external diameter of the part of the link member to engage in the invagination.
In this instance, the link member is part of an end link generally indicated at 15, of a chain. In this case, the clasp part would be secured to the opposite link of the chain. The slot of the clasp part also opens at the surface of the body on each major face thereof so that a part 17 of the loop formed by the link 15 can be passed through the mouth of the slot by an approach as shown by arrow "A" in FIG. 1 and along the path as indicated by arrow "B" in FIG. 1b to the remote end thereof (FIG. 1c) to assume the position shown in outline in FIG. 1c. It is then raised, as viewed in FIG. 1c, from the position indicated in outline in that Figure, and pivoted in the direction indicated by arrow "C" in FIG. 1c to the position indicated in full line to draw the end 17 of the link into the inturned end 13 of the slot, and is then pivoted from that position (indicated in outline in FIG. 1d ) to the position it is to assume in use of the clasp as indicated in full line in FIG. 1d. The cross-sectional dimension "x" of the bridge 12 is such, and the cross-sectional dimension "y" of the part 14 of the link member passed into the slot and the shape thereof at are such, as to prevent any substantial pivoting of the member when the part 14 lies in the bridge 12. As a result, when the link member is in the position shown in full line in FIG. 1d, it cannot be passed along the bridge 12. In order to permit pivoting of the link member to its final position, the shorter limb 9 of the "U" is formed with a cross-sectional enlargement as indicated at 10 in FIG. 1.
In this connection, it is preferred in order to facilate the user's entering the loop into the slot, that the limb 11 be of a cross-section dimension greater than is strictly needed to permit entry of the loop i.e. it is preferred that it be of greater cross sectional dimension than the bridge 12. In use of the chain, the ends of which are thus clasped together, the link member is virtually incapable of any movement, whether during handling by the user to put it on or take it off or during the time the chain is being worn, that can remove the link member from the body. If the link pivots contrary to the direction of arrows "D" in FIG. 1d from the position shown in full line in FIG. 1d, the part of the link within the slot catches on the lip 19 formed by the turned-in portion 13 of limb 9. If it pivots in the direction of arrow "D" from the position in FIG. 1d, removal is prevented by the chain link 5 to which the body is secured. If, however, the link and body are moved relatively towards one another, removal is stopped by the part 14 of the link. It follows that these movements cannot separate the link 15 from the body.
It will be evident from the above that the link member can only be removed by precisely reversing the movements by which it is moved to the position it assumes in use and that this operation first requires a change in the relative orientation of the link member and clasp part.
In the illustrated embodiment of FIG. 1, the dimension "a" measuring the internal axial length of link 15 is only slightly greater than the length "a 1 " of the shorter one of the two opposite walls 21, 23 constituting limb 11 and is less than the length "a 2 " being the length of the shorter wall 24 of bridge 12 plus its rectilinear extension to the periphery of the body, so that, even if the part 14 of the link member could be entered into the bridge 12 of the slot, it could not be removed by a first movement which simply entails a movement of the link member and clasp part towards one another, and would still require in the reverse movement of link 15 to release it, fairly precise positioning of the link in relation to the body to assume the positions shown in FIG. 1 especially due to the presence of the flat 8. The chance of this happening unintentionally is very remote. Therefore in a modification of the illustrated embodiment, the bridge 12 is such that the part 14 of the link member can be entered into it by a movement of the two parts towards one another.
FIGS. 3 and 4 show an alternative link member differing from the link part shown in FIGS. 1 and 2 only in having the lateral flanges 31, 33 of wider dimension i.e. dimension "b" is greater than dimension "b 1 ". The part shown in FIG. 5 is substantially identical to part 1 shown in FIGS. 1 and 2 but is of lighter weight due to cut-out portions 35, 37.
The embodiment of FIGS. 6 to 8 differs from that of FIG. 1 only in shape and in the thickness of disc 1 and integral link 5, and providing a longer bridge 12.
In the modifications shown in FIGS. 9 and 10, the body is covered with wall members 25, 27 spaced from the surfaces of the body at which the slot opens; the only difference between the two modifications being that of the shape of the wall members. The wall members may be secured or made integral with a part of the body as indicated generally at 29 in FIG. 1. If a plastic material is used for the body and wall members, it may be possible integrally to form them.
In the case where the body is made of metal and is to be used with another metal part, it may be welded thereto.
In the embodiment of FIGS. 11 and 12, the body is rectangular in shape and the slot is in the form of a general "S" shape. However, the internal axial dimension "c" of the loop is again less than the dimension "c 1 " of the body and only slightly greater than the dimension "c 2 " of the body; but due to the "S" shape, the body provides even greater difficulty in the unintentional separation of the two parts of the clasp. Further, the cross-sectional shape and dimensions of part 14 of the link member and the cross-sectional dimensions of limbs S1, S2 and S3 are such that the link member cannot be pivoted in these limbs, thus again a precise positioning of the member in relation to the clasp part in the movements to engage and disengage the two parts is required.
As will be evident from the above, in the embodiments of FIGS. 1 to 10, the disengagement of the link member from its position shown in full line in FIG. 1d to remove it from the other clasp part entails, following the change in relative orientation to the other clasp part, the two parts relatively to describe a movement along a generally "L" shaped path, that is, a movement in two mutually perpendicular directions, and in the embodiment of FIGS. 11 and 12 the following movement describes a movement along a generally "S" shaped path, that is, a movement in more than two mutually perpendicular directions.
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The clasp of the disclosure is of the kind comprising a clasp part and, for engagement therewith, a complementary link member; said clasp part comprising a body formed with a labyrinthine slot open at a surface of the body to permit said member to be passed thereinto to lodge therein remote from the mouth of the slot with part of said member lying externally of the body; the labyrinth being dimensioned so that, with said member and the clasp part in operative positions, said member can be removed from the clasp part only by a relative movement which first entails a change in their relative orientation.
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FIELD OF THE INVENTION
[0001] The present invention relates to a hole saw with interchangeable cutting or drilling blades. In particular, a hole saw adapted to receive a plurality of cutting blades of different cutting configurations.
BACKGROUND OF THE INVENTION
[0002] Hole saws are a very widely used tool for many applications. Typically a hole saw includes a flat solid base that is locked by a drill, the base providing support for the hole saw. Some bases include multiple diameter grooves adapted to accommodate hole saws of different diameters. Typically these bases, with a plurality of concentric grooves, are of a diameter greater than the hole saw blade and as a result drilling depth is limited to the length of the hole saw body portion. This limitation restricts the possible uses of the hole saw and possible surfaces able to be drilled.
[0003] Other hole saws are single sized, overcoming the abovementioned problem of a larger diameter base but requiring the user to change the entire hole saw for each application. A user with a single sized hole saw needs to replace the hole saw for each surface being drilled as well as for each different diameter hole. The removal and installation of hole saw bodies for each new application or following the failure of a hole saw blade is troublesome, labour intensive, and time consuming.
[0004] Holes saw blades use different cutter materials and configurations to more effectively cut the surface being drilled. For example, serrated carbide tipped hole saws are generally used to drill harder and more abrasive surfaces than is possible with a regular steel blade. Some composite woods are more effectively cut with a different blade configuration and are best cut with a single tooth carbide tipped cutting element. Abrasive materials such as glass, ceramics, stone, asbestos and some plastic surfaces also require different cutting materials and configuration of the hole saw blade. A diamond or carbide grit encrusted blade is typically used in these applications. As each application may require a different hole saw blade configuration, the user is required to maintain an inventory of different hole saws for each surface to be drilled and each diameter of hole, inclusive of back up hole saw bodies in the event of blade failure. Such a large inventory is both cumbersome and expensive.
[0005] It is therefore an object of the present invention to overcome the aforementioned problems and to provide the public with a useful alternative.
SUMMARY OF THE INVENTION
[0006] Therefore in one form of the invention there is proposed a hole saw including:
[0000] a hole saw body portion; and
a hole saw blade portion, wherein said hole saw blade portion is removably attached to said hole saw body portion.
[0007] Preferably said hole saw blade portion includes at one end a cutting blade and at the other end an engagement means.
[0008] Preferably said hole saw body portion includes at one end an attachment means adapted to receive said engagement means of the hole saw blade and at the other end a plurality of bores including at least a central bore.
[0009] Preferably said engagement means includes at least one lug extending longitudinally from the hole saw blade portion.
[0010] Preferably said central bore is adapted to receive a drill bit, wherein said drill bit extends through and beyond said hole saw blade portion.
[0011] In a preferred embodiment said engagement means of the hole saw blade portion is adapted to be received by the hole saw body portion attachment means rotatably from a first to a second position, wherein said first position the hole saw blade portion is freely insertable and removable from the hole saw body portion and in said second position at least one said extending lug is adapted to be retained by said attachment means thereby locking the hole saw blade to the hole saw body.
[0012] In another embodiment said engagement means of the hole saw blade portion is adapted to be received by the hole saw body portion attachment means using an interference fit to retain at least one said extending lug with said attachment means.
[0013] In a further embodiment said hole saw body portion further includes at least one retention clip longitudinally slidable from a first to a second position, wherein said first position the hole saw blade portion is freely insertable and removable from the hole saw body portion and in said second position said retention clip extends into said hole saw blade portion thereby locking the hole saw blade to the hole saw body.
[0014] In preference said retention clip does not extend radially out from the hole saw body portion.
[0015] In a still further form of the invention said hole saw blade portion and said hole saw body portion further include a annular groove adapted to retain a C clip, wherein said C clip is inserted into said annular groove when said hole saw body portion and said hole saw blade portion are abutted together thereby locking the hole saw blade to the hole saw body.
[0016] In preference said C clip does not protrude radially from the hole saw body portion or the hole saw blade portion.
[0017] In a still further for of the invention said hole saw body portion further includes at least one locking strip projecting longitudinally from the hole saw body portion at one end and attached to said hole body portion at the other end, wherein said locking strip is biased from a first to a second position and includes a protrusion adapted to be received by a corresponding aperture in said hole saw blade portion thereby locking the hole saw blade portion to the hole saw body when said biased locking strip is in the first position.
[0018] An advantage of such a interchangeable hole saw blade arrangement is that a hole saw blade may be rapidly removed and reattached.
[0019] Still a further advantage is that by utilising such a removably attachable hole saw blade portion a user requires less room to store a plurality of hole saw blades for different applications.
[0020] Still a further advantage is that said hole saw body can be used with commonly available hole saw mandrels.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several implementations of the invention and, together with the description, serve to explain the advantages and principles of the invention. In the drawings:
[0022] FIG. 1 a illustrates a perspective view of a hole saw body and a hole saw blade in a disengaged position;
[0023] FIG. 1 b illustrates a perspective view of a hole saw body and a hole saw blade in an inserted position;
[0024] FIG. 1 c illustrates a perspective view of a hole saw body and a hole saw blade in a locked position;
[0025] FIG. 2 illustrates a cross sectional view of a hole saw body and a hole saw blade in a locked position;
[0026] FIG. 3 illustrates a top view of a hole saw body and a hole saw blade in a locked position;
[0027] FIG. 4 a illustrates a perspective view of a hole saw body and a hole saw blade in a disengaged position;
[0028] FIG. 4 b illustrates a perspective view of a hole saw body and a hole saw blade in an inserted position;
[0029] FIG. 4 c illustrates a perspective view of a hole saw body and a hole saw blade in a locked position;
[0030] FIG. 5 illustrates a cross sectional view of a hole saw body and a hole saw blade in a locked position;
[0031] FIG. 6 illustrates a top view of a hole saw body and a hole saw blade in a locked position;
[0032] FIG. 7 a illustrates a perspective view of a hole saw body and a hole saw blade in a disengaged position;
[0033] FIG. 7 b illustrates a perspective view of a hole saw body and a hole saw blade in a locked position;
[0034] FIG. 8 illustrates a cross sectional view of a hole saw body and a hole saw blade in a locked position;
[0035] FIG. 9 illustrates a top view of a hole saw body and a hole saw blade in a locked position;
[0036] FIG. 10 illustrates a top view of a hole saw body and a hole saw blade in a locked position;
[0037] FIG. 11 a illustrates a perspective view of a hole saw body and a hole saw blade in a disengaged position;
[0038] FIG. 11 b illustrates a perspective view of a hole saw body and a hole saw blade in a locked position;
[0039] FIG. 12 illustrates a perspective view of a hole saw body and three different hole saw blade configurations;
[0040] FIG. 13 illustrates a perspective view of a hole saw body and an alternate locking means of the hole saw blade;
[0041] FIG. 14 illustrates a perspective view of a hole saw body and a further locking means of the hole saw blade;
[0042] FIG. 15 illustrates the locking means of FIG. 14 without a hole saw blade;
[0043] FIG. 16 illustrates the locking means of FIG. 15 with a steel hole saw blade attached and locked thereto;
[0044] FIG. 17 illustrates the locking means of FIG. 15 with a concrete saw blade attached and locked thereto; and
[0045] FIG. 18 illustrates the locking means of FIG. 15 with a timber hole saw blade attached and locked thereto.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0046] The following detailed description of the invention refers to the accompanying drawings. Although the description includes exemplary embodiments, other embodiments are possible, and changes may be made to the embodiments described without departing from the spirit and scope of the invention.
[0047] FIGS. 1 a , 1 b and 1 c show a perspective view of one embodiment of the present invention. Shown in the figures is a hole saw 10 including a hole saw blade portion 12 and a hole saw body portion 14 . The hole saw blade 12 includes a cylindrical body with at least one cutting tooth 16 at one end thereof. The arrangement of the cutting teeth differs for each application and in this embodiment shown is a hole saw blade 12 with a plurality of cutting teeth 16 . The hole saw blade also contains circular apertures 18 in its cylindrical body to reduce material needed in the construction of a hole saw blade and provide a cooling effect. At the opposite end of the hole saw blade 12 is the engagement means by which the blade is attached to the hole saw body 14 .
[0048] The engagement lug 20 extends longitudinally from the end of the hole saw blade 12 and shown in this figure is a plurality of repeating dog leg shaped engagement lugs 20 , whereby, the lug is comprised of a rounded recessed portion 22 , a rounded protruding portion 24 , and a substantially flat portion 26 . Between each repeating dog leg shaped extending lug 20 is the base 28 of the hole saw blade portion which has a width greater than the width of the substantially flat portion 26 of the extending lug 20 .
[0049] The hole saw body 14 includes a cylindrical body which may contain slots 30 extending longitudinally along the length of the hole saw body to assist with the removal of the core and reduce the amount of material required for the manufacture of the hole saw body. The hole saw body 14 further includes at one end an attachment means to attach the hole saw body to the hole saw blade 12 . The attachment means comprises of an engagement lug 32 extending longitudinally from the end of the hole saw body 14 . Shown in this figure is a plurality of repeating dog leg shaped engagement lugs 32 , whereby, the lug is comprised of a rounded protruding portion 34 , a rounded recessed portion 36 , and a substantially flat portion 38 . Between each repeating dog leg shaped extending lug 32 is the surface 40 of the hole saw body.
[0050] Shown in FIG. 1 b is the hole saw blade 12 and the hole saw body 14 abutted together in a first position. In this position the flat portions 26 of the engagement lugs 20 lie substantially parallel with the flat hole saw body surface 40 and the protruding portion 24 of the dog legged engagement lugs has not entered the receded portion 36 of the hole saw body engagement lug 32 . In this first position the hole saw body 14 and hole saw blade 12 are removable and insertable and not locked together. FIG. 1 c shows the hole saw body 14 and hole saw blade 12 rotated to a second position thereby locking the abovementioned blade to the body. The direction of rotation of the hole saw enables the blade to be retained during use. Such an attachment means may also utilise an interference fit to further retain the blade to the body.
[0051] FIG. 2 illustrates a cross sectional view of the hole saw body portion 14 and the hole saw blade portion 12 locked together. FIG. 3 illustrates the same arrangement in a top view. Shown in these figures, at the opposite end to the hole saw blade portion, is the means of fixing the hole saw body 14 to a mandrel (not shown). Also, a central bore 42 is adapted to receive a drill bit (not shown) wherein the drill bit extends through and beyond the hole saw blade portion 12 to guide the hole saw. Holes 44 and 46 are adapted to be a component of the arrangement used to fix the hole saw body 14 with a base or mandrel (not shown).
[0052] FIGS. 4 a, 4 b and 4 c illustrate an alternative embodiment of the present invention. The present invention includes further means of retaining the hole saw blade portion to the hole saw body portion. In this embodiment the hole saw blade portion 12 includes at one end at least one cutting element 16 and at the other end an engagement means by which the blade is attached to the hole saw body 14 .
[0053] The engagement means on the hole saw blade 12 further includes at least one engagement lug 48 extending longitudinally from the flat edge 50 of the hole saw blade portion 12 . Shown in this figure is a plurality of repeating teeth shaped engagement lugs 48 whereby the lug projects at an acute angle from the hole saw blade portion 12 with the angle of the leading edge of the lug 48 being greater than the angle of the trailing edge. The hole saw blade portion 12 further includes at least one substantially rectangular recession 52 with an angular depression 54 approximately about half way up the side wall of the rectangular recession. The attachment means on the hole saw body 14 is adapted to receive the abovementioned engagement means in a rotatable manner. The attachment means comprises of a plurality of engagement lugs 56 , extending longitudinally from the end of the hole saw body 14 , and adapted to be received in the space between the extending hole saw blade lugs 48 .
[0054] To further retain the hole saw blade 12 to the hole saw body 14 , the present embodiment utilises at least one retention clip 60 longitudinally slidable from a first to a second position. This additional retention device safeguards against the blade unintentionally being removed through misuse or rough handling. The retention clip includes a tab 62 which a user asserts force upon to slidably move the retention clip from a first to a second position. In doing so the extension strip 64 is moved up into the recess 52 provided in the hole saw blade 12 . A projection 66 is adapted to be received by a depression 54 and ensures that the clip is retained in the second and locking position.
[0055] FIGS. 4 b and 4 c show the hole saw blade 12 and hole saw body 14 rotatably attached with the retention clip 60 in the first and second positions. The first position of the retention clip 60 allows the hole saw blade portion 12 to be inserted and removed from the hole saw body portion 14 . In the second position the retention clip extends into the hole saw blade portion recess 52 thereby locking the hole saw blade to the hole saw body.
[0056] The retention clip 60 slides along longitudinally extending rails 68 . These rails are formed by pressing the steel about the slot used to house the retention clip 60 in order to create a reduced thickness of the rails when compared with the thickness of the hole saw body 14 . The reduced thickness of the rails allows the retention clip to be the same thickness as the body and as a result it does not protrude radially from the hole saw body 14 . Thus allowing through-drilling applications and does not prevent drilling depth to be limited to only the depth of the hole saw blade portion 12 .
[0057] FIG. 5 illustrates a cross sectional view of the hole saw body portion 14 and the hole saw blade portion 12 locked together with the retention clip 60 in the second and locked position. FIG. 6 illustrates the same arrangement in a top view. Also not shown in this figure is the means of fixing the hole saw body to a mandrel or base.
[0058] FIGS. 7 a and 7 b illustrate a further alternative embodiment of the present invention. The present invention includes further means of retaining the hole saw blade portion to the hole saw body portion. In this embodiment the hole saw blade portion 12 includes at one end at least one cutting element 16 and at the other end an engagement means by which the blade is attached to the hole saw body 14 .
[0059] The engagement means on the hole saw blade 12 further includes at least one engagement lug 70 extending longitudinally from the flat edge 72 of the hole saw blade portion 12 . Shown in this figure is a plurality of repeating rectangular lugs and so as to ensure that the width of each lug is the same, at some point on the circular opening there is one larger than uniform gap 74 between the lugs 70 . This allows the same tooling equipment to be used in the manufacture of all diameters of hole saw blades and ensures that the hole saw body and the hole saw blade can only be aligned for locking in one particular position.
[0060] The hole saw blade portion 12 further includes an annular groove 76 on the inside surface of the extending lugs 70 . The attachment means on the hole saw body 14 is adapted to receive the abovementioned lugs 70 in an insertable manner. The attachment means comprises of a plurality of engagement lugs 78 and gaps 80 between these lugs. The lugs extend longitudinally from the end of the hole saw body 14 and are adapted to be received in the space 72 between the extending hole saw blade lugs 70 . The hole saw body 14 also includes one larger width lug 82 adapted to be received in the larger width gap 74 of the hole saw blade 12 . The hole saw body 14 also further includes an annular groove 84 on the inside surface of the extending lugs 78 .
[0061] To further retain the hole saw blade 12 to the hole saw body 14 , the present embodiment used a C clip 86 inserted into the abovementioned annular grooves 84 and 76 . The grooves are aligned once the hole saw blade 12 is inserted into the hole saw body 14 and the C clip is biased so as to push outwards into the aligned grooves thus retaining the blade to the body. To remove the blade from the body and release the C clip, an object is placed into the aperture provided 88 to dislodge the C clip.
[0062] In FIGS. 8 and 9 it is shown that the clip does not extend radially from the hole saw. This allows through-drilling and places no limitation onto the drilling depth possible with such an arrangement
[0063] FIG. 10 shows the same embodiment as in FIGS. 7 a and 7 b but without the provision for a C clip. In this embodiment the hole saw blade 12 is attached to the hole saw body portion 14 by an interference fit. The side wall 90 of the extending lug of the blade portion 12 is machined on such an angle, taking into consideration compressive properties of steel, that when it is received by the side wall 92 of the hole saw body lug 78 , it is restrained from movement.
[0064] FIGS. 11 a and 11 b illustrate a further alternative embodiment of the present invention. The present invention includes a further means of attaching the hole saw blade portion 12 to the hole saw body portion 14 whilst retaining the same insertion means as shown in FIGS. 7 a and 7 b.
[0065] In this embodiment the hole saw body 14 further includes at least one locking strip 94 projecting longitudinally from the hole saw body 14 . Shown in this figure is three locking strips 94 , spaced equally about the circular opening of the hole saw body 14 . The locking strip 94 is attached at end to the hole saw body 14 with a rivet 96 although alternative methods of attachment may be used, such as a spot weld. At the other end of the locking strip 94 is a protrusion 98 adapted to be received by an aperture 18 on the cylindrical body of the hole saw blade portion 12 . Thereby the hole saw blade 12 is locked to the body 14 as the locking strip is biased from a first to a second position and the protrusion 98 is pressed into the aperture 18 whilst in this first position. To remove the blade, the protrusions are pressed inward thus retracting the locking strip 94 to its second position and allowing the hole saw blade 12 to be removed.
[0066] FIG. 12 shows three different hole saw blade configurations adapted to be attached to a hole saw body 14 using the previous embodiment's method of using a C clip to ensure attachment. Shown is a single tooth hole saw blade 100 with single carbide tipped cutting element 102 . Such an arrangement is typically adapted for cutting composite wood surfaces. Also shown is a serrated steel cutter blade 104 with a plurality of teeth 106 . These teeth may also be tipped with tungsten carbide or an alternative material for increased durability and the ability to cut different surfaces. Also shown is a diamond or carbide grit encrusted blade 108 with diamond encrusted teeth elements 110 for cutting abrasive materials such as glass, ceramics, stone, asbestos and some plastic surfaces. Other configurations of hole saw blades and cutting elements are available for a user to select depending on the application. The present invention allows the user to store a large array of blade types in a compact and more cost effective manner.
[0067] It is important to understand that the present invention teaches a removable hole saw blade that is adapted to be removably attached to a hole saw body. The advantages of this is that the user only needs to have one hole saw body and several blades to be able to cu through a range of materials. Not only is this more space effective and cheaper but it has the result that once a hole saw blade has worn out it can be simply replaced and used with the original hole saw body. This has the effect on saving on materials and thus cost.
[0068] There are several features that although not essential are preferred in connection with this hole saw. Thus it is desirable that the locking mechanism that locks the blade to the hole saw body is contained within the footprint of the body, that is, does not protrude in any direction, enabling the hole saw to be used for deep drilling. Nevertheless at times the locking means may indeed protrude (as will be seen in a minute) provided that the operator is aware of the limitations that this may cause in drilling. FIG. 13 illustrates such a locking mechanism where a pivotable lever 112 pivots from hole saw body 114 . Hole saw blade 116 , that is a wood drilling blade, includes a protruding button 118 that is engaged by cut out 120 in lever 112 .
[0069] However a preferred locking means is illustrated in FIG. 14 . Here a slidable lug whose thickness is the same as the hole saw body 124 includes internally facing grooves 126 that engage a correspondingly shaped protrusion 128 of the hole saw body. The lug is thus restrained in place and can only move up or down to lock and unlock the hole saw blade 130 , the lug sliding within aperture 132 defined both by the hole saw body and the hole saw blade. To ensure that once the lug has slid up and engaged blade 130 it remains in place and does not slide down a press stud 134 may be used that engages correspondingly shaped aperture 136 in the hole saw body and prevents the lug from sliding. To unlock the blade from the body the stud 134 may be depressed and then the lug slid down to unlock the blade from the body. Once the hole saw blade is attached to the body the configuration of the various lugs 129 that have non-parallel surfaces to the longitudinal axis of the hole saw body and blade ensures that the blade is firmly locked to the body and cannot disengage itself. Given that the various lugs are typically not symmetrical nor equally spaced around the blade a marker may be used on both the blade and the body (not shown) to assist in the user correctly positioning the blade on the body.
[0070] Yet other ways of locking the lug in place may be used including an embodiment where a groove may engage protruding pins and so on. It is not intended to limit the invention to a particular way of causing the locking to occur.
[0071] FIGS. 15 through to 18 illustrate in principle the present invention, FIG. 15 illustrating the hole saw body 138 with the locking mechanism 122 of FIG. 14 , FIG. 16 illustrating a metal hole saw blade 140 attached to the body, FIG. 17 illustrating a concrete drilling blade 142 attached to the body 138 and FIG. 18 illustrating a timber drilling blade 144 attached to the body.
[0072] Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.
[0073] In any claims that follow and in the summary of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprising” is used in the sense of “including”, i.e. the features specified may be associated with further features in various embodiments of the invention.
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A hole saw having a central body portion adapted to receive a hole saw blade portion. The body and the blade have correspondingly shaped apertures and lugs that co-operate together to hold the blade in place. A locking means further assists in ensuring that the blade remains locked to the body and includes a sliding klatch that engages an aperture in the blade and the body and is itself locked in place to thereby lock the blade to the body.
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BACKGROUND OF THE INVENTION
1. Field of the Invention.
This invention relates in general to earth boring bits of the type used to drill oil and gas wells.
2. Description of the Prior Art.
Commercially available earth boring bits can be generally divided into the rolling cutter bits, having either steel teeth or tungsten carbide inserts, and diamond bits, which utilize either natural diamonds or artifical or man-made diamonds. The artificial diamonds are "polycrystalline," used either individually or as a component of a composite compact or insert on a cemented tungsten carbide substrate. Recently, a new artificial polycrystalline diamond has been developed which is stable at higher temperatures than the previously known polycrystalline diamond.
The diamond earth boring bits can be generally classified as either steel bodied bits or matrix bits. Steel body bits are machined from a steel block and typically have cutting elements which are press-fit into recesses provided in the bit face. The matrix bit is formed by coating a hollow tubular steel mandrel in a castin mold with metal bonded hard material, such as tungsten carbide. The casting mold is of a configuration which will give a bit of the desired form. The cutting elements are typically either polycrystalline diamond compact cutters brazed within a recess provided in the matrix backing or are thermally stable polycrystalline diamond or natural diamond cutters which are cast within recesses provided in the matrix backing.
The single piece bits, whether steel bodied or matrix, typically include a bit body with a tubular bore which communicates with the interior bore of the drill string for circulation of fluids. At least one fluid opening communicates the bit face with the tubular bore for circulating fluid to the bit face to carry off cuttings during drilling. A plurality of fluid courses, sometimes referred to as "void areas" or "junk slots" allow the flow of drilling fluid and formation cuttings from the bit face up the bore hole annulus.
In the past, these void areas or fluid courses have tended to be of uniform width and depth, particularly in the gage region of the bit body and have tended to become packed off by cuttings in certain formations. As a result, the bit penetration rate dropped.
SUMMARY OF THE INVENTION
A bit is shown for use in drilling earthen formations which includes a body having a bit face on one end and a shank on the opposite end with means for connection to a drill string for rotation about a longitudinal axis. The bit body has a tubular bore which communicates with an interior bore of the drill string for circulation of fluids. The bit face increases in external diameter between a nose and a gage region of the bit. At least one fluid opening communicates the bit face with the tubular bore for circulating fluid to the bit face. A plurality of fluid courses disposed on the bit face extend through the gage region of the bit. The fluid courses become ever wider and ever deeper along their entire disposition.
Additional objects, features and advantages will be apparent in the written description which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a bit of the invention showing the ever widening and deepening fluid courses on the bit body.
FIG. 2 is a simplified, schematic view of the bit of FIG. 1 showing the ever deepening nature of the fluid course.
FIG. 3 is a simplified, schematic view of the bit of FIG. 1 showing the ever widening nature of the fluid course.
FIG. 4 is a partial, sectional view taken along lines B--B' in FIG. 3.
FIG. 5 is a partial, sectional view taken along lines A--A' in FIG. 3.
DETAILED DESCRIPTION OF THE INVENTION
The numeral 11 in the drawing designates an earth boring bit having a body 13 with a threaded shank 15 formed on one end for connection with a drill string member (not shown). The body 13 further includes a pair of wrench flats 17 used to apply the appropriate torque to properly "make-up" the threaded shank 15. The body 13 has a tubular bore 19 which communicates with the interior of the drill string member, and which communicates by internal fluid passageways (not shown) with one or more fluid openings 21 which are used to circulate fluids to the bit face.
On the opposite end of the bit body 13 from the threaded shank 15, there is formed a bit head or "matrix" 19 in a predetermined configuration to include cutting elements 23, longitudinally extending lands 25, and fluid courses or void areas 27. The matrix 19 is of a composition of the same type used in conventional diamond matrix bits, one example being that which is disclosed in U.S. Pat. No. 3,175,629 to David S. Rowley, issued Mar. 30, 1965. Such matrices can be, for example, formed of copper-nickel alloy containing powdered tungsten carbide.
Matrix head bits of the type under consideration are manufactured by casting the matrix material in a mold about a steel mandrel. The mold is first fabricated from graphite stock by turning on a lathe and machining a negative of the desired bit profile. Cutter pockets are then milled in the interior of the mold to the proper contours and dressed to define the position and angle of the cutters. The fluid channels 27 and internal fluid passageways are formed by positioning a temporary displacement material within the interior of the mold which will later be removed.
A steel mandrel is then inserted into the interior of the mold and the tungsten carbide powders, binders and flux are added to the mold. The steel mandrel acts as a ductile core to which the matrix material adheres during the casting and cooling state. After firing the bit in a furnace, the mold is removed and the cutters are mounted on the exterior bit face within recesses in or receiving pockets of the matrix.
The bit body 13 in FIG. 1 has a ballistic or "bullet-shaped" profile which increases in external diameter between a nose 29 and a gage region 31 of the bit. Referring to FIG. 2, the face region extends generally along the region "X," the gage region extends generally along the region "Y" and the shank extends generally along the region "Z." The bit is generally conical in cross-section and converges from the gage region "Y" to the noze 29. By "gage" is meant the point at which the bit begins to cut the full diameter. That is, for an 81/2 inch diameter bit, this would be the location on the bit face at which the bit would cut an 81/2 inch diameter hole.
As shown inFIG. 1, each fluid course 27 comprises a groove of lesser relative external diameter located between two lands (25, 33 in FIG. 1) on the bit face. The lands 25, 33 have polycrystalline diamond cutter elements 23 mounted therein within backings of the matrix for drilling the earthen formations. The backings 35 for the cutting elements 23 are portions of the matrix which protrude outwardly from the face of the bit and which are formed with cutter receiving pockets or recesses during the casting operation.
The cutting elements 23 are of a hard material, preferably polycrystalline diamond composite compacts. Such cutting elements are formed by sintering a polycrystalline diamond layer to a tungsten carbide substrate and are commercially available to the drilling industry from General Electric Company under the "STRATAPAX" trademark. The compact is mounted in the recess provided in the matrix by brazing the compact within the recess. The preferred cutting elements 23 are generally cylindrical.
As shown in FIG. 1, each land 25, 33 is formed as a convex ridge of the matrix material which extends from the nose 29 outwardly in an arcuate path, the path gradually transitioning to extend generally longitudinally along the bit axis 37 to terminate in a planar pad 39 at the gage region 31 of the bit. The planar pads 39 have small diamonds (polycrystalline and/or natural) imbedded in the surface thereof and have longitudinal troughs which extend generally parallel to the longitudinal axis 37 of the bit.
The fluid courses 27 become ever wider and deeper through the gage region "y" of the bit where prior art bits were of constant width and depth. In the preferred embodiment shown in FIG. 1, the fluid courses 27 become ever wider and deeper along the face of the bit from the nose 29 through the gage region 31 to the shank region "Z" (FIG. 2). As illustrated in FIGS. 4-5, D 2 -D 1 is always greater than 0, and W 2 -W 1 is always greater than 0. Thus a normal plane drawn through any selected fluid course 27 at one incremental location (such as that illustrated in FIG. 5) along the bit face increases in cross-sectional area in the direction of the gage region 31 (as indicated in FIG. 4). The cross-sectional area of the normal plane decreases in increments in the direction of the nose 29.
The constantly deepening feature of the void area is illustrated in FIG. 2. Imaginary line 43 drawn parallel to the bit axis 37 represents the constant depth of a prior art bit in the gage region "Y". Imaginary line 45 is an extension of the actual depth of the fluid course 27 in the bit of the invention. The angle alpha formed between lines 43 and 45 is preferably in the range from about 1/4 degree to about 7 degrees and most preferably is in the range from about 1 degree to 2.5 degrees.
The constantly widening feature of the void area is illustrated in FIG. 3. Imaginary line 47 in FIG. 3 is parallel to a plane drawn through the bit axis 37 and corresponds to an edge of a constant width void area of a prior art bit in the gage region "Y." Imaginary line 49 is an extension of the fluid course 27 in the bit of the invention. The angle beta is in the range from about 1/4 degree to 10 degrees, preferably in the range from about 2 degrees to 4 degrees, most preferably about 3 degrees on either side of the fluid course. That is, angle tau in FIG. 3 is equal to angle beta.
An invention has been provided with several advantages. The drilling bit of the invention features fluid courses which are ever widening and ever deepening from their lowermost and/or centermost disposition through the gage region of the bit. Because the void area is fully expanding, there is no choke point present which would tend to form a constriction for entrained cuttings in the drilling fluid. Any tendency of the fluid course to pack-off is eliminated because any differential movement of the obstruction moves the obstruction to a larger cross-sectional flow area to allow release. It is no longer necessary for the operator to run a special additive in the drilling fluid to strip off a packed formation or to back the drill string off the bottom of the hole in an attempt to blow the obstruction away with drilling fluid. In addition, the improved removal of cuttings allowed by a bit embodying the invention results in faster penetration rates and more economical drilling.
While the invention has been shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit thereof.
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A bit is shown for use in drilling earthen formations which includes a body having a bit face on one end and a shank on the opposite end which is connected in the drill string. The bit body has a tubular bore which communicates with an interior bore of the drill string for circulation of fluids. The bit face increases in external diameter between a nose and a gage region of the bit. A fluid opening communicates the bit face with the tubular bore for circulating fluid to the bit face. A plurality of fluid courses are disposed on the bit body, the fluid courses becoming ever wider and ever deeper along their entire disposition from their lowermost incorporation through the gage region thereof.
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BACKGROUND OF THE INVENTION
1. Field of Invention
The instant invention relates generally to motors and more specifically it relates to the improvement in the method of assembling and presenting the brushes to a motor prior to the insertion of the armature within the brush assembly housing.
2. Description of the Prior Art
The present method by which the task of assembling motors that require brushes, undertaken by those who are in the field is as follows. The common practice is that a skilled operator uses some kind of pliers that will press the brushes within the brush housing as the operator forces the armative in between the brushes with hope that there is no damage done to either part. The process is very slow and any equipment heretofore produced has been very expensive.
SUMMARY OF THE INVENTION
A principle object of the present invention is to provide a brush assembly tool that will overcome the disadvantages of the prior art.
Another object is to provide a brush assembly tool that is fast and effective for presenting the spring loaded brushes within the brush housing so that the armature can be placed within.
An additional object is to provide a brush assembly tool that has no moving parts and requires no additional special tools.
A further object is to provide a brush assembly tool that is simple and easy to use.
A still further object is to provide a brush assembly tool that is economical in cost to manufacture.
Further objects of the invention will appear as the description proceeds.
To the accomplishment of the above and related objects, this invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific construction illustrated and described within the scope of the appended claims.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
FIG. 1 is a perspective view of the brush assembly tool with the spider brush retainer exploded above.
FIG. 2 is a top plan view of the brush assembly housing on the reduced top portion of the post body of the brush assembly tool with all the brushes pushed in and held.
FIG. 2A is an enlarged perspective view of a portion of the brush assembly housing with parts broken away of a typical brush, brush holder and brush spring thereon.
FIG. 3 is an elevational view of the brush assembly tool with parts broken away, such that the brush assembly housing is on the reduced top portion with all the brushes pushed in and held and the spider brush retainer in position on top.
FIG. 4 is a perspective view of a modified brush retainer having a continuous flange.
FIGS. 5 through 10 are diagrammatic top plan views of the brush assembly housing taken through various steps so that the armature of the motor can fit in between the brushes.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Turning now descriptively to the drawings, in which similar reference characters denote similar elements throughout the several views, FIGS. 1 through 3 illustrates a brush assembly tool 11 for a brush assembly housing 34 having a central aperture 36 surrounded by four brush holders 30, four brushes 28 and four brush springs 32.
The brush assembly tool 11 consists of a platform 12 with a vertical cylindrical post 14 attached thereto. The vertical post 14 has three different diameter portions 16, 17 and 18.
The lower portion 16 has the largest diameter and acts as a stop for the brush assembly housing 34 when it is placed onto the post 14. The middle portion 17 has a diameter "E" that is equal to the diameter of an armature 38 (see FIG. 10) that is to be assembled to the brush assembly housing 34.
The upper portion 18 has a slot 20 that is machined cut into its end at a depth "B" equal to the depth of the brushes 28. The width "A" of the slot 20 is equal to or greater than the width of the brushes 28. The diameter "D" of the upper portion 18 is equal to the inside diameter of a spider brush retainer 24 that has four fingers 26. There is an angular lip 22 between the upper portion 18 and the middle portion 17 indicated by "C".
FIG. 4 shows a modified brush retainer 24a that can be substituted for the spider brush retainer 24. The brush retainer 24a has a continuous flange 26a instead of the four fingers 26 and will function in the same way as the spider brush retainer 24.
FIGS. 5 through 10 illustrates the various steps that must be taken to use the brush assembly tool 11.
FIG. 5 shows step number 1. The four brushes 28 are in the aperture 36 in an unassembled position.
FIG. 6 shows step number 2. Two opposite brushes 28 not in alignment with the slot 20 are manually pushed in and held when the aperture 36 of the brush assembly housing is placed onto the top portion 18 and partly pushed down.
FIG. 7 shows step number 3. The other opposite brushes 28 in alignment with the slot 20 are manually pushed in and held when the brush assembly housing 34 is pushed all the way down to the lower portion 16.
FIG. 8 shows step number 4. The spider brush retainer 24 is placed upon the top portion 18 so that the fingers 26 are in proper position with all the brushes 28.
FIG. 9 shows step number 5. With the spider brush retainer 24 manually held down the brush assembly housing 34 is removed from the brush assembly tool 11. The four finger 26 of the spider brush retainer 24 holds the four brushes 28 in position.
FIG. 10 shows step number 6. The armature 38 is pushed through the central aperture 36 and removes and replaces the spider brush retainer 24 to hold the four brushes 28 in position. The spider brush retainer 24 is displaced by the armature 38 and can be used again.
While certain novel features of this invention have been shown and described and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing from the spirit of the invention.
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A brush assembly tool is provided and includes a cylindrical post and a brush retainer that will effectively preset four spring loaded brushes within a brush assembly housing so that a motor armature can be placed within the brush assembly housing.
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DESCRIPTION
[0001] The invention relates to a device for shape-forming the end region of a workpiece, especially for cold-press shape-forming of a pipe end region. It is known to set in compression a workpiece by means of a first hydro-dynamically actuable force transmission element and to shape-form the end region via direct or indirect application of force thereagainst by a second hydrodynamically actuable force transmission element. The concept of hydro-dynamically actuable force transmission elements comprehends a body which is actuable in a hydraulic and/or pneumatic manner. In connection with the highest force which is required for the shape-forming of a workpiece, a hydraulic actuation is chosen specifically for this purpose.
[0002] DE 195 11 447 A1 discloses a device adapted for shape-forming a pipe end region. This device includes a recess for exchangeable jaws operable to set the pipe in compression. By means of a first hydraulically actuable piston, the jaws are driven under pressure in order to compressively engage the pipe. The first piston comprises a central through opening in which a piston rod of a second hydraulically actuable piston is guidably disposed. The two pistons are in this manner coaxially movable within one and the same housing serially one behind the other.
[0003] The piston rod of the second piston, which is provided with a shape-forming tool, can effect application of a force on the pipe end region, in view of the fact that the piston rod extends through the central, end-to-end continuously open, opening in the first piston, whereby the pipe end region is shape-formed in the axial direction. In this manner, the end region deforms in correspondence with the geometry of the shape-forming tool and the jaws.
[0004] In a special configuration, the known device comprises a three-part housing. A first housing portion has a first bore in which the first, annularly shaped, piston is movably guided with its sleeve and has a second bore in which the second piston with its piston rod is movably guided. The second bore has a relatively smaller diameter than the first bore. In this manner, a stop or shoulder for engaging the sleeve of the first, annularly shaped, piston is formed which defines the maximum return position of the first piston. A hydraulic fluid can be introduced for actuating the first piston between the stop or shoulder and the piston sleeve. A further portion of the three-piece housing forms with the first housing portion a threadable housing end piece which comprises a cylindrical bore for guiding the end piece of the second piston. The first housing portion forms a stop or shoulder in the actuation direction of the second piston. A hydraulic medium can be introduced between the stop or shoulder and the second piston in order to effect a return movement of the second piston after the shape-forming of the pipe. The corresponding hydraulic space for receipt of the hydraulic fluid is sealed off relative to the first hydraulic space between the sleeve of the first piston and its rearward stop or shoulder. The third portion of the three-piece housing forms the receiving portion for the jaws and the forward portion of the first and the second pistons or, respectively, the shape-forming tool. The shape-forming tool is configured and connected with the forward end region of the piston rod of the second piston such that, during return movement of the second piston, the first piston is correspondingly brought along and the jaws are thus released from their compression position. In this connection, the central through opening of the first piston comprises a rearward stop or shoulder. The shape-forming process performed by the known device disclosed in DE 195 11 447 A1 is, to this extent, burdened with disadvantages in that a control of the course of the shape-forming process from the beginning to the end thereof as well as a monitoring of the tool and the pipe to be shape-formed before the beginning of the shape-forming process is neither provided for nor possible due to the coupling of the two pistons during their return movements.
[0005] The invention provides a solution to the challenge of making available a device for shape-forming a workpiece end region which makes possible a better control of the shape-forming process.
[0006] The solution to this challenge is revealed in the advantageous embodiments and further configurations of the invention as set forth in the patent claims which follow this description.
[0007] In this connection, the invention initially provides, in a first embodiment, that, between the first force transmission element and the second force transmission element, a first pressure space is arranged communicated with a first pressure connector and that the second force transmission element has a second pressure space, communicated with a pressure connector, arranged relative thereto such that the introduction of a pressure medium into the second pressure space drives the second force transmission element in the compression and shape-forming direction. During the forward displacement of the second force transmission element to set the workpiece in compression, the pressure exerted by the pressure medium in the first pressure space is maintained via blockage of the first pressure connector, whereby, upon reaching a predetermined overpressure, the pressure medium is released from the first pressure space, so that the second force transmission element moves relative to the first force transmission element, which remains in its workpiece compressive engagement position, to thereby effect shape-forming of the workpiece and, after the shape-forming of the end region of the workpiece, the second force transmission element is moved rearwardly to its start position by a renewed introduction of a pressure medium in the first pressure space and, by means of a special drive, the first force transmission element is moved correspondingly therewith back into its start position.
[0008] In this connection, the advantage is provided that, by reason of the pressure controlled release of the pressure medium in the first pressure space following the reaching of the overpressure during the forward displacement of the second force transmission element, the workpiece compressive engagement pressure is uniformly maintained at the required value. The required pressure need only be maintained so long as is necessary. In this manner, an unnecessarily high pressure, and an unnecessarily long time period for the maintained pressure and the therewith connected unnecessary loss of performance and high temperature development, are avoided in an advantageous manner. After completion of the shape-forming process, the second force transmission element is movable in an active manner back into its start position.
[0009] In accordance with one embodiment of the invention, it is provided that a third pressure space with a connection to a third pressure connector is provided as a drive for the return movement of the first force transmission element. Alternatively, the drive for the return movement of the first force transmission element can, however, be additionally configured as a return spring.
[0010] In accordance with an embodiment of the invention, it is provided that the start position of the first force transmission element is defined between the housing and a first force transmission element stop or shoulder. By fixedly positioning the first force transmission element in its start position as well as, also, by selection of the start position of the second force transmission element, the relative displacement movement path between the second and the first force transmission elements required for the shape-forming process is constructively laid out.
[0011] In accordance with embodiments of the invention, sensors are provided which recognize the inserted workpiece as well as monitor the respective position of the first force transmission element to determine whether the first force transmission element has again been returned into its start position. In this connection, it is provided, in a case-by-case manner, that before the start of the shape-forming process, it can be automatically determined whether a suitable compression and/or shape-forming tool is available and/or is properly positioned, whereby the availability and/or the proper position of the shape-forming tool can be determined by a non-contact distance measurement effected by a sensor. Additionally, it can be provided that, via a sensor, the start position of the shape-forming tool and the position thereof during the shape-forming process can be sensed.
[0012] In a further development of the inventive device, it can be provided that the required relative movement path for the shape-forming process between the first force transmission element and the second force transmission element—that is, the so-called shape-form length L—is adjustably settable in a first process step, such that the first force transmission element is movable away from the second force transmission element by introduction of a pressure medium into the first pressure space, whereby, via introduction of a pressure medium in the second pressure space, the compression process and the shape-forming process follow thereafter as described. A pressure medium is, accordingly, introduced into the first pressure space both for actuation of the first force transmission element as well as for releasing the second force transmission element, whereby there is obtained the advantage of a still further improved control possibility for the shape-forming process.
[0013] In this connection, it can be provided that the length of the first pressure space between the first actuation surface and the second actuation surface is adjustably set before the shape-forming of the workpiece in order to set the desired defined work path. Following therefrom, the two force transmission elements can be moved while maintaining a constant relative position to one another until the workpiece has been set in compression. As a further consequence thereof, the second force transmission element is movable precisely along the predetermined length of the pressure space against the first force transmission element, so that the compressively engaged workpiece is shape-formed by a movement along this length. The shape-forming process is brought to an end in particular due to the engagement of the first actuation surface and the second actuation surface of the first pressure space with one another.
[0014] In a further configuration of the device, the length of the pressure space is directly or indirectly measurable in order to adjustably set the length. In particular, the length is indirectly measurable via a distance sensor which is oriented toward a surface whose distance from the distance sensor varies as a function of the length of the pressure space. A surface of this type is, for example, configured as an outwardly expanding conical outer surface of the first force transmission element. It is advantageous if a non-contact measuring distance sensor is deployed.
[0015] A non-contact measuring sensor is provided which emits a signal in dependence upon whether the workpiece to be shape-formed is in a start position in which it can be compressively engaged and/or shape-formed. The sensor is, in particular, a distance sensor which measures the distance in a measurement direction to the most closely adjacent object. Such sensors, including, for example, a laser emitting sensor, are known.
[0016] In this event, the workpiece need only be disposed in the start position in order to produce the signal. In particular for controlling the compression process and/or the shape-forming process, a control is provided which is connected via a signal connection with the sensor. By means of the transmission of a signal to the control, especially, an automatic signal, the compression process and/or shape-forming process is initiated.
[0017] In particular, non-contact measurement of a dimension of the workpiece to be shape-formed or, respectively, a measurement value, is performed which provides a clear measurement of the dimension of the workpiece to be shape-formed. If, for example, a pipe is to be shape-formed, the possibility is available to measure the pipe diameter. This permits, before the start of the compression process and/or the shape-forming process, a monitoring of whether a workpiece with the desired dimensions for shape-forming is standing ready. If the proper workpiece has not been brought into a start position or there is, in any event, no workpiece at all in the start position, a start signal is correspondingly also not produced. An unintended actuation of the shape-forming device or, respectively, the working of the workpiece with false dimensions can thus be avoided in this manner. An important advantage lies in the fact that security measures for protecting the operating personnel can be maintained in a simple manner and, at the same time, damage of the device such as through the disposition of too large a workpiece therein, can be prevented.
[0018] Furthermore, it is suggested that, before the start of the compression process and/or the shape-forming process, that it be automatically determined whether a suitable compression and/or shape-forming tool is available and/or is properly positioned. In this connection, it is particularly suggested to provide a non-contact measuring sensor which generates a signal as a function of whether a suitable compression and/or shape-forming tool is available and/or is properly positioned. A shape-forming tool recognition in this manner can be combined with the above-described sensor to produce a start signal in order to achieve still greater assurance against false actuation and false functioning. In particular, the same sensor can be used for measuring the start position and for measuring the availability and/or the positioning of the shape-forming tool. In this event, the availability and/or the proper positioning of the shape-forming tool is, preferably, initially measured or, respectively, pre-set.
[0019] Moreover, it is further suggested to provide a sensor which measures in a non-contact manner the progression or continuing movement of the shape-forming of the workpiece. In particular, a control can be further provided which receives a signal of the sensor, and which, after the shape-forming has been adequately performed, effects the end of the shape-forming process.
[0020] The inventive device is described hereinafter in connection with two embodiments thereof; in this regard, the drawings show:
[0021] [0021]FIG. 1 A longitudinal view through a shape-forming device in its start position,
[0022] [0022]FIG. 2 the shape-forming device shown in FIG. 1 having a workpiece received therein in the start position,
[0023] [0023]FIG. 3 the shape-forming device after the completion of the workpiece compressive engagement process,
[0024] [0024]FIG. 4 the shape-forming device in its position at the end of the shape-forming process,
[0025] [0025]FIG. 5 the shape-forming device in the intermediate position during return movement at a time at which the second force transmitting element has already been returned to its start position,
[0026] [0026]FIG. 6 the shape-forming device in another embodiment thereof comprising a function for variable adjustment of the shape-form length (L), the shape-forming device being shown in the start position,
[0027] [0027]FIG. 7 the subject matter shown in FIG. 6 with an inserted pipe end,
[0028] [0028]FIG. 8 the shape-forming device as shown in FIG. 6 following setting of the shape-form length (L),
[0029] [0029]FIG. 9 the shape-forming device as shown in FIG. 8 upon reaching the workpiece compressive engagement position of the first force transmitting element,
[0030] [0030]FIG. 10 the shape-forming device as shown in FIG. 9 following completion of the shape-forming process.
[0031] [0031]FIG. 1 shows a longitudinal view through a shape-forming device 1 . The shape-forming device 1 includes a base housing 3 having a central cylindrical bore such that a cylinder surface 4 is formed thereby. In the region of the open end of the base housing 3 , a receiving housing 5 is disposed for receipt of jaws 31 operable as compression jaws. The cylinder surface 4 is configured as a guide surface for guiding the movement of a first force transmission element configured as an outer ring piston 7 and for guiding the movement of a second force transmission element configured as an inner piston 9 . The inner piston 9 substantially completely fills the closed end of the cylindrical bore. A piston rod 11 of the inner piston 9 extends in the direction toward the open end of the cylinder bore. The piston rod 11 is received in a central cylindrical bore of the outer piston 7 and is fixedly coupled with an extension piece 11 ( a ) which is, in turn, connected to a compression tool 13 . The outer piston 7 thus forms a guide for guiding the movement of both the piston rod 11 and a rotation preventing device 15 which connects the piston rod 11 or its extension piece 11 ( a ) with a compression tool 13 operable as a shape-forming tool.
[0032] The rotation preventing device 15 is operable in a manner similar to a bayonet lock. A locking projection 16 of the compression tool 13 is disposed, via a linear movement in the axial direction of the extension piece 11 ( a ) of the piston rod 11 , into a corresponding recess in the extension piece 11 ( a ) and is thereafter pivoted about the longitudinal axis of the piston rod 11 in order to lock the connection.
[0033] The base housing 3 comprises a first pressure connection 25 through which a hydraulic medium can be introduced into the interior of the base housing 3 or, respectively, can be discharged from the base housing 3 . A first pressure space 26 in the base housing 3 is communicated with the first pressure connector 25 , the pressure space being disposed outside of the cylinder surface 4 and being limited, as well, by a first actuation surface 10 of the outer piston 7 and by a second actuation surface 12 of the inner piston 9 . The first pressure space 26 is configured as a relatively larger or smaller space as a function of the operational condition of the shape-forming device 1 and can be disposed in various positions relative to the first pressure connector 25 (see FIGS. 1 - 5 ). In each operational condition, however, the first pressure connector 25 is communicated with the first pressure space 26 .
[0034] In particular, the first pressure space 26 expands outwardly in the radial direction, as the first actuation surface 10 and the second actuation surface 12 are each partially configured as conical surfaces.
[0035] As can be seen in FIGS. 3 and 4, the first actuation surface 10 and the second actuation surface 12 each respectively comprise a further region which is annularly shaped and represents a stop or shoulder for the other piston 7 , 9 .
[0036] The first pressure space 26 is sealed off against the open end and the closed end of the cylinder bore of the base housing 3 by seals between the piston rod 11 and the inner surface of the outer piston 7 , by seals between the outer surface of the outer piston 7 and the cylinder surface 4 , and as well by seals between the outer surface of the inner piston 9 and the cylinder surface 4 . The seals are collectively designated with the reference numeral 21 .
[0037] In the region of the closed end of the cylinder bore, there is additionally provided a second pressure space 28 in the base housing 3 which is communicated with a second pressure connector 27 . The second pressure space 28 has a variable volume which can be varied to a value of practically zero.
[0038] On the side of the outer piston 7 turned away from the first pressure space 26 , a third pressure space 51 is formed in the compression and shape-forming device in front of the outer piston 7 between this piston and a housing insert 52 , the third pressure space being communicated with a third pressure connector 50 . This third pressure space 51 serves as a drive for the return movement of the outer piston 7 into its start position.
[0039] The receiving housing 5 forms a receiving space for the jaws 31 which are operable through actuation of the pistons 7 , 9 —that is, through the movement of the pistons in the axial direction—to place a workpiece under compression. The jaws 31 are, for example, configured and actuated in the same manner as the jaws shown in DE 195 11 447 A1.
[0040] The jaws 31 include, on the right hand back end thereof as viewed in FIGS. 1 - 5 , a shape-forming recess 33 which forms an encircling groove-type recess closing upon itself if a workpiece with a corresponding outer dimension is disposed under compression in the shape-forming device. The shape-forming recess 33 serves to shape-form the workpiece as will be described hereinafter in more detail. Alternatively or additionally, the shape-forming can also be effected by selection of the geometry of an alternative compression tool which is provided in lieu of the illustrated compression tool 13 and which is connectable with the piston rod 11 .
[0041] The compression tool 13 comprises, on its free back end at which the compression tool has a smaller outer diameter than the area thereof axially behind this free back end, a measurement band 8 .
[0042] The inner piston 9 comprises, in the region of the free end of its piston rod 11 or its respective extension piece 11 ( a ) which extends toward the jaws 31 , a conically shaped section 6 which forms the outer periphery of the extension piece 11 ( a ).
[0043] Two bores are formed in the complete housing formed by the base housing 3 and the receiving housing 5 , the two bores extending in a radial direction to the central longitudinal axis of the shape-forming device 1 . A sensor S 1 or, respectively, S 2 , is arranged in each respective bore. The sensor S 1 serves to identify the compression tool 13 in that the sensor S 1 is oriented toward the measurement band 8 of the compression tool 13 and can identify the respective compression tool 13 as a function of the distance between the sensor S 1 and the measurement band 8 .
[0044] The sensor S 2 serves to establish the base position of the inner piston 9 in that the sensor S 2 is oriented toward the conical surface 6 of the extension piece 11 ( a ) that is connected with the inner piston 9 , so that, via the determination of the position of the conical surface 6 or, respectively, the movement of the extension piece 11 ( a ) with the cylindrical peripheral surface relative to the sensor S 2 , the continuation of the movement of the inner piston 9 is sensed.
[0045] An example of the operation of the shape-forming device 1 is hereinafter described:
[0046] Starting from the position of the shape-forming device as shown in FIG. 1, initially, a workpiece such as, in particular, the end of a pipe 2 , is introduced into the shape-forming device until the inward end of the pipe is seated against the compression tool 13 , whereby the start position of the shape-forming device can be seen in FIG. 2. As can be seen in FIG. 3, the pressure space 28 is filled with a pressurized medium which leads to a displacement of the inner piston 9 to the left hand direction as seen in FIG. 3. Since the pressure connector 25 of the first pressure space 26 is closed during this first phase of the pressure filling of the second pressure space 28 , the feeding force of the inner piston 9 is transmitted via the pressure medium present in the first pressure space 26 to the outer piston 7 so that this piston is displaced in the same direction in coordination with the displacement of the inner piston 9 ; with continuing movement of the two pistons 7 , 9 , the jaws 31 are pushed into position on the outer surface of the pipe 2 and place the pipe in compression, whereby the outer piston 7 pushes outwardly in a discharging manner the pressure medium present in the third pressure space 51 . Once the pipe 2 is placed in compression, the outer piston 7 can no longer be further moved and, in this manner, the pressure rises in the pressure medium in the first pressure space 26 until an overpressure corresponding to the desired compression force is reached. Upon reaching the overpressure, the pressure connector 25 is opened so that the pressure medium in the first pressure space 26 can flow out of the pressure space. In this manner, a continuation of the feed movement of the inner piston 9 is made possible, with the piston now being further displaced relative to the fixedly positioned outer piston 7 and thereby performing a compression working until the space between the annular surfaces of the inner pistons 9 and the outer piston 7 , which has been laid out as a function of the compression work to be exerted, has been exhausted.
[0047] Upon the completion of the compression working, the pressure connector 27 of the second pressure space 25 is moved into a release position and a pressure medium is introduced via the first pressure connector 25 into the first pressure space 26 ; in this manner, the inner piston 9 is moved in the right hand direction into its start position, as can been seen in FIG. 5. Thereafter, a pressure medium is introduced via the third pressure connector 50 into the third pressure space 51 and, thereby, the outer piston 7 is likewise moved in the right hand direction into its start position as can be seen in FIG. 1, or respectively, in FIG. 2. The end position of the outer piston 7 is thereby determined or given by a stop member (not shown) between the outer piston 7 and the housing.
[0048] With respect to the embodiment of the shape-forming device shown in FIGS. 6 - 10 , there is performed, in addition to the functions performed by the embodiment described in accordance with FIGS. 1 - 5 , an additional function by which the shape-form length L required for the working of the workpiece is variably adjustable in a first functional step. Otherwise, the same components are designated with the same reference numerals.
[0049] Thus, a receiving space 18 extends outwardly from the rotation preventing device 15 in the axial direction of the piston rod 11 toward the interior thereof, a compression spring 17 being received in the receiving space. The compression spring presses the compression tool 13 into a position in which a gap is created between the compression tool 13 and a surface 14 formed on the back end of the piston rod 11 . Correspondingly, a gap is also formed in the region of the rotation preventing device 15 between the compression tool 13 and the piston rod 11 which permits movement of the compression tool 13 against the piston rod 11 by the width of the gap.
[0050] In addition to the seals 21 disposed between the respective moveable components, guide rings 19 are provided for guiding the movement of the pistons 7 , 9 .
[0051] Moreover, a sensor arrangement is variably configured in the embodiment shown in FIGS. 6 - 10 . In this connection, the jaws 31 include a measurement groove 35 which extends radially inwardly from the outer surface of the jaws 31 . In lieu of the measurement groove 35 , a measurement indentation can be provided which, unlike the groove shown in FIGS. 6 - 9 , does not extend in the circumferential direction around the jaws 31 but is, however, only a single indentation formed in one location or at several locations on the jaws. In this event, the proper positioning must be observed relative to a distance sensor, whose function is described in more detail hereinafter.
[0052] The jaws 31 further include a measurement opening 29 extending in the radial direction which permits an electromagnet emission such as, in particular, a laser emission, to be directed from outside the jaws 31 interiorly onto a workpiece which is held in compression by the shape-forming device. The measurement opening 29 terminates on the inside of the shape-forming recess 33 so that, as will be described in more detail hereinafter, the progress of the shape-forming process can be measured.
[0053] In a variation of the embodiment shown in FIGS. 1 - 5 , the conical surface 6 is configured on the free end of the outer piston 7 turned toward the jaws 31 , whereby the conical surface 6 defines the outer periphery of the outer piston 7 .
[0054] In addition to the bores previously described with respect to the embodiment in FIGS. 1 - 5 for receipt of the sensors, both bores in the embodiment shown in FIGS. 6 - 10 each comprise a distance sensor 37 , 39 . The distance sensors 37 , 39 measure the distance to the most closely adjacent object lying in the radial direction inwardly or, respectively, the distance to the oversurface associated therewith. As schematically shown in FIG. 6, the first distance sensor is connected via a first signal lead 43 with a control 41 . Furthermore, the second distance sensor 39 is connected via a second signal lead 45 with the control 41 . The control 41 is, in turn, connected with a display device 47 which comprises six light emitting diodes 49 . The light emitting diodes 49 serve to display the operational phases and the measured operational conditions of the shape-forming device 1 .
[0055] By use of the device shown in FIGS. 6 - 10 , the device measures the first distance via the first distance sensor 37 to the measurement band 8 of the compression tool 13 . The outer diameter at the measurement band 8 is a characteristic measure of the type of compression tool that the compression tool 13 is, especially with respect to its other measurements. Each compression tool connectable with the piston rod 11 or any other tool has, in any event, a measurement band which, however, has a different outer diameter. In accordance with the distance to the measurement band 8 and, correspondingly, the outer diameter of the compression tool 13 , the first distance sensor generates a measurement signal which is transmitted to the control 41 . The control 41 which is, in particular, configured as an intelligent microprocessor-configured control, recognizes the presence of the tool via the measurement signal.
[0056] The second distance sensor 39 measures the distance to the bottom of the measurement groove 35 in the jaws 31 . The distance to the groove bottom is a representative measure of the type of jaws which the jaws 31 are. The second distance sensor 39 generates a corresponding measurement signal via the second signal lead 45 to the control 41 . The control 41 recognizes the jaws 31 .
[0057] The jaws 31 and the compression tool 13 serve to shape-form a certain type of pipe—namely, the shape-forming of pipes with a predetermined outer diameter. From the information concerning which compression tool and which jaws are available, the control 41 determines what type of pipes can be shape-formed in combination with the workpieces.
[0058] As shown in FIG. 7, if a pipe is received in a receiving opening 20 of the compression tool 13 and, as shown by the arrow pointing to the right, is impacted by a force, the shape-forming of the pipe 2 commences. If the force is sufficiently large in order to move the compression tool 13 so as to overcome the counter force of the spring 17 against the rod rear surface 14 , then the compression tool 13 is positioned at a spacing from the jaws 31 . As a result of this, the first distance sensor 37 can now measure the distance or spacing to the outer surface of the pipe 2 . The first distance sensor 37 transmits via the first signal lead 43 a corresponding measurement signal to the control 41 . The control 41 monitors whether the pipe 2 has the proper outer diameter or, respectively, whether the proper measurement signal was received. If this is the case, the control 41 starts the compression-and shape-forming process.
[0059] In this connection, as can be seen in FIG. 8, the outer piston 7 is initially moved along the shape-form length L in the axial direction (in the illustration in FIG. 8, towards the left). In order to ensure that the movement is accomplished, a hydraulic medium is introduced through the first pressure connector 25 into the first pressure space 26 . During this procedure, the first distance sensor 37 measures the distance to the conical surface 6 of the outer piston 7 and continuously transmits a measurement signal to the control 41 . Once the distance between the annularly-shaped surfaces of the first actuation surface 10 and the second actuation surface 12 is the same as the shape-form length L, and the first distance sensor 37 has transmitted a corresponding measurement signal to the control 41 , the control 41 interrupts the introduction of the hydraulic medium into the first pressure space 26 so that the movement of the outer piston 7 is stopped.
[0060] Thereafter, as best seen in FIGS. 9 and 10, the actual compression and shape-forming of the pipe 2 begins, as has been basically described with respect to the embodiment shown in FIGS. 1 - 5 , whereby the control 41 commences the introduction of a hydraulic medium through the second pressure connector 27 into the second pressure space 28 . Following this operational condition, which is shown in FIG. 9, the compression-and shape-forming work is completed as has already been described with respect to the embodiment shown in FIGS. 1 - 5 .
[0061] Insofar as the compression work of the jaws 31 is effected in a rapid manner, the continuing movement of the inner piston 9 in the axial direction towards the left ensures that no slippage of the pipe 2 through the jaws 31 occurs, once the inner piston 9 has reached its maximal extended position. If, for example, because of relatively low surface roughness of the pipe outer surface and/or the jaws 31 , a slippage of this type should occur, an adjustment of the distance between the actuation surfaces 10 , 12 (see the operational phase shown in FIG. 8) can be implemented. In this event, the shape-form length L does not, in fact, exactly correspond to the actual path, in which the end of the pipe 2 is shape-formed in the axial direction. A precise pre-adjustment of the desired shape-form path is, however, possible. A further factor, which can lead to inequality between the shape-form length L and the actual shape-form path, is the yieldability or, respectively, the elasticity, of the material connection between the outer piston 7 and the jaws 31 . In particular, elastic material can be deployed such as, for example, a material to effect a damping of noise or to prevent a wearing away.
[0062] As the end region of the pipe 2 is shape-formed via the application of force by the shape-form tool 13 in the axial direction, the second distance sensor 39 measures, through the measurement opening 29 , the distance to the bend or bulge 36 formed as a result of the shape-forming around the outer periphery of the pipe 2 . A corresponding signal is continuously provided by the second distance sensor via the second signal lead 45 to the control 41 . After the shape-forming of the pipe has ended by means of engagement of the shape-form tool 13 against the jaws 31 , the actual measurement value is compared with a desired value and it is determined whether the bulge 36 has achieved the desired outer diameter. Alternatively, the shape-forming can be ended once the control 41 determines that the bulge 36 has achieved the desired outer diameter and the control can thereby interrupt the shape-forming process. In this event, the shape-form length L serves to ensure that a sufficiently long shape-forming path is available.
[0063] After the stroke movement of the inner piston 9 in the axial direction to the left has ended, the second pressure space 28 is released from its pressurized condition—that is, the hydraulic medium disposed therein is permitted to flow out through the second pressure connector 27 . Moreover, the pressure medium in the first pressure space 26 is flowed out via the first pressure connector 25 . In this manner, the inner piston 9 is moved under the influence of the pressure medium in the second pressure space 25 in the axial direction toward the right. Thereafter, via opening of the blocking valve, the hydraulic medium in the first pressure space 26 is released so that the hydraulic medium flows out of the pressure space 26 . The outer piston 7 is returned to its start position by means of spring force generated thereagainst by one or more not-illustrated springs to return to its start position as shown in FIG. 6. In this manner, the jaws 31 release the shape-formed pipe 2 so that this pipe can be removed.
[0064] Once the heretofore described work steps, operational conditions and/or operational phases have been successfully concluded, the respective status is indicated by illumination of a respective one of the light emitting diodes 49 . In this connection, the control 41 controls the display device 47 . The meaning of the illumination of the in total six light emitting diodes 49 is, in connection with the serial passage of a successfully concluded shape-forming process, as follows:
[0065] 1. Light Emitting Diode: Compressive- and shape-forming tool correctly disposed,
[0066] 2. Light Emitting Diode: Pipe outer diameter is appropriate for the shape-forming tool,
[0067] 3. Light Emitting Diode: Forward movement of the outer piston and setting of the shape-forming length L concluded,
[0068] 4. Light Emitting Diode: Pipe set in compression,
[0069] 5. Light Emitting Diode: Pipe is shape-formed, shape-forming result is satisfactory,
[0070] 6. Light Emitting Diode: Return stroke is concluded, pipe can be removed.
[0071] If a mistake occurs, this can be determined by reading the display device 47 , which indicates the respective operational phase or, respectively, operational condition, during which the mistake occurred. In particular, an additional, not-illustrated light emitting diode can be provided which displays or illuminates if there is an interruption of the shape-forming process. Alternatively or additionally, a mistake can be indicated by intermittent lighting of a light emitting diode to show the corresponding operational phase. Also, it can be additionally interpreted that, if, for example, a light emitting diode does not illuminate, yet a light emitting diode later in the series does illuminate, that a mistake has occurred.
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The invention relates to a device for forming an end area of a workpiece ( 2), especially for cold press-forming an end area of a pipe, comprising two force transmitting elements ( 7, 9) which are guided in a common housing ( 3). The device is characterised in that a first pressure chamber ( 26) is located between the two force transmission elements ( 7, 9) and in that a second pressure chamber ( 28) is allocated to the second force transmission element ( 9). When the first force transmission element ( 7) is in the bracing position, the second force transmission element ( 9) can be displaced in relation to the first force transmission element ( 7) in order to form the workpiece.
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DESCRIPTION
1. Technical Field
This invention relates to a shield to be bonded to the leading surfaces of each lift wing of a conventional steel rotary mower blade; this shielding being made of a durable resilient elastomeric material that will substantially reduce wear to the lift wing from abrasion and the like to greatly increase the useful life of a blade.
2. Background Art
Conventional lawn mowers used by the average homeowner are usually rotary and are gasoline or electric motor operated. This type of mower is also popular with industrial mowing operations.
The term "rotary" refers to a mower in which the shaft extends vertically downward from the housing and upon which the blade is mounted so that it rotates in a plane parallel to the ground. This type of mower is popular because it is simple to operate, inexpensive to build, and performs a highly satisfactory job of cutting grass and weeds. Unfortunately, however, the performance of the cutting blade not only depends on a sharp cutting edge, but also having trailing lift wing or uplifted flange area on said blade. This lift wing working with, and as part of the blade, provides the air flow necessary to perform a satisfactory cutting job.
While the conventional steel blade may be re-sharpened as needed, nothing can be done to maintain the lift wing areas which tend to wear out long before the cutting edges are rendered useless. Additionally, the severely worn lift wings become fragmented and present a safety hazard. For this safety reason, most professional lawn mower service shops will not re-sharpen a blade that has severe lift wing damage. While a blade with a worn lift wing may be re-sharpened, the overall performance suffers because of the resulting loss of lift, and the aforementioned safety hazard still remains.
This loss of lift is particularly troublesome where bagging, or collection of the grass, is required. Lawn mower blade wear is especially severe in sandy types of soils.
DISCLOSURE OF THE INVENTION
It is an object of this invention to provide for an elastomeric shielding material to be bonded to the leading surfaces of each lift wing of a conventional steel blade to substantially reduce wear to the lift wing from abrasion and thus to greatly extend the useful life of a lawm mower blade.
It is another object of this invention to cut the protective material of the blade at such an angle as to provide an increase in the lift generated by the lawn mower blade to assure a more even cutting action of the blade.
It is a further object of this invention, because of the resulting increase in lift, to provide for more efficient movement of the grass clippings for bagging.
It is another object of this invention to form a shallow recess in the top of the blade to place the protective material. The forward edge of the protective material set in a recess will reduce the tendency of sand, dirt, et. to force itself under the protective material.
It is a further object of this invention to place the forward edge of the protective material parallel to and back from the rearward top of the cutting surface approximately 2 to 5 mm.
The foregoing, and other features and advantages of the present invention will become more apparent from the following description and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a rotary mower blade showing my invention;
FIG. 2 is a cross-sectional view of the rotary mower blade taken along the line 2--2 of FIG. 1;
FIG. 3 is a cross-sectional view of a modification of the rotary mower blade taken along the line 2--2 of FIG. 1; and
FIG. 4 is an enlargement of the modification of FIG. 3, also showing a recess.
BEST MODE FOR CARRYING OUT THE INVENTION
The mower blade of this invention, which is generally indicated at 7 of FIG. 1, is designed for horizontal rotation about the center of a bolt opening 5 of FIG. 1 at its center for receiving a bolt to attach the blade to a drive shaft of a mower. The blade 7 of FIG. 1 is elongated and is provided at each end with cutting surfaces 1 having leading edges 5 of FIG. 1 which are disposed on the forward side of the blade inasmuch as the blade is designed to rotate in the direction of the arrow 3 of FIG. 1.
Each lift wing 2 of FIG. 1 defines an angle θ with respect to the adjacent horizontal surface area 6 of FIG. 1. To each lift wing 2 is applied a layer 4 of polyurethane plastic, or similar protective material. Suitable materials include polyurethanes, such as the polyurethane materials supplied by Harkness Industries of Cheshire, Conn. as grades MP600 and MP750. Suitable materials will have Durometer hardness of 55-100 and preferably 60-85 measured on the Shore A scale and will exhibit less than 70 mg and preferably less than 45 mg loss per thousand cycles of Taber abrasion testing using the H18 test at 1,000 gms load (ASTM C501).
The polyurethane layer 4 should be of such a size as to cover the uplifted area of both lift wings 2, and the horizontal surface area 6 of the blade 7 that are adjacent to the lift wings 2. This is accomplished by having a single piece of polyurethane shaped for each lift wing 2 that is covered. The single layer 4 is cut to cover a lift wing 2 with allowance to cover a portion of the adjacent flat surfaces 6 of the blade 7. A mower blade 7, having two lift wings 2, will thus require just two layers 4 of protective material, one for each lift wing 2. The blade 7 can be recessed at 20 to receive the layer 4. This is done to especially prevent the undercutting of the leading edge of the leading surface 10 of layer 4 by sand, dirt particles, etc.
The polyurethane layer 4 should be approximately one-eighth to one-quarter inch in thickness and have a Durometer Shore A hardness of between 60a and 85a. The leading surface 10 of each protective layer 4 of FIG. 2 is cut at an acute angle with reference to the horizontal surface 6 of FIG. 1. Each leading surface 10 of layer 4 on each lift wing 2 provides an increase in the lift generated by the blade to improve the cutting action of the blade 7.
The bonding of the polyurethane layer 4 of the metal of the blade 7 can be accomplished by using a cyanoacrylate-type of adhesive, together with an appropriate primer such as those containing tetrahydrofuran. The BLACK MAX™ adhesive and PRISM™ 704 primer material supplied by Loctite of Newington, Conn. have been used with great success. The polyurethane surface of layer 4 to be bonded is first coated with the primer. The adhesive is then applied to the metal blade 7. The two surfaces are quickly joined together and clamped. They are then allowed to cure in air at normal air temperatures for approximately 120 hours. This bonding process results in an extremely tight and secure bond that will withstand severe shock and abrasion. Other protective materials of similar hardness can be affixed to a blade 7 over the lift wings 2.
The angled leading, or forward, surface 10 of a protective layer 4 can have its leading edge cut blunt at 12 to flatten the forward edge where it is adhered to the flat horizontal area surface 6. In tests with a layer 4 bonded to the surface 6, a test piece had a small portion of the leading edge of the forward surface 10 cut off at approximately 90° to be blunt at 12 and produced a very successful operation of the blade 7, and provided an extended life. In a blade made, the layer 4 had its angled forward surface 10 with its leading edge essentially parallel to the rearward top of the cutting surface 1 of the blade. This distance measured in the range of 2 to 5 mm.
Alternately, for high production situations, polyurethane materials may be cast over the lift wing portion of the blade. In these circumstances the blade may be perforated to provide mechanical interlocking between the lift wing blade portion and the polyurethane material.
Although this invention has been shown and described with respect to detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the claimed invention.
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A rotary mower blade for mounting on a power driven rotary lawn mower and designed for improved durability, performance, and safety. The blade is formed of solid metal in the conventional manner, but has an added elastomeric protective shielding applied to each uplifted flange area. The shielding of a layer of polyurethane can be mounted in a recess in the surface of the blade.
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BACKGROUND OF THE INVENTION
The invention relates to hydraulic processing grippers or hydraulic processing pincers.
“Processing gripper”, according to the invention, generally refers to a device with which workpieces can be gripped, machined or processed hydraulically and, therefore, with a high application of force. The processing gripper comprises at least two elements that can move in relation to each other and form a working gap between them, one of the elements is a hydraulically actuated press ram and the other element forms a workpiece assembly or a further workpiece element.
A generic hydraulic processing gripper is known in the art from DE 103 59 879 and is used to provide functional elements or connecting elements, such as nuts, bolts etc. in workpieces made of sheet metal by means of joining and subsequent pressing.
Especially for pressing there is a press ram or plunger, which for closing of the processing gripper during feeding can be moved from a press ram or plunger starting position into a working position, in which the plunger is supported on the functional element to be inserted into the workpiece and the functional element is supported on the workpiece. A hydraulic pressure cylinder then fixes the functional element in the workpiece by means of pressing, i.e. by means of permanent material deformation for example of the functional element and/or of the workpiece.
The basic advantage of the known setting gripper is that the feed movement of the press ram or plunger can be executed with a large stroke, and with reduced force, while the increased force required for processing or pressing when the processing gripper is closed is generated by the pressure cylinder, with an extremely short stroke. In order to achieve this, the processing gripper is designed so that the pressure piston of the pressure cylinder is arranged on the same axis with the press ram or plunger. As a result, the plunger, when advanced, is at an axial distance from the pressure piston of the pressure cylinder. Via a pressure element, which can be moved radially to the axis of the press ram, the distance between the pressure piston of the pressure cylinder and the advanced press ram is bridged. The pressure piston then acts on the press ram via this pressure element during pressing. When the press ram is retracted into starting position with the processing gripper open, the pressure element is located to the side of the press ram and therefore provides the free space necessary for the press ram to return to its starting position.
The disadvantage of the known processing gripper is its relatively large overall height, which is due in particular to the fact that the size of the pressure transfer element or pressure element in the axis direction of the workpiece is at least equal to the stroke of this press ram from its starting position to the working position.
It is an object of the invention to present a processing gripper that enables a more compact design while retaining the basic advantages of the existing gripper. This object is achieved by a processing gripper made up of a tool having an axially displaceable tool plunger, which, with a first end and an opposite work rest, forms a working region or a working gap and can be moved with the first end towards and away from the work rest. The processing gripper has a hydraulic actuating device for applying a force to the tool plunger via a movable pressure-transmitting element, the force moving the tool plunger in the direction of the work rest.
SUMMARY OF THE INVENTION
The advantage of the invention is, in particular, that the press ram or plunger in its retracted position or starting position is accommodated at least partially in the pressure cylinder or in the piston there or in the piston rod, so that the dimensions of the pressure transfer element in the direction of the axis of the press ram can be much smaller than the stroke of the press ram.
To eliminate this disadvantage, it has already been suggested to provide the pressure cylinder so that it is radially movable to the axis of the press ram, which however entails a more complex design due to the high pressure forces that have to be transferred from the pressure cylinder to the press ram.
The invention is characterized by a reduced overall height with a simplified design.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described below based on the drawings with sample embodiments, as follows:
FIG. 1 the elements of a work station for inserting components, for example connecting elements, in a workpiece;
FIGS. 2 and 3 a processing or setting gripper of the workstation in FIG. 1 in various operating states; and
FIG. 4 a schematic representation of the pressure cylinder of the processing gripper in a further possible embodiment.
DETAILED DESCRIPTION OF THE INVENTION
The work station depicted in FIG. 1 is used for the insertion of components, e.g. for the insertion of nuts 1 in workpieces 2 made of sheet metal.
The work station includes a workplace comprising a C-shaped or setting gripper 3 and of a hydraulic working cylinder 4 that drives the setting gripper 3 and is spatially separate from this gripper. The working cylinder 4 , or its working piston 4 . 1 , is actuated in the depicted embodiment by a motor (not depicted), via a threaded spindle 7 . The setting gripper 3 or a pressure cylinder 5 located there and the working cylinder 4 are connected with each other by means of a hydraulic pressure line 6 .
The setting gripper 3 , which is fastened to a machine frame or a mount (not depicted), consists of a C-shaped gripper frame 8 comprising the gripper arms 8 . 1 and 8 . 2 and the yoke section 8 . 3 connecting the arms. By means of the yoke section the gripper 8 is also fastened to a machine frame (not depicted). A tool head 9 with a matrix-type tool element 10 is provided on the arm 8 . 1 depicted as the lower arm in the drawings.
A punching head-shaped pressing tool 11 is fastened to the other gripper arm 8 . 2 , which is opposite the gripper arm 8 . 1 and depicted in the drawings as the upper arm. The pressing tool 11 is depicted only schematically in the drawings and consists essentially of a ram or plunger 12 , which is movably guided in a housing 13 fastened to the gripper arm 8 . 2 for an axial stroke in the plunger axis AP, extends with a partial length over the side of the housing 13 facing the gripper arm 8 . 1 , and supports a tool element 14 on the end of the partial length. The tool element 14 together with the tool element 10 joins and fixes (by pressing) the respective components 1 in the workpiece 2 .
A special characteristic of the setting gripper 3 or of the pressing tool 11 is that the closing of the setting gripper 3 , i.e. the moving of the plunger 12 with the tool element 14 and the components 1 to be inserted from the plunger starting position toward the workpiece 2 or into the plunger working position and the re-opening of the setting gripper 3 , i.e. the moving of the tool element 14 away from the workpiece 2 and the moving back of the plunger 12 into its plunger starting position, takes place by axial movement of the plunger 12 with a large stroke A, namely by a drive 15 indicated schematically in FIG. 2 , for example a pneumatic, electric or hydraulic drive, which effects this axial movement of the plunger 12 with relatively little force. The pressing of the components 1 takes place with great force and a short stroke B by the pressure cylinder 5 , which is provided on the top of the housing 13 .
The pressure cylinder 5 , as schematically depicted in FIGS. 2 and 3 , consists of a cylinder housing 16 and a piston rod 17 that is axially movable in the cylinder housing 16 with a piston 18 . The piston 18 delimits two cylinder chambers 16 . 1 and 16 . 2 , of which the cylinder chamber 16 . 1 can be pressurized with the hydraulic pressure of the working cylinder 4 during pressing.
The axis of the piston rod 17 is the same as the axis AP of the plunger 12 . The piston rod 17 is designed as a hollow rod, namely with an inner diameter that is somewhat larger than the outer diameter of the plunger 12 so that the plunger 12 in its raised, i.e. retracted plunger starting position, in which the tool element 14 is at the greater distance from the tool element 10 and therefore the setting gripper 3 is opened, is accommodated with a partial length in the piston rod 17 . This results in a low overall height for the setting gripper 3 .
To create the necessary driven connection between the piston rod 17 and the plunger 12 for pressing, a slide 19 is movably guided (double arrow C) on the top of the gripper arm 8 . 2 radially to the setting gripper axis AP, namely by a drive 20 . The drive 20 is an electric motor, hydraulic or pneumatic drive. A pressure plate 21 is provided or guided in the slide 19 so that it can be moved in the slide with a short stroke in an axis direction parallel to the axis SA.
By means of the drive 20 , the slide 19 can be moved from a starting position, in which the slide 19 including the pressure plate 21 is completely outside the sphere of movement of the plunger 12 ( FIG. 3 ), into a working position in which the slide 19 and its pressure plate 21 are located on the same axis as the axis SA.
The functional principle of the setting gripper 3 is shown in FIGS. 2 and 3 . It is assumed that the setting gripper 3 is opened. In this case the plunger, in the case of the slide 19 being retracted into the starting position, is moved upward by the drive 15 until the tool element 14 is at the greater distance from the tool element 10 and the upper partial length of the plunger 12 is accommodated in the piston rod 17 designed as a hollow rod. After insertion of the workpiece 2 , the setting gripper 3 is closed, i.e. the plunger 12 is moved downward by the drive 15 into the plunger working position so that the tool element 14 bears with the functional element 1 already present on said tool element against the workpiece 2 . The upper end 12 . 1 of the plunger 12 is then in the plane of the bottom of the slide 19 and of the pressure plate 21 or somewhat lower. However in any case the upper end 12 . 1 of the plunger 12 is at a distance below the lower end 17 . 1 of the piston rod 17 , which is at the level or somewhat above the level of the top of the slide 19 and the top of the pressure plate 21 .
Afterwards, the drive 20 moves the slide 19 from its starting position into the working position (arrow C). In the working position the pressure plate 21 is between the end 17 . 1 of the piston rod 17 and the top 12 . 1 of the plunger 12 , so that the pressure plate 21 creates a driven connection between the piston rod 17 and the plunger 12 . By pressurizing the cylinder chamber 16 . 1 with the hydraulic pressure supplied by the working cylinder 4 , the functional element 1 (e.g. nut) can be pressed in the workpiece 2 (e.g. sheet metal part) with a short stroke B via the piston rod 18 , the pressure plate 21 , the plunger 12 and the tool element 14 .
After pressing, the slide 19 moves back to its starting position so that the plunger 12 can be moved back up via the drive 15 to open the setting gripper 3 and the upper length of the plunger 12 is again accommodated in the piston rod 17 . The retraction of the piston 18 , is achieved for example, by pressurizing the cylinder chamber 16 . 2 with the hydraulic pressure.
It was assumed above that the piston rod 17 is designed as a hollow tube. Fundamentally, other designs are also possible. For example, and as shown in FIG. 4 , it is also possible to use instead of the piston 18 a piston 18 a , which is axially guided in the cylinder chamber of the cylinder housing 16 and has a suitable ratio of piston length to piston diameter for this purpose. The piston 18 a is provided with an opening 22 , which is open on the side facing the plunger 12 and in which the plunger 12 is accommodated with a partial length in the plunger starting position. For pressing, the opening 22 is then again closed by the pressure plate 21 , i.e. the latter is located between the piston 18 a and the upper plunger end 12 . 1 .
Further, it is possible to design in particular the tool element 14 so that it has a corresponding hold-down device, which for example presses the workpiece 2 against the tool element 10 prior to pressing and holds it in position there.
The invention was described above based on sample embodiments. It goes without saying that numerous modifications and variations are possible without abandoning the underlying inventive idea of the invention; all embodiments have in common that the piston or the piston rod of the pressure cylinder 5 is designed so that a partial length of the plunger 12 is accommodated in this pressure cylinder when the setting gripper is open.
REFERENCE LIST
1 functional element, for example nut
2 workpiece
3 setting gripper
4 working cylinder
5 pressure cylinder
6 hydraulic pressure hose
7 threaded spindle
8 C-shaped gripper frame
8 . 1 , 8 . 2 gripper arm
8 . 3 section
9 tool head on gripper arm 8 . 1
10 tool element
11 pressing tool
12 plunger
12 . 1 top end of plunger 12
13 housing
14 tool element
15 drive
16 cylinder housing of pressure cylinder 5
16 . 1 , 16 . 2 cylinder chamber
17 piston rod
17 . 1 end of piston rod 17
18 , 18 a piston
19 slider
20 drive for slider 19
21 pressure plate
22 opening
A feed movement of plunger 12 or of tool element 14
B movement stroke of pressure cylinder 5
C movement of slide 19
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The invention relates to a novel design of hydraulic processing pincers for processing workpieces, with a tool which, in a first tool part, has an axially displaceable tool plunger which, with a first end or with a tool provided there and an opposite work rest, forms a working region or a working gap and can be moved with the first end towards and away from the work rest, and made up of a hydraulic actuating device for applying a force to the tool plunger via a movable pressure-transmitting element, said force moving said tool plunger in the direction of the work rest. The piston and/or the piston rod are/is designed with a cavity in which the tool plunger is accommodated in its initial position at least over part of its length.
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FIELD OF THE INVENTION
This invention relates to an improved mold apparatus and method. In particular, the invention relates to an apparatus and method for creating designs on the interior of molds. Even more particularly, the invention relates to an apparatus and method for creating investment cast molds with complex designs on the interior and/or on the interior and exterior of the molds.
BACKGROUND OF THE INVENTION
A tension arises when a business attempts to create objects with unique designs. The tension results from a conflict between various competing interests a business has. On one hand, businesses are interested in obtaining objects with unique designs that meet or exceed the customer's requirements. On the other hand, the business must keep time and cost to a minimum in order to remain profitable. If time and money are no object, almost any object may be created with any unique designs imagined. Since time and money are always a concern, however, there is a practical limitation to the creation of objects with unique designs that results in the practical impossibility of creating some objects and some designs in a commercially reasonable, i.e. profitable, manner.
By way of example and not limitation, it is known throughout the munitions industry that certain types of notch patterns or grooves cut into the inside, and outside, walls of a projectile or warhead case dramatically improves their fragmentation characteristics, thereby increasing overall effectiveness. Typically, such notches are cut utilizing traditional machining methods such as broaching, shaping, milling and sawing.
A major drawback to these traditional machining methods is their inherent low production rate and high cost. The cost of the cutting tools, machinery, and labor required to implement these traditional machining methods can easily create a situation in which it is cost prohibitive or unprofitable to produce such items on a mass production basis. As a result, even though a number of warheads/projectiles in existence or currently in production do employ notches, they are very simple or less than optimal notch patterns. That is, currently straight-line configurations i.e. straight up-and-down notches or circumferential rings, are the only practical configurations for machined/broached projectile cases. Furthermore, while designs on the outside of the casing are easier, the preferred casing has designs on the inside or on the inside and outside in combination, which is, again , extraordinarily difficult to accomplish.
The prior art machined or broached warhead/projectile cases perform only adequately, because the fragments have a tendency to slab (not separate) due to the straight-line broaching/notching configuration limitation. As a result, fragmentation and, consequently, lethality is only modestly controlled and predictable when cases are created with the limited machine options known in the prior art.
Attempts have been made to create complex shapes without machining. Galliger, U.S. Pat. No. 6,019,927 discloses the use of a flexible and resilient positive pattern to make solid parts with complex geometry. However, the flexible and resilient pattern is simply used to create a hard shell into which metal is poured. That is, the Galliger device can only be used to create a solid thing and can not be used to create a casing with an interior with a complex geometry.
A further serious drawback of the prior art warhead/projectile case creation processes is that typically warhead/projectile cases are machined or forged from solid bar stock. Consequently, as much as seventy-five percent of the high-quality steel used to manufacture a warhead/projectile case goes into the scrap bin. This results in a huge waste of energy, time and material.
Still another serious drawback of the prior art techniques is that any hole, regardless of depth, that is machined in the solid bar stock, must have a zero draft angle (straight walls). A draft angle (taper), from the bottom of the hole to the beginning of the hole, creates a variation in wall thickness which is not acceptable in the munitions industry, for example. While complex, three dimensional, nonlinear designs can be created on the inside of cases with no draft angle, a myriad of specialized tooling and hardware is required which, for all practical purposes, makes the end product prohibitively expensive.
The investment casting process, also known as the “lost-wax ”casting process, provides a viable solution to many of the problems associated with traditional machining methods. Despite an industry bias against cast casings, by its very nature, the investment casting process lends itself well to the creation of protruding or indented features, such as the aforementioned notches. Another advantage is the significant reduction in material waste as well as a reduction in the time required to perform any necessary finish machining operations, since parts may be cast to near-net shape.
The first step in the traditional investment casting process is to produce a wax replica of the part to be cast. This item is commonly referred to as a wax pattern or wax mold. Typically, wax patterns are produced by injecting melted wax into an aluminum mold assembly with internal cavities and/or cores conforming to the desired was pattern shape. Upon cooling and solidifying, the wax pattern must be removed from the aluminum assembly.
For the purposes of the present invention, this is where problems with the prior art arise. A hollow wax pattern with a round cross section, such as a wax pattern for producing the aforementioned warhead/projectile casing with an internal notch configuration, can not be produced by an aluminum mold of conventional design. That is because, in order to produce the hollow, notched interior surface, the mold design would have to incorporate an aluminum core, and, in addition this core would have to have protrusions in order to create indentations (notches) in the wax pattern. This creates an interference condition in which the removal of the wax pattern from the aluminum core is impossible without destroying the wax pattern.
Thus, there is a need in the art for an inexpensive apparatus and method for creating designs on the inside and outside of cases and other objects.
SUMMARY OF TIE INVENTION
Accordingly, an apparatus for creating designs on the interior of molds includes a resilient form with an exterior and an interior, with a design formed on the exterior. A rigid support member is removably attached to the interior of the resilient form. A mold pattern, conformed to removably receive the rigid support member and the resilient form in combination, completes the basic assembly.
In one aspect of the invention, a passageway in the rigid support member is provided for introducing a gas between the rigid support member and the resilient form. In a further aspect of the invention, the design is a three dimensional design. In another aspect of the invention, a vacuum application device is provided for applying a vacuum to the resilient form. In a further aspect of the invention, the vacuum application device has a draft angle. In another aspect of the invention, the vacuum application device includes a plurality of extensions conformed to create a draft angle. In yet another aspect of the invention, the exterior of the resilient form has no draft angle and the interior has a draft angle. In another aspect of the invention, a lubricant is provided between the resilient form and the rigid support member.
In another embodiment of the invention, an apparatus for creating designs on the interior and exterior of a mold includes a first resilient form with an exterior and an interior, with a design on the interior. A rigid base is conformed to removably receive the exterior of the first resilient form. A second resilient form with an exterior and an interior, with a design on the exterior, is provided. A rigid support is removably attached to the interior of the second resilient form. The rigid base and the interior of the first resilient form is conformed to removably receive the rigid support member and the second resilient form in combination.
In another embodiment of the invention, in a process for creating an investment cast case, an apparatus for creating complex designs on the interior of the case includes a flexible sleeve with an exterior with a three dimensional design and no draft angle and an interior with a draft angle and a closed end and an open and. A support core, conformed to just receive and support the interior of the flexible sleeve from the closed end to the open end, is provided. Finally, a mold pattern is conformed to releasably receive the support core and flexible sleeve in combination.
In a further aspect of the invention, a passageway is provided in the support core conformed to introduce gas at the closed end of the flexible sleeve. In one aspect of the invention, a vacuum applicator is provided. In a further aspect of the invention, the interior has no draft angle. In another aspect of the invention, lubricant is provided between the flexible sleeve and the support core.
In another embodiment of the invention, in a process for creating investment cast cases, an apparatus for creating complex designs, including undercuts, notches, grooves, counter bores, slots, dimples and bosses, on the interior and exterior of a mold is provided.
In a further embodiment of the invention, a method of creating a design on the inside of a mold includes the steps of creating a resilient form with an exterior with a design and an interior. A rigid support member is attached to the interior of the resilient form. A mold pattern is created conformed to removably receive the resilient form and the rigid support member in combination. The resilient form and the rigid support member in combination are inserted into the mold pattern. Mold material is added to the mold pattern. Then the rigid support is removed. Finally, the resilient form is removed from the mold pattern.
In another aspect of the method, a passageway is provided in the rigid support member conformed to introduce gas between the rigid support member and the resilient form. Thereafter, gas is introduced in the passageway at the porper step to facilitate removal of the rigid support member. A further aspect of the method of this invention, includes forming the exterior with no draft angle and the interior with a draft angle. In another aspect of the method of the invention, a vacuum application device is provided and, after removing the rigid support from the old pattern, the vacuum application device is inserted within the interior of the resilient form in the mold pattern. Then, a vacuum is applied to the resilient form so as to collapse the resilient form around the vacuum application device and the vacuum application device is then removed from the mold pattern.
In still another aspect of the invention, the step of adding lubricant between the resilient form and the rigid support member is provided.
In another preferred embodiment a method of creating a design on the inside and the outside of a mold is provided.
In another preferred embodiment, a method for forming an investment cast case with a three dimensional design on the interior of the case includes the steps of creating a master pattern of the three-dimensional design in a female receiver. A male rigid support core is created with a draft angle, conformed to fit within the female receiver and including a passageway for introducing gas. The passageway is sealed with a removable pin so that the male rigid support core is a solid form. The male rigid support core is inserted into the female receiver and a flexible material forming fluid is introduced into the female receiver between the female receiver and the male rigid support core. The flexible material forming fluid is allowed to cure and create a flexible sleeve with a three dimensional design on the exterior and the interior conformed exactly to the male rigid support core. The removable pin is removed and compressed gas is blown into the passageway so that the gas is introduced between the rigid support core and the flexible sleeve. The flexible sleeve is removed from the master pattern female receiver. The male rigid support core is then inserted within the interior of the flexible sleeve and the flexible sleeve and rigid support core in combination are inserted within a mold pattern conformed to form the exterior of a case. Wax is added to the interior of the mold pattern and allowed to harden. The hardened wax and the combination of the flexible sleeve and the rigid support core are removed from the mold pattern. Compressed gas is blown into the passageway and the rigid support core is removed. The flexible sleeve is removed from the hardened wax. Finally, a case with three-dimensional designs on the inside of the case is created from the hardened wax by means of a lost wax process.
In a further aspect of the method of the invention, a vacuum applicator is provided and, after the rigid support core is removed from the hardened wax and the flexible sleeve, is inserted within the flexible sleeve. Then, a vacuum is applied to the inside of the flexible sleeve with the vacuum applicator so that the flexible sleeve is pulled away from the hardened wax and attached to the vacuum applicator. Then, the vacuum applicator, and flexible sleeve, is removed from the hardened wax. In another aspect of the invention, the vacuum applicator is formed with a draft angle.
DESCRIPTION OF THE DRAWINGS
Other objects, features, and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiment, the appended claims and the accompanying drawings in which:
FIG. 1 is a side sectional view of the master pattern of the apparatus for creating designs on the interior of mold to the present invention;
FIG. 2 is a side sectional view of the support core of the present invention;
FIG. 3 is a side sectional view of the support core, with a removable pin in place, joined together with the master pattern;
FIG. 4 is a side sectional view illustrating the formation of the flexible sleeve of the present invention by using combination illustrated in FIG. 3;
FIG. 5 shows the master pattern in combination with the support core where in the removable and is removed and the flexible sleeve has been formed;
FIG. 6 is an exploded view showing the support core separated from the flexible sleeve and removed from the master pattern;
FIG. 7 is an exploded view showing the flexible sleeve removed from the master pattern;
FIG. 8 is an exploded view showing the flexible sleeve in preparation for been inserted over the support core without the removable pin;
FIG. 9 is an exploded view showing the flexible sleeve in combination with the support core ready for insertion into the mold pattern;
FIG. 10 shows the flexible sleeve held by the support core in place within the mold pattern;
FIG. 11 is an exploded view showing the flexible sleeve and the support core removed from the mold pattern with a mold material adhered to the flexible sleeve;
FIG. 12 is an exploded view showing the support core removed from the flexible sleeve and would be mold material still adhered to the flexible sleeve;
FIG. 13 is an exploded view illustrating the vacuum extractor of the present invention part to insertion within the flexible sleeve to which the mold material is still attached;
FIG. 14 illustrates the vacuum extractor in place within the mold material and the flexible sleeve as a vacuum is applied so that the flexible material is pulled away from the mold material;
FIG. 15 is an exploded view and showing the vacuum extractor removed from the mold material along with the flexible sleeve leaving the finished mold pattern; and
FIG. 16 is a top sectional view of the apparatus of the invention for creating designs on the interior and the exterior of a mold.
DETAILED DESCRIPTION OF THE INVENTION
The preferred embodiments of the present invention are illustrated by way of example in FIGS. 1 through 16. The apparatus and method for creating designs on the interior of molds 10 of the present invention may be begun to be understood by reference to FIGS. 1 and 2. FIG. 1 illustrates master pattern 12 . In a preferred embodiment, master pattern 12 is formed from clear cast acrylic. The master pattern 12 is carefully created to include any and every conceivable form of three dimensional design which may be desired to be created, including but not limited to non-linear overhangs and undercuts, notches, grooves, counter bores, slots, dimples, and bosses. Master pattern 12 includes inlet 14 as will be discussed more fully hereafter.
Referring now to FIG. 2, support core 16 is illustrated. Support core 16 includes removable pin 18 and an air vent ( passageway) 20 . Additionally, in a preferred embodiment, support core 16 includes a draft angle 22 .
FIG. 3 shows support core 16 in place within master pattern 12 . Removable pin 18 is shown in place within support core 16 , so that support core 16 is a solid form.
Referring now to FIG. 4, one step of the method of the invention is illustrated whereby pressure pot 24 includes flexible material forming fluid 26 . Flexible material forming fluid 26 may be any liquid for forming a flexible material as is now known or hereafter developed such as a polymer of any type. As illustrated, pressure pot 24 includes a pressure system 28 including an air pressure inlet 30 , pressure gauge 32 and air pressure outlet 34 . Flexible material forming fluid 26 is forced from pressure of pot 24 through connection 36 controlled by open and close valve 38 . Connection 36 is attached to inlet 14 on master pattern 12 . As illustrated, support core 16 with removable pin 18 is in position within master pattern 12 . Open and close valve 38 is opened, air pressure is applied through pressure system 28 and flexible material forming fluid 26 flows into master pattern 12 and around support core 16 . Air vent 20 allows air to escape from master pattern 12 .
Referring now to FIGS. 5, 6 , and 7 , removable pin 18 is shown removed from support core 16 exposing pin passageway 40 . If necessary, gas, compressed air or the like, is introduced into passageway 40 so that support core 16 may be removed from master pattern 12 . In some cases, no air or gas is needed and passageway 40 is unnecessary. At that point, flexible sleeve 42 , formed from the flexible material forming fluid 26 , is removed from master pattern 12 . Flexible sleeve 42 now includes an exterior that exactly matches the master pattern that was painstakingly and carefully created in the master pattern 12 . The resulting three dimensional design created in flexible sleeve 42 is created on the exterior 44 of flexible sleeve 42 . Additionally, because support core 16 was formed with a draft angle 22 , the interior 46 of flexible sleeve 42 has an exactly identical draft angle 22 . To reiterate, exterior 44 includes three dimensional designs exactly matching the designs in master pattern 12 without a draft angle while interior 46 of flexible sleeve 42 , in a preferred embodiment, has a draft angle 22 identical to and formed by a draft angle 22 of support core 16 .
Referring now to FIGS. 8, 9 , and 10 , the apparatus and method for creating designs on the interior of molds is further explained. FIG. 8 shows flexible sleeve 42 in position to be reconnected, attached, to support core 16 . Support core 16 at this stage does not include removable pin 18 so that pin passageway 40 , if provided, is open and free. FIG. 9 shows flexible sleeve 42 in position over support core 16 , i.e. with support core 16 inserted in the interior 46 of flexible sleeve 42 , and ready for insertion together into mold pattern 48 . Mold pattern 48 is any mold pattern desired for the exterior of the final product. For example, FIG. 9 shows mold pattern 48 formed into the exterior smooth shape of a projectile case. In FIG. 10, flexible sleeve 42 in combination with support core 16 is shown in position on mold pattern 48 . Mold pattern 48 includes injection port 50 . It should be clear at this time, that the exterior 44 of flexible sleeve 42 which includes the three dimensional design from master pattern 12 will form the interior of the projectile case created by mold pattern 48 .
Referring now to FIGS. 11 and 12, mold material 52 , which was injected into mold pattern 48 through injection port 50 , has solidified. In FIG. 11, mold material 52 , having taken on the exterior form of the projectile case created by mold pattern 48 , has been removed from mold pattern 48 . At this time, support core 16 and flexible sleeve 42 are still connected to mold material 52 . In FIG. 12, gas, such is compressed air, for example, has been introduced into pin passageway 40 thereby separating support core 16 from flexible sleeve 42 and allowing support core 16 to be easily withdrawn from flexible sleeve 42 . In a preferred embodiment, a lubricant 54 is previously added between support core 16 and flexible sleeve 42 . Lubricant 54 may be any appropriate lubricant now known or hereafter developed, such as, for example, talcum powder.
Referring now to FIGS. 13, 14 , and 15 , a preferred embodiment for removing flexible sleeve 42 from mold material 52 is illustrated. In many cases, flexible sleeve 42 may physically be removed from mold material 52 simply by pinching flexible sleeve 42 together and withdrawing it. However, in larger mold patterns 48 , and whenever the design created in master pattern 12 is intricate and complex such that the design may be damaged when removing the flexible sleeve 42 , a preferred embodiment includes withdrawing flexible sleeve 42 by means of vacuum extractor 56 . In use, vacuum extractor 56 is inserted within flexible sleeve 42 while still in connection with mold material 52 . As illustrated, once vacuum extractor 56 is in place within flexible sleeve 42 , a vacuum is applied such that flexible sleeve 42 is sucked onto vacuum extractor . 56 and away from mold material 52 . At that point, vacuum extractor 56 , in combination with flexible sleeve 42 , is removed from mold material 52 . In a preferred embodiment, vacuum extractor 56 includes a draft angle 22 . In another preferred embodiment, vacuum extractor 56 includes a plurality of extensions 58 conformed to form a draft angle by decreasing dimension toward the closed end 60 of flexible sleeve 42 and increasing dimension toward the open end 62 of flexible sleeve 42 .
At this time, as illustrated in FIG. 15, mold material 52 includes an exterior 64 created by mold pattern 48 and the identical design from master pattern 12 on the interior 66 of mold material 52 which exactly matches the design on the exterior 44 of flexible sleeve 42 . In a preferred embodiment, mold material 52 is wax. At this time, mold material 52 is utilized to create a cast case with three dimensional designs on the inside of the case identical to the designs now on the hardened wax mold material 52 by means of a lost wax process as is known in the art and not disclosed more fully herein.
Applicant' invention further includes an apparatus and method for creating complex designs on the interior and exterior of a mold. By way of example and not limitation, it is sometimes desirable for notches and the like to be formed on both the inside and outside of a projectile case. Whenever necessary this is easily accomplished by Applicants' invention as illustrated in FIG. 16 . To begin with, a master pattern is created with the required design on the outside of master pattern 12 . A first flexible sleeve 68 is formed in a manner as described above for the creation of flexible sleeve 42 , except that the design is created on the interior 72 of first flexible sleeve 68 not the exterior 74 . Thereafter, a second flexible sleeve 70 is created in the identical manner as flexible sleeve 42 discussed above, including having the design on the exterior 44 and not the interior. Once both first flexible sleeve 68 and second flexible sleeve 70 are ready, first flexible sleeve 68 is inserted in and contained and supported by rigid base 76 . At that point, second flexible sleeve 70 in combination with support core 16 , as discussed and disclosed above, is positioned within the interior 72 of first flexible sleeve 68 and spaced apart therefrom. At that point, mold material 52 is injected between the interior 72 of first flexible sleeve 68 and the exterior 44 of second flexible sleeve 70 . Because the desired design is on the interior 72 and on the exterior 44 , the mold material 52 has the desired design both on the exterior 64 and the interior 66 . Once mold material 52 has hardened, rigid base 76 is removed and first flexible sleeve 68 is peeled or rolled off of the exterior 64 . Next, support core 16 is removed and then second flexible sleeve 70 is removed leaving a wax, for example, mold of mold material 52 with complex designs on both the exterior 64 and the interior 66 . Thereafter, a casing with identical features can be created by the lost wax process.
By way of the present invention then, any form of complex design is capable of being created on the interior 66 or exterior 64 of mold material 52 . Importantly, because flexible sleeve 42 , used to create the design on the interior 66 of mold material 52 has an exterior 64 that has no draft angle, the interior 66 of mold material 52 also has no draft angle. Once again, this is critical, because in many instances, draft angles on the interior result in inferior products. By way of example, as previously discussed warhead and projectile cases require uniform thicknesses for predictable results. Prior to applicants' invention, tedious and expensive hand tooling was the only way complex designs could be created on the interior of projectile cases. Now, by way of applicant' invention, extraordinarily complex designs are capable of being formed on the interior and the exterior of projectile cases by investment casting. Huge amounts of material waste are prevented and time saved with a product that is superior in strength and fragmentation predictability.
While the present invention has been disclosed by way of example in connection with use in the creation of investment casting warhead and projectile cases, certainly no narrow limitation may be inferred thereby on the uses of applicant' invention. For any business, and for any purpose, where a need exists for the creation of a complex design on the interior and/or the interior and exterior of an object, applicant' invention applies. That is, the description of the present embodiments of the invention have been presented for purposes of illustration, but are not intended to be exhaustive or. to limit the invention to the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. As such, while the present invention has been disclosed in connection with the preferred embodiment thereof, it should be understood that there may be other embodiments with fall within the spirit and scope of the invention as defined by the following claims.
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A mold apparatus and method for creating designs on the interior of molds includes a resilient form with an exterior and an interior, with a design formed on the exterior. A rigid support member is removably attached to the interior of the resilient form. A mold pattern, conformed to removably receive the rigid support member and the resilient form in combination, completes the basic elements of the invention. In one aspect of the invention, a passageway in the rigid support member is provided for introducing a gas between the rigid support member and the resilient form. In another aspect of the invention, a vacuum application device is provided for applying a vacuum to the interior of the resilient form. The apparatus and method also provide for the simultaneous creation of designs on the interior and exterior of molds
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to a cutting tool and is specifically concerned with a separable end working or rotary cutting tool that is adapted to rotate to cut a stationary workpiece or that may cut a rotating work piece when stationary.
2. Description of the Related Art
Separable rotary cutting tools are known in the prior art. One such tool is described in U.S. Pat. No. 5,904,455, to Krenzer et al. This tool is described as a drill comprising an insert and body. The drill has a locating feature comprised of a groove in the body defined by two groove flanks and mating side faces on the head. The groove is slightly smaller than the insert. This results in a positive location and an interference fit between the insert and body. In operation, the insert is forced in an axial direction in the groove or drawn into the groove with a screw. In absence of a screw, the insert is predisposed to be axially displaced and thus can become axially dislodged from the groove. On the other hand, the use of a screw would require the physical size of the tool to be large enough to accompany the screw.
Other separable rotary cutting tools are described in U.S. Pat. Nos. 6,059,492 and 5,957,631, to Hecht. Both patents describe an insert and body joint. One embodiment includes two base surfaces, two torque transmission walls, and two fixation walls. The transmission and fixation walls are located between the base surfaces and adjacent to one another. The transmission walls are spaced 180 degrees apart as are the fixation walls. The fixation walls are conical or dovetail in shape and expand in a direction away from the cutting tip of the insert. The base surfaces are transverse or perpendicular from the axis of the body. A front base surface is used as the axial stop. The torque transmission walls are defined as extending in radial directions. The fixation walls are defined as having radial dimensions substantially less than the cutting diameter. Hecht also describes an embodiment comprised of a pair of base surfaces, one of which acts as an axial stop. Torque transmission walls and fixation walls are located between these base surfaces. The torque transmission walls are transverse to the axis of the fixation walls. The length of the fixation and transmission walls is about the same. The fixation walls are located further away from the tool tip than the torque transmission walls. Both of these embodiments described by Hecht have a reduced risk of becoming axially dislodged because each includes conical or dovetail shaped fixation walls. However, such walls are difficult to machine because the walls expand in a direction away from the cutting tip of the insert and into the body.
Clearly, there is a need for a separable rotary cutting tool that is not prone to inadvertent axial separation. Ideally, such a tool would be easier to manufacture and thus minimize the cost of the tool. Finally, it would be desirable if such a tool could be easily assembled.
SUMMARY OF THE INVENTION
Generally speaking, the invention is directed to a rotary cutting tool that overcomes the aforementioned shortcomings associated with the prior art. To this end, the tool of the invention comprises a shank and a head. The shank has a receiver comprised of a shank guide at a trailing end of the receiver, opposing shank drive keys at a leading end of the receiver, and a shank locator located axially between the shank guide and the shank drive keys. The shank drive keys each comprises an axially extending shank drive key radial stop surface that is disposed at an angle relative to a plane extending through a central axis of the receiver. The head has a connector comprised of a head guide at a trailing end of the connector, opposing head drive keys at a leading end of the connector, and a head locator located axially between the head guide and the head drive keys. The head drive keys each comprises an axially extending head drive key radial stop surface that is disposed at an angle relative to a plane extending through a central axis of the connector. Each shank drive key radial stop surface is adapted to angularly align with a corresponding head drive key radial stop surface.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features of the present invention, as well as the advantages derived therefrom, will become clear from the following detailed description made with reference to the drawings in which:
FIG. 1 is an exploded perspective view of a rotary cutting tool of the invention;
FIG. 2 is a perspective view of the rotary cutting tool shown in FIG. 1 partially assembled;
FIG. 3 is a perspective view of the rotary cutting tool shown in FIGS. 1 and 2 completely assembled;
FIG. 4 is an exploded side elevational view of the rotary cutting tool shown in FIGS. 1-3;
FIG. 5 is a sectional view in elevation of a rotary cutting tool of the invention;
FIG. 6 is a cross-sectional view of the rotary cutting tool taken along the line 6 — 6 in FIG. 5;
FIG. 7 is a sectional view in elevation of another rotary cutting tool of the invention;
FIG. 8 is a cross-sectional view of the rotary cutting tool taken along the line 8 — 8 in FIG. 7;
FIG. 9 is a sectional view in elevation of another rotary cutting tool of the invention;
FIG. 10 is a cross-sectional view of the rotary cutting tool taken along the line 10 — 10 in FIG. 9;
FIG. 11 is a sectional view in elevation of another rotary cutting tool of the invention;
FIG. 12 is a cross-sectional view of the rotary cutting tool taken along the line 12 — 12 in FIG. 11;
FIG. 13 is a sectional view in elevation of another rotary cutting tool of the invention;
FIG. 14 is a cross-sectional view of the rotary cutting tool taken along the line 14 — 14 in FIG. 13;
FIG. 15 is a sectional view in elevation of another rotary cutting tool of the invention; and
FIG. 16 is a cross-sectional view of the rotary cutting tool taken along the line 16 — 16 in FIG. 15; and
FIG. 17 is a sectional view of the taken along the line 17 — 17 in FIG. 16 .
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference now to FIGS. 1-6, wherein like numerals designate like components throughout all of the several Figures, there is illustrated a rotary drill or tool 10 having a leading end, generally indicated at 12 , and the trailing end, generally indicated at 14 . The tool 10 is comprised of a body or shank 16 and an insert or head 18 . The shank 16 has a receiver or receiving portion 20 at its leading end and a shank 22 at its trailing end. The head 18 has a cutting tip 24 at its leading end and a connector or mounting portion 26 at its trailing end. The mounting portion 26 cooperates with the receiving portion 20 to couple the head 18 to the shank 16 .
The receiving portion 20 is comprised of a guide or shank guide portion 28 , a locator or shank locating portion 30 at the leading end of the shank guide portion 28 , and diametrically disposed torque or drive keys 32 (also referred to as shank drive keys) at the leading end of the shank locating portion 30 . The mounting portion 26 is comprised of diametrically disposed torque or drive keys 34 (also referred to as head drive keys), a locator or head locating portion 36 at the trailing end of the head drive keys 34 , and a guide or head guide portion 38 at the trailing end of the head locating portion 36 .
The mounting portion 26 is adapted to be axially inserted into the receiving portion 20 until the head guide portion 38 engages the shank guide portion 28 . Upon twisting the head 18 , the locating portions 30 and 36 engage one another to provide an interference fit. The drive keys 32 and 34 radially engage one another to function as cooperating radial stop surfaces and drive surfaces during the operation of the tool 10 .
The shank guide portion 28 is preferably defined in part by an inner cylindrical surface, such as the inner guide surface 40 shown. The inner guide surface 40 is preferably a generally straight cylindrical surface having a shank guide diameter D 1 (shown in FIG. 4 ). The shank guide portion 28 may also be provided with a generally spherical radial inner radial surface 42 adjacent its trailing end, as shown in FIGS. 1-6, or a conical inner radial surface 44 , as shown in FIG. 6 . In a preferred embodiment of the invention, the diameter of a conical inner radial surface 44 increases toward the leading end of the shank guide portion 28 . The trailing end of the shank guide portion 28 may be defined by a first radially extending surface, which may also be referred to a radially extending shank guide surface. The first radially extending surface may be an arcuate or spherical surface 46 , which may coexist with the spherical inner radial surface 42 , or a generally flat surface 48 , as shown in FIGS. 7, 9 , 11 , 13 , and 15 , which extends generally perpendicular to the axis A 1 of the shank 16 . The spherical and conical inner radial surfaces 42 and 44 may function as axial stop surfaces, as shown in FIGS. 5 and 7. This holds true even if the radially extending surface is perpendicular to the shank axis A 1 , as shown in FIGS. 9, 11 , 13 , and 15 .
The shank locating portion 30 is preferably defined by a cylindrical bore. The cylindrical bore may be a generally straight cylindrical bore defined by generally straight cylindrical inner locating surfaces 50 , as shown in FIGS. 7, 9 , 11 , 13 , and 15 , or a tapered bore defined by tapered inner locating surfaces 52 , as shown in FIG. 5 . The distance between the generally straight cylindrical inner locating surfaces 50 , or the smallest distance between the tapered inner locating surfaces 52 , is measured by a shank locator or locating diameter D 2 (shown in FIG. 4 ).
The surfaces defining the shank guide and locating portions 28 and 30 may be joined by a transitional surface 54 . In a preferred embodiment of the invention, the transitional surface 54 is inclined obliquely relative to the central axis A 1 of the shank 16 and faces generally longitudinally toward the leading end of the receiving portion 20 . The transitional surface 54 accommodates for the difference between the shank guide and locating diameters D 1 and D 2 (shown in FIG. 4 ).
The locating portion 30 terminates at a second radially extending surface located at the leading end of the locating portion 30 . The second radially extending surface may be defined by a pair of radially extending surfaces 56 , which extend perpendicularly to the central axis A 1 of the shank 16 , as shown in FIGS. 5, 7 , 9 , 13 , and 15 , or radially extending surfaces 58 , which are inclined obliquely relative to the central axis A 1 and face generally longitudinally toward the leading end of the shank 16 , as shown in FIG. 11 . The second radially extending surface may function as an axial stop surface in the place of the first radially extending surface described above.
The shank drive keys 32 are located at the leading end of the shank locating portion 30 . In a preferred embodiment of the invention, the shank drive keys 32 have an axial profile dimension D 3 (shown in FIG. 5) and a radial profile dimension D 4 (shown in FIG. 4 ). The radial profile dimension D 4 is preferably smaller than the axial profile dimension D 3 to enable the shank drive keys 32 to be closely aligned with the central axis A 1 of the shank 16 . The shank drive keys 32 are defined by an inner shank drive key surface 60 , an outer shank drive key surface 62 , a pair of circumferentially spaced, axially extending shank drive key surfaces 66 and 64 , and a radially extending shank drive key surface, which may also be referred to as a third radially extending surface 68 . The third radially extending surface 68 extends in a first direction between the inner and outer shank drive key surfaces 60 and 62 and in a second direction between the circumferentially spaced, axially extending shank drive key surfaces 66 and 64 , all shown in FIG. 1 . The inner shank drive key surface 60 may be coexistent with the inner shank locating surface. Similarly, the outer shank drive key surface 62 may be coexistent with an outer curved surface 70 of the shank 16 . One of the circumferentially spaced, axially extending shank drive key surfaces 66 may define a flute, or a flute portion, through which particles of a workpiece may be discharged when the tool 10 is in use. The other circumferentially spaced, axially extending shank drive key surface 64 functions as a shank drive key radial stop surface, which is preferably disposed at an angle α (shown in FIG. 5) relative to a plane extending through the axis A 1 of the shank 16 and facing generally longitudinally toward the trailing end of the shank 16 . In a preferred embodiment of the invention, the angle α is 15 degrees. The shank drive key radial stop surfaces 64 may be perpendicular relative to the inner and outer shank drive key surfaces 60 and 62 , as shown in FIGS. 5, 9 , 11 , 13 , and 15 . Alternatively, shank drive key radial stop surfaces 72 may be provided which are inclined relative to the inner and outer shank drive key surfaces 60 and 62 , as shown in FIG. 7 . The third radially extending surface 68 may be perpendicular relative to the central axis A 1 of the shank 16 , as shown in FIGS. 5, 7 , 11 , and 13 . Alternatively, a third radially extending surface 74 may be provided which is inclined relative to the central axis A 1 , as shown in FIGS. 9 and 15. Inclined axially or radially extending surfaces may reduce the risk that the shank drive keys 32 will spread apart. It should be appreciated that the third radially extending surface 68 may function as an axial stop surface in the place of the first and second radially extending surfaces described above.
The head guide portion 38 is preferably defined in part by an outer cylindrical surface, such as the outer guide surface 78 shown. The outer guide surface 78 is preferably a straight cylindrical surface having a head guide diameter D 5 (shown in FIGS. 4 and 6 ). The head guide portion 38 may also include a generally spherical outer radial surface 82 , as shown in FIG. 5, adjacent its trailing end, or a conical outer radial surface 84 , as shown in FIG. 7 . In a preferred embodiment of the invention, the diameter of the conical surface 84 increases toward the leading end of the head guide portion 38 . The trailing end of the head guide portion 38 may be defined by a first radially extending surface, which may also be referred to as a radially extending head guide surface. The first radially extending surface maybe an arcuate or spherical radial surface, which may coexist with the spherical outer radial surface 82 , or a generally flat surface 76 , as shown in FIGS. 7, 9 , 11 , 13 , and 15 , which extends generally perpendicularly to the axis A 2 of the head 18 . The head guide portion 38 is adapted to engage the shank guide portion 28 and functions to stabilize the shank 16 and head 18 in radial direction when coupling the head 18 to the shank 16 .
The head locating portion 36 is defined by an outer surface. The outer surface may be a generally straight cylindrical surface outer locating surface 86 , as shown in FIGS. 7, 9 , 11 , 13 , and 15 . Alternatively, the outer surface may be a tapered outer locating surface 88 , as shown in FIG. 5 . The largest diameter of the outer surface is defined by the head locator or locating diameter D 6 (shown in FIGS. 4 and 6) and is slightly larger than the shank locating diameter D 2 (shown in FIG. 4 ). Consequently, the head locating portion 36 must be forced into the shank locating portion 30 , causing the shank locating portion 30 to deflect outward, resulting in an interference fit between the two locating portions 30 and 36 . It should be appreciated that a tapered outer locating surface 88 having a larger diameter at its leading end insures contact substantially with the entire shank locating portion 30 , even when the shank locating portion 30 deflects outward. The increase in diameter D 6 is preferably measured by an angle of inclination β (shown in FIG. 5) in the tapered outer locating surface 88 of less than one degree relative to a plane P 1 extending generally parallel to the central axis A 1 .
The head locating portion 36 preferably has an axially extending angular lead surface 90 which provides clearance for an approaching portion of the head location portion 36 upon rotating the head 18 to couple the head 18 to the shank 16 . The angle of the axially extending or angular lead surface 90 may vary. The angle is preferably in a range between 2 degrees and 20 degrees. For example, the angle θ 1 of the lead surface 90 shown in FIG. 14 is 15 degrees relative to a line tangent to the outer locating surface at the intersection of the outer locating surface and the lead surface 90 . The angle θ 2 of the lead surface 90 shown in FIG. 6, 8 , 10 , 12 , and 16 is 20 degrees.
In the preferred embodiment of the invention, the head locating portion 36 has a larger diameter D 6 (shown in FIGS. 4 and 6) that is more than half the cutting diameter D 7 of the tool 10 (shown in FIGS. 4 and 5 ). This is to establish a relationship between the locating diameter and the depth of the flute to insure proper assembly of the shank 16 and head 18 . Moreover, the length of the head locating portion 36 is slightly less or more than the head locating diameter D 6 (shown in FIGS. 4 and 6 ). For example, a range for the length of the head locating portion 36 may be ¾ to 2 times the head locating diameter D 6 . The length of the head locating portion 36 would be determined by the size of the tool 10 . Larger tools would be in the ¾ to 1 ¼ range while smaller diameters could be up to 2 times the diameter.
Similar to the receiving portion 20 set forth above, the mounting portion 26 may be provided with a transitional surface 92 . In a preferred embodiment of the invention, the transitional surface 92 is inclined obliquely relative to the central axis A 2 of the head 18 and faces generally longitudinally toward the trailing end of the mounting portion 26 . The transitional surface 92 accommodates for the difference between the head guide and locating diameters D 5 and D 6 (shown in FIGS. 4 and 6 ).
The head locating portion 36 terminates at a second radially extending surface located at the leading end of the head locating portion 36 . The second radially extending surface may be defined by a pair of radially extending surfaces 94 , which extend perpendicularly to the central axis A 2 of the head 18 , as shown in FIGS. 5, 7 , 9 , 13 , and 15 , or radially extending surfaces 96 , which are inclined obliquely relative to the central axis A 2 and face generally longitudinally toward the trailing end of the head 18 , as shown in FIG. 11 .
The head drive keys 34 are located at the leading end of the head locating portion 36 . In a preferred embodiment of the invention, the head drive keys 34 have an axial profile dimension D 8 and a radial profile dimension D 9 (shown in FIG. 4 ). The radial profile dimension D 9 is preferably less than the head locating diameter D 6 (shown in FIGS. 4 and 6 ). Longer head drive keys 34 may result in a weaker connection between the shank 16 and the head 18 . Moreover, the radial profile dimension D 9 is preferably smaller than the axial profile dimension D 8 to enable the head drive keys 34 to be closely aligned with central axis A 2 of the head 18 . The head drive keys 34 are defined by an outer head drive key surface 100 , circumferentially spaced, axially extending head drive key surfaces 102 and 104 , and a radially extending head drive key surface, which may be referred to as a third radially extending surface 106 (all shown in FIG. 1 ). One of the axially extending head drive key surfaces 102 may define a portion of a flute. The other axially extending head drive key surface 104 functions as a head drive key radial stop surface, which is preferably disposed at an angle a relative to a plane P 1 extending through a central axis A 2 of the head 18 and facing generally longitudinally toward the leading end of the head 18 , as shown in FIG. 5 . In a preferred embodiment of the invention, the angle α is 15 degrees. The head drive key radial stop surfaces 104 may be perpendicular relative to the outer surface 100 , as shown in FIGS. 5, 9 , 11 , 13 , and 15 . Alternatively, head drive key radial stop surfaces 108 may be provided which are inclined relative to the outer surface 100 , as shown in FIG. 7 . The head drive key radial stop surfaces 102 and 108 are adapted to fit in angular alignment with the shank drive key radial stop surfaces 64 and 72 . The third radial surface 106 may be perpendicular relative to the central axis A 2 . Alternatively, a third radially extending surface 106 may be provided which is inclined relative to the central axis A 2 , as shown in FIGS. 9, 15 , and 17 .
In operation, the mounting portion 26 is adapted to be inserted axially into the receiving portion 20 . Subsequently, the head 18 is twisted into a final radial location determined by the engagement of the shank drive keys 32 and 34 .
It should be noted that the locating diameters D 2 and D 6 (shown in FIG. 4) must be larger than the guide diameters D 1 and D 5 (also shown in FIG. 4 ). Moreover, the guide diameters D 1 and D 5 should be sufficiently small enough to require the head guide portion 38 to be inserted axially into the shank guide portion 28 . In this way, the guide portions 38 and 28 cooperatively act as a guide during rotation of the head 18 . The drill flutes should be dimensioned so that the head guide portion 38 does not escape in the radial direction from the shank guide portion 28 . By providing locating diameters D 2 and D 6 that are larger than guide diameters D 1 and D 5 , the drill flutes may be dimensioned large enough to allow the mounting portion 26 to be inserted into the receiving portion 20 within the flutes. The head 18 may then be rotated 90 degrees with an assembly tool (not shown) that serves as a radial guide for the leading end of the shank 16 and the head 18 .
The angular alignment of the drive key radial stop surfaces 64 and 72 provides retention of the head 18 during removal of the tool 10 from a work piece (not shown). Rotary cutting tools tend to drag during retraction. This drag creates a torsional moment on the head 18 as well as a force to separate the head 18 from the shank 16 . The torsional moment, combined with the angular alignment of the drive keys 32 and 34 , make it difficult for the head 18 to separate from the shank 16 .
It should be appreciated that the shank 16 may include a mounting portion, such as that shown and described above, and the head 18 may include a receiving portion.
While this invention has been described with respect to several preferred embodiments, various modifications and additions will become apparent to persons of ordinary skill in the art. All such variations, modifications, and variations are intended to be encompassed within the scope of this patent, which is limited only by the claims appended hereto.
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A separable rotary cutting tool is disclosed. The tool comprises a shank and a head. The shank has a receiver comprised of a shank guide at a trailing end of the receiver, opposing shank drive keys at a leading end of the receiver, and a shank locator located axially between the shank guide and the shank drive keys. The shank drive keys each comprises an axially extending shank drive key radial stop surface that is disposed at an angle relative to a plane extending through a central axis of the receiver. The head has a connector comprised of a head guide at a trailing end of the connector, opposing head drive keys at a leading end of the connector, and a head locator located axially between the head guide and the head drive keys. The head drive keys each comprises an axially extending head drive key radial stop surface that is disposed at an angle relative to a plane extending through a central axis of the connector. Each shank drive key radial stop surface is adapted to angularly align with a corresponding head drive key radial stop surface.
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FIELD OF THE INVENTION
[0001] This invention relates to material handling equipment such as excavators, backhoes, and clamping and grappling equipment, and the like. More particularly it relates to a mounting for a tooth bar on a thumb assembly for use with such equipment.
BACKGROUND
[0002] The use of a thumb, with attached tooth bar, on excavator machinery is well known. Typically the thumb is used in conjunction with the excavator bucket so as to make the bucket more effective in picking up material. For example in demolition sites a thumb is a particularly useful means of grabbing material which would otherwise be difficult to be picked up solely by a bucket.
[0003] The thumb is typically pivotally mounted to the excavator arm and is controllable, by an hydraulic ram. The thumb has a tooth bar attached to its distal outer end, this tooth bar generally being configured to suit the particular type of bucket with which it is to be used. For example, the tooth bar may have four or six teeth depending on the number of teeth mounted to the edge of the bucket.
[0004] Because of the differing end user requirements it is often the case that the manufacturer of the thumb will manufacturer thumb assemblies particularly suited for the end application.
[0005] Consequently there is always a lead time between an end user ordering a thumb and it actually being delivered from the manufacturer.
[0006] Accordingly there is a need for a more modular system whereby the manufacturer can have a standard thumb sub-assembly and attach to this a suitable pre-manufactured tooth bar depending on the end users requirements.
[0007] Typically the tooth bar may be welded to the thumb, but with a more modular system it is more practical to have bolt on tooth bars. Bolt on tooth bars are already known, however those that are known generally suffer from draw backs - the main one being that they tend to work loose as a consequence of the forces, and sometimes extreme treatment, which the thumb experiences during normal use.
[0008] It is consequently an object of the present invention to provide a mounting for a tooth bar on a thumb which at least goes some way to overcoming the problem of loosening of the tooth bar during operation of the thumb, alternatively it is an object to at least provide the public with a useful choice.
SUMMARY OF THE INVENTION
[0009] Broadly according to one aspect of the invention there is provided a mounting for a tooth bar to a mounting surface of a thumb sub-assembly, the mounting including one or more inwardly narrowing slots located adjacent the mounting surface and into which a part of the mounting portion of the tooth bar can be wedgingly engaged, there being means for fixing the tooth bar into engagement with the mounting surface following the mounting portion being wedgingly engaged.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] In the following more detailed description of a preferred embodiment of the invention reference will be made to the accompanying drawings in which:
[0011] FIG. 1 illustrates an exploded perspective view of the components of a thumb sub-assembly and associated tooth bar which is mountable to the sub-assembly by the mounting according to the present invention,
[0012] FIG. 2 illustrates a perspective view of the thumb showing the tooth bar mounted to the thumb subassembly,
[0013] FIG. 3 illustrates a side elevation view of the thumb when mounted to an excavator arm, and
[0014] FIG. 4 illustrates a perspective view of the arrangement shown in FIG. 3 but with the thumb inter-engaging with the bucket as shown in dotted detail in FIG. 3 .
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0015] In the drawings FIGS. 1 and 2 show a tooth bar of a “universal” type. By way of further illustration, however, FIGS. 3 and 4 show a tooth bar having four teeth configured to inter-engage with the five teeth on the cutting edge of the excavator bucket. Other configurations of tooth bar can be mounted to the thumb assembly using the mounting of the present invention.
[0016] FIG. 1 shows the component parts of the thumb. This includes a thumb subassembly 10 and tooth bar 11 . The subassembly 10 has a mounting plate 12 which forms a mounting surface 12 a against which a plate 13 of the tooth bar 11 can engage and be bolted thereto by a series of bolts and associated nuts 14 .
[0017] The subassembly 10 includes a pair of side plates 15 which, in accordance with conventional construction, include along one edge thereof serrations or teeth 15 . At the ends of the side plates 15 opposite to mounting plate 12 are a pair of aligned openings 17 . Bushes 18 are provided for the openings 17 . Through the bushes 18 is engaged a pin 19 by which, together with selected spacers 20 , the subassembly 10 can be typically attached to the excavator arm E. To one end of the pin 19 is attached a radial extending plate 21 to which a retainer bar 22 is fitted.
[0018] Between the side plates 15 is a mounting plate 23 which, as more clearly shown in FIGS. 1 and 4 , carries flanges 24 having openings therein which align with openings in the side plates 15 and through which a thumb pin 25 can be engaged. This provides a mounting for the bush 26 of the piston rod of hydraulic ram 27 . The body of the hydraulic ram 27 has a bush 28 which is engaged in bracket 29 via pin 30 .
[0019] Attached to the mounting plate 13 of the tooth bar 11 is the teeth assembly 31 . This can include a plurality of teeth 32 (see FIG. 4 ) or in the more universal fitting of FIGS. 1 and 2 a toothed or serrated plate 33 .
[0020] The upper edge of the mounting plate 13 is preferably beveled as indicated by numeral 34 . The mounting plate 13 further includes a series, of openings which align with elongate openings 35 in the mounting plate 12 of the subassembly 10 . The bolts 14 pass through these aligned openings and with the associated nuts bolt the mounting plates 12 and 13 together.
[0021] The mounting according to the present invention includes a plurality of flanges 36 which, in the illustrated form, are a pair of parallel spaced apart flanges mounted to the mounting plate 23 . These flanges 36 are, in the illustrated form of the construction, located either side of an opening 37 formed in the mounting plate 23 .
[0022] Each of the mounting flanges 36 have a finger portion 37 which extends over the mounting surface of the mounting plate 12 . These fingers 37 include an edge surface 38 which faces towards the mounting surface 12 a and is configured such that the distance between the edge 38 and the mounting surface 12 a decreases inwardly from the distal ends of finger 37 . The result is a narrowing slot into which the beveled edge 34 can be engaged when the mounting plate 13 is bought into engagement with mounting plate 12 . There is thus a wedging action between the edge 38 /mounting surface 12 a and the mounting plate 13 of the tooth bar 11 .
[0023] Accordingly when the tooth bar 11 is mounted to the subassembly 10 the edge 34 is introduced between the edge surfaces 38 of the fingers 37 and the mounting surface 12 a . The tooth bar 11 is then driven into hard engagement with the fingers 37 so that the edge 34 is firmly wedged into position. This is shown in more detail in the enlarged part view in FIG. 3 . The bolts 14 are then introduced through the aligned openings 35 and the openings in the mounting plate 13 and the tooth bar thereby bolted onto the subassembly 10 . The elongate nature of the openings 35 ensure that the mounting plates 12 and 13 can be bolted together irrespective of the final position of the edge 34 between the fingers 37 and mounting plate 12 .
[0024] If, during use, the tooth bar 11 loosens it is simply a matter of loosening off the nuts/bolts 14 followed by a driving force applied to the tooth bar 11 so as to force the edge 34 further into wedging engagement between the mounting surface 12 a and the edge surfaces 38 and retightening the nuts on the bolts.
[0025] The present invention thus provides a mounting arrangement for a tooth bar such that the tooth bar 11 can be readily fitted onto the subassembly 10 and held firmly in place. The invention therefore lessens the likelihood of the tooth bar 11 working loose. Even though the forces to which the tooth bar will be subjected during normal use may still cause the tooth bar to loosen, the likelihood is less than with conventional mounting arrangements. If loosening does occur it is a matter of retightening in a simple and straightforward manner.
[0026] It will be appreciated by those skilled in the art that the present disclosure applies to an hydraulically controllable thumb. The invention is also applicable to a fixed/rigid thumb (i.e. one which is not hydraulically operable) where the clamping action with the fixed/rigid thumb is achieved by the crowd action of the bucket.
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A mounting for a tooth bar to a mounting surface of a thumb sub-assembly, the mounting including one or more inwardly narrowing slots located adjacent the mounting surface and into which a part of a mounting portion of the tooth bar can be wedgingly engaged, there being fixing means for fixing the tooth bar into engagement with the mounting surface following the mounting portion being wedgingly engaged.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. patent application Ser. No. 10/781,052, filed on Feb. 18, 2004 now U.S. Pat. No. 7,165,654.
FIELD OF THE INVENTION
The present invention relates generally to storage containers, and more particularly to a storage container having independently hinged sleeves for retaining drill bits.
BACKGROUND
Storage containers exist in many varieties and may be used to store, organize and transport various items such as fasteners, tool bits and other accessories. Plastic storage containers can be typically manufactured fairly inexpensively, but often at the expense of being less rigid and providing less flexibility in adapting the storage container to store items of various sizes. When a storage container is used to store tool accessories such as drill bits on a job site, it is desirable for the user to be able to quickly identify and access the drill bit of interest. Sometimes however, a large collection of drill bits of random size are staggered within a storage container such that identification and access is cumbersome.
Furthermore, storage containers that incorporate organizational schemes often present the drill bits in a structured pattern such that the user may easily identify the drill bit of interest but do not allow the user convenient access to remove or replace the drill bit from its holding arrangement. In addition, a storage case must be built to be strong and durable so that if it is moved quickly or dropped, it will not allow smaller drill bits to slide out of their respective holding arrangements.
SUMMARY OF THE INVENTION
A storage container for housing drill bits according to the present teachings can include a front housing portion and a rear housing portion. The front and rear housing portions can be pivotally connected through a hinge for moving between open and closed positions. The front and rear housing portions can define a body cavity therebetween in the closed position. A front bit holder can be pivotally connected to the hinge and lie adjacent to the front housing portion. A rear bit holder can be pivotally connected to the hinge and lie adjacent the rear housing portion. An intermediate bit holder can be pivotally connected to the hinge and lie between the front and rear bit holder.
According to additional features, the front bit holder can extend upward a first distance from a bottom of the body cavity. The rear bit holder can extend upward a second distance from the bottom of the body cavity. The second distance can be greater than the first distance. The intermediate bit holder can extend upward from a bottom of the body cavity a third distance. The third distance can be less than the second distance and greater than the first distance.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
FIG. 1 is a right perspective view of the storage container constructed in accordance to the present invention shown in the closed position;
FIG. 2 is a left perspective view of the storage container;
FIG. 3 is a plan view of the outer surface of the rear clam shell housing portion;
FIG. 4 is a left side view of the storage container illustrating the hinge connecting the front and rear clam shell housing portions;
FIG. 5 is a right side view of the storage container illustrating the latch for releasably engaging the front and rear clam shell housing portions;
FIG. 6 is a top view of the storage container;
FIG. 7 is a bottom view of the storage container;
FIG. 8 is a partial front perspective view of the storage container shown with the front cover removed for illustration;
FIG. 9 is a perspective view of the storage container shown in an open position;
FIG. 10A is a perspective view of a first metal sleeve of the storage container;
FIG. 10B is a perspective view of a first frame body portion of the storage container;
FIG. 11A is a perspective view of a second metal sleeve of the storage container;
FIG. 11B is a perspective view of a second frame body portion of the storage container;
FIG. 12A is a perspective view of a third metal sleeve of the storage container;
FIG. 12B is a perspective view of a third frame body portion of the storage container;
FIG. 13A is a partial cutaway view of the storage container illustrating a latch overextend prevention feature;
FIG. 13B is the cutaway view of FIG. 13A shown with the latch urged into an open position; and
FIG. 13C is the cutaway view of FIG. 13B shown with the storage container in a locked position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
With initial reference to FIGS. 1 and 2 , a bit container according to the present invention is illustrated and generally identified at reference 10 . The container 10 includes a front clam shell housing portion 12 and a rear clam shell housing portion 14 . The front clam shell housing portion 12 is connected to the rear clam shell housing portion 14 by a hinge pin 16 extending through hinge 17 . A latch 18 is connected to the front housing 12 and pivots to an engaged position to engage the rear housing portion 14 . With reference to FIGS. 8 and 9 , three page-like bit holders 19 A- 19 C are pivotally disposed within the container 10 . The page-like bit holders 19 A- 19 C generally include metal sleeves 20 A- 20 C which are each received within corresponding frame body portions 22 A- 22 C. The frame body portions 22 A- 22 C are formed as part of the hinge 17 . Each of the metal sleeves 20 A- 20 C include apertures 24 A- 24 C incorporated in the respective metal sleeves 20 A- 20 C for receiving various sized drill bits. The apertures may be configured to accept metric or English unit drill bits, or both. Preferably, the apertures 24 A- 24 C are arranged with increased diameter across each of the metal sleeves 20 A- 20 C for convenience and ease of identification. In addition, drill bit size indicators 26 are etched on both sides of the metal sleeves 20 A- 20 C (most clearly shown on FIGS. 8 and 9 ). The frame body portions 22 A- 22 C are pivotal relative to the front and rear clam shell housing portions 12 , 14 to allow the page-like bit holders 19 A- 19 C to be flipped like pages relative to the housing portions 12 , 14 .
With continued reference to FIGS. 1 and 2 and further reference to FIGS. 4-7 and 9 , the front housing portion 12 will be described in greater detail. The front housing portion 12 generally includes a front outer face 30 and a front inner face 32 having an optional viewing passage 36 incorporated therethrough. A diagonal strip 38 is disposed across the viewing passage 36 and incorporates a depth D (most clearly shown in FIG. 9 ) into an inner cavity of the container 10 . The diagonal strip 38 is arranged to align with the tips of a series of drill bits 40 A disposed in sleeve 20 A. In this way, the diagonal strip 38 precludes axial movement of the drill bits 40 A in sleeve 20 A from sliding toward a top surface 44 of the front housing portion 12 while the container is in a closed position or while in an open position with sleeve 20 A positioned against the front housing portion 12 . Viewing passage 36 may comprise an aperture, an aperture having a transparent panel fitted thereon or alternately the front outer face 30 of the front housing portion 12 may be solid to prevent viewing or otherwise access therethrough.
Front housing portion 12 is further defined by a peripheral side wall including a side latch face 46 ( FIG. 5 ), a side hinge face 48 ( FIG. 4 ), a bottom face 50 ( FIG. 7 ) and the top surface 44 . The side hinge face 48 (best illustrated in FIG. 4 ) includes cutouts 54 for accommodating hinge arms 60 A- 60 C of the hinge 17 , as will be described in greater detail. A groove 64 (best shown in FIG. 9 ) extends around an inner edge of the top surface 44 and the side hinge face 48 of the front housing portion 12 to cooperate with a complimentary lip 66 on the rear housing portion 14 in a closed position. The bottom face 50 of the front clam shell housing portion 12 incorporates an inset portion 70 , as illustrated in FIGS. 7 and 9 , for accommodating the frame body portions 22 A- 22 C while in a closed position. A ledge 68 provides vertical support for the page-like bit holders 19 A and 19 B when the container 10 is in a closed position. With reference to FIG. 4 , the side hinge face 48 of the front housing portion 12 includes hinge posts 71 separated by void portions 72 formed thereon for accommodating hinge posts 74 of the rear housing portion 14 .
The rear clam shell housing portion 14 is defined by a peripheral side wall extending from a rear face 76 ( FIG. 3 ). The peripheral side wall of the rear housing portion 14 includes a side latch face 80 ( FIG. 5 ), a top face 84 ( FIG. 6 ), a side hinge face 86 ( FIG. 4 ) and a bottom face 88 ( FIG. 7 ). The groove 66 ( FIG. 9 ) is formed on an inner edge of the top face 84 and the side latch face 80 of the rear housing portion 14 . Similar to the front housing portion 12 , the bottom face 88 of the rear housing portion 14 incorporates an inset 94 ( FIG. 7 ) for accommodating the frame body portions 22 A- 22 C while in a closed position. A ledge 69 provides vertical support for the page-like bit holders 19 B and 19 C when the container 10 is in a closed position. The side hinge face 86 of the rear housing portion 14 includes void portions 96 disposed between the hinge posts 74 for accommodating the hinge posts 71 of the front housing portion 12 .
With particular reference to FIGS. 3 , 8 , 9 and 13 A- 13 C, the latch 18 will be described in greater detail. A catch 90 extends from the side latch face 80 for catching a tooth 81 ( FIGS. 13A-13C ) incorporated on an underside of the latch 18 in an engaged position. First and second shoulders 98 extend on opposite ends of the latch 18 and function to prevent the latch 18 from over-rotating in an inward direction when the container 10 is in an open position. Specifically the shoulders 98 abut a wall 102 ( FIG. 13A ) formed on the front body portion 12 to preclude the latch 18 from becoming trapped between the front and rear housing portions 12 and 14 when a user rotates the front and rear housing portions 12 and 14 from an open position to a closed position. As the user rotates the rear housing portion 14 toward the front housing portion 12 , the surface to surface interaction of tooth 81 and the catch 90 influences the latch 18 counterclockwise as viewed from FIG. 13B . In particular, the front surface 82 of the tooth 81 is angled and/or otherwise configured so as to cause the tooth 81 to ride upward when contacted by the catch 90 , thus causing the counterclockwise rotation of the latch 18 . Once the front and the rear housing portion are touching ( FIG. 13C ), the tooth 81 of the latch 18 may be located into the locked position with the catch 90 .
The front and rear housing portions 12 , 14 are preferably comprised of hard plastic such as high impact ABS. As shown in the drawings ( FIGS. 1 and 2 ), various inset and outset portions 110 , 112 are incorporated on the side hinge faces 48 , 86 of the front and rear housing portions 12 , 14 for structural integrity. Furthermore, the inset portions 110 and the outset portions 112 are alternatively placed whereby an inset portion 110 of one of the front and rear housing portions 12 , 14 accepts an outset portion 112 of the other front and rear housing portion in an open position. The side latch faces 46 , 80 of the front and rear housing portions 12 , 14 incorporate indentations 114 thereon, to improve structural integrity and robustness. The hinge pin 16 is preferably comprised of durable metal having a smooth surface such as zinc plated steel. In addition, the hinge pin 16 may be coated with a clear chromate surface.
Turning now to FIGS. 4 and 7 - 9 , the metal sleeves 20 A- 20 C will be described in greater detail. The metal sleeves 20 A- 20 C are preferably arranged in increasing height from front to rear of the storage container 10 . Likewise, a series of smaller drill bits 40 A are received within the shorter front sleeve 20 A while a series of larger drill bits 40 C are received within the taller rear sleeve. This arrangement allows convenient viewing of the drill bits to properly identify the drill bit of interest. In addition, the hinged configuration of the metal sleeves 20 A- 20 C allows a user to index freely through the page-like bit holders 19 A- 19 C to gain adequate access to remove or insert a particular drill bit.
Each of the frame body portions 22 A- 22 C includes a pair of laterally offset hinge arms 120 A, 120 B, and 120 C, respectively so as to cooperatively interfit with the hinge 17 (see e.g. FIG. 4 ). Preferably one of the hinge arms 120 A cooperate with the hinge 17 at an area proximate to the bottom face 50 . Accordingly, the hinge arms 120 B are offset toward the top face 44 a predetermined distance from hinge arms 120 A and hinge arms 120 C are offset toward the top face 44 a predetermined distance from hinge arms 120 B. Such an alignment provides structural balance for the page-like bit holders 19 A- 19 C consistent with the increasing height from the page-like bit holders 19 A- 19 C. It is appreciated however that alternative hinge arrangements may be employed.
Each frame body portion 22 A- 22 C incorporates a stepped surface 126 A- 126 C thereon. The stepped arrangement provides increased structural integrity consistent with the aforementioned inset and outset portions 110 and 112 of the front and rear housing portion 10 , 12 . The side surfaces 130 A- 130 C of each of the frame body portions 22 A- 22 C include ridges 132 A- 132 C formed therealong. The ridges 132 A- 132 C provide an improved gripping surface to facilitate indexing through the page-like bit holders 19 A- 19 C.
The storage container 10 incorporates a variety of surfaces that allow the storage container to free-stand thereon. Specifically, the outset portions 112 (see e.g. FIG. 2 ) arranged on the hinge faces 48 and 86 present a favorable side plane having a sufficient footprint to rest thereon. Furthermore, protruding sections 116 are formed on the front and rear housing portions 12 and 14 (see e.g. FIG. 1 and 3 ) and cooperate with the lower faces of the stepped surfaces 126 A- 126 C incorporated on the bit holders 19 A- 19 C to present a common plane of which the storage container may free-stand thereon (see e.g. FIG. 9 ). In this way, the protruding sections 114 and the lower faces of the stepped surfaces 126 A- 126 C communicate with the common plane at a fully open position and a fully closed position and throughout all positions between providing a plurality of free standing conditions on the common plane.
With continued reference to FIG. 9 and further reference to FIGS. 10A-12C additional features of the page-like bit holders 19 will be described. Passages 140 A- 140 C ( FIGS. 10A , 11 A and 12 A) are incorporated in the metal sleeves 20 A- 20 C for receiving complementary teeth 142 A- 142 C disposed on the respective frame body portions 22 A- 22 C in an engaged position ( FIG. 9 ). The passages 140 A- 140 C and complementary teeth 142 A- 142 C provided on the metal sleeves 20 A- 20 C and frame body portions 22 A- 22 C are preferably configured to prohibit the metal sleeves from being placed backward or on the wrong frame body portion. In this way, the passages 140 A- 140 C are distinctly spaced on each of the frame body portions 22 A- 22 C and will only accommodate similarly spaced teeth 142 A- 142 C on the respective metal sleeves 20 A- 20 C.
Feet 148 A- 148 C extend from each respective frame body portion 22 A- 22 C in a lateral direction with respect to the ledges 68 and 69 of the front and rear housing portions 12 and 14 . The foot 148 A and a portion of the foot 148 B overlap the ledge 68 when the page-like bit holders 19 A and 19 B are rotated against the front inner face 32 of the front housing portion 12 . The ledge 68 disposed beneath the feet 148 A- 148 B inhibits downward vertical deflection of the page-like bit holders 19 A and 19 B thereby enhancing structural robustness and reducing stress on the hinge arms 120 A- 120 C in the event of dropping or otherwise jolting the container 10 . Similarly, the ledge 69 of the rear housing portion 14 laterally supports the foot 148 C and a portion of the foot 148 B to inhibit downward vertical deflection of the page-like bit holders 19 B and 19 C. It should be understood that the overlapping feet of the frame body portions of the page-like bit holders do not need to extend laterally from the bit holders, but instead can be formed in any manner to cause a portion of the bit holders to simply overlap the ledges 68 , 69 .
Radial support members 150 A- 150 C are formed along each of the frame body portions 22 A- 22 C. The radial support members 150 A- 150 C and the complementary apertures 24 A- 24 C in the metal sleeves 20 A- 20 C are collectively referred to as bit receiving portions. The radial support members 150 A- 150 C facilitate smooth insertion and retraction of the drill bits 40 A- 40 C by providing partial radial boundaries for the drill bits 40 A- 40 C. As shown in the drawings, the radial support members 150 B and 150 C of the frame body portions 22 B and 22 C occupy a partial circumferential boundary of the apertures 24 B and 24 C. Preferably, complimentary radial support members 150 A- 150 C are disposed at axially offset locations of the apertures and occupy an unbounded circumferential portion of the apertures. The axial offset of the radial support members 150 A- 150 C on opposite sides of the frame body portions 22 A- 22 C facilitate the molding of the frame body portions 22 A- 22 C.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
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A storage container for housing drill bits can include a front housing portion and a rear housing portion. The front and rear housing portions can be pivotally connected through a hinge for moving between open and closed positions. The front and rear housing portions can define a body cavity therebetween in the closed position. A front bit holder can be pivotally connected to the hinge and lie adjacent to the front housing portion. A rear bit holder can be pivotally connected to the hinge and lie adjacent the rear housing portion. An intermediate bit holder can be pivotally connected to the hinge and lie between the front and rear bit holder.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a control mechanism in a brush-honing machine to compensate for the wear of the brushes.
2. Prior Art
Brush-honing is a process to improve honed surfaces of borings or the like as described, for example, in European patent application EP-A1-0 247 572 (published Dec. 2, 1987). Actually, after honing, the honed surfaces are further treated with brushes under certain conditions to improve the quality of the surfaces by reducing burrs and grate-like sheet metal particles, which are generated and not removed in the preceding honing process.
Further, such brush-honing treatment may be used to provide the end treatment of borings in workpieces of certain aluminum alloys, especially silica containing aluminum alloys like AlSi 17 Cu 4 MG, in which relatively hard silicon crystals are embedded in a considerably softer aluminum matrix. If a boring in a workpiece of such a material, e.g. in a cylinder block for a combustion engine, is treated by brush-honing, the soft aluminum matrix will be somewhat moved around the harder silicon crystals, which will remain unaffected by this operation, such that thereafter the harder crystals project a little over the surface of the aluminum matrix . The projecting crystals will serve as bearing surfaces for any corresponding and/or cooperating other metal part, e.g. for the piston in an engine block. At the same time, the softer portions, of which some material has been removed, will serve as pockets for lubricating liquids. This treatment is applied especially to high-quality aluminum cylinder blocks for automobile engines, which, before such brush-honing method had been developed, were treated by a complicated etching process.
In connection with such a brush-honing operation, the brushes basically are applied in the same manner as honing tools are applied in the honing process, i.e. they are introduced into the boring and, while the free ends of the brushes or bristles respectively are pressed with some predetermined tension radially against the interior wall of the boring, they are rotated and at the same time moved upwardly and downwardly in the axial direction of the boring. The brushing then essentially follows the cross pattern, which has been produced in the honing process. Rotation may also be reversed when used in connection with the mentioned treatment of boring silicon containing alloys.
In order to maintain a certain predetermined tension of the free ends of the bristles of the brushes against the interior wall of the boring despite their wear, the tools, which carry the brush elements, can expand in the radial direction. The tension of the brush or bristles is usually measured by the amount with which the outer diameter of the brush is larger than the diameter of the boring of the workpiece. However, the counter pressure exerted by the wall of the boring on the bristles of the brush and on the tool is not strong enough to keep the brush at a position in which the tension of the brush or the bristles is exactly determined.
In other words, the adaption of conventional honing-machines for such brush-honing as are described in European patent application EP-A1-0 247 572, is rather difficult, since brush-honing can not rely on an exact position of a surface-to-surface-contact of the tool against the workpiece to define a predetermined tension of the brush or bristles respectively against the surface of the workpiece. Further, the rotational speed of the tool (up to 400 rpm) is much higher than with conventional honing, while the pressure of the tool against the workpiece surface is much less.
SUMMARY OF THE INVENTION
It is an object of the present invention to overcome this difficulty and to provide a control mechanism for a brush-honing tool, which can be adjusted in such a manner that a predetermined tension of the brush or the bristles can exactly be provided and corrected to compensate for any wear of the brushes.
A new control mechanism is proposed which effects the necessary reciprocal and radial movement of the brush-honing tool such that the noted predetermined tension is achieved.
The desired movement is achieved by the new control mechanism disclosed below by reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevational view, partly in cross section, of a preferred embodiment of the invention.
FIG. 2 illustrates the upper portion of the embodiment of FIG. 1 on an enlarged scale; and
FIG. 3 illustrates the lower portion of the embodiment of FIG. 1 on an enlarged scale.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the drawings, the tool 1, which basically is the same as that shown in EP-A1-0 247 572, comprises a number of brush elements 2, which are circumferentially distributed around the tool axis A. The brush elements 2 radially extend through slots in a cage-like holding member 90, which is connected to the tool body 25. The brush elements 2 comprise bristles, which have one of their ends fastened to metal strips 11. These strips are held together by springs 3, 4 (FIG. 3). Cam surfaces 5, 6 of the brush elements 2 are pressed against respective conical expanding members 7, 8, which form the forward end of a tool control bar 9 which extends in the axial direction of the tool 1. When the tool control bar 9 is moved downward in the axial direction, the brush elements 2 will be forced radially outwardly. If the control bar 9 moves in the upward direction, the brush elements 2 can move radially inwardly under the force of springs 3, 4. Also part of the tool control bar 9 is a cylindrical portion 12, which is provided with a groove 13 (FIG. 3), into which a bolt 14 extends for preventing the tool control bar 9 from rotation with respect to the tool body 25.
At its upper end, the tool control bar 9 is provided with an outer thread 15, which is received within an interior thread 16 of a hollow sleeve member 17. Once the hollow sleeve member 17 has a defined position in the axial direction, the extent, to which the tool control bar 9 is threaded into the sleeve member 17, will define a particular position of the conical extending members 7, 8 and thereby also of cam surfaces 5, 6. Thus, the exact length, to which the tool control bar 9 is threaded into the hollow sleeve member 17, defines the expansion state of the brush element 2 in the radial direction.
This particular position of the tool control bar 9 within the hollow sleeve member 17 is fixed by a screw 21 screwed into the interior thread 16 from above by inserting an appropriate tool into its socket 22. This socket 22 can be reached through the open upper end of sleeve member 17.
The sleeve member 17 is movably received within the tool body 25. Tool body 25 also basically has the form of a hollow sleeve. It is provided with an internal rim 26. Between this rim 26 and the tool body 25 there is provided an expansion spring 27, which presses the sleeve member 17 with its shoulder 28 against an abutment disc 29, which is secured by screws 30 to the tool body 25.
The unit comprising the tool control bar 9 and the sleeve member 17, can be pushed in the downward direction within the tool body 25 and relative to it against the force of spring 27 by a plunger rod 31, which rests against the upper front surface 17' of the sleeve 17. Such downward movement will expand the brush elements 2 in the radial direction, provided that the tool body 25 is axially held in place during this operation as explained below.
The means for rotating the tool comprises a spindle 35, which is rotated, as will be described later, by a motor 53. The spindle 35 receives the tool member 25 as follows: the tool member 25 has an outer trapezoidal thread 25', on which a sleeve 80 is positioned, which is provided with corresponding internal ' thread. On the other hand, the external thread 25' on the tool member 25 does not engage the internal surface of the spindle 35. The tool member 25 in this respect is able to be inserted freely in the interior boring of the spindle 35, while rotation therein is prevented by a leaf spring 91. The sleeve 80 will be brought manually by rotation in such a position that its upper face 81 abuts the lower face 35' of the spindle 35 in a position, in which the upper front surface 17' of sleeve 17 rests against the enlarged portion 48 of the plunger rod 31. This situation then is fixed by a clamping member 83. In the position shown, the inclined surface '83 of the clamping member 83 presses against a number of circumferentially distributed balls 84. These balls 84 are held in a cage (not shown for simplicity reasons) and together form a bearing; they rest in a corresponding groove 80' in the outer side of the sleeve 80. Thus, the sleeve 80 is locked to the clamping member 83. At the same time, the clamping member 83 is pressed upwardly by a spring 85, which with its one end abuts the rim 86 of the clamping member 83 and with its other end abuts flange 87 of spindle 35. The motion of the clamping member 83 in the axial direction is limited by a bolt 88, which is connected to the clamping member 83 and extends into a slot 89 in the spindle 35. By manually moving the clamping member 83 downward and thereby compressing the spring 85, the inclined surface 83' will move out of contact with balls 84 and thus allow them to expand radially outwardly out of the groove 80' and thereby release the sleeve 80 such that it can be pulled out of its engagement with the clamping member 83.
When the parts are in the position, as explained so far, then any downward movement of the plunger rod 31 will also move the sleeve 17 downwardly within the tool body 25, which is held in space to rest at the spindle 35 by the clamping member 83. This downward motion of sleeve 17 will expand the brush elements 2 as explained.
The plunger rod 31 is connected to a further plunger rod 46. The connection is made such that any downward motion of the rod 46 also will push the rod 31 in the downward direction. However, while the rod 46 does not rotate and only moves in the axial direction, the rod 31 can rotate with the tool 1, when it is with its enlarged portion 48, in contact with the upper face 17' of sleeve 17, which latter rotates with spindle 35.
For this purpose, the rod 46 is integrally provided with a bell-shaped coupling member 47, which extends around an enlarged portion 36 of rod 31. A combined needle and roller bearing 37 is provided such that rod 31 can rotate, while rod 46 can not and a downward pressure can be transmitted from rod 46 to rod 31.
To rotate the spindle 35, the spindle 35 carries a sprocket wheel 49. The connection between the spindle 35 and the sprocket wheel 49 is effected by a leaf spring 50 received in a groove of the spindle 35 and in a corresponding groove in the sprocket wheel 49. A similar sprocket wheel 51 is provided at the free end of a shaft 52, which is driven by the motor 53 and held by bearings 54, 55 within an arm structure generally indicated by 56. A belt 57 transmits the rotation from the shaft 52 to the spindle 35. The belt 57 also runs over an adjustable belt tensioning wheel 58. The machine arm structure 56 is moveable in the upward and downward direction along a machine support guiding element 100 by appropriate driving means. This is done in the usual manner as known from normal honing machines and thus needs not be described in greater detail.
The displacement of the plunger rod 46 is effected by a step motor 59. The end of driving shaft 60 of the step motor 59 is fixed by a press-fit to a driving sleeve 61, within which a boring 62 is provided. Boring 62 is internally provided with a thread 63. This boring 62 of sleeve 61 receives a threaded head 64 integrally connected to a shaft 65 and to plunger rod 46. At the same time a bolt 66 is provided close to the upper end of plunger rod 46 and extends therefrom to its right side. The projecting end 66' of bolt 66 is received within a longitudinal groove 67 connected to the machine arm structure 56 such that this bolt/groove-arrangement prevents the plunger rod 46 and head 64 from rotation. Thus, when the driving sleeve 61 is rotated by the step motor 59, this will result in a downward axial movement of rod 46. With this axial motion, the projecting end 66' of bolt 66 also moves in the axial direction. Its end positions will be detected by position sensing elements 68, 69. These might be of the magnetic type and suited to derive an appropriate electrical signal whenever the projecting end 66' is positioned exactly.
The operation of the machine is as follows:
When the tool 1 including tool body 25 is not yet positioned within the machine as shown, the tool control bar 9, with its threaded portion 15, will be screwed so far into sleeve 17 and fixed in this position by screw 21, that the ends of the bristles constituting brush elements 2 will define a predetermined outer brush diameter to be used in the brush-honing process. The tool body 25 then will be introduced into the spindle 35 until the end of sleeve 17 abuts the enlarged portion 48. This insertion is done while clamping member 83 is in the downward position. When it is released, it then will move upwardly and lock tool body 25 within spindle 35. When the motor 53 is energized, the spindle 35 together with tool 1 will rotate. While motor 53 rotates spindle 35, the frame arm structure 56 will be moved in the upward and downward direction between end points, which define the stroke of the brush honing operation and are determined by the size and position of the boring to be brush-honed. At certain intervals, which are determined from experience, to compensate the wear of the brushes and the corresponding decrease of tension of them against the surfaces of the workpieces, will be compensated by a certain angular motion of the step motor 59 resulting in a certain axial displacement of rods 46 and 31, which then by also displacing sleeve 17 within tool body 25 will effect a certain radial expansion of the brush elements 2.
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A brush-honing machine including a brush-honing tool which is displaceable both axially and rotationally thereby displacing a plurality of brush elements of the tool both axially and radially. A step motor is provided the angular movement of which is translated into the noted axial and radial displacement.
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BACKGROUND OF THE INVENTION
The present invention relates to fasteners in general, and, more in particular, to fasteners that lock when set and that develop a predetermined clamp-up load while being set.
Threaded fasteners consist of an internally threaded fastener or nut and an externally threaded fastener or bolt. The nut has internal threads that thread onto external threads of the bolt. Wrenching surfaces of the nut and bolt accept torque to form a joint where the fasteners hold one or more workpieces, often called sheets, tightly together. Another name for a bolt is a threaded pin, and a nut is sometimes referred to as a collar.
Many environments in which fasteners are used require that the fasteners have extremely high integrity and strength. Use in aircraft is an example of such an environment. Fasteners must often bear loads not only along their longitudinal axis, but radially of the axis. More particularly, when fasteners join together two or more sheets and the sheets are loaded in their planes with different loads, one sheet tends to slide over the other. Fasteners passing through both sheets become loaded in shear during their resistance to this type of loading. Axial loads arise by the clamping of fastened sheets between a head of the pin on one side of the sheets and the collar on the other side of the sheets.
Fasteners quite often must respond as well in environments where they are cyclically stressed under conditions that could give rise to fatigue failure. A fastener with adequate clamp-up load on it tends to resist fatigue failure.
An obviously desirable feature of a fastener is that it does not come apart in service. Various locking devices exist that keep nuts and bolts together. One deforms the thread of the nut so that it bears in radial compression against the thread of the pin. The resistance to unthreading in this lock is purely frictional. The thread is commonly deformed at the factory in preference to the field, but field deformation has also been practiced. This type of thread lock is known as a prevailing torque thread lock.
Knowledge of the clamping load the fastener applies to a structure is also desirable. Clamp-up load correlates to the resistance of a nut to further tightening onto a bolt and against the sheets. As a clamp-up force increases, the resistance to further tightening increases, and the torque required to turn the nut increases. This fact has been used in fasteners to develop a predetermined clamp-up load.
U.S. Pat. No. 4,260,005 to Edgar Stencel discloses a self-locking collar or nut that uses external lobes to accept a wrenching tool to tighten the nut on a cooperating bolt or pin. Once a predetermined axial load exists in the joint being made, the lobes plastically deform and wrenching can no longer take place. The lobes displace material radially inward of them into and across the thread or flutes of the cooperating bolt to produce a thread lock. The thread lock results from net material deforming into and across the pin flutes. When after lobe deformation material of the nut is in the flutes of the pin, a mechanical or interference, thread lock exists. Lobe deformation is a function of setting torque applied through the wrenching tool. The advantages of the Stencel nut include free running threads prior to the forming of a thread lock, a thread lock upon reaching preload, and accurate preload.
The three lobed nut described in the Stencel patent has constant thickness walls between the lobes. In some of these nuts, upon lobe deformation, the walls between the locations of the lobes displace radially outward while the walls in the vicinity of the lobes displace radially inward, changing the shape of the nut from generally cylindrical to triangular. This triangulation enhances the thread lock. The nuts are set by a driver, such as the one described in U.S. Pat. No. 4,742,735 to Edgar Stencel. This driver has a generally triangular or deltoid shape socket. The wall material of the nuts that displaces radially outward upon lobe failure tends to interfere with the walls of the driver. This interference makes the driver "stick" to the nuts, making release of the driver from the nuts difficult.
SUMMARY OF THE INVENTION
The present invention provides a unique locking nut, a fastener system of the nut and a bolt, and a process for their use.
The invention contemplates an improvement in the internally threaded fastener or nut disclosed in U.S. Pat. No. 4,260,005 to Stencel. The nut is used with an externally threaded fastener or pin. As described in the patent, the nut has at least one external lobe that provides purchase for a wrenching tool or driver with a deltoid socket that tightens the nut; upon reaching a predetermined preload, the lobe deforms, preventing further wrenching and forcing nut material radially inward to deform an internal thread of the nut into a locking relationship with a bolt or pin. The walls between the lobes have a reduced outer radius. Upon the deformation of the lobes, the reduced outer radius walls can still displace radially outward, but they are constrained by having a smaller radius and do not move enough to interfere with the walls of the deltoid driver. Because the nut does not interfere with the walls of the deltoid driver at the completion of a joint, the nut readily releases from the driver. The reduction in the outer radius can increase the amount of inward deformation of the nut at the lobes and increases the mechanical lock.
Preferably, an external taper on each wall of the nut between lobes provides the reduced outer radius and reduced wall thickness. The taper ends at an axial location within the axial span of the nut thread. The tapered wall satisfactorily reduces radial displacement of the wall and eliminates wall interference with the driver and the sticking of the nut to the driver. The tapered wall terminating in the threaded section of the nut avoids sticking, while maintaining high breakaway torque values. The tapered wall does not adversely affect tensile strength because most of the tensile load is picked up by the first few threads of the nut that are closest to the work, and the wall thickness of the nut at these threads is thick and its hoop strength correspondingly high, unaffected by the taper that ends above them.
Preferably, in addition to the tapered walls, the nut has a base with an outer radius larger than the maximum lobe radius. The lobes are on a barrel of the nut and stop before reaching the base so that a gap or relief exists between the lobes and the base. This gap frees the lobes from influence by the base and permits the lobes to deform independently of the base, increasing the accuracy of preload. During setting, a deltoid wrenching driver bears against the lobes with a radial component of force, a component of force in the direction of the axis of the nut. When the resistance to rotation of the nut increases to a predetermined level after the nut engages the surface of the work, the lobes yield in radial compression and displace nut material radially inward of the lobes into locking engagement with the bolt. When the lobes yield, barrel material in the zone of the lobes moves radially inward to contribute to the lock; with three lobes, the barrel triangulates, with the walls between lobes and adjacent to them displacing radially inward and the middle of such walls displacing radially outward.
In a presently preferred detailed embodiment of the invention, the nut has a barrel containing an internally threaded, right cylindrical bore and a base containing a larger diameter counterbore. A bolt or pin cooperates with the nut and can have a manufactured head or it can be a stud. A plurality of axially extending lobes, a convenient number is three, equally spaced lobes, on the outside of the barrel of the nut and radially outward of the nut thread are the lobes that fail in radial compression and cause the deformation that in a three lobed nut is the triangulation. A gap or relief separates the lobes from the base. The barrel walls between the lobes each has an outside taper diverging from the top of the barrel toward the base. The taper can end within the barrel at about the inner axial end of the lobes and run out in the gap or relief. The taper reduces the outer radius of the wall that it is in, with the radius getting larger progressively from the top of the nut. A driver has wrenching surfaces that bear against these lobes to thread the nut onto the bolt or pin, and then to fail the lobes in radial compression and displace material of the nut radially inward of the lobes against the bolt or pin. The geometrical relationship between the surface of the lobes and the wrenching surfaces is the same for each lobe so that each lobe and its backing material radially inside of it yield at the same applied torque. Void cavities or volumes on the bolt or pin, formed, for example, by flats or flutes, receive radially displaced material to form a thread lock. In many applications, just the displaced material against the bolt or pin thread provides a sufficient thread lock.
Features of the present invention include, an upper, radially extending surface just below the relief between the lobes and the base to cooperate with a complementary surface of the driver to pilot the driver. The fastener components can have desired corrosion inhibiting surfaces and lubrication. Chemical film corrosion inhibiting surface coatings, such as alodine, coupled with a suitable dry film lubricant overcoating, work well.
These and other features, aspects and advantages of the present invention will become more apparent from the following description, appended claims and drawings.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 is an elevational view of the preferred nut of the present invention with the right half being in section;
FIG. 2 is a top plan view of the nut of FIG. 1;
FIG. 3 is an elevational view of the fastener system of present invention that includes the nut of FIGS. 1 and 2 and a conventional pin, together with structure held together by the nut and pin;
FIG. 4 is a top plan view of the system shown in FIG. 3 from the nut end of the joint; and
FIG. 5 is a side elevational view of the structure shown in FIG. 3 after a joint has been effected and the lobes of the nut have been displaced radially inward.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows a locking nut 10. The nut has a base 12, a barrel 14, a locking section 16 of the barrel, a longitudinal axis 18, an internally threaded bore 20, and a counterbore 22.
Nut 10 also has three axially extending lobes 24. The lobes extend the axial length of the locking section and are integral with the nut. The lobes are spaced at 120° intervals around axis 18. The lobes also have right cylindrical curvature in radial planes. Each lobe has a starting chamfer 26 to center and align a driver used to set the nut. As seen in FIG. 2, each of the lobes has a major radius 28. This radius is greater than any other radius in locking section 16. The lobes determine the preload of a joint made with the nut because they fail at a predetermined preload, as described in U.S. Pat. No. 4,260,005 to Stencel, cited previously. The preload can be determined by the resistance of the locking section to deformation. One convenient way to adjust the value of preload is to adjust the length of the lobes and, consequently, the length of the wall between them.
Locking section 16 has walls 30 between the lobes. As seen best in FIG. 2, the thickness of these walls varies depending on location. The walls are also externally tapered at 31, as seen best in FIG. 3, with the taper diverging from a top 32 axially to the end of the locking section. The walls are thick adjacent the lobes and thin out to their thinnest midway between the lobes that border the particular wall being considered, as indicated by reference number 34 in FIG. 2. Because of the taper, the walls where they are tapered are at their thinnest at the top of the nut and get thicker away from the top. A radius 36 from axis 18 at top 32 to each of the thinnest sections is the shortest radius in the locking section. Radii at axial locations between the top and bottom of the locking section to the thinnest section of the wall at these locations get progressively longer towards the bottom of the locking section. In other words, the walls at their thinnest fall on a line of a right cylindrical cone. This thinning out of the walls reduces the outside radius of the walls, as can be seen in FIG. 2. The reduction in the outside radius keeps the final outer radius of the deformed walls at the setting of the nut small enough to eliminate the sticking problem. As seen best in FIG. 3, walls 30 outside of where they are tapered are of constant thickness and extend circumferentially further at axial locations progressing to the bottom of the locking section, as indicated by reference numeral 38. The walls increase in thickness as the tapers progress to their inner end, increasing the hoop strength of the walls.
Barrel 14 contains the thread of the nut. Lobes 24 and locking section 16 end at circumferential relief 40. A circumferential, frusto-conical, external shoulder 42 on the side of the relief opposite the lobes provides axial bearing for a cooperating surface of a wrenching tool or driver. This shoulder caps a lower section 44 of the barrel. The lower barrel section has the same radius wherever taken. This radius is about the same as the major radius of the lobes, but greater than the rest of the locking section. FIG. 2 shows this best. The thread has a run-in at the top of the barrel, adjacent top 32, that may have a narrower included angle than usual, 60° instead of 120°.
Base 12 and counterbore 22 function as they do in the prior art. The counterbore accepts imperfect thread run-out of a pin or bolt, makes it possible for the fastener to accommodate grip variations resulting from different thickness workpieces, and provides a nut that has lower unit loading on the sheets because axial preload is spread over a greater area.
Relief 40 uncouples the lobes from the base. The relief is at the internal axial end of the lobes and separates the lobes from nut material that would prevent the lobes from failing uniformly along their length. In the illustrated embodiment, the relief separates the lobes from the base. As pointed out in the "Background of the Invention" section of this specification, the accuracy of preload sometimes is affected by the base in the nut explicitly described in U.S. Pat. No. 4,260,005 to Stencel where the base and lobes connect directly. This union of the lobes with the base strengthens the lower portions of the lobes adjacent to the base; consequently, the lobes fail progressively with the top portion of the lobes failing before the bottom portions. This skews the wrenching surface of the lobes out of alignment with the axis of the nut, and creates a surface that tended to cam the driver off the nut, a surface at an angle to the axis of the nut. The relief eliminates this coupling and solves the problem of possible variation of preload because the nut material at the interior axial end of the lobes is not strengthened by the base.
The thread of the nut is standard. The run-in of the thread at the base end of the nut may begin as a transition from counterbore 22 to the thread in the manner of U.S. Pat. No. 4,842,466 to Rath and Wheeler. The nut material may be standard 7075 aluminum alloy, for example Grip accommodation may also be standard, say 1/16th of an inch. The number of lobes is preferably three, but need not be. Three lobes provide enough material for effective engagement by the wrenching tool that could be a problem with more lobes. Two lobes work, but increases the amount of material that must be plastically deformed for a given preload. The curvature of the outside surface of the lobes should be the same for all lobes and such that radial inward failure occurs, as opposed, for example, to circumferential.
With reference to FIG. 3, a fastener system in accordance with the present invention is shown. There, nut 10 is received on a male threaded fastener in the form of a threaded pin 48 of standard configuration except for axially extending flats 50 that extend axially in the thread of the pin and which provide space for the material of the lobes to enter to form a mechanical lock, in the manner described in the '005 Stencel patent. The number of flats relative to the number of lobes is such that all the lobes cannot line up between flats at lobe failure, and some of the material of at least one of the lobes can enter the flat to effect the mechanical lock. Presently, it is preferred to provide five flats in the pin with three lobes on the collar. As is standard, the pin has a hexagonal wrenching recess 50 at its threaded end, shown in FIG. 4, and a manufactured head 52.
In FIG. 3, the nut has been threaded onto the pin with the base of the nut bearing on an upper sheet 56 of a joint. The sheet cooperates with a lower sheet 58, manufactured head 54 of pin 48, and nut 10 to form the joint, the sheets being loaded in compression between the nut and the manufactured head of the pin. As wrenching progresses, the load on the lobes increases and eventually the lobes plastically fail in radial compression and move radially inward of the barrel, displacing material inside of the lobes against the thread of the pin and into the flutes to effect the lock.
As described in the Stencel '005 Patent, the lobes provide for wrenching the nut onto a cooperating pin by providing the purchase for a wrenching tool or driver, a generally deltoid shaped socket, for example, shown in U.S. Pat. No. 4,742,735 to Stencel. As wrenching progresses, resistance to wrenching increases, and this resistance correlates to the load the fastener applies on a joint. Eventually the load becomes high enough that the lobes and the walls between them plastically deform. The lobes, and the wall portion immediately adjacent to the lobes, move radially inward, while the wall portion between the lobes moves radially outward, creating a locking relationship with the cooperating pin.
The taper reduces the radius of the walls from what they would be if the walls were at the same radius as at the base of the lobes. The taper also reduces the strength of the walls over the strength that they would otherwise be. Accordingly, upon lobe failure the material of the nut at the lobes will move plastically radially inward to lock securely with the cooperating bolt or pin. In the typical case, inward deformed material will include the portions of walls 30 contiguous with the lobes. The walls more centrally between the lobes plastically deforms radially outward. Because the radius of the walls in these locations is smaller, the amount of radial movement will not be enough to cause the walls to interfere with the adjacent walls of the driver, and the nut will not stick to the driver. The amount of deformation reduces as the taper runs from the top of the nut to the end of the taper. The tensile strength of the joint is unaffected by the taper that runs out well before the nut thread convolutions that bear the greater tensile load of the joint.
A completed joint is shown in FIG. 5 with the lobes deformed. The joint in FIG. 5 has a preload correlated with the deformation of the lobes, a preload that can be closely controlled. The pin shown in FIG. 5 at 60 has a protruding head 62.
The present invention has been described with reference to a preferred embodiment. The spirit and scope of the appended claims should not, however, necessarily be limited to the description.
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Wrenching lobes of an internally threaded nut are separated by circumferential, tapered walls so that the lobes and contiguous portions of the walls deform in radial compression upon reaching a predetermined preload and displace radially inwardly while the central portions of the walls deform radially outwardly, but do not interfere with the tool that sets the nut.
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TECHNICAL FIELD
This invention relates to a rolling worker access platform facilitating servicing and repair of helicopters.
BACKGROUND OF THE INVENTION
The servicing and repair of helicopters requires a movable structure by which a servicing or repair person can obtain access to the part of the helicopter requiring service. The rotor for instance is one such area requiring inspection, servicing and repair. Stepladders could be used, however, they do not provide safe support nor do they permit sufficient lateral movement of the worker. The support structure for permitting a worker to service or repair a helicopter needs to be selectively mobile so that it can be manually moved into a rotor servicing position at either lateral side of the helicopter.
BRIEF DESCRIPTION OF THE INVENTION
A mobile worker access platform for servicing helicopter is provided which is light weight and easily positioned manually to service the helicopter. The support tower for a worker platform or floor is laterally narrower than the floor thereby providing an overhanging floor at both lateral sides of the platform. A pair of wheeled outriggers supporting the tower are spaced from one another far enough to straddle the landing gear or runners and extend beneath the fuselage of the helicopter. The tower structure between the outriggers is high enough to clear the runner supports. This construction permits the worker platform to be moved close to the helicopter with the floor extending over a side of the fuselage thereby placing the servicing person close to the rotor area. A convenient inclined stairway serves as part of the support tower for the floor of the platform and has a front outrigger secured thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the invention is illustrated in the drawings, in which:
FIG. 1 is a side view of a helicopter access platform and includes an outline of a helicopter with parts of the rotor and tail boom assembly broken away;
FIG. 2 is a top view of the helicopter access platform;
FIG. 3 is a front view of the helicopter access platform;
FIG. 4 is rear end view of the helicopter access platform positioned at the left side of the helicopter;
FIG. 5 is a rear view of the helicopter access platform positioned at the right side of the helicopter;
FIG. 6 is a section taken on the line VI—VI in FIG. 5;
FIG. 7 is a partial rear view of an outrigger;
FIG. 8 is a partial top view of an outrigger; and
FIG. 9 is a section taken along the line IX—IX in FIG. 2 .
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1 and 4, a helicopter access platform 11 is shown in a servicing position on the left hand side of a helicopter 12 which has a rotor 13 on a vertical rotor shaft 14 and a fuselage 16 supported on a pair of parallel laterally spaced ground engageable runners 17 , 18 . The fuselage 16 is low to the ground and may have as little as 3 decimeters of clearance. In order to service the rotor area of the helicopter 12 the platform 11 is provided with an elevated quadrilateral floor 19 supported on a support tower 21 which includes four vertical support columns 22 , 23 , 24 , 26 having upper ends secured in supporting relation to the floor 19 . The lower ends of the columns 22 , 23 are secured as by welding to a fore and aft extending horizontal beam 31 and the lower ends of columns 24 , 26 are secured as by welding to a fore and aft extending horizontal beam 32 which is parallel to beam 31 . Cross braces 36 , 37 having upper ends welded to the left side of the floor 19 , as viewed in FIG. 3, and have lower ends welded to the beam 31 . Similarly positioned cross braces, not shown, are welded to the right side of the floor 19 and the beam 32 . As viewed in FIGS. 4 and 5 cross braces 38 , 39 have their upper ends welded to the floor and their lower ends welded to a cross brace 41 , the opposite ends of which are welded to the beams 31 , 32 . As shown in FIGS. 3, 4 and 5 the floor 19 extends laterally beyond the support columns 22 , 23 , 24 , 26 .
As shown in FIGS. 1, 2 and 3 the support tower 21 includes an inclined stairway 43 formed by a pair of parallel stair joints 44 , 46 and a plurality of steps 47 , the opposite ends of which are welded to the joists 44 , 46 . The upper ends of the stair joists 44 , 46 are welded respectively, to the upper ends of the columns 22 , 24 and to the front side of the floor 19 . The joists 44 , 46 have the same lateral spacing as the columns 22 , 24 , the columns 23 , 26 and the support beams 31 , 32 . Thus the joist 44 , the beam 31 and the columns 22 , 23 are coplanar. Likewise the joist 43 , the beam 32 and the columns 24 , 26 are coplanar. The front ends of the support beams 31 , 32 terminate at an angle which corresponds to the incline of the stairway joists 44 , 46 thereby facilitating welding the front ends of the beams 31 , 32 to the underside of the joists 44 , 46 .
As illustrated in FIGS. 1, 2 , 3 , 4 and 5 , a guard railing is provided for the floor 19 which includes posts 51 , 52 , 53 , 54 56 and rails 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 . A gateway opening is provided between railing posts 52 , 53 and a similar gateway opening is provided on the right hand side of the access platform 11 , as viewed in FIG. 4 . Toe guard panels the height of oxford shoes provided around the perimeter of the floor 19 except for the stairway opening between the railing posts 57 , 58 . A toe guard panel 71 has its opposite ends welded to railing posts 51 , 52 . A toe guard panel 72 has its opposite ends welded to railing posts 53 , 54 . A toe guard panel 73 has its opposite ends welded to railing posts 56 , 57 and a toe guard panel 74 has its opposite ends welded to rail posts 58 , 51 . In a like manner a toe guard panel, not shown is provided between the railing post 56 and a post at the front side of the gateway on the right hand side of the access platform. A pair of gates 76 , 77 , similar in construction, are provided for the left and right gateways in the safety railing. The gate 76 is pivotally connected to the railing post 53 on a vertical pivot axis 78 and the gate 77 is pivotally connected to the railing post 54 on a vertical axis 79 . Both gates 76 , 77 open only in a laterally inward direction. Broken lines 81 in FIG. 2 show gate 76 in a slightly open position and broken lines 82 show gate 77 in a slightly open position. Each of the gates 76 , 77 can be separately opened 90 degrees to where it is parallel to guard rail 63 at the rear of the floor 19 . The gates 76 , 77 may be opened when the access platform is placed for servicing the helicopter 12 thereby giving the servicing person better access to the areas requiring service. Or the servicing person may step out onto the fuselage 16 if necessary. Tabs 83 , 84 are provided on the gates to prevent them from being opened laterally outwardly. Each of the gates is provided with a toe guard panel. As shown in FIG. 1 a toe guard panel 86 is secured to the lower ends of vertical connectors 87 , 88 which have their upper ends welded to a U-shaped component 89 of the gate 76 .
The access platform 11 is supported at its front and rear by a pair of low to the ground wheeled outriggers 91 , 92 . The rear outrigger 92 is rigidly connected to the beams 31 , 32 by studs 93 , 94 and the front outrigger 91 is rigidly connected to the second step 47 , from the bottom of the stairway, by short studs 96 , 97 , as shown in FIGS. 3 and 9.
As shown in FIGS. 1, 2 , 3 , 4 , 5 , 6 , 7 , and 8 the rear outrigger 92 includes a T-shaped transverse horizontal truss 101 formed by welding a hollow upper tube 102 of rectangular section to a rectangular section hollow lower tube 103 as illustrated FIGS. 6 and 7. The tube 102 is approximately twice as wide as it is high and the tube 103 is approximately three times as high as it is wide. As shown in FIGS. 7 and 8, a channel member 106 has a vertical flange welded to the lateral end of the tube 103 and has a horizontal flange to which a wheeled swivel caster 107 is secured by releaseable fasteners in the form of four threaded studs 108 and nuts 109 . A small vertical plate 11 is welded to the tubes 102 , 103 and the channel member 106 and a gusset 112 is welded to the plate 111 and to the horizontal flange of the channel member 106 . A wheeled swivel caster 113 is mounted on a channel member 114 at the other end of the T-shaped section of the outrigger 101 in a reverse image manner. The wheels of the casters 107 , 113 make contact with a support surface 117 at points approximately vertically beneath the laterally opposite edges of the floor 19 .
As shown in FIGS. 3 and 9, the outrigger 91 at the front of the access platform is similar in construction to the rear outrigger 92 and has a T section truss 121 to which a pair of channel members 122 , 123 are welded. A pair of wheeled swivel casters 126 , 127 are mounted on the channel members 112 , 123 and positioned vertically below the lateral edges of the floor 119 . The swivel casters 126 , 127 have manually lockage wheels to prevent movement of the access platform 11 when in a helicopter servicing position as shown in FIGS. 1, 4 and 5 . The wheels of the swivel casters 107 , 113 may also be selectively lockable.
The front to rear spacing of the outriggers 91 , 92 is greater than the length of the runners 17 , 18 so as to permit them to straddle the runner at either side of the helicopter thereby permitting the floor 19 of the access platform to be positioned close to the helicopter. The support beams 31 , 32 are at a sufficient elevation to define an underside opening high enough to clear the runner or undercarriage support members 128 , 129 . As shown in FIGS. 4 and 5 the floor 19 extends laterally beyond the support tower 21 at a height above the fuselage 16 of the helicopter. The overhang of the floor 19 permits the service personnel close access to the rotor area which requires critical, accurate inspection and servicing. As shown in FIGS. 4 and 5 the outriggers 91 , 92 extend laterally beneath the fuselage 16 to the same extent as the floor 19 extends laterally over the fuselage 16 .
As illustrated in FIGS. 1, 2 , 3 , 4 , and 5 , bumper pads 131 , 132 of resilient cushioning material are secured to the laterally opposite sides of the floor 19 and similar pads 113 , 134 , 136 , 137 are secured to the columns 22 , 23 , 24 , 26 . The pads are designed and provided to prevent damage to the fuselage of the helicopter.
Practical Application
Helicopters require careful diligent servicing to insure efficient, safe operation. Servicing the rotor area of the helicopter is critical to functional operation of the helicopter. The herein disclosed access platform provides a stable floor positioned over the fuselage and close to the rotor area. The access platform is symmetrical, permitting it to be placed at either side of the helicopter. The support tower 21 for the floor 19 includes four columns 22 , 23 , 24 and 26 mounted on a pair of parallel longitudinally extending beams 31 , 32 which have their front ends connected to an inclined stairway 43 whose upper end is secured to the floor 19 . Thus the stairway serves as a fore and aft structural brace in the floor support tower 21 . By aligning the columns 22 , 23 , the beam 31 , the stringer 44 and the stud 93 in a coplanar manner and by aligning the posts 24 , 26 , the stringer 43 , the beam 32 and the stud 93 in a coplanar manner, efficient use of materials is achieved thereby reducing weight and cost while maximizing rigidity and strength. The stairway provides a convenient support for the front outrigger 91 with a minimum amount of connecting framework. The columns, the beams, the studs, the T section members of the outrigger and the stairway are made of aluminum tubes which provide strength and low weight. The wheeled access platform is sufficiently light to permit it to be moved into and out of a servicing position by one or two servicing personnel. Its light weight enhances its air transportability which is important when the helicopters are moved to new bases of operation. The toe guard panels around the floor and the inward only swinging gates contribute to the safety of the helicopter servicing activity.
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A mobile worker platform providing access to the rotor area of a helicopter having outriggers spaced to straddle the helicopter landing gear.
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STATEMENT OF GOVERNMENT INTEREST
The inventions described herein may be manufactured, used and licensed by or for the United States Government.
BACKGROUND OF THE INVENTION
The invention relates to press-loading energetic material into warhead projectiles.
A conventional press-loading process for a projectile uses multiple increments of powder to achieve specified quality requirements. Warhead projectiles typically are shaped with a length-to-diameter (l/d) ratio that balances ballistics and payload. When press-loading projectiles with larger l/d ratios, quality and performance issues arise due to an inherent inefficiency in pressing long charges of powder. It is known that friction forces, both inter-particle and wall-boundary, are quality factors that must be minimized during the press-loading process. Otherwise, the pressed charge will have a density gradient marked by significant degradation along its central axis and further from the press punch. Consequently, long powder charges cannot be pressed to meet density and mass specifications. The conventional pressing process relies on multiple pressed increments of powder to reduce the l/d ratio to a manageable amount.
Conventional load procedures typically require that multiple increments of powder or pre-consolidated pellets are loaded and compacted individually. For example, for a cylindrical die, efficient consolidation of energetic material is only achieved if the punch diameter is equal to or greater than the length of the container (l/d less than 1). Thus, in the conventional process, the powder is poured and pressed incrementally. Inefficient cohesion between subsequent compacted layers and sharp corners left behind upon withdrawal of the punch may cause the layers to crack and de-laminate internally. Poorly bonded layers and low-density areas manifest themselves as transverse cracks and internal voids. When a warhead is launched, the case is propelled forward while the energetic fill is forced against the back of the case under its own momentum. This phase, referred to as setback acceleration, harbors severe risk of unintended initiation as any transverse cracks in the energetic material may close violently. Conversely, with particularly insensitive compositions, a warhead may not reliably initiate if a detonation wave cannot cross these large transverse voids.
To obtain consistent quality through the entire length of a column of energetic material, each pressed increment requires a complete cycling of all the pressing steps and parameters including loading, vacuum dwell, pressure dwell, pressure cycling, and unloading. Generally, the use of fewer increments reduces the total cycle time but decreases the overall quality. A balanced process can be achieved, but throughput in a production setting is always choked by incremental press-loading.
A need exists for a faster method of press-loading energetic material that results in consistently high quality throughout the column of energetic material.
SUMMARY OF INVENTION
One aspect of the invention is a method of filling a projectile case with energetic material. The method includes providing the energetic material in a powder form. A column of the powder is isostatically pressed to create a pre-formed billet (PFB). The PFB is placed in the projectile case and pressed in the projectile case. The projectile case is filled using only one PFB.
The method may include placing the PFB in a projectile case having an l/d ratio greater than or equal to one.
The step of isostatically pressing may include only pressing the column of powder radially and not pressing the column axially.
The step of isostatically pressing may include pressing a mold in which the column of powder is disposed.
The invention will be better understood, and further objects, features and advantages of the invention will become more apparent from the following description, taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, which are not necessarily to scale, like or corresponding parts are denoted by like or corresponding reference numerals.
FIG. 1 is a schematic of one embodiment of an isostatic pressing tool with a column of powder to be pressed.
FIG. 2 is a schematic of the isostatic pressing tool of FIG. 1 after the column of powder has been pressed.
FIG. 3 is a schematic of one embodiment of a pre-formed billet disposed in a projectile case.
FIG. 4 is a schematic of one embodiment of a conventional press with a pre-formed billet prior to pressing in a projectile case.
FIG. 5 is a schematic of the press of FIG. 4 after the pre-formed billet has been pressed into the projectile case.
FIG. 6 is a schematic view of a finished warhead.
DETAILED DESCRIPTION
A novel method of loading energetic material in a warhead enables filling a projectile having a large l/d ratio with only a single increment of energetic material, while maintaining high quality. The method may be used to compact powders into long, closed containers, such as the warhead of a rocket or projectile.
The process relies on the use of pre-formed billets (PFBs) produced by isostatic pressing. Isostatic pressing is a technique that uses hydraulic fluid contained within a pressure vessel to generate uniform forces on a powder-filled flexible container. The flexible container is called bag tooling. In traditional isostatic presses, the bag tooling is submerged in hydraulic fluid within a pressure vessel. In newer isostatic presses, hydraulic fluid does not contact the mold directly. This method is known in industry as dry-bag isostatic pressing. Consolidation forces are applied radially to the mold. The radially applied forces compact the mold and the energetic powder uniformly along the central longitudinal axis. The compaction of the powder volume reduces its cross-sectional area in proportion to the square of the radius of the area. Isostatic pressing is an efficient method of applying compaction forces uniformly upon all exposed surfaces.
FIG. 1 is a schematic of an isostatic pressing tool 10 with a column 12 of powder to be pressed. The powder may be energetic material. Pressing tool 10 includes a fixed lid 14 and a base plate 16 . A spacer 18 and a pressure plug 20 are disposed beneath base plate 16 . A cap 24 is disposed beneath the fixed lid 14 . The powder column 12 is disposed in bag tooling, for example, a low durometer polyurethane mold 22 . The interior walls of the pressure vessel (not shown) are an oil-filled bladder which applies force to the mold 22 without exposing the mold 22 to the oil. Isolating the oil from the mold 22 simplifies loading and extraction of the mold 22 and enables easier automation of the isostatic pressing process.
FIG. 2 is a schematic of the isostatic pressing tool 10 after the column 12 of powder has been pressed and transformed into a pre-formed billet (PFB) 26 . In FIG. 2 , the arrows A represent the isostatic pressure applied to the mold 22 by hydraulic fluid. As the hydraulic fluid pressure increases, the mold 22 transfers the pressure to the powder column 12 . The isostatic pressing process reduces the diameter D of the powder column 12 by, for example, about 33%, while the length L of the column 12 is unchanged. Base plate 16 and lid 14 are fixed in place to constrain axial flow of the powder in column 12 .
The finished PFB 26 is strong, flat on one end, fairly straight along its central axis, and has a rough finish. The mold 22 , base plate 16 and cap 24 can be designed to form a variety of shapes and features needed for press loading. The shapes and features may include, for example, ogives, domes, shoulders, bellies, etc.
In the isostatic pressing process, the pressure, temperature, vacuum level and dwell time may be controlled parameters. Pressing the PFB 26 isostatically may require known tooling made of polyurethane and metal. Because the PFB 26 is isostatically pressed on its radius, there are no density gradients along the central longitudinal axis (along the length L). PFBs 26 of almost any l/d ratio can be isostatically pressed without degrading the density consistency needed for warheads.
Once a PFB 26 has been isostatically pressed, it can be immediately loaded into a waiting projectile case 28 ( FIG. 3 ) for final press-loading or, it can be moved into raw material inventory for future press loading. Either way, the PFB 26 is the single increment charge necessary to implement the remainder of the warhead loading process.
After the PFB 26 is isostatically pressed, conventional press tooling and platforms may be used to deform the PFB 26 inside a projectile case 28 . Depending on the projectile case strength, the mechanical properties of the energetic material, and the pressing parameters, the press tooling can be designed to meet safety regulations and quality standards. In addition to the pressing parameters controlled in the isostatic pressing process, ram position may also be controlled when pressing the PFB 26 in the projectile case 28 .
Well-characterized energetic material properties provide a reliable basis for developing mathematical models for predicting behavior of the column 12 of energetic material under consolidation stress. Stress fields and density mapping shown through finite element analysis (FFA) can provide insights to tooling design and press process development (time, temperature, pressure). The PFB 26 will deform under relatively low force. To fill corners of a projectile case 28 with energetic material and to raise the fill-density to near theoretical maximums, greater pressing forces may be required.
Prior to pressing the PFB 26 into an empty projectile case 28 , the projectile case 28 is aligned and supported by tooling so that the projectile case 28 remains fully constrained during the pressing step. The PFB 26 may be pressed to a density of, for example, about 95% of the theoretical maximum density so that the energetic material readily deforms and flows in the projectile case void. Once the energetic material begins to flow and fills the void, its density begins to rise as the pressure increases. The deformation of the PFB 26 within the consolidation zone in the projectile case 28 is radially outward toward the case wall. The radially outward deformation minimizes wall friction and counter forces applied to the advancing press punch.
FIG. 4 is a schematic of one embodiment of a conventional press 30 with a pre-formed billet 26 prior to pressing in a projectile case 28 . Press 30 includes a ram 32 , a forming punch 34 , a support die 36 , a support tooling 38 and a loading sleeve 40 . In this case, the PFB 26 is greater than two times the length of the void to be filled. Support tooling 38 provides alignment and support of the projectile case 28 under extreme loading forces. Forming tools such as forming punch 34 may be useful to produce desired features in the pressed charge. FIG. 5 shows the press 30 after the PFB 26 has been compacted into a pressed charge 42 in projectile case 28 . FIG. 6 shows the finished warhead 44 with projectile case 28 and pressed charge 42 .
The novel process has several advantages over conventional incremental powder pressing. Because only one compacted increment is loaded and pressed, the final product has no transverse cracks. A single PFB 26 can be used to press-load longer projectiles than can be pressed with prior art processes. The production time is faster. The novel process can integrate easily into conventional pressing platforms.
While the invention has been described with reference to certain embodiments, numerous changes, alterations and modifications to the described embodiments are possible without departing from the spirit and scope of the invention as defined in the appended claims, and equivalents thereof
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A method of filling a projectile case with energetic material includes isostatically pressing a column of the powder to create a pre-formed billet (PFB). The single PFB is placed in and then pressed into the projectile case to create the finished warhead. The single PFB effectively fills a projectile case having a large l/d ratio. The single PFB eliminates the problems and poor quality associated with pressing multiple increments in a projectile case.
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BACKGROUND AND SUMMARY OF THE INVENTION
[0001] The present invention relates to a process for producing a joint inner part for a constant-velocity rotary joint with a plurality of circumferentially distributed ball raceways for accommodating torque-transmitting balls, and to a suitable tool for carrying out this process.
[0002] German document DE 35 08 487 C2 has disclosed discloses various processes for producing joint inner parts for constant-velocity rotary joints: it joints. It is known in particular to produce a joint inner part blank by casting or forging and then to introduce the ball raceways into the joint inner part blank in the cold, semi-hot or hot state by grinding, chip-forming machining or deformation. If an accurately specified form of the ball raceway is to be achieved, it is customary for the approximate contours of the ball raceways to be formed into the joint inner part blank by cold-working or forging and then for the desired highly accurate shape of the ball raceways to be produced by chip-forming machining, in particular grinding. Grinding entails high levels of tool wear, and consequently grinding-relief sections which are intended to relieve the grinding forces are provided in the raceways. The introduction of these grinding-relief sections entails increased machining outlay; furthermore, grinding is a relatively time-consuming process.
[0003] The One object of the invention is based on the object of providing a process which allows the ball raceways to be introduced into joint inner parts with a high level of accuracy and within a significantly shorter time than has been the case with conventional processes. Furthermore, Another object of the invention is based on the object of providing a tool for carrying out this process.
[0004] According to the invention, the object is achieved by the features of claims 1 and 2 .
[0005] Accordingly, the ball raceways are introduced into the joint inner part by means of cylindrical milling. Cylindrical milling per se is a known process, which has hitherto been used in particular to produce grooves (as described for example in German document DE 295 11 482 U1) or to machine crankshaft bearings (as described for example in German document DE 198 01 862).
[0006] The main cylindrical milling variable which determines time and therefore productivity is the advance rate v f . It is dependent, in accordance with the formula
v f = f z × z × v c π × d Wz ( I )
(source: Degner, Lutze, Smejkal: “Spanende Formung” [Chip-forming shaping], Carl Hanser Verlag Munich 1993), on the tooth advance f z , the number of teeth z, the cutting velocity v c and the tool diameter d Wz . To achieve maximum productivity, the smallest possible tool diameter d Wz should be the objective for a given tooth advance f z and a given number of teeth z. In the past, it has only been possible to achieve low advance rates v f and low levels of accuracy, and consequently cylindrical milling has never hitherto been considered a suitable process for the production of raceways in constant-velocity rotary joints.
[0007] According to the invention, it is proposed that cylindrical milling be used to produce raceways in constant-velocity rotary joints. The invention is based on the consideration that in the meantime new cutting materials (in particular hard metals) have become available at economically acceptable prices. Using milling cutters made from cutting materials of this type, it is possible, in accordance with formula (I), to achieve high advance rates v f even with small milling cutter diameters d Wz , in particular if a large number z of milling teeth are provided on the circumference of the milling cutter. The advantages of the small tool diameter d Wz reside in the high tool stability (low axial deformation and susceptibility to vibration), the low torque loading on the main spindle and, finally, a significantly lower price. Furthermore, in recent years high-performance CNC machine tools have been developed, which are suitable for the production of complex geometries.
[0008] Therefore, if a tool made from a high-performance material (preferably a hard metal with a hard material coating, cf. claim 7 )coating) and a large number z of milling teeth along the circumference of the cylindrical milling cutter is used, it is possible to achieve the object of forming ball raceways quickly, highly accurately and at low cost into a joint inner part of a constant-velocity rotary joint in a surprisingly simple way by using cylindrical milling. The support reaction forces can be determined and compensated for by measuring the cutting forces during the cylindrical milling, so that it is possible to satisfy the high demands on accuracy imposed on ball raceways on joint parts. Furthermore, the high material-removal rate makes it possible to achieve a short machining time and therefore a high productivity.
[0009] A tool which comprises a milling body in disk form with milling teeth arranged on the circumferential surface, with the quotient formed from the number of milling teeth and the diameter of the milling body being greater than 0.25 tooth/mm cf. claim 2 ) , tooth/mm, is used to carry out the process according to the invention. As described above, this makes it possible to achieve high advance rates v f for the tool with respect to the joint inner part and therefore very short machining times.
[0010] The cylindrical form milling of the ball raceways of the constant-velocity rotary joint may be a two-stage process comprising a roughing step and a finishing step. These two process steps can be combined in a particularly advantageous, time-saving way if the roughing milling tool is mounted together with the finishing milling tool on the same tool spindle (cf. claim 3 ). spindle. In this case, the process kinematics can be selected in such a way that the machine non-productive time required for the return movement of the roughing tool is used for the finishing process. This allows the cycle time to be considerably shortened. It is preferable for the number of teeth on the roughing tool and finishing tool to be equal (cf. claim 4 ). equal. Alternatively, it is possible to use a single milling tool which carries out a roughing action in the advancing movement and a finishing action in the return movement.
[0011] Using the process according to the invention, it is possible to introduce the ball raceways into a previously unmachined blank. To ensure that the wide chips which are produced during the roughing operation are transported out of the relatively small chip space of the roughing tool, the roughing tool is expediently provided with chip-divider grooves (cf. claim 5 ). grooves. The chip-divider grooves break the wide chips into short chip segments, preventing the chips from becoming jammed in the chip space of the tool.
[0012] On account of the large number of milling teeth based on the milling body diameter, the chip space available on the milling tool for removal of the milling chips is very small. Experience has shown that the chips produced can nevertheless be removed reliably from the process if the milling teeth are arranged at a rake angle of preferably between 5 and 12 degrees (cf. claim 6 ) degrees.
[0013] The text which follows provides a more detailed explanation of the invention on the basis of an exemplary embodiment illustrated in the drawings, in which: drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 a shows a joint inner part of a rotary joint;
[0015] FIG. 1 b shows a blank used to produce the joint inner part shown in FIG. 1 a;
[0016] FIG. 2 a illustrates the roughing of the joint inner part blank;
[0017] FIG. 2 b illustrates the finishing of the joint inner part blank; and
[0018] FIG. 3 shows a side view of the tool illustrated in FIG. 2 a.
DETAILED DESCRIPTION OF THE INVENTION
[0019] FIG. 1 a shows a joint inner part 1 of a constant-velocity rotary joint which has been produced from a joint inner part blank 1 ′ ( FIG. 1 b ). The joint inner part 1 has, on its outer circumferential surface 2 , a plurality of ball raceways 3 , in which, in the assembled state of the joint inner part 1 with a joint outer part (not shown in FIG. 1 a ), torque-transmitting balls are accommodated. The ball raceways 3 extend substantially in the longitudinal direction of the joint inner part 1 ; in the example shown in FIG. 1 a , the ball raceways 3 are arranged parallel to the axis of symmetry 4 of the joint inner part 1 ; with these geometries, the raceway shape is curved. In other forms of rotary joints, the ball raceway 3 is tilted through an angle of inclination 5 with respect to the axis of symmetry 4 of the joint inner part 1 (cf. FIGS. 2 a and 2 b ).
[0020] FIG. 2 a shows a milling tool 6 for producing the ball raceways 3 on the joint inner part blank 1 ′ shown in FIG. 1 b . The milling tool 6 comprises two cylindrical milling cutters 7 , 7 ′, a roughing cutter 7 and a finishing cutter 7 ′, which are jointly arranged on a rotary spindle 9 , axially offset from one another by a distance 8 . The two milling cutters 7 , 7 ′ have a diameter 21 , 21 ′. As can be seen from the side view presented in FIG. 3 , each milling cutter 7 , 7 ′ has a multiplicity of milling teeth 11 , 11 ′ on its circumferential surface 10 , 10 ′; the cutting contour 12 , 12 ′ is calculated from the shape of the ball raceway 3 to be produced. In addition to the straight-toothed milling cutters 7 , 7 ′ shown in FIGS. 2 a and 2 b , it is also possible to use obliquely toothed milling cutters.
[0021] The milling teeth 11 of the roughing cutter 7 are provided with chip-divider grooves 13 in order to ensure that the chips are transported out of the chip space of the roughing cutter 7 during the roughing process. Since the chips produced during the finishing operation are much smaller, there is no need for chip dividers to be present at the milling teeth 11 ′ of the finishing cutter 7 ′.
[0022] In the present exemplary embodiment, the roughing cutter 7 and finishing cutter 7 ′ are each of single-part design. Both milling cutters 7 , 7 ′ are solid hard-metal tools provided with a hard material coating (e.g. with a TiAlN multilayer coating). The joint inner part blank 1 ′ consists of a steel material, e.g. Cf53. The cutting speeds v c for these combinations of materials are within the standard range for such tools, namely from 300 m/min to 400 m/min.
[0023] In the present exemplary embodiment, both the roughing cutter 7 and the finishing cutter 7 ′ have 26 milling teeth 11 , 11 ′, and both cutters have a diameter d Wz of 80 mm. At cutting speeds v c of 300 m/min to 400 m/min and a tooth advance f z =0.12, it is possible with milling cutters 11 , 11 ′ of this type—in accordance with formula (I)—to reach advance rates v f of from 3000 mm/min to 6000 mm/min. To ensure that the chips formed slide away in an appropriate way on the tool face, the rake angle 14 of the milling teeth 11 , 11 ′ is in this case approximately 10°.
[0024] The following text will explain the kinematics involved in milling the ball raceways 3 into the joint inner part blank 1 ′, considering figures FIGS. 2 a , 2 b and 3 in combination with one another. During machining, the joint inner part blank 1 ′ is clamped into a chuck (not shown in figures FIGS. 2 and 3 ) with the aid of which the joint inner part blank 1 ′ can be rotated about its axis of symmetry.
[0025] To produce a ball raceway 3 which is tilted by an angle 5 with respect to the axis of symmetry 4 ′ of the joint inner part blank 1 ′, the rotary spindle 9 is tilted through the same angle 5 ′ with respect to a direction of rotation running perpendicular to the axis of symmetry 4 ′. Then, to carry out the roughing operation, the tool 6 is initially guided in such a way with respect to the joint inner part blank 1 ′ that the roughing cutter 7 introduces a flute-like groove 15 of depth 16 into the surface of the joint inner part blank 1 ′ (arrows 17 and 17 ′ in figures FIGS. 2 a and 3 ). Then, the tool 6 is advanced along the spindle axis 9 ′ by an offset A (arrow 18 in FIG. 2 a ), where A corresponds to the distance 8 between roughing cutter 7 and finishing cutter 7 ′ on the tool spindle 9 , so that the finishing cutter 7 ′ comes to lie opposite the flute-like groove 15 which has already been milled in. Then, the tool 6 is initially guided in such a way with respect to the joint inner part blank 1 ′ that the finishing cutter 7 ′ finely machines the region of the flute-like groove 15 which has been introduced in the first process step, so as to produce the final shape of the ball raceway 3 (arrow 19 in FIG. 2 b ). Finally, the tool 6 is moved back into the starting position by being displaced back by the offset Δ in the direction of the spindle axis 9 ′ (arrow 20 in FIG. 2 b ). In this way, the first ball raceway 3 is completed and the joint inner part blank 1 ′ can be rotated by means of the chuck in order for a further ball raceway 3 to be introduced into the outer circumferential surface of the joint inner part blank 1 ′.
[0026] In addition to this preferred embodiment of the invention illustrated in figures FIGS. 2 a and 2 b , in which two separate milling cutters 7 , 7 ′ are used for the roughing operation and the finishing operation, it is also possible for the two machining steps to be carried out using a single milling cutter, which carries out the roughing operation in its advancing movement and the finishing operation in its return movement. In addition to the kinematics illustrated in figures FIGS. 2 a and 2 b , in which a ball raceway is firstly roughed and finished before machining of the next ball raceway commences, it is also possible for a plurality of ball raceways to be roughed in succession first of all, followed by finishing of these ball raceways in succession. Furthermore, depending, for example, on the combination of materials and/or the desired quality of the ball raceway to be produced, it may be sufficient to carry out just one roughing operation, without subsequent finishing.
[0027] In the process kinematics illustrated in figures FIGS. 2 a and 2 b , the tool 6 is displaced with respect to the workpiece 1 ′ clamped in the chuck during the machining operation. In principle, it is also possible for the advancing movements to be carried out by the workpiece 1 ′. Which of the relative movements are carried out by the workpiece 1 ′ and which are carried out by the tool 6 depend on the particular machine.
[0028] During the hardening process which follows the chip-forming machining, the joint inner part is deformed so that the ball raceways are curved. To avoid expensive rework, this curvature must be taken into account in the milling process.
[0029] The process and tool according to the invention can be used to mill both straight and curved ball raceways 3 into joint inner part blanks 1 ′. In addition to the elliptical cutting contour 12 , 12 ′ of the cutting teeth 11 , 11 ′ shown in figures FIGS. 2 and 3 , the milling teeth 11 , 11 ′ may also have other cutting contours (e.g. trapezoidal cutting contours), in order to produce ball raceways with a rectangular or trapezoidal cross section instead of the ball raceways 3 with an elliptical cross section shown in FIG. 1 a.
[0030] In addition to the milling cutters 7 , 7 ′ of single-part configuration shown in figures FIGS. 2 a , 2 b and 3 , it is also possible to use milling cutters with cutting tips which can be inserted individually. This has the advantage that in the event of wear to individual milling teeth 11 , 11 ′, it is not necessary to replace the entire milling cutter 7 , 7 ′, but rather only the defective cutting tip has to be replaced. In this case, the cutting tips which form the milling teeth 11 , 11 ′ are preferably attached to the milling cutter by brazing or clamping.
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Cylindrical milling is used to produce ball raceways on an outer circumferential surface of a joint inner part for a constant-velocity rotary joint. To do this, a cylindrical milling tool with a large number of milling teeth based on the diameter of the tool is used in order to achieve a high advance rate.
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FIELD OF THE INVENTION
[0001] The present invention is in the field of tire retreading apparatus, and relates to improvements in both an apparatus and method used for retreading tires. In particular, the invention relates to rasp blades, and an improved assembly and method of use of such blades on tire rasp hubs for buffing away the tread on worn tires.
BACKGROUND OF THE INVENTION
[0002] The conventional process by which tire casings are retreaded is to buff away the worn tread, repair any damage that may be required in the casing after buffing, bond a new tread to the casing by a selected vulcanizing process, and then cure the rubber so as to harden and shape it into the desired tread design.
[0003] In order to buff and remove the worn tread, the tire casing is mounted on a buffing machine and inflated. A hub assembly, comprising a hub core having a large number of toothed rasp blades mounted thereon, is then rapidly rotated such as on a motor driven shaft, and the peripheral surface of the casing bearing the worn tread is forced against the rotating rasp blades to loosen, tear and grind off the excess rubber and roughen the remaining surface sufficiently so that the buffed surface of the casing can form a sufficient bond with the new replacement rubber tread in the vulcanizing process. Each tire size has a predetermined crown width, profile and radius and the casing must be buffed to the particular shape, size and texture to receive a new tread that ensures proper tread-to-road contact. Buffing of the worn tread is, therefore, a critically important operation of the retreading process affecting the quality, performance and safety of the retreaded tire.
[0004] Rasp blades of the prior art comprise numerous configurations and shapes, with a preferred type having teeth of essentially dove-tail shape projecting from the outer working edge. Individual teeth have a notch cut out from the center of the periphery or working edge of the tooth to form a series of substantially “Y” (or dove-tail) shaped teeth defined by cutouts of partly circular shape. The notch formed in each tooth divides it into halves. Each half of a given tooth is offset to opposite sides of the plane in which the blade lies, thus creating a primary cutting edge to one side of the blade body followed by a laterally spaced buffing edge for each tooth. As the rasp hub is rotated, the primary cutting edge and the buffing edge prepare the surface of the casing to a texture necessary and desirable for bonding to a new rubber tread.
[0005] A typical tire buffing hub assembly which includes rasp blades has the form of a hub defined by interconnected front and back cylindrical end plates having mounted there between arcuate or quadrant-shaped rasp blades stacked in four (or more) separate arrays around the perimeter of the hub. Each rasp blade of any one stack is separated from adjacent blades of the stack by spacers, the stack being secured in position between the end plates by support pins. The hub assembly is mounted on a drive shaft, and a The hub assembly is mounted on a drive shaft, and a bolt holds the end plates together, sandwiching the rasp blades, thus allowing for dismantling of the hub for purposes of blade replacement, such as when the teeth become worn or are broken. The stacks of blades may be inclined relative to a plane perpendicular to the axis of rotation of the hub; and the stacks may be alternated in this inclination or offset. That is, the blades of one stack may be inclined toward one end of the hub and an adjacent stack inclined toward the opposite end of the hub.
[0006] Many blades of various configurations and shapes used on tire rasp hubs, with all of the blades in a given hub having generally the same shape, size and distribution of teeth. For instance, any two adjacent blades in a stack may have identical secondary and tertiary configurations and the teeth of one blade may be substantially laterally aligned with the teeth of an adjacent blade. This arrangement is typically facilitated by using identical blades throughout and fixing each blade of a stack in a “name down” (or “face down”) direction, whereby the manufacturer's name appears on only one of the two opposed faces of the blade and indicates the direction in which the name side of all blades of that stack are to face. Where this technique is not employed, some other means for facilitating the stacking of the blades in a commonly aligned direction is used.
[0007] All of the teeth on each blade are symmetrically disposed along the working edge of the blade. For instance, the tooth (or partial tooth) closest to one end of the blade is located the same distance from that end as the tooth closest to the other end is located from that other end. Thus, the blades and configuration of teeth remain the same even if the blade is reversed and the “name” sides of adjacent blades face each other.
[0008] There have been suggestions to “stagger” the teeth of adjacent blades to provide an improved buffed surface for better adhesion to the tread after treating the tread-receiving outer surface of the casing. By using a tire rasp assembled with staggered teeth according to this invention, worn tire tread may be buffed away from a casing at a rapid rate while developing minimum amount of heat that might otherwise adversely affect the texture of the buffed surface needed for suitable retreading. Such suggestions include U.S. Pat. No. 3,102,325 of Hemmeter, and Australian Patent Application No. 58,291/99 of Anthony Collins. However, both suggested approaches requires “back to back” stacking of the blades in loading a hub.
SUMMARY OF THE INVENTION
[0009] The present invention is directed to a rasp blade for a tire buffing machine adapted to be mounted on a conventional rotary hub which typically includes disc-shaped end mounting plates and a plurality of cylindrical mounting pins (normally 2 or 3 pins) pressed into one of the end plates. The mounting pins extend parallel to the axis of rotation of the hub and serve to mount the blades between the discs to form a rasp assembly which is then mounted to a driven shaft.
[0010] Each blade includes a curved blade body having mounting apertures adapted to be received on the mounting pins, and an outer, working edge on which the teeth are formed. The entire blade is formed from a stamping which makes it economical to manufacture. After the blade is stamped out, forward and rear segments of each individual tooth are displaced in opposite lateral directions relative to the plane of the blade. The teeth are arranged on the working edge of the blade in side-by-side relation and in uniform pitch (i.e. spacing).
[0011] The body of the blade includes a mounting aperture for each pin located on the one end disc of the hub. Two or three mounting pins may be used, and the blades have a corresponding number of mounting apertures. For purposes of illustration, it will be assumed that three such mounting pins are used.
[0012] The body of the blade thus includes three mounting apertures. According to the present invention, one or two of the mounting apertures are duplex mounting apertures. This means that the same opening has two separate locations for receiving one of the mounting pins. The two locations are offset laterally by an amount related to the pitch of the teeth such that when the blades are mounted all “face up” (or face down) on the hub, the cutting teeth of one blade are staggered relative to the cutting teeth of adjacent blades when viewed from the side so long as the mounting pin (or pins) is received in alternate ones of the openings of the duplex mounting aperture.
[0013] One advantage of the present invention is that all of the blades in a given quadrant of the hub can be mounted in the same orientation. This permits the operator to conveniently load blades in a rotary manner (that is, assembling all blades of a given rank in the assembly) or to load each quadrant of blades before going to the next quadrant, according to the preference of the operator. The invention also eliminates “flipping” of the blades when loading a hub, as required in systems in which the blades are mounted in “back-to-back’ relation. Thus, the present invention reduces the amount of handling of the blades during assembly by the operator. Staggering the teeth is believed to produce more favorable conditions of buffing and a surface which forms an improved bond with the tread. In addition, staggering the teeth extends the life of the blade.
[0014] There are other features and advantages of the present invention which will be apparent to persons skilled in the art from the following detailed description of a preferred embodiment accompanied by the attached drawing wherein identical reference numerals are used to refer to like parts in the various views.
BRIEF DESCRIPTION OF THE DRAWING
[0015] [0015]FIG. 1 is an elevational view of a rasp blade for a tire buffing machine constructed according to the present invention;
[0016] [0016]FIG. 2 is a close-up fragmentary view of the left side of the rasp blade of FIG. 1 assembled to a mounting pin of a hub in the “left” position;
[0017] [0017]FIG. 3 is a view similar to FIG. 2 with the duplex opening modified slightly to increase the capture of the blade;
[0018] [0018]FIG. 4 is a perspective view of a portion of a hub end plate including mounting pins on which two adjacent blades constructed according to the present invention are mounted;
[0019] [0019]FIG. 5 is an elevational view of fragmentary left sides of two rasp blades constructed according to the present invention in staggered relation; and
[0020] [0020]FIG. 6 is an elevational view of a rasp blade incorporating the present invention and including two duplex mounting apertures.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] Referring first to FIG. 1, reference numeral 10 generally designates a rasp blade formed in a quadrant or arcuate shape. That is, the blade extends around approximately one quarter of a cylindrical hub assembly of a buffing machine (described later in connection with FIGS. 4 and 5). The blades 10 are stamped from sheet metal, and therefore are flat and extend in a plane generally perpendicular to the axis of rotation of the hub, although they may be slightly skewed (by approximately 3°-5°, for example) relative to a plane perpendicular to the rotational axis of the hub, as is known in the art. That is, alternate stacks of blades may be skewed in opposing directions—that is, one stack having its blades angled in one direction relative to a plane perpendicular to the axis of rotation and an adjacent stack having its blades angled toward the other direction relative to the same plane.
[0022] Located on a working edge of the blade 10 are a plurality of teeth generally designated 12 which are formed during the stamping process. The method of manufacturing and the form of the blade 10 (except for the duplex mounting aperture to be described), including the shape of the teeth 12 are known, as exemplified in U.S. Pat. No. 3,082,506.
[0023] The set of teeth 12 are uniformly distributed along the working edge, generally designated 14 , and have a predetermined, constant pitch. As used herein, “pitch” is the distance from the leading edge of one tooth to the leading edge of the next adjacent tooth on the same blade.
[0024] The teeth 12 are shaped in the form of a “dove tail” with a central notch. For example, the tooth designated 16 in FIG. 2 has a central notch 17 which separates a first tooth section 18 and a second tooth section 19 . Adjacent teeth are separated by a larger circular opening 21 . As seen in FIG. 2, the left edge of the section 18 forms an acute angle, thus forming a cutting edge 23 . Similarly, the section 19 forms a cutting edge 24 facing a direction opposite the cutting edge 23 . Moreover, the right edge 25 of the left tooth section 18 of the tooth 16 has a buffing edge 25 , and the left edge 26 of the right section 19 forms a similar buffing edge facing the opposite direction.
[0025] Each of the teeth 16 is twisted so that one individual section (for example, section 18 in the example of FIG. 2) formed by the notch 17 and the opening 21 is displaced to one side of the body 28 of the blade (for example, out of the plane of the page) in FIG. 2); and the other tooth section 19 is displaced to the other side of the blade body 28 (into the plane of the page), thus providing two individual tooth sections 18 , 19 displaced to opposite sides of the blade body 28 .
[0026] When the blade is rotated counter-clockwise as seen in FIGS. 1 and 2, the cutting edge 23 and the buffing edge 26 of the tooth cooperate to prepare the surface of the tire casing being worked on. If the blade is driven in the opposite direction, namely, clockwise as viewed in FIG. 1, the cutting edge 24 of the tooth section 19 and the buffing edge 25 of the tooth section 18 cooperate in preparing the surface of the tire.
[0027] Although not shown in the drawing, a manufacturer of rasp blades typically imprints its trademark or identification on one side of the blade. It is not necessary to the practice of the invention that one side of the blade be marked, but it may help to understand the operation of assembling blades to a hub if it is assumed that one side is marked or is the “face” side and the other is the back side.
[0028] As indicated above, it has already been suggested in the prior art to “stagger” the teeth of blades mounted on a hub. In this connection, the word “stagger” means that the teeth on adjacent blades mounted on the hub are offset from one another when viewed from the side—that is, the direction in which the observer looks when viewing FIGS. 1 and 2. This is parallel to the axis of rotation. However, the above-referenced Collins prior art suggests an arrangement in which the mounting apertures in the blade body (at least the two apertures to the side of the center) are located in offset positions relative to the center of the blade so that when the blades are mounted “back-to-back”, the cutting edges of teeth on adjacent blades are offset. Mounting blades back-to-back require that every other blade be flipped, leading to errors and increased handling, resulting in additional mounting time.
[0029] The present invention accomplishes a similar purpose in staggering the teeth, but it accomplishes this purpose by means of a mounting aperture such as the aperture designated 30 in FIG. 1 in the form of a “FIG. 8” and which is sometimes referred to as a duplex aperture to connote that the associated mounting pin may have two separate operating positions within the single opening or aperture 30 . That is, referring to FIGS. 1 and 2, the aperture 30 has a left circular segment 31 and a right circular segment 32 . Each of the circular segments 31 , 32 opens into the other, and have equal radii so as to receive and be secured to a mounting pin (see, for example, mounting pin 35 in FIGS. 2 and 5).
[0030] As can be seen in FIG. 2, the two circular segments 31 , 32 are joined at opposing points designated 38 , 39 . The chord, or straight line, extending between the two points 38 , 39 is less than the diameter of the associated mounting pin 35 . This ensures a secure engagement of the pin 35 by the associated segment of the duplex aperture, preventing the blade from sliding laterally. Moreover, it is desired that the circular segment 31 snugly receive the outer diameter of the mounting pin 35 for accuracy and for securing the blade on the hub during operation.
[0031] Other mounting apertures, such as apertures 40 and 41 shown in FIG. 1, are used to mount the blade 10 to a hub. Each of the mounting apertures 40 , 41 is of a shape referred to as “obround”, meaning that the left and right curved sections, designated 42 and 43 in mounting aperture 41 , are each semicircular and have a radius corresponding to the radius of the circular portions 31 , 32 of the duplex aperture 30 . However, the circular end segments 42 and 43 of aperture 40 are joined by slightly curved sections 44 and 45 presenting a generally obround opening. This permits the mounting pin to be received in either end of the mounting aperture 40 —that is, one side of mounting pin 35 engages either edge 42 or edge 43 for stability. Aperture 41 may be of a similar obround shape, or it may be a “FIG. 8” shape of a duplex aperture as seen in FIG. 6 and designated 48 . Further, a hub may have three mounting pins or two mounting pins. Thus, the blade may have three mounting apertures with one or two of the three apertures being duplex apertures, see FIGS. 1 and 6. Alternatively, the blade may have two mounting apertures with either or both being duplex apertures. As seen in FIG. 2, the upper and lower intersections 38 , 39 of the two circular segments 31 , 32 of the duplex aperture 30 are pointed. These intersections may be radiused as at 50 , 51 in FIG. 3 for a tighter securement of the blade, if desired.
[0032] Turning now to FIG. 4, the mounting of blades 12 and 12 A on an end plate 50 is illustrated. The end plate 50 has three mounting pins 35 , 35 A and 35 B. However, as explained above, two pins may be employed. The pins are pressed into bores machined in the plate 50 , as known. The first blade 12 is mounted to all three pins, 35 , 35 A and 35 B by means of duplex mounting aperture 30 , and obround apertures 40 and 41 . Blade 12 is mounted with the circular section 31 of duplex aperture 30 engaging or receiving the mounting pin 35 . (It will be observed that blade 12 is turned upside down in FIG. 4 as compared to the view of this blade in FIG. 1). Next, blade 12 A is attached to end plate 50 by inserting each of the three pins 35 , 35 A and 35 B through a respective aperture in the blade, however pin 35 is inserted in the circular segment 32 of duplex aperture 30 .
[0033] The centers of the duplex apertures are spaced such that by mounting alternate circular segments of the duplex aperture on the same mounting pin, and leaving the blades same side (or face side) up, the teeth are staggered with teeth being located in alternate blades approximately one-half pitch from the teeth in the next adjacent blades. This is so whether the hub is drive clockwise or counterclockwise.
[0034] The blades may be assembled to the end plate either in one stack at a time, or in one layer or rank at a time, as the operator desires and without flipping blades.
[0035] Turning now to FIG. 5, which is a view looking from the top of the stack in FIG. 4, it can be seen that the teeth of adjacent blades are staggered in the sense that the cutting edges of the teeth of one blade are offset relative to the cutting edges of the teeth in the next adjacent blade. For example, in FIG. 5, for the upper blade 12 A, assuming that the blades are being rotated counter-clockwise in FIG. 5, a cutting edge of blade 12 A is designated 23 A, and the cutting edge of a tooth of the adjacent blade 12 is designated 23 . Persons skilled in the art will understand that the same is true if the blades are rotated in a counter direction.
[0036] Having disclosed more than one embodiment of the invention, persons skilled in the art will appreciate that certain modifications may be made equivalent elements substituted for those disclosed while continuing to practice the principle of the invention. For example, the circular segments 31 , 32 of the duplex aperture could be formed of small, straight segments and still engage an associated mounting pin and provide adequate coupling. Further, the teeth of the illustrated embodiment are offset by one-half the pitch of the teeth. The teeth could be offset by one-third of the pitch, or other relationship. This would require an additional coupling segment for the duplex aperture, which would become a three-position aperture. It is thus intended that all such modifications and substitutions be covered as they are embraced within the spirit and scope of the appended claims.
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A rasp blade includes a mounting aperture having at least two aperture segments which are laterally spaced and communicate with each other. Each aperture segment may independently secure the blade on a mounting pin. Alternate blades are mounted using different aperture segments to fix adjacent blades in laterally offset positions, thereby staggering the teeth in adjacent blades.
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FIELD OF THE INVENTION
[0001] The present invention relates to chromatography equipment and column assembly.
BACKGROUND OF THE INVENTION
[0002] In gas chromatography (“GC”), the apparatus incorporated within the instrument that houses the column, is sometimes referred to as the column basket. As the columns are typically arranged in some form of coil, the size of the column basket is described in terms of its diameter. The diameter of the column basket generally dictates the size of the oven, which in turn dictates the overall size of the entire instrument size. Additionally, oven size and temperature needs dictate the power requirements of the instrument. In some markets there is a need for significantly smaller and faster gas chromatographs than the commonly available gas chromatograph. To those skilled in the art, this type of instrument is known as Micro GC.
[0003] Currently, Micro-GCs include columns wound down to small diameter (˜2″) inside a copper can. The column is manually positioned inside the can by a process of winding the column into the can where it expands inside the copper can. In some instances, multiple columns are wound down and expand inside the copper can. The copper can with the column or columns is then installed into the Micro GC where it serves as the oven. This arrangement and process for installation has several drawbacks.
[0004] First, Columns would by hand into cans is time-consuming and expensive. The entire installation process is typically performed by a skilled technician where the Micro GC is assembled for commercial use. As a result the end user cannot simply change columns or make repairs in the field. The entire unit must be shipped back to the manufacturer in order to change a column.
[0005] Second, manual winding, in a small fixed can, limits the length of column that can be used in the assembly. As the column fills the can from the outside diameter inwards, the volume of the can and the column minimum bending radius limits how much material can fit in the oven, and therefore the maximum column length provided. Longer length columns are especially problematic and can only be handled through special hand wound processing. Column integrity and lifetime are a function of bending radius. Damage to column material is cumulative, such that material drawn over a small radius even for short periods may experience significant reductions in expected lifetime. The process of overbending the column material to fit it inside the current can configuration necessarily reduces its lifetime. Currently, column lengths are limited to about 14 meters before problems arise with the installation.
[0006] Third, manual winding can be detrimental to the integrity of the column itself. The column packing or stationary phase can be disrupted by the process of winding it inside the can. Winding PLOT (Porous Layer Open Tubular) columns in particular degrades the internal coating by over bending the column during assembly, creating fractures in the brittle internal coating, producing shards or dust of stationary phase, which can degrade chromatography or adjacent devices such as micro injector valves.
[0007] What is needed is a method of installing columns in a Micro GC that avoids manual winding of the column into the copper can. Further, an apparatus that allows easy installation and removal of the columns in a Micro GC is needed. It would be particularly advantageous to be able to easily and reliably install longer columns.
SUMMARY OF THE INVENTION
[0008] A column installation assembly for a Micro Gas Chromatograph that includes a coiled column is described. The assembly also includes a mechanism within the Micro Gas Chromatograph for removably securing the coiled column in place.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, explain the advantages and principles of the invention. In the drawings,
[0010] FIG. 1 is a perspective view of an air wound column around the winding template;
[0011] FIG. 2 is a perspective view of an air wound column with a portion of the column fastened in position using ties with the winding template removed;
[0012] FIG. 3 is plan view of a Micro GC configured to receive an air wound column;
[0013] FIG. 4 is a plan view of a Micro GC with an air wound column placed in position;
[0014] FIG. 5 is a plan view of a Micro GC with an air wound column installed in the Micro GC.
DETAILED DESCRIPTION
[0015] Turning now to the drawings, FIG. 1 illustrates an embodiment of an air wound column of the invention. The majority of the column 10 is wound in a coil 15 around a winding template 20 . A length of each end 25 a and 25 b of the column 10 remains unwound from the coil 15 .
[0016] Preferably, the column 10 is wound around the winding template 20 using an automated respooling apparatus. While some column material is available in bulk spools, most analytic column material must be purchased in 30 meter or shorter lengths, already wound onto a conventional basket. In this instance, to the column is unwound from the basket onto a temporary spool without introducing any scratches, foreign material, twists or other stresses to the material. In particular, it is important not to bend the material to the extent that it would introduce large lifetime reducing stresses. From the temporary or bulk spool, the column material is metered through a tensioning device to the winding template 20 . A uniform small tension is important to feeding the material onto the template and ensuring it coils uniformly rather than stack up and collapse, leaving crossing tubing and internal voids in the bundle. Additionally, the tension also reduces the tendency of the relatively stiff tubing to spring out of the template before the assembly operation is complete. The metering of column length onto the template is preferably a non-contact operation. When the final length (typically 2-12 meters, but occasionally up to 30 meters) is counted onto the coil, a length of column at each end 25 a and 25 b is left un-looped and unsecured from the coil 15 of the assembled column and are fastened to the template with fastening devices 27 a and 27 b . Then, the column is severed, and the template is removed from the winding machine.
[0017] The internal diameter of the winding template is larger than the typical internal diameter of manually wound columns that are used inside of the copper can of conventional Micro GCs. As a result, this method of preparing the coil 15 places minimal stress on the integrity of the column packing and tubing. The preferred winding template 20 is a Teflon coated bobbin or spool. A Teflon coated bobbin or spool is easily removed from the coil 15 once the coil 15 is secured in shape, as discussed below. Although not required, it is preferred that the winding template 20 be removed from the coil 15 prior to use in a Micro GC as it may affect the heat distribution and overall performance once in place.
[0018] Once the column 10 is coiled around the winding template 20 , at least a portion of the coil 15 must be secured or fasted in coil shape so that it does not uncoil or unravel when being handled. FIG. 2 illustrates the preferred method of securing the coil 15 using physical fastening devices. Twist ties 30 a , 30 b , and 30 c of high temperature tape or string are fastened around the coil 15 positioned at approximately equidistant points around the circumference of the coil 15 . Twist ties 30 a 30 b , and 30 c are twisted tightly enough so that the coil 15 does not unravel but not so tightly that it damages the column 10 . FIG. 2 shows the use of three twist ties to fasten the coil 15 , however, less or more could be used to obtain the level of fastening needed. Additionally, other devises can be used in place of twist ties 30 . Non-limiting examples such as wire or clips can also be used.
[0019] Additional methods for securing or fastening the coil 15 can also be used. In one embodiment, an adhesive (not shown) is applied while the coil is still positioned on the winding template 20 . The adhesive is cured prior to the subsequent removal of the coil 15 from the winding template 20 . The preferred adhesive is EPO-TEK 353ND, however other adhesives may be used. One advantage of epoxy adhesive, and to some extent high temperature tape, is that the regular cross section of the coiled column is retained, making precision fitting into the oven assembly of the Micro-GC easier, providing more uniform temperature for good chromatography. The effect of temperature on the adhesive is an important factor to consider when choosing a suitable adhesive. Also, its potential reactivity with the coating of the column 10 is another important factor.
[0020] A length of column at each end 25 a and 25 b is left un-looped and unsecured from the coil 15 . The precise length left unsecured and un-looped at each end 25 a and 25 b is not critically important and can vary from application to application. The length must be long enough so that it may be properly installed in a Micro GC (discussed below). In the preferred embodiment, the final loop of each end 25 a and 25 b of the column 10 within the coil 15 is left unsecured as well. These unsecured loops are sometimes referred to service loops. The presence of service loops assists in the installation and service of the column 10 .
[0021] FIG. 3 illustrates an inside view of a Micro GC 100 configured for installation of a pre-wound column. A circular groove 110 is positioned inside the Micro GC 100 and dimensioned to receive the coil 15 of a pre-wound column (not shown). The cylindrical groove 110 is formed from a circular outer wall 117 . The back 112 of the cylindrical oven groove 110 is preferably lined with copper for its heat conducting properties and preferably includes a heater 121 , bonded to the copper lining. The width of the groove 110 is preferably large enough to house multiple columns at once. The outer wall 117 is constructed from the same material as the housing of the Micro GC, which is typically high temperature plastic. Optionally, the groove may also be bordered on inner side of the groove with an inner wall 115 , which is concentric to with the outer wall 117 . Preferably, the inner and outer walls 115 and 117 are integral with the back wall of the housing, however, they need not be. The inner wall 115 is generally unbroken, while the outer wall 117 has a number of breaks 119 to allow for the ingress and egress of the column ends 25 a and 25 b (not shown). The remainder of the Micro GC is generally configured as a conventional Micro GC. One end has an injector 122 and the other end has a detector 124 . The specific type and position of the injector 122 and detector 124 can vary and will depend on the specific requirements of the user.
[0022] FIG. 4 illustrates an inside view of the Micro GC 100 with a column 10 installed in position. The coil 15 of the pre-wound column 10 is placed in the groove 110 . The ends 25 a and 25 b are positioned out of the groove 110 through one of the breaks 119 in the outer wall 117 of the groove 110 . In order to provide some length adjustment, the free ends 25 a and 25 b of the column are preferably looped around inside the wall 117 to create a service loop. This provides enough axial travel for each column end for dressing or assembling it into the next device without requiring precision trimming and location. Typically, one end 25 a will exit the groove 110 in the direction of the detector 124 and the other end 25 b will exit the groove 110 in the position of the injector 122 .
[0023] Once the column 10 is installed, a lid 130 is placed over top of the column 10 to complete the installation. FIG. 5 illustrates the installation of the column 10 with the lid 130 in place. The lid 130 is also preferably constructed from copper. Other materials may be used, however the thermal properties of the material are a consideration. The lid 130 is dimensioned to fit firmly inside the outer wall 117 of the groove 110 . Clamping devises may also be used to hold the lid in place. Once the lid 130 is secured, the column ends may be coupled to the upstream and downstream devices.
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A column installation assembly for a Micro Gas Chromatograph that includes a coiled column is described. The assembly also includes a mechanism within the Micro Gas Chromatograph for removably securing the coiled column in place. A method for preparing a column for installment in a Micro Gas Chromatograph is also described
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to magnetic holders for knives or similar objects.
2. Description of the Prior Art
There have been previous inventions of magnetic holders for knives or similar objects, but none that are equivalent to the present invention.
U.S. Pat. No. 4,183,439, issued on Jan. 15, 1980, to William W. Bell, discloses a utensil and tool holder, that retains knives (and other utensils or tools) on magnetic strips that hang from a bracket. The instant invention is distinguishable, in that it uses disk-shaped magnets that are enclosed in non-magnetic material.
U.S. Pat. No. 4,451,810, issued on May 29, 1984, to Merrill R. Miller, discloses a magnetic tool holder, having a pair of plates with a magnetic bar sandwiched between the plates. The instant invention is distinguishable, in that it uses several disk-shaped magnets, rather than a single bar.
U.S. Pat. No. 5,011,102, issued on Apr. 30, 1991, to Walter J. Kiefer, discloses a magnetic knife holder, having disk-shaped magnets covered top and bottom by a cowling having a curved entry to guide the knife to the magnets. The instant invention is distinguishable, in that in it the magnets are embedded in a wooden board, and the knives are retained on the surface of the board.
U.S. Pat. No. 5,301,822, issued on Apr. 12, 1994, to Edward S. Coleman and Richard Scalise, discloses a magnetic tool holder, having a single elongated magnet, rather than several disk-shaped magnets as in the instant invention.
U.S. Pat. No. 6,575,313, issued on Jun. 10, 2003, to Kung Cheng Chen, discloses a structure for firmly resting tools thereon, with a magnetic sheet, rather than several disk-shaped magnets as in the instant invention.
U.S. Pat. No. 6,626,303, issued on Sep. 30, 2003, to Peter Moodie, discloses a magnetic presentation and display board, with two pairs of magnets for retaining various articles, including in each magnet pair a magnet on the exterior surface of the board, and a magnet embedded in the board. The instant invention is distinguishable, in that it is an elongated board with a single magnet for holding each knife, with every magnet embedded in the board, and dowels to mark the location of the magnets.
U.S. Pat. No. 6,719,155, issued on Apr. 13, 2004, to Ching-Tsung Chang, discloses a magnetic tool rack made of plastic, in which rectangular magnets are embedded. The instant invention is distinguishable, in that it is a wooden board in which disk-shaped magnets are embedded, with dowels to mark the location of the magnets.
U.S. Pat. No. 7,073,672, issued on Jul. 11, 2006, to Steven Sholem, discloses a tool organizer system, having a flat sheet of magnetically attracted material, rather than a board with embedded magnets as in the instant invention.
U.S. Pat. No. 7,172,079, issued on Feb. 6, 2007, to Hsuan-Sen Shiao, discloses a magnet rack that can be easily removed from a magnetically attractive surface. The instant invention is distinguishable, in that it is a wooden board with disk-shaped embedded magnets.
U.S. Pat. No. Des. 338,583, issued on Aug. 24, 1993, to John Esposito, Jr., discloses a design for a magnetic toothbrush support assembly. The toothbrushes appear to be retained by a single magnet, rather than several disk-shaped magnets as in the instant invention.
U.S. Patent Application Publication No. 2002/0130231, published on Sep. 19, 2002, to Stanley D. Winnard, discloses a method and apparatus for securing non-ferrous objects, using magnetic plates, rather than disk-shaped magnets as in the instant invention.
U.S. Patent Application Publication No. 2002/0175131, published on Nov. 28, 2002, to Alan L. Johnson, discloses a magnetic cutlery rack, with a backboard and a series of horizontal stop ledgers. The instant invention is distinguishable, in that in it there is a single elongated board on which the knives are retained vertically, and the magnets are embedded in the board, with their positions indicated by dowels.
British Patent No. 2 389 031, published on Dec. 3, 2003, inventors Paul Prelstman, Caroline Casey and Chris Parker, discloses a magnetic knife holder, having a plurality of magnets spaced apart in locations inside and along the length of a holder. Knives can be retained vertically on the horizontal holder. The instant invention is distinguishable in that it is formed from an elongated piece of wood that is sawed apart, drilled, and glued back together, with the magnets retained in the drilled holes, and the position of the magnets indicated by dowels.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.
SUMMARY OF THE INVENTION
The present invention is of magnetic holders for knives or similar objects, formed from boards that are sawed in half lengthwise, to form a front half and a rear half. A shallow wide hole is drilled in the center of the exterior surface of the front half, in which a disk having a company logo or other design is inserted. On both sides of the center, evenly-spaced wide holes are drilled from the interior surface of the front half about half-way through, then narrow holes are drilled the rest of the way through from the centers of the wide holes. Coin-shaped magnets are placed in the wide holes, and dowels are placed in the narrow holes to mark the position of the magnets. Knives may be retained on the holder by the magnets at the positions marked by the dowels. Slots for mounting on wall hooks are drilled or carved in the back surface of the rear half. The front and rear halves are then glued together, for a seamless look. The edges of the boards are preferably rounded.
Accordingly, it is a principal object of the invention to provide a means for removably retaining knives in an area where they may be conveniently retrieved.
It is another object of the invention to provide a means for removably retaining other objects in an area where they may be conveniently retrieved.
It is a further object of the invention to provide a means for retaining knives in an upright position on a wall.
Still another object of the invention is to provide a means for retaining other objects in an upright position on a wall.
It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the first preferred embodiment of the invention.
FIG. 2 is a front elevational view of the first preferred embodiment of the invention.
FIG. 3 is a rear elevational view of the first preferred embodiment of the invention.
FIG. 4 is a top plan view of the first preferred embodiment of the invention, with the bottom view being identical.
FIG. 5 is a left side elevational view of the first preferred embodiment of the invention, with the right side view being symmetrical.
FIG. 6 is a rear perspective view of the front half of the first preferred embodiment of the invention, with the rear half removed.
FIG. 7 is a rear elevational view of the front half of the first preferred embodiment of the invention, with the rear half removed.
FIG. 8 is a section view of the first preferred embodiment of the invention along lines 8 - 8 of FIG. 1 .
FIG. 9 is an environmental view of the first preferred embodiment of the invention, showing it holding a knife.
FIG. 10 is a perspective view of the second preferred embodiment of the invention.
FIG. 11 is a front elevational view of the third preferred embodiment of the invention.
FIG. 12 is a front elevational view of the fourth preferred embodiment of the invention.
FIG. 13 is a front elevational view of the fifth preferred embodiment of the invention.
Similar reference characters denote corresponding features consistently throughout the attached drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is boards with embedded magnets for holding knives or similar objects.
FIG. 1 is a perspective view of the first preferred embodiment of the invention, comprising a rectangular board 10 , having a front half 12 and a rear half 14 retained together at glue joint 16 , and holes (or “apertures”) containing short segments of dowel rods 18 marking the location of magnets embedded in the board. (Alternatively, the apertures may be filled with any other suitable material having a different appearance from the exterior surface of the board.) A disk 20 (or “coin inlay”) is retained in a shallow cylindrical hole in the center of the front surface of the board. There may be a company logo 22 or other decorative insignia on the exterior surface of the disk. The front edges 24 and front corners 26 of the front half of the board are preferably rounded. FIG. 2 is a front elevational view of the first preferred embodiment of the invention. The board is preferably made of hardwood, but it may made of any suitable material that is not attracted by magnets.
FIG. 3 is a rear elevational view of the first preferred embodiment of the invention, showing the slots 28 with recesses 30 by which the board may be retained on a wall or other surface using screws, nails, hooks or similar objects. The rear edges 32 and rear corners of the rear half of the board are preferably left square.
FIG. 4 is a top plan view of the first preferred embodiment of the invention, with the bottom view being identical. The coin inlay 20 may extend slightly from the front surface of the board. FIG. 5 is a left side elevational view of the first preferred embodiment of the invention, with the right side view being symmetrical.
FIG. 6 is a rear perspective view of the front half of the first preferred embodiment of the invention, with the rear half removed. For the sake of illustration, two disk-shaped magnets 36 are shown to fill two of the four disk-shaped cavities, while the other two disk-shaped cavities 38 are left empty. Small cylindrical apertures 40 pass between the center of each cavity and the front surface of the board, and are filled with the dowel rod segments that mark the location of the magnets. FIG. 7 is a rear elevational view of the front half of the first preferred embodiment of the invention, with the rear half removed, showing all the magnets 36 filling all the cavities 38 , as they normally would. The exterior surfaces of the magnets should be flush against the interior surfaces of the cavities. The magnets are preferably made from a rare earth element such as neodymium, that can be intensely magnetized to strongly attract knife blades or other metallic objects to be removably retained on the board. The apertures 40 holding the dowel rod segments are shown in broken lines, as they are hidden from view by the magnets.
FIG. 8 is a section view of the first preferred embodiment of the invention along lines 8 - 8 of FIG. 1 , taken halfway between the top and bottom surfaces of the board 10 , and passing through the centers of: the coin inlay 20 and its recess, the magnets 36 and their recesses 38 , and the dowel rod segments 18 and their apertures 40 .
FIG. 9 is an environmental view of the first preferred embodiment of the invention, showing a knife K held on the board by the attraction of its metal blade by one of the hidden embedded magnets.
FIG. 10 is a perspective view of the second preferred embodiment of the invention 42 , which is the same as the first preferred embodiment, except that it has only a single magnet 36 in a single cavity 38 , whose position is marked by a single dowel rod segment 18 in a single aperture 40 , and has no coin inlay. (The magnet, cavity and aperture are shown in broken lines, as they are hidden from view.) It may be called a “SideCar”, as it can be placed to the side of one of the longer boards to hold a single large knife or utensil.
The invention may be sold as set of magnetic knife holders, rather than individual holders sold separately. For the third, fourth and fifth preferred embodiments, for all the finished boards, the preferred width (distance from top edge to bottom edge) is two inches, and the preferred thickness (distance from front side to back side) is one inch. For the third, fourth and fifth preferred embodiments, all the magnets are preferably neodymium disks with a thickness of three-eighths of an inch.
FIG. 11 is a front elevational view of the third preferred embodiment of the invention, which is a set of knife holders called the “Signature Series”, having one six magnet board 44 (21 inches long), one four magnet board 10 (15 inches long), and two SideCars 42 (three inches long) with single magnets. The embedded magnets are preferably seven-eighths to one inch in diameter, with their centers spaced three inches from the centers of nearest magnets and/or the coin inlay.
FIG. 12 is a front elevational view of the fourth preferred embodiment of the invention, which is a set of knife holders called the “Steak Knife Series”, with one twelve magnet board 45 (19.5 inches long), one eight magnet board 46 (13.5 inches long), and one four magnet board 47 (7.5 inches long). The embedded magnets are preferably three-quarter of an inch in diameter, with their centers spaced one and a half inches from the centers of nearest magnets and/or the coin inlay, and their positions are indicated by smaller dowel plug 19 , that are one-quarter inch in diameter.
FIG. 13 is a front elevational view of the fifth preferred embodiment of the invention, which is a set of knife holders called the “Standard Series”, comprising three boards with no coin inlays, including one six magnet board 48 (18 inches long), one five magnet board 50 (15 inches long), and one four magnet board 52 (12 inches long). The embedded magnets are preferably seven-eighths to one inch in diameter, with their centers spaced three inches from the centers of nearest magnets.
The preferred embodiments of the present invention may be constructed by a method including the steps of:
1. Obtaining a rectangular board (preferably 5/4 to 6/4 inches thick).
2. Cutting the board into a first piece and a second piece (each about ⅝ inches thick), with a cut that is parallel to two opposite surfaces of the board, yielding pieces that are a “closed” book-match, said match being maintained throughout the following steps.
3. Planing the first and second pieces to one-half inch of thickness.
4. Rip sawing the first and second pieces to two inches in width.
5. Cutting the first and second pieces to the desired length of the finished board.
6. Drilling pocket holes (or “cylindrical recesses”) for the magnets in the interior surface of the first piece, said holes having the same diameter as the magnets and being ⅜ inch deep.
7. Drilling holes (or “cylindrical apertures”) for dowel plugs between the cylindrical recesses in the interior surface of the first piece and the exterior surface of the first piece opposite to the interior surface, with the cylindrical recesses and cylindrical apertures being concentric, and the cylindrical apertures being one-quarter inch in diameter for the Steak Knife Series, and three-eighths inches in diameter for the Signature and Standard Series mentioned above.
8. Drilling a pocket hole for the center inlay coin in the exterior surface of the first piece, one and a half inches in diameter and the depth of the inlay coin.
9. Inserting one disk-shaped magnet into each of the cylindrical recesses.
10. Reattaching the second piece over the interior surface of the first piece, preferably with glue. The glue joint should be barely visible, because the first and second pieces are a “closed” book-match, that is maintained throughout the process.
11. Cutting a hardwood (e.g., maple or walnut) dowel (one-quarter to three-eighths inches in diameter) into plugs 3/16 inches long. The wood should be chosen to contrast with the surface of the board.
12. Putting glue on the dowel plugs and pressing them into the circular apertures, then allowing the glue to set. (Alternatively, filling the apertures with any suitable material having a different appearance from the board.)
13. Rough sanding of all surfaces of the invention to remove excess glue and make the surfaces flush with each other.
14. Rounding the edges and corners of the board on the front side of the first piece (preferably using one-quarter inch round-over).
15. Forming one or more recesses (or “mounting slots”) in an exterior surface of the second piece of the board, suitably configured to enable the board to be retained (preferably by routing with a slot cutting bit).
16. Finish sanding of all surfaces, using progressive grits to obtain a desired smoothness.
17. Applying final finish, using two or three coats of edible mineral oil, edible walnut oil or edible shellac (They should be edible because the knives being held will contact the finish and then food and/or the holder could be chewed by children.)
18. Gluing and inserting the center inlay coin (having a diameter of one and a half inches) into its pocket hole.
The foregoing steps need not be performed in the exact order given. The dimensions given are for the sake of illustration only, and are not meant to limit the scope of the invention.
The design ensures that no contact between the magnet and knife (or other implement being held) can occur, because there is always about one-eighth inch of wood between the magnet and the knife. As the dowel plug has a color that contrasts with the board, it helps users locate the position of the magnets. The process of construction is basically the same for all sizes and types of knife holders. The size and number of magnets used can vary with the size and type of knives being held. Spacing varies with magnet size and the presence or absence of the decorative center inlay disk. The center inlay can have any desired insignia or design on its exterior surface. It is expected that the boards will primarily be constructed of domestic hardwood, but nearly any species of wood can be used, as can other material such as plastic, fiberglass, ceramics, etc. The overall dimensions of the holders and the size of the magnets can be varied to accommodate holding nearly any size or shape of implement.
It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.
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Magnetic holders for knives or similar objects, formed from boards that are sawed in half lengthwise, to form a front half and a rear half. A shallow wide hole is drilled in the center of the exterior surface of the front half, in which a disk having company logo or other design is inserted. On both sides of the center, evenly-spaced wide holes are drilled from the interior surface of the front half about half-way through, then narrow holes are drilled the rest of the way through from the centers of the wide holes. Coin-shaped magnets are placed in the wide holes, and dowels are placed in the narrow holes to mark the position of the magnets. Knives may be retained on the holder by the magnets at the positions marked by the dowels. The front and rear halves are then glued together, for a seamless look.
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BACKGROUND
[0001] 1. Field of the Invention
[0002] This patent relates to a protective device for door frames. More particularly, this patent relates to a device for protecting door frames that can be installed prior to construction, renovation and moving, and then easily and quickly removed afterwards.
[0003] 2. Description of the Related Art
[0004] During construction, renovation and moving operations key surfaces in a building can be subjected to abuse by workers and equipment moving in and around the building rooms. These surfaces, which include door frames, door edges and outer wall edges (i.e. outwardly projecting wall corners), are costly to repair and can often delay the completion of a building project. Protecting these surfaces can avoid costly repairs, reduce overall building costs and shorten building project time.
[0005] Several previous attempts to provide a protective device for door frames and the like are known. For example, Weller U.S. Pat. No. 4,768,320 describes a generally U-shaped door frame guard having a rigid outer shell and a soft inner shell. The guard has a generally rectangular central section (spine) and generally straight inwardly converging side members designed to grip a wall.
[0006] Freelove U.S. Pat. No. 5,203,130 describes a generally U-shaped extruded plastic door frame shield having flange-like cleats that oppose the door frame trim to hold the shield in place.
[0007] Raulerson et al. U.S. Pat. No. 5,737,878 describes a U-shaped door guard made from polymeric material and having side members that taper toward each other and can grip a doorway.
[0008] Hill U.S. Pat. No. 5,775,045 described a magnetic door frame guard to be used with metal door frames.
[0009] Wamsher U.S. Pat. No. 5,815,998 describes a resilient, U-shaped, door jamb protector comprising a high density plastic core sandwiched between soft plastic foam material.
[0010] Haldeman U.S. Pat. No. 6,357,187 describes a cardboard door frame protector that encloses the door frame without contacting it.
[0011] Hartley et al. U.S. Pat. No. 6,526,708 describes a guard that is attached to a door frame with a clamp.
[0012] Stradel U.S. Pat. No. 6,826,877 describes a guard for protecting a door frame having trim molding. The guard comprises a planar web (spine) and parallel side panels normal to the spine that flex toward each other. At least one of the side panels has an inwardly directed shoulder with a transverse flange that seats against a rear facing surface of the door trim molding.
[0013] Lovas U.S. Pat. No. 6,829,863 describes a guard that is attached to a door jamb via metal spring strips.
[0014] Mayes U.S. Patent Application Publication No. 2004/0088933 describes a C-shaped door trim guard having ridges for gripping the door trim.
[0015] It is an object of the present invention to provide an alternative means for protecting building surfaces, particularly door frames, that are vulnerable to abuse by workers and equipment.
[0016] Another object of the invention is to provide a protective device for building surfaces that does not require adhesive and is easy to install and remove.
[0017] Further and additional objects will appear from the description, accompanying drawings, and appended claims.
SUMMARY OF THE INVENTION
[0018] The present invention is a guard for protecting a door frame from impacts caused by people and equipment. The guard is a formed and cut paperboard tube comprising a longitudinal spine and two curvilinear, elongated, resilient side members attached to the spine. Each side member terminates in a free edge running parallel to the spine. The free edges are adapted to grip opposite sides of the door frame or the wall when the guard is placed over the door frame. No tape or other means of securing is required. Each side member further comprises a longitudinally disposed bead for added impact resistance. The guard may be manufactured by winding paperboard into a hollow longitudinal tube, forming the tube into the desired curvilinear shape, and making a longitudinal cut along the tube.
THE DRAWINGS
[0019] FIG. 1 is a perspective view of a door frame guard according to the present invention.
[0020] FIG. 2 is a top perspective view of the door frame guard of FIG. 1 shown protecting a door frame.
[0021] FIG. 3 is a side plan view of the door frame guard of FIG. 1 shown protecting a door frame.
[0022] FIG. 4 is a close up perspective view of the door frame guard of FIG. 1 shown protecting a door frame.
[0023] FIG. 5 is a cross sectional view of the door frame guard of FIG. 1 .
[0024] FIG. 6 is a cross sectional view of the door frame guard of FIG. 1 shown installed over a door frame.
DETAILED DESCRIPTION OF THE INVENTION
[0025] While this invention may be embodied in many forms, there is shown in the drawings and will herein be described in detail one or more embodiments, with the understanding that this disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the invention to the illustrated embodiments.
[0026] Turning to the drawings, there is shown in FIG. 1 one embodiment of the present invention, a guard 10 for protecting door frames and other building surfaces. The guard 10 comprises a longitudinal spine 12 and two opposing, substantially U-shaped, curvilinear, elongated, resilient side members 14 connected to each other along the spine 12 . Each side member 14 terminates in a longitudinal free edge 16 that is substantially parallel to the spine 12 . The resilient nature of the guard 10 causes the side members 14 to be biased toward each other when the side members 14 are flexed outwardly (away from each other).
[0027] More particularly, each U-shaped side member 14 comprises an outer wall segment 18 and an inner wall segment 20 connected at an outer apex 22 . The inner wall segment 20 extends from the outer apex 22 to the free edge 16 . The outer wall segment extends from the outer apex 22 to the spine 12 .
[0028] Optional beads 24 may be longitudinally disposed in each outer wall segment 18 for added impact resistance and to enhance the spring-like characteristics of the guard 10 . The spine 12 itself may be curved inwardly—in the direction of the inner wall segments 20 —to further enhance the spring-like characteristics of the guard 10 .
[0029] In its relaxed, unstressed condition, the distance (D) between the free edges 16 of the guard 10 preferably is less than the thickness of the wall to which the door frame is mounted. Consequently, when installing the guard 10 around a door frame affixed to a wall having a thickness greater than (D), the side members 14 must be flexed outwardly, away from each other. This is typically done by hand. When released, the free edges 16 grip either side of the wall 20 to hold the guard 10 in place without the need for further securing means.
[0030] FIGS. 2-4 are views of a guard 10 shown installed over a door frame 26 . When the guard 10 is placed over the door frame 26 to cover and protect it, the side members 14 are in a stressed, spread apart, state. The guard 10 covers the door frame 26 along its length, and preferably along that part of its length most likely to be subject to abuse from people and equipment.
[0031] Of course, the guard 10 can be made to any length to cover as much of the door frame 26 as desired. The guard 10 may be made wide enough and resilient enough to accommodate various door frame and wall thicknesses.
[0032] FIG. 5 is a cross sectional view of an edge guard 10 according to the present invention showing the distance (D) between the free edges when the guard 10 is in an unstressed position. The side members 14 are generally U-shaped and are connected at the inwardly curved spine 12 . The outer and inner wall segments 18 , 20 of each side member 14 meet at an outer apex 22 .
[0033] FIG. 6 is a cross sectional view of the edge guard 10 of FIG. 5 shown installed over a door frame 26 . The guard 10 is now in a stressed state and the free edges 16 are spread apart a distance greater than (D). The free edges 16 are in contact with the wall 30 .
[0034] The guard 10 may be made from any suitable material, including plastic or metal, but preferably is made from paper or, more specifically, layers of paperboard laminated together.
[0035] The guard 10 may be manufactured by winding paperboard into a hollow tube, forming the tube into the desired curvilinear shape, and then making a longitudinal cut along the tube opposite the spine 12 .
[0036] It is understood that the embodiments of the invention described above are only particular examples which serve to illustrate the principles of the invention. Modifications and alternative embodiments of the invention are contemplated which do not depart from the scope of the invention as defined by the foregoing teachings and appended claims. It is intended that the claims cover all such modifications and alternative embodiments that fall within their scope.
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A guard for protecting a door frame is provided. The guard is a formed and cut paperboard tube comprising a longitudinal spine and two curvilinear, elongated, resilient side members attached to the spine. The side members terminate in free edges adapted to grip opposite sides of the door frame wall. Each side member further comprises a longitudinally disposed bead for enhanced impact resistance.
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RELATED PATENT APPLICATIONS
[0001] This PCT application claims the further benefit of Australian provisional application 2010903253 filed on 21 Jul. 2010, and Australian provisional application 2011900008 filed on 1 Jan. 2011.
BACKGROUND OF THE INVENTION
[0002] The production of many goods for commercial and private use requires the utilisation of numerous types of minerals, or orebodies, and the processing of the same from raw materials into finished goods. Similarly, the production of much of the heat and electrical energy in use today requires a substantial amount of coal. The minerals utilised in industry are obtained from the crust of the earth, usually by mining the same. Before mining machines were in general use, the mining of minerals was carried out manually by using picks and shovels, as well as wagons pulled by horses or mules. In order to increase the production level of minerals, mining machines were invented to allow the minerals to be more easily mined from the earth and transported to the refining and manufacturing sites.
[0003] Minerals are mined by different methods depending on where the minerals are found in the crust of the earth. When the minerals are found near the surface of the earth, the overburden is first removed and then the minerals are mined by surface equipment, such as power shovels, bulldozers, drag lines, etc. Minerals are also located underground to the extent that the mining thereof must be carried out by tunneling into the earth to extract the minerals. Numerous types of underground mining techniques have been developed to efficiently and safely recover the minerals.
[0004] The underground mining of tabular orebodies, and in particular coal or trona, generally involves the use of mining equipment which cuts roadways in the orebody. In one form of underground mining, a series of pillars are formed so that a portion of the ore is removed and a portion of the ore (the pillar) is left in place. The pillars support the roof of the mine and prevent it from caving in and filling the mine workings. This is referred to as either “bord and pillar” mining or “room and pillar” mining. Sometimes the pillars of ore are removed on retreat from the mine to extract the remaining pillars of ore. The removal of the pillars causes the roof to cave in and form a goaf or gob. In addition to this technique of underground mining, a more productive system involves extracting the ore using longwall mining techniques.
[0005] The longwall mining systems essentially divide the entire coal seam into a number of “panels” which are typically 3 to 4 km deep or long, 200 to 350 m wide and 1.5 to 5 m high. Roadways are initially excavated on each side of each panel to provide transportation of equipment, miners and allow transport of the mined coal during mining of the panel. One roadway is a main gate and the other roadway is a tail gate. The maze of roadways in a coal seam can be used to ventilate the working area and remove dangerous gases, such as methane and carbon dioxide, and provide fresh air.
[0006] A large and heavy mining machine is equipped with a rotating shearer which is moved laterally back and forth across the face of the panel to successively remove thick sheets or slices of coal. Because of the complexity and size of such mining machines, they are extremely expensive. The slice of coal removed during a single pass can be about I m thick. The chunks of coal which are removed from the face of the panel fall into an armoured face conveyor which moves the chunks of coal laterally to the main gate. At the main gate or roadway, the coal can be pulverised into smaller pieces and loaded onto a long conveyor to be transported along the main gate and eventually to the surface.
[0007] The longwall mining machine further includes a number of hydraulic jacks which extend across the width of the panel and function to support the roof of the mined area just in back of the face of the coal panel. The hydraulic support jacks move with the mining machine forwardly as the rotating shearer is moved forward to extract coal from the face of the panel. Once the mining machine moves forwardly during the mining operation, the portion of the roof that is no longer supported by the hydraulic support jacks caves in and forms a goaf. Each panel of coal is mined in the manner described until the entire coal seam is spent. The longwall mining system can either operate as advancing longwalls, or as retreating longwalls, depending on whether the gateroads are progressed with the face of the panel, or the face is retreated between the roadways. In either case, a goaf is formed between the gateroads in the waste zone of the mined area.
[0008] Where appropriate, hydraulic jet mining is used to recover ore from surface deposits or from underground deposits. The hydraulic mining system is particularly suited to the underground environment where the ore is weak and the roof and floor rocks are hard to provide support and guard against cave in of the roof. It is also a suitable method to use where the orebody is tabular and located on a slope. As the ore is manually eroded by the hydraulic jet, it is carried downwardly with the assistance of gravity along the slope of the mine floor. Hydraulic jet mining is generally accomplished by using high volumes of pressurised water projected at the orebody from a nozzle or monitor which is controlled by an operator. Limitations of hydraulic jet mining include the effective dispersal range of the jet, which is approximately 30 m, and the limited visibility afforded to the operators. Typical examples of such mining systems were Sunagawa Colliery in Japan, and the Strongman Mine in New Zealand.
[0009] Directional drilling has been in use for some time in the petroleum industry, and in coal mining where it is used for either gas drainage operations or for exploration. In its preferred form, directional drilling involves the use of a bottom hole assembly consisting of a downhole mud motor with a bent sub which drives a rotary drill bit. The drilling of the borehole is guided by the use of a survey system which determines the orientation of the borehole, as well as the toolface angle of the bent sub. Based on information from the survey system, the operator may rotate the drill string to re-orient the bent sub and thus steer the borehole in another direction. In addition to downhole motors, alternative bottom hole assemblies may be used for directional drilling. The use of offset jets has long permitted the direction of a borehole to be corrected. The process used is similar to that used for a downhole motor and bit, except the corrected borehole is drilled by high pressure jets. Other directional control systems are also used in drilling. These may involve a rotating drill string with a bottom hole assembly consisting of pressure pads which push the bit to one side of the borehole, or the other, so that a desired borehole path is followed.
SUMMARY OF THE INVENTION
[0010] In view of the foregoing, it can be seen that a need exists for a method of mining underground orebodies, where the equipment is much less expensive and complicated, as compared to the longwall mining technique. The various features of the invention combine both the practise of directional drilling and hydraulic mining to extract a sloping tabular ore body in an underground environment. In its preferred embodiment, roadways are driven or formed underground to permit ventilation and access in the normal manner. Gateroads are formed with a dip, and with respective ditches therein to provide downhill drainage of the mined slurry of ore and jetting water. The ditch in the downhill gateroad permits the transport of the slurry of the jetting fluid and ore down to a sump, from whence the slurry can be pumped to the surface. Alternatively, the ore may be separated from the fluid at the sump and transported to surface. Drilling is used to connect gateroads on each side of an ore panel with a borehole. Drilling is normally of a directional nature and orientated off of the dip direction of the ore body. Directional drilling between the gateroads may be achieved using downhole mud motors, water jets or other systems to provide directional control of the borehole formation. Such systems typically utilise a form of borehole survey system.
[0011] On reaching the opposite gateroad, the directional bottom hole assembly is exchanged for a jetting bit which erodes the formation laterally. This is done either physically by changing the bit, or by remotely changing the mode in which the bit operates, such as a method of pumping a sealing ball down the drill string and pressurising it until a pressure relief port blows, thus creating a lateral jet. In any event, the hydraulic jet at the end of the drill string is directed to the sidewall of the borehole adjacent to the goaf area to erode the ore, while moving along the borehole. The ore is thus effectively mined from the borehole between the roadways, except for the formation of a pillar, if desired. It can be appreciated that the initial borehole is formed at a location where the mining of the panel is to be commenced.
[0012] The bulk of mining is achieved through the mechanism of erosion brought about by pumping a pressurised fluid from a lateral jet. The jet is controlled in order to drill in the direction of the orebody on the waste or goat side of the face of the orebody. If the mode of operation is that the borehole is drilled updip, fluid and ore flow downhill and back towards the borehole along the solid bottom edge of the orebody. Where the borehole is essentially drilled down dip, the slurry of fluid and ore proceed down the intersection of the solid edge of the panel face with the floor of the orebody to the roadway at the lower level of the panel being mined, from thence flowing to the sump.
[0013] Where the borehole is drilled essentially up dip, the borehole must be of a sufficiently large diameter to permit the fluid and ore to pass back through the borehole while the drill string is still in the borehole. A useful method to enlarge the borehole and remain in line with the mining system is to use a fluid jet to erode the borehole and enlarge the diameter thereof. After the enlargement of the drilled borehole, the lateral jet bit is used to mine the ore. Where the borehole is drilled up dip, the preferred sequence is to drill the borehole from one roadway to the other roadway, ream it out, re-enter the borehole with a jetting bit which will erode laterally, and then mine on the waste side of the panel face with the ore and fluid passing down the borehole to the lower roadway and thence to the sump. Depending on the pressure of the fluid used with the hydraulic jet, it is possible to mine the face of the ore panel with a height greater than the vertical diameter of the initial borehole.
[0014] Once a first pass of the mining operation is accomplished through the first borehole, a second borehole is formed downhill and parallel to the first borehole. A subsequent mining pass is accomplished using the second borehole to erode a further layer of ore from the formation. Subsequent boreholes arc formed to allow additional mining passes to deplete the panel of ore located between the roadways.
[0015] It can be appreciated that rather than using expensive and extremely heavy machinery for longwall mining, essentially the same result can be accomplished using directional drilling to sequentially form boreholes between roadways, and then use a high pressure jet which traverses each borehole to erode the ore panel. The mining of the ore continues in each borehole until the panel is spent. According to this technique, the equipment can be easily moved from one ore panel to another in a short period of time, thereby making the technique very cost effective. The nature of the equipment means that it can be easily retrieved should a collapse of the borehole or face occur. Another borehole may then be drilled and the mining process is recommenced through erosion. In the event that the drill string is lost then its cost is small compared to that of conventional longwall equipment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Further features and advantages will become apparent from the following and more particular description of the preferred and other embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters generally refer to the same parts, functions or elements throughout the views, and in which:
[0017] FIG. 1 shows a plan view of a panel being mined. The dip of the orebody is down the page. The boreholes are drilled down dip along the line 2 - 2 and the jetted face is along the line 3 - 3 ;
[0018] FIG. 2 shows a sectional view, taken along the line 2 - 2 of FIG. 1 , through a panel where the boreholes are drilled down dip and extraction is taking place;
[0019] FIG. 3 shows a sectional view through a panel where the boreholes are drilled up dip and extraction is taking place;
[0020] FIG. 4 shows a section taken along 4 - 4 of FIG. 1 , through the mining zone; and
[0021] FIG. 5 shows a plan view of a panel being mined with boreholes which are drilled up dip.
DETAILED DESCRIPTION OF THE INVENTION
[0022] FIG. 1 illustrates a plan view of a mineral panel that is being mined by drilling down dip. The mining operation of the panel proceeds in the drawing of FIG. 1 to the right, with the goaf ( 2 ) to the left and the unmined orebody ( 3 ) to the right. The angle or dip of the panel of ore being mined is shown in FIG. 2 , where the gateroad ( 10 ) is lower in elevation than the gateroad ( 5 ). The panel of ore of interest includes the solid deposit of ore ( 3 ) to be mined, as well as the goaf ( 2 ) that has been mined. The dip direction is marked by an arrow ( 18 ) in FIG. 1 . illustrated also is a neighbour goaf ( 1 ) that was formed in the area of the previously mined neighbour panel. The neighbour goaf ( 1 ) is separated from the current mining panel, i.e. solid ore ( 3 ) and associated goaf ( 2 ), by gateroads ( 4 , 5 ). On the lower side of the panel ( 2 , 3 ) undergoing the mining operation are the lower elevation gateroads ( 10 , 11 ). The gateroads ( 4 , 5 , 10 , 11 ) slope downhill to the right of the figure and include respective ditches (not shown) to drain the slurry of ore and water down to a sump ( 12 ).
[0023] The gateroads ( 4 , 5 , 10 , 11 ) are connected to main roadways ( 7 , 8 , 9 ) which are used for access and ventilation during development of the mine. The sump ( 12 ) collects the slurry of ore and fluid. Drilling of the borehole ( 17 ) is initiated at the gateroad ( 5 ) at ( 19 ). The borehole is shown as ( 17 ) and is drilled to gateroad ( 10 ) at ( 13 ). The borehole ( 17 ) can be drilled with diameters between about 0.1 m and 0.3 m, and preferably about 0.15 m. The length of the borehole ( 17 ) is about the same as the distance between opposite roadways, namely about 300 m. This distance is to a significant extent controlled by ventilation needs. The angle or dip of the borehole ( 17 ) with respect to a horizontal reference can be anywhere between about 6 degrees and 45 degrees. It is noted that these dimensions and numerical limitations are not critical to the operability of the methods of the invention. In any event, while drilling the borehole ( 17 ), the ore removed is also mined and recovered by way of a slurry at the sump ( 12 ).
[0024] At the terminal location ( 13 ) of the drilled borehole ( 17 ), the directional drill bit is changed to a lateral jetting device (not shown) and the zone to the left of the borehole ( 17 ) is eroded. The goaf ( 2 ) is thereby formed. In the figure, the eroding bit is at ( 16 ) and a panel face ( 15 ) is formed which is advanced up dip. The eroded ore and fluid flow down the lower face ( 14 ) to downhill gateroad ( 10 ) into a ditch ( 23 in FIG. 2 ), and thence down the ditch ( 23 in FIG. 2 ) to the sump ( 12 ). Once the ore has been mined from the initial borehole ( 17 ), the drill pipes are removed and the drilling equipment is moved downhill a short distance to drill a subsequent borehole where another mining operation is again carried out using the jetting nozzle. Depending on the roof behaviour, it may be possible to erode all the ore from the eroding bit ( 16 ) to the goaf edge. If, however, roof control becomes an issue and it is not possible to erode back to the goaf edge, the preferable approach is to leave a pillar parallel to the borehole ( 17 ) to provide roof support. This pillar can be designed to crush as the goaf ( 2 ) fully forms, or to remain standing.
[0025] The ore is transported to surface from the sump ( 12 ) either as a pumped slurry or is separated at ( 12 ) and is carried to surface by such a device as a conveyor while the water is pumped separately.
[0026] A pillar ( 6 ) is formed because the eroding jet is controlled so as not to erode the formation all the way to the roadway ( 5 ). The pillar ( 6 ) is Conned adjacent to the gateroad ( 5 ) where the directional drilling equipment is located.
[0027] In another embodiment of the invention, it is possible to pre-drill all of the boreholes ( 17 ) in the panel and use them for drainage of water and/or gas prior to mining.
[0028] FIG. 2 illustrates a borehole cross-section through the panel of FIG. 1 . Up dip, the roadway ( 4 ) has a goat zone ( 1 ) uphill from it and is therefore damaged. Drilling of the borehole ( 17 ) in this embodiment begins at the higher elevation roadway ( 5 ), and proceeds down to the lower elevation roadway ( 10 ). As noted above, at borehole location ( 13 ), a laterally eroding jet bit (not shown) is attached to the drill string (not shown) in the borehole ( 17 ). The jetting bit is shown at location ( 16 ) having eroded the zone ( 26 ). The shaded area ( 6 ) near roadway ( 5 ) depicts the pillar zone where mining does not take place so as to preserve the roadway ( 5 ) and the drilling machinery ( 27 ) located therein. The drill pipe in the borehole ( 17 ) is pulled back by the drill ( 27 ) which is used to manipulate the orientation of the drill string in the borehole ( 17 ) and with it the jetting bit. The roof above the orebody is marked as ( 21 ) and the floor as ( 20 ). Drainage ditches are formed in the floor of the roadways at ( 23 , 24 , 25 ). The ditch ( 23 ) carries the slurry of fluid and ore away from the mining area as originally did the up dip ditch ( 25 ) for the previously mined up dip panel. The ditch ( 24 ) carries drill fluid away from the directional drilling operation. The borehole spacing might be typically 5 to 10 m, limited by the eroding capability of the jetting bit within the particular ore type. While not shown, the borehole ( 17 ) is drilled at desired locations between roadways ( 5 , 10 ) using directional and/or spatial sensors and other equipment well known in the art. A survey and mapping of the formation can be made to determine where the various roadways should be made before the mining operation is commenced. The actual mining operation can be carried out using a camera or other visualisation device such as an acoustic scanner located at the jetting nozzle so that the operation can be observed and controlled by an operator at a remote location. Cameras utilising self cleaning lenses can be used to provide an unobstructed view of the mining operation and the need for adjustment thereof. Using a joystick, the operator can control the orientation of the jetting nozzle to selectively erode the ore panel, and at the same time remotely view the jetting operation to verify that it is progressing as desired. At times, if the drainage of the slurry is slowed due to blockage by excessive ore on the mine floor, borehole or ditches, the jetting erosion can be temporarily suspended so that the additional fluid can be used to flood the area and clear the drainage way of the excess ore. The advantage of the remote control of the jetting operation is that workers arc not in the area where there is a risk of the mine roof collapsing, or being overcome by dangerous gasses or outbursts.
[0029] FIG. 3 illustrates another embodiment showing a sectional view through an ore panel where the borehole ( 17 ) has been drilled up dip from roadway ( 10 ) to roadway ( 5 ). The borehole ( 17 ) has then been reamed to a large size. The drill string (not shown) equipped with a jetting nozzle has then been re-inserted into the borehole ( 17 ). The eroding jet bit is shown at location ( 33 ), and is moving downhill toward the roadway ( 10 ). The zone up dip of the eroding bit at ( 33 ) and below the roadway ( 5 ) has been removed by the action of fluid erosion. The ore and fluid mined has passed back down the enlarged borehole ( 17 ) to the drainage ditch ( 23 ). The zone ( 30 ) is not mined so as to form a barrier pillar and prevent caving damage to roadway ( 10 ). In its preferred embodiment, the enlarged borehole ( 17 ) is eroded to a larger size than the original borehole ( 17 ) by the use of a combination of different eroding bits, water flow or eroding time duration to suit requirements. The reaming of borehole ( 17 ) may also be accomplished by other means such as rotating mechanical reamers.
[0030] FIG. 4 is an enlarged view of the mining face at section 4 - 4 of the operation depicted in
[0031] FIG. 1 . Here, the lateral jetting bit is at ( 16 ) in borehole ( 17 ). The jetting bit ( 16 ) has lateral port(s) in it which make it jet laterally from the bit ( 16 ). The jets which issue from the lateral port(s) may be directed to sweep at different orientations by twisting the drill string within the borehole ( 17 ) using the drilling machine. This twisting is controlled by the operator working under the guidance of the survey system and visualisation system contained within the drill string and delivering information to the operator.
[0032] The roof of the orebody is shown at ( 21 ) and the floor at ( 20 ). The face which has been eroded is at ( 15 ) and solid ore is to the right of the jetting bit ( 16 ) and between the roof ( 21 ) and floor ( 20 ). A goat is formed at ( 2 ), because the roof of the excavated portion of the panel can no longer support the weight of the material thereabove. Angular movement of the jet ( 22 ) cuts ore from the face ( 15 ) which then flows down the floor ( 20 ) to the face at ( 16 ) and thence along the intersection of the eroded face ( 14 ) and the floor ( 20 ) into the ditch in the roadway (not shown) and outward.
[0033] While it is not shown in this figure, the potential exists to not use the jet ( 22 ) to cut the full way to the goaf ( 2 ) but rather leave a narrow pillar between, which is parallel to borehole ( 17 ). This pillar then serves to control the failure of the roof ( 21 ) into the area where flow of the mined ore slurry takes place. The use of such parallel pillars also retards goaf formation and permits ventilation of the mining area.
[0034] FIG. 5 illustrates the drilling operation conducted up dip from roadway ( 10 ). The dip direction is marked by an arrow ( 18 ). Here, the roadway ( 5 ) is at a higher elevation than the roadway ( 10 ), but the mining with the hydraulic jet starts at the higher end of the panel. The drill rig is positioned in the downhill roadway ( 10 ) at ( 31 ) and has drilled up grade to position ( 32 ) in the roadway ( 5 ). The borehole ( 17 ) is then reamed out and a lateral jetting bit (not shown) is attached to the end of the drill string (not shown). In the figure, the jetting bit is at location ( 16 ) and is shown cutting the face ( 15 ) of the ore panel. The mined ore and fluid flow down the borehole ( 17 ) to location ( 31 ) and thence into the ditch (not shown) in the roadway ( 10 ).
[0035] From the foregoing, it can be seen that ore panels can be mined without the utilisation of heavy and expensive equipment which is difficult to move from one panel to another. According to a feature of the invention, the mining of a panel of ore is commenced by forming a borehole from one roadway on one side of the panel, to the opposite roadway on the other side of the panel. The roadways are preferably sloped to carry the mined slurry of ore and a liquid used to erode the face of the panel. Similarly, the borehole is sloped so that the mined ore can be carried as a slurry either in it or along its former position to the downhill roadway. Once the initial borehole is formed through the ore panel to the opposite roadway, the drill bit is changed to a hydraulic jet, and a pressurised liquid is used to erode the sidewall of the borehole as the hydraulic jet is withdrawn back down the borehole. The sweeping up and down of the hydraulic jet as it is moves down the borehole forms a face of the ore panel. Once the first pass of the hydraulic jet is made to erode the sidewall of the borehole and the orebody across the panel, a second borehole is formed through the ore panel, and the hydraulic jet is again used to erode a subsequent slice of the panel face. The process continues until the entire panel of ore has been mined. During the mining of the ore using the hydraulic jet, the ore and liquid form a slurry that is carried down the bottom of the mined area, and again down the downhill roadway to a sump. A goaf is formed after an area has been mined, as the mined area can no longer support the roof. Should the roof of the mine prematurely collapse, a new borehole can be formed and the mining operation again commenced to continue mining the ore panel. Even if the ore formation is not oriented on slope, which is optimum, the mining operation can be carried out by forming the opposite gateroads with different elevations so that the slurry of ore is nevertheless carried downhill by the action of gravity. The system is best but not exclusively suited to narrow orebodies which are soft and thus easily eroded while having a hard roof and floor which is not easily eroded and which does not cave near the face. Thus an open area is left adjacent to the face and between it and the goaf to permit ventilation between the gateroads. The prudent use of the system would involve the capability to ventilate the upper and lower gate roads independently in the event of a face collapse which blocks air flow between gateroads. The use of the system following gas drainage drilling could be advantageous as the gas drainage boreholes could be re-used as the boreholes from which mining is undertaken by the described methods. Another advantage of the system is that the maximum amount of mining hardware that is at risk is the drill string, survey and surveillance tools and either a downhole motor and bit or the jetting assembly. This is significantly less machinery than is involved in conventional longwall mining operations.
[0036] While the preferred and other embodiments of the invention have been disclosed with reference to specific mining methods, structures and equipment, it is to be understood that many changes in detail may be made as a matter of engineering choices without departing from the spirit and scope of the invention, as defined by the appended claims.
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A mining system for extracting ore using directional chilling techniques to obtain access to the orebody. Spaced-apart roadways are formed in the ore formation, with a downhill roadway being lower in elevation than the other roadway, and the downhill roadway having a ditch therein draining downhill. A borehole is formed between roadways in the ore formation using the directional drill bit, and then the end of the drill string is equipped with a jetting nozzle. The jetting nozzle is moved within the borehole to erode the formation and mine the ore. In one embodiment, a slurry of mined ore and jetting fluid flows as a slurry down the intersection of the mined face and the floor towards a ditch formed in the downhill roadway. In another embodiment, a slurry of the mined ore and the jetting fluid flows down the borehole, and then down the ditch formed in the downhill roadway. In each case, the ore flows down the downhill roadway to a sump. From the sump, the ore is carried to the surface for transportation and eventual refining or use.
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FIELD OF THE INVENTION
This invention relates to an automatic turret lathe.
BACKGROUND OF THE INVENTION
It is already known to fit the turret of an automatic turret lathe with combination tools comprising an internal tool and an external tool. The tool holders pertaining thereto are however relatively complicated. Moreover, a satisfactory cutting position for the two tools can be attained only with difficulty.
It is already known to dispose two separate turrets one behind the other. However, as both have the same diameter, they are hardly suitable for combined tool use. In this known construction, if only one turret is needed, the other cannot be removed (German Auslegeschrift 19 52 050).
SUMMARY OF THE INVENTION
The object of the invention is to provide a turret arrangement with which it is possible to simultaneously machine with two tools using separate tool carriers and holders, but wherein the arrangement is such that its structure is suitable for different types of turning, such as bar machining, chuck machining and shaft machining.
According to the invention there is provided an automatic turret lathe comprising a bedplate, a main spindle for rotating a workpiece; a headstock on the bedplate carrying the main spindle; a main turret which is indexable about an indexing axis and has a plurality of main tool carriers; a removable supplementary turret disposed on the same indexing axis as the main turret and having a plurality of supplementary tool carriers arranged so as to form pairs with respective main tool carriers, the supplementary tool carriers being closer to the indexing axis than the main tool carriers; and a support on which both turrets are mounted and which is slidable in longitudinal and transverse directions on the bedplate.
By this means all tools or their tool holders can be inserted individually into their carriers, yet each tool of the supplementary turret can be combined with a tool of the main turret. Furthermore, the cutting edges of the two tools which are simultaneously in use can be brought into advantageous mutual positioning.
Due to the fact that the supplementary tool carriers are at a smaller distance from the indexing axis and the difference relative to the corresponding distance of the main tool carrier of the main turret is considerable because of the advantageous cutting edge arrangement, the main turret basically comprises more tool carriers than the supplementary turret. For all machining in which a combination of two tools is not necessary or is not possible, for example in shaft machining, the main turret can be used for turning work in the normal known manner after removing the supplementary turret.
In order to be able to carry out cylindrical turning, a material guide can be provided with a guide bush, fitted to a support which moves together with the turrets. By this means, internal machining can be carried out by the supplementary turret simultaneously with external machining by the main turret.
In this connection, it is significant that because of the substantially smaller radical distance of the supplementary tool carriers from the indexing axis, the internally machining tools of the supplementary turret and the externally machining tools of the main turret can be so disposed that their cutting edges are at approximately the same direction from the indexing axis. For cylindrical turning, it can also be advantageous if the distance of the externally machining tool from the indexing axis is slightly greater than that of the internally machining tool.
In using the two turrets, pairs of tool carriers can certainly be present which are fitted only with internally machining tools. In this case, in order to avoid collisions, the two tool holders of this pair of tool holders should be disposed at a distance apart in the direction of the indexing axis which is greater than the radius of the material chuck or of the largest workpiece.
In an advantageous construction, there is provided a longitudinal carriage slidable to and fro in a longitudinal direction on the bedplate, and both the two transversely mobile turrets and the material guide for guiding the working material are disposed on this longitudinal carriage.
Generally it is advantageous for the number of main tool carriers to be considerably greater than the number of supplementary tool carriers. However, it is advantageous for the main tool carriers not to be a whole multiple of the supplementary tool carriers. For example, the number of tool carriers is advantageously at least one tool carrier, and preferably an even number of tool carriers, greater than double the number of supplementary tool carriers. A desirable arrangement is one in which there are fourteen main tool carriers and six supplementary tool carriers.
In practically all types of machining with the exception of shaft machining, it is advantageous to insert internally machining tools and externally machining tools alternately in the main tool carriers. This leads to several advantages. In the first place, any danger of collision between neighbouring tools is avoided. Again, in collaboration with the supplementary turret, favourable cooperation between the tools of the two turrets can be attained. Furthermore, the tool pairs can be changed by changing over the externally machining tools of the main turret. This latter advantage can also be attained in that the supplementary turret can be shifted separately from the main turret. Overall, the automatic turret lathe according to the invention, including its preferable features, is suitable for practically all turning which is done on such machines, such as chuck machining, shaft machining using a tailstock, machining short cylindrical parts from bar stock, and machining long cylindrical parts from bar stock using a material guide. Suitable tool arrangements for these types of machining are known, such as for example a disc-type turret for shaft machining, a star-type turret for chuck machining, and a drum-type turret for long cylindrical machining. Instead of using these known types of construction, the automatic turret according to the invention, including its preferable features, is particularly suitable for all this work.
The importance of this universal use is closely connected with the fact that automatic turret lathes, in particular NC latches, are mostly used only for machining small batch runs for economical reasons. This leads to the requirement that such a lathe must have considerable flexibility. This is particularly true of small NC lathes, as the machining times of the workpieces prepared thereon are short. Such a machine can therefore be employed to full capacity only if a plurality of workpieces of the most difficult types can be prepared on such lathes.
Further advantages and characteristics of the invention will be apparent from the description given hereinafter of embodiments of the invention, with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view of an automatic turret lathe according to the invention illustrating the machining of short cylindrical parts;
FIG. 2 is a front view of the two turrets of FIG. 1 without tools and to a larger scale than FIG. 1;
FIG. 3 is a plan view of FIG. 2;
FIG. 4 is a plan view of an automatic turret lathe according to the invention illustrating long cylindrical machining;
FIG. 5 is a partial front view of FIG. 1 or 2 with the supplementary turret removed, illustrating the machining of a large chuck part;
FIG. 6 is a plan view of FIG. 4 with the supplementary turret removed, illustrating the machining of shafts;
FIG. 7 is a partial side view in the direction of the arrow A of FIG. 6, with the headstock removed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In the embodiment shown in FIGS. 1 to 3, a bedplate is indicated by 16, on which a headstock 18 is fixed, to take the rotatable main spindle, the spindle head being indicated by 20. A chuck, not shown, is fitted thereon, in which a workpiece 24 is clamped. The spindle axle is indicated by 26.
Opposite the headstock there is provided a tailstock 28, comprising a tail spindle 33 with a tail centre 31. The tailstock is longitudinally slidable on a guide 30, disposed on the front cheek of the bedplate. From FIG. 7 it can be seen that the tailstock is in the special shape of a projecting arm.
A longitudinal carriage 34 is longitudinally slidable on a carriage guide 32 on the rear cheek of the machine bed, and a holder 36 (see FIG. 4) is transversely slidable in the carriage 34 and carries on its front end a main turret 38, possessing a total of fourteen main tool carriers or stations 40 (see FIGS. 2 and 3). A supplementary turret 42 is provided with supplementary tool carriers or stations 44 is removably disposed on the front of this main turret 38. This supplementary turret has a substantially smaller circumference than the main turret, so that the distance between the supplementary tool carrier and the indexing axis is considerably smaller, and preferably less than half, the distance between the main tool carriers and the main axis.
The supplementary turret is preferably fitted with internally machining tools, of which only four are shown in FIG. 1. As clearly shown in FIG. 2 a main tool carrier 40 is always associated with each supplementary tool carrier 44, so as to form pairs of tool carriers and thus tool pairs when tools are inserted. A pair consisting of dissimilar tools will be known as a first pair, and in FIG. 1 two first pairs are present. A pair with similar tools will be known as a second pair, and two second pairs are shown in FIG. 1.
A workpiece can be machined, as with a combination tool, by the first pairs of tools, as will be described hereinafter. In this, it is advantageous if the cutting edges of the two tools as seen in front view in FIG. 1 lie at approximately the same distance from the indexing axis 29 of the two turrets, or, in other words, lie approximately on the same trajectory circle. However, in FIG. 1, the internally machining tools of the supplementary turret are somewhat shortened for clarity in the Figure.
It should be mentioned also that the support which supports the turrets and which comprises the longitudinal carriage 34 and holder 36 can be formed in another manner, and for example can comprise a lower and upper carriage in the manner of a cross carriage. It is merely essential that the turrets can move in the longitudinal and transverse directions.
The two turrets 38 and 42 are formed in the manner of horizontal turrets, and can be indexed stepwise about the indexing axis 29, which is transverse to the spindle axis 26 and cuts this latter. The two turrets can be indexed either together or advantageously individually by means of an indexing device, not shown.
In the embodiment shown in FIG. 1, the main turret is fitted alternately with internally machining tools 46 and externally machining tools 48. These tools are held in tool holders, which in their turn engage in the corresponding carriers. However, for the sake of simplicity, hereinafter, in the case of both turrets, the description will only make reference to "tools," and this expression is also understood to include the respective tool holders. The distance between the tool carriers of the two turrets in the direction of the indexing axis should not be too large, so as to be able to machine with two tools in the manner of a combination tool in the case of the first pairs. However, this distance should also be large enough so that when machining with the internally machining tools of the second pairs, the respective tool which is not being used remains free from the workpiece and from the workpiece clamp with the spindle head. In this respect, care should also be taken that the clamping device and the spindle head not only have an appropriate small circumference, but also have an appropriate axial length such that the internally machining tools of the supplementary turret can be fully used for machining.
FIGS. 2 and 3 are a front and plan view to an enlarged scale of the two turrets, but without tools. The main tool carriers are indicated by the reference numerals 1 to 14, and the supplementary tool carrier by the reference numerals 1', 3', 6', 8', 10', 12'.
If it is now assumed that the main turret 38 of FIG. 1 is fitted alternately with internally and externally machining tools, and the supplementary turret 42 carries six internally machining tools 49, then there are two first pairs 1, 1' and 3, 3', and four second pairs, namely 6, 6', 8, 8', 10, 10' and 12, 12'. Thus a combined machining is possible in two positions.
In order to bring the internally machining tools of the four second pairs into full machining, it is necessary, as already heretofore stated, for the distance between the two turrets in the axial direction to be sufficient, and for the circumference and length dimensions of the chuck and spindle head to be such that machining can be carried out free from collisions.
The relationships between first and second pairs can be interchanged by moving all tools of the main turret through one station, or, in the case of separately indexable turrets, by indexing one of the two turrets through one step.
In FIG. 4 and the remaining figures, parts analogous to those of FIGS. 1 to 3 are indicated with the same reference numerals.
In FIG. 4, a support 50 is fixed on the longitudinal carriage 34 and carries a guide bush 52, in which a bar-shaped work-piece 24 is guided. The workpiece is clamped in a chuck, not shown, in the spindle head 20.
Only a few tools are disposed on the two turrets for better visibility. It can be seen that a first pair comprising an externally machining tool 48 on the main turret 38 and an internally machining tool 49 on the supplementary turret 42 simultaneously machine the front end of the bar. As in this case the chips are removed in the manner of long cylindrical machining, it is particularly important for the cutting edges of the two simultaneously machining tools to be at approximately the same distance from the indexing axis, or in other words, approximately on the same trajectory circle, and to lie close to the guide bush 52. In the case of long cylindrical machining, it can be advantageous for the cutting insert of the internally machining tool to lie a very small distance behind the cutting insert of the externally machining tool.
FIG. 5 shows that when machining a workpiece 60 of large diameter, which is held in a chuck 62, the supplementary turret is mostly unusable, and can therefore be removed.
FIGS. 6 and 7 show the use of the automatic turret lathe for shaft machining. The end of the shaft 70 is held with a chuck 72, and the other end is held in the centre 31 of the tail spindle 33 of the tail-stock 28. In this case the supplementary turret 42 is removed, and the main turret 38 is fitted with externally machining tools, of which only one is shown.
FIG. 7 shows a special form of the tailstock. It can be seen that when machining the total length of the shaft, the tool carrier lying opposite the machining tool on the main turret is left free.
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An automatic turret lathe has a main and a supplementary tool-carrying turret both being jointly movable in longitudinal and transverse directions with the turrets being indexable about an indexing axis. The supplementary turret is of smaller diameter than the main turret. Turning tools can be placed in the turrets so that a tool in one turret forms a pair with a tool in the other turret, and the turrets arranged so that both inside and outside machining of a workpiece can be carried out simultaneously. Tools can be placed in the carriers in the turrets to carry out a particular desired function. The supplementary turret can be removed for machining shafts. The turrets can be moved towards and away from as well as along the lathe axis.
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BACKGROUND OF THE INVENTION
This invention relates generally to tools for installing helical coil inserts into tapped holes, and, more particularly, to tools having means for adjusting the depths to which such inserts are installed.
Helical coil inserts are commonly installed into tapped holes of a workpiece such that threaded fasteners, e.g., screws, thereafter can be held more securely. The inserts are frequently installed in relatively soft materials such as aluminum, to improve the gripping of threaded fasteners made of relatively hard materials such as various steel alloys.
Helical coil inserts of this kind are usually installed by compressing them into a smaller diameter and then rotatably threading them into the tapped holes. Once installed, the inserts expand from their compressed diameters and thereby press radially outwardly against the tapped holes and are held securely in place.
Tools for installing the helical coil inserts are typically driven by an air motor and include a tubular tool body having a threaded opening extending along its axis and having means at one end for carrying an insert. A mandrel is received within the threaded opening and is rotatably advanced by the air motor into engagement with the insert. Further advancement of the mandrel forces the insert through a prewinder, which reduces the insert's diameter, and from there into a tapped hole in an adjacent workpiece.
The insertion depth of the helical coil wire insert is controlled by limiting the distance to which the mandrel can be advanced. Typically, this has been accomplished using a sleeve of a desired length which is positioned between the tubular tool body and a flange on the mandrel. In order to change the insert's installation depth, the mandrel had to be removed from the tool body and a different-length sleeve or spacer put in position around the mandrel. An exemplary tool of this kind is shown in U.S. Pat. No. 3,111,751 to Eddy.
The need to remove the mandrel from the tool body in order to adjust the insert's installation depth is unduly time consuming. This has been a particular problem when a large number of inserts have to be installed at a variety of depths.
Another approach has also been used previously, with equal difficulty. A stop collar has been used to limit the distance the mandrel could travel and thereby set the depth to which the helical coil insert could be installed. A set screw secured the collar in a selected position on the mandrel, but the collar would often slide up or down the mandrel after repeated use, because of vibrational forces and the force of the collar jamming against the tool body.
It should therefore be appreciated that there is a need for an installation tool for helical coil inserts that quickly and conveniently allows the adjustment and setting of insertion depths. In particular, there is a need for a tool that can be adjusted without having to disengage the mandrel from the tool body, without having to maintain an inventory of a number of different-length sleeves, without having to retighten a stop collar that loosens due to vibration and jamming, and without having to substantially disassemble the entire tool. The present invention fulfills this need.
SUMMARY OF THE INVENTION
The present invention is embodied in a tool for installing helical coil inserts into tapped holes in a workpiece, the tool being quickly and conveniently adjustable to control the depth to which each insert is installed. The tool includes a tubular tool body having a threaded opening extending along its axis and having means at its leading end for carrying a helical coil insert, in alignment with the threaded opening. A mandrel is located in the threaded opening for engagement with the insert, and driving means applies a torque to the mandrel sufficient to install the insert into a tapped hole. In accordance with the invention, the tool further includes a sleeve threadedly received in the threaded opening of the tubular body, encircling the mandrel. The sleeve is engaged by an annular shoulder on the driving means, to prevent further advancement of the driving means and mandrel and thereby limit the depth to which the insert is installed in the tapped hole. The insertion depth can be adjusted quickly and conveniently, without requiring any removal of the mandrel from the tool body, by controllably threading the sleeve into or out of the tool body.
In other, more detailed aspects of the invention, the sleeve has two flats interrupting the threads, on opposite sides of the sleeve. A set screw threaded through the tubular body can be tightened against one of the flats to secure the sleeve's position within the tool body. The exposed upper end of the sleeve is slotted so that a spanner wrench can grip and threadedly turn the sleeve into or out of the tool body. The slots can be aligned with the flats, to indicate the flats' circumferentional locations on the sleeve.
Other features and advantages of the present invention should become apparent from the following description of the preferred embodiment, taken in conjunction with accompanying drawings, which illustrate, by way of example, the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the preferred embodiment of a tool for installing a helical coil insert into a tapped hole in a workpiece.
FIG. 2 is a side elevational view of the installation tool, with the front portion of an associated adaptor for an air motor being shown in phantom lines.
FIG. 3 is an exploded perspective view of the installation tool.
FIG. 4 is an enlarged sectional view of the installation tool, with the adjusting sleeve in its most inward position, resulting in the helical coil insert being installed to a maximum depth.
FIG. 5 is an enlarged sectional view of the installation tool, with the adjusting sleeve in an extended position from that of FIG. 4, resulting in the helical coil insert being installed to an intermediate depth.
FIG. 6 is an enlarged sectional view of the installation tool, with the adjusting sleeve in an even further extended position from that of FIGS. 4 and 5, resulting in the helical coil insert being installed to a relatively shallow depth.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference now to the drawings there is shown a tool for use in installing a helical coil insert 11 into a tapped hole 13 in a workpiece 15. The tool includes a tubular tool body 17 having an opening 18 extending axially through its entire length. An insert is carried in a recess 19 formed adjacent the body's leading end and coaxial with the body's opening 18. An elongated, threaded mandrel 21 engages threads 23 (FIGS. 4-6) in the body opening, immediately adjacent the insert recess, such that rotation of the mandrel relative to the body advances the mandrel's leading end into engagement with the insert. Further rotation of the mandrel forces the insert through a threaded compression section or prewinder 25 of the tool body, which compresses the insert's diameter for threaded insertion into the tapped hole. After the insert has been installed to a predetermined depth, the mandrel is rotated in the reverse direction, to withdraw from the tapped hole. The insert expands into tight engagement with the hole and thereafter can serve as a hard surface for securely gripping the threads of a threaded fastener, e.g., a screw (not shown).
The mandrel 21 is rotatably driven by an air motor that includes an adapter portion 27 (FIG. 2) coupled to the tool body's trailing end. The adapter's leading end is secured to the tool body 17 by a nut 28 that grasps two annular flanges 29 and 31 projecting outwardly from the body. A clutch assembly 33 is interposed between the air motor and the mandrel's trailing end, for coupling torque to the mandrel 21. Rotation of the motor thus threads the mandrel downwardly through the tool body, until the mandrel's leading end engages the insert 11 and threads it through the prewinder 25 into the tapped hole 13. The clutch assembly has a diameter larger than that of the mandrel, such that its lower end forms an annular shoulder 35.
In accordance with the invention, the installation tool further includes a sleeve 37 encircling the mandrel 21 and threaded into an upper section 39 of the tool body's opening 18. An upper annular shoulder 41 of the sleeve is positioned to be engaged by the shoulder 35 of the clutch assembly 33, which limits further advancement downwardly of the clutch assembly. After a few additional turns, the clutch assembly ceases to couple the motor's rotation to the mandrel and further threading of the insert 11 into the tapped hole 13 likewise ceases. Operation of the clutch assembly is described more fully below.
As shown in FIG. 3, the adjusting sleeve 37 includes threads on its exterior surface, to be threadable into or out of the tool body 17. This exterior threading is interrupted by two flats 43 and 45 directly opposite each other, for use in locking the sleeve in a selected position to the tool body. A set screw 47 is threaded through a threaded opening 49 in the body to abut against one of the sleeve's two flats. This prevents the sleeve from rotating and thereby locks it in place.
The adjusting sleeve 37 further includes wrenching slots 51 on its upper or trailing end, for engagement by a spanner wrench 53 (FIG. 1). The wrench includes protruding fingers 55 for gripping the slots and enabling the sleeve to be threaded to a preferred position. The slots are preferably aligned with the flats 43 and 45, to provide a visible indication of the flats' circumferential location relative to the set screw 47 and threaded opening 49.
Threading the adjusting sleeve 37 inwardly or outwardly relative to the tool body 17 provides the installation tool its variability in setting the depth of the helical coil insert 11 to be positioned within the tapped hole 13. To the extent that the sleeve rises above the tool body's upper end, the distance the mandrel can travel through the body is limited. This limits the depth that the insert will be set within the tapped hole. This adjustability is illustrated in FIGS. 4-6, which depict three exemplary depth settings, A, B and C, respectively.
In FIG. 4, the adjusting sleeve 37 is positioned in its most retracted position, i.e., almost entirely within the tool body 17. The clutch assembly 33 is depicted with its shoulder 35 in contact with the sleeve's shoulder 41. The resulting insertion depth A of the helical coil insert 11 in the tapped hole 13 of the workpiece 15 is the deepest the installation tool can provide.
In FIG. 5, the adjusting sleeve 37 is retracted from its FIG. 4 position such that the clutch assembly's shoulder 35 engages the sleeve's shoulder 41 sooner. The mandrel 21 is therefore not advanced as far as it was in FIG. 4, and the helical coil insert's insertion depth B is correspondingly shallower than the insertion depth A of FIG. 4.
In FIG. 6, the adjusting sleeve 37 is retracted even further from the positions of FIGS. 4 and 5. The mandrel 21 can therefore be advanced by the air motor only a short distance, and the helical coil insert's insertion depth C is relatively shallow.
As shown in FIGS. 1-3, the recess 19 at the lower end of the tool body 17 is sized to permit a convenient placement of the helical coil insert 11. A slot 57 on the back side of the recess facilitates automatic loading of a series of inserts carried on a plastic strip (not shown), as is conventional. The empty strip exits through the slot, while the next succeeding insert is loaded into the recess.
As best shown in FIG. 3, the clutch assembly 33 includes a clutch sleeve 59, two clutch elements 61 and 63 contained within the clutch sleeve, and a compression spring 65 for urging the two clutch elements together. The first clutch element 61 is secured to the clutch sleeve by a transverse locking pin 67, and the second clutch element 63 is integral with the mandrel 21, forming its upper end. The respective clutch elements 61 and 63 include a mating tab 69 and notch 71, such that rotation of the first element is positively coupled to the second element.
In operation, the air motor rotatably drives the clutch sleeve 59, in a first direction, e.g., clockwise, via a tab 73 projecting from the sleeve's side. This rotates the first clutch element 61 and, in turn the second clutch element 63, which is urged into engagement with the first element by the compression spring 65. Since the second clutch element is integral with the mandrel 21, this rotation threadedly advances the mandrel relative to the threaded section 23 of the tool body opening 18.
Eventually, the mandrel's leading end engages the helical coil insert 11 and rotatably drives it through the prewinder 25 and into the tapped hole 13. The mandrel will disengage from the threaded section 23 of the tool body at a point during the installation procedure; however, the mandrel continues to advance relative to the tool body because it and the insert are then threadedly engaged with the tapped hole.
When the shoulder 35 on the lower end of the clutch sleeve 59 finally reaches the shoulder 41 of the upper end of the adjusting sleeve 37, further axial advancement of the clutch sleeve is prevented. Further rotation of the clutch sleeve and first clutch element 61 continues to advance the second clutch element 63 and the mandrel 21, however, until the tab 69 and notch 71 of the respective clutch elements move out of engagement with each other. Thereafter, no further advancement of the mandrel can occur, and installation of the insert in the tapped hole is complete. Conventional air motors are designed to reverse rotation directions automatically when this has been accomplished. This withdraws the mandrel from the installed insert 11 by rotating in a second or reverse direction, e.g., counterclockwise.
It should be appreciated from the foregoing description that the present invention provides an improved tool for use in automatically installing a helical coil insert to a selected depth in a tapped hole. A special adjusting sleeve is threaded to a selected position in a tubular tool body to serve as a stop preventing further advancement of a mandrel that forces the insert into the tapped hole. The sleeve's position can be conveniently and precisely threaded into or out of the tool body, to adjust the insertion depth without requiring any disassembly of the mandrel from the tool body.
Although the invention has been described in detail with reference to the preferred embodiment, those skilled in the art will appreciate that various modifications can be made without departing from the invention. Accordingly, the invention is defined only by the following claims.
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A tool for use in automatically installing a helical coil insert to a preselected depth in a tapped hole formed in a workpiece. The tool includes a tubular tool body carrying an insert near its lower end, and a mandrel in treadedly received in the tool body for engaging the insert and rotatably advancing it into the tapped hole. An adjusting sleeve encircles the mandrel and is threaded to a selected position in the tool body, to serve as a stop for further advancement of the mandrel, thereby controlling the depth to which the insert is installed. The sleeve's position can be adjusted quickly and conveniently without the need for removing the mandrel from the tool body.
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CROSS-REFERENCE TO RELATED APPLICATION(S)
None
BACKGROUND OF THE INVENTION
The present invention relates to cutting tools such as drills having a liquid as both a coolant and a lubricant supplied to the cutting face of the tool and the material being cut and, more particularly, to liquid flow path restrictions for such tools.
Tools that are used to cut through hard material operate in the presence of large amounts of heat generated thereby and undergo rapid wear of the tool cutting surface in the absence of measures to reduce same. One such measure is to provide a liquid serving as both a coolant and a lubricant at the tool cutting surface where it engages the material being cut. In one such situation, in which a drill is being used to form a hole in a hard material, such a drill can be provided with an interior fluid flow channel to allow transport therethrough of such a liquid under substantial pressure to the interface between the drill and the material thereby allowing that liquid to serve as both a coolant and a lubricant for the drill cutting surface. Such a liquid brought to the drill cutting surface in addition aids in forcing out cut away portions of the material being cut as well as aiding in preventing the drill bit from overheating which can lead to increased tool wear or even breakage.
In such a cutting situation, the liquid pressure may have to be quite large for the liquid to be effective at the tool cutting surface where it meets the material being cut. Liquid pressures from a few hundred pounds per square inch to thousands of pounds per square inch may be needed depending on the particular situation. Fluid confinement in the toolholder at appropriate locations and in the interior fluid flow channel of the tool except at the orifices of that channel where the liquid exits onto the tool cutting surface is necessary if such liquid pressures are to be maintained during operation of the tool. Thus, the pressurized liquid must be confined to flowing with respect to the tool only through the transfer channel and out the orifices thereof in the cutting tool surface, and not along other circumventing paths. That is, the liquid from the pressurized reservoir thereof in the toolholder must flow through the transport channel in the drill and not through other parallel paths to the atmosphere.
One such parallel path for the liquid are leakage paths around the shaft of a drill bit being used as the operating tool. Such leakage has been limited in the past by providing some sort of a seal around the periphery of the drill bit so that fluid reaching the drill shaft from the pressurized reservoir is prevented, at least in large part, from flowing along the sides of the drill. One such seal is shown in U.S. Pat. No. 5,567,093 to the present inventor based on a rigid seal positioned at one end about the drill with an O-ring therebetween, and with the opposite end of the rigid seal being captured between the collet chuck and the collet nut so as to be held by the tightened nut against the collet chuck and the liquid pressure. However, changes in shapes of collets and collet nuts that have previously been commonly used, and increases in liquid pressures being used, can limit the suitability of such a rigid seal. Thus, there is a need for a tool shaft seal system in connection with a toolholder that accommodates various collet chuck shapes and higher liquid pressures for liquids used as a coolant and lubricant at the cutting surface of the tool during operation thereof in cutting materials.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a seal assembly for a toolholder with a collet clamping member about an extended tool placement opening that can be forced radially inward to clamp a tool having a forcing ring in which at least in part the clamping member can be positioned with a seal ring opening positioned adjacent to, and coaxially with, the clamping member with this opening having an inner surface supporting an engager accommodation such as threading. A seal ring with a tool insertion opening including a surrounding O-ring holder has an outer surface supporting an engager, such as threading, that can be removably engaged with the forcing ring engager accommodation in the forcing ring seal ring opening to place this seal ring in a selected position therein. An O-ring is provided in the seal ring O-ring holder. The seal ring has a pair of ends with one of these ends having a pair of holes therein opposite one another across the tool insertion opening.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a truncated side view including a partially cutaway view of a toolholder arrangement and assembled tool embodying the present invention,
FIG. 2 is an exploded perspective view of the toolholder shown in FIG. 1,
FIG. 3 is an exploded side view of the toolholder shown in FIG. 1 and tool including partially cutaway views,
FIG. 4 is an exploded perspective view of an alternative toolholder embodying the present invention,
FIG. 5 is an exploded side view of the toolholder shown in FIG. 4 and tool including partially cutaway views, and
FIG. 6 is an end view of the present invention.
DETAILED DESCRIPTION
FIG. 1 is a truncated side view, including a partially cutaway view portion, 10 , of a toolholder with an assembled tool showing a chuck, 11 , with jaws, 12 , clamping a toolholder extension, 13 , at one end thereof. Chuck 11 has a liquid transport channel, 14 , in the interior thereof connected to a reservoir of liquid in the toolholder provided under substantial fluid pressure to serve as a coolant and a lubricant for tools held in, or ultimately held by, this chuck. Such a liquid is thereby present in extension 13 again under this substantial fluid pressure.
Extension 13 , at its opposite end, has an interior surface portion, 15 , which tapers outwardly from the smallest inner diameter of extension 13 to a largest interior diameter occurring at this very end thereof to thereby have a taper angle with the length axis of symmetry of extension 13 . The outside of extension 13 at this same end has a threaded surface, 16 , thereabout that is more clearly seen in FIGS. 2 and 3.
Interior tapered surface 15 at the tool end of extension 13 forms a chamber at that end in which a collet chuck, 17 , can be inserted so that an outer long tapered surface portion, 18 , thereof is closely mated with interior tapered surface 15 of extension 13 , i.e. has a taper angle with respect to the length axis of symmetry of collet 17 similar to that of surface portion 15 with respect to the length axis of symmetry of extension 13 . Outer long tapered surface 18 of collet 17 ends at a collet nut capture channel, 19 , recessed into the outer surface of collet 17 on the other side of which the remainder of the outer surface of collet 17 is formed by a short tapered surface, 20 . Outer long tapered surface portion 18 , at the end thereof opposite the end thereof adjacent to channel 19 , ends at an end, 21 , of collet 17 , and outer short tapered surface portion 20 , at the end thereof opposite the end thereof adjacent to channel 19 , ends at a second end, 22 , of collet 17 .
Outer surface portions 18 , 19 and 20 of collet 17 are the outer surface portions of a collet wall structure, 23 , which is formed about a tool placement opening, 24 , which has a truncated cylinder shape, and opening 24 extends through collet 17 from end 21 to end 22 . A set of slots, 25 , extend from collet end 21 through collet wall structure 23 for substantial distance toward end 22 . Similarly, a set of slots, 26 , extend from end 22 through wall structure 23 a substantial portion of the way towards end 21 with slots in this set alternating with those in set 25 around the periphery of collet 17 . Thus, a radially directed inward force on outer tapered short wall surface portion 20 of collet 17 causes portions of collet wall 23 to be moved radially inward from an unforced position to being against a tool shaft provided in tool placement opening 24 .
Such a radially directed inward force on outer tapered short wall surface portion 20 of collet 17 can be provided by tightening a collet nut, 30 , onto the end of extension 13 over collet 17 positioned in the chamber in extension 13 formed by interior tapered surface 15 thereof. Collet nut 30 has an approximately truncated cylindrical outer surface with some depressed portions provided therein to aid in gripping it, and this outer surface extends between a first end, 31 , and a second end, 32 .
An extension opening, 33 , approximating a truncated cylinder extends into collet nut 30 inward from end 31 , and a seal ring opening, 34 , also approximating a truncated cylinder extends inward into collet nut 30 from end 32 thereof. The inner surface of collet nut 30 about extension opening 33 at end 31 thereof is threaded to provide a threaded interior surface portion, 35 , which can mate and engage with the threads on threaded surface 16 at the end of extension 13 . The interior surface of collet nut 30 about seal ring opening 34 at end 32 thereof is also threaded to form a threaded interior surface portion, 36 .
A clamping structure opening, 37 , is provided between extension opening 33 and seal ring opening 34 within collet nut 30 to form a continuous opening therethrough. Clamping structure opening 37 has atapered interior surface portion, 38 , of collet nut 30 thereabout with a taper angle with respect to the length axis of symmetry of collet nut 30 substantially matching that of outer short tapered surface portion 20 of collet 17 with respect to the length axis of symmetry of collet 17 . Tapered surface 38 extends between a circular shoulder, 38 ′, formed at the interior end of seal ring opening 34 and a circular opening constriction ridge, 38 ″, formed at the interior end of extension opening 33 . Circular opening constriction ridge 38 ″ fits in collet nut capture channel 19 of collet 17 when mated therewith in mounting a tool in extension 13 . Alternatively, rather than being formed as part of collet nut 30 , tapered interior surface portion 38 and circular shoulder 38 ′ can be provided by a tapered opening ring and held in an extension of extension opening 33 in collet nut 30 by a snap ring also serving as circular opening constriction ridge 38 ″.
Thus, when collet 17 is in the end of extension 13 and collet nut 30 has the threaded surface 35 thereof engaged with threaded surface 16 of extension 13 sufficiently, tapered interior surface 38 of collet nut 30 is forced against outer short tapered surface portion 20 of collet 17 , and tapered interior surface 15 of extension 13 is forced against outer long tapered surface portion 18 of collet 17 , to thereby force wall structure 23 at tapered surface portion 20 inward so as to clamp a tool shaft provided in tool placement opening 24 of collet 17 . An example of such a tool shaft is shown provided as part of a drill, 39 , having a liquid transport channel, 39 ′, therein extending through the length thereof.
A seal ring, 40 , has an O-ring channel, 41 , formed therein about a tool insertion opening, 42 , otherwise shaped as a truncated cylinder. An O-ring, 43 , is shown positioned in channel 41 in FIGS. 1 and 3 but outside of ring 40 in FIG. 2 . The exterior surface otherwise approximating a truncated cylinder of seal ring 40 is threaded to form a threaded surface, 44 , that can mate with threaded surface 36 of collet nut 30 so as to be rotatable therein to a position against shoulder 38 ′ in collet nut 30 .
As a result, in the mounted tool assembly shown in FIG. 1, pressurized liquid provided in extension 13 is also at the base of the shaft portion of drill 39 from which it flows through drill liquid transport channel 39 ′. The pressurized liquid is also forced through the slots in collet 17 , and about collet 17 , into collet nut 30 but is prevented from leaving collet nut 30 at end 31 thereof by the mating of threaded surface 35 of that collet nut and threaded surface 16 of extension 13 . The pressurized liquid is also prevented from flowing through seal ring opening 34 of collet nut 30 by the mating of threaded surface 36 of collet nut 30 with threaded surface 44 of seal ring 40 . Finally, the pressurized liquid is prevented from flowing along the sides of drill shaft 39 by tightly fitted O-ring 43 held thereagainst by sealing ring 40 .
Collet nuts and extensions are formed of high quality steel and have substantial wall thicknesses to withstand high torques thereon occurring during tightening one on the other, and therefore can withstand large internal fluid pressures. Seal ring 40 , having a substantial thickness, is also well able to withstand the liquid pressures encountered as is its threaded mating with collet nut 30 .
A newer geometric form for the collet chuck and corresponding collet nut is shown in the exploded perspective view of an alternative toolholder of FIG. 4 and the exploded side view thereof shown in FIG. 5 again with the shaft of a drill shown as the tool to be held. This collet chuck, 17 ′, again has outer long tapered surface portion 18 extending between collet end 21 and circumferential collet nut capture channel 19 recessed into the outer surface of collet 17 ′. However, a much shorter outer short tapered surface portion, 20 ′, extends between channel 19 and the remaining collet end, 22 ′. The correspondingly changed wall structure, 23 ′, however still has slot sets 25 and 26 therein as formed about tool placement opening 24 .
Because of the geometry changes in collet chuck 17 ′ from the geometry of collet chuck 17 , a changed collet nut, 30 ′, is correspondingly provided as shown in FIGS. 4 and 5. Collet nut 30 ′ again has extension opening 33 with threaded interior surface portion 35 thereabout extending into collet nut 30 inward from end 31 , and seal ring opening 34 with threaded interior surface portion 35 thereabout extending inward into collet nut 30 from end 32 thereof. However, clamping structure opening 37 between extension opening 33 and seal ring opening 34 now has no significant tapered interior surface portion 38 thereabout extending between circular shoulder 38 ′ and circular opening constriction ridge 38 ″ which instead are immediately adjacent one another in collet nut 30 ′.
In tightening collet nut 30 onto collet 17 above in FIGS. 1, 2 and 3 , tapered interior surface 38 of collet nut 30 is forced against outer short tapered 5 surface portion 20 of collet 17 but can come against it off center to leave collet 17 with tool 39 canted off center. However, tightening collet nut 30 ′ onto collet 17 ′ here results in the left side of channel 19 of collet 17 ′ being forced against circular shoulder 38 ′ so that the centerline of collet 17 ′ must align with the centerline of collet nut 30 ′, i.e. without any canting.
The same seal ring 40 and O-ring 43 used with collet nut 30 above can be used with collet nut 30 ′ here so that threaded surface 44 can be mated with threaded surface 36 of collet nut 30 ′ so as to be rotatable therein to a position against shoulder 38 ′ in collet nut 30 ′. Pressurized liquid can again be provided in extension 13 to the base of the shaft portion of drill 39 from which it flows through drill liquid transport channel 39 ′, and through the slots in collet 17 ′ and around collet 17 ′ into collet nut 30 ′ but is prevented from leaving collet nut 30 ′ by the mating of threaded surfaces with extension 13 and seal ring 40 . Again, the pressurized liquid is prevented from flowing along the sides of drill shaft 39 by tightly fitted O-ring 43 held thereagainst by sealing ring 40 . The high quality steel and substantial wall thicknesses of extension 13 , collet nut 30 ′ and seal ring 40 are well able to withstand the liquid pressures encountered.
An end view of seal ring 40 is shown in FIG. 6 . There can be seen four small recessed holes, 45 , symmetrically around tool insertion opening 42 on a common position placement circle of a radius larger than that of opening 42 . Pairs of holes 45 are across from one another on a diameter of that common position placement circle. Holes 45 are of a sufficient diameter to accept therein bosses on a spanner wrench to allow tightening of seal ring 40 in seal ring opening 34 of either of collet nuts 30 or 30 ′ against shoulder 38 ′ at the bottom of those openings to assure pressurized liquid does not flow past seal ring 40 where mated with a collet nut.
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
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A seal assembly for a toolholder with a collet clamping member having a forcing ring in which at least in part the clamping member can be positioned, and a seal ring with a tool insertion opening including a surrounding O-ring holder that can be removably engaged with the forcing ring to place this seal ring in a selected position therein. An O-ring is provided in the seal ring O-ring holder.
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FIELD OF THE INVENTION
The invention is directed to an improved structure for a self-adjusting wrench capable of handling a range of sizes of hexagonal bolts or nuts.
BACKGROUND OF THE INVENTION
It is common to employ open end and box wrenches, or wrenches having one adjustable jaw member to grip hexagonal bolts or nuts. In the case of open end and box wrenches, they make good contact with the several flats of hexagonal bolts or nuts, but a different size wrench is required for each size of fastener. The adjustable wrenches have disadvantages in that they generally engage only two of the hexagonal bolt/nut flats and, consequently, are subject to slippage about the fastener, they generally require carefully machined screw-type driving surfaces and must be reversed as between fastening and unfastening operations.
SUMMARY OF THE INVENTION
The disadvantages of the prior art wrenches are overcome in the present invention by providing a wrench which is adjustable to accommodate a range of sizes of hexagonal bolts or nuts and engages all six corners and flats of the fasteners thereby being operative for both fastening and unfastening once positioned. The wrench is provided with pivoted handles which are squeezed together to actuate a plurality of jaw elements which close upon the hexagonal bolts or nuts contacting all six faces of those members.
In more detail, each handle element terminates in an actuating arm portion and the actuating arm portions are moved toward each other as the handle members are squeezed and rotate about the pivot. Each actuating arm is connected to drive lateral jaw members toward a central position. The lateral jaw members associated with each actuating arm are comprised of paired, spaced jaw elements which are joined by a pair of drive pins. The lateral jaw members together cooperate to conform to four faces of a hexagonal bolt or nut as they are driven toward a central position.
Between the paired, spaced jaw elements, upper and lower jaw members are installed and arranged to move toward a central position. The upper and lower jaw members are each provided with a pair of angled slots through which the drive pins joining the paired, spaced lateral jaw elements extend. The upper and lower jaw members are each shaped to provide a surface for contacting one face of an hexagonal bolt or nut.
As the adjustable wrench is placed about a hexagonal bolt or nut and the handle is squeezed, the actuating pins force the lateral jaw members toward a central position, the drive pins secured to the lateral jaw members ride in the slots of the upper and lower jaw members, moving the upper and lower jaw members toward a central position. The net effect of the coordinated movement of the jaw members toward a central position is to close tightly upon the hexagonal nut or bolt lying within the jaw members ready for fastening or unfastening operation.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of the adjustable wrench of the invention in the open position;
FIG. 2 is a view similar to FIG. 1 with the wrench in the closed position;
FIG. 3 is a side view of the wrench with a dotted line showing of an alternate handle shape;
FIG. 4 is a plan view of a lateral jaw element used in the present invention; and
FIG. 5 is a plan view of an upper or lower jaw member used in the present invention.
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1 the adjustable wrench 10 is shown in normally open position having handle members 1 and 2 pivoted at 4 and biased to the open position by spring 5. The handle members 1 and 2 extend beyond the pivot to provide, respectively, at the working end of the wrench, the actuating arms 6 and 7. Actuating pins 8 and 9 are located, respectively, near the ends of actuating arms 6 and 7. Lateral jaw members 12 and 14 each comprise a pair of spaced and paired identical jaw elements 12a, 12b and 14a, 4b joined by a pair of drive pins 16, 17 and 21, 22. As shown in the FIGURES, each drive pin is shown as a double cylindrical pin, but a single drive pin of generally elliptical cross-section could be used as well. The actuating pins 8 and 9 pass through and are joined to lateral jaw members 12 and 14. The upper and lower slotted jaw members, 23 and 27, are sandwiched between the spaced lateral jaw elements of jaw members 12 and 14 with drive pins 16, 17 and 21, 22 passing through slots 24, 25 and 28, 29, respectively. As indicated, there are two slots in each of the upper and lower jaw members 23 and 27 with the slots generally at an angle of 100° from each other with the apex of the angle at the upper end of the upper jaw 23 and at the lower end of the lower jaw 27.
In operation, the handle members 1 and 2 are squeezed together compressing spring 5 and moving actuating arms 6 and 7 and actuating pins 8 and 9 toward each other. The actuating pins 8 and 9 move lateral jaws 12 and 14 toward each other while drive pins 16, 17 and 21, 22 follow cam slots 24, 25 and 28, 29 to move upper and lower jaws 23 and 27 toward each other. With all jaws moving toward a central position, a hexagonal open space 30 is defined between the jaws which decreases in size as handle members 1 and 2 are squeezed together. The wrench will thus lock down on any hexagonal nut or bolt in its size range positioned within space 30. Upon release of squeeze pressure, the spring 5 will return the wrench to normal open position.
The jaw members 12 and 14 are designated "lateral" in the following sense: The vertical axis "A" of the wrench passes between handle members 1 and 2, through pivot 4 and through a hexagonal open space 30 defined between the actuating arms 6 and 7 by cooperating jaw members 12, 14, and 23, 27. The actuating pins 8 and 9 on the actuating arms 6 and 7 are movable toward each other and axis "A" to close upon the hexagonal open space 30. The actuating pins drive the jaw members 12 and 14 laterally toward each other and the vertical axis "A", thereby defining in part the hexagonal open space.
There has thus been described a relatively simple adjustable wrench which is a usefull and effective tool over a wide range of hexagonal nuts and bolts. The manufacture of this wrench is greatly simplified by the fact that the jaw elements 12a, 12b and 14a, 14b forming the lateral members 12 and 14 are identical in shape and size as are the top and bottom jaw members 23 and 27.
The above described embodiments of the invention are illustrative only and modifications thereof may occur to those skilled in the art. Accordingly, this invention is not to be regarded as limited by the embodiments disclosed herein, but is to be limited only as defined by the appended claims.
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An adjustable wrench having a pair of spring-biased pivoted handles and a plurality of jaw members having fastener-contacting faces actuable by squeezing motion of the handles to close upon a range of sizes of hexagonal fastener members.
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TECHNICAL FIELD
This invention relates to a method for producing a needle of plastic, a system for same as well as a needle of plastic, in particular a needle for medical purposes.
PRIOR ART
Needles or cannulas for medical purposes, such as injections of medicine, have been produced in various sizes depending on their intended use. For medicine to be injected frequently, such as several times a day, it is preferred to use the thinnest possible needle taking into account the viscosity of the medicine to be injected. Diabetics injecting insulin several times a day would preferably use a very thin needle, such as from gauge 26 to gauge 30, in order to reduce the pain as well as reduce the tissue damage resulting from each injection. In the present context the term “thin” refers to the diameter of the needle in question. Usually needles and other medical tubings are sized in gauges, wherein gauge 8 corresponds to 4.19 mm, and gauge 30 corresponds to 0.30 mm, for example.
In order to obtain a needle exhibiting the necessary strength for penetrating the skin and subcutis as part of the injection the very thin needles have usually been made from metal. Like many other medical articles it is of interest to produce the needles of a plastic material.
EP 452 595 discloses a method for producing a plastic medical tubing, such as a catheter, wherein a liquid crystalline polymer has been shear-thinned to such a viscosity allowing the melt to flow into and fill a mould. The plastic tubings produced have a gauge size of from 8 to 26, preferably from 14 to 20. The shear-thinning is provided by passing the plastic melt through an orifice before the melt reaches the mould. The patent describes a method for preparing the tubing by extruding the shear-thinned polymer into a mould, and describes further that the polymer melt may be forced under pressure through the orifice and thence directly into the mould.
However, in order to obtain very thin needles of the length relevant for injection of medicine very small volumes of plastic melt is used. It has been found, that merely extruding the melt, optionally under pressure will not result in the moulding of a needle of the dimensions in question with sufficient strength.
Injection moulding systems are often used for the production of large amount of articles. Injection moulding is a periodical process, in which a plastic granulate is being homogenized and melted by heating as well as by mechanical working. The plastic melt is injected into a mould cavity. The mould cavity has a temperature which is controlled to be lower than the melting point of the plastic. Hereby the melt injected into the mould cavity will solidify from the wall of the mould cavity to the centre of the article.
In the known injection moulding systems a screw may be used to the mechanical working of the melt as well as to introduce the melt into the mould cavity at a certain injection speed.
The screw movement or injection stroke is normally set to 1 to 4 times of the diameter of the screw. Hereby a right quality of the melt as well as a uniform shot volume will be ensured. By “shot volume” is meant the amount of melt necessary to at least fill the mould cavity to obtain a needle of predetermined dimensions.
The inertia of the screw as well as the hydraulic pressure transferred to the screw ensures in the known systems a pressure which is sufficient to fill large shot volumes.
However due to the small amount of melt necessary for producing a small article pressure applied to the screw cannot be timely transferred to the melt at the entrance of the mould cavity. The matter is that the hydraulic pressure behind the screw shall build up a pressure from the screw to the entrance of the mould cavity in approximately 1 to 10 msec, which has not been possible in known injection moulding system. Therefore, it has not previously been possible to obtain plastic needles or cannulas for medical purposes, for which the outer diameter of the needle or the cannula is 0.5 mm or less.
Furthermore, needles or cannulas of this diameter having an inner diameter is very thin-walled, a wall thickness of approximately 0.10-0.18 mm. This provides the problem of introducing the melt into the mould cavity in such a short time, that “freezing” of the melt is avoided. By “freezing” is meant that the melt solidifies rapidly due to the small thickness of the material. In case melt freezes in the first part of the mould cavity, the melt will not be able to fill the entire mould cavity and thereby a needle of predetermined dimensions will not be obtained.
By the known methods of injection moulding it has therefore not previously been possible to mould needles or cannulas having a wall thickness of material of approximately 0.10-0.18 mm.
The needles or cannulas are furthermore having a very large L/D ratio (wherein L is the length, and D is the diameter of the article) which further provides the problem of not only requiring a small shot volume but also of filling the “long” mould cavity as compared to a small diameter. Thus, in order to ensure that the mould cavity is filled totally with melt a very precise control of the energy reserve in the melt at the entrance of the mould cavity is necessary.
Certain requirements must be met for needles Or cannulas for medical purposes irrespective of the material used. One requirement is that the needle must not bend during insertion of the needle into the patient. Many plastic needles have lacked sufficiently strength when the diameter of the needle is decreased, so that in practice it has not been possible to use plastic needles for medical purposes unless very large needles, such as needles having a diameter of 1 mm or above.
CORE OF THE INVENTION
One aspect of the invention relates to a method for producing a plastic needle, which needle has two ends, wherein at least the outer diameter of one end is less than 0.50 mm, said needle further having a longitudinal lumen extending between two openings of the needle, in a moulding system having an assembly comprising a feed system and a mould cavity,
said method comprising the following steps:
introducing a melt of plastic into the feed system,
increasing the melt pressure gradually during melt passage through the feed system,
passing the melt into the mould cavity, whereby the melt substantially fills the mould cavity,
cooling the melt in the mould cavity whereby the melt solidifies to a needle, and
removing the needle from the mould cavity.
Another aspect of the invention is a system for producing a hollow plastic needle, having an assembly comprising a feed system and a mould cavity, and further comprising means for introducing a melt of plastic into the feed system, said feed system being arranged for increasing the melt pressure gradually during melt passage through the feed system, and means for passing the melt into the mould cavity, so that the melt substantially fills the mould cavity.
By the present invention it has been found that in order to produce small, thin and elongated articles by injection moulding whereby the shot volume is very small it is required to ensure a high energy reserve in the melt at the entrance of the mould cavity itself.
By gradually increasing the pressure through the feed system it is possible to meet the specific pressure demands at the entrance of the mould cavity in order to mould the thin and elongated articles in spite of the small shot volume, because the melt will then reach a sufficient pressure before it enters the mould cavity.
During injection moulding the melt is in motion in the feed system, i.e. flows, whereby the flow front of the melt has a pressure of approximately 0.1 MPa whereas the pressure in front of the screw is high. Accordingly, a high pressure gradient is present.
The high pressure gradient in the feed system ensures the high energy reserve in the melt. This energy reserve in the melt has the same function as for example a biased spring.
When the melt is introduced into the entrance of the mould cavity the energy reserve in the melt ensures, that the spring effect in the melt when released will substantially fill the mould cavity in a very short time. By “substantially fill” is meant that the mould cavity is filled with melt within predetermined tolerances for needles produced.
Surprisingly, it has been found, that due to the energy reserve in the melt, the high melt pressure in front of the screw can be transferred to the flow front of the melt in approximately 1 msec. Hereby, the solidification or freezing of the melt before the melt actually has substantially filled the entire mould cavity is avoided.
Accordingly, the entire mould cavity will substantially be filled by the melt, so the predetermined length and diameter of the needles is obtained.
A third object of the invention relates to a plastic needle having two ends, said needle being produced by injection moulding from a plastic melt, wherein the outer diameter of the moulded needle in at least one end of the needle is less than 0.50 mm, preferably less than 0.45 mm, said needle comprising a lumen.
Hereby, a plastic needle is obtained having an outer diameter, which diameter is so thin that the pain as well as the tissue damage resulting from injections is reduced. Especially for diabetics who are injecting insulin several times a day the thin needle is useful.
In an embodiment according to the invention the inner diameter of the needle, e.g. the diameter of the lumen, may correspond to at most 60% of the outer diameter of the needle, preferably from 20% to 50% of the outer diameter. Hereby, a high strength of the needle is obtained compared to the size of the inner diameter.
The lumen may be formed in many different ways. In one embodiment according to the invention an insert in the mould cavity corresponding to the lumen of the needle may form the lumen.
In another embodiment the insert may comprise a wire substantially centred in the mould cavity for forming the lumen in the needle. According to the invention the wire may be fixed extending through the entire mould cavity. Hereby, the melt flows around the wire and the lumen is formed.
After the melt has solidified and the needle is formed the wire is removed from the needle. For example, means may be arranged for removing the wire after moulding. The removal of the wire may be carried out before or after the needle leaves the mould cavity.
The pressure is increased gradually through the feed system to meet the specific pressure demands at the entrance of the mould cavity. The pressure increase may be carried out by any suitable means.
In one embodiment the specific design of the feed system, i.e. the geometry of the feed system, leads to an increase of the pressure.
The feed system may be comprised of a long tube having a small diameter, optionally with parts of decreasing diameter.
The diameter of the feed system may be decreased in many suitable ways such as stepwise or continuously. In one embodiment according to the invention the feed system is at least partly of conical shape, or in another embodiment the feed system comprises cylindrical parts of different diameters separated by conical parts, whereby the pressure is increased gradually through the feed system. It is of importance to ensure that a sudden increase of pressure is avoided in the feed system.
The amount of melt being introduced into the feed system shall be of a rate sufficient to fill at least the feed system completely in a predetermined time interval, so the design of the feed system can increase the pressure to a level which is enough for completely filling the mould cavity.
If the rate introduced is too small, the feed system will not be timely filled and accordingly the pressure will not be increased sufficiently to eventually fill the mould cavity.
In cases where the rate introduced is to large, it is not possible to control the increase of the pressure and thereby the complete filling of the mould cavity.
Therefore, the melt is preferably introduced into the feed system with a rate of from 0.10 to 100 ccm/sec, preferably from 1 to 10 ccm/sec.
The feed system and mould cavity may exhibit many different temperatures according to the material used in moulding process. The temperature of the feed system and mould cavity has a direct influence on the viscosity of the melt and thereby the ability of the melt to flow easily through the feed system and the mould cavity. However, the temperature may not be to high as this will influence on the strength of the produced needle.
According to the invention the temperature of the feed system and of the mould cavity may be from 50 to 350° C., preferably from 120 to 140° C. Hereby, the flow length of the melt in the feed system and in the mould cavity is optimal in relation to the strength of the produced needle.
In a preferred embodiment according to the invention a ring gate is arranged in front of the mould cavity, so the melt is introduced into the ring gate before entering the mould cavity. The melt will in this embodiment be completely confluent along the periphery of the ring gate before entering the mould cavity in order to avoid a burr or any other moulding defects due to lack of confluence.
The ring gate may have many different shapes. In one embodiment the ring gate is of a conical shape. When the ring gate have an elongated conical shape, no sudden changes in the thickness of the melt material will occur and the melt flow will not stop.
Especially in cases where a wire is substantially centred in the ring gate and the mould cavity for forming the lumen, the melt may be introduced radially into the ring gate. A suitable balance of the melt in the ring gate is hereby obtained. The melt will flow equally around the wire and will have a uniform flow front and thereby distribution in the mould cavity. Hereby, the produced needle avoid having a burr or any other moulding defects.
In order to avoid that the plastic melt will freeze or solidify in the mould cavity, the melt has to be introduced into the mould cavity in a short time. According to the present invention the mould cavity may be substantially filled in a period of time from 0.1 to 10 msec, preferably from 1 to 2 msec. Hereby, the entire mould cavity will be filled with the melt before it starts to solidify or to freeze.
The plastic needle is preferably produced from a liquid crystalline polymer melt. The material, liquid crystalline polymer, may be used due to the fact, that it has a high degree of molecular orientation. During moulding the molecules of the liquid crystalline polymer melt are aligned substantially in the direction of the main flow of the melt. After solidification of the liquid crystalline polymer the molecular orientation is maintained. This high degree of orientation of the material ensures that the needles obtained exhibits high strength compared to needles made of other plastic materials.
The liquid crystalline polymer may be a polymer comprising monomer units selected from hydroxybenzoic acid, hydroxynaphtoic acid, terephtalic acid, p-aminophenol and p-biphenol alone or in combination.
In an embodiment according to the invention the polymer may be a random copolymer comprising 70-80% hydroxybenzoic acid and 20-30% hydroxynaphtoic acid.
The passage of the melt in the feed system ensures a gradually increase in pressure, the passage furthermore ensures that an optimal orientation of the material particles in the plastic melt is obtained. Hereby, a needle with the necessary strength is obtained.
In order to increase the strength of the needle, the plastic melt may comprise fibre reinforcement. The reinforcement may be selected from glass fibre, carbon fibre, aramid fibre or any suitable fibres.
When the melt comprises fibre reinforcement the viscosity of the melt is increased and thereby it's ability to flow is decreased. For obtaining a sufficient strength of the needle in relation to the viscosity of the melt, the reinforcement fibres may constitute from 15 to 40% by weight of the solid plastic, preferably from 25 to 35%, such as approximately 30%.
DETAILED DESCRIPTION
The invention will be explained more fully below with reference to particularly preferred embodiments as well as the drawing, in which
FIG. 1 is a schematic view of an injection moulding system according to the invention,
FIG. 2 is a schematic view of an assembly comprising the mould cavity and the feed system,
FIG. 3 is a schematic view of the mould cavity and a ring gate,
FIG. 4 is a schematic view of a first embodiment of the feed system according to the invention,
FIG. 5 is a schematic view of a second embodiment of the feed system according to the invention,
FIG. 6 is a sectional view of the ring gate shown in FIG. 3,
FIG. 7 is a schematic sectional view of the plastic needle.
FIG. 8 is a schematic sectional view of the vertical section A—A shown in FIG. 6, and
FIG. 9 is a view of a diagram showing the pressure as function of the time.
All the figures are highly schematic and not necessarily to scale, and they show only parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.
The moulding system 1 may be any injection moulding system suitable for injection moulding of small articles. In FIG. 1 is shown a schematic view of a injection moulding system 1 .
The system 1 comprises a granulate reservoir 2 , which reservoir 2 contains the plastic in a solid phase.
The granulate is at the bottom 3 of the reservoir 2 lead through a feed tube 4 into a chamber 5 . In this embodiment the chamber 5 comprises a screw 6 , which screw 6 is rotated by a driving shaft 7 connected to a motor 8 . An instrument for measuring pressure 9 is connected to the chamber 5 in front of the screw 6 , for monitoring the pressure building by the screw 6 . As the screw 6 rotates the granulate is led towards the entrance of an assembly 10 . During the rotation of the screw 6 the granulate is being heated and becomes a plastic melt. The temperature is monitored by a temperature sensor 11 .
The temperature of the assembly 10 is monitored by a temperature sensor 12 and is controlled to be from 50 to 350° C., preferably from 120 to 140° C. according to the material used in the moulding process. Hereby, the flow length of the melt in the assembly 10 is optimal in relation to the strength of the produced needle.
The assembly 10 is shown schematic in FIG. 2 . The assembly 10 comprises in this embodiment a mould cavity 13 and a feed system 14 .
The melt from the chamber 5 is introduced into the feed system 14 . From the feed system 14 the melt is introduced radially into the mould cavity 13 . In the feed system 14 the melt pressure is gradually increased before the melt enters the mould cavity 13 .
In the embodiment shown in FIG. 2 the pressure is increased due to the distance the melt has to flow. The matter is that the pressure is increased due to the flow resistance of the melt. The pressure is furthermore increased by decreasing the diameter of the feed system 14 . The feed system 14 comprises a first cylindrical part 15 having a first diameter and a second cylindrical part 16 having a second diameter, smaller than the first diameter. The first cylindrical part 15 is separated from the second cylindrical part 16 by a conical part 17 .
The melt pressure in this embodiment is already increased from the start of the feed system 14 and afterwards increased gradually by the passage of the melt through the feed system 14 due to the distance the melt has to flow as well as due to the decreasing of the diameter of the feed system 14 .
The melt pressure is increased sufficiently so the high energy reserve in the melt is ensured. Hereby, the melt pressure can be transferred to the flow front of the melt in approximately 1 msec.
In FIG. 3 is the mould cavity 13 shown separated from a ring gate 18 , the function of the ring gate 18 will be explained more fully below. The melt is in this embodiment introduced radially from the feed system 14 into the ring gate 18 in respect to the melt flow in the mould cavity 13 . The mould cavity 13 comprises a first part 19 having a first diameter and a second part 20 with a second diameter smaller than the first diameter. The first part 19 is separated from the second part 20 by a conical part 21 . The diameter of the second part 20 corresponds to the outer diameter of the needle and is less than 0.50 mm.
A wire 22 is substantially centred in the mould cavity 13 for forming the lumen in the needle. In this embodiment the wire 22 is fixed and extends through the mould cavity 13 and further through the ring gate 18 . Hereby the melt flows equally around the wire during moulding and the lumen is formed in the centre of the needle.
In FIG. 4 another embodiment of the feed system 14 according to the invention is shown. The feed system 14 has in this embodiment a first diameter D entrance at the entrance to the feed system 14 and a second diameter D exit at the exit of the feed system 14 . The diameter of the feed system 14 is in this embodiment gradually decreasing along the entire length L feed system , so the feed system 14 exhibits a conical geometry.
In FIG. 5 is the feed system 14 shown in the same way as in FIG. 2 . In this embodiment the feed system 14 is having two cylindrical parts separated by conical parts. The first cylindrical part 15 is having a diameter corresponding to the diameter D entrance at the entrance to the feed system 14 . The second cylindrical part 16 is having a diameter D middle , which diameter D middle is smaller than the diameter D entrance . At the end of the feed system 14 the diameter corresponds to the diameter D exit , which diameter corresponds to the entrance of the mould cavity. The first cylindrical part 15 is separated from the second cylindrical part 16 by a first conical part 17 . The second cylindrical part 16 is further separated from the mould cavity by a second conical part 23 . The diameter of the feed system 14 is in this embodiment decreased in steps along its entire length L feed system .
In FIG. 6 is a schematic sectional view of the ring gate 18 shown. The arrow B indicates the main melt flow direction in the feed system. The melt is introduced radially into the ring gate 18 (indicated by arrow B) with respect to the melt flow in the mould cavity (indicated by arrow A). A first part 24 of the ring gate 18 , where the melt is introduced, is formed with a large volume around the circumference of the ring gate 18 , whereby the melt is forced to flow firstly along the circumference of the first part 24 filling the large volume with melt before entering a second part 25 of the ring gate 18 . In the second part 25 the melt flows in direction of arrow A. The second part 25 of the ring gate 18 is designed with an elongated conical geometry to avoid any sudden changes in geometry that otherwise could lead to melt stop.
In FIG. 7 a schematic sectional view of a plastic needle 26 is shown. The needle 26 is having a longitudinal lumen 27 extending between one opening 28 at a first end 29 of the needle 26 and a second opening 30 at a second end 31 .
FIG. 8 shows a sectional view of the vertical section A—A of the needle 26 . In this embodiment the needle 26 is round and has an outer diameter D needle as well as an inner diameter D lumen .
A plastic needle being produced according to the invention having an outer diameter of 0.40 mm and a length of 8.00 mm. The needle is further having a lumen with a diameter of 0.16 mm. The wall of the needle is in this embodiment 0.12 mm.
The plastic melt used is a liquid crystalline polymer, which is a random copolymer comprising 73% hydroxybenzoic acid and 27% hydroxynaphtoic acid.
The needle is being produced in an injecting moulding system having an assembly comprising a feed system, a ring gate as well as a mould cavity.
The screw used in the injecting moulding system has a 15 mm screw. The injection moulding system is set to introduce approximately 2.6 ccm of melt into the feed system with an injection speed of 3 ccm/sec. The temperature of the assembly is controlled to 130-140° C.
The geometrical form of the feed system is as follows, an entrance diameter of 4.00 mm, a first cylindrical part with a diameter of 2.50 mm for distance of 449.00 mm, a second cylindrical part with a diameter on 1.60 mm for a distance of 10.00 mm, separated by a conical part for a distance of 10.00 mm.
The diagram in FIG. 9 shows an abscissa and an ordinate. At the abscissa the time is indicated as seconds, and at the ordinate the pressure is indicated as MPa. The diagram shows the melt pressure at the entrance to the feed system as function of the time during filling of the assembly. In the diagram it is shown, that the pressure is being increased gradually for about a second during the melts passage of the feed system. At about 1 sec on the abscissa, the pressure have a high increase due to the small diameter of the mould cavity. The high pressure in the melt will due to the energy reserve be transferred to the flow front of the melt, so the entire mould cavity will be filled before the melt starts to solidify.
Hereby, the pressure of the melt will be increased during passage of the feed system, so the energy reserve in the melt will be sufficient to fill the entire mould cavity in approximately 1 msec. Accordingly, the produced needle will obtain the predetermined size as mentioned before.
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A method and a system is provided for producing a needle of plastic, as well as the needle of plastic which includes a needle for medical purposes. The method for producing the needle includes introducing a melt of plastic into a feed system, increasing the melt pressure gradually during melt passage through the feed system, passing the melt into the mould cavity, whereby the melt substantially fills the mould cavity, cooling the melt into the mould cavity whereby the melt solidifies to a needle, and removing the needle from the mould cavity. Increasing the pressure through the feed system provides for meeting specific pressure demands at the entrance of the mould cavity, thereby moulding thin and elongated articles.
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TECHNICAL FIELD
The invention relates to threaded inserts for plates and in particular for inserts placed within plates having a high directional stress.
There are occasions when attachments must be bolted to plates with the plates having high stresses therein. The threads of a tapped hole create high stress concentrations and accordingly are unacceptable in such an environment. It therefore is known to provide unthreaded openings through the plate and to place threaded inserts therein. While the opening through the plate is larger, the absence of stress concentrations because of threads actually results in a lower stress level. Prior art inserts while not creating the stress concentrations of a threaded opening have produced stress concentrations because of the locking mechanisms used to prevent the insert from rotating when the accessory is bolted thereto.
DISCLOSURE OF THE INVENTION
There is provided a threaded insert arrangement for securing a threaded insert to a plate with that plate having a high directional stress therein. The insert is for later bolting an attachment thereto. A cylindrical opening through the plate receives an insert having a tightly fitting cylindrical body and an internal longitudinally threaded bore. A shoulder on the insert abuts against the inside of the plate which may later be inaccessible when attaching the accessory.
Contiguous with the cylindrical opening and the plate is a restraining recess preferably in the form of a part depth partially cylindrical recess. This recess is located only in line with the directional stress so that it is located at a very low stress region with respect to the stress pattern around the cylindrical opening. A portion of the insert is located so as to be deformable into the restraining recess.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1. shows a fuel nozzle mounted in a highly stressed plate.
FIG. 2 is a detail of the mounting of the fuel nozzle.
FIG. 3 is a detail from the bolted side of the connection showing the orientation of the restraining recesses with respect to the stress field.
FIG. 4 is a section through the threaded insert.
FIG. 5 is a view of the recess.
FIG. 6 is an alternate view using two recesses.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 illustrates the combustor area of a gas turbine engine wherein combustor shell 10 contains high temperature high pressure air 12 in the order of 450 psi pressure and 1000° F. temperature. A fuel injector 14 secured to flange 16 must be bolted into place during construction. For this purpose the combustion shell 10 has a thickened portion 18 with openings therein for the purpose of bolting flange 16 thereto.
Because of the high internal pressure the combustor shell 10 including the thickened portion 18 is highly stressed in the hoop stress direction while stresses are much lower in the other direction. This is particularly so since it is desirable to keep this shell as thin as possible not only to save weight but to avoid stresses caused by thermal transients.
The shell must have a large opening 19 for receiving the fuel injector in addition to whatever openings are required for bolting purposes. The opening 19 through the shell is unavoidable and causes a stress pattern flow around the opening which creates stresses higher than those already existing. While thickening of the material locally provides some relief, it is still of critical importance to avoid any unnecessary stress concentrations which could start local cracking which would propagate to ultimate failure. Threading the openings through the shell would create such unacceptable stress concentrations.
A cylindrical opening 20 is placed through plate 18 at each location where a bolted connection is desired. An insert 22 having a cylindrical body is placed within opening 20 and formed to have a tight fit. Such tight fit is an interference fit of 0.0005 to 0.00035 inches. The insert has a threaded bore 24 longitudinally extending through the insert. It has a shoulder 26 extending beyond the cylindrical body for abutment with plate 18 to secure the insert in that direction not only prior to bolting on the fuel injector but in resisting the force created by the bolting.
As best seen at FIG. 5 the cylindrical opening 20 has contiguous therewith a partial cylindrical recess 28 centered about a line which intersects the central axis parallel to the directional stress. An unthreaded cylindrical extension 30 is located adjacent to the recess and a portion 32 is deformed into the recess. The insert is thereby retained from falling out and also capable of resisting rotation when an attachment is bolted thereto.
FIG. 3 shows the direction of the high hoop stress 34. It is essential that these recesses 28 be in line with the stress path as illustrated by the three openings in FIG. 3. A high stress occurs at the portion of the material adjacent to the openings where the side of the opening is parallel to the stress field. Low stresses exist at the points 90 degrees therefrom. Accordingly, the recess for holding the insert and preventing rotation is placed only at these low stress conditions. Accordingly, an insert is provided which may be held and restrained with a minimum of stress concentrations.
FIG. 6 shows an alternate embodiment having two recesses 36 and 38 which are located 180 degrees apart. Both of these recesses are, however, only in line with the known high directional stress.
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A threaded insert 22 is restrained from rotation by deformation into a recess 28. The recess 28 is only located in line with a directional stress pattern 34 in the receiving member 18 whereby stress concentration is avoided at high stress locations.
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CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] The present application is a divisional of and claims priority to U.S. Non-provisional patent application Ser. No. 12/556,674, filed Sep. 10, 2009, entitled “Mounting Assembly,” naming inventors Andrew Robert Slayne and Simon Alan Hughes, which application claims priority to U.S. Provisional Patent Application No. 61/095,841, filed Sep. 10, 2008, entitled “Mounting Assembly,” naming inventors Andrew Robert Slayne and Simon Alan Hughes, of which both applications are incorporated by reference herein in their entirety.
FIELD OF THE DISCLOSURE
[0002] The present disclosure relates to apparatus comprising mating inner and outer components, which are mounted together using a tolerance ring.
[0003] In an embodiment, the apparatus can be used for mounting an arm on a bearing to form a pivot.
BACKGROUND
[0004] It is known to connect together mating inner and outer components using a tolerance ring. For example, a tolerance ring may be sandwiched between a shaft that is located in a corresponding bore formed in a housing, or it may act as a force limiter to permit torque to be transmitted between the shaft and the housing. The use of a tolerance ring accommodates minor variations in the diameter of the inner and outer components without substantially affecting their interconnection.
[0005] Typically, a tolerance ring comprises a band of resilient material, e.g. a metal such as spring steel, the ends of which are brought towards one another to form a ring. A strip of projections extends radially from the ring either outwardly or inwardly towards the centre of the ring. The projections can be formations, possibly regular formations, such as corrugations, ridges, waves or fingers. The band thus comprises an unformed region from which the projections extend, e.g. in a radial direction. There may be one or more rows of projections.
[0006] In use, the tolerance ring is located between the components, e.g. in the annular space between the shaft and bore in the housing, such that the projections are compressed between the inner and outer components. Typically, all of the projections extend either outwardly or inwardly so that one of the inner and outer component abuts projections and the other abuts the unformed region. Each projection acts as a spring and exerts a radial force against the components, thereby providing an interference fit between them. Rotation of the inner or outer component will produce similar rotation in the other component as torque is transmitted by the ring. Likewise, linear movement of either component will produce similar linear movement in the outer component as linear force is transmitted by the ring.
[0007] If forces (rotational or linear) are applied to one or both of the inner and outer components such that the resultant force between the components is above a threshold value, the inner and outer components can move relative to one another, i.e. the tolerance ring permits them to slip.
[0008] Typically tolerance rings comprise a strip of resilient material that is curved to allow the easy formation of a ring, e.g. by overlapping the ends of the strip.
[0009] During assembly of apparatus with an interference fit between components, a tolerance ring is typically held stationary with respect to a first (inner or outer) component whilst a second component is moved into mating engagement with the first component, thereby contacting and compressing the projections of the tolerance ring to provide the interference fit. The amount of force required to assemble the apparatus may depend on the stiffness of the projections and the degree of compression required. Likewise, the load transmitted by the tolerance ring in its final position and hence the amount of retention force provided or torque that can be transmitted may also depend on the size of the compression force and the stiffness and/or configuration of the projections.
[0010] One example of the use of a tolerance ring is in a hard disk drive (HDD) pivot mount, where the tolerance ring provides axial retention between a rotatable pivot shaft and an arm mounted thereon. In conventional pivot mounts, the tolerance ring provides an interference fit between the arm and a bearing mounted on the shaft. Typically the bearing comprises two pairs of races which are axially separated from each other by a spacer. Since the components in pivot mounts are very small and sensitive, the bearing is often protected by a surrounding sleeve (a “sleeved pivot”). The sleeve often has the spacer machined on its inner surface. In such arrangements the tolerance ring is sandwiched between the sleeve and the arm. Whilst sleeved pivots are less prone to damage and therefore are less likely to adversely affect hard disk drive performance, the precise machining required to form the spacer on the inner surface of the sleeve and the desire to use less material in the manufacture of pivot mounts has led to the introduction of sleeveless pivots.
[0011] In sleeveless pivots, the outer race of each part of races is exposed, and the spacer comprises an annular band located axially (“floating”) between them. The spacer is held in place by an axial pre-loading force exerted on the bearing. In such arrangements the tolerance ring is located between the outer races of the bearing and the arm.
[0012] The coupling between mating components may exhibit resonant behavior, i.e. where external vibrations are amplified in the coupling. The resonant frequency or frequencies of an assembly are important in determining the operation of that assembly. For example, in hard disk drive pivot mounts accurate data writing cannot take place when resonance occurs, so it is important to know the frequency of resonance. The resonant frequency may depend on amount of compression that takes place during installation.
SUMMARY
[0013] At its most general, the present disclosure proposes varying the stiffness of tolerance ring waves around the circumference to even out the compression force experienced by an inner component held within the tolerance ring in use. The stiffness of the waves may provide means for controlling the compression force experienced by the inner component, which in turn may affect the properties of that component.
[0014] In one example, the inner component may be a bearing, e.g. a bearing mounting on a shaft forming part of a hard disk drive HDD pivot. Uneven compression forces exerted by the waves of the tolerance ring may cause distortion of the bearing. This may occur especially if the outward facing wall (e.g. the sleeve or outward facing wall of each race) of the bearing is thin, which is typical in small scale apparatus. Distortion of the bearing can have an effect on the resonant frequency of the pivot joint in use, e.g. by contributing to bearing stiffness and rotation torque profile. By evening out the compression forces experienced by the bearing, distortion can be controlled, e.g. minimized, which may provide greater control over the resonant frequency of the pivot joint in use.
[0015] In one aspect, an apparatus can comprise an inner component, an outer component which mates with the inner component, and a tolerance ring located between the inner and outer components to provide an interference fit there between, wherein the tolerance ring comprising a split ring having a plurality of radially extending projections which are compressible between the inner and outer components, and in which in the stiffness of the projections varies around the circumference of the tolerance ring.
[0016] The tolerance ring may comprise a strip of material that is curved into the split ring configuration. The strip of material may comprise an unformed region from which all the projections extend in the same direction, e.g. either all radially inward or all radially outward. The projections may be press-formed in the strip of material. With this configuration the unformed surface of the tolerance ring abuts one of the inner and outer components, and the projections abut the other of the inner and outer components.
[0017] The stiffness of a projection may be a measure of the force required to deform the projection to a certain radial distance from the unformed surface of the tolerance ring.
[0018] Each projection may be a circumferential hump which extends inwardly or outwardly in the radial direction. Each hump has a circumferential width within which it rises to and falls from a peak. There may be one or more series of humps, axially spaced from one another.
[0019] The stiffness of a projection may be altered by changing its circumferential width. Increasing the width of a projection whilst maintaining its radial height may soften the projection, i.e. decrease its stiffness. Alternatively or additionally, the stiffness of a projection may be altered by changing its radial height. Increasing the height of a projection whilst maintaining its circumferential width may harden a projection, i.e. increase its stiffness. Other methods of altering the stiffness of a projection can include altering the profile of the projection or altering the axial width of the projection. Varying the stiffness of the projections around the circumference of the tolerance ring may be achieved using any one of these techniques or both in combination.
[0020] The variation in stiffness may provide stiffer projections at the gap in the split ring, i.e. towards the ends of the strip of material that are curved towards each other to form the ring. It has been found that the since the projections at the gap are less constrained than those further around the ring they tend to exert lower forces. Stiffening the projections at the gap may enable the force exerted by the ring on the inner component to be distributed more evenly around its circumference.
[0021] The projections may include one or more edge projections located adjacent to the gap and a plurality of body projections around the ring between the edge projections associated with each side of the gap, wherein the edge projections have a higher stiffness than the body projections. Other stiffness profiles may be used. For example, the stiffness of the body projections may increase gradually towards the edge projections. In the HDD environment it is preferred to use a stiffness profile which provides an even force around the inner component. However, other environments may require different stiffness profiles, e.g. a stiffness profile which provides an uneven distribution of force around the circumference. By varying the stiffness of the projections, any type of stiffness profile can be implemented in a controllable and repeatable manner.
[0022] In another aspect, a hard disk drive pivot joint can include an arm having a bore therein, a shaft receivable in the bore, and a tolerance ring located between in the bore between the shaft and arm to provide an interference fit there between, wherein the tolerance ring comprising a split ring having a plurality of radially extending projections which are compressible between the shaft and arm, and in which in the stiffness of the projections varies around the circumference of the tolerance ring.
[0023] The shaft may have a bearing mounted thereon. The projections on the tolerance ring may extend radially outwardly only such that an unformed region abuts an outward facing surface of the bearing, and the projections abut an inward facing surface of the arm within the bore. This configuration may permit the force transmitted through the tolerance ring to be diffused by the unformed region over the outward facing surface of the bearing.
[0024] Hard disk drive pivot joints are small, so the tolerance ring may have a diameter of less than 16 mm in use.
[0025] In another aspect, a pre-assembly apparatus can be used for a hard disk drive pivot joint. The pre-assembly apparatus can comprise a tolerance ring mounted on either one of an arm with a bore therein, the tolerance ring being located in the bore, or a shaft receivable in a bore, the tolerance ring being located around the shaft, wherein the tolerance ring comprising a split ring having a plurality of radially extending projections whose stiffness varies around the circumference of the tolerance ring.
[0026] In one embodiment the pre-assembly comprises a tolerance ring with only radially outwardly extending projections located in a bore formed in an arm. The diameter of the bore may be smaller than the rest diameter of the tolerance ring, whereby the tolerance ring is retainable therein under its own resilience. The projections may engage the inward facing surface of the bore. A outward tapering axial edge may extend from one or both ends of the tolerance ring to act as a guide for an inner component (e.g. shaft) to be inserted into the pre-assembly, i.e. into the centre of the tolerance ring. Insertion of the inner component may deform the tolerance ring to compress the projections and provide an interference fit between the arm and the inner component.
[0027] In yet another aspect, tolerance ring comprising a split ring having a plurality of radially extending projections which are deformable to provide an interference fit between an inner component and an outer component of the pivot, wherein the stiffness of the projections varies around the circumference of the tolerance ring. The tolerance ring can be used in a hard disk drive pivot joint.
[0028] The tolerance ring may have any of the features discussed above with reference to the other aspects of the present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings.
[0030] FIG. 1 shows a plan view of a conventional hard disk drive pivot mount which includes a tolerance ring;
[0031] FIG. 2 shows a cross-section taken along the line X-X of the hard disk drive pivot mount shown in FIG. 1 ;
[0032] FIG. 3 shows a close-up of the coupling between the arm and sleeved pivot of the hard disk drive pivot mount shown in FIG. 1 ;
[0033] FIG. 4 is a exaggerated scale roundness trace of a bearing in a conventional pivot joint without even force distribution;
[0034] FIG. 5 is a schematic diagram illustrating how tightly balls are held in a bearing in a conventional pivot joint without even force distribution;
[0035] FIG. 6 is a schematic diagram illustrating compression force exerted through projections around a tolerance ring which are compressed to the same height for sample tolerance rings with and without projection stiffness modification;
[0036] FIG. 7 is a plan view of a strip of material having projections formed therein for a conventional HDD tolerance ring;
[0037] FIG. 8 is a plan view of a strip of material having projections formed therein for an HDD tolerance ring that is an embodiment of the present disclosure;
[0038] FIG. 9 is a side view of a strip of material having projections formed therein for an HDD tolerance ring that is another embodiment of the present disclosure;
[0039] FIG. 10 is a schematic diagram illustrating the different stiffness characteristics of an edge projection and a body projection according to an embodiment of the present disclosure;
[0040] The use of the same reference symbols in different drawings indicates similar or identical items.
DETAILED DESCRIPTION
[0041] FIG. 1 shows a known hard disk drive pivot mount 30 , which comprises an arm 32 adapted to carry read/write heads and pivot 34 which is rotatable on a bearing about a shaft. A tolerance ring (not shown in FIG. 1 ) provides an interference fit between the pivot 34 and the arm 32 such that the arm rotates with the pivot.
[0042] FIG. 2 shows a cross-section taken along the line 2 - 2 in FIG. 1 . FIG. 2 shows that the arm 32 comprises a circumferential housing 36 which includes a bore in which the pivot 34 is received. The pivot 34 comprises a rotatable sleeve member 42 which is coupled to a shaft 38 via a pair of bearings 40 , 41 . FIG. 2 thus shows an example of a sleeved pivot. The tolerance ring fits between the outer surface of the rotatable sleeve member 42 and the inner surface of the bore formed in the circumferential housing 36 . This is shown in more detail in FIG. 3 , where it can be seen that a tolerance ring 20 having waves 28 substantially aligned with bearings 40 , 41 is compressed between the rotatable sleeve member 42 and circumferential housing 36 .
[0043] In FIG. 3 it can be seen that rotatable sleeve member 42 comprises an integral spacer element 43 which separates the bearings 40 , 41 .
[0044] FIGS. 4 , 5 and 6 help to illustrate the problem that is addressed by the present disclosure. FIG. 4 is a graphical representation of plan view of a bearing wall 50 in an HDD pivot which is distorted in use by a conventional tolerance ring, i.e. a tolerance ring which has uniform projections. The scale is exaggerated to demonstrate the effect. A circular dotted line 52 represents the undistorted edge of the bearing wall. To give an idea of the scale of the distortion, the demarcations 54 on the 0°, 90°, 180° and 270° axes are at intervals of approximately 3 μm. The overall diameter of a bearing is around 15 mm, so the scale of the distortion is small relative to the diameter.
[0045] FIG. 4 shows that the bearing wall is distorted such that it is pushed in further in the 0°-90° quadrant and the 180°-270° quadrant and sticks out in the 90°-180° and 270°-0° quadrants. It has been found that the sticking out in one quadrant occurs at the gap in the tolerance ring. Because the projections at the gap have more freedom of movement they appear to exert a lower force. This freedom of movement is also reflected in looseness at the opposite side of the bearing because the bearing may shift towards the gap to occupy an off centre position where the forces through the projections adjacent the gap and opposite the gap are substantially equal. Thus, there is more play for the bearing wall at the gap and opposite the gap because the forces exerted by the projections in these regions is less than the other quadrants. The difference in the compression forces leads to the bearing wall distortion. The compression across the bearing from projections at the gap in the ring is less than those which are not at the gap.
[0046] FIG. 5 is a diagram showing how the distortion of the bearing wall manifests itself in the forces experiences by the balls held in the bearing's races, i.e. how tightly each ball is held in its race. FIG. 5 shows that there is significant variation of tightness around the circumference of the bearing. There are two tightness peaks, which correspond to the two pushed in areas seen in FIG. 4 . Likewise there are two regions of looseness. These occur at the gap of the tolerance ring and opposite the gap of the tolerance ring.
[0047] FIG. 6 is a graph showing the compression force transmitted through tolerance ring projections that are compressed to a uniform height (in this example 0.29 mm) around the circumference of the tolerance ring. Line 56 is a plot of values obtained from a conventional tolerance ring having uniform projections. The compression force rises to a peak at the projections opposite the gap and is low at the projections adjacent to the gap, i.e. at the projections which less constrained due to the presence of the gap.
[0048] To reduce or minimize the distortion of the bearing wall, a tolerance ring can have projections that exhibit an even compression force around the circumference of the tolerance ring when compressed to a uniform height (e.g. corresponding to a given clearance), as illustrated by dotted line 58 in FIG. 6 .
[0049] To achieve the even compression force it is necessary to vary the stiffness of the tolerance ring projections. Varying the stiffness permits the compression force delivered by a projection to be tailored to its location relative to the gap. To even out the compression force shown in FIG. 6 , the projections at the gap need to provide a stronger compression force for a given clearance, i.e. be stiffer, and the waves in the centre need to provide a weaker compression force, i.e. be less stiff.
[0050] FIG. 7 shows a strip of resilient material 60 , e.g. spring steel, into which a two rows of projections 62 are press-formed, e.g. stamped. The strip 60 may be curved to form a tolerance ring by bring edges 66 , 68 towards one another. The top and bottom edges 64 , 65 are flared outwards (i.e. in the same direction as the projections 62 ) to provide an inwardly tapering guide surface for the tolerance ring. FIG. 7 shows a conventional tolerance ring in that all of the projections have the same size and shape.
[0051] FIG. 8 shows an embodiment of a strip of resilient material 70 having a plurality of projections 72 press-formed therein which, when edges 74 , 75 are curved towards one another so that the strip forms an annular band. The top and bottom edges 76 , 77 are flared outwards as in FIG. 7 .
[0052] Similarly to FIG. 7 , the strip 70 in FIG. 8 has two rows of projections 72 . However, in this embodiment each row has three different types of projection. At (i.e. adjacent) the edges 74 , 75 there is a set of three edge projections 78 . These projections have a narrower width (i.e. smaller circumferential extent) than but the same peak height as the projections 62 shown in FIG. 7 . This means they are stiffer, i.e. exhibit a higher compression force for a given compression distance.
[0053] Circumferentially inwards of each set of edge projections 78 there is a set of two intermediate projections 80 . These projections are wider than the edge projections but have the same height (i.e. peak extension away from the strip) and hence are less stiff than the edge projections.
[0054] Between the sets of intermediate projections 80 is a set of three body projections 82 . The body projections are each wider than an intermediate projection but have the same height and hence are less stiff than the intermediate and edge projections. In this illustrated embodiment the body projections 82 are the same size as the projections in FIG. 7 . This need not be the case. In fact, it may be preferred for the body projections to be less stiff than conventional projections.
[0055] In an embodiment, the difference in stiffness between the edge projections and the body projections can be at least about 2%, such as at least about 3%, even at least about 5%. In certain embodiments, the difference in stiffness between the edge projections and the body projections can be at least about 7%, even at least about 10%. In a particular embodiment, the stiffness of the edge projections can be not greater than about two times the stiffness of the body projections, such as not greater than about 1.9 times, such as not greater than about 1.8 times, even not greater than about 1.7 times. Further, the stiffness of the edge projections can be not greater than about 1.6 times the stiffness of the body projections, even as not greater than about 1.5 times.
[0056] The number and precise size of each type of projection may depend on the particular use. For example, there may be no intermediate projections. There may be only one edge projection in each row at each edge. Moreover, the projections in each set need not be identical. For example, the edge projections could each increase in width towards the intermediate or body projections, e.g. to provide a smooth transition between projection types. Similarly, the body projection may increase in width towards the centre of the strip, i.e. the location opposite the gap in use.
[0057] Although two rows of projections are illustrated, any number of rows may be used. The different types of projections are preferably aligned in all the rows.
[0058] FIG. 9 shows a cross-section through a row of projection on a sheet of material 84 for making a tolerance ring. In this embodiment the widths of each projection in the row is constant, but the peak extension varies. The relative heights of the projections are exaggerated for clarity.
[0059] Thus, at each edge 86 , 87 there is an edge projection 88 which has a greater height (distance from unformed region 84 ) than the inner projections. Circumferentially inwards of the edge projections 88 is a set of two intermediate projections 90 which have an intermediate height. Between the intermediate projections there is a body projection 92 which has a lower height than the intermediate and edge projections. As with FIG. 8 , the number of each type of projection may be different in other embodiments.
[0060] In practice, adjusting the stiffness profile of the projections may be achieved using a combination of the widening effect illustrated in FIG. 8 and the raising of wave height illustrated in FIG. 9 . Other methods may also be used, e.g. altering the cross section shape of the projection by changing the angle of the slope of the hump or the like.
[0061] FIG. 10 is a graph showing stiffness profiles for an edge projection and a body projection to demonstrate how different compression forces are generated for the same clearance, i.e. annular gap between components. The stiffness profile 94 for the edge projection lies above the stiffness profile 95 for the body projection. In this embodiment, within the tolerance region 96 of typically annular clearances in HDD pivot mounts (i.e. between about 0.27 mm and about 0.31 mm) the edge projection exerts a force that is consistently about 50 N greater than the body projection.
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A tolerance ring is disclosed and can include a strip of material having a length, a first end, a second end opposite the first end, and a plurality of radially extending projections between the first and second ends. The strip of material can be curved into a ring having a gap. The radially extending projections are configured to be compressible between a bore and a shaft. A width and/or a height of a radially extending projection closest to the first end is different from a width and/or a height of a radially extending projection closest to a line extending perpendicular to the length and bisecting the strip of material within a circumferential row of the radially extending projections.
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BACKGROUND OF THE INVENTION
The present invention is directed to a hand-held tool for use as a hammer drill, a powered drill or screw driver and the like and has a detachable chuck, for holding tool bits, secured on a rotary spindle. The chuck has a chuck part in inter-engagement with the rotary spindle with a front end part of the spindle located within a socket-shaped section of the chuck part. The chuck is connected with the rotary spindle so that it can be locked for rotation with the spindle.
In hand-held tools of the above type, it is frequently necessary to use the functional mode of one type of tool in another type of tool. For instance, relatively often the striking action of a hammer drill can be switched off and the hammer drill used as a regular drilling tool. To clamp the tool bit required for such conversion, the hammer drill must have a suitable drill chuck which, as a rule, is effected by providing a chuck with an insertion end arranged to receive the hammer drill.
Such retooling involves the disadvantage that the runout and concentricity of the clamped tool bit cannot be assured and, in addition, the transmittal of torque and percussive force occurs with play or backlash. Moreover, the known hand-held tools have a large over-all length.
It was found impractical to replace the entire chuck instead of so-called adapter solutions, since no solution was known to permit the exchange without involving a high expenditure of time and tooling. For instance, the tool chuck disclosed in DE-OS No. 33 10 371 can be detached from the rotary spindle of the hand-held tool only with special effort requiring additional tools. In the known tool chuck, a set screw has to be loosened by a tool and then an adjusting ring must be moved to a specific location whereby the clamping member releases the connection between the chuck and the rotary spindle. In addition, the connection between the chuck and the rotary spindle disclosed in the above patent publication requires a relatively large guidance region for guiding the chuck on the rotary spindle to assure adequate run-out and concentricity.
SUMMARY OF THE INVENTION
Therefore, the primary object of the present invention is to provide a hand-held tool with a chuck capable of being replaced without any additional tools, and where the connection between the chuck and the rotary spindle assures concentricity and the required runout while affording a short overall length.
In accordance with the present invention, a socket-shaped section on the chuck and a front end part of the rotary spindle each have corresponding axially extending conically shaped surfaces which engage with one another. The engaging surfaces are a conically-shaped shaft section and a conically-shaped bore. A recess is formed in an outer surface of the spindle and the recess has a base inwardly of the outer surface face shorter in the axial direction of the spindle than the opening into the recess. Further, the recess has a flank closer to the front end of the spindle inclined from the opening of the recess to the base in the direction toward the rear end of the spindle. A clamping member is located in a radially extending through opening in the socket-shaped section and extends into the recess in the spindle surface. A spring member in engagement with the clamping member holds the clamping member in the recess in engagement with the spindle. A gripping means in contact with the spring member displaces the clamping member into and out of engagement with the recess. The dimension of the clamping member within the recess in the direction of the axis of rotation of the spindle corresponds at most to the least dimension of the recess in the same direction.
Connecting the chuck to the rotary spindle by axially extending conically-shaped support surfaces on the chuck and the spindle provides a concentric engagement free of play assuring concentricity as well as true runout. The over-all length of the tool can be kept small, since the length is governed by the axial dimension of the conically shaped surfaces. To facilitate the disengagement of the support surfaces, the cone angle of the surfaces is located outside of the self-blocking range and is in the range of approximately 25° to 35°. The conically-shaped support surfaces are formed by a conically-shaped shaft section inserted into a conically-shaped bore. Preferably, the shaft section is located on the rotary spindle and the conically shaped bore is located in the chuck.
Advantageously, several clamping members arranged uniformly in a circumferential direction of the chuck are guided in through openings in the chuck and afford backlash-free interengagement of the conically-shaped shaft section in the conically-shaped bore. The clamping members are pressed or biased inwardly by a spring against an inclined flank of the recess in the spindle with the recess located adjacent to the front end of the spindle. The stressing action of the spring is afforded by an external gripping or handling means. The inclined flank in the recess formed in the spindle is inclined at an angle of about 45° to the axis of rotation of the spindle. Because the clamping member abuts against the flank, it does not come in contact with the base of the recess and thus afford an axial force component which provides backlash-free interengagement of the conically-shaped support surfaces. Plural clamping members afford the axial retention of the chuck on the rotary spindle with the transmission of rotational movement being provided by separate and preferable positively locked transmission means, such as interengaged splined surfaces.
It is advantageous to arrange the recess as a circumferentially extending annular groove to facilitate the entry of the clamping members. It is easy to fabricate an annular groove and simplify the connection of the chuck with the rotary spindle, since the chuck can be placed on the spindle in any desired rotational position so that the clamping members can move inwardly into the annular groove independently of the rotational position.
For reasons of simplicity, the clamping members are in the form of balls. Such balls are not only cost effective mass production articles, but further are distinguished by simple functioning and installation because of their shape.
The spring acts on the clamping members in the radial direction to utilize the entire biasing action of the spring without losses through redirection for engagement of the clamping members. Accordingly, it is possible to prevent any jamming effect.
In a preferred embodiment, the spring is formed as an annular member acting on the outer surfaces of the clamping members with the inner side of the spring being prestressed against the socket-shaped section of the chuck for displacing the clamping members inwardly into the annular groove.
It is advantageous if the annular spring is polygonal with the number of corners of the polygonally-shaped spring corresponding to the number of the clamping members. Depending upon the rotational position of the annular spring, the individual side surfaces or corners of the spring can be located opposite the clamping members. The side surfaces of the annular spring rest in a curved manner under prestress at the outer surface of the socket-shaped section of the chuck. With such an arrangement, the clamping members are shifted by the side surfaces of the spring at an appropriate rotational position into the groove. By rotation of the annular spring its corners are moved opposite and are radially spaced from the outer surface of the socket-shaped section into register with the clamping members so that the clamping members can move outwardly into the corners becoming disengaged from the groove. In this position, the chuck can be pulled axially off the rotary spindle without the requirement of any significant force.
In another embodiment, the spring acting on the clamping members is in the form of a cup spring package. A gripping or handling sleeve, rotatable relative to the chuck member, is preferred for actuating the spring. The annular spring can be fixed axially on one side and nonrotatably relative to the gripping sleeve. The axially exposed segment of the spring acts on the clamping members. If cup spring packages supported in the through openings are used, the cup spring packages are actuated by means of a sliding shoe in contact with the radially inner surface of the gripping sleeve.
In one embodiment of the invention, the inner surface of the gripping sleeve contains recesses or depressions corresponding to the number of clamping members. In the circumferential direction, a portion of the depressions are of an increased depth. In the rotational position of the gripping sleeve when the increased depth of the depressions are not located radially opposite the clamping members, the surface of the depressions presses the cup spring packages radially inwardly and biases the clamping members into the groove in the rotary spindle affording the desired backlash-free clamping of the conically-shaped support surfaces on the chuck and the rotary spindle. By an angular displacement via the gripping sleeve with the increased depth section of the depressions being located opposite the cup spring packages, the cup spring packages are released rebounding outwardly and the clamping members can then disengage from the groove permitting the chuck to be removed.
Snap-in means can be provided for locking the gripping sleeve in its different positions. Such snap-in means can be in the form of spring biased balls, supported radially displaceably in the gripping sleeve for movement into snap-in openings in the outer surface of the chuck. Further, blocking means limiting the turning of the gripping sleeve from one position to the other can be provided.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWING
In the drawing:
FIG. 1 is a side elevational view of a hand-held tool with a tool bit chuck embodying the present invention;
FIG. 2 is an enlarged view, partially in section, of the chuck shown in FIG. 1 clamped to a rotary spindle in the tool;
FIG. 3 is a sectional view taken along the line III--III in FIG. 2;
FIG. 4 is a view similar to FIG. 2, however, illustrating the chuck released from the rotary spindle;
FIG. 5 is a sectional view taken along the line V--V in FIG. 4;
FIG. 6 is an axially extending sectional view of another embodiment of the tool bit chuck clamped to the rotating spindle of the present invention;
FIG. 7 is a sectional view taken along the line VII--VII in FIG. 6; and
FIG. 8 is a sectional view, similar to FIG. 7, however, showing the chuck released from the rotary spindle.
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, a hand-held tool is shown comprising a housing 1 having a front end located on the left and a rear end on the right. A handle 2 extends downwardly from the rear end of the housing. A trigger-like switch 3 is located in the handle 2 for switching on and off the hand-held tool. A chuck 4 is located at the front end of the housing 1 detachably connected to a rotary spindle 5 extending in the front end--rear end direction of the housing with the front end of the spindle projecting axially from the front end of the housing. In the following description and in the claims, the front end and rear end of certain parts of the invention are mentioned with the front end being the left-hand end in FIGS. 1, 2 and 4 and the rear end being the right-hand end. The rotary spindle 5 has an axis of rotation extending in the front end-rear end direction.
Chuck 4, shown on an enlarged scale in FIG. 2, includes an axially extending chuck part 6 at the rear end. An adjusting sleeve 7 for clamping jaws 8 is located between the front end and rear end of the chuck with the clamping jaws projecting axially at the front end of the chuck. A gripping sleeve 9 encircles the rear part of the chuck extending around the chuck part 6. An annular sleeve 11 is fixed at its front end within the gripping sleeve 9 and extends rearwardly around the rear end of the chuck part 6. Chuck part 6 includes an axially extending socket-shape section 12 forming a conically-shaped bore 13 with the bore being open toward the rotary spindle 5. A blind stepped cylindrical bore 14 extends from the front end of the conically-shaped bore 13 toward the front end of the chuck. At its rear end, the socket-shaped section 12 has three through openings 15 extending into the rear end of the bore 13. As can be seen in FIG. 3, the openings 15 are equiangularly spaced apart in the circumferential direction of the chuck part 6. A locking member or ball 16 is located in each of the openings 15. The radially outer surfaces of the balls 16 bear against the axially extending rear section of the annular spring 11.
In the direction toward the front end of the chuck 4, the chuck part 6 has snap-in depressions 17 in its outer surface for the engagement of a spherical snap-in member 18 so that the gripping sleeve 9 can be secured against rotation relative to the chuck part 6. The snap-in member 18 is supported in a tranversely extending blind bore 19 extending outwardly from the inner surface of the gripping sleeve 9 and a compression spring 21 is located within the bore and biases the member 18 radially inwardly. Rotary spindle 5 has an axially extending central bore 22, note FIGS. 3 and 5, containing a percussion transmission set 23. For the transmission of rotational movement, a set of axially extending splines 24 are located in the outside surface of the spindle at the rear end of the gripping sleeve 9 and the splines interengage with a matching set of corresponding splines 25 formed at the inside surface of the chuck part 6 at its rear end. The axially extending front end part 26 of the rotary spindle 5 forms a conically-shaped shaft section 27 having a cone angle corresponding to the cone angle of the conical bore 13. The conically-shaped shaft section 27 is bounded at its rear end by a circumferentially extending annular groove 28. The groove 28 has an opening in the surface of the spindle and a base spaced inwardly from the outer surface. The axially extending dimension of the groove 28 is greater at the opening than at the base and the reduced axial length of the base is effected by the slope of the flank 29 located closer to the front end of the spindle. When the conically-shaped shaft section 27 of the spindle 5 is inserted into the conically-shaped bore 13, the locking members or balls 16 under the action of the prestressed annular spring 11 abut against the flank 29 and are spaced outwardly from the base of the groove so that a backlash-free clamping of the shaft section 27 in the bore 13 is obtained.
As can be seen in FIGS. 3 and 5, the annular spring 11 has a polygon shape. Sides 31 of the spring are curved outwardly under prestress and contact the outer surfaces of the socket-shaped section 12 pressing the balls 16 radially inwardly into the annular groove 28 in the rotational position of the spring as shown in FIGS. 2 and 3. As can be seen in FIGS. 3 and 5, the annular spring is in the form of an equilateral triangle made up of three arc-sides 31 with three corners 32 spaced radially outwardly from the outside surface of the socket-shaped section 12. When the spring 11 is moved from the position in FIGS. 2 and 3 into the position in FIGS. 4 and 5, the corners 32 move into alignment with the balls 16, and the balls can move radially outwardly out of the annular groove 28 into contact with the corners. In this rotated position of the annular spring achieved by rotating the gripping sleeve 9 relative to the chuck 4, the chuck can be pulled in the axial direction off the shaft-shaped section 27 of the spindle 5 without any significant force and without the use of any additional tool and it also can be moved in the opposite direction onto the front end of the rotary spindle 5. When the clamp is inserted onto the front end of the spindle, the chuck can be clamped by rotating the gripping sleeve 9 and the spring 11 through 60° back to the position shown in FIGS. 2 and 3.
In FIGS. 6-8, a chuck 41 is shown suitable for rotary and percussion operation. Chuck 41 is positioned on the front end of a rotary spindle 42.
Chuck 41 includes a chuck part 43 with a gripping sleeve 44 located on an axially extending section of the rear end of the chuck part. Chuck part 43 has a axially extending cylindrical bore 45, and a portion of the bore at the front end of the rotary spindle 42 has a axially extending conically-shaped section 46 for engagement with a correspondingly-shaped axially extending surface on the front end of the rotating spindle 42. Accordingly, for backlash-free centered engagement, the front end of the rotating spindle 42 has a conically-shaped shaft section 47.
A percussion transmittal set 48 extends axially through the hollow rotating spindle of 42, and provides rotational motion to the rotary spindle and also affords percussive force to a tool bit 49 positioned within the axially extending bore 45 in the chuck part 43.
The rotatable percussion transmittal set 48 has axially extending entrainment grooves 51 in its outer surface in which axially extending roller-shaped locking members 52 are positioned. The locking members 52 are supported, radially outwardly of the set 48, in through openings 53, in the rotary spindle 42. Accordingly, the locking members 52, held in the engaged position by a rotatable support ring 54, transmit the rotational motion from the set 48 to the rotary spindle 42.
An axially extending section of the rotary spindle 42 engaged in the chuck part 43 has a circumferentially extending annular groove 55 with the base of the groove being axially shorter than the opening into the groove in the outer surface of the spindle. The reduced axial extent of the groove at its base is implemented by the slope of the groove flank 56 located closer to the front end of the spindle. Depressions 57 located diametrically opposite one another are machined into the outer surface of the rotary spindle between the annular groove 55 and the front end of the spindle. The depressions 57 extend in the axial direction of the spindle 42.
Chuck part 43 has an axially extending sleeve-shaped section 58 in which an axial extending section of the front end of the rotary spindle 42 is received. The section 58 has bores 59 extending transversely of the axial direction of the spindle. A ball 61 is displaceably supported in each of the bores 59 and is biased by a cup spring package 62 in the radially inward direction. Radially outwardly, the cup spring package 62 is in abutment with a sliding shoe 63 with the radially outer surface of the shoe located adjacent the inner surface 64 of the gripping sleeve 44. In the position shown in FIGS. 6 and 7, the cup spring package 62 is stressed and presses the ball 61 radially inwardly against the flank 66 within the annular groove 55. This interconnection affords a backlash-free clamping of the shaft section 47 of the spindle 42 in the conically-shaped surface 46 of the chuck part 43.
Axially extending roller-shaped locking members 65 engage in the depressions 57 in the radially outer surface of the rotary spindle 42, and are supported within openings 66 in the chuck part 43 so that the locking members are radially displaceable. Locking members 65 bear radially outwardly against the inside surface of the gripping sleeve 44. Circlips 67, 68 are located in the inner surface of the gripping sleeve 44 and in the outer surface of the rotary spindle 42, respectively, and prevent the axial displacement of the gripping sleeve 44 and the support ring 54.
Stop ring 69 is threaded onto the axially extending front end region of chuck part 43. An elastic ring 71 is located within the front end of the chuck part 43 for providing a sealing action about the tool bit 49. A feed cuff 72 is displaceably supported on the chuck part 43. Feed cuff 72 laterally and axially encircles the chuck part. A cylindrical spring 73 encircles the chuck part 43 and biases the feed cuff 72 against a stop ring 69 located at the front end of the chuck 41. Another elastic ring 74 is located between the feed cuff 72 and the chuck part 43 and dampens the impact blow of the feed cuff. Roller-shaped locking members 76 are supported in openings 75 extending through an axially extending front portion of the chuck part 43 and the locking members are radially displaceable. Locking members 76 can be shifted into axially extending entrainment grooves 77 in the surface of the tool bit 49 for retaining the tool bit and transmitting rotational movement to it. The inside surface 78 of the feed cuff 72 opposite the locking members 76 as viewed in FIG. 6, projects radially inwardly relative to the inside surface at the front end of the feed cuff. The surface 78 holds the locking members 76 in the grooves 77 in the tool bit. To disengage the locking members 76, the feed cuff is displaced in the axial direction toward the rear end of the tool against the force of spring 73 so that the locking members 76 reach the increased diameter section at the front end of the feed cuff so that the locking members 76 can move radially outwardly releasing the tool bit for removal from the chuck 41.
FIGS. 7 and 8 show the cooperating relationship of the gripping sleeve 44 with the cup spring packages 62. The radially inner surface 64 of the gripping sleeve 44 has a control depression 79 extending in the circumferential direction around the axis of the spindle and at one end the depressions have an increased depth section 81 for releasing the cup-shaped packages so that they no longer bias the balls radially inwardly and affording disengagement of the balls 61 out of the grooves 55. In the position of the depression 79 shown in FIG. 7, the increased depth section 81 is located out of alignment with the shoes 63, accordingly, the cup spring packages are pressed inwardly and hold the balls 61 in the annular groove 55. By rotating the gripping sleeve 44 in the clock-wise direction, as viewed in FIGS. 7 and 8, the increased depth sections 81 in the depressions 79 are aligned in the radial direction with the sliding shoes 63, note FIG. 8, releasing the balls 61 from engagement with the annular groove 55.
Accordingly, the chuck 43 can be removed from the front end of the spindle 42.
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.
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A hand-held tool for use as a powered drill or screw driver, has a chuck for holding a tool bit, and the chuck is replaceable without employing another tool. A conically shaped shaft section on a rotary spindle fits into a conically shaped bore in a socket section of a part of the chuck. The shaft section and chuck part are secured together by clamping members held in place by a spring. The interconnection affords concentricity and true runout. The rotary spindle is provided with a recess or groove in its outer surface. The groove has an inclined flank closer to the front end of the spindle and the clamping members is biased by the spring against the flank. The spring is displaceable by a gripping sleeve between the biasing position and a released position.
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FIELD OF THE INVENTION
This invention relates to a metal cutting tool consisting of a tool holder and at least one cutting insert releasably retained within a pocket formed in the tool holder.
BACKGROUND OF THE INVENTION
With such a cutting tool, the or each cutting insert is releasably retained in a respective pocket formed in a tool holder by, for example, a clamping screw which extends through a central hole formed in the insert into an appropriate tapped bore formed in the tool holder or, alternatively, by some other suitable clamping system. In many cases, a metal shim is interposed between the insert and the bottom wall of the tool holder pocket, this shim serving to protect the tool holder proper from excessive wear or damage through use. Additionally, shims of differing heights can be employed so as to vary as required the specific location of the cutting insert with respect to the tool holder and in particular that of the cutting edge. In most cases where such shims are employed with screw bolted inserts, the shim is retained in position in the pocket by means of the same screw used to secure the insert, which screw passes through an aperture formed in the shim aligned with the bore of the insert. It will be readily appreciated that this method of securing the shim to the tool holder is inconvenient, particularly in view of the fact that during replacement of an insert, the shim is no longer secured to the holder and can either become lost or forgotten when the operator may forget to replace the shim.
In order to overcome this problem, and also to ensure that the shim is effectively secured to the tool holder even when the insert is retained by means other than a through-going bolt, it has been proposed, particularly in connection with milling tools, to retain the shim in position with respect to the tool holder quite independently of the releasable retention of the insert, and this by means of a special retaining pin which is inserted into the tool holder and retains the shim in position. It has been found in practice, however, that the retaining pin often becomes broken and this in itself can have undesirable consequences in the use of the cutting tool. Additionally, with shims so retained, difficulties are often encountered in releasing the shim for replacement and such replacement may become time consuming.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide a metal cutting tool with new and improved means for the retention thereon of the insert seating shim.
It is an object of the present invention to provide a metal cutting tool with new and improved means for the retention thereon of a replaceable cutting insert.
As used in the present specification, the term "replaceable element" shall be deemed to include both the replaceable cutting insert and also a replaceable insert shim where such is provided.
According to the present invention there is provided a metal cutting tool comprising a tool holder; a pocket in said tool holder defined by a pair of side walls and base walls; an elongated, tubular recess formed in said tool holder and opening into said pocket; a replaceable element having outer, base and side surfaces and a split, tubular coupling portion formed integrally with one of said surfaces and insertable, upon spring-like compression thereof, into said tubular recess so as to be retained therein.
In accordance with a preferred embodiment of the present invention, the replaceable element is constituted by an insert seating shim having an outer, substantially planar face upon which the insert is to be supported.
In accordance with another embodiment of the present invention, the replaceable element is constituted by a cutting insert.
Thus, with a metal cutting tool in accordance with the invention, the insert seating shim or cutting insert is integrally formed with means (the split, tubular coupling portion) facilitating its ready, secure, releasable mounting in the tool holder pocket without the necessity of providing for separate retaining means.
BRIEF SUMMARY OF THE DRAWINGS
For a better understanding of the present invention, and to show how the same may be carried out in practice, reference will now be made to the accompanying drawings, in which:
FIG. 1 is a perspective view of a rotary milling head (prior to the mounting thereon of cutting inserts) and constituting a cutting tool in accordance with the present invention;
FIG. 2 is a perspective view of the milling head shown in FIG. 1 with the cutting inserts mounted into position;
FIG. 3 is an exploded view on an enlarged scale of a detail of the cutting tool shown in FIG. 2;
FIG. 4 is a partially sectioned side elevation of the insert seating shim shown in FIG. 3;
FIG. 5 is a plan view from above of the seating shim shown in FIG. 4;
FIG. 6 is a side elevation of a further form of insert seating shim in accordance with the invention;
FIG. 7 is a front elevation of the seating shim shown in FIG. 6;
FIG. 8 is a plan view from above of a modified form of the seating shim in accordance with the present invention;
FIG. 9 is a side view of the seating shim shown in FIG. 8;
FIG. 10 is a side view of a milling head with a cutting insert shown seated on a seating shim as shown in FIGS. 8 and 9 of the drawings;
FIG. 11 is a cross-sectional view of a portion of the milling head shown in FIG. 10 taken along the line XI--XI;
FIG. 12 is a plan view of a seating shim blank;
FIG. 13 is a side view of the seating shim blank shown in FIG. 12;
FIG. 14 is a side view of the seating shim formed from the blank shown in FIGS. 12 and 13;
FIG. 15 is an exploded view corresponding to that shown in FIG. 3 of the drawings, wherein a modified form of seating shim and tool holder are shown;
FIG. 16 is a perspective view of a still further form of seating shim;
FIG. 17 is a plan view from above of a cutting tool incorporating a seating shim as shown in FIG. 16 of the drawings; and
FIG. 18 is a longitudinally sectioned view of the cutting tool shown in FIG. 17 taken along the line XVIII--XVIII.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Reference will now be made to FIGS. 1, 2 and 3 of the drawings, which illustrate the application of the invention to a cutting tool in the form of a substantially standard milling cutter head 1 which is formed with a plurality of peripherally distributed recesses 2, each recess having formed therein an insert retaining pocket 3 shown clearly in FIG. 3 of the drawings. Each pocket 3 is defined by a pair of side walls 4 and 5 and a base wall 6. An elongated tubular recess 7 is formed at the junction of the side wall 5 and the base wall 6 and opens into the pocket 3 via an elongated slot 8 which is codirectional with the linear junction of the side wall 5 and the base wall 6. Extending centrally into the base wall 6 is a tapped aperture 9.
An insert seating shim 11 is constituted by a substantially rectangular planar base portion 12 having outer, base and side surfaces and which substantially corresponds in shape and area to the base wall 6 of the pocket 3 and in which is formed a central, through-going aperture 13. Formed integrally with a side edge of the base portion 12 is a split, tubular side portion 14 which is coextensive with the edge to which it is connected.
In order to retainably locate the seating shim 11 in position in the pocket 3, the tubular side portion 14 is springily compressed and is inserted into the tubular recess 7 with the planar portion 12 projecting through the elongated slot 8. In this position, the seating shim 11 is securely retained within the pocket and is ready to have placed thereon a cutting insert 15 which is clamped thereto and to the milling head by means of a clamping screw 16. FIG. 2 shows the milling head provided with cutting inserts, each of which is seated on a seating shim of the kind shown and described with reference to FIG. 3 of the drawings.
FIGS. 6 and 7 of the drawings show a modified form of seating shim 21 having, as before, a substantially planar, rectangular base portion 22 and a split, tubular side portion 23. Additionally, the seating shim is formed integrally with an edge thereof perpendicular to the tubular side portion 23 with an abutment shoulder 24 against which an insert 25 is designed to abut when the shim is retainingly placed in position in the pocket 3.
In the embodiment shown in FIGS. 8 through 11 of the drawings, the seating shim is, as in the embodiment shown in FIGS. 6 and 7, provided with an insert abutment shoulder but in the case of this embodiment, the abutment shoulder is constituted by a portion of the split, tubular side portion. As seen in FIGS. 8 through 11, an insert seating shim 31 comprises a substantially rectangular base portion 32 having a through-going aperture 33 and having a split, tubular side portion 34 formed integrally with a side edge thereof. As distinct from the embodiment previously described, in the present embodiment the tubular side portion 34 is not coextensive with the edge of the base portion with which it is integral, but is constituted by a first section 35 which is formed integrally with a portion of the side edge of the base portion 32 and a second section 36 which projects beyond the side edge of the base portion 32. As seen in FIG. 11 of the drawings, a tool pocket 3' is formed with an inwardly extending tubular recess 37 into which the tubular side portion section 36 is inserted so as to retain in position the shim 31 within the pocket 3'. As can be clearly seen in FIG. 10 of the drawings, with this construction the tubular side portion section 36 constitutes an abutment shoulder for an insert 15 which rests on the seating shim 31 and is secured thereto by the clamping screw 16.
Whilst in the embodiments specifically described above, the seating shim together with its integrally formed side portion are produced by suitable casting, in the embodiment shown in FIGS. 12, 13 and 14 of the drawings a seating shim blank 41 constituted by a substantially rectangular base portion 42, with which is integrally formed a side blank 43 also of substantially rectangular shape. The side blank 43 is joined to the base portion 42 via an intermediate tapering portion 44. As can be clearly seen in FIG. 14 of the drawings, when the side blank 43 is bent into a substantially circular shape, it effectively constitutes the split, tubular side portion which can be used, upon insertion into a corresponding tubular recess, for the retention of the seating shim in the pocket.
In the modification shown in FIG. 15 of the drawings, a seating shim 51 is formed with a split tubular coupling element 52 which is integral with a corner of the seating shim 51 via a neck portion 53. As before, a tool holder 54 is formed with a retaining pocket 55 defined by a base wall 56 and a pair of side walls 57 and 58. At the intersection of the walls 57 and 58 is formed a tubular recess 59 which opens into the pocket via a narrow slot 60.
In order to retainably locate the seating shim 51 in position in the pocket 55, the tubular coupling element 52 is springily compressed and is inserted into the tubular recess 59 with the neck portion 53 projecting through the slot 60. In this position, the seating shim 51 is securely retained within the pocket 55 and is ready to have placed thereon a cutting insert 61 which is clamped thereto and to the tool holder 54 by means of a clamping screw 62.
In the further modification shown in FIGS. 16, 17 and 18 of the drawings, a seating shim 65 is formed with a central, downwardly depending, split tubular coupling element 66. A tool holder 67 (in this example, of a turning or grooving tool) is formed with a pocket having a base wall 68 and a pair of side walls 69 and 70. A tubular recess 71 is formed in the base wall 68 corresponding in crosssectional shape to that of the coupling element 66, this tubular recess being coaxial with and constituting an extension of a tapped clamping bore 72.
The seating shim 65 is placed in position within the pocket by springily compressing the tubular coupling element 66 which is then inserted into the correspondingly shaped tubular recess 71 to prevent relative rotational displacement of the seating shim 65 with respect to the tool holder 67. A cutting insert 73 is placed on the seating shim 65 with a pair of side walls thereof abutting the side walls 69 and 70 of the pocket. The insert 73 and seating shim 65 are then clamped in position by means of a clamping screw 74 which is screwed into the clamping bore 72.
Whilst in the embodiments specifically described and illustrated above the seating shim has been provided with a throughgoing aperture it will be readily appreciated that this is not essential seeing that retention and clamping is quite independent of a throughgoing screw or bolt. Furthermore, whilst the invention has been specifically described when applied to milling tools the invention is equally applicable in the case of other cutting tools such as those used in turning, drilling and parting off operations and the like.
Although the invention has been specifically described as applied to an insert seating shim, the principle underlying the retention means as described with reference to the seating shim can be readily applied to the retention of the cutting insert itself. Thus, the cutting insert can be provided with an integrally formed split tubular coupling element which can be retained within a corresponding tubular recess formed in the tool holder. In this connection, inserts with integrally formed, split tubular coupling elements corresponding in general shape to the shims shown in FIGS. 4, 5; FIG. 15; and FIGS. 16, 17 and 18, can be employed.
It will be readily appreciated that, by virtue of the specific construction of the seating shim in accordance with the present invention and its use in conjunction with metal cutting tools provided with an appropriate recess for receiving the integrally formed tubular attachment of the seating shim, the disadvantages accompanying the use of known seating shims, such as the necessity for providing separate attaching means, are completely avoided or overcome.
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A metal cutting tool having a tool holder and a pocket formed in the tool holder in which an insert is to be replaceably retained, there being formed in the tool holder an elongated tubular recess which opens into the pocket and there being furthermore provided a replaceable element having a split tubular coupling portion formed integrally therewith so as to be insertable upon spring-like compression into the tubular recess. This replaceable element is preferably constituted by an insert seating shim.
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FIELD OF THE INVENTION
The present invention relates to a head slider which is used in a magnetic disk drive or the like. The head slider mounts a recording/reproducing element and is also arranged on a recording medium to fly over the recording medium owing to the airflow generated by movement of the recording medium.
In more specific, the present invention relates to a head slider having projections at the sliding surface, which are suitable for avoiding the stiction between the head slider and the recording medium.
BACKGROUND OF THE INVENTION
FIGS. 1 ( a )-( c ) show a magnetic head slider of the prior art. In the prior art, the magnetic head slider has floating rails 41 and 42 , in the longitudinal direction, just opposed to a magnetic disk 3 when it is built into a magnetic disk drive. The magnetic head slider flies over the magnetic disk 3 when the airflow generated by rotation of the magnetic disk 3 enters into an air inflow end 5 and affects the floating rails 41 - 43 , and then conducts the recording/reproducing operation to and from the magnetic disk 3 with an electromagnetic transducer 2 arranged at the area near the air outflow end 7 .
It is effective to reduce the contact area of the magnetic head slider in order to prevent the stiction at the time of contacting with a CSS (Contact Start Stop) zone, therefore, projections 61 - 64 are provided on the rail surfaces of the floating rails 41 and 42 . As shown in FIG. 1 ( b ), in order to effectively prevent the stiction while the projections 61 - 64 are contacting with the magnetic recording, the height H of the projections 61 - 64 must be necessarily at least 20 nm for the magnetic disk 3 having Ra (average roughness) of about 2 nm. It has been verified experimentally that the stiction cannot be prevented if the height H is less than such value.
However, the prior art explained above has following disadvantages. The magnetic head slider takes a flying condition that the flying height of the air inflow end 5 is higher than one of the air outflow end 7 as shown in FIG. 1 ( c ). If the electro-magnetic transducer 2 is attempted to be located near the magnetic disk 3 by reducing the flying height δ of the magnetic head slider in view of enhancing the recording/reproducing sensitivity, the projections 63 and 64 near the air outflow end 7 may interfere with the surface of the magnetic disk 3 . Moreover, in order to prevent the interference of the projections 63 and 64 , it is thought to set up the pitch angle of the magnetic head slider, but it is disadvantage in the viewpoint of balance of the flying condition.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a head slider suitable for preventing the stiction to a recording medium.
It is another object of the present invention to provide a head slider which realizes the small flying height while preventing the stiction to a recording medium.
It is further object of the present invention to provide a head slider which achieves the small flying height and improves the recording/reproducing sensitivity to a recording medium.
The objects explained above can be achieved by a head slider which mounts a recording/reproducing element and flies over the recording medium with the airflow generated when the recording medium moves. This head slider comprises a slider body having the air inflow end and an air outgoing end, a rail which is projected from the slider body to define an air bearing surface extended to the outflow end, a projection formed on the rail and between the inflow end and the outflow end, and a recess formed at the outflow end of the rail to make narrow the width of the rail.
According to the present invention, when the recording medium stops to move, the head slider and the recording medium are in contact each other at the projection and the air outflow end of the rail. Since the air outflow end of the rail is rather narrow in width, the stiction can be prevented. Moreover, it is no longer required to form a projection near the outflow end of the rail and therefore the flying height of the recording/reproducing element can be lowered to improve the recording/reproducing sensitivity.
According the other aspect of the present invention, the width of the recording/reproducing element at the surface opposed to the recording medium is narrower than the width of the outflow end of the rail. According to this aspect, the recording/reproducing element is never exposed to the side wall of the recess of the rail and thereby the corrosion of the recording/reproducing element can be prevented.
According to still another aspect of the present invention, the rail comprises a couple of rails, and the width of one rail, where the recording/reproducing element is formed, at the outflow end is wider than the corresponding one of the other rail. According to this aspect, the width of the outflow end of the one rail is set so that the recording/reproducing element is never exposed. Moreover the width of the outflow end of the other rail can be set so that the stiction never occurs.
Moreover, according to still further aspect of the present invention, the recess isolates an area, where the recording/reproducing element is formed, from the air bearing surface of the rail and thereby the area is formed like an island. According to this aspect, the phenomenon that the lubricant creeps up can be prevented, therefore, the stiction can be prevented effectively.
Moreover, according to still further aspect of the present invention, a forward projection and a backward projection are provided on the rail. According to this aspect, the area in which the head slider is in contact with the recording medium can be reduced, therefore, the stiction can be prevented effectively. Namely, the head slider is in contact with the recording medium in the following three condition, first the inflow end and the forward projection, secondly the forward projection and the backward projection, and thirdly the backward projection and the outflow end are in contact with the recording medium. Even in any type of contact condition, the contact area between the head slider and recording medium can be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 ( a )-( c ) show a head slider of the prior art.
FIG. 1 ( a ) is a front elevation viewed from a side of the floating rail forming surface,
FIG. 1 ( b ) is a side elevation illustrating the contacting condition to the magnetic disk, and
FIG. 1 ( c ) is a side elevation illustrating a flying condition.
FIGS. 2 ( a )-( c ) show a head slider of the present invention.
FIG. 2 ( a ) is a front elevation viewed from a side of the floating rail forming surface,
FIG. 2 ( b ) is a side elevation illustrating the contacting condition to the magnetic disk, and
FIG. 2 ( c ) is a cross-sectional view along the line 1 C— 1 C of FIG. 2 ( b ).
FIGS. 3 ( a )-( c ) show an electro-magnetic transducer.
FIG. 3 ( a ) is a front elevation viewed from a side of the air outflow end,
FIG. 3 ( b ) is a cross-sectional view along the line 2 B— 2 B of FIG. 3 ( b ), and
FIG. 3 ( c ) is a cross-sectional view along the line 2 C— 2 C of FIG. 3 ( a ).
FIGS. 4 ( a ) and 4 ( b ) show a modification example of the electromagnetic transducer.
FIG. 4 ( a ) is a front elevation of the electro-magnetic transducer viewed from a side of the air outflow end, and
FIG. 4 ( b ) is a cross-sectional view along the line 3 C— 3 C of FIG. 4 ( a ).
FIG. 5 shows a head slider of the second embodiment of the present invention.
FIG. 6 shows a head slider of the third embodiment of the present invention.
FIGS. 7 ( a )-( c ) show a header slider of the fourth embodiment of the present invention.
FIG. 7 ( a ) is a front elevation viewed from a side of the floating rail forming surface,
FIG. 7 ( b ) is a side elevation illustrating the contacting condition to the magnetic disk, and
FIG. 7 ( c ) is a side elevation illustrating the flying condition.
FIGS. 8 ( a ) and 8 ( b ) show the process of manufacturing a thin film magnetic head.
FIG. 8 ( a ) is a perspective view of a wafer, and
FIG. 8 ( b ) is a perspective view illustrating a condition where a bar is cut out.
FIGS. 9 ( a )-( e ) show the process of forming the floating rail.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIGS. 2 ( a )- 2 ( c ) show a head slider of the present invention. A magnetic head slider is manufactured by forming an electro-magnetic transducer 2 on slider body 1 using the thin film process and by forming floating rails 41 - 43 on the surface opposing to magnetic disk 3 . The floating rails are formed of a couple of side rails 41 and 42 and a center rail 43 . The slider body 1 is formed, for example, of alumina-titanium-carbide (Al 2 O 3 TiC).
The magnetic head slider flies over the magnetic disk 3 at the predetermined height with the airflow in the direction of an arrow mark A in FIG. 2 ( b ) due to the rotation of the magnetic disk 3 . Moreover, the magnetic head slider has a sloping surface 8 at the air inflow end 5 of the slider body 1 and the floating rails 41 to 43 .
The projections 61 and 62 are formed at the boundary between the sloping surface 8 and a rail surface 8 ′ of the floating rails 41 and 42 , and are projected toward the magnetic disk 3 . With respect to the size of the projections 61 and 62 , the contacting area to the magnetic disk 3 are as small as not causing the stiction and are as large as not being worn out easily due to the friction with the magnetic disk 3 . For example, the projections 61 and 62 are formed as an elongated column having the minor axis length of about 50-70 μm, while the width of the floating rails 41 and 42 is about 300 μm.
As explained above, the projections 61 and 62 are required to have the sufficient height to show stiction-free, for example, about 20 nm in minimum or about 30 nm assuming a margin for the magnetic disk 3 having the surface roughness Ra of about 2 nm. In FIGS. 2 ( a ) and 2 ( b ), the projections 61 and 62 are formed at the boundary between the sloping surface 8 and the rail surface 8 ′ but these may also be formed on only the rail surface 8 ′.
FIGS. 3 ( a )-( c ) show the electro-magnetic transducer. In these figures, the electro-magnetic transducer 2 is a composite type head which is generally called an MR head and which is formed integrally an inductive element for recording and a magneto-resistive element for reproducing. The electro-magnetic transducer 2 is formed by utilizing the thin film process and the magneto-resistive element and the inductive element are formed in this sequence from the side of slider body (substrate) 1 .
The magneto-resistive element is composed, as shown in FIGS. 3 ( b ) and 3 ( c ), of a magneto-resistive layer (MR layer) 2 f , a non-magnetic gap layer 2 a formed for surrounding the MR layer 2 f , and an upper magnetic shield 2 c and a lower magnetic shield 2 d formed for sandwiching the MR layer 2 f and the gap layer 2 a.
The inductive element is composed of a lower magnetic pole (the upper shield) 2 c , an upper magnetic pole 2 b , a non-magnetic gap layer 2 a ′ for forming an interval between the upper and lower magnetic poles 2 b and 2 c and at the rail surface, a non-magnetic insulating layer 2 i formed between both magnetic poles 2 b and 2 c , and a coil 2 e formed in the non-magnetic insulating layer 2 i.
In the electro-magnetic transducer 2 , as shown in FIG. 3 ( b ), a protection film 2 h is formed on the upper magnetic pole 2 b of the inductive element and a protection film 10 a is formed in the floating surface side of the inductive element and magneto-resistive element.
As shown in FIGS. 2 ( a )-( c ), the electro-magnetic transducer 2 is arranged at the air outflow end 7 of the floating rail 41 and a part of the electro-magnetic transducer 2 is appearing on the rail surface of the floating rail 41 . In the floating rail 41 , at the air outflow end 7 , both sides of the electromagnetic transducer 2 are engraved along the longitudinal direction of the floating rail 41 , and thereby a narrow width portion 4 a and recesses 9 are formed.
Namely, the floating rail 41 is narrowed in width at the air outflow end 7 for the contact with the magnetic disk 3 . When the magnetic disk 3 having the surface roughness Ra of about 2 nm is considered, it is desirable that the depth d of the recesses 9 of the floating rail 41 be 20 nm or more and the width w of the narrow portion 4 a be about 50 to 100 μm.
In this embodiment, when contacting with the CSS zone, the projection 61 near the air inflow end Sand the narrow portion 4 a at the air outflow end 7 are in contact with the surface of the magnetic disk 3 as shown in FIGS. 2 ( b ) and 2 ( c ). The narrow portion 4 a is as narrow as 50 to 100 μm in width in comparison with the floating rail 41 of 300 μm and therefore there is no fear for the stiction to the magnetic disk 3 . Moreover, even in the case of the floating condition, since the projection is not provided near the narrow portion 4 a , the flying height from the magnetic disk can be reduced.
FIGS. 4 ( a ) and 4 ( b ) show a modification example of the electro-magnetic transducer. In the electro-magnetic transducer shown in FIGS. 3 ( a )-( c ), since the floating rail 41 where the electro-magnetic transducer 2 is arranged is engraved, the upper and lower shields 2 c and 2 d are exposed to the side wall of the engraved portion. Therefore, the electro-magnetic transducer 2 potentially has the possibility of corrosion.
This problem can be eliminated, as shown in FIGS. 4 ( a ) and 4 ( b ), by forming the upper and lower shields 2 c and 2 d of the electromagnetic transducer 2 to such a size as can be accommodated within the narrow portion 4 a . Namely, in this embodiment, the magnetic shields 2 c and 2 d are formed so as to have a step that their tip portions opposed to the magnetic disk 3 are narrowed in width, and the floating rail 41 is engraved at the position adequately isolated from the side edge of the magnetic shields 2 c and 2 d . As a result, the side wall of the narrow portion 4 a is covered with the protection film 2 h which is also covering the electromagnetic transducer 2 . Thereby, the exposure to the outside can be prevented.
FIG. 5 shows a head slider of a second embodiment of the present invention. For the explanation of the second embodiment, the elements which are substantially same as the above-mentioned embodiment are designated by the same reference numerals, and the explanation is omitted here. In this embodiment, the width w 1 of the narrow portion 4 a of the floating rail 41 where the electromagnetic transducer 2 is arranged is formed wide and the width w 2 of the narrow portion 4 a of the floating rail 42 where the electro-magnetic transducer 2 is not arranged is formed narrow.
Since the narrow portion 4 a of the floating rail 41 where the electro-magnetic transducer 2 is arranged is formed in the width not interring the magnetic shields 2 c and 2 d , the magnetic shields 2 c and 2 d are never exposed to the outside. Therefore, there is no fear for the corrosion. Moreover, since the narrow portion 4 a where the electromagnetic transducer 2 is not arranged is formed narrow, in comparison with the first embodiment, as much as the widening of the narrow portion 4 a of the floating rail 41 where the electro-magnetic transducer is arranged. Therefore, the total contacting area is never enlarged.
FIG. 6 shows a head slider of a third embodiment of the present invention. This embodiment is a modification for effectively preventing the stiction. The recesses 9 in both right and left sides of the narrow portions 4 a are coupled with second recesses 9 ′ crossing the floating rails 41 and 42 . As a result, the narrow portion 4 a is formed like an island which is capable of preventing that the lubricant creeps up by the capillarity. The second recess 9 ′ has the same depth to both right and left recesses and the width wc of about 5 μm.
FIGS. 7 ( a )- 7 ( c ) show a head slider of a fourth embodiment of the present invention. In this embodiment, each floating rail 41 and 42 is provided with the backward projections 63 and 64 , in addition to the forward projections 61 and 62 in the side of the air inflow end 5 . The backward projections 63 and 64 as shown in FIG. 7 ( b ) have the height of 20 nm or more not to cause the stiction at the time of contacting with the magnetic disk 3 .
Moreover, it is preferable, as shown in FIG. 7 ( c ) that the backward projections 63 and 64 are provided at the area so that they are not in contact with the magnetic disk 3 when the magnetic head slider flies. In this embodiment, the backward projections 63 and 64 has the height almost equal to the forward projections 61 and 62 provided near the air inflow end 5 , and are arranged at the center of each floating rail 41 and 42 .
Therefore, in this embodiment, since the projection 61 - 64 are in contact with the CSS zone of the magnetic disk 3 under normal condition as shown in FIG. 7 ( b ), the contacting area with the magnetic disk 3 can be reduced and thereby the stiction can be prevented. In addition, even if the air outflow end 7 is in contact with to the CSS zone as shown by a chain line in FIG. 7 ( b ), the angle Θ to the magnetic disk 3 becomes large. Therefore, the contacting area becomes small and the possibility for the stiction is also lowered.
FIGS. 8 ( a ) and 8 ( b ) show the process of manufacturing the magnetic head slider. The magnetic head slider can be obtained by forming a plurality of electro-magnetic transducers 2 on a ceramic wafer 10 such as alumina-titanium-carbide (Al 2 O 3 TiC) using the thin film process as shown in FIG. 8 ( a ), then cutting the wafer by a dicing saw into bars that the electromagnetic transducers 2 are arranged in a line as shown in FIG. 8 ( b ), then forming the floating rails 41 and 42 on the cutting surface A of the magnetic pole side of each bar by the process explained later, and then separating from the bar. If a sloping surface 8 as shown in FIG. 2 is formed at the air inflow end 5 , the chamfering process applies to the edge of the bar after the cutting process of the wafer into the bar and before the forming process of the floating rails.
FIG. 9 shows the process of forming the floating rails to the bar. First, the floating rails are formed by etching the floating rail forming surface (surface A of FIG. 8 ( b )) of the bar. Thereafter, as shown in FIG. 9 ( a ), an adhesion layer 10 a of about 2 nm in thickness is formed on the rail surface of the floating rail by the sputtering of Si or SiC, and then a protection layer 10 b is laminated thereon. The protection layer 10 b is formed with the diamond-like carbon (DLC) film by the plasma CVD process and its thickness is about 20 nm or more, for example, of about 30 nm.
Thereafter, as shown in FIG. 9 ( b ), the resist 10 c is formed on the area of the protection layer 10 b to form the projections 61 and 62 . The resist 10 c is coated corresponding to the projections 51 and 62 in the side of the air inflow end 5 and, if necessary, to the backward projections 63 and 64 . Thereafter, the remaining portion not covered with the resist 10 c is etched by the ion milling process or the like, and thereby the projections 61 and 62 consisting of DLC are formed as shown in FIG. 9 ( c ).
Moreover, as shown in FIG. 9 ( d ), the surface of floating rail is coated with the resist 10 d , except the area corresponding to the recess 9 . Thereafter, as shown in FIG. 9 ( e ), the narrow portion 4 a is formed on the floating rail by etching the area corresponding the to the recess 9 and then the resist 10 d is removed. With the processes explained above, the magnetic head slider as shown in FIGS. 2 ( a )- 2 ( c ) can be obtained. In the magnetic head slider, the floating rail including the narrow portion 4 a is covered with the adhesion layer 10 a which is also working as the protection film, and the projections 61 and 62 consisting of DLC are provided in the predetermined positions.
INDUSTRIAL APPLICABILITY
As will be apparent from above explanation, the present invention can provide the small flying height and can prevent the stiction to the magnetic disk.
The head slider of the present invention can realize the small flying height while preventing the stiction to the magnetic disk. Therefore, the recording/reproducing sensitivity to the recording medium can be improved and therefore the high density recording can be realized.
Particularly, the magnetic disk drives have been greatly improved in the recording capacity and is still required to further increase the recording capacity. From this point of view, the head slider of the present invention is very effective. Moreover, the present invention is also effective not only to the magnetic disk drive but also to an optical disk drive using the head slider.
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The head slider mounts a recording/reproducing element and flies over a recording medium with the airflow generated when the recording medium moves. The head slider comprises a slider body having an air inflow end and an air outflow end, a rail projected from the slider body to define an air bearing surface extended to the outflow end, a projection formed on the rail and between the inflow end and the outflow end, and a recess formed at the outflow end of the rail to make narrow the width of the rail. When the recording medium stops, the head slider and the recording medium are in contact at the projection and the air outflow end of the rail. Since the outflow end of the rail is narrow in width, the stiction can be prevented. Moreover, it is unnecessary to form a projection near the outflow end of the rail and thereby the flying height of the recording/reproducing element can be lowered to improve the recording/reproducing sensitivity.
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CROSS-REFERENCE TO RELATED APPLICATIONS
None.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
Not applicable.
BACKGROUND
The present disclosure relates to harvesting articulated (jointed) combines and more particularly to improved concaves in the forward tractor or crop processing power unit (PPU).
Most agricultural combines use a rotary threshing and/or separating system including at least one rotor drivingly rotated about a rotational axis within a rotor housing, the housing having a lower region including a perforated concave spaced radially outwardly of the rotor. The rotor often may have a frusto-conical inlet end having a helical flight or flights therearound for conveying a flow of crop material into the space between the rotor and the housing. The main body of the rotor typically will have an array or layout of threshing elements, most commonly including rasp bars and separating elements, and/or elongated tines, all of which protrude radially outwardly therefrom into the space. The rasp bars and separator bars are configured differently, so as to perform different functions and may not all be present on a given rotor design. The functions of the rasp bars include to cooperate with one or more vanes and guides typically disposed around the upper portion of the inner circumference of the rotor housing, for conveying a mat of the crop material along a generally helical path through the space, while cooperating with the vane or vanes and/or guides, and other aspects of the concave, e.g., bars, perforations and the like of the concave, to break up larger components of the crop material into its constituents, namely larger constituents or elements of crop residue commonly referred to as straw, which includes stalks, stems, cobs and the like, and smaller constituents which comprise the grain and smaller elements of material other than grain (MOG), in the well known manner.
Rasp bars usually are relatively narrow and generally concentrated nearer the inlet end of the rotor and include a plurality of serrations defining grooves in the threshing element. These grooves are oriented at small acute angles to, or generally aligned with, the direction of rotation of the rotor for raking or combing through the mat of crop material and uncoupling the smaller constituents from the crop material thus allowing the grain to fall through the openings in the concave. Straight separator bars, in contrast, are often longer and generally located nearer to the discharge end of the rotor and include one or more bars with at least one sharp edge extending perpendicular to the direction of rotation to plow the larger components of the crop mat and carry them away from the smaller grain and MOG. The function of typical straight bars is to disrupt the consistent flow that shorter rasp bars establish and, thereby, cause grain to be shaken out of the straw due to that turbulence.
To minimize damage to the grain it is desirable to separate the grain from the mat of crop material so it can fall through the openings in the concave as far forward in the threshing system as possible. The number and size of openings in the forward portion of the concave is limited, however, and it has been observed that some of the threshed grain travels over additional rasp bars or other threshing surfaces on the rotor prior to falling through an opening of the concave.
It has also been observed that when the relatively narrow rasp bars engage the mat of crop material, some of the larger portions, particularly ears of corn, will deflect off rather than flowing over the rasp bars. As a result, the grain remains in the threshing system longer, encountering more threshing elements, risking damage to the grain, and increasing the likelihood that the cobs will break.
Accordingly, what is sought is a threshing system for an agricultural harvester including threshing elements, which overcome at least some of the problems, shortcomings, or disadvantages set forth above.
BRIEF SUMMARY
Disclosed is a rotor and cage assembly that includes a skeleton of curved spaced-apart side members affixed to laterally extending horizontal (upper and lower) spaced-apart members therebetween and surrounding the rotor. One of the curved spaced-apart side members is terminated with curved fingers. Three concave inserts insert laterally into the skeleton spanning 270° around the rotor. One of the concave inserts carries straight fingers that interlace between the skeleton side member curved fingers. A control assembly of plates having arcuate slots placed at 3 of the pivots of the skeleton assembly, control bars connected to the skeleton pivots, and an actuator connect to the control bars at one end effect arcuate rotation of the control bars resulting in the synchronized rotation of the arcuate slotted plates so that the interlaced straight fingers move closer together or farther apart with the fixed skeleton assembly curved fingers for different types of grain. The interlacing and overlapping concave inserts permit the three sections of 270° degree wrap to expand and contract their combined circumference as the concaves move nearer and farther from the rotor swung diameter. This movement is necessary in order to adjust to various crops and conditions, specifically and intentionally to prevent wide gap spaces between concave inserts especially when the assembly is in its open position. A reasonably identical grate assembly, which may or may not allow adjustment, follows and is adjacent to the concaves skeleton and also surrounds the rotor. Of course, the number off concave inserts could be greater or lesser in number and extend to less or more than 270°. For present purposes, the two different sets of fingers “interlace” both by being laterally offset (side-to-side), but also by being vertically offset (up-and-down). The key for interlaced fingers is that they move closer together and further apart for different types of grains.
A concaves control assembly for a concaves assembly includes a skeleton for receiving at least two concave inserts end-to-end. At least two concave inserts are housed within the skeleton for threshing grain in concert with a rotor assembly. Rotatable plates have arcuate slots are located where the at least two concave inserts meet and are carried by and are rotatable with skeleton pivot pins. Control bars connect to and are between the skeleton pivot pins. An actuator connects to the control bars at one end of one of the control bars, whereby actuation of the actuator moves the control bars causing arcuate rotation of the arcuate slotted plates for moving the at least two end-to-end concave inserts closer together and farther apart.
A grates control assembly for a grates assembly includes a skeleton for receiving at least two grate inserts end-to-end. At least two grate inserts insert within the skeleton for separating grain in concert with a rotor assembly. Rotatable plates have arcuate slots and are located where the at least two grate inserts meet and are carried by and rotatable with skeleton pivot pins. Control bars connect to and are located between the skeleton pivot pins. An actuator connects to the control bars at one end of one of the control bars, whereby actuation of the actuator moves the control bars causing arcuate rotation of the arcuate slotted plates for moving the at least two end-to-end grate inserts closer together and farther apart.
The concaves assembly and grates assembly are placed together with both the concaves control assembly and grates control assembly working in concert to adjust both the concaves assembly and the grates assembly. The actuator of some of the grates inserts may be manual and/or powered.
These are other features will be described in detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the nature and advantages of the present method and process, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:
FIG. 1 is a side elevation view of an articulated combine having the disclosed grain cart;
FIG. 2 is an overhead view of the articulated combine of FIG. 1 ;
FIG. 3 is an isometric view of the articulated combine of FIG. 1 ;
FIG. 4 is an isometric view of the PPU from its rear;
FIG. 5 is the isometric view of FIG. 4 with the outer shell or skin removed from the PPU;
FIG. 6 is a sectional view taken along line 6 - 6 of FIG. 1 ;
FIG. 7 is an isometric view like that of FIG. 5 of the opposite side of the PPU;
FIG. 8 is a bottom view of the PPU;
FIG. 9 is a bottom view of the concaves section of the PPU and includes the twin straw choppers;
FIG. 10 is a side isometric view of the concaves of FIG. 9 ;
FIG. 11 is a front isometric view of the concaves of FIG. 8 ;
FIG. 12 is a side isometric view of the rotor assembly of the concaves;
FIG. 13 is a bottom isometric view of the concave grates and concaves frame assembly;
FIG. 14 is a front view of the concaves cage in a closed position with common actuator assembly;
FIG. 15 is a front view of the concaves cage from FIG. 14 with the common actuator removed;
FIG. 16 is a front view of the grates (or bonus sieves) cage in an open position with common actuator mechanism;
FIG. 17 is a front view of the grates (or bonus sieves) cage from FIG. 16 with the common actuator removed;
FIG. 18 is an isometric view of the concaves sieves assembly in a closed position;
FIG. 18A is a blowup of the fingers of the concaves sieves assembly of FIG. 18 with the fingers in a closed position consonant with the concaves being in a closed position;
FIG. 19 is an isometric view of the concaves sieves assembly in an open position;
FIG. 19A is a blowup of the fingers of the concaves sieves assembly of FIG. 19 with the fingers in an open position consonant with the concaves being in an open position;
FIG. 20 is an isometric view of one of the 3 concaves sieves;
FIG. 21 is an isometric view of just one of the sieve inserts;
FIG. 22 is an isometric view showing installation of one of the sieve inserts;
FIG. 23 is an isometric view of the frame assembly from underneath.
The drawings will be described in greater detail below.
DETAILED DESCRIPTION
Referring initially to FIGS. 1, 2, 3, and 4 , an articulated harvester, 10 , consists of a powered PPU, 12 , a rear grain cart, 14 , and an articulation joint, 16 , that connects PPU 12 with rear grain cart 14 . The details of articulation joint 16 are disclosed in commonly owned application Ser. No. 14/946,827 filed Nov. 20, 2015. PPU 12 carries a grainhead, 18 , operator's cab, 20 , grain cleaning and handling assembly, and engines. PPU 12 is devoid of any grain storage, such being exclusive in rear grain cart 14 . While both PPU 12 and rear grain cart 14 are shown being carried by wheel assemblies, one or both could be tracked. A screened air inlet, 15 , is located atop PPU 12 where the air likely is the cleanest around harvesting combine 10 .
An off-loading auger assembly, 22 , is in the folded home position and being carried by rear grain cart 14 . Grain cart 14 also bears a foldable roof, 24 , shown in an open position, but which can fold inwardly to cover grain stored in rear grain cart 14 . Foldable roof 24 may be made of metal, plastic, or other suitable material, but may be made of durable plastic for weight reduction and easy folding/unfolding. A grain storage bin, 28 , (see also FIG. 14 ) carried by grain cart 14 may be made of plastic also in keeping with desirable weight reduction; although, it could be made of metal also at the expense of weight. All plastic parts may be filled with particulate or fiber reinforcement in conventional fashion and could be laminate in construction. Further details on rear grain cart 14 can be found commonly owned application Ser. No. 14/946,842 filed Nov. 20, 2015.
Referring now to FIG. 4 , the operator is granted access to cab 20 by a stair assembly, 30 , that extends upwardly from just above the ground and will be more fully disclosed in commonly owned application Ser. No. 15/654,786, filed Jul. 20, 2017. The skin or shell has been removed in FIG. 5 to reveal the components housed within PPU 12 . A fan assembly, 32 , is located centrally for air to enter through screened air inlet 15 . This location was chosen, as it arguably will be the cleanest flow of air around PPU 12 . Radiators, as typified by a main cooling system air box, 34 , surround fan assembly 32 and are coolingly connected with a pair of engines, 36 and 38 , located on either side of main cooling fan assembly 32 . Engine 36 powers the hydraulics for articulated combine 10 , while engine 38 powers all other components of articulated combine 10 . Exhaust after treatment assembly, 40 , cleans air for emission control. When firing up the engines, which typically will be diesel engines, engine 38 is started first so that coolant flowing through engine 38 will warm up engine 36 and the hydraulic fluid for articulated combine 10 . The twin engines aspect will be described in detail in commonly owned application Ser. No. 15/643,685, filed Jul. 7,2017 and the air inlet assembly will be described in detail in commonly owned application Ser. No. 15/642,799, filed Jul. 6, 2017. Other components visible in FIG. 5 will be described in detail below.
Looking next at FIG. 6 , grainhead 18 typically will be between about 30 and 50 feet wide and severs the crop in various fashions from its stalk or its attachment to earth. Grainhead 18 is carried by a feeder face adapter, 44 , to a feeder mechanism assembly, 50 , as described in detail in commonly-owned application Ser. No. 15/621,218, filed Jun. 13, 2017, which conveys the severed crop consisting of both stalk and grain. By convention in the industry, all material that is not grain is referred to as “Material Other than Grain” or, simply, “MOG”.
Progressing rearwardly, the crop material reaches the end of feeder assembly 50 at velocity and is projected rearwardly and upwardly onto the walls of a transition cone, 52 , which is a robust structure that describes shape and direction of material flow and generally funnels the flow of crop material toward both sides and the bottom of a rotor inlet cone, 52 , of a spinning rotor, 54 (see FIG. 12 ). Rotor inlet flighting, 56 , is identified as the front portion of rotor 54 that is predominately 2, 3, 4, or more large auger flights attached to the skin of rotor 54 and serve to both propel the crop material rearward into a rotor cage, 58 , and begin the rotation of the crop material (as viewed from the rear of the module) around the periphery of rotor cage 58 . The rotation of rotor 54 occurs by virtue of a pulley assembly, 42 , a gearbox, 60 , and shaft, 62 . Rotor cage 58 is the empty space located within the rotor tube and is formed by concaves, grates, and a top cover with vanes that define the rotor tube or cylinder within which the rotor rotates and provides all stationary surfaces that the grain is threshed against and separated therethrough.
The process within rotor cage 58 delivers the crop material off the end of flights 56 and onto rasp bar assemblies for grain threshing and separation (see FIG. 12 ). These rasp bar assemblies may be rough cast iron configurations that impact, move, and pinch the crop material in order to dislodge the grain from the MOG parts of the plant, such that the grain can be removed from the flow. A typical rasp bar, 64 , as are all rasp bars, is attached to rotor 54 by means of its bolting to barnacles, as typified by a barnacle, 66 , which in turn is welded to rotor 54 in carefully identified locations to form the desired spiral patterns on the rotor as a whole. The rasp bars will be located in a spiral configuration around rotor 54 such that the crop material will be rolled, twisted, and rubbed against itself, the net affect of which will be to have significantly enhanced and substantially “gentler” threshing action, thereby nearly eliminating grain damage common to units that “smack the crop with steel” to achieve threshing. Each raps bar assembly, then is composed of a rasp bar and a barnacle.
Entry into rotor cage 58 begins the threshing process, as the rasp bars rub the crop material across concaves, 70 (see also FIGS. 10 and 13 ), which are porous structures typically made of steel that surround the lower 270° of the periphery of rotor cage 58 and are divided into three sections, each of which covers 90°. Concaves 70 can have numerous actual structural constitutions, but in general provide a rough surface to cause significant rubbing and turbulence between the rasp bars and the top surface of concaves 70 . Additionally, concaves 70 also are quite porous (have holes) to allow released grain to exit through the holes to be introduced to a cleaning area, 68 . The concave inserts (often simply called “concaves”), as typified by a concave insert, 72 (see FIGS. 13 and 18 ), change from one type of surface to a different type of surface as crop type and condition dictate. Ideally and typically, this front section (˜½) of the length of rotor cage 58 can remove nearly 75% of the entrained grain from the MOG material, and coincidentally pass on perhaps more than 80% of the MOG to a separation section or cleaning section 68 that follows and is described in greater detail in commonly owned application Ser. No. 15/642,799, filed Jul. 6, 2017. Typical to all harvesting combines, concaves 70 are suspended from above such that they can be moved in and out relative to the rasp bars swung diameter to cause a change in the relative clearance of the rasp bars top surface to the concaves inner surface. This allows for varying aggressiveness in the threshing process contrasted to crop type and condition and will be described in detail later herein.
The separation section of rotor cage 58 is located immediately behind (upstream) the threshing section and is for most part identical to the threshing section. By tradition, the same inserts that are located in the threshing area are now called grates, 74 (see FIG. 19 ), when in this rearward portion of the process. Typically, grates 74 are fixed in place and do not adjust in and out as do concaves 70 ; however, because the mechanisms are identical to the concave supports, grates 74 could be adjusted and that capability will be disclosed herein. The intended function of grates 74 is to separate the remaining grain from the MOG; however, since the MOG to grain ratio now significantly favors the MOG, the proportion of MOG exiting grates 74 is quite a bit higher that from concaves 70 . All of this material falls downward toward cleaning system sieves 68 .
An important and new feature in rotor cage 58 is a top cover vane assembly, 76 (see FIG. 10 ), as typified by a vane, 78 , located on the underside of the flat roof section of rotor cage 58 . The vanes are basically steel angle plates that bolt thru the top cover on the one horizontal leg, and protrude downwardly into the crop flow with their 90° vertical leg. These vanes serve to regulate the speed of flow of material thru rotor cage 58 , thereby affecting the relative aggressiveness of threshing and separation. When set at an angle more perpendicular to axial flow, the vanes retard the flow rate; when set at an angel less perpendicular (“laid back” or “sped up” in the language), the vanes allow faster, less power intensive flow. All other rotary combines have a curved top cover that requires the cage vanes to be curved also. This curvature sincerely limits the range of adjustment due entirely to the fact that as (for instance) a vane that would conform to a line that is perpendicular to axial on the cage cylinder, would be curved too much to fit a position that was 30° off of perpendicular. With the flat surface disclosed herein will have on the top cover. The vanes of top cover vane assembly (see FIG. 7 ) are attached to tubular control bars, 80 and 81 , which is moved by cylinders, 82 and 83 , to control their angle. Control can be exercised remotely in cab 20 by the operator to give the operator a tool that will be effective in controlling throughput versus threshing versus separation to optimize productivity of harvester 10 . Top cover vane assembly 76 is described in great detail in commonly owned application Ser. No. 15/623,619, filed Jun. 15, 2017.
Finally the MOG (which by convention now changes its name to straw or residue) now located at the rear of the separation area (grates 74 ) is ready to be discharged from rotor cage 58 to be spread across the ground. In PPU 12 , this will be done quite unconventionally by discharge openings in rotor cage 58 to discharge assemblies that contain straw chopper assemblies, 90 and 92 (see FIG. 9 ), where rapidly rotating drums with numerous swinging blades will reduce the length of the residue pieces and propel them horizontally and transversely outwardly at high velocity. Assisting in the chopping process are stationary knives, (“counter knives”, “fixed knives”), not seen in the drawings, which act as shearing surfaces to hold the long residue for the swinging (sharp) knives to better cut the residue.
Shortly after chopping and propulsion, the residue pieces will encounter straw hood assemblies, 94 and 96 (see FIG. 9 ), that is used as a deflector to influence the direction of the pieces such that some continue far out away from the vehicle, while variably others fall at distances from the vehicle, causing and ideally uniform distribution of the pieces over the ground surface. PPU 12 will have two sets of these chopper assemblies and knives 90 and 92 , one on each side as seen in FIGS. 8 and 9 and described in detail in commonly assigned application Ser. No. 15/652,806, filed Jul. 18, 2017.
Returning to the MOG and grain that is being expelled through concaves 70 and grates 74 , these materials exit the inserts at reasonably high velocity and on a trajectory imposed by both their angular velocity from spinning in rotor cage 58 and from the centrifugal force imparted by rotation of rotor 54 , the net of which is largely an outward (if not radial) departure from rotor cage 58 down into the void below rotor cage 58 and above cleaning system assembly 68 (see FIG. 6 ) known as the “chaffer” (its purpose in the process is to help remove the bigger, lighter chaff from the grain by allowing the grain to fall through while rejecting the chaff to be blown out the rear of the machine). However, in accordance with the present disclosure, an additional cleaning component that takes advantage of that exit velocity of the material mix leaving the separation system is provided. Front Bulkhead 98 of the rotor/cage support structure has louvered slots (see FIG. 8 ) in it that will allow high velocity air being forced downwardly into a plenum to which the bulkhead is one wall, the driving force of the air being cleaning charge fan assembly (see FIG. 6 ) located above the rotor cage, in front of main cooling system air box 34 (see FIG. 6 ). The charge fan assembly will be collecting exhaust air from a cooler assembly 34 , imparting new velocity to it and sending it down through the plenum formed by front cage bulkhead 98 , rotor inlet cone 52 , a separator sidesheet, and a cover sheet to complete the plenum. The purpose being to deliver air from above PPU 12 down through the plenum and into the inlet of cleaning fan 33 , located in front of the axle, as explained in detail in U.S. Ser. No. 15/641,799(cited above).
As a matter of secondary assurance of high capacity, and because the disclosed PPU 12 configuration allows it, a bonus sieves assembly, as disclosed in commonly assigned application Ser. No. 15/649,684, filed Jul. 14, 2017, is provided. Unknown to the rest of the industry, these bonus sieves are allowed by the rear axle for harvesting combine 10 being on rear module 12 , not beside the sieves. So the frame of PPU 12 will bulge outwardly wider once past the front tires, and fill that space on each side of the main sieves with narrower, shorter sieve members, bonus sieves, that in total will add about 20% more sieve area. Moreover, remembering the condition of having a much higher MOG ratio being expelled from the rear of the separation area, this bonus sieves area will add additional cleaning area back where the cleaning is made more difficult by higher MOG concentrations, whether that be in the airstream or on the sieve surfaces.
Under the front majority of the major sieves' length, a clean grain conveyor, a belt conveyor (running rearward on the top) that catches the grain as it falls, and conveys it rear ward to a clean grain cross auger. A secondary, but equally important, function of the flat top of the conveyor is to serve as a converging plenum versus the lower sieve, such that the air being moved rearward by the cleaning fan is progressively force to be directed upward through the sieves, thus powering the pneumatic cleaning function of the cleaning system. If stray MOG were to fall through both sieves, this is yet another chance for that MOG piece to be blown rearward, and perhaps out of the system. Again, this is disclosed in detail in U.S. Ser. No. 15/641,799cited above.
The fate of the separated clean grain exiting the various cleaning systems in PPU 12 and its transfer to grain cart 12 is disclosed in commonly owned application Ser. No. 14/946,827 cited above.
Finally, PPU 12 will contain a tailings return system, as disclosed in detail in commonly owned application Ser. No. 15/649,684, filed Jul. 14, 2017 , that will be located below and aft of the aft of cleaning assembly 68 . Material that is small enough and dense enough to fall through the extreme rear section of the chaffer, referred to as a chaffer extension, and material that because of size or low density could not fall through the lower sieve will be delivered to a tailing auger trough. In the trough is a tailings cross auger, an auger with opposing flighting, that this time augers the material outward from the middle. As the material reaches the sidesheets of the major structure, it enters a tailings elevator, one on each side of the structure. Running on a sprocket on the (each) end of the cross auger will be a roller chain with rearward leaning paddles that are also canted to move the material inward against the inner wall as it is conveyed upward. The leaning and canting of the paddle reduces the conveying efficiency while also increasing the tumbling and rubbing of the unthreshed grain against the walls and outer ring of the elevator chute. This “rethreshed” material will then be introduced back into cleaning system 68 above the bonus sieves by auger flights on a tailings top drive shaft to make another attempt at proper cleaning and saving, or to be rejected again, and, in either case, it will in one way or another be ejected from the system.
At this point in the disclosure, we look at FIGS. 8 and 10 whereat the support for concaves 70 and grates 74 is shown. In particular, a front bulkhead, 98 , a middle bulkhead, 100 , and a rear bulkhead, 102 , provide support for the rotor/cage structure. Looking at FIGS. 13-22 , concaves 70 and grates 74 are disclosed in detail. A skeleton, 104 , supports and accepts concave inserts, such as concave insert 72 , and a skeleton, 105 , that supports and accepts a grate insert, 106 . There are three sieve inserts across and three sets of these inserts spanning 270°. FIG. 20 shows frame assembly 104 , concave insert 72 , a concave insert, 108 , and concave insert 110 . One end of concave insert 108 is flat plate, 109 , for permanent attachment to skeleton 104 , while the other end has a finger assembly, 112 . The finger assembly end of concave insert 108 is curved and partially goes around an upper bar, 114 , portion of skeleton 104 by virtue of its end having a U-shape to receive upper bar 114 . The insertion of concave insert 108 into skeleton 104 is seen in FIG. 22 to involve concave insert 108 being moved from the side into position with flat 109 being bolted or otherwise attached to a flat bar, 116 , of skeleton 104 and the U-shaped upper end taking in bar 114 . All of the concave inserts are attached in a same manner. In fact, the grate inserts are similarly configured and inserted into frame skeleton 105 in the same manner. The disclosed design permits easy installation and removal of any one of the concave or grate inserts. A bent finger assembly, 111 (see FIG. 19A ), is part of the skeleton assembly and is present for both the concave assembly and the grate assembly and interact with the finger ends of the concave and grate inserts to accommodate the size of the grain being handled.
Referring additionally to FIGS. 14 and 15 , the ends of skeleton 104 are configured to receive rotatable bars, 118 , 120 , and 122 , and a fixed bar, 124 . As seen more clearly in FIGS. 14 and 15 , slotted plates, 126 , 128 , and 130 , having arcuate slots are attached to rotatable bars 118 , 120 , and 122 and are rotated by a cylinder assembly, 132 , so that the finger assemblies are in a closed position. In this closed position, the sieve inserts are in a pinched configuration with respect to rotor 54 for small grain. As more clearly seen in FIGS. 16 and 17 , cylinder assembly 132 has rotated so that the finger assemblies are in an open position for large grain. Simultaneous motion is achieved by cylinder assembly being attached to link bars, 134 and 136 . A similar set of link bars are provided at the other end of the concaves assembly. The arcuate rotation results in the fingers being moved in an arcuate motion and in an up and down motion. These simultaneous motions result in the fingers, straight on one side and curved on the other side, moving closer and further apart while simultaneously moving slightly up and down. Additionally, cylinder assembly 132 can be actuated remotely by the operator. Additionally, while hydraulic cylinders are shown in the drawings, such cylinders (or actuators in general) could be pneumatic, linear actuators, electric motors, or other assemblies. Actuators are “powered” for present purposes.
While the disclosed concaves inserts surmount 270°, a lesser or greater amount of wrap could be designed into such concave inserts. Moreover, the sections of concaves can be adjusted independently to not only effect a change in clearance to the rotor, but also to achieve multiple pinch points around the periphery in the same number as the number of peripheral sections. The drawings show 3 such concave sections resulting in triple convergence of concave clearance to the rotor. The net effect of this triple convergence is to enable a single crop pass around the periphery of rotation to have threshing and separation equivalence to three separate passes from typical configurations, greatly increasing the efficiency of threshing and separation. The disclosed design, then, permits the totality of the designated “separation” area, the grates, to be reconfigurable with respect to the type of grate separation surface chosen, as opposed to being fixed sized holes. Moreover, the grates also could be designed for simple adjustment for clearance and pinch should that be desired.
The flexibility of the concave adjustment mechanism permits their synched or adjusted independently. The same goes for the grates with the proviso that the grates could be synched with the concaves. The concave inserts and grate inserts are easily and quickly inserted and withdrawn according to their disclosed design. All concave inserts and all grate inserts are the same in design, permitting any insert to be installed in any location. Finally, the concave inserts have sets of fingered panels that move closer and apart as the concave clearance is adjusted inwardly and outwardly. These fingers on the panels are offset to each other to effect great change in the open area and shape of the open area to give prescribed separation based on crop type.
Returning to FIG. 13 , it will be observed that spacers, 138 , 140 , 142 , and another not seen, provide a break between bar 118 for concaves 70 and a bar, 119 , for grates 74 . The same is true for bar 122 and a bar, 123 . Such spacers could be omitted and the respective bars be continuous for grates 74 to rotate as do concaves 70 . Alternatively, grates 74 could be constructed, as are concaves 70 for independent rotation and adjustment.
FIG. 23 shows frame assembly 143 with its various members. Of note is the bulging of the frame behind where the tires, locations 144 and 146 are located to accommodate additional treating assemblies for separation of the grain, as described above and in related patent applications. Front slotted bulkhead 98 is seen in this view also. Some of the plates will contain holes or apertures for achieving weight reduction without sacrifice of structural strength.
While the device and method have been described with reference to various embodiments, those skilled in the art will understand that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope and essence of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiments disclosed, but that the disclosure will include all embodiments falling within the scope of the appended claims. In this application all units are in the metric system and all amounts and percentages are by weight, unless otherwise expressly indicated. Also, all citations referred herein are expressly incorporated herein by reference.
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A rotor and cage assembly includes a skeleton of curved spaced-apart side members affixed to laterally extending upper and lower spaced-apart members therebetween and surrounding the rotor. One of the curved spaced-apartside members is terminated with curved fingers. Three concave inserts insert laterally into the skeleton spanning 270deg around the rotor. One of the concave inserts carries straight fingers that interlace between the skeleton side member curved fingers. A control assembly of plates having arcuate slots placed at 3 of the pivots of the skeleton assembly, control bars connected to the skeleton pivots, and an actuator connect to the control bars at one end effect arcuate rotation of the control bars resulting in the synchronized rotation of the arcuate slotted plates so that the interlaced straight fingers move closer together or farther apart with the fixed skeleton assembly curved fingers for different types of grain.
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BACKGROUND OF THE INVENTION
The present invention relates to an equipment for the injection molding of bars for spectacles, made of plastic material and incorporating a metal stem or core onto which the respective metal hinge is previously welded, or obtained in one piece therewith.
As everyone knows, it is very difficult to produce--in a single injection molding stage--finished bars for spectacles, already incorporating a stiffening metal stem or core.
In actual fact, if one prepares a mold in which the metal stem is arranged in a central position and held by its end provided with hinge, at the moment of injecting the plastic material--which should surround and envelop the core--the speed and pressure at which said material enters the mold, cause the curling up of the stem.
All the attempts made to hold the stem more firmly into the mold, during the injection of the plastic material, have always given negative results.
Different techniques--more or less complicated and anyhow comprising several working stages--have therefore been adopted for producing spectacle bars of the aforementioned type.
According to a first technique, one produces first of all a bar preform by injection molding. In a subsequent working stage, the preform is heated and a metal core, provided at one end with the respective hinge, is introduced with its other end into the preform, wherein it is caused to slide along the longitudinal axis thereof. The preform is heated to the softening point, so as to allow the introduction therein of the pointed and relatively narrow metal core. Obviously, at the end of said operation of introduction, the preform undergoes further treatment so as to acquire the final shape of the spectacle bar.
As can easily be realized, this technique involves:
two working stages,
the need to work on one bar at a time,
a high percentage of defective pieces,
a limitation in the shapes and sizes of the finished bars.
According to a more recent technique, it has been proposed to introduce the metal cores in the actual molding machine, immediately after the injection stage. To obtain this result, one uses a mold which is closed, at the end of the bar which will carry the hinge, by a knife element, a guide for the metal core being provided beyond said knife element and along the extension of the longitudinal axis of the bar. At the end of the injection stage and as soon as the mold has been filled with molten plastic material, after having interrupted the feed pressure, the closing knife is opened and the metal core is caused to slide axially into its guide by being thrust at one end and being introduced with the other end into the mold.
To make sure that the metal core--which, as already said, is very thin and flexible--does not bend during this operation of introduction (which tends to be opposed by the plastic material present in the mold, though at the semimolten state), it is indispensable for the core to fit exactly in its guide. It is thus excluded that also the hinge of the bar may slide into the same guide.
To adopt this technique, the metal cores are therefore perfectly rectilinear, with no hinges or other projecting parts. At the end of the molding stage and after introduction of the metal core, the bar will be provided with its hinge in a subsequent working stage. The hinge is usually fixed by riveting or similar techniques.
Though this system has certain advantages compared to that previously described, in that:
in a single working stage one obtains the bar in its final shape and with the metal core inserted therein, and
in a single subsequent working stage the hinge is applied; nevertheless, it is not always the preferred system, on account of the fact that:
the technique of applying the hinge by riveting is delicate,
the fixing obtained thereby is not so firm and lasting as in the case of hinges welded on the core,
the global aesthetical effect is not always acceptable, since a hinge thus mounted is quite massive and bulky.
SUMMARY OF THE INVENTION
All the above drawbacks are now eliminated with the equipment according to the present invention which allows to carry out, in a single working stage in the same machine, both the injection molding of the bar in its final shape, and the introduction of a metal stem or core onto which the hinge has already been previously welded.
This result is obtained--in an injection molding machine of the heretofore described type, having a mold closed at one end by a knife element, beyond which and along the extension of the longitudinal axis of the mold a guide is provided for the metal stem or core--due to the fact that said guide consists of a groove wherein the core is guided with no slack on three of its sides, the fourth side of the core, from which projects the hinge at the end opposite to the knife element, being guided by means apt to be removed as the metal core advances introducing itself in the mold.
BRIEF DESCRIPTION OF THE DRAWINGS
Further characteristics and advantages of the equipment according to the present invention will anyhow result more evident from the following description of some preferred embodiments thereof, illustrated in the accompanying drawings, in which:
FIG. 1 is a schematic axial section view of the molding equipment according to the invention;
FIG. 2 is a schematic front view of the same equipment;
FIG. 3 shows, on an enlarged scale, a detail of the equipment according to FIGS. 1 and 2, concerning the guiding system of the metal stem or core for introduction into the mold;
FIG. 4 is a view similar to that of FIG. 3, but showing the stem while it is being introduced;
FIG. 5 is a schematic horizontal section view of the equipment shown in the previous figures;
FIGS. 6 and 7 are views similar to those of FIGS. 4 and 5, but showing a modified embodiment; and
FIG. 8 is a schematic front view similar to that of FIG. 2, but referring to another modified embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown schematically in FIGS. 1 and 2, the molding equipment comprises a mold in two parts 1a and 1b, which are shown closed one against the other in FIG. 1, while FIG. 2 shows only the mold part 1a, open.
In the mold cavities 2 are molded the bars in their final shape; the plastic material is injected through passages 3. The injection ducts and the other parts of the actual molding machine are not shown in detail, as they are o known type.
According to the present invention, the upper part of the mold cavities 2 is closed by a knife element 4. This upper part of the cavity corresponds to that designed to form the end of the bar provided with the hinge.
The knife 4 is mounted on a slide 5, which can be shifted in a direction transversal to the longitudinal axis of the mold cavities 2. The movement of the slide 5 is controlled by a cylinder 6 by means of two toggle-joint levers 7 and 8.
A guide 10, for the metal stem stiffening the bars, is provided on the extension of the longitudinal axis of the cavities 2, as shown in detail in FIGS. 3 to 5. On the extension of the longitudinal axis of the cavities 2 and of the guide 10 is also provided an operating finger 11, mounted on a slide 12 and movable along said longitudinal axis under the control of the cylinder 13.
As shown in FIGS. 3 to 5, the guide 10 practically consists of an axial groove, formed into a rigid piece 10a, fixedly connected to the casing of the machine. The groove 10 is shaped so as to exactly house the stiffening stem 15 or, more precisely, so as to house with no slack all its lateral faces except for one. Since, generally, the stiffening stem 15 has a rectangular or substantially rectangular section, the groove 10 will be shaped so as to provide a proper support for one of the major faces and for the two sides, as for the stem shown in FIG. 5 (which has a rectangular section with two ribs on the major faces).
In this manner, the stem 15 is perfectly guided on three of its faces; the guiding in correspondence of the fourth face is guaranteed--as clearly shown in FIG. 5--by a plurality of rollers 16, with axis perpendicular to that of the groove 10, housed with a minimum slack and slidable into a track 17 formed between a pair of opposed guiding profiles 18.
As results evident from FIG. 5, the profiles 18--through allowing the rollers 16 to slide in a direction parallel to the axis of the guide 10--are apt to keep said rollers tightly adherent to the piece 10a, so that their lateral surface acts as cover for the fourth side of the guide 10. In other words, the stem 15 is firmly held in position--though with possibility to slide in the axial direction--by bearing with three of its faces inside the guide 10 and by resting its fourth face against the lateral surface of the rollers 16.
It should be noted, in particular, that in the case of the stem 15--the fourth face of which is provided, as said, with a rib--each of the rollers 16 is in turn provided with an annular groove, the profile of which mates with said rib. This guarantees a more precise and proper bearing of the fourth face.
Of course, the section of the stem 15 can also be quite different from that shown in the drawings, for instance it can be triangular. In each case it is anyhow indispensable for the groove of the guide 10 to provide a slackless housing for most of the faces of the stem, while at least the face onto which is welded the hinge part should be retained or supported by the rollers 16.
This arrangement is conceived for guiding a stem 15 as that illustrated in FIGS. 3 and 4, namely provided with a hinge 20 which has been previously welded in correspondence of its end 15" opposite to its tip 15'. The hinge part 20, however large it may be--or instance, even as shown with dotted lines in FIG. 5--will be freely housed into the track 17 containing the rollers 16, that is, between the guiding profiles 18.
When the operating finger 11 performs its downstroke, bearing against the end 15" of the stem, namely against the actual hinge 20, in order to push the stem into the mold, it will also push downward the set of rollers 16. These get driven--as clearly shown in FIG. 4, which illustrates an intermediate position of the introduction stroke--and are apt to slide within a channel 22 forming a horizontal extension of the track 17, and then towards a container 23 in the form of a vertical channel. A counterweight 24, guided in turn in the container channel 23 and bearing on the rollers 16, opposes a predetermined force to the sliding of said rollers 16 towards the container 23, so that the rollers are always inclined to keep in mutual contact and in contact with the finger 11, thereby guaranteeing a practically continuous support of the fourth face of the stem 15.
FIG. 6 shows a different embodiment in which the track 17, between the profiles 18, is far less wide and is used for guiding a flexible metal lamina 30. In this case, the track 17 is connected to the channel 22 and to the container 23 through arched channel sections, as illustrated.
Since in this case the hinge part 20 cannot be housed in the width of the track 17, the opposed profiles 18 will have to be kept sufficiently spaced to allow the hinge part 20 to be housed therebetween, as shown diagrammatically with dotted lines in FIG. 7.
Instead of using a continuous lamina 30, it is obviously possible to use a kind of small rolling shutter, that is a series of parallel lamina strips, mutually hinged or else simply superposed one above the other.
FIG. 8 finally illustrates a still further embodiment in which the fourth face of the stem 15 is retained by a plurality of pawls 31, oscillating about pins 32 perpendicular to the surface of said fourth face. Said pawls are normally held--by spring means not shown--in the position represented in FIG. 8, in which their end is placed astride of the groove forming the guide 10. In this position, as can easily be understood, they form a closing element for the guide 10 and they firmly retain the stem 15.
When the finger 11 starts its downstroke, pushing downward the stem 15, it is the actual hinge part 20 which, projecting out of the groove 10, pushes sideways the pawls 31 against the opposition of the respective springs, so that there is no real obstacle to the descent of the hinge.
In each case, when the finger 11 ends its stroke, the stem 15 is correctly housed and centered within the plastic material previously injected into the cavity 2, while its hinge part 20 projects therefrom, in the position indicated by 20' with dotted lines.
At this stage, the mold can be opened and the bars are withdrawn finished, that is, both in their final shape determined by the mold, and with the stiffening metal stem or core provided with the respective welded hinge part, already perfectly inserted along its longitudinal median axis.
It is anyhow understood that the invention is not limited to the embodiments shown, which have been given by mere way of example, but that it covers all those embodiments, within reach of an expert in the field, in which the stem is guided onto at least one side by means apt to be removed as the stem moves down to penetrate into the mold, while the other three sides thereof are guided along a fixed guide essentially in the form of a groove.
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The present invention relates to equipment for the injection molding of spectacles bars of plastic material and for the introduction in said bars of metal stems or cores. In said equipment, the metal core--onto an end of which is previously welded the respective metal hinge--is axially inserted into the mold already filled with plastic material, wherein it is caused to slide along a grooved guide, into which it is held by means apt to be removed as the core moves forward.
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CROSS REFERENCE TO RELATED APPLICATIONS
This application is the National Stage of PCT/EP2009/050135 filed on Jan. 7, 2009, which claims priority under 35 U.S.C. §119 of German Application No. 10 2008 003 723.0 filed on Jan. 9, 2008, the disclosure of which is incorporated by reference. The international application under PCT article 21(2) was not published in English.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a pliers, such as a center cutter or a side cutter, having pliers jaws that are formed on pliers limbs and have a working region, the pliers limbs, which have gripping regions and are formed to cross over one another, being pivotably mounted by bearing bolts that connect a cover plate, and the pliers jaws being formed on the working region side of the cover plate and the cross-over region of the pliers limbs being formed on the other side of the cover plate. Here there are in question in particular high force ratio jaws, to which there belong also jaws such as pressing jaws and crimping jaws.
2. The Prior Art
A pliers of this kind is known for example from EP 331 927 B1. The disclosure content of this patent specification is hereby included in full in the disclosure of the present application, in respect of the basic construction of the pliers, in particular also in respect of the tooth-space engagement and of the run of the pliers limbs, as well as the principle of holding together by means of a cover plate, also for the purpose of incorporating features of the above-mentioned specification in claims of the present application.
Reference is also made to U.S. Pat. No. 2,806,394 A as prior art.
SUMMARY OF THE INVENTION
In regard to the known pliers, it is an object of the invention to improve the ease with which it may be handled.
This object is met according to a first aspect of the invention by the subject matter of claim 1 , it being provided that a tangential bend is formed in the pliers limbs on the gripping side relative to the cover plate, different pivot planes of the pliers limbs created thereby intersecting one another in the bend, the gripping regions running in one pivot plane and regions of the pliers limbs extending on the working region side of the tangential bend running in another pivot plane.
Because of the tangential bend, ease of handling is advantageously more favourable and improved, for example in the case that the pliers has to be placed such that the user's fingers engaging around the gripping region would already collide with a base or an upstanding feature. The tangential bend enables an advantageous separation of the working plane and the plane or the raised region in which the user's fingers engage around the handles. By virtue of the tangential bend being formed on the gripping side of the cover plate, the cutting region and also the cover-plate region of the known pliers remain unchanged. The favourable cutting properties continue to be obtained, for example in the case of a center or side cutter. In particular, a advantageous clearance for the cutter is also provided above and below.
A further solution to the problem is also provided by the features of claim 2 , it being provided that the pliers jaws are held together by only one cover plate, located on one side. In this way, placement of the pliers jaws directly against the working surface is enabled, when the single cover plate is located on the top. In principle, a cover plate may also be disposed underneath, and thus enable, in the upper side region, advantageous bringing against a workpiece or introduction into a working space.
Further features of the invention are explained below, which are in principle significant both combined with one or more of the features of the groups of features explained above, as well as however also independently.
Thus it is preferred that the cross-over region of the pliers limbs runs on the gripping side of the tangential bend. The gripping regions thus run through, in side view, together with the cross-over region of the pliers limbs, practically in a straight line. The tangential bend is then formed further toward the cover plate, preferably by virtue of bending deformation, in the pliers limb that runs through and is also preferably integral, so that the adjoining region of the pliers limbs, which is also referred as a whole as a head region of the pliers, extends in another pivot plane compared with the combined region of the gripping regions and the cross-over region.
As an alternative to this, the cross-over region of the pliers limbs may also run on the working region side of the tangential bend. The cross-over region then extends, preferably together with the portion of the pliers limbs forming the head region, in a common pivot plane, which is different from the pivot plane of the gripping regions.
More preferably, also only two different pivot planes are formed on the pliers.
It is further preferred that the cover plate is located on the inner side, when a tangential bend is provided; this means on the inner side of the angle in side view, thus in the space which encloses the smaller angle.
It is also further preferred that the rear sides of the pliers jaws, opposite from the cover plate, form a common contact face, which can be directly engaged against a workpiece or a base, because it is free of upstanding features. The rear sides of the pliers jaws, which in principle, as already stated above, may be the “upper side”, merge in this way into one another, preferably in alignment, thus form in any case a common contact plane in a substantial part of the rear side surface. A part of or the entire rear side of the cross-over region of a pliers limb in the cross-over region may also be incorporated into this contact plane. Because of the crossing-over arrangement, this rear side of the pliers limb in the region mentioned also results in additional stabilising of the contact.
The bearing mounting for the pliers jaws is further formed by means of a tooth-space engagement securing the pliers jaws to one another. This tooth-space engagement is preferably formed by a roller member. This roller member may be formed on one of the pliers jaws or also as a separate part, then preferably as a basically cylindrical pin.
When the tooth-space engagement is formed by the separate pin, it is further preferred that this bearing pin is of stepped form. A stepped embodiment of this kind enables the bearing pin to be held in a positive manner even when only one cover-plate is provided. While it is restrained against movement in one direction by the cover-plate, it is restrained against movement in the other direction—in the direction of its longitudinal axis—by the stepped formation. The stepped formation must not be formed as a continuous ongoing decrease in diameter. It may also be formed only by a groove, in which a protrusion from the pliers jaws engages.
In general form, it is provided that positive holding of the bearing bolt is achieved on the one hand by interaction with the cover plate and on the other hand by interaction with the pliers jaws.
In regard to the mounting of the preferably one cover plate by means of bearing pins, it is further preferably provided that these are held in the pliers jaws in rivet-like manner. For this, an end face of one of the bearing pins may form a part region of a rear side face of a pliers jaw or may be arranged offset relative to this; the latter preferably in the sense that a set back portion relative to the rear side face results. The other end region of the bearing pin may be formed in the manner of a rivet head.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained further below with reference to the accompanying drawing, which however relates only to an embodiment. In the drawings,
FIG. 1 is a perspective view of the pliers;
FIG. 2 is a plan view of the pliers;
FIG. 3 is a view corresponding to FIG. 3 , from the rear;
FIG. 4 shows a cross-section through the item of FIG. 3 , sectioned along the line IV-IV;
FIG. 5 shows a side view of the pliers, relating the head region, with part of the jaw limb adjoining the cover plate on the grip region side, with a first arrangement of the tangential bend;
FIG. 6 is an illustration corresponding to FIG. 5 , with a second arrangement of the tangential bend;
FIG. 7 is an illustration of the pliers in the opened state;
FIG. 8 is an illustration corresponding to FIG. 6 , showing the rear side.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Shown and described is a pliers 1 formed as a center cutter having two pliers limbs, which form gripping regions 2 , 3 , these gripping regions each continuing initially into a cross-over region K of the pliers limbs and then integrally into a pliers jaw 4 , 5 . The pliers limbs are forgings. Each gripping region 2 , 3 and pliers jaw 4 , 5 is pivotably mounted on a bearing bolt 6 , 7 . The bearing bolts 6 , 7 extend transversely to a pivot plane of the pliers jaws in the front cutting region of the pliers jaws.
The gripping regions 2 , 3 cross over each other without any pivot pin before they pass into the region of the cover plate 8 which connects the pivot bolts 7 , 6 , accordingly after they change side relative to one another. The bearing bolts 6 , 7 pass through openings in the cover plate 8 that match the cross-section of the bolts. The cover plate 8 , which is disposed on one side only, according to FIG. 1 on the upper side of the pliers shown there, is of plate-like form. The cover plate 8 , which is of substantially elongate rectangular shape, has its longitudinal axis extending transversely to the longitudinal extent of the gripping regions 2 , 3 .
In order to fix the bearing bolts 6 , 7 , these have, at one end, (cf. for example FIG. 4 ) heads 9 and at the other end, are in the form of a rivet 10 . The heads have a frustoconical shape. The rivet portions are rounded transversely.
In the region of the cutters 11 , 12 that form the working region of the pliers jaws 4 , 5 and are directed toward one another, the cover plate 8 has an inwardly rounded recess, this for example advantageously with respect to a centring action for an item to be cut, such as for example a wire.
The pliers jaws 4 , 5 are formed to be visible on the working region side of the cover plate 8 , while the cross-over region K of the pliers limbs is formed on the other side of the cover plate 8 , the gripping region side of the cover plate 8 .
A roller member 14 , cf. for example FIGS. 3 , 4 and 7 , is housed between the bearing bolts 6 , 7 , at the same spacing from each bolt. The roller member 14 forms a kind of tooth space engagement between the cutting jaws and 12 . The roller member 14 is basically of cylindrical configuration. Its edges are bevelled.
The axial length of the roller member 14 corresponds more or less to the clear space from the underside of the cover plate 8 to the contact face 15 formed by the rear side of the pliers jaws 4 , 5 , see for example FIGS. 4 to 6 . Preferably the length is a little less. The roller member 14 , which is cylindrical and extends transversely to the cutters 11 , 12 , is thus seated, respectively partially, in a corresponding through cavity formed by two cavity portions 16 , 17 of the cutters 11 , 12 , see for example FIG. 8 . Since the cutters 11 , 12 are wedge-shaped and the roller member 14 is of cylindrical shape, the cavity portions 16 , 17 have, in the exemplary embodiment, a lens-shaped wall profile.
As will be apparent from a comparison between FIGS. 1 and 7 , the roller member 14 appears to move forwards when the pliers are opened and passes partially underneath the cover plate 8 . In reality, the cover plate 8 actually moves somewhat to the rear, cf. also FIGS. 3 and 8 which relate to the view from beneath.
The roller member 14 may be formed not only as a separate part, as in the exemplary embodiment, but may also be produced to be fixedly connected to one of the pliers jaws or even integral with this. Only the other pliers jaw then has the recess 16 .
The adjoining offset cross-over region K of the gripping regions 2 , 3 , on the gripping side behind the cover plate 8 , is clearly widened as compared with the gripping zone and the jaw zone (see for example the plan view according to FIG. 1 ). As a rule, the faces of the pliers limbs in this cross-over region K do not however engage on one another, but move with a spacing with respect to each other.
Referring to a side view, as is shown for example in FIGS. 5 and 6 , the tangential bend A is formed in each case on the gripping side of the cover plate 8 . The portions of the pliers limbs adjoining the tangential bend A to each side thus run in different pivot planes E 1 -E 1 and E 2 -E 2 respectively. The pivot planes E 1 -E 1 and E 2 -E 2 intersect one another in the region of the tangential bend A.
In the exemplary embodiment of FIG. 5 ( FIGS. 1 to 3 and 7 , 8 also relate in each case to this embodiment), the pliers jaws which appear in the side view in the form of plates that are as a whole in one piece and the region of the pliers limbs that extends underneath the cover plate run in the pivot plane E 1 -E 1 , while the cross-over region K together with the gripping regions 2 , 3 extends in the pivot plane E 2 -E 2 . The planes E 1 -E 1 and E 2 -E 2 together enclose an angle alpha, which is less than 180°.
The respective tangential bend A is, in further detail, formed by a bendingly formed portion 18 . The bendingly formed portion 18 is formed in the region of the pliers limb that is considerably reduced in thickness compared with the gripping regions 2 , 3 ; in the case of the embodiment according to FIG. 5 , also—seen form the cover plate 8 —before the step S formed in one pliers limb, which on the one hand is necessary for the cross-over of the pliers limbs, on the other hand, in the case of the other pliers limb, see for example FIG. 1 , is provided as a stabilising built-up mass of material. In this case, the notch-like cut between the cover plate and the step S or the related built-up material of the other pliers limb is also used for the bend.
The reduction in thickness is 10 to 70%, preferably for example 40 to 50%, of the thickness in the gripping region 2 , 3 . In this regard, with reference to the larger percent range, all intermediate values are also included in the disclosure.
The pliers 1 has only one cover plate 8 . With reference to the angle alpha, cf. FIGS. 5 , 6 , which in each case characterises the tangential bend A, this cover plate 8 is disposed in the interior of the angle.
On the side facing away from the cover plate 8 , the rear side of the pliers jaws 4 , 5 , the pliers jaws 4 , 5 form a common planar contact face 15 . In the exemplary embodiment, this contact face 15 extends, as shown, over practically the entire transverse region of the secured-together pliers jaws 4 , 5 and, in the elongate direction of the pliers, from a tip 19 as far as the tangential bend A. This contact plane is also free of upstanding features. It is therefore not for example interrupted by projecting pin portions or rivet heads. It is therefore suitable for direct engagement against a workpiece or for contact against a base.
In the case of the exemplary embodiment of FIG. 6 , the cross-over region K, or the rear side of this, is also incorporated into the contact face 15 . By contrast, in the case of the exemplary embodiment of FIG. 5 , only the rear side region of the pliers limbs that extends from the tip 19 as far as the tangential bend A, or the pliers jaws 4 , 5 formed by this, is incorporated into the contact face 15 .
In further detail, it is important that the angle alpha is between 110° and 175°; preferably between 150° and 165°, all degree values as well as fractions of degrees of the first range noted being here included in the disclosure.
The heads 9 mentioned of the bearing bolts 6 , 7 passing through the cover plate 8 form a planar, lower, outwardly lying boundary surface, which likewise lies in the contact face 15 mentioned or is optionally set back somewhat relative to this in the direction of the cover plate 8 .
In the same manner, the roller member 14 forms a lower end face, which likewise lies in the contact face 15 or, as in the case of the exemplary embodiment, is set back slightly from this in the direction of the cover plate 8 .
The roller member 8 itself is formed in a stepped manner. It has an upper larger-diameter region 14 a and a lower smaller-diameter region 14 b , see FIG. 4 .
Since the transition between the regions 14 a and 14 b is located at a corresponding shoulder 20 of the pliers jaws 4 , 5 and on the other hand, as already mentioned, the roller member 14 is covered, in the upward direction, by the cover plate 8 , the roller member 14 is thus secured in the pliers head in a positive manner.
All features disclosed are (in themselves) pertinent to the invention. The disclosure contents of the associated/attached priority documents (copy of the prior application) are hereby also included in full in the disclosure of the application, also for the purpose of incorporating features of these documents in claims of the present application.
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Pliers ( 1) as middle cutter or side cutter having plier jaws ( 4, 5) configured on plier legs, with a work range, wherein the plier legs with grip areas ( 2, 3) and configured to cross over one another around bearing bolts ( 6, 7) connected by a cover plate ( 8) are pivotably supported. The plier jaws on the working region side of the cover plate ( 8) and the crossing region (K) of the plier legs are configured on the other side of the cover plate ( 8). In order to improve the handling of these pliers, that relative to a side elevation, on the grip side with respect to the cover plate ( 8) in the plier legs, a tangential bend (A) is configured in which resultantly created different pivot planes (E 1 -E 1) or (E 2 -E 2) of the plier legs cross one another. The grip areas ( 2, 3) run in one pivot plane (E 2 -E 2) and in another pivot plane (E 1 -E 1) areas of the plier legs extended on the work range side of the tangential bend (A) run.
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BACKGROUND OF THE INVENTION
The invention relates to a radial press for workpieces with rotationally symmetrical outside surface, with a
(a) A plurality of press jaws disposed in a circle around the axis of the workpiece outer surface, which are movable radially to this axis and whose outsides have at least two first planar controlling surfaces sloping with respect to the axis and disposed V-wise, which run between two parallel lateral guiding surfaces disposed on the press jaws, the bisector of the "V" being aligned radially and the surface normals passing through the centroids of the controlling surface intersecting the axis,
(b) Control bodies whose insides each have at least one likewise planar, second controlling surface cooperating with the corresponding controlling surfaces of the press jaws,
(c) A drive means producing the axial displacement of the control bodies relative to one another.
The term, "rotationally symmetrical outside surface," as used herein, is to be interpreted to mean workpiece shapes having circular cross sections and cross sections in the form of regular polygons, such as are found in hexagonal or octagonal rolled stock. The outside surfaces of the workpieces can at the same time be rectilinear in the axial direction, barrel-shaped, or stepped. Such workpiece surfaces can be accommodated by constructing the press jaws accordingly. A special field of application for which the subject matter of the invention is preferentially suited is the joining of hose fittings consisting of steel to flexible hoses, as well as the production of cable thimbles.
In a known radial press described in PCT application No. WO 81/03456, both the controlling surfaces of the press jaws and the controlling surfaces of the control bodies are conical surfaces or sectors of these conical surfaces. The controlling surfaces of the press jaws are sectors of truncoconical surfaces whose base surfaces, of equal size, are identical. Two intersecting generatrices of these conical surfaces consequently form a wide-open "V" whose bisector is precisely radial to the axis A of press and workpiece.
As a rule, one of the two control bodies is fixed, and the other control body is displaced axially by a hydraulic drive against the fixed control body. Due to the above-described configuration of all controlling surfaces, the press jaws cover exactly half of the distance in the axial direction which is covered by the moving control body. It is apparent that a precisely full-surface contact between the cooperating controlling surfaces is possible only in one very specific axial position. Above and below this point of full-surface contact, contact takes place only along a central generatrix of the controlling surface of the press jaw, or along the two farthest outside longitudinal edges of the controlling surface of the particular press jaw. This peculiarity of conical controlling surfaces brings it about that, at high press forces, such as those occurring especially in the pressing of hose fittings, extremely high surface loading occurs, and resulting frequency in the breakdown of the lubricant film, so that a stiffness or low efficiency of the press is the result. Consequently, due to the response of an overload protection (pressure relief valve in the hydraulic drive), the operation of the press comes to a halt before the pressing operation has reliably been completed. Later this can endanger personnel, considering that hydraulic hoses with their fittings can be subjected to internal pressures of 1000 bars and more.
To forestall excessive wear due to the extreme line-of-contact pressures, the motion controlling surfaces are, as a rule, hardened. This requires either the use of materials that can be hardened on-site, or the use of materials which can be case-hardened by a so-called "pack hardening" process through diffusion into the surface at high temperatures. This heat treatment, which is necessary in any case, regularly results in a distortion of the workpieces, which has to be minimized by complex design measures, and the distortion, which can not be entirely avoided, must be compensated by grinding to dimension. Such materials, and their manufacturing and processing, are expensive and complicated, and even so they do not bring the desired success in every case.
Also, on account of the transition from line contact to surface contact to line contact, instabilities occur in the pressing process between the cooperating motion controlling surfaces. On the one hand when the press jaws make contact along their center lines they tend to rock about these lines so that the pressing results on the finished workpiece are not always precisely the same, and on the other hand the sliding of the press jaws on the motion control bodies is not uniform at both ends of the press jaws, so that the longitudinal axes of the press jaws are not always precisely parallel to the press axis.
The above-described instabilities can still be overcome to some extent as long as pressing at low pressing forces and/or small workpiece diameters is involved, as is the case in crimping operations in which a sheet metal fitting is pressed onto a low-pressure hydraulic hose with the formation of serrations. At high press pressures, therefore, the initially described, double-sided pressing jaws have, as a rule, been avoided, and instead pressing jaws that act unilaterally have been used, which are operated by a single motion control body and are supported for radial displacement on the face end of an anvil on which they are mounted for radial movement, with the aid in some cases of dovetail guides.
If the radial dovetail guides are not used, and conical motion controlling surfaces are used, the disadvantage is encountered that the press jaws have the tendency to distribute themselves irregularly on the circumference of the workpiece, so that the so-called "pressing center," i.e., the sum of the vectors of all individual forces no longer coincides with the press axis. This too leads to irregular results. The return springs usually used for spreading the press jaws apart cannot, in any case, prevent the unequal distribution of the press jaws.
Furthermore the useful stroke, in the case of press jaws operated by a motion control body, is shorter, because the press jaws are given a tilting stress by the shifting attack of the motion control body, so that a relatively great overlapping of the motion controlling surfaces is necessary.
To the extent that multilaterally operating presses are disclosed by U.S. Pat. No. 4,535,689 (FIGS. 18 and 19), the planar motion controlling surfaces of the press jaws are formed by the surfaces of wedge-shaped bodies which engage one another alternately from opposite directions and are guided in face-end plates of a press frame. Due to the alternate engagement of the wedges a considerable amount of motion control area is lost, i.e., the press jaws are supported by the wedges on no more than half of their outer surfaces, so that, at a given pressing force, at least twice the pressure per unit area occurs. The guidance in the press frame is only indirect, in a kind of overhung mounting, so that the lateral guidance is but slight in spite of the enormous amount of space required by the arrangement. The axis-parallel contact surfaces for the wedges provide the press jaws in any case with no kind of lateral or transverse guidance. In the given manner of construction it is not possible to arrange more than four pairs of motion control wedges or more than four press jaws around the workpiece. Lastly, maintenance is also problematical, since the lubrication points are very much concealed, so that the press has to be at least partially disassembled for lubricating purposes.
The invention is therefore addressed to the object of improving a radial press of the kind described above such that its efficiency will be increased, that it will permit uniform pressures all the way to the end of the press action, and that both the manufacturing and the maintenance costs will be reduced accordingly.
SUMMARY OF THE INVENTION
The achievement of the described object is accomplished according to the invention, in the radial press described above, by the fact that:
(d) The second motion controlling surfaces are disposed in two motion control bodies constructed as plates,
(e) The motion control bodies are each provided with grooves corresponding to the number of press jaws whose sidewalls run parallel and are guiding surfaces for the press jaws and whose groove bottom forming the particular motion controlling surface is flat and has the same slope in the axial direction as the corresponding motion controlling surface of the press jaw,
(f) The motion controlling surfaces cooperating in pairs are configured and arranged in mirror-image symmetry with respect to a radial plane lying between the motion control bodies, and
(g) Between the motion controlling surfaces of the motion control bodies and the motion controlling surfaces of the press jaws plates of a bearing material are inserted whose bearing portion is defined by plane-parallel surfaces.
By the above-named features it is brought about that, at the end of each press stroke, the entire area of the motion controlling surfaces of the press jaws is utilized, so that the press jaws are completely supported. The press jaws in this case are guided perfectly in the motion control bodies, i.e., in their grooves, the base of which forms the motion controlling surface. This direct guidance of the jaws in the transverse direction, however, serves not only for the guidance of the jaws but also for the reliable holding of the plates made of a bearing material. The guidance, and the transfer of the very high pressing forces is consequently possible within a very small space, so that more than four press jaws can be distributed around the circumference of the workpiece. This greatly improves the distribution of the pressing forces. It is to be noted in this case that the flow of the workpiece that takes place in the pressing operation is greatly dependent upon a uniform distribution of the pressing forces.
The bearing plates simply laid in the grooves of the motion control bodies eliminate all lubrication problems. If these bearing plates should wear out, it is very simple to replace them with new bearing plates. On the other parts of the press there is no appreciable wear, and cheaper, unhardened materials can be used, so that distortion due to hardening is eliminated. The lower pressure per unit area relative to the conditions according to U.S. Pat. No. 4,535,689 leads also to another advantage, namely to the possibility of giving the motion controlling surfaces a greater angle of attack in relation to the press axis. The greater this angle of attack is, the greater will be the radial stroke of the press jaws upon the relative axial movement of the motion control bodies. The greater this radial stroke is, the greater can be the bulk of parts which are inserted into the press, e.g., fittings of complicated shape, elbows, or the like.
In comparison to presses with conical motion controlling surfaces the advantages are retained that transitions from surface contact to line contact, press jaw canting, varying stresses per unit area and high friction losses are avoided and a very uniform flow-pressing is made possible. Breakdown of the lubricant film can no longer occur. Thus the driving forces are also reduced, so that smaller and lighter, transportable presses can be made. Nevertheless, each pressing operation is reliably carried out to the end.
It is especially advantageous if the motion controlling surfaces cooperating in pairs are arranged in mirror-image symmetry with respect to a radial plane situated between the motion control bodies. Thus it will be possible, in spite of a great radial jaw stroke length, to achieve a press of short axial overall length. This advantage is important especially in conjunction with the hose presses described above, because in these presses, either on account of the complicated shape of the fittings and/or on account of the need to press fittings onto individual sections of hose so as to form continuous lengths, a great amount of free space in both the radial and the axial direction is required in back of the press. The shorter the press is, the greater is its usefulness.
At the same time it is again advantageous for the insert plates to be made of a bearing material with self-lubricating properties. Such a bearing material is marketed under the name, "KS-DU", in the form of laminated plates or strips, for example under license from the firm of Glacier Metal Company Limited, Great Britain. Such friction bearing plates have an extremely low friction coefficient of 0.02. Thus the friction losses amount to no more than about 5% as compared with 30% in conventional designs, so that the driving forces can be lower without reducing the closing force of the press tool. A hose press equipped with such bearing plates is virtually maintenance-free, since the self-lubricating bearing material eliminates the need to relubricate the highly stressed surfaces.
It is especially advantageous, again, for the plates consisting of bearing material to have tabs bent down at both ends of the bearing portion so as to overlap the radial face ends of the motion control bodies. Such plates can then simply be laid in the press between the controlling surfaces. Then the only other thing that might be done would be to put screws through the tabs.
The construction of the radial press according to the invention makes it possible to increase considerably, in comparison to conventional designs, the angle of the controlling surfaces with respect to the press axis, from about 10 degrees to more than 20 degrees, for example. Even a controlling surface angle of 26.5 degrees has proven practicable in one example. For a given axial displacement of the control bodies relative to one another, such a steep angle results in a correspondingly greater radial stroke of the press jaws, and this in turn makes it possible to insert workpieces of more complex configuration, such as elbowed fittings for example. For this purpose a correspondingly greater no-load stroke beginning from the radially outermost end of the press jaw motion is necessary. To accomplish this, radial presses have been created in the state of the art which have composite controlling surfaces of varying pitch, and which are very expensive to manufacture. This expense can be avoided by the subject matter of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Additional advantageous developments of the subject matter of the invention will appear from the following description of an embodiment, in conjunction with FIGS. 1 to 7, wherein:
FIG. 1 shows a partially offset vertical section through the radial press (taken along line I--I) in FIG. 3, with the press jaws fully opened.
FIG. 2 is a partial vertical section through the radial press with the press jaws fully closed,
FIG. 3 is a top view, partially in section, of the end face of the radial press (seen from the left in FIG. 1),
FIG. 4 is a perspective view of a single press jaw,
FIGS. 5 and 6 are perspective views of the two plates of bearing material belonging to a press jaw, and
FIG. 7 is a photomicrographic cross-section through a bearing material for the plates according to FIGS. 5 and 6.
FIG. 8 is a perspective view of a control body.
FIG. 9 is a perspective view of a control body illustrating the geometric lines of the body.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In FIGS. 1 to 3 there are represented a stationary control body 1 and a movable control body 2 which is displaceable against the control body 1 by the action of a hydraulic drive means 3. The hydraulic drive means 3 consists of two or four hydraulic cylinders which thrust against the control body 2, and of pistons 5 and piston rods 6 which simultaneously serve as tension rods and are affixed to the control body 1 by screws 7. As a hydraulic fluid is pumped into the hydraulic cylinder 4 on the left of piston 5, the control body 2 is displaced leftward with a speed corresponding to the pumping power (i.e. pumped hydraulic fluid per unit of time of the hydraulic unit (not shown), until the end position is reached in which the control bodies 1 and 2 have the closest possible distance from each other.
A hydraulic drive of the kind described above, and its advantages, are explained in DE-OS 35 12 241 of the same applicant and corresponding to U.S. patent application Ser. No. 070,165 filed on July 1, 1987 based on U.S. Ser. No. 841,935 filed on Mar. 20, 1986 now abandoned, the application herein incorporated by reference. However, in the present case it is also possible to use a central piston drive in conjunction with additional tension rods.
The piston rods 6 are guiding elements which pass through the movable control body 2, which is provided with bushes 8 at the opening through which they pass. With the exception of the points of contact with the piston rods 6, the control bodies 1 and 2 are of a mirror-image configuration in relation to a radial plane of symmetry E--E lying between them, including the controlling surfaces which are to be further described below.
The control bodies 1 and 2, which are in the form of plane-parallel plates of square profile, each have a passage opening 9 and 10, respectively, whose envelope surface is in each case in the form of a truncated cone, while the larger base surfaces of the truncated cones face the plane of symmetry E--E. The openings 9 and 10 serve to accommodate a workpiece 11 which consists of a hose 11a and a sleeve 11b which is to be pressed thereon, and which is part of a hose fitting with an elbow 11c and a connecting nut 11d. It can be seen that the workpiece 11 is of relatively awkward shape, so that it requires the press jaws, which are to be further described below, to be able to open very wide to permit the workpiece to be inserted into the press.
Grooves 12 and 13 are machined into the control bodies 1 and 2 at equal distances around the circumference of the openings 9 and 10, respectively, and their bottoms form controlling surfaces 14 and 15, respectively. These controlling surfaces 14 and 15 are flat and have a defined slope of, for example, 26.5 degrees with reference to the axis A--A. The surface normals N passing through the centroids C of the controlling surfaces 14 and 15 all intersect the said axis A--A.
The grooves 12 and 13 have sidewalls 16 and 17 which run parallel to each groove and constitute surfaces for the guidance of press jaws 18, part of which has been omitted from FIG. 1 for the sake of clarity. Each of the press jaws 18 consists of a base jaw 18a and a jaw facing 18b (the latter represented in broken lines in FIG. 1). In a mirror-image relationship to the plane of symmetry E--E, the press jaws 18 have on their outer sides 2 the controlling surfaces 19 and 20 which have the same slope in the axial direction as the controlling surfaces 14 and 15 in the control bodies 1 and 2. The controlling surfaces 19 and 20 can also be imagined as being formed by generatrices oriented V-wise which are displaced parallel to themselves in a straight line.
As it appears especially in FIG. 4, the controlling surfaces 19 and 20 extend between two parallel lateral guiding surfaces 21 and 22 of which the rear one is concealed from view. The press jaws 18 are engaged with these guiding surfaces in the grooves 12 and 13, i.e., the guiding surfaces are in contact with the sidewalls 16 and 17 of the grooves. It is not necessary for the guiding surfaces 21 and 22 to be offset step-wise from the outer surfaces of the base jaws 18a lying above them. Instead, a step-less transition is possible, as is represented in FIG. 2 for the lower press jaw 18 that is shown there.
Between the controlling surfaces 14 and 15 of the motion control bodies 1 and 2 and the controlling surfaces 19 and 20 of the press jaws 18 are the plates 23 and 24 which consist of a bearing material. As it appears in FIGS. 5 and 6, these plates 23 and 24 have a middle, load-bearing portion defined by the plane-parallel surfaces 23a/23b and 24a/24b, respectively. The plates 23 and 24 have end tabs 23c and 23d, and 24c and 24d, respectively, which are bent down at both ends of the bearing portion. With these tabs the plates 23 and 24 overlap the radial end faces of the motion control bodies 1 and 2, as represented in FIGS. 1 and 2.
As it also appears in FIGS. 1 and 3, the base jaws 18a have each a locking screw 25 in their center by which the jaw facings 18b are held removably. Backing for the thrust of the locking screws 25 is provided by hook-like projections 26 disposed in the middle of the press jaws, which interlock with the dovetails 18c of the jaw facings 18b (FIG. 4).
On the side opposite the dovetail 18c, the jaw facings 18b have a working surface 18d which determines the shape of the workpiece, and in the present case is formed of a sector of a cylindrical surface.
It can be seen in FIG. 1 that a micrometer screw 27 is fastened to the control body 2, and a limit switch 28 is fastened to the control body 1. As soon as the end 27a of the micrometer screw encounters a plunger pin 28a of the limit switch, the end of the forming operation is reached and the drive means 3 is shut off by the limit switch 28. Such an end position is represented in FIG. 2.
It can furthermore be seen in FIG. 2 that, instead of the pressing of a workpiece 11 with an elbow 11c, the connection of a workpiece 11 to another workpiece 29 can be made, to which belongs a hose 29a on which a sleeve 29b has already been pressed in the same manner.
In FIG. 3 it can be seen that the hydraulic drive means can consist of either two or four hydraulic cylinders which are connected together in parallel by a hydraulic line 30, and are supplied with hydraulic fluid through a connection 31. It can furthermore be seen how the grooves 12 are distributed equidistantly on the circumference of the opening 9. Between the grooves 12 are fillets 32 which are defined by the sidewalls 16 of the grooves 12. The maximum outward position of the working surfaces 18d of the press jaws 18 is indicated by a circle with the diameter Da, and the maximum inward position, which corresponds to the final diameter of the workpiece, is indicated by the circle with the diameter Di. When the position of the working surfaces 18d reaches the inside diameter Di, the press jaws 18 and their jaw facings 18b are virtually side by side with no interval between them, so that the working surfaces 18d make up a cylinder, as represented in the upper half of FIG. 3.
It can also be seen in FIG. 3 that, between directly adjacent press jaws 18, compression springs 33 are provided which thrust tangentially against the press jaws and thereby return the press jaws 18 by means of their radial component of force to their initial position represented in FIG. 1 when the control bodies 1 and 2 are shifted apart. It must be emphasized that the compression springs 33 have no effect on the position of the press jaws circumferentially, since this position is determined exclusively by the sidewalls 16 and 17 of grooves 12 and 13, respectively, in conjunction with the guiding surfaces 21 and 22 on the press jaws. This can very clearly be seen also in the bottom half of FIG. 3.
In FIG. 7 there is also shown a photomicrograph of a cross section through the plates 23 and 24 in accordance with FIGS. 5 and 6. These plates consist of a backing of sheet steel and the actual bearing material 35, the two being bonded tightly to one another by a copper layer 36. The bearing material 35 consists of an originally highly porous tin-bronze layer 37 whose interstices are filled with a solid mass of polytetrafluorethylene (PTFE) with lead particles. This bearing material has self-lubricating properties which are retained over a long period of time, and the effect whereby the lubricating properties increase with increasing surface pressure can also be observed. The common "sticking" of a radial press, which can be observed when the design surface pressure is exceeded, does not occur with this bearing material even though the design data are otherwise identical.
The bottom of the grooves 12 and 13 are always referred to above as a motion controlling surface. However, it is just as easy to consider the radially inward-facing bearing surfaces of plates 23 and 24 as controlling surfaces, inasmuch as the said surfaces are displaced radially only by the thickness of the plates 23 and 24.
FIGS. 8 and 9 are perspective views of a control body 1 illustrating the grooves 12. Each groove 12 has parallel side walls 1b and a bottom or motion controlling surface which corresponds to and accommodates the control surfaces of the plate 23.
As shown in FIG. 8, a control body is machined from a rectangular shaped block to form a hollow truncated cone having a top TC, a smaller circle SM and a base circle BC. In the walls of the cone, grooves 12 are machined having a flat bottom which act as a cone surface for the press jaws. The grooves 12 have side walls 16 which are parallel to each other. The lines of symmetry of all the cam or controlling surfaces intersect the axis A--A at the point SL. Thus, the cam or controlling surfaces have a slope relative to the axis A--A and the normals N drawn in the centers of the cam surfaces also intersect the axis A--A at the points P. Additionally the V-shaped surfaces of the press jaws are shown in FIG. 1 to be bisected by the line BIS.
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A radial press with a plurality of press jaws whose outer sides have at least two control surfaces configured at an angle to the press axis in a V-shaped arrangement. These jaws are moved in the radial direction by two control bodies, each of whose inner sides have at least one control surface cooperating with the corresponding control surfaces of the press jaws. The axial displacement of the control bodies relative to one another is performed by a drive means. The control surfaces of the press jaws and of the control bodies are planar surfaces with a slope in the direction of the axis, whose surface normals through the centroids of the surfaces intersect the axis. The control surfaces of the control bodies form the bottom surfaces of grooves whose sidewalls run parallel and are surfaces for guiding the press jaws. Between the control surfaces of the control bodies and the control surfaces of the press jaws, plates of a bearing material are inserted.
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RELATED APPLICATIONS
This is a 35 USC 371 U.S. National Phase of International Application No. PCT/KR2008/007341, filed 11 Dec. 2008 and published in English as WO 2010/067910A1 on 17 Jun. 2010. The contents of the aforementioned application are incorporated by reference in their entirety.
TECHNICAL FIELD
The present invention generally relates to cutting tools, and more particularly to a milling cutting tool having a simple structure for performing a high-speed process to stably secure a cutting insert to a pocket part of a tool body.
BACKGROUND ART
A cutting insert mounted on a milling cutting tool for performing a high-speed process generally receives a considerable amount of cutting load during a cutting process. Accordingly, it is critical for the cutting insert used in the milling cutting tool to be reliably secured to the cutting tool body even under such a cutting load.
Generally, the cutting tool body includes a pocket part wherein the cutting insert is mounted. Said pocket part consists of a bottom surface and two planar side surfaces. The cutting insert is provided with a through-hole, through which the cutting insert is secured to the pocket part using a screw. Further, a lower surface and a side surface of said cutting insert contact a bottom surface and a side surface of the pocket part, wherein the cutting insert is pressurized and supported.
However, the bottom and side surfaces of the pocket part are not structured to provide any support to the cutting insert against the cutting load applied in the outward direction of the main body of the milling tool. This allows said cutting load to be transferred directly to the cutting insert, eventually applying an excessive force onto a screw and possibly causing damage to the screw. To lower the chances of damage, the cutting transfer speed and the cutting depth must be limited.
In order to solve such a problem, as shown in FIG. 1 , there has been introduced a technique of forming projections ( 40 ) in the teeth shape on the lower surface ( 20 ) of the cutting insert ( 10 ) and grooves for receiving such projections on the bottom surface of the pocket part of the main body where the cutting insert ( 10 ) sits in. The cutting insert may be supported by the projections and the grooves, which provide the cutting insert with good resistance against the cutting load exerted in the outward direction of the main body of the tool. As such, the problem of the prior art can be resolved while ensuring a reliable fixing of the cutting insert to the main body.
However, the cutting insert should be configured such that the side and lower surfaces of the cutting insert contact the side and bottom surfaces of the pocket part of the main body. Further, it should also be configured such that the teeth-shaped projections of the cutting insert precisely fit in the grooves of the main body of the pocket part. Accordingly, the side and lower surfaces of the cutting insert and the pocket part must be produced in a precise manner. However, this inevitably increases manufacturing costs.
FIG. 2 illustrates another conventional cutting insert ( 50 ). The lower surface ( 55 ) of the cutting insert ( 50 ) is provided with concaves ( 60 ) in a V-shape. However, since it is difficult to polish the lower surface ( 55 ) due to its geometrical structure, the lower surface cannot be brought to a precise process. This causes the lower surface ( 55 ) not to precisely contact the bottom surface of the pocket part, thus failing to stably secure the cutting insert. Moreover, a super alloy cutting insert generally tends to be weak against a tensioning force but strong against a compressing force. Thus, in a structure providing concaves ( 60 ) to the lower surface ( 55 ) of the cutting insert, a predetermined opposing force to the pressuring force provided by the screw is generated at the projections ( 65 ) of the bottom surface of the pocket part, wherein said opposing force is applied to the cutting insert as the tensioning force. This can result in creating cracks around the concaves ( 60 ).
FIG. 3 illustrates yet another example of a conventional cutting insert ( 70 ). The lower surface ( 75 ) of the cutting insert ( 70 ) is provided with projections ( 80 ) on a portion of said lower surface. Further, the bottom surface of the pocket part is provided with concaves ( 85 ) receiving the projections ( 80 ). However, a gap is formed between the lower surface ( 90 ) and the bottom surface ( 75 ) of the pocket part. Accordingly, an excessive force may be applied to the screw during screw-fastening for securing the cutting insert to the bottom surface of the pocket part, which can damage the screw. In addition, from the concaves of the pocket part, the projections receive a predetermined opposing force to the cutting load, wherein said force is applied in the outward direction of the main body of the tool, thus ultimately damaging the projections.
SUMMARY
The present invention is designed to solve the above problems associated with the conventional cutting tools. It is an object of the present invention to provide a cutting tool, which is configured to be simple in structure, while being capable of reliably securing a cutting insert to the pocket part of the main body of the tool.
In order to achieve the above objective, the cutting tool of the present invention is configured to have a cutting insert and a main body, wherein said cutting insert comprises an upper surface, a lower surface and a side surface connecting the upper surface and the lower surface, and wherein said main body comprises a pocket part where the cutting insert is mounted. Said lower surface forms a downwardly convex configuration as a whole and includes: a base surface; a first inclined surface extending toward the upper surface from the inner end of the base surface and being inclined in the inward direction of the main body from the base surface when the cutting insert is mounted in the pocket part; and a second inclined surface extending toward the upper surface from the outer end of the base surface and being inclined in the outward direction of the main body from the base surface. Said pocket part includes a side surface and a bottom surface, wherein said side surface of the cutting insert contacts the side surface of the pocket part on the surface, and wherein said second inclined surface of the cutting insert contacts the bottom surface of the pocket part on the surface. Said bottom surface of the pocket part forms a concave configuration as a whole and includes: a base surface facing the base surface of the cutting insert; a first pocket part inclined surface which contacts the first inclined surface on the surface; and a second pocket part inclined surface which contacts the second inclined surface on the surface.
In the cutting tool according to the present invention, the base surface and the first inclined surface may be configured so as to be placed with a space from the bottom surface of the pocket part. The second inclined surface may be polished in order to contact the bottom surface of the pocket part on the surface.
According to the present invention, the second inclined surface, which is provided to the lower surface of the cutting insert, contacts the bottom surface of the pocket part on the surface, thereby providing a predetermined resistance against the cutting load outwardly applied from the main body. As such, the cutting insert can be reliably mounted onto the pocket part of the main body. In addition, the lower surface of the cutting insert and the bottom surface of the pocket part of the main body can be formed to have a simple configuration. Also, the number of surfaces where the cutting insert and the pocket part of the main body contact is minimized. This facilitates the manufacture of the cutting insert and the main body of the tool.
Moreover, the entire portion of the lower surface of the cutting insert is in the downwardly convex shape. This allows the cutting insert to receive a compressing force from the bottom surface of the pocket part without any tensioning force when the cutting insert is pressurized against the pocket part by a screw. Generally, a super alloy cutting insert, which is weak against the tensioning force but strong against the compressing force, is advantageous in terms of strength. Further, any damage to the cutting insert can be reduced with a predetermined opposing force to the cutting load outwardly applied to the cutting insert (the opposing force provided by the bottom surface of the pocket part) compared to the structure of convex projections provided to a portion of the planar lower surface according to the prior art.
DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic view of a cutting insert according to the prior art.
FIG. 2 is a schematic view of another cutting insert according to the prior art.
FIG. 3 is a schematic view of yet another cutting insert according to the prior art.
FIG. 4 is a perspective view showing an upper portion of a cutting insert according to an embodiment of the present invention.
FIG. 5 is a perspective view showing a lower portion of the cutting insert according to an embodiment of the present invention.
FIG. 6 is a lateral view of the cutting insert according to an embodiment of the present invention.
FIG. 7 is a perspective view showing a pocket part of a main body of a cutting tool according to an embodiment of the present invention.
FIG. 8 is a perspective view showing a cutting tool wherein a cutting insert according to an embodiment of the present invention is mounted.
FIG. 9 is a schematic view of a side end surface of the cutting insert according to an embodiment of the present invention.
FIG. 10 is a schematic view of a side cross-section of the cutting insert according to another embodiment of the present invention.
DETAILED DESCRIPTION
The present invention will now be described with reference to the accompanying drawings.
FIGS. 4 and 5 are perspective views respectively showing an upper portion and a lower portion of the cutting insert ( 100 ) according to an embodiment of the present invention. FIG. 6 is a lateral view of the cutting insert according to an embodiment of the present invention. FIG. 7 is a perspective view showing a pocket part of a main body of a cutting tool according to an embodiment of the present invention. With reference to FIGS. 4 and 5 , the cutting insert ( 100 ) comprises an upper surface ( 110 ), a lower surface ( 130 ) and a side surface ( 120 ) connecting the upper surface ( 110 ) and the lower surface ( 130 ). The cutting insert ( 100 ) is provided with a through-hole ( 150 ), which passes through a center of the upper surface ( 110 ) and the lower surface ( 130 ). The cutting insert ( 100 ) is secured to a pocket part ( 300 ) of a main body ( 200 ) of a cutting tool by a screw (not shown), which is inserted through the through-hole ( 150 ). The lower surface ( 130 ) of the cutting insert ( 100 ) forms a downwardly convex configuration as a whole and includes a flat base surface ( 132 ) and end portions of the base surface ( 132 ). Both end portions consists of a first inclined surface ( 134 ) and a second inclined surface ( 136 ) extending toward the upper surface ( 110 ) from the inner end and the outer end of the base surface ( 132 ). Further, as shown in FIGS. 6 and 9 , the first inclined surface ( 134 ) is inclined to the base surface ( 132 ) in the inward direction of the main body ( 200 ) when the cutting insert ( 100 ) is mounted onto the pocket part. The second inclined surface ( 136 ) is inclined to the base surface ( 132 ) in the outward direction (indicated by an arrow in FIGS. 9 and 10 ) of the main body when the cutting insert ( 100 ) is mounted in the pocket ( 300 ).
With reference to FIG. 7 , the main body ( 200 ) of the cutting tool includes a pocket part ( 300 ) where the cutting insert ( 100 ) is mounted. The pocket part ( 300 ) includes side surfaces ( 320 , 340 ) and a bottom surface ( 360 ). Corresponding to the convex configuration of the lower surface ( 130 ) of the cutting insert ( 100 ), the bottom surface ( 360 ) of the pocket part ( 300 ) includes a base surface ( 362 ), and a first pocket part inclined surface ( 364 ) and a second pocket part inclined surface ( 366 ) extending from the both ends of the base surface ( 362 ), forming a concave configuration. The first pocket part inclined surface ( 364 ), the second pocket part inclined surface ( 366 ) and base surface ( 362 ) of the pocket part ( 300 ) face the first inclined surface ( 134 ), the second inclined surface ( 136 ) and the base surface ( 132 ) of the cutting insert ( 100 ), respectively.
Preferably, inclination angles of the second inclined surface ( 136 ) of the lower surface ( 130 ) of the cutting insert ( 100 ) and the second pocket part inclined surface ( 366 ) of the pocket part to the base surface ( 132 ) are approximately between 160 and 170 degrees. If the inclination angles are greater than 170 degrees, then the second inclined surface ( 136 ) of the cutting insert ( 100 ) and the second pocket part inclined surface ( 366 ) of the pocket part are not inclined so sufficiently that the cutting insert ( 100 ) cannot be provided with a sufficient resistance against the cutting load exerted in the outward direction of the main body from the second pocket part inclined surface ( 366 ) of the pocket part ( 300 ). If the inclination angles are smaller than 160 degrees, then the main body of cutting tool can be damaged since thickness of an outer portion formed by the second pocket part inclined surface ( 366 ) of the pocket part ( 300 ) becomes smaller and strength thereof becomes weaker. Most preferably, the inclination angles of the second inclined surface ( 136 ) of the lower surface of the cutting insert ( 100 ) and the second pocket part inclined surface ( 366 ) of the pocket part to the base surface ( 132 ) must be 165 degrees.
The first inclined surface ( 134 ) and the second inclined surface ( 136 ) of the cutting insert ( 100 ) contact the first pocket part inclined surface ( 364 ) and the second pocket part inclined surface ( 366 ) of the pocket part ( 300 ) on the surfaces, respectively, and are supported thereon when the cutting insert ( 100 ) is mounted onto the pocket part ( 300 ). Thus, a predetermined opposing force (i.e. supporting force) from the second pocket part inclined surface ( 366 ) of the pocket part ( 300 ) against the cutting load applied in the outward direction from the main body ( 200 ) is applied to the cutting insert ( 100 ) and a force applied to the screw is alleviated as the opposing force. Accordingly, the likelihood of causing a damage of the screw can be alleviated while the cutting insert ( 100 ) can be reliably fastened to the pocket part ( 300 ).
FIG. 10 is a schematic view of a side cross-section of the cutting insert according to another embodiment of the present invention. (The through-hole ( 150 ) and the screw are omitted for convenience of the description.) With reference to FIG. 10 , in this embodiment, the first inclined surface ( 134 ) and the base surface ( 132 ) of the cutting insert ( 100 ) is configured to be apart from the first pocket part inclined surface ( 364 ) and base surface ( 362 ) of the pocket part ( 300 ), respectively, when the cutting insert ( 100 ) is mounted onto the pocket part ( 300 ). Thus, a contact area of the cutting insert ( 100 ) and the pocket part ( 300 ) is minimized to the side surface and the second inclined surface. Thus, the cutting insert ( 100 ) and the pocket part ( 300 ) can be manufactured more easily since the second inclined surface ( 136 ) of the cutting insert ( 100 ) is deformed elastically when the cutting insert ( 100 ) is pressed to the pocket part ( 300 ) by the screw such that it contacts the second pocket part inclined surface ( 366 ) of the pocket part ( 300 ) on the surface.
However, it is preferable that the lower surface ( 130 ) of the cutting insert ( 100 ) is polished to improve the surface roughness thereof. Particularly, it is preferable that only the second inclined surface ( 136 ) is polished if only the second inclined surface ( 136 ) of the lower surface ( 130 ) of the cutting insert ( 100 ) contacts the bottom surface ( 360 ) of the pocket part ( 300 ). Such treatment allows entire area of the second inclined surface ( 136 ) of the cutting insert ( 100 ) to contact the pocket part ( 300 ) on the surface uniformly so that a stress concentration on a partial area of the second inclined surface ( 136 ) of the cutting insert ( 100 ) can be prevented and the likelihood of causing damage of the cutting insert ( 100 ) can be alleviated while the cutting insert ( 100 ) can be mounted onto the pocket part ( 300 ) stably.
Further, in this embodiment, the first inclined surface ( 134 ) and the second inclined surface ( 136 ) of the cutting insert ( 100 ) has a rotation-symmetry of 180 degrees with respect to the through-hole ( 150 ) passing through a center of the upper surface ( 110 ) and the lower surface ( 130 ) of the cutting insert ( 100 ). Thus, the cutting insert ( 100 ) can be relocated on the pocket part ( 300 ) by 180 degrees rotation.
Moreover, in this embodiment, chamfered recesses ( 380 , 390 ) are formed at a corner portion where the side surfaces ( 320 ) of the pocket part ( 300 ) meet each other and at other corner portions where the side surfaces ( 320 ) meet the bottom surface ( 360 ). Although a protrusion according to the manufacturing problem is formed on a meeting portion of the side surfaces ( 120 ) of the cutting insert ( 100 ) or on meeting portions of the side surfaces ( 120 ) and the lower surface ( 130 ) when the cutting insert ( 100 ) is mounted onto the pocket part ( 300 ), interference of the protrusion to the side surface ( 320 ) or to the bottom surface ( 360 ) of the pocket part ( 300 ) is prevented so that the side surface ( 120 ) and the lower surface ( 130 ) of the cutting insert ( 100 ) can closely and stably contact the side surface ( 320 ) and the bottom surface ( 360 ) of the pocket part ( 300 ).
While the present invention has been described by way of embodiments thereof, the present invention may be embodied in various manners. However, these modifications will fall within the scope of the present invention.
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A cutting tool has a main body provided with a pocket part and a cutting insert. The pocket part includes at least one side wall and bottom surface which includes a pocket part base surface, a first pocket part inclined surface connected to an inner end of the base surface on an inside of the main body, and a second pocket part inclined surface connected to an outer end of the base surface on an outside of the main body. The cutting insert has an upper surface, a lower surface and side surfaces connecting the upper surface and the lower surface. The lower surface includes an insert base surface, first and second inclined surfaces inclined upwardly from first and second sides of the base surface, respectively. The cutting insert is seated in the pocket part such that the second inclined surface abuts the second pocket part inclined surface.
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BACKGROUND OF THE INVENTION
This invention relates generally to drill booms and more particularly to a drill boom arrangement for positioning an elongated rock drilling apparatus to different drilling positions with respect to a boom support wherein the drill boom is pivotally connected to the boom support, a boom head carrying the elongated rock drilling apparatus is pivotally connected to the drill boom, and the rock drilling apparatus is rotatable about a geometrical polar axis which is parallel with the longitudinal direction of the rock drilling apparatus.
During drilling, a turning moment arises about the polar axis. In previously known drill booms of this type the turning moment is transferred to the drill boom through the turning device which rotates the rock drilling apparatus about the polar axis. The turning moment can be considerable, particularly in drill boom arrangements where the rock drilling apparatus is pivotable to a position which is substantially perpendicular to the polar axis.
It is an object of the invention to provide a drill boom of the above type in which the turning device does not need to be dimensioned to be able to transfer the whole turning moment. This means that the turning device can be smaller and less expensive. Another object of the invention is to provide a drill boom in which the turning moment is divided into two components; one component which is transferred to the drill boom through the turning device and one component which is transferred directly to the drill boom.
The above and other purposes of the invention will become obvious from the following description and from the accompanying drawings in which one embodiment of the invention is illustrated by way of example. It should be understood that this embodiment is only illustrative of the invention and that various modifications thereof may be made within the scope of the claims following hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a side view of a drill boom in which the invention is applied.
FIG. 2 is a top view of the drill boom in FIG. 1.
FIG. 3 shows partly in section a coupling means according to the invention.
FIG. 3a shows a portion of the coupling means on an enlarged scale.
FIG. 4 shows a hydraulic circuit for controlling the turning device and the coupling means.
DETAILED DESCRIPTION
In FIGS. 1, 2 a drill boom 10 is pivotally supported on a horizontal cross shaft 11 and a vertical cross shaft 12 which are carried by a boom support or bracket 13. The horizontal cross shaft 11 is journalled in a link 14 which is swingable together with the drill boom 10 about the vertical cross shaft 12. The boom support 13 is carried by an element 15 which forms part of a drill wagon or rig, not shown, on which several drill booms 10 can be mounted in a group.
The drill boom is swingable about the cross shafts 11, 12 by means of hydraulic lift and swing cylinders 16, 17. The cylinder 17 is pivotable about a horizontal cross shaft 18 and a vertical cross shaft 19 which are carried by the boom support 13. The horizontal cross shaft 18 is journalled in a link 20 which is swingable together with the cylinder 17 about the vertical cross shaft 19. The end of the piston rod of the cylinder 17 is pivotally connected to the drill boom 10 by means of a joint 21 that takes up vertical movement and some horizontal movement. The cylinder 16 is connected to the boom support 13 and the drill boom 10 in the same manner as the cylinder 17. The cross shafts associated with the cylinder 16 are designated with 18 1 , 19 1 , 21 1 . The cylinders 16, 17 are of equal size and have the same mounting geometry relative to the boom support 13 and the drill boom 10.
Due to the fact that the boom support 13 carries the cylinder 17 for swinging about the vertical shaft 19 which is laterally spaced from the vertical swinging plane of the drill boom 10 a variation in length of solely the cylinder 17 will cause the drill boom 10 to swing about both the vertical shaft 12 and the horizontal shaft 11.
An extension or contraction of the cylinders 16, 17 of equal amount causes the drill boom 10 to swing only about the horizontal cross shaft 11. An extension of the cylinder 17 and a contraction of the cylinder 16 of equal amount or vice versa causes the drill boom 10 to swing about only the vertical cross shaft 12. By differently varying the lengths of the cylinders 16, 17 the drill boom 10 will simultaneously swing about both cross shafts 11, 12.
At its distal end the drill boom 10 carries a guide housing 22 in which a boom extension member 23 is guided axially slidably but non-rotatably. The boom extension member 23 is longitudinally adjustable by means of a hydraulic cylinder which is mounted inside the drill boom in a conventional manner. The guide housing 22 and the boom extension member 23 are described in detail in U.S. Pat. No. 3,923,276. The joint 21 is located at a predetermined distance from the cross shaft 12. This distance, thus, is maintained constant during swinging of the drill boom 10.
The boom extension member 23 carries a boom head 24. The boom head 24 is pivotally supported by the boom extension member on a horizontal shaft 25 and a vertical shaft 26. The horizontal shaft 25 is journalled in a link 27 which is swingable together with the boom extension member about the vertical shaft 26.
The boom head 24 is swingable about the cross shafts 25, 26 by means of hydraulic tilt and swing cylinders 28, 29. The end of the piston rod of the cylinder 29 is swingable about a horizontal cross shaft 30 and a vertical cross shaft 31 which are carried by the boom head 24. The horizontal cross shaft 30 is journalled in a link 32 which is swingable together with the cylinder 29 about the vertical cross shaft 31. The cylinder 29 is pivotally connected to the boom extension member 23 by means of a joint 33, that takes up vertical movement and some horizontal movement. The cylinder 28 is connected to the boom head 24 and the boom extension member 23 in the same manner as the cylinder 29. The cross shafts associated with the cylinder 28 are designated with 30 1 , 31 1 , 33 1 . The cylinders 28, 29 are of equal size and have the same mounting geometry relative to the boom head 24 and the boom extension member 23.
Due to the fact that the vertical swinging axis of the cylinder 29 is laterally spaced from the vertical swinging plane of the boom head 24 a variation in length of solely the cylinder 29 will cause the boom head 24 to swing about both the vertical shaft 26 and the horizontal shaft 25.
An extension or contraction of the cylinders 28, 29 of equal amount causes the boom head 24 to swing only about the horizontal cross shaft 25. An extension of the cylinder 29 and a contraction of the cylinder 28 of equal amount or vice versa causes the boom head 24 to swing only about the vertical cross shaft 26. By differently varying the lengths of the cylinders 28, 29 the boom head 24 will simultaneously swing about both cross shafts 25, 26.
The boom head 24 carries a turning device 34 which can be of the type disclosed in U.S. Pat. No. 3,563,321 incorporated by means of reference herein. Since the construction of the turning device is not essential to the invention it is not described in detail.
A feed beam holder 35 is pivotally journalled in a casing 37 by means of a cross shaft 36. The casing 37 is coupled to the propeller shaft of the turning device 34. The feed beam holder 35 carries an elongated rock drilling apparatus which includes a feed beam 40 which supports a rock drill 41. The feed beam includes hydraulic power means for displacing the drill along the feed beam in a conventional manner. The rock drill 41 rotates a drill steel 42 and delivers impacts on the drill steel. The drill steel 42 is guided by means of drill steel centralizers 43, 44. A hydraulic feed beam extension cylinder 38 for axially displacing the feed beam 40 is fixed to the feed beam holder 35 and it is also fixed to a bracket 39 which in its turn is fixed in the feed beam 40. The feed beam 40 is slidably supported in the longitudinal direction thereof on the feed holder 35 by means of guides fixed thereon. By extension or contraction of the feed beam extension cylinder 38 the feed beam 40 can be adjusted longitudinally with respect to the drill boom 10.
In order to obtain a hydraulically bound parallel displacement of the feed beam 40 during swinging of the drill boom 10 the cylinder 16 is connected to the cylinder 29 and the cylinder 17 is connected to the cylinder 28. This hydraulic parallel displacement arrangement is described in detail in Swedish Pat. No. 7804051-6. This patent teaches that the requirements which must be met in order to obtain an exact parallel displacement of the feed beam 40 during swinging of the drill boom 10 are that a triangle having its corners on the horizontal swinging axes 11, 18, 21 is similar to a triangle having its corners on the horizontal swinging axes respectively 25, 30 1 , 33 1 and that a triangle having its corners on the vertical swinging axes 12, 19, 21 is similar to a triangle having its corners on the vertical axes 26, 31 1 , 33 1 .
The turning device 34 is fixedly connected to the boom head 24 by means of bolts 47. By actuating the turning device 34 the feed beam 40 can be rotated 360° about an axis 45. A sleeve member 49 is fixedly connected to the casing 37 perpendicular thereto. The sleeve member 49 is journalled on the housing of the turning device 34 by means of bearings 50, 51.
According to the invention the sleeve member 49 and thus also the feed beam 40 can be locked relative to the boom head 24 against rotation about the axis 45 by means of a coupling generally denoted by 52. The coupling 52 is mounted on the turning device 34 concentrically therewith. The coupling 52 is of a friction clutch type known per se and comprises friction discs 53-56 which are non-rotatably connected to the boom head 24 and friction discs 57-61 which are nonrotatably connected to the sleeve member 49. An actuating means comprising peripherally spaced pistons 62 is adapted to apply a pressure force on the friction discs 53-61 by means of springs 63, e.g. Belleville springs. The spring force is of sufficient magnitude to lock the feed beam 40 against rotation about the axis 45. The pistons 62 are mounted in the sleeve member 49. Upon actuation of the turning device 34 by means of a control valve 64, hydraulic fluid is supplied through a conduit 65 to act upon the surface of the piston 62 which is opposite to the springs 63. The coupling 52 is thus released. Due to a shuttle valve 66 the coupling 52 is released independently of the direction of rotation of the turning device 34.
By means of a cylinder 46 the feed beam 40 can be swung about the cross shaft 36 substantially 90° to a position which is at right angle to the axis 45. During drilling with the feed beam in this position, the turning moment which arises and has to be transferred to the boom head 24 and the drill boom 10 is considerable. Because of the coupling means 52 this turning moment can wholly or preferably partly be transferred directly to the boom head 24. This means that the turning device 34 has to be dimensioned to be able to actively rotate the feed beam about the polar axis 45. It need not be dimensioned to withstand the moments that will occur during drilling.
According to the invention the drill boom is also provided with a second coupling of a friction clutch type known per se, generally denoted by 67. This slip-coupling 67 is adapted to lock the feed beam 40 relative to the propeller shaft 48 of the turning device 34. The coupling means 67 comprises a sleeve 68 provided with an inner recess which is fluid-filled. The fluid pressure and thus the maximum transferable moment between the shaft 48 and the feed beam 40 can be adjusted by means of an axially movable cover 69 so that the turning device 34 cannot be overloaded. The turning device 34 is preferably self-braking by means of a so called hydraulic lock that comprises two pilot-operated check valves 70, 71 in the two supply lines of the turning device.
The two couplings 52, 67 are connected between the feed beam 40 and the boom head 24 in parallel with each other. This means that the total lock moment which prevents rotation of the feed beam 40 about the axis 45 is the sum of the lock moments of the couplings 52, 67. Preferably, the magnitudes of the two lock moments are in the same order. Due to the fact that the couplings 52, 67 are of friction clutch type, the transferred moment is automatically distributed on the two coupling means 52, 67.
The coupling means 52, 67 are preferably dimensioned starting from the deformation moment of the turning device 34. By means of the cover 69 the coupling means 67 is set to a transferable moment which is below this deformation moment to a suitable certainty. The coupling means 52, then, has to be dimensioned to be able to transfer the difference between the allowed overall lock moment and the moment which is transferred by the coupling means 67. The deformation moment of the turning device 34 is usually more than twice the maximum active torque of the turning device.
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In a drill boom arrangement, a feed beam for a rock drill is turnable by means of a hydraulic turning device (34) about an axis (45) that is normally parallel with the axis of drilling during drifting. When not actuated, the turning device (34) is at least partially relieved of torque by means of a friction coupling (52) which is coupled in parallel with the turning device and is normally engaged. The coupling is automatically released when the turning device is actuated. A slip-coupling (67) is coupled in parallel with the first coupling (52) and in series with the turning device in order to avoid overloading of the turning device which is hydraulically self-braking.
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REFERENCE TO RELATED PATENTS AND PATENT APPLICATIONS
This application is a continuation of application Ser. No. 86,018, filed Oct. 17, 1979, and now abandoned.
My previously issued U.S. Pat. Nos. 4,123,861; 4,117,611; 4,098,013; 4,037,337; and my copending patent application Ser. No. 086,017 filed Oct. 17, 1979, now U.S. Pat. No. 4,321,762; and the art of record cited therein.
BACKGROUND OF THE INVENTION
The backhoe-type digging machine excavates material from the earth in an efficient and rapid manner. The backhoe machines are available in various different sizes and sometimes cost more than a quarter million dollars. Hence, the hourly cost of operating the large backhoe bucket is astronomical; but on the other hand, the cost is very little compared with the results, and especially the results when contrasted with other methods of excavating earth.
The backhoe bucket design directly governs the efficiency of operation of the entire backhoe machine. The design of the digging teeth is directly related to the overall efficiency of a particular bucket. The condition of the digging teeth can influence the digging efficiency more than 50 percent, depending upon the type of formation being excavated. In some instances, as the digging teeth progressively wear, the efficiency can drop from 300 feet of ditch per day, down to less than 100 feet of ditch per day. Accordingly, it is desirable that the backhoe bucket be provided with a bucket of efficient design, having sharp digging teeth thereon which likewise are of optimum design respective to the bucket and to the formation being excavated.
Digging teeth which are low in cost and which may be maintained in good cutting condition is the subject of the present invention.
SUMMARY
This invention comprehends a combination backhoe bucket, tooth-receiving shanks, and digging teeth therefor. The invention further comprehends a combination shank and digging tooth therefor.
The tooth-receiving shank of the present invention comprises an elongated main body having a forward and rear portion aligned respective to a bucket so that a tooth mounted within a tooth-receiving pocket thereof is disposed forwardly of the bucket in aligned relationship respective to the direction of travel of the bucket. The tooth has a main body which is a polygon in cross-section. The polygon preferably is a quadrilateral, and more specifically is square in cross-sectional area. The opposed ends of the teeth are provided with identical cutting edges by the formation of parallel oblique faces arranged parallel to one another and defining the extremities of the tooth.
The oblique face preferably is a plane in the form of a diamond, with each corner of the diamond being one corner of the quadrilateral or square.
The configuration of the pocket is complementary to the configuration of either marginal end of a tooth so that the cutting face, cutting edge, and side walls of the tooth are received in close tolerance relationship with complementary arranged wall surfaces of the pocket.
The foregoing description of a pocket and tooth enables the digging teeth to be reversed within a pocket of a shank, thereby providing each of the teeth with dual cutting edges, and enabling any one of the teeth to be interchanged for another, as well as being reversed as may be required as the cutting edge is worn.
This remarkable configuration of a digging tooth further enables the cutting edges thereof to be resurfaced or dressed in the field so that the digging bucket is essentially provided with an inexhaustible supply of sharp digging teeth.
The teeth of this invention are fabricated from an elongated piece of metal stock of satisfactory alloy, which has been normalized and sawed at spaced intervals, with each of the saw lines being arranged parallel to one another and defining the face of the teeth. The teeth are subsequently heat treated to achieve optimum hardness.
Accordingly, a primary object of the present invention is the provision of a backhoe bucket, shank, and tooth combination which enables any one tooth to be exchanged for any other tooth, as well as enabling each of the teeth to be reversed within a pocket in order to present a new cutting edge forwardly of the bucket.
Another object of the invention is to provide a tooth and shank combination, wherein the tooth has cutting edges formed on opposed marginal ends of the cutting teeth, and with the shank having a pocket made complementary respective to either marginal end of the tooth.
A further object of this invention is to disclose and provide a tooth and pocket combination in which the digging tooth is provided with a cutting edge at each extremity thereof so that either cutting edge can be utilized by reversing the tooth within the pocket.
A still further object of this invention is to provide a tooth and shank combination which enables digging loads encountered by the cutting edge of the tooth to be transferred into the shank and then into the bucket in an improved and unusual manner.
Another and still further object is to provide a tooth and shank combination which enables the digging tooth to be reversed within a pocket of the shank to present a new cutting edge, and which furthermore enables the cutting edge of the tooth to be field dressed in an easy and efficient manner.
These and various other objects and advantages of the invention will become readily apparent to those skilled in the art upon reading the following detailed description and claims and by referring to the accompanying drawings.
The above objects are attained in accordance with the present invention by the provision of apparatus fabricated in a manner substantially as described in the above abstract and summary.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a broken, side elevational view of a combination backhoe bucket, shank, and tooth made in accordance with the present invention.
FIG. 2 is an enlarged, perspective view of the digging bucket seen in FIG. 1;
FIG. 3 is a reduced, broken, top view of the apparatus disclosed in FIG. 2;
FIG. 4 is a reduced, front view of the apparatus disclosed in FIG. 2;
FIG. 5 is an enlarged, broken, top plan view of the apparatus disclosed in FIG. 4;
FIGS. 6, 7, and 8, respectively, are top and side elevational views of the digging teeth disclosed in the foregoing figures;
FIGS. 9, 10, and 11, respectively, are front elevational views of the combination disclosed in FIGS. 6, 7, and 8, respectively;
FIG. 12 is a side elevational view of the apparatus disclosed in FIG. 8;
FIG. 13 is a cross-sectional view of part of the apparatus disclosed in FIG. 12;
FIG. 14 discloses the opposite side of part of the apparatus disclosed in FIG. 12;
FIG. 15 is a cross-sectional view taken along line 15--15 of FIG. 12;
FIG. 16 is a rear view of the apparatus disclosed in FIG. 12;
FIG. 17 diagrammatically illustrates a flow sheet of the manufacture of part of the apparatus disclosed in the foregoing figures; and,
FIG. 18 is a schematical, cross-sectional view of a ditch which has been dug using the apparatus disclosed in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 discloses a backhoe bucket 10, preferably made in accordance with my previous U.S. Pat. Nos. 4,037,337 and 4,123,861. The bucket includes a plurality of shanks and teeth, generally indicated by the numeral 12, positioned at the forward end of the bucket. The bucket is attached to the dipper stick 14 of a backhoe (not shown).
As best seen in FIG. 2, together with other figures of the drawings, the bucket includes a lip 16 having a front edge 18. A plurality of teeth-receiving shanks 20 each has a rear marginal edge portion affixed to the forward marginal edge portion of the lip. A tooth 22 has a rear marginal length which is received within a pocket formed within the forward marginal edge portion of each of the shanks. For purposes of illustration, some of the shanks in FIG. 2 have the teeth removed therefrom.
In FIGS. 2-5, it will be noted that the bucket lip is in the form of a "V", with one side of the V having a plurality of teeth and shanks 24 attached thereto, the other side of the V-shaped lip has a plurality of teeth and shanks 26 affixed thereto, with there being a central tooth and shank at 28 connected along the apex 30 of the V. The apex also forms the keel or central portion of the bucket. The keel extends longitudinally of the bucket, while the lip extends laterally of the bucket. The shanks at 24 are mirror images of the shanks at 26, and the shank at 28 is made more or less symmetrical. Therefore, the shanks at 24 and 26 are asymmetrical.
One side 32 of the V-shaped bucket bottom is connected to the other side 34 of the V-shaped bottom, and the entire bottom is connected to opposed bucket side walls 36 and 38.
FIGS. 6-11 illustrate the details of the teeth and shanks seen at 24, 26, and 28 in the previous figures of the drawings. As particularly seen in FIG. 6, the shank 24 has a main body 40 which terminates forwardly at shoulder 42. The rear marginal portion of the shank is in the form of a lower tang 44 having a rear marginal end spaced from upper tang 46, thereby leaving a lip-receiving opening or slot 48 between the upper and lower tangs.
The shank has a trailing end 50 which is also the free terminal end of the lower shank. A lightening hole 52 is formed in the upper face of the lower tang to conserve material and weight.
As seen in FIG. 7, the main body of each of the shanks is provided with sloped walls 54 and 56 which are joined at apex 58. A pin hole 60 extends through the shank and engages a tooth which may be contained therewithin so that the tooth is removably mated within the pocket of the shank. The entrance into the pocket is defined by the shoulder 42.
In FIGS. 12-16, in conjunction with FIGS. 6-11, the foward tip 64 defines one terminal end of the tooth, while an identical tip 66 forms the opposite terminal end of the tooth. The tip 64 also defines the beginning of a face 68, and the face 68 forms the forward cutting edges of the tooth. The main body of the tooth includes side walls 74, 75, 76, 77, which terminate forwardly in the before mentioned edge portions and which terminate rearwardly in identical edge portions. The face 68 is parallel to the face 69.
The pocket 62 includes a roof 78, a floor 79, side walls 80, and a rear wall 82. The tip 66 of the tooth is received at apex 84 of the rearwardly converging walls.
Accordingly, the pocket 62 is made complementary respective to a marginal end of the tooth, with the side walls of the tooth being received in close tolerance relationship respective to the side walls of the pocket, and with the face of the tooth being received in abutting relationship respective to the rear wall 84 of the pocket, and with the tip 66 of the tooth being received within the similarly contoured or complementary shaped apex 84.
In FIG. 17, there is disclosed an elongated, longitudinally extending length of suitable alloy steel 95 which has been normalized so that the steel is relatively soft and can be easily cut. The long, rectangular body of steel has been milled at spaced locations 60' to provide a groove across one entire face of the tooth side wall. The groove 60' registers with the pin hole 60 so that a rolled pin or the like can be driven through the pin hole 60 and groove 60', thereby releasably affixing the tooth within the pocket of a shank.
The metal stock 95 is sawed along parallel saw lines 85 to provide a plurality of teeth 22, 22', 22", with each of the teeth being identical, and with the saw line defining the opposed cutting faces 68, 69 of the teeth.
After the metal stock 95 has been sawed into individual teeth, the individual teeth are heat treated at 96, thereby providing a heat-treated tooth 22 of suitable alloy which has been brought to optimum hardness, and which can be used in conjunction with a shank and bucket in accordance with the present invention.
In FIG. 18, there is disclosed a ditch 86 which has been dug with the bucket of FIG. 2. It will be noted that the teeth 22 in FIG. 2 are arranged at 24 and form the ledges 88 of FIG. 18; and that the tooth 22 located at 28 in FIG. 2 has formed the bottommost ledge 90, while the teeth 22 located at 26 in FIG. 2 have dug ledges 92 of FIG. 18. The cutting face of the teeth at 24 is aligned such that the face slopes upwardly towards the top of the bucket and inwardly towards the central tooth 28. The teeth at 26 are located opposite to the teeth at 24 so that the face of the teeth 26 also slopes upwardly towards the top of the bucket and inwardly towards the central tooth 28. This arrangement of the cutting faces of the teeth causes excavated material to flow into the bucket in a superior manner.
It will be noted that the central tooth 28 is located inwardly of the other teeth 24 and 26, with adjacent teeth being located forwardly and above the tooth 28, in accordance with my previously issued U.S. Pat. No. 4,037,337.
All of the teeth at 24, 26, and 28 are identical; and therefore, any one tooth can be substituted for any other tooth. Moreover, any tooth can be removed from a pocket and reinstalled with the previous digging end being inserted into the pocket in the manner of FIG. 12. This presents a new cutting edge, thereby providing each of the teeth with dual cutting surfaces which may be selectively employed whenever needed by reversing any one tooth within its socket.
Looking again now to FIGS. 2 and 18, it will be noted that the central tooth 28 digs a groove 90 having two side walls and a bottom, while the remaining teeth dig only a side wall and bottom, as noted at 88 and 92. The outermost teeth dig in advance of the innermost teeth and therefore wear at a faster rate. Accordingly, it is sometimes advantageous to be able to interchange some of the intermediate teeth for the outermost and innermost teeth.
The teeth of the present invention are low in cost; and therefore, an ample supply of teeth can be maintained available for use. This enables one set of teeth to be dressed while another set of teeth is being used by the backhoe bucket. As the teeth become dull, they are easily and quickly reversed within their pockets, and when both cutting edges have been dull, the teeth may be field dressed, thereby presenting a new cutting edge on the old teeth by the mere employment of a common bench grinder.
As seen illustrated in the various figures of the drawings, the main body of the tooth is polygonic in cross-section. The polygon preferably is a quadrilateral which has been truncated to form two oblique faces spaced apart and placed in parallel relationship respective to one another, with each of the faces being defined by a plurality of cutting edges. More specifically, the quadrilater is a truncated, elongated, solid length of steel or steel alloy having the oblique face arranged in a plane which lies 36° respective to the bottom wall of the tooth, and also arranged at an angle of 36° respective to a side wall thereof, so that the face slants upwardly back towards the bucket and inwardly towards the center of the bucket.
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A combination of digging teeth, mounting shank, and backhoe bucket. The shank of each tooth has a rear part by which it can be permanently affixed to the bucket lip. The forward part of the shank has a pocket formed therewithin of a particular configuration which receives a digging tooth in close tolerance relationship therewithin such that a forward marginal part of the tooth extends forwardly from the bucket lip and engages the earth. Each opposed marginal end of each of the teeth has identical cutting edges formed thereon so that a tooth can be reversed as well as being substituted one for the other. The teeth are easily field dressed so as to restore a sharp cutting edge thereon.
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Related application Ser. No. 12/097,702, filed Dec. 18, 2006, currently pending, is directed to a light weight combination carrier unit and head support apparatus for use in confined spaces.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a 35 USC 371 application of PCT/GB 2005/002429 filed on Jun. 20, 2005.
BACKGROUND OF THE INVENTION
The present invention relates to a head support and in particular to a light weight head support for use in confined spaces.
Due to increased volumes of traffic on the road and rail infrastructures and increased volumes of national and International airline flights, a greater number of passengers spend an increasing number of hours travelling which generally involves sitting in confined spaces. These spaces are particularly uncomfortable if a passenger is required to rest in an upright sitting position for prolonged periods of time for example on a long haul flight in an economy class aeroplane seat. Passengers encounter problems with trying to sleep under these conditions and one problem occurs as a direct result of the weight of the passengers' heads. When a person starts to slip into a light sleep, the muscles of the neck relax and the head drops suddenly causing a small shock to the body of the passenger as a result of the jerking motion and the passengers' tight sleep is broken. This cycle is repeated generally until the passenger finds a position where the weight of the head has at least partial support avoiding the jerking action of the head. The problem with this type of resting position is that the passenger often wakens up with a strain in their neck muscles.
OBJECT AND SUMMARY OF THE INVENTION
It is an object of the present invention to obviate or mitigate the above outlined problem.
Accordingly, the present invention provides a head support having a body with a recess defined along a recess edge of the body for receiving a person's lower jaw, a torso engaging edge of the body opposite the recess edge being formed for engaging a portion of the person's body when the person is sitting in a substantially upright position preventing the recess from falling away from the lower jaw area of the person.
In general, the person is a passenger but the invention is not limited to use by passengers. The invention is also suitable for use by people such as medical patients with back or neck or other injuries which requires the person to have their head supported upright. The invention is also suitable for people with nocturnal breathing difficulties such as asthma which often requires them to sit in an upright position to avoid breathing problems while sleeping.
Advantageously, the weight of the person's head is transmitted through the head support back to their own body with the head support acting as a strut.
Ideally, the head support has a short body so that the torso engaging edge of the body rests against the upper chest area of a person in use.
Preferably, the head support has an elongated body so that the torso engaging edge of the body rests against the stomach region of a person in use.
Advantageously, the head support with the elongated body has a greater surface area resting against the person's body which generates additional friction further preventing the recess falling away from the person's lower jaw area.
Ideally, a recess is provided in two opposite edges of the body.
Beneficially, the head support can be used upside down.
Preferably, each edge of the body has a recess.
Ideally, the body has an external surface resting against a person's chest area in use and a distal surface distal from a person's chest area in use.
Preferably, means for releasably securing a passenger's arms onto the distal surface of the body are provided.
Ideally, the securing means comprises a cruciform element with four arms, the four free ends of the arms extending out of the main plane of the cruciform element in the same direction and being attached at or about four edges of the distal surface of the body in a spider-like configuration, the distal surface and the spider-like cruciform element defining an open chamber therebetween having four apertures for receiving the arms of the person.
Advantageously, this embodiment provides support for a person's arms during sleeping in a confined space and the person is encouraged to sleep in the natural foetal position.
Ideally, a stiffening member is disposed within the body of the head support.
Preferably, the head support is an inflatable body.
Ideally, the body of the head support is manufactured from foam.
Preferably, the foam is at least partially covered with a material having a high coefficient of friction.
Ideally, the head support is a combination of a foam insert coated with an outer skin.
Preferably, the recess has a hemi-conical surface expanding from the proximal surface to the distal surface with the hemi-conical surface having a longitudinal axis substantially orthogonal to the main plane of the body.
Ideally, the body has a protuberance extending rearward from the body at or about the same location of the body as the recess.
Preferably, the securing means comprises a cruciform element with four arms, the four free ends of the arms extending out of the main plane of the cruciform element in the same direction and being attached at or about four edges of the distal surface of the body in a spider-like configuration, the distal surface and the spider-like cruciform element defining an open chamber therebetween having four apertures for receiving the arms of a person.
Ideally, the securing means is at least one adjustable strap.
Preferably, the bottom portion of the body tapers to the torso engaging edge to provide a stake like effect to prevent the body sliding down a person's torso in use.
Ideally, the head support has a body comprising a head element, an elongate spinal element and a body engaging element.
Ideally, the elongate spinal element has a two-piece rigid board with preferably a hinge between the two-pieces of board to allow the spinal element to fold over onto itself.
Preferably, the two piece board is covered with foam strips front and back respectively with preferably the front strip of foam being split in alignment with the hinge.
Ideally, the body engaging element is mounted on the elongate spinal element distal from the head element and comprises a block of foam for engaging a person's stomach region to define the second point of connection on a person's body to allow the head support to act as a strut.
Preferably, a single strap is connected to the two piece board at both sides of the hinge and the single strap has two free ends carrying fastening members.
The present invention also provides a garment of clothing for a person's torso having a head support incorporated thereinto, the head support extending from the neck region to the stomach region of the garment of clothing, the head support having a body with a recess defined along a recess edge of the body for receiving a person's lower jaw, a torso engaging edge of the body opposite the recess edge being formed for engaging a portion of the person's torso when the person is sitting in a substantially upright position preventing the recess from falling away from the lower jaw area of the person in use.
Ideally, when the garment of clothing has a zipper centrally mounted thereon in alignment with the longitudinal axis of the wearer, the head support is split about a centre line extending along the longitudinal axis of the head support so that one half of the split head support is carried by the garment on one side of the zipper and the other half of the split head support is carried by the garment on the other side of the zipper.
BRIEF DESCRIPTION OF THE DRAWINGS
This invention will now be described with reference to the accompanying drawings which show, by way of example only, three embodiments of the head support in accordance with the invention, in the drawings:
FIG. 1 is a side elevational view of a first embodiment of a head support in use;
FIG. 2 is a front elevational view of the head support of FIG. 1 ;
FIG. 3 is a side view of the head support of FIGS. 1 and 2 ;
FIG. 4 is a top plan view of the head support of FIGS. 1 to 3 ;
FIG. 5 is a bottom plan view of the head support of FIGS. 1 to 4 ;
FIG. 6 is the same front elevational view as FIG. 2 showing internal support members;
FIG. 7 is a sectional view of FIG. 6 taken along A-A;
FIG. 8 is the same front elevational view as FIG. 6 showing an internal stiffening member;
FIG. 9 is a side elevational view of FIG. 8 ;
FIG. 10 is a top plan view of FIG. 8 and FIG. 9 ;
FIG. 11 is a bottom plan view of FIGS. 8 to 10 ;
FIG. 12 is a front elevational view of a second embodiment of a head support;
FIG. 13 is a side elevational view of the second embodiment of the head support of FIG. 12 ;
FIG. 14 is a front elevational view of a third embodiment of the head support;
FIG. 15 is a first side elevational view of the third embodiment of the head support; and
FIG. 16 is a second side elevational view of the third embodiment of the head support.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring initially to FIGS. 1 to 11 , there is shown a head support indicated generally by the reference numeral 1 . The head support 1 has a body 2 with a recess 3 (see FIGS. 2 , 4 , 6 , 7 , 8 and 9 ) along a recess edge 4 of the body 2 . The recess 3 is generally v-shaped for accommodating a person's lower jaw although any shape of recess 3 capable of performing the function of supporting the lower jaw is suitable for use with the head support 1 . The body 2 (see FIGS. 3 and 7 ) has a proximal planar surface 5 which rests against a person's chest region in use and a distal planar surface 6 which is distal from the person's body in use.
A spider-like cruciform element 11 has four arms 14 extending in the same direction out of the main plane of the cruciform element 11 and is mounted onto the distal planar surface 6 of the body 2 at the four outer ends 12 of the arms 14 . The spider-like cruciform element 11 and the distal planar surface 6 define a cavity 15 with four apertures 16 which allow a person to criss-cross their arms through diametrically opposed apertures 16 as shown in FIG. 1 .
A torso edge 21 of the body 2 opposite the recess 3 has an insert 22 for improving the strength of this edge 21 to mitigate against deformation.
FIG. 6 and FIG. 7 show blocks 25 which are disposed between the arms 14 of the cruciform element 11 and the distal surface 6 of the body 2 . These blocks 25 improve the overall structural integrity of the head support 1 .
FIGS. 8 to 11 show a stiffening board 26 . The stiffening board 26 prevents deformation of the head support I and is an optional feature.
Referring now to FIGS. 12 and 13 , there is shown a second embodiment of a head support indicated generally by the reference numeral 101 . The head support 101 has a body 102 with a recess 103 along a recess edge 104 of the body 102 . The recess 103 is semi-circular in shape although the recess 103 can be any shape provided it is capable of performing the function of accommodating a person's lower jaw in use. The body 102 has a proximal planar surface 105 which rests against a person's chest in use and distal planar surface 106 which is distal from the person's body in use. The recess 103 has a hemi-conical surface 108 expanding from the proximal planar surface 105 to the distal planar surface 106 with the recess 103 having a longitudinal axis substantially orthogonal to the main plane of the body 102 .
The body 102 has a protuberance 111 extending rearward from the proximal planar surface 105 at or about the same location of the body 102 as the recess 103 . The effect of the protuberance 111 is to propel the hemi-conical surface 108 of the recess 103 up and out from the person's neck to hold the person's head in the most upright position possible within the geometrical constraints imposed by the width of the body 102 and the width of the protuberance 111 . Otherwise, the weight of the person's head may compress the deformable recess portion negating the desired effect of the head support 101 . The body 102 of the head support 101 is a foam body in this embodiment. It will be appreciated that the body of the present invention may be an inflatable body formed of a substantially airtight inflatable outer skin with a high co-efficient of friction or a combination of a foam insert coated with an outer skin of plastic or some similar suitable material. The foam body 102 of FIGS. 12 and 13 has two pairs of openings 115 , 116 and two straps 117 , 118 . Strap 118 passes through the pair of openings 115 and the other strap 117 passes through the other pair of openings 116 . The straps 117 , 118 are open ended and have fastening members on their free ends 119 to allow a person to adjust the position of straps 117 , 118 depending on the size of their arms. The free ends 119 of the straps 117 , 118 pass out of the body 102 at the distal planar surface 106 with the straps 117 , 118 extending from a first free end 119 through the body 102 via a first opening of the pairs 115 , 116 , along the proximal planar surface 105 and back through the second opening of the pairs 115 , 116 to the distal planar surface 106 . The bottom edge 121 of the body 102 tapers to the torso engaging edge 125 to provide a stake like effect to prevent the body 102 sliding down a person's torso in use.
Referring to FIGS. 14 to 16 there is shown a third embodiment of head support indicated generally by the reference numeral 71 . The head support 71 has a body 72 comprising a head element 80 , an elongate spinal element 83 and a body engaging element 54 . The head element 80 has a recess 73 which has a hemi-conical surface 81 for receiving a person's lower jaw. The longitudinal axis of the recess 73 is substantially orthogonal to the main plane of the body 72 . A tapered protuberance 84 extends rearward from the head element 80 and performs the same function as the protuberance 111 of FIGS. 12 and 13 . The elongate spinal element 83 has a two-piece rigid board 87 with preferably a hinge 88 between the two-pieces of board 87 to allow the spinal element 83 to fold over onto itself for storage or in the event of a person's head lunging forward suddenly as could happen during take-off, landing, heavy turbulence or an accident. The two piece board 87 is covered with foam strips 91 , 92 front and back respectively with the front strip 91 of foam being split in alignment with the hinge 88 . The body engaging element 84 is mounted on the elongate spinal element 83 distal from the head element 80 and comprises a block of foam for engaging a person's stomach region to define the second point of connection on a person's body to allow the head support 71 to act as a strut. A single strap 95 is connected to the two piece board 87 at both sides of the hinge 88 and the single strap 95 has two free ends 96 , 97 carrying fastening members such as Velcro® patches. These fastening members allow the strap 95 to be adjusted to accommodate people with different sizes of arms.
It will also be appreciated that additional belts may be attached to the head support which can extend around the body of a person using the head support.
Variations and modifications can be made without departing from the scope of the invention defined in the appended claims.
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A head support having a body with a recess defined along a recess edge of the body to receive a person's lower jaw. A torso engaging edge of the body opposite the recess edge being formed to engage a portion of the person's torso when the person is sitting in a substantially upright position to prevent the recess from falling away from the person's lower jaw area.
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CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a non-provisional application claiming the benefit of prior U.S. Provisional Application No. 60/481,912, filed Jan. 16, 2004.
FIELD OF THE INVENTION
[0002] This invention relates generally to structural systems and a joint for joining structural elements together as a building material. More particularly, the joint is for trim moulding or stationary framework that is mitered on opposite ends to form a mortise or tenon.
BACKGROUND OF THE INVENTION
[0003] Many types of joints for structural elements exist. A simple butt joint is formed by nailing or screwing two ends together. This joint is formed by nailing or screwing the end of one piece of wood to the end of the other. While this is simple, fast and effective, the butt joint cannot be used on many types of end joints since it is not strong. A simple butt joint also leaves the heads of the fasteners exposed which is often undesirable.
[0004] Another type of joint is the end lap joint. This joint is made by removing substantially halfway through each piece of structural element. That is, chamfering the ends of structural elements, and securing them together. Typically, the ends are glued with an adhesive or fastened together with a fastener. This is a common type of joint used in picture frames. The problem with this type of joint is that it does not withstand shear forces very well, and any force on the structure will impart shear forces on the joint. Glued joints of this type are also weak due to the shear forces.
[0005] A rabbet joint has become a standard design for many applications that utilize extended tab and pocket cutout joinery. In a rabbet joint, the pocket cutouts are at the very edge of the panel, with the pocket sidewalls actually incorporated into the outer edge of the panel.
[0006] Rabbet joints are commonly found in simple box and case construction. A rabbet is typically an L-shaped groove cut across the edge or end of one structural element. Fitting the other piece into it makes the joint. The rabbet joint is usually fastened with glue and nails or screws. This type of joint permits joint location to occur at the edge of a panel, thus providing the benefit of a non-interfering edge profile. The disadvantage of the rabbet joint, is that the joint must be adhesive bonded to secure the panel connection, and the primary load path is through the relatively weak adhesive bondline at the rabbet joint.
[0007] The dado is used to provide a supporting ledge for a shelf. The dado is a groove cut across the grain. In the simple dado joint, the butt end of the piece or shelf fits into this groove. The problem with this joint is that, unless a face frame is added to the front of the case, it has an unattractive look. For better appearance, a stopped or blind dado is the very best. In this joint, a dado is cut partway across the first piece, and then a corner is notched out of the second piece so the two fit together.
[0008] An alternate to the joint mentioned is referred to as a mortise and tenon joint. To form this joint, a slot is placed in one structural element. The end of the other structural element is then notched out to correspondingly fit the slot in the first piece. One inserts the notched piece into the slotted piece of the structural element. An open mortise and tenon joint is made by cutting the slot or mortise only partway into the structural element. Then create a notched-out area on the other piece that correspondingly fits into the slotted area in the first piece.
[0009] The bonding process of a mortise and tenon joint may involve applying adhesive into the mortise pocket, however, since the pocket is fully enclosed in the mortise panel (not incorporated into the panel edge as in the rabbet joint), the primary load path is through the mortise panel itself and not the adhesive bondline. The disadvantage of the mortise and tenon joint is the existence of an edge margin of the mortise panel that extends from the mortise pocket to the actual edge of the panel. This interfering edge margin reduces the volume which can be achieved inside a defined envelope.
[0010] Typically, relatively large clearances must be designed into mortise and tenon joint interfaces so that costly interference conditions do not occur, preventing the tenon tabs from fitting into the mortise pockets, and resulting in the scrapping of parts or expensive rework. These large clearances between the mortise pocket sidewalls and the tenon tab surfaces, increase the need for elaborate and expensive tooling to accurately locate and secure the panels. While the panels are held in place, an adhesive, which is used to bond the joint, is allowed the necessary time to cure. A joint structure with inherent self-tooling features that could eliminate the need for expensive additional tooling is highly desirable.
SUMMARY OF THE INVENTION
[0011] This invention provides an improved mortise and tenon joint. The joint is a stopped or blind mortise and tenon joint where the tenon is hidden fully in the mortise. In the preferred embodiment of the present invention, a first and second trim moulding is constructed as a mortise and tenon. In the preferred embodiment, the tenon is perpendicular to the miter edge. The tenon preferably has a thickness of approximately ⅓ that of the moulding at the middle of the miter. The width is approximately ½ the width of the joint. The height is approximately equal to the mortise depth and preferably less approximately ¼ inch.
[0012] The tenon has a glue relief on the back side. In the preferred embodiment, the tenon is produced on the vertical side of the trim, but can be produced on the horizontal as well. The mortise can be produced on the vertical or horizontal as well. By consistently producing the mortise in one configuration and the tenon in the other, identifying the vertical and horizontal structural elements is easier. The mortise is designed to receive the tenon in a tight, close fit such that the friction between the mortise and tenon hold the structural elements together under the expected stress and forces. The depth of the mortise may vary depending on the materials, design preferences, strength desired as well as other factors. Preferably it is designed to come within ¼ inch of the outside surface of the finish moulding, and thus is unique to a particular size and style of moulding.
[0013] The purpose of the mortise and tenon on the miter of the vertical and horizontal joining of the structural elements is: (1) to maximize the surface area of contact in the joining; (2) to assure that the joining parts do not move independently of each other; and (3) to assure the precise alignment in the joining of the mitered edges to produce a quality joint by the end user at the time of application with minimal amount of skill and time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a plan view of a tenon of the present invention;
[0015] FIG. 2 is an elevational view of a tenon of the present invention;
[0016] FIG. 3 is a schematic view of an embodiment of the present invention;
[0017] FIG. 4 is a schematic view of the tenon and structural element; and
[0018] FIG. 5 is a schematic view of the mortise and structural element.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The present invention provides an improved mortise and tenon joint. In FIG. 1 , a side view schematic of the tenon is depicted. In this embodiment, the tenon 10 is generally oval or oblong with two opposing ends 22 , 24 and a center portion 26 . The ends 22 , 24 are shaped to extend in a slope upwards toward the center portion 26 as shown in FIG. 2 . The center portion 26 comprises opposing sides 28 , 30 that slope up towards, and meet at, a middle 28 . The tenon may be of other known shapes and is not limited to this preferred design.
[0020] The proper proportion between the overall length and height of the tendon compared to the overall size and shape of the structural element is generally known in the art. In the embodiment shown in FIG. 1 , the size is approximately 31.75 mm in length and 4.76 mm in width and, as shown in FIG. 2 , 12.7 mm in height. The size is generally determined by the structural elements being joined, which in this case are window or door mouldings. The constraints include but are not limited to the weight and shear forces acting on the joint as well as the amount of material available to form the mortise and tenon. These factors will help determine the dimensions (length, width, height) of the tenon.
[0021] FIG. 3 is a side plan view of the mortise 50 of the present invention. As is known in the art, the mortise is designed to generally correspond to the shape and size of the tenon, although they do not have to correspond exactly. In the example shown in FIG. 3 , the mortise is oval or oblong and slightly larger in dimensions than the tenon, the walls do not slope and the bottom is planar. The size is intended to accommodate the tenon in a tight and close fitting joint. The joint is held together by both frictional forces, and the weight and shear forces acting on the joint from outside. The joint may also be fixed by adhesives or fasteners.
[0022] FIG. 4 shows the position of the tenon on the mitered edge of a moulding. The miter shown is a typical 45 degree corner but the corner may be of any angle. The tenon 10 height dimension is perpendicular to the mitered edge when the miter is a 45 degree miter. When the miter is anything else but a 45 degree angle, the tenon should be at an angle such that it will fit the mortise to form the final angle desired of the joined structural elements. This provides that the angle compensates for the angle of the mitered edge to form a 90 degree angle, but a 90 degree angle is not always necessary for the present invention. It might be desired that the structural elements form an angle less than or greater than 90 degree s.
[0023] FIG. 5 shows the preferred mortise embodiment. The structural element, in this case a moulding, has a mitered edge at a substantially 45 degree angle. The mortise is also perpendicular to this edge such that it joins well with an opposing tenon.
[0024] The embodiments shown in the present figures are mouldings intended for doors or windows, however, the tendon design is not limited to that use and can be used for other structural elements. The materials from which the joint of the present invention may be made include wood, plastic, concrete, rubber and other known building materials. It is preferred that the tenon be integral with the structural element however this is not necessary. For example, a mortise may be filed with a dowel or tenon element making the mortise a tenon.
[0025] Accordingly, it should be readily appreciated that the mortise and tenon joint of the present invention has many practical applications. Additionally, although the preferred embodiments have been illustrated and described, it will be obvious to those skilled in the art that various modifications can be made without departing from the spirit and scope of this invention. Such modifications are to be considered as included in the following claims.
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The invention provides a joint and a method for forming a joint between two structural elements comprising a tenon on a mitered edge of a first structural element joined to an oppositely corresponding mortise on a mitered edge of a second structural element.
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1. FIELD OF THE INVENTION
[0001] The present invention relates to articles for dispensing powdered compositions, and methods of using such articles.
[0002] The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein, or any publication specifically or implicitly referenced herein, is prior art, or even particularly relevant, to the presently claimed invention.
2. BACKGROUND
[0003] Veterinarians, technicians, groomers and even some pet owners often find themselves applying styptic powder to bleeding toe nails after cutting the nails too short. “Cutting to the quick” is a common expression in the pet care profession, and refers to cutting into the blood supply of the affected nail. There are various products on the market to expedite the clotting of blood, including gel and silver nitrate sticks, although by far the most commonly used topical hemostatic agent for this purpose is a styptic powder available through various vendors, all with varying methods of application. While the most prominent and widely used method of stopping blood flow from a bleeding toe nail has been the use of a styptic powder, its application is crude at best, and is often performed by manual application of loose powder first placed on a person's finger tip and then applied directly to the animal's nail or, alternatively, by applying a cotton tip applicator loaded with styptic powder directly to the nail. In either of these approaches, the user often fumbles with the styptic powder while the animal struggles, with the result often being the spillage of the styptic powder, either because of user error or the bleeding animal knocking the powder from the user's hand. Either of such outcomes results in ineffective application and loss of product. In addition to being wasteful, conventional approaches are time consuming. Moreover, in conventional approaches the styptic powder is frequently overexposed to the atmosphere or to air and humidity, the result of which is caking of the powder.
[0004] While various applicators have been developed as attempts to improve delivery of styptic powders, the need still exists for a simple, inexpensive hand-held device that a user can employ to efficiently and effectively administer a hemostatic amount of a styptic powder (or other composition capable of stemming blood flow) to a bleeding toenail.
3. DEFINITIONS
[0005] Before describing the instant invention in detail, several terms used in the context of the present invention will be defined. In addition to these terms, others are defined elsewhere in the specification as necessary. Unless otherwise expressly defined herein, terms of art used in this specification will have their art-recognized meanings.
[0006] An “antihemorrhagic” or “hemostatic” compound or composition refers to a substance or composition that promotes hemostasis, i.e., stops bleeding. A “styptic” compound or composition refers to a class of antiseptic hemostatic substances or compositions that function by stimulating contraction of tissue, particularly blood vessels. An example of a commercially available styptic powder is KwicStop® (Arc Laboratories, Inc., Atlanta, Ga.: a hemostatic composition that includes ferric subsulfate, aluminum chloride, diatomite bentonite, copper sulfate, ammonium chloride, idophor, and benzocaine). Other topical hemostatic substances or compositions that can also be used in practicing the invention include coagulants, i.e., compounds and compositions that promote platelet aggregation, such as microfibrillar collagen and chitosan.
[0007] A “patentable” article of manufacture, device, machine, process, or composition of matter according to the invention means that the subject matter satisfies all statutory requirements for patentability at the time the analysis is performed. For example, with regard to novelty, non-obviousness, or the like, if later investigation reveals that one or more claims encompass one or more embodiments that would negate novelty, non-obviousness, etc., the claim(s), being limited by definition to “patentable” embodiments, specifically exclude the non-patentable embodiment(s). Also, the claims appended hereto are to be interpreted both to provide the broadest reasonable scope, as well as to preserve their validity. Furthermore, the claims are to be interpreted in a way that (1) preserves their validity and (2) provides the broadest reasonable interpretation under the circumstances, if one or more of the statutory requirements for patentability are amended or if the standards change for assessing whether a particular statutory requirement for patentability is satisfied from the time this application is filed or issues as a patent to a time the validity of one or more of the appended claims is questioned.
[0008] A “plurality” means more than one.
4. SUMMARY OF THE INVENTION
[0009] Thus, one object of the invention relates to articles adapted to deliver a powered composition, for example, a styptic powder. The powder dispensers of the invention house replaceable powder filled-cartridges that are easy to use. In some embodiments, such articles can be used for applying styptic powder to a bleeding animal's toenail. In other embodiments, they are used dispensing an approximate measure of different powdered compositions, for example, a cooking spice.
[0010] In general, the powder-dispensing articles of the invention include a housing that houses a cartridge that can move in relation to the housing, typically by depressing a plunger that protrudes from the housing. After use, the cartridge preferably returns to an idle position. In most embodiments, the housing is an elongated housing that has an open end opposite a sealed end and a housing access port disposed proximal to the sealed end so as to provide access to the interior of the housing. The cartridge is disposed inside of and in moveable relation to the housing, and comprises first and second sealed ends disposed opposite each other so as to define a reservoir configured to store a powdered composition. Cartridges also include a cartridge access port that provides access to the reservoir, particularly to powdered contents stored in the reservoir. Preferably, the first sealed end of a cartridge faces the sealed end of the housing in which the cartridge is placed, while the cartridge's second sealed end faces the open end of the housing. The plunger comprises a plunger element that has a flange disposed at one end and at the other end, an exposed surface configured for application of an actuation force by a user.
[0011] The flange has a cartridge-facing surface that engages the second sealed end of the cartridge and a retaining surface opposite the cartridge-facing surface. The plunger element extends through the open end of the housing and is retained in the housing by a plunger retainer disposed on the open end of the housing. The dispensing articles of the invention also preferably include a biasing member (e.g., a spring) disposed inside the housing and positioned to engage and return the cartridge to a resting or “idle” position after an actuation force applied by a user is reduced or removed. As will be appreciated, application of an actuation force by a user will causes the cartridge to move in relation to the housing and bring the cartridge and housing access ports into alignment, thereby allowing access to the reservoir
[0012] As those in will appreciate, a clear advantage afforded by the articles of the invention is that the replaceable cartridge within the housing is kept semi-airtight and spill resistant, and thereby minimizes waste of the powdered composition contained within the cartridge. Also, the cartridges preferably contain quantities of the desired composition to enable multiple independent uses of the device, thereby avoiding a requirement for manual filling for a given application. Moreover, because the powdered composition is stored safely within the cartridge, users can avoid contact with the cartridge contents. As opposed to the currently available styptic powder dispensers, spice dispensers, and other powdered composition dispensers, which are primarily storage containers for loose powdered compositions, the powdered compositions within a cartridge of an article according to the invention is less subject to spillage and atmospheric conditions.
[0013] The articles of the invention can also further include one or more other components, including any one or more of an alignment system that provides complementary structures between the housing and cartridge to promotes alignment between the housing access port and cartridge access port when a cartridge is moved into dispensing position, a stop disposed in the reservoir opposite the cartridge access port, and a powdered composition in the reservoir.
[0014] Another aspect of the invention concerns methods of dispensing a powdered composition from a cartridge in an article according to the invention. Typically, this is accomplished by a user applying an actuation force to the article's plunger to bring the housing access port and cartridge access port into alignment to allow at least a portion of the powdered contents within the cartridge to be dispensed.
[0015] These and other aspects and embodiments of the invention are discussed in greater detail in the sections that follow. The foregoing and other aspects of the invention will become more apparent from the following detailed description, accompanying drawings, and the claims. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. In addition, the materials, methods, and examples below are illustrative only and not intended to be limiting.
5. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] A brief summary of each of the figures is provided below.
[0017] FIG. 1 shows a representative embodiment of a device of the invention from a top perspective view.
[0018] FIG. 2 shows the device depicted in FIG. 1 in an exploded perspective view.
[0019] FIG. 3 shows an inner cartridge of a device according to the invention from a side elevational view.
[0020] FIG. 4 shows a representative embodiment of a device of the invention from an exploded perspective view.
[0021] FIG. 5 shows another representative embodiment of a device from an exploded perspective view.
[0022] FIG. 6 shows the inner cartridge in its entirety from a side elevational view.
[0023] In the drawings, the following reference numerals correspond to the indicated component, unless otherwise indicated.
[0000]
Drawings - Reference Numerals
22 Plunger Retainer
24 Plunger cover
26 Plunger
28 Cartridge
30 Square cut o-ring
31 Tongue
32 Saddle seal (bearing)
34 Cartridge access port
36 Cartridge bottom plug
38 Biasing Member
40 Outer housing tube
42 Stabilizing notch
44 Housing access port
46 Sliding sleeve
48 Housing bottom plug
50 Nail stop point
52 Pocket clip (optional)
54 Magnet (optional)
49 Saddle seal (bearing)
DETAILED DESCRIPTION
[0024] The following description describes several representative embodiments of certain preferred dispensing articles of the invention. These embodiments are non-limiting.
[0025] A first embodiment is illustrated in FIG. 1 . The powder dispenser includes an outer housing tube 40 , which in this embodiment is made of 0.75 in. anodized aluminum tubing or other workable materials such as cardboard, stainless steel, or polycarbonate plastic. The outer housing can be made in various lengths, with 4-7 in. being preferred, and a length of about 5.5 in. being particularly preferred. The housing 40 is topped with a replaceable 0.75 in. plunger retainer 22 that has a 0.5 in. hole bored out of the center. The plunger retainer 22 can be made of any suitable material, including vinyl, plastic, or threaded metal. The 0.5 in. plunger cover 24 is also made of vinyl or a polycarbonate plastic, and protrudes from the inner cartridge (not shown in FIG. 1 ) and conceals the plunger 26 (shown FIG. 2 ) made of acrylic, polycarbonate plastic, or other suitable materials. The housing 40 also includes a sliding sleeve 46 , which can made of vinyl or polycarbonate plastic. The bottom of the housing 40 , opposite the end from which the plunger protrudes (i.e., the top end of the housing 40 ), is sealed. In this embodiment, the bottom end of housing 40 is sealed, for example, with a bottom plug 48 , made of polycarbonate plastic. The bottom plug 48 may be permanently attached or be removable. In some embodiments, the bottom of the housing may be sealed, for example, by crimping the housing and eliminating the bottom plug 48 , while in still other embodiments, the bottom of the housing is left open.
[0026]
FIG. 2
[0027] Starting at the top down is a plunger retainer 22 that slides over the top of the plunger cover 24 and the plunger 26 finally resting on top of the outer housing tube 40 . The plunger 26 is concealed by the plunger cover 24 and both the plunger 26 and plunger cover 24 are attached to the top of the cartridge 28 . The cartridge 28 carries a square cut o-ring 30 that rests just below the tongue 31 . The lower portion of the cartridge is saddled with a saddle seal 32 , which is centered over the cartridge access port 34 .
[0028] The entire cartridge 28 is sealed on the bottom with a cartridge bottom plug 36 , which be made of polycarbonate plastic. A biasing member 38 is positioned inside of the outer housing tube 40 resting at the bottom on top of the inner housing bottom plug 48 .
[0029] A ⅞″ deep stabilizing notch 42 is milled from the top wall of the outer housing tube 40 . The stabilizing notch serves as a groove for the tongue 31 to slide in. The housing access port 44 is bored out about 1″ from the bottom of the outer housing tube 40 . The sliding sleeve 46 rides on the outer wall of the outer housing tube 40 and is placed atop of the housing access port 44 concealing it while in its resting position. The outer housing tube 40 is sealed on the bottom with the housing bottom plug 48 . An optional magnet 54 may be attached to the inner wall of the outer housing tube 40 .
[0030]
FIG. 3
[0031] The plunger cover 24 conceals the plunger 26 , which is bonded to the inner wall of the cartridge 28 sealing in a powdered composition. The square cut o-ring 30 wrapped around the cartridge 28 rests below the tongue 31 and the saddle seal 32 is positioned over the cartridge access port 34 within the cartridge 28 just below the cartridge access port 34 resting on the inner back wall of the cartridge 28 is a nail stop point 50 , which could be made of a composite of resins and glues or molded plastic or cork or metal, and the bottom of the cartridge 28 is sealed with the cartridge bottom plug 36 .
[0032] The outer wall of the cartridge carries a square cut o-ring 30 and the saddle seal 32 , which not only functions as a seal but also provides spacing between the cartridge 28 and the outer housing tube 40 in order to reduce any caking or sticking of the cartridge to the inside wall of the outer housing tube 40 and thereby ensure fluidity of movement of the cartridge inside the outer housing when a user presses down on the plunger assembly.
[0033]
FIG. 4
[0034] Shown at the top of the article is a plunger retainer 22 that slides over the top of the plunger cover 24 and the plunger 26 , finally resting on top of the outer housing tube 40 . The plunger 26 is concealed by the plunger cover 24 and both the plunger 26 and plunger cover 24 are attached to the top of the inside walls of the cartridge 28 which, for example, could be made of 0.5 inch outer diameter acrylic tubing, two separate half pieces of molded plastic bonded together, an extruded piece of aluminum tubing sized to fit and move within the housing, or any suitable tubing material (or combination of materials). The cartridge 28 carries an o-ring 30 . The lower portion of the cartridge is saddled with a saddle seal or bearing 32 , which is centered over the cartridge access port 34 . The entire cartridge 28 is sealed on the bottom with the cartridge bottom plug 36 , which be made of polycarbonate plastic (or any suitable material). A biasing member 38 is disposed inside of the outer housing tube 40 in order to engage the cartridge. In the embodiment shown, the open end of the housing is sealed with an inner housing bottom plug 48 , upon which the biasing member 38 rests.
[0035] Those in the art will appreciate that complementary mechanical features can be used to provide registration between the housing and cartridge.
[0036] The housing access port 44 is bored through the wall of the housing. In the embodiment shown, the housing access port is about 1″ from the bottom of the outer housing tube 40 . The sliding sleeve 46 rides on the outer wall of the outer housing tube 40 and is placed atop of the housing access port 44 , concealing it while in its resting position. The outer housing tube 40 is sealed on the bottom with the housing bottom plug 48 . An optional magnet 54 can be attached to the inner wall of the outer housing tube 40 .
[0037]
FIG. 5
[0038] This figure shows a device similar to that depicted in FIG. 4 . In the embodiment shown in this Figure, bearing 32 is replaced with bearing or saddle seal 49 , which has an opening or port therein. Bearing or saddle seal 49 is preferably is secured to cartridge 28 (as is also preferably the case for bearing 32 of the device shown in FIG. 4 ) in manner such that its opening or port aligns with the cartridge access port 34 of cartridge 28 .
[0039]
FIG. 6
[0040] The plunger cover 24 conceals the plunger 26 , which is bonded to the inner wall of the cartridge 28 sealing in a powdered composition. The square cut o-ring 30 wrapped around the cartridge 28 rests above the saddle seal 32 , which is positioned over the cartridge access port 34 . The bottom of the cartridge 28 is sealed with the cartridge bottom plug 36 .
[0041] The outer wall of the cartridge carries a square cut o-ring 30 or a Gore sealant in another embodiment. The saddle seal 32 not only functions as a seal but also acts as a spacer to provide a gap between the cartridge 28 and the inner surface of housing tube 40 in order to reduce any caking or sticking of the cartridge and providing fluidity of movement.
[0042] Operations
[0043] The manner of using a powder dispenser of the invention in its intended primary use as a styptic dispenser is as shown in FIG. 1 is straightforward. For example, a user, while cutting the toenails of a dog or other animal, inadvertently cuts into the blood supply of the nail, resulting in bleeding. The user then manually picks up the powder dispenser by the outer housing tube 40 and pushes down the sliding sleeve 46 , revealing the wall of the inner cartridge 28 . The user then proceeds to engage the top plunger 26 via the plunger cover 24 with his or her thumb, thus pushing down the inner cartridge 28 and bringing the cartridge access port 34 into alignment with the outer housing access port 44 , thereby exposing the styptic powder in the cartridge's reservoir. The user then presses the animal's bleeding nail into the nail stop stop ( 50 ), which stops the bleeding.
[0044] The user then pulls the article away from the animal's paw while releasing his or her thumb from the plunger cover 24 and plunger 26 , which returns the cartridge 28 to its starting position. In this way styptic powder can be directly delivered from the gravity fed cartridge 28 , and any contaminated or used powder is fused with the nail, leaving the cartridge stocked and ready for the next needed application.
[0045] In another embodiment, the user while cooking can deliver a “pinch” of, for example, spice stored in the cartridge's reservoir. To add the spice, the user simply picks up the powder dispenser by the outer housing tube 40 and pushes down the sliding sleeve 46 revealing the wall of the inner cartridge 28 . The user then proceeds to engage the top plunger 26 via the plunger cover 24 with his or her thumb thus pushing down the inner cartridge 28 and bringing the cartridge access port 34 into alignment with the outer housing access port 44 , thereby exposing the powdered spice composition, the desired amount of which the user can then dispense from the reservoir before releasing his or her thumb from the plunger cover 24 to return plunger 26 of the cartridge 28 to its starting position.
[0046] In yet another embodiment, the compression spring disposed within the housing rests behind the main outer housing tube in a separate adjoining tube so as to lower the housing access port. In another embodiment the housing tube includes an access window to allow a user to visualize the cartridge in order to monitor the amount of powdered contents remaining in the cartridge's reservoir.
[0047] In still another embodiment the outer housing tube has an attached magnet. In another embodiment powder is forced through a diaphragm so as to dispense an allotted amount of powder during a particular dispensing operation. Alternatively, differing amounts of powdered contents from the reservoir can be dispensed by varying the diameter of the cartridge and/or the cartridge access port size(s).
[0048] All of the articles and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the articles and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied without departing from the spirit and scope of the invention. All such variations and equivalents apparent to those skilled in the art, whether now existing or later developed, are deemed to be within the spirit and scope of the invention as defined by the appended claims.
[0049] The invention illustratively described herein suitably may be practiced in the absence of any element(s) not specifically disclosed herein. Thus, for example, in each instance herein any of the terms “comprising”, “consisting essentially of”, and “consisting of” may be replaced with either of the other two terms. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.
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Described are articles that serve as integrated dispensers or applicators for powdered compositions. Primarily, the powder-dispensing articles of the invention include a housing in which a cartridge is disposed that can move in relation to the housing, typically by depressing a plunger that protrudes from the housing. The housing unit contains a housing access port that provides access to the preferably replaceable cartridge. The cartridge also contains an orifice, referred to as a cartridge access port, in the cartridge wall. The housing and cartridge access ports are brought into alignment by the user, for example, by depressing a plunger that causes the cartridge to move in relation to the housing by compressing a biasing member. Such port alignment exposes the powdered composition inside the cartridge.
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DESCRIPTION OF THE INVENTION
The invention relates to a device for the stuffing of plastic materials, for instance sausage "brat" into a casing or the like which is slid on a tube-like socket and, during the stuffing operation, runs off through an annular opening between the mouthpiece of the socket and a nozzle which is movable back and forth between a filling position and an idle position.
If the supply of casing, which had been slid on the socket, for instance a pivotally mounted socket, has been used up, the socket must be removed and a new supply of casing ribbon must be slid on the socket. Since the capacity of a modern stuffing device of the present type depends to a large degree on how fast the socket can be restocked with a new supply of casing, this operation is of special importance.
There are sturdy qualities of casings where the beginning of the casing ribbon is wrapped once around the exit of the socket tube. Then the nozzle is placed in the stuffing position, and finally the casing is pressed through the nozzle in the direction of the operation with the help of the filling pressure.
Unfortunately, many natural and synthetic casings cannot withstand the increased mechanical stress which occurs with this operation when the filling pressure is used; therefore the casing very frequently bursts. In order to avoid this, the person operating the machine must thread the beginning of the casing through the nozzle with his fingers. This action is tedious and time consuming.
The invention is therefore based on the problem to design a device of the present type in such a way that, at the beginning of the filling operation, the start of the casing can be easily threaded through the nozzle (which has been moved into its filling position) without any damage.
As set forth in the present specification, this problem is solved by a hook at the end of a pin which is coupled with the device by way of connecting elements in such a manner that it reaches through the nozzle when the nozzle is in the idle position and threads the end of the casing, which has been fastened on the hook, through the nozzle opening when the nozzle returns to its filling position.
With a device designed in such a way no special operation is necessary to thread the casing through the nozzle. The operator must merely turn the front end of the casing supply, which has been slid on the socket, into the opposite hook and then pivot the nozzle into its filling position. The threading of the casing through the nozzle then takes an automatic course.
According to the construction type of the filling device the pin, on whose end the hook is located, can be disposed either stationarily or movably on the device. On a device with a pivotable carrier for the nozzle, the nozzle plane of which is at a distance from the axis of rotation of the carrier, the connecting elements of the pin consist preferably of a carrying arm and a rectangular linkage attached on said arm where the one link pivot lies on the axis of rotation of the nozzle carrier. In this connection it can be of advantage if the pin has a curvature.
This way there is achieved with relatively simple kinematic means that the hook always moves through the center of the nozzle. This solution has the additional advantage that, with appropriate dimensioning of the rectangular linkage, the hook in its idle position is near the mouthpiece of the turn-off socket and, in its filling position, is at a sufficiently far distance from said mouthpiece. This way, on the one hand, one can thread conveniently and, on the other hand, one can maintain a sufficient distance from the threading hook and the exiting stuffed casing during the filling operation.
It can be of advantage to design the hook in the type of the eye of a needle that is open at the side.
The pin can also be screwed on the carrying arm so that, according to the quality of the casing, the best suited pins with corresponding hooks can be inserted and used.
In the following, a preferred embodiment of the invention is explained in detail with reference to the drawing. In the only FIGURE of this drawing the nozzle of a filling device for casings and such, which is fastened on a pivotable carrier, is shown in section by continuous lines in its threading position and by dash-dotted lines in its filling position.
A filling device (which is not shown in the drawing) includes a stationary attachment 1 with a point of rotation 2 in the form of a bolt for a rotatable holding arm 4 with a nozzle 5 for a holding device for the casing as it is used, for instance, for sausage stuffing machines. This nozzle carrier 4 can be rotated around an axis formed by the point of rotation 2 from the lower idle position, which is shown by continuous lines in the drawing and in which the front end of the casing 8 can be fastened on a threading pin 11 (which will be described in detail hereinafter), into a filling position indicated by dash-dotted lines.
In the filling position, the holding arm is indicated by 4' and the nozzle by 5'. In this position the mouthpiece of a pivotable socket 7 of the holding device for the casing is indicated by dots and dashes is in a conical enlargement of the nozzle 5 while forming an annular opening through which the casing 8 can pass braked during the filling position.
As can be seen in the drawing, the narrowest area of the bore in the nozzle 5 is in a plane which runs approximately in the area of the lower edge of the holding arm 4 and is distant from the point of rotation 2. In order that the threading pin 11, which protrudes through the bore of the nozzle 5 in the idle position or threading position of the nozzle, moves always through the center of the nozzle bore, it is necessary in the present example that the threading pin 11 has a curvature. beyond this, the threading pin 11 is kinematically connected with the holding arm 4 by way of a rectangular linkage which is described in detail immediately hereinafter.
As can be learned from the drawing, the threading pin 11 carries on its rear end a thread and is screwed in place in a corresponding bore on the free end of a hook carrier by means of two nuts 13 and 14. This screw connection permits the alternative fastening of a corresponding threading pin 11 with an appropriately shaped hook 12 on the hook carrier 10 according to the type of casing used.
The actual rectangular linkage for the kinematically correct coupling of the hook carrier 10 to the holding arm 4 of the holding device for the casing is formed by the previously mentioned stationary attachment 1 on the device, an attachment 6 of the holding arm 4, a base attachment 14 and, on the upper end of the hook carrier 10 in the drawing, a tongue 19 and also a total of 4 points of rotation 2, 16, 18 and 20. As mentioned before, the point of rotation 2 connects the stationary attachment 1 with the holding arm 4. In the point of rotation 16, the base attachment 14 is pivotally connected with the attachment 6 of the holding arm 4, whereas the tongue 19 is connected at points of rotation 18 and 20 with the base attachment 14 or the stationary attachment 1, respectively.
In the idle position or threading position illustrated by continuous lines in the drawing, the holding arm 4 with the nozzle 5 is swung away from the mouthpiece of the pivotable socket 7 drawn by dots and dashes. In this position a new casing 8 can be slid on the socket 7 and the lower free end of the casing 8 can be hung into the hook 12 of the threading pin 14 which protrudes through the nozzle 5.
When subsequently the holding arm with the nozzle 5 is again swung into the filling position indicated by dots and dashes, the threading of the casing 8 through the opening of the nozzle 5 takes place automatically. The rectangular linkage described before assures that the threading pin 11 always moves through the center of the nozzle bore 4. When the holding arm 4 is in its filling position designated by 4', the hook carrier 10 with the threading pin 11 assumes a second position which is also drawn dash-dotted, and in which the hook carrier is marked 10' and the threading pin 11'.
The specific example of the invention as heretofore described is by way of illustrative example. Various changes will no doubt occur to those skilled in the art and will be understood as forming a part of the present invention insofar as they fall within the spirit and scope of the appended claims.
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A tube-like socket is provided in a machine for stuffing sausage and the like. A nozzle is swingably or pivotally mounted for swinging movement between operating position in which a sausage tubing feeds between the socket and nozzle, and idle position away from the socket. A hook-like structure is pivotally converted to the mounting mechanism for the nozzle such that it projects through the nozzle with the nozzle in idle position and automatically feeds sausage tubing through the nozzle as the nozzle is swung to operating position.
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BACKGROUND OF THE INVENTION
The present invention relates to a revolving cutting press with a rotatable tool. More particularly, it relates to a revolving cutting press which has at least one revolving plate provided in its peripheral region with a plurality of complete tool sets, a drive for driving the revolving plate about an axis, and at least one tool set rotatable about an axis extending substantially perpendicular to the plane of the revolving plate.
Revolving cutting presses of the above mentioned general type are known in the art. During the production of punched parts by means of revolving cutting presses, tools profiled in the peripheral region are frequently used. They are received in the revolving plate rotatably about their longitudinal axes and are controllable in their angular position. Such revolving cutting press is disclosed for example in the German Document DE 3,441,530 A1. It is characteristic for this revolving cutting press that for driving the tools about their longitudinal axes at least a special motor drive is required. Such a drive is arranged in the peripheral region of the revolving plate and can be coupled with individual tool sets. For transferring a predetermined tool set to its working position which includes a rotation of the revolving plate to the respective punching position and a rotation of the tool set about its longitudinal axis to a predetermined angular position, the revolving plate is first transferred by actuation of its drive to the punching position and fixed with special arresting devices. Then, the drive associated with the rotation of the tool about its longitudinal axis is coupled with a respective tool, and the tool is transferred to the desired angular position. For specific positioning of the tools relative to their longitudinal axes, in other words for specific angular adjustment of the tools, the tool sets prior to a plate rotation must be either arrested in their last rotary angular position so that, starting from a predetermined, supplied rotary angular position the rotation required for reaching a new rotary angular position is achieved. Or, before each change of the rotary angular position, first the exact zero position of the respective tool set must be adjusted to arrive at a new angular position from this zero position.
These known revolving cutting presses are relatively complicated with respect to their drive and control expenses for the system of the revolving plates and rotatable tools. Moreover, depending on the coupling of the special drive associated with rotation of the tool sets about their longitudinal axes, the synchronization of the rotary angular positions of upper and lower tool for avoiding the angular errors and tool damages must be thoroughly monitored. Furthermore, the coupling of a further drive in many cases causes additional inaccuracies.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a revolving cutting press of the above mentioned type, which avoids the disadvantages of the prior art.
More particularly, it is an object of the present invention to provide a revolving cutting press of the above mentioned general type which is structurally simplified in the sense of its drive and control.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a revolving cutting press in which the tool set rotatable about its axis is connectable with the drive of the revolving plate.
In accordance with the present invention, the rotary movement required for driving a tool set about its longitudinal axis is derived directly from an available controllable drive system for driving the revolving plate about its rotary axis. This presumes however features for selective coupling of the above mentioned drive either with the revolving plate or with a predetermined tool set. In comparison with the above described prior art, the arrangement of a special drive whose only purpose is to rotate an individual tool set is dispensed with. Moreover, an available controllable drive is used for rotation of the tool set. This results in a reduction of the structural and controlling expenses. While in the above discussed known revolving cutting press the drive for rotating individual tool sets about their longitudinal axes is located in the peripheral region of the revolving press and therefore a certain increase of the lateral place consumption occurs, the inventive cutting press provides the further advantage in that its dimensions are not touched due to individual tool sets rotatable about their longitudinal axes. The reason is that the drive elements which serve for the coupleable connection with the plate drive are arranged in a region near the axis of the revolving plate.
In accordance with another embodiment of the present invention, each revolving plate can be provided with an individual drive from which the rotary movement of individual tool sets can be derived. However, also a common drive for both revolving plates arranged over one another can be provided, so that the rotary movements of all tool sets can be derived from this common drive. In the latter case, a branching transmission for transmitting the rotary movements to both revolving plates is required. But, as compared with the first mentioned case, the arrangement of special synchronizing devices for insuring the identical rotary movement of both revolving plates can be dispensed with. In this case, angular errors with respect to the position of the upper and lower tool are avoided in a simple manner. Since the functional elements required for transmission of rotary movement to the individual tool sets are arranged on the opposite side of the revolving plates, the narrow intermediate space between the revolving plates is not affected by the rotary drive of individual tool sets.
Still another feature of the present invention is that the switchable functional elements are arranged in the region immediately adjacent to the axis of the revolving plate. As a result, a compact construction of the rotary drive for the tool sets which does not affect the outer space is provided.
Residual functional elements of the drive can include a disc coaxially surrounding the axis of the revolving plate for frictional torque transmission, and a controllable device for the axial displacement of the disc. This controllable device can be of any construction. It is especially advantageous when it is designed as a pressure-medium actuated device. The remaining functional elements for actuation of the tool drive can include a toothed gear transmission providing a kinematic connection between a rotation a plate drive shaft and the individual tool. When a frictional connection is produced by the above mentioned disc, the whole revolving plate including the tool sets rotatable on it moves as a rigid body. When a frictional connection through the above mentioned disc is however not produced and the respective revolving plate is arrested, a rotation of the plate drive shaft results in a rotation of the tool set in correspondence with the transmission ratio of the above mentioned toothed gear transmission. Since all rotatable tool sets are coupled in this sense with the plate drive shaft, an individual tool set always rotates all tool sets during a positioning movement.
The invention provides for an especially simple embodiment of the controllable device for axial displacement of the disc. It includes a ring piston received in a ring groove in the revolving plate, and pressure medium openings in the plate drive shaft. When the disc is axially displaced on the plate drive shaft for the frictional torque transmission and at the same time does not rotate relative to the latter, the above mentioned ring piston causes the rotary movement of the plate drive shaft only in the event of the pressure application, or in other words, in case when a torque transmission to the revolving plate occurs.
The controllable device can be designed in accordance with an alternative embodiment, wherein the ring piston can be formed of one piece integrally with the above mentioned disc. In this construction a reduction of the number of structural elements is achieved and therefore a simple construction of the revolving plate is provided. Simultaneously, the mass of the parts rotatable with the plate drive shaft during its rotation is increased by the mass of the ring piston.
All drive elements of an individual tool set are always arranged on the upper or lower side of the respective revolving plate, so that the narrow intermediate space between the revolving plates is not affected by the rotatable arrangement of the individual tool sets. The upper tool can be composed from a punch and a punch holder which latter can be received in an axially displaceable and non-rotatable manner in an opening of a bush inserted in the upper revolving plate. The bush can be driveable through a toothing formed in its edge. However, the bush can be formed of one piece integrally with the punch holder, so that here also the number of the structural elements is reduced.
Tooth gaps can be eliminated in the region of the toothed gear transmission for driving the tool sets and thereby the accuracy of the rotary angular adjustment of each tool set can be increased. This can be achieved by displaceable arrangement of the toothed gears on the respective revolving plates. These features as well as the adjustable arrangement of the toothing of the bushes serve for accurate adjusting of a zero position for all rotatable tool sets. In connection with the substantially play-free toothed gear transmission, synchronization errors between the rotary angular positions of the upper and lower tool are avoided and simultaneously the control expenses for positioning of the tool sets maintained at a low level.
Depending on the space consumption for mounting the toothed gear transmission above or below a revolving plate, any number of tool sets can be driveable about their longitudinal axes. Also, the toothed gear transmission can be replaced by a respective rotary angular, switchable transmission device between the plate drive shaft on the one hand and the bush on the other hand.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a revolving cutting press in accordance with the present invention;
FIG. 2 is a side view of a revolving cutting press in accordance with the present invention;
FIG. 3 is an axial section of an upper revolving plate of the revolving cutting press of the present invention;
FIG. 4 is an axial section of a lower revolving plate of the revolving cutting press of the present invention;
FIG. 5 is a plan view of the upper side of the upper revolving plate; and
FIG. 6 is a plan view of details of the upper revolving plate of the inventive revolving cutting press.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows an inventive revolving cutting press as a whole. The revolving cutting press has a C-shaped base frame 1, and two revolving plates 2 and 3 arranged at a distance from one another on the end region of the base frame 1. The revolving plates 2 and 3 are coaxial with one another and rotatable about a vertically extending axis. The revolving plates 2 and 3 carry a plurality of complete tool sets 4, 5 arranged in series in the peripheral region of the revolving plates. The construction of the tool sets will be explained in detail later on, and the tool set includes at least one punch arranged in the upper revolving plate 2 together with a punch holder and a matrix arranged in the lower revolving plate. The two sets 4, 5 of the upper and lower revolving plates 2, 3 are located so that they are axially oriented relative to one another.
The base frame 1 serves also for receiving the support and the drive of the revolving plates, as well as elements for actuating the press drive, which cooperate respectively with the tool sets located in a working station 6. Reference numeral 7 identifies a known coordinate table. By a not shown auxiliary means, the coordinate table serves for exact positioning of the workpiece which as a rule is flat, for example a sheet, relative to the working station 6.
For turning or controlling the cutting press, a DNC-control 8 is provided. The DNC-control 8 is accommodated near the base frame in a switching cabinet.
The punches of at least some tool sets 4 are profiled in their peripheral region. These tool sets 4 are received rotatably about their respective longitudinal axes 9 in their receptacles in the revolving plates 2, 3. For this purpose the revolving plates are provided with special drive elements 10 which will be explained later on and serve for individual driving of the above mentioned tool sets about their longitudinal axes 9.
Reference numeral 11 schematically identifies an axis. The revolving plates 2, 3 are rotatable in the base frame 1 about the axis 11.
An electric motor is identified with reference numeral 12 in FIG. 2. It serves for driving in a not shown manner both revolving plates 2, 3 about their axes 11 and the tool sets 4 about their axes 9. The motor 12 which is stationarily mounted in the base frame 1 is connected for this purpose with an intermediate shaft 14 through a toothed belt 13. The intermediate shaft 14 is supported in the base frame 1. The connection is performed through pulleys 15 and 16 which are arranged on the drive shaft of the motor 12 on the one hand and the intermediate shaft 14 on the other hand. The motor 12 is NC-controllable in a known manner and is in operative communication with the DNC-control 8 in a not shown manner.
The intermediate shaft 14 which is vertically supported in the base frame 1 is connected in turn with pulleys 18, 18' through toothed belts 17, 17'. The pulleys 18, 18' are arranged respectively on the plate rive shaft 19, 19' extending in the direction of the axes 11. The connection of the toothed belt 17, 17' with the intermediate shaft 14 is performed through pulleys 20, 20' arranged on the latter. The belt drive defined by the pulleys 19, 20 in connection with the belt drive 17 on the one hand, serve respectively for driving the upper plate 2 and the lower revolving plate 3 and moreover also for driving the individual tool sets 4 as will be explained hereinbelow.
The plate drive shafts19, 19' are received in bearings which have bearing housings 21, 21' supported in the base frame 1. For arresting of the revolving plates 2, 3 in predetermined rotary angular positions, arresting devices 22, 22' are provided as will be explained later on. A further motor which serves for driving the press itself is not shown in the drawings. It is in operative communication with the press plunger 25 through a cardan shaft 23 and an eccentric 24. The punch located in the working station 6 is coupled with the press plunger 25.
FIG. 3 shows a construction of the upper revolving plate 2 in an axial section. The plate drive shaft 19 is supported on the one hand by a bearing housing 21 received in the base frame 1 or the radial bearing 26 associated with the bearing housing, and in a radial axial bearing 27 schematically shown in the drawings. The axial bearing 27 cooperates with a running ring 29 mounted on the lower side of the revolving plate 2 by screws 28.
The tool set 4 of the upper revolving plate 2 shown partially in section includes a punch holder 30 which contains a punch 30' and is non-rotatably supported in a bush 32. The punch 30' is displaceable in a known manner in direction of the arrow 31. A key 33 for non-rotatable guidance of the punch holder 30 is inserted in its periphery and slides inside a groove 34 formed on the inner side of the bush 32. The sliding is performed in a peripheral direction and in a substantially play-free manner. The bush 32 in turn is inserted in a corresponding opening 35 of the revolving plate 2. Inside the opening it is supported on the one hand by a ring body 36 arranged on its upper end for engaging the opening 35, and on the other hand by an arresting ring 37 engaging in the outer side of the bush part which extends outwardly beyond the lower side of the revolving plate 2. The ring body 36 carries a toothing 38 in its peripheral region. The toothing 38 serves for driving the tool set 4 in rotation about its axis 9 in a manner which will be explained hereinbelow.
The punch 30' is provided at its upper side with a T-shaped head part 39. This head part is received in a correspondingly designed receptacle of the press plunger 25.
A plurality of openings 41 are arranged in an outer edge 40 of the revolving plate in a uniform manner at positions corresponding to the positions of the tool sets. The opening 41 extends parallel to the axes 9 of the tool sets and accommodate receiving bushes 42. The receiving bushes 42 cooperate with arresting pins 43 of the stationary arresting device 22.
Reference 44 identifies a toothed gear which engages the toothing 38. The toothed gear 44 is further rotatably supported on a bearing bush 45 by a radial bearing 46. The bearing bush 45 is connected by a screw 47 with the revolving plate. The axis of the toothed gear 44 extends parallel to the axis of the plate drive shaft 19.
The above mentioned toothed gear 44 is in further engagement with a toothed gear 48. The latter is non-rotatably arranged on the plate drive shaft 19.
Reference 49 identifies an insertion ring which is inserted in an opening 50. The opening 50 is arranged in the vicinity of the axis of the revolving plate 2 and is open above and toward the axis of the plate. The insertion ring 49 is connected at its radially outer end with the revolving plate 2 by screws 51. The lower side 52 of the recess 50 is provided with a ring groove 53. The ring groove 53 extends in the vicinity of the axis and coaxially to the plate drive shaft 19 and open in direction to the insertion ring 49. A ring piston 54 is inserted in the groove 53. The ring piston 54 is provided with seals 55 at its radially inner and outer sides. It is slidable in the ring groove 53 in direction of the arrow 56.
An opening 57 which extends coaxially inside the plate drive shaft 19 serves for pressure medium supply to the ring piston 54. A plurality of radial openings 58 extend from the opening 57 and provide a communication between the opening 57 and a ring chamber 59. The ring chamber 59 is formed between the outer side of the plate drive shaft 19 on the one hand and the inner side of the revolving plate 2 on the other hand. The above mentioned ring chamber also communicates with the lower side of the ring groove 53 through a series of radially extending passages 60 for loading the ring piston 54.
Reference numeral 57" shown in FIG. 2 identifies the rotary connections for the pressure medium supply.
Reference numeral 61 identifies a circular ring-shaped disc which is slidingly inserted in a recess 63 provided in the lower side 62 of the insertion ring 49. It extends coaxially to the axis of the plate drive shaft 19. The disc 61 is non-rotatably mounted on the plate drive shaft 19 by a multiple-connection 64 and is insignificantly axially slidable due to this connection.
It can be recognized from the above presented description that under the action of a pressure loading of the ring piston 54 through the openings 57, 58, 60 the ring piston 54 slides upwardly in direction of the arrow 56 and in this manner presses the disc 61 against the insertion ring 49 so that the revolving plate 2 is coupled with the plate drive shaft 19 in a frictional manner. Without the pressure loading, the disc 61 is freely rotatable relative to the insertion ring 49. Therefore, with the arrested revolving plate 2, a rotation of the plate drive shaft 19 in this case results through the toothed gears 48, 44 in a rotation of the bush 32.
Reference numeral 65 identifies a further radial opening inside the revolving plate 2. It connects the ring groove 53 with the inner side of the opening 65, so that leakage fluid produced inside the ring groove 53 is used for lubricating the bush 32.
FIG. 4 shows the lower revolving plate corresponding to the showing of FIG. 3. The comparable operational elements are identified with the same reference numerals with the addition of ', and therefore a redundant description is avoided.
Reference numeral 66 identifies a matrix arranged axially non-displaceably on the bush 32', and rotatable relative to the bush.
Reference numeral 67 identifies a workpiece to be machined and formed for example as a flat workpiece. In deviation from the upper revolving plate 2, the drive elements 10 for rotating the tool, here the matrix 66, are located on the lower side of the lower revolving plate. The arrangement is however mirror-symmetrical relative to the upper revolving plate. Therefore the recess 50' as well as the ring groove 54' are open to the lower side of the revolving plate 3. Since the operation of the selective coupling of the plate drive shaft 19' with the revolving plate 3 or the bush 32' and thereby the tool, here the matrix 66, corresponds to the respective mechanisms of the upper revolving plate 2 its description can be dispensed with.
The showing of FIG. 5 which, depending on the properties of the respective tool, can be interpreted either as a plan view of the upper side of the upper revolving plate 2 or the view of the lower side of the lower revolving plate 3, shows that all tool sets are arranged in the peripheral region of the revolving plate on a common partial circle 68. In the shown embodiment four tool sets 4 are supported rotatably about their axes. The remaining tools which are different from one another and identified as a whole with reference numeral 69 are arranged non-rotatably about their respective longitudinal axes. The intermediately arranged toothed gears 44, 44' provided for connection between the central toothed gears 48, 48' are located in turn also on a common partial circle 70.
FIG. 6 shows on a plan view the inventive drive elements 10 in accordance with a further embodiment on the upper revolving plate 2. In identical manner they can be used also on the lower revolving plate 3. The central toothed gear 48 is mounted through two key-groove connections on the plate drive shaft 19.
The bearing bush 45 is provided with a longitudinal opening 71 for receiving the screw 47. With a respective dimension of the longitudinal opening 71, a certain adjustability of the set position of the toothed gear 44 is possible. The toothing 38 is located in a toothed ring 72 which is screwed in a not shown circular ring support. The latter forms an integral part with the bush 32. The connection between the toothed ring 72 and the above mentioned circular ring support is performed by screws 73 inserted in longitudinal openings 74 of the toothed ring 72. The longitudinal openings 74 are located along a common partial circle and extend substantially coaxially to the axis of the tool set 4.
The adjustability of the central toothed gear 44 as well as the toothed ring 72 illustrated in FIG. 6 provides for an approximately play-free coupling of the rotary movement of the toothed gear 48 with the bush 32 on the one hand, and the adjustment of exactly definite initial angular position of the bush 32 on the other hand in such a manner that the central point of the key-groove connection 33, 34 is oriented to the central point of the plate drive shaft 19. In this manner, a highly accurate, play-free drive for the individual tool sets 4 is provided. Simultaneously, the control required for accurate positioning of a rotary angular position can be maintained low, since all tool sets are associated with the same zero position.
Practically, the arresting devices 22, 22' can be interconnected with the above mentioned ring pistons 54, 54' in a controllable manner, so that during pressure loading of the ring pistons the revolving plates are always freely rotatable.
It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.
While the invention has been illustrated and described as embodied in a revolving cutting press, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.
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A revolving cutting press comprises at least one revolving plate having a peripheral region provided with a plurality of complete tool sets, a drive for rotating the revolving plate about an axis, at least one tool set rotatable about an axis extending substantially perpendicularly to plane of the revolving plate, the tool sets being connectable with the drive of the revolving plate.
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FIELD OF THE INVENTION
[0001] This invention relates to a powered mechanism such as a spindle head and more particularly, but not exclusively, concerns a multi-axis spindle head.
BACKGROUND OF THE INVENTION
[0002] With the increasing ability of designers using CAD systems to specify complex surfaces, there is a similar need for machine tools to articulate about all 5 degrees of freedom to render these surfaces in metals.
[0003] Currently most machine mills move the spindle along 3 Cartesian axes, with the 2 axes tilt of the spindle not supported. It would be desirable to substitute the usual fixed axis spindle with one able to additionally tilt in 2 axes such as to upgrade 3 axis machines to 5 axes.
[0004] Many solutions to this need have been proposed, however all are compromises involving accuracy, stiffness, compactness and complexity.
OBJECTS AND SUMMARY OF THE INVENTION
[0005] The principal object of the present invention is to overcome or at least substantially reduce some at least of the drawbacks of known spindle heads.
[0006] It is another object of the present invention to prescribe a new means of articulating a spindle in 2 axes about a common focal point. It is another object or the present invention to avoid the mechanical complexity of traditional geared rotary stages by use of push rods acting against cranks to effect the rotations. This enables low cost ball screws to be employed.
[0007] In broad terms, the present invention resides in the concept of taking advantage of a novel multi-axis spindle head design to provide movement about two orthogonal tilt axes, thereby enabling the spindle head design to have additional degrees of movement over known spindle head designs.
[0008] Thus, according to the present invention, there is provided a powered mechanism able to articulate about two orthogonal tilt axes wherein means retained by a notional ring or band is constrained such that it can only rotate about the axis of the notional ring or band and with motive source to displace one with respect to the other, and the notional ring or band is also able to pivot about an orthogonal intersecting axis when motive source is applied from a reference position, the mechanism providing an output orthogonal to and intersecting the other two tilt axes.
[0009] Advantageously, this invention splits up the 2 axes into mechanically independent systems in the manner of a gimbal. Driven push rods can then power each movement axis, and encoders can be located around these axes in order to measure their absolute degree to rotation.
[0010] In an embodiment of the invention which is described in detail hereinafter a spindle unit is located within a notional sphere, and means are provided to articulate the sphere. One axis is supported by a band running around the sphere and keyed into the sphere such that it can only move around one latitude. This band is pivotally supported by bearings whose common axis intersects the sphere focal point. A servo motor is attached to the band with a ballscrew extending in the motor axis. The ballscrew runs through a nut otherwise retained to the sphere. Both motor unit and nut support are pivotally supported. As the motor rotates the screw, the nut is displaced along it, in turn rotating the sphere with respect to the band and in a common axis. An encoder strip is placed around the sphere and a read head is located on the band to determine angular displacement.
[0011] The other axis is also enabled by a further motor and push rod system acting from a fixed reference on the unit housing and pushing against the band via a short crank arm. The band is thereby caused to rotate about its support pivot axis and in turn rotates the sphere by virtue of being keyed into a latitudinal track as explained above. A further encoder track is supported by an arc segment with a common pivot axis to the band. A read head is retained by the housing and overhangs this track such that it can measure its angular displacement.
[0012] The band can advantageously have actively opposed segments such that it retains itself around the sphere. The sphere will then be entirely supported by the band pivot axes. Alternatively the band can serve to push the sphere into an annular socket. In this case the socket acts to establish the spheres focal point Cartesian position, with the band arranged to “float” with respect to the housing around the sphere but still applying downward preload.
[0013] In another embodiment which is also described in detail hereinafter a gimbal based 2 axis articulation stage comprises a mounting ring that pivotally supports a gimbal ring which in turn pivotally supports the spindle unit on an orthogonal axis.
[0014] Drive units are then arranged to push/pull from the mounting ring to the gimbal ring, and from the gimbal ring to the spindle unit. The push/pull action causes rotation about the respective pivot axes thereby effecting the 2 axis tilt of the spindle unit.
[0015] The two drive units are arranged in a “T” configuration to avoid interference during articulation and to minimise the overall package size.
[0016] The degree of tilt can be conveniently measured from encoder tracks mounted on a radial section of the spindle unit and on the gimbal ring. By locating the tracks equatorially centred about their respective pivot axes the system is relatively immune from axial displacement errors and with suitably located encoder read modules delivers accurate absolute radial displacement values.
[0017] The mechanical arrangement comprises a small number of compound parts that can be cost effectively produced from castings with limited finish machining. Firstly a mounting ring that can be extended to become the unit housing and supports a pivot axis, a drive unit and an encoder read module. Then a gimbal ring supports two pivot axes, a drive unit, a push point, an encoder track and an encoder read module. Finally a spindle unit supports a pivot axis, a push point and an encoder track and the spindle mechanism. Of course these parts can bc made out of separate components for ease of manufacture if preferred.
[0018] The two pivot axes between the spindle unit and gimbal ring, and gimbal ring and mounting ring can be arranged such that when preloaded they both try to either open up or compress the gimbal ring. This minimises any distortion of the gimbal under load as it is harder to bend it into a ‘square’ than to squash it into an ellipse. To effect this the internal mounting between gimbal and sphere should be push based, and the external mounting between gimbal and mounting ring pull based—or vice versa.
[0019] The services to the spindle unit also have to articulate about the two tilt axes. So as not to interfere with the tilt mechanism, this is most conveniently done on the underside of the mounting ring. To support the articulation an appropriate arrangement is to form the services power, air and fluid connections along a spiral pathway from the end of the spindle following a spherical profile to the underside of the mounting ring. The spiral can then compress about any net tilt axis.
[0020] The above and further features of the invention are set forth with particularity in the appended claims and will be described hereinafter with reference to exemplary embodiments which are illustrated in the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
[0021] [0021]FIG. 1 is a perspective view of a first embodiment of the present invention, partly in section;
[0022] [0022]FIG. 2 is an enlarged perspective view of the first embodiment with the spindle sphere displaced to reveal details that otherwise would be obscured;
[0023] [0023]FIG. 1 is an enlarged, fragmentary perspective view showing details of the seating of the spindle sphere of the first embodiment;
[0024] [0024]FIG. 4 is a perspective view showing a second embodiment of the present invention;
[0025] [0025]FIG. 5 is a top plan view of the second embodiment, shown to a reduced scale;
[0026] [0026]FIGS. 6 and 7 are front and side elevation views of the second embodiment, again shown to a reduced scale; and
[0027] [0027]FIG. 8 is an enlarged perspective view of the gimbal ring of the second embodiment, the gimbal ring mounting the spindle sphere and itself being mounted in the mounting ring.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0028] Referring to FIGS. 1 to 3 which show a first embodiment of the invention, a rotary spindle 18 is mounted to a sphere 3 which is mounted for articulation in two orthogonal directions, a first of which is accommodated by mounting of the sphere 3 to an arcuate band 1 with the sphere being movable in one direction relative to the band by virtue of the provision of a sphere tilt motor 7 which is mounted on the band and drives the sphere. The band 1 is in turn arranged to be movable in an orthogonal direction by virtue of being pivotally mounted in a housing 25 with a band tilt motor 5 mounted in the housing and driving the band 1 . The bottom of the sphere 3 is journalled a spherical socket defined in the housing 25 , with the spindle 18 projecting through a window in the housing.
[0029] The band 1 is semi-circular extending to house pivot bearings 15 in its longitudinal axis. It has circumferal underside grooves 22 that act as ball bearing raceways. Conforming raceways are located in the top of the sphere 3 . The balls are retained by a cage that looks like an arc segment with a subtended angle that is smaller than the effective raceway by half the maximum articulation angle. This ensures that the ball cage assembly 21 can roll around between its raceways 22 without overlapping them at its limits. The top cap 2 of the articulating sphere 3 is of a size such that when at full articulation it still does not interfere with the support socket rim. The lower segment of the sphere needs to be prepared to a good sphericity to ensure good maintenance of focal point when articulating around the socket.
[0030] More than one raceway can be employed but always sharing the same pivot axis. The band 1 can be pre-loaded against the sphere 3 from its pivot axes 15 by means (not shown) such as an elastomeric bearing support or externally arranged downward preload on the bearing axles. Alternatively, the band could be preloaded by an opposing bearing raceway caused to move along the common axis by a means that applies pressure around its rim. This latter arrangement would have the stiffness advantage of two tracks, without requiring high engineering precision or risking over-constraining the two ball tracks resulting in spatial instability.
[0031] A mounting bracket 5 is added to the band 1 to pivotally retain the sphere tilt motor 7 . The pivot is necessary to accommodate changes in angle as a ballscrew 10 follows the circumference of the sphere 3 . The motor core is attached to the ballscrew 10 and held in bearings that prevent its axial displacement. Tile ballscrew 10 then extends out in the motor axis. A ballnut 12 rides on the screw 10 and is pivotally retained to a short crank arm 4 extending from the sphere 3 . Suitable cut-outs in the sphere and the band permit the displacement of the screw and rotation of the crank arm.
[0032] The sphere 3 has an accommodation for a readable scale 20 to be fitted. This must extend around the sphere by a subtended angle greater than the expected maximum tilt angle. A read head 19 is retained on the band 1 such that it can read the scale 20 .
[0033] A mounting bracket is provided on the band 1 to act as a crank arm 14 pivotally supporting a further captive ballnut 13 . In this case the band tilt motor/ballscrew unit 8 is pivotally supported by a bracket 6 on the housing 25 . In operation it therefore displaces the band 1 with respect to the housing 25 and can then only rotate about its pivot axis-rotating the sphere 3 with it.
[0034] A further readable scale 17 is attached to the circumference of an arc segment 16 with a defined pivot axis that can be brought co-axial with the band pivot axis. A reader 11 is retained on a bracket otherwise attached to the housing 25 such that it can read the scale and consequently measure the displaced angle of the band about the common pivot axis.
[0035] Instead of employing a servo driven push rod system where the nut is captive and the screw shaft is rotated, the nut could alternatively be rotated by the motor causing the screw shaft to be driven through it. In this case the end of the screw shaft would be pivotally retained by the crank arms and a spatial accommodation would need to be made to permit the screw shaft to extend out of the back of the motor as it is withdrawal. One advantage of this variant is that, because the screw shaft would never extend beyond the end of the crank, it would not need any commensurate cut-outs in the sphere or band to accommodate it. Also because the shaft would not be rotated, the inertial mass could be lower and critical speed problems would be less likely to arise.
[0036] In this embodiment the band system applies downward preload onto the sphere, pressing it into an annular socket ring defined in the housing 25 . It is the socket that consequently establishes the reference position of the sphere. It is cut out to provide a window shown in FIG. 3 which provides space for the spindle to extend through it over as much of its theoretical articulation range as possible. This window accommodates the spindle shaft in swinging through its maximum tilt in one axis, and then that arc swings to its maximum tilt about an orthogonal intersecting axis. Because after the first swing, the tilt limits are closer to the axis of the second swing, the window is not symmetrical but in plan view would have vertical short sides 23 and subtended arc long sides 24 .
[0037] The net articulation range is therefore the full “a” tilt taken through the full “b” tilt. The diagonal displaced angle is consequently greater than the individual maximum tilt angles.
[0038] The drives 7 and 8 ideally employ brushless servo motors. They can have integrated annular encoders that permit push-rod extension and hence subtended linkage angle to be deduced, but a preferred arrangement is to close the control loop around the absolute measured displaced angles.
[0039] Because the push-rods defined by the ball screw shafts act against the sphere or band at varying angles, such as in one embodiment +−40 degrees at their limits, their force and displacement gearing will change by cos 40 and 1/cos 40 respectively, i.e. it will push with around 77% of the maximum rotational force, but will move at around 130% of the speed. These effects can be taken into account by a smart servo controller.
[0040] Referring now to FIGS. 4 to 8 , these show a second embodiment of the invention. In this embodiment, as will be described in detail hereinafter, a spindle unit housed in a sphere 4 is pivotally mounted in a gimbal ring 2 for tilting movement about one axis and the gimbal ring 2 is itself pivotally mounted in a mounting ring 1 for pivotal movement about an orthogonal axis. Drive motors 3 and 5 determine the movements of the sphere 4 relative to the gimbal ring 2 and of the gimbal ring 2 relative to the mounting ring 1 .
[0041] As can be seen from FIGS. 4 to 8 , the notional gimbal ring 2 (“notional” because though performing the function of a ring it is not in fact formed as a ring) lies orthogonal to the spindle axis C-C such that it can be pivotally supported by the mounting ring 1 about axis B-B. The gimbal ring 2 in turn supports the notionally spherical spindle unit 4 on a pivot axis orthogonal to the gimbal ring pivot axis A-A. The two orthogonal pivot axes A-A and B-B intersect at a common point through which the spindle axis C-C also passes orthogonal to the other axes.
[0042] A powered push rod system 3 is mounted on an extension of the gimbal ring 2 to push against the spindle sphere 4 causing the gimbal to pivot about the pivot axis A-A linking the sphere to the gimbal. A further powered push rod 5 is then mounted on the mounting ring 1 and pushes against the gimbal causing the gimbal to pivot about the pivot axis B-B linking the gimbal to the mounting ring.
[0043] The degree of tilt of the two axes is measured by attaching an encoder track 6 radially around the spindle sphere and fixing a read head 7 to the gimbal and by attaching an encoder track 8 to the gimbal and fixing a read head 9 to the mounting ring via an extended support 19 .
[0044] The gimbal ring actually comprises a largely hemispherical shell with cut outs to provide for access to the spindle sphere and encoder track. It can then provide suitable mounting locations for the encoder read head 7 , push rod drive unit 3 and push point 10 which works with the drive unit otherwise attached to the mounting ring 1 .
[0045] The push rod system can be similar to the previous embodiment and comprises rotary drive units 3 & 5 that can be pivotally mounted about axes intersecting and orthogonal to the drive rotation axes. The drive units each support one end of respective ballscrews 12 & 13 with the ballscrews consequently acting as the push rods. Ballnuts 14 & 15 are then held such that they can pivot parallel to the drive units pivot axes and again with the pivot axes being orthogonal to the screws. They are held by mounting supports from the driven member 10 & 10 . The drive units are mounted on extended supports 17 & 18 connecting them to the gimbal ring and mounting ring 1 . The drive unit and captive ball nut unit pivots are all effected by a similar mechanical arrangement, such that a preload can be generated through the bearings to maintain stiffness. Bearing outer races are retained on either side of the units. Stub axles e.g. 21 & 23 extend inward from the mountings, being firmly retained against them by fastener arrays. On one side 2 a series pair of disc springs 2 ′ push from a shoulder on the axles to the bearings inner race. On the other, the axle shoulder directly pushes against the inner races.
[0046] The services (power, air and liquid) are accommodated through 3 sets of 3 tubes 21 arranged as 3 spiral starts with the 3 tubes offset from each other normal to the central spindle sphere. At their start they attach to an extension 20 of the spindle sphere looping round towards the mounting ring where suitable connections can be effected.
[0047] The main pivot axes A-A and B-B are arranged with preload such that they push out from the spindle sphere to the gimbal ring, and pull out from the gimbal ring to the mounting ring. Referring to FIG. 8, the internal pivot axis A-A is effected by locating the outer races of bearings 5 & 5 a in either side of the spindle sphere, and supporting the inner races on stub axles 3 & 3 a otherwise firmly retained against the gimbal ring 10 with arrays of fasteners. Two disc springs in series 4 push from a shoulder on the stub axle to the inner race of the bearing on one side of the pivot axis. On the other side the disc springs are replaced by a spacer 11 that defines the axial offset. The external pivot axis B-B is effected by locating the outer race of the bearings 7 & 7 a into the gimbal ring via ring extensions 5 & 5 a . The inner races arc supported on stub axles 1 & 1 a with a disc spring 9 pushing between the axle and the inner race on one side and again an appropriate spacer 6 acting as the axial displacement reference on the other. The stub axles are pulled finally into the holders 2 & 2 a on tapered shoulders by arrays of fasteners. The holders in turn are firmly retained in the mounting ring with further arrays of fasteners.
[0048] Having described the invention in the foregoing by reference to specific embodiments, it is to be appreciated that the embodiments are exemplary only and that modifications and variations are possible without departure from the spirit and scope of the invention. For example, the sphere in the described embodiment could be replaced by a disc or by any other means performing as described. It is for this reason that the term “notional ball” is used in some of the appended claims; the “ball” does not have to be a sphere.
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A multi-axis spindle head for a machine tool has a spindle drive motor mounted in a sphere ( 4) with the motor axis extending radially and the sphere ( 4) is articulated to move about two orthogonal axes by virtue of being mounted in a gimbal ring ( 10) providing for pivotal movement of the sphere about one axis, and by virtue of the gimbal ring ( 10) being mounted in a mounting ring ( 1) providing for pivotal movement of the gimbal ring about an orthogonal axis. Ball screw drive motors ( 3, 5) provide for controlled movement of the sphere relative to the gimbal ring and of the gimbal ring relative to the mounting ring so as to provide the spindle drive motor with all five degrees of freedom of movement.
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CROSS REFERENCE TO RELATED APPLICATIONS
None.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
This invention was not federally sponsored.
BACKGROUND OF INVENTION
Tools to cut wire have been popular for centuries, as have been wire twisting devices. These types of tools are commonly used in construction, where wire is used to attach two pieces of rebar prior to pouring slabs or columns. Wire twisting and cutting devices are also frequently used to attach fences to posts, repair holes in fences, and wire pieces of reinforcing bar together when pouring concrete slabs and making concrete posts and ceilings. Taking the ends of a piece of wire and twisting them by hand is an extremely time-consuming and strenuous task.
While the prior art has examples of tools which are designed to cut and twist wire, the current invention is the first to combine in an inexpensive hand tool an ergonomic fit, a method of regulating the output and intake of wire, a protective covering over the wire before it leaves the tool, and an efficient cutting and twisting ability which does not twist the wire inside of the tool body itself and can be accomplished using only hand strength without relying on electrical or battery power.
U.S. Pat. No. 5,836,137 to Contreras (1998) teaches an intermittent rotable pneumatic drive which gathers material around an article for tying, but this machine is expensive, cannot be operated by hand, and would not be convenient to use in a construction setting where a small hand tool would be much more convenient.
U.S. Pat. No. 3,091,264 to Stanford (1963), U.S. Pat. No. 3,593,759 to Wooge (1971), and U.S. Pat. No. 4,448,225 to Schmidt (1984) teach hand tools which would be convenient to use on a construction site, but require as part of their operation that the supply wire be twisted, thereby creating a potential for jamming problems with the supply wire.
U.S. Pat. No. 5,501,251 to Vader (1996) teaches a hand tool which has a supply of wire which is twisted by the tool and cut by additional pulling on the tool, but this tool is not ergonomically designed, requires an external source of wire, thereby decreasing its ease of use, and requires the addition of a commercially available ratchet spring return twister rather than having the twisting mechanism built into the tool.
The current invention meet the long-felt need for an inexpensive, easy to use hand tool that is ergonomically designed for the human hand, and supplies wire from an internal spool which can easily be refilled or replaced by a user, has a cranking mechanism to extrude wire from the jaws of the tool or wind back in excess wire, has jaws to cut the wire and a groove and steel ball mechanism to twist the wire was the user pulls back on the tool.
BRIEF SUMMARY OF INVENTION
It is therefore an object of this invention to provide an inexpensive, simple and efficient method of cutting and twisting cutting wire with a tool that is ergonomically comfortable and efficient, and can be used without reliance on electrical or battery power.
It is a further object of this invention to provide a means by which the wire can be fed out through the jaws of the tool through means of a spool.
It is an additional object of this invention that the wire inside the body cavity of the tool is protected from dirt and debris by the tool body, and that the wire inside the body cavity is not twisted by the tool.
Other and further objects and features of this invention will be apparent to one skilled in the art.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 is a side view of the invention show the major external parts, as well as the wire twisting capabilities.
FIG. 2 is a side view of the invention, showing the three main parts: a body part, a head part, and a lock washer. This view shows the inner workings of the invention as well.
FIG. 3 is a cut-away view of the invention, with the external side of the device closest to the viewer removed to show the internal mechanisms of the invention.
FIG. 4 is a partial elevational view of the invention, showing a close-up of the jaw mechanisms.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to a tool which can easily and efficiently twist and cut wire which is fed through the jaws of the tool by means of a spooling assembly and a cranking mechanism.
Referring to the drawings the invention consists of a spool of wire held inside of the tool body, where the wire is fed out through the jaws of tool where the wire is cut, and a series of grooves and steel balls allows the wire to be twisted by the rotating tool head. The tool consists of four detachable parts, a tool body in which the spool is located, the tool head portion where the jaws and grooves are located, a locking ring which attaches the head portion to the tool body, and two steel balls which sit in indentations in the tool body and cause the head portion to spin and twist the wire before it is cut.
FIG. 1 is a side view of the tool. The tool consists of four parts, three of which are visible here. A tool body ( 1 ) is comprised of two tool body parts, the right side or first body part is visible in this drawing. The tool body has a palm section ( 2 ), which has a palm side ( 3 ) and a finger side ( 4 ), and is designed to fit comfortably into the hand of a user. The ergonomic fit is a key feature of this invention. The tool body ( 1 ) has a spool end ( 25 ) and a head end ( 26 ). Attached to the head end ( 26 ) of the tool body ( 1 ), that is, the section furthest away from the palm section ( 2 ) is the tool head ( 5 ), which can rotate about an axis in a circular direction ( 6 ) defined by a wire ( 11 ). The wire ( 11 ) comes from a spool inside the tool body (not shown in this figure), and passes through an upper jaw member ( 8 ) and a lower jaw member ( 7 ) of the tool head ( 5 ), and between a cutting blade ( 9 ) located at the tip of the upper jaw member ( 8 ) and a cutting slot ( 10 ) located at the tip of the lower jaw member ( 7 ). The tool head ( 5 ) rotates around a device comprised of grooves and steel balls, not shown in this figure. The wire ( 11 ) is cut by the jaw mechanism, and then gripped between the upper jaw member ( 8 ) and the lower jaw member ( 7 ) to be twisted. To prevent the tool head ( 5 ) from rotating at times when such rotation is undesirable, the invention has a quick release locking mechanism ( 7 A), which is attached to a pivot point ( 22 ) protruding from the underside of the tool body ( 1 ), and has a lock tab ( 23 ) which fits into slots (not shown in this figure) in the tool head ( 5 ) to prevent the tool head ( 5 ) from rotating unless the quick release locking mechanism is pushed against the locking mechanism retaining spring ( 24 ) by the fingers of the user and allows a user to detach the tool head ( 5 ) from the tool body ( 1 ). To cut the wire ( 11 ) the upper jaw member ( 8 ) has attached to it at a lever pivot point ( 14 ) a lever bar ( 12 ) which, when pressed against a fulcrum bar (not shown in this figure) at a fulcrum bar pivot point ( 15 ), pressure is exerted upon the upper jaw member ( 8 ) such that the cutting blade ( 9 ) snaps the wire against the cutting slot ( 10 ), thereby breaking the wire ( 11 ). The lever bar ( 12 ) moves in a direction indicated by the number ( 13 ). To move the wire either out of the tool or back into the tool, in cases where and excess of wire was pulled out of the tool, there exists a cranking mechanism. The cranking mechanism can be located in one of two positions. In one iteration, the cranking mechanism is located, under number 17 , in the middle of the tool body ( 1 ), where a crank handle ( 18 ) rotates an internal device which moves the wire ( 11 ) in and out of the tool. In another iteration, the cranking mechanism is located, under number 19 , on the spool end ( 25 ) of the tool body ( 1 ), where a crank handle ( 20 ) can swivel and fit into a crank receptacle ( 21 ) built into the tool body.
FIG. 2 is a cutaway view of the tool, showing some of its internal parts. Looking inside the tool body ( 30 ), there is a spool ( 31 ) which rotates about a spool axel ( 32 ). There is a length of wire ( 33 ) wound around the spool ( 31 ). The wire ( 33 ) feeds from the spool ( 31 ) through a guiding and movement restriction device consisting of an upper cylinder ( 34 ) which rides over the wire ( 33 ) and has built into it an upper wire guide, (not shown in this figure), which is a semi-circular indentation in the middle of the surface slightly larger than the diameter of the wire ( 33 ) which serves to guide the wire ( 33 ) in a straight line between the spool ( 31 ) and the jaws of the tool ( 47 ). There is an upper cylinder attachment rod ( 36 ) which anchors the upper cylinder ( 34 ) to the first body part (here, the only half of the tool body ( 30 ) which is seen), and an upper cylinder spring ( 37 ) which maintains a constant pressure in a downward direction on the upper cylinder ( 34 ). There is a lower cylinder ( 35 ) which is attached to the first body part by a lower cylinder attachment rod ( 48 ). The lower cylinder ( 35 ) has built into it a lower wire guide, (not shown in this figure), which is a semi-circular indentation in the middle of the surface slightly larger than the diameter of the wire ( 33 ) which serves to guide the wire ( 33 ) in a straight line between the spool ( 31 ) and the jaws of the tool ( 47 ). A lower cylinder spring ( 38 ) working in conjunction with a lower cylinder attachment structure ( 48 ) maintains a constant upward pressure on the lower cylinder ( 35 ), thereby restraining the wire ( 33 ) in the grooves on the upper and lower cylinders. Attached to the lower cylinder ( 35 ) is a winding crank ( 39 ) which is turned by a user grasping the winding handle ( 40 ) and turning it, thereby moving the wire either on or off the spool ( 31 ). Moving further down the tool body ( 1 ) away from the spool ( 31 ) there is a lock washer ( 42 ) which serves to attach the tool head ( 44 ) to the tool body ( 30 ). The tool head ( 44 ) slips over the head end ( 41 ) of the tool body ( 30 ). There are two steel balls ( 43 ) located in indentations ( 49 ) in the head end ( 41 ) which fit into a series of grooves ( 45 ) in the tool head ( 44 ), and can turn the tool head ( 44 ) as a user pulls back on the tool body ( 30 ). There is also a lock washer ( 48 ) shown next to the tool head ( 44 ) to show how the inside diameter of the locker washer ( 48 ) is slightly larger than the outside diameter of the tool head ( 44 ), thereby allowing the lock washer ( 48 ) to slide over the tool head ( 44 ) and lock it in place, after the tool head ( 44 ) is slid over the head end ( 41 ) of the tool body ( 30 ).
FIG. 3 is a side view of the invention illustrating how the user can cut and twist wire with the tool. When a user wants to cut the wire ( 76 ), he/she presses in a downward direction ( 60 ) on the lever bar ( 77 ), such motion causing the upper jaw member ( 78 ) to move in a downward direction ( 61 ) to cut the wire. When the user stops putting downward pressure on the lever bar ( 77 ), the lever spring ( 64 ) pushes the lever bar ( 77 ) in an upward direction ( 62 ), thereby causing the upper jaw member ( 78 ) to move in an upward direction ( 63 ), thereby open the jaws. To twist wire, the user first puts the two ends of the wire into the jaws of the tool, and locks the lever bar ( 77 ) in a down position, by pushing it down forcefully such that it locks against the tool, then presses in an upward direction ( 70 ) on the quick release locking mechanism ( 71 ), which causes the lock tab ( 73 ) to move in a downward direction ( 72 ), thereby unlocking the tool head ( 75 ) from the tool body ( 74 ). As the user then pulls back, in a direction illustrated by the number ( 68 ), the steel balls ( 65 ) sit in their indentations ( 66 ) and the tool head ( 75 ) rotates in a direction indicated by number ( 69 ) as the grooves ( 67 ) cause the tool head ( 75 ) to spin around, twisting the wire. When the wire has been twisted to the extent desired, the user unlocks the jaws of the tool by pulling upward on the lever bar ( 77 ), thereby opening the jaws.
FIG. 4 is close-up view of the tool head, showing how the cutting blade ( 91 ) and the cutting slot ( 92 ) can be replaced or removed for sharpening should they become dull.
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A wire twisting tool with a spool assembly, locking mechanism, manual wire feeding mechanism, and cutting jaws is claimed. The tool is designed to quickly and efficiently cut wire and twist it, utilizing a series of matching grooves into which are placed two steel balls which allow the cutting and twisting head portion to rotate about the body portion as the body portion is pulled back by a user.
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FIELD OF THE INVENTION
The present invention relates generally to a lock assembly and more particularly to a lock assembly that is preloadable and may be used to secure multiple different lockable structures.
BACKGROUND OF THE INVENTION
Consumption of electricity is typically monitored through the use of meters that are housed within meter boxes. Such meter boxes are usually locked to prevent access and tampering. In particular, meter boxes are often locked with “tab lock” locking mechanisms.
Moreover, utilities are generally provided to customers through lines that include valves, referred to as “stops” or “cocks.” These valves include a body portion having an inlet and outlet that are separated by a rotatable plug. The plug has a handle or knob that may be rotated to control fluid flow. The valves are secured using a “pad lock” or “cock lock” locking mechanism.
While effective, the aforementioned locking mechanisms are not interchangeable. That is, a tab lock cannot be used to secure a valve and a cock lock cannot be used to lock a meter box. As will be appreciated, this necessitates the manufacture and deployment of two types of locking mechanisms for each application.
Moreover, existing tab locks are not preloadable and require assembly and the use of a key to install them. These limitations are not ideal as it is desirable to reduce the number of keys in the field to prevent loss and theft and to have a tab lock that does not require a key for assembly at the time of installation. Furthermore, it is desirable to have a tab lock that provides an ease of manufacture not presently available with known mechanisms.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a lock assembly.
It is an additional object of the present invention to provide a lock assembly that may be preloaded.
It is an additional object of the present invention to provide a lock assembly that may be used in a variety of applications.
It is an additional object of the present invention to provide a lock assembly that may be easily manufactured.
An embodiment of the present invention is a lock assembly including a body portion having a bore configured to receive a lock. The assembly further includes a blade operably connected to the body portion and a head portion removably securable to the body portion. The head portion has a slot configured to receive the blade when assembled and the head portion also has a through bore to allow insertion of the lock, such that the lock can lock the head portion and the body portion together during installation. The lock assembly may be used to secure multiple different lockable structures.
An additional embodiment of the present invention is a lock system for securing multiple different lockable structures. The system includes a substantially U-shaped body portion having a blade and a bore configured to receive a barrel lock. The system includes a head portion removably securable to the body portion. The head portion has a slot configured to receive the blade and a through bore to allow insertion of the barrel lock, such that, when assembled, the barrel lock can lock the head portion and the body portion together. The bore of said body portion includes an annular channel for partially receiving balls of the barrel lock to selectively hold the lock system in a pre-loaded condition such that a key is unnecessary for installation of the system.
Another embodiment of the invention is a method of securing a lockable structure. The method includes the steps of placing a body portion of a lock assembly in contact with a lockable structure. The method further includes aligning a head portion of the lock assembly with the body portion, the head portion being operatively connected to the body portion through a pre-loaded barrel lock. The barrel lock from a first preloaded position within the body portion to a second locked position within the body portion whereby the lock assembly secures the lockable structure.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a lock assembly in accordance with an embodiment of the present invention.
FIG. 2 is a perspective view of a body portion of the lock assembly of FIG. 1 .
FIG. 3 is a sectioned side view of the body portion of FIG. 2 .
FIG. 4 is a perspective view of a head portion of the lock assembly of FIG. 1 .
FIG. 5 is a sectioned side view of the head portion of FIG. 4 .
FIG. 6 is a side view of a blade portion of the lock assembly of FIG. 1 .
FIG. 7 is a perspective view of the lock assembly of FIG. 1 depicting the assembly is in a preloaded state.
FIG. 8 is a perspective view of the lock assembly of FIG. 1 depicting the assembly mounted on a meter box.
FIG. 9 is a perspective view of the lock assembly of FIG. 1 depicting the assembly mounted to a valve.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1-6 , an embodiment of the present invention includes a lock assembly 10 with a body portion 20 , head portion 30 and blade 40 . In use, the head portion is secured to body portion 20 and the blade 40 protruding from the body portion 20 . A barrel lock 50 is then used to secure the head portion 30 and body portion 20 together. As will be appreciated, the inventive lock assembly 10 may be configured for use with various barrel locks such as, rotating disk and plunger type barrel locks, and, in particular, may be used with the barrel locks described in U.S. Pat. Nos. 5,086,631 and 7,775,071, which are hereby incorporated by reference in their entireties.
More specifically, in one embodiment, the body portion 20 is generally L-shaped and includes a slot 22 configured to receive and retain the blade 40 . The blade 40 may be secured within the slot 22 through a variety of means. For example, the blade 40 may contain an attachment groove or slot 44 ( FIG. 6 ) that could receive correspondingly shaped protrusions within the slot 22 (not shown) to fix the blade 40 in place. Alternatively, the blade 40 and body portion 20 can be unitary and formed from a single piece of material.
The body portion 20 further includes a cylindrical bore 24 for receiving the barrel lock 50 . The bore 24 includes a recess 28 for the balls (not shown) of the barrel lock 50 allowing the barrel lock 50 to be secured within the body portion 20 . The body portion 20 also includes an annular channel 26 that creates a circumferentially enlarged section of the bore 24 . The channel 26 receives the balls of the barrel lock 50 allowing the lock 50 to be “preloaded” within the bore 24 of the body portion 20 .
In particular, the channel 26 is not as deep as the recess 28 and, as such, the balls of the lock 50 can only partially extend into the channel 26 . As such, the channel 26 simply holds the barrel lock 50 within the body portion 20 to facilitate installation. In use, the barrel lock 50 is urged forward within the lock body by an installer which forces the balls out of the channel 26 and into the recess 28 to lock the barrel lock 50 and secure the inventive lock assembly.
As stated, an embodiment of the lock assembly 10 also includes a generally L-shaped head portion 30 . The head portion 30 has a cylindrical through bore 34 that allows the barrel lock 50 to be inserted through the head portion 30 and into the body portion 20 . The through bore 34 includes first section 36 and a second section 38 having a reduced diameter. The first section 36 receives the head of the barrel lock 50 which itself has a larger circumference than the portion of the lock 50 that extends into the bore 24 of the body portion 20 . In particular, the first section 36 encapsulates the head of the barrel lock 50 to protect the lock head from attack. The second section 38 forms a “shoulder” portion, which prevents the passage of the barrel lock 50 through the through bore 34 and removal of the lock assembly. The second section 38 has a diameter that is substantially the same as the diameter of the bore 24
The head portion 30 also features a mounting slot 32 . The mounting slot 32 is configured to receive the blade 40 of the body portion 20 when the inventive lock assembly 10 is assembled. More specifically, the blade 40 extends through the slot 32 allowing a sealing tab 70 to be placed on the blade 40 to provide a visual indicator of whether the assembly 10 has been tampered with. As shown in FIG. 6 , the sealing tab 70 is placed through a tab slot 42 in the blade 40 .
Referring now to FIG. 7 , the head portion 30 is rotatable relative to the body portion 20 when the lock assembly 10 is in a preloaded state, i.e., the barrel lock 50 is in the body portion 20 and its balls are located in annular channel 26 . In this state, the body portion 20 may be placed into a locking position about, for example, a meter box tab, and then the head 30 may be rotated until the slot 32 is aligned with the blade 40 . The barrel lock 50 and head portion 30 are then urged toward the body portion 20 causing the blade 40 to pass through the slot 32 and the balls of the lock 50 enter the recess 28 thereby locking the inventive lock assembly 10 . A security seal may then be placed on the blade 40 .
When assembled, the inventive lock assembly 10 forms a substantially quadrilateral shape with a relatively large central void or space S that is square or rectangular in shape. As will be appreciated, the space S may be made larger or smaller through the sizing of, among other things, the body portion 20 and head portion 30 . The space S is configured such that it allows the inventive lock assembly to be employed in a variety of applications. This versatility is illustrated in FIGS. 8 and 9 , which depict installation on a meter box tab and on a utility valve, respectively.
In particular, FIG. 8 illustrates that the inventive lock assembly 10 can be installed on a meter box. In this specific installation, the meter box is closed such that a first tab 74 protrudes through the cover 72 . A second tab 76 or closure is then rotated until a portion of it protrudes through an opening in the first tab preventing the cover 72 from being opened. The lock assembly 10 is then placed through a opening in the second tab 76 to prevent its rotation out of the opening in the first tab 74 .
Turning now to FIG. 9 , the inventive lock assembly 10 may also be used to secure a valve. This is facilitated, in part, by the space S. As shown, the lock assembly 10 is deployed by aligning an aperture in a valve body portion 90 with an aperture in a rotatable plug portion 80 having a handle or knob that may be rotated to control fluid flow. Once aligned, the blade 40 of the assembly 10 is then placed through the aligned apertures and the assembly 10 may be secured as described above.
In the embodiment described herein, the body portion and head portion may be manufactured from any suitable durable material, e.g., a hardened steel.
Furthermore, while the inventive assembly 10 has been described as being usable with meter boxes and valves, the assembly 10 may also be used for other applications like securing a chain, for example.
An embodiment of the present invention also contemplates a method of securing a lockable structure. The inventive method includes the steps of placing a body portion of a lock assembly in contact with a lockable structure. The method further includes aligning a head portion of the lock assembly with the body portion, the head portion being operatively connected to the body portion through a pre-loaded barrel lock. The barrel lock from a first preloaded position within the body portion to a second locked position within the body portion whereby the lock assembly secures the lockable structure.
It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. While the dimensions and types of materials described herein are intended to define the parameters of the invention, they are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.
In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” “third,” “upper,” “lower,” “bottom,” “top,” “up,” “down,” etc. are used merely as labels, and are not intended to impose numerical or positional requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.
This written description uses examples to disclose several embodiments of the invention, including the best mode, and also to enable any person skilled in the art to practice the embodiments of invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising,” “including,” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property.
Since certain changes may be made in the above-described invention, without departing from the spirit and scope of the invention herein involved, it is intended that all of the subject matter of the above description or shown in the accompanying drawings shall be interpreted merely as examples illustrating the inventive concept herein and shall not be construed as limiting the invention.
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A lock assembly including a body portion having a bore configured to receive a lock. The assembly further includes a blade operably connected to the body portion and a head portion removably securable to the body portion. The head portion has a slot configured to receive the blade when assembled and the head portion also has a through bore to allow insertion of the lock such that the lock can lock the head portion and the body portion together during installation. The lock assembly may be used to secure multiple different lockable structures.
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TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates to dismantling a gas turbine engine, in particular removing the nut connecting the high-pressure rotor to the front bearing in a twin-spool, front-fan turbofan.
PRIOR ART
[0002] A twin-spool, front-fan turbofan comprises two coaxial rotors supported by bearings housed in the hubs of two structural casing elements: referred to in the art as the intermediate casing and the exhaust casing. At the front of the engine, the bearings are mounted in the intermediate casing and, at the rear, one or more bearings are housed in the exhaust casing. In an engine such as the CFM56, the rotating assemblies are thus mounted on five bearings: three at the front and two at the rear. At the front, the fan shaft and the shaft of the low-pressure (LP) rotor are respectively mounted in the two first bearings. The high-pressure (HP) rotor is supported by bearing no.3, downstream of the first two. At the rear, this same HP rotor is supported by an inter-shaft bearing and the shaft of the LP rotor is supported by a bearing mounted in the hub of the exhaust casing.
[0003] After a period of operation, each engine is sent to the workshop for example for a complete overhaul, in which it is entirely dismantled and each part is cleaned, repaired or replaced if necessary. Dismantling comprises several steps, including that of removing the LP turbine module at the rear and then the module formed by the HP spool. The rotor of the HP spool comprises an upstream journal which is retained in bearing no.3 by a connecting nut which must be unscrewed. This operation has a certain degree of difficulty per se due to the relative inaccessibility of this part. The connecting nut is a cylindrical, threaded part which serves to immobilize the upstream end of the journal of the HP rotor with respect to the inner race of the bearing. This nut comprises four teeth cut into the cylindrical wall and is located in the upstream extension of the threaded portion.
[0004] The standard procedure starts with removing the LP module to the rear and extracting the LP shaft, also to the rear. Access to the connecting nut is then possible via the central passage left free by the LP shaft. After putting in place a wedging device, which replaces the bearing which has been removed, and an internal guiding tube, an appropriately shaped tool provided with two retractable lugs at the end of a cylindrical tube is introduced into this passage as far as the nut, then the two lugs are deployed radially such that they engage against two of the four teeth of the connecting nut. As the HP rotor is prevented from rotating by a wedge, turning the tool about its axis allows the nut to be unscrewed.
[0005] This operation is delicate inasmuch as the teeth of the nut must not be damaged and the nut must not be deformed. To that end, the instructions of the engine manufacturer prescribe a maximum torque to be applied.
[0006] If the connecting nut cannot be unscrewed in this way, the procedure then consists in removing the assembly consisting of the fan and the low-pressure (LP) compressor in order to gain access to the nut via the front of the engine. Once this path is open, an appropriately shaped tool is introduced along the axis of the engine as far as the connecting nut. The head of the tool is adapted to the shape of all the teeth of the nut, such that it is possible to apply a larger torque than before and increase the chances of managing to loosen it.
[0007] However, if the connecting nut can still not be removed by this operation, it has to be cut. Cutting the nut, which is not an inexpensive or straightforward solution, is to be avoided as not only must the nut be replaced but there is a risk of the resulting chips and filings contaminating the gearing located in the immediate vicinity, which would require these parts to be removed and cleaned. This gearing, known as the IGB, serves to drive the radial arm connected to the gearbox for the accessories, the AGB.
[0008] With increasing duration or number of operating cycles of the engines, and the use thereof, where relevant, in aggressive environments, it is observed that dismantling now leads more often to the connecting nut being cut due to seizing of the nut.
[0009] Seizing of the connecting nut is due to multiple factors:
coking of the grease resulting from heating of the part, deformation of the nut during loosening, due to the torsion forces generated by the permitted torque limit being exceeded, oxidation of the portions of the nut forming the centering tracks with the journal and the inner race of the rolling bearing.
[0013] The present applicant has set itself the objective of developing a method for dismantling a motor, avoiding as far as possible the need to cut the connecting nut.
DISCLOSURE OF THE INVENTION
[0014] The invention relates to a twin-spool turbofan comprising a front fan, a HP module with a HP rotor and a LP turbine module, the intermediate casing having a bearing for supporting the HP rotor. The HP rotor is retained in the bearing of the intermediate casing by a connecting nut. The method for dismantling the engine comprises a step of introducing a tool for unscrewing the connecting nut once access to the connecting nut has been cleared, and is characterized in that it comprises a step of heating, beforehand, the connecting nut before engaging the unscrewing tool.
[0015] Previous heating to a moderate temperature makes it possible to soften the coked oils gluing together the thread of the connecting nut and that of the journal and also to allow a differential expansion between the cylindrical elements in mutual contact via close-fitting supporting surfaces.
[0016] The temperature must be kept below a safe value for the integrity of the parts present. The maximum heating temperature for an exemplary embodiment of the method is 130° C.
[0017] Preferably, once the LP turbine module, with its shaft, has been removed, a tubular heating means is introduced from behind into the central space left free by the LP turbine module, along the axis of the engine, and the connecting nut is heated from the inside.
[0018] In accordance with another feature, the heating means comprises a tube with a means for blowing hot air in via one end and radial openings at the other end so as to guide the hot air radially toward the connecting nut.
[0019] After heating the nut, a rear unscrewing tool is introduced. The tool preferably comprises a tube and a plurality of fingers which are retractable between a position in which they are housed within the tube, such that the tube can be introduced as far as the nut, and a position in which they are deployed radially so as to come into contact with the teeth of the connecting nut. An unscrewing torque is then applied to the tool, the torque being maintained at a value below that at which the forces on the teeth of the nut would risk damaging them.
[0020] According to another way of effecting the dismantling, either after an unsuccessful attempt via the rear or directly, the fan is removed so as to free up said connecting nut in the forward direction and putting in place a front unscrewing tool for applying a torque for unscrewing the nut. The front unscrewing tool preferably comprises a tubular element which is provided with teeth of a shape complementary with that of the teeth of the connecting nut; the tubular element is put in place on the nut and an unscrewing torque is applied.
[0021] The tubular element is advantageously placed in a support attached to the casing of the engine, said support forming a contact point for applying the unscrewing torque.
[0022] It is also necessary to immobilize the rotor of the HP module. To that end, the LP turbine module having been removed, the HP rotor is prevented from rotating by means of a tubular element which is engaged in the space left free by the LP module and which is attached by one end to the casing of the HP module and at the other end is secured in rotation with the HP rotor. As a safety measure, when resistance to unscrewing is observed, it is ascertained that the connecting nut has not seized, by means of a break-action torque wrench calibrated to the maximum permitted torque.
BRIEF DESCRIPTION OF THE FIGURES
[0023] The method for removing the connecting nut will now be described in more detail, according to one embodiment given by way of non-limiting example, the description being made with reference to the appended drawings, in which:
[0024] FIG. 1 is a representation in axial section of an engine to which the method according to the invention applies;
[0025] FIG. 2 is an axial half-section view showing, in situ, the nut which connects the HP rotor to the front bearing in the intermediate casing and which is to be removed;
[0026] FIG. 3 is a schematic side view of the engine during dismantling;
[0027] FIGS. 4 and 5 represent one embodiment of the device for heating the connecting nut;
[0028] FIGS. 6 , 7 and 8 represent one embodiment of the device for unscrewing the connecting nut, with introduction via the rear, on the turbine side; FIG. 7 is a section through AA in FIG. 6 showing the tooling in the deployed position and FIG. 8 shows the tool in the retracted position;
[0029] FIGS. 9 to 11 show the tooling for unscrewing via the front of the engine, with the support and the tubular key;
[0030] FIG. 12 shows, in isometric section, the tool for preventing the HP rotor from rotating.
DETAILED DESCRIPTION OF THE INVENTION
[0031] The section of FIG. 1 shows a twin-spool, front-fan turbofan 1 . This figure shows, from right to left, that is to say from upstream to downstream in the direction of the gas streams, the rotor of the fan 2 inside the fan casing 2 ′. The fan duct delimited by the casing is split into two concentric annular ducts, one for the primary flow which passes through the engine, the other for the secondary flow which is expelled without having been heated. The primary flow is compressed in the low-pressure boost compressor and then in the HP compressor 3 . It is admitted into the combustion chamber 4 where it is heated by combustion of a fuel. The hot gases issuing therefrom are expanded successively in the HP turbine 5 and the LP turbine 6 before being expelled. The rotors are supported within the two structural casings which are the intermediate casing 7 —the fan casing being attached on the upstream side thereof—and the exhaust casing 8 to the rear.
[0032] The fan 2 with the boost compressor and the LP turbine 6 are connected by a LP turbine shaft 6 ′. The turbine shaft 6 ′ and the turbine 6 with its casing form, with the exhaust casing 8 , the LP turbine module 60 .
[0033] The HP compressor 3 and the HP turbine 5 form the HP rotor 35 inside the HP spool or module 40 . This also comprises the combustion chamber 4 . The HP rotor 35 is mounted at the upstream end in the bearing P 3 which is supported in the hub of the intermediate casing 7 . The gearbox referred to as the IGB, for driving the accessory gearbox (AGB) via a radial shaft housed in an arm of the intermediate casing, is also here.
[0034] FIG. 2 shows this portion of the engine in more detail; the upstream journal of the rotor 35 is housed in the inner race P 3 i of the rolling bearing P 3 via the intermediary of the pinion 9 of the IGB gearing. The connecting screw 20 is screwed at 21 to the end of the rotor 35 and immobilizes the latter axially with respect to the intermediate casing. The connecting nut 20 is therefore a cylindrical part with an inner thread 21 , an outer centering track 23 and teeth 22 in the axial upstream extension of its cylindrical wall.
[0035] Removing the HP module 40 involves, beforehand, removing the LP module 60 so as to free up access to the nut 20 and putting in place a disk 70 for retaining the HP rotor in its casing, thus replacing the inter-shaft bearing. This disk replaces the downstream inter-shaft bearing which has been removed with the LP module 60 . The state of the engine is represented schematically in FIG. 3 . The front portion, comprising the fan casing and the intermediate casing, is secured to a frame and the rear portion which is to be detached from the intermediate casing is the HP module 40 . It is attached to a beam 90 suspended from a hoist.
[0036] The following step involves introducing, into the guiding tube 41 put in place in the central space freed up by the shaft of the LP turbine, the means 100 for heating the nut 20 .
[0037] It comprises a trolley 101 mounted on wheels and having a vertical wall 103 provided with vertical rails 105 guiding a platform 107 which can move vertically. The platform is suspended from a cable which is connected, via a set of pulleys, to a manually operated winch 109 by means of which the height of the platform can be adjusted. The platform 107 supports the heating assembly consisting of a heating unit 110 and a hollow tube 112 . The heating unit is arranged at the proximal end of the tube so as to produce a flow of hot air in the hollow tube 112 , directed toward the other end of the latter. This other end is open laterally with holes 114 cut into the wall of the tube 112 , about the axis of the latter. The heating assembly also comprises a means for siting the tube and wedging it in position when it is introduced into the engine. This means is formed here by two projections 113 on a transverse plate.
[0038] The heating assembly is mounted on the platform via the intermediary of a horizontal rotation spindle 115 such that it is possible to pivot it into a vertical storage position, in which it is stowed in the trolley, or into a horizontal active position. The angular position of the heating assembly is controlled by a handwheel 116 arranged on the side of the trolley. An appropriate mechanism transmits the movement of rotation of the handwheel to the rotation of the heating assembly about the horizontal spindle 115 .
[0039] In order to heat the connecting nut 20 , the trolley is placed facing the engine and in line with the axis thereof, the heating element is brought to horizontal and introduced into the guiding tube 41 until the projections 113 are in abutment in their respective housings created in the retaining disk 70 . The end of the tube is then level with the nut. The heating unit is switched on and the hot air is blown in via holes 114 of the tube toward the connecting nut. The increase in the temperature of the connecting nut is monitored, and must not exceed 130° C. When the temperature is reached, the heating unit is switched off and the trolley is withdrawn and put away.
[0040] The second step concerns unscrewing the nut with introduction of the tooling 200 from the turbine, at the rear, into the guiding tube 41 . To that end, use is made of an unscrewing tooling comprising an unscrewing tube at the end of which are mounted four fingers which can be moved between a retracted position within said tube, allowing the tube to be moved along the inner tubular space 41 , and a deployed position in which they extend radially out from the cylindrical wall of the unscrewing tube. In this latter position, and by applying a rotational torque about the axis of the tube, the four fingers press against a lateral edge of each tooth and transmit the unscrewing forces thereto. By providing a number of fingers which is equal to the number of teeth of the connecting nut, a better distribution of the forces, compared to with only two fingers, is ensured. It follows that a higher torque can be applied, increasing the chances of managing to loosen the nut.
[0041] FIGS. 6 to 8 show a section of a tooling suited to the method. This tooling 200 comprises a tubular element 201 inside which is housed the mechanism for deploying and then retracting the fingers for contact with the teeth of the connecting nut.
[0042] The mechanism for actuating the fingers comprises a disk 210 arranged across the tube, at the end thereof; the disk has four radial grooves 211 arranged in a cross, for housing each of the fingers 212 . These are connected to connecting rods 213 which are articulated to an actuating member 214 , as shown in FIGS. 7 and 8 for two positions of the fingers. By turning the actuating member on itself, about its axis, one way or the other, the fingers are made to adopt, by means of the action of the connecting rods, a retracted or extended position, depending on the direction. The disk 210 is secured to a tubular element 216 surrounding the member 214 for actuating the fingers. The tubular element 216 is secured to a toothed wheel 217 in order to be driven in rotation. The tubular element 201 is arranged so as to be made immobile with respect to the HP module 40 . To that end, it comprises projections which are not shown here and which, as in the means for heating the connecting nut, engage with the retaining disk 70 . At its other end, the tube is provided with pegs 218 which are designed to be engaged in grooves of the HP rotor journal in order to help prevent any rotation of the HP rotor 35 while the loosening torque is applied to the nut. Finally, the tube 201 is associated with vanes 219 which are able to move radially, actuated by the handwheel 222 , and which serve to extract the brake of the nut 20 before loosening.
[0043] An upstream guiding member 220 is also shown in this figure. It is of smaller diameter than the tube 201 and serves to center the tooling 200 via a tooling which is provided to that end and which is mounted on the fan 2 .
[0044] After heating the connecting nut, the tooling is introduced into the central space until the lateral projections, not shown, abut against the device 110 . The disk is then facing the teeth of the nut. The fingers are then deployed radially by means of a determined angular rotation of the control member 223 t . With one or more fingers having a lateral tab, the disk is turned such that the tabs slide into the corresponding grooves created below the teeth.
[0045] In the abutment position, it is known that, at the upstream end of the tube (not shown from the rear), the axial pegs are engaged in the corresponding axial grooves of the inside of the journal of the HP rotor 35 . While still in position and wedged, a torque multiplier, for example that known under the Sweeney brand, is put in place.
[0046] It is ascertained that the connecting nut has not seized, by means of a break-action torque wrench calibrated to the maximum permitted torque. If the wrench yields and folds in two, the maximum permitted torque has been exceeded; the nut is deemed to be stuck, and unscrewing from the front must be attempted. If the wrench does not break, a motor, for example a compressed air motor, is put in place on the torque multiplier and the connecting nut is first loosened and then unscrewed.
[0047] The method for removing the connecting nut from the front involves, first of all, removing the assembly formed by the fan, the boost compressor and the bearings P 1 and P 2 in order to have a direct view of the nut from the front.
[0048] As in the method for removing via the turbine, and in the same manner, the connecting nut is heated beforehand with the aid of the tooling 100 . Then, the front unscrewing tool 300 is put in place on the engine, FIGS. 9 , 10 and 11 . The tool comprises two parts: a key support 310 secured to the casing of the engine, and a tubular key 320 which is able to turn about its axis in the support. The assembly is shown in FIG. 9 . The support 310 comprises four branches 312 which extend in a star shape from a cylindrical stem 311 . The support comprises removable shoes 322 . The operator installs shoes which are appropriate for the type of engine, such that it is possible to attain the correct interfaces for attachment to the casing. The branches and the shoes 322 have at their end holes 313 through which can pass screws for attaching to the intermediate casing. The tubular key 320 is housed in the cylindrical stem such that it is blocked axially but can rotate freely about its axis. The key comprises two circular supporting surfaces 321 which come to place themselves in the corresponding ring 314 . A removable ring 315 closes the space of the groove in the upstream direction so as to lock the key axially in the support. The key comprises, at one end, four teeth 316 of a shape complementary with the teeth 22 of the connecting nut 20 and, at its other end, a pinion 317 for driving it in rotation. The key also comprises a thin ring 323 which serves to push away the brake of the nut 20 before loosening.
[0049] Once the tool 300 has been put in place, a wedging tube 350 , FIG. 12 , is arranged inside the HP rotor so as to prevent it from rotating. This tube comprises a transverse plate with locating projections 353 which come into abutment in corresponding notches in the disk 70 . Pegs 351 , which engage with axial grooves of the HP rotor so as to immobilize the latter, are placed at the end of the tube.
[0050] The operating method comprises the following steps:
[0051] Heating the connecting nut by means of the heating device 100 up to a temperature not exceeding 130° C.
[0052] Putting in place the rear loosening tooling 200 .
[0053] Putting in place a force multiplier on the pinion, for example a device of the Sweeney type.
[0054] Ascertaining that the connecting nut can be loosened by applying a torque lower than the limit permitted by the manufacturer, by means of a break-action torque wrench engaged in the Sweeney force multiplier.
[0055] If the wrench allows the pinion to be rotated without folding, then the connecting nut has not seized and a pneumatic motor is put in place to drive the pinion.
[0056] If the torque wrench indicates that the maximum torque has been exceeded, loosening via the front must be contemplated.
[0057] Heating via the front comprises the following steps:
[0058] Heating the connecting nut by means of the heating device 100 , up to a temperature not exceeding 130° C.
[0059] Putting in place the front loosening tooling 300 .
[0060] Mounting the support 310 onto the intermediate casing and screwing the four branches to the orifices existing therein.
[0061] Introducing the unscrewing key 320 into the stem of the support until the toothed end is engaged between the teeth of the nut.
[0062] Axially locking the key by means of the ring 315 on the support.
[0063] Preventing the HP rotor 35 from rotating, for example by means of a wedging tube 350 provided with wedging pegs.
[0064] Putting in place a force multiplier on the pinion 317 , for example a device of the Sweeney type.
[0065] Ascertaining that the connecting nut can be loosened by applying a torque lower than the limit permitted by the manufacturer, by means of a break-action torque wrench engaged in the Sweeney force multiplier.
[0066] If the wrench allows the pinion to be rotated without folding, then the connecting nut has not seized and a pneumatic motor is put in place to drive the pinion.
[0067] If the torque wrench indicates that the maximum torque has been exceeded, cutting the nut must be contemplated.
[0068] The method of the invention is thus an improvement with respect to the prior art since, with this method, it has been noted that the number of instances of the nut being cut after application of the procedure has been reduced considerably and notably.
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A method for removing a twin-spool turbine including a front fan, a HP module with a HP rotor, and a LP turbine module, an intermediate casing including a support bearing for the HP rotor, the HP rotor being retained in the bearing by a link nut, the method including inserting a tool for unscrewing the link nut after having released access to the link nut, and preheating the link nut before starting the unscrewing tool.
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CROSS-REFERENCES TO RELATED APPLICATIONS
U.S. Patent Application Ser. No. 756,164, entitled DRILL PIPE IDENTIFICATION METHOD AND SYSTEM, filed by Walter A. Gunkel and Robert W. Lybecker on the same date as the present application, U.S. Patent Application Ser. No. 756,215, entitled DRILL PIPE IDENTIFICATION SYSTEM, filed by Edward M. Galle on the same date as the present application.
BACKGROUND OF THE INVENTION
This invention relates to the identification of drill pipe sections employed in a drill string of a borehole drilling system.
In borehole drilling operations, it is desirable to keep track of the position of the drill pipe sections in a drill string and to obtain a record of the service time of each drill pipe section for the purpose of determining fatigue damage. Such information is particularly useful by the contractor in determining the dollar value of the damage occuring to the pipe in drilling a given well and to determine when to downgrade or retire the pipe from service. It is possible to obtain and record this information manually, however, such a technique is time consuming and subject to error.
In a new identification process and system, numbers in binary form, comprising apertures filled with a non-magnetic material, are formed in the outer walls of the drill pipe sections. The numbers are read by a sensor comprising an encircling electrical coil and a detecting element which is rotated around the drill pipe sections as they are moved through the encircling coil.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an apparatus for use in the above mentioned identification system for supporting the detecting element for rotation around the drill pipe section and which takes into account lateral movement of the drill stem which may occur as it is being lowered into or raised from the borehole.
It is a further object of the present invention to provide an apparatus for supporting the detecting element close to the drill pipe stem during reading operations and which moves the detecting element outward to allow drilling or other operations to be carried out.
The apparatus comprises an outer plate means supported for rotation and having an opening in which is located an inner plate also having an opening for receiving the drill stem. Arms couple the inner plate to the outer plate means for rotation therewith and also support the inner plate for lateral movement in the opening of the outer plate means. The detecting element is coupled to the inner plate by an arm which moves the detecting element close to the drill stem for reading purposes. Means also is provided for operating the detecting element arm to move the detecting element outward to allow drilling or other operations to be carried out.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a typical borehole drilling system;
FIG. 2 illustrates an end of a drill pipe identified with a number in binary form and a detecting system comprising an encircling electrical coil and a rotating detecting element for detecting the identification number;
FIG. 3 is a side view of the end of the drill pipe shown in FIG. 2;
FIG. 4 is a cross-sectional view of FIG. 3 taken along the lines 4--4 thereof;
FIG. 5 is a cross-sectional view of the end of the drill pipe of FIG. 2 illustrating the magnetic field generated by the encircling electrical coil of the detecting system of FIG. 2;
FIG. 6 is an enlarged view of the detecting element of the detecting system of FIG. 2 which is rotated around the drill pipe sections in the vicinity of the encircling coil;
FIG. 7 illustrates the system of the present invention for supporting the detecting element of FIG. 6 for rotation;
FIG. 8 is an electrical schematic of a system employed for processing and recording the output signals generated by the detecting element of FIG. 6;
FIG. 9 are timing diagrams useful in understanding the system of FIG. 8; and
FIG. 10 is an electrical schematic of a system for energizing the encircling electrical coil of FIG. 2.
DRILL PIPE IDENTIFICATION PROCESS AND SYSTEM
Referring to FIG. 1, there is shown a conventional rotary drilling rig. Reference numeral 21 designates a derrick located over a borehole 23 that contains surface casing 25, steel drill pipe sectons 27 threaded together to form a drill string, and a drill bit 31.
The drill pipe sections 27 are threaded together with members commonly called "tool-joints". Such jonts are formed by an externally threaded steel tubular member called a "pin" connected to one end of each pipe section and an internally threaded steel tubular member called a "box" connected to the opposite end of each pipe section. In the drawings, a pin connected to the lower end of a pipe section is identified at 27A and a box connected to the upper end of another pipe section is identified at 27B. These joint members may be connected to the ends of the pipe by welding or by threaded connections.
Rotation of the bit 31 is achieved by the engagement of a rotary table 33 with a kelly 35, which is the upper most tubular member of the drill string. The kelly 35 is attached to a swivel 37 which is supported in the derrick 21 by a hook 39, traveling block 41 and cable 43. The cable 43 is attached through pulleys at the top of the derrick (not shown) to the draw works 45, which lifts and lowers the drill string.
As indicated above, it is desirable to identify and maintain a record of each drill pipe section which is employed as part of the drill string. This is accomplished by encoding an identification number on each drill pipe section and reading the numbers as the drill pipe sections preferably are lowered into the borehole as part of the drill string in preparation for drilling operations. Preferably the numbers are encoded on the box member of each pipe section prior to the attachment of the box to the pipe.
Referring to FIGS. 2-4 and 7, the identification numbers are in binary form and comprise symbols 51 formed on the outer perphery of the box member 27B and hence of the drill pipe section 27. The symbols are of two sizes, a smaller size 53 which represents a "0" binary bit and a larger size 55 which represents a "1" binary bit. The bits are located along a circle defined by the outer periphery of the box member 27B and may comprise 12 bits to provide up to 4,095 different serial or identification numbers.
In forming the bits, 12 holes are drilled into the wall of the box member 27B from the outside in a given plane. The holes extend into the wall a short distance but do not extend through the wall. The 12 holes are equally spaced with respect to each other, except that the spacing between the 12th hole and the 1st hole is greater than the equi-distant spacing between all other holes. They are drilled selectively in one or two diameters, such as one-fourth of an inch and one-eighth of an inch. The smaller diameter holes 53A represent a "0" binary bit and the larger diameter holes 55A represent a "1" binary bit. The holes are plugged or filled with a relatively non-magnetic material 56 having a wear resistance at least equal to that of steel and which preserves a smooth surface on the tool joint member 27B. The plugging material may be for example, stainless steel. Thus, the bits formed by the holes with their non-magnetic inserts have a much lower magnetic permeability than that of the steel walls of the drill pipe. Although 12 bits are disclosed, it is to be understood that more or less than 12 bits may be used to provide more or less than 4,095 different serial numbers.
The binary serial number of each individual pipe section may be automatically read as the pipe enters (or leaves) the well by a detecting means or system shown in FIG. 2. This system comprises an electrical coil 61 having an enlarged central opening 63 positioned to receive the drill pipe sections as they are lowered into and raised from the borehole. Also provided is a detecting element 65 which includes a small electrical coil 67 (See FIG. 6) supported to rotate around and in contact with the pipe sections in the vicinity or within the opening 63 of the electrical coil 61. In operation, the electrical coil 61 is energized to generate a magnetic field as illustrated at 71 in FIG. 5. As a pipe section is moved through the coil 61, the magnetic field flows through the wall of the pipe section parallel to the longitudinal axis of the pipe and thus magnetizes the steel pipe. The resulting magnetic flux flows uniformly through the wall of the pipe section except in the area of the encoding holes where a leakage of flux occurs outside of the pipe section because the holes and inserts are non-magnetic and represent an interface to magnetic flux flow. A typical pattern of flux leakage around the holes 53A and 55A is shown at 71A and 71B in FIG. 5.
The shoe 65 is formed of a non-magnetic material such as brass and has the electrical coil 67 embedded therein. As the shoe 65 and hence the coil 67 is rotated in the opening of or within the vicinity of the electrical coil 61, it passes in sequence next to each binary hole as the pipe is moved through the coil 61 and a voltage pulse is induced into the coil 67 by virtue of the coil 67 passing through the magnetic leakage field about each hole. The small diameter holes, representing a "0" bit, induce a voltage pulse into the shoe coil 67 of a particular amplitude and the larger diameter holes, representing a "1" bit, induce a voltage pulse into the coil 67 approximately twice the amplitude of the small hole pulse. Thus, the shoe coil 67 has either a "0" or a "1" amplitude voltage induced into it for each of the holes. The voltage pulses generated thus represent the "0" bits and "1" bits defining a particular binary number encoded on each pipe section. These electrical signals may be removed from the electrical shoe coil 67 by conventional signal retrieval means such as slip rings or FM radio. After retrieval, the signals may be recorded directly on magnetic tape for subsequent analysis and processing. Preferably the signals are processed electronically at the well site to provide a serial number read-out in the desired form. One such circuitry for processing and recording the signals is shown in block diagram in FIG. 8.
Referring now to FIGS. 8 and 9, there will be described the circuitry shown for processing and recording the signals produced by the shoe coil 67. FIG. 9A represents the output of coil 67. The output pulses of the coil 67 occur in two amplitudes 72 and 73 representing "0" and "1" bits. In FIG. 9A, a train of signal pulses are shown at the beginning of the sequence diagram on the left as might occur if the shoe 65 initially comes into the encoded area between the sixth and seventh holes, for example. These six samples do not constitute the full binary count and therefore must be discarded. As seen in FIG. 8, the output of coil 67 is amplified by an amplifier 75. The output of the amplifier 75 actuates a gate 77 which is turned on by the first received pulse from coil 67 and has a time constant long enough to stay on until the next pulse, provided it occurs within the time spacing of the equally spaced holes. The output of the gate 77 is shown in FIG. 9B. After the last signal of the initial train of six signals (or whatever number of signals the initial train has) gate 77 turns off in the absence of an additional signal. A resulting pulse is produced by the gate having a trailing edge 79. The output of gate 77 is differentiated by circuitry 81 to generate a negative pulse when the gate 77 turns off. The negative pulse produced by the circuitry 81 is shown at 83 in FIG. 9C. This pulse turns on a gate 85 whose time constant is set to span the time interval of a full train of twelve pulses which is shown on the right in FIG. 9A. The purpose of this action is to insure that the full series of twelve binary bits are read in sequence. The positive voltage produced by gate 85 is shown at 87 in FIG. 9D. The output of amplifier 75 also is connected to the gate 85 by way of conductor 89. When gate 85 is turned on, it allows the amplified coil signals from amplifier 75 to pass through the gate to a count-to-twelve circuit which, upon counting to twelve and no more or less, activates a circuit to certify that a legitimate reading has occured. The certification circuit may include a light which is turned on for a certain period of time when the exact count-to-twelve has occurred. In addition, the output signals from gate 85 drive a twelve-position shift register 93 and each position of the shift register, in sequence, turns on twelve stages of a binary storage system 95. In this respect, the first pulse from the train of twelve pulses from the shoe 67 turns on the first stage of the shift register 93. The second pulse of the train of twelve pulses from the shoe 67 turns the first stage off, which action turns on the second stage of the shift register 93. The third pulse from twelve pulses from the shoe 67 turns on the third stage of the shift register 93, etc. When a given stage of the shift register is on, the other stages will be off. The outputs of the stages of the shift register 93 are coupled to corresponding stages of the binary storage 95 by way of conductors 97. The output pulses from the twelve stages of the shift register 93 are shown in FIG. 9E.
The output signals from gate 85 also are applied to a delay circuit 99 which delays the signals later in time with respect to the shift register signals. The output of the delay circuit 99 is applied to a window 101 which is in effect a pulse height discriminator. The window 101 differentiates between the low amplitude and the high amplitude signals to generate "0" bit pulses in correct time sequence on conductor 103 and "1" bit signals in correct time sequence on the conductor 105. The signals on conductor 103 are illustrated in FIG. 9F while the signals on conductor 105 are illustrated in FIG. 9G. The time delay of these signals relative to the shift register signals is not illustrated in FIG. 9 because the amount of delay necessary is only about 10 percent of the shift register pulse width and could not be clearly shown in the Figure. The purpose of the time delay is to permit the shift register to fully turn on each binary stage before the application of "0" and "1" bit pulses, in order to be certain the bits are entered uniquely in the correct binary stage. As shown conductor 103 is connected to each stage of the binary storage 95 by way of conductors 107 and conductor 105 is connected to each stage of the binary storage by way of conductors 109. As each of the stages of the shift register 93 are sequentially turned on, each of the stages of the binary storage 95 are sequentially set whereby the binary bit signals on conductors 103 and 105 are appropriately stored in the proper stage of the binary storage 95. Thus, upon shifting to twelve of the shift register 93 the full binary sequence will be stored in the binary storage.
In addition, upon shifting to twelve, the shift register 93 generates a signal which is applied by way of conductor 110 through a delay circuit 111 to activate a read-out circuit 113. The outputs of the twelve stages of the binary storage 95 are connected to the read-out 113 by way of twelve conductors although for purposes of clarity a single conductor 115 is shown. The read-out circuit 113 thus reads the binary numbers stored in the twelve stages of the binary storage and applies them to an appropriate read-out or recording device 117. This device may comprise a binary-to-digital circuit and digital display; a binary-to-digital circuit which is coupled to a tape recorder; a tape recorder for recording the binary data directly on magnetic tape, etc. Simultaneously, the shift to twelve signal applied to delay circuit 111 activates a re-set and inhibit circuit 119 to re-set the shift register and the binary storage stages to zero and to inhibit additional signals from the same pipe section. The connection between the inhibit circuit 119 and the shift register 93 and binary storage 95 are not shown for purposes of clarity. The output of delay circuit 111 is shown in FIG 9H and the output of circuit 119 is shown in FIG. 9I. Additional signals from the same pipe section may be inhibited by applying the output of the inhibit 119 to a circuitry which may be connected to the input of amplifier 75 or of gate 77 to prevent passage, for a predetermined time, of additional pulses from the coil 67 to the circuitry shown.
Circuitry for processing the signals before recording such as that shown in FIG. 8 is preferred since the data recorded is compatible with a computer which may be employed to calculate fatigue damage, cost and other information of the pipe sections. It is not necessary for a computer to be located on the rig, since the data recorded may be processed later through the computer. It is to be understood that circuit arrangements different from that shown in FIG. 8 may be employed to process and record the signals from the shoe coil 67.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 7, there will be described the system of the present invention for supporting the detecting shoe 65 and its electrical coil 61 for rotation around the drill pipe sections. The system of FIG. 7 comprises an annular support plate 131 which is fixed to the floor under the rotary table. The central opening of the annular support plate 131 is relatively large and is located to allow the pipe sections to pass through the opening when they are being raised from or lowered into the borehole. The support plate 131 is shown connected to two arms 133 which are in turn connected to the rig to properly locate the support plate. Plate 131 supports two plates 135 and 137 for rotation. Each of plates 135 and 137 is annular in shape and has a central opening slightly less than the opening of the support plate 131. Plate 135 has a horizontal portion 139 and a vertical portion 141 whereby the plate 135 is L-shaped in cross-section. Both of plates 135 and 137 are fixedly connected together (by means not shown) whereby plate 137 is spaced upwardly from plate 135. Bearings 143 support plate 135 and hence plate 137 for rotation relative to support plate 131. The plates are rotated by a motor 145, connected to one of the arms 133, and a belt 147 which fits into a groove 149 formed in the exterior of vertical portion 141 of plate 135.
A smaller diameter plate 151 is supported within the openings of plates 135 and 137. Inner plate 151 is supported by way of three radially extending arms located 120° apart. Only two arms 153 and 155 are shown. These arms ride in the space 150 between the plates 135 and 137 and hence support the plate 151 within the openings of the plates 135 and 137. Plate 151 is annular shaped and has a central opening 157 large enough to receive the drill pipe sections 27 as they are inserted into or removed from the well bore. The openings of plates 135 and 137 are large enough to allow the plate 151 to move laterally therein. Arm 153 has an elongated slot 161 formed therein. A pin 163 is fixedly attached between plates 135 and 137 and is fitted within the slot 161. A roller 165 surrounds the pin 163. Thus, as the outer plates 135 and 137 rotate, the pin 163 and roller 165 fitted within the slot 161 of arm 153 cause the arm 153 and hence the inner plate 151 to rotate with the outer plates as they are rotated by the motor 145 and belt 147. The pin 163 and roller 165 fitted within the slot 161 of the arm 153 also allow the inner plate 151 to translate and pivot about the pin 163 and hence move laterally within the openings of the outer plates 135 and 137 as they rotate. This arrangement allows the inner plate 151 to remain concentric with the drill stem or string as it moves through the opening 157 of the inner plate 151 and in the event that the drill string also moves laterally while moving downward or upward. A bearing 167 is fitted within an aperture 169 of the arm 155 for engagement with the upper surface of plate 135 to allow the arm 155 to move freely. A similar bearing is formed on the outer end of the third arm.
Pivotally attached to the inner plate 151 are three pairs of arms which support three shoes 65 for rotation around the drill pipe sections as they are moved through the opening 157 of inner plate 151. The three pairs of arms are located 120° apart. Only two pairs of arms 171 and 173 supporting two shoes 65 are shown. Three pairs of arms and three shoes are provided for balance purposes. One or two of the shoes may be dummy shoes with the third shoe having the detecting coil 67 embedded therein for reading the binary coded identification numbers on each of the pipe sections as described above. In the alternative, two or all three of the shoes may employ detecting coils 67 to obtain two or three records of the binary coded identification number of each pipe section for comparison purposes to insure accuracy of reading the identification numbers. In FIG. 7, the shoe on the left is a dummy shoe while the shoe on the right has the coil 67 embedded therein for reading the identification numbers. The two ends of the coil 67 are connected to conductors 175 and 177 which in turn are connected to slip rings 179 and 181 supported by the vertical portion 141 of the outer plate 135. Brushes, now shown, are employed to take the signals off of slip rings 179 and 181 and apply the signals by way of conductors to the recording system located on the rig.
Since both paits of arms 171 and 173 are identical and operate in the same manner, only the pair of arms 173 will be described in detail. This pair of arms comprises an elongated arm 191 and a shorter arm 193. Arm 191 has its inner end pivotally connected to the top of the shoe 65 by way of a pivot pin 195. An intermediate portion of the arm 191 is pivotally connected to the inner plate 151 by way of a pivot pin 197. The outer end of the arm 191 has a roller 199 connected thereto and which is adapted to engage an outer beveled plate 201 which has a central opening which coincides with the central openings of plates 135 and 137. As shown the upper surface of plate 201 defines an inverted, hollow, truncated cone. Connected between the arm 191 and the arm 155 of the inner plate 151 is a spring 200 which urges the inner end of arm 191 upward and the outer end of arm 191 downward. The lower arm 193 has its inner end pivotally connected to the shoe 65 by way of a pivot pin 203 and its outer end pivotally connected to two support tabs 205 by way of a pivot pin 207. The tabs 205 are connected to the lower end of the inner plate 151. Two hydraulic cylinders 209, attached to arms 133, have their pistons 211 connected to opposite edges of the plate 201 to move the plate to an upper position or to a lower position.
While the identification numbers of the pipe sections are being read, the beveled plate 201 is located at its lower position where its upward surface is out of engagement with the rollers 199 to allow the pivoting arms 191 urged by the springs 200, to bring the shoes 65 into contact with the drill pipe as it is being lowered into the borehole. Plate 201 is moved to this lower portion by proper actuation of cylinders 209. During reading operations plates 135 and 137 are rotated to rotate the inner plate 151 and its shoe support arms and hence the shoes 65 around the drill pipe. During drillng operations or when large or irregularly shaped pieces are lowered into the borehole, the shoes 65 are retracted to move them outward to allow sufficient space for drilling operations to take place or for large or irregularly shaped pieces to be lowered into the borehole. During this time, rotation of the shoes 65 is terminated. Retraction is accomplished by actuating the cylinders 209 to move the beveled plate 201 upward to engage the rollers 199 to move the outer ends of arms 191 upward which causes the inner ends of the arms 191 and hence the shoes 65 to be moved outward.
Attached to the upper ends of the shoes 65 are flexible guide members 215 for guiding the drill pipe sections through the shoe 65. Although not shown, small rollers may be attached to the inner surfaces of the shoes 65 to reduce their sliding contact with the drill pipe sections and thereby increasing their service life. The components including the inner plate 151 and the shoe supporting arms 191 and 193 may be formed of a non-magnetic material such as brass. The plates 135, 137 and 201 also may be formed of non-magnetic material.
The coil 61 may be supported in place by the support arms 133. It may be located below the plate 131 close to the shoes 65. The shoes 65 and their coils 67 are relatively long and may extend down into the opening of the coil 61 when the shoes 65 are in their reading positions.
Referring to FIG. 10, when it is desired to energize coil 61 for reading purposes, a switch illustrated at 221 will be closed to connect the coil with a source of voltage shown at 223. Although not shown a source of voltage will be connected to the leads 145A of the electric motor 145 with a control switch connected in one of the leads to turn the motor on or off.
In operation, for reading purposes, the cylinders 209 will be actuated to move the plate 201 to its lower position to allow the springs 200 to move the shoes inward against the drill pipe. As the drill pipe is moved through the opening 157 of plate 151, coil 61 will be energized and motor 145 actuated to rotate the shoes 65 around the drill pipe. In order to carry out drilling operations or to lower large pieces of equipment into the borehole, coil 61 will be de-energized and motor 145 stopped to terminate rotation of shoes 65. In addition, cylinders 209 will be actuated to move the plate 201 to its upward position to move the shoes 65 outward.
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An apparatus for supporting a detecting shoe of a sensor for rotation around a drill pipe stem for detecting identification numbers encoded on the drill pipe sections of the stem as they are lowered into a borehole. The apparatus comprises an outer plate means supported for rotation and having an opening in which is located an inner plate also having an opening for receiving the drill stem. Arms couple the inner plate to the outer plate means for rotation therewith and also support the inner plate for lateral movement in the opening of the outer plate means. The detecting shoe is coupled to the inner plate by an arm which moves the shoe against the drill stem for reading purposes. Means also is provided for operating the shoe arm to move the shoe outward to allow drilling or other operations to be carried out.
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BACKGROUND OF THE INVENTION
1. Field of Invention
This invention pertains to earth boring and more particularly to drill directing apparatus.
2. Description of Prior Art
It is known to drill a hole in the earth with a rotating bit. In such drilling the bit may be loaded axially either by the weight of the drill stem to which the bit is connected or by application of fluid pressure to a piston or cylinder connected to the drill stem anywhere along its length between the bit and the mouth of the hole. The bit can be rotated by a motor connected to the drill stem anywhere between its inner end adjacent the bit and its other or outer end, which may be out of the hole at the earth's surface. It is known to guide the bit to cause the hole to be bored in any desired direction. For example, in U.S. Pat. Nos. 3,298,449 to Bachman et al; 3,326,305 to Garrett et al; and 3,460,639 to Garrett there is shown a bit deflection barrel around the drill stem and through which the drill stem moves axially as drilling proceeds, the drill stem being turned by an out of the hole motor. U.S. Pat. No. 2,637,527 to Andrews shows a deflection and force application barrel about a drill stem projectable into the hole as drilling proceeds and carrying an in-hole motor between the barrel and stem. See also U.S. Pat. No. 3,023,821, issued Mar. 6, 1962 to W. H. Etherington. Instead of fixing the barrel in the hole and drilling through it, it is also known to provide bit deflection means affixed to the bit or to the drill stem adjacent the bit, such deflection means moving axially in the hole as the bit proceeds.
To take the reaction force of an inhole bit loading device, an in-hole motor or a bit directing device, it is known to provide anchor means to engage the wall of the hole being drilled. This is shown, for example, in U.S. Pat. No. 556,718, to Semmer which also shows means for advancing an in-hole motor and bit loading device along the hole as it is drilled. Another example of such anchor means is the construction shown in U.S. Pat. No. 2,946,578, to DeSmaele. See also U.S. Pat. Nos. 3,088,532, 3,105,561, to Kellner; U.S. Pat. Nos. 3,180,436, 3,180,437, to Kellner et al; U.S. Pat. No. 3,225,844, to Roberts; and U.S. Pat. No. 3,561,549, to Garrison et al.
It is also known in the art to orient the pipe from outside the hole as in U.S. Pat. No. 3,561,549 to Garrison et al.
It is also known in the art to transmit electrical data from the hole to the surface, including the use of special pipe to transmit hydraulic fluid and electrical signals.
It is also known to mount two or three pipes concentrically with supports and including various types of expansion joints.
It is also known to centralize or prevent skewing by the drill bit in the hole. See U.S. Pat. No. 3,088.532, issued May 7, 1963, to J. M. Kellner and U.S. Pat. No. 3,561,549, issued Feb. 9, 1971, to E. P. Garrison et al.
SUMMARY OF THE INVENTION
According to the invention, a deflection barrel is disposed about and fixedly attached to the housing of an in-hole bit driving motor. The barrel is free to be turned within the hole to the desired azimuthal position about the center line of the hole. The barrel is connected to a string of pipe, connected at its outer end to an out-hole orientation and axial force application means for turning the barrel as desired relative to the hole and applying axial force to the bit, and supplying fluid to drive the motor and carry away the detritus. In-hole orientation responsive transmitter means and other hole characteristic responsive transmitters which provide means to give a remote indication of the barrel orientation and hole characteristics provide signals which are transmitted by electrical cable mounted within a hydraulic line inside the pipe string. A hydo electric triple swivel is connected mechanically to the outer end of the pipe string, provides means for connecting stationary out-hole fluid and electric conduits to the conduits in the pipe string independent of the orientation of the pipe string. The hydraulic and electric conduits are supported within the pipe string by shock mounts fixedly attached to the hydraulic conduit. Instruments out of the hole can be used to indicate the hole characteristics and barrel orientation. The hydraulic line supplies fluid to actuate wall engaging shoes in the deflection barrel. A sub between the motor shaft and bit carries means to limit rate of change of hole direction.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevation largely in section, showing a drill bit connected to a rate of direction change limiter according to the invention;
FIGS. 2 through 5 together form a view partly in elevation and partly in section showing an apparatus embodying the invention;
FIGS. 6 through 8 are transverse sections taken through the apparatus shown in FIGS. 2 through 5 at the indicated planes,
FIGS. 9 and 10 are schematic views of a rig constituting the out hole force applicator and azimuthal orientation apparatus for turning the pipe string and applying axial force thereto.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A. GENERAL
Referring now generally to FIGS. 1 through 5, there is shown a drill bit 21 connected by sub 63 to the shaft 23 of an in-hole motor 25. The motor is connected to an instrument package 27 supplied with electrical connections by electrical conduit 28. The motor and drill bit are suplied with fluid through fluid passage or conductor 29 provided by a string of pipe sections 32. Motor 25 is of the fluid turbine type including shaft 23 and housing 31. Fluid for operating the motor and carrying away the drill bit cuttings is supplied via tubular shaft 23 fed by conductor 29. Axial force to the motor housing 31 is supplied by the drilling rig (see also FIGS. 9-10) acting on the string of pipes 32 to which it is attached by connector 30. Rig 37 also takes the reaction torque of the in-hole motor 25. Devices supplying axial hole force are known in the art and a typical example thereof is disclosed in U.S. Pat. No. 3,463,252, issued Aug. 26, 1969, to C. E. Miller et al. The axial force on motor housing 31 is transmitted by thrust bearings (not shown) to motor shaft 23 and thus to bit 21.
To direct the drill bit a deflection barrel 41 is provided around the motor 25, the barrel 41 being provided with asymetrically disposed wall engaging means 81, 83 (shoes) to urge the motor and bit to one side of the hole. The wall engaging means 81, 83 are adapted to slide longitudinally along the hole as drilling proceeds. The barrel is rotatable with the motor housing to the desired position by means of connector 30 actuated by the drilling rig 37 through the rigid pipe connections 32.
The rate that deflection barrel 41 can change hole direction is limited by a rotating rate of change limiter 24 fixedly mounted on sub 63 which connects bit 21 to motor shaft 23.
It will be understood that the invention is designed for use in drilling more or less horizontal holes or holes having at least a horizontal component, so that devices such as gravity actuated mercury potentiometers, pendulums or other devices well known in the art may provide an indication of the azimuthal position of the barrel deflection means 81, 83 relative to the hole axis.
B. RATE OF CHANGE LIMITER
Referring now to FIGS. 1, 2 and 3, there is shown drill bit 21 having a pin 61 screwed into box 62 of sub 63. Box 62 has a rate of change limiter 24 comprising body 35 and fins 33 affixed thereto. The outer diameter of rate of change limiter 24 is less than the diameter of the bore 66 with the difference in diameters controlling the rate of change of the hole direction with bigger differences permitting faster changes in hole direction. Sub 63 has its other end 64 screwed onto the inner end 65 of motor shaft 23. Heavy, radial load, roller bearings 67 (see also FIG. 7) lie between outer end 64 and cuff 69 which is screwed to the inner end 71 of the deflection barrel 41.
C. DEFLECTION BARREL
Barrel 41 is sealed to motor housing 31 by annular elastomeric seal ring 73 disposed in an annular groove 75 in barrel end 71. Motor housing 31 is attached by shouldered screw connection 76 to deflection barrel 41. Referring also to FIG. 8, two windows 77, 79 in the barrel receive hole wall engaging blocks or pistons 81, 83. Between the pistons and the windows is disposed elastomeric mounting means 86 for sealingly mounting the pistons in the windows and which allows the pistons to be moved outwardly by pressure differential to engage the wall of hole or bore 66, as shown in dotted lines, and which retracts the pistons from wall engaging position, as shown in solid lines.
Fluid for pushing pistons 81, 83 outwardly is conveyed to the slight annular clearance between elastomeric sleeve 89, integral with means 86, and motor housing 31, by annular groove 93 in the sleeve. Fluid is supplied to groove 93 by longitudinal channel 95 cut into deflection barrel 41.
D. INSTRUMENT PACKAGE
Referring now to FIGS. 3 and 4, instrument package or tube 27 is connected by shouldered and threaded connection 94 to deflection barrel 41 and by similar connection 115 to pipe section 37. Tube 27 is provided with a tapered shoulder 30 facing the out-of-hole end of the package. An instrument container in the form of a hollow cylinder 116 is coaxially disposed inside tube 27. The in-hole end of cylinder 116 is closed by bulkhead 103, which is beveled at 96, and the bevel is provided with azimuthally spaced ribs 105 which rest against shoulder 30. The other end of cylinder 116 is closed by a screw plug 141 and sealed by seal ring 112. Screw plug 141 is provided with azimuthally spaced ribs 142. A threaded ring 144 secured to the outer ends of ribs 142 is screwed into the threaded box 98 of connection 115. Cylinder 116 is thus held in place within tube 28. The outer diameter of cylinder 116 is smaller than the inner diameter of tube 27 forming an annular fluid passage or channel 106 therebetween communicating through the flow passages formed between the ribs 105 and between the ribs 142 with the spaces inside tube 28 at the ends of the cylinder.
Axially extending through instrument container 116 is a tubular conduit 97 forming hydraulic channel 100. The conduit is sealed by seal rings 110 and 114 to inner bulkhead 103 and the outer bulkhead formed by plug 141. Conduit 97 is telescopically connected by tube or channel 104 to longitudinal channel 95 in barrel 41. Seal 101 keeps channels 100, 104 in fluid tight flow communication. Spider 102 connects longitudinal channel 104 to deflection barrel 41 and supports it to maintain proper alignment for telescopic connection. Spider 102 contains flow channels between its ribs to permit fluid flow between longitudinal drilling fluid channel 106 and flow channel 108. Flow channel 108 is formed at the entrance to motor shaft 23 to supply fluid from channel 105 via tubular pin 76 in motor stator 109 for powering motor 25 and for flowing through drill bit 21 to wash chips away for return through the annulus between the drill pipe and hole 66.
Instrument container 116 contains instruments (not shown) for determining tool position with relation to the edge of a coal or other mineral seam e.g. as shown in U.S. Pat. No. 3,823,787 to Haworth, so that the tool can be kept in the center of the seam, or for determining the direction and inclination of the hole, such as a three axis magnetometer or a compass and inclinometer known in the art of oil well surveying, whereby the hole can be kept straight or in other manner directed as desired. If desired, both types of hole responsive instruments can be used in the container. In any event the container will also include means for determining the azimuthal position of the deflection barrel, such as the mercury potentiometer described in co-pending U.S. application of Jackson M Kellner Ser. No. 584,736 filed June 9, 1975, entitled Drill Director.
E. INSTRUMENT PACKAGE CONNECTION TO PIPE SECTION
Referring now to FIG. 4, instrument package 27 is connected by threaded and shouldered connection 115 with pipe section 32 forming part of a string of pipe extending to out-of-hole drill rig 37. Section 32 is the same as all of the other pipe sections 32 of the pipe string so that only one need be described, as will be done in more detail hereinafter. As many pipe sections 32 are used as necessary to extend the pipe string from instrument package 27 to the mouth of the hole.
The instruments in instrument container 116 terminate in conductor means 118. Conductor means 118 includes a cable bundle of conductors 120 surrounded, insulated and sealed by rubber 124. Conductor means 118 extends radially through the side of tube 100 and into a position coaxial within hydraulic channel or tube 100 and is held concentrically therein by mount 119, leaving flow annulus 121 for flow of hydraulic fluid. Conductors 120 terminate in female banana connector 122. Female electrical connector 122 extends beyond the pin end 123 of tube 100 that extends out from screw plug 140 of the instrument container. Electric connector 122 and pin 123 of the hydralic tube are adapted to mate with correlation members on the adjacent one of pipe sections 32.
F. PIPE SECTION
Each pipe section 32 includes an outer tube 125 having a cylindrically threaded pin 126 at one end and a cylindrically threaded box 127 at the other end for making rotary shouldered connections with correlative members on adjacent pipe sections. For details of rotary shouldered connections see U.S. Pat. No. 3,754,609 to W. R. Garrett. Near its pin end the outer tube has an internal, tapered shoulder 128 facing toward its outer end. An other tube 129, providing a continuation of hydraulic fluid channel or tube 100, is disposed concentrically within outer tube 125 and is positioned centrally and axially by spiders 130 and 131. Spider 130 includes a disc 132 having a bevelled outer periphery 133 adapted to seat on shoulder 128. Disc 132 is provided with a plurality of fluid passages or ports 135. The inner periphery of disc 130 is secured to the outer periphery of tube 129 by a resilient sleeve 138. Sleeve 138 has a lower modulus of elasticity than that of tubes 125, 129, and disc 130, which typically are made of metal, usually steel. Preferably sleeve 138 has an elastic modulus of between 100,000 and 250,000 pounds per square inch. Sleeve 128 is preferably made of rubber or other elastomeric material having a durometer hardness of between 40 and 90 on the Shore A scale. Spider 131 at the out hole end of pipe section 32 includes threaded ring 145 rigidly mounted to hub 147 by azimuthally spaced ribs 149 leaving fluid passages between the ribs. Hub 147 fits snugly over a terminal portion 123 of the pipe section 32 and is welded thereto. Tube 129 is assembled within tube 125 by inserting it through box 127 until bevel 133 seats against shoulder 128, this being accomplished finally by rotation, to screw ring 195 into box 127. Alternatively ring 195 could be unthreaded, slipped into box 127, and welded thereto. Elastomeric sleeve 138 allows for relative rotation, turning or twisting, and elongation and contraction between outer tube 125 and the other tube 129. If this is insufficient, spider 131 can be constructed with an elastomeric portion the same as spider 132. Sleeve 138 provides also a damper for torsional and axial vibrations.
Within tube 129 is disposed an inner tube 151. Tube 151 has fins 153 secured to its outer periphery and to the inner periphery of intermediate tube 129, e.g. by epoxy cement. An annular fluid passage is thus formed between the intermediate and inner tubes, the space between the fins providing fluid passages from one side of the fins to the other. A box 155 on the in-hole end of the intermediate tube 129 telescopically receives pin 123 on the end of tube 100 in the instrument package or a like pin 123 on the end of tube 129 of another pipe section 32. A seal ring 157 received in a groove in box 155 seals with pin 123 while allowing relative rotation and relative axial motion, there being no shoulder or end engagement between the pin and box to prevent such axial motion, there being instead clearance at 159, 161 when connection 115 is made up tight.
Electric conduit or cable 28 extends axially through inner tube 129, being insulated therefrom by rubber sleeve 163, the same as cable 118 is insulated by rubber sleeve 124. The rubber sleeve fits tight enough in tube 129 to retain cable 118 therein. At the in-hole end of cable 28 there is a pin connector 165 adapted to connect with box connector 122 at the end of cable 118 or at the end of a like connector on the out hole end of another pipe section 32. An extension 167 of the rubber insulation around box 122 has an internal groove 169 adapted to snap over an annular rib 171 at the base of pin 165 to keep the electrical connection together. This snap together occurs as the threaded connection 115 on the outer tube is made up tight. A connection of this type is known as a bulkhead connection, one form of which is available from Vector Manufacturing Company, Houston, Texas.
It will be noted that inner tube 129 terminates short of the end of the rubber sleeve 163 at the out hole end of the sleeve, leaving the thickened end of the sleeve externally unsupported. This allows for rubber flow sufficient to permit twisting and axial motion of pin 165 relative to box 122.
G. SWIVEL
Pipe sections 32 may be strung for thousands of feet and terminate at interface section 150 (FIG. 5) whose out-hole end provides the outermost stem 152 of hydraulic pneumatic triple swivel 154. Swivel 154 includes a body 163 within which stem 152 is rotatably received. Swivel body 163 includes channel 156 in fluid tight flow communication with annular chamber 162, the latter being sealed by seals 158, 160. Port 164 in body 163 connects chamber 162 with a pipe 163 leading to drill fluid pump 166. A block 170 closing the end of stem 162 includes channel 168. Channel 168 permits fluid tight flow communication between socket 174, into which pin 172 on intermediate stem 175 of the swivel is screwed, and annular chamber 176 of swivel body 163. Chamber 176 is sealed by seals 160 and 178. It is connected by pipe 180 with hydraulic fluid source 182.
Block 170 has a smooth socket 183 receiving the out-hole end of inner stem 185 within which is disposed a continuation of electric cable 28. A radial passage 187 in block 170 receives electrical conductor riser 189, electrically coupling conductor cable 28 with electrical pick-offs 184 of swivel connector 154. Electrical pick-offs 184 are sealed by seals 178 and 186 and include springs 188 engaging pick-off wires 190 to annular slip ring terminals 194 of electrical conductor coupling riser 182. Wires 190 are terminated at electrical power and data transmission apparatus 196 which includes indicators and controls. Thrust bearings 198 permit terminating stem 152 to be rotatably engaged within body 163. The space surrounding bearings 198 is sealed by seals 158 and 200. Block 170 terminates at screw coupling 30 which connects to drill rig 37 to be rotated to position pistons 81, 83 azimuthally relative to the hole while leaving swivel body 163 in a fixed position.
Intermediate stem 175 is supported within outer stem 152 by spider 202 affixed to the intermediate stem and slipped into the outer stem, being otherwise similar to spider 31. The in-hole ends of the swivel stems terminate in threaded, telescopic, and bulkhead connections the same as on pipe sections 32, thereby to connect the swivel stems with the pipe sections. The annulus between the outer and inner stem provides a flow passage communicating with the flow passage between the outer and intermediate tubes of the pipe sections, the annulus between the intermediate and inner sleeve providing a flow passage communicates with the flow passage between the intermediate and inner tubes of the pipe sections, and the electric cable in the inner stem connecting to the electric cable in the inner tube of the pipe sections.
H. DRILL RIG
Referring now to FIGS. 9 and 10, there is shown the out-hole apparatus or rig 37 for turning the pipe string azimuthally about its axis as may be desired to position the deflection barrel and for advancing and retracting the pipe string axially in the hole as may be desired, e.g. for loading the drill bit axially or for withdrawing the drill string in whole or in part to change bits or add pipe sections or to commence or discontinue drilling. Rig 37 includes a frame 251 to be anchored to the earth or having sufficient weight to hold it in place. Mounted on the frame are tracks 253 having downwardly facing rack teeth 255. A movable chassis 257 has slides 259 resting on tracks 253. On the lower part of the chassis are mounted hydraulic motors 261 driving pinions 263. The pinion engage racks 253 so that when the motors are rotated the chassis 257 is driven forward or backwards along the tracks.
On top of the chassis 257 is disposed a gear box 265 driven by hydraulic motor 267. The output shaft 269 of the gear box is screwed to pin 30 on the out-hole end of the outermost stem 150 of the swival 154 (see also FIG. 5). The pin on the in-hole end of swivel stem 150 is connected to the box of the outer tube of the adjacent pipe section 32. When motor 267 drives the gear box, the string of pipe sections 32 is turned azimuthally about is axis.
I. OPERATION
During drilling motor 31 turns bit 21 to bore hole 66. Instruments in container 116 transmit signals out of the hole via cable to tell the operator if the hole is going in the desired direction. If not, the string of pipes 32 is turned by rig 37 through swivel stem 152 until deflection barrel 41 is in an azimuthal position that will redirect the bit in the proper direction. The azimuthal position of the barrel is known from electric signals transmitted out of the hole via cable 28. When the hole is going in the right direction, the deflection barrel may be deactivated by reducing the pressure therein, allowing the deflection pistons or shoes to retract.
J. MODIFICATIONS
Although the system as described above in detail is believed to be most satisfactory and preferred, different applications and many variations in its elements and the structure of its elements are possible. For example, an electric in-hole motor may be used. Moreover, out-hole torque detection means may be employed to detect the contacting of the rate of change limiter 24 with the hole which would indicate the desirability of letting off pressure on deflection pistons 81, 83.
The above are, of course, merely exemplary of the possible changes and variations.
Because many varying and different embodiments may be made within the scope of the inventive concept herein taught, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirements of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.
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The housing of an in-hole drill motor is provided with a deflection barrel to apply lateral force to the side of the housing directed along any desired radius. The barrel is fixedly attached to a pipe string and the motor is fixedly attached to the barrel inside the barrel. The barrel is oriented and axial force is applied to the motor housing through the pipe string from without the hole, using orientation and other signals transmitted from within the hole adjacent the motor. The signals are transmitted through an electrical conduit housed within a hydraulic conduit used to supply fluid to expand the deflection barrel shoes. The hydraulic and electric conduits are supported within the pipe string by shock mounts fixedly attached to the hydraulic conduit. The annulus between the hydraulic conduit and the pipe string provides means to transmit fluid for driving the motor and removing the detritus formed by a drill bit driven by the motor. The out-of-hole connections to the pipe string annulus and the hydraulic and electric conduits are made through a hydro-electric triple swivel. A rate of direction change limiting mechanism mounted between the bit and the barrel for rotation with the bit prevents the deflection barrel from changing hole direction too rapidly. Instruments out of the hole can be used to indicate the hole characteristics detected in the hole.
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FIELD OF THE INVENTION
A machine tool has a closed force loop design, a fixed bifurcated Y-axis column, and a Z-slide design that optimizes the consistency of the rigidity of the machine.
BACKGROUND OF THE INVENTION
A plate mill is a type of machine tool that is used to machine large flat workpieces having a substantial length and width, but relatively little height. Because the workpiece is large, the plate mill itself is relatively large, and in large machines, rigidity and the ability to resist deformation during operation are important design considerations. In machine tools that use a Z-axis ram, it is important to keep the center of gravity of the ram as close as possible to the suspension points for the ram to minimize the effects of acceleration forces that occur during machine operation. It is also important in high performance machines that the rigidity of the machine remain as constant as possible throughout the working envelope of the machine. This allows for optimal process parameters to be utilized throughout the envelope instead of having to vary the process parameters depending on workpiece location in the workzone. In high speed machining there are stability lobes where based on the cutter tooth pass frequency and the rigidity of the system greater metal removal rates can be achieved without chatter. These stability lobes exist in fairly narrow ranges and changes in system stiffness within the work envelope can cause parameters that allow chatter free cutting in one area to cause chatter in another.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
FIG. 1 is a perspective view of a machine tool according to the invention.
FIG. 2 is a simplified view of the X, Y, and Z-axis elements of the machine tool of FIG. 1 .
FIG. 3 is a sectional view of the machine tool taken along lines 3 - 3 of FIG. 1 .
FIG. 4 is a side sectional view of the machine tool taken along lines 4 - 4 of FIG. 1 .
FIGS. 5 and 6 are graphical drawings showing a conventional suspension system for a Z-axis ram and the resulting load path.
FIGS. 7 and 8 are graphical drawings showing the C-axis droop for the Z-axis ram of FIGS. 5 and 6 .
FIGS. 9 and 10 are graphical drawings showing a suspension system for a Z-axis slide with a front mounted saddle and the resulting load path.
FIGS. 11 and 12 are graphical drawings showing a suspension system for a Z axis slide with a middle mounted saddle and the resulting load path.
FIGS. 13 and 14 are graphical drawings showing the C-axis droop for the Z-axis slide of FIGS. 11 and 12 .
BRIEF SUMMARY OF THE INVENTION
The frame of a machine tool is configured to form a closed force loop design that surrounds a workzone containing the spindle head. The front of the loop comprises a fixed Y-axis bifurcated column and the back of the loop comprises a fixed X-axis frame. The top and bottom of the loop is formed by structural tubes that tie the Y-axis column and the X-axis frame together. A pallet receiver that supports the workpiece is mounted to move on X-axis rails. A vertically movable saddle is mounted near the center of Z-axis stroke on the Y-axis column and carries a Z-axis slide. The support of the saddle on the Y-axis column and of the Z-axis slide on the saddle maintains the load path for the working tool relatively constant throughout its stroke, and adds to the rigidity of the machine.
The X, Y, and Z-axis drive motors are all mounted outside of the workzone. The X-axis drive is mounted on a fixed wall that is attached to an X-axis frame member. The Y-axis drive is mounted on the fixed Y-axis column on the side of the Y-axis column that is opposite the workzone. The Z-axis drive is mounted on a saddle on the opposite side of the Y-axis column from the workzone. The positioning of the X and Y-axis drives on a stationary part of the machine adds to the rigidity of the machine, and eliminates the need for flexible cables to power and control these drives.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a machine tool generally designated by the reference numeral 10 . The machine tool is surrounded by standard guarding 12 , and an operator station 14 is positioned outside of the guarding. The machine tool receives a pallet 15 with a workpiece from a pallet manipulator 17 that may be positioned adjacent to a pallet access opening 18 in the guarding. In operation, the pallet 15 is transferred from the pallet manipulator 17 to a pallet receiver 19 that is a part of the machine. The pallet receiver 19 is then driven to the working zone of the machine in front of the spindle and the working tool.
FIG. 2 shows the X, Y, and Z-axis elements of the machine tool. The pallet 15 with a workpiece 16 is positioned in front of a spindle or multi-axis head 23 that carries the working tool 24 and this establishes a workzone. The Y-axis column 25 is fixed and is bifurcated. As shown in FIG. 2 and also in FIG. 3 , the Y-axis column 25 carries a vertically movable saddle 26 that is mounted in a center opening 21 between the two sides of the bifurcated column 25 on vertical linear guides or ways 27 best seen in FIG. 3 . Although not separately shown, feedback sensors for the vertical position of the saddle are also located adjacent to the ways 27 . A servomotor 28 is mounted on each side of the Y-axis column 25 , and each servomotor 28 is coupled to a drive screw 29 . The drive screws 29 engage drive nuts 31 on opposite sides of the saddle 26 , and the servomotors 28 are used to raise and lower the saddle to the desired vertical position.
The vertically movable saddle 26 carries a Z-axis slide 32 . Bearings mounted on the Z-axis slide 32 support the slide on bearing ways 34 that are mounted on the saddle. A Z-axis drive assembly 36 comprises a servomotor 37 and a drive screw 38 that are mounted on the saddle 26 . The Z-axis drive assembly 36 may be selectively controlled to position the Z-axis slide 32 and the working tool 24 in the desired position along the Z-axis. As used herein, the term Z-axis slide is used to designate a structure in which the bearings are mounted on the slide 32 and the bearing ways 34 are mounted on the saddle 26 . This is to distinguish the structure from a Z-axis ram in which the bearings are mounted on the saddle and the ways are mounted on the ram.
X-axis frame members 40 and 44 support an X-axis wall 42 , and a plurality of X-axis rails 41 are mounted on the X-axis wall 42 . The pallet receiver 19 is mounted on the X-axis rails 41 for horizontal movement along the X-axis. One or more X-axis drive motors 43 shown in phantom are mounted on the X-axis wall 42 to drive the pallet receiver back and forth along the X-axis rails. The X-axis frame member 40 is coupled to the Y-axis column 25 by upper and lower tubular frame members 46 and 47 , respectively, to form a rigid closed force loop design.
FIG. 3 is a sectional view of the machine tool taken along lines 3 - 3 of FIG. 1 showing certain elements of the machine 10 in greater detail. Two Y-axis ways 27 that guide the vertical movement of the saddle 26 are positioned on the bifurcated column 25 on either side of the center opening 21 . Two Y-axis flexible cable guides 51 are provided to carry electrical and hydraulic cables and the like from the stationary part of the Y-axis column 25 to the movable saddle 26 . One or more Z-axis flexible cable guides 52 are provided to carry electrical and hydraulic cables from the saddle 26 to the Z-axis slide 32 . FIG. 3 shows the X-axis rails 41 that extend from one side of the machine to the other to support the pallet receiver 19 and to position the pallet 15 in front of the working tool 24 . In this view, the pallet 15 and the receiver 19 are centered in front of the Y-axis column 25 .
FIG. 4 is a side sectional view of the machine tool taken along lines 4 - 4 of FIG. 1 . FIG. 4 shows that the drive screws 29 that move and support the saddle 26 are positioned at approximately the midpoint of the saddle measured along the Z-axis. Allowing for the mass and overhang of the spindle head 23 , this positioning of the drive screws 29 relative to the saddle 26 allows the center of gravity 30 of the combination of the saddle 26 and the Z-axis slide 32 to be maintained in relative proximity to the drive screws 29 . On high acceleration and deceleration machines, the acceleration forces become a greater concern than the cutting forces. These forces can be considered to act at the center of gravity of the moving mass. The greater the distance from the center of gravity to the drive system, the greater the moment load that is added to the system and therefore the deflection caused during acceleration. The greater the distance from the center of gravity to the way system, the greater the moment that is exerted on the bearings, again causing greater deflection. The greater the distance from the feedback sensors to the drive system, the greater the Abbe Error (angular error) that will be seen in the linear feedback which will decrease the electronic stiffness of the servo system. The Z-axis slide 32 is fitted with bearing trucks or carriages 33 that ride on the ways 34 that are mounted on the saddle.
FIG. 4 shows the two Z-axis cable guides 52 that carry electrical and hydraulic cables from the saddle 26 to the Z-axis slide 32 . FIG. 4 also shows the X-axis wall 42 that extends along the back of the workzone and is supported by the X-axis frame members 40 and 44 . A plurality of X-axis rails 41 are mounted on the wall 42 . The pallet receiver 19 is mounted on the X-axis rails 41 for horizontal movement along the X-axis. The X-axis drive motors 43 (only one shown) are used to drive the pallet receiver 19 back and forth along the X-axis rails 41 .
The Z-axis slide 32 carries the spindle 22 , the head 23 , and the tool 24 , and is movably mounted on the saddle 26 to travel in the Z-axis direction. Since the Z-axis slide 32 is relatively slender (its length is much greater than its width and height) and the working element or tool 24 overhangs from the support point of the bearing trucks or carriages 33 on the Z-axis slide on the ways 34 , placing the Z-axis ways 34 on the saddle 26 and the bearing trucks or carriages on the Z-axis slide 32 causes the droop and stiffness of the constant overhang Z-axis slide to be more constant than with a conventional ram design in which the guide ways are mounted on the ram and the bearing trucks or carriages are mounted at a fixed location on the saddle. Drawing FIGS. 5-14 illustrate these principles and are explained in greater detail below.
FIGS. 5 and 6 show the change in the load path 55 in a conventional ram 56 when the bearings 57 for the ram 56 are mounted on the saddle 58 and the ways 59 are mounted on the ram. FIG. 5 shows the ram 56 fully extended in the Z-axis direction. The length of the load path 55 measured from the midpoint 61 of the suspension point for the saddle 58 on the Y-axis ways 62 to the tip 63 of the ram 56 is nominally taken to be 1.0. FIG. 6 shows the ram 56 fully retracted. The length of the load path 55 measured from the midpoint 61 of the suspension point for the saddle 58 on the Y-axis ways to the tip 63 of the ram is 0.5, half the load path length shown in the configuration of FIG. 5 .
FIGS. 7 and 8 show how the angle or droop of the C-axis (the longitudinal axis of the ram 56 ) changes as the load path changes. In FIG. 7 , with the ram 56 fully extended, the angle α of the C-axis is significant. In FIG. 8 , with the ram 56 fully retracted, the angle α is zero. Thus, when using a ram with this design, the Z-axis ram stiffness and the C-axis angle vary with the position of the Z-axis ram 56 relative to the saddle 58 .
When the bearings trucks move with the Z-axis element and the ways are mounted on the supporting structure, the Z-axis element is called a slide. FIGS. 9 and 10 show the change in the load path 65 in a slide 66 when the bearings 67 are mounted on the slide 66 , the ways 68 are mounted on the saddle 69 , and the saddle 69 is suspended from one end. FIG. 9 shows the slide 66 fully extended in the Z-axis direction. The length of the load path 65 measured from the midpoint 61 of the suspension point for the saddle 69 on the Y-axis ways 62 to the tip 71 of the slide 66 is nominally taken to be 1.0. Although not shown, the load path length for the slide 66 at mid-stroke is 1.25. FIG. 10 shows the slide 66 fully retracted. The length of the load path 65 measured from the midpoint 61 of the suspension point for the saddle on the Y-axis ways 62 to the tip 71 of the slide is 1.5, a change of fifty percent from the length of the load path 65 shown in the configuration of FIG. 9 .
FIGS. 11 and 12 show the change in the load path for a Z-axis slide 66 in another suspension arrangement in which the bearings 72 for mounting the saddle 73 to the Y-axis ways 62 are positioned in the center of the saddle 73 instead of at one end. FIG. 11 shows the slide 66 fully extended in the Z-axis direction. The length of the load path 75 measured from the midpoint 61 of the suspension point for the saddle on the Y-axis ways 62 to the tip 71 of the slide is nominally taken to be 1.1. Although not shown, the load path length for the slide at mid-stroke is 0.9. FIG. 12 shows the slide 66 fully retracted. The length of the load path 75 measured from the midpoint 61 of the suspension point for the saddle on the Y-axis ways to the tip 71 of the ram is 1.1, the same as the load path length shown in FIG. 11 .
FIGS. 13 and 14 show how the angle of the C-axis changes as the load path changes with the suspension arrangement shown in FIGS. 11 and 12 . A comparison of FIGS. 13 and 14 shows that the overhang of the slide 66 remains constant as the slide moves from a fully extended to a fully retracted position on the saddle 73 , and as a result, angles α 1 , and α 2 are substantially the same with the slide 66 in the two positions.
A comparison of the change in the load path length in the examples shown in FIGS. 5 , 9 , and 11 shows that the load path changes the least with the suspension arrangement shown in FIGS. 11-14 . It will be appreciated by those skilled in the art that minimizing the change in length of the load path minimizes the change in the angle of the C-axis of the working tool, thus increasing the consistency of the rigidity of the tool, and improving the mechanical accuracy that can be maintained by the tool over its range of operation.
Because of the fixed overhang of the Z-slide design as shown in FIGS. 13 and 14 , the drives, bearings and external linear feedback for the Y-axis servo system can be positioned behind and near the center of gravity 77 of the saddle 73 and the Z-axis slide structure throughout the stroke of the Z-axis slide 66 . This keeps the center of gravity of the Y-axis moving mass as close as possible to the Y-axis drive screws 29 and Y-axis ways 34 to minimize twisting moments in the saddle structure caused by acceleration forces in the Y-axis direction. The fixed overhang of the Z-axis slide 66 also minimizes variation in length of the load path 75 throughout the Z-axis stroke as shown in FIGS. 11 and 12 . The load path length variation is roughly proportional to the stiffness variation. This location of the Y-axis supporting elements for the saddle also allows the Y-axis column structure 25 in the preferred configuration to be placed in front of the Y-axis drive components 28 , 29 , and 31 , the Y-axis ways 49 , and feedback systems. This in turn allows the maintenance removal of the entire saddle, the Y-axis drives, the Y-axis ways and linear feedback from the outside of the workzone, greatly improving maintainability of the systems. Furthermore, the location of these elements on the side of the Y-axis column that is opposite the workzone also makes these sensitive systems less likely to be contaminated by chips and cutting fluids from the workzone.
Having thus described the invention, various alterations and modifications may be apparent to those skilled in the art, which modifications and alterations are to be considered to be within the scope of the invention as defined by the appended claims.
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The frame of a machine tool forms a closed force loop design that surrounds a workzone containing the spindle head. The X and Y-axis drive motors are mounted on stationary elements of the machine. The Y-axis column is fixed, and supports a Z-axis ram. The mounting and positioning of the Z-axis ram minimizes the change in droop and the effects of acceleration forces on the Z-axis structure. The X, Y, and Z-axis drive motors are all mounted outside of the workzone to shield them from contamination and debris generating during the machining process, and for ease of maintenance.
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BACKGROUND OF THE PRESENT INVENTION
This invention relates to fluid cylinder devices, such as hydraulic and pneumatic cylinder devices, having stroke adjustment mechanisms.
Pneumatic and hydraulic cylinders are widely used mechanical drive components. Precision in cylinder piston rod movement is often desirable or required. Precise placement of a cylinder is often not possible, and despite precise placement, changes in other drive components, non-drive machinery components, workpieces and work processes occur. As a result, precise adjustment of piston rod stroke length and stroke end positions, both retracted and extended, is desirable.
To date, precision stroke adjustment mechanisms have been so limited as to provide adjustment of the stroke length and retracted position only, to the exclusion of adjustment of the piston rod extended position.
SUMMARY OF THE INVENTION
An object of the inventor in making the invention of this specification was to create a commercially useful fluid cylinder with a precision adjusting mechanism for precise adjustment of piston rod advanced position.
In a principal aspect, the invention is a fluid cylinder device comprising a fluid cylinder, a piston rod, a piston, and two elements described in "means plus function" terminology. The piston is mounted to the piston rod and in the fluid cylinder. The piston is so mounted for movement of the piston and rod in an extending direction and a retracting direction. A stopping means is mounted on the cylinder for stopping the movement of the piston and rod in the extending direction at an extended position. An adjusting means is operatively connected to the stopping means for adjusting the stopping means to adjust the extended position.
The stopping means is preferably a sleeve against which the piston abuts in the extended position, and through which the piston rod passes. The sleeve is adjustably mounted as by screw threads to a sleeve bushing fixed in position on the cylinder. Adjustment occurs by manual movement of the sleeve relative to the bushing.
Other objects, advantages and features of the invention will be understood from the description of the preferred embodiment, which follows.
BRIEF DESCRIPTION OF THE DRAWING
In the accompanying drawing, the preferred embodiment of the invention is shown, with the left half cut away and cross-sectioned to reveal internal detail.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the accompanying drawing, the preferred embodiment of the invention is a fluid cylinder device such as a pneumatic or hydraulic cylinder device 2. The device includes a fluid cylinder 3 having a base 4, cylindrical sidewall 5, and a cylinder head 6. The base, sidewall, and head are sealed to each other.
A piston rod 7 is affixed to a piston 8 in the cylinder. The piston includes seals such as seals 9, 10 about the periphery against the cylinder wall 5. The piston slides within the cylinder under fluid pressure (fluid fittings are not shown, for clarity of drawing) and the piston rod follows. The piston and rod are movable in a retracting direction to a retracted position, as shown, and in an extending direction 12 to an extended position, as shown in phantom.
The extended position is adjustable. Defining the movement of the piston and rod from the retracted position to the extended position as the stroke, the stroke is also adjustable.
The extended position is set by abuttment of the piston against the end of an adjusting sleeve 13. An adjusting sleeve bushing 14 is located within a recess 15 of the cylinder head, and screw threaded to the adjusting sleeve. The bushing and sleeve have operatively cooperating screw threads which accomplish threading.
The bushing 14 is held or retained within the recess 15 by a bushing retainer plate 16. A plurality of fasteners such as 17 affix the plate to the head, over the recess and against a ledge 18 of the bushing. A seal 19 encircles the bushing in a groove, sealing the bushing against the head recess wall.
A thread seal 20, comprising a washer 21 with opposed rubber coatings 22, 23 surmounts the retainer plate 16. The seal is held to the plate by being screwed onto the sleeve and by a jam nut 24. The nut is screw threaded to the sleeve 13.
The piston rod 7 is mounted within the sleeve 13, and the sleeve 13 is located through the head 6, bushing 14, retainer 16, seal 20 and nut 24. The rod is slidable within the sleeve. Two seals 25, 26 seal the rod against the sleeve.
The sleeve is movable relative to the head, through manual threading movement. Wrench flats such as flat 27 are on the sleeve, external to the cylinder 3 and the nut 24. Release of the nut 24 provides for manual threaded movement of the sleeve 13. Because the bushing 14 is fixed in position relative to the cylinder 3, threaded movement of the sleeve causes movement of the sleeve relative to the bushing and the cylinder. Sleeve movement results in relocation of the extended position of the piston and rod, through movement of the sleeve end against which the piston abuts.
Adjustment of the stroke and piston extended position is thus desirably possible. For gross adjustments the sleeve may be outward from the cylinder, the rod positioned to any extended position desired, and the sleeve retracted into abuttment. For fine adjustments, the sleeve may be advanced or retracted any desired small amount.
The preferred embodiment and the invention are now described in such full, clear, concise and exact terms as to enable a person of skill in the art to make and use the same. To particularly point out and distinctly claim the subject matter regarded as invention, the following claims conclude this specification.
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A pneumatic and hydraulic cylinder includes a precision adjustment mechanism for precise adjustment of piston rod extended position. The rod is slidable within a sleeve, which is screw threaded or otherwise adjustably mounted to the cylinder. The sleeve includes a stop for the piston, adjustably establishing the extended position.
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BACKGROUND OF THE INVENTION
[0001] The present invention relates to a hydraulic fastening device and method, and in particular to such a device and method useful in the mining or earthmoving industry for attaching teeth or wear plates to bucket drag lines of such implements and the like.
[0002] The present invention is however useful for attaching any two components together which might normally be joined by some form of mechanical joining mechanism, such as bolts, screws, or welds.
DESCRIPTION OF THE PRIOR ART
[0003] There are in existence different methods of using wedge and spool assemblies for connecting implements such as teeth and/or adaptors to drag lines buckets and the like which methods include that described in the applicant's International PCT Patent Application No. PCT/AU94/00035. That application discloses a spool and wedge assembly which comprises an array of wedges which co-operate to endable secure fitting of teeth to the buckets.
[0004] In the heavy earthworks industry, buckets attached to heavy earthmoving equipment are adapted with leading edge implements for cutting or moving overburden. These implements, commonly referred to as teeth, must by necessity be replaceable due to heavy wear and tear.
[0005] Teeth are generally fixed to a bucket in one of two ways. In the case of smaller buckets the teeth are detachably fixed directly to an adaptor formed integral with the bucket generally known as a bucket nose. In the case of the larger buckets the teeth are fitted via an adaptor which attaches to a specifically configured formation in the bucket leading edge. The teeth and adaptors are subjected to heavy wear and must be regularly replaced with the life of the teeth and adaptor generally dictated by the nature of over burden that the bucket is required to move. In the case of drag lines the wear is significant. According to the prior art the teeth are generally wedge shaped and attach to the leading edge of the adaptor by pin encapsulation, the pin connecting the spool and wedge assembly.
[0006] The adaptor mates at its trailing end to the bucket leading edge. At present, this particular attachment is effected by a known spool and wedge, assembly which comprises a generally elongated truncated cylindrical spool and a sedge which mutually cooperate to secure the adaptor to the bucket. Buckets usually have a multiplicity of such spool and wedge assemblies spaced apart along the leading edge of the bucket generally commensurate with the number of teeth on the bucket. In the case of large buckets there could be half a dozen or more assemblies which require constant replacement.
[0007] Not only do these assemblies require replacement after excessive wear, they also require constant monitoring during use to ensure that they do not become sloppy and loose thereby inhibiting the efficiency of the operation of the teeth.
[0008] Presently, according to one method, in order to fit the wedge and spool assembly, the wedge and spool are placed into recesses formed in both the adaptor and bucket, which are aligned when the adaptor is fitted to the bucket. When the adaptor is fitted to the bucket, this recess is axially aligned. The wedge element is then driven home axially by a sledge hammer, to secure the adaptor to the bucket. A tight fit is ensured by jamming the wedge against the spool. At present, the spool and wedge assembly extends axially downwardly beyond the periphery of the underside of the adaptor and bucket. The extension engages the ground during use of the bucket and causes the adaptor to become loose as the wedge and spool work loose. This occurs particularly in circumstances where the bucket is used to excavate hard and rocky ground. Personnel are employed to regularly check the integrity of the connection of the adaptor. Where the fit works loose, due to movement of the wedge and spool assembly, it must be constantly hammered to tighten the connection. This is a labour intensive and physically demanding activity. Likewise, when a spool and wedge assembly is to be released to free the adaptor from the bucket the assembly must be violently hammered to remove it and generally from underneath the bucket. For this purpose the bucket must be lifted up to enable a labourer to gain access to the distal end of the assembly. Due to the intensely physical nature of this work, many men are require to fit and remove the adaptors and to check and ensure tightness of the fit.
[0009] According to the prior art methodology, trades people, such as fitters, are employed to fit the spool and wedge assemblies to the buckets. The spool and wedge assembly is inserted into the recess in the implement to be fitted to the bucket. The wedge is hammered with a sledge hammer to drive the wedge home. Once a tight fit is achieved the bucket is used a small number of times and then rechecked. If loosening occurs the fitter drives the wedge in even further until it is tight enough to allow continued operation of the bucket. At that time any part of the wedge and spool assembly which extends beyond the extremity of the implements fitted to the bucket are removed by means of an oxy acetylene cutter.
[0010] The difficulty with removing the head piece and tail piece of the wedge and spool assembly is that if it again becomes loose it is difficult for the fitter to hammer the top of the wedge as it is flush with the surface of the implement fitted to the bucket.
[0011] Also, when an implement such as a tooth is finally worn out it can sometimes be so difficult to remove the spool and wedge assembly that it is necessary to cut through the old tooth or adaptor in order to remove the assembly. This clearly adds to the cost of fitting and maintaining the prior art wedge and spool assemblies.
[0012] The applicant has previously addressed this problem, one solution to which has been made the subject of aforesaid International PCT Patent Application No. PCT/AU94/00035. That application discloses an alternative form of spool and wedge assembly, and comprises a spool and wedge assembly for use in connecting an implement to the nose of an earth moving bucket. The spool and wedge assembly comprises first and second spools, first and second wedges, and, a bolt assembly for joining the first and second wedges. When the bolt is tuned in one direction the wedges are drawn towards each other thereby urging the spools apart and against the wall of a recess in which said spool and wedge assembly is placed thereby securing said implement to said bucket. As an alternative to the bolt assembly a threaded shank with a hexagonal nut my be used.
[0013] That invention has major advantages over the prior art particularly in its facility for convenient releasable attachment of implements to the buckets.
SUMMARY OF THE INVENTION
[0014] The present invention seeks to provide a further alternative to the applicant's own previous invention and in doing so to ameliorate the aforesaid disadvantages.
[0015] The present invention seeks to provide a convenient method for fitting, adjusting and/or removing a wedge and spool assembly.
[0016] The invention also seeks to provide a wedge and spool assembly adapted for ease of fitting, adjustment and release of a tooth or like implement and/or adaptor from an earthmoving bucket.
[0017] In one broad form, the present invention provides a hydraulic fastening device, for securement of two components, each component having an orifice or cavity at least partly therethrough adapted to be substantially coaxially aligned, said fastening device comprising:
[0018] a substantially elongate body member adapted to be inserted substantially within said orifice or cavity of each component when substantially coaxially aligned;
[0019] a fluid conduit within said body member containing a fluid therein;
[0020] at least one movable protrusion means in contact with said fluid, adapted to protrude in a substantially transverse direction from said elongate body member; and,
[0021] control means to control the movement of said at least one protrusion;
[0022] such that, upon operation of said control means, said at least one protrusion is moved to a protruded position to fasten said two components.
[0023] Preferably, said control means is a valve mechanism to permit the ingress/egress of fluid to/from said fluid conduit.
[0024] such that, upon the ingress of fluid, said protrusion(s) protrude from said body member, and, upon the egress of fluid, said protrusion(s) retract within said body member.
[0025] Alternatively, but also preferably, said control means comprises a piston device,
[0026] such that, when said piston device is actuated, a compressive force is applied to said fluid to cause said protrusion(s) to protrude from said body member, or, a decompressive force is applied to said fluid to cause said protrusion(s) to withdraw into said body.
[0027] In a preferred form of the invention a first of said components is a bucket or other component of an earthmoving or mining equipment, or the like; and,
[0028] a second of said components is one or more teeth, adaptors or the like, to be attached to said earthmoving or mining equipment or the like.
[0029] In a further preferred form said first component is embodied as an outwardly projecting member and is provided with a traverse orifice therethrough; and,
[0030] said second component is of complementary shape with a hollow centre portion, adapted to substantially surround said projecting member such that orifice(s)/cutout(s) provided on either side thereof are adapted to be substantially axially aligned with said orifice of said first component:
[0031] such that, when said orifice(s)/cutout(s) of said components are substantially aligned, said body member may be inserted and fastened therein.
[0032] Perhaps most preferably said body member is substantially cylindrical in shape.
[0033] In a further broad form, the present invention provides a method of fastening two components, wherein each of said components are of complementary shape and are provided with an orifice and/or cutout therein, comprising the steps of:
[0034] positioning said two components such that their respective orifice(s)/cutout(s) are substantially aligned;
[0035] inserting a fastening device within said joined orifice(s)/cutout(s), characterised in that said fastening device comprises a substantially elongate body member provided with a fluid conduit, at least one protrusion means, and control means to hydraulically control the movement of said protrusion means;
[0036] operating said control means such that said protrusion means extends substantially transversely of said body member such that said components become substantially fastened.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] The present invention will become more fully understood from the following detailed description of preferred but non-limiting embodiments thereof, described in connection with the accompanying drawings, wherein:
[0038] [0038]FIG. 1 shows an exploded view of a prior art spool and wedge assembly;
[0039] [0039]FIG. 2 shows a cross sectional view of the prior art device, in an assembled manner;
[0040] [0040]FIG. 3 shows a cross sectional view if the fastening device according to a preferred embodiment of the invention in assembled form;
[0041] [0041]FIG. 4 shows a side elevational view of the body member of the fastening device;
[0042] [0042]FIG. 5 shows a side elevational view of the body member of the device, rotated 90 degrees;
[0043] [0043]FIG. 6 shows an end view of the device;
[0044] [0044]FIG. 7 shows a cross sectional view of the device, detailing the fluid conduit; and,
[0045] [0045]FIG. 8 shows the piston like movable protrusion means and associated sealing rings which act in fastening the device.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0046] Referring to FIGS. 1 and 2 there is shown cross sectional views of the applicant's prior art spool and wedge assembly 1 , FIG. 1 showing an exploded view, and FIG. 2 showing the device in assembled form. The assembly comprises first and second opposing spool members 2 and 3 respectively, and includes first and second wedge members 4 and 5 linked by means of bolt 6 . Bolt 6 is adapted with hexagonal head 7 which preferably fits within recess 8 . Bolt 6 also has threaded portion 9 which threadably engages first wedge member 4 .
[0047] [0047]FIG. 2 shows a cross sectional assembled view of the assembly 1 fitted within a passage 9 in bucket nose 10 . Passage 9 aligns with passage 11 in adaptor 12 . Passages 9 and 11 are substantially in axial alignment when the adaptor is properly fitted to the bucket nose 10 . When an adaptor is to be fitted to the bucket nose 10 , the passages are first aligned so as to enable feeding therein of assembly 1 in a loosely assembled form. When the assembly 1 is in position, the user rotates head 7 of bolt 6 in a first direction which urges wedges 4 and 5 towards each other. When the assembly 1 is in position the wedges 4 and 5 abut spools 2 and 3 . Contact between wedge 4 and spools 2 and 3 takes place via abutment of surface 13 against surface 14 and abutment of surface 15 against surface 16 . Similarly, contact between wedge 5 and spools 2 and 3 takes place via abutment of surface 17 against 18 and surface 19 against 20 . The camming action generated between the aforesaid contacting surfaces induces a wedging effect and urges spools 2 and 3 in opposing directions and against the wall 21 in the case of bucket nose 10 and wall 22 in the case of adaptor 12 of passages 9 and 11 respectively.
[0048] Referring to FIG. 3 there is shown a cross sectional view of an alternative fastening arrangement 25 according to a preferred embodiment of the invention. The preferred embodiment in the invention will be described according to its use as a hydraulic wedge assembly as an alternative device to the spool and wedge assembly of FIGS. 1 and 2. It should be appreciated that the hydraulic fastening device is adaptable to a wide variety of applications far beyond replacement of a prior art mechanical spool and wedge device.
[0049] Assembly 25 generally comprises a substantially elongate body member 26 adapted to be inserted substantially within orifices or cavities of the pair of components. In the illustrated embodiment of FIG. 3, a first of the components is an outwardly projecting member 29 provided on a bucket or other component of an earthmoving or mining equipment. Component 29 is provided with an orifice 50 transversely therethrough. The second component is a complementary shaped component 51 which is adapted to be secured to the component 29 . A second component 51 is adapted to substantially surround the projecting member 29 , and is also provided with an orifice 52 therethrough. The orifice 52 is adapted to substantially coaxially align with the orifice 51 such that the fastening device may be inserted therein. As will be seen, when the first component 29 is substantially aligned with the second component 51 , the body member 25 may be inserted therein, as shown in FIG. 3.
[0050] [0050]FIG. 4 shows a side view of the device 25 , whilst FIG. 5 shows another side of it, rotated through a 90° angle.
[0051] [0051]FIG. 6 shows an end view of the device of FIGS. 3 to 5 . FIG. 7 shows a cross-sectional view of the device, and FIG. 8 shows details of the projection members and sealing means, of the fastening device.
[0052] The operation of the hydraulic fastening device will now be described in relation to FIG. 7. As the cross-sectional view of FIG. 7 shows, the device 26 is provided with a fluid conduit 32 therein, formed by a central cavity or channel 33 , a pair of channels 38 and 39 leading to chambers 36 and 37 , respectively. The fluid conduit and the chambers are adapted ti receive grease or other fluid substance therein. In the case of grease, a grease nipple 34 is provided to permit the ingress or egress of grease to and from the conduit 32 . A pair of pistons or protrusion members, such as detailed in FIG. 8 and shown by reference numerals 40 and 41 , are adapted to provided within the chambers 36 and 37 and be movably displaced in a direction transverse to the longitudinal direction of the body member 26 . The piston or protrusion members 40 and 41 are provided with suitable O-ring type seals or the like to ensure that good movement of the pistons 40 and 41 is enabled without the loss of fluid from within the fluid conduit. Suitable type rings are shown in FIG. 8 and illustrated by the numerals 60 and 61 .
[0053] The actuation of the pistons or protrusion members 40 and 41 will now be described in relation to this application to earth moving or mining equipment.
[0054] When an element such as a tooth or adaptor is to be fitted to an earth moving bucket, the main body member 26 is provided to within the recess or orifice formed between the two components 29 and 51 . Once the main body member 26 is in position, a grease gun is attached to the nipple 35 , and grease is supplied to within the fluid conduit 32 , such that pistons 40 and 41 which fit snugly within the cavities 36 and 37 are urged beyond the periphery 42 of the body member 26 . Depending upon how much grease is supplied to within the fluid conduit 32 , the pistons 40 and 41 may be advanced to a further or lesser distance. By way of example, the pressure required to advance the piston the small distance required to effect wedging of the fastening device between the two components in accordance with the preferred arrangement of the present invention, may typically be within the range of 5 psi to 1,000 psi. The distance of travel of the pistons to effect wedging would be typically of the order of 10-12 mm, but could be between 5 and 50 mm. Obviously, the pressure and distance travelled will vary depending upon the particular application of the invention.
[0055] When the fastening device 26 is to be released, for example, when the implement attached to the bucket is to be removed for replacement, the grease nipple may be rotated such that the pressure within the fluid conduit is reduced enabling the pistons 40 and 41 to be retracted to within the cavities 36 and 37 . Thereafter, the embodiment 26 is able to be released from the cavities or orifices.
[0056] The present invention has the advantage of reduced weight compared to the prior art devices and ease of insertion and release from its work sites. The physical effort required to remove the spook and wedge assembly is dramatically reduced and little or no sledge hammering is required. A large mechanical advantage is obtained in use of the hydraulic assembly to induce the friction forces in the recess rather than relying on the strength of a sledge hammer blow to achieve the same friction effect as was the case with the prior art.
[0057] It will of course be recongnised by persons skilled in the art that numerous variations and modifications may be made to the invention. For example, whilst the present invention has been particularly described in relation to a particular fastening arrangement useful for attaching wear teeth to an earth moving bucket, the device may be equally as well used for fastening any other two components together, from domestic household commercial use, etc. For example, wherever substantially aligned holes are drilled or otherwise supplied in two components and those components are intended to be fastened together, the fastening device may be used. It will be appreciated that a particular advantage of the fastening device of the present invention is that the provision of compression or additional fluid material to the device is easily supplied by known means, and likewise pressure or additional fluid may be released from the device by likewise known devices.
[0058] The utilisation of a hydraulic mechanism eliminates disadvantages with known mechanical fastening methods and devices. There is often a relationship between the physical strength of the person supplying the mechanical fastening device into position. Obviously also, the shape and configuration of the device will obviously be able to be varied to a large extend. The number, size and shape of the protrusions may also vary to a large extent.
[0059] Accordingly, it will be appreciated to persons skilled in the art that numerous variations and modifications to the invention will become apparent. All such variations and modifications should be considered to fall within the scope of the invention as broadly described hereinbefore and as claimed hereinafter.
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A hydraulic fastening device, for securement of two components, for example, securement of teeth to a bucket on earthmoving or mining equipment. Each component ( 29) and ( 51) has an orifice ( 50) and ( 52) therein adapted to be substantially aligned. A body member ( 26) is inserted in the aligned orifices ( 50) and ( 52). A control means ( 34) is then operated to move at least one protrusion ( 40) and ( 41) to protrude from the body ( 26) and to fasten the components ( 29) and ( 51). This achieved by hydraulic operation and connection of a fluid conduit ( 32) between the control means 34, e.g. A grease nipple, and the protrusions ( 40) and ( 41).
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FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a belt driving device capable of executing control for compensating for the lateral deviation (shift) and angular deviation (inclination) of its endless belt. It relates to also an image forming apparatus employing a belt driving device.
Some electrophotographic image forming apparatuses employ an endless belt (which hereafter may be referred to simply as “belt”) for transferring a toner image on a photosensitive member onto recording medium. For example, some electrophotographic image forming apparatuses employ an intermediary transferring member and/or a transfer medium bearing member, which is in the form of an endless belt. An intermediary transferring member temporarily carries a toner image when the toner image is transferred from a photosensitive member onto the intermediary transferring member. A transfer medium bearing member bears and conveys a sheet of transfer medium, onto which a toner image is transferred from an intermediary transferring member or a photosensitive member.
It has become possible to improve an image forming apparatus employing an intermediary transferring member and/or transfer medium bearing member, in various functions. For example, in the case of an image forming apparatus, the intermediary transferring member of which is a belt, multiple monochromatic toner images, different in color, are layered on the belt. Therefore, it enjoys a few advantages. For example, it is unlikely to be affected by the changes in the electrical resistance of transfer medium, which are attributable to changes in humidity or the like. However, it suffers from a problem peculiar to an image forming apparatus which employs a belt. More specifically, it suffers the problem that while its belt is driven, the belt changes its position in terms of the widthwise direction of the belt (which hereafter may be referred to as “lateral belt shifting” or “lateral belt deviation”), and/or the problem that, in terms of the widthwise direction of the belt, the upstream and downstream ends of the belt become different in position, that is, the belt becomes inclined, oblique or angled relative to the normal transfer medium conveyance direction (which may be referred to as “angular belt deviation”). If the lateral belt deviation is excessive, that is, if the belt laterally shifts excessively in the frontward or rearward direction, it is possible that the belt will be damaged. Further, if the belt, in particular, the belt of a full-color image forming apparatus, becomes angled relative to the normal transfer medium conveyance direction, it is possible that the apparatus will output full-color images which suffer from color deviation.
The phenomenon that while a belt is driven, it laterally deviates and/or it becomes angled relative to the normal transfer medium conveyance direction is sometimes attributable to the belt driving mechanism and/or the mechanical accuracy of the belt itself. Further, it is sometimes attributable to the changes in belt properties, various external forces to which the belt is subjected, for example, the vibrations which occur to the belt the moment a sheet of transfer medium is transferred onto the belt (as a transfer medium bearing member), from a transfer medium delivery mechanism. Therefore, it is desired that a belt driving device is equipped with a means for preventing the occurrence of the lateral belt deviation, and/or angular belt deviation, and a means for compensating for the lateral belt deviation and angular belt deviation as they occur.
Some of the means for compensating for the lateral belt deviation and angular belt deviation as they occur are as follows:
In the case of the belt driving device disclosed in Japanese Laid-open Patent Application 2006-76784, it is provided with two pairs of sensors for detecting the position of the belt, in terms of the widthwise direction (which hereafter may be referred to as “deviation direction” of the belt or simply as “belt position”), and a pair of belt steering rollers, which are at the upstream and downstream ends of the belt, one for one, in terms of the transfer medium conveyance direction. It is structured so that the steering rollers can be tilted in the out-of-plane direction. More specifically, the upstream steering roller is tilted in response to the information regarding the belt position, in terms of the widthwise direction of the belt, detected by the upstream and downstream sensors, whereas the downstream steering roller is tilted in response to the information regarding the belt angle, relative to the normal recording medium conveyance direction, detected by the downstream pair of sensors.
In the case of the belt driving device disclosed in Japanese Laid-open Patent Application 2011-170081, the downstream steering roller is tilted in the out-of-plane direction, in response to the information regarding the belt position in terms of the widthwise direction of the belt, and the tension roller, which is on the upstream side, is displaced in the thrust direction of the roller, in response to the information regarding the belt angle, relative to the normal transfer medium conveyance direction, or the upstream steering roller is tilted based on the information regarding the belt angle relative to the normal transfer medium conveyance direction.
However, in a case where only one steering roller is tilted in the out-of-plane direction to compensate for the angular belt deviation as disclosed in Japanese Laid-open Patent Application 2006-76784, the belt is changed in position in terms of its widthwise direction at the same time as it is changed in angle. Similarly, in a case where only one steering roller is tilted in the out-of-plane direction to compensate for the lateral belt deviation, the belt is changed in angle at the same time as it is changed in position in terms of its widthwise direction. Therefore, the operation for compensating for the angular belt deviation, and the operation for compensating for the lateral belt deviation, interfere with each other. Thus, it is difficult to quickly and precisely compensate for the lateral belt deviation and angular belt deviation.
For the reason given above, it takes a substantial length of time from when the driving of the belt is started to when the belt becomes stable in angle at a target value, and position at a target value, in terms of its widthwise direction. Therefore, it sometimes takes an unexpectedly long time from when an operator gives an image forming apparatus a command to start a printing operation to when a first sheet of transfer medium having a fixed toner image is outputted. Further, the operation for compensating for the angular belt deviation, and the operation for compensating for the lateral belt deviation, interfere with each other. Therefore, the belt driving device reduces in the level of accuracy at which the compensation is made for the angular belt deviation. Thus, it occurs sometimes that an image forming apparatus outputs images which suffer from color deviation and/or nonuniformity in color. Moreover, if an attempt is made to improve a belt driving device in its capability to compensate for the angular belt deviation, by increasing the control gain for the operation to compensate for the angular belt deviation in order to minimize an image forming apparatus in color deviation, not only does the belt change in angle, but also, the belt changes in position in terms of its widthwise direction. Therefore, the control system sometimes oscillates. In reality, therefore, control gain cannot be increased enough for the double-steering mechanism to be fully utilized in its performance. In other words, there is a limit to the conventional method for improving a belt driving device in its capability to compensate for the angular belt deviation.
Further, in a case where a belt suspending-tensioning roller is displaced in its thrust direction to compensate for the angular belt deviation as stated in Japanese Laid-open Patent Application 2011-170081, the belt angle and belt position change at the same time as stated in Japanese Laid-open Patent Application 2006-76784. Therefore, the same problem as that stated in Japanese Laid-open Patent Application 2006-76784 occurs.
Further, in a case where a steering roller is tilted in the in-plane direction to compensate for the angular deviation as disclosed in Japanese Laid-open Patent Application 2011-170081, a belt displaces in the belt conveyance direction. Thus, this method is problematic in that it has undesirable effects upon the color deviation in terms of the secondary scan direction.
SUMMARY OF THE INVENTION
According to an aspect of the present invention, there is provided a belt driving device for driving an endless belt, the belt driving device comprising a plurality of rollers configured to stretch the belt, said rollers including first and second steering rollers being provided in an upstream side and a downstream side of an image receiving surface of the belt for receiving an image, respectively, and being configured to change a position of the belt in a direction crossing with a moving direction of the belt by inclining respectively; a pivoting unit configured to pivot said first and second steering rollers, respectively; a detecting unit for detecting an inclination amount of the belt with respect to a feeding direction of the belt; and a controller configured to pivot said first and second steering rollers in the same direction by said pivoting unit on the basis of a result of detection of said detecting unit.
According to another aspect of the present invention, there is provided a belt driving device for driving an endless belt, the belt driving device comprising a plurality of rollers configured to stretch the belt, said rollers including first and second steering rollers being provided in an upstream side and a downstream side of an image receiving surface of the belt for receiving an image, respectively, and being configured to change a position of the belt in a direction crossing with a moving direction of the belt by inclining respectively; a pivoting unit configured to pivot said first and second steering rollers, respectively; a detecting unit for detecting an inclination amount of the belt with respect to a direction crossing with a feeding direction of the belt; and a controller configured to pivot said first and second steering rollers in opposite directions by said pivoting unit on the basis of a result of detection of said detecting unit.
According to a further aspect of the present invention, there is provided a belt driving device for driving an endless belt, the belt driving device comprising a plurality of rollers configured to stretch the belt, said rollers including first and second steering rollers being provided in an upstream side and a downstream side of an image receiving surface of the belt for receiving an image, respectively, and being configured to change a position of the belt in a direction crossing with a moving direction of the belt by inclining respectively; first and second pivoting mechanisms configured to pivot said first steering roller and second steering roller in accordance with respective pivoting instruction values; a first detecting member and a second detecting member configured detect a position of the belt with respect to a widthwise direction crossing with a moving direction of the belt; a first setting portion configured to set a first pivoting instruction value and a second pivoting instruction value through which said first steering roller and said second steering roller are pivoted in the same direction, respectively, on the basis of results of detections of said first detecting member and second detecting member; a second setting portion configured to set a third pivoting instruction value and a fourth pivoting instruction value through which said first steering roller and said second steering roller are pivoted in the opposite directions, respectively, on the basis of a result of detection of at least one of said first detecting member and second detecting member; and a controller configured to pivot said first steering roller by said first pivoting mechanism on the basis of an addition value of the first pivoting instruction value and the third pivoting instruction value, and configured to pivot said second steering roller by said second pivoting mechanism on the basis of an addition value of the second pivoting instruction value and the fourth pivoting instruction value.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic sectional view of the image forming apparatus in the first embodiment of the present invention.
FIGS. 2( a ) and 2 ( b ) are schematic drawings for describing the belt edge sensors in the first embodiment.
FIG. 3 is a side view of the steering roller and its adjacencies in the first embodiment.
FIGS. 4( a ), 4 ( b ), and 4 ( c ) are schematic perspective drawings for describing the principle based on which a belt is moved in its widthwise direction by the tilting the steering roller, in the first embodiment.
FIG. 5 is a graph which shows the relationship between the angle by which the steering roller is tilted, and the speed with which the belt moves in its widthwise direction.
FIG. 6 is a block diagram of the steering control system, in the first embodiment.
FIGS. 7( a ) and 7 ( b ) are schematic perspective views of the belt unit when two steering rollers are simultaneously tilted in the same direction.
FIG. 8 is a graph which shows the changes in the position of the belt, in terms of the widthwise direction of the belt, which occurred as two steering rollers were simultaneously tilted in the same direction, and which were detected by the first and second sensors.
FIGS. 9( a ) and 9 ( b ) are schematic perspective views of the belt unit when the two steering rollers were simultaneously tilted in the opposite direction relative to each other.
FIG. 10 is a graph which shows the changes in the position of the belt, in terms of the widthwise direction, which occurred as two steering rollers were simultaneously tilted in the opposite direction relative to each other, and which were detected by the first and second sensors.
FIG. 11 is a flowchart of the steering control sequence in the first embodiment, showing from the starting to the end of a printing operation.
FIG. 12 is a block diagram of a comparative example of steering control.
FIG. 13 is a graph which shows the changes in the belt position in terms of its widthwise direction, which occurred when a single steering roller was tilted by the comparative example of steering control, and which were detected by the first and second sensors.
FIG. 14 is a block diagram of the steering control sequence in another (second) embodiment of the present invention.
FIG. 15 is a flowchart of the steering control sequence in the second embodiment, showing from the beginning to the end of a printing operation.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, belt driving devices and image forming apparatuses, which are in accordance with the present invention, are described in detail with reference to appended drawings.
Embodiment 1
1. Overall Structure and Operation of Image Forming Apparatus
FIG. 1 is a schematic sectional view of the image forming apparatus in the first embodiment of the present invention (at plane perpendicular to the belt conveyance direction, which will be described later in detail).
The image forming apparatus 1 is a full-color printer of the so-called tandem type, and also, of the so-called intermediary transfer type. That is, it has multiple image forming portions 20 Y, 20 M, 20 C and 20 K, as image forming means, which are aligned in tandem in the moving direction of the primary transfer surface H of the intermediary transfer belt 31 . The image forming portions 20 Y, 20 M, 20 C and 20 K form yellow (Y), magenta (M), cyan (C) and black (K) images, respectively.
The image forming portions 20 Y, 20 M, 20 C and 20 K are practically the same in structure and operation, although they are different in the color of the toner they use. Thus, in the following description of the image forming apparatus, the suffixes Y, M, C and K which are for indicating color are not shown. That is, in terms of structural components, the four image forming portions are described together, unless they need to be differentiated.
The image forming portion 20 has a photosensitive drum 21 , as an image bearing member, which is an electrophotographic photosensitive member. The photosensitive drum 21 is in the form of a drum (cylindrical). The photosensitive drum 21 is rotationally driven in the direction indicated by an arrow mark R 1 in the drawing. Each image forming portion 20 has also a charging device 22 of the corona type, as a charging means, an exposing device (laser scanner) 23 as an exposing means, a developing device 24 as a developing means, a primary transfer roller 25 as a primary transferring means (primary transferring member in form of roller), and a drum cleaning device 26 as a photosensitive member cleaning means, which are disposed in the adjacencies of the peripheral surface of the photosensitive drum 21 , in the listed order, in the rotational direction of the photosensitive drum 21 .
The photosensitive drum 21 has a negatively chargeable photosensitive layer as the surface layer. It is rotationally driven at a process speed of roughly 300 mm/sec, in the direction indicated by the arrow mark R 1 in the drawing.
The charging device 22 of the corona type negatively charges the peripheral surface of the photosensitive drum 21 to a preset potential level VD (pre-exposure potential level), by irradiating charged particles attributable to corona discharge.
The exposing device 23 writes an electrostatic image (electrostatic latent image) on the peripheral surface of the photosensitive drum 21 , by scanning the charged portion of the photosensitive drum of the photosensitive drum 21 , with the beam of laser light it emits while modulating (turning on or off) the beam, according to the image formation data obtaining by separating the image to be formed, into monochromatic images of the primary colors.
The developing device 24 charges the two-component developer, that is, the developer made up of nonmagnetic toner particles (toner) and magnetic carrier particles (carrier), makes its development sleeve 24 a , as a developer bearing member, bear the charged developer, and conveys the charged developer to the area where the development sleeve 24 a opposes the photosensitive drum 21 . To the development sleeve 24 a , an oscillatory voltage, which is a combination of DC and AC voltages, is applied as development bias. Thus, the negatively charged toner is made to transfer onto the exposed points (portions) of the peripheral surface of the photosensitive drum 21 , which are positive in polarity relative to the negatively charged toner. Consequently, the electrostatic latent image is developed in reverse.
The primary transfer roller 25 presses the intermediary transfer belt 31 , from the inward side of the intermediary transfer belt 31 , upon the peripheral surface of the photosensitive drum 21 , forming thereby a primary transferring portion (nip) T 1 between the photosensitive drum 21 and intermediary transfer belt 31 . In the primary transferring portion T 1 , the toner image on the peripheral surface of the photosensitive drum 21 is transferred (primary transfer) onto the intermediary transfer belt 31 . More specifically, in order to transfer the toner image on the photosensitive drum 21 onto the intermediary transfer belt 31 , positive DC voltage, which is opposite in polarity from the toner (normal toner charge polarity) is applied as primary transfer bias to the primary transfer roller 25 .
The drum cleaning device 26 scrapes the peripheral surface of the photosensitive drum 21 with its cleaning blade. Thus, the toner (primary transfer residual toner) remaining on the peripheral surface of the photosensitive drum 21 after the primary transfer is removed from the photosensitive drum 21 , and is recovered.
A belt unit 30 , as a belt driving device, is positioned so that it opposes the photosensitive drum 21 of each image forming portion 20 . Although the structure and operation of the belt unit 30 will be described later in detail, the belt unit 30 has the intermediary transfer belt 31 suspended, and kept tensioned, by multiple rollers. As a first steering roller 34 , which will be described later, is rotationally driven, the intermediary transfer belt 31 is circularly moved in the direction indicated by the arrow mark R 2 in the drawing. Further, each image forming portion 20 is provided with a primary transfer roller 25 , which is positioned on the inward side of the loop (belt loop) which the intermediary transfer belt 31 forms, so that it opposes the photosensitive drum 21 . Further, there is a secondary transfer roller 47 as the secondary transferring member, on the outward side of the loop which the intermediary transfer belt 31 forms. The secondary transfer roller 47 is positioned so that it opposes a belt-backing roller 36 , which also will be described later. The secondary transfer roller 47 is placed in contact with the portion of the intermediary transfer belt 31 , which is supported by the belt-backing roller 36 from within the belt loop, forming thereby the secondary transferring portion (nip) T 2 . Further, there is a belt cleaning device 39 as the means for cleaning the intermediary transfer belt 31 , on the outward side of the belt loop, and is positioned so that it opposes the first steering roller 34 , which will be described later.
When the image forming apparatus 1 is used for forming a full-color image, first, a yellow toner image is formed on the photosensitive drum 21 Y in the image forming portion 20 Y, and is transferred (primary transfer) onto the intermediary transfer belt 31 . In the image forming portion 20 M for magenta color, a magenta toner image is formed on the photosensitive drum 21 M, and is transferred (primary transfer) in layers on the yellow toner image on the intermediary transfer belt 31 . In the image forming portions 20 C and 20 K for cyan and black colors, respectively, cyan and black toner images are formed on the photosensitive drum 21 C and 21 K, respectively, and are transferred (primary transfer) in layers onto the intermediary transfer belt 31 . After being transferred onto the intermediary transfer belt 31 , the multiple (four) toner images, different in color, are conveyed to the secondary transferring portion T 2 , and transferred together (secondary transfer) onto a sheet P of transfer medium such as recording paper.
Sheets P of transfer medium in a transfer medium cassette 44 are pulled out of the transfer medium cassette 44 while being separated one by one by a separation roller 43 , and then, each sheet P of transfer medium is conveyed to a pair of registration rollers 45 . The registration rollers 45 catch each sheet P of transfer medium, and keeps the sheet P on standby, while remaining stationary. Then, they send the sheet P to the secondary transfer portion T 2 , with such a timing that the sheet P arrives at the secondary transferring portion T 2 at the same time as the toner images on the intermediary transfer belt 31 . In the secondary transferring portion T 2 , the sheet P is sandwiched by the intermediary transfer belt 31 and secondary transfer roller 47 , being layered upon the toner images on the intermediary transfer belt 31 . Thus, while the sheet P is conveyed through the secondary transferring portion T 2 , the toner images on the intermediary transfer belt 31 are transferred (secondary transfer) onto the sheet P of transfer medium. During this process, DC voltage which is positive in polarity, being therefore opposite in polarity from the polarity of toner (normal polarity of charged toner) during development, is applied as the second transfer bias to the secondary transfer roller 47 .
The toner (secondary transfer residual toner) which was not transferred onto the sheet P of transfer medium, and therefore, are remaining on the peripheral surface of the photosensitive drum 21 after the secondary transfer, is removed from the intermediary transfer belt 31 by the belt cleaning device 39 , and is recovered.
After the transfer of the full-color toner image, made up of four monochromatic images, different in color, onto the sheet P of transfer medium, the sheet P is separated from the intermediary transfer belt 31 with the utilization of the curvature of the intermediary transfer belt 31 , and then, is introduced into a fixing device 46 as a fixing means. The fixing device 46 fixes the full-color toner image to the surface of the sheet P by applying heat and pressure to the sheet P. After the fixation of the toner image to the sheet P, the sheet P is discharged from the main assembly of the image forming apparatus 1 .
In the case of the intermediary transfer system which indirectly transfers a toner image onto a sheet P of transfer medium by way of the intermediary transfer belt 31 , it is on the intermediary transfer belt 31 that multiple monochromatic toner images, different in color, are layered. Therefore, it is unlikely to be affected by the changes in the electrical resistance of transfer medium, which is attributable to changes in humidity, for example. Further, in comparison to the direct transfer system which directly and sequentially transfers multiple monochromatic toner images, different in color, onto a sheet P of transfer medium, the intermediary transfer system is easier to control in the condition under which toner images are transferred when a full-color image is formed. Further, an image forming apparatus which employs the intermediary transfer system is simpler in the transfer medium conveyance system, and therefore, less likely to suffer from sheet jam.
2. Belt Steering System
In order to form a high quality full-color image, in particular, a full-color image which does not suffer from color deviation, with the use of an image forming apparatus 1 structured so that it is on the intermediary transfer belt 31 that multiple toner images are layered, it is important to control the belt unit of the image forming apparatus 1 so that the belt unit becomes as close as zero in the angular deviation of the belt, for the following reason. That is, if the belt is angled relative to the normal transfer medium conveyance direction, the image forming portions 20 , different in the color of the image they form, become different in the position of their primary transferring portion T 1 , in terms of the direction perpendicular to the normal transfer medium conveyance direction. This results in the formation of a full-color image which suffers from color deviation. Further, if the intermediary transfer belt 31 laterally deviates all the way (virtually completely deviates in its widthwise direction, that is, either rearward or forward), it is possible that the intermediary transfer belt 31 will be damaged. In order to prevent this problem, it is important to keep the intermediary transfer belt 31 positioned so that the intermediary transfer belt 31 is prevented from laterally deviating all the way.
However, as an endless belt suspended, and kept tensioned, by multiple rollers, is circularly driven, the belt is subjected to such a force that pushes the belt in the direction parallel to the axial line of each roller (widthwise direction of belt). Therefore, the belt displaces in the direction parallel to the axial line of the roller until the above-described force disappears. This phenomenon is attributable to several factors, for example, errors in belt dimension, errors in the diameter of each of belt suspending rollers, misalignment of the rollers, which occurred during the assembly of the belt unit, etc.
Therefore, in the case of the image forming apparatus 1 in this embodiment, a belt steering system is employed to ensure that when the belt is circularly driven, it remains stable in its path. Generally speaking, the belt steering system is structured as follows: That is, the belt unit is structured so that at least one of the rollers by which the belt is suspended is usable as a steering roller, that is, a roller which can be tilted. Further, the position to which the belt has laterally moved, and the angular deviation of the belt, are detected. Then, based on this information, the steering roller is controlled in the direction in which it is to be tilted, and the amount (angle) by which it is to be tilted, in order to compensate for the lateral deviation of the belt and angular deviation of the belt. In particular, in the case of the image forming apparatus 1 in this embodiment, the two steering rollers are controlled in angle in order to compensate for two factors, that is, the lateral deviation of its belt, and the angular deviation of the belt.
3. General Structure of Belt Unit
Next, the belt unit 30 , as a belt driving device, in this embodiment, which is equipped with a belt steering system is described.
Regarding the orientation of the image forming apparatus 1 and/or its structural components, the front side is equivalent to the front side of the sheet of paper on which FIG. 1 is drawn. The rear side is the opposite side of the front side. Further, the direction which is parallel to the line connecting the front and rear sides is the rearward direction. The rearward direction is such a direction that is perpendicular to the belt conveyance direction (roughly parallel to axial line of belt supporting roller).
The belt unit 30 has: the intermediary transfer belt 31 which is an endless belt (belt, belt-like member); and multiple belt suspending rollers (belt supporting rollers), as a belt suspending-tensioning members, which are means for rotatably supporting the intermediary transfer belt 31 . In this embodiment, the belt unit 30 has the following multiple rollers which support, and keep tensioned, the intermediary transfer belt 31 . More specifically, the belt unit 30 has: the first steering roller (belt driving steering roller) 34 , which functions as both a belt driving roller, and belt steering roller; the second steering roller 35 ; the first idler roller 32 ; the second idler roller 33 ; and the belt-backing roller 36 . Further, the belt unit 30 has also the primary transfer rollers 25 Y, 25 M, 25 C and 25 K, which are on the inward side of the loop (belt loop) which the intermediary transfer belt 31 forms, as described previously. In this embodiment, each of the primary transfer rollers 25 Y, 25 M, 25 C and 25 K also makes up a part of the combination of the multiple belt suspending rollers. The intermediary transfer belt 31 is rotatably supported and kept tensioned, by these belt suspending rollers.
The first steering roller 34 is in connection to the belt-driving motor 37 as a belt driving means. Thus, as the first steering roller 34 is rotationally driven in the direction indicated by an arrow mark R 3 in the drawing by the belt-driving motor 37 , the intermediary transfer belt 31 is circularly moved in the direction indicated by the arrow mark R 2 in the drawing.
The second steering roller 35 is kept pressed by a pair of springs 42 , outward of the intermediary transfer belt 31 , from within the belt loop. It is attached so that it can be changed in position. Thus, the second steering roller 35 provides the intermediary transfer belt with a preset amount of tension.
The first and second idler rollers 32 and 33 prevent the intermediary transfer belt 31 from being changed in its angle (inclination), relative to a preset plane, by the tilting of the first steering roller 34 and second steering roller 35 , in order to keep the primary transfer surface H parallel to the preset plane.
The first idler roller 32 is positioned upstream of the primary transfer roller 25 Y (that is, primary transferring portion T 1 ) of the image forming portion 20 Y, which is the most upstream image forming portion 20 , in terms of the belt conveyance direction. The second idler roller 33 is positioned downstream of the primary transfer roller 20 K of the image forming portion 20 K, which is the most downstream image forming portion 20 , in terms of the belt conveyance direction. The first steering roller 34 and second steering roller 35 , which are belt suspending rollers adjustable in alignment, are on the upstream and downstream sides, respectively, of the primary transfer surface (image receiving portion) H of the intermediary transfer belt 31 .
Although detailed description will be given later, the belt unit 30 is structured so that the lateral deviation of the intermediary transfer belt 31 , and the angular deviation of the intermediary transfer belt 31 , can be controlled by optionally changing the first steering roller 34 and second steering roller 35 in alignment. “Alignment” means the angle of the rotational axis of a steering roller relative to the direction perpendicular to the belt conveyance direction, that is, the out-of-plane angular deviation. “Lateral deviation” of the intermediary transfer belt 31 means the change (deviation) in the position of the intermediary transfer belt 31 in terms of its widthwise direction. Further, “Angular deviation” of the intermediary transfer belt 31 is equivalent to the difference in position between the upstream and downstream ends of the intermediary transfer belt 31 , in terms of the widthwise direction of the belt 31 . It sometimes is referred to as “belt inclination” or “belt skew”.
Next, the means employed by the belt steering system in this embodiment to detect the position of the intermediary transfer belt 31 in terms of its widthwise direction, and the angle of the intermediary transfer belt 31 relative to the normal belt conveyance direction, is described.
The belt unit 30 is provided with a pair of sensors (first and second sensors 38 a and 38 b ), which are disposed so that their position corresponds to the first transfer surface H of the intermediary transfer belt 31 , with the presence of a preset distance between the two sensors 38 a and 38 b in terms of the belt conveyance direction. The first and second sensors 38 a and 38 b are detecting means for detecting the lateral deviation of the intermediary transfer belt 31 , and/or angular deviation of the intermediary transfer belt 31 . That is, they make up an example of means for detecting the position (to which intermediary transfer belt 31 has deviated) of the intermediary transfer belt 31 in terms of its widthwise (direction of deviation) direction.
The first sensor 38 a is disposed in the adjacencies of the first idler roller 32 which is on the upstream side of the primary transfer surface H. The second sensor 38 b is disposed in the adjacencies of the second idler roller 33 which is on the downstream side of the primary transfer surface H. To describe in more detail, the first sensor 38 a is between the first steering roller 34 and the primary transfer roller 25 Y of the most upstream image forming portion 20 Y which is the closest of the four primary transfer rollers 25 to the first steering roller 34 . It is in the adjacencies (downstream side) of the first idler roller 32 . Further, the second sensor 38 b is between the first steering roller 34 and the primary transfer roller 25 K of the most downstream image forming portion 20 K which is the closest of the four image forming portions 20 to the second steering roller 35 . It is in the adjacencies (upstream side) of the second idler roller 33 .
In this embodiment, the first sensor 38 a and second sensor 38 b are principally the same. They are edge sensors for detecting one of the lateral edges of the intermediary transfer belt 31 . Here, the second sensor 38 b , which is on the downstream side of the primary transfer surface H, is described further in detail.
FIG. 2( a ) is a schematic drawing which shows the appearance of the downstream portion of the belt unit 30 where the second sensor 38 b is present. The second sensor 38 b can detect the position of the intermediary transfer belt 31 in terms of the widthwise direction of the intermediary transfer belt 31 , at its location (detection point).
FIG. 2( b ) is a schematic sectional view of the second sensor 38 b . The second sensor 38 b is structured so that one end of its contact 38 x is kept pressed upon the one (rear) of the lateral edges of the intermediary transfer belt 31 , by the tension of the spring 38 w . In this embodiment, the contact pressure generated between the contact 38 x and the lateral edge of the intermediary transfer belt 31 by the spring 38 w is properly set, that is, large enough to keep the contact 38 x in contact with the lateral edge of the intermediary transfer belt 31 , but not large enough to deform the intermediary transfer belt 31 . Further, the contact 38 x is rotatably supported by a shaft 38 y , at its center portion. Further, a displacement sensor 38 z , which is a photosensor of the reflection type, is positioned so that it opposes the other end of the contact 38 x . Thus, the changes in the position of the intermediary transfer belt 31 in terms of its widthwise direction (indicated by arrow mark y in drawing) is converted into the movement (oscillatory movement) of the contact 38 x which is kept pressed upon the lateral edge of the intermediary transfer belt 31 . More specifically, the output level of the displacement sensor 38 z changes in response to the movement (displacement) of the contact 38 x . Therefore, the position of the intermediary transfer belt 31 in terms of its widthwise direction can be continuously determined based on the output of the sensor 38 z.
Generally speaking, here, the contour of the edge of the intermediary transfer belt 31 is not really straight, because of what occurred during the manufacturing of the intermediary transfer belt 31 , the material for the intermediary transfer belt 31 , etc. Therefore, in the case of a system which detects the edge of the intermediary transfer belt 31 to determine the position of the intermediary transfer belt 31 , the belt position in terms of its widthwise direction can be more accurately detected by making the two sensors substantially different in the belt edge detection timing by providing a substantial distance between the two sensors, or obtaining in advance the profile of the belt edge, and compensating the results of the measurement by the sensors, based on the belt edge profile.
Incidentally, the method for detecting the position of the intermediary transfer belt 31 in terms of its widthwise direction does not need to be limited to the means such as the above described one which places a sensor of the contact type along one of the lateral edges of the intermediary transfer belt 31 . For example, it may be a method which reads a mark (which may be drawn or formed in advance, or formed with toner) drawn on the belt, with the use of a sensor of the non-contact type. That is, the present invention is compatible with either of the above described two means for detecting the position of the intermediary transfer belt 31 in its widthwise direction.
As the information, regarding the angular deviation of the intermediary transfer belt 31 , which can be used by the belt steering system to control the angular deviation of the intermediary transfer belt 31 , the value which is obtainable by the subtraction between the belt position detected by the sensor 38 a and the belt position detected by the sensor 38 b is used. As the information, regarding the position of the intermediary transfer belt 31 , which can be used by the belt steering system to control the lateral deviation of the intermediary transfer belt 31 , the average value (which may be referred to “average belt position”) obtainable by averaging the information, regarding the belt position, detected by the two sensors 38 a and 38 b , is used.
As the information regarding the angular belt deviation which is used to control the angular deviation of the belt, the belt angle obtainable by using a single two-dimension area sensors, may be used. Further, as the information regarding the lateral deviation of the belt may be the value (output) of a single sensor, or the average value obtainable by averaging the results of the belt position detection by three or more sensors.
5. Operation to Tilt Steering Roller
Next, the operation carried out by the belt steering system to tilt the steering rollers is described.
As described above, the image forming apparatus 1 has two steering rollers, that is, the first steering roller 34 and second steering roller 35 . In this embodiment, the method for tilting the first steering roller 34 and the method for tilting the second steering roller 35 are the same. Here, therefore, only the tilting of the second steering roller 35 is described.
FIG. 3 is an enlarged schematic side view (as seen from direction intersectional to belt conveyance direction) of the second steering roller 35 and its adjacencies.
First, the structure of the front end portion of the second steering roller 35 is described. The second steering roller 35 is rotatably supported by a bearing holder 107 , which is fixed to the movable side of a slidable rail 106 . Further, a slider 105 is fixed to the surface of the slidable rail 106 , to which the bearing holder 107 is fixed. The stationary side of the slidable rail 106 is fixed to the steering arm (supporting member) 101 . Further, the slider 105 is under the pressure generated in the direction indicated by an arrow mark T in FIG. 3 (outward direction of loop which intermediary transfer belt 31 forms), by a spring (pressure generating member) 109 , as pressure generating means, anchored to the steering arm 101 . Therefore, the slider 105 slides on the steering arm 101 . Thus, the second steering roller 35 is kept pressured in the direction indicated by the arrow mark T in FIG. 3 (outward direction of loop which intermediary transfer belt 31 forms), providing thereby the intermediary transfer belt 31 with tension.
In this embodiment, the second steering roller 35 is kept pressured by the spring 109 , functioning thereby to provide the intermediary transfer belt 31 with a preset amount of tension. However, the steering function and tensioning function does not need to be provided by the same component. That is, the image forming apparatus 1 may be structured so that the member for tilting the steering roller is independent from the member for providing the intermediary transfer belt 31 with tension.
In this embodiment, the front steering arm 101 is supported by a shaft (pivot) 104 so that it can be pivotally moved about the shaft 104 . There is a follower 102 on the steering arm 101 . The follower 102 is on the opposite side of the shaft 104 from the second steering roller 35 , and is supported by a shaft. There is a cam 103 , as an activating portion, which is enabled to come into contact with the follower 102 . The cam 103 is rotatable by a steering motor 108 as steering roller driving means. The cam 103 and steering motor 108 make up a cam mechanism 110 , as force generating means, which generates the force for tilting the steering roller 35 .
As the cam 103 rotates in the direction (clockwise) indicated by an arrow mark A in FIG. 3 , the lengthwise end portion of the steering arm 101 , which has the follower 102 , rotates in the direction (clockwise) indicated by an arrow mark C in FIG. 3 , about the shaft (pivot) 104 . As a result, the lengthwise end portion of the steering arm 101 , by which the second steering roller 35 is held, rotationally moves in the direction indicated by an arrow mark E (downward relative to primary transfer surface H), causing thereby the steering arm 101 to change in alignment. On the other hand, as the cam 103 rotates in the direction (counterclockwise) indicated by an arrow mark B in FIG. 3 , the follower 102 side of the steering arm 101 rotationally moves in the direction (counterclockwise) indicated by an arrow mark D in FIG. 3 , about the shaft (pivot) 104 . As a result, the second steering roller 35 side of the steering arm 101 rotationally moves in the direction (upward relative to primary transfer surface H), causing thereby the second steering roller 35 to change in alignment.
The rear end portion of the second steering roller 35 is supported roughly in the same manner as the front end portion of the second steering roller 35 . On the rear end side, however, the steering arm 101 is fixed to the rear end portion of the second steering roller 35 ; it is not provided with the cam mechanism 110 .
FIG. 4 is a schematic perspective view of the second steering roller 35 and its adjacencies. It is a drawing for describing the changes caused to the position of the intermediary transfer belt 31 , in terms of its widthwise direction, by the tilting of the second steering roller 35 .
As the second steering roller 35 is tilted as shown in FIG. 3 , the intermediary transfer belt 31 is changed in position in terms of its widthwise direction as shown in FIGS. 4( a ), 4 ( b ) and 4 ( c ). More specifically, as the second steering roller 35 is changed in alignment in the direction indicated by an arrow mark E in FIG. 3 , the intermediary transfer belt 31 shifts rearward, whereas the second steering roller 35 is changed in alignment in the direction indicated by an arrow mark F in FIG. 3 , the intermediary transfer belt 31 shifts frontward.
In this embodiment, the rear steering arm (unshown) is fixed. However, this embodiment is not intended to limit the present invention in scope. For example, the rear side of the belt unit 30 may be provided with the same mechanism as the front side in order to make the rear steering arm pivotally movable. In such a case, it is possible to make the front and rear sides opposite in the direction in which they pivotally move, but the same in the absolute value of the amount of pivotal move, in order to make the second steering roller 35 pivotally move about the center of the second steering roller 35 .
At this time, referring to FIG. 4 , the basic relationship between the inclination of the second steering roller 35 and the lateral shift of the intermediary transfer belt 31 is described.
When the belt unit 30 is in the state shown in FIG. 4( a ), the second steering roller 35 is roughly parallel to the primary transfer surface H (second idler roller 33 , second steering roller 35 , and belt-backing roller 36 are roughly parallel to each other). In this case, it does not occur that the intermediary transfer belt 31 shifts on the second steering roller 35 in the direction parallel to the rotational axis of the second steering roller 35 .
When the belt unit 30 is in the state shown in FIGS. 4( b ) and 4 ( c ), the second steering roller 35 is tilted relative to the primary transfer surface H (that is, second steering roller 35 is tilted relative to the second idler roller 33 and belt-backing roller 36 ). In this case, the point at which the intermediary transfer belt 31 begins to wrap around the second steering roller 35 , and the point at which the intermediary transfer belt 31 separates from the second steering roller 35 , are different in terms of the direction parallel to the rotational axis of the second steering roller 35 .
That is, in the state shown in FIG. 4( b ), the second steering roller 35 tilts in such a direction that its front end 35 a moves downward. In this case, as the intermediary transfer belt 31 is conveyed in the direction indicated by the arrow mark R 2 in FIG. 4 , it shifts in parallel to the direction of the rotational axis of the second steering roller 35 , in the direction indicated by an arrow mark +Y in FIG. 4( b ) (that is, toward upstream end of second steering roller 35 in terms of belt conveyance direction). In comparison, in the state shown in FIG. 4( b ), the second steering roller 35 tilts in such a direction that its front end 35 a moves upward. In this case, as the intermediary transfer belt 31 is conveyed in the direction indicated by the arrow mark R 2 in FIG. 4 , it shifts in parallel to the rotational axis of the second steering roller 35 , in the direction indicated by an arrow mark −Y in FIG. 4( c ) (that is, toward upstream end in terms of belt conveyance direction).
The greater the second steering roller 35 in inclination, the greater the amount by which the intermediary transfer belt 31 shifts on the second steering roller 35 , in the direction parallel to the rotational axis of the second steering roller 35 . Therefore, the relationship between the amount a of inclination, that is, the angle of the second steering roller 35 relative to the inclination of the second steering roller 35 shown in FIG. 4( a ), and the speed (v) at which the intermediary transfer belt 31 shifts in the direction parallel to the axial line of the steering roller 35 , is as shown in FIG. 5 . Referring to FIG. 5 , the amount a of inclination (absolute value, strictly speaking) increases beyond a certain value, the relationship loses its linear characteristic, for the following reason. That is, as the second steering roller 35 increases in its inclination, the second steering roller 35 and intermediary transfer belt 31 begin to continuously slip relative to each other. Thus, it is within the range, shown in FIG. 5 , in which the relationship is linear, that the lateral and/or angular deviation of the intermediary transfer belt 31 is controlled by the belt steering system.
The mechanism for tilting the first steering roller 34 is the same as the above described mechanism for tilting the second steering roller 35 . Therefore, it will not be described in detail. In this embodiment, each component of the mechanisms for tilting the first steering roller 34 and second steering roller 35 is fixed to a frame (unshown), which supports the belt unit 30 .
In this embodiment, the above described mechanism for controlling the tilting of the first steering roller 34 and second steering roller 35 , the first sensor 38 a and second sensor 38 b , etc., make up a tilt control unit 100 ( FIG. 6 ). The above described mechanism is made up of steering arm 101 , follower 102 , cam 103 , shaft (pivot) 104 , slider 105 , slide rail 106 , bearing holder 107 , steering motor 108 , spring 109 , etc. The steering motors of the mechanism for tilting the first steering roller 34 and second steering roller 35 are referred to also as the first steering motor 108 a and second steering motor 108 b , respectively.
6. Steering Control
Next, the control, in this embodiment, for compensating for the lateral and/or angular deviation of the intermediary transfer belt 31 is described (this control may be referred to simply as “steering control”).
FIG. 6 is a block diagram of the control sequence, in this embodiment, for compensating for the angular deviation of the belt, and the lateral deviation of the belt. In this embodiment, it is possible to compensate for the angular deviation of the belt and the lateral deviation of the belt at the same time. However, in order to make it easier to understand the control of the angular deviation of the belt, and the lateral deviation of the belt, the compensation for the angular belt deviation, and the compensation for the lateral belt deviation, are separately described, with reference to a situation in which compensation needs to be made for only the angular belt deviation, and a situation in which compensation needs to be made for only the lateral belt deviation.
6-1. Compensation for Angular Belt Deviation
First, the control for a situation in which compensation has to be made for only the angular belt deviation, that is, the control required when the belt angle is deviant from the target value, but, the average belt position is on the target value, is described.
First, the belt angle is obtained by subtracting the belt position signal from the second sensor 38 b of the tilt control unit 100 , from the belt position signal from the first sensor 38 a of the tilt control unit 100 .
Next, the belt angle obtained through the above-described process is subtracted from the target value (target belt angle), to obtain the amount of the angular deviation of the belt.
Next, with the calculated amount of angular belt deviation being used as an input, the amount by which the belt needs to be corrected in angle (attitude) is computed by an angular deviation controlling device C 1 made up of a PID compensator, etc., and control signals for correcting the belt in angle is outputted. The turning on or off of the outputting of the control command signal from the angular belt deviation controlling device C 1 is not illustrated. However, it can be turned on or off. In this embodiment, the control algorism, such as the algorism for controlling the PID (proportion/Integration/Differentiation) control, is optional. The details of operational expressions etc., are not described here.
The control command signals outputted from the angular deviation controlling device C 1 are inputted into the first and second steering motors 108 a and 108 b , respectively, to change the first and second steering rollers 34 and 35 in the same phase. That is, the first steering roller 34 and second steering roller 35 are simultaneously tilted in the same direction.
FIG. 7 is a schematic perspective view of the belt unit 30 when the first steering roller 34 and second steering roller 35 are simultaneously changed in angle in the same phase.
Here, “changing the first steering roller 34 and second steering roller 35 in angle in the same phase” means the following: Referring to FIG. 7 , it is assumed here that when the primary transfer surface H, which faces upward and is roughly horizontal as it is seen from the downstream side (second steering roller 35 side) in terms of the belt conveyance direction, and from the direction roughly parallel to the belt conveyance direction, the clockwise direction is referred to as +direction, and the counterclockwise direction is referred to as −direction. Thus, it means to tilt the first steering roller 34 and second steering roller 35 in the same direction, that is, +direction, or −direction. That is, when the first steering roller 34 is tilted in the direction +ST 1 , the second steering roller 35 is tilted in the direction +ST 2 ( FIG. 7( a )). Similarly, when the first steering roller 34 is tilted in the direction −ST 1 , the second steering roller 35 is tilted in the direction −ST 2 ( FIG. 7( b )).
Referring to FIG. 7( a ), it is assumed here that the first and second steering rollers 34 and 35 are tilted in the +direction at the same time (that is, first steering roller 34 is tilted in direction ST 1 , and second steering roller 35 is tilted in direction +ST 2 ). By the way, regarding the direction of change in the position of the intermediary transfer belt 31 in terms of its widthwise direction, the rearward direction is referred to as the +direction, and the frontward direction is referred to as the −direction. In this case, the direction of the change in the position of the intermediary transfer belt 31 in terms of its widthwise direction, which occurs on the first steering roller 34 , is the direction indicated by an arrow mark +Y 1 (rearward direction). Also in this case, the direction of the change in the position of the intermediary transfer belt 31 in terms of its widthwise direction, which occurs on the second steering roller 35 , is the direction indicated by an arrow mark −Y 2 (frontward direction). In this case, therefore, the change in the position of the first steering roller 34 in terms of its widthwise direction, which occurs on the first steering roller 34 is opposite to the direction of the change in position of the intermediary transfer belt 31 in terms of its widthwise direction, which occurs on the second steering roller 35 . The amount of angular belt deviation is the value obtained by subtracting the belt position signal outputted by the first sensor 38 a from the belt position signal outputted by the second sensor 38 b . Therefore, as the first and second steering rollers 34 and 35 are tilted, the angular belt deviation is corrected in the +direction. By the way, as the edges of the intermediary transfer belt 31 move rearward, the first and second sensors 38 a and 38 b displace rearward (+direction), as shown in FIG. 7( a ), and increase in output value.
On the contrary, in a case where both the first and second steering rollers 34 and 35 are simultaneously tilted in the −direction (that is, first steering roller 34 is tilted in the direction indicated by arrow mark −ST 1 , and second steering roller 35 is tilted in direction indicated by arrow mark −ST 2 ), the direction of the change in the position of the intermediary transfer belt 31 in terms of its widthwise direction, which occurs on the first steering roller 34 , is the direction indicated by arrow mark −Y 1 (frontward direction). On the other hand, the direction of the change in the position of the intermediary transfer belt 31 in terms of its widthwise direction, which occurs on the second steering roller 35 , is the direction indicated by an arrow mark +Y 2 (rearward direction). Therefore, also in this case, the direction in which the intermediary transfer belt 31 changes in position in terms of its widthwise direction, on the first steering roller 34 , becomes opposite from the direction in which the intermediary transfer belt 31 changes in position in terms of is widthwise direction, on the second steering roller 35 . Further, the angular belt deviation is corrected in the −direction.
FIG. 8 shows the changes in the position of the intermediary transfer belt 31 in terms of its widthwise direction, which occurred when the first and second steering rollers 34 and 35 are simultaneously tilted in steps in the +direction (+ST 1 and +ST 2 , respectively) as shown in FIG. 7( a ). The timing with which the first and second steering roller 34 and 35 are tilted is a timing indicated by an arrow mark S 1 . The first sensor 38 a displaces in the +direction, and the second sensor 38 b displaces in the −direction. Thus, the belt angle has substantially changed in the +direction. On the other hand, the two plots are roughly horizontal after the change in the angle of the intermediary transfer belt 31 in the + or −direction, and therefore, it has virtually no effect upon the average position of the intermediary transfer belt 31 , for the following reason. That is, the change in the position of the intermediary transfer belt 31 , which was caused by the first steering roller 34 , and that caused by the second steering roller 35 , are opposite in direction, and are the same in the amount by which the intermediary transfer belt 31 was laterally moved relative to the primary transfer surface H.
This simultaneous tilting of the first and second steering rollers 34 and 35 in the same direction is utilized as an actuator for the feedback control system for compensating for the angular belt deviation by detecting the amount of angular deviation of the intermediary transfer belt 31 . Thus, the angular belt deviation can be controlled without affecting the average belt position.
6-2. Compensation for Lateral Belt Deviation
Next, the control to be executed when compensation has to be made for only the average position of the intermediary transfer belt 31 , that is, when the intermediary transfer belt 31 has deviated in average position from the target position, and the belt angle is on the target value, is described.
First, the belt position signal outputted by the first sensor 38 a of the belt angle controlling unit 100 , and the belt position signal outputted by the second sensor 38 b of the belt angle controlling unit 100 are added to each other by the adder 86 to obtain the average belt position.
Next, the average amount of the lateral belt deviation is calculated by subtracting the average belt position obtained as described above, from the target value (target average position) for the average belt position.
Next, an average belt position controlling device C 2 made up of a PID compensator, etc., is used to calculate the amount by which the intermediary transfer belt 31 is to be changed in position, and control command signal for average belt position compensation are outputted. The turning on or off of the outputs of the control command signal is not illustrated. However, they can be turned on or off.
The control command signal outputted from the average belt position controlling device C 2 is inputted into the first steering motor 108 a while the first steering motor 108 a is rotated in the positive direction. Further, it is inputted into the second steering motor 108 b after being reversed by a reversing device 82 . Thus, the direction in which the first steering roller 34 is tilted becomes opposite from the direction in which the second steering roller 35 is tilted.
FIG. 9 is a schematic perspective view of the belt unit 30 when the first steering roller 34 and second steering roller 35 are changed in angle in the opposite direction relative to each other.
Here, “changing the first steering roller 34 and second steering roller 35 in angle in the opposite phase” means the following. It is assumed here that as the primary transfer surface H, which is roughly horizontal and faces upward, is seen from the downstream side (second steering roller 35 side) in terms of the belt conveyance direction, and also, from the direction which is roughly parallel to the belt conveyance direction, the clockwise direction is referred to as the +direction, and the counterclockwise direction is referred to as the −direction. Thus, it means to tilt the first steering roller 34 and second steering roller 35 in the opposite direction relative to each other. That is, when the first steering roller 34 is tilted in the direction indicated by an arrow mark −ST 1 , the second steering roller 35 is tilted in the direction indicated by an arrow mark +ST 2 ( FIG. 9( a )). Similarly, when the first steering roller 34 is tilted in the direction indicated by an arrow mark +ST 1 , the second steering roller 35 is tilted in the direction indicated by an arrow mark −ST 2 ( FIG. 9( b )).
Referring to FIG. 9( a ), in a case where the first and second steering rollers 34 and 35 are tilted in the opposite direction relative to each other (that is, steering roller 35 is tilted in −ST 1 direction, and second steering roller 35 is tilted in +ST 2 direction), the direction of the change in the position of the intermediary transfer belt 31 in its widthwise direction, which occurs on the first steering roller 34 , is the −Y 1 direction (frontward direction). Further, the direction of the change in the position of the intermediary transfer belt 31 in terms of its widthwise direction, which occurs on the second steering roller 35 is also −Y 2 direction (frontward direction). In this case, therefore, the direction of the change in position of the intermediary transfer belt 31 in terms of its widthwise direction, which occurs on the first steering roller 34 , and that on the second steering roller 35 , are the same. Also in this case, compensation is made for the average belt position in the −direction.
In comparison, referring to FIG. 9( b ), in a case where the first and second steering rollers 34 and 35 are tilted in the opposite phase from the above described one (that is, first steering roller 34 is tilted in +ST 1 direction, and second steering roller 35 is tilted in −ST 2 ), the direction of the change in the position of the intermediary transfer belt 31 in terms of its widthwise direction, which occurs on the first steering roller 34 is the +Y 1 direction (rearward direction). In this case, the direction of the change in the position of the intermediary transfer belt 31 in terms of its widthwise direction, which occurs on the second steering roller 35 , is also the +Y 2 direction (also, rearward direction). That is, the changes in the position of the intermediary transfer belt 31 in terms of its widthwise direction which occur on the first steering roller 34 , and those on the second steering roller 35 , are the same in direction. In this case, compensation is made for the average belt position in the +direction.
FIG. 10 shows the changes in the position of the intermediary transfer belt 31 in its widthwise direction, which occur when the first and second steering rollers 34 and 35 are tilted in steps in the −ST direction, and +ST direction, respectively, as shown in FIG. 9( a ). The timing with which the steering rollers 34 and 35 are tilted in steps is the timing S 2 in FIG. 10 . It is evident from FIG. 10 that both the first and second sensors 38 a and 38 b displaced in the −direction, and the average belt position changed in the −direction. Further, both plots in FIG. 10 overlap with each other, indicating that both the belt edge, the position of which is detected by the first sensor 38 a , and the belt edge, the position of which is detected by the second sensor 38 b , moved in the −direction. That is, this control has virtually no effect upon the angle of the intermediary transfer belt 31 , because the changes in the position of the intermediary transfer belt 31 in terms of its widthwise direction, which occur on the first steering roller 34 , and those on the second steering roller 35 , are the same in direction, and also, the amount by which the intermediary transfer belt 31 is laterally moved relative to the primary transfer surface H by the first steering roller 34 , and the amount by which the intermediary transfer belt 31 is moved relative to the primary transfer surface H by the second steering roller 35 are roughly the same.
The tilting of the first steering roller 34 , and the tilting of the second steering roller 35 , which are different in direction, are used as the actuator for controlling the feed back control system which compensates for the average belt position by determining the average belt position. Therefore, it is possible to control the average position without affecting the belt angle.
6-3. Compensation for Angular Belt Deviation and Lateral Belt Deviation
Next, it is assumed that the intermediary transfer belt 31 is deviant from target values in both its angle and average position. In this case, the operation for compensating for the angular belt deviation, and the operation for compensating for the lateral belt deviation, are carried out at the same time. Incidentally, it is assumed here that the system is linear in characteristic, and therefore, two operations can be carried out at the same time.
The amount of the control command for the first steering motor 108 a when compensation is made for both the lateral belt deviation and angular belt deviation at the same time is the sum of the following control command signals obtained by the adder 83 . The first is the control command signal (first angle control command signal) outputted from the belt angle control device C 1 , based on the detected amount of angular deviation, to control the first steering roller 34 in angle. The second is the control command signal (first position command value) outputted from the average belt position control device C 2 based on the average belt position to control the first steering roller 34 to compensate for the average belt position.
Further, the amount of control command for controlling the second steering motor 108 b when compensation is made for both the angular belt deviation and lateral belt deviation at the same time, is the sum of the following control signals obtained by the adder 84 . The first is the control command signal outputted from the belt angle control device C 1 based on the detected amount of angular belt deviation to control the first steering roller 35 in angle. The second is the control command signal (second position command value) outputted from the average belt position control device C 2 based on the detected average belt position to control the second steering roller 35 to control the intermediary transfer belt 31 in average position.
This is how the intermediary transfer belt 31 can be compensated for its angular deviation and lateral deviation.
6-4. Effects of Angular Belt Deviation and Lateral Belt Deviation
At this time, the effects of the angular belt deviation and lateral belt deviation upon the color deviation which might occur during a printing operation are discussed.
If the intermediary transfer belt 31 is deviant in angle from the target value, it results in color deviation. Thus, it is desired that the angular belt deviation relative to the target value is as close as possible to zero. In other words, in order to minimize color deviation, it is highly important to strictly control the belt angle in terms of absolute value. On the other hand, the lateral belt deviation has little effect upon color deviation, as long as the intermediary transfer belt 31 does not change in the average position while a given point of the intermediary transfer belt 31 is conveyed from the primary transferring portion T 1 Y of the image forming apparatus 20 Y, or the most upstream image forming apparatus 20 , to the primary transferring portion T 1 K of the image forming apparatus 20 K, or the most downstream image forming portion 20 . Therefore, need to strictly control the intermediary transfer belt 31 in position (absolute value of target value for average belt position) in terms of its widthwise direction is relatively low, as long as the intermediary transfer belt 31 does not deviate all the way to the lengthwise end of the belt supporting roller(s). Further, it is possible that if compensation is too quickly and excessively made for the lateral belt deviation, the compensatory operation itself will result in color deviation, in a case where the intermediary transfer belt 31 is suddenly changed in average position by the separating operation or contacting operation. Therefore, in order to minimize color deviation, it is desired that the control gain for compensating for the angular belt deviation is made as large as possible, whereas the control gain for compensating for the lateral belt deviation is made as small as possible within the range in which it is possible to prevent such problems that the intermediary transfer belt 31 is made by external disturbance or the like to displace itself all the way to the edge of the belt supporting roller(s), and/or excessively change in position.
An image forming apparatus is desired to output images which are virtually free of color deviation during a printing operation, and also, to be short in the length of time from when an operator gives a print start signal to when images begin to be outputted. Thus, it is necessary for the belt angle and average belt position will have reached their target values during the period between when the operator gives a print start signal and when the image forming apparatus begin to output images. In order to shorten the length of time between inputting of a print start signal by an operator to the outputting of images by the image forming apparatus, it is desired that the belt angle reaches the target value as fast as possible. In this chain of thought, it is effective to increase the control gain for the belt angle compensation. Further, in order to minimize the amount by which the intermediary transfer belt 31 has to be laterally moved for the compensation for the lateral belt deviation during a printing operation, it is effective to change the target value (target average position) for the average belt position, to the current average belt position, with such a timing that the belt conveyance speed becomes stable after the intermediary transfer belt 31 begins to be conveyed. Setting the target average belt position value (target average position) to the current average belt position makes it unnecessary to substantially change the average belt position to compensate for the lateral belt deviation. Therefore, it becomes possible to make the average belt position to quickly reach its target value to minimize the intermediary transfer belt 31 in lateral deviation. Thus, it becomes possible to reduce the length of time between when an operator inputs a print start command and when images begin to be outputted.
Further, the target average belt position can be changed to a position (normally, center value of belt in its widthwise direction), where it does not occur that the intermediary transfer belt 31 laterally deviates all the way to the edge of the belt supporting roller(s), at a speed permissible from the standpoint of preventing color deviation, after the target average position is changed to such a value as the value of the average belt position immediately after the intermediary transfer belt 31 became stable in conveyance speed. Therefore, it is possible to accomplish all of the objective of minimizing the length of time it takes for an image forming apparatus to output images after the inputting of a print start signal, the reduction in the color deviation attributable to the sudden change in the belt position in terms of the widthwise direction of the belt, and the objective of preventing the belt from laterally deviating all the way to the lengthwise end of the belt supporting roller(s). In this case, the speed with which the above described target average belt position is changed can be set as the speed which does not cause color deviation, to the following value(s). More specifically, the change in the position of the intermediary transfer belt 31 in its widthwise direction, which occurs while a given point of the intermediary transfer belt 31 moves between the adjacent image forming means (for example, between the primary transferring portions T 1 Y and T 1 K of the image forming portion 20 Y and 20 K, respectively), results in color deviation. Therefore, the speed with which the above described target average belt position is changed has only to be set so that the color deviation which occurs during this period can be kept at a target level or less.
6-5. Control Flow
FIG. 11 is a flowchart of the general operational sequence of an image forming operation. It shows the portion of the image formation sequence from when a print start command is inputted by an operator to when a printing operation ends.
First, a print start command is inputted by an operator (S 101 ). As the operation for conveying the intermediary transfer belt 31 is started (S 102 ), the target average belt position is changed to the current average position (S 103 ), whereby the amount by which the intermediary transfer belt 31 is to be changed in position in terms of its widthwise direction can be minimized, and therefore, image formation can be started sooner.
Next, both the operation for compensating for the lateral belt deviation, and the operation for compensating for the angular belt deviation, can be started at the same time (S 104 ). These operations are continued until the average belt position becomes stable at the target average belt position (S 105 ). As soon as the average belt position becomes stable at the target average belt position, the control for changing the target average belt position to the center value of the intermediary transfer belt 31 suspension, at a preset speed, is started (S 106 ). Here, regarding the preset speed, it is desired to be set to a value which is small enough not to make intolerably conspicuous the color deviation attributable to the change in the position of the intermediary transfer belt 31 in terms of its widthwise direction.
Next, until the belt angle becomes stable at a target value, the image formation is not started in any of the image forming portions 20 , and the operation for compensating for the angular belt deviation, and the operation for compensating for the lateral belt deviation are continued (S 107 ). As soon as the belt angle becomes stable at a target value, image formation is started in the image forming portions 20 (S 108 ). By the way, it may be before the starting of image formation or during image formation that the target average belt position reaches the center value.
As soon as images are formed on a preset number of sheets of transfer medium (S 109 ), the printing operation is ended (S 110 ). At the end of the printing operation, the conveyance of the intermediary transfer belt 31 is stopped, and the operation for controlling the intermediary transfer belt 31 in average position, and the operation for controlling the intermediary transfer belt 31 in angle, are stopped.
In this embodiment, the operations carried out by various portions of the image forming apparatus 1 are integrally controlled by the control portion 10 ( FIG. 1 ) of the image forming apparatus 1 . The control portion 10 has: a CPU as a computation controlling means; and memories (storage medium) such as RAM and ROM as storing means. It controls the operational sequence of each of various portions of the image forming apparatus 1 , according to the programs and data stored in the memories. For example, the control portion 10 activates the tilt control unit 100 , etc., with a preset timing to carry out the printing operation job (image forming operation to be started by print start signal to form an image on single or multiple sheets of transfer medium) from the beginning to the end.
Typically, the first and second steering rollers 34 and 35 are roughly the same in the absolute value (angle) of the angle b which they are simultaneously tilted in the same or opposite direction. However, in a case where the first and second steering rollers 34 and 35 are different in diameter and/or angle by which the intermediary transfer belt 31 wraps around them, and/or in the case of a steering mechanism which can steer the intermediary transfer belt 31 in parallel and/or perpendicular to the primary transfer surface H, even if the first and second steering rollers 34 and 35 are tilted by the same angle, the speed with which the intermediary transfer belt 31 is made to laterally shift by the first steering roller 34 and that by the second steering roller 35 sometimes do not become the same. Therefore, in a case where the two steering rollers 34 and 35 are tilted in the same direction and by the same angle, it sometimes occurs that not only the intermediary transfer belt 31 changes in angle, but also, lateral shift destination. Further, even if the two steering rollers 34 and 35 are tilted in the opposite direction by the same angle, it sometimes occur that the intermediary transfer belt 31 changes not only in its lateral shift destination, but also, angle, for the reasons given above.
Therefore, in a case where the first and second steering rollers 34 and 35 are different in diameter and/or angle of contact, and/or in the case of a steering mechanism which is capable of tilting the steering rollers 34 and 35 in parallel to the primary transfer surface H, they may be structured, as shown in FIG. 6 , so that before a command to begin driving the first and second steering rollers 34 and 35 is given, control gains b 1 and b 2 , which are for balancing the first steering roller 34 and second steering roller 35 in lateral belt shift speed, are given. That is, the control unit 10 may be structured so that one or both of the first and second steering rollers 34 and 35 are weighted in the absolute value of the angle by which they are tilted.
Here, the lateral belt shift speed is generated as the point at which the intermediary transfer belt 31 begins to wrap around a steering roller ( 34 or 35 ), and the point at which the intermediary transfer belt 31 separates from the steering roller ( 34 or 35 ) become different in terms of the direction parallel to the axial line of the steering roller. Therefore, compensation can be made using the inverse number of the ratio between the lateral shift speed of the first steering roller 34 and that of the second steering roller 35 when the two steering rollers 34 and 35 are set at the same in angle. Therefore, even if the belt unit 30 is such that its first and second steering rollers 34 and 35 are different in the lateral belt shift speed when the two rollers 34 and 35 are the same in angle of tilt, compensation can be highly precisely made for both the angular and lateral deviation of its intermediary transfer belt, for the following reason. That is, the speed with which the intermediary transfer belt 31 is laterally shifted by the first steering roller 34 in one direction, and the speed with which the intermediary transfer belt 31 is laterally shift by the second steering roller 35 in opposite direction, in order to compensate for the angular belt deviation, can be made permissibly close to each other.
As described above, the belt driving device 30 in this embodiment has the first and second steering rollers 34 and 35 , which are on the upstream and downstream sides of the image receiving surface (primary transfer surface) H, in terms of the belt conveyance direction, by which the intermediary transfer belt 31 receives images. The first sensor 38 a is for changing the intermediary transfer belt 31 in position in terms of the direction intersectional (roughly perpendicular, in this embodiment) to the belt conveyance direction. Further, the belt driving device 30 has the tilting means for separately tilting the first and second steering rollers 34 and 35 . In this embodiment, the tilting means is made up of the tilt control unit 100 , and blocks 80 - 86 , C 1 , C 2 , b 1 , b 2 , etc. Further, the belt driving device 30 has the first detecting means (which hereafter may be referred to as “belt angle detecting means”) for detecting the belt angle relative to the normal belt conveyance direction. In this embodiment, the belt angle detecting means is made up of the first sensor 38 a , second sensor 38 b , substracter 85 , etc. Further, the belt driving device 30 has the second detecting means (which hereafter may be referred to as “belt position detecting means”) for detecting the belt position in terms of the direction perpendicular to the belt conveyance direction. In this embodiment, the belt position detecting means is made up of the first sensor 38 a , second sensor 38 b , adder 86 , etc. The tiling means tilts the first steering roller 34 , based on the sum of the control amounts. The first one is the control amount for tilting the first steering roller 34 , based on the results of the detection by the belt angle detecting means, so that the first and second steering rollers 34 and 35 simultaneously tilt in the same direction. The second one is the control amount for tilting the first steering roller 34 based on the results of detection by the belt position detecting means, so that the first and second steering rollers 34 and 35 simultaneously tilt in the opposite direction relative to each other. Further, the tilting means tilts the second steering roller 35 , based on the results of the addition of the following control amounts. The first one is the control amount for tilting the second steering roller 35 , based on the results of detection by the belt angle detecting means, so that the first and second steering rollers 34 and 35 simultaneously tilt in the same direction. The next one is the control amount for tilting the second steering roller 35 , based on the results of detection by belt position detecting means, so that the first and second steering rollers 34 and 35 simultaneously tilt in the opposite direction relative to each other.
In this embodiment, the control gain based on the results of detection by the belt angle detecting means can be made greater than the control gain based on the results of detection by the belt position detecting means. Further, the belt driving device 30 may have a means which sets a target value for the results of detection by the belt position detecting means, to control the operation for tilting the first and second steering rollers 34 and 35 with the use of the tilting means. In this embodiment, the target value setting means is made up of the control portion 10 , etc. Further, this target value setting means sets the position (value) of the intermediary transfer belt 31 detected by the belt position detecting means after the intermediary transfer belt 31 began to be conveyed and became stable in conveyance speed, as the initial position (value) for the target value. Further, the target value setting means is provided with a referential value which corresponds to the referential belt position in terms of the direction perpendicular to the belt conveyance direction. The target value setting means can change the target value from the above described initial value to the above described referential value, at a preset rate.
Typically, the tilting means makes the first and second steering rollers 34 and 35 roughly the same in the absolute value of the angles by which they are tilted, as described above. However, the tilting means can be weighted in terms of the absolute value of the angles by which the first steering roller 34 and/or second steering roller 35 is tilted, as described above. Therefore, it is possible to make roughly the same the speed with which the intermediary transfer belt 31 is moved in the direction intersectional to the belt conveyance direction, by the tilting of the first steering roller 34 , and the speed with which the intermediary transfer belt 31 is moved in the direction intersectional to the belt conveyance direction, by the tilting of the second steering roller 35 , as described above. That is, simultaneously tilting the first and second steering rollers 34 and 35 in the same direction includes not only simultaneously tilting the first and second steering rollers 34 and 35 in the same direction by roughly the same angle in terms of absolute value, and also, simultaneously tilting them in the same direction by weighted angles in terms of absolute value. Similarly, simultaneously tilting the first and second steering rollers 34 and 35 in the opposite direction includes not only simultaneously tilting them in the opposite direction by roughly the same angle in terms of absolute value, but also, simultaneously tilting them in the opposite direction by the weighted angles in terms of absolute value.
To describe in further detail, in this embodiment, the tilting means is provided with controlling devices (C 1 , C 2 , etc.) which generate the following command values. The first is the first belt angle command value which is for tilting the first steering roller 34 based on the result of the detection by the belt angle detecting means. The next is the second belt angle command value which is for tilting the second steering roller 35 based on the result of the detection by the belt angle detecting means. The next is the first belt position command value which is for tilting the first steering roller 34 based on the results of the detection by the belt position detecting means. The next is the second belt position command value which is for tilting the second steering roller 35 based on the result of the detection by the belt position detecting means. In this case, the tilting means has the first adder 83 which adds the first position command value and the first belt angle command value, and the second adder 84 which adds the second position command value and the second belt angle command value. Further, the tilting means has the first driving means 108 which tilts the first steering roller 34 in response to the output of the first adder 83 , and the second driving means 108 b which tilts the second steering roller 35 in response to the output of the second adder 84 .
7. Comparison with Comparative Control
Next, the control in this embodiment is compared with a comparative control. A comparative image forming apparatus and its belt unit are practically the same in structure as those in this embodiment shown in FIG. 1 . However, the former is different from the latter in the control of the operation for compensating for the angular and lateral deviations of its intermediary transfer belt 31 .
FIG. 12 is a block diagram of the comparative control sequence for compensating for the angular belt deviation and lateral belt deviation. In the case of the comparative control, one (first steering roller 34 ) of the two steering rollers is driven based on the amount of the angular belt deviation, and, the other steering roller (second steering roller 35 ) is driven based on the amount of the lateral belt deviation.
The characteristics of the comparative corrective operation are as follows: Shown in FIG. 13 are the changes in the belt position detected by the first sensor 38 a and second sensor 38 b when the first steering roller 34 was tilted in steps in the +direction (+ST 1 ). The timing with which the first steering roller 34 began to be tilted in steps is a point S 0 in FIG. 13 . Referring to FIG. 13 , the belt position detected by the first sensor 38 a and that detected by the second sensor 38 b gradually changed in the −direction while increasing in the difference in the amount of lateral shift between the belt positions detected by the first and second sensors 38 a and 38 b , respectively. Thus, it is evident that in a case where only one steering roller is used to tilt the intermediary transfer belt 31 , the change in the average belt position and the change in the belt angle occurs at the same. Therefore, in a case where the tilting of a single steering roller is used as an actuator for the control for compensating for the angular belt deviation or lateral belt deviation, the following occurs. That is, the belt unit 30 becomes such a system that compensating for the angular belt deviation disturbs the belt unit 30 in terms of the belt position (comparison with FIG. 8 ), whereas compensating for lateral belt deviation disturbs the belt unit 30 in belt angle (comparison with FIG. 10 ). Therefore, it becomes difficult to precisely compensate for the angular belt deviation and/or lateral belt deviation.
Next, a case in which it is attempted to increase in gain the operation for compensating for the angular belt deviation in order to reduce an image forming apparatus in color deviation is discussed. In this case, increasing in gain the operation for compensating for the angular belt deviation increases the belt unit 30 not only in the performance to compensate for the angular belt deviation, but also, the amount by which the belt unit 30 is disturbed in belt position. Therefore, it possibly causes the intermediary transfer belt 31 to laterally shift all the way to the end of the belt supporting roller(s), and/or the operation will fail. In reality, therefore, it is impossible to increase in gain the operation for compensating for the angular belt deviation as much as necessary. In other words, in the case of the comparative operation, it is difficult to improve the belt unit 30 in the performance to compensate for the angular belt deviation. In comparison, in the case of the control in this embodiment, compensation for the angular belt deviation is made by tilting two steering rollers. Therefor, the compensation can be made without disturbing the intermediary transfer belt in position in terms of its widthwise direction. Therefore, even if the operation for compensating for the angular belt deviation is substantially increased in control gain, it does not cause the belt to lateral shift all the way to the lengthwise end of the belt supporting roller(s), nor to cause the operation to fail, by its interaction with the operation for compensating for the angular belt deviation. Therefore, it can be made substantially greater in control gain, compared to the comparative operation. That is, the operation, in this embodiment, for compensating for the angular belt deviation is greater in performance than the comparative one. Therefore, the employment of the control in this embodiment can substantially reduce an image forming apparatus in the length of time it takes for the apparatus to begin image formation after the inputting of a print start signal, compared to the comparative operation, and also, can prevent color deviation.
Next, the comparative operation is described regarding a case in which in order to reduce the length of time it takes for image formation to be started after a printing start command is given, the target average belt position is changed to the current belt position, with the timing with which the belt becomes stable in conveyance speed after the belt begins to be conveyed. In this case, as the target average belt position is changed, the belt is corrected (changed) in position based on the new target average belt position. In the case of the comparative control operation, however, the belt is affected in angle. That is, it does not occur that compensation is made for only the lateral belt deviation as intended. Therefore, even if the average target position is slowly changed in order not to cause the color deviation attributable to the change in belt position, the belt unit is affected in belt angle which has direct effect upon color deviation. Therefore, the change in the target average belt position results in the occurrence of color deviation. In comparison, in the case of the control in this embodiment, it is possible to compensate for the lateral belt deviation, based on the information regarding the belt position, without affecting the belt angle. Therefore, it does not cause problems such as those described above. In other words, by changing the target average belt position with the use of the control in this embodiment, it becomes possible to reduce the length of time it takes for image formation to be started after a print start command is given, without negatively affecting an image forming apparatus in terms of the color of a full-color image.
Embodiment 2
Next, another embodiment of the present invention is described. The belt driving device and image forming apparatus in this embodiment are basically the same in structure as those in the first embodiment. Therefore, the components of the belt driving device and image forming apparatus in this embodiment, which are the same as, or equivalent to, the counterparts in the first embodiment, in function and structure, are given the same referential codes as those given to the counterparts, and are not described in detail.
For example, if the two steering rollers are different in the material of their surface layer, they become different in the manner in which a belt slides on a roller. Thus, it sometimes occurs that the two steering rollers temporarily become different in properties, and/or the change in the alignment of the intermediary transfer belt affects only one of the two steering rollers. In such a case, there occurs sometimes a cross-talk between the compensation for the angular belt deviation and the compensation for the lateral belt deviation.
In a case where there is cross-talk between the compensation for the angular belt deviation and the compensation for the lateral belt deviation, it is effective to alternately and independently carry out the operation for compensating for the angular belt deviation by simultaneously tilting the first and second steering rollers 34 and 35 in the same direction, based on the amount of the angular belt deviation, and the operation for compensating for the lateral belt deviation by simultaneously tilting the first and second steering rollers 34 and 35 in the opposite direction, based on the detected belt position.
By independently and alternately carrying out the operation for compensating for the angular belt deviation and the operation for compensating for the lateral belt deviation, it is possible to highly precisely compensate for the angular belt deviation and lateral belt deviation while minimizing the possibility that the control is nullified by the cross-talk.
FIG. 14 is a block diagram of the control sequence in this embodiment, for compensating for the angular belt deviation and lateral belt deviation. Each of the operation for compensating for the angular belt deviation, and the operation for compensating for the lateral belt deviation, is the same as the counterpart in the first embodiment. However, this embodiment is different from the first embodiment in that in this embodiment, switches SW 1 and SW 2 are provided in place of the adders 83 and 84 , in the first embodiment, for adding the control commands.
When it is necessary to compensate for only the angular belt deviation, both the switches SW 1 and SW 2 are flipped upward in FIG. 14 (side which connects belt angle controlling devices C 1 to first and second steering motors 108 a and 108 b (or control gains b 1 and b 2 ). On the other hand, when it is necessary to compensate for only the lateral belt deviation, both the switches WW 1 and SW 2 are flipped downward in FIG. 14 (side which connects average belt position controlling device C 2 to first and second steering motor 108 a and 108 b or control gains b 1 and b 2 ).
In other words, this embodiment makes it possible to select the control command for the belt angle compensation, or the control command for the belt position compensation, in order to selectively carry out the operation for compensating for the angular belt deviation, or the operation for compensating for the lateral belt deviation, respectively.
FIG. 15 is a flowchart of the general operational sequence from when a print start command is given by an operator, to when the printing operation ends.
A print start command is given by an operator (S 201 ). As the intermediary transfer belt 31 begins to be conveyed (S 202 ), first, the target average belt position is changed to the value of the current average belt position (S 203 ), whereby it becomes possible to minimize the amount by which the belt has to be changed in position, and therefore, it is possible to reduce the length of time it takes for the image forming apparatus to start forming images after the print start command is given.
Next, only the operation for compensating for only the lateral belt deviation is started (S 204 ). By the way, in the operation for compensating for only the lateral belt deviation, the control which changes, at a preset speed, the target average belt position to the center value of the suspension of the intermediary transfer belt 31 is also carried out. This operation is continuously carried out until the average belt position settles at the target average belt position (S 205 ). As soon as the average belt position settles at the target value, the operation for compensating for the lateral belt deviation is stopped (S 206 ), and the operation for compensating for only the angular belt deviation is started (S 207 ). This operation is continued alone until the belt angle settles at the target angle (S 208 ). As soon as the belt angle settles at the target angle, the operation for compensating for only the angular belt deviation is ended (S 209 ), and image formation is started in the image forming portions 20 (S 210 ).
Even during an image forming operation, the operation for determining whether or not the belt position is stable at the average target position (S 211 ), and the operation for determining whether or not the belt angle is stable as the target angle (S 214 ), are alternately repeated. If it is determined that the belt unit is not stable in the belt angle, or belt position, the operation for compensating for the lateral belt deviation, and the operation for compensating for the angular belt deviation are carried out (combination of S 212 and S 213 , and combination of S 215 and S 216 ).
As soon as the image forming operation is carried out for a preset number of sheets of transfer medium (S 217 ), the printing operation is ended (S 218 ). When the printing operation is ended, the conveyance of the intermediary transfer belt 31 is also ended.
By independently and alternately carrying out the operation for compensating for the angular belt deviation, and the operation for compensating for the lateral belt deviation, it is possible to highly precisely compensate for the angular belt deviation and lateral belt deviation, while minimizing the possibility that the belt control is nullified by cross-talk, even if there is cross-talk. Further, because it is possible to highly precisely compensating for the angular belt deviation and lateral belt deviation, it is possible to reduce the length of time it takes for an image forming apparatus to start image formation after a print start command is given, and also, to prevent the apparatus from outputting images suffering from color deviation.
As described above, the tilting means can alternately carry out the operation for simultaneously tilting the first and second steering rollers 34 and 35 in the same direction, based on the result of the detection by the belt angle detecting means, and the operation for simultaneously tilting the first and second steering rollers 34 and 35 in the opposite direction, based on the result of the detection by the belt position detecting means. In this case, the tilting means is provided with controlling devices (C 1 , C 2 , or the like) which generate the belt angle command value and belt position command value, and a selecting devices (SW 1 , SW 2 , or the like) for selecting one of the belt angle command value and belt position command value, respectively. Also in this case, the tilting means is provided with first and second driving means 108 a and 108 b for tilting the first and second steering rollers 34 and 35 , respectively, in response to the belt angle command value or belt position command value, which is selected by the selecting device.
Miscellaneous
In the foregoing, the present invention was described with reference to concrete embodiments of the present invention. However, these embodiments are not intended to limit the present invention in scope.
According to the present invention, the two steering rollers are simultaneously tilted in the same direction, based on the information regarding the belt angle, in order to compensate for the angular belt deviation, or the two steering rollers are simultaneously tilted in the opposite direction, based on the information regarding the belt position, in order to compensate for the lateral belt deviation. In this context, the present invention can be embodied in the form of a belt driving device, and also, an image forming apparatus, which are entirely or partially different in structure from those in the preceding embodiments. In other words, the present invention is compatible with any belt driving device which employs an endless belt, whether the belt is used as an intermediary transfer belt (intermediary transferring member), a transfer medium conveying belt (transfer medium bearing member), a transfer belt (transferring member), a photosensitive belt (image bearing member), or the like. Further, the present invention is also compatible with any image forming apparatus which employs an endless belt which is steered with steering rollers, whether the apparatus is of the tandem/singe drum type, or intermediary transfer/transfer medium conveyance type. In the description of the preceding embodiments of the present invention, only the portions of the image forming apparatus, which are related to the formation of a toner image, and the transfer of the toner image, were described. However, the present invention is applicable to various image forming apparatuses such as printers, copying machines, faxes, multifunction image forming apparatuses, etc., which are combinations of the above described portion, and additional devices, equipments, casing, etc. Further, the above described embodiments are not intended to limit the present invention in the number of image forming portions.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims priority from Japanese Patent Application No. 127991/2013 filed Jun. 18, 2013, which is hereby incorporated by reference.
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A belt driving device includes first and second steering rollers to stretch an endless belt, first and second pivoting mechanisms, and first and second detecting members to detect a position of the belt A first setting portion sets first and second pivoting instruction values through which the first and second steering rollers are pivoted in the same direction, and a second setting portion sets third and fourth pivoting instruction values through which the first and second steering rollers are pivoted in the opposite directions. A controller pivots the first steering roller by the first pivoting mechanism on the basis of an addition value of the first pivoting instruction value and the third pivoting instruction value, and pivots the second steering roller by the second pivoting mechanism on the basis of an addition value of the second pivoting instruction value and the fourth pivoting instruction value.
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This invention relates to ammunition projectiles with sabots and specifically to process for making such projectiles.
BACKGROUND AND SUMMARY OF INVENTION
The conventional Phalanx ammunition round includes an expensive projectile. The projectile has a heavy metal core ("penetrator") designed to penetrate metallic armour and within a surrounding light plastic sabot designed to allow the penetrator to be fired from a large diameter barrel bore so as to have the propelling pressure act over a bigger area and thus produce a bigger force on the penetrator which in turn gives greater acceleration and ultimately higher velocities to the penetrator. The projectile also has a pusher plug designed to impart spin to the penetrator to enhance penetration and designed to protect the penetrator base from contact by the hot propellant gases during firing. In order to minimize cost, this pusher plug is conventionally aluminum and has a ringshaped rotating band around it to protect the gun barrel from aluminum fouling which might otherwise occur if the aluminum pusher plug were to directly contact the barrel bore. In order to be most effective, it is necessary that the rotating band, penetrator (projectile core), pusher plug and sabot all be aligned with each other, and especially the rotating band and projectile core. If the core and band are misaligned even slightly, the spin-up of the projectile about the axis of the rotating band will result in wobbling of the core and resultant inaccuracy. The conventional Phalanx round has many advantages, but also has one disadvantage. The round tends to wobble down the barrel bore. The importance of such a discovery should not be underestimated. The Phalanx gun is the gun currently used by the Navy to shoot down incoming cruise missiles by firing at rates of 3,000 rounds per minute. Inaccuracy could conceivably lead to the crucial ones of those thousands of rounds missing the target with resultant loss of an aircraft carrier or other extremely vital naval vessel together with its crew. It is a major accomplishment that the present invention has effectively minimized barrel wobble due to the misalignment above noted and has done so at reduced cost, thus allowing for more rounds of better ammunition to be acquired within the same defense budget.
The invention achieves this end by providing a manufacturing method in which the core, sabot, plug and band are all simply, effectively and automatically aligned with each other so that misalignment is effectively eliminated. The invention also allows for an unstressed sabot in contrast to the conventional sabot which is highly stressed when assembled. High sabot stresses before loading and firing are advantageously avoided by the invention thus eliminating conventional misalignments caused by uneven stress-strain properties within the sabot.
BRIEF DESCRIPTION OF DRAWING
The invention will be better understood by reference to the attached drawing in which the FIGURE is a diametrical cross-sectional view taken along the longitudinal axis of a projectile 10 in position for molding within a mold 12.
DETAILED DESCRIPTION
Referring to the FIGURE, projectile 10 comprises a projectile core ("penetrator") 14, a pusher plug 16, a rotating band 18 about the plug 16, a discarding sabot 20, surround core 14 and a projectile nose cover 22, the purposes of which have been described above except nose cover 22 which is aluminum, plastic or other protective material designed to protect the nose of the projectile from abrasion or supersonic heating during flight, especially where the penetrator 14 is made of an incendiary material like depleted uranium. Alternatively cover 22 may be an incendiary material to aid the "burning" action necessary to penetrator armour. Projectile 10 can have any desired external shape such as the exemplary modified Phalanx shape shown.
The sabot 20 of projectile 10 abuts against pusher 16, whereas in conventional Phalanx ammunition there is a gap between the rear (top as shown) of the sabot 20 and the front (bottom as shown) of the plug 16, the size of the gap being a function of the amount of pre-stress on the conventional Phalanx sabot. The invention is applicable to other rounds than the modified Phalanx projectile shown.
Mold 12 comprises a main body 23, an upper alignment body 24, a holder 26 and an ejector 28. Main body 22 has a tapered circular interior cavity wall 30 which has the desired exterior sabot shape. Upper alignment body 24 is a hollow cylindrical body with upper and lower inside walls 32, 34 separated by an upwardly facing interior annular abutment shoulder 36 which is carefully coaxially aligned with the axis of the cavity 30 of main body 22 when bodies 23 and 24 are joined. Wall 32 is of just slightly larger diameter than the outside diameter of band 18 while wall 34 is of a smaller diameter just slightly larger than the outside diameter of the sidewall of pusher plug 16 in front of band 18. Shoulder 36 is downwardly tapered in conformance with the front edge of band 18. The fit between wall 34 and plug 16 and between band 18 and shoulder 36 is preferably tight enough that a minimum amount of molding medium enters the space there between. Bodies 23 and 24 cooperate to define mold openings 36 (preferably four openings spaced 90° apart) therebetween. Bodies 23 and 24 can be a single integral piece if desired. Conventional flow control means and plastic supply, timing, heating means (not shown) would be used to control flow through mold 12. Holder 26 is a simple push cup 38 or other pressure plate means for holding band 18 against shoulder 36 during molding. This holding action, together with the fixed alignment between shoulder 36 and cavity wall 30 results in an aligned band, plug and sabot. Alignment between core 14 and the other components (especially band 18) is achieved by pre-aligned fit between plug 16 and core 14 which is achieved by a jig guaranteeing such alignment or by a high tolerance force fit between a frontal plug recess 40 and core 14. Plug 16 and core 14 can be preassembled as a unit and alignment checked easily since the core 14 is not yet hidden by the sabot 20 at that stage of the process.
With the aligned core, plug and band held in place by holder 26, the molding is accomplished to produce an aligned, unstressed sabot. At this stage it will be appreciated that a major advance over the prior art has been made in that an accurate, uniform and reliable alignment of all projectile components is achieved. Since the sabot is unstressed this alignment is not likely to change and the sabot is not likely to crack prematurely due to unexpected overstressing. The holder 26 is now released and ejector 28 is raised to shove the completed projectile from the mold.
ADVANTAGES OF THE INVENTION
Concentricity (alignment) is assured. The sabot is not a separate component so inspection load is lightened. The sabot is not in a highly prestressed material state as it is when it is assembled conventionally either in "drill and pin" or welded configurations, thus reducing the likelihood of in-field cracking problems. The external configuration has no gap between sabot and pusher plug to collect debris which might later damage a barrel. The molding-in-place process of the invention produces intimate contact between the sabot and the pusher plug to increase joint strength thereby increasing resistance to torque, bending and tensile forces. Also a hermetic seal is provided about the projectile to prevent contamination from or to the projectile core (penetrator). Consistency of sabot separation is improved since the stress levels are uniform and low (resulting on from material shrinkage during mold curing). Regrind plastic (surplus) can be used.
In short, a much better projectile at much less cost is available as a result of the invention.
In view of the substantial benefit to the public to be produced by this invention and in view of its surprising superiority, this invention is to be understood as being quite broadly entitled to a wide range of equivalents in terms of apparatus within the scope of the overall methods claimed below.
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A method of manufacturing a sabot projectile is disclosed. The projectile core is used as the core pin of a mold and the sabot is molded directly onto and in alignment with the projectile core.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of PCT/US98/14701, filed Jul. 13, 1998, which claims the benefit of U.S. Provisional Application No. 60/057,712 filed on Aug. 27, 1997.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of dental instruments and more particularly to dental wedges.
2. Related Art
Dental wedges are well known in the art and have been used in restorative dentistry for over a century. Generally, dental wedges are used to separate the teeth and hold a matrix band against the side of the tooth being restored or repaired. These functions are important for the successful restoration of the form and function of teeth. Unless adequate separation of the teeth is achieved, the adjacent teeth, once restored, will inadequately contact one another. Without adequate contact between the teeth, food will pack and otherwise accumulate in between the teeth, leading to decay and periodontal problems. Moreover, unless the matrix band conforms adequately to the side of the tooth, filling material can be forced below the gum line or leave the tooth with unnatural and irregular contours known as ledges, overhangs, and underhangs. These flaws aid and cause plaque accumulation, leading to decay and periodontal problems.
To prevent these problems, the dentist uses a wedge, which is typically piece of wood or plastic of a basic tetrahedral shape, thus tapered to a point on one end. In use, a wedge is inserted into the space between the adjacent teeth at the gum line and forced into the space to cause separation of the teeth so that they may be restored. This causes the matrix band material to be pressed against the gingival portion of the tooth at the floor of a preparation, thereby closing the space and preventing the overhang.
The ideal dental wedge should be relatively hard in order to drive the teeth apart at least the thickness of the average matrix band (approximately 0.002 inch). When the wedge and matrix band are removed, the restored teeth should rebound to their normal physiological position due to the elastic memory of the periodontal membrane and maintain physiologic contact in order to prevent food debris from packing between the teeth during chewing. The wedge should also provide resistance against the matrix band so as to prevent deformation or dislodgment due to the outward pressure a dentist typically exerts when packing restorative materials in the matrix-confined cavity space.
Most commercially available dental wedges are a basic tetrahedral shape and made of various types of wood. To accommodate different sizes of interproximal spaces, wedges are generally available in various sizes from small to large and the size used is determined by the size of the interproximal space. While these wedges are hard enough to allow the teeth to be driven apart, they suffer from the problem of not conforming adequately to the interproximal surface of the tooth.
Another basic requirement of a dental wedge is that it be able to cause the matrix band to intimately conform to the anatomical surfaces of the tooth to be restored. Often, the interproximal surface of the tooth will be concave. Wherever a dental wedge does not intimately contact the flexible matrix band and force it against the concave surface of the tooth, the band is unsupported. In such a condition, a gap or opening will develop in response to the pressure of packing the restorative material into the matrix-confined cavity preparation. These gaps allow the filling material to push past the matrix and create a ledge, overhang, or an otherwise unacceptable contour of the tooth in the interproximal space. Further, the gaps allow blood and other fluids to enter the band, thereby contaminating the restorative materials, which results in a compromised restoration as explained below. Rigid, fixed-shaped wedges or wedge type devices known in the art do not adapt well to the variable contours of the interproximal spaces.
A further problem of the present art is that the insertion of the rigid wedge is detrimental to the interproximal gingival tissues. Gingival tissue is soft and displaceable. Thus, a rigid wedge design does not accommodate the gingival tissue and simply and traumatically displaces the tissue, resulting in upward force on the teeth walls. Tearing the gingival tissue permits blood, saliva, and other contaminants to flow into the preparation cavity. Because dental restorative materials only function optimally when dry, the service and longevity of the restoration are compromised.
The dental wedge must also be easily removed from the interproximal space between the teeth. While a wedge that resists backing out is a desired characteristic of wedges, such a characteristic makes the wedge more difficult to remove from between the teeth. To accommodate placement and removal, a wedge may include a small protuberance which is adapted to be grasped by an implement such as pliers, as seen in U.S. Pat. No. 4,696,646. Easy placement and removal further reduces trauma to the gingival tissue, which results in a cleaner and drier work surface. Further, a flexible wedge that forces the band against the concavities of the interproximal tooth seals the preparation cavity against fluid seepage due to any incidental trauma that might occur.
Numerous attempts have been made to accommodate the varying interproximal surfaces of teeth, while avoiding trauma to the soft tissues and maintaining adequate stiffness to remain in place. Most dental wedges, however, share the common problem that they adhere to the basic tetrahedral shape, which on the inferior surface of the tetrahedron typically causes trauma to the gingival tissues upon surface. The wedge described in U.S. Pat. No. 3,890,714, however, includes less surface area on the side of the wedge communicating with the gingival tissue. This wedge suffers from three problems. First, the wedge body is substantially hollow, which results in ineffectual strength for conforming a matrix band to any tooth defects and insufficient strength to place the wedge and to separate the teeth. Second, the wedge does not include a protuberance for grasping the wedge with dental pliers or the like, which makes removal of the wedge particularly difficult. Third, the wedge has a tendency to back out of the interproximal space, thereby interrupting the dentist who must re-insert the wedge.
SUMMARY OF THE INVENTION
The present invention provides a one-piece dental wedge which is capable of separating adjacent teeth and conforming a matrix band to the irregular surfaces of the tooth being restored, and doing so with minimal compression of gingival tissue between the teeth. This dental wedge possesses elastic properties which enable it not only to recover deformation but also rebound to the irregular contours of the tooth being repaired. The elasticity enables the wedge to be forced between two teeth and then expand into a concave, interproximal surface in one of the teeth with enough force to cause a matrix band to adapt to the interproximal contours.
The present wedge comprises a one-piece substantially tetrahedral body having a small protuberance on its blunt end adapted to be grasped by a dentist's implement for accommodating placement and removal of the wedge. In an aspect of the invention, a tapering V-shaped interior cut out from the side of the tetrahedron in communication with the gingival tissue. Preferably made from plastic, the wedge is firm enough to provide resistance to compression when wedged between two teeth, and also capable of rebounding from compression to conform to the contours of two surfaces.
An alternative embodiment of the present wedge according to the invention is similar to the wedge described above but includes a series of serrations formed on the outer surface, as well as a bottom surface rear portion angled upwardly generally parallel to the top surface from approximately a mid point of the bottom surface of the wedge to the proximal end portion, which includes the small protuberance adapted to be grasped by a dentist's implement. The series of serrations provide traction for the wedge when it is inserted between adjacent teeth to prevent the wedge from backing out of the interproximal space. Further, the wedge includes a rounded distal leading point for a wider body without unnecessary length, as well as for promoting safe insertion of the wedge between the adjacent teeth.
Other objects, features, and advantages of the invention will be apparent from the ensuing description in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
The invention will now be described with reference to the drawings in which:
FIG. 1 is a side elevational view of the wedge according to the prior art;
FIG. 2 is cross sectional view taken along line 2--2 of FIG. 1;
FIG. 3 is a front elevational view of the wedge of FIG. 1;
FIG. 4 is a side elevational view of a wedge according the invention;
FIG. 5 is an end elevational view of the wedge of FIG. 4;
FIG. 6 is a cross sectional view taken along line 6--6 of FIG. 4;
FIG. 7 is a top plan view of the wedge of FIG. 4;
FIG. 8 is a cross section of the wedge similar to FIG. 6, in use between two teeth;
FIG. 9 is a top plan view of the wedge of FIG. 4 in use between two teeth;
FIG. 10 is a side elevational view of a wedge according to a further embodiment of the invention; and
FIG. 11 is a bottom elevational view of the wedge of FIG. 10.
DETAILED DESCRIPTION
A dental wedge 100 of the prior art is illustrated in FIGS. 1-3. The wedge 100 has an overall tetrahedral shape including a substantially flat lower surface 102 which is prone to cause trauma to the gingival tissue 36 upon insertion between two teeth 32. A dental wedge 10 of the present invention is shown in FIGS. 4-9. Looking first at FIGS. 4-7, it can be seen that the wedge 10 includes a body 20, which tapers overall from a proximal end portion 12 to a distal leading point 14.
As illustrated by FIGS. 8 and 9, the wedge 10 is positioned within an interproximal space 30 between teeth 32 and superior to the gingival tissue 36. As shown in FIG. 9, the teeth 32 include a concave defect 40, which is a typical depressed surface on the sides of the teeth 32 facing the interproximal space.
The body has a longitudinal apex 26 about which it is symmetrical in plan view, as illustrated in FIG. 7. Looking also at FIGS. 4-6 again, the wedge 10 has a generally elongated tetrahedral shape, including an inferior face 18 and two symmetrical side faces 22 and 24. The side faces 22, 24 are triangular and planar. The inferior face 18, on the other hand, has a shallow recess 16, which tapers from its greatest depth at the end portion 12 to the leading point 14. Thus, a lower portion of the side faces 22, 24 form relatively thin walls 23, 25 which bound the shallow recess 16. The walls 23, 25 are structurally thin enough to flex in response to pressures exerted by adjacent teeth 32, to conform to any irregular shape on the teeth 32, and to rebound upon relief from such pressure as in a concavity on an adjacent tooth. Further, the walls' resiliency is strengthened by a solid body portion 34 extending between the apex 26 and a concave face 42 partially defining the shallow recess 16.
The end portion 12 of the wedge 10 includes a protuberance 28, adapted for engagement by a suitable implement for easy placement of the dental wedge into the interproximal space 30 between teeth 32. The protuberance 28 comprises a flat upper surface 38 and a corresponding flat lower surface 39.
As illustrated by FIGS. 10 and 11, a further embodiment of a dental wedge, according to the invention is shown. As shown in FIG. 10, a dental wedge 110 includes a body 120 that tapers overall from a proximal end portion 112 to a distal leading point 114.
The body 120 has a longitudinal axis of symmetry in plan view. Further, the wedge 110 has a generally elongated tetrahedral shape, including a lower face 118 and two symmetrical side faces 122, 124. A lateral cross-section of the body 120 is generally triangular, and the lower face 118 has a shallow recess 116 that tapers from its greatest depth at the proximal end portion 112 to the leading point 114. Thus, a lower portion of the side faces 122, 124 form relatively thin walls 123, 125 that bound the shallow recess 116. Preferably, the walls 123, 125 are structurally thin enough to flex in response to pressures exerted by adjacent teeth 32, whereby they are adapted to conform to any irregular shape on the teeth 32, and rebound upon relief from such pressure as in a concavity on an adjacent tooth. Further, the walls' resiliency is strengthened by a solid back portion 134 extending between the apex 126 and a concave face 142 partially defining the shallow recess 116.
The end portion 112 of the wedge 110 includes a protuberance 128, which is adapted for engagement by a suitable implement for easy placement of the dental wedge 110 into an interproximal space 30 between adjacent teeth 32. The protuberance 128 comprises preferably a flat upper surface 138 and a corresponding flat lower surface 139. The leading point 114 is preferably rounded, whereby it is safer for insertion within an interproximal space with a lower risk of gingival trauma than a sharp point as shown in the prior embodiment.
The side faces 122, 124 defining the body 120 have a textured outer surface 170 to prevent backing out of the wedge 110 from the interproximal space 30, preferably formed of a series of angled serrations 180, which define an outer surface notched with tooth-like projections. Alternatively, the textured outer surface may be knurled or rippled. The angled serrations 180, each of which provides a ramped surface 172 adapted to ease insertion of the wedge 110 and an edge 174 at the end of each ramped surface 172 to resist removal of the wedge, are specifically adapted to resist backing out once placed within the interproximal space 30. By the inclusion of the protuberance 128, however, wedge 110 is simply removable by a suitable dental implement. Thus, the textured outer surface 170 provides traction for resisting inadvertent outward movement of the wedge 110 from the interproximal space, which aids the wedge in providing adherence of the matrix band 50 to the defects of the teeth 32.
The lower portion of the side faces 122, 124 on the lower face 118 include a rearward portion 119 that extends rearwardly from an intermediate portion 121 toward the end portion 112 at an angle relative to a forward portion 129 that extends forwardly from the intermediate portion 121 toward the distal leading point 114. The intermediate portion 121 may be a point, but preferably represents a zone of engagement where a minimal portion of the lower edge 118 is presented to the gingival tissues when the wedge is inserted between the teeth.
It is important to note that for each of the two embodiments described above, the combination of certain features according to the invention are not unique to one embodiment or the other. For example, the first embodiment might include serrations but not an angled lower surface; or, the second embodiment might include an angled lower surface but no serrations. Thus, the features described with reference to a particular embodiment may be incorporated into the other embodiments, in whole or in part, as should be well understood by one of skill in the art.
Preferably, the wedge 10 is made of a polymer plastic. However, it is entirely within the scope of the present invention to form the wedge from many other types of materials, such as synthetics, other plastics, or wood. The only requisite is that there be sufficient resilience to permit flexure of the walls 23, 25.
Use of the dental wedge is best shown in FIGS. 8 and 9. While the wedge 10 is shown, FIGS. 8 and 9 apply equally well to the wedge 110, as does the following description. The wedge 10 is first placed between adjacent teeth 32, with the leading point 14 inserted first, and positioned to provide adequate separation between the teeth 32. Using pressure from a dental implement (not shown) on the protuberance 28, the wedge 10 is inserted between two teeth 32 until resistance is felt.
As is well known, separation between the teeth 32 is necessary to compensate for the thickness of a matrix band 50 used in restorative dentistry. The matrix band 50 is placed around a tooth 32 and a dental wedge 10 is inserted between the tooth 32 and the adjacent tooth 32 to separate the teeth 32 and conform and hold the matrix band 50 against the tooth 32 to be restored. When the wedge 10 is inserted, the walls 23, 25 flex into the groove 16 as the faces 22, 24 engage the matrix band 50 surrounding the teeth 32. When the faces 22, 24 meet a concave irregularity on the tooth 32, the walls 23, 25 carrying the faces at a lower portion of the wedge rebound and conform the matrix band 50 to the irregularity.
To remove the wedge 10 from the interproximal space 30, a dental implement (not shown) will simply grasp the protuberance 28, clamping into it at the upper and lower surfaces 38, 39, and pull the wedge 10 from between the teeth 32. The teeth 32 will rebound to their normal physiological position due to the elastic memory of the periodontal membrane and maintain physiologic contact with adjacent teeth 32 in order to prevent food debris from packing between the teeth during chewing.
Reasonable variation and modification are possible within the spirit of the foregoing specification and drawings without departing from the scope of the invention.
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The dental wedge includes a generally tetrahedral body having a central longitudinal apex flanked by a pair of resilient side walls, connecting a narrow distal point and a wider proximal end, and having an open underside opposite thereto, as well as a protuberance extending axially from the proximal end and adapted for gripping by a dental implement.
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FIELD
[0001] The present invention relates to a pin. In particular, the invention relates to a pin having reduced areas for dirt ingress for use in a barrier such as a safety barrier or the like.
BACKGROUND
[0002] Pins are used in safety barriers to secure together discrete components, such as posts and rails of a barrier system. Such barriers systems may, for example, be designed to prevent shelving from being directly impacted by vehicles.
[0003] To improve stability, pins are commonly locked into place by the rotation of the pin. A tool, such as a screwdriver, is normally used to provide increased mechanical advantage for the rotation of the pin in order to achieve sufficient tightening and to enable the pin to be removed.
[0004] The interaction between a pin and a tool is normally in the form of cooperating male and female components. Usually, the pin contains the female component and the tool the male component. Engagement of the tool and the pin requires that the surfaces of the components abut such that rotation of the tool causes the pin to co-rotate.
[0005] In such areas where a relatively high level of cleanliness is required, such as area where food is stored and/or processed, it is important to ensure that there is a low level of dirt and the like. However, the presence of projections and/or recesses in the pins as a result of the male or female components can provide areas for dirt to gather. It will often be a laborious task to remove the dirt from these areas, and dirt can often be missed.
SUMMARY
[0006] It is an object of the present invention to attempt to overcome at least one of the above or other disadvantages. It is a further aim to provide a pin that reduces the areas for dirt to gather and increase the ease with the pin may be cleaned whilst still permitting for a tool to be used to provide improved mechanical advantage for the insertion and removal of the pin.
[0007] According to the present invention, there is provided a pin as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.
[0008] In the exemplary embodiments pins are described having a tool engagement portion and a resiliently deformable cover. It will be clear to those skilled in the art that a pin commonly also comprises a head portion and a shank. The head generally comprises a portion having a wider circumference than the shank such as to help determine the extent of the insertion of the pin into a recess. The shank generally forms the part of the pin that provides the structural rigidity to hold the attached components in place. The shank may also comprise fixing means such as a form of screw thread or bayonet type of fixing projections. Such forms of pin commonly required rotation of the pin is required to fix it in place. As such, the head may also comprise means for engaging with a tool that allows for increased mechanical advantage to be leveraged in the rotation of the pin, whether that is to tighten or loosen the pin.
[0009] According to a first aspect there is provided a pin having a tool engagement portion and a resiliently deformable cover arranged over the tool engagement portion. The resiliently deformable cover is operable to deform from a first raised position to a second lowered position to allow for the engagement of the tool engagement portion with a tool. Generally, the contours of the tool engagement position are substantially not present in the upper face of the pin when the cover is in the first raised position. Upon deformation of the cover to the second lowered position contours similar to those of the tool engagement portion become present in the upper face of the pin. Suitably, when the deformable cover is deformed from a first raised position to a second lowered position a portion of the upper face of the cover is moved from a first raised position to the second lowered position. Typically, a portion of the upper face of the deformable cover maintains substantially the same orientation in the second position as the first position, such as substantially having a plane along the lateral cross-section of the pin. Typically, a portion of the upper face of the deformable cover is moved from a plane substantially along the lateral cross-section of the pin to a plane substantially along a longitudinal cross-section of the pin.
[0010] The cover may be formed of any suitable resiliently deformable material. Suitably, the cover is at least partially formed from one or more of the materials selected from TPE Rubber, TPU, Silicon rubber, elasticated rubber or any other suitable elasticated material. Generally, the portion of the cover formed from one or more of the above materials will be the portion arranged over and immediately around the tool engagement portion of the pin.
[0011] In the exemplary embodiments, the resiliently deformable cover may provide a substantially smooth surface in the first position. For example, the upper face of the deformable cover may comprise substantially no sharp angles or deep recesses in the first position. “Sharp angles and deep recesses” as used herein being intended to be relative to the angles and recesses of the tool engagement portion. The upper face of the deformable cover may comprise an undulating surface such that portion of the surface comprises projections or are of a curved nature, such as convex or sloped when viewed from above. Suitably, the substantially smooth surface is present over the upper face of the head of the pin, such as substantially the whole upper face of the head of the pin.
[0012] In the exemplary embodiments, the resiliently deformable cover in the first position may comprise a ridge of resiliently deformable material. The ridge may extend from the upper face of the cover. The ridge may comprise a sloped upper face. Typically, the ridge is at least partially formed of resiliently deformable material, suitably the same resiliently deformable material as the remainder of the cover. The ridge may comprise a region of increased thickness relative to a portion of the cover substantially surrounding the ridge. The ridge may comprise the thickest portion of the cover. Typically, the ridge provides a thickness of resiliently deformable material of between 0.001 m to 0.0015 m. The portion of the cover arranged within the inner edge of the ridge suitably has a thickness less than the thickness of the ridge.
[0013] In the exemplary embodiments, the ridge may provide an indication of the location of the tool engagement portion of the pin. As such, the ridge may be a guiding ridge. The ridge may extend at least partially around substantially the periphery of the tool engagement portion. Typically, at least a portion of the inner edge of the ridge is arranged substantially longitudinally above at least a portion of the periphery of the tool engagement portion. Suitably substantially all of the inner edge of the ridge is arranged substantially longitudinally above at least a portion of the periphery of the tool engagement portion. The inner edged of the ridge may have substantially the same shape as the periphery of the tool engagement portion. In such an embodiment, the ridge provides a relatively shallow impression of the shape of the tool engagement portion of the pin. This arrangement helps to reduce the depth to which the upper face of the cover must deform before the tool is able to cause co-rotation of the pin.
[0014] Advantageously, the ridge of the deformable cover also allows a user to quickly and easily located the concealed tool engagement portion of the pin. Such a feature may reduce unnecessary damage to the cover caused by misplaced impacts of the tool against areas of the cover which are not arranged over the tool engagement portion. Furthermore, by providing an excess of resiliently deformable material adjacent to the tool engagement portion, the ridge may spread the stress suffered by the cover during engagement of a tool over a relatively large amount of material.
[0015] In the exemplary embodiments, the resiliently deformable cover may be in the form of a cap. The cap may be comprised of an upper wall and a skirt. Suitably, the upper wall and the skirt are formed of resiliently deformable material. Typically, the skirt extends from the periphery of the upper wall, such as from substantially the outer edge of the upper wall. The skirt may extend around substantially the whole periphery of the upper wall. Suitably, the cap forms a tight abutting fit around the pin.
[0016] Advantageously, a cover in the form of a cap provides the terminable edges of the cover longitudinally distal to the upper edge of the pin such that, in use, when the upper edge of the pin is substantially flush with a surrounding barrier part the terminal edges of the cover are hidden from view, thus further reducing the points at which dirt may ingress. This arrangement may also help to improve the integrity of the cover such as to improve resistance to lifting of the cover in use.
[0017] In the exemplary embodiments, the resiliently deformable cover may be removable. The resiliently deformable material of the cover may degrade at a faster rate than the other material of the pin. As such, it is advantageous that the cover may be removed and replaced to extend the lifetime of the remainder of the pin.
[0018] In the exemplary embodiments, the pin may further comprise a lip. The lip may be arranged toward the upper face of the pin. Suitably, the lip extends substantially perpendicularly to the side wall of the pin. Suitably, the lip is formed of a substantially non-deformable material, such as a non-deformable metal. The lip may engage with the resiliently deformable cover such that the cover is overstretched. Suitably, the cover, for example the skirt of the cover, abuts opposite faces of the lip when in the first position.
[0019] Advantageously, the lip may help to hold the cover in place as well as helping to form a close fit between the cover and the remainder of the pin.
[0020] In the exemplary embodiments, the tool engagement portion provides means for engagement with a tool such that rotation of the tool causes co-rotation of the pin. Typically, the pin comprises a female tool engagement portion operable to engage with the male projection of an appropriate tool. Suitably, the tool engagement portion comprises a recess, the recess extending into the body of the pin, suitably extending substantially longitudinally into the body of the pin. Typically, the recess extends substantially perpendicularly from the surrounding upper face of the pin. The tool engagement portion is generally formed of a substantially non-deformable material, such as a non-deformable metal.
[0021] In the exemplary embodiments, the recess of the tool engagement portion may have a substantially curved perimeter. For example, a perimeter in substantially the shape of an oval. Suitably, the peripheral shape of the recess substantially avoids sharp angles, such square edged corners. Suitably, the peripheral shape of the recess contains only curved corners.
[0022] Advantageously, the use of curves and the avoidance of sharp angles helps to avoid focusing stress on relatively small areas of the cover by providing a more uniform distribution of the stress, thus extending the life of the cover.
[0023] In the exemplary embodiments, the recess may extend along substantially the whole longitudinal length of the pin. Suitably, the recess does not extend the whole longitudinal length of the pin. As such, typically the pin comprises an open end, that is the end at which the female tool engagement portion is arranged, and closed end.
[0024] Advantageously, the presence of a recess extending a substantial distance into the pin reduces the amount of material required to manufacture the pin and thus lower the cost of manufacturing the pin.
[0025] In the exemplary embodiments, the pin may comprise fixing means operable to upon actuation substantially prevent removable of the pin. Suitably, the fixing means of the pin are actuated by rotation of the pin. The fixing means of the pin may comprise fixing means such as a screw thread and/or bayonet projections. Typically, the fixing means comprise at least one bayonet projection, such as two bayonet projections. Suitably the bayonet projections are arranged at diametrically opposed positions on the pin.
[0026] In the exemplary embodiments, the pin may further comprise a sheath. The sheath is generally operable to be arranged over a portion of the shank of the pin such as to encase a portion of the shank of the pin in use. As such, the sheath may comprise larger lateral dimensions than the lateral dimensions of the shank of the pin. In use in a barrier system, the sheath may be operable to be inserted in the opposite end of the aperture through which a pin is to be inserted, or operable to be inserted through an aperture substantially opposite the aperture through which the pin is to be inserted. Suitably, once the pin is engaged at least partially within the sheath, the pin is rotated within the sheath to secure the pin in position. It will be apparent that a resiliently deformable cover and tool engagement portion of the pin may alternatively, or additionally, be arranged on the closed end of the sheath such as to allow rotation of the sheath with an appropriate tool.
[0027] In the exemplary embodiments, the sheath may comprise an open end and a closed end. Suitably, the open end of the sheath is operable to receive at least a portion of the shank of the pin. The sheath may further comprise a flange. Suitably, the flange is arranged toward an end of the sheath. The flange of the sheath may be arranged toward the closed end of the sheath, typically arranged at the upper edge of the closed end of the sheath. The flange may provide a continuation of the upper face of the closed end of the sheath beyond the sidewalls of the sheath. The exterior surface of the flanged closed end of the sheath may be substantially smooth. The sheath may comprise the complementary fixing means to the fixing means of the pin. For example, where the pin comprises bayonet fixing means, the sheath may comprise a channel operable to receive the bayonet fixing means. Typically, the channel comprises an L-shaped portion, a portion of which is operable to receive a respective bayonet fixing means upon rotation of the pin into the locked position in a manner known in the art.
[0028] Advantageously, by providing the complimentary fixing means in the sheath to the fixing means of the pin, components to be fixed together are not required to comprise such fixing means. As such, the pin may be used with any components having only an aperture passing there through.
[0029] According to a second aspect, there is provided a kit of parts having a pin according to the first aspect and a tool. This tool is operable to engage the tool engagement portion of the lock pin such that, when engaged, rotation of the tool causes rotation of the pin. Using such a tool the pin may be locked in position during assembly and unlocked to remove the pin during disassembly. The tool is operable to deform the cover from the first position to the second position, wherein the tool may engage the tool engagement portion of the pin such that rotation of the tool causes co-rotation of the pin. It will be clear that the phrase “engage the tool engagement portion” when used herein refers to the cover deforming to an extent that allows rotation of the tool to cause co-rotation of the pin. Engagement of the tool with the tool engagement portion is thus commonly via the material of the cover. Generally, the tool engagement portion provides a mould into which the cover may deform thereby providing the shape appropriate for the tool engage with the pin in order to cause co-rotation of the pin.
[0030] In the exemplary embodiments, the tool may comprise projections operable to limit the depth of the insertion of the tool into the tool engagement portion of the pin, in use. Suitably, the projections are operable to engage with a portion of the cover not arranged over the tool engagement portion of the pin. The projections may be operable to engage with the ridge of the cover. Typically, the projections provide a substantially planar lower face that is operable to engage with the upper face of the cover. The projections may be in the form of at least two outwardly extending projections. The projections may be spaced about 180° apart.
[0031] Advantageously, the projections of the tool prevent the tool from being inserted too deeply into the tool engagement portion.
[0032] According to a third aspect, there is provided a barrier assembled from parts, the parts comprising: first and second spaced posts; and a first rail interconnecting said first and second posts, wherein the rail is not inserted within the posts; characterised in that the first post, second post, and rail are hollow in at least the region of the intended interconnection and each post includes an aperture and is connected to the rail by a coupling, wherein the coupling includes a connector; the connector is arranged to extend through the aperture so that a first portion of the coupling is arranged inside the hollow region of the post and a second portion of the coupling is arranged inside the hollow region of the rail; and the connector includes an abutment that is able to be arranged to prevent movement of the connector through the aperture in use, and able to be arranged to allow movement of the connector to allow disassembly of the rail from the post by allowing the connector to withdraw from one of the post or rail, wherein the parts further comprise a pin according to the first aspect.
[0033] In the exemplary embodiments, the terminal edges of the resiliently deformable cover may be hidden from view, in use.
[0034] In the exemplary embodiments, the upper face of the pin may be substantially flush with the upper face of the respective surrounding post or rail, in use.
BRIEF DESCRIPTION OF DRAWINGS
[0035] For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which:
[0036] FIG. 1 shows a perspective view of a pin according to an embodiment of the present invention;
[0037] FIG. 2 shows a side cross-sectional view of a pin comprising a pin and tool operable to engage the tool engagement portion of the pin.
[0038] FIG. 3 shows a side cross-sectional view of a pin comprising a pin engaged with a tool.
[0039] FIG. 4 shows a perspective view of a sheath.
DESCRIPTION OF EMBODIMENTS
[0040] Referring to FIGS. 1 to 3 there is shown pin 100 . The cylindrical elongate pin 100 comprises head 200 and shank 300 extending co-axially therefrom. Head 200 comprises solid steel core portion 202 and resiliently deformable elastomeric cap 204 . Cylindrical core portion 202 has lip 214 extending perpendicularly around the top edge thereof and ramp 216 arranged below lip 214 , ramp 216 extending around the circumference of the core portion 202 . Lip 214 has sloping side face 216 . The upper face of core portion 202 is convex when viewed from above. Extending longitudinally inward from the upper face of core portion 202 is oval shaped recess 220 .
[0041] Cap 204 is formed of top wall 206 and skirt 208 , skirt 208 extending perpendicularly from the edge of top wall 206 . Top wall 206 has oval shaped curved ridge 210 arranged centrally thereon and extending upwards from the upper face. Arranged on outer face of skirt 208 is linear channel 212 . Channel 212 extends around the circumference of skirt 208 and is arranged toward and parallel with, but inwardly spaced from, the lower edge of the skirt 208 .
[0042] Cap 204 is arranged over core portion 202 such that the inner face of top wall 206 tightly abuts the upper face of core portion 202 and the inner face of skirt 208 tightly abuts around the side face of core portion 202 . Lip 214 extends into the resiliently deformable material of skirt 208 . Cap 204 is arranged over the core portion 202 of head 200 such that the inner edge of ridge 210 is arranged substantially directly above the perimeter of recess 220 .
[0043] Shank 300 has core portion 302 and outer layer 304 . Resiliently deformable outer layer 304 extends along and around the side wall of core portion 302 . Outer layer 304 is formed of a mesh-like lattice structure with interconnecting cross-members and a plurality of recesses. Arranged extending perpendicularly from the outer face of outer layer 304 are diametrically opposed cylindrical bayonet fixing projections 306 .
[0044] Referring specifically to FIGS. 2 and 3 , there is shown the engagement of a tool 400 with the recess of pin 100 . Tool 400 has recess engaging portion 402 and blocking projections 404 . Engaging portion 402 is formed of a projection that has an oval shaped lateral cross-section of substantially the same shape but of slightly smaller lateral dimensions than the recess 220 of head 200 . The pair of oppositely extending blocking projections 404 are spaced inwardly from engaging portion 402 and extend perpendicularly away therefrom.
[0045] As shown in FIG. 2 , where top wall 206 of cap 204 is in a first raised position, the upper face of top wall 206 provides a substantially smooth surface over recess 220 . No sharp angles or deep recesses where dirt may gather exist in the surface.
[0046] As shown in FIG. 3 , top wall 206 of cap 204 may resiliently deform to a second lowered position such that the upper face of top wall 206 forms relatively sharp angles and a deep recess according to the profile of recess 220 .
[0047] In use, a portion of top wall 206 is deformed from the first position to the second position by the insertion of tool 400 in direction X. Under this force top wall 206 is deformed to the profile of recess 220 .
[0048] Projections 404 are arranged inwardly of engaging projection 402 such that engaging projection 402 may by inserted into top wall 206 to a degree sufficient to allow pin 100 to co-rotate upon rotation of tool 400 . Excess stress on the deformed part of top wall 206 is mitigated by engagement of the blocking projections with a portion of top wall 206 that is arranged over the solid surface of head 200 and over recess 220 . Thus further progression of tool 400 into recess 220 is blocked.
[0049] Upon removal of tool 400 from recess 220 , top wall 206 returns to the first raised position.
[0050] Referring now to FIG. 4 there is shown sheath 500 . Sheath 500 is formed of cylindrical wall 502 , cylindrical wall 502 having a closed end 510 and open end 508 . Closed end 510 has flange 504 arranged around the upper edge thereof, flange 504 extending perpendicularly from the edge of closed end 510 relative to wall 502 . Diametrically opposed open end 508 has bore 512 extending inwardly there form. Arranged along a portion of the inner face of wall 502 and extending longitudinally from the upper edge of open end 508 are diametrically opposed channels 506 . Channels 506 both comprise an end portion (not shown) that extends substantially perpendicularly away from the main body of the channel.
[0051] In use, pin 100 may be inserted shank-end first into bore 508 through the open end 510 of sheath 500 . As pin 100 is inserted channels 506 receive a respective bayonet projection 306 . Pin 100 slides into bore 508 until bayonet projections 306 abut the bend of the respective channel 506 . At this stage, pin 100 may be rotated about its longitudinal axis to engage the bayonet projections with the end portion of the respective channel such that pin 100 may not be removed from sheath 500 without reverse rotation of the pin 100 .
[0052] In the present embodiment, pin 100 may be used to connect the railing and post of a barrier system (not shown). A coupling is arranged in the railing's cavity and extends through an aperture in the post into the cavity of the post. Pin 100 can be used to secure the coupling in position within the cavity of the railing.
[0053] In use with such a barrier system, sheath 500 is inserted through an aperture in the railing and the coupling (not shown). Pin 100 is inserted through an opposing set of apertures such that pin 100 may be inserted into the bore 508 of sheath 500 to the point at which bayonet projections 306 abut the bend of the respective channel 506 . At this stage the upper face of the closed end 510 of sheath 500 is substantially flush with an upper face of the rail. Likewise, the upper face of top wall 206 of cap 204 is substantially flush with an upper face of the rail.
[0054] To fix pin 100 in position, tool 400 may engage recess 220 as described above to allow co-rotation of pin 100 with tool 400 such that bayonet projections 306 are locked into the end portion of respective channels 506 . Upon locking of the pin within the sheath, there is formed a locked barrier system wherein the upper face of the head 200 of pin 100 is substantially flush with an upper face of the rail and wherein the upper face of the head 200 does not comprises sharp angles or deep recesses where dirt and the like could collect and which prevent simple cleaning.
[0055] Pin 100 may be removed to allow the associated part of the barrier system to be disassembled by re-insertion of tool 400 in the manner described above and counter-rotation according to the practice commonly known in the art.
[0056] Although a few preferred embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims.
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A pin having a tool engagement portion and a resiliently deformable cover arranged over the tool engagement portion. The resiliently deformable cover is operable to deform from a first position to a second position to allow for the engagement of the tool engagement portion with a tool. The tool engagement portion is substantially concealed when the cover is in the first position, reducing the opportunities for dirt ingress. A tool may be used to deform the cover and allow the tool to engage with the tool engagement portion such that rotation of the tool causes co-rotation of the pin.
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CROSS-REFERENCE TO RELATED APPLICATION
The invention described and claimed hereinbelow is also described in German Patent Application DE 10 2005 041 448.6 filed on Aug. 31, 2005. This German Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119(a)-(d).
BACKGROUND OF THE INVENTION
The present invention relates to a portable power drill or a drill hammer.
Many kinds of systems for shifting the change-speed gears of portable power drills and drill hammers are known, such as rotatable selector elements and levers with which various operating states can be selected; in these systems, the selector elements must pass through the housing wall.
To that end, it is usual to use selector elements designed as a one-piece component with complex locking contours, mounted on the gearbox. A disadvantage is that producing these complex components requires complicated, expensive tools, and the sealing between the housing wall and the selector element is problematic.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide a portable power drill with a gear box which eliminates the disadvantages of the prior art.
In keeping with these objects and with others, one feature of the present invention resides, briefly stated, in a portable power drill or drill hammer, comprising a housing composed of half-shells; a shiftable change-speed gear received in said housing and having a manually hand-rotatable selector element which converts a rotary motion into a shifting motion, said selector element having a circular shell-shaped handle part outer handle part which is joinable with a further circular shell-shaped inner selector part so as to be sealed from outside and inside relative to one of said half shells, said inner selector part having a spring which is configured as leaf spring arranged in a form-locking fashion in said inner selector part, so that it radially overlaps said selector part at both sides and is supported with both overlapping ends inside on said half-shell.
When the portable power drill is designed in accordance with the present invention it has the advantage that an economical selector element is created which can be mounted simply and securely, functions reliably, has a long life, and is sealed.
The invention is described below in further details in terms of an exemplary embodiment, in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 , an exploded drawing of the drill hammer of the invention;
FIG. 2 , an exploded drawing of the selector element;
FIG. 3 , an external view of a drill hammer housing provided with the selector element;
FIG. 4 , an internal view of a drill hammer housing provided with the installed selector element;
FIG. 5 , an inside view of an outer part of the selector element, the outer part being positioned from outside on the drill hammer housing;
FIG. 6 , an inside view of the outer and inner parts of the selector element that are seated on the drill hammer housing without a leaf spring;
FIG. 7 , a three-dimensional back view of the assembled selector element;
FIG. 8 , a three-dimensional top view on the inner part of the selector element; and
FIG. 9 , a three-dimensional view of the leaf spring of the selector element.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The exploded view in FIG. 1 shows a drill hammer 10 with a housing 12 ; the housing comprising two half-shells 13 , 14 of plastic, with a vertical parting line 15 . The housing 12 receives a motor 16 with an ON/OFF switch 18 and a suitable power cord 20 for connection to an external power source, as well as a gear 26 and a percussion mechanism 36 . The motor 16 includes a motor shaft 22 , whose free end has a motor pinion 24 that is supported in an intermediate flange 25 that can be positionally secured between the half-shells 13 , 14 . The motor pinion 24 is in engagement with a driving gear wheel 30 of an intermediate shaft 28 of the gear 26 , the intermediate shaft being supported by one end in the intermediate flange 25 via a needle bearing, not shown. Adjoining this, a swash gear wheel 38 is rotatably supported on the intermediate shaft 28 , adjacent to a driving gear wheel 30 seated firmly on it and in particular press-fitted onto it. The swash gear wheel 38 has a swash plate 40 with a wobbling prong 42 , as part of the percussion mechanism 36 . Axially adjacent to the swash gear wheel 38 , a slaving gear wheel 32 is seated rotatably but in a manner fixed against relative rotation on the intermediate shaft 28 , in particular being press-fitted on, and the slaving gear wheel 32 is followed axially adjacent it by a driven gear wheel 35 , which is axially secured by a roller bearing 45 , seated firmly on the other end of the intermediate shaft 28 ; the slaving gear wheel 32 is embraced by a shift sleeve 34 in such a manner that it is slaved rotationally and is axially displaceable. The driven gear wheel 35 of the intermediate shaft 28 meshes with the driving gear wheel 48 of the driven shaft 46 ; with the gear 26 , by displacement of the shift sleeve 34 with switching means 52 , the rotary motion of the motor 16 can be selectively adjusted by hand by means of selector element 59 to a purely rotary motion, or in other words drilling, or a purely reciprocating motion, or in other words chiseling, or a rotary and reciprocating motion, or in other words drill hammering, of the driven shaft 46 .
Adjoining the wobbling prong 42 , the percussion mechanism 35 continues with a percussion element 44 , which via the swash plate 40 transmits percussive energy, converted from a rotary motion to a translational motion, to a chisel or drill restrained axially displaceably on a drill chuck 50 seated on the driven shaft 46 or on the end thereof.
The shift sleeve 34 has an annular-groovelike slot 33 on its circumference, for engagement by a gearshift fork 52 , which is part of a shift plate 54 designed in particular as a one-piece bent sheet-metal part. The shift plate 54 is a sheet-metal part bent into a U, the first leg of which U, with a semicircular recess, embraces the shift sleeve 34 or the slot 33 , and the other leg of which U serves as a locking fork 56 and is provided with a tooth hub profile 58 , located in a semicircular recess, for engagement with the serrated shaft profile of the driven gear wheel 35 . In the aforementioned engagement, the driven gear wheel 35 is simultaneously released from the slaved rotation by the shift sleeve 34 and is locked in a manner secured against relative rotation. Thus with the selector element 59 , a selectable rotary position of the driven shaft 46 for chiseling can be fixed. The shift plate 54 is longitudinally displaceable axially parallel to the intermediate shaft 28 via a guide rod 51 , which penetrates a guide bore 53 that passes transversely through the gearshift fork 52 and the locking fork 56 . For displacement of the shift plate 54 , the selector element 59 , on the order of a rotary knob, is used; its rotation can be transmitted, via its eccentric cam 59 , as a sliding motion to a protrusion 55 of the shift plate 54 .
The rotary motion of the electric motor 16 is transmitted via the driving gear wheel 30 to the intermediate shaft 28 and the slaving gear wheel 32 . The slaving gear wheel, of sintered material, is in the form of a serrated shaft, whose profile extends over its entire external length. The swash gear wheel 38 can be coupled in a manner fixed against relative rotation to the slaving gear wheel 32 via the suitably positioned shift sleeve 34 , and then the rotary motion of the intermediate shaft 28 is converted, via the swash plate 40 and the wobbling prong 42 , into a translational motion of the percussion element 44 .
The driven gear wheel 35 , seated rotatably on the intermediate shaft 28 , can be coupled in a manner fixed against relative rotation to the slaving gear wheel 32 via the shift sleeve 28 , and part of the driven gear wheel 35 has a serrated shaft profile 31 and 66 , which corresponds to the tooth hub profile 29 of the shift sleeve 28 , and a further part of the driven gear wheel 35 has a spur gear profile 68 for transmitting rotation to the driving gear wheel 48 of the driven shaft 46 . As a result, the rotary motion of the intermediate shaft 28 can be transmitted to the driven shaft 46 and to the drill chuck 50 secured therein, or to a tool insert in the form of a drill or chisel seated therein. The coupling or shifting between the slaving gear wheel 32 and the axially adjacent swash gear wheel 38 or driven gear wheel 35 is effected via the shift sleeve 34 , whose positioning is established solely by way of the form lock between the slot 33 and the gearshift fork 52 engaging it, without any friction losses occurring in the operation of the drill hammer 10 . Thus the shift sleeve 34 , in all three switching positions, remains unsubjected to axial force, resulting in less wear and a longer service life.
If upon axial displacement of the shift sleeve 34 the corresponding serrated shaft/tooth hub profiles of the swash gear wheel 38 or driven gear wheel 35 meet one another on the face end with that of the shift sleeve 34 , shifting synchronizing means make the shifting easier. To that end, on their side toward the slaving gear wheel 32 , each of the serrated shaft profiles of the swash gear wheel 38 or driven gear wheel 35 has a parallel tooth width reduction 62 , 64 of approximately ⅔ of the tooth width over a tooth length of approximately 1 to 2 mm. This leads to a partial widening of the tooth gaps of the serrated shaft profile and facilitates the entry there of the tooth hub teeth of the shift sleeve 34 .
In a transitional position in shifting from the percussion drilling mode to the chiseling mode, the drill chuck 50 or the chisel can be rotated by hand into a desired working position. After the shifting to the chiseling mode shifting position, the selected rotary position of the chisel is maintained by way of the locking with the locking fork 56 .
The shift travel amounts to approximately 5 mm of displacement distance of the shift sleeve 34 , or rotational distance of the selector element 59 to the right or left.
The selector element 59 comprises a shell-like outer, hand-actuatable handle part 100 and an inner selector part 102 , centrally fitting into the outer handle part 100 , with a cam 74 , with which the shifting operation for selecting a gear or changing gears is accomplished. Both parts can be screwed together on a housing shell 13 in a manner that is sealed off from the housing shell; a sealing ring 104 is held in prestressed fashion between the edge of the inner selector part 102 and the inner wall of the housing shell 13 .
The inner selector part 102 , on its inside, has a rectilinear, groovelike recess 120 for form-locking reception of an elongated, rectilinear leaf spring 103 with a central through hole 107 for a mounting screw 106 . The outer ends of the leaf spring 103 have camlike indentations 105 , which fit into corresponding associated indentations 113 on the inside of the housing shell 13 and define overloadable adjustment positions of the selector element 59 .
The outer handle part 100 can be screwed to the inner selector part 102 by passing a screw through its central through hole 109 to engage a threaded hole 108 of the handle part 100 . The inner selector part 102 is aligned with a centering ring 112 of the handle part 100 .
The handle part 100 has a twist knob 110 protruding in beamlike fashion, which rests graspably in the user's hand and allows the handle part or the selector element 59 to be easily rotated. The housing shell 13 , outside the circumference of the handle part 100 , has an outward-protruding stop 114 as well as graphic symbols 116 , 117 , 118 that can be felt by the hand. The stop 114 corresponds to the beamlike twist knob 110 , upon whose rotation, in the chiseling position, the user's hand meets the stop 114 and can tell that the chiseling position has been reached.
Thus an indexing and positional fixation of the selector element 50 and hence of the gearshifting in the selected position is assured.
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A portable power drill or hammer drill having a housing ( 12) which consists in particular of half shells ( 13, 14) and accommodates a manual gearbox ( 26), wherein a shift element ( 59) that can be rotated by hand converts its rotary movement into a shift movement, can be produced cost-effectively and can be easily operated, without lubricant escaping from the housing ( 12), by the shift element ( 59) consisting of a shell-like handle part ( 100) which can be joined together with a further, shell-like shift part ( 102) in a sealing manner from outside and inside relative to a housing shell ( 13).
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BACKGROUND
Heavy transportation machinery including motor vehicles such as light-duty, medium-duty, and heavy-duty trucks for personal and commercial use, and off-highway equipment and vehicles are typically constructed and assembled via separate subassemblies. One such subassembly is the motor cooling system which includes a front or side mounted fan for certain operation requirements. An additional subassembly is the radiator and cooling assembly. Both of these subassemblies are intended to be mated such that the fan facilitates in drawing air through the radiator assembly for facilitating in the cooling of the engine. There are a variety of fans used in these types of applications such as axial-flow fans, radial-flow fans, mixed-flow fans and high-efficiency hybrid-flow fans. Additionally, in the radiator or cooling assembly, it is common to include a ring shroud or cowling that surrounds the fan and which is intended for increasing the fan efficiency and reducing the sound of the operation of the fan.
An integral feature of the manufacturing of these subassemblies including the ring shroud is the tolerances which must be observed in the manufacturing. In order to maximize the performance of the fan, sufficient efforts should be made to mount the ring shroud very precisely around the fan, that is, there must be consistent clearance or a gap around and in between the entire circumference of the fan outer ring and the ring shroud. Such tolerances must be carefully controlled in order to preserve the performance and reliability of the machine. Not only does the ring shroud facilitate in improving the efficiency of the fan, but the gap between the ring shroud and fan outer ring is necessary to avoid crash conditions between them. Since the fan subassembly is connected to the engine, movement of the engine results in relative movement of the fan subassembly relative to the ring shroud. Consequently, interference may exist which may damage the fan outer ring and the fan vanes, thus the importance of sufficient and consistent gap between the ring shroud and the fan outer ring.
Accordingly, there is a need to ensure that the fan subassembly is mounted accurately and precisely within the ring shroud during manufacturing utilizing a simple system which facilitates the ease of assembly for an installer during the manufacturing process and also requires limited parts to limit costs. The described embodiment is directed to overcoming problems triggered by the variation present in most large scale manufactured parts and associated with mounting the ring shroud with respect to the fan subassembly.
SUMMARY
Disclosed herein are embodiments of a cooling fan and gap tool. In one embodiment, a fan assembly and gap tool for motor vehicle cooling system comprises an engine, a fan motor, a cooling fan, at least three mounting brackets, a ring shroud, and at least three fan braces. The fan motor is mounted to the engine. The cooling fan is mounted to the fan motor. Each of the at least three fan braces is affixed to the ring shroud. Each of the at least three mounting brackets has one end and an opposite end. Each of the at least three mounting brackets is mounted to the engine at the one end and is loosely mounted to one of the at least three fan braces at the opposite end. A plurality of gap tools align the ring shroud to the cooling fan before securing the at least three mounting brackets to the at least three fan braces.
Another embodiment provides a gap tool for mounting a ring shroud to a cooling fan assembly in a motor vehicle. In this embodiment, the gap tool comprises a head, an elongated cylinder having one end and an opposite end, a shoulder stop and at least one resilient arm. The head is connected to the one end of the elongated cylinder. The elongated cylinder has a beveled finish at the opposite end. The shoulder stop is attached to the elongated cylinder in a planar configuration with the head. The at least one resilient arm is attached to the elongated cylinder and gradually and continuously diverges outwardly from the opposite end of the elongated cylinder.
DESCRIPTION OF THE DRAWINGS
FIG. 1A is a side elevational view of gap tool disclosed herein;
FIG. 1B is a side elevational view rotated 90 degrees from FIG. 1A ;
FIG. 1C is a sectional view taken along line A-A of FIG. 1A ;
FIG. 1D is an end view taken along line B-B of FIG. 1A ;
FIG. 1E is a perspective view of the gap tool of FIG. 1A
FIG. 2 shows an exploded view of a high efficiency hybrid fan and 15 liter engine.
FIG. 3 shows an exploded view of a high efficiency hybrid fan and 15 liter engine (rear).
FIG. 4 shows an exploded view of a 15 Liter engine with fan motor.
FIG. 5 shows a perspective view of a 15 Liter engine with fan motor.
FIG. 6 shows an exploded view of a high efficiency hybrid fan, fan hub nuts, fan motor and 15 L engine.
FIG. 7 shows a perspective view of a high efficiency hybrid fan and 15 L engine.
FIG. 8 shows an exploded view of a high efficiency hybrid fan, 15 L engine and mounting brackets.
FIG. 9 shows a perspective view of a high efficiency hybrid fan, 15 L engine and mounting brackets.
FIG. 10 shows an exploded view of the ring shroud, high efficiency hybrid fan, 15 L engine and mounting brackets.
FIG. 11 shows a perspective view of partially assembled ring shroud, high efficiency hybrid fan, 15 L engine and mounting brackets.
FIG. 12 shows a perspective view of the gap tool.
FIG. 13 shows an exploded view of gap tool and ring shroud with keyhole.
FIG. 14 shows a cross-sectional view of the gap tool, ring shroud, fan vane and fan rubber seal.
FIG. 15 shows a perspective view of partially assembled ring shroud, high efficiency hybrid fan, 15 L engine and mounting brackets and gap tool.
FIG. 16 shows a close up view of inserted gap tool in ring shroud.
FIG. 17 shows a perspective view of the partially assembled ring shroud, high efficiency hybrid fan, 15 L engine, mounting brackets, gap tools and clamping devices.
FIG. 18 shows a perspective view of an assembled high efficiency hybrid fan and 15 liter engine.
DETAILED DESCRIPTION
Embodiments of a fan assembly and a gap tool are disclosed. One embodiment comprises a system for mounting a ring shroud to a motor vehicle cooling system and engine. This system comprises of an engine that supports a fan subassembly having a fan motor, a cooling fan that is mounted to the fan motor which is propelled by the engine. The cooling fan member has a fan hub and a plurality of fan vanes extending outwardly from the fan hub. The fan vanes sit in between a fan circumferential ring and a fan outer ring. The fan circumferential ring is attached to the fan vanes and it surrounds the fan hub, the fan circumferential ring member has a disc shape extending radially. The fan outer ring has an annular shape and is attached to the tips of the fan vanes. The fan subassembly is partially covered by a ring shroud mounted in front of the fan outer ring. The ring shroud comprises of an annular shaped ring shroud base, a fan rubber seal, and mounting hardware such as ring inlets or fan braces. The ring shroud base has perforations to allow the insertion of a mounting or gap tool during assembly or subassembly.
In another embodiment, the assembly of the ring shroud to the fan subassembly involves the engagement of several mounting brackets between the engine and the ring shroud and the use of a plurality of gap tools. After the cooling fan subassembly has been installed, the method of assembly of the ring shroud to the cooling fan assembly entails installing mounting brackets to the engine, followed by tightening the fasteners in the mounting brackets at the engine end but leaving the fasteners loose at the opposite end. The ring shroud mounting hardware or braces may have oversized holes that would allow for any necessary adjustments during the ring shroud placement. The ring shroud is mounted against the free end of mounting brackets that were previously mounted to the engine at the opposite end. While the fasteners in the ring shroud end are still loose, the gap tools are inserted through apertures in the pre-perforated ring shroud base.
In some embodiments, the gap tool facilitates the aligning of the ring shroud against the fan outer ring by providing static conditions and defining precisely the radial and axial gap between the interior of the ring shroud base and the exterior of the fan outer ring. Several gap tools may be inserted through the pre-perforated ring shroud base. The head of the gap tool acts a stopper restricting how far the gap tool will penetrate once inserted through the ring shroud base aperture. The shoulder stop of the gap tool defines the axial gap between the interior of the ring shroud base and the exterior fan outer ring. The elongated cylinder body of the gap tool defines the radial gap between the interior of the ring shroud base and the exterior fan outer ring.
In an embodiment of the gap tool, at least two resilient arms are attached to the elongated cylinder body and extend outwardly from the beveled end tip. The resilient arms will be urged together during the gap tool positioning through the ring shroud aperture. Once completely inserted, the resilient arms return to a deployed configuration securing the gap tool in place while engaged between the ring shroud base and the fan outer ring. Once sufficient gap tools have been inserted, at least two clamping devices may be positioned temporarily at opposite ends to grip together the fan subassembly, including the ring shroud. At this point, the remaining loose fasteners within the mounting brackets engaged between the engine and the ring shroud end are tightened to secure the cooling fan assembly together. Once the fasteners are tightened, the ring shroud and fan assembly has been securely mounted. The clamping devices and the gap tools can then be removed. Each gap tool can be removed by urging the resilient arms together to reverse the previously deployed configuration into an un-deployed configuration. The un-deployed configuration allows the inserted section of the gap tool that passed through the ring shroud aperture to be removed and disengaged from the ring shroud and fan assembly.
FIG. 1A to FIG. 1E and FIG. 12 show an embodiment of the gap tool 200 for mounting a ring shroud 320 onto to a cooling fan 300 assembly. FIG. 1A shows a side view of the gap tool 200 . FIG. 1A shows a tool shaped similar to a commercially available key having attached one resilient arm 250 coming out the side of its main body or elongated cylinder 240 . FIG. 1A shows in one end of the gap tool 200 , a head 220 in the shape of a key bow or a crest but it can be any shape as long as it is larger than the keyhole or aperture 210 in the perforated the ring shroud 320 and is large enough for a person's hand or machine to grip. Dimensionally, the head 220 has about twice the height (y-plane) when compared to its width (x-plane). The head 220 , which is left protruding out of the ring shroud 320 when the gap tool 200 is in use, has a slope of about thirty-four degrees that rises (x-y plane) from the elongated cylinder 240 body on its upper side.
Attached to the head 220 in FIG. 1A is an elongated cylinder 240 that makes the main part of the gap tool 200 body and defines the radial gap 290 between the interior of the ring shroud 320 and the exterior of the fan outer ring 340 . According to FIGS. 1A and 1B the length of the elongated cylinder 240 from the head 220 to the beveled tip 260 is about twice as long as the distance between the head 220 and the end of the shoulder stop 230 (x-plane). FIG. 1A shows at the end opposite to the head 220 a beveled tip 260 cut in about a twenty-two degree angle and rising from the x-plane.
FIG. 1A shows the shoulder stop 230 . The shoulder stop 230 saliently comes out of the elongated cylinder 240 in the x-y plane. The shoulder stop 230 may be in a rectangle shape, its dimension defines the axial gap 280 between the interior of the ring shroud 320 and the exterior of the fan outer ring 340 , and it is about half as long as the longest span of the elongated cylinder 240 starting from the end of the head 220 to the beveled tip 260 .
FIG. 1B and FIG. 1C show the two resilient arms 250 in a z-plane and being attached and parallel to the elongated cylinder 240 body. The two resilient arms 250 gradually and continuously diverge outwardly at about a three degree angle from the beveled tip end 260 of the elongated cylinder 240 . The resilient arms 250 span to a length approximately half of the length of the gap tool 200 including the head 220 and the elongated cylinder 240 body. The resilient arms 250 are sufficiently resilient so that the resilient arms 250 can be urged or squeezed together into an un-deployed or closed configuration when pressure or force is applied. The resilient arms 250 should be capable of springing back to an open or deployed configuration once the pressure or force is removed.
FIG. 1D is an end view taken along line B-B of FIG. 1A . FIG. 1D shows the depth (z-plane) of the shoulder stop 230 being about half the size of the depth of the head 220 . FIG. 1D , additionally the outward span of the resilient arms 250 are shown as slightly wider than the diameter of the elongated cylinder 240 body.
FIG. 1E is a perspective view of the gap tool of FIG. 1A having a head 220 , a shoulder stop 230 , a resilient arm 250 and an elongated cylinder 240 body with a beveled tip.
The gap tool 200 can be made of any thermoset polymer material, thermoplastic polymer material, metal, or wood among other materials. Depending on the material, the gap tool 200 can be manufactured by injection molding, extrusion, casting, or spin casting among other methods.
FIGS. 2 to 18 shows the gap tool 200 for mounting a high efficiency hybrid fan to a 15 L engine but the embodiment and utility of the gap tool is not limited to high efficiency hybrid fan systems or to 15 L engines as it could be useful on any type of cooling system for a motor vehicle engine that contains a shroud or cowling part mounted to a fan assembly.
The cooling fan 300 system in the embodiment shown in FIGS. 2-3 and FIGS. 6-11 has a fan hub 360 , a fan circumferential ring 330 surrounding the fan hub 360 , a plurality of fan vanes 310 that are positioned around the fan hub 360 and fan outer ring 340 connected to the ends of the fan vanes 310 members. The use of fan vanes 310 and rotating ring elements such as the fan circumferential ring 330 and the fan outer ring 340 to form a cooling fan 300 subassembly is well known in the art, and these fan subassemblies are commonly referred to as ring fans.
Although the embodiments of the fan circumferential ring 330 and the fan outer ring 340 shown in FIGS. 2-3 are solid, it is also possible that either one be discontinuous with gaps between the vanes or have openings in the ring itself, or that the ring member (or discontinuous portions thereof) can be positioned radially inwardly slightly from the ends of the fan vanes 310 .
FIG. 2 and FIGS. 6-10 show a fan outer ring 340 that is intricately formed with the cooling fan 300 assembly and thus fixedly attached to the tips of the fan vanes 310 . In accordance with an embodiment of the present invention, the fan outer ring 340 can also have a concave shape.
FIGS. 2-3 , FIGS. 10-11 , and FIGS. 15-17 show a ring shroud 320 having an annular shape. The ring shroud 320 has incorporated along its circumference four fan braces 350 that serve as its mounting hardware. The ring shroud 320 is to be positioned circumferentially around, or substantially circumferentially around, all or a principal portion of the rotating fan outer ring 340 . FIGS. 2-3 , FIGS. 10-11 , FIGS. 13-18 show a fan rubber seal 370 surrounding the ring shroud 320 . Although in the present embodiment the ring shroud 320 has four fan braces 350 , it is possible to have less or more than four fan braces 350 for mounting a ring shroud 320 to a cooling system 300 assembly.
The method of mounting the ring shroud 320 to the cooling fan 300 assembly using the described embodiment of the gap tool 200 begins by mounting the fan motor 110 to the engine 100 as shown in FIG. 4 . Once the fan motor 110 is installed, as shown in FIG. 5 , the shoulder portions of the shoulder nuts 400 are added. FIG. 6 shows a pre-assembled cooling fan 300 as it is being installed against the fan motor 110 and it is bolted in place with the use of the nut portion of the shoulder nuts 400 .
FIG. 7 shows the cooling fan 300 installed on the engine 100 . FIG. 8 shows mounting brackets 410 of a variety of shapes and sizes all having T-shape ends. In addition, FIG. 8 shows the cooling fan 300 and the engine 100 subassembly. FIG. 9 shows the mounting brackets 410 attached to different parts of the engine 100 at one end and not attached to anything at the opposite end with some fasteners 415 tightened and other fasteners 415 loose in preparation for subsequent subassembly steps.
FIG. 10 shows the engine 100 , the cooling fan 300 , the mounting brackets 410 and the ring shroud 320 with four fan braces 350 , and a fan rubber seal 370 surrounding the ring shroud 320 . Each fan brace 350 in FIGS. 2-3 and FIGS. 10-11 have a face plate 345 end with holes 355 . The fan brace holes 355 may be oversized to allow for adjustments during assembly and are intended to be attached to mounting brackets 410 with the help of fasteners 415 . FIG. 11 shows the ring shroud 320 subassembly mounted to the mounting brackets 410 , the fasteners 415 of the mounting brackets 410 are tightened on the engine 100 side only.
FIG. 13 shows that while the mounting brackets 410 are fastened in the engine 100 end and loose in the ring shroud 320 end, a plurality of gap tools 200 are inserted through perforated holes 210 in the ring shroud 320 . FIG. 14 shows a cross-sectional view of the gap tool 200 being used to create a static condition during assembly and align the interior of the ring shroud 320 to the exterior fan outer ring 340 . The shoulder stop 230 of the gap tool 200 sets the axial distance or clearance 280 between the interior of the ring shroud 320 and the exterior of the fan outer ring 340 . The elongated cylinder 240 body of the gap tool 200 serves to set the radial distance or clearance 290 between the interior of the ring shroud 320 and the exterior of the fan outer ring 340 .
FIG. 15 shows the engine 100 , the cooling fan 300 assembly with four engaged gap tools 200 (only the head 220 portion and the outside portion of the resilient arms 250 can be seen) about ninety degrees from each other. FIG. 16 shows a segment of the ring shroud 320 , the fan rubber seal 370 , the fan vanes 310 , the head 220 and the tip of two resilient arms 250 of the gap tool 200 . In order to release the gap tool 200 from the ring shroud 320 and cooling fan 300 assembly, the resilient arms 250 may be squeezed together by manually exerting pressure on both sides inward towards the head 220 .
FIG. 17 shows the engine 100 , the cooling fan 300 assembly with four engaged gap tools 200 (only the head 220 portion and the outside portion of the resilient arms 250 can be seen) about ninety degrees from each other. FIG. 17 shows two commercially available clamping devices 420 clasping together the ring shroud 320 , the fan rubber seal 370 , and the cooling fan 300 including the fan circumferential ring 330 in the rear of the cooling fan 300 assembly. Although FIG. 17 suggests the use of only two clamping devices, the described method of assembly can use more than two clamping devices 420 .
Once the gap tool 200 has facilitated the positioning of the ring shroud 320 over the cooling fan 300 assembly then the assembly operator (not shown) either manually or through automation will tighten the remaining loose fasteners 415 whereby securing the ring shroud 320 and cooling fan 300 assembly. After the fasteners 415 are tightened on all mounting brackets 410 , the gap tools 200 may be removed manually or through automation means by urging the resilient arms 250 together with enough force to allow the gap tool 200 to once again fit through the ring shroud aperture 210 and be completely retrieved.
FIG. 18 shows the finished ring shroud 320 and cooling fan 300 assembly mounted on an engine 100 .
Although the assembly method described utilizes mounting brackets with fasteners, the same outcome can be achieved with alternative mounting means while using the embodiment of the mounting gap tool 200 described. In place of mounting brackets with fasteners, the operator may use adhesive methods such as an epoxy adhesive for securing a ring shroud to a cooling assembly after the gap tools have been inserted to set the clearance between the subassembly components.
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This is a system and apparatus for precisely mounting a ring shroud to a motor vehicle cooling system and engine. A cooling fan subassembly is mounted to an engine and ring shroud subassembly containing fan braces that are mounted to the engine via mounting brackets. A mounting gap tool is inserted through apertures in the ring shroud to prescribe the radial and axial clearance between the ring shroud and the cooling fan subassembly. Once the ring shroud and cooling fan assembly are aligned to predetermined specifications for clearance, the installer secures all the fasteners in the mounting brackets and retrieves any or all the mounting gap tools.
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FIELD OF THE INVENTION
The present invention relates to the field of abrasives.
BACKGROUND OF THE INVENTION
Abrasive discs for grinders are well known. Such discs ubiquitously include an annular abrasive element. Often, the grinder has a rotating threaded spindle, and the abrasive element is secured to the spindle by a nut. Alternatively, the abrasive element can be manufactured with an attached nut. Discs of this type are relatively convenient to replace, and thus, are relatively popular, notwithstanding that attaching a nut to an abrasive element in a manner that can withstand the very high rotation speeds associated with grinding operations can add substantial costs to manufacture.
SUMMARY OF THE INVENTION
An improved abrasive disc for use with an angle grinder forms one aspect of the invention. The grinder is of the type having a threaded spindle. The disc is of the type having: a central portion defining a threaded bore for receiving said spindle; and abrasive material surrounding the central portion. The improvement comprises: a hub defining the threaded bore; an annular element providing the abrasive material, the annular element having a central primary aperture aligned with the threaded bore in the hub to provide access to the bore by said spindle in use; and elements mechanically securing the hub to the annular element, for co-rotation.
According to another aspect of the invention, the elements can extend through the annular element to the hub.
According to another aspect of the invention, the annular element can have two or more secondary apertures spaced about the primary aperture; and the elements can be provided one for each secondary aperture and extend therethrough to the hub.
According to another aspect of the invention, a component can be provided, spacing apart the elements and from which the elements extend.
According to another aspect of the invention, the hub can have a socket for, and in receipt of, each element.
According to other aspects of the invention, the elements can be frictionally engaged by the hub; the elements can be adhesively secured to the hub; the elements can mechanically engage the hub; or the elements can be welded to the hub.
According to another aspect of the invention, the elements can have enlarged heads, disposed within the sockets and produced via a deformation operation, which mechanically secure the elements to the hub.
According to other aspects of the invention, the elements can be formed integrally with the component; or the elements can be formed separately from each of the hub and the component and defined by rivets.
According to another aspect of the invention, the elements can be formed integrally with the hub and extend therefrom through the annular element.
According to another aspect of the invention, the annular element can have two or more secondary apertures spaced about the primary aperture; and the elements can be provided one for each secondary aperture and extend therethrough.
According to another aspect of the invention, there can be further provided a component to which the elements extend.
According to another aspect of the invention, the component can have a socket for, and in receipt of, each element.
According to other aspect of the invention, the elements can be frictionally engaged by the component; the elements can be adhesively secured to the component; the elements can mechanically engage the component; or the elements can be welded to the component.
According to another aspect of the invention, the elements can have enlarged heads, disposed within the sockets and produced via a deformation operation, which mechanically secure the elements to the component.
According to another aspect of the invention, the annular element can have a socket for, and in receipt of, each element.
According to other aspects of the invention: the elements can be frictionally engaged by the annular element; the elements can be adhesively secured to the annular element; the elements can mechanically engage the annular element; and the elements can be welded to the annular element.
According to another aspect of the invention: the elements can have enlarged heads, disposed in the sockets and produced via a deformation operation, which mechanically secure the elements to the annular element.
According to another aspect of the invention: the annular element can have two or more secondary apertures spaced about the primary aperture; the elements can be provided one for each secondary aperture and extend therethrough; and the elements can be defined by rivets.
According to another aspect of the invention: the elements can be pins and, in the event that the disc binds in use, the pins can break, to permit the spindle to rotate freely of the annular element.
A method for producing an abrasive disc for use with an angle grinder forms another aspect of the invention. The grinder is of the type having a threaded spindle. The disc is of the type having: a central portion defining a threaded bore for receiving said spindle; and abrasive material surrounding the central portion. The method comprises: providing an annular element providing the abrasive material, the annular element having a central primary aperture and two or more secondary apertures spaced about the primary aperture; providing a hub defining the threaded bore; providing a pin for each secondary aperture; fitting each pin through the secondary aperture for which it is provided; and providing for the hub to be secured to the annular element via the pins.
According to another aspect of the invention, the pins can be provided as part of a spacer structure; the hub can have a socket for each pin; and each pin can be fitted into the socket which is provided therefor after passage through the secondary aperture for which it is provided.
According to another aspect of the invention, the pins can be secured to the hub via a mechanism selected from the group consisting of: deformation of the pin head; adhesive; welding; frictional engagement; and snap-fit.
According to another aspect of the invention, the pins can be provided as part of the hub; the annular element can have a socket for each pin; and the pins can be secured to the annular element via a mechanism selected from the group consisting of: deformation of the pin head; adhesive; welding; frictional engagement; and snap-fit.
According to another aspect of the invention, the pins can be frangible such that, in the event that the disc binds in use, the pins break, to permit the spindle and hub to rotate freely of the annular element.
Other advantages, features and characteristics of the present invention, as well as methods of operation and functions of the related elements of the structure, and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following detailed description and the appended claims with reference to the accompanying drawings, the latter being briefly described hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an abrasive disc according to an exemplary embodiment of the invention in use with an angle grinder;
FIG. 2 is an exploded view of FIG. 1 ;
FIG. 3 is a plan view of encircled structure 3 of FIG. 2 ;
FIG. 4 is a view along section 4 - 4 of FIG. 3 ;
FIG. 5 is a pre-assembly view of encircled structure 3 of FIG. 2 ;
FIG. 6 is an assembled view, similar to FIG. 4 , of the structure of FIG. 5 ;
FIG. 7 is a view, similar to FIG. 5 , of another exemplary embodiment;
FIG. 8 is a view, similar to FIG. 4 , of another exemplary embodiment;
FIG. 9 is a view, similar to FIG. 4 , of another exemplary embodiment;
FIG. 9.1 is an enlarged view of a portion of the structure of FIG. 9 ;
FIG. 10 is a view, similar to FIG. 4 , of another exemplary embodiment;
FIG. 10.1 is a detail view of encircled area 10 . 1 of FIG. 10 ;
FIG. 11 is a view, similar to FIG. 4 , of another exemplary embodiment;
FIG. 12 is a view, similar to FIG. 4 , of another exemplary embodiment;
FIG. 12.1 is a view, similar to FIG. 4 , of another exemplary embodiment;
FIG. 12 . 1 . 1 . is a perspective view of a portion of the structure shown in sectional view in FIG. 12.1
FIG. 13 is a view, similar to FIG. 4 , of another exemplary embodiment;
FIG. 13.1 is a detail view of encircled area 13 . 1 in FIG. 13 ;
FIG. 13.2 is a perspective view of a portion of the structure shown in sectional view in FIG. 13
FIG. 14 is a view, similar to FIG. 4 , of another exemplary embodiment;
FIG. 15 is a perspective view of an abrasive disc according to another exemplary embodiment;
FIG. 16 is a pre-assembly view of the structure of FIG. 15 ;
FIG. 17 is a plan view of the structure of FIG. 15 ;
FIG. 18 is a view along section 18 - 18 of FIG. 17 ;
FIG. 19 is a plan view of encircled structure 19 of FIG. 16 ;
FIG. 20 is a view along section 20 - 20 of FIG. 19 ;
FIG. 21 is a plan view of encircled structure 21 of FIG. 16 ;
FIG. 22 is a view along section 22 - 22 of FIG. 21 ;
FIG. 23 is a view, similar to FIG. 4 , of another exemplary embodiment; and
FIG. 24 is a view of encircled area 24 in FIG. 23 .
DETAILED DESCRIPTION
As indicated above, FIG. 1 shows an abrasive disc 20 according to an exemplary embodiment of the present invention in use with an angle grinder 21 . As will be readily understood by persons of ordinary skill in the art, this disc 20 is of the well-known threaded type. The grinder 21 forms no part of the invention and is illustrated for ease of reference only. As best indicated in exploded FIG. 2 , in common with other discs of this class, the illustrated disc 20 has a central portion 22 defining a threaded bore 24 for receiving the spindle 23 of the grinder 21 and has abrasive material 26 surrounding the central portion 22 . However, in contradistinction to other devices of the subject class, this disc 20 is characterized in the presence of a hub 28 which defines the threaded bore 24 , a spacer structure 30 and an annular element 32 which provides the abrasive material 26 , which together form the disc 20 , and as further described hereinafter.
FIG. 5 shows the various components 28 , 30 , 32 which ultimately form the disc 20 in a pre-assembled state, and will be initially referenced, for clarity. Hub 28 is an injection-molded plastic piece and has formed therein a pair of opposed indents 45 and four sockets 47 surrounding the threaded bore 24 . The annular element 32 providing the abrasive material 26 will be seen to include a central primary aperture 34 and two or more, specifically, four, secondary apertures 36 spaced about the primary aperture 34 . The spacer structure 30 includes a pin element 40 for each secondary aperture 36 . The spacer structure 30 also includes an annular component 38 spacing apart the pins 40 and from which the pins 40 rigidly extend.
The various pieces 28 , 30 , 32 are shown in an assembled state in FIG. 6 . In this state, each pin element 40 extends through the secondary aperture 36 for which it is provided into a respective socket 47 and the central primary aperture 34 is aligned with the threaded bore 24 in hub 28 .
In order to produce the disc 20 from the structure shown in FIG. 6 , one must merely deform the heads of the pins, through a staking process; the deformed heads are shown in the cross-section view of FIG. 4 . The deformed heads 100 mechanically engage sockets 47 . This secures the annular component 38 in spaced relation to the hub 28 , with the abrasive element 32 sandwiched therebetween. The aligned central aperture 34 providing egress for the spindle 23 to the threaded bore 24 in use.
An advantage associated with this structure is the ease by which it is manufactured. The hubs 28 and spacer structures 30 can routinely be obtained by persons of ordinary skill in the art of injection molding. For both pieces, a suitable mold material is, for example, Nylon 66. The annular element 32 providing the abrasive material 26 is routinely obtainable by persons of ordinary skill in abrasives manufacture. Indeed, but for secondary apertures 36 , annular element 32 itself can be substantially identical to abrasive structures commonly available in the marketplace. In annular elements wherein the central portion is fibreglass, secondary apertures 36 can be easily obtained through a simple punching operation. In annular elements wherein abrasive material composes the bulk of the part, apertures 36 will normally need to be produced when the central aperture 34 is produced, but again, this is a matter of routine to persons of ordinary skill.
Another advantage associated with the illustrated structure is the indents 45 which are provided on the hub 28 , which enable to disc 20 to be finger manipulated without handling the abrasive 26 . The openings in socket 47 , however, also admit the use of a conventional spanner wrench (not shown), if additional force is necessary.
Various changes in, inter alia, size and shape of parts may be made. For example, the elements need not be round pins, but could take other cross-sectional shapes.
By way of further example, FIG. 7 shows a structure with a modified annular element 32 ′ wherein the apertures 36 are contiguous with, rather than separate from, central aperture 34 .
FIG. 8 , shows a modified version of the disc 20 A, wherein another modified annular element 32 A is provided, which is substantially planar, and modified versions of the hub 28 A and spacer structure 30 A are provided which have complementary geometries.
FIG. 9 shows a further modified spacer structure 30 B. This structure 30 B is also molded out of plastic, and voids 100 are formed, so as to provide thin walled break zones 102 in the modified pins 40 B. An advantage associated with this structure is that, in the event that the disc binds in use, i.e. “grips rather than rips” the material being abraded, the pins 40 B break, to permit the spindle of the grinder to rotate freely of the annular element 30 . This can avoid wrist and other injuries that might otherwise result. In order to provide this functionality, it is important to ensure that the hub does not frictionally grip the annular element with substantial force. In FIG. 9 , this is accommodated by configuring the hub to engage against the spacer structure, as indicated at areas X, but in applications wherein a spacer structure is not provided, this can equally be accommodated by arranging the hub to bear against the locating shoulder typically found on the grinder spindle, which shoulder is indicated as part Y in FIG. 2 . The plastic chosen for molding should also be such that it tends to shear in the break zones, rather than simply deform; again, this is a matter of routine to persons of ordinary skill.
FIGS. 10 and 10 . 1 show a yet further modified disc 20 C in cross-section. In this structure, modified pins 40 C are provided, which mechanically engage modified sockets 47 C without the need for a staking operation. This structure can simply be forced together. The between the pins 40 C and sockets 47 C is of the well-known technology employed in “zip ties” and the like.
FIG. 11 shows a yet further modified disc 20 D in cross-section. In this structure, the pins are defined by rivets 40 D, i.e. provided as discrete elements, separate from the other components, and deformed to provide for securement.
FIG. 12 shows a yet further modified disc 20 E in cross-section. In this structure, the pins 40 E engage the sockets 47 E in press-fit, frictionally-engaged relation. Welding techniques, such as sonic welding, can also be employed, to strengthen the bond.
FIGS. 12.1 and 12 . 1 . 1 show a yet further modified disc 20 F in cross-section. In this structure, two modified resilient pins 40 F are provided, which engage in the socket 37 in snap-fit, mechanically-engaged relation.
FIGS. 13 , 13 . 1 and 13 . 2 show a yet further modified disc 20 G in cross-section. In this disc 20 G, the pins 40 G are provided on modified hub 28 G, and engage in snap-fit relation within sockets 47 G in modified annular element 32 G.
FIG. 14 shows a yet further modified disc 20 H in cross-section. In this disc 20 H, the pins 40 H are formed integrally with modified hub 28 H, and are deformed by a swaging operation in sockets 40 H provided within modified annular element 32 H.
FIGS. 15-22 detail a yet further modified disc 201 . In this disc 201 , pins 401 extend from modified spacer structure 301 , through primary aperture 34 in sockets 471 formed in modified hub 281 and are secured together by glue (not shown).
FIGS. 23 and 24 show a yet further modified disc 20 J. This disc 20 J is substantially similar to disc 20 , but adhesive 70 is provided to secure the various elements together.
Whereas only a finite number of exemplary embodiments are herein shown and described, the various embodiments presented above are merely examples and are in no way meant to limit the scope of this invention. Further variations of the innovations described herein will be apparent to persons of ordinary skill in the art, such variations being within the intended scope of the present application. In particular, features from one or more of the above-described embodiments may be selected to create alternative embodiments comprised of a sub-combination of features which may not be explicitly described above. In addition, features from one or more of the above-described embodiments may be selected and combined to create alternative embodiments comprised of a combination of features which may not be explicitly described above. Features suitable for such combinations and sub-combinations would be readily apparent to persons skilled in the art upon review of the present application as a whole. The subject matter described herein and in the recited claims intends to cover and embrace all suitable changes in technology and the invention.
Further, without intending to be limiting, it should be specifically understood that the invention can be incorporated into any grinding disc that normally runs with a ⅞ arbor hole on a ⅝-11 threaded spindle, and can be used with discs of varies thicknesses and types, including plastic, fibreglass and possibly even bonded.
Accordingly, the invention should be understood as limited only by the claims appended hereto, purposively construed.
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An improved abrasive disc for use with an angle grinder is disclosed. The grinder is of the type having a threaded spindle. The disc is of the type having: a central portion defining a threaded bore for receiving said spindle; and abrasive material surrounding the central portion. The improvement comprises: a hub defining the threaded bore; an annular element providing the abrasive material, the annular element having a central primary aperture aligned with the threaded bore in the hub to provide access to the bore by said spindle in use; and elements mechanically securing the hub to the annular element, for co-rotation. Apparatus and methods for producing discs are also disclosed.
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BACKGROUND OF THE INVENTION
This invention relates to tools or measuring probes (hereinafter referred to collectively or individually as tools) for use with numerically controlled (NC) machine tools or with measuring machines.
Such machines have the capability of automatically substituting different types of tools in order to perform different machining or measuring operations on a workpiece. Each tool must therefore be capable of being releasably secured to the machine easily and quickly. Where a tool includes an electric circuit within its housing, a power supply has to be provided for the circuit, and this must be positioned either on the machine or within the tool and some form of releasable electrical connection has to be made between the tool and the machine. Physical electrical connections are not favored however because of the liklihood of corrosion due to the machine environment.
It is known, for example, from U.S. Pat. No. 4,145,816 to provide a battery within a tool for powering an electric circuit, and the electrical connection between the tool and the machine is made by an inductive connection. It is also known, for example, from UK Pat. No. 2,084,737 to use a battery in the tool to power an optical telemetry system for wirelessly transmitting signals from the tool to the machine.
The use of batteries however, has its drawbacks in that, at present, battery life is low, and the batteries require regular re-charging or replacement. Another problem is that ony a limited amount of power is available from the battery, particularly where the tool housing has to be small to enable it to fit into a limited amount of space. Thus for small tools requiring a relatively high power supply, a battery-powered tool may not be the best solution.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a means for supplying power to the electric circuit of a tool which overcomes or substantially diminishes these problems.
According to the present invention there is provided a machine having a movable member capable of supporting a tool for performing an operation on a workpiece and having a supply of pressurized fluid, the tool including an electric circuit and means for releasably connecting the tool to the movable member, characterized in that the tool comprises a drive means, such as a turbine which is arranged to be driven, in operation, by pressurized fluid supplied from the machine, and an electricity generator drivingly connected to the turbine for providing power to the electric circuit.
In one form of the invention the tool comprises a fluid flow duct and means for releasably connecting the fluid flow duct to the supply of pressurized fluid, the turbine being disposed in the fluid flow duct and arranged to be driven by pressurized fluid flowing, in operation, through the duct.
Alternatively the turbine is in the form of a pelton wheel, the buckets of which are rotated by directing the pressurized fluid at them in a jet.
The pressurized fluid may be liquid or gas, a supply of which may already be present on the machine.
Also according to this invention there is provided a probe for sensing a surface of an object, comprising a sensing device including an electric circuit, characterized by a fluid flow duct, and an electricity generator for powering said circuit and adapted to be driven by fluid flow passing, in operation, through said duct.
The invention is particularly of use in cases where the electric circuit in the tool has a relatively high current consumption.
BRIEF DESCRIPTION OF THE DRAWING
An example of apparatus according to this invention will now be described with reference to the accompanying drawings in which:
FIG. 1 is a sectional elevation of the spindle assembly of a machining centre including a measuring probe, and,
FIG. 2 is a sectional elevation of an alternative form of the invention applied to a boring bar.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1 the spindle assembly comprises a spindle 10 supported for rotation in bearings 11 in a bearing housing 11A and intended to support a tool introduced to the spindle by an automatic tool change device (not shown). The tool in this example is a probe 12 for sensing a workpiece 13 for the purpose of measuring the position thereof. It is to be understood, however, that the tool may be any one of the usual types of cutting tools used for performing machining operations on the workpiece. The spindle 10 has an axis 10A defining the direction in which the tool is removed from and introduced to the spindle.
The probe 12 comprises a housing 14 having a shank 15 for releasably securing the probe to the spindle 10. The shank is tapered and is drawn into engagement with a corresponding taper in the spindle 10 by a draw bar 15A having clamping jaws 15B, operated by an operating mechanism (not shown but well known per se) at the opposite end of the spindle 10. The housing 14 supports a surface sensing device 16 including an elongate stylus 17, an electric circuit 18 and a signalling device 19 adapted to produce an optical signal 20. One end of the stylus 17 is supported in the housing 14 by electrical contacts 22 provided in the circuit 18. The other end, 23, of the stylus is free for engagement with the workpiece 13. Such engagement, which is produced by relative movement of the spindle and the workpiece, displaces the stylus from a rest position on the contacts 22 thereby breaking the circuit 18 and producing the signal 20 indicating that the surface of the workpiece has been sensed. The circuit 18 and the signalling device 19 are powered by a battery 24 arranged in the housing 14.
The battery 24 is adapted to be charged, or for its charge to be maintained, by a rotary generator 25 acting through a charge control unit (not shown). The generator 25 is driven by a turbine 26 arranged in a turbine flow duct 27 connected to a supply duct 28 provided in the shank 15. The duct 28 has inlets 28A from a duct 29 provided in the spindle 10, and the latter duct is connected to an air compressor 30 mounted on the bearing housing 11A. Compressed air supplied by the compressor 30 reaches the turbine 26 through the ducts 28,29 to drive the turbine and thus drive the generator 25. To avoid contamination of the electrical components by the fluid, the duct 27 is separated from the generator 25 by a partition 31 of non-magnetic material, and the generator 25 is coupled to the turbine across the partition by a magnetic coupling 32 having elements 32A,32B situated at opposite sides of the partition 31. The duct 27 has an outlet 27A for the air which may be ducted toward the stylus 17 to provide a cleaning flow of air over the surface to be measured.
In many machine tools a source of compressed air is already provided for cleaning the tapered shank 15 of the tool 12 immediately prior to clamping the shank taper into the spindle taper with the draw bar 15A. The compressed air is supplied through the draw bar in the centre of the spindle along a duct illustrated in dotted lines at 29A. This air supply can form an alternative supply of pressurized fluid to the turbine 26, the only modification which is required of the machine tool being the provision of an aperture or apertures 29B in the jaws 15B of the draw bar to ensure that the air passes into the duct 29. This alternative will also avoid the requirement for sealing the spindle against loss of air pressure since the fit between the tapered shank and the spindle taper will provide an effective air seal.
It will be appreciated that the spindle 10, while being rotatable for the purpose of driving rotary cutting tools, is usually held against rotation for the measuring operation.
In a modification, the probe 12 is provided with a radial extension 33 having a portion 34 extended parallel to the axis 10A and adapted to engage a socket 35, provided on the housing 11A, when the probe is introduced to the spindle 10. The socket is connected to the compressor 30 and the extension 33 and portion 34 define a duct 36 leading to the turbine flow duct 27 to feed compressed air thereto. In this modification the duct 28 in the shank 15 is dispensed with and the turbine is driven by flow through the duct 36.
However, most machine tools provide a supply of liquid lubricant for the cutting process and generally this supply is provided close to the end of the spindle. In these circumstances the socket 35 to which the extension portion 34 connects may communicate with a supply of liquid under pressure, and this would provide a greater source of energy for the turbine 26.
FIG. 2 illustrates diagrammatically a further alternative method of generating electricity at the tool itself. In this embodiment a collar 40, including an annular multi-pole magnet, is mounted for rotation on bearing surfaces 41 on the outside of the housing 42 of the tool 48. A coil or coils 43 are provided on the inside of the housing for generating electricity to charge a battery 44 within the tool for powering an electrical circuit 45 which drives an electric motor 46 within the tool housing.
A turbine in the form of a Pelton Wheel is provided around the outer periphery of the collar. The Pelton Wheel has buckets 47 which can be driven by directing a supply of pressurized fluid onto them. A convenient source of pressurized fluid would be the nozzles which provide cutting liquid, as shown at 49, which are normally available on a machine tool. This arrangement allows for electricity generation by the tool without any modification of the existing machine tool design.
In this illustration the tool is a boring bar having a cutter 50 the position of which is capable of being adjusted transversely to the spindle axis by means of the electric motor, as is known per se, to vary the diameter of a hole which may be bored in a workpiece.
Still further alternative embodiments of this invention are possible. For example a magnetic collar could be mounted for rotation within the housing, or axially on one end of the tool, and suitable integral turbine blades of any convenient type can be provided on it. The electricity generating coil or coils would be appropriately positioned to generate electricity from the rotation of the magnet. The fluid used to drive the turbine on the collar may then be supplied externally or internally as described hereinbefore. Alternatively, the collar may simply support a bar or cruciform magnet rather than itself being a magnet.
The invention may be applied to a machine tool in which the spindle is axially extendible in addition to being rotatable but in such machine tools the provision of pressurized fluid at the tool involves significantly more difficult sealing problems for the machine tool designer if continuous operation of the turbine is required while the spindle is moving axially.
It will also be understood that in some forms of tooling the circuit may have to be kept live even when the tool is stored, in which case the battery as described in both embodiments is essential. However, where this is not the case the battery may be eliminated and the probe made live by the flow of pressurized fluid passing through the turbine and generating sufficient current to power the circuit.
It will also be understood that the embodiment of the invention described in FIG. 2 as applied to a boring bar could be applied to any other form of tool including the measuring probe of FIG. 1, and that the embodiment described in FIG. 1 as applied to a measuring probe could be applied to any other tool including the boring bar of FIG. 2.
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A machine has a movable member capable of releasably supporting a tool for performing an operation on a workpiece, and a supply of pressurized fluid. The tool includes an electric circuit which is provided with power from an electrically generator drivingly connected to a turbine driven by the machine's supply of pressurized fluid. The turbine may be in the form of a Pelton Wheel, the buckets of which are rotated by directing the pressurized fluid at them in a jet. The pressurized fluid may be a liquid or a gas. The tool may take one of several alternative forms, such as a boring bar or measuring probe.
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TECHNICAL FIELD
The present invention is related to a lock structure of a connector.
BACKGROUND ART
As a conventional lock structure of a connector, such a lock structure as shown in FIGS. 5 and 6 has been disclosed (see PTL 1). FIG. 5 is a perspective view of an entirety of a lock part, and FIG. 6 is a partial sectional view showing the lock part in a female connector housing.
Both side faces of a lock part 105 in a female connector housing 101 are formed in a shape of a half arrow head extending in a fitting direction, and a releasing lever part 107 is formed of these side faces. In a front end part (an end part at a forehand side in FIG. 5 ) of the releasing lever part 107 , there is formed a front edge part 111 so as to extend over an entire width in a lateral direction. Two lock arms 109 in a plate-like shape are extended backward substantially horizontally from the front end part 111 . As shown in FIG. 6 , respective back end parts (at a deep side in FIG. 5 ) of the two lock arms 109 are bent downward, and connected to a horizontal wall part 101 a of the female connector housing 101 to be formed into fixed ends 109 a.
An intermediate part of the front edge part 111 between the two lock arms 109 which are spaced in the lateral direction is formed as a latch part (a lock engaging part) 111 a for locking a locking part of a male connector housing (not shown).
On the other hand, a lower end part of the releasing lever part 107 is at the substantially same position in the fitting direction as the fixed ends 109 a in the back end parts of the lock arms 109 , and constitutes a supporting part 107 a which performs as a pivot of rotation of the releasing lever part 107 at a time of lock releasing operation. In a state where the female connector housing 101 exists by itself, there is a gap between this supporting part 107 a and the horizontal wall part 101 a of the female connector housing 101 (See FIG. 6 ).
A flat face part of the releasing lever part 107 which is spread backward than the supporting part 107 a over the entire width constitutes a finger hooking part 117 .
According to the lock structure as described above, the releasing lever part 107 for releasing the locked condition between the male connector housing and the female connector housing 101 , utilizing a lever action, is provided so as to be continued from the latch part 111 a of the lock arms 109 . Therefore, when the latch part 111 a of the lock arms 109 are deformed by a predetermined amount, occurrence of an excessive stress to be exerted on the fixed ends 109 a of the lock arms 109 can be prevented. As the results, the lock arms 109 may be broken.
CITATION LIST
Patent Literature
[PTL 1] JP-A-2001-250636
SUMMARY OF INVENTION
Technical Problem
In a tendency of downsizing the connector, it is requested that the lock structure of the connector is also downsized. For this purpose, it is necessary to make the lock arms 109 shorter in length. However, in case where the lock arms 109 are simply made shorter, rigidity of the lock arms 109 is enhanced, and the lock arms 109 are hardly deformed in a curve.
When a force for displacing the latch part 111 a upward is applied to the lock arms 109 , on occasion of locking or unlocking, there is such possibility that the stress may be concentrated on the fixed ends 109 a , resulting in breakdown of the lock arms 109 .
It is therefore one advantageous aspect of the present invention to provide a lock structure of a connector in which flexibility of lock arms can be maintained, even in case where the lock arms are made shorter in length, while the lock structure itself can be downsized according to a request for downsizing the connector.
Solution to Problem
According to one advantage of the invention, there is provided a lock structure of a connector, in which a first connector housing and a second connector housing to be engaged with each other are locked in a releasable manner, the lock structure comprising:
a flexible lock arm, fixed to a wall part of the second connector housing at a base end portion of the flexible lock arm, and extended in a fitting direction in which the second connector housing is fitted with the first connector housing;
a lock engaging part, provided at a distal end portion of the flexible lock arm, and configured to be locked with a locking part provided in the first connector housing; and
a releasing lever part, connected to the lock engaging part at one end portion of the releasing lever part, extended along the flexible lock arm, and configured to be rotated together with the lock engaging part around a pivot which is movable while releasing the lock,
wherein a thickness of the flexible rock arm is gradually decreased from the base end portion to the lock engaging part.
Advantageous Effects of Invention
According to the lock structure of the connector having the above described structure, when the first and second connector housings are engaged with each other, a member for resisting displacement of the lock engaging part is only the lock arm of a cantilever type. Moreover, the lock arm is formed in such a manner the thickness of the lock arm in the cross sectional plane is gradually decreased from the base end portion to the lock engaging part. Therefore, even in case where a total length of the lock arm is made shorter, the distal end side of the lock arm can be deformed in a curve, and stress exerted on the base end portion can be dispersed. As the results, it is possible to prevent breakdown of the lock arm.
At the time of the lock releasing operation, the locked state is released, by rotating the lock engaging part together with the releasing lever part around the pivot. On this occasion, because a position of the pivot of the rotation can be displaced, the lock engaging part is rotated without resistance, and the lock arm which is deformed will not receive an excessive load. As the results, a problem of being short of rigidity will not occur.
According to the lock structure of the connector according to the invention, it is possible to provide the lock structure of the connector in which flexibility of the lock arm can be maintained, even in case where the lock arms are made shorter in length, while the lock structure itself can be downsized according to a request for downsizing the connector.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a perspective view of an entirety of a lock part in a lock structure of a connector in an embodiment according to the invention.
FIG. 2 is a partly broken perspective view showing a second connector housing in the embodiment according to the invention.
FIG. 3 is a partial sectional view showing the lock part of the second connector housing as shown in FIG. 2 .
FIG. 4A is a partial sectional view showing operation of the first and second connector housings in the embodiment according to the invention, in a state where the lock part is not locked to a locking part.
FIG. 4B is a partial sectional view showing the operation of the first and second connector housings in the embodiment according to the invention, in a state where the lock part is locked to the locking part.
FIG. 5 is a perspective view of an entirety of a conventional lock part.
FIG. 6 is a partial sectional view showing the conventional lock part in a female connector housing.
DESCRIPTION OF EMBODIMENTS
Referring to the drawings, a lock structure of a connector in an embodiment according to the invention will be described in detail.
As shown in FIG. 1 , both side faces of a lock part 5 of a female connector housing (a second connector housing) 1 in the embodiment are formed in a shape of a half arrow head extending in a fitting direction (a longitudinal direction of the lock part 5 ), and a releasing lever part 7 is formed of these side faces. A front edge part 11 extending over an entire width in a lateral direction is formed in a front end part (an end part at a forehand side in FIG. 1 ), which is one side end of the releasing lever part 7 .
Two lock arms 9 in a plate-like shape are extended backward substantially horizontally from the front edge part 11 . As shown in FIG. 2 , respective back end parts (at a deep side in FIG. 1 ) of the two lock arms 9 are bent downward, and formed into base end portions 9 a which are connected to a horizontal wall part (a wall part) 1 a of the female connector housing 1 .
The front edge part 11 at an intermediate between the two lock arms 9 which are spaced in the lateral direction is provided with a lock engaging part 20 to be locked to a locking part 13 of a male connector housing (a first connector housing) 3 (See FIG. 4 ), so as to project from a face thereof (a lower face in FIG. 3 ) opposed to the female connector housing 1 .
Each of the lock arms 9 is formed in such a manner that a thickness H 2 in a cross sectional plane near the lock engaging part 20 is smaller than a thickness H 1 in a cross sectional plane of the base end portion 9 a , and the thickness of the lock arm 9 in the cross sectional plane is gradually decreased from the base end portion 9 a to the lock engaging part 20 .
Sign f represents an overhanging amount of the lock arm 9 from the base end portion 9 a to the lock engaging part 20 (See FIG. 3 ). Reference numeral 15 in FIG. 3 represents a seal member.
On the other hand, a lower end part of the releasing lever part 7 is at the substantially same position in the fitting direction as the base end portion 9 a at a back end side of the lock arm 9 , and constitutes a supporting part 7 a which functions as a pivot of rotation of the releasing lever part 7 at a time of lock releasing operation, which will be described below. In a state where the female connector housing 1 exists by itself, there is a gap d between this supporting part 7 a and the horizontal wall part 1 a of the female connector housing 1 (See FIG. 3 ).
A flat face of the releasing lever part 7 which is spread backward than the supporting part 7 a over the entire width constitutes a finger hooking part 17 for the lock releasing operation. Sign g represents a distance from the supporting part 7 a to a back end of the finger hooking part 17 , and sign h represents a distance from the supporting part 7 a to the lock engaging part 20 .
Then, operation of the lock part 5 when the two connector housings 1 and 3 are engaged and disengaged (at the time of the lock releasing operation) will be described referring to FIGS. 4A and 4B .
FIG. 4A shows a state just before the male connector housing 3 is locked to the female connector housing 1 , while they are engaged with each other. When the engagement between the two connector housings 1 , 3 proceeds, the locking part 13 of the male connector housing 3 comes into contact with the lock engaging part 20 of the lock arm 9 , and pushes up the lock engaging part 20 . On this occasion, the lock arm 9 receives an upward bending moment around the base end portion 9 a at the back side. A radius of action of a pushup force is the overhanging amount f.
The lock arm 9 in this embodiment is formed in such a manner that the thickness thereof in the cross sectional plane is gradually decreased from the base end portion 9 a to the lock engaging part 20 . The cross sectional plane in which the thickness is defined is a plane in which the lock arm 9 is deformed. Therefore, even in case where a total length of the arm is made smaller, a distal end side of the lock arm 9 can be deformed in a curve, and an angle of flexure near the base end portion 9 a of the lock arm 9 , when the lock engaging part 20 is pushed up, can be made smaller. As the results, it is possible to prevent breakdown of the lock arm 9 , by dispersing the stress to be exerted on the base end portion 9 a.
As the lock arm 9 is deformed and bent, the supporting part 7 a of the releasing lever part 7 which is continued from the front edge part 11 (the lock engaging part 20 ) moves downward, and comes into contact with the horizontal wall part 1 a of the female connector housing 1 , making the gap d zero. When the locking part 13 has passed the lock engaging part 20 , the lock arm 9 which has been pushed up by the lock engaging part 20 and deformed is restored to its original state, and thus, the male connector housing 3 is locked. In the locked state, the gap d of the supporting part 7 a is recovered. Although a posture of the releasing lever part 7 changes while the locked state is achieved, this change in posture can be freely performed, without being affected by the other members.
FIG. 4B shows a state where the lock between the two connector housings 1 and 3 is released. In order to release the lock, the finger hooking part 17 at the back end of the releasing lever part 7 is pushed downward. With this pushdown operation, the supporting part 7 a of the releasing lever part 7 is moved downward and brought into contact with the horizontal wall part 1 a of the female connector housing 1 . Even in case where the finger hooking part 17 is further pushed downward after the contact, a lifting moment to be exerted on the lock engaging part 20 is equal to a moment of pushing down the finger hooking part 17 around the supporting part 7 a , due to a lever action. Because the radius h of the rotation of the lock engaging part 20 around the supporting part 7 a is set to be larger than the radius g of the rotation at a side of the pushdown operation, the force for lifting the lock engaging part 20 is smaller than the force for pushing down the finger hooking part 17 . Therefore, there is no such anxiety that the lock arm 9 may be short of rigidity.
The cross sectional plane in which the thickness of the lock arm 9 is defined is a plane in which the finger hooking part 17 moves downward by being pushed.
As described hereinabove, according to the embodiment, as different from the prior art, the releasing lever part 7 for releasing the locked state between the male and female connector housings 3 and 1 , utilizing the lever action, is provided in a manner continued from the lock engaging part 20 of the lock arm 9 , and the thickness of the lock arm 9 in the cross sectional plane is so formed as to be gradually decreased from the base end portion 9 a to the lock engaging part 20 . Therefore, even in case where the total length of the lock arm is made smaller, the distal end side of the lock arm 9 can be deformed in a curve, and the stress exerted on the base end portion 9 a can be dispersed. As the results, it is possible to prevent breakdown of the lock arm 9 .
In the lock part 5 in the above described embodiment, an R part 22 is formed in an upper part at the distal end side of the lock arm 9 which is extended backward from the front edge part 11 , and therefore, the thickness of the lock arm 9 in the cross sectional plane at the distal end side is larger than the thickness H 2 in the cross sectional plane near the lock engaging part 20 . However, the thickness of the lock arm 9 in the cross sectional plane is so formed as to be gradually decreased from the base end portion 9 a to the lock engaging part 20 , as described above, and hence, the distal end side of the lock arm 9 can be sufficiently deformed in a curve.
It is of course possible to appropriately modify a shape of the lock arm 9 at the distal end side, so that the thickness of the lock arm 9 in the cross sectional plane may be gradually decreased from the base end portion 9 a to the lock engaging part 20 .
The lock structure of the connector according to this invention is not limited to the above described embodiment, but various modifications, improvements, and so on can be appropriately made. Further, materials, shapes, sizes, numbers of the respective constituent elements in the above described embodiment are not limited, but optional, provided that the invention can be achieved.
The present application is based on Japanese Patent Application No. 2011-195370 filed on Sep. 7, 2011, the contents of which are incorporated herein by way of reference.
INDUSTRIAL APPLICABILITY
According to a lock structure of a connector of the invention, flexibility of lock arms can be maintained, even in case where the lock arms are made shorter in length, while the lock structure itself can be downsized according to a request for downsizing the connector.
REFERENCE SIGNS LIST
1 Female connector housing (second connector housing)
1 a Horizontal wall part (wall part)
3 Male connector housing (first connector housing)
5 Lock part
7 Releasing lever part
7 a Supporting part (pivot)
9 Lock arm
9 a Base end portion
11 Front edge part
13 Locking part
17 Finger hooking part (releasing operation part)
20 Lock engaging part
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A lock structure of a connector includes a flexible lock arm, a lock engaging part and a releasing lever part. The flexible lock arm fixed to the second connector housing at a base end portion thereof is extended in a fitting direction of the connector. The lock engaging part provided at a distal end portion of the flexible lock arm is configured to be locked with a locking part provided in the first connector housing. The releasing lever part connected to the lock engaging part is extended along the flexible lock arm, and is configured to be rotated together with the lock engaging part around a pivot which is movable while releasing the lock. A thickness of the flexible rock arm is gradually decreased from the base end portion to the lock engaging part.
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BACKGROUND OF THE INVENTION
a. Field of Invention
This invention pertains to a blade used on a doctor for a pulp or papermaking machine, and more particularly to a blade made of a fiber enforced composite material.
Pulp or papermaking machines, utilize machine rolls. Such machine rolls are used during various aspects of the process, for example, in the forming, pressing, drying or calendering sections. The operation of machine rolls requires a device to remove contaminants which form on the roll surface and/or to peel off a sheet or web from the rolls. A traditional method of achieving this is through the use of a mechanical device commonly referred to as a doctor or doctor blade. The failure to remove the contaminants or the sheet effectively can have a catastrophic effect on the quality of the product being produced.
The doctor blade is typically fastened to a structural beam which is adjustably supported across the papermaking machine on which a blade holder and a replaceable blade is provided. The doctor blade comes in direct contact with the roll surface so as to scrape off any contaminants from the roll surface including the whole pulp or paper web sheet or parts thereof.
b. Description of the Prior Art
There is a plurality of different doctor blade types having dimensions and materials commonly available in the industry, as well as different designs of blade holders. Laminated plastic doctor blades and blade holders such as type KF-35, KF-35A or PNEUFLEX blade holder are manufactured by Albany International Corporation, the assignee of the present invention. For obvious reasons the blade should be securely attached to the blade holder as a doctor without a blade will not scrape anything from the roll, and as aforesaid, this will have a catastrophic effect on the machine production. But even worst, the blade or a part thereof can come off and fall in the process where it will irreparably damage the pulp or paper machine clothing, and possibly the roll, because of direct and sudden contact with the blade holder.
The ultimate solution to prevent the aforesaid catastrophic situation would be to permanently fasten the blade to the holder or to make it as an integral part of the holder. But, doctor blades do wear with time. Depending on the application, they can last anywhere from a few hours to several months. Therefore, a doctor blade must be a replaceable item. The blade and holder design should allow for easy, fast and safe blade replacement so as to insure that neither the blade or part thereof, like the fastening devices for example, will come off and fall into the process.
A common design in the industry is to put along one edge of the blade, some types of rivets, or some other mechanical retainers that could be, for example, rivetted, glued, or press-fitted to the blade. The holder is then manufactured with a slot incorporating a step or a groove. The edge of the blade with the retainers can be slid into the groove through one end of the holder. Alternative designs are also available which allow a blade to be removed from the front of the holder, for the few applications where the access through the ends is limited. However, all these designs although widely used in the industry have a significant drawback as very often a retainer will come off the blade, and will either fall into the process, or will stay in the holder but become wedged into the blade slot, thus making the blade very difficult to slide in or out.
Another design used in the industry consist of making the blade with built-in retainers whereby there is no mechanically fastened part on the blade that can come off. One known way to do this is to machine the blade out of thicker material, leaving a narrow step along one edge that will retain the blade in the holder slot. This method is widely used to manufacture polyethylene doctor blades, where machining is fast and easy, and where thicker material is also required to add strength or to increase wear life. Theoretically, this method can be used to manufacture blades out of other popular materials, like metal or laminated plastic. However, the extended cost of the material and machining time combined with the high amount of tooling required, render this method simply undesirable. Moreover, it would not be suitable for the front removable blade design.
Another known way of making built-in retainers to the doctor blade is to stamp or punch pairs of short recesses along one edge of the blade at a certain spacing, to simulate the function of the rivets of the first design. A typical drawing of the industry standard is shown in FIGS. 1 and 2. However, this design has been used only to manufacture metallic doctor blades, such as bronze or stainless steel for example. It was believed that the mechanical properties of synthetic material used in the doctor blade industry, those of laminated glass fiber reinforced plastic, for example, did not allow this method to be used on plastic blades. All the laminated composite doctor blades known to be used on the pulp or paper machines today, are manufactured with add-on retainers that are either rivetted, glued, or press-fitted along one edge of the blade, a design with major disadvantages as described above. One such prior art rivetted composite doctor blade is shown in FIG. 3.
OBJECTIVES AND SUMMARY OF THE INVENTION
It is therefore a principle objective of the invention to provide a laminated plastic doctor blade with built-in retainers, thereby offering all the advantages relating to this design yet cost effective to manufacture.
A blade is made in accordance with this invention by taking an elongated strip of reinforced composite material and punching a plurality of elongated recesses adjacent to a longitudinal side of the material. The recesses are formed by making cuts which are made long enough so that the plastic or permanent deformation of the material in the region around each recess is avoided. The cuts are made by a method which fibrillates the material along the plane of the cut so that irregularities are formed in the material along the cut which prevent the recessed material from returning to a normal position.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a plan view of a prior art metallic doctor blade discussed above;
FIG. 2 shows a partial side view of the prior art doctor blade of FIG. 1;
FIG. 3 shows a side view of a rivetted plastic prior art doctor blade;
FIG. 4 shows a plan view of a plastic laminated doctor blade constructed in accordance with this invention;
FIG. 4A shows an enlarged partial plan view of the blade of FIG. 4;
FIG. 4B shows an end view of the doctor blade of FIG. 4;
FIG. 5 shows a partial side view of the doctor blade of FIGS. 4, 4A, 4B;
FIG. 6 shows a partial sectional view taken along line VI--VI in FIG. 4;
FIG. 7 shows a doctor blade constructed in accordance with this invention inserted into a blade holder;
FIG. 8 shows a side view of the holder of FIG. 7 being inserted into the holder;
FIG. 8A shows an alternate embodiment for the holder and blade of FIG. 8;
FIG. 9 shows a front view of a punch-and-die assembly used to punch the recess in the blade of FIGS. 4-8;
FIG. 10 shows an end view of the punch-and-die assembly of FIG. 9;
FIG. 11 shows a plan view of an alternate embodiment of the invention;
FIG. 12 shows a side view of the embodiment of FIG. 11;
FIG. 13 shows a plan view of yet another alternate embodiment of the invention;
FIG. 14 shows a blade holder for the embodiment of FIG. 13; and
FIG. 15 shows yet a further embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1 and 2, one known doctor blade 10 consists of an elongated strip 12 made of stainless steel, bronze, or other alloys. One longitudinal side 14, strip 12 is beveled to form an edge. Along the opposite side, strip 12 is provided with a plurality of short punchings 16 punched into the member 12. Preferably, punchings 16 are formed in pairs as shown, and each punching is about 3/8" (9.5 mm) long. These punchings are made by permanently or plastically elongating and deforming the material of the strip to form the shown structure. This process could not be used on a reinforced composite blade because such materials are fragile and when they are punched they do not deform plastically, but rather they break quickly.
FIG. 3 shows another prior art doctor blade 18 made of a composite plastic material which at regular intervals is provided with a protruding rivet 19.
A doctor blade 20 constructed in accordance with the present invention and shown in FIGS. 4, 4A, 4B, 5 and 6 consists of a strip 22 a plastic material such as a fiber reinforced laminated plastic material having a plastic laminated base of, for example, a vinyl ester reinforced by fiberglass fibers. In a preferred embodiment of the invention, strip 22 is about 0.060 (1.5 mm) thick, and 3" (78 mm) wide. One side 24 of strip 22 is bevelled at an angle of about 45° to form a sharp doctoring edge 25. Adjacent to the other side 26 of the strip 22, there are a plurality of tabs or recesses 30 extending along the length of the strip. At least one end of the strip 22 is provided with a through hole 32 by which the strip can be grabbed so that it can be removed from a holder.
As shown in more detail in FIG. 4A, each recess 30 is formed by making two parallel cuts 34, 36 in the strip 22. Because the strip is made of fiber glass reinforced composite material, as described above, the cuts 34, 36 are not perfectly planar, but are somewhat irregular with the inner surfaces of the cuts having a plurality of irregular fibrillations 38 (shown in FIG. 6). (For the sake of clarity, in FIG. 4A the irregularities of cuts 34 and 36 are shown somewhat exaggerated).
Preferably, simultaneously with the cutting, the strap 40 is pushed out laterally with respect to the strip 22 to form the corresponding recess. The length and spacing of the cuts 34, 36 and their distance from side 26 are selected to insure that as the recess is formed the material around the cuts is deformed substantially, elastically, whereby the strip 22 is not permanently deformed. In this manner, the strap 40 is not broken off but remains attached to the strip at both ends to form the recesses. The strap 40 is retained in the position shown in FIG. 6 by the interference created between the irregularities or fibrillations on the surfaces formed by cuts 34, 36. Typically, each strap 40 may be, for example, about 1" (25 mm) long and 3/16" (4mm) wide, and may be disposed at least 1/8" (3mm) away from edge 26.
Referring now to FIGS. 7 and 8, a typical flexible doctor blade holder 50 consists of an elongated first member 52 secured to a frame (not shown). Several fingers 58 equally spaced along first member 52 as shown. Each finger 58 includes a channel 66. After blade 20 is formed as described above with reference to FIGS. 4-6, it may be inserted into the holder by sliding it into cavity 62 in direction A, with recesses 30 sliding through channel 66. A sharp tool may be used to engage hole 32 to pull the blade into the holder. The holder is made to have dimensions just slightly larger than the blade whereby, once the blade is seated in its place it is maintained there by interference fit with the holder. Additionally a hole 70 may be made at the ends of the holder. After the blade is inserted a pin is then introduced through hole 70, and hole 32 in the blade, thereby securing the blade in place. In FIG. 7 blade shown with edge 25 positioned for doctoring a roller 64.
The fingers 58 are spaced at a preselected distance of, for instance, 2 inches. For the embodiment of FIG. 8, in order to insure that at least some of the recesses 30 are captured between the fingers 58 and member 52, they are spaced at odd intervals, i.e. an odd number of inches.
In the preferred embodiment of FIG. 8A, the blade 20 is not inserted longitudinally. Instead the blade 20 is first positioned so each recess 30 is disposed between two fingers 58 and the blade is advanced laterally between plate 52 and fingers 58. The blade is then moved longitudinally, as indicated by arrow B until the recesses 30 are captured within channels 66 of fingers 58 and member 52. For this embodiment the recesses 30 must be spaced evenly with the spacing of the fingers 58. The blade may now be secured as described above. This embodiment is used in environments where there is insufficient lateral space to slide the blade longitudinally into the holder.
FIGS. 9 and 10 show a punch-and-die assembly 80 which may be used to make the recesses 30 in a strip 22. The assembly 80 includes a table 82 with two vertical uprights 84, 86. On table 82 there is a blade holder 88 for holding a blade 22. A lip 90 on holder 88 helps position the strip 22. The holder also has an arcuate depression 92 positioned at a distance from lip 90 to define the position and dimensions of the recesses. Above the table 82 there is a member 94 movable vertically on the uprights 84, 86 as shown. This member 94 has a lower extension 96 disposed exactly above depression 92 and dimensioned to be complementary in size and shape to the depression. Thus, without the strip 22, when the member 94 lowered on the holder 88, extension 96 fits snugly into depression 92.
The operation of assembly 80 is obvious from the above description. The strip 22 is first placed on holder 88 and then the member is forcefully lowered or dropped onto the strip 22. The shear formed at the interface between extension 96 and depression 92 generates the cuts 34, 36, and strap 40, and extension 96 pushes the strap 40 down to deform it elastically to form a recess. After each recess is made the strip is repositioned for the next recess by shifting it laterally. Alternatively the assembly 80 may be modified to make all the recesses simultaneously. Of course, other devices may be used to make the recesses as well.
An alternate embodiment of the invention is shown in FIGS. 11 and 12. In these Figures, strip 100 is made with two sets of recesses 102, 104 the difference between the two sets being that while recesses 102 are punched from the bottom, recesses 104 are punched from the top of strip 100 as shown. In the embodiment of FIGS. 11 and 12 the recesses 102, 104 are in line.
A further embodiment of the invention is shown in FIG. 13 wherein strip 110 is also formed with two sets of recesses 112, 114. However in this latter embodiment recesses 112 are laterally offset from recesses 114. A holder 116 for a doctor blade made like strip 110 is shown in FIG. 14. In this Figure, the holder 116 is made with a much wider channel 118 to accommodate both recesses 112, and 114 as shown.
Finally, the recesses may be formed by means other than two parallel cuts. For example as shown in the embodiment of FIG. 15, a blade 120 may be made with recesses 122 formed by a single curve, dimensioned and shaped to cut out sufficient material to allow elastic deformation. As previously described, the recess will hold in place because of the fibrillation of the material along the curved cut.
Similarly, numerous other modifications may be made to the invention without departing from its scope as defined in the appended claims.
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A doctor blade is made from an elongated strip of reinforced composite material which material forms fibrillated protrusions when cut. A plurality of cuts are made in the material which form recesses or tabs. The recesses are offset to increase the effective thickness of the strip so that it can be inserted longitudinally or transversely into a doctor blade holder. The fibrillated protrusions maintain the recesses in an offset position.
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TECHNICAL FIELD OF THE INVENTION
[0001] This invention relates to automated assembly equipment and more particularly to a manipulator/end effector head for robotic assembly.
BACKGROUND OF THE INVENTION
[0002] Robotics are commonly used today for the processing and/or assembly of miniature and subminiature assemblies. Robotics are used, amongst other things, to pick up and move parts from a storage area to processing and assembly areas. Robotics can also be used to orient the part and hold it in position for assembly or move the part to an assembly position and help effect assembly of two or more parts to make an assembly. For example, a semi-conductor chip can be taken from a storage area and then placed into a socket on a circuit board after which the chip would be soldered in place on the circuit board. Robotics can move in various directions including X-Y-Z and θ (rotation). As parts to be assembled have become smaller and more complex, the robotics must be more precise in both their ability to pick up and hold a part in a proper position for processing, and also to move the part to a position with greater precision in its placement relative to a processing device or another part to which it is to be joined or otherwise assembled. For many operations, the location accuracy needs to be on the order of about 1 micrometer (μm) (0.00004 inches).
[0003] To achieve higher dimensional or location precision, machine vision systems are used to allow viewing of a part and fiducial points accurately positioned on the part so that the vision system can precisely detect and determine the location of the part and points thereon. In one form of machine vision system controlled robot, the vision system views the part that is held stationary and the robot moves another part to it for assembly therewith. After determining the location of the stationary part, the robot then moves the other part into position and assembles the two parts together. However, such a vision system and associated controller assumes the relative position between the two parts while they are some distance apart which is an acceptable method unless the requirements for placement is very stringent. Such a vision system is typically mounted on the side of a robot and moves therewith. After locating the stationary part, the controller then effects movement of the second part to the first part assuming precise relative positions. Such systems can also be used to move a part to be processed from a pick-up station to processing stations, say for example, for the application of glue or other type of liquid thereto and then to an assembly station for subsequent assembly with a stationary part. Such apparatus with associated vision systems have been effective for lower precision work. However, they have not always been as effective as desired for higher precision work. Thus, there is a need for an improved apparatus and method for processing of parts requiring high precision placement for processing.
SUMMARY OF THE INVENTION
[0004] The present invention provides an apparatus for processing miniature and sub-miniature parts using robotics for moving and placing parts. In one aspect of the invention, the apparatus includes an X-Y manipulator for accomplishing the coarse movement of the gripper and the part once gripped. A second device is provided for fine X, Y, Z, and θ movement of the gripper and part carried thereby. A machine vision system is provided that is operable to view the part at a processing station and to provide a signal indicative of the part's location relative to either another part or a processing device and to help guide the part into the proper location by the continued viewing of the part during the final movement or to provide ongoing information about the location such that any assumption regarding part location when the part is not being viewed will cause minimal error with subsequent part movement.
BRIEF DESCRIPTION OF THE DRAWING
[0005] For a more complete understanding of the device and advantages thereof, reference is now made to the following descriptions in which like reference numerals represent like parts:
[0006] [0006]FIG. 1 a is a front elevation view of an apparatus used for robotically moving and assembling parts;
[0007] [0007]FIG. 1 b is an elevation view of the apparatus of FIG. 1;
[0008] [0008]FIG. 1 c is a cutaway overhead view of the apparatus;
[0009] [0009]FIG. 2 is a partially cutaway view of a manipulator device;
[0010] [0010]FIG. 3 is a cutaway view of one side of a manipulator device;
[0011] [0011]FIG. 4 is a cutaway view for a second side of the manipulator device; and
[0012] [0012]FIG. 5 is an enlarged view of the gripper.
DETAILED DESCRIPTION OF THE INVENTION
[0013] [0013]FIG. 1 a is a front view of an assembly system 100 , FIG. 1 b is a side view of assembly system 100 and FIG. 1 c is a cutaway overhead view of the assembly system 100 . Illustrated in these drawings are an assembly system 100 . Assembly system 100 includes a top portion 102 coupled to a base portion 104 using isolation pad 106 . Top portion 102 is preferably manufactured from granite. Top portion includes a top surface 102 a and a bottom surface 102 b . Base portion 104 is preferably manufactured using a welded structural steel. Isolation pad 106 is manufactured from urethane. Top portion 102 , base portion 104 and isolation pad 106 together form an assembly system that is extremely rigid and vibration free.
[0014] Inside top portion 102 and coupled to a top surface 102 a is a robot platen 108 . Coupled to robot platen 108 is a manipulator device 110 . Robot platen 108 in one embodiment is a steel plate. Manipulator device 110 , discussed in further detail below, has magnets distributed about the portion that couples to the steel plate and is able to move about the steel plate. This is accomplished by injecting compressed air between the manipulator device 110 and the robot platen 108 . This forms what is commonly known as an air bearing between the manipulator device 110 and robot platen 108 .
[0015] Inside top portion 102 and coupled to a base plate 102 b are a part processing station 114 , part assembly station 112 , and a part pick up station 116 . Adhesive dispense system 114 is operable to apply an adhesive to a work piece and is discussed in further detail in copending application entitled “ADHESIVE DISPENSING AND VISION SYSTEM FOR AN AUTOMATIC ASSEMBLY SYSTEM”, Ser. No.______ and filed May 25, 2001. The disclosure of the co-pending application is incorporated herein by reference.
[0016] Part assembly station 112 is an area where an object may be assembled with another. Part pickup station 116 is an area where manipulator device 110 can pick up a part.
[0017] Bottom portion 104 provides a rigid support base for top portion 102 . Bottom portion 102 also provides an area to place an AC distribution enclosure as well as mount controls and provide various storage areas.
[0018] A computer 150 including is provided to control the manipulator device 110 , part processing station 114 and other parts of the system 100 . Computer 150 can be any general purpose computer, such as a small office computer running the WINDOWS operating system, as sold by Microsoft, Corp. of Redmond, Wash. Computer 150 will typically include a display screen, keyboard, sensor inputs and other input output connections.
[0019] In operation, under computer control or, optionally under manual control, manipulator device 110 utilizing the air bearing formed between manipulator device 110 and robot platen 108 , will move over to part pickup station 116 where it will get a workpiece. Manipulator device 110 will then move the workpiece to the part assembly station 112 such as an adhesive dispensing system 114 . There, the adhesive dispensing system 114 applies adhesive to the workpiece. The manipulator device 110 will then move the work piece to part assembly station 112 where the manipulator device 110 will place the work piece onto a second workpiece while applying force to connect the two workpieces.
[0020] Referring now to FIGS. 2, 3 and 4 , FIG. 2 is a partially cutaway isometric view of the manipulator device, FIG. 3 is a cutaway view of the side of the manipulator device and FIG. 4 is a second cutaway side view. As seen in those figures, manipulator device 110 includes a coarse stage 202 . In the illustrated structure, the coarse stage 202 utilizes a Normag Dual Axis Linear Stepper Motor Forcer unit (available from NORMAG Corp. of Santa Clarita, Calif.) which is in the form of a planar motor that is magnetically suspended from the robot platen 108 . Compressed air is injected between an upper plate 203 of coarse stage 202 and robot platen 108 to provide what is generally referred to as a frictionless air bearing between the upper plate 203 and the platen 108 . Coarse stage 202 contains the planar motor which is operable to move the manipulator device 110 in X and Y directions as directed by signals from a controller connected thereto. Coarse stage 202 carries and moves the rest of the manipulator device 110 including the various means for fine movements. Coupled to coarse stage 202 are fine X movement stage 204 and fine Y movement stage 206 . The X axis movement is accomplished through the X axis motor 204 while the Y movement is accomplished by the Y axis motor 206 . The motors 204 , 206 accomplish the fine X-Y movement and encoders can be used with the motors to provide information about the amount of movement and location. The X-Y movement of the fine stage is accomplished through the use of a dual axis positioning system utilizing linear motion motors of high precision such as those available under the name Inchworm from Burleigh Instruments, Inc. of Fishers, N.Y. These motors utilize compact piezoelectric ceramic actuators to achieve ultra-high resolution linear motion positioning.
[0021] The motors 204 and 206 are secured to the coarse stage 202 in any suitable manner. A bracket 205 is secured to the Y motor 206 and suspends therefrom. A linear motion motor 208 is mounted on the bracket 205 and is operable to provide the Z axis movement of a pick up head assembly 214 mounted to housing 209 and, which in turn is carried by a bracket 207 which is mounted for movement to the motor 208 .
[0022] A pick up assembly 214 is carried by the manipulator device 110 and is operable for releasably retaining a workpiece 216 . Pick up head assembly 214 is a variable force vacuum pick up head assembly as are known in the art and is pivotally mounted on the manipulator device 110 . The force applied to the workpiece 216 by the pick up head assembly 214 engaging the part, is exerted by a voice coil motor 212 to prevent the over application of force to the workpiece 216 . Such a pick up head assembly 214 is well known in the art. The workpiece 216 is releasably retained in the pick up head assembly 214 by the application of vacuum to the part and is released from attachment to the pick up device by the release of the vacuum.
[0023] θdirection movement of the pick up head assembly 214 and hence a work piece 216 coupled to a gripper portion 215 of the pick up head assembly 214 is accomplished by a servo motor (not seen in FIG. 2) which connects to a housing 209 via a toothed driving belt 218 (sometimes referred to as a gearbelt or a timing belt) that engages a pulley 303 on the servo motor 302 and pulley 305 mounted on the housing 209 . The θ direction rotation is in the X-Y plane, generally parallel to the top surface of the top portion 102 . Housing 209 is rotatably mounted on a protective shroud 310 via one or more high precision ball bearings 220 . The housing 209 is movable in the Z direction via the Z-axis motor as described above. A machine vision system is provided and includes camera 210 mounted on the manipulator device 110 in the housing 209 for movement in at least the X and Y directions. The position of the camera 210 can be adjusted relative to the opening 224 through which the camera 210 views the workpiece 216 for proper focus of the camera on the part and portions of the processing station 114 , pickup station 116 , and assembly station 112 . Alternatively, the pick up head assembly 214 can be moved out of the field of view of camera 210 for viewing just the processing station 114 , pick up station 116 and assembly station 112 .
[0024] The camera 210 can be any suitable machine vision camera, e.g., a video camera, that has the appropriate focal length, field view, correct working distance and depth of field for viewing the workpiece 216 and portions of the processing stations 114 and/or other components. In operation, the camera 210 simultaneously views the workpiece 216 and some element (including a secondary component or part to make an assembly with) at a processing station 114 to provide information to the computer/controller 150 . The provided information is analyzed (processed) by the computer/controller 150 which in turn provides control signals to control operation of the manipulator device 110 and hence movement of the workpiece 216 relative to some predetermined point or location at the processing station for processing of the workpiece. The signals generated by the computer/controller 150 are sent to the various elements of the manipulator device 110 for controlling movement of the coarse stage 202 and X motor 204 , Y-motor 206 and Z-axis motor 208 .
[0025] The invention will be better understood by a description of the operation thereof. A workpiece 216 is located at the pick-up station 116 . The manipulator device 110 moves the gripper 215 to a location for picking up the workpiece 216 . In the particular form of invention illustrated, vacuum is applied through a vacuum tube 213 to the workpiece 216 that then releasably retains the workpiece 216 on the gripper 215 . The amount of force applied to the workpiece 216 is monitored by the voice coil motor 212 to insure adequate retention while reducing the risk of damage to the part. The computer/controller 150 is programmed with instructions for movement of the workpiece 216 to the locations at the various subsequent processing stations, for example the stations 114 . Coarse (low precision or low resolution) movement of the workpiece 216 is accomplished by the coarse stage 202 of the manipulator under control of the computer/controller 150 . When adjacent to a processing station, the camera 210 is operative to simultaneously view both the workpiece 216 and at least a portion of the processing station 114 such as a glue nozzle to determine the relative position between the workpiece 216 and the processing station 114 . Fiducial points can be provided both on the workpiece 216 and/or secondary part at the processing station for precisely locating the relative position of the workpiece 216 and the processing station 114 . The controller then determines the direction and magnitude of movement required for the workpiece 216 to position it accurately at the processing station 114 . After the part is close to the final position, signals are then sent to the fine stage of the manipulator device 110 for movement of the workpiece 216 to the appropriate position relative to the processing station. X, Y, Z and θ movements may be required to appropriately position the workpiece 216 for one or more operations. A fiber optic light source 308 is provided to camera 210 to provide illumination within the field of vision of camera 210 .
[0026] Preferably the vision system is operable to continuously monitor movement of the workpiece 216 relative to the processing station 114 to ensure proper final location of the workpiece 216 . However, it is to be understood that when the workpiece 216 is close to the desired location, the last portion of the movement of the workpiece 216 need not be continuously monitored by the camera 210 . However, it has been found desirable to continuously monitor the movement of the part 210 relative to the processing station 114 until the precise relative position has been attained. Continuous monitoring may include some interval breaks in the monitoring during movement to the final position and still provide adequate location precision or the continuous monitoring may have no breaks. The above described movement process is also applicable to moving the workpiece 216 relative to a secondary part positioned for such things as forming an assembly.
[0027] An example of an operation that can be performed at the first processing station 20 is the application of one or more spots of adhesive to the part. In this case, the workpiece 216 would be located relative to the adhesive dispensing nozzle at one or more positions on the workpiece for the application of adhesive thereto at predetermined locations on a downwardly facing surface.
[0028] An example of a processing step that could be conducted, e.g., at the assembly station 114 , is the application of a secondary part or subcomponent, such as an electronic component, to the workpiece 216 by moving the workpiece 216 into engagement with the subcomponent for the adhesive securement of the two together.
[0029] [0029]FIG. 5 is a view pick up head assembly 214 . Pick up head assembly 214 includes a gripper portion 215 , which is operable to hold a workpiece via the application of a vacuum via a vacuum line 213 . Voice coil motor 212 applies a force on a workpiece proportional to the current applied to the voice coil motor. A sensor 402 detects very small rotational motion in pick head assembly, which is indicative of the gripper portion 215 contacting a workpiece. A stop 404 limits how far the pick up head assembly can rotate about pivot point 400 .
[0030] In operation, pick head assembly 214 is mounted to the rest of manipulator device 110 . Once it is over a workpiece, it will be lowered in the z-axis. Once the sensor 402 will indicate when the gripper portion contacts the workpiece. Then, if the workpiece is to be moved a vacuum is applied to vacuum line 213 to hold the workpiece. The amount of force exerted on the workpiece is determined by the current applied to the voice coil motor,
[0031] In view of the above, it will be seen that several objects of the invention are achieved and other advantageous results attained.
[0032] As various changes could be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
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A manipulator head for use in a precision assembly unit is disclosed. The manipulator head includes a coarse X-Y stage or movement along the top surface in the X and Y-axis, a fine X stage for fine X-axis movements, a fine Y stage for fine Y-axis movements, and a Z stage for movement in the Z direction. Additionally, a th stage carried by the manipulator is included. A video camera is coupled to the fine X stage and fine Y stage. The video camera has an optical axis directed substantially in the Z direction. The video camera's field of view encompassing at least a portion of a part secured by a gripper attached to the manipulator head when the part is in position for processing at the workstation.
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BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a device for making a bias tape which is mainly used for finishing or decorating clothing or the like. Such a device is referred to as a bias tape maker.
[0003] 2. Description of the Related Art
[0004] A bias tape is a narrow strip of cloth having a pair of longitudinal margins folded toward each other. Such a bias tape may be made by cutting a cloth diagonally across the weave to provide an elongate bias cloth, and then folding the longitudinal margins of the bias cloth toward each other. The bias tape thus provided has a good stretch and a high flexibility so that it is suited for use in finishing or decorating clothes or the like.
[0005] [0005]FIG. 10 illustrates atypical prior art bias tape maker. The bias tape maker 100 comprises an outer shell 102 and an inner core 103 for insertion into the outer shell 102 . The outer shell 102 , which may be made by bending a thin metal plate, has a generally tubular configuration which is progressively flattened toward its front end. The outer shell 102 includes a pair of roof margins 21 .
[0006] The inner core 103 , which may be made of a resin, tapers from its rear end toward its front end. The inner core 103 is formed with a generally triangular platform 131 which is laterally formed with a pair of longitudinal engaging grooves 32 .
[0007] As shown in FIG. 11, by engaging the roof margins 21 of the outer shell 102 with the engaging grooves 3 , the outer shell 102 is assembled with the inner core 103 . In the bias tape maker 100 thus assembled, a tape folding portion (not specifically shown) is defined between the inner core 102 and the outer shell 103 .
[0008] In use, a bias cloth 11 is introduced into the bias tape maker 100 from the rear end thereof. In advancing through the non-illustrated tape folding portion toward the front end of the tape maker 100 , the bias cloth 11 is continuously formed into a bias tape 1 provided with a pair of longitudinally extending folds 11 a . The bias tape 1 thus formed is pulled out from the front end of the bias tape maker 100 . The folds 11 a may then be fixed or set by ironing for example.
[0009] The bias tape thus provided may be fixed on clothing for example in the following manner. First, the bias tape is bent into a desired configuration and ironed for example for setting the configuration. Then, the bias tape is disposed on clothing and provisionally fixed thereon with pins or needles for example. Then, the bias tape is sewed onto the clothing. Thus, the fixing process is rather complicated and troublesome.
[0010] For easier fixation, a bias tape is known which is provided with an auxiliary adhesive tape. Such a bias tape is hereinafter referred to as adhesive bias tape an example of which is shown in FIG. 9. As shown in the figure, the adhesive bias tape 1 comprises a bias cloth 11 (hereafter referred to as “main tape”) including a pair of folds 11 a , and an auxiliary tape 12 attached on the main tape 11 . The auxiliary tape 12 , which is in the form of a narrow strip, comprises an adhesive layer 12 a which becomes tacky or sticky by heating, and a releasable substrate 12 b , such as a silicone sheet, for releasably carrying the adhesive layer 12 a.
[0011] For fixing the adhesive bias tape 1 onto clothing for example, the user removes the releasable substrate 12 b from the adhesive layer 12 a . Then, while bending the bias tape 1 into a desired configuration, the user provisionally fixes the bias tape 1 onto the clothing by ironing, and then sews it onto the clothing. Thus, the adhesive bias tape 1 can be fixed more easily than an ordinary (non-adhesive) bias tape.
[0012] Such an adhesive bias tape 1 may be formed by disposing an auxiliary tape 12 on the folds 11 a of a main tape 11 and then bonding the auxiliary tape 12 to the bias tape 1 by thermally melting the adhesive layer 41 by ironing for example.
[0013] However, such fabrication of an adhesive bias tape has the following problems. Firstly, since both the auxiliary tape 12 and the main tape 11 are in the form of a narrow strip, it is difficult to accurately position the auxiliary tape relative to the main tape. Secondly, the ironing need be performed twice, i.e., for setting the folds 11 a of the main tape 11 and for bonding the auxiliary tape 12 to the main tape 11 , which is troublesome.
SUMMARY OF THE INVENTION
[0014] It is therefore an object of the present invention to provide a bias tape maker which facilitates the formation of an adhesive bias tape.
[0015] According to a first aspect of the present invention, a bias tape maker comprises an outer shell including a tape entering port and a tape exiting port for introduction and exit of a main tape, respectively, and an inner core fitted in the outer shell for defining a main tape passage between the outer shell and the inner core. The main tape passage includes a tape folding portion for folding longitudinal margins of the main tape toward each other. The outer shell is provided with an auxiliary tape entry window adjacent the tape exiting port for introducing an auxiliary tape into the tape folding portion of the main tape passage.
[0016] Preferably, the auxiliary tape entry window has a width equal to or slightly larger than that of the auxiliary tape.
[0017] In a preferred embodiment, the outer shell comprises a pair of roof margins which extend toward each other into abutment adjacent the tape exiting port, and the auxiliary tape entry window is defined by a cutout formed in the pair of roof margins adjacent the tape exiting port.
[0018] Preferably, the auxiliary tape guide groove may be aligned with the auxiliary tape entry window longitudinally of the auxiliary tape.
[0019] Preferably, the auxiliary tape guide groove has a width generally equal to that of the auxiliary tape.
[0020] Preferably, the upper portion of the inner core has a front end partially extending into the auxiliary tape entry window.
[0021] Preferably, the upper portion of the inner core has a rear end formed with a handle which in turn is formed with an auxiliary tape guide hole for introducing the auxiliary tape toward the auxiliary tape guide groove.
[0022] Preferably, the auxiliary tape guide hole may be aligned with the auxiliary tape guide groove and the auxiliary tape entry window longitudinally of the auxiliary tape.
[0023] Preferably, the handle is inclined backwardly upward, the auxiliary tape guide hole being provided at a base end of the handle.
[0024] According to a second aspect of the present invention, a bias tape maker comprises an outer shell including a tape entering port and a tape exiting port for introduction and exit of a main tape, respectively, and an inner core fitted in the outer shell for defining a main tape passage between the outer shell and the inner core. The main tape passage includes a tape folding portion for folding longitudinal margins of the main tape toward each other. The inner core includes an upper portion formed with an auxiliary tape guide groove for guiding an auxiliary tape toward the tape exiting port.
[0025] Other features and advantages of the present invention will become clearer from the detailed description given below with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] [0026]FIG. 1 is a perspective view showing a bias tape maker, together with a bias tape, according to an embodiment of the present invention.
[0027] [0027]FIG. 2 is a plan view showing an outer shell of the bias tape maker shown in FIG. 1.
[0028] [0028]FIG. 3 is a side view, partially in section, showing the inner structure of the bias tape maker shown in FIG. 1.
[0029] [0029]FIG. 4 is a sectional view taken along lines IV-IV in FIG. 1.
[0030] [0030]FIG. 5 is a sectional view taken along lines V-V in FIG. 1.
[0031] [0031]FIG. 6 is a sectional view taken along lines VI-VI in FIG. 1.
[0032] [0032]FIG. 7 is a perspective view showing an inner core of the bias tape maker shown in FIG. 1.
[0033] [0033]FIG. 8 is a perspective view showing the bias tape maker of FIG. 1 without a bias tape.
[0034] [0034]FIG. 9 is a schematic perspective view showing an adhesive bias tape which is made by the bias tape maker of the present invention.
[0035] [0035]FIG. 10 is an exploded perspective view showing a prior art bias tape maker.
[0036] [0036]FIG. 11 is a schematic perspective view showing the same prior art bias tape maker.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] A preferred embodiment of the present invention will be described below in detail with reference to FIGS. 1 through 8 of the accompanying drawings.
[0038] Referring to FIG. 1, there is illustrated a bias tape maker A for making an adhesive bias tape 1 which includes a main tape 11 of a cloth or fabric and an auxiliary adhesive tape 12 (see also FIG. 9). After biasing with the bias tape maker A, the main tape 11 has a pair of longitudinal edges 11 a folded toward each other and joined together by the auxiliary tape 12 to form a closed loop which is flattened. The auxiliary tape 12 includes an adhesive layer 12 a carried on a releasable substrate 12 b of a silicone paper for example. The adhesive layer 12 a has such a nature that it becomes tacky only when heated.
[0039] The bias tape maker A comprises an outer shell 2 , and an inner core 3 for fitting into the outer shell 2 . The outer shell 2 may be made by cutting or punching a thin metal plate into a predetermined configuration and bending the plate. The inner core 3 may be molded of a resin.
[0040] As shown in FIGS. 2, 3 and 8 , the outer shell 2 includes a bottom wall 22 , a pair of sidewalls 23 rising from the bottom wall 22 , and a pair of roof margins 21 bent at the respective side walls 23 toward each other. The outer shell 2 tapers from its rear end to its front end.
[0041] The roof margins 21 include mutually abutting portions 21 a near the front end of the outer shell 2 (see particularly FIG. 8). Thus, the outer shell 2 provides a tape exiting port 24 at its front end. Each of the roof margins 21 includes an engaging portion 21 b for engagement with a corresponding engaging groove 32 of the inner core 3 when the inner core 3 is assembled with the outer shell 2 (see particularly FIGS. 2 - 4 ). The engaging portion 21 b is formed with a generally triangular engaging notch 21 c for engagement with a corresponding engaging projection (not shown) formed in the engaging groove 32 , thereby preventing the inner core 3 from being unexpectedly detached from the outer shell 2 .
[0042] Each of the roof margins 21 is further formed with a cutout 21 d (FIG. 2) which defines an auxiliary tape entry window 5 adjacent the tape exiting port 24 together with the counterpart cutout 21 d of the other roof margin 21 . The window 5 has a width W w which is equal to or slightly larger than the width of the auxiliary tape 12 . As shown in FIG. 8, when the outer shell 2 and the inner core 3 are assembled, a front end portion 3 a of the inner core 3 advances partially into the window 5 . However, the window 5 is still kept open for introducing the auxiliary tape 12 into the outer shell 2 adjacent the tape exiting port 24 . Alternatively, the window 5 may be defined solely by the outer shell 2 as spaced away from the front end 3 a of the inner core 3 .
[0043] As shown in FIG. 2, the bottom wall 22 of the outer shell 2 is formed with a tape advancing slot 29 provided between the front end and the rear end of the outer shell 2 . The function of the tape advancing slot 29 will be described later.
[0044] As shown in FIGS. 3 and 7, the inner core 3 tapers from its rear end toward its front end. Each of the longitudinal engaging grooves 32 is formed on a respective side surface of the inner core 3 and extends forwardly downward for engagement with the corresponding roof margin 21 of the outer shell 2 , as previously described. The inner core 3 mainly comprises two integral portions, i.e., an upper portion located above the engaging grooves 32 and a lower portion located below the engaging grooves 32 . When the inner core 3 is assembled with the outer shell 2 , the upper portion is exposed, whereas the lower portion is enclosed in the outer shell 2 .
[0045] As shown in FIG. 1, the inner core 3 is provided, on its top, with an auxiliary tape guide groove 31 extending longitudinally of the bias tape maker A for guiding the auxiliary tape 12 toward the auxiliary tape entry window 5 . The guide groove 31 generally corresponds in width to the auxiliary tape 12 . As shown in FIG. 4, the guide groove 31 is defined by a bottom surface 31 b and a pair of side walls 31 a . The bottom surface 31 b has a width WT which is equal to or slightly larger than that of the auxiliary tape 12 . Each side wall 31 a has a height which is larger than the thickness of the auxiliary tape 12 . Thus, it is possible to smoothly advance the auxiliary tape 12 along the guide groove 31 .
[0046] As shown in FIGS. 3 and 7, the inner core 3 is formed, at its rear end of the upper portion, with a handle 6 which is inclined backwardly upward. The handle 6 is formed with an auxiliary tape guide hole 61 (FIG. 7) for guiding the auxiliary tape 12 . The guide hole 61 has a width which is equal to or slightly larger than that of the auxiliary tape 12 for allowing insertion of the auxiliary tape 12 . As shown in FIG. 8, the guide hole 61 , the guide groove 31 and the window 5 are aligned longitudinally of the bias tape maker A.
[0047] As shown in FIG. 7, the lower portion of the inner core 3 below the engaging grooves 32 comprises a larger width portion 34 , a smaller width portion 35 , and a generally triangular portion 36 . The larger width portions 34 and the triangular portion 36 are continuous with each other and provides a flat upper surface 36 a on each side of the auxiliary tape guide grove 31 . As shown in FIG. 3, each of the engaging grooves 32 is defined between this flat surface 36 a and the corresponding side wall 31 a of the guide groove 31 . The smaller width portion 35 is located below the larger width portion 34 and the triangular portion 36 . The upper surface of the smaller width portion 35 is divided by the triangular portion 36 into two triangular surfaces 35 a.
[0048] As shown in FIGS. 4 and 5, when the outer shell 2 and the inner core 3 are assembled, a tape inserting portion R 1 and a tape folding portion R 2 are formed between the outer shell 2 and the inner core 3 . The tape inserting portion R 1 extends from the rear end of the outer shell 2 for inserting the main tape 11 , whereas the tape folding portion R 2 extends from the tape inserting portion R 1 to the tape exiting port 24 for folding the longitudinal margins 11 a of the main tape 11 toward each other. Specifically, in passing through the tape inserting portion R 1 , the main tape 11 is bent to have a U-shaped cross section with the longitudinal margins 11 a raised. On the other hand, in passing through the tape folding portion R 2 , the longitudinal margins 11 a of the main tape 11 are folded toward each other, thereby turning into a pair of folds 11 a.
[0049] For making an adhesive bias tape 1 , the above-described bias tape maker A may be used in the following manner.
[0050] First, a main tape 11 is introduced into the tape inserting portion R 1 from the rear end of the bias tape maker A. Then, the main tape 11 is advanced until the leading end of the main tape 11 is exposed at the tape advancing slot 29 . In this state, the user can advance the main tape 11 by making access to the main tape 11 via the tape advancing slot 29 directly with a finger or a short engaging article (not shown). In subsequently passing through the tape folding portion R 2 , the longitudinal edges 11 a of the main tape 11 are folded toward each other, as described before.
[0051] Finally, the main tape 11 is pulled out from the tape exiting port 24 by the user nipping the leading end of the tape 11 (see FIG. 1).
[0052] Then, as shown in FIG. 1, an auxiliary tape 12 is introduced from the rear side of the handle 6 into the guide hole 61 and is advanced along the guide groove 31 . Then, the leading end of the auxiliary tape 12 is inserted through the window 5 into the bias tape maker A. The auxiliary tape 12 is pushed until its leading end projects out from the tape exiting port 24 . As shown in FIG. 6, upon passing in front of the inner core 3 , the auxiliary tape 12 lies on the folded longitudinal margins 11 a of the main tape 11 .
[0053] While pulling out the auxiliary tape 12 together with the main tape 11 from the tape exiting port 24 , ironing may be performed from above the auxiliary tape 24 . As a result, the folded longitudinal margins 11 a of the main tape 11 are fixed or set, and at the same time, the auxiliary tape 12 is bonded to the folded longitudinal margins 11 a of the main tape 11 , thus providing an adhesive bias tape 1 .
[0054] With the bias tape maker A according to the present invention, it is possible to pull out the auxiliary tape 12 together with the main tape 11 from the tape exiting port 24 with the auxiliary tape 12 accurately positioned on the folded main tape 11 . Therefore, unlike the prior art bias tape maker, the user need not perform a separate step of accurately positioning the auxiliary tape relative to the main tape. Moreover, the setting of the folds 11 s and the bonding of the auxiliary tape 12 to the main tape 11 can be performed simultaneously by a single ironing step. Therefore, it is possible to efficiently make an adhesive bias tape 1 .
[0055] Moreover, since the window 5 , the guide groove 31 and the guide hole 61 are aligned longitudinally of the bias tape maker A, the auxiliary tape 12 can be reliably and smoothly introduced into the window 5 and pulled out from the tape exiting port 24 without lateral rubbing. As a result, it is possible to prevent the auxiliary tape 12 from breaking due to friction.
[0056] Further, by holding the handle 6 of the inner core 3 , the user can press the bottom wall 22 of the outer shell 2 against the workbench, thereby preventing the adhesive bias tape 1 from being unexpectedly lifted from the workbench during ironing. Therefore, the ironing of the adhesive bias tape 1 can be performed efficiently. Since the guide hole 61 is formed at the base end of the handle 6 , the user can hold the handle 6 without contacting the auxiliary tape 12 , thereby preventing the auxiliary tape 12 from being undesirably deformed. Thus, the user can perform efficient ironing without the need for taking care not to deform the auxiliary tape 12 .
[0057] The preferred embodiment of the present invention being thus described, it is obvious that the same may be varied in many ways. For instance, the main tape 11 may be made of any material other than cloth or fabric. The bottom of the smaller width portion 35 may be formed with downwardly directed grooves to reduce the contact area between the main tape 11 and the smaller width portion 35 for enabling smooth movement of the main tape 11 . Such variations are not regarded as a departure from the spirit and scope of the present invention, and all such variations as would be obvious to those skilled in the art are intended to be included in the scope of the appended claims.
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A bias tape maker includes an outer shell including a tape entering port and a tape exiting port for introduction and exit of a main tape, respectively, and an inner core fitted in the outer shell for defining a main tape passage between the outer shell and the inner core. The main tape passage has a tape folding portion for folding longitudinal margins of the main tape toward each other. The outer shell is provided with an auxiliary tape entry window adjacent the tape exiting port for introducing an auxiliary tape into the tape folding portion of the main tape passage.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject invention resides in methods and apparatus for centering advancing tapes and has utility in tape transports employed in magnetic tape recording equipment and in other applications where a tape or tape-like web is to be centered onto a desired tape or web advance path.
2. Description of the Prior Art
The most frequently employed method for centering an advancing tape onto a desired path resides in the provision of members defining one or two guide edges. In practice, this has imposed considerable wear and tear on the tape and has rendered the system sensitive to tape width tolerances and snakiness. In the case of information recording tape, the mentioned prior-art solution has also introduced scrape flutter into the information signal.
It had, therefore, been proposed that fluid bearings be employed for centering purposes. In this connection reference is made to the U.S. Pat. Nos. 2,848,820, 2,908,495, 2,954,911, 2,967,674, 3,032,246, 3,087,664, and 3,281,040.
In reviewing the proposals contained in these patents, it will be noted that some of them provide only a single fluid bearing at each guide, which impairs an efficient centering action. Some prior art has attempted to counter this by generating trough-like air jets. This, however, bent the tape edges away from the bearing and maintained the tape edges bent during the operation of the equipment, thereby disturbing a desired generally flat tape configuration.
Another proposal developed a transverse pressure gradient in a single fluid bearing chamber. This required the tape edge to slide along a guide surface, which made tape centering sensitive to the snakiness of commercial grade tapes. Another proposal, which also employed only a single bearing chamber, required the provision of upright fixed flanges which rendered the bearing sensitive to tape width tolerances and snakiness and which tended to introduce scrape flutter in response to tape contact of either of the flanges.
The above mentioned deficiencies of prior-art proposals and systems also resulted in a loss of data in the tape margin which was engaged by a guide surface.
SUMMARY OF THE INVENTION
It is a general object of this invention to overcome the above mentioned disadvantages.
It is a more specific object of the invention to provide improved tape transport equipment and techniques.
It is a similar object of this invention to provide improved methods and apparatus for centering a tape onto a desired tape advance path without the use of any guide edges which could be touched by the tape with resulting wear and tear, loss of data in the tape margin and incidental scrape flutter.
It is a related object of this invention to provide improved methods and apparatus for centering a tape onto a desired tape advance path in such a manner that lateral tape movements due to snakiness and similar causes occur always at the same tape location in any tape rerun with the same kind of equipment.
Other objects will become apparent in the further course of this disclosure.
From a first aspect thereof, the invention resides in a method of centering a tape having two edge regions onto a desired tape advance path, comprising in combination the steps of providing a pair of separate cavities at said tape advance path, providing each of said cavities with a lateral fluid flow orifice extending beyond the desired tape advance path, providing each of said cavities with a fluid bearing chamber having a larger effective cross-section than said lateral fluid flow orifice, covering both of said fluid bearing chambers with said tape, establishing independent fluid pressures in said cavitites, moving said tape along said desired tape advance path, maintaining both of said fluid bearing chambers covered by said tape during movement of said tape, subjecting said tape to a first fluid pressure with one of said fluid flow orifices at one of said edge regions, subjecting said tape to a second fluid pressure with the other of said fluid flow orifices at the other of said edge regions, increasing said first fluid pressure in response to movement of said one edge region away from said desired tape advance path in one direction by varying the effective cross-section of said one orifice with said one edge region, returning said tape onto said desired tape advance path with said increased first fluid pressure, increasing said second fluid pressure in response to movement of said other edge region away from said desired tape advance path in a direction opposite to said one direction by varying the effective cross-section of said other orifice with said other edge region, and returning said tape onto said desired tape advance path with said increased second fluid pressure.
From a second aspect thereof, the invention resides in a method of centering a tape having two edge regions onto a desired tape advance path, comprising in combination the steps of providing a first fluid flow orifice on a first side of said desired tape advance path providing a first fluid bearing chamber within said desired tape advance path having a larger effective cross-section than said first fluid flow orifice, providing a second fluid flow orifice on an opposite second side of said desired tape advance path providing a second fluid bearing chamber within said desired tape advance path having a larger effective cross-section than said second fluid flow orifice, moving said tape along said desired tape advance path, establishing a fluid pressure in said first fluid bearing chamber and flowing fluid through said first orifice, establishing a fluid pressure in said second fluid bearing chamber and flowing fluid through said second orifice, maintaining said first and second fluid bearing chambers covered by said tape during movement of said tape, reducing the effective cross-section of said first fluid flow orifice with one of said edge regions of the tape when said one edge region moves away from said desired tape advance path in one direction and providing fluid pressure through said reduction in effective cross-section of said fisrt fluid flow orifice for returning said tape onto said desired tape advance path, and reducing the effective cross-section of said second fluid flow orifice with the other of said edge regions of the tape when said other edge region moves away from said desired tape advance path in a direction opposite to said one direction and providing fluid pressure through said reduction in effective cross-section of said second fluid flow orifice for returning said tape onto said desired tape advance path.
From a third aspect thereof, the invention resides in apparatus for centering an advancing tape having two tape edge regions onto a desired tape advance path having two path edge regions corresponding to said tape edge regions, comprising in combination first means for subjecting said tape to a first fluid pressure at one of said tape edge regions, said first means include means defining a first cavity within a first side of said desired tape advance path and forming a first fluid bearing for said tape, second means distinct from said first means for subjecting said tape to a second fluid pressure at the other of said tape edge regions, said second means include means defining a second cavity within a second side of said desired tape advance path and forming a second a second fluid bearing for said tape, and means for separating said second cavity from said first catvity, third means connected to said first and second means for individually supplying pressurized fluid to said first and second means, fourth means connected to said first means for increasing said first fluid pressure in response to movement of said one tape edge region away from said desired tape advance path in one direction and for returning said tape to said desired tape advance path with said increased first fluid pressure, said fourth means including means defining an extension of said first cavity beyond one of said path edge regions to form a first fluid flow orifice having a variable effective cross-section relative to said one tape edge, and fifth means connected to said second means for increasing said second fluid pressure in response to movement of said other tape edge region away from said desired tape advance path in a direction opposite to said one direction and for returning said tape to said desired tape advance path with said increased second fluid pressure, said fifth means including means defining an extension of said first cavity beyond the other of said path edge regions to form a second fluid flow orifice having a variable effective cross-section relative to said other tape edge.
From yet a further aspect thereof, the invention resides in apparatus for centering an advancing tape having two tape edge regions onto a desired tape advance path having two path edge regions corresponding to said tape edge regions, comprising in combination a first fluid bearing for said tape extending from within one side of said desired tape advance path into a first area beyond one of said path edge regions, a second fluid bearing for said tape extending from within another side of said desired tape advance path into a second area beyond the other of said path edge regions, means for separating said first and second fluid bearings from each other, and means connected to said first and second fluid bearings for individually supplying pressurized fluid to said fluid bearings, said fluid supplying means including a source of pressurized fluid, first means for conducting pressurized fluid from said source to said first fluid bearing, and second means, distinct from said first means, for conducting pressurized fluid from said source to said second fluid bearing, said first conducting means including first means for regulating the flow of fluid from said source to said first fluid bearing, said second conducting means including second means, independent of said first regulating means, for regulating the flow of fluid from said source to said second fluid bearing, said first fluid bearing having a larger effective cross-section within said desired tape advance path than in said first area beyond said one path edge region, and said second fluid bearing having a larger effective cross-section within said desired tape advance path than in said second area beyond said other path edge region.
The expression "fluid" as herein employed is intended to refer broadly to gases, vapors and liquids. For practical reasons and in keeping with the most preferred embodiment presently contemplated by applicant, the further disclosure herein will be styled in terms of pressurized air being employed as the mentioned fluid. However, no limitation to air as the requisite fluid is thereby intended.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention and its objects will become more readily apparent from the following detailed description of preferred embodiments thereof, illustrated by way of example in the accompanying drawings, in which like reference numerals designate like or functionally equivalent parts, and in which:
FIG. 1 is a plan view of a tape transport assembly which incorporates tape centering devices according to a preferred embodiment of the subject invention;
FIG. 2 is a diagram showing the use of a tension transducer to control a reel drive motor in combination with the tape centering action according to the subject invention;
FIG. 3 is an elevation, on an enlarged scale, of a tape centering device in accordance with a preferred embodiment of the subject invention, as seen in the direction of arrow 3 in FIG. 1; and
FIG. 4 is a section, with parts broken away, taken on the line 4 -- 4 in FIG. 3.
DESCRIPTION OF PREFERRED EMBODIMENTS
By way of background, the tape transport assembly shown in FIGS. 1 and 2 will first be described before reference is made to the specific construction of the tape centering devices according to the subject invention.
In particular, the tape transport shown in FIG. 1 includes a supply reel 11 and a take-up reel 12 which are mounted by suitable hubs 13 and 14, respectively, to drive shafts of corresponding drive motors, one of which is shown at 15 in FIG. 2 with a drive shaft 16 for the hub 13 of reel 11. A corresponding drive motor (not shown) is employed for the reel 12.
The tape supply and take-up reels 11 and 12 are mounted above a transport face or base plate 17.
A magnetic recording tape 18 extends from the supply reel 11 to the take-up reel 12 along a predetermined tape path.
A head assembly 19, which may include recording, playback and erasing heads, is located in the tape path and is connected to equipment (not shown) for recording, playing back and erasing information onto and from the magnetic tape 18.
The tape 18 proceeds from the supply reel along the mentioned tape path via a tape guide post 20, a tape tensioning device or transducer 28, tape guide posts or idler rollers 21 and 22, a tape drive capstan 23, the head assembly 19, a further tape drive capstan 24, tape guide posts or idler rollers 25 and 26, a further tape tensioning device or transducer 29, and a tape guide post 27.
The capstans 23 and 24 are driven by conventional motors or drives 15 and 16 whereby the magnetic tape 18 may be driven past the head assembly in either direction.
The tape transport 10 shown in FIG. 1, as well as the tape tension devices or transducers 28 and 29 are disclosed in U.S. Pat. No. 3,787,690, by Joseph J. Neff, issued Jan. 22, 1974, to the present assignee, and herewith incorporated by reference herein. As disclosed in that incorporated patent, each tape tension device or transducer functions within the transport 10 to maintain the tape 18 at the adjacent portion of the tape path within relatively narrow, predetermined limits of tape tension, to sense the instantaneous value of tape tension, and to generate a control signal which is indicative of sensed tape tension, and also to provide a buffer storage capacity for tape 18 in those instances where the adjacent tape reel 11 or 12 tends to overrun or underrun the adjacent tape drive capstan.
Each of the tape tensioning devices or transducers 28 and 29 has a pair of tape guide rollers 47 mounted on a circular carrier plate 46 which is connected to a rotary signal generator 30. The tape 18 engages each pair of tape guide rollers 47 to form a variable tape loop. As more fully disclosed in the incorporated patent, the signal generator 30 produces a signal which varies in accordance with variations of the tape loop at the particular tensioning device or transducer.
This signal is applied to a control 88 which, in turn, varies the energization of the corresponding tape drive, such as the tape drive 15 shown in FIG. 2, so that overrunning or underrunning of the particular tape reel is avoided.
In accordance with a preferred embodiment of the subject invention, the tape guide posts so far mentioned may be of the type illustrated in FIGS. 3 and 4. This will now be explained relative to the tape guide post 20 which serves as a turnabout for the tape proceeding from or to the variable diameter tape roll on the adjacent reel into and from the tape path leading to and from the head assembly 19.
An important object of the illustrated preferred embodiment of the invention is to center the advancing tape 18 onto a desired tape advance path, the opposite edge regions of which are indicated in FIG. 3 by dotted lines 51 and 52. In accordance with the subject invention, this is to be accomplished without the use of any guide edges or surfaces that would be contacted by edge portions of the tape.
To this end, the tape guide post 20 includes a pair of first and second fluid bearings 54 and 55 which, as best seen in FIG. 4, maintain the tape 18 riding on a fluid film ahving a very low coefficient of friction. The guide post 20 comprises a wall portion 57 for separating the first and second fluid bearings from each other.
The first fluid bearing 54 extends from within one side of the desired tape advance path into a first area beyond the path edge region 51. Similarly, the second fluid bearing 55 extends from within another side of the desired tape advance path into a second area beyond the other path edge region 52.
In the illustrated preferred embodiment, the fluid bearings 54 and 55 are located on opposite sides of a longitudinal axis of symmetry 59 in the desired tape advance path between the path edge regions 51 and 52. Moreover, the first fluid bearing 54 includes a first cavity 61 within the mentioned first side of the desired tape advance path. Similarly, the second fluid bearing includes a second cavity 62 within a second side of the desired tape advance path.
A pair of separate and distinct conduits 64 and 65 extend from a common source of pressurized fluid 66, such as an air compressor, to the cavities 61 and 62, respectively, to supply pressurized fluid to the fluid bearings 54 and 55. Individually and separately adjustable valves or other regulating devices 68 and 69 are located in the conduits 64 and 65, respectively, in order to enable the individual metering of fluid supplied to each of the bearings and the individual adjustment of fluid pressure provided thereby.
The cavity 61 of the first fluid bearing 54 has an extension 71 beyond the desired path edge 51. Similarly, the cavity 62 of the fluid bearing 55 has an extension 72 beyond the desired path edge 52.
In this manner, the cavity extension 71 forms a first fluid flow orifice 74 having a variable effective cross-section relative to the adjacent tape edge 75. Similarly, the cavity extension 72 forms a second fluid flow orifice 77 having a variable effective cross-section relative to the other tape edge 78.
During the operation of the illustrated equipment, the tape 18 moves along the desired path delimited by the path edge portions 51 and 52. The two fluid bearings 54 and 55 center the tape 18 onto the desired tape path. If the tape 18 moves laterally so that the tape edge region 75 moves away from the desired tape advance path onto first fluid orifice 74, as indicated by the dotted lines 75' and 78' in FIG. 3, the effective cross-section of the orifice 74 is automatically reduced by the tape edge region 75. In consequence, the first fluid pressure in the fluid bearing 54 is automatically increased in response to movement of the tape edge region 75 away from the desired tape advance path delimited by the desired tape advance path edges 51 and 52.
Conversely, the effective cross-section of the orifice 77 is automatically increased when the tape edge region 78 moves further onto the desired tape advance path or, in other words, moves toward the symmetry axis 59, as indicated by the dotted line 78'.
Accordingly, the fluid pressure in the second air bearing 55 is decreased when the laterally moving tape increases the first fluid pressure in the fluid bearing 54.
The increased fluid pressure in the first bearing 54 tends to lift the tape edge region 75 when the same has moved laterally as indicated at 75' in FIG. 3. Since the fluid film on which the tape 18 is riding by operation of the fluid bearings 54 and 55 has a very low coefficient of friction, the tape 18 will tend to slide down off the lifted position and towards the center position on the desired tape advance path. This will automatically center the tape onto the desired path.
Mutatis mutandis, the tape edge region 78 will reduce the effective cross-section of the orifice 72 when the tape 18 laterally moves so that the tape edge region 78 moves away from the desired tape advance path. Simultaneously, the effective cross-section of the orifice 71 will be simultaneously increased as the tape edge region 75 moves toward the axis 59. In consequence, the fluid pressure in the bearing 55 will increase as the fluid pressure in the bearing 54 is decreased by the laterally moving tape.
Accordingly, the increased fluid pressure in the bearing 55 will tend to lift the tape edge region 78 and the tape will slide down the low-friction fluid film and will automatically center itself onto the desired tape advance path.
It will thus be recognized that the subject invention automatically returns the tape 18 onto the desired tape advance path with the increased first and second fluid pressures. In considering the illustrated preferred embodiment, it will be noted that the first fluid bearing 54 has a larger effective cross-section within the desired tape advance path where the proper of the cavity 61 or fluid bearing chamber is located, than in the area beyond the path edge region 51 where the cavity extension in the form of the orifice 71 is located. Similarly, the fluid bearing 55 has a larger effective cross-section within the desired tape advance path where the proper of the cavity 62 is located, than in an area beyond the path edge region 52 where the cavity extension 72 in the form of the orifice 72 is situated. While these cavity proportions are not mandatory, they do have the advantage that the tape 18 is capable of riding on an adequate air film and of changing the bearing fluid pressures very rapidly in response to lateral deviations from the desired tape advance path.
While the invention has been illustrated in the drawings in terms of a tape guide post, it should be recognized that the subject invention may be employed in other implementations where an advancing tape or similar traveling web or strip is to be automatically centered.
The subject extensive disclosure will suggest or render apparent various modifications and variations within the spirit and scope of the subject invention to those skilled in the art.
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An advancing tape is subjected to a first fluid pressure at one of its edge regions, and to a second fluid pressure at the other of its edge regions. The first fluid pressure is increased in response to movement of the mentioned one edge region away from a desired tape advance path. The tape is then returned to that desired tape advance path with the aid of the increased first fluid pressure. The second fluid pressure is increased in response to movement of the other edge region away from the desired tape advance path. The tape is thereupon returned onto the desired tape advance path with the latter increased second fluid pressure.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a National Phase Application of International Application No. PCT/EP2007/060158, filed on Sep. 25, 2007, which claims the benefit of and priority to European patent application no. EP 06 121 267.6, filed on Sep. 26, 2006. The disclosures of the above applications are incorporated herein by reference in their entirety.
FIELD OF THE INVENTION
The invention relates to a method of producing a piston for internal combustion engines from two pre-fabricated parts which, having been pre-fabricated, are connected together to form the piston. As well as this, the invention also relates to a piston which is produced in a corresponding manner from two parts.
BACKGROUND
Pistons for internal combustion engines are usually produced by casting or forging processes. Production by casting has the advantage that it allows pistons of complex shape and low weight to be produced. However, what has to be accepted at the same time is that the production involves considerable cost and complication. This is particularly true when a steel material is to be used as the material for producing pistons able to withstand especially high stresses.
Depending on their size and intended purpose, forged steel pistons may both be of a one-piece form and may also be composed of two or more parts. In the case of multi-piece pistons assembled from two or more parts, the individual parts are usually connected together, by suitable joining processes, by friction, bonding, or positive fit in such a way that they will withstand the forces acting on them in practical use. What is suitable for this purpose is for example welding or screwing together of the separate parts of the piston.
An example of a multi-piece piston for an internal combustion engine is known from DE 102 44 513 A1. This piston has, on the one hand, a head part which is forged from steel and integrally formed in which are formed dishing for the combustion chamber, an annular wall and a cooling passage in the form of a groove. On the other hand the piston has a skirt part which carries the head part of the piston and in which are formed bosses to receive a piston pin which connects the piston to the connecting rod. To produce this piston, the head part and skirt part of the piston are pre-shaped by forging in separate operations and are then machined by stock-removing machining to finish them. The finish machining of the head part of the piston also includes in this case the stock-removing machining of the portions of wall adjoining the cooling passage, by means of which portions of wall a joint is then made to the skirt part of the piston by physical union by welding or brazing.
It is true that multi-piece construction of this kind allows the piston which is formed from the two parts to be made of a complex shape. However, apart from the problems relating to load-bearing capacity which arise from its multi-piece nature, the cost and complication its production involves are considerable.
Disadvantages of the production of one-piece pistons are the high weight of the blank for the piston, as a result of which processing and handling equipment of particularly large dimensions is required, and the expense involved in the mechanical post-processing which is inevitably required in present-day practice. Despite the advantages that one-piece pistons have, as far as their load-bearing capacity is concerned, the disadvantages mentioned mean that when production is conventional one-piece pistons can only be produced at increased production costs.
One possible way of connecting together, by forging, a piston formed from two previously manufactured parts is known from JP 03-267552 A. In this piece of prior art, a piston-skirt blank whose basic shape is that of a cylinder is produced by sintering a metal powder. A projection which is of a circular disc-like shape is produced on the end-face of the piston-skirt blank when this is done.
In addition to the skirt part of the piston, what is also produced by the known method is a head part of the piston which is likewise of a disc-like basic shape. The diameter of the skirt part of the piston corresponds to the diameter of the head part of the piston in this case. Formed in the end-face of the head part of the piston is a recess whose opening is so defined by an encircling portion which projects into the recess that an undercut is formed between the said portion and the floor area of the recess. To allow the skirt part and head part of the piston to be joined together, the head part of the piston is first placed in a die whose inside diameter corresponds to the outside diameter of the skirt part and head part of the piston. The recess in the head part of the piston faces towards the opening of the die while the said head part of the piston is supported at its other end-face by means of a punch. The piston-skirt blank is then introduced into the die until its projection is seated in the recess in the head part of the piston. The head part of the piston then has a forging force applied to it by means of a shaping punch, which force causes the material of the skirt part of the piston to flow into the recess in the head part of the piston and to fill the undercut which is formed in the latter. The skirt part of the piston is given its cup-like final configuration at the same time.
The piston which is produced by the method from JP 03-267552 A is of an outside shape which is, in essence, completely cylindrical. Formed in the circumferential surface of the skirt part of the piston in this case, closely adjacent to the head part of the piston which is carried by the skirt part of the piston, are grooves for piston rings. Neither the skirt part of the piston nor the head part of the piston have, in this case, any additional configurational features which would make them suitable for a modern-day internal combustion engine. In particular, the known piston does not have any special shaping of the head part of the piston of the kind which is nowadays required if optimum use is to be made of the energy from the fuel which is burnt in the given internal combustion engine. It is also found that simple designs of piston of the kind described in JP 03-267552 A are not equal to the thermal demands which arise in modern-day internal combustion engines.
Comparable possible ways of producing pistons from two parts by means of a positive fit between the parts produced by forging are known from DE 725 761 C, JP 54-021945 A, GB 2 080 485 A or U.S. Pat. No. 3,075,817 A1. However, what all these pieces of prior art have in common is that the pistons which are assembled in a known manner from two parts are each of a simple shape which no longer meets the modern-day demands that are made of pistons for internal combustion engines.
SUMMARY OF THE INVENTION
Against the background of the prior art explained above, an aspect underlying the invention is therefore to provide a method which makes possible the inexpensive production even of pistons of complex shape for internal combustion engines. Another aspect is also to specify a piston for internal combustion engines which can be produced inexpensively with great accuracy of manufacture despite its being of complex shape.
In accordance with the invention, the connection between the two parts of the piston is made by means of a mechanical connection in which the material of the projection on one part is clamped by the material surrounding the recess in the other part in such a way that the two parts are indissolubly connected together. For this purpose, there is formed in the region of the recess in one part an undercut which, on the two parts being compressed, is filled by the material of the projection which flows into it. There is formed in this way a mechanical locking system which operates in essence by positive inter-engagement and which ensures that the two parts of the piston produced in accordance with the invention are held solidly together in a durable way. A major advantage of the invention lies in this case in the fact that the individual parts from which the piston is assembled, which are composed of a steel material for example, can be preformed in a completely finished form and the connection between the parts can be made without any additional connecting members such as screws or bolts. The mechanical connection which is provided in accordance with the invention, which is made by material of the two parts interlocking by positive fit, makes it possible in this case for the at least two individual parts from which a piston according to the invention is assembled to be accurately pre-shaped. When they are put together to form the piston, they are therefore of a minimized weight, which means that only low forces have to be applied to handle the workpieces. What is more, due to the joining process according to the invention, there is no change in the basic shape of the piston and a consequence of this is that, at least as a rule, only a very much reduced amount of mechanical post-processing of the fully joined piston is utilized.
Something which proves to be particularly advantageous in this connection is that the way in which the two parts of the piston are connected in accordance with the invention makes it possible for the piston to be produced by hot-forging operations alone. In this way, as well as the two parts of the piston being pre-fabricated by hot forging, the undercut which is formed in one part may also be produced by hot-forging steps.
For this purpose, a projection is first formed on the first part by means of a shaping tool, which projection is directed substantially in the opposite direction from that in which the tool acts. A lateral force which is directed in the direction of the receptacle is then applied to this projection to form the undercut. When the undercut is produced in such a way in two stages, a projection which has no undercut and from which the forging tool can be separated again by a simple lifting movement is first formed on the first part by means of a suitable tool. Then, by the lateral application of force, the projection is sloped in the direction of the receptacle of the first part in such a way that the projection makes an angle of less than 90° between its free end and the bottom of the receptacle. Any additional stock-removing machining to make the undercut can be avoided in this way.
What is more, with the manner of production in accordance with the invention there is no longer any need for the parts of the pistons to be heated to their melting point locally. With a piston according to the invention there is likewise no longer any risk of changes in microstructure or of stresses arising in the piston which such heating involves.
Another significant aspect of the invention is that the at least two parts are connected together by a simple operation comparable to a forging step. The apparatus required for this purpose can be designed to be simple and hence inexpensive because a special die or comparable aids which determine the flow of the material and prevent the components from deforming are not required in the region of the connecting zone and instead the desired filling of the recess in one part of the piston by the material of the projection on the other part of the piston is ensured by the fact that the projection is plugged into the recess in the other part and the flow of material which then occurs when pressure is applied is determined by the shape of the recess itself.
The outcome is that the invention thus makes available a method which, in a simple and inexpensive way, makes it possible for pistons for internal combustion engines to be produced which are very accurately shaped and, at the same time, able to carry high stresses. Their configuration is selected in such a way in this case that they can be joined together from two parts with simple means without the need for expensive and complicated apparatus or excessively high forces. An embodiment of the invention which is particularly right for practical requirements is characterized in that the recess and the projection are formed at respective end-faces of the parts respectively associated with them. In this embodiment, all that is required to cause the desired flow of material is a compressive force acting in the direction of the longitudinal axis of the piston which is to be produced. At the same time, what is ensured in the case of this arrangement is a connection which is optimum with regard to the stresses which occur in practical use.
A particularly simple form for the parts of the piston and a variant of the method according to the invention which can be carried out in an equally simple way are obtained when one part forms the head of the piston to be produced and the other part forms the skirt thereof.
Basically, it is immaterial to the success of the invention which of the parts the projection and recess are respectively associated with. In this way, in cases where one part forms the piston skirt to which the given connecting rod is coupled in practical use and which guides the piston in the bore of the cylinder and where the other part forms the piston head in whose end-face remote from the piston skirt a dishing for the combustion chamber is usually formed, it is possible for the projection to be formed on the head part of the piston and the recess to be formed in the skirt part thereof. However, from the production point of view it has proved to be particularly practical for the projection to be associated with the skirt part of the piston and the recess with the head part thereof.
Something which also makes a contribution to simplifying that part of the piston which is provided with the recess in the course of previous manufacture is for the recess concerned to have a circular opening.
The undercut which is provided in accordance with the invention in the region of the recess can easily be produced by making the opening of the recess an area which is smaller than the projected floor area of the recess, which projected floor area is situated opposite the opening. With sizing of this kind, the area of the opening is always smaller than the floor area when the latter is projected into the plane of the area of the opening. What this means is that, when the floor area is seen in plan, at least a portion or portions of the edge of the opening are arranged to be offset from the edge of the floor area towards the center of the floor area, which means that an undercut is necessarily formed at the portions in question as the edge of the opening changes to the edge of the floor area. The undercut may be formed in this case by, starting from the floor area of the recess, aligning at least a portion or portions of the circumferential surface surrounding the recess to be inclined towards the area of the opening.
Basically, it is conceivable for the parts which together form the piston to be connected together by cold forming. However, a considerable simplification of the complication which this kind of forming involves can be achieved by, when force is applied to make the positive fit connection between the first and second parts, heating the part which is provided with the projection to forging temperature at least in the region of the projection. When this is the case, the first, cold, part acts, by means of its receptacle, as a die for the forming of the projection on the second part, which projection is inserted into the receptacle and is at forging temperature, which means that there is an assurance of even and complete filling of the undercut region of the receptacle by the material of the projection in the course of the deformation of the projection which occurs as a result of force being applied.
The support which one part of the fully assembled and joined piston has on its other part may be boosted by forming a shoulder at the transition from the projection to the main portion of the part associated with the projection. The other part is able to support itself on this shoulder at least by the wall which defines its recess.
Something that has proved particularly apt for practical requirements is an embodiment of the invention in which at least a portion or portions of the recess are defined by a freely projected collar portion. This collar portion on the one hand forms the shaping element by which the undercut which is filled with the material of the projection on the other part is formed in the region of the recess. On the other hand, the flow of material which occurs in the course of the application of pressure can be steered in such a way that the collar portion ensures that the two parts are clamped together reliably, securely and durably by engaging comparatively deeply into the material of the part of the piston which is provided with the projection and by virtue of the fact that the material of the part provided with the projection surrounds at least a portion or portions of the collar portion.
The security with which the two parts of the piston according to the invention are held together even under the heating-up which occurs in operation can be optimized, while at the same time not changing the simple assembly process, by making the volume of the projection on one part of a size such that, taking into account the thermal expansion of the two parts, the material of the projection completely fills the recess in the other part even in the cooled-down state. For this purpose the shape of the circumference of the projection on one part may be matched to the shape of the opening of the recess in the other part in such a way that the projection is able to be slid into the opening when it is in the state where it is heated to hot-forging temperature, and in such a way that the height of the projection is greater than the depth of the recess.
A significant advantage of the invention lies in the fact that the manner in accordance with the invention of producing a piston allows the respective materials which are selected for the two parts from which the piston is assembled to be ones which are optimally matched to the stresses which act on the respective parts in operation. In this way, the invention makes it possible, when selecting the respective materials, for allowance to be made not only for the respective mechanical stresses but also for stresses which arise as a result of, for example, thermal or chemical effects to which a piston according to the invention is exposed in practical use.
It is therefore proposed in a particularly advantageous embodiment of the invention that one part of a piston according to the invention be manufactured from a first material and that the other part be manufactured from a second material which is different from the first material. As a function of the particular area of use, the first part for example may therefore be previously manufactured from steel of a first grade and the second part from steel of a second grade, or the first part from a grade of steel and the second part from another metallic material and in particular a light metal, or the first part from a ceramic and the second part from a metallic material. As well as hot forging being used as a method of previous manufacture for forgeable materials, previous manufacture by sintering may also be used in accordance with the invention at least for the head part of the piston. The starting material for the head part of the piston is then powdered metal for sintering.
The invention also allows the individual parts from which a piston is assembled in the manner according to the invention to be differently heat-treated or differently treated in some other way to allow for the stresses which act on the respective parts in practice.
The production and configuring in accordance with the invention of a piston for internal combustion engines thus provides a wide range of possible means of optimization which allow pistons of this kind each to be matched to their respective intended uses in the optimum way.
The piston according to the invention is so designed that, while being able to be produced easily, it meets the demands made of modern-day pistons. In this way, it is assembled from two parts produced by hot forging which are connected together by positive fit. At the same time however, in the region of the transition between the head of the piston and the skirt of the piston, an encircling free space which is known per se by means of which the heat which arises in practical use is dissipated in terms of a cooling passage. To achieve this, there is formed, in accordance with the invention, on one part a receptacle which is surrounded by a circumferential wall and, in this receptacle, a recess which is surrounded by an encircling collar portion which is aligned to be inclined at an angle to the longitudinal axis of the piston in such a way that at least one undercut is formed which is substantially completely filled in order to bring about the positive inter-engagement of material of a projection which is formed on the other part, the said free space being left between the outer circumferential surface of the collar portion and the inner circumferential surface of the circumferential wall.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained in detail below by reference to drawings which show an embodiment. In the drawings, which are each schematic longitudinal sections:
FIG. 1 shows a piston assembled from two parts.
FIG. 2 shows the parts from which the piston shown in FIG. 1 is assembled.
FIG. 3 and FIG. 4 show two of the operating steps which are performed when the first part of the piston is being produced.
DESCRIPTION
The piston 1 is assembled from a first, head part 2 of the piston which forms its head and a second, skirt part 3 of the piston which forms its skirt, which parts are connected together by positive fit and friction in the region of a joint zone 4 which is formed between the head part 2 of the piston and the skirt part 3 thereof. The head part 2 of the piston, the skirt part 3 of the piston and also the connection by friction and positive fit between the said two parts 2 , 3 are produced in this case by hot-forging operations.
The head part 2 of the piston is produced from a steel blank by hot forging and is of a disc-like basic shape. Formed in that end-face 5 of the head part 2 of the piston which is associated in practical use with a combustion chamber (not shown) in an engine block (not shown likewise) is a dishing 6 for the combustion chamber. Following on from the end-face 5 there is a circumferential wall 7 which points in the direction of the skirt part 3 of the piston and which surrounds a receptacle 9 which is formed in that end-face 8 of the head part 2 of the piston which is associated with the skirt part 3 of the piston. The area at the bottom of the receptacle 9 is situated opposite the skirt part 3 of the piston and formed in it is a recess 10 .
To produce the head part 2 of the piston, a preform (not shown) is first produced by simple upsetting from a steel blank (not shown likewise) which is heated to a forging temperature of approximately 1050° C., from which preform a piston-head blank 2 a whose basic shape already corresponds to that of the head part 2 of the piston is then produced by means of a forging tool (also not shown). The recess 10 , in its rough shape, has already been formed in this case in the piston-head blank 2 a by means of the forging tool. At the same time, a non-undercut projection 12 a has been formed on the piston-head blank 2 a by the forging tool, which projection 12 a surrounds the recess 10 in an annular form and is aligned in the opposite direction to that direction R in which the forging tool (not shown) acts. In the case of the piston-head blank 2 a , the face of the inner wall of the recess 10 surrounded by the projection 12 a is thus substantially cylindrical.
The calibration of the piston-head blank 2 a then takes place in a further forging operating step. For this purpose, the piston-head blank 2 a is placed in a two-piece calibrating tool K whose bottom part K 1 associated with the end-face 5 of the piston-head blank 2 a copies the finished shape of the dishing 6 for the combustion chamber in the head part 2 of the piston. The top part K 2 of the calibrating tool K has, by contrast, on its side associated with the bottom part K 1 of the tool, a projection V which extends round in an annular shape and which is carried by a plate E.
This projection V is so arranged that, when a piston-head blank 2 a is lying on the bottom part K 1 of the tool by its end-face 5 , the said projection V points into the annular gap S which is present between the projection 12 a and the circumferential wall 7 of the piston-head blank 2 a . Starting from the free end of the projection V, the inner circumferential surface U thereof makes an obtuse angle β of 115-120° with the underside of the plate E which carries the projection V, and the projection V is thus thicker in cross-section in the region of its root which adjoins the plate E than in the region of its free tip. At the same time, the outer circumferential surface of the projection V extends parallel to the inner surface of the circumferential wall 7 .
When the calibrating tool K 2 is lowered, the projection V engages in the annular gap S and its inner circumferential surface U impacts on the projection 12 a on the piston-head blank 2 a . In this way, a lateral force Q directed into the recess 10 is exerted on the projection 12 a and the material of the projection 12 a is displaced by this lateral force Q towards the recess 10 .
As soon as the calibrating tool K 2 has reached its lowest position, at which the tip of its projection V is seated against the bottom of the annular gap S, the projection 12 a on the piston-head blank 2 a has been shaped into the collar portion 12 , which is now arranged in a position where it is inclined at an angle α of approximately 25-30° to the longitudinal axis L of the head part 2 of the piston.
In this way, the circular opening 11 of the recess 10 is surrounded by the encircling collar portion 12 which projects freely into the receptacle 9 and which, starting from the likewise circular floor area 13 of the recess 10 , is aligned towards the longitudinal axis L of the head part 2 of the piston. In this way, the floor area 13 is larger than the area occupied by the opening 11 . At the same time, an undercut 14 is formed in the region of the angle α which is made between the floor area 13 and the collar portion 12 which is arranged to be inclined, which undercut 14 cannot be obtained by a movement which only takes place parallel to the longitudinal axis L.
The skirt part 3 of the piston is likewise produced from a cylindrical steel blank by a plurality of hot-forging operations. For this purpose, the blank (not shown) was placed in the die of a forging apparatus (not shown likewise) in which, starting from one end-face of the blank and by means of a punch, a recess 15 in the skirt part 3 of the piston was then formed in a first forging step, which recess 15 is at the rear relative to the head part 2 of the piston in the fully assembled state. At the same time, a cylindrical projection 16 and a shoulder 17 which follows on without a step from projection 16 and encircles it were formed in the region of the other end-face of the blank, the shapes of which cylindrical projection 16 and shoulder 17 were preset by the die of the forging apparatus. The blank which had been pre-contoured in this way was then fully shaped in a second forging step. Apart from minor differences, the geometrical dimensions of the skirt part 3 of the piston which is obtained in this way correspond to the final size which is required and there are thus only small amounts of mechanical post-processing which have to be carried out (near net shape production).
On the skirt part 3 of the piston which is brought to a finished state in this way, the projection 16 which merges into the main portion 18 of the skirt part 3 of the piston without a step via the shoulder 17 is formed on the end-face situated opposite the recess 10 . The main portion 18 comprises in essence an encircling wall in which are formed, amongst other things, the mounting openings (not visible here) for a connecting rod of the internal combustion engine for which the piston 1 is intended. Except that it is undersized, the diameter D of the projection 16 corresponds in this case to the diameter of the opening 11 of the recess 10 in the head part 2 of the piston, thus enabling the projection 16 to be introduced into the recess 10 in the head part 2 of the piston with a small amount of clearance. The transition from the projection 16 to the end-face 19 is formed to be continuous and free of any steps, i.e. is formed not to have a right-angled shoulder. This configuration makes it easier for the projection 16 to be introduced into the recess 10 .
To simplify the introduction of the projection 16 to an additional degree and at the same time to make it possible for the head part 2 of the piston and the skirt part 3 thereof to be aligned with particular accuracy, the projection 16 may be formed to taper slightly, starting from the shoulder 17 , in the direction of its free end-face 19 .
The height H of the projection 16 is larger in this case than the depth T of the recess 10 . This being so, the dimensions of the projection 16 on the skirt part 3 of the piston are thus matched, overall, to the dimensions of the recess 10 in the head part 2 of the piston, while allowing for a proportion Vk by which the volume of the projection 16 shrinks as it cools down after the skirt part 3 of the piston has been connected to the head part 2 thereof. Where the skirt part 3 and head part 2 of the piston are produced from steel and where that volume of the recess 10 which is to be filled by the material of the projection 16 is V 1 , this extra volume Vk works out as Vk=V 1 ×0.014.
To ensure that there is a connection between the parts 2 and 3 which is lastingly solid under all conditions of temperature, the volume V 2 of the projection 16 is therefore V 2 =V 1 +Vk, the additional volume Vk being formed particularly in the region of the projection 16 , which projection 16 is associated with the collar portion 12 of the head part 2 of the piston after the joining of the skirt part 3 and head part 2 of the piston
To connect the head part 2 of the piston to its skirt part 3 , the skirt part 3 of the piston is first heated to a forging temperature of approximately 1050° C. while the head part 2 of the piston remains at room temperature.
The two parts 2 , 3 are then positioned in suitably shaped receptacles in a compressing apparatus (not shown) in such a way that their longitudinal axes L are in line with one another and the projection 16 on the skirt part 3 of the piston and the recess 10 in the head part 2 of the piston are facing towards one another. The parts 2 , 3 are then moved towards one another until the free end-face 19 butts against the floor area 13 of the recess 10 . A compressive force P acting in the direction of the longitudinal axis L is then exerted on the head part 2 of the piston and/or on the skirt part 3 thereof. This force is sufficiently large for the material M of the projection 16 on the skirt part 3 of the piston, which has been heated to forging temperature, to flow into the space in the recess 10 which had, up till then, been free in the region of the undercut 14 .
The compressing process is continued until the free edge of the collar portion 12 is seated in the hollow 20 at which the projection 16 merges into the adjoining shoulder 17 on the skirt part 3 of the piston. In this state, the steel material of the projection 16 completely fills the recess 10 including the undercut 14 . The head part 2 of the piston is now connected to the skirt part 3 by positive fit by the material of the projection 16 which fits behind the collar portion 12 .
The overfilling of the recess 10 which occurs as a result of the additional volume Vk of the projection 16 is compensated for by elastic deformation of the collar portion 12 . The collar portion 12 , having been deformed in this way, moves back towards its original shape as it cools down and the positive inter-engagement which is created by the filling of the recess 10 is thus supplemented by a frictional engagement which is caused by the interlocking and elastic return of the material of the projection 16 and of the collar portion 12 , which latter is not, or not fully, deformed plastically.
Because the edge region of the collar portion 12 penetrates slightly into the material of the skirt part 3 of the piston, the head part 2 of the piston is, at the same time, supported on the shoulder 17 by means of the collar portion 12 in such a way that, even when the stresses in the region of the dishing 6 for the combustion chamber are adversely distributed, it is ensured that forces will be evenly transmitted from the head part 2 of the piston to the skirt part 3 thereof.
Between the outer circumferential surface of the collar portion 12 and the inner circumferential surface of the circumferential wall 7 there is left, in this case, an encircling free space 21 of a channel-like form which is available in practical use to dissipate the heat from the head part 2 of the piston, particularly in the region of the highly stressed circumferential wall 7 .
For the head part 2 of the piston to be connected to its skirt part 3 , it is, basically, possible for both parts to be heated to hot-forging temperature. It is however enough for only the skirt part 3 of the piston, or even only the projection 16 on the skirt part 3 of the piston, to be heated to hot-forging temperature while no deliberate increase is made in the temperature of the head part 2 of the piston. Regardless of whether the projection 16 is heated on its own or together with the entire skirt part 3 of the piston, the recess 10 in the head part of the piston acts in this case as a forming die for the reshaping of the projection 16 on the skirt part 3 of the piston which is required to connect the skirt part 3 and head part 2 of the piston together. The head part 2 of the piston can then be left in the bottom part K 1 of the tool in this reshaping step. In this way, the bottom part K 1 of the tool can be used not only to calibrate the blank 2 a of the head part 2 of the piston but also as a tool for connecting the head part 2 of the piston to its skirt part 3 . The tooling costs can be reduced in this way and there is also no need for the forging tool to be changed between the individual operations, which, all in all, has a beneficial effect on the costs of production.
REFERENCE NUMERALS
1 Piston
2 Head part of piston
2 a Piston-head blank
3 Skirt part of piston
4 Joint zone
5 End-face of the head part 2 of the piston and of the piston-head blank 2 a
6 Dishing for combustion chamber
7 Circumferential wall of the head part 2 of the piston and of the piston-head blank 2 a
8 Second end-face of the head part 2 of the piston
9 Receptacle in the head part 2 of the piston
10 Recess
11 Opening of the recess 10
12 Collar portion
12 a Projection of the piston-head blank 2 a
13 Floor area of the recess 10
14 Undercut
15 Recess at rear of the skirt part 3 of the piston
16 Projection
17 Shoulder
18 Main portion of the skirt part 3 of the piston
19 End-face of the projection 16
20 Groove at the transition from the projection 16 to the shoulder 17
21 Free space
α, β Angles
D Diameter of the projection 16
E Plate
H Height of the projection 16
K 1 Bottom part of calibrating tool K
K 2 Top part of calibrating tool K
K Calibrating tool
L Longitudinal axis of the piston 1 and of the parts 2 , 3
M Material of the projection 16
P Compressive force
R Direction in which the forging tool acts
T Depth of the recess 10
V Projection on part K 1 of the tool
S Annular gap
U Inner circumferential surface of the projection V
Q Force
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A method for producing a piston for internal combustion engines includes the following steps: a first part is pre-fabricated by hot forging and a recess which has an undercut is formed in the first part during pre-fabrication by forming on the first part a projection, to which projection a lateral force is applied to form the undercut; a second part is pre-fabricated by hot forging and a projection is formed on this second part whose dimensions are matched to the dimensions of the recess; the two parts are joined together so that the projection on one part engages in the recess in the other part; and a compressive force is applied to the two parts which is sufficiently large and so aligned that the material of the projection on one part flows into the recess in the other part and completely fills it to connect the parts by positive fit.
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This is a continuation-in-part of application, Ser. No. 326,795 filed Dec. 3, 1981, now abandoned.
This invention pertains to a manually operated two-position electric switch.
BACKGROUND OF THE INVENTION
The art has disclosed a manually operated switch having an asymmetic cam, which serves to close two spring contacts or hold them apart, depending upon the position of the cam. An indentation in one spring and one asymmetric projection on the cam coact to provide detenting.
A stop inner ledge in the housing and minor projections on the cam coact to stop rotation of the cam at the extremes of both directions.
The relation of the projections on the cam that coact with the spring contacts is such that two brief periods of sliding occur during the closure of the contacts.
This is U.S. Pat. No. 3,878,344.
Another similar switch has an actuator with two relatively widely spaced projections that press upon ridges formed in each of the two spring contacts to give a combined asymmetric structure. Detent action is provided by nesting one projection within the ridge of the adjacent spring.
Projections on each side of the actuator engage a ledge of the housing to provide stops.
There is no teaching as to sliding contacts.
This is U.S. Pat. No. 4,119,823.
BRIEF SUMMARY OF THE INVENTION
A slightly deformable rotor of insulating material coacts with the inner walls of the housing to provide detent action. No stop is required.
Two symmetrical projections upon the bottom of the rotor essentially midway between the walls of the housing engage the free ends of two opposed cantilever springs to make electrical contact in a single significant wiping action upon the rotor being manually rotated to one side. When rotated to the other side the springs are allowed to separate. An original bias of the springs provides a separating force. Additionally, the second projection moves to provide a positive separation.
An alternate embodiment has symmetrical cantilever springs.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan fragmentary view of plural switches in one housing according to the invention.
FIG. 2 is a sectional elevation view of the open switch along line 2--2 in FIG. 1.
FIG. 3 is a sectional elevational view of another closed switch along line 3--3 in FIG. 1.
FIG. 4 is an elevation view of an alternate form of rotor with a fragmentary showing of the upper portion of the housing.
FIG. 5 is a sectional elevation view of an alternate form of the switch in the open position, along line 5--5 in FIG. 7.
FIG. 6 is a sectional elevation view of the alternate form of the switch in the closed position.
FIG. 7 is a top plan fragmentary view of plural switches in one housing having a common rotor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1, numeral 1 identifies the housing of the switch. This is usually made multiple, as from one to twelve positions, as indicated by the fragmentary plural showing in FIG. 1. A multiple of eight of the dual in-line package, "DIP", format is typical. The switch can be made in any size, and as only one unit. However, the DIP size utilizes a width of 1 centimeter (cm), a length of 2 cm, and a housing height of approximately 0.6 cm, with two lines of eight contact pins separated by 0.7 cm.
The housing is fabricated of a hard dimensionally stable plastic, such as a glass-filled polyester. It has the appearance of a trough with several partitions. Spring contacts, to be later described, are interferenced fitted and cemented in the housing. The active spring portions of each are just above the bottom of each compartment and the connection pins pass through the bottom, vertically, and extend in the DIP format.
An aligned central hole 2 passses through all partitions and the ends of the housing to journal the cylindrical stub shafts 3 and 3' that are integral with each rotor 5, 5', etc.
Alternately, the partitions may be formed with slightly non-parallel sides, being thicker at the bottom, so that the stub shafts are nested in a half-journal. Hole 2 through all of the partitions is then not required.
The inter-relation of the principal elements of the switch is shown in FIG. 2. The intimate contact between inner wall 6 of the housing and edge 7 of rotor 5 is seen at the right. Similarly, the intimate contact between inner wall 8 and edge 9 is seen at the left.
In each instance the lower corner of the edge of the rotor, as 7, is below the center-line of shaft 5. This deforms edge 7 for the over-center cam detent action. Similarly, lower corner of edge 9 is above the center-line of shaft 5, and enhances over-center cam detent action.
The lower cantilever spring 11 is captured in housing 1, as is upper spring 12, each passing through housing 1 close to inner walls 8 and 7, respectively. The bottom extensions 11a and 12a of these springs are exterior to the housing and serve as the DIP-configuration external connections to the switch. It has been found that the performance of the spring contacts is superior if the thickness thereof is about one-third that of the bottom extensions; i.e., about 0.11 millimeter (mm) thick.
Copper alloy CDA 688 or CDA 725, or a similar alloy is a suitable material. The contact surfaces are gold plated. The bottom extension is tin or solder plated for ease in soldering. Alternately, a nickel-silver alloy may be used and plating could be eliminated.
Lower spring 11 is pre-tensioned to an upward angle with respect to the inner bottom of housing 1 of not less than approximately three degrees. Similarly, the free position of cantilever arm 12 is twenty-five degrees with respect to the bottom.
In FIG. 2, plural projections 14 and 15 form the lower central part of rotor 5 and mechanically coact with cantilever springs 11 and 12. FIG. 2 shows the electrically "open" position, with the extremities of springs 11 and 12 quite widely separated.
Projection 14 retains spring 11 in the 3° inclined position while the central separation between the projections allows spring 12 to lift to the full extent of the inherent spring bias thereof. Should the bias on either spring be somewhat different than that shown the position and shape of each of the projections retains the springs as required for the proper operation of the switch.
Apertures 16 and 17 in the body of rotor 5 provide the slight deformable property desired of the rotor. The rotor is fabricated of a glass-filled polyester plastic that is less hard than that used for housing 1. With the over-center cam action this flexibility provides a desirable snap action.
Alternately, sides 6 and 8 of housing 1 could be fabricated to be slightly deformable and rotor 5 to be non-deformable.
Rotor 5 assumes the position shown in FIG. 2 upon a force indicated by arrow 18 being exerted upon the upper left part of the rotor, which may be labelled "Off". Classically this would be finger pressure, but where plural switches are present in the DIP format the width of the rotor is only 1.8 mm. Accordingly, a finger-nail, a coffee-stirring stick, or a small screwdriver are preferred manual actuating intermediaries in the hand of the operator.
The deformation structure described gives an audible "snap" when the rotor is actuated. A pressure of approximately six hundred grams is required to operate the switch from "Off" to "On", and vice versa.
Stub shafts 3, 3', etc. are approximately 1 mm in diameter and 0.25 mm long, the latter dimension allowing the shafts to be sprung into central hole 2 and allowing adjacent shafts to colinearly share the same journal in housing 1.
Additionally, the lower part of each interior partition has a slightly increased thickness 10 on each side, say 0.5 mm, to form a pillow block to support the shafts.
Two rows of cylindrical bosses 19 and 20 are disposed about 1 mm from the adjacent DIP terminals. These are approximately 0.5 mm in diameter and 0.5 mm long. These are stand-offs that slightly raise the bottom of housing 1 from the printed-circuit board to which it is typically attached. This allows cleaning after soldering and prevents entrapment of contaminants.
FIG. 3 shows the electrically closed, or "On", position of the switch. The identifying numerals are the same as shown in FIG. 2. Rotor 5 has been rotated clockwise about 60° by the application of force 28 on the upper right top of the rotor.
Spring 12 has been pushed significantly downward by projection 15, which in turn has pushed spring 11 downward by a few degrees. Electrical contact is made on ridge 21, which extends a small portion of the length of spring 12 at the free end thereof.
This ridge contacts ridge 22, which extends the width of opposite spring 11.
It will be seen that as spring 12 bears upon spring 11 because of the clockwise rotation of projection 15, the mutually downward action of the springs results in ridge 21 wiping along ridge 22 of spring 11 in the direction away from the free end. A contact-cleaning wipe occurs in the opposite direction upon moving the rotor to "Off". The final contact area is limited to area of the intersection of the two ridges.
With the sides of the rotor securely detented against the inner walls of housing 1 and projection 15 pressing firmly upon the two springs, it is seen that the electrical contact is locked against vibration or the like. The upward bias pressure of spring 11 maintains the contact with the two ridges.
In certain applications it is desirable to retain a low physical profile for the switch as a whole. This can be accomplished by utilizing a modified rotor 50, as shown in FIG. 4.
The top of the rotor of FIG. 3 is concave upwards, whereas the top of the rotor of FIG. 4 is concave downwards. Rotor 50 thus never extends above housing 1.
Detent action with rotor 50 is accomplished in the same manner as it was with rotor 5. Edge 70, though less extensive than edge 7, coacts with wall 6 as before; as does edge 90 with wall 8.
Lower projections 140 and 150 coact with springs 11 and 12 as before.
The embodiment of FIGS. 5 and 6 is totally symmetrical about a central vertical plane, whereas the prior embodiment(s) have had an asymmetrical contact spring structure. The symmetrical embodiment promotes ease and economy in fabrication.
Rotor 25 of FIG. 5 is the same as rotor 5 of FIG. 2, except that circular cut-out 26 between projections 14 and 15 is about three times larger than before. This accommodates symmetrical cantilever springs 11' and 12' as will be noted by the position of spring 12' in FIG. 5. Instead of being of unequal length, as springs 11 and 12, springs 11' and 12' are of equal length. The whole of the latter springs are of equal size and shape; thus only one spring need be manufactured.
In FIG. 5, spring 12' has been bent in the last manufacturing step to be at a greater angle to its stem 12a' than spring 11'. This "shingles" spring 12' over spring 11'. See FIG. 6.
In the detent position of rotor 25 in FIG. 5, projection 15 allows full opening of the contacts. Projection 14 holds spring 11' down.
As the rotor is rotated clockwise to the detent position shown in FIG. 6, spring 12' is urged downward by projection 15 and spring 11' is released by projection 14. Spring 12' is firmly pressed down upon spring 11' to give the electrically closed condition for the switch circuit.
The configuration shown in FIGS. 5 and 6 provides a closed circuit when rotor 25 is down at the right. By merely interchanging the positions of springs 11' and 12', so that the overlay is opposite, an open circuit is provided when the rotor is down at the right.
In manufacture, plural switch sections, as shown at 10 and 10' in FIG. 7 (and in FIG. 1), can be assembled to give all sections electrically closed when the rotor is down at the right. This is the "Z" configuration, as known in the trade.
If plural switch sections are assembled with the springs overlaid at the right in one section and at the left in another section, then one section has closed contacts with a given position of the rotor and another section has open contacts. This is the known "C" configuration. Compare the overlay of springs 12' in FIG. 7.
It will be understood that plural adjacent rotors, such as 5 and 5' in FIG. 1 and 25 and 25' of the alternate embodiment can be fabricated in one piece, as rotor 27 in FIG. 7, which replaces rotors 25 and 25'. In this way two or more poles of the switching circuit can be actuated at once.
With such a multiple rotor and the selection of how the springs are formed and inserted in switch body 1, it is seen that many desired switching patterns can be actuated by manipulating only one rotor.
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A manually operated switch, typically of DIP size, having a slightly deformable over-center cam rotor journalled in a hollow housing. Symmetrical projections on the rotor move two opposed cantilever springs into and out of electrical contact. The deformation of the rotor provides detent action. Stops are not required. Single wiping action occurs upon closing the contacts. The cantilever springs may be ridged and of unequal length, or not ridged and of equal free length.
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BACKGROUND
1. Field of the Invention
The present invention relates to pipe connectors, particularly, but not exclusively, for use in connecting sections of a pipe string for use in drilling. More specifically, it relates to the design of a pin and box connection of the type used in oil well tubing, casing, and the like. The invention provides a driveable threaded joint with dual mating shoulders and nose faces on the pin and box members. The dual mating shoulders substantially improve the joint's ability to withstand the intense axial compression loading that occurs when driving the pipe into the ground.
2. Description of the Related Art
Threaded connections between pipe members are typically made by providing one end of one pipe member with a male connector in the form of an externally threaded pin member, and providing one end of second pipe member with a female connector in the form of an internally threaded box member which receives the pin member. The pin and box members may be integral parts of their respective pipe members, or may be added thereto by welding or threaded engagement.
In the past, several different types of threaded connections have been designed to manage the extreme compressive, tensile, and bending forces to which the connection is exposed. Several prior art designs incorporate internal and/or external mating shoulders and end faces on the pin and box members. As used in this description, the terms "end face" and "nose face" are interchangeable. In several designs, the mating shoulders are used as torque shoulders to stop axial advancement of the pin and box members during make-up of the joint. In many designs, the shoulders are also used to provide resistance to axial compression during pile driving. Although many prior art designs use a combination of external and internal shoulders, these designs are usually configured such that only one of the shoulders will mate with its corresponding nose face upon initial make-up of the joint. These designs rely on either the external or the internal shoulder alone to mate with its corresponding nose face upon initial make-up of the joint, with the other shoulder remaining axially spaced from its corresponding nose face. The shoulder that is axially spaced from its corresponding nose face at initial make-up may not actually mate until final make-up of the joint, and in some designs may never mate, or only make contact with its corresponding nose face after the threads or other portions of the joint begin to yield. It is one object of the present invention to provide a threaded connection design that uses dual mating shoulders in which both internal and external shoulders mate with their corresponding nose faces during initial make-up of the joint. By providing dual mating shoulders, the shoulders share axial compression loads and provide the joint with improved performance in resisting the extreme axial compression loads encountered during pile driving.
In addition to providing resistance to axial compression loading, the dual mating shoulders in the present invention also function as torque shoulders to stop axial advancement of the pin and box members during make-up of the joint. In several prior art designs, the threaded connections use converging or wedge-type thread flanks rather than shoulders to act as a torque stop. As used in this description, the terms "converging" and "wedge-type" are interchangeable. In general, the pin and box threads in a converging thread flanks connection have progressively changing axial widths. The axial thread width of the pin member progressively decreases in the direction of the mouth of the pin member over the length of the thread structure. The axial thread width of the box member, on the other hand, progressively decreases in the opposite direction, such that a pair of pin and box members in the fully made up condition have a mutually wedging interfit. When converging threads are screwed together and wedging between the flanks takes place, the torsional resistance of the connection increases as the thread flanks act as a torque stop to halt axial advancement of the pin and box members. Several other threaded connection designs use tapered buttress-type thread forms that rely on radial interference to stop axial advancement of the pin and box members during make-up. In a tapered threads configuration, the radial interference fit forms as the crests and roots of the pin and box threads converge upon make-up of the joint
Although these thread form designs may succeed in providing a torque stop to halt axial advancement of the pin and box members during make-up, and also allow the threads to provide resistance to axial compression loading, taking pressure off any pin and box shoulders that may be used in the design, such use of an interference fit in the thread form has its drawbacks. Such uses of interference fits in the thread form may create high surface contact stress on the threads, which can cause galling and other localized thread damage that can severely limit the number of times the connection can be made up. In addition to limiting the repetitive use of the threads, the areas of high surface contact stress are susceptible to stress corrosion cracking, known as sulfide stress cracking, that occurs in petroleum well conduits. It is one object of this invention to provide a threaded joint connection that uses the shoulders of the pin and box members rather than the threads to function as a torque stop.
Conventionally, the pin member of the joint is tapered inwardly from the proximal end of the threaded portion to the distal end to mate with a similarly tapered female threaded box member. The taper facilitates entry of the pin member into the box member. Although the taper facilitates entry of the pin member, the wall thickness at the nose face end of a tapered thread form is often very small, especially in a flush joint configuration. Although the wall thickness at the shoulder of the pin and box member may be a substantial portion of the pipe wall thickness, with the shoulder occupying only a small portion of the wall, the wall thickness at the nose face end may be very small. This tapered configuration leaves the nose face end with a reduced wall thickness that must withstand the extreme axial compression during pile driving, as well as the extreme tensile, compressive, and bending forces to which the pipe is exposed downhole. It is one object of the present invention to provide a threaded pin and box joint in which the thread form is straight rather than tapered, to allow substantially the full one-half thickness of the wall of the pin and box members for sustaining compressive, tensile, and bending forces to which the pipe is exposed.
Although a tapered thread form may facilitate entry of the pin into the box member during make-up of the joint, tapered threads are still susceptible to cross-threading if the pin and box members are not properly aligned at the point of threaded engagement. One example of an apparatus designed to prevent cross-threading is found in U.S. Pat. No. 4,407,527, issued to Mr. Larry E. Reimert. The Reimert patent discloses a guide surface axially spaced from the internal threads of the box member to constrain the relative orientation between the pin and box members prior to threaded engagement. Although the Reimert design may be successful in preventing cross-threading, we have found that the guiding means may also be integrated into a mating shoulder configuration by axially spacing the nose face from the threads on the pin and box members. It is therefore one object of this invention to provide a guiding means for preventing cross-threading that is integrated into the shoulders and nose faces of a pin and box connection.
Several further objects of the present invention include providing means for preventing separation of the pin and box members, providing a thread form configuration that allows quick make-up of the joint, as well as several other objects and advantages that will become apparent from a reading of the attached claims and description of the preferred embodiments.
SUMMARY
These and other objects of the invention are attained by providing one end of one pipe member with a male connector in the form of an externally threaded pin member, and providing one end of second pipe member with a female connector in the form of an internally threaded box member which receives the pin member. The pin and box members may be integral parts of their respective pipe members, or may be added thereto by welding or threaded engagement. In the preferred embodiment of the present invention the pin and box members are integral parts of their respective pipe members, but it should be understand that the inventive design may also be used by mounting the pin and box members on their respective pipe members, or could be used in any of the various forms of collars or nipples known in the art featuring combinations of two box ends, two pin ends, or a box end with a pin end for threaded connection to appropriate ends of two pipe members sought to be mutually connected.
The threaded connection has dual mating shoulders in which both the internal and the external shoulder mates with its corresponding nose face during initial make-up of the joint. By providing dual mating shoulders, the shoulders share axial compression loads and provide the joint with improved performance in resisting the extreme axial compression loads encountered during pile driving. In addition to providing resistance to axial compression loading, the dual mating shoulders in the present invention also function as torque shoulders to stop axial advancement of the pin and box members during make-up of the joint. The thread form on the pin and box members is straight, rather than tapered, and does not have converging thread flanks, so the threads do not act as a torque stop, nor do they provide any substantial portion of the resistance to the extreme axial compression loading encountered during pile driving.
By providing dual mating shoulders that share axial compression loads, and by using a thread form having straight threads with uniform axial thread widths, the compressive loads on the pin and box members are transferred substantially through the shoulders rather than through the thread form. This configuration allows the shoulders to take the brunt of the axial compression loading and spare the threads. This configuration avoids high surface contact stress on the threads to prevent galling and other localized thread damage that would severely limit the number of times the connection can be made up. This configuration also helps to prevent stress corrosion cracking that occurs in areas of high surface contact stress that are exposed to sulfide in petroleum wells. The use of a straight thread form, rather than tapered, provides substantially the full one-half thickness of the wall of the pin and box members for sustaining compressive, tensile, and bending forces to which the pipe is exposed.
The straight thread form provides substantially the full one-half thickness of the wall of the pin and box members for sustaining the forces to which the pipe is exposed, but the ideal design of the pin and box members results in the wall thickness of the pin and box members being not precisely one-half the connector thickness. The optimal design provides that the pin and box members will be of equal strength. In order to design the pin and box members to be of equal strength, the pin and box members are configured to have equal annular cross-sectional areas. Because the inner diameter of the box member is aligned with the outer diameter of the pin member, the medial diameter of the box member is larger than the medial diameter of the pin member. To design the pin and box members to be of equal strength, the wall thickness of the pin member (the member with a smaller medial diameter) is increased to slightly greater than one-half the total wall thickness of the connection, and the wall thickness of the box member (the member with a larger medial diameter) is decreased to slightly less than one-half the total wall thickness of the connection. This optimal design provides substantially the full one-half thickness of the wall of the pin and box members for sustaining the forces to which the pipe is exposed, but also provides that the wall thickness of the pin and box members will be slightly other than precisely one-half the connector thickness, in order to provide that the pin and box members will be of equal strength.
The present invention also provides an integrated guiding means to facilitate entry of the pin into the box member. This integrated guiding means also functions as a self-centering means to align the pin and box members upon threaded engagement to avoid cross-threading. The integrated guiding and self-centering means is achieved by providing a design in which the shoulders and nose faces of the pin and box members are axially spaced from their most adjacent thread flanks. This configuration facilitates entry of the pin into box member, and constricts the relative orientation of the pin and box members at the point of threaded engagement, thus avoiding cross-threading.
Another feature of the present invention is the use of trapped thread flanks to prevent separation of the pin and box members. Conventional pin and box connections are susceptible to separation, often called "jumpout," when the connection is subjected to extensive axial tension and/or bending type loads. Under axial loading in tension, the pin member will shrink due to the "Poisson's" effect, and the box member will expand or "bell out," a condition known as "belling." To counteract these conditions, the thread form is provided with reverse angle load flanks, often referred to as "trapped" or "hooked" thread flanks. When the connection is subjected to axial loads in tension, the trapped load flanks cause the pin member to be pulled radially outward toward the box member, and the box member to be pulled radially inward toward the pin member. This feature secures the pin and box members together and prevents jumpout that could otherwise cause failure of the joint. By placing the box member in a state of hoop compression and the pin member in hoop tension, the trapped load flanks also serve to counteract induced assembly stresses and improve the joint's strength in sulfur environments that could otherwise make the joint susceptible to stress corrosion or hydrogen embrittlement fracture.
In addition to providing trapped thread flanks to prevent jumpout, the present invention provides trapped nose faces as well. Some prior art designs provide mating shoulders and nose faces having dissimilar angles so that the shoulder traps the nose face. One example is found in U.S. Pat. No. 4,822,081, issued to Thomas L. Blose. The Blose patent discloses a shoulder and nose face having dissimilar angles so that the shoulder traps the nose face and the nose face will not slip out upon the application of axial driving force. The present invention improves on this type of feature by providing a trapped nose face that is radially balanced to provide a radially balanced resistance to axial loading in compression. The radially balanced nose face efficiently distributes compressive forces and allows the nose face to withstand increased compressive loading without yielding.
Another feature of the present invention is a thread form configuration that provides a quick make-up of the joint. As can be seen in the drawings more fully described below, the preferred embodiment provides complete make-up of the joint in approximately one and one-half turns, a feature which offers great advantages in the field. The present invention will be more fully understood from the following description of the preferred embodiments, given by way of example only, with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a cross-sectional view of a tool joint constructed in accordance with this invention.
FIG. 2 shows a partial cross-section of a box member.
FIG. 3 shows a partial cross-section of a pin member.
FIG. 4 shows a partial cross-section of the threaded connection prior to make-up of the joint.
FIG. 5 shows a partial cross-section of the threaded connection in the fully made-up condition.
FIG. 6 shows the lower end of a pin member.
FIG. 7 shows a cross-section of the upper end of a box member.
FIG. 8 shows an inner diameter surface flat layout view of a box member.
DETAILED DESCRIPTION
FIG. 1 shows a cross-sectional view of a threaded connection according to the present invention with the pin and box members in a fully made up condition. FIG. 1 shows upper pin member 10 secured into a lower box member 11 to form a connection designated generally as 12 along axis 13. In a preferred embodiment, the threaded connection 12 has mating pin and box members having outside diameters and inside diameters substantially identical for each of the two members. This is commonly referred to as a flush connection when assembled. The flush connection is preferred in practice to avoid irregularities on the outer surface of the joint that cause resistance when driving the casing into the ground or when running the pipe through the well bore. Although the flush connection is preferred, the present invention is not limited to flush connections. Nor is the invention limited to the pin and box members being integral parts of their respective pipe members. The pin and box members may be integral parts of their respective pipe members, or may be added thereto by welding or threaded engagement. Still referring to FIG. 1, the threaded connection 12 includes pin member threads 16 that are adapted to be made-up with box member threads 17. Also shown in FIG. 1 are pin member nose face 18, box member shoulder 19, box member nose face 20, and pin member shoulder 21.
FIG. 2 shows a partial cross-section of the box member 11. The box member 11 includes box member threads 17 having box thread crests 26 and roots 27. The box member threads 17 also include stab flanks 28 and load flanks 29. The term stab flank refers to the side of the thread facing inwardly towards the joint, and the term load flank refers to the side of the thread facing away from the joint.
FIG. 3 shows a partial cross-section of the pin member 10. The pin member 10 includes pin member threads 16, which have pin thread crests 22 and roots 23. Also shown are pin member stab flanks 24 and load flanks 25.
FIG. 4 shows a partial cross-section of the threaded connection prior to final make-up. The figure shows the connection at the point of threaded engagement at which the first stab flank 30 on the pin member contacts the first stab flank 31 on the box member. In this position, one can see that the axial spacing between the nose face 18 and the first stab flank 30 on the pin member, and the axial spacing between the nose face 20 and the first stab flank 31 on the box member, form guiding surfaces 32 on the pin member and 33 on the box member. These guiding surfaces facilitate entry of the pin into the box member and function as self-centering means to align the pin and box members upon threaded engagement to avoid cross-threading. This configuration prevents cross-threading by constricting the relative orientation of the pin and box members at the point of threaded engagement.
FIG. 5 shows the threaded connection in a fully made-up condition. The tolerances of the thread form are designed so that when the joint is fully made-up, although the load flanks are in intimate contact, the clearances remain between the stab flanks to ensure that compressive loads on the pin and box members are transferred substantially through the pin and box shoulders rather than through the thread form. FIG. 5 shows stab flanks 24, 28, 30, and 31 as substantially square. Load flanks 25 and 29 form angle B with respect to a line drawn perpendicular to the longitudinal axis 13 of the connection. Load flanks angle B is preferably between 0 degrees and about 30 degrees, but may vary outside the upper limit of this range depending on the application. This is referred to as a "nonpositive" or "reverse" angle, or, if the angle is greater than 0 degrees, a "trapped" flank. A "trapped" flank also is known as a "hooked" thread. In this configuration, the thread crest extends over the thread root. The nonpositive angled load flanks help ensure that the threads do not slip out and become disengaged during axial loading in tension.
In addition to providing trapped thread flanks to prevent jumpout, the present invention provides trapped nose faces as well. FIG. 5 shows annular shoulders 19 and 21 trapping nose faces 18 and 20 as the threaded connection achieves its fully made-up condition. Nose faces 18 and 20 are radially balanced to provide a radially balanced resistance to axial loading in compression. The radially balanced nose face efficiently distributes compressive forces and allows the nose face to withstand increased compressive loading without yielding. The preferred embodiment represented shows a generally rounded nose face, but it should be understood that several alternative configurations such as a "V" shape or a square plug configuration may be used to achieve a radially balanced trapped nose face. The configuration may also be reversed such that the nose face receives a squared plug shoulder, or a rounded or "V" shape shoulder extension. Several alternative configurations such as these may be used without departing from scope and spirit of the invention.
FIG. 6 shows the lower end of a pin member 10. FIG. 7 shows a cross-section of the upper end of box member 11. Seal groove 44 is identified in FIGS. 6 and 7. Seal groove 44 on the pin member is located proximate the shoulder of the pin member and seal groove 44 on the box member is located proximate the shoulder of the box member. Each of these seal grooves may be used to contain an elastomer ring or metal seal to seal the pin and box members from leakage. The connection may be designed to include one or both of these seal grooves, or may be configured to not include either seal groove. Regardless of whether a seal groove is included in the design, the annular shoulder region 47 of the pin member functions as a seal against the annular end region 48 of the box member, and the annular shoulder region 49 of the box member seals against the annular end region 50 of the pin member. As described above, the annular shoulder region in each member functions as a guiding surface as well as a sealing surface.
FIG. 8 shows an inner diameter surface flat layout view of a box member. The preferred double lead thread form can be seen more clearly in this flat layout view. As can be seen from this figure, the threads are configured to allow the joint to be fully made-up in approximately one and one-half turns. This quick make-up feature provides significant advantages in the field. The present invention can be configured with a single lead thread form or a multiple (two or more) lead, but the preferred embodiment uses a multiple lead thread design because it has been found to provide a stronger connection. The multiple lead thread design also contributes to the quick make-up feature of the present invention because a double thread will advance twice as far as a single thread for each turn of the connection.
The above disclosure and description is illustrative and explanatory of the present invention, and it is understand that various changes in the method steps as well as in the details of the illustrated apparatus may be made within the scope of the following claims without departing from the spirit of the invention.
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A tool joint for use in connecting sections of pipe string for use in drilling. The joint is a pin and box connection of the type used in oil well tubing, casing, and the like. The driveable threaded joint has dual mating shoulders and nose faces on the pin and box members. The connection is designed so that compressive loads on the pin and box members are transferred substantially through the pin and box shoulders rather than through the thread form. The dual mating shoulders substantially improve the joint's ability to withstand the intense axial compression loading that occurs when driving the pipe into the ground.
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BACKGROUND OF THE INVENTION
[0001] (1) Field of Invention
[0002] The present invention relates generally to devices for the accurate and repeated automatic or robotic control of the movement and positioning of a toolhead relative to the surface of a workpiece for carrying out computer-controlled programmed instructions for manufacturing operations.
[0003] (2) Description of Prior Art
[0004] The acronyms CNC and CAM stand respectively for Computer(ized) Numerical(ly) Control(led) and Computer Aided Manufacturing, and refers specifically to the computer control of machine tools for the purpose of (repeatedly) manufacturing complex parts in metal as well as other materials.
[0005] The introduction of CNC machines radically changed the manufacturing industry. Curves were as easy to cut as straight lines, complex 3-D structures were relatively easy to produce, and the number of machining steps that required human action diminished drastically.
[0006] In a production environment, all of these machines may be combined into one station to allow the continuous creation of a part involving several operations. CNC machines are driven directly from files created by CAD (Computer Aided design)/CAM software packages, so that an assembly or part can go from design to production without any intermediate paper drawing work being required. In one sense, CNC machines may be said to represent special industrial robot systems, as they are programmable to perform any kind of machining operation (within certain physical limits, like other robotic systems). CNC machines were relatively briefly preceded by the less advanced NC, or Numerical(ly) Control(led), machines.
[0007] A computer numerically-controlled (CNC) machine tool utilizes computer controlled motors in addition to the position feedback signals to precisely machine components. They may machine components using simultaneous multi-axis coordinated motion. Once the part program (computer software) is prepared, CNC machines can run unattended.
[0008] The machining objective loaded into the controller identifies the current operation as a positioning, contouring or pocketing operation. The machining constraints associated with the current objective are also loaded into the controller. These constraints may differ for each objective, as will be explained shortly. Position transducers (sensors) mounted on the machine tool issue position feedback signals which indicate their positions.
[0009] For contouring operations, a path constraint and a tolerance are specified by the machinist. This path may be in the form of a line/arc definition of the desired trajectory, a mathematical function or any other format that lends itself to manipulation by a computer. The tolerance value, identifying the locus of points that are within a known distance from the path movement, is used to establish the tolerance zone in which the tool motion is permitted. This information along with the position feedback signals is used, in part, to issue control signals to the motion switch means.
[0010] When a positioning operation of the tool is desired, the machinist enters a position constraint and tolerance constraint for each controlled axis collectively defining a target region. These constraints are used to issue control signals to the motion switch means based on the position feedback signals for each axis as transmitted by the position transducers.
[0011] Pocketing operations require the machinist to define boundary surface constraints and may include a tolerance or roughing distance. The “boundary surface constraints” define surfaces with which the tool is not permitted to come into contact and the “roughing distance” defines how close to the boundary surface constraints the tool is permitted to be moved. These constraints and the position feedback signals are used, in part, to issue control signals to the motion switch means, enabling and disabling the relative motion of the tool.
[0012] Computer-controlled carving machines, referred to as “CNC routers,” have been commercially available for some time. CNC routers are expensive and large relative to the size of the workpiece that they can be employed to shape and rout.
[0013] CNC routers suffer from a number of deficiencies, in addition to large physical size relative to the maximally sized workpiece on which they can operate. First, the large bed required to support large workpieces adds considerably to the cost of CNC routers. The large bed size also adds considerable weight to the overall weight of CNC routers, since the large bed must be thickly cast or otherwise rigidly constructed to avoid sagging and other shape alterations. CNC routers require stiff and rigid components, because positional accuracy of the cutting head under computer control is possible only when x, y, and z translations of the cutting head predictably and reliably position the cutting head with respect to the bed, and the workpiece affixed to the bed. In general, CNC routers employ non-intuitive, and difficult-to-learn operator interfaces, and programming of CNC routers generally requires considerable training.
[0014] CNC routers, despite their disadvantages, have enormous usefulness in woodworking and in carving and shaping other rigid and semi-rigid materials. Wood workers, manufacturers, carpenters, artists, hobbyists, and others who carve and shape rigid and semi-rigid materials have thus recognized a need for a cheaper, smaller, lighter, and easier-to-use processor-controlled carving and shaping device.
[0015] A conventional vertical milling machine is equipped with a horizontal table for holding a workpiece, and a power-rotated cutter for machining the workpiece. The table and the cutting tool of a typical three-axis machine are adapted for relative longitudinal movement along a horizontal X-axis, relative lateral movement along a horizontal Y-axis, and relative vertical movement along a Z-axis. The cutting tool in such machines is typically positioned in a spindle in a vertical position, and in certain machines in a horizontal position or in an adapter for selecting either the vertical or horizontal position. In certain high-performance 4-axis machines, the cutting tool is located in a motorized spindle adapted for pivoting about a horizontal axis A, and in 5-axis machines, for rotation about a vertical axis C.
[0016] A conventional vertical turret lathe is equipped with a horizontal table mounted for continuous rotation of the workpiece about a vertical axis, and a non-rotating cutting tool typically positioned in a horizontal position. The table and cutting tool are typically adapted for relative positioning along the X and Z-axes for positioning of the workpiece on the table and machining of the rotating workpiece.
[0017] Numerous variations of milling machines and turret lathes are known in the art, as well as several machines that have attempted to merge the benefits of these two types of machines. One prior type of machine includes an adapter permitting removal of the turret lathe horizontal tool holder and installation of a milling vertical tool holding spindle to effect conversion from turret lathe operation to milling operation. Another prior type of machine provides for a turret lathe and a milling station in close proximity in the same machine to reduce transfer time between the two stations. Yet another type of vertical milling machine has been provided with a table mounted for rotation about a vertical axis and for swiveling about a horizontal axis.
[0018] However, these as well as other prior machines have failed to achieve an effective combination of the machining capabilities of milling machines and turret lathes, coupled with the necessary quick response times, such that the resultant machine is suitable for precision, high-speed CNC milling operations as well as general turning purposes of a conventional turret lathe.
[0019] It is conventional in the U.S. automotive industry to shape a complex workpiece, such as an engine block or head, by transferring such workpiece, clamped on a fixture and pallet, along a series of machining stations where a specific surface is cut or finished by a dedicated tool (or cluster of dedicated tools) fed along a unitary axis. The workpiece must be transferred, with time-consuming effort, to other fixtures and/or pallets to expose a variety of faces to the feed axis of the tools. The percentage of in-cut time exercised by such a system is low due to the frequency of low speed workpiece transfer and due to the slow rates of toolhead positioning. Each toolhead carries out a task dedicated solely to one machining function with little modification over several years of use. The initial cost of fabricating and installing such nonflexible dedicated equipment with complex controls is very high not only due to their sophistication but also due to the large number of single purpose cells needed to complete the shaping of a specific engine block or head.
[0020] While machining devices may be manually or computer-controlled, CNC milling machines are increasingly performing the greatest proportion of such milling tasks. Typical CNC milling machines have a machine spindle head with a rotating spindle shaft that handles a plurality of machining tools, including drills and many styles of chip removing cutters. When these CNC milling machines include a mechanism for exchanging of these chip-cutting tools, they are generally referred to as machining centers. These milling machines and machining centers are designed to produce a finished workpiece from the raw starting material as quickly and precisely as possible. Machines have been developed to operate as fast as possible, and milling tools are designed to efficiently remove large quantities of waste material through their cutting actions. When an exchange of tools is required, the interruption of the machining operation for the tool exchange function is typically so short that little time is added to that of actual machining.
[0021] The spindles on the most common CNC milling machines have either a vertical or horizontal orientation that sets the manner in which the milling cutters address the workpiece. It is obvious that workpieces may require milling from more than one side, and such workpieces require extra operations that may include repositioning of the workpiece on the machine's workpiece mount so that the cutters can address the other sides of the workpiece. This repositioning of the workpiece causes a loss of time and accuracy in the operations. Some milling machines have more than one tool-driving spindle, with secondary spindles being able to work on the same or other sides of the workpiece. Milling machines that have these secondary spindles are, however, of special and expensive construction, and as such are less common in the industry.
[0022] The most complex and expensive milling machines respond to these problems by the inclusion of mechanisms which tilt the spindle or the workpiece about one more axes, thus allowing the cutters to address the workpiece from more than one side. These complex machines, often called universal or 5-axis milling machines, while versatile in achieving many angles of milling, lose rigidity in the tilting mechanisms, accommodate relatively smaller workpieces, and must be constructed with great and costly care to achieve accuracy.
[0023] U.S. Pat. No. 4,146,966 to Levine et al., Apr. 3, 1979, discloses an engraving machine for rings with a rotating workpiece. The limited range of movement does not provide for movement in perpendicular rotational axes around the workpiece.
[0024] U.S. Pat. No. 4,848,942 to Speicher, Jul. 18, 1989, discloses a device utilizing impact pins to mark an arcuate surface. The limited range of movement does not provide for movement in perpendicular rotational axes around the workpiece.
[0025] U.S. Pat. No. 5,190,384 to Speicher, Mar. 2, 1993, discloses a dome and round parts rotary marker utilizing impact pins to mark an arcuate surface. The limited range of movement does not provide for movement in perpendicular rotational axes around the workpiece.
[0026] U.S. Pat. No. 5,203,088 to Morgan, Apr. 20, 1993, discloses a device for engraving an article with a curved surface (e.g., rings). The limited range of movement does not provide for movement in perpendicular rotational axes around the workpiece.
[0027] U.S. Pat. No. 6,145,178 to Green, Nov. 14, 2000, discloses a milling machine with horizontal and vertical spindles. The limited range of movement does not provide for movement in the rotational axes around the workpiece.
[0028] U.S. Pat. No. 6,502,002 B2 to Susnjara et al., Dec. 31, 2002, discloses a multi-purpose, flexible CNC machine for performing a variety of machining operations on all parts of a product. It does not provide for six degrees of freedom of movement utilizing only five axes of movement.
OBJECTS AND ADVANTAGES
[0029] It is an object of the present invention to provide a computer numerically-controlled (CNC) positioning device and platform for numerous types of toolhead assemblies.
[0030] It is an object of the present invention to offer a platform for a smaller, less expensive, lighter, and easier-to-use CNC router and milling machine.
[0031] It is an object of the present invention to offer a platform, outfitted with the appropriate toolhead assembly, to automatically and rapidly size and machine a sphere to a precise diameter, using only two degrees of freedom, that of two perpendicular rotational axes.
[0032] It is an object of the present invention to offer a platform, outfitted with the appropriate toolhead assembly, to automatically and rapidly size and machine an elliptical object (e.g., egg-shaped object) to a precise diameter, width, height, and elliptical arc, utilizing three degrees of freedom.
[0033] It is an object of the present invention to offer a platform, outfitted with the appropriate toolhead assembly, to automatically and rapidly mill various textures or 3D reliefs onto the surface of a sphere or some other arcuate surface.
[0034] It is an object of the present invention to offer a platform, outfitted with the with the appropriate toolhead assembly, to engrave or print photographs, text, or patterns onto the surface of a sphere or some other arcuate surface.
[0035] Advantages of this invention over prior art include the following:
(1) The invention addresses and concentrates on the positioning and platform aspect of a machining device, rather than the toolhead assembly, creating incredibly greater flexibility in function of the invention. (2) It provides a platform for an improved machining device for the high-speed milling of certain parts which previously could only be manufactured by other less efficient methods, so as to reduce total manufacturing time, and increase machining accuracy. (3) It provides a platform for an effective combination of the machining capabilities of high-speed CNC milling operations with that of the general turning purposes of a conventional turret lathe, coupled with quick response times of CNC machines. (4) It provides a platform for a smaller, less expensive, lighter, and easier-to-use CNC router. (5) It provides a platform for the recognized need for a cheaper, smaller, lighter, and easier-to-use processor-controlled carving and shaping device.
SUMMARY OF THE INVENTION
[0041] The present invention is a multi-axis, processor-controlled, toolhead positioning device. It is unique and novel in design and purpose by providing a toolhead positioning device with six degrees of freedom of movement, using only five axes, in a new and innovative configuration. It is also unique and novel in providing a toolhead assembly base for mounting different toolhead assemblies to the invention. The invention is a computerized numerically-controlled (CNC) positioning device for a myriad of toolhead types. Although typical uses come to mind immediately such as milling, routing, and engraving operations, the present invention can also be used to calculate the surface area of a workpiece, print photo images onto an arcuate surface, or perform welding operations; the invention is not limited to machining operations per se. These are simply a few examples for illustrating the capabilities of the present invention. As a toolhead positioning device, the potential uses are limited only by the number of different toolhead assemblies in the world and one's imagination. The multi-axis, processor-controlled, toolhead positioning device is fully scalable and can be adapted to many various sizes, depending on the toolhead assembly mounted to the invention. Those skilled in the art will recognize the numerous toolhead configurations possible with such a toolhead assembly platform. A specific toolhead assembly does not define the invention; it enhances it.
[0042] Degrees of freedom describe the motion of an object in 3-dimensional space. An object in three-dimensional space has six degrees of freedom: three linear coordinates for defining the position of its center of mass, or any other its point, and another three Euler angles defining relative rotation around the body's center of mass. Two main groups describing such degrees of freedom include (1) translation, and (2) rotation. Translation is the ability to move in three dimensions in an X-Y-Z linear coordinate system, while rotation is the ability to change angles around an axis. To break down the six degrees of freedom that an object might possess in 3-dimensional space, each of the following is one degree of freedom: (1) moving up and down (heaving), (2) moving left and right (swaying), (3) moving forward and backward (surging), (4) tilting up and down (pitching), (5) turning left and right (yawing), and (6) tilting side to side (rolling). Directions such as right, left, up, down, front, and back are described as viewed by an individual standing in front of and facing the invention.
[0043] In the multi-axis, processor-controlled, toolhead positioning device, the linear motion up and down (heaving) is achieved through the vertical movement of the workpiece mount in a linear Z-axis. The linear motion left and right (swaying) is achieved through the horizontal sliding movement of the toolhead assembly base (mounted on top of the X-axis carriage) in the longitudinal X-axis. The sliding movement forward and backward of the toolhead assembly base along the transverse Y-axis illustrates the remaining linear motion of moving forward and backward (surging).
[0044] The rotational movement of the workpiece mount provides the first rotational degree of freedom, that of turning left and right (yawing). This is the rotation of the workpiece mount about the vertical Z-axis or preferably, in the rotational C-axis. The rotational movement of the gantry about the longitudinal X-axis (or preferably, in the rotational A-axis) above and around the workpiece, perpendicular to the rotational C-axis of the rotating workpiece, effectively creates the tilting up and down movement (pitching) relative to the workpiece, constituting a second rotational degree of freedom. These five movements (three linear and two rotational) provide five degrees of freedom. However, by combining the rotational movement of the workpiece mount (and its secured workpiece) with the rotational movement of the gantry about and around the workpiece, the remaining third rotational degree of freedom, that of tilting side to side (rolling), is achieved.
[0045] As the multi-axis, processor-controlled, toolhead positioning device's design and concept are its unique features, the previous listed prior art most certainly relates more to a desired ramification than the preferred embodiment.
DESCRIPTION OF THE DRAWINGS
[0046] (1) FIG. 1 is a perspective frontal view of the invention showing an elevated gantry.
[0047] (2) FIG. 1A is a perspective frontal view of the invention showing an elevated gantry along with a workpiece and mounted toolhead assembly.
[0048] (3) FIG. 2 is a perspective rear view of the invention showing a lowered gantry.
[0049] (4) FIG. 2A is a perspective rear view of the invention showing a lowered gantry with a workpiece and mounted toolhead assembly.
[0050] (5) FIG. 3 is a perspective view of the work piece mount assembly and rotary table.
[0051] (6) FIG. 4 is a perspective bottom view of the work piece mount assembly and rotary table.
[0052] (7) FIG. 5 is a cross-sectional view of the work piece mount assembly with a vacuum securing system.
[0053] (8) FIG. 5A is a perspective view of the work piece mount assembly with a mechanical clamping attachment.
[0054] (9) FIG. 6 is a perspective view of the left-hand side (when viewed from the front) support arm with a rotating plate.
[0055] (10) FIG. 7 is a perspective view of the right-hand side (when viewed from the front) support arm with a rotary table and rotating plate.
[0056] (11) FIG. 8 is a perspective bottom view of the gantry bridge assembly.
[0057] (12) FIG. 9 is a perspective view of the X-axis mounting plate with an X-axis carriage.
[0058] (13) FIG. 10 is a perspective top view of the gantry bridge assembly with an X-axis carriage.
[0059] (14) FIG. 11 is a perspective view of an X-axis carriage and a toolhead assembly base.
[0060] (15) FIG. 11A is a perspective view of an X-axis carriage and a toolhead assembly base, with a mounted toolhead assembly.
[0061] (16) FIG. 12 is a perspective front and side view of the gantry and tool head assembly base.
[0062] (17) FIG. 13 is a perspective rear and side view of the gantry and tool head assembly base.
[0063] (18) FIG. 14 is a perspective frontal view of the gantry rotatably mounted to a pair of support arms.
[0064] (19) FIG. 14A is a perspective frontal view of the gantry rotatably mounted to a pair of support arms with a mounted toolhead assembly.
[0065] (20) FIG. 15 is a perspective view of the invention with one support arm.
[0066] (21) FIG. 16 is a perspective view of the gantry with a rotary table attached to a gantry arm.
[0067] (22) FIG. 17 is a schematic block diagram of computer-controlled events.
LIST OF DRAWING REFERENCE NUMBERS
[0000]
24 —Base plate
26 —Workpiece
28 —Workpiece mount assembly
30 —Workpiece mount
32 —First rotary table
34 —First rotary motor
36 —Support tube
38 —Translating tube
40 —Support tube mounting bracket
42 —First linear motor
48 —Translating screw
50 —Retaining nut
52 —Vacuum line
54 —Vacuum chamber
56 —Elastic grommet
58 —Keyway
59 —Clamping device
60 —First vertical support arm
62 —Second vertical support arm
64 —Gantry
65 —Gantry bridge assembly
66 —Gantry bridge
68 —First rotating plate
70 —Second rotating plate
72 —Second rotary table
73 —Second rotary motor
75 —First mounting disc
77 —X-axis mounting plate
78 —Second mounting disc
79 —Carriage mounting bracket
80 —Toolhead assembly base
82 —Y-axis carriage guide rail
84 —First counter weight
86 —Second counter weight
88 —Stiffener plate
89 —X-axis leadscrew
90 —Second linear motor
91 —X-axis carriage
95 —Y-axis leadscrew
96 —Third linear motor
100 —Toolhead holder
102 —Toolhead
106 —First gantry arm
108 —Second gantry arm
111 —Mounting bolt
111 A—Mounting bolt
112 —Mounting bolt
112 A—Mounting bolt
113 —Mounting bolt slot
113 A—Mounting bolt slot
114 —Rotation pin
115 —Mounting bolt slot
115 A—Mounting bolt slot
116 —Toolhead assembly
118 —Contact switch
120 —Computer
130 —Third rotary table
132 —Third rotary motor
DETAILED DESCRIPTION OF THE INVENTION
(1) Preferred Embodiment
[0126] A preferred embodiment of the multi-axis, processor-controlled, toolhead positioning device is illustrated in FIG. 1 and FIG. 2 . FIG. 1 shows a perspective view of the front of the invention illustrating a workpiece mount assembly 28 , an elevated gantry 64 , and the linear and rotational axes of movement. FIG. 2 shows a perspective view of the rear of invention again illustrating the workpiece mount assembly 28 , but showing the gantry 64 in a lowered position. As the invention is described, directions such as right, left, up, down, front, and back are as viewed by an individual standing in front of and facing the invention. The linear and rotational axes of movement referred to throughout this specification are described in greater detail in the summary.
[0127] The major components of the multi-axis, processor-controlled, toolhead positioning device are illustrated in FIG. 1 . They comprise the following: a base plate 24 , a rotating and elevating workpiece mount assembly 28 , vertical support arms 60 , 62 , a rotating gantry 64 , and a slidable toolhead assembly base 80 . The computer 120 , which is vital to the operation of the invention, is not shown in FIG. 1 . FIG. 17 is the only figure that addresses the computer, by providing a schematic block diagram of the computer-controlled events essential to the operation of the multi-axis, processor-controlled, toolhead positioning device.
[0128] As shown in FIG. 1 and FIG. 2 , the first rotary table 32 is mounted on top of the base plate 24 , along with its attached first rotary motor 34 . A support tube mounting bracket 40 is attached to the top of the first rotary table 34 . The workpiece mount assembly 28 is attached to the top of the support tube mounting bracket 40 .
[0129] FIG. 3 shows a perspective view of the workpiece mount assembly 28 attached to the first rotary table 32 . As part of the workpiece mount assembly 28 , one end of a support tube 36 extends vertically upward, normal to the base plate 24 (see FIG. 1 ). The other end of the support tube 36 extends downward below the support tube mounting bracket 40 and through the first rotary table 32 at which point it is attached to the first linear motor 42 (see FIG. 4 ). A translating tube 38 rests inside and extends above the support tube 36 . A workpiece mount 30 with an attached elastic or rubber grommet 56 , or similar elastomeric o-ring, is mounted to the top of the translating tube 38 to provide a secure resting place for the workpiece 26 . A keyway 58 is provided on the translating tube 38 to prevent independent rotation between the translating tube 38 and the support tube 36 . FIG. 4 shows a bottom view of the workpiece mount assembly 28 and its attached first rotary table 32 .
[0130] FIG. 5 shows a cross-sectional view of the workpiece mount assembly 28 . A translating screw 48 attached to the first linear motor 42 , runs vertically from the first linear motor 42 through the support tube 36 , finally connecting to the bottom of the translating tube 38 , for elevating the translating tube 38 vertically up and down. FIG. 5 illustrates one of several means of securing the workpiece 26 . A vacuum line 52 extends into the support tube 36 , coils around the translating screw 48 , and continues its vertical extension upward and through the base of the translating tube 38 into the vacuum chamber 54 (i.e., the translating tube 38 ), for establishing a vacuum in order to secure the workpiece 26 to the top of the workpiece mount assembly 28 . The elastic grommet 56 attached to the top of the workpiece mount 30 , which in turn is mounted to the top of the translating tube 38 , helps provide an airtight seal in effectively maintaining a vacuum on the workpiece 26 to securely hold it in place. The required suction for establishing a vacuum within the vacuum chamber 54 is created by using a source of negative pressure attached to the vacuum line 52 , e.g., a vacuum pump (not shown on the drawings).
[0131] FIG. 5A illustrates a second means of securing the workpiece 26 through the use of a clamping device 59 , such as a chuck or vise system mounted to the top of the translating tube 38 .
[0132] FIG. 6 and FIG. 7 provide perspective views of the vertical support arms 60 , 62 . FIG. 6 shows a first vertical support arm 60 with a first rotating plate 68 pivotably mounted at the top, right-side of the first vertical support arm 60 . FIG. 7 shows a second vertical support arm 62 with a similar second rotating plate 70 , but with a second rotary table 72 and its attached second rotary motor 73 situated between the second rotating plate 70 and the second vertical support arm 62 . The back of the second rotary table 72 is mounted to the top, left-side of the second vertical support arm 62 and the front of the second rotary table 72 is mounted to the second rotating plate 70 .
[0133] FIG. 8 shows a bottom view of the gantry bridge assembly 65 , which is comprised of mounting discs 75 , 78 , a gantry bridge 66 , and an X-axis mounting plate 77 . As shown in FIG. 8 , the gantry bridge 66 is located on the bottom of the gantry bridge assembly 65 , beneath the X-axis mounting plate 77 . Mounting discs 75 , 78 , are attached to the ends of the gantry bridge 66 and X-axis mounting plate 77 combination.
[0134] FIG. 9 shows a top frontal view of the X-axis mounting plate 77 . A second linear motor 90 is attached to one end of the X-axis mounting plate 77 . An X-axis leadscrew 89 attached to the second linear motor 90 , running horizontally from the second linear motor 90 along the longitudinal X-axis of the X-axis mounting plate 77 , is connected midway along the X-axis mounting plate 77 to the X-axis carriage 91 . The rotational movement of the X-axis leadscrew 89 imparts a linear motion to the attached X-axis carriage 91 , allowing it to move linearly along the longitudinal X-axis of the X-axis mounting plate 77 . FIG. 10 shows a top view of the gantry bridge assembly 65 with the X-axis mounting plate 77 mounted on top of the gantry bridge 66 , two mounting discs 75 , 78 , attached to the ends of the gantry bridge 66 and X-axis mounting plate 77 combination, and the X-axis carriage 91 slidably mounted to the top of the X-axis mounting plate 77 .
[0135] FIG. 11 provides an illustration of additional features of the gantry bridge assembly 65 . A rotation pin 114 is attached to the end of the mounting disc 78 directly in the center of the disc. A pair of mounting bolts 112 , 112 A (see FIG. 12 ) is also attached to the end of the mounting disc 78 , and is situated on the same side as the rotation pin 114 , across from one another, with the rotation pin 114 located directly between them. The rotation pin 114 and mounting bolts 111 , 111 A, 112 , 112 A of each mounting disc 75 , 78 are connected to both the first and second gantry arms 106 , 108 , with the mounting bolts 111 , 111 A, 112 , 112 A placed through the mounting bolt slots 115 , 115 A, 111 , 111 A (see FIG. 12 and FIG. 13 ) and the rotation pin 114 placed into a corresponding hole centered in between the mounting bolt slots 115 , 115 A, 111 , 111 A. The rotation pin 114 provides a pivot point about which the gantry bridge 66 and its attached X-axis mounting plate 77 (see FIG. 12 and FIG. 13 ) can be rotated so as to align a mounted toolhead 102 to a reference point on the workpiece 26 . The rotation of the gantry bridge 66 and X-axis mounting plate 77 is accomplished by manipulating the placement of the mounting bolts 111 , 111 A, 112 , 112 A situated within the mounting bolt slots 115 , 115 A, 111 , 111 A. FIG. 16 shows an additional embodiment in which a third rotary table 130 , and its attached third rotary motor 132 , is mounted to the outside of one of the gantry arms 106 . The third rotary table 130 is connected to the mounting bolts 112 , 112 A that are slidably mounted within the mounting bolt slots 115 , 115 A on the first gantry arm 106 (see FIG. 12 and FIG. 13 ). By rotating the third rotary table 132 , the mounting bolts 112 , 112 A are repositioned along and within the mounting bolt slots 115 , 115 A. This causes the gantry bridge assembly 65 to rotate in an A-axis, re-aligning the position of the toolhead assembly base 80 and toolhead assembly 116 attached to it, relative to the workpiece 26 .
[0136] Referring to FIG. 11 , a carriage mounting bracket 79 is attached to the top of the slidably-mounted X-axis carriage 91 . A Y-axis carriage guide rail 82 is mounted to the top of the carriage mounting bracket 79 . The toolhead assembly base 80 is fitted onto the Y-axis carriage guide rail 82 . A third linear motor 96 is attached to the rear of the carriage mounting bracket 79 . A Y-axis leadscrew 95 attached to the third linear motor 96 , running from the third linear motor 96 along the traverse Y-axis of the carriage mounting bracket 79 , is connected to the toolhead assembly base 80 . The rotational movement of the Y-axis leadscrew 95 imparts a linear motion to the attached toolhead assembly base 80 , allowing it to move linearly along the traverse Y-axis of the carriage mounting bracket 79 .
[0137] FIG. 12 is a perspective view of the front of the gantry 64 , showing the gantry arms 106 , 108 connected to each other by the gantry bridge 66 between them. FIG. 13 shows the same gantry 64 from a rear perspective.
[0138] FIG. 14 illustrates the gantry 64 connected to the vertical support arms 60 , 62 . The vertical support arms 60 , 62 are positioned parallel and opposite one another. The first and second rotating plates 68 , 70 are aligned facing each other, with a common centerline. The gantry arms 106 , 108 are mounted to both first and second rotating plates 68 , 70 of the vertical support arms 60 , 62 , placing the gantry 64 between both vertical support arms 60 , 62 . To balance the first and second gantry arms 106 , 108 , each arm has a first and second counterweight 84 , 86 mounted on it, respectively. A stiffener plate 88 (see FIG. 13 ) is mounted to the bottom of the first and second gantry arms 106 , 108 to provide structural support. FIG. 15 illustrates a different embodiment of the invention in which only one vertical support arm is used, providing a cantilever-type modification.
[0139] FIG. 17 provides a schematic of the computer-controlled system, which utilizes computer-aided machining (CAM) program software, either off-the-shelf or developed in-house, to control all movement of the first, second and third rotary motors 34 , 73 , 132 , as well as the first, second, and third linear motors 42 , 90 , 96 . The computer-controlled operation can be set-up with known techniques utilizing known CAM software and therefore will not be described in greater detail here. In-house software programs may be designed and developed to enhance the invention's utility in terms of efficiency and usefulness.
[0140] The function of minor parts (attachment/retaining screws, etc.) is evident from the drawings and is not described here.
(2) Operation of Invention
[0141] As a multi-axis, processor-controlled, toolhead-positioning device, the invention is not defined by a specific toolhead assembly, but by its ability to position a toolhead assembly about a workpiece 26 . The easiest way to describe the operation of the invention is to provide a toolhead assembly as an example, along with a workpiece 26 , and illustrate the movements and controls of the invention. The operational movements of the invention will clearly be shown, but the description of any additional aspects of the toolhead unit will not affect the invention's basic design and operation.
[0142] In the following description of the operation of the multi-axis, processor-controlled, toolhead positioning device, the chosen toolhead assembly for illustration purposes consists of a toolhead holder 100 (e.g. spindle) and toolhead 102 (e.g., cutting tool), with the gantry 64 positioned in a vertical direction, and the toolhead 102 facing due south. The workpiece 26 situated on the workpiece mount assembly 28 is a bowling ball. The invention will position and operate the toolhead assembly so as to engrave a design on the workpiece 26 , e.g., bowling ball.
[0143] To begin the operation, the workpiece 26 (in this case, a bowling ball) is set on top of the elastic grommet 56 or some similar elastomeric o-ring attached to the workpiece mount 30 . A vacuum pump (not shown in the figures) is turned on. As the air is evacuated from the vacuum chamber 54 within the translating tube 48 from the negative pressure exerted by the vacuum pump, the arcuate surface of the bowling ball is pressed against the elastic grommet 56 and the ball is held securely in place through the vacuum force of the applied negative pressure. Note that for other types of workpieces, particularly those without curved or flat surfaces, for which such a vacuum system would prove ineffective in securing the workpiece 26 to the workpiece mount 30 , another type of securing means would have to be in place. Other such options would include mechanical fastening devices (e.g., chucks, vises, clamps, etc.), magnetic devices for certain metallic workpieces, (e.g., electromagnetic systems with external power source, natural magnetic systems), and chemical devices wherein the workpiece 26 may be attached to a mount by some form of epoxy or glue. The degree of security may depend upon the type of workpiece 26 used and the operation to be performed. For instance, the workpiece 26 must be totally secure and rigid in the mount for machining and tooling operations, whereas some form of strong glue attachment may be sufficient for painting operations using a spray paint toolhead assembly. The degree of security therefore depends upon the specific toolhead operation to be performed by the invention.
[0144] Once the bowling ball is securely mounted to the workpiece mount 30 , the first linear motor 42 is engaged to turn the translating screw 48 , which in turn acts to raise the translating tube 38 , and along with it, the bowling ball. Once the bowling ball touches the contact switch 118 located below the toolhead 102 , the computer 120 then automatically calculates the exact diameter of the sphere, knowing the height of the workpiece mount 30 . The computer 120 will then calculate the proper tool, tool paths, and feed rates to apply a particular pattern (for engraving purposes) to a sphere of the calculated diameter. When the calculated tool, tool paths, and feed rates are calculated, the computer will instruct the first linear motor 42 to lower the sphere to the appropriate height such that the centerline of the sphere coincides with the height of the common centerline extending between the first and second rotating plates 68 , 70 . The toolhead 102 (e.g., cutting tool) will then be aligned with a reference point on the workpiece 26 . Typically, this will be the center of the bowling ball.
[0145] Once the toolhead 102 is properly aligned with the reference point on the bowling ball, and the bowling ball is positioned for final tooling, the toolhead 102 is engaged and the computer 120 simultaneously controls the movements of the first rotary table 32 (which rotates the sphere in the C-axis), the second rotary table 72 (which allows the gantry 64 together with the toolhead 102 to rotate about the sphere in the A-axis) and third linear motor 96 (which controls the depth of the cut by allowing linear movement in the transverse Y-axis). Additional refinements to the engraving operation, such as changing the angle of approach of the toolhead 102 in the X and Z-axes, are also available. Off-setting the angle of approach of the toolhead 102 in the X-axis can be accomplished by moving the X-axis carriage 91 (upon which the toolhead assembly base 80 is mounted). Engaging the second linear motor 90 to turn the X-axis leadscrew 89 , acts to move the connecting X-axis carriage 91 , off-setting the angle of approach of the toolhead 102 relative to an arcuate surface area. Off-setting the angle of approach of the toolhead 102 in the Z-axis is accomplished by raising or lowering the bowling ball. Engaging the first linear motor 42 turns the translating screw 48 , which in turn acts to raise or lower the translating tube 38 , and along with it, the bowling ball.
[0146] FIG. 17 is a schematic block diagram of the computer-controlled events. The operation of the computer 120 is as follows: The computer 120 generates tool-paths from a computer-aided machining (CAM) program, and processes it into G-code (directions for electromechanical devices). While operating numerical control (NC) software, the G-code is sent to the controller. The controller takes the G-code and creates individual commands for all axis involved. These commands are sent to the drive for each respective axis. In addition to the commands received from the controller, the drive also receives regulated power from a power supply. The signal from the controller is amplified and sent to a motor as electrical current. The motor's onboard encoder monitors precise rotation, and relays actual positions to controller, and then back to the CNC software. Positional information received from the encoder (through the controller) is referenced by numerical control software and corrective signals are generated if necessary. These actions effect great positional accuracy and system stability.
[0147] As a CNC device, position feedback signals are continually being sent back to the computer 120 and new commands sent to the computer-controlled motors to precisely machine components. Machine components are tooled using simultaneous multi-axis coordinated motions. Once a particular part(s) program (computer software) is prepared, CNC machines are designed to function unattended. The multi-axis, processor-controlled, toolhead positioning device can work with existing software; however, proprietary software may be developed to enhance the capabilities of the multi-axis, processor-controlled, toolhead-positioning device to work with specific toolhead assemblies.
(3) Description and Operation of Alternate Embodiments
[0148] Other alternate embodiments deal with the securing means relative to the workpiece mount assembly 28 . Instead of the vacuum clamping system described in the preferred embodiment of the invention, other securing means are available for securing a workpiece 26 to the workpiece mount assembly 28 . FIG. 5A is a perspective view of the workpiece mount assembly 28 with a mechanical clamping attachment. This clamping attachment may consist of a chuck or some other type of mechanical clamp mounted to the top of the translating tube 38 for securing the workpiece 26 to the workpiece mount assembly 28 . Another securing method may include utilizing magnetic devices for certain metallic workpieces (e.g., electromagnetic systems with external power source, natural magnetic systems, etc.). Yet another securing means may include some form of chemical clamping system involving glues or epoxies. These systems may be appropriate when the workpiece 26 is being photographed, painted, or having some other technique applied to it, whereby a rigid security system is not required.
[0149] The multi-axis, processor-controlled, toolhead positioning device is fully scalable and can be adapted to many various sizes. It may be sized to hold a cutting device for large motors, or it may be sized specifically for engraving bowling balls, or it may be sized even smaller for grinding and polishing lenses. These are simply examples of the scalability of the invention, and are not meant to be limiting by any means.
[0150] It is conceivable that the multi-axis, processor-controlled, toolhead positioning device can be manufactured with one vertical support arm instead of two support arms 60 , 62 as described in the preferred embodiment. FIG. 15 is an illustration of the invention with one vertical support arm.
[0151] Instead of manually adjusting the mounting bolts 111 , 111 A, 112 , 112 A on the gantry 64 , this function may be automated by attaching a third rotary table 130 to one of the gantry arms 106 with control assigned to the computer system. FIG. 16 provides an illustration of a rotary table 130 attached to the gantry arm 106 .
[0152] Still another embodiment of the multi-axis, processor-controlled, toolhead positioning device provides for the addition of a toolhead changer supplied with numerous toolhead attachments.
[0153] Still another embodiment provides for the gantry to be permanently attached to a fixed toolhead assembly unit, unable to move. Instead of the gantry moving, the base of the multi-axis, processor-controlled, toolhead positioning device moves about the toolhead assembly unit. In other words, the base with the attached rotating workpiece rotates about the fixed toolhead assembly unit by means of the pivotably supported vertical support arms.
RAMIFICATIONS
[0154] The vast majority of ramifications concern the type of toolhead assembly mounted onto the multi-axis, processor-controlled, toolhead positioning device's toolhead assembly base. As the invention is designed to provide a precision-positioning device and the associated mounting platform for a toolhead assembly, the following is a list of various ramifications that immediately come to mind. This list is by no means intended to be limiting, but merely indicative of the immense scope and range of uses posed by the current invention. The ramifications include:
(1) the control of a toolhead, such as a machine tool, relative to the surface of a workpiece which is to be machined; (2) the control of a toolhead, such as an engraver, relative to the surface of a workpiece which is to be engraved; (3) the control of a toolhead, such as a polisher, relative to the surface of a workpiece which is to be polished; (4) the control of a toolhead, such as a grinder, relative to the surface of a workpiece which is to be ground; (5) the control of a toolhead, such as a sand blaster, relative to the surface of a workpiece which is to be sand blasted; (6) the control of a toolhead, such as a cutting torch, relative to the surface of a workpiece which is to be torch-cut; (7) the control of a toolhead, such as an ink printer, relative to the surface of a workpiece which is to be printed; (8) the control of a toolhead, such as an paint sprayer, relative to the surface of a workpiece which is to be spray painted; (9) the control of a toolhead, such as an photographic camera, relative to the surface of a workpiece which is to be photographed; (10) the control of a toolhead, such as an coordinate measurement probe, relative to the surface of a workpiece which is to be probed for coordinate measurements; (11) the control of a toolhead, such as an coordinate measurement laser scanner, relative to the surface of a workpiece which is to be scanned for coordinate measurements; (12) the control of a toolhead, which may be a laser beam for directing a laser beam to a impinge upon a particular point on the surface of a workpiece, for cutting or etching the surface; (13) the control of a toolhead, which may be a powder-fed laser fusion welding torch that allows customized welding upon a particular point on the surface of a workpiece, for laser fusion welding by delivery of laser light onto a stream of welding fusion powder; (14) the control of a toolhead, which may be a deposit welder that allows customized welding upon a particular point on the surface of a workpiece by delivery of laser light onto a stream of welding fusion powder; (15) the control of a toolhead, which may be a electron beam welding device that produces a weld by impinging a beam of high energy electrons to heat the weld joint upon a particular point on the surface of a metal workpiece; (16) the control of a toolhead, which may be a electrical discharge machine that erodes material in the path of electrical discharges that forms an arc between an electrode tool and the surface of a metal workpiece; (17) the control of a toolhead, which may be a video camera, relative to the surface of a workpiece for which a video tape or file may be made; (18) the control of a toolhead, which may be a hot melt adhesive dispensing unit, relative to the surface of a workpiece for dispensing adhesive; (19) the control of a toolhead, which may be a gas tungsten arc welding device that produces a weld by forming an arc between a non-consumable tungsten electrode and the particular point on the surface of a metal workpiece; (20) the control of a toolhead, which may be a gas metal arc welding device that produces a deposition weld by releasing a shielding gas which forms the arc plasma and stabilizes the arc on the metal being welded, shields the arc and molten weld pool, and allows smooth transfer of metal from the weld wire to the molten weld pool; and (21) the control of a toolhead, which may be a high pressure water jet cutting device relative to the surface of a workpiece which is to be cut.
[0176] The numerous and varied ramifications are based for the most part on the type of toolhead assembly mounted on the toolhead assembly base. Other ramifications include the grinding and polishing of spherical and aspherical glass lenses, including those for eyeglasses, telescopes, microscopes, etc. The ramifications listed above demonstrate only a small fraction of the potential toolhead assemblies available for mounting onto, and inclusion into, the present invention. The numerous variations would be obvious to one of ordinary skill in the art. The description of the preferred embodiment with a specific toolhead is intended for illustration purposes only in describing the structure and operation of the multi-axis, processor-controlled, toolhead positioning device, and is not meant to be limiting.
CONCLUSIONS AND SCOPE
[0177] In conclusion, the multi-axis, processor-controlled, toolhead positioning device is unique and novel by providing a toolhead positioning device with six degrees of freedom, but utilizing movement in only five axes. This is possible through the design and creation of a new and innovative configuration.
[0178] The multi-axis, processor-controlled, toolhead positioning device is unique and novel in providing a toolhead assembly base for mounting different toolhead assemblies to the invention. By concentrating on the positioning and platform aspect of the machining device, rather than the toolhead assembly, the invention creates much greater flexibility in form and function by being able to utilize the capabilities of many different toolhead assemblies, simply by mounting a specific toolhead assembly to the toolhead assembly base. Then the attached toolhead assembly is allowed to operate about a workspace with six degrees of freedom, but utilizing only five axes of movement.
[0179] By being fully scalable in size, the multi-axis, processor-controlled, toolhead positioning device further demonstrates its flexibility in design and function.
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A multi-axis, computerized numerically-controlled (CNC) toolhead positioning device with six degrees of freedom of movement while utilizing only five axes of movement, comprising a rotating workpiece mount assembly ( 28) and a rotating gantry ( 64) with a mounted toolhead assembly base ( 80). Perpendicular rotational axes about a mounted workpiece ( 26) provide the capability to perform specific toolhead operations on the arcuate surface of the workpiece ( 26), subject to the type of mounted toolhead assembly. The computer ( 120) uses CNC software to integrate operator instructions, machining operations, and the sequence of operations into an automatic and coherent machining package.
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BACKGROUND
[0001] The present invention relates generally to web printing presses and more particularly to a printing press roll having a non-contacting and disengageable motor device for rotating the roll during webbing-up.
[0002] To prepare for printing operations in a web offset lithographic printing press, the web end must first be fed over the various rolls and through the various nips in the press to the end of the press. This process is known as “webbing-up.” Webbing-up may be performed in a variety of ways including manually, or by using automatic or semi-automatic web-up systems. As part of the webbing-up process an operator may manually rotate a roll to feed the web past the roll. Such manual feeding and roll rotation operations can be difficult and time-consuming, as well as present a safety hazard to the operator.
[0003] For example, former rolls below a former may be rotated by hand to assist in feeding the web through the nip area between the former rolls of a folder and into the lower portion of the folder. Because the web drives the rolls and due to the fact that the rolls are in close proximity to each other, there is a nip hazard present, i.e., there is a danger that the operator's hand may become caught between the rolls and injured. Several guard designs have been employed in previous machines to protect the operator from the nip area. Many of these prior guard designs inhibit the operator from rotating the rolls to assist in webbing up.
[0004] Commonly-owned U.S. Pat. No. 5,605,267, which is not necessarily prior art to the present invention, describes a device for automatically advancing the end of a web over a former and into a folder unit in a printing press. A motor is used to rotate an endless belt which contacts the web and advances the web over the former and down through the former rolls. The motor also rotates the former rolls via belts to push the web through the former rolls and into the folder. A machined groove is required in one or both of the former rolls, which may result in marking on the printed product.
[0005] Prior devices may be complex and expensive.
SUMMARY OF THE INVENTION
[0006] The present invention provides a roll for a web printing press. The roll includes a cylindrical member configured for supporting a web, the cylindrical member being rotatable about an axis of rotation. Also included is a non-contacting and disengageable motor device disposed at the axis of rotation and configured for rotating the cylindrical member so as to advance the web over the cylindrical member during a webbing-up operation.
[0007] The cylindrical member may be movable axially and laterally and the motor device may be movable therewith. The motor device may be operable in conjunction with an automatic webbing-up system. Moreover, the motor device may be further configured for permitting the cylindrical member to rotate freely during a printing operation, or “normal operation,” of the printing press.
[0008] The motor device may include an electric motor. The electric motor may be disposed at an end portion of the cylindrical member. Moreover, the electric motor may be housed within the cylindrical member.
[0009] The motor device may include a fluid motor. The fluid motor may be an air motor including a plurality of vanes attached to the cylindrical member and an air source configured for blowing air against the vanes so as to cause the cylindrical member to rotate. The vanes may be housed within the cylindrical member or within a housing disposed at an end of the cylindrical member. The air source may include an air outlet integrated in the shaft and disposed so as to blow air against the vanes. Moreover, the air source may include an air outlet disposed outside the cylindrical member so as to blow air against the vanes.
[0010] The roll may further include a control device for controlling a flow of air to the air motor, the control device being configured for stopping the flow of air to the air motor a predetermined time after a release of an operator air flow activation device.
[0011] The roll according to the present invention maybe a former roll.
[0012] The present invention also provides a web printing press including a cylindrical member configured for supporting a web, the cylindrical member being rotatable about an axis of rotation. A motor device is disposed at the axis of rotation and configured for rotating the cylindrical member so as to assist the advance of the web over the cylindrical member during a webbing-up operation.
[0013] The present invention also provides a method for rotating a roll in a web printing press during a webbing-up operation. The method includes: providing a motor device disposed at an axis of rotation of the roll and configured for rotating the roll so as to advance the web over the roll; and operating the motor device so as to rotate the roll.
[0014] The present invention provides a relatively inexpensive way of remotely rotating rolls, such as former rolls, during webbing-up, allowing a more complete roll/nip guard design.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The present invention is elaborated upon below based on exemplary embodiments with reference to the accompanying drawings.
[0016] [0016]FIG. 1A shows a schematic front elevational view of a former according to an embodiment of the present invention.
[0017] [0017]FIG. 1B shows a schematic side elevational view of the former of FIG. IA.
[0018] [0018]FIG. 2 shows a detail schematic plan view of area A of FIG. 1A according to an embodiment of the present invention using an electric motor.
[0019] [0019]FIG. 3 shows a detail schematic plan view of area A of FIG. 1A according to another embodiment of the present invention using an air motor.
[0020] [0020]FIG. 4 shows a perspective partial view of a former roll according to the embodiment of the present invention shown in FIG. 3.
[0021] [0021]FIG. 5 shows a schematic plan view of a pair of former rolls according to an embodiment of the present invention.
[0022] [0022]FIG. 6A shows a schematic plan view of a former roll portion of a former according to an embodiment of the present invention.
[0023] [0023]FIG. 6B shows a schematic cross-sectional view along section B-B of the former roll portion of FIG. 6A.
[0024] [0024]FIG. 6C shows a perspective view of the vane housing of the former roll portion of FIGS. 6A and 6B.
DETAILED DESCRIPTION
[0025] [0025]FIGS. 1A and 1B show schematic views of a former 100 according to an embodiment of the present invention. Former 100 includes cylinder 2 , former board 4 and former rolls 10 . Web 1 travels over cylinder 2 and down former board 4 through nip 6 between former rolls 10 . Due to the triangular shape of former board 4 and the interaction with former rolls 10 , web 1 is folded as it travels through former 100 .
[0026] [0026]FIG. 2 shows a detail schematic plan view of area A of FIG. 1A according to an embodiment of the present invention using an electric motor 17 . Former rolls 10 each include respective outer cylindrical member 11 which rotates about respective shaft 12 . Adjustment devices 22 permit former rolls 10 to be moved horizontally and vertically in the direction of axes L and X (see FIG. 1B), respectively, for adjustment purposes. Former rolls 10 are each provided with respective electric motor 17 . Each electric motor 17 includes stator member 16 and rotor member 18 . Stator member 16 is affixed to shaft 12 , while rotor member 18 is affixed to cylindrical member 11 radially outside the stator member. By the electromagnetic interaction between rotor member 18 and stator member 16 , rotor member 18 —and with it cylindrical member—is caused to rotate about shaft 12 on bearings 14 disposed at either end of the shaft.
[0027] Stator member 16 and rotor member 18 of electric motor 17 may be disposed inside cylindrical member 11 , as shown in FIG. 2. As such, a compact design is provided in which electric motor 17 moves with cylindrical member 11 when the position of former roll 10 is adjusted using adjustment device 22 . In other embodiments of the present invention, electric motor 17 may be disposed on an end portion of shaft 12 outside of cylindrical member 11 . In such embodiments, electric motor 17 also moves with former roll 11 when the position of former roll 10 is adjusted using adjustment device 22 . Of course other configurations of electric motor 17 are possible. In some embodiments of the present invention, for example, stator member 16 may be disposed radially outside rotor member 18 so that rotor member 18 rotates inside of, rather than, outside of stator member 16 .
[0028] Control device 32 is provided for controlling the speed of electric motor 17 . Power is supplied to control device 32 via electric line 34 . Power is supplied from control device 32 to electric motor 17 via electric line 36 . Control device 32 includes control button 38 , which permits an operator to activate and/or stop the rotation of cylindrical member 11 . Control device may include a timer mechanism which acts to keep electric motor 17 energized, and thereby rotor member 18 rotating, for a predetermined time, which maybe variable, after an operator pushes control button 38 . When no power is provided to electric motor 17 , former roll 10 may rotate freely under the action of moving web 1 during printing operations, for example.
[0029] [0029]FIG. 3 shows a detail schematic plan view of area A of FIG. 1A according to another embodiment of the present invention using an air motor 47 . Former rolls 10 each include respective outer cylindrical member 11 which rotates about respective shaft 12 . Adjustment devices 22 permit former rolls 10 to be moved horizontally and vertically in the direction of axes L and X (see FIG. 1B), respectively, for adjustment purposes. Former rolls 10 and are each provided with respective air motor 47 . Each air motor 47 includes air nozzle 45 and vanes 41 . Air nozzle 45 , fed by air line 46 , is fixed relative to shaft 12 , while vanes 41 are affixed to the inside of cylindrical member 11 (see FIG. 4). As such, a compact design is provided in which vanes 41 move with cylindrical member 11 when the position of former roll 10 is adjusted using adjustment device 22 . Air from air nozzle 45 is blown against vanes 41 , causing the vanes to move and thereby causing cylindrical member 11 to rotate about shaft 12 on bearings 14 disposed at either end of the shaft. In other embodiments of the present invention, air from air nozzle 45 may be blown into a chamber (not shown) and then allowed to escape through vanes 41 , causing the vanes to move. Spent air may exit cylindrical member 11 via open ends of the cylindrical member or any other suitable openings provided for this purpose (not shown).
[0030] Control device 42 is provided for controlling air motor 47 . Air is supplied to control device 42 via air line 44 . Air is supplied from control device 42 to air motor 47 via air line 46 . Air line 46 may be flexible along at least a portion of its length, to permit nozzle 45 to move during position adjustment of former roll 10 using adjustment device 22 . Control device 42 includes control button 48 , which permits an operator to activate and/or stop the rotation of cylindrical member 11 . Control device 42 may include a solenoid and regulator mechanism. Moreover, control device 42 may include a timer mechanism which acts to keep air flowing to air motor 47 , and thereby keep vanes 41 rotating, for a predetermined time, which may be variable, after an operator pushes control button 48 . When no air is provided to air motor 47 , former roll 10 may rotate freely under the action of moving web 1 during printing operations, for example.
[0031] [0031]FIG. 4 shows a perspective partial view of former roll 10 . Vanes 41 project inward from cylindrical member 11 . Vanes 41 may be formed integrally with cylindrical member 11 or may be attached to the cylindrical member. In other embodiments of the present invention, vanes 41 may be separate from, but connected to, cylindrical member 11 so that the cylindrical member rotates when the vanes move under the action of air against the vanes.
[0032] [0032]FIG. 5 shows a schematic plan view of a pair of former rolls according to an embodiment of the present invention in which air nozzle 45 is integrated into shaft 12 . In this embodiment, shaft 12 is provided with drilled passage 43 . Passage 43 is closed with plug
[0033] [0033] 49 . Air line 46 is connected to passage 43 via fitting 51 . Nozzle 45 is integrated into shaft 12 at any desired position, or combination of positions, along passage 43 , as shown in FIG. 5. Air flows from control device 42 , through air lines 46 , into passage 43 and out nozzle 45 to impinge against vanes 41 . This embodiment enables vanes 41 to be disposed in any longitudinal position along cylindrical member 11 .
[0034] FIGS. 6 A-C show another embodiment of the present invention using an air motor 60 with vanes 41 disposed on an end portion of shaft 12 outside of cylindrical member 11 . Housing 64 serves as an enclosure for vanes 41 and to prevent damage to the vanes, as well as providing enhanced control of air flow to the vanes, and thereby more power to rotate former roll 10 . Air is supplied to housing 64 from air line 46 via air inlet 66 . Housing 64 may be slidably and rotatably supported relative to, and even on, shaft 12 , and at least a portion of air line 46 may be flexible so that air motor 60 may move with former roll 10 when the position of former roll 10 is adjusted using adjustment device 22 . A control device 42 (not shown in FIGS. 6 A-C), as described above with reference to FIG. 3, may be provided for controlling air motor 60 . Air flows from control device 42 , through air line 46 , and into housing 64 via air inlet 66 to impinge against vanes 41 .
[0035] In other embodiments of the present invention, other types of motors may be used to rotate cylindrical member 11 . For example, other types of fluid motors, such as hydraulic motors may be used. Additionally, each former roll 10 may be provided with a motor at each end of shaft 12 , to provide additional torque for rotating larger rolls, for example.
[0036] By properly controlling the rotation of cylindrical members 11 , operator can feed web through former rolls 10 in a controlled and safe manner without the need to rotate the former rolls by hand. By disengaging the motor, i.e., removing the electrical power, air flow, etc., to the motor, cylindrical member 11 may rotate freely during printing operations under action of the moving web. Since the motor is located at the axis of rotation and no contact devices, such as belts, etc., are required between the motor and cylindrical member 11 , the former roll according to the present invention has a compact and simple design. The former roll according to the present invention may also be decelerated or stopped using the provided motor. Moreover, the former roll according to the present invention may also be used in conjunction with an automatic webbing system.
[0037] It will of course be understood that the present invention has been described above only by way of example and that modifications of details can be made within the scope of the invention. For example, the roll of the present invention is not limited to former roll applications, but may be used for other rolls in a web printing press.
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A roll for a web printing press includes a cylindrical member configured for supporting a web, the cylindrical member being rotatable about an axis of rotation. A motor device is disposed at the axis of rotation for rotating the cylindrical member so as to advance the web over the cylindrical member during a webbing-up operation.
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BACKGROUND OF THE INVENTION
The present invention relates to a tablet making machine comprising a frame, a spindle mounted on the frame and fixed to the frame at opposite ends and a rotor carried by bearings mounted on an intermediate axially extending portion of the spindle, the rotor including a die table carrying dies and opposed pairs of punches, one pair for each die guided in punch guides of the rotor, the positions of the punches being controlled by fixed cam means carried from the frame.
With such a machine any "run-out", i.e. wobble of the rotor is fully controlled, to a minimum, to improve the consistency of the die fill and hence the tablet weight consistency.
Certain proposals have already been made for reducing downtime for tool and product changeover on rotary tablet presses. In one such proposal, described in German Petty Patent No. 87 06 056.6 the press has a rotor located in a housing and connected to a drive shaft, the rotor including a die table and means in which top and bottom punches are guided, the position of which is controlled as the rotor rotates by fixed cams mounted on holders. The holders are connected to fixed parts of the machine housing by detachable connectors and coupled by freely running couplings, to the rotor, these couplings coming into play when the rotor is lifted from the drive shaft, after the connectors for the holders have been detached, to connect the cams and holders to the rotor for removal with the rotor from the press. The machine in this case is a spindleless machine, the rotor being cantilevered on the drive shaft bearings.
SUMMARY OF THE INVENTION
The present invention aims to provide significant improvements in downtime for spindled presses.
This is achieved in accordance with the present invention in that, proceeding from a machine as defined in the opening paragraph of this specification, the intermediate, axially extending portion of the spindle is formed as a separate portion of the spindle which is normally fixed in position by releasable means which, when released, allows the intermediate portion of the spindle to be removed transversely from the machine, together with the rotor and the rotor bearings.
In a preferred development, in accordance with the present invention, said intermediate, axially extending portion of the spindle is axially clamped in its normally fixed position and supports a fixed frame member which carries the cam means for controlling corresponding ones of the punches of each pair, said fixed frame member being removable with said intermediate axially extending portion of the spindle
This feature permits, e.g. the cam means controlling the top punches, to be removed from the machine directly with the rotor, without any need to unfasten any further, individual fastenings.
It is also preferred that said intermediate, axially extending portion of the spindle is axially clamped in its fixed position between opposite end portions of the spindle carried by the frame.
By this means, the intermediate spindle portion may be readily unclamped, e.g. from one end, for removal from the machine.
The rotor may be driven by drive dogs on a drive pulley rotatably mounted on one of said fixed end portions of said spindle, the drive dogs engaging drive dogs on the pulley, and the other fixed end portion of the spindle may be axially displaceable by fluid pressure to clamp the intermediate, axially extending portion of the spindle against said one fixed end portion of said spindle.
With this arrangement, the inter-engaging drive dogs are freed of the clamp-up loads.
Conveniently, the drive dogs are engageable and disengageable axially of the spindle and said one fixed end portion of said spindle incorporates a jack means operable to lift said intermediate axially extending portion of the spindle to disengage the drive dogs and position the intermediate portion for transverse removal from the machine.
These and other advantageous features of the present invention will become clear from the following detailed description, given by way of example, with reference to the accompanying figures of drawings which show one specific embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of a tablet making machine in accordance with the present invention and showing centrally a trolley in a rotor removing position and bearing the machine rotor carried by an intermediate axially extending portion of the spindle, which has been transversely removed from the machine, together with the cams and cam holders, on a conveyor roller belt of the trolley, the original tablet making position of the rotor in the machine being shown in chain dotted outline, and the trolley also being shown in chain dotted outline in a removed position carrying away the rotor for servicing;
FIG. 2 is a vertical cross-section of a relevant portion of the tablet-making machine of FIG. 1 in its assembled tablet making condition;
FIG. 3 is a corresponding view showing the intermediate, axially extending portion of the spindle lifted by the jack means ready for transverse removal of the rotor and the cams and cam holders from the machine on the trolley conveyor;
FIG. 4 is a horizontal section on line 4--4 in FIG. 1;
FIG. 5 is a vertical section on line 5--5 in FIG. 4; and
FIG. 6 is a hydraulic circuit diagram.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference now to the figures of drawing and first to FIG. 1, the machine comprises a base frame 10 comprising a cabinet 11 having a cabinet top 12 and an upper frame 13 comprising a cabinet 14 supported from the lower frame on pillars, there being two front pillars 15 disposed one to each side of the cabinet top 12 towards the front and two rear pillars 16 disposed more centrally than the front pillars 15 towards the back of the cabinet top 12. The positions of the pillars 15 and 16 are most clearly seen in the cross-sectional view of FIG. 4.
The machine has a rotor 18 arranged to be driven by a drive pulley 19 through inter-engaging drive dogs 20, 22. The pulley 19 is arranged to be driven from a drive shaft 24 by a drive belt 26.
The drive pulley 19 is carried by bearings 28, 30 mounted on a lower, fixed end portion 32a of a spindle 32 attached to the machine base frame 10. An upper, end portion 32c of the spindle 32 is attached to the machine upper frame 13. The portion 32c of the spindle comprises a fluid operable clamp-up member 34 which is displaceable axially of the spindle by fluid under pressure supplied to a cylinder space 36 to urge the member 34 downwardly in the drawings into engagement with the upper end face 38 of an intermediate, axially extending portion 32b of the spindle 32 thereby to clamp the lower end face 40 of the portion 32b of the spindle against the upper end face 42 of the spindle portion 32a.
The member 34 is reversely displaceable by the supply of fluid under pressure to a cylinder space 44 to unclamp the mid-spindle portion 32b and the spindle portion 32a incorporates a fluid operable jack 46 which may be raised by the supply of fluid under pressure to a cylinder space 50 to lift the mid-spindle portion 32b to the position shown in FIG. 3, in which the drive dogs 20, 22 are disengaged
The mid-spindle portion 32b mounts rotor bearings 52, 54 which carry the rotor 18. The rotor 18 comprises a die table 56 carrying dies 58 and opposed pairs of punches 60, 62 one pair for each die. The punches 60, 62 are guided in punch guides 66, 68 of the rotor, the positions of the punches 60, 62 being controlled by respective upper and lower fixed cams 70, 72.
The upper cam 70 is carried by a support 74 fixed to the upper end of the mid-spindle portion 32b and the lower cams are carried by a cam plate 78 which is fixedly clamped to the cabinet top 12 of the machine base frame 10 by two front fluid pressure extendible pins 80 extendible radially inwardly by the supply of fluid under pressure to cylinder spaces 82 to positions as shown in FIGS. 2 and 4 and by one rear fluid pressure clamp down pin 84 having a head 86 to engage with its underside against the top of the cam plate 78 when fluid under pressure is supplied to cylinder space 90 (see FIG. 5).
On unclamping of the cam plate 78 by retraction of the pins 80 to positions as shown in FIG. 3 by the supply of fluid under pressure to the cylinder spaces 88, and on raising of the pin head 86 by the supply of fluid under pressure to the cylinder space 91 seen in FIG. 5, the cam plate 78 is released to be raised by cam plate support blocks 92 which normally maintain a running clearance with a rotor flange 94 but which engage with the flange 94 to cause the cam plate 78 to be lifted with the rotor 18 when the mid-spindle portion 32b carrying the rotor is lifted by the jack 46.
In this lifted position, as seen in FIG. 3, the rotor 18 is freed to be removed transversely from the machine, complete with the mid-spindle portion 32b and the rotor bearings 52, 54, the upper cam support 74 and the upper cam 70, the cam plate 78 and all the punches 60, 62.
To assist in this operation trolley fork passages 96 are provided in the cabinet top 12 for trolley forks 100 of trolley 102 (see FIG. 1) to engage beneath the cam plate 78 to support the rotor 18 so that it can be wheeled by the trolley, out of the machine.
A fully serviced replacement rotor 18 may then immediately be wheeled into position on a further trolley 102 and lowered into drive engagement in the machine by lowering of the jack 46, the clamp-up member 32c next being operated to clamp the rotor 18 in its tablet making position, at the same time refixing the upper cam support 74 and cam 70. Additionally, the clamp pins 80, 84 are operated to clamp the lower cam plate 78 fixedly to the cabinet top 12, this re-establishing the machine in its operational mode.
As seen in FIG. 4, the replacement cam plate 78 is positioned against the rear pillars 16, when the replacement rotor is wheeled into position on the trolley 102 and then centred by extension of the pins 80, which have tapered ends 104 to engage chamfers 106 on the upper edge of the cam plate 78, the cam plate having cut outs 108 to engage the pillars 16, the pin head 86 being lowered to prevent any tilting of the cam plate. The upper end portion 32c and the mid-spindle portion 32b of the spindle have guide bosses 110 and 112 at their lower ends respectively which enter recesses 114, 116 in the upper ends respectively of the mid-spindle portion 32b and the lower end portion 32a of the spindle, thereby to centre the mid-spindle portion 32b with respect to its end portions upon reinstatement of a rotor 18.
In an alternative arrangement, the clamp-up member 32c may engage the upper cam support if desired, the upper cam support 74 covering over the upper end of the mid-spindle portion 32b.
The hydraulic system of the machine enabling rotor 18 removal and replacement will next be described with reference to FIG. 6. The hydraulic system comprises a hydraulic pump 120 connected to be driven by an electric motor 121 to draw fluid from a fluid reservoir 122 and supply the fluid under pressure to a conduit 124. When the line pressure reaches a preset value, determined by the setting of a pressure relief valve 126, a two-position solenoid valve 128 is operated to move to its second position against the action of its spring 130, thereby to initiate the retraction of the clamp pins 80 and the raising of the clamp pin head 86. Hydraulic fluid flows into a conduit 132 and opens a check valve 134. The pressure fluid then flows via a non-return valve 135 and a conduit 136, and also via conduits 138 and 140, into the cylinder spaces 91 and 88 already described. At the same time, hydraulic fluid is exhausted from the cylinder spaces 90 and 82 and flows via a conduit 142, the check valve 134, the solenoid valve 128 and conduit 144 back into the fluid reservoir 122.
A two-position solenoid valve 146 is next operated to move to its second position against the action of its spring 148 to select a light fluid-pressure-holding of the clamp-up member 34 to hold the rotor 18 steady during its subsequent lifting operation by the jack 46. A two-position solenoid valve 150 is moved against the action of its spring 152 to its second position. A three position solenoid valve 154 remains in its second position as shown in FIG. 6. A three position solenoid valve 158 is adjusted upwardly in FIG. 6 to its third position. Fluid under pressure flows via a conduit 160 and non-return valve 162 into the cylinder space 50 to raise the jack 46, thus forcing hydraulic fluid out of the cylinder space 36 via a conduit 162, the solenoid valve 150, a pressure relief valve 164, the solenoid valve 146 and line 144, back to the hydraulic fluid reservoir 122.
The rotor 18 is now in its raised position shown in FIG. 3. Solenoid valve 158 is returned to its second, i.e. central, position, as illustrated in FIG. 6. This locks the jack 46 in its raised position.
A sensor (not shown) is provided to indicate that the trolley 102 is in position with its forks 100 engaged beneath the cam plate 78.
Solenoid valve 158 is adjusted to its first position, i.e. downwardly, in FIG. 6. The weight of the rotor 18 then forces hydraulic fluid out of the cylinder space 50 via a fluid flow restrictor 166, the conduit 160, the solenoid valve 158, and the conduit 144 back to the hydraulic fluid reservoir 122. At the same time, the solenoid valve 154 is adjusted upwardly in FIG. 6, into its third position. Hydraulic fluid flows via a conduit 170 into the cylinder space 44. The pressure of fluid in the conduit 170 opens a check valve 172 and hydraulic fluid is forced out of the cylinder space 36 via the valve 172, a non-return valve 174, the solenoid valve 154 and the conduit 144 into the reservoir 122. The clamp-up member is thus fully raised to release the rotor 18 for transverse removal from the machine.
In order to replace a serviced rotor 18, the rotor is wheeled into position on the trolley 102. The sensor 160 detects that the rotor is in place. The motor 121 is started. Solenoid valve 146 and solenoid valve 150 are moved to their second positions to select light fluid-pressure-holding of the rotor. Hydraulic fluid under pressure flows via a pressure reducing valve 180 and the solenoid valve 150 into the cylinder space 36 to lower the clamp-up member 34 to enter its bos 110 into the recess 114 of the rotor and steady the rotor in its trolley supported position. After a time interval, solenoid valve 158 is adjusted to its third position and hydraulic fluid flows via the conduit 160 and non-return valve 162 into the cylinder space 50, thereby jacking up the rotor on the jack 46. Hydraulic fluid is forced out of the cylinder space 36 via the solenoid valve 150, pressure reducing valve 164, solenoid valve 146 and conduit 144, back into the reservoir 122. Solenoid valve 158 moves to its second position to lock the jack 46 in its raised position. The trolley 102 is then removed. Next, solenoid valve 158 is adjusted into its first position, thus releasing hydraulic fluid from the cylinder space 50 for return to the reservoir 122. The jack 46 is lowered under the weight of the rotor. Solenoid valve 128 is moved to its first position and hydraulic fluid flows via the check valve 134 and conduit 142 into the cylinder spaces 90 and 82 to lower the clamp pin head 86 and extend the clamp pins 80 into their clamping positions in which they clamp the cam plate 78 to the cabinet top 12. Hydraulic fluid returns from the cylinder spaces 91 and 88 via the conduit 137 and solenoid valve 128 to the reservoir 122. The hydraulic fluid from the cylinder space 91 flows via the flow restrictor 132 to reduce the speed at which the clamp pin head 186 is engaged. A pressure switch 184 changes over when the pressure in the conduit 142 reaches a predetermined value so as to signal when the cam plate 78 has been clamped in position by the clamp pins 80 and the clamp pin head 82. Solenoid valve 154 is next to its first position to allow pressure fluid to flow via the pressure reducing valve 186 and the check valve 172 into the cylinder space 36 to increase the holding force of the clamp-up member 34. The pressure in the cylinder space 36 is sensed by the pressure switch 190 which changes over to signal when the pressure reaches a predetermined higher value at which the rotor is firmly clamped in place for tablet manufacturing. Solenoid valve 128 is then returned to its second position to maintain the pressure in the turret clamp cylinder 36 at the higher value, whilst allowing the motor 121 to be switched off and the hydraulic pump 120 stopped until rotor removal and replacement is again required.
Although the present invention has been described with reference to a preferred embodiment, modifications may be made by those skilled in the art without departing from the scope and spirit of the present invention as defined by the appended claims.
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A tablet making machine of the kind including a rotor having a die table carrying dies and opposed pairs of punches which operate in the dies, under the control of fixed position cams to form tablets in the dies is described. The rotor is carried by bearings mounted on an intermediate axially extending portion of a spindle fixed on the machine frame at its opposite ends. The rotor is made removable from the machine together with the intermediate spindle portion and the rotor bearings for replacement by a separately serviced rotor. In this fashion, downtime is reduced for tool and product changeover.
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This invention relates generally to the fastening art and more particularly to improvements in tooling attachments useful with robotic machining centers for the purpose of automating the assembly and integration of parts by means of rivets or similar fasteners.
Under modern day manufacturing technology, computer controlled high speed mobile machining centers or "robots", equipped with one or more drive spindles capable of selected spacial positioning and adapted to receive various machine tools, have gained popular acceptance for carrying out a variety of automatic machining operations.
In certain limited instances, such robots have been adapted to riveting procedures wherein a single robot working over one side of fixture held work pieces performs the successive functions of hole preparation, rivet insertion and installation at each rivet location before proceeding to the next rivet location. So far this application of robotic rivet installation has been limited to the installation of blind rivets.
In a prior U.S. application Ser. No. 07/183,697, filed July 7, 1988, now U.S. Pat. No. 4,885,836, issued Dec. 12, 1989 and owned by the assignee hereof, apparatus for automatically carrying out riveting procedures utilizing two robots working in mirror relationship on opposite sides of fixture held assembly parts is disclosed. In the riveting procedure described therein the robots first prepare all rivet holes at successive locations and thereafter return to each such location for insertion and installation of rivets or other type of fasteners.
BRIEF SUMMARY OF INVENTION
The present invention constitutes an improvement over prior known robotic fastener tooling applications and procedures in that it presents a single end effector attachment for the mobile working head of a robot which adapts a single robotic machining center to drive a pair of cooperating spaced tool heads. In accordance with this invention a pair of tool heads, operationally disposed on opposite sides of fixture held parts to be assembled are maintained in aligned relationship so that they may work in tandem to accomplish hole preparation, fastener insertion and installation operations at selected locations of the parts to be assembled. In a preferred form of the end effector, two tool heads are interconnected by a generally U-shaped yoke or frame and are so arranged that the tooling carried thereby serves to tightly clamp the assembly parts at each hole location without overstressing the parts and the fixture holding the same. Each tool head preferably carries multiple tool drivers, each acceptable of selected tools for hole preparation and fastener installation, such as drills, hammers, bucking bars, deburring and reaming tools and the like. Since the tool drivers are adapted to accept a multiplicity of various tooling, this invention provides a highly flexible capability for installing a variety of fasteners, such as solid metal rivets, lock bolts, both pull and stump type, and the like at each hole location. The tooling arrangement is such that each hole may be formed and prepared for fastener installation and the latter function carried out at each position of the end effector. Alternatively all holes to be formed in the assembly parts may be prepared in succession and the robotically controlled end effector and tool heads subsequently relocated opposite each preceding hole for subsequent installation of the selected fasteners.
It is a particular object of this invention to provide an improved end effector attachment for the mobile head of a robotic machining center.
Another important object of this invention is to provide an improved end effector for use with the mobile head of a robot which presents two aligned spaced tool heads, operable on opposite sides of assembly parts, each of which carries one or more tool driving means.
Still another important object of this invention is to provide a new and improved end effector for the mobile head of a robot which provides a pair of separated tool heads powered and controlled by the robot and capable of working on opposite sides or faces of intervening work piece with the spaced tool heads being capable of performing independent and simultaneous operations.
Another important object of this invention is to provide an improved end effector attachable to the working head of a computer controlled robot which permits a single robot to carry out selected operations on opposite sides of stationary work pieces to be assembled.
Still another object of this invention is to provide an improved end effector for attachment to the working head of a computer controlled robot which provides a pair of spaced coaxially aligned tool heads, each having a multiplicity of selectively positioned tool drivers for operating selected tooling.
Another important object of this invention is to provide an end effector of the order set out in the immediately preceding object which is attachable to the working head of a single robot and is capable of driving and managing spaced tool heads carried by an intervening frame; each tool head having a multiplicity of individual tool drivers and means for selectively positioning the same.
Having described this invention, the above and further objects, features and advantages thereof will be apparent to those of skill in the art from the following detailed description of a preferred embodiment of the invention illustrated in the accompanying drawings and representing the best mode presently contemplated for enabling those of skill in the art to carry out and practice this invention.
IN THE DRAWINGS
FIG. 1 is a schematic representation of a work cell and robot equipped with an end effector according to this invention;
FIG. 2 is a schematic illustration of a computer control system for the work cell and robot of FIG. 1;
FIG. 3 is a front elevation of an end effector of this invention positioned for interconnection with a robot;
FIG. 4 is a partial perspective view of the end effector shown in FIG. 3;
FIG. 5 is a front elevation, with parts in section, of the end effector of FIG. 3;
FIG. 6 is a partial enlarged end elevation thereof, taken substantially from vantage line 6--6 of FIG. 5;
FIG. 7 is a top plan thereof with portions broken away in section;
FIG. 8 is an enlarged cross-sectional view with parts in elevation of a modified end effector embodying a pivotally mounted tool head;
FIG. 9 is a schematic diagram illustrating the operational cycle of a typical arrangement of multiple tool drivers and tools in the end effector of this invention; and
FIGS. 10-15 are partial elevations schematically depicting successive steps of installing a rivet with the end effector hereof.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Before describing the details of the improved end effector according to this invention, initial consideration will be given to the general characteristics of a preferred working environment in which to practice this invention.
It is to be noted that the illustrative embodiments of this invention described hereinafter are related to the production and assembly of components and parts utilized in the aircraft industry in which large, relatively heavy structures of complex shape, such as wing and fuselage sections are involved. Those familiar with this art, however, will readily recognize other fields of use and application for this invention.
In general, an end effector according to this invention is best used in a work cell environment in which one or more computer controlled robotic machining centers, or robots, capable of imparting multi-axis linear and rotational movements to the end effector hereof may be employed. Typifying this environment is the work cell illustrated in FIG. 1 of the drawings which comprises a high speed machining center or robot designated R 1 mounted to move along a pair of parallel elongated horizontal tracks or railways 20, 20 in response to actuation of power driven rack and pinion drive means or the like (not shown). The illustrated robot R 1 is of Cartesian structure having linear, horizontal, vertical and transverse X, Y and Z axes of movement; the X axis being defined by the associated horizontal, linear ways 20, 20; the Y axis being defined by a central, vertical column 21 of the machine and the Z axis by a transversely related linearly moveable extensible ram 22. An articulated wrist or twist head 23 is disposed at the outer end of ram 22 and comprises a pair of transverse rotary axes A and C. Column 21 is likewise rotatable about its vertical axis to defined a third rotary axis B.
Located opposite the robot R 1 is an automatic flexible or adjustable fixture (F) for holding the assembly of parts and components, such as wing panels and ribs, indicated generally at 25 in FIG. 1. Fixture (F) preferably is mounted parallel to the X axis of robot R 1 .
The twist head 23 normally has a rotatable machining spindle designed to carry working tools via tapered connections (not shown), but which is not used with the end effector hereof. The robot embodies various power supplies and specific performance features required for machine operations to be performed in the cell.
The robot may be equipped with a stationary rivet feed station and automatic magazines for storing various end effectors attachable to its head 23. If such a stationary arrangement is used the same may be located conveniently at one or both ends of the robot's X axis of movement. Alternatively, mobile magazines of the order taught in U.S. Pat. No. 4,344,221 of Aug. 17, 1982, for example, may be employed to resupply tools, end effectors and fasteners to the robot in accordance with the computer controlled requirements for a particular assembly.
As indicated in FIG. 2, the work cell is importantly controlled by a host computer which receives computer aided manufacturing (CAD/CAM) instructions, via direct numeric control (DNC) or other means as well as operator controlled instructions which determine and or modify the design of the end assembly. All output signals are sent from the host computer to pertinent lower level computers in direct command control of the robot. As the instructions are performed, feedback signals are returned by the sub-level computers to the host computer.
By way of illustration, the host computer instructs the tool room management computer (TRM) which determines the selection and supply of tools and end effectors to enable the robot to find and acquire the required tools or end effector in correct pick-up positions. The tool room computer (TRM) also updates the use history and other data files for each end effector and tool. When mobile magazines are used then the TRM computer controls the management thereof as well.
Rivet feed computers (RFC) control the rivet feed stations (RFS), for selecting and controlling the exact type of fastener to be sent to the end effector's fastening tools during the fastening operation.
A continuous numeric control computer (CNC) feeds appropriate signals to the robot R 1 to move the same on its axes whereby to position the tools and end effector correctly inside of the work envelope.
The end effector control computer (EEC), on receipt of a start signal command, manages the appropriate sequence of movements of the robot and end effector operation including hole preparation, clamping, inspection, inserting and upsetting of the fasteners as well as other desired operations.
A fixture control computer positions all clamps of the fixture (F) according to the geometry of the parts to be assembled and also controls fixture configuration used for and during a particular assembly.
Robotic machine tool centers capable of carrying out the above and other tasks required by this invention are commercially available, such as an upright robotic machining center of the order illustrated in FIG. 1 or a gantry type; both types of machining centers being marketed by JOBS, Piacenza, Italy, under the name Job Mach among others.
While there are other commercial sources of machining centers capable of meeting the requirements of this invention, it is necessary that the selected robot be of rigid construction and have a capability of high accuracy in positioning the working tools. Among other features, such a machine tool center must be capable of employing different types of tool holding spindles and drivers for machining different materials, such as low RPM and high torque spindles for hard materials and high RPM spindles for composite materials. A capability of automatically changing tools and end effectors for automated and unmanned installations in conjunction with computer controls, such as the described system illustrated in FIG. 2 of the drawings, is also desirable. In the usual instance the selected robot must be capable of drilling, reaming, countersinking, milling, routing, net trimming, impacting and other machining as well as measuring and inspection operations, while rigidly supporting a variety of end effectors and, in this instance, the end effector of this invention.
In conjunction with the aforenoted features, the selected robot should be equipped with a probe which finds the exact location of the work pieces. If this position differs from the theoretical program position, it should produce accommodating alterations of the host computer program to adjust to the new position in order to avoid the necessity of locating the work pieces in a precise theoretical position as preconceived by the computer program.
In a similar vein, part adjustment capability of the robot is also required in order to adjust the part program according to the geometrical characteristics of the parts where these may differ from theoretical characteristics. Thus, if a drilling operation is required in the middle of two assigned points, the machine must automatically locate such points and calculate what the position of the required hole should be and thereafter perform the necessary operation at a new substitute position.
Thermal variations in working environment also may cause dimensional variations in the work pieces and structure of the machine. Thus the robot should be capable of compensating for these and other variations by modifying the part program accordingly.
In any event, regardless of the particular robot selected it is essential that the same provide a rigid support for the end effector of this invention, as well as the appropriate pneumatic, hydraulic and electrical power supplies necessary for driving the tooling carried by the end effector for the purpose of installing fasteners or performing other operations in the fixture held assembly parts.
Turning now to the features of the illustrated preferred embodiment of the present invention, specific reference is made to FIGS. 3-7 of the drawings.
As shown in FIG. 3 an end effector in accordance with this invention, indicated generally at 30, comprises a master head 31 with attached interface bell 32 and a slave head 33. The two heads 31 an 33 are aligned coaxially in opposing spaced relationship and are interjoined by an intervening substantially inverted U-shaped yoke 34 which, while hollow, is of rigid construction, preferably made of light weight material such as cast aluminum or the like.
In FIG. 3 of the drawings end effector 30 is shown positioned on pedestals or like under supports in position for automatic engagement with the twist head 23 of the robot. For this purpose the interface bell 32 comprises a face plate 35 for connection with the twist head by means of an automatic coupling system which includes plural guide/locking pins 36, 36 that lock-up with plate means 35 according to known practice.
The interface bell 32 in addition to the locking system for cooperation with the twist head of the robot, also comprises a power console section 38 which automatically interconnects with appropriate pneumatic, hydraulic and electrical power connections associated with the robot.
Adjoining the interface bell is a main body 39 of the master head 31 which supports a first shuttle means 40, a plurality of tool drivers 41 and drive means 42 for translating the shuttle 40 laterally of the head 31 for purposes of aligning selected drivers 41 coaxially of a nose piece 43.
The nose piece as shown herein is of general frusto-conical formation having an extending hollow cylindrical foot bush section 44 at its apex end through which tools 45 carried by a driver 41 are moved in operation. The outer end of the foot bush 44 carries a swivel mounted contact piece 46 which, within limits, can conform to the plane of contact with a work piece. A pressure responsive sensor 47 is mounted at the outer end of contact piece 46 for signaling the robot when contact has been made with the skin or surface of an opposing work piece, preliminary to initiation of a working operation. It will be noted that the nose piece 43 is coupled to the main body of the head 31 in a manner to be described presently. Preferably intervening flexible dust bellows 48 are employed between the nose piece and body of head 31 to prevent the entry of dust, chips and like impurities into the interior of the nose piece.
The slave head 33 is substantially a duplicate of the master head 31 with the exception that it does not include the interface bell 32 or power console 38. Consequently further detailed description thereof is not deemed necessary herein.
Briefly, however, slave head 33 includes a main a body 49, shuttle means 50 for carrying plural tool drivers 51, drive means 52 for driving the shuttle; and a nose piece 53 with foot bush 54, contact piece 56 and sensor 57. A dust cover or bellows 58 preferably extends between nose piece 53 and body 49 of the slave head.
It should be noted that it is fully contemplated that the shuttles 40 and 50 may move vertically with equal facility as opposed to the herein illustrated embodiment, if desired.
The yoke 34, as illustrated herein, comprises a substantially inverted U-shaped support member formed preferably as a rigid fabricated or cast structure of light weight material, such as aluminum or magnesium steel, and is appropriately hollow to carry required power supplies to the slave head 33. It is to be understood that while the yoke 34 is herein illustrated to be of generally symmetrical configuration, the particular shape of the yoke may be widely varied and custom fit to dedicate it to the shape of a particular assembly encountered by the end effector 30. For example, the throat of the illustrated yoke assembly 34 can be considerably elongated from that illustrated to accommodate positioning of the two working heads 31 and 33 over a greater work area of the assembled parts. In a like manner, the inverted U configuration may be asymmetrical with the downwardly extending arms of the U being curved, inclined or custom shaped to accommodate the particular shape of the parts assembly. Other configurations will be apparent to those with skill in this art.
With reference to FIG. 4 of the drawings the shuttles 40 and 50 associated with the master and slave heads 31 and 33, respectively, are shown in perspective and constitute substantially rectangular parallelopiped metal blocks having a plurality of cylindrical sockets 60 opening inwardly of one front face 61 thereof for slidably receiving the tool drivers 41 and 51, as the case may be. It will be noted that the drivers 41 and 51 are disposed in coaxially opposed position on opposite sides of the open throat formed by the spaced arms of the inverted U-shaped yoke 34. In addition the upper face or wall 62 of each of the shuttle members 40 and 50 is provided with parallel rails 63, 63 extending along the upper lateral margins thereof. Such rails are formed with a semi-circular depression or groove 64 receptive of race held ball bearing means 65, 65 which ride in the grooves 64 and vertically support the shuttle member in its translating movements laterally of an associated head 40 or 50. In addition to the rails 63 a rack member 66 is fastened along one upper side margin of the each of the shuttle members for engagement with a driving gear 67 engaged by motor driven pinion 68. As shown best in FIG. 5 each pinion 68 is driven by an electrical motor means 70 which is periodically energized according to the dictates of computer control signals for translating the shuttles. In this manner a selected pair of tool drivers 41 and 51 may be positioned in desired locations for interactive cooperation during the hole forming, preparation and fastener application functions.
In the particular instance illustrated herein, each of the shuttles 40 and 50 carries three drivers 41 or 51, which pass laterally through aligned cut away openings 73 and 74 in the nose pieces 43 and 53, respectively. When positioned for operation, two of the drivers 41 and 51 are aligned coaxially with their associated nose pieces 43 and 53 so that the tooling carried thereby may operate coaxially through the foot bushes 44 and 54.
Interconnection of the nose pieces with the main bodies of the master and slave heads will best be understood with reference to FIGS. 5-7 of the drawings. By way of illustration, the nose piece 43 associated with master head 31, for example, comprises a planar base plate 80 which is formed in two sections 80 and 80a, one above and one beneath the lateral openings 73 which permit lateral passage of the power driven tool drivers 51. (See FIG. 4 also). This bifurcated base plate, which is located at the larger or base end of the fustro conical body 81 for the nose piece 43, is positively coupled to the outer ends of the plurality of piston rods 82 extending from cylindrical pistons 83 located in suitable cylindrical piston chambers 84 formed within the body 39 of the master head. (See FIGS. 5-7). As illustrated there are a total of six such piston and cylinder actuators, three located in the upper regions of the master head body 39 and three in the lower regions thereof. It is to be noted that the cylinder and piston assemblies in each bank, that is the upper and lower banks thereof, are in coplanar alignment and that the outer end of each of the piston rods 82 is fixed, as by welding, rigidly to the base plate 80 of the nose piece.
It also will be appreciated that the nose piece attachment structure associated with the slave head nose piece 53 is identical to that described above and comprises six cylinder and piston assemblies, indicated by like numbers, as described for nose piece 43. The cylinder and piston assemblies attached to the respective nose pieces 43 and 53 are supplied with appropriate pneumatic or hydraulic fluid to drive the pistons 83 coaxially of the cylinder chambers 84 whereby to advance and retract the nose pieces 43 and 53 for purposes which will be described more fully hereinafter.
As illustrated in FIG. 7 of the drawings, the nose pieces 43 and 53 are disposed in a retracted or home position and are held there by hydraulic or pneumatic forces acting against the actuating pistons 83 therefore until it is desired to advance the nose pieces during operation of the end effector in accordance with appropriate control signals from the end effector computer. Appropriate porting and supply passageways (not shown) are provided in the bodies of the master and slave heads to activate the pistons 83 in accordance with conventional hydraulic or pneumatic practice.
In addition to the actuators for driving the nose pieces of the master and slave heads as above related, each of the heads also embodies means for advancing and retracting the tool drivers. To that end, reference is made to FIGS. 6 and 7 from which it will be recognized that the shuttle members 40 and 50 are provided with internal piston and cylinder assemblies 90 comprising cylinders 91, pistons 92 and piston rods 93 located internally of the body of the shuttle and located near the lower sides thereof. The piston rods 93 extend outwardly of the front or forward face 61 of the shuttle blocks where each is joined or fixed to one end of an actuating arm member 95 fixed to an adjacent tool driver 41 or 51 as the case may be. (See FIG. 7). Again the assemblies 90 are actuated by hydraulic or pneumatic forces fed to passageway in the shuttles by an appropriate flexible umbilical coupled to a source of such power located in the robot and transferred to the shuttle through the power console 38 as will appear presently. It will be understood that each of the actuators 41 associated with the master head, for example, is coupled to an arm 95 powered by the associated piston and cylinder assembly 90 so that movement of the piston in one direction serves to advance a tool driver 41 forwardly or toward a work piece located between the master and slave heads in operation and conversely to retract the same to a home position as illustrated in FIGS. 5 and 7 in particular. Inasmuch as there are three drivers 41 in the master head assembly, there are three such assemblies 90 associated with the master shuttle 40. In a similar fashion three drivers associated with the slave head are actuated by corresponding actuator means 90 as shown in FIG. 5 and so will not be described further herein since they are identical to the actuator assemblies associated with the master head described above.
With reference now to FIG. 8 of the drawings, a modified slave head assembly 100 is therein illustrated, mounted at the lower end of the yoke arm. Assembly 100 comprises a main body 101 carrying a slidably moveable shuttle member 102 for housing a plurality of tool drivers 103 moveable laterally of body 101 by actuation of a motorized drive means 104, identical to the drive means 42 and 52 heretofore described and comprising a motor driven pinion, gear and rack train as before described. A frusto-conical nose piece 105 is mounted at one end of body 101 and includes a foot bush 106 and contact piece 107 with sensor 108 all as in the nose piece 53 of FIG. 3. Plural hydraulic or pneumatically powered actuator means 110 are provided, each comprising a cylinder 111, piston 112 and piston rod 113. Such assemblies are mounted within the body 101 and fixed to one end of the nose piece 105 to advance and retract the latter in the manner heretofore described.
The tool drivers 103 are mounted in cylindrical sockets 115 extending inwardly of the outer face of the shuttle member 102 and comprise a fixed body portion 116 held in bearing means 117 near the inner end of each socket 115. Secondary bearing means 118 adjacent the outer end of each socket support moveable cylindrical body 120 which moves coaxially over the fixed body portion 116 in operation. Advancing and retracting movements of the tool driver coaxially of the nose piece takes place in response to hydraulic actuator assemblies (not shown) identical to the actuator assemblies 90 heretofore described and shown in FIGS. 6 and 7 of the drawings.
Lateral movements of the shuttle member 102 are brought about by the drive means 104, as above noted. To that end the shuttle member is suspended on rails 122 attached to the upper lateral margins thereof and cooperating with, in this case, thrust bearing assemblies 123 as opposed to the roller bearing assembly 65 described heretofore in association with the shuttles 40 and 50.
The principle departure of the modified slave head assembly 100 of FIG. 8 over the slave head 33 of FIG. 4, for example, resides in the provision of means for pivotally moving the slave head relative to the yoke, as is necessary when mounting the end effector over certain fixture held parts, such as, parts assembly 125, which may require greater clearance between the master and slave heads than is possible in the fixed slave head assembly incorporated in the end effector of FIGS. 1-7 of the drawings. To this end, it will be noted that a hydraulic actuated ram assembly 130 is pivotally anchored at one end to a mounting ear 131 projecting from the outer side of the yoke 34. Moveable piston rod 132 of assembly 130 is pivotally joined to a crank arm 133 fixed, as by key means to a shaft 134 extending between rearwardly projecting supports extending from opposite sides of the yoke 34 adjacent the upper end of the slave assembly body 101. Thus, when the piston rod 132 is extended, in the manner illustrated in FIG. 8, the slave head 100 is held in its operating position against the yoke 34 as therein illustrated. On the other hand, retraction of the piston rod 132 serves to pivotally swing the slave head assembly downwardly through an arc as indicated in FIG. 8 to dispose the outer end of the nose piece in a depending state from that illustrated in FIG. 8 so that it may clear a fixture held assembly in mounting end effector thereover. Once the end effector is positioned over the work pieces 125, the slave head assembly 100 is then returned to its working position as illustrated in FIG. 8, being held in such position by the by the ram assembly 130 or a locking device.
THE USE AND OPERATION
It will be recalled that each of the master and slave heads in the herein illustrated case carry three independent tool drivers which are readily adapted for accommodating different tools for performing selected functions. By way of illustration, FIG. 9 of the drawings schematically sets forth a typical arrangement of the master and slave head tooling accommodated by the multiple drivers mounted therein. As there set forth, the functions performed by the tools carried by the master head are indicated at 1A, 2A and 3A as comprising, in this instance, a drill at 1A, a sealant applicator at 2A and a rivet setting hammer at 3A. The opposing respective tools in the slave head comprise a reaming tool at 1B, an inspection probe in driver 2B and a bucking bar in tool driver 3B. With this particular arrangement the cycle of operation as indicated in FIG. 9 is as follows: the drill in driver 1A is utilized to a form hole through the fixture held parts assembly followed by the activity of the slave head driver 1B which reams the hole formed by the drill in the driver 1A. Driver 2B is then positioned opposite the previously formed hole and an inspection probe inspects the hole for roundness and other factors, as desired. Thereafter driver 2A positioned opposite the drilled hole advances a sealant applying tool which applies sealant adjacent the hole. The rivet setting hammer in driver 3A is then disposed opposite the drilled and reamed hole and a rivet previously fed to the nose piece of the master head is then inserted into the hole and the held in place by the hammer in tool driver 3A awaiting positioning of the bucking bar held in the tool driver 3B of the slave head. Operation of the hammer and bucking bar serve to cooperatively set the rivet and fasten the parts together.
It will be understood from FIG. 9 that depending on the selection of the particular tooling held by the various drivers of the master and slave heads, a wide variety of operations may be carried out as desired for hole preparation and insertion of selected fasteners. It is further to be recognized that the present invention is not to be limited to the formation of holes and installation of fasteners, but is obviously capable of carrying out other machining operations and functions as well such as using an end mill to trim the edges or cut openings through the work pieces.
By way of further illustration of the functioning of the improved end effector of this invention for purposes of rivet setting, references is now made to the schematic illustrations of FIGS. 10-15 of the drawings which illustrate a typical rivet installation and upsetting operation.
FIG. 10 demonstrates hole selection and alignment of the two working heads and more particularly the foot bush portions of the nose pieces thereof on opposite sides of intervening fixture held work pieces.
FIG. 11 demonstrates the initial engagement on one side of the assembly parts by the foot bush of the master head with predetermined force as dictated by the sensor means at the outer end of the foot bush and predetermined values for such engagement force as specified by the controlling computer program.
FIG. 12 illustrates the coaxial alignment of the foot bush portions of the master and slave nose pieces on opposite sides o the parts assembly and the clamping engagement of the assembled work parts by the end effector of the slave head with predetermined clamping force. Note that a rivet has been fed in advance of a hammer tool carried by the master head.
FIG. 13 demonstrates the insertion of the rivet into the previously formed opening by advancing the hammer tool of the master head.
FIG. 14 shows the positioning of the bucking bar tool carried by the slave head in opposing alignment with the hammer tool for upsetting the rivet therebetween; and
FIG. 15 demonstrates the completed installation of the rivet after operation of the hammer tool and bucking bar.
It will be appreciated that the schematic illustration of FIGS. 10-15 corresponds to the tooling arrangement set forth in FIG. 9 of the drawings.
In view of the foregoing it is believed that those familiar with the art will readily understand and appreciate the novel advancement presented by this invention and will readily recognize that while the same has been described largely in association with its utilization in the aircraft industry, its teachings and concepts are equally applicable to other fields and areas of operation. Additionally while the invention hereof has been set forth in association with particular tools and working apparatus along with particular preferred and modified embodiments thereof, illustrated in the drawings, it is to be understood that such described embodiments are susceptible to variation, modification and substitution of equivalents without departing from the spirit and scope of the invention which is intended to be unlimited by the foregoing except as may appear in the following appended claims.
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A multiple-task end effector attachment for the articulated head of a computer controlled robotic machining center capable of imparting multi-axis linear and rotational movements to the end effector which comprises opposingly aligned master and slave related tool heads that carry multiple tool drivers receptive of selectively changeable tooling. The tool heads are interjoined and rigidly supported in opposing alignment on opposite sides of fixture held stationary work pieces by means of an intervening generally U-shaped yoke or frame of selected configuration dedicated to the particular shape of the parts assembly. The master tool head of the end effector is connected directly to and carried by the mobile head of the robot which powers and controls the positioning and operation of both tool heads of the end effector. The tool heads operationally cooperate in slave relationship to clamp the parts therebetween and form and prepare holes through the work pieces at predetermined locations followed by the installation of selected fasteners such as rivets, bolts and the like. This arrangement enables a single robot to operate multiple tool heads on opposite sides of stationary work pieces.
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CROSS-REFERENCE TO RELATED APPLICATIONS
The following applications are related to each other:
U.S. Pat. application Ser. No. 607,002, filed Aug. 22, 1975, entitled "Multioriented Composite-Surface Tape Guide for Use in a Cassette," by Douglass L. Blanding; U.S. Pat. application Ser. No. 606,994, filed Aug. 22, 1975, entitled "Yieldable, Coaxially-Driven Tape Wrapping Guides for Use in a Helical Tape Recorder," by Douglass L. Blanding; U.S. Pat. application Ser. No. 606,995, filed Aug. 22, 1975, entitled "Rotatable Multifaceted Tape Guide for Use in a Cassette," by Thomas G. Kirn.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to apparatus for guiding a tape through one, or another, tape path in a tape recorder; more particularly, the invention is concerned with guides mounted in a coaxial-reel tape cassette, for guiding magnetic tape selectively through different tape paths, including one path which is so disposed in the tape recorder that a television signal train may be helically recorded on the tape. (As used herein, the term "recorder" shall be taken to mean apparatus which either plays back or records a video signal.)
2. Description Relative to the Prior Art
While not so restricted, the invention acquires a special significance when it is used to guide magnetic tape contained in a coaxial-reel cassette toward and away from a helical recording drum in a video tape recorder. Coaxial-reel cassettes are particularly well adapted for use with video recorders, which generally tend to be bulky, since cassette takeup and supply reels are rotated on the same axis. As is usual, coaxial-reel cassettes will have a pair of inclined or tapered guide posts which are so oriented as to take up the change in the tape level between the reels when the tape, fully contained in the cassette, passes directly from one reel to the other.
For helical recording, the tape is initially pulled from the cassette and wrapped around the recording drum at a helix angle. In addition, the helical recording format requires precise positioning of the span of tape which passes around the drum; positioning errors may cause, for example, mistracking during playback. Tracking problems are diminished, however, if the tape follows a precise path into, around, and out of the drum assembly. In one video recorder configuration, the paths into and out of the drum are horizontal and substantially in the same plane as the supply and takeup reels, respectively. The last post before the tape touches the drum and the first post after the tape leaves the drum are designed to change the tape's horizontal level a few degrees so as to dispose the tape properly to form a helix around the drum.
These factors suggest the use of the coaxial-reel cassette with the helical drum assembly; however, this combination is hampered significantly because the tape presented to the helical drum is last touched within the cassette by the inclined or tapered guide posts. What this means is that the last guide surfaces within the cassette will tend to force the tape into an inclined path which is not suitable for presentment to the drum assembly and its associated guides. On the other hand, the tape still needs to be positively guided to the vicinity of the drum at the correct height for proper helical scanning. In an attempt to meet this problem, copending U.S. patent application Ser. No. 606,995, in the name of Thomas G. Kirn, filed concurrently with and assigned to the same assignee as the present application, provides a rotatable guide, for use within a coaxial-reel cassette, having right circular conical and cylindrical surfaces on opposite sides thereof. By providing such a guide, with appropriate selective orientation, a tape may be translated directly between the reels by means of the conical surface, or guidedly directed to and from a recording drum, about which it helically wraps, by means of the cylindrical surface. Although the cylindrical surface will suitably direct the tape to the drum assembly, the upright conical surface still contributes undesirable stress differentials and distorts the tape as it passes thereabout from one coaxial level to the other.
Further refining this approach, copending U.S. patent application Ser. No. 607,002, in the name of Douglass L. Blanding, filed concurrently with and assigned to the same assignee as the present application, provides a guide for use within a coaxial-reel cassette, having composite conical and cylindrical surfaces. By obliquely orienting the conical surface with respect to the cylindrical surface, their composite juncture presents a smooth, continuous guiding surface. Such a guide translates the tape free of distortion directly between the reels by means of the cylindrical and conical surfaces together, or guidedly directs the tape to or from the recording drum, about which it helically wraps, by means of the cylindrical surface alone. When the latter path is so directed to the drum that the tape cannot clear the conical surface, the post is rotated sufficiently to provide such clearance.
Apart from the selective use of two contiguous guiding surfaces mounted within a cassette, it is known to selectively substitute a guide post mounted on the recorder for a post located in the cassette so as to achieve selective guiding through two tape paths, e.g., U.S. Pat. No. 3,678,213. In such a substitution, a spring-biased post, located in a coaxial-reel cassette, is forced out of the tape path by a fixed post on the recorder deck when the cassette is emplaced on the recorder; therefore, two different guide posts are provided for two different paths. However, high speed winding with the tape contained in the cassette is hindered by the presence of the incorrect guide surface. Belgian Patent No. 534,063 illustrates another form of substitution, although not adapted to a cassette, in which a capstan protrudes through an angular slot in a rotatable plate mounted on a recorder. A pressure roller and a guide roll are so mounted on the plate relative to the slot that the plate may be rotated between two tape-encountering positions. In the first position, the tape is pressed against the capstan by the pressure roller to drive the tape. In the second position, with the plate rotated sufficiently that the pressure roller releases the tape from the capstan, the guide roll holds the tape away from the capstan to enable the rewinding of the tape.
Turning now to another course of development in the prior art, U.S. Pat. No. 3,790,055 (to Sims) discloses the cooperation of a capstan with a post in a cassette for quickly stopping the motion of a magnetic tape. The post, which Sims describes as a motion control device, consists of an elongated member having a central cavity within which a freely rotatable capstan fits. The member rotates from a driving position exposing the enclosed capstan to the tape through a cut-away sidewall to a braking position wherein the tape is separated from the capstan and pinched between the sidewall of the member and a resilient pressure member. A similar type of motion control device had previously been proposed in U.S. Pat. No. 2,590,665, although not in conjunction with a tape cassette. For purposes that later will become clearer, the Sims patent is of interest merely because it shows a situation in which a capstan may cooperate with a rotatable element in a cassette.
SUMMARY OF THE INVENTION
Recognizing the desirability of minimizing the number of tape-contacting surfaces in a recorder and, particularly, of combining the functions of several tape-contacting posts so as to reduce the overall size of the recorder, the invention initially proposes the hollowing out of a composite guide of the type disclosed in the earlier mentioned copending application Ser. No. 607,002, to Blanding. The central cavity thereby formed is so disposed as to receive the shaft of a capstan, protruding from the recorder deck, when the cassette is emplaced on the recorder. In addition, a side of the post, corresponding to the cylindrical surface disclosed by Blanding, is removed so that the capstan is exposed through the resulting cutaway. When the tape is contained within the cassette and passes directly between the levels of the coaxial reels, the conical surface is presented to the tape for accommodating the level change. When the tape is withdrawn from the cassette in conjunction with the rotation of the post, the cutaway side is presented to the tape so that the tape rides up against the capstan disposed therein. Therefore, by means of the hollowed-out post, the capstan may doubly perform, first, as the driving element when a pinch roll forces the tape into driving engagement with the rotating capstan, and, second, as the cylindrical surface disclosed by Blanding for directing the tape toward a helical recording drum.
In another aspect of the invention, by providing a cylindrical surface contiguous to the conical surface, the tape is more carefully directed from the reel to the conical surface when the tape passes directly between the reels. In addition, the cylindrical surface is provided with at least one flange for defining the path of the tape around the surface. When the tape is withdrawn from the cassette, the post is rotated sufficiently such that both surfaces clear the tape. In yet another aspect, by providing an aperture in the bottom of the cassette, a precision edge guide mounted on the recorder may be adapted to enter the cassette through the aperture when the cassette is emplaced on the recorder. The guide is so disposed on the recorder as to contact the tape and precisely define the path of the tape after the post is rotated and the tape has fallen onto the capstan.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described with reference to the figures, wherein:
FIGS. 1 and 2 are top views illustrating two modes of a presently preferred embodiment of the invention;
FIG. 3 is a perspective cross-sectional view taken generally along line 3--3 in FIG. 1;
FIGS. 4 and 5 are side and front elevation views of the rotatable guide of the invention as shown in FIG. 1;
FIG. 6 shows in solid line the relationship of the rack, pinch roll, and rotatable guide as illustrated in FIG. 2 and in dotted line the same relationship as illustrated in FIG. 1; and
FIG. 7 is a cross-sectional view taken generally along line 7--7 in FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Because helical tape recorders are well known, the present description will be directed in particular to elements forming part of, or cooperating more directly with, the present invention. Recorder elements not specifically shown or described may take various forms well known to those skilled in the art.
Referring specifically to FIG. 1, there are shown the parts of a helical video recorder which are sufficient for an understanding of the present invention. A helical tape recorder 2 is provided for use with a coaxial-reel cassette 4. A supply reel 6 is coaxially disposed at a first level in the cassette 4 with respect to a takeup reel 8 at a second level. To facilitate understanding, the reels 6 and 8 are shown with different diameters in FIGS. 1 and 2, although this will ordinarily not be the case. The respective arrangement of the reels is illustrated in FIG. 3. Each reel 6 and 8 is mounted in the cassette 4 for rotation around a common axis 10. A magnetic tape 12 leaves the supply reel 6 and passes around guide posts 14, 15, and 16 during the course of its travel to the takeup reel 8. As better shown in FIGS. 4 and 5, the guide 15 has two tape-contacting guide surfaces formed thereon; a conical surface 18 formed from a section of a frustum of an oblique circular cone and a cylindrical surface 20 formed from a section of a right circular cylinder. The conical surface 18 has an axis 22 obliquely directed both with respect to the axis of the cylindrical surface 20 and the axis 10 of the coaxial reels 6 and 8. The cylindrical surface 20 is disposed on the guide post 15 at the level of the supply reel 6. Furthermore, the tape 12 is introduced to the conical surface 18 such that it is tangent to the conical surface 18 along a line 26. The significance of this orientation is that the plane and direction of travel of the tape 12 is changed as it passes around the conical surface 18 without incurring a distribution of stress differentials on the tape 12. Thus, while the angle of incline of the tape 12 is changed, as is necessary, the tape 12 still enters and exits from the conical surface 18 in a vertical plane. The cone from which conical surface 18 is taken, shown in broken lines, has an apex 28 which points generally toward the level of the takeup reel 8. The cylindrical surface 20 is provided with flanges 30 which are spaced apart a distance equivalent to the width of the tape 12. The flanges 30, though formed on the cylindrical part of the guide 15, prevent lateral wandering of the tape 12 while the tape 12 rides across the conical surface 18.
As shown in FIGS. 3 through 5, a pinion 24 is disposed on the post 15 for rotation about an axis 27. An interior portion 32 of the post 15 is hollowed out, as indicated by the dotted lines in FIGS. 4 and 5 and as best seen in FIG. 7. The hollowed-out interior cavity 32 is further exposed by a cut-away side generally depicted as 33. A ledge 34, as best seen in FIG. 3, is cut into the top of the post 15 and provides a channel in which a stop 36 rides. The top surface of the post 15 also receives a linkage 38 which moves in conjunction with the rotation of the post 15. The post 16 is mounted for rotation within the cassette; the other end of the linkage 38 is connected to the top surface of the post 16 for providing such rotation. A spring S, schematically depicted in FIG. 1, rotationally biases the guide post 15 so that it presents the conical surface 18 for cooperation with the tape when the cassette 4 is not within the recorder 2. The post 16 is similarly biased by the spring S by means of the linkage 38, so that it presents the conical surface 19 for cooperation with the tape.
The guide post 16 thus far described is the same as that post disclosed in the above-mentioned copending application Ser. No. 607,002, by Blanding, and reference is made to that application for a more specific description of the structure, function, and operation of the guide post. To reiterate those points sufficient for an understanding of the present invention, the post 16 includes two contiguous surfaces, a conical surface 19 and a cylindrical surface 21. The conical surface 19 is similar to the conical surface 18 on the post 15 except that it defines an apex pointing generally toward the supply reel 6 and is positioned generally at the level of the takeup reel 8.
Referring again to FIG. 1, the cassette 4 has a cut-away front face 40, hereinafter sometimes referred to as a window, which is so designed as to permit the positioning of a pair of tapered threading guides 42 and 44, also referred to as tape wrapping guides, behind the tape 12. The opening 40 is sufficiently extensive to expose the guide 15, for purposes which will be seen hereafter. The threading guides 40 and 42 are mounted on drive gearing, not specifically described but generally designated by gear assembly 46 for rotational movement around an axis 48. A recording drum 50, carrying at least one recording head (not shown), is rotatable about the axis 48. The path of the recording head is slanted with respect to the tape 12 so that helical recording may take place when the tape 12 is wrapped around the drum 50 by the movement of the guides 42 and 44 (to be later described).
A spring-biased lever 52 is provided for movement around a pivot 54 on the recorder 2. The lever 52 has a vertically extending side member 55, better shown in perspective in FIG. 3, which serves to mount a rack 56 by means of a flexible arm 58 and to support a resilient pressure roller 60, sometimes hereinafter referred to as a pinch roller. A leaf spring 62, affixed to the lever 52, is in contact with a plunger 66. The plunger 66 which is free to slide within a block 68 translates to the spring 62 the motion of a cam 70 mounted for rotation on the gear assembly 46. A return spring 67 ensures the return of the plunger 66 to the position illustrated in FIG. 1 when the cam 70 releases the plunger 66 in a manner to be hereafter described.
The cassette 4 is provided with an opening 72, as shown in FIG. 7, for allowing a capstan 74 to pass through. The capstan 74, the opening 72, and the cut-away interior portion 32 of the post 15 are so arranged that the shaft of the capstan 72 is freely received within the cut-away portion 32 when the cassette 4 is emplaced on the recorder 2, as shown variously in FIGS. 3 through 7. The cassette 4 is further provided with another opening 76 for receiving an edge guide 78 mounted on the recorder 2. Flanges 80 are provided on the edge guide 78 for directing the tape from the supply reel 6 to the capstan 74.
FIGS. 1 and 2 illustrate the two modes of operation of the presently preferred embodiment. FIG. 1 shows the apparatus in a position as depicted in perspective by FIG. 3 wherein the tape passes across the guides 15 and 16 from the supply reel 6 to the takeup reel 8. Each guide 15 and 16 presents a conical surface 18 and 19, respectively, to the tape which differ in that their apices are inversely disposed with respect to each other. In addition, the tape 12 is guided onto the conical surface 18 by the cylindrical surface 20. The flanges 30 define the edges of the path of the tape 12 across the cylindrical surface 20 and prevent edgewise wandering of the tape. In accordance with the disclosure in the above-mentioned copending application Ser. No. 607,002 by Blanding, the tape rides around the conical surface 19 on the post 16 and across the cylindrical surface 21 on its way to the takeup reel 8.
To commence the wrapping operation, the tape threading guides 42 and 44 rotate about the axis 48 along the paths 90 and 92, respectively (shown by broken lines in FIG. 1), until they reach the positions 42' and 44' (also shown by broken lines). In this position, further illustrated in FIG. 2, the tape 12 is helically wrapped around the drum 50 so that the recording head travels an oblique path across the tape 12. Another copending application Ser. No. 606,994, also in the name of Douglass L. Blanding and assigned to the same assignee as the present invention, discloses a preferred drive means for rotating the tape threading guides 36 and 38 from the unwrapped position to the wrapped position, and back again; after the wrapping and unwrapping motions are completed, a suitable switch or motor control unit disables the drive means.
The cam 70 rotates concurrently with the movement of the threading guide 44, also in the direction of the arrow 92 (FIG. 1). As the cam 70 proceeds to the position portrayed in FIG. 2, the face of the cam 70 encounters the plunger 66 and cams it through the block 68 against leaf spring 62. The spring 62 forces the lever 52 in a clockwise direction so that the rack 56 enters the open front face 40 of the cassette 4 and engages the pinion 24 on the guide post 15. The subsequent rotation of the guide post 15 in the direction of arrow 94 accomplishes several functions in the cassette 4: the post 15 is so rotated as to clear both the cylindrical surface 20 and the conical surface 18 from contact with the tape 12; simultaneously, the cut-away side 33 is moved adjacent the tape 12, revealing the capstan 74 inside, and the tape 12 falls into contact with the capstan 74. Additionally, as the tape 12 falls onto the capstan 74, it slips sideways a predetermined distance in the cassette 4 so chosen that the tape 12 now rides against the guide 78 and between the flanges 80. The linkage 38 rotates together with the post 15 and forces a similar, but counter, rotation in the post 16 until the cylindrical surface 21 is disposed adjacent the tape 12. Finally, the pinch roller 60, also supported on the lever 52 for movement toward the cassette, resiliently urges the tape 12 into driving engagement with the capstan 74. With all these interrelated movements completed, as shown in FIG. 2, recording may commence. When it is desired to draw the tape 12 back into the cassette 4, all the movements are basically reversed. Of particular mention, when the cam 70 releases the plunger 66, the lever 52 will begin to rotate in response to the torque of the return spring 67 until resuming the position depicted in FIG. 1. The guide posts 15 and 16 are simultaneously counterrotated by the retreating rack 50 and the linkage 38, respectively, until the surfaces 18 and 19 are again presented to the tape 12.
Copending application Ser. Nos. 606,994, and 607,002, both in the name of Douglass L. Blanding and assigned to the same assignee as the present invention, are incorporated herein by reference; reference is made to these applications for a more specific description of the path of the tape 12 across and through the window 40. In particular, it is noted that the plane of the tape 12 toward and away from the guides 15 and 16 is always maintained parallel to the rotation axis 10 of the coaxial reels 6 and 8 whether the tape 12 passes across the window 40 or out of the cassette 4 through the window 40.
The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
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A rotatable guide post having a conical guiding surface and a hollowed-out interior cavity is provided within a coaxial-reel cassette for cooperating with a capstan and for directing a magnetic tape along two different tape paths depending on whether the tape is wound within the cassette between the coaxial reels or is withdrawn from the cassette and wrapped around a helical recording drum. By adapting the post to freely receive a capstan into the cavity and by additionally cutting away a sidewall of the post to reveal the cavity, the capstan may be selectively exposed to the tape, and as such performs the dual function of a drive and cylindrical guide. The post, with appropriate selective orientation, translates the tape directly between the reels by means of the conical surface, or guidedly directs the tape to and from the recording drum, about which it helically wraps, by means of the cylindrical surface of the capstan.
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FIELD OF THE INVENTION
This invention relates to drilling systems for mineral exploration sampling; and more particularly to mobile drilling systems for exploration sampling,
BACKGROUND OF THE INVENTION
Exploration drilling of suspected and known mineral deposits is commonly performed in the process of locating and evaluating mineral deposits. In the course of an exploration of a given geography, it is not uncommon to lay out an extensive grid pattern of drill sites, drill hundreds to thousands of mineral-sampling holes as dictated by the grid pattern, and assay the multitude of samples obtained by the sample drilling. Then, based on the assays, overlay another grid pattern and conduct a more extensive drilling of sampling holes. Of course, a likely candidate location must be first identified, often by random, sample drilling, often called "wildcat drilling." Then the evaluation of the candidate location begins with sample drilling of a wide grid pattern to identify possible minable reserves. Then, if further exploration is warranted, sample drilling on a finer grid pattern of the proven minable reserves is conducted for mine planning.
In order to perform this extensive sample drilling, access roads and drilling sites must be located and established. The cutting of access roads and surface drill sites has a very significant impact on the ecology of the surrounding geography. Site and road preparation is costly; and, where required, returning the terrain to its original condition is also costly. This is a major undertaking. Each surface drill site, for example, must have sufficient room for the drill and drill pipe, water pumps, drill rods, drilling mud, storage containers of various types, turn around for the drill rig and other vehicles. Efforts are made, therefore, to provide mobile sample drilling systems in as compact a configuration as possible, while still being capable of meeting the sample drilling requirements.
This can pose problems in that various geological structures may require that different drilling techniques be employed; and a particular drilling rig is not necessarily capable of employing the drilling technique required at a particular site. Oftentimes, a particular exploration project will require the use of more than one drilling technique over the course of the project. Consequently, a driller must have several types of drilling rigs available in order to qualify for the drilling jobs that will become available.
SUMMARY OF THE INVENTION
The system of the present provides a mobile drilling rig that may be mounted on a track undercarriage, a rubber tired undercarriage or on a skid undercarriage. The drilling rig of this invention is not only mobile, it is adjustable for drilling sample holes at various positions around the undercarriage and at various angles with respect to the plane of the undercarriage. The drilling rig of this invention is capable of employing a variety of drilling techniques, such as rotary drilling, percussion drilling, and reverse-circulation drilling. It can recover samples from such diverse structures as rock formations requiring coring and from sands. This drilling rig is therefore capable of drilling in any kind of terrain and through any kind of geological formations that might be encountered in a mineral exploration project.
The drilling system of this invention provides a drill mast mounted on a turntable. The turntable may be mounted on any type of undercarriage or carrier. The drill mast can be positioned around the perimeter of the turntable, it can be positioned near to, or away from, the turntable. The drill mast is carried on a trunnion mounting and can be oriented along Y and Z axis' with respect to the turntable X axis for drilling angle holes. A three-way adjustable control console is provided for operator comfort, regardless of the drilling mast position. Consequently, this drilling system can operate without provision of a drill pad at the drill site. This versatility can result in less extensive, and less expensive, site preparation.
The drilling system provides a drill head with gear reduction that can be set up with two to eight high performance hydraulic motors for varied application and a variable speed rotation. The maximum rotational torque can be varied in increments, as a result, from about 9000 ft.lbs. to 18,000 ft. lbs., 27,000 ft. lbs. to 36,000 ft.lbs. The drill mast mounts the drill head for a draw works lift force of up to about 88,000 lbs.
The drill mast mounting to the turntable enables the drill mast to be transported laying down over the turn table. The system need not be dismantled for transport from project site to project site. The overall height of the drilling system in its transport mode is low enough for transport on public roadways.
In a preferred embodiment of the drilling system of this invention, a pipe joint breaker assembly is provided adjacent the lower end of the drilling mast. This assembly can accommodate different size pipe diameters.
The drilling systems of this invention is specially adapted to reverse-circulation sample drilling employing a down-the-hole hammer drill. The drilling head configuration provides for simultaneous feeding into a multi-walled drill string of drilling mud, compressed air into the drill string to operate the hammer drill and to feed the hammer drill bit head, and withdrawing of sample-containing return air. The system includes a triple-walled, reverse-circulation drill rod especially adapted for down-the-hole hammer drilling that eliminates the need for a separate drive casing string.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the drilling system of this invention, mounted on a truck undercarriage, with the drill mast tilted and angled;
FIG. 2 is a side elevation view of the drill mast mounted to its turntable and positioned vertically;
FIG. 3 is another side elevation view of the drill mast mounted to its turntable and tilted with respect to the plane of the turntable;
FIG. 4 is a front elevation view of the drill mast;
FIG. 5 is an enlarged detail view of a portion of the FIG. 4 view illustrating the stabilizer mounting for the drill head positioning cylinder rod;
FIG. 6 is an enlarged detail view of another portion of the FIG. 4 view illustrating the pipe joint breaker assembly;
FIG. 7 is a side elevation view further illustrating the workings of the structure shown in the FIG. 6 detail view;
FIG. 8 is a perspective view of the drill mast pivot cylinder mounting;
FIG. 9 is a plan view of the drill mast slide assembly;
FIG. 10 is an end view of the FIG. 9 assembly;
FIG. 11 is a plan view of the male trunnion that underlies the FIG. 9 assembly;
FIG. 12 is an end view of the FIG. 11 trunnion;
FIG. 13 is a side view of the FIG. 11 trunnion;
FIG. 14 is a plan view of the mast turntable slide assembly;
FIG. 15 is a perspective view of the drill head assembly;
FIG. 16 is a view of an unassembled triple-walled drill bit section;
FIG. 17 is an exploded view of the FIG. 16 drill bit section;
FIG. 18 is a cross-section view of the drill bit section coupling to the next-adjacent drill string stem section;
FIG. 19 is a bottom perspective view of an exemplary drill bit head of FIG. 16;
FIG. 20 is a side perspective view of the FIG. 19 drill bit;
FIG. 21 is a cross section an exemplary outer casing for use with the FIG. 16 drill bit section; and
FIG. 22 is an exploded view of the FIG. 18 coupling.
DETAILED DESCRIPTION OF THE INVENTION
The drilling system of this invention is designed to drill out mineral samples of the kind required in exploration mineral sampling drilling. In this drilling, holes in the range of 4 in. to 7 in. are commonly drilled to depths up to a few thousand feet. Various types of drilling techniques are required, such as rotary drilling, percussive drilling, hammer drilling, and core drilling, depending on the geology of the structure from which the sampling is done. Drill strings composed of drill bit and drill stem sections coupled together, connected to a drill head assembly on the drill mast, are provided in sectional lengths of six to twelve feet. As the drilling operation is conducted, lengths of drill pipe are coupled, during drilling, and uncoupled, during drill string retraction. Consequently, the drilling system of this invention provides a drilling machine configured to accommodate the various drilling techniques. The drilling system of this invention provides a drill head assembly configured to accommodate drill strings required by the various drilling techniques. The drilling system also provides a pipe joint breaker assembly configured to couple and uncouple drill string pipe sections for the various types of drill strings required for these various drilling techniques. A preferred drilling system also incorporates a triple-walled, reverse-circulation, down-the-hole hammer drill string and provides the necessary infeed and outfeed for lubricating mud, pressurized operating air, and sample-carrying return air flows.
The drilling system of this invention comprises a mobile drilling machine 10 (sometimes also called a "drill rig") comprising a drill mast assembly 12 mounted to a turntable 14 carried by an undercarriage 16. The undercarriage 16 may be any suitable carrier such as a wheeled vehicle, a track vehicle, or a sled vehicle. The drill mast assembly 12 comprises a drill head frame subassembly 18 and a mast support frame subassembly 20 that mounts frame subassembly 18. A mast trunnion and slide frame assembly 22 slideably carries drill mast 12 and mounts drill mast 12 to the turntable 14.
In point of reference, in the following description, "upper" refers to elevated aspects of the drill mast when the mast is upright, "bottom" refers to the opposite of upper, "outer" refers to outward away from the turntable, and "inner" refers to inward facing toward the turntable.
Drill mast frame subassembly 18 comprises a pair of side beams 30, 32 connected across the top by an upper cross beam 34 and connected across the bottom by a bottom cross beam 36. Outer and inner gusset plates 38 connect the upper ends of beams 30, 32 to the upper cross beam 34 and stabilize the top of the drill mast frame subassembly 18. The bottom cross beam 36 is configured, viewed at right angels to the plane in which side beams 34 lay, as a wide angle "V" with the bottom apex of the "V" being provided with a rectangular passage in line with the mid-line drill string axis of the system. This bottom cross beam rectangular passage is provided by an enlarged rectangular box 40, open at the top and bottom and having a width greater than the width of the side beams 30, 32 and the bottom cross beam 36. Side beams 30, 32 are fabricated as steel box beams of generally square cross-section. Upper cross beam 34 is fabricated with welded steel side and top plates welded to the top portion of the side beams 30, 32; the ends of cross beam 34 being extended laterally outward beyond the side beams 30, 32. The bottom cross beam 36 is fabricated with welded steel side, top and bottom plates extended from the side beams to the box 40; and the box 40 is fabricated with welded steel plate side walls. The bottom cross beam plates are welded to the bottom portions of the side beams 30, 21 and to the box 40.
The side beams 30, 32 slideably mount a drill head assembly 50, the outer and inner faces of the side beams being provided with bearing surfaces on which the drill head assembly 50 bears when it travels up and down the drill mast assembly 12. The drill head assembly includes side bearing channels 52, 54 that have inner and outer bearing faces that engage the outer and inner faces of the side beams 30, 32 and ride thereon. Side bearing channels 52, 54 also have base faces, located at their base between their inner and outer faces, that slideably engage the opposed side faces of side beams 30, 32 to locate and stabilize the drill head assembly 50 between the two side beams.
The drill mast subassembly 18 also comprises a drill head positioning subassembly. The drill head assembly 50 tracks along the side beams 30, 32 and is moved therealong by means of left and right side cable and hydraulic cylinder positioners. The left side cable and cylinder positioner comprises: (a) a left hand hydraulic cylinder 56 mounted to and suspended from the left extension of the upper cross beam 34 at its cylinder end along the left side of the side beam 30; (b) a cable sheave subassembly 60 mounted at the end of the cylinder rod associated with cylinder 56 and carrying a pair of freely rotatable cable sheaves; (c) an upper cable sheave 64 freely rotatably mounted in the left extension of the upper cross beam 34; (d) a bottom cable sheave 68 free rotatably mounted at the bottom of side beam 30; (e) a cable tensioner drum 72 mounted on the left side at the bottom of side beam 30; (f) a left side upper cable dead end tensioner and shock adjuster 76; (e) a left side drill head assembly bottom positioning cable 80 that extends upward from the tensioner drum 72 and reeves around the lower sheave of the subassembly 60, extends downward and reeves around sheave 68, and extends upward to a point of connection 86 with the drill head assembly 50; and (g) a left side drill head assembly upper positioning cable 88 that extends from the cable shock adjuster 76 downward and reeves around the upper sheave of the subassembly 60, extends upward and reeves around upper sheave 64, and extends downward to a point of connection 92 with the drill head assembly 50. The right side cable and cylinder positioner comprises: (a) a right hand hydraulic cylinder 58 mounted to and suspended from the right extension of the upper cross beam 34 at its cylinder end along the right side of the side beam 32; (b) a cable sheave subassembly 62 mounted at the end of the cylinder rod associated with cylinder 58 and carrying a pair of freely rotatable cable sheaves; (c) an upper cable sheave 66 freely rotatably mounted in the right extension of the upper cross beam 34; (d) a bottom cable sheave 70 free rotatably mounted at the bottom of side beam 32; (e) a cable tensioner drum 74 mounted on the right side at the bottom of side beam 32; (f) a right side upper cable dead end tensioner and shock adjuster 78; (e) a right side drill head assembly bottom positioning cable 82 that extends upward from the tensioner drum 74 and reeves around the lower sheave of the subassembly 62, extends downward and reeves around sheave 70, and extends upward to a point of connection 88 with the drill head assembly 50; and (g}a right side drill head assembly upper positioning cable 90 that extends from the cable shock adjuster 78 downward and reeves around the upper sheave of the subassembly 62, extends upward and reeves around upper sheave 66, and extends downward to a point of connection 94 with the drill head assembly 50. The left side cylinder 56 is stabilized by cylinder mounting bracket 96 extending from side beam 30. The right side cylinder 58 is stabilized by cylinder mounting bracket 98 extending from side beam 32. Over the length of extension of the rods of cylinders 56 and 58, outer and inner, left and right rod aligning tracks 100, 102 and 104, 106, respectively, are provided on the outer and inner faces of the side beams 30, 32 to carry and stabilize the end of these cylinder rods. The support and stabilization is provided by the respective left and right cable sheave subassemblies 60, 62 which journal mount outer and inner guide wheels 108, 110 (left side) and 112, 114 (right side) which track on the side beam aligning tracks. In the operation of the drill head positioning subassembly, extension of the rods of cylinders 56, 58 will cause the drill head assembly 50 to move up the drill mast side beams 30, 32, and retraction of the cylinder rods will cause the drill head assembly 50 to move down the drill mast side beams 30, 32.
The drill mast frame subassembly 18 is carried and reinforced by the mast support frame subassembly 20. Mast support frame subassembly 20 comprises a pair of side beams 120, 122, each of which being parallel and underlying one of the drill mast frame subassembly side beams 30, 32. Left and right side beams 120, 122 are shorter than their corresponding drill mast frame side beams 30 or 32, and are connected thereto by upwardly-angled left and right upper end beams 124, 126 and downwardly-angled left and right lower end beams 128, 130. The upper and lower end beams, 124, 126 and 128, 130, are long enough to space the side beams 120, 122 inward from the drill mast frame side beams 30, 32 a sufficient distance to provide adequate clearance therebetween for travel of drill head assembly 50 and the related apparatus, piping and hosing. Left and right brace beams 132, 134 extend between the mast frame and support frame side beams near the top of the drill mast assembly 12 to form a triangular reinforcing brace with the upper end beams 124, 126. The beams that make up the mast support frame subassembly 20 are steel box beams welded to one another and to the corresponding outer drill head frame side beams.
The mast trunnion and slide assembly 22 comprises a mast slide subassembly 140 to which the drill mast assembly 12 is slideably mounted, and turntable slide subassembly 142 to which the mast slide assembly is pivotally mounted. The turntable slide subassembly 142 is carried by the turntable 14. The mast slide subassembly 140 comprises left and right pairs of upper and lower steel bearing sleeves 144, 146 and 148, 150 that slideably enclose and ride on the mast support frame side beams 120, 122. Upper and lower steel cross beams 152, 154 are welded to the opposed faces of the upper and lower bearing sleeve pairs 144, 146 and 148, 150. A steel trunnion-mounting framework 156 is mounted to the cross beams 152, 154 for a steel mast pivot pin 158. Pivot pin 158 is positioned in the trunnion-mounting framework 156 from the inward side and is confined therein by an appropriate bearing collar 160 mounted to the outer end of pivot pin 158. The inward end of the pivot pin 158 is rotatably mounted in a male trunnion framework 162 so that framework 162 is located adjacent to and inward of the trunnion-mounting framework 156. Male trunnion framework 162 pivots about pivot pin 158 in a plane parallel to whatever position the drill mast assembly 12 assumes. Male trunnion framework 162 is provided with left and right mast pivoting cylinder rod mounting lugs 164, 166. A steel mast pivoting cylinder bracket 168 is welded to the inward side of the lower bearing sleeves 148, 150 and pivotally mounts a pivot cylinder 170. The end of the rod associated with cylinder 170 is attached to one or the other of the rod mounting lugs 164, 166. When cylinder 170 is actuated, the drill mast assembly 12 will pivot about the axis of pivot pin 158. The upper and lower cross beams 152, 154 mount left and right mast extension cylinders 172, 174. The ends of the rods associated with cylinders 172, 174 are connected to the upper end of the drill mast frame subassembly 18 by left and right steel mounting arms 176, 178 which are welded to the cross beam 34. When the cylinders 172, 174 are actuated, the drill mast assembly 12 will slide up or down, through the bearing sleeves 144, 146 and 148, 150.
The turntable slide subassembly 142 comprises a pair of telescoping mast extender tubes 190, 192 mounted on the deck 194 of the turntable 14, and a pair of tilting cylinders 196, 198 mounted to a slide mounting 200. The outer ends of the telescoping mast extender tubes 190, 192 are connected to left and right mounting lugs 202, 204 provided on the male trunnion framework 162. The ends of the rods associated with the tilting cylinders 196, 198 are connected to left and right mounting lugs 206, 208. When the mast extender tubes 190, 192 are actuated, the drill mast assembly 12 will be shifted inward or outward with respect to the turntable. When the tilting cylinders 196, 198 are actuated, the drill mast assembly 12 will be tilted relative to the axis of the turntable 14. If the turntable axis is considered to be the X axis of the system, tilting cylinders 196, 198 will tilt the drill mast assembly 12 about the Y axis of the system and pivot cylinder 170 will pivot the drill mast assembly 12 about the Z axis of the system. The Y axis of the system is defined by the axis point 210 through the left and right mounting lugs 202, 204. The so-called "Z axis" of the system, defined by the axis of the pivot pin 158, does not remain perpendicular to the turntable axis, although it does remain perpendicular to the Y axis of the system.
A pipe joint breaker assembly 220 is associated with the drill mast assembly 12. Assembly 220 is supported from a steel support platform 222, welded to the outer face of the drill mast frame bottom cross beam 36 just above box 40. Assembly 220 is centered over the passage 41 through box 40 and mounted on the frame 222. Assembly 220 comprises a steel cylinder 224 positioned in axial alignment with the passage through box 40 and having an inner diameter at least as large as the width of passage 41. A series of steel angle brackets 226 are welded to the periphery of cylinder 224 at their apexes so that a series of steel hydraulic cylinder-holding cups 228 may be mounted between the bracket legs as shown in FIG. 6. Each cylinder-holding cup 228 is aligned at an acute angle of about 10 degrees outward from the axis of cylinder 224 (which is coincident with the drill string axis of the system) and welded to the adjacent legs of the angle brackets 226. There are at least three cups 228 located around the periphery of cylinder 224. At least three hydraulic cylinders 230 are mounted in three of the cups 228 with their cylinder rods extending upward and outward at the acute angle of the cups 228. Each cylinder rod 232 has an arm in the form of a steel bar 234 extended at right angle to the cylinder axis. A removable gripper shoe 236 is carried by each bar 234. Each gripper shoe 236 has a curved gripper face 238 aligned parallel to the drill sting axis. With at least three such gripper shoes installed about the periphery of cylinder 224, when the gripping cylinder rods 232 are retracted, the shoe gripper faces 238 will be translated downward and inward toward the drill string axis. Any drill string section, such as a coupling or bit, can be grasped by the gripper shoe faces and secured relative to the cylinder 224. By so doing, and then rotating the drill string in opposite hand to the threads of the drill string section connections, the drill string above the gripper shoes 236 can be unthreaded from the drill string section confined by the gripper shoes. Each gripper shoe 236 is provided with an outward-opening slot 240 designed to fit over the end of the adjacent gripper cylinder rod arm 234. When a gripper cylinder rod 232 is extended, bringing the associated gripper shoe out of contact with the drill string, the shoe may be pivoted away from the drill string and removed from the cylinder rod arm. Thus, the shoe is interchangeable with shoes having different gripping faces 238 or with shoes having a different width to accommodate drill string sections of various diameters.
The drill head assembly 50 comprises a drive subassembly 250, a rotary air interchange and discharge subassembly 252, and a rotary lubricating mud interchange subassembly 254. The drive subassembly 250 comprises a drive gear box 255 to which the side bearing channels 52, 54 are mounted, an axial bull gear 256 and four peripheral drive pinion gears 258 meshed with the bull gear. The pinion gears are selectively driven by individual hydraulic motors 259 mounted atop the drive gear box 255. The rotary air interchange and discharge subassembly 252 comprises a concentric configuration of air inlet and discharge swivels that enable sample-containing return air to be withdrawn axially from the drill string and pressurized operating air to be directed into an annular passage in the drill string. The subassembly 252 is mounted axially atop the drive gear box 255 and is connected to appropriate supply and return air conduits. The lubricating mud interchange subassembly 254 comprises a concentric configuration of a mud inlet swivel enabling the introduction of lubricating mud to an annular passage in the drill string while enabling supply and return air to travel therethrough. The subassembly 254 is mounted axially underneath the drive gear box 255.
A drill head adapter 260 is bolted to the underside of the lubricating mud interchange subassembly 254 and constitute the first section of the drill string assembly 262. A preferred reverse-circulation drill string assembly is shown comprising a plurality of sections that are threaded to one another commencing with the drill head adapter 260, a plurality of intermediate pipe sections 264, and concluding with a drill bit section 266. The intermediate pipe sections 264 each comprise three concentric steel pipes joined together within an steel upper coupling sleeve 268 by a spider coupler 270. The upper coupling sleeve 268 has a configuration similar to a conventional box coupling of a box and pin threaded coupling employed in conventional drill string couplings in that the upper end of the coupling sleeve 268 has a tapered inwardly-threaded box end designed to have an correspondingly-tapered male thread pin end of an adjacent drill string section threaded therein. The upper end of the outermost pipe 272 (the section casing) is welded to the end of the coupling sleeve 268 opposite the threaded box end. The lower end of the casing pipe 272 is welded to a steel lower coupling sleeve 274. The lower coupling sleeve 274 has a configuration similar to a conventional pin coupling of a box and pin threaded coupling in that its lower end, opposite to the weldment to the casing 272, has an externally-threaded pin end.
The spider coupler 270 is located below the box end of the upper coupling sleeve 268 and comprises concentric inner and outer cylindrical elements 271 and 273. Coupling sleeve 268 has an inner conical surface 276 that makes a transition from the box end to a thicker main portion 278. It is within this main portion 278 that spider coupler 279 is positioned. If the outer element 273 of spider coupler 279 is provided with an externally-threaded portion, the main sleeve portion 278 can be internally-threaded as shown to receive and locate the spider coupler. The spider coupler must be positively positioned within sleeve 268 and, to that end, the outer element 273 may be provided with an outer conical surface 280 designed to seat against the upper coupling sleeve conical surface 276. The inner element 271 of the spider coupler 270 must be positively positioned within the outer element 273 and, to that end, the inner element may be provided with an outer conical surface 282 designed to seat against an inner conical surface 284 provided in the outer element 273. The outer element 273 is counterbored to receive the upper end of an intermediate pipe 286, pipe 286 being welded to the lower end of the outer element. The inner element 271 is counterbored to receive the upper end of an inner pipe 288, pipe 288 being welded to the lower end of the inner element. The interiors of the inner and outer elements are provided with O-ring seal sets 290, 292. The seal set 290 in the outer element 273 is located above the position of the inner element 271. The seal set 292 in the inner element 271 is located above the position of the upper end of the inner pipe 288, being separated therefrom by an inner rim 294.
The pin ends of the concentric intermediate and inner pipes 286, 288 extend beyond the pipe section lower coupling sleeve 274. The intermediate pipe 286 must extend beyond the lower coupling far enough to be insertable into the adjacent outer spider element 273 into engagement with the O-ring seal set 290. The inner pipe 288 must extend beyond far enough beyond the lower coupling to be insertable into the adjacent inner spider element 271 into engagement with the O-ring seal set 292. When adjacent pin and box ends are threaded together, the bottom of the upper intermediate pipe 286 will extend into the box end coupling below and seat on the upper rim 296 of outer element 273, and the bottom of the upper inner pipe 288 will extend further into the box end coupling below and seat on the inner rim 294 of inner element 271. The tolerances between the intermediate and inner pipe ends and the pipe-receiving portions 298, 300 of the adjacent spider inner and outer elements are small enough to insure that the O-ring seal sets will make pressure-tight seals.
The lower ends of the intermediate and inner pipes in a pipe section are supported within the lower coupling sleeve by means of spacers. These spacers 306, 308 are welded to the outer periphery of the inner and intermediate pipes, respectively, and located within the confines of the lower coupling sleeve 274. The spacers contact the opposing surface across the annular space to maintain the concentric relationship of the three pipes. Consequently, the inner and intermediate pipe lower ends project unencumbered beyond the lower coupling sleeve but are fixed concentrically by the spacers. Because the spacers are attached to one surface within the annulus, the inner and intermediate pipes may contract and expand relative to the outer casing without damaging any of the interconnections between the pipes that make up a pipe section of the drill string.
The threaded peripheral surfaces of the inner and outer spider elements 271, 273 are provided with a series of longitudinal grooves 302, 304 radially spaced around the exterior of the inner and outer elements. These grooves are similar in appearance to spline grooves and provide for fluid communication longitudinally through the pipe section couplings: that is, through the annular passage between the outer casing and the intermediate pipes and through the annular passage between the intermediate pipes and the inner pipes through the pipe couplings.
If one of the inner or intermediate or outermost pipes is damaged or worn out, the spider may be disassembled and a replacement made. Consequently, a pipe section may be repaired rather than completely replaced. Oftentimes, it will be an outermost pipe, or casing, that will become damaged or worn out and require replacement. It that event, the spider may be removed from the upper coupling sleeve, with the intermediate and inner pipes attached, and simply reinserted as a complete unit into a replacement upper coupling and casing.
In a typical use of this triple-walled drill string, pressurized air would be delivered downward through annulus between the longitudinally-assembled inner and intermediate pipes, return air carrying drilled particle samples would be delivered upward through the longitudinal-assembled inner pipes, and lubricating mud would be delivered downward through the annulus between the longitudinally-assembled outer casings. The outer casing of each pipe section is provided with outlet passages 310 from the annular passage between the outer casing and the intermediate pipe. These outlet passages enable lubricating mud to vent to the outer periphery of the drill string along the pipe sections during a drilling operation. These outlet passages are preferably provided at several locations radially around the casing and may be provided in the upper coupling sleeve at the box end of each pipe section.
In the preferred embodiment of the triple-walled drill string, the bottom section, comprising the drill bit section 266, comprises an outer casing section 320, an interchanger subassembly 322, a down-the-hole hammer drive subassembly 324, and a bit subassembly 326. The bottom casing section 320 comprises a threaded box coupling as previously described at its upper end and a casing pipe welded to the box coupling and extending down into contact with the drive subassembly 326. The interchanger subassembly 322 comprises a double-walled cross-over upper section adapted to be connected to and supported by the bottom casing box coupling. The cross-over section is ported to receive pressurized air from above and transfer it into the down-the-hole hammer subassembly 324 for operating the hammer subassembly and for supplying scavenging air to the bit head. The upper portion of the interchanger subassembly 322, contained within the bottom casing box coupling, is provided with an external peripheral O-ring seal which bears against the inner periphery of the coupling as a mud seal. The bottom box coupling is provided with lubricating mud passages, as described above, located above the O-ring seal and, consequently, lubricating mud flow will be blocked by the O-ring seal and forced to pass out through the adjacent lubricating mud passages. The bottom casing pipe section is provided with external, longitudinal grooves 328 extending from the upper lubricating mud passages to a region adjacent the drive subassembly 326. At least two such grooves, 180 degrees apart, are preferably provided. These grooves 328 are in fluid communication with the upper lubricating mud passages and with lower lubricating mud passages 330 so that lubricating mud can be channeled to the bottom of the drill string for lubricating the outer casing at points adjacent the drive subassembly 326. This feature of the invention eliminates the need for providing for lubricating mud passage through the interchanger subassembly 322.
A preferred bit subassembly 326 for placer drilling comprises a scavenging air inlet 332, hammer piston striking face 333, bit shank 334, centering spider 335, and the head 336. The head 336 contains a pre-load surface 337 against which the bottom end of bottom casing pipe 320 abuts. Centering spider 335 contacts the inner wall of drive hammer subassembly casing 325 and insures that head 336 is axially centered at the end of the drill string. The pre-load surface 337 makes the transition between the bore-contacting periphery 338 of the bit head and a collar 339. The bit is mounted within the bottom end of the drive hammer casing 325 so that the end of casing 325 abuts the top of the collar 339. A portion of collar 339 remains within the casing pipe 320 at all time during a drilling operation by the working area limits on the bit shank so that the upper parts of the bit subassembly are isolated from the bore hole. Consequently, no lubricating mud or other contaminants can gain access to the inner portions of the bit subassembly from the periphery of the bit. Therefore, the entrained sample cuttings will provide a true sample of the geological structure through which the bore hole was made.
A preferred bit head 336 is provided with internal scavenging air passages 340 leading from the interior part of the bit subassembly, that is in air communication with the drive hammer subassembly, to the bottom cutting face 341 of the bit head for flushing the face of the bit head and entraining sample cuttings from the bottom of the bore hole. The bit head 336 is also provided with internal return air passages 342 leading from the cutting face 342 through the bit head 336 to open into the annulus between the hammer subassembly casing 325 and drill string bottom casing pipe 320 for transfer of the entrained sample cuttings away from the drill bit head. These entrained cuttings travel upward along the exterior of the hammer subassembly casing 325, and inside of the drill string bottom section casing 320, and pass into the cross-over of the interchanger subassembly 322. From within the cross-over, the entrained sample cuttings travel axially upward through the inner pipes 288 of the drill string sections and finally through the drill head assembly 50 and out into a collecting tank where the entraining air and the sample cuttings are separated. The bit head 336 is designed so that sample cuttings must pass upward through the bit head into the annulus between the bottom section casing 320 and the exterior of the drive hammer subassembly casing 325. The sliding fit between the upper part of the collar 339 ensures that no contaminating material from the bore hole can gain access to the entraining air stream as it carries sample cuttings upward for collection.
The preferred embodiment of this system is capable of drilling to 3000 feet, has a drill head torque of 20,000 ft-lbs. and a draw works lifting power of 88,000 lbs. The drill mast turntable can be mounted on truck (FIG. 1), track frame (FIG. 2) or other types of carriers. The mast will turn 90 degrees-to-carrier on both sides and, with the mast trunnion and slide assembly, will allow positioning to all positions at side or rear of carrier. The drill mast transports laying down over the turn table. With the hydraulic mast extension and the telescoping extension on the turn table, any angle hole can be drilled without a drill pad. No drill pad is needed with this system. A three-way operator's control console may be mounted to the mast if desired. The drill head with gear reduction can be set up with two to eight high performance hydraulic motors for varied applications and with a variable speed rotation control located on the operator's console. For example, up to four additional motors could be mounted to the underside of the drill head gear box 255 to drive the pinion gears to provide added torque up to 35,000-40,000 ft-lbs. In addition, a speed increaser gear box could also be mounted to the underside of the gear box 255, there being sufficient power to drive the drill string through the speed increaser. Thus, with the present system, a drilling setup requiring only 30 rpm drilling speed could be easily converted to a setup requiring a 600 rpm drilling speed.
In the course of operation, the drilling rig of this invention would be transported to a drilling site and roughly positioned at the desired point of drilling. Through appropriate rotation of the turntable and inner/outer positioning of the mast-turntable extension, the drilling mast can be directed to the exact location required. It may be the case that the drilling mast must be angled to become properly directed and, in such a case, the mast trunnion can rotate the mast to the desired skewed position, and the mast extension can pivot the drilling mast from the FIG. 2 position to a FIG. 3-like position so that the drilling mast can thereby be positioned in like manner to that shown in FIG. 1, to a variety of compound-angled positions however conditions require. Thus, the drilling mast can be shifted in and out, pivoted from vertical, and skewed to a compound angle, all without moving the carrier. When the mast is properly located at the point of desired drilling, the mast in then shifted down into contact with the ground for the commencement of drilling.
Depending on surface conditions, the bottom of the drilling mast may be positioned to bear against a timber or other support to stabilize its location with respect to the drilling hole's surface entry. An inner bearing plate 37 is provided at the bottom of the drill mast frame side beams 30,32 for this purpose. This would be useful when time comes for pulling the drilling string from the bore hole.
While the preferred embodiment of the invention has been described herein, variations in the design may be made. The scope of the invention, therefore, is only to be limited by the claims appended hereto.
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The drilling system of this invention provides a drill mast mounted on a turntable. The turntable may be mounted on any type of undercarriage or carrier. The drill mast can be positioned around the perimeter of the turntable, it can be positioned near to, or away from, the turntable. The drill mast is carried on a trunnion mounting and can be oriented along Y and Z axis' with respect to the turntable X axis for drilling angle holes. A pipe joint breaker assembly is provided adjacent the lower end of the drilling mast. This assembly can accommodate different size pipe diameters. The drilling systems of this invention is specially adapted to reverse-circulation sample drilling employing a down-the-hole hammer drill. The drilling head configuration provides for simultaneous feeding into a multi-walled drill string of drilling mud, compressed air into the drill string to operate the hammer drill and to feed the hammer drill bit head, and withdrawing of sample-containing return air. The system includes a triple-walled, reverse-circulation drill rod especially adapted for down-the-hole hammer drilling that eliminates the need for a separate drive casing string.
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SUMMARY OF THE INVENTION
The invention relates to a device for supporting and moving a tool within a tapping traversing a wall so as to be flush on one side of the wall and projecting on the other side.
BACKGROUND OF THE INVENTION
In heavy components made in boiler factories, in particular pressurized water nuclear reactor vessels, pipe outlets or inlets in the tank or tappings are formed in the wall of the vessel so as to permit the connection, outside of this vessel, between the tapping and an inlet or outlet pipe.
Such tappings are formed in the wall so that the tapping is flush with the inner surface of the tank and projects fairly widely outside the tank to connect it with a pipe of the primary circuit of the reactor bringing water under pressure into the tank, or enabling the outflow of this water, which acts as coolant in the core of the reactor, from the vessel to the steam generators.
The inner surface of the vessel as well as of the tappings must be coated with a layer of stainless steel, and the quality of this coating must be checked, in particular within tappings formed in the wall of the tank.
Such checks assume a very good surface condition of the coating, and the entire inner surface of the tapping must be milled before commencing the checking operation.
On the other hand, when defects are detected, it is necessary to carry out machining in greater depth in order to determine the depth of these defects.
To carry out the machining operations or the checking operations, a tool or a checking means must be moved inside the tapping into different positions, enabling the various areas of the lateral surface of the tapping to be reached.
In the case of pressurized water reactor vessels, the borings or checks inside the tappings of the primary circuit are generally performed when the vessel is in vertical position, i.e., with tappings whose axes are practically horizontal.
To date, these operations are performed manually and are extremely arduous since it is necessary to work with very different positions of the tool although the internal diameter of the tapping is relatively small.
In the same way, the sound execution of the work inside the tapping is hampered by limited accessibility, the internal diameter of the tapping being relatively small. In certain cases, the space available is not even sufficient to permit the use of certain types of tools.
In addition, tappings of pressurized water inlet pipes in the vessel of the reactor have a conically shaped bore which further complicates manual machining for the purpose of achieving a good surface condition.
More generally, when it is desired to carry out machining or checking operations in tappings formed in the wall of a large sized boiler-made component, difficulties are encountered due to the exiguity of the space within which the machining is to be done, to the various positions that the tool or the checking means must be made to assume to follow the inner surface of the tapping, and to the fact that the inner bore of these tappings is not always cylindrical.
It is therefore an object of the invention to provide a device for supporting and moving a tool within a tapping having a symmetry of revolution and traversing a wall so as to be flush on one side of the wall and project on the other side, this device enabling automatisation of the work carried out with the tool, and accurate positioning of the tool with respect to the surface to be worked inside the tappings.
It is another object of the invention to provide a device for supporting and moving a tool within a tapping which device is adaptable to different types of profile and to different bore sizes.
GENERAL DESCRIPTION OF THE INVENTION
Accordingly, the device according to the invention comprises:
(a) means for supporting and centering in the form of a star the arms of which are radial with respect to the tapping and bear centering parts designed to be engaged in the orifice of the tapping and means for fixing to the wall, on the flush side of the tapping;
(b) a centering part at the projecting end of the tapping and within the latter;
(c) the supporting means and the centering part carrying end bearings having the axis of the tapping for a common axis,
(d) a tool holder bar connected to two stub shafts aligned along the axis of the tapping, each rotating in one of the end bearings and mounted off-set with respect to the axis of the tapping in a radial direction,
(e) means for rotating the tool holder bar around the tapping axis; and
(f) means for guiding and moving a tool in the axial direction and in radial directions of the tapping, borne by the tool holder bar.
In order that the invention may be more clearly understood an embodiment thereof will now be described by way of example, with reference to the accompanying drawings, in the case where the supporting and moving device according to the invention is used for machining and checking in tappings of a pressurized water nuclear reactor vessel.
BRIEF INTRODUCTION TO THE DRAWINGS
FIG. 1 is an elevation, partly in section, of the whole of the device in position within the cylindrical bore of a tapping formed in the wall of a pressurized water nuclear reactor vessel.
FIG. 2 is an enlarged section along the line A--A of FIG. 1.
FIG. 3 is a view on a larger scale of the right-hand portion of FIG. 1.
FIG. 4 is a section along the line C--C of FIG. 3.
FIG. 5 is a section along the line B--B of FIG. 1.
FIG. 6 is an elevation, partly in section, of the whole of the device in position in a conically shaped bore of a tapping formed in the wall of a pressurized water reactor tank.
DESCRIPTION OF PREFERRED EMBODIMENT
FIG. 1 shows a portion of the wall 1 of a pressurized water reactor vessel having a tapping 2 which is practically flush with the inner surface 1a of the wall 1 of the vessel, and which projects with respect to the outer wall 1b of this vessel.
The inner bore 3 of the tapping 2 is cylindrical.
The supporting and moving device for a milling tool in the bore of the tapping shown in FIG. 1 includes a handling frame 6, a star-shaped support 7, a tool holder bar 8 and a centering bell 9.
The handling frame is constituted by a bracket formed by two beams 10 and 11 of rectangular section, the beam 10 being positioned vertically and the beam 11 horizontally when the device is in position inside the vertical tank 1.
The horizontal beam 11 bears a handling lug 12 enabling the transportation of the device as a whole with a travelling bridge crane. This beam 11 is supported on the upper portion of the vessel 1 through two supports 13 constituted by screws enabling adjustment of the verticality of the handling frame positioned on the vessel. Means for attaching the handling frame on the tank are provided at the end of the beam 11, and comprise an arm 14 held in position at the end of the beam 11 by pins 15 inserted in openings of arm 14.
A screw 16 enables the handling frame to be locked in position on the upper portion of the tank. The handling frame 6 also carries an electrical box 17 enabling the supply of the drive members of the device.
The handling frame 6 is connected to the star-shaped supporting device 7 by bolting at the level of a junctions plate 18 assuring the connection between the lower end of the handling frame and one of the arms of the star-shaped support 7 which is constituted by three arms 7a, 7b, 7c each having, as its plane of symmetry, a plane containing the axis xx' of the tapping, i.e., radial planes.
The arms 7a, 7b, 7c are inclined to the vertical and radial with respect to the tapping when the device is in position as shown in FIG. 1.
The arm 7a is constituted at its end by a beam portion 19 enabling its coupling with the frame 6. This beam portion 19 bears a suction disc 20 whose position is adjustable with respect to the arm 7a by means of a screw 21. The beam 19 also carries a centering bracket 23 engageable in the orifice of the bore 3 flush with the inner surface 1a of the tank, this bracket itself bearing a stub 24 enabling support on the inner surface 1a of the vessel.
In the same way, the arms 7b and 7c include respectively adjustable suction discs and support brackets to permit the centering and attachment of the device to the inner surface of the vessel at the level of the tapping. The stubs associated with the arms 7b and 7c, respectively, are adjustable by means of the jacks 22.
At the center of the star is fixed a bearing 25 in which rotates the shaft 26 axially positioned with respect to the tapping. The shaft 26 is connected to the tool holder bar 8 by means of a device 30 enabling adjustment of inclination, and to be described in more detail with reference to FIGS. 3 and 4.
At the end of the shaft 26 is fixed a wheel 31 enabling the shaft 26 to be rotated manually from a derrick floor within the vessel.
The end of the shaft 26 is also fast to a gear-wheel 34 engaging with a pinion 35 driven by a motor 36 supported by the arm 7a of the star.
The centering bell 9 inserted in the projecting end of the tapping comprises a cylindrical jack 38 bearing on its outer surface sliding pads such as 39 facilitating the insertion of the centering bell into the tapping, and inflatable seal 40 positioned within a groove machined in a projecting portion of the outer surface of the bell 38.
At the central part of the cylindrical envelope 38 of the bell is fixed a bearing 41 constituted by a tube made fast to the bottom of the bell 38 by ribs 42.
In the bearing 41 is engaged a shaft 44 connected in articulated manner to the end of the tool holder bar 8, as will be explained with reference to FIG. 2. The shafts 26 and 44 are aligned and positioned axially with respect to the tapping, i.e., in the case of FIG. 1, in a horizontal direction.
The tool holder bar 8 is provided over its whole length with a slide 46 with a dovetailed profile and a screw 47 mounted in bearings such as 48 permitting the movement of the tool 70 constituted by a grinding wheel and its driving motor in the axial direction of the tapping.
The tool will be described in more detail with reference to FIG. 2, which shows the pivoting axle 44 inside the bearing 41 positioned at the center of the cylindrical bell 38 in axial direction.
The shaft 44 is fast to a bracket 50 whose horizontal part enables fixing of the tool holder bar 8 in a precise position as regards its orientation with respect to the shaft 44. For this, the bar 8 is fast to a sleeve 51 in the central bore through which passes an axle 52 fixed with respect to the bracket by means of screws 53 and with respect to the sleeve 51 by a nut 54 engaged on the threaded upper end of the shaft 52. Openings in the sleeve 51 and cotters 55 enable the bar 8 to be held in a constant angular position with respect to axial shaft 44, if one considers a rotation around the axle 52.
In all cases, the longitudinal axis yy' of the tool holder bar 8 is radially off-set with respect to the axis xx' of the tapping.
The shaft 44 is pierced at its center by a passage 57 enabling the supply of control fluid to the inflatable seal 40.
FIGS. 3 and 4 show axial shaft 26 mounted to rotate in the bearing 25 and connected through a sleeve 65 and stiffeners 64 to a plate 62, the stiffeners 64 being welded on the one hand to the sleeve 65 and on the other hand to the plate 62.
The plate 62 comprises two holes 63a within which pass screws 63b enabling the shaft 26 and the tool holder bar 8 to be fastened together.
The tool holder bar 8 is fast to an attachment plate 61, whereas a support plate 60 is inserted between the plate 62 fast to the shaft 26 and the plate 61 fast to the tool holder bar 8.
The support plate 60 is pierced with holes 68 centered on the vertical axis of this plate 60.
The concordance between the holes 63a and 68 enables the plates 60 and 62 to be made fast through screws 63b.
The plate 61 fast to the tool holder bar 8 comprises sets of two threaded holes 67 the spacing of which corresponds to that of the holes 63a of the plate 62.
In FIG. 3 a first set of holes 67 of the plate 61 is shown in concordance with the holes 63a and 68, so that the screws 63b permit the shaft 26 and the tool holder bar to be fastened together, whereby the axis of this bar is parallel with the axis of the shaft 26, i.e., with the axis of the tapping.
This corresponds to the position of the tool shown in FIG. 1 where the rotational positioning of the axle 26 through the gear wheel 34 enables the mill of the tool 70 to be made to describe the internal cylindrical surface of the bore of the tapping 2.
The second set of holes 67, when brought into concordance with the holes 63a and 68, enables the plate 61 to be placed in the position 61' shown in dot-dash lines in FIG. 3. For this, it suffices to unscrew the screw 63b and to move the plate 61 fast to the tool holder bar 8 downwards, then to rotate it slightly to bring the holes 67 into concordance with the holes 63a and 68. The shaft 26 and the tool holder bar 8 can then be fastened together by means of the screws 63b which have just been fixed in the second set of holes 67 of the plate 61.
The axis of the tool holder bar 8 is then inclined with respect to the axis of the shaft 26, i.e., with respect to the axis of the tapping 2.
The device is then in the position shown in FIG. 6.
The arrangement of two sets of holes 67 on the plate 61 is selected so as to bring the axis of the tool holder bar along the direction of a generator of the cone constituting the bore of the tapping 2' shown in FIG. 6.
In fact, in pressurized water nuclear reactor vessels the tappings are of two types, some with an inner cylindrical bore, others with a conical inner bore. With a plate including two sets of holes 67 as shown, it is hence possible to move the device very rapidly and very easily from the machining position in a cylindrical bore to the machining position in a conical bore.
In fact, on the placing in rotation of the shaft 26, the grinding wheel of the tool 70 can then describe a conical surface corresponding to the inner surface of the bore.
Referring to FIGS. 1 and 5, the whole of the tool is seen constituted by a grinding wheel 70 mounted on an axle 71 driven by a motor 72 through a belt 73.
The whole of the tooling is fixed to a frame 74 mounted to slide on the dovetailed slide 46 fast to the tool holder bar 8. On the other hand, the frame 74 bears a nut 75 in engagement with the endless screw 47 rotated by a motor supported by the tool holder bar 8.
In this manner, the whole of the tooling can be moved axially in the bore by being moved along the slide 46 of the tool holder bar 8.
The axle 71 of the grinding wheel 70 is rotatably mounted in a barrel 77 which can be moved along its axis by a jack 78, with respect to the frame 74 of the tooling. This effects penetration of the grinding wheel into the covering metal of the bore of the tapping.
A set of pulleys 79 permits the electric wires or fluid supply tubes to reach the different motors or jacks supported by the tool holder bar and the tooling.
To place the supporting and moving device which has just been described in service, the various adjustments enabling it to be adapted to the tapping to be machined are first made.
Thus, the brackets 23 are adjusted to the aperture of the tapping, a bell 38 of a diameter corresponding to the inner diameter of the tapping is selected and the inclination of the tool holder bar 8 with respect to the rotary axis of this bar is selected so as to be adapted to the geometry of the tapping. A tool suitable for the machining to be done is placed on the tool holder bar.
Once these adjustments have been made, the tool is placed in raised position and the suction cups in their rear position.
The device is then inserted into the tapping by handling it by means of the lifting lug 12 until the bell is in its final position at the level of the end of the projecting portion of the tapping. The stubs 24 are placed in position against the inner wall of the vessel and the seal 40 of the bell 28 is inflated by sending the actuating fluid for the seal through the central passage 57 of the shaft 44.
Then the adjustment in position and the fixing of the tool is carried out by means of the shaft 14 and by the screws 12 and 16.
The suction cups 20 are then adjusted by acting on the screws 21 so that these suction discs contact the inner wall of the vessel. These suction discs 20 have a contact surface constituting a portion of a cylinder, so as to enable them to mate perfectly with the inner surface of the tank.
The suction discs are then subjected to suction, which permits the device to be held in position independently of any other support. Then the working parameters of the tool are selected which is started up from a control box arranged on the portion of the device which is inside the tank.
If it is desired to true the entire inner surface of the tapping, the grinding wheel can be advanced step by step in the axial direction and the tool holder bar rotated slightly over 360° so as to effect a complete sweep of the surface with a slight overlap. Each of the step by step advances is obviously selected so that its amplitude is less than the operating width of the grinding wheel.
In this case, after the positioning of the tool and the placing of the suction discs 20 under reduced pressure, the centering brackets 23 are dismounted, permitting a sweep of the inner surface of the tapping by the grinding wheel up to the end of this tapping flush with the inner surface of the tank.
The principal advantages of the device according to the invention are to enable automatisation of the operations of machining in a tapping and the use of more bulky tools, to provide high power at the shaft end and to permit adaptation to various geometries of tapping.
On the other hand, in the case of trueing the inner surface of the tapping with a grinding wheel, the regularity of the milling compared to manual milling results in a surface of very high quality.
It is also possible to completely isolate the tapping during the operations which are carried out then by means of inflatable seals of the centering bell.
Finally, the use of the device according to the invention is particularly simple and accurate.
The invention is not limited to the embodiment which has just been described, but encompasses all modifications and the use of equivalent means.
Thus, instead of using a grinding wheel for trueing the tapping, it is possible to use an abrasive belt passing over a pulley and a support wheel rotated by a motor.
Instead of a milling tool, it is possible to arrange on the tool holder bar a tooling enabling any operation to be carried out at any location within the tapping bore.
It is also possible to use fastening means other than suction discs attached against the inner wall where the tapping opens out, and to use other embodiments of the device for variable inclination of the tool holder bar.
The use of the device according to the invention is not limited to machining, but may also be used to carry out non-destructive checking within a tapping by replacing the tool mounted on the tool holder bar by checking means which can be moved into positions enabling the checking of the entire inner surface of the bore.
Finally, the device according to the invention may be employed in fields other than the construction of nuclear reactor vessels, e.g., in the construction of other forged or boiler-made vessels of large dimensions including tappings of any shape.
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A supporting and centering arrangement in the form of a star the arms of which are radial with respect to a tapping to be machined or checked. These arms have elements for centering and fastening them to the tapped wall, as well as a centering element at the projecting end of the tapping. The support and the centering element carry bearings. A tool holder bar connected to two rotating stub shafts is mounted off-set from the axis of the bearings in the radial direction of the tapping. The bar supports a tool guide, and is rotatable about the axis of the tapping. The device is especially useful for machining and checking tappings formed in a pressurized water nuclear reactor tank.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This invention claims priority from and is a continuation-in-part of currently pending patent application Ser. No. 12/700,923 (attorney docket 16169-E), filed Feb. 5, 2010, which application is incorporated herein by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] This invention was made with Government support under Contract DE-AC0576RL01830 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.
BACKGROUND
[0003] During friction stir welding, two pieces of metal can be mechanically intermixed at the place of the join. During intermixing, the materials can be transformed into a softened state that allows the metal to be fused using mechanical pressure. A friction stir weld is made with a rotating tool that is plunged into a material along a joint line, and then translated along the joint. The tool, therefore, is preferably wear-resistant and exhibits high strength, toughness, oxidation resistance, and low thermal conductivity. Widespread commercial applications of friction stir welding will require the development of cost-effective and durable tools.
SUMMARY
[0004] This document describes compositions, and processes of fabrication, of tools for friction stir welding. According to embodiments described herein, tools can be made with fewer process steps, lower cost techniques, and/or lower cost ingredients than other state-of-the-art processes. Furthermore, the resultant tool compositions can exhibit improved distribution and homogeneity of chemical constituents, greater strength, and/or increased durability.
[0005] In one embodiment, a friction stir weld tool comprises tungsten and rhenium and is characterized by carbide and oxide dispersoids, by carbide particulates, and by grains that comprise a solid solution of the tungsten and rhenium. The grains do not exceed 10 micrometers in diameter. In some embodiments, the grains have a diameter between 100 nm and 1 micrometer.
[0006] The rhenium can be less than or equal to 20 wt % of the tool. Alternatively, the rhenium can be less than or equal to 10 wt % of the tool. Preferably, the rhenium is less than or equal to 5 wt %.
[0007] In some instances, the material properties and performance improve as grain size decreases. The improvement can be sufficient to allow changes in tool composition that would normally be undesirable because it results in poor material properties and performance. For example, with sufficiently small grain size, the friction stir weld tool can have substantially no nickel. Alternatively, or in addition, the friction stir weld tool can exclude rhenium.
[0008] Friction stir weld tools according to embodiments described herein can exhibit a hardness value of at least 450 H V at room temperature. As used herein, H V refers to the Vickers hardness.
[0009] The dispersoids can be located in the grains, on the grains, or both. In some embodiments, the tool comprises both hafnium carbide and cerium oxide as carbide and oxide dispersoids, respectively.
[0010] In some embodiments, the carbide particulates can comprise hafnium carbide. Preferably, the carbide particulates are uniformly distributed in the tool. For example, the volume fraction of carbide particulate in any 50 cubic micrometer volume the tool falls within 1 standard deviation of the mean volume fraction of carbide particulate in any 500 cubic micrometer volume of a dense solid provided the carbide particulate is 1 to 5 micron in size.
[0011] In some embodiments, the tool comprises substantially equiaxed grains and an even size distribution of grains. For example, 80% of the grains can be within 1 standard deviation of a mean grain size in any 500 cubic micron volume of the tool.
[0012] In one embodiment, a friction stir weld tool comprises tungsten and is characterized by carbide and oxide dispersoids and by grains having diameters between 100 nm and 10 micrometers, wherein the grains comprise tungsten and substantially no rhenium.
[0013] Methods for fabricating friction stir weld tools comprising tungsten and rhenium can be characterized by providing a nanopowder and comminuting a mixture comprising the nanopowder, particulates comprising a carbide compound and an oxide material. The nanopowder comprises crystallites having an average crystallite diameter between 20 and 60 nanometers and comprises tungsten. The methods further comprise sintering the mixture at a temperature and for a time such that the tool has grains not exceeding 10 micrometers in diameter, and forming carbide and oxide dispersoids in the tool from at least a portion of the carbide compound and the oxide material, respectively.
[0014] In various embodiments, the crystallites can comprise tungsten and rhenium in a solid solution. The carbide can comprise hafnium carbide. The oxide material can comprise cerium oxide. In one example, the oxide material is contained in a sol.
[0015] One example of comminuting includes, but is not limited to, milling the mixture in water.
[0016] Preferably, the temperature for the sintering is less than or equal to 1600° C. The time, in one embodiment, is less than or equal to 5 hours. In another, it is less than or equal to 2 hours.
[0017] One example of a method for fabricating a friction stir weld tool is characterized by synthesizing a nanopowder from an aqueous solution comprising tungsten and rhenium precursors, crystallites of the nanopowder having an average diameter between 20 and 60 nanometers and comprising a solid solution of tungsten and less than 10 wt % rhenium. A mixture comprising water, the nanopowders, hafnium carbide particulates, and a sol comprising cerium oxide is then comminuted and the mixture compacted. The mixture can then be sintered at a temperature less than or equal to 1600° C. for a time less than or equal to 5 hours such that the tool has grains not exceeding 10 micrometers in diameter, and such that hafnium carbide and cerium oxide dispersoids form in the tool from at least a portion of the hafnium carbide particulates and the cerium oxide, respectively. Preferably, the synthesizing step further comprises forming tungsten carbide dispersoids from excess carbon in the aqueous solution, wherein the tungsten carbide dispersoids are located in, or on, the crystallites.
[0018] The purpose of the foregoing summary is to enable the United States Patent and Trademark Office and the public generally, especially the scientists, engineers, and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The summary is neither intended to define the invention of the application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
[0019] Various advantages and novel features of the present invention are described herein and will become further readily apparent to those skilled in this art from the following detailed description. In the preceding and following descriptions, the various embodiments, including the preferred embodiments, have been shown and described. Included herein is a description of the best mode contemplated for carrying out the invention. As will be realized, the invention is capable of modification in various respects without departing from the invention. Accordingly, the drawings and description of the preferred embodiments set forth hereafter are to be regarded as illustrative in nature, and not as restrictive.
DESCRIPTION OF DRAWINGS
[0020] Embodiments of the invention are described below with reference to the following accompanying drawings.
[0021] FIG. 1 includes a scanning electron microscope (SEM) micrograph of an agglomerated crystallite after combustion synthesis according to embodiments of the present invention.
[0022] FIGS. 2A and 2B include micrographs of dense compacts after sintering according to embodiments of the present invention.
[0023] FIG. 3 includes a micrograph obtained from a W-4% Re—HfC sample that shows greater than 90% density and WRe grain size below 900 nm with only sintering, according to embodiments of the present invention.
[0024] FIGS. 4A and 4B include micrographs showing a fractured surface ( 4 A) and a polished surface ( 4 B) at two levels of detail of one embodiment that was 96.8% dense and exhibited grain sizes near 100 nm.
[0025] FIG. 5 is a mapping of hardness of an FSW tool prepared by conventional means.
[0026] FIG. 6 is a mapping of hardness of a W-6Re-0.1Ni—HfC—CeO FSW tool according to embodiments of the present invention.
DETAILED DESCRIPTION
[0027] The following description includes the preferred best mode of one embodiment of the present invention. It will be clear from this description of the invention that the invention is not limited to these illustrated embodiments but that the invention also includes a variety of modifications and embodiments thereto. Therefore the present description should be seen as illustrative and not limiting. While the invention is susceptible of various modifications and alternative constructions, it should be understood, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims.
[0028] Processes for fabricating tools embodied by the description provided herein can include W—Re nanophase powder production, mixing with secondary phases, and densification. The W—Re nanopowders are produced using either combustion synthesis (Glycine Nitrate process) or by a spray pyrolysis process. The resulting powders, which commonly comprise primarily metal oxides, are then placed in a vacuum furnace for reduction to W—Re alloy metal powder. The reduced powder can then be mixed with secondary phases. For example, the W—Re nanopowder can be mixed with various quantities of HfC particulate and CeO sol in an aqueous media. In one instance, the mixture is ball milled for 4 hrs using YSZ milling media. Immediately after mixing, the aqueous suspension is poured onto a tray and liquid nitrogen is added to cover the powder bed. This tray is inserted in a freeze dryer and dried for 12 hrs until all moisture is removed.
[0029] The dried powder is then collected and put through a process of densification. Densification can be done in one of several ways including, but not limited to, cold isostatic pressing (CIP) with sintering, hot isostatic pressing (HIP), and CIP with sintering and HIP. According to one example involving the CIP and sinter approach, the powder is loaded into a latex cylindrical “can” and CIPed at 50,000 psi. The cylinders of compacted powder are then sintered at 1200 to 1400 C for 2 hours. The final compacts are then machined to shape. Alternatively the powders after freeze drying can be placed in a stainless steel cylindrical can and HIPed, for example, at 1100° C. and 15,000 psi for 11 hours, followed by machining to final shape. This is a significantly lower temperature than traditional HIP, which can occur at temperatures at or above 1700° C.
[0030] Preferably, the constituents in the tool are uniformly distributed throughout the composition. Uniform distribution can be quantified by measures described elsewhere herein. Alternatively, uniform distribution can be characterized by a coefficient of variation (COV) value as described by Yang et al. in “Simulation and quantitative assessment of homogeneous and inhomogeneous particle distributions in particulate metal matrix composites” (see Journal of Microscopy, Vol. 201, Pt 2, February 2011, pp. 189-200), which is incorporated herein by reference. A COV of mean near-neighbor distance (d-mean) can be a powerful parameter to identify homogeneity. In one instance, a COV d-mean value of 0.36 is preferred and can be a standard indication of homogeneity. Values departing from this standard can be acceptable depending on the needs of a particular FSW tool application (i.e., tool specifications versus cost considerations).
[0031] According to one embodiment, a combustion synthesis procedure can be used to produce an appropriate nanopowder from which a friction stir weld tool can be fabricated. A similar combustion synthesis procedure is described in U.S. patent application Ser. No. 12/700,923, which is incorporated herein by reference. In one example, a 93.9 wt % W-6.0 wt % Re-0.1 wt % Ni modified glycine nitrate process (GNP) powder was produced, which yielded approximately 100 g of a nano-particulate W—Re—Ni metal powder after reduction.
[0032] The reactants included standard grade Ammonium Metatungstate (AMT) {(NH 4 ) 6 H 2 W 12 O 40 ·5H 2 O; F.W.=3048.076 g/mole; % W by Wt.=72.38%} as a source of W, Nickel(II) Nitrate hexahydrate {Ni(NO 3 ) 2 ·6H 2 O; F.W.=290.81 g/mole; % Ni by Wt.=20.19%} as the source of Ni, and Ammonium Perrhenate (APR) {NH 4 Re O 4 ; F.W.=268.24 g/mole; Assay: % Re by Wt.=69.4%} as the source of Re. The reactants further included ethanolamine {(NH 2 ) CH 2 CH 2 OH; F.W.=61.09 g/mole}, 70% Nitric Acid Solution {HNO 3 ; F.W.=63.01 g/mole}, and deionized water. The amounts of reactants were determined as follows.
[0000] 93.90 g W÷0.7238=129.73 g (0.042561 mole) of AMT needed
[0000] 6.00 g Re÷0.694=8.65 g (0.032247 mole) of APR needed
[0000] 0.10 g Ni÷0.2019=0.50 g (0.001719 mole) of Ni(NO3)2·6H2O needed
[0000] AMT:APR:Ni(NO)3 molar ratio=1:0.758:0.040
[0000] In addition, the stable combustion synthesis solution comprised a molar ratio of AMT:Ethanolamine equal to 1:4.154. Therefore, the molar ratio of AMT:APR:Ni(NO 3 ) 2 :Ethanolamine was 1:0.758:0.040:4.154.
[0033] In order to produce the necessary stoichiometric burn when combusted, equal amounts of oxidizing and reducing capacity must be present in the combustion synthesis solution. Additional details regarding the determination of oxidizing and reducing capacities of various materials is provided by J. J. Kingsley and L. R. Pedersen in “Energetic Materials in Ceramic Synthesis” (Mat. Res. Soc. Symp. Proc. 296 (1993) 361-366), which details are incorporated herein by reference. Briefly, the molecular formulas of each of the reagents are determined to be either net oxidizing agents or net reducing agents on a per mole basis. The relative molar ratios of the reagents required for a stoichiometric burn can then be calculated. The oxidizing and reducing capacities for the reagents of the present example are determined as follows.
[0000]
For AMT = (NH 4 ) 6 H 2 W 12 O 40
N = 6 × 0 = 0
H = 26 × −1 = −26
O = 40 × +2 = +80
W = 12 × −6 = −72
Sum =
−18 per mole (net reducing)
For APR = NH 4 ReO 4
N = 1 × 0 = 0
H = 4 × −1 = −4
O = 4 × +2 = +8
Re = 1 × −7 = −7
Sum =
−3 per mole (net reducing)
For Ni(NO 3 ) 2
N= 2 × 0 = 0
O = 6 × +2 = +12
Ni = 1 × −2 = −2
Sum =
+10 per mole (net oxidizing)
For Ethanolamine = (NH 2 )CH 2 CH 2 (OH)
N = 1 × 0 = 0
H = 7 × −1 = −7
C = 2 × −4 = −8
O = 1 × +2= +2
Sum =
−13 per mole (net reducing)
For HNO 3
N = 1 × 0 = 0
H = 1 × −1 = −1
O = 3 × +2 = +6
Sum =
+5 per mole (net oxidizing)
For H 2 O
H = 2 × −1 = −2
O = 1 × +2 = +2
Sum =
0 per mole (inert)
[0034] Next, the components of the solution were compared and the required molar ratios were calculated for producing a stoichiometric burn ratio as follows:
[0000] 1 × AMT (@ −18 per mole) = −18 (net reducing) 0.758 × APR (@ −3 per mole = −2.274 (net reducing) 4.154 × Ethanolamine (@ −13 per mole) = −54 (net reducing) 0.040 Ni(NO3)2 (@ +10 per mole) = +0.40 (net oxidizing) −73.874 (net reducing)
For a stoichiometric burn, net oxidizers need to equal net reducers, therefore +73.874 of net oxidizers (HNO 3 in this case) also needs to be added to the solution. (+73.874÷+5 per mole of HNO 3 =14.775 moles of HNO3 per mole of AMT is needed).
The resulting solution comprised a molar ratio of AMT:APR:Ni(NO 3 ) 2 :Ethanolamine:HNO 3 equal to 1:0.758:0.040:4.154:14.775.
[0035] The combustion synthesis solution comprising the reactants in the amounts described above can be prepared in two steps. A first solution (Soln.A) is prepared by adding Ni(NO 3 ) 2 , ½ of the total amount of D.I. water, HNO3 solution, and ethanolamine, which is then set aside. A second solution (Soln. B) is prepared by dissolving the APR in the second ½ of the D.I. water while heating on a hotplate. Then, after all of the APR has dissolved, the AMT is added. The two solutions are then mixed together to obtain the final combustion synthesis solution. The amounts of materials used in the solution preparation are calculated as follows.
Solution A Ni Nitrate+½ of the D.I. Water+HNO 3 solution+Ethanolamine)
[0000]
1) 0.50 g of Ni(NO 3 ) 2 ·6H 2 O
2) 75 g of D.I. Water
3) 14.775×(0.042561 mole)×63.01 g/mole HNO 3 ÷0.70=56.60 g of 70 wt. % HNO 3 solution
4) 4.154×(0.042561 mole)×61.09 g/mole Ethanolamine=10.80 g of Ethanolamine
Solution B (APR+½ of the D.I. Water+AMT)
[0000]
1) 8.65 g of APR
2) 75 g of D.I. Water
3) 129.73 g of AMT
[0043] The combustion synthesis solution burn was carried out using a 4 L stainless steel beaker, which is heated on a hotplate to near red heat temperature. After the hotplate has heated the beaker bottom to near red heat, the entire combustion synthesis solution is quickly poured into the hot beaker, and the beaker is covered with a clean 100 mesh sieve to contain most of the solid particles produced, while allowing steam and combustion gasses to escape from the beaker. Steam is rapidly evolved for ˜8-10 minutes, then red colored NO x fumes are evolved as the combustion process begins to initiate. When the NO x evolution subsides, the beaker containing the porous ash is removed from the hotplate and allowed to cool to room temperature. Typically, the entire burn process can be completed within less than 15 minutes. After cooling, the ash is recovered from the beaker, and ground to a fine powder, typically dark blue in color. The finely divided powder was recovered and was ready to be reduced.
[0044] Referring to FIG. 1 , a scanning electron microscope (SEM) micrograph shows agglomerated crystallites directly after combustion synthesis (agglomerates are hundreds of nanometers across, but composed of <10 nm crystallites. The small sizes allow for unique behavior in compaction according to embodiments of the present invention.
[0045] For example, the nanopowders allow for higher sintered density at lower temperature and less time at temperature. The micrograph in FIG. 2A shows a 98.6% dense compact after sintering at 1400 C for 4 hours, which is a much lower temperature and a much shorter time than commercial products with large powder sizes traditionally require. FIG. 2B shows grain size at about 5-8 micron, which is much finer than the conventional processes produce, but not as fine as can be produced in optimized conditions of embodiments of the present invention. Furthermore, there is no need for additional processing to subsequently work the structure to reduce grain size from hundreds of microns to tens of microns at high temperatures, such as approximately 1800 C.
[0046] Synthesis of friction stir weld tools from nanopowders also allow for retaining fine grain size at high density with only very small (0.1%) Ni added (it is typically necessary to add Ni to get tungsten to sinter at low temperatures, but the grain size balloons up to hundreds of microns). The micrograph in FIG. 3 shows W-4% Re—HfC that shows greater than 90% density and WRe grain size below 900 nm by only CIP and sintering, without any post-densification working at elevated temperatures. Traditionally, one must put work into this alloy to get a grain size this small either through hot isostatic pressing, swaging, and/or extrusion.
[0047] Embodiments of the present invention can include a wet milling step before consolidation that dramatically improves densification and allows for retention of fine grain size. FIG. 4A includes micrographs showing a fractured surface at two levels of detail. FIG. 4B includes micrographs showing a polished surface at two levels of detail. The sample from which the micrographs were obtained was 96.8% dense and exhibited grain sizes near 100 nm. The micrographs exhibit the extremely small grain sizes and the high homogeneity of HfC particulate (see small black dots in FIG. 4B ) distribution, which can be characteristics of embodiments of the present invention.
[0048] Embodiments of the present invention also exhibit improved hardness. FIG. 5 includes a mapping of hardness from a W—Re—HfC friction stir weld tool that was prepared conventionally by sintering at a temperature greater than 2000 C and extruded at 1800 C. In comparison, a W-6Re-0.1Ni—HfC—CeO tool prepared according to embodiments of the present invention by sintering alone resulted in much higher hardness values across the mapping (see FIG. 6 ). The tool was ball milled with alumina media and heat treated at 1650 C for 2 hours.
[0049] While a number of embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the invention in its broader aspects. The appended claims, therefore, are intended to cover all such changes and modifications as they fall within the true spirit and scope of the invention.
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Tools for friction stir welding can be made with fewer process steps, lower cost techniques, and/or lower cost ingredients than other state-of-the-art processes by utilizing improved compositions and processes of fabrication. Furthermore, the tools resulting from the improved compositions and processes of fabrication can exhibit better distribution and homogeneity of chemical constituents, greater strength, and/or increased durability. In one example, a friction stir weld tool includes tungsten and rhenium and is characterized by carbide and oxide dispersoids, by carbide particulates, and by grains that comprise a solid solution of the tungsten and rhenium. The grains do not exceed 10 micrometers in diameter.
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This is a continuation of application Ser. No. 105,046, filed Dec. 18, 1979, now abandoned.
FIELD OF THE INVENTION
The invention relates to a preassembled zero insertion force (ZIF) electrical circuit board connector in which electrical terminals are to be driven into apertures of a circuit board with a compression fit.
BACKGROUND OF THE PRIOR ART
A circuit board connector typically comprises an elongated, rigid dielectric housing containing one or more rows of leaf spring electrical terminals. A card edge type connector is adapted with a receptacle opening into which may be plugged a circuit card having conductive circuits thereon for frictional and electrical engagement by the leaf spring terminals. A stackable connector is adapted to receive conductive electrical post terminals of another circuit board connector into the receptacle opening for frictional and electrical engagement by the leaf spring terminals. Either type of circuit board connector may be a ZIF type wherein the housing is provided with a camming mechanism which resiliently deflects the leaf spring terminals away from the receptacle opening, to allow entry of the circuit card or conductive terminals without undue frictional engagement by the leaf spring terminals. The camming mechanism releases the leaf spring terminals so that they resiliently spring into frictional engagement with the card or the post terminals.
A ZIF connector is mounted on a circuit board by its leaf spring terminals, which extend below the connector housing and which are driven into apertures of the circuit board with a compression fit. Some circuit board mounted connectors are sufficiently rugged to withstand forceful driving of the terminals into circuit board apertures, even with the connector housing preassembled over the terminals. However, the trend toward miniaturization in electronic circuits has necessitated connectors which are not adaptable for preassembly, prior to driving the terminals in a circuit board. Miniaturized connectors are less rugged and are provided with thinner, more densely spaced terminals. A larger number of terminals is allowed by dense spacing, with larger forces needed to drive the terminals into a circuit board. The densely spaced, fragile terminals are susceptible to damage by slightly misaligned insertion tooling. If the terminals are preassembled in a connector housing, the presence of the housing provides a further impediment to alignment of the insertion tooling. Replacing a terminal damaged by the insertion procedure is further impeded by presence of the housing. Accordingly, the accepted assembly procedure has heretofore required insertion of the terminals while they remained separate from the housing and still connected to a carrier strip. One example of a machine for inserting the terminals is disclosed in U.S. Pat. No. 3,875,636. Following insertion of the terminals, the carrier strip was removed and the connector housing then was carefully assembled onto the terminals. An example of such a housing is disclosed in U.S. Pat. No. 3,905,665. The housing has an open bottom allowing the housing to pass freely over the inserted terminals. A latching finger is molded to the housing which latches to one of the terminals, thereby retaining the housing in place.
SUMMARY OF THE INVENTION
The present invention relates to an improved circuit board connector of the stacking type, which also may be modified to serve as a card edge type. The terminals of the connector are preassembled in the connector housing. Each terminal is designed with a tool rest. An insertion tool is provided with multiple blades which may enter the housing to engage the tool rests of the terminals and collectively drive the terminals into a circuit board.
Additionally, the connector comprises a ZIF type, which may be preassembled without special tools. The camming mechanism of the connector is readily disassembled for replacement of a damaged terminal, or for other repairs. In a specific form of the connector, a shroud portion of the mechanism is pivotally mounted on fulcrum tabs molded integrally with the housing. Resilient fingers, also integrally molded, bias the shroud into pivotal engagement with the fulcrum tabs. Also, the leaf spring terminals of the connector coact with the resilient fingers to bias the shroud into engagement with the fulcrum tabs. The resilient fingers are deflected to allow snap on, snap off mounting of the shroud.
OBJECTS
An object of the present invention is to provide a circuit board connector adapted for assembly of all component parts prior to precisely aligning insertion tooling with the terminals of the connector and driving the terminals collectively into respective apertures of a circuit board with a compression fit.
Another object of the present invention is to provide a circuit board connector having a housing, leaf spring terminals and a camming mechanism for the terminals, all of which are preassembled prior to driving the terminals collectively into respective apertures of a circuit board with a compression fit.
Another object is to provide a circuit board connector with an assembly of a housing and leaf spring terminal which are formed with tool rests to be engaged by insertion tool blades which may enter the housing, register precisely with the terminals and drive the terminal collectively into respective circuit board apertures with a compression fit.
Another object is to provide a ZIF connector with terminals preassembled in a housing molded with integral fulcrum tabs and integral fingers, which resiliently bias a snap on, snap off shroud portion of a terminal biasing cam mechanism into pivotal connection with the fulcrum tabs.
Another object is to provide a ZIF connector with preassembled terminals, housing and a cam mechanism of which a snap on, snap off shroud portion is resiliently biased into pivotal mounting on the housing by resiliency inherent in the terminals, coacting with resilient fingers molded integrally with the housing.
Other objects and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanyng drawings.
DRAWINGS
FIG. 1 of the drawings is an enlarged fragmentary perspective of a ZIF type circuit board connector comprising a preferred embodiment of the present invention.
FIG. 1A is a reduced fragmentary perspective of a cam of the connector illustrated in FIG. 1.
FIG. 2 is an enlarged fragmentary transverse section of the elongated connector illustrated in FIG. 1, and illustrating more particularly a multiple blade insertion tool for collectively driving the electrical terminals of the connector into respective apertures of a circuit board.
FIG. 3 is an enlarged section similar to FIG. 2 illustrating two electrical connectors of the preferred embodiment in stacked relationship, with the terminals of an upper connector inserted into the lower connector and frictionally engaged by the terminals of the lower connector.
FIG. 4 is a section similar to FIG. 2 illustrating a terminal camming feature of the connector illustrated in FIG. 2.
FIG. 4A is a fragmentary enlarged section taken generally along the line 4A of FIG. 2.
FIG. 4B is a fragmentary enlarged section similar to FIG. 4A, and taken generally along the line 4B of FIG. 4.
FIG. 5 is a fragmentary enlarged transverse section similar to FIG. 2 illustrating assembly of a snap on, snap off shroud portion of the connector.
FIG. 5A is an enlarged fragmentary section taken along the line 5A of FIG. 5.
FIG. 6 is an enlarged perspective of a terminal according to the present invention.
FIG. 7 is an enlarged transverse section of a connector shown in FIG. 1 modified to serve as a card edge ZIF connector.
DETAILED DESCRIPTION
With more particular reference to FIG. 1 of the drawings, a stackable, ZIF type, circuit board connector is generally shown at 1. FIG. 6 shows an electrical terminal 2 for use in the connector 1, stamped and formed from metal stock into a leaf spring configuration. An upper free end 4 is formed with a reversely curved shape, defining a curved recess portion 6 adjacent a curved projecting portion 8, which is the engaging electrical contact portion of the terminal. A substantial lengthy section of the terminal 2 is widened as shown at 10. A vertical slot 12 is provided along the widened section 10, particularly along an arcuate part 14 of the section 10. The lower end of the slot is defined by a rounded, end wall 16, providing a tool rest, for a purpose to be described. Below the slot 12, yet in the widened section 10 of the terminal, a spur or lance 18 is formed, by punching the outline of three sides of the lance, and then bending the outlined lance to project the same out of the thickness plane of the terminal. Below the widened section 10, the terminal has a split section formed into a pair of offset legs 20 which are adapted for frictional, wedged retention in an aperture of a circuit board. The upper end of the terminal is adapted for mounting in the connector 1. A lower end 22 of the terminal 2 is adapted to project outwardly from a circuit board in which the legs 22 are mounted, and to provide a circuit path conductor, which can be pluggably inserted into another stackable, ZIF type, circuit board connector 1, and be electrically engaged by a corresponding terminal of that connector.
Details of the connector 1 will be described with reference with FIGS. 1, 1A, 5 and 5A. A housing portion generally indicated at 24 is of unitary, molded plastic construction, and includes a pair of parallel, horizontally elongated side walls 26, and a central barrier wall 28 parallel with the walls 26. The barrier wall is molded at each end with an end wall 29. In the stackable version of the ZIF connector, receptacle openings are in the form of a row of vertical cavities 30 molded along each side of the barrier wall 28, with adjacent cavities 30 being separated by molded, vertical webs 32 bridging between, and integrally joining, the wall 28 with an outer wall 26.
As shown in FIGS. 5 and 5A, each web 32 has a lower, thickened web portion 34. Vertical slots 34A are recessed in the web portions 34. Each cavity 30 has a smaller sized cavity portion 30A passing between adjacent thickened web portions 34. The barrier wall 28 is provided with a vertical slot 28A communicating with each cavity portion 30A.
As shown in FIGS. 1 and 5, along the bottom length of each side wall 26, is molded a thickened wall portion 36 provided with a series of vertical slots 38. A series of thin, and thereby stiffly resilient, fingers 40 are molded to project outwardly from the slots 38, and outwardly past the thickened wall portion 36. Each finger cups upwardly with a smoothly curved, S-shape. Also projecting outwardly past the wall portion 36 is a series of fulcrum tabs 42 of inverted hook configurations, molded integrally with the wall portion 36. A horizontal shelf 44 is provided along the top of each wall portion 36. Along the top length of each side wall 26 is molded a series of wedge shaped projections 46, spaced above a corresponding shelf 44.
With reference to FIGS. 5, 5A and 6, assembly of the terminal 2 into the connector 1 will be described. A terminal 2 is inserted vertically downward along each corresponding cavity 30. As shown in FIG. 5A, the widened section 10 of the terminal slidably interfits within corresponding slots 34A in the webs 34. The lance 18 of the terminal wedges against the wall defining the cavity portion 30A. Thereby, the terminal is locked into a position of stable support. The cavity portion 30A comprises a terminal receiving cavity portion which opens vertically upward into the remainder of cavity 30 which defines a receptacle opening of the connector 1 into which the contact section 8 of the terminal 2 projects. The free end 4 of the terminal projects vertically upward beyond the sidewall 26.
With more particular reference to FIGS. 1, 1A and 5, a molded unitary cam, generally shown at 48, includes a pair of parallel, elongated cam blades 50 integrally joined by a vertical end wall 52 which, in turn, is joined to a horizontal platform portion 54. A handle 56 is molded to join the wall 52 and the platform 54. The platform 54 is provided with an inverted track 58 which, as shown in FIG. 1, is slidably assembled along an elongated rail 60 molded integral with, and projecting from, one end wall 29 of the housing 24. Each blade 50, as shown in FIG. 1A, is provided with a series of wedge shaped sections 62 horizontally, one behind the other. Each wedged shaped section 62 terminates in a projecting, vertical stop wall 64. The cam 48 is assembled to the housing 24 as shown in FIG. 1A with the track 58 slidably assembled over the rail 60, and with the cam blades 50 slidably received and seated against the horizontal shelves 44. The inclined surface of each wedged shaped section 62 slideably registers against a corresponding projection 46 on each housing side wall 26.
As shown in FIGS. 1 and 5, a molded dielectric shroud 66 is assembled to the housing 24, covering each cam blade 50. Each shroud is molded with a top wall 68 which is offset with a vertical portion at 70, hooked over the projecting free ends 4 of a row of terminals 2, and registered within the recess portions 6 of the terminals. The shroud further is molded with an elongated side wall 72 that is provided with a series of apertures 74 defining tapered horizontal lip portions 76 at the lower peripheries of said apertures. The shroud is hooked over the terminal ends 4 in registration with the recess portions 6, and then pivoted toward the wall 36 of the housing 24. The bottom edge 78 of the shroud will engage and resiliently deflect the free ends of corresponding fingers 40 resiliently downward vertically, allowing the apertures 74 to align with and snap over the fulcrum tabs 42. The contact ends 4 also are deflected slightly to allow the fulcrum tabs 42 to align with the apertures 74. The stored resilient energy in each of the spring contacts continuously tends to lift the shroud 66, hooking the tapered lip portions 76 under the fulcrum tabs 42. Such lifting action coacts with the lifting action of the series of fingers 40 which continuously, resiliently impinge against a bottom edge 78 of the shroud. The shroud is readily disassembled by prying the edge 78 until it snaps outwardly from the fulcrum tabs and the fingers, and then removing the shroud from the assembly. The terminals 2 are exposed for selective removal by any suitable tool with a fishhook shaped blade, not shown, hooked into the recess 12 of a selected terminal and pulled to remove the terminal.
FIG. 2 illustrates the completed assembly of the connector 1. Additionally, the connector is illustrated with an insertion tool 80 in the form of an elongated, rectangular in section, anvil block 82 provided with rows of depending insertion blades 84 corresponding to the number of terminals 2 in the housing 24. Each insertion blade 84 is of a size to be inserted freely into a corresponding receptacle opening 30. Each blade passes between a contact 2 and the central barrier wall 28. The tip or end of each blade enters a corresponding terminal aperture 12 and seats against a tool rest 16 of each terminal. The tips are complimentary in shape to the rounded configuration of the tool rests 16. A downward force applied to the anvil causes each blade to press each of the terminals vertically downward to insert and wedgingly register the terminal legs 20 frictionally within the apertures 86. Considerable force is required to drive all the terminals into the circuit board apertures. The forces are applied directly to the terminals only, leaving the remaining components of the connector 1 free from possible damage. The insertion blades 84 also are supported against the central barrier 28 to prevent their buckling. The terminals 2 resiliently press against the blades 84 supporting the blades against the wall 28. Each blade 84 is independently adjustable by slight deflection to align in the cavity and seat properly with a corresponding terminal tool rest.
FIG. 4 illustrates the camming action of the connector 1. The cam 48 is slid along the rail 60 in the direction of the arrow 90 in FIG. 1, causing the cam blades 50 to slidably traverse over the walls 44. The relatively thick portions 62A of the wedge sections 62 will overlie the projections 46, wedging apart the shrouds 66 from the housing walls 26. To prevent inadvertent removal of the cam blades, the walls 64 register against the projections 46 to limit sliding displacement of the cam blades 50. The shrouds 66 will pivot about the fulcrum tabs 42. Since the shrouds are hooked over the terminal ends 4, pivoting the shrouds will tend to deflect the terminals toward one side of each corresponding receptacle opening 30. In this manner, circuit path conductors may be readily inserted into the corresponding receptacle opening 30 without undue frictional engagement against the terminals 2.
FIG. 3 shows a pair of connectors 1 of the type described. The circuit path conductors, inserted into the receptacle openings 30 of the lower illustrated connector, are portions 22 of the terminals 2 of the other connector 1. Therefore, the connector 1 described is a stacking ZIF type circuit board connector. The terminals 2 of the lower connector 1 frictionally engage the terminal portions 22 of the upper connector 1. This is accomplished by slidably displacing the cam blades 50 until the relatively thinner dimension 62B, of the wedge sections 62 are impinged against the series of projections 46. When this occurs, the cam blades 56 will register against the walls 26, allowing the terminals 2 to deflect by their stored spring energy into engagement with the inserted circuit path conductor portions 22. Such deflection of the terminals also will pivot the shrouds to their positions shown in FIGS. 3 and 4A.
FIG. 7 illustrates a modified connector 1A in which the central barrier wall 28 terminates inside the connector housing 26. The portion 90 of the wall 28 forms a bottom of a single receptacle opening 30 running the length of the connector housing 26. A planar circuit board 92 having plated circuit path conductors 94 thereon is insertable into the corresponding receptacle opening 30 until it registers against the bottom 90. Subsequently, the terminals 2 may deflect resiliently toward the wall 28 in a manner described in conjunction with FIG. 3, to frictionally engage the conductors 94. When using the multiple blades of the insertion tool, it is desirable to insert a shim block between the rows of blades to simulate the central barrier wall 28 which is absent from the connector 1A.
Although preferred embodiments of the present invention are disclosed in detail, other embodiments and modifications thereof which would become apparent to one having ordinary skill in the art are intended to be covered by the spirit and scope of the appended claims.
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A zero insertion force (ZIF) connector is preassembled with electrical terminals in a dielectric housing. The housing is molded with integral features that facilitate snap on assembly of a camming mechanism for the terminals. A multiblade insertion tool enters the housing to register with the contacts and to drive the terminals into apertures of a circuit board.
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