Method of and Machine for Grinding a Workpiece

Technical Field

Our invention relates to a machine for regrinding grooves of a constant velocity universal joint workpiece.

Background Art

Constant velocity universal joints are used in the wheel drive axle of front wheel drive automobiles; these joints are well known to those skilled in the art and are described, e.g., in United States patents 4,177,654, 4,300,651, 4,476,950, and 4,634,402, the disclosure of each of which is hereby incorporated by reference into this specification.

The constant velocity universal joints often are damaged during use. However, because of the relatively high cost of the precision machined components in such joints, the complete replacement of the joint is very expensive.

United States patent 4,593,444 of Kavthekar discloses a machine for manufacturing constant velocity universal joints. The Kavthekar machine requires the use of a plurality of ma¬ chining stations (and, thus, a plurality of tools). Further¬ more, because the Kavthekar machine is designed for the origi¬ nal manufacturing of such joints, it relies upon the keyway of the original blank for positioning a workpiece in the machine. Furthermore, the Kavthekar machine does not contain means to move its grinding spindle in a vertical direction, or means to stop and lock its swing arm in a precise angular position relative to the axis of the grinding spindle; thus, this machine cannot be used to effectively regrind a Cross Groove style or a Plunge style constant velocity joint, and it cannot be used to grind the ball openings of the hardened cage. Furthermore, the Kavthekar machine does not contain means for calibrating the position of any given tool in relationship to

the center of rotation in order to insure that precise dimen¬ sions are being machined.

It is an object of this invention to provide a machine for regrinding a variety of worn constant velocity components to within manufacturer's original tolerances or better, wher¬ ein the original ball bearings are replaced by oversized ball bearings of a common size for a particular type and size constant velocity joint.

It is another object of this invention to provide a machine for regrinding the individual components of a constant veloci¬ ty universal joint which ensures precision grinding by coop¬ erative movement of a workpiece table and grinder table through a predetermined and controlled pattern of positions without interruption of the process for the purpose of moni¬ toring the dimensions of the component being ground.

It is yet another object of this invention to provide a machine which regrinds worn or damaged constant velocity universal joints to consistent, precise, and improved toler¬ ances between the ball bearings and the inner and outer races. It is yet another object of the invention to provide a grinding machine with a novel arrangement of workpiece holder and tool holder which is capable of rotating various types and sizes of constant velocity universal joints through predetermined patterns of movements to accomplish precision grinding of various individual components.

It is yet another object of this invention to provide a machine which automatically performs the operations necessary to accomplish precision regrinding of the individual compon¬ ents of various types and sizes of constant velocity universal joints.

It is yet another object of this invention to provide a single station machine which can perform multiple operations on workpieces of various types and sizes, with the aid of specially designed adaptors.

It is yet another object of this invention to provide a

comprehensive data base and catalog for the purpose of identi¬ fying constant velocity universal joints, combined with the appropriate information and dimensional locations for automat¬ ic positioning of all axis of motion required for the regrind¬ ing process.

Disclosure of invention

In accordance with this invention, there is provided a machine for regrinding grooves of a constant velocity univer¬ sal joint workpiece. This machine preferably contains a chuck mechanism for holding the various workpieces of the constant velocity universal joint, an adaptor for mounting the work¬ piece in the chuck mechanism, a rotatable arm for supporting the chuck mechanism, means for controlling the motion of the rotatable arm in accordance with a computer program, a motor¬ ized grinding spindle with a grinding bit, a lubricating fluid injection system, and a protective enclosure.

Brief Description of Drawings

The details of our invention will be described in connection with the accompanying drawings, in which:

Fig. 1 is a perspective view of one preferred embodiment of the regrinding machine assembly of this invention;

Fig. 2 is another perspective view of one portion of the assembly of Fig. 1;

Fig. 3 is another perspective view of the assembly of Fig. l;

Fig. 4 is a sectional view of a constant velocity universal joint;

Fig. 5 is an exploded view of a Rzeppa constant velocity universal joint;

Fig. 6 is an exploded view of an In-Line constant velocity universal joint;

Fig. 7 is an exploded view of a Skewed Groove Disk constant velocity universal joint;

Fig 8 is an exploded view of a Tripod constant velocity universal joint;

Fig. 9 is a schematic perspective view of the workpiece and grinding bit of the assembly of Fig. 1, with the outer race component of the Rzeppa constant velocity joint mounted for grinding and shown in the starting position;

Fig. 10 is a schematic perspective view of the assembly of Fig. 9, shown midway through the grinding process;

Fig. 11 is a schematic perspective view of the assembly of Fig 9, shown at the innermost position;

Fig. 12 is a schematic perspective view of the workpiece and grinding bit with the outer race component of the In-Line constant velocity joint, mounted for grinding and shown in the starting position;

Fig. 13 is a schematic perspective view of the assembly of Fig. 12, shown in the innermost position;

Fig. 14 is a schematic perspective view of the workpiece and grinding bit with the outer race component of the Skewed Groove Disk constant velocity joint, mounted for grinding and shown with the grinding bit in the starting position for the right skewed groove;

Fig. 15 is a schematic perspective view of the workpiece and grinding bit with the outer race component of the Skewed Groove Disk constant velocity joint, mounted for grinding and shown with the grinding bit in the starting position for the left skewed groove;

Fig. 16 is a schematic perspective view of the workpiece and grinding bit with the inner race component of the Rzeppa constant velocity joint mounted for grinding and shown in the starting position;

Fig. 17 is a schematic perspective view of the rotatable arm, the workpiece and the grinding bit with the intermediate bearing retainer mounted for regrinding;

Fig. 18 is a plan view of the cage adaptor assembly;

Fig 19 is a sectional view of the outer race spacer;

Fig. 20 is a plan view of the inner race spacer; Fig. 21 is a view of the inner race expanding mandrel; Fig. 22 is a view of the horizontal alignment adaptor; and Fig. 23 is a flow chart illustrating computer controlled operations according to one preferred method of the invention.

Best mode for carrying out the invention

Figure 1 is a representational perspective view of one preferred embodiment of grinding machine assembly 10. Assem¬ bly 10 preferably comprises grinding machine 20 and micropro¬ cessor 11; and these components are preferably maintained within cabinet 15.

Referring to Figure 1, it will be seen that, within cabinet 15, grinding machine 20 is preferably partially enclosed by protective enclosure 16, which prevents the lubricating medium from escaping to the outside environment as it is sprayed onto the workpiece and the workpiece table. In one preferred embodiment, protective enclosure 16 is a sheet of flexible material which not only facilitates sealing but also deforms in order to admit to small displacements of grinding bit 28, in the X and Y plane, in order for grinding bit 28 to be repositioned prior to regrinding workpiece 36.

Again referring to Figure 1, it will be seen that grinding machine 20 is preferably comprised of a hose and nozzle ar¬ rangement 18 which permits the user to wash away grinding residues from the surfaces of the grinding machine 20 with the aid of supply conduit 29. These residues are then carried into a recycling reservoir (not shown) where the coolant medium is cleaned and decontaminated.

Also illustrated in Figure 1 is monitor 12, which, in response to requests from the grinding machine operator, can display information regarding the particular component part, or workpiece, which is to be reground. In the preferred embodiment illustrated in Figure 1, the grinding machine operator may input information through keypad 13. In this

embodiment, the microprocessor 11 retrieves data regarding the specifications for the particular constant velocity universal joint component part being reground from a database in a micro floppy disk. The information is processed by the microprocessor, resulting in the initiation of the appropriate grinding sequence and precise axis positioning.

Referring again to Figure 1, and in the preferred embodiment illustrated therein, it will be seen that emergency stop button 14, when depressed, will immediately remove the electricity and the air pressure from all of the components of the grinding machine assembly 10. Emergency stop button 14 is preferably incorporated into cabinet 15, within the panel of switchgear 19 which provides electricity for the electronic components which serve to supply energy to the electrically operated parts of the grinding machine, and the assorted hydraulic and/or pneumatic components.

Figure 2 is a perspective view of a preferred embodiment of grinding machine 20, which is comprised of a grinding station 17 situated upon a base 22. The grinding station 17 includes workpiece table 31 which is movably mounted upon a first set of elongate bars 24 opposite grinder table 23. Supply conduit 29 is part of a lubricating fluid injection system and is supported by the grinder table; it directs a stream of liquid coolant into the regrinding operation in order to wash away waste material, shavings, and particles of ground metal and to cool grinding bit 28 during regrinding. The lubricating fluid injection system also includes a means to pump the liquid coolant from its source through the supply conduit.

The workplace table 31 is comprised of rotatable arm 32, upon which is mounted chuck mechanism 33. Chuck mechanism 33 is the preferred means for receiving the workpiece 36 and, with the aid of adaptor 41, accommodates the workpiece 36. In one preferred embodiment, the workpiece 36 is any one of the various components of a constant velocity universal joint.

Referring again to Figure 1, it will be seen that the

grinder table supports grinder spindle 25. Spindle 25 is connected to prime mover 26 which is coupled to variable chuck mechanism 27. Chuck mechanism 27 is the preferred means for _fc receiving the grinding bit 28.

In the preferred embodiment, the prime mover is a constant high speed motor. The variable chuck mechanism holds the grinding bit which is preferably made of "BORAZON," or a like material. The grinding bit is preferably replaceable; howev¬ er, in one preferred embodiment, the grinding machine is comprised of a means to compensate for the resulting deterio¬ ration of the grinding bit due to successive regrindings. Moreover, because the length of the grinding bit affects the depth of regrinding, the position of the grinding bit must be adjusted relative to the workpiece in order to compensate for a change in the length of the grinding bit. Before the re¬ grinding operation begins, the appropriate grinding bit is inserted loosely into the variable chuck mechanism 27 and the workpiece table 31 is positioned in relationship to the grind¬ ing bit 28, with a reference surface 21 oriented towards the grinding bit. The grinding bit is then pulled out of the variable chuck mechanism 27 until it is solidly against refer¬ ence surface 21. Then the variable chuck mechanism 27 holding the grinding bit is tightened.

Empirical tests have shown that, with the grinding bit sized properly, very precise control of the regrinding opera¬ tion is obtained to a tolerance of plus or minus one thousandth of an inch.

_^ Figure 3 is a perspective view of grinding machine 20 illustrating the components of workpiece table 31 and grinder . table 23 as they are engaged in the grinding of workpiece 36.

Referring to Figure 3, it will be seen that workpiece table 31 is supported for movement over the length of base 22 by a first set of elongate bars 24 which are preferably precisely aligned parallel to the axis of travel on the workpiece table. Actuator 46 moves the workpiece table 31 toward and away

from the grinder table 23 along the axis indicated by the double-headed arrow labeled 47 (the X-axis).

The grinder table 23 is supported for movement over the width of the base by a second set of elongate bars 39, which are preferably precisely aligned to the axis of travel of the grinder table and perpendicular to the axis of travel of the workpiece table.

The grinder table is reciprocally movable along an axis, indicated by a double-headed arrow labeled as 49 (Y axis), which is preferably precisely at a right angle to the X-axis, the axis of travel of the workpiece. In the preferred embodi¬ ment illustrated in the Figure, stepper motor 37 provides a means to effect the movement of the grinder table along the Y axis. In an alternative embodiment, position readout 38 provides a means to precisely measure the position of the grinder table in relation to the position of the workpiece.

The second set of elongate bars 39 is attached to a sub- base 40, which is able to be positioned in either the same plane with respect to the base, or in a plane perpendicular to the first set of elongate bars 24. When the sub-base 40 is positioned in the same plane as the first set of elongate bars 24, the stepper motor 37 causes grinder spindle 25 to move front to back on the Y-axis. However, when the sub-base 40 is positioned in the plane perpendicular to the first set of elongate bars, the stepper motor 37 causes the grinder spindle 25 to move either up or down on the axis indicated by the double headed arrow labeled 51 (the Z-axis).

In one embodiment of the invention, the grinder table 23 is equipped for controlled simultaneous movement along both the Y axis and the Z-axis.

In one preferred embodiment, the grinding machine 20 is adapted to automatically regrind the components of a variety of constant velocity universal joints. The particular work¬ piece 36 to be reground is maintained on the workpiece table 31 by chuck mechanism 33 and adaptor 41. As will be apparent

to those skilled in the art, the embodiment of the adaptor to be used will depend upon the type of workpiece being reground.

Figure 4 is a cross-sectional view of a typical constant velocity universal joint 1, the components of which include outer race 2 (which is typically connected to the front wheel components by means of a splined trunion) , inner race 3 (which is typically connected to the vehicle transmission output by means of a splined receptacle) , intermediate bearing retainer 8, and ball bearing 5. These components, in combination, constitute a sliding joint which accommodates vertical and horizontal misalignment between the vehicle transmission and the front wheel drive components and, thus, permits the turn¬ ing of the front wheels for steering.

Referring again to Figure 4, a typical constant velocity universal joint is assembled such that the ball bearings fit closely within radial circular grooves 4 which are machined in the inner surface of the outer race and in the outer surface of the inner race. This design permits the ball bearings to roll forward and backward in the radial circular grooves as input shaft 6 is turned out of axial alignment with output shaft 7 but prevents the ball bearings from vertical to hori¬ zontal motion relative to the radial circular grooves' central axis.

The intermediate bearing retainer is machined with openings 51 (see Figure 5) on its surface so that it can retain the ball bearings within the radial circular grooves and between the outer race and the inner race.

Referring again to Figure 4, it will be seen that boot 9, which preferably is made of rubber or like material, is tight¬ ly affixed to the outer surface of the constant velocity universal joint and the output shaft in order to protect the assembly.

It will be apparent to those skilled in the art that Figure 4 is merely illustrative of the typical components of a con¬ stant velocity universal joint and that several different

kinds of constant velocity universal joints exist. The grind¬ ing machine of this invention is easily adaptable to regrind the components of any one of a number of constant velocity universal joints, some of which are discussed below.

Figure 5 illustrates a typical Rzeppa constant velocity universal joint la. Like the typical constant velocity univer¬ sal joint discussed in Figure 4, the components of this Rzeppa joint include outer race 2a, inner race 3a, and intermediate bearing retainer 8a. Radial circular grooves 4a, 4b, and 4c, discussed previously with reference to Figure 4, are also illustrated in Figure 5.

Figure 6 illustrates an In-Line constant velocity universal joint 92 which includes outer race 72, and intermediate bear¬ ing retainer 93. The joint is similar to the one illustrated in Figure 4 except the grooves 74 of the outer race do not have a radius of curvature.

Figure 7 illustrates Skewed Groove Disk constant velocity universal joint 94. In this type of constant velocity univer¬ sal joint, outer race 62 contains grooves 64a and 64b. The three grooves 64a are skewed clockwise; the other three grooves 64b are skewed counterclockwise. The grooves 64a and 64b do not have a radius of curvature as do the grooves 4 in the outer race of the constant velocity joint of Figure 4. Inner race 65 is similar to the inner race of the constant velocity joint of Figure 4 except that grooves 63a and 63b are angled either clockwise or counterclockwise. This type of constant velocity universal joint also includes intermediate bearing retainer 95.

Figure 8 illustrates a fourth type of constant velocity universal joint, the Tripod constant velocity universal joint 91. This Tripod constant velocity universal joint is comprised of outer race 96 and inner roller bearings 97 The outer race can easily be reground in a typical fashion by the grinding machine of this invention. The inner roller bearings, howev¬ er, are preferably not reground but instead are replaced with

new and larger inner roller bearings.

It will be apparent to those skilled in the art that the grinding machine of this invention, although adapted to regrind the components of the four constant velocity universal joints discussed above, is in no manner limited to regrinding only these components. Referring to Figure 2, it will be seen that the grinding machine 20 is adapted to operate as a single grinding station with the ability to regrind a variety of workpieces with only one tooling implement, grinding bit 28. The various regrinding operations are automatically achieved by the coordinate efforts of the microprocessor 11 (see Figure 1), a database (not represented pictorially) , and a control unit (not represented pictorially) . The database is comprised of a collection of manufacturing specifications for a variety of constant velocity universal joint models.

A means for controlling the motion of rotatable arm 32 is illustrated in part in Figure 3. In coordination with the microprocessor 11 (see Figure 1), a control unit (not repre¬ sented pictorially) controls the motion of rotatable arm 32. The control unit sends and receives signals to or from some or all of the moving parts illustrated in Figure 3 such as, e.g., prime mover 26, second actuator 46 (which is used for moving workpiece table 31 towards or away from grinding bit 28) third actuator 37 (which is used for rotating the rotatable arm 32 around its center of rotation 45, which causes the workpiece to be moved through a radius, indicated by the double-headed arrow 43, in relationship to the grinding bit 28), stepper motor 37 (which is used to move grinder table 23 from front to back or up to down) , first actuator 42 (which is used to increment the workpiece to one of several precise sequential positions about its center axis and in a radius indicated by the double headed arrow labeled 39, and means to pump coolant solution to the supply conduit 29.

The information in the database is used to program into the control unit the pattern through which the workpiece moves in

relation to the replaceable grinding bit 28 during the re¬ grinding operation. The control means and the first actuator are the preferred means for rotating the workpiece through a predetermined pattern. In a typical regrinding operation, the control unit transmits and receives a series of signals which cause the grinder table, the grinder spindle, and the replace¬ able grinding bit to be moved along the Y and/or Z axis and into their proper position, the rotatable arm to be rotated into a starting position, the grinder motor and means to pump coolant solution to the supply conduit to be turned on, and the workpiece table to advance towards the replaceable grind¬ ing bit in the predetermined sequence and at predetermined intervals as required by the particular type and size of the constant velocity universal joint component being reground.

Referring again to Figure 3, and by way of illustration, the following discussion illustrates one preferred procedure for regrinding outer race 2a(see Figure 5) of the Rzeppa constant velocity universal joint la (see Figure 5). The workpiece 36 is inserted into the chuck mechanism 33 using an adaptor such that the center of the radius of grooves 4a(shown in Figure 5) is directly and precisely over the center of rotation of the chuck mechanism 33. Outer race spacer 53 (shown in Figure 19) is the preferred adaptor for this compon¬ ent. The chuck mechanism 33 is loosely closed around the splined shaft of the outer race in order to permit the turning of the outer race in the chuck mechanism. A dial indicator (not shown pictorially), or another means (such as the hori¬ zontal alignment adaptor shown in Figure 22) is then used to locate and position the central axis of two opposite grooves 4a in precise alignment horizontally with the center of grind¬ ing bit 28 along the Z-axis as the outer race is turned in the loosened chuck mechanism. The chuck mechanism is then tight¬ ened and the horizontal alignment adaptor removed to enable the regrinding operation to begin.

Next the workpiece table is moved along the X axis and

rotated about the center of rotation indicated by double- headed arrows 43 to position the outer race at a point at which the head of the grinding bit 28 is at a point which will grind the proper depth into the outer race as the outer race is rotated around the tip of the grinder bit. Upon initiation of the automatic grinding sequence regulated by the control unit, the position of the outer race is automatically rotated slowly around the center of rotation 45 with the grinding bit rotating at high speed until the grinding bit has traveled forward and back through a given arc into the groove of the outer race.

This process for regrinding one of the grooves of the outer race of the Rzeppa joint is further illustrated by Figures 9, 10, and 11. Figure 9 is a schematic perspective view with outer race 2a of the Rzeppa constant velocity joint mounted for grinding with grinding bit 28 in the starting position. Figure 10 shows outer race 2a and grinding bit 28 midway through the grinding process. Figure 11 illustrates the regrinding at the innermost position. Once this process is completed, the workpiece is then returned to its starting position with the head of the grinding bit in front of the outer race 2a.

To regrind the next groove, the control unit transmits a signal to the chuck mechanism 33 to increment the position of the outer race about the center axis of the workpiece, as indicated by double-headed arrows 39, until the next groove of the outer race is sequentially placed into position engaging the grinding bit, and then the procedure illustrated in Fig¬ ures 9, 10, and 11 is repeated. The complete grinding se¬ quence is repeated until all grooves have been ground identi¬ cally and precisely to exacting tolerances.

In view of the fact that the features of the various con¬ stant velocity universal joints vary, the regrinding pro¬ cedures need to be varied also. This requirement poses no problem for the grinding machine because, based on the data

input by the grinding machine operator, the appropriate re¬ grinding procedure can easily be determined and relayed to the grinding machine through the microprocessor and the control unit.

By way of further illustration, in order to regrind race 72 (see Figure 6) and/or other components of the In-Line constant velocity universal joint, the rotatable arm 32 is moved into engagement with the workpiece and locked into place, with the grooves 74 precisely in line with the grinding bit. The workpiece is then advanced to the grinding bit and slowly advanced forward to allow the grinding bit to regrind each groove in a fashion similar to that used in the regrinding of the Rzeppa constant velocity joint (see Figure 5) except that the rotatable arm does not rotate during the grinding opera¬ tion. This procedure is illustrated in Figures 12 and 13. Referring to Figure 12, grinding bit 28 is in its starting position, with outer race 72 mounted for regrinding. Figure 13 illustrates outer race 72 and grinding bit 28 during re¬ grinding at the innermost position. Once these procedures are completed, the outer race 72 is then turned in order to put the next groove in position for regrdinding. The inner race (see Figure 16) is reground in a similar manner.

By way of further illustration, in order to enable regrind¬ ing of the internal components of a Skewed Groove Disk con¬ stant velocity universal joint 94 (see Figure 7), the grinding machine 20 (see Figure 3) is modified to include a means to lock the rotatable arm 32 in one of two positions (not shown pictorially) in order to effectuate regrinding. The locking means first sets the rotatable arm in a first position wherein the clockwise grooves 64a (see Figure 7) are precisely aligned to the centerline of the grinding bit 28 along the Y axis. In the second position, the locking means sets the rotatable arm 32 counterclockwise, with the grooves 64b (see Figure 7) precisely aligned to the centerline to the grinding bit along the Y axis. The locking means preferably comprises a pneumat-

ically operated solenoid (not shown in the Figures) which is located beneath the rotatable arm and which, when operated, causes a tapered pin to be forced into one of several precise¬ ly located receptacles on the underside of the rotatable arm; an electrical position sensing device (such as, e.g., a mag¬ netically operated electrical switch) , also not shown, senses both the motion and the relative position of the rotatable arm and transmits signals to the control device.

The process for regrinding outer race 62 (see Figure 7) of the Skewed Groove Disk constant velocity universal joint 94 (see Figure 7) is illustrated in Figures 14 and 15. Figure 14 is a schematic perspective view of outer race 62 with grinding bit 28 in the starting position for regrinding clockwise skewed groove 64a. Figure 15 shows the grinding bit 28 in the starting position for counter-clockwise skewed groove 64b.

As is illustrated in Figure 14, it is necessary to first align the grinding bit at a position correspond to the top center of the outer race 62. The rotatable arm 32 (shown in Figure 3) is then moved to the first position and locked into place, with the clockwise grooves 64a precisely in line with the grinding bit. The outer race is then advanced to the grinding bit and slowly advanced forward to allow the grinding bit to grind the first clockwise groove 64a. The rotatable arm does not rotate during the grinding operation. Upon completion of regrinding the first groove 64a, the outer race is moved away from the grinding bit and turned one hundred and twenty degrees to the next clockwise groove. This sequence is followed until all three clockwise grooves 64a have been ground to within specification.

When this procedure is completed, the outer race is then moved away from the grinding bit, and the rotatable arm is moved into the second position with the counterclockwise grooves 64b precisely in line with the grinding bit. The grinding operation shown in Figure 15 is repeated until each counterclockwise groove 64b is reground. The inner race 65

(shown in Figure 7) is similarly reground following this procedure.

By changing the adaptor 41 with which the workpiece is held in the chuck mechanism 33 and repositioning the grinding bit in relation to the workpiece, the inner race for each constant velocity universal joint type can be ground using the same size grinding bit that was used on each outer race.

Similarly, the grinding machine of this invention, and the methods of regrinding, can be modified to accommodate preci¬ sion regrinding of the Tripod type constant velocity universal joint shown in Figure 8.

Figure 16 illustrates a process for grinding grooves 4b in inner race 3a. The inner race is inserted into the chuck mechanism 33 (shown in Figure 3), using the appropriate work¬ piece adaptor 41 with an expanding mandrel in order to proper¬ ly position the center of rotation of the inner race directly and precisely over the center of rotation 45 for the rotatable arm during the grinding operation. The expanding mandrel is tightly adjusted to lock the workpiece to the adaptor. In the preferred embodiment, the adaptor is configured as illustrated in Figure 20 as inner race spacer 54 which is attached to the expanding mandrel and the chuck mechanism. the preferred expanding mandrel is designed as in Figure 21 to be a slotted mandrel 43a with expansion screws 44 operating within. With the preferred adaptor fixed to the workpiece, the chuck mechanism is then loosely closed around the adaptor and the inner race in order to permit the rotation of the adaptor within the inner race in the chuck mechanism. In the pre¬ ferred embodiment illustrated, the horizontal alignment adap¬ tor (see Figure 22) is used to locate and position the central axis of two opposite grooves 4b of the inner race (see Figure 16) to be precisely aligned horizontally with the centerline of the grinding bit along the Z axis as the inner face (shown in Figure 16) is turned in the loosened chuck mechanism. The chuck mechanism is then tightened and the horizontal alignment

adaptor removed to enable the grinding operation to begin. Next, the position of the grinding bit tip along the Y axis is adjusted in order to place the tip of the grinding bit at the proper position so as to remove a known amount of material from the surface of the groove as the workpiece is rotated by the rotatable arm. Upon completion of regrinding a groove, the control unit (now shown) then transmits a signal to the chuck mechanism 33 to increment the position of the workpiece about the center axis of the workpiece as indicated by the double-headed arrows 39 until the next groove of the inner race is sequentially placed into position for engaging the grinding bit 28. The grinding sequence is repeated until all grooves have been ground identically. The grinding machine 20 can accommodate the regrinding of the inner races of the In- Line and Skewed Groove Disk joints as well.

It has been found that if the inner race is not ground to a specific tolerance, the constant velocity joint may seize under normal working conditions. In order to prevent seizing, the grinding bit should be five ten-thousandths of an inch greater than the size of the new ball bearing's diameter. Moreover, the new ball bearing's diameter should be two one- hundredths of an inch greater than the size of the original inner race grooves. These tolerances produce the appropriate clearances allowing the ball to actually move and not seize in the inner race groove.

Figure 17 illustrates one preferred process for regrinding intermediate bearing retainer 8. The intermediate bearing retainer is mounted in the chuck mechanism by using an appro¬ priate workpiece adaptor 41. An intermediate bearing retainer adaptor cover plate 49 is turned onto threaded concentric shaft 50 to clamp the intermediate bearing retainer tightly between the adaptor and the cover plate. The chuck mechanism is loosely closed around the adaptor and the intermediate bearing retainer to permit the rotation of the adaptor and intermediate bearing retainer in the chuck mechanism. In the

preferred embodiment, the adaptor is cage adaptor assembly 55 (shown in Figure 18). As is illustrated in Figure 18, the cage adaptor assembly 55 includes adaptor body 59 which mounts into the chuck mechanism at one end and intermediate bearing retainer at the other. The intermediate bearing retainer is sandwiched by adaptor body and cone 58. Fast-lock knob 57 secures screw 56 through the cone, and intermediate bearing retainer into the adaptor body mounted into the chuck mechan¬ ism.

Referring to Figure 17, rotatable arm 32 is positioned perpendicular to the central axis of grinding bit 28. The center of opening 51 of the intermediate bearing retainer 51 is aligned with the centerline of the grinding bit along the Y and Z axis as the intermediate bearing retainer is turned in the loosened chuck mechanism. The chuck mechanism is then tightened to enable the grinding operation to begin. The position of the workpiece table 31 (shown in Figure 3) is advanced slowly toward the grinding bit until the grinding bit has penetrated the opening in the intermediate bearing retain¬ er. The position of the grinding bit along the Z axis is then adjusted to move the grinding bit up and down along the Z axis to grind both sides of the rectangular opening in the interme¬ diate bearing retainer. When the grinding operation has been completed, the workpiece table (shown in Figure 3) is moved away from the grinding bit, the chuck mechanism is then incre¬ mented to position the next opening (opening 51a) in line with the grinding bit, and the operation is repeated until each of the openings has been ground.

Once all of the grinding operations are complete, the inner race, outer race 2, ball bearings 5, intermediate bearing retainer 8, and rubber boot 9 (see Figure 4) can then be reassembled in the same manner in which the original constant velocity universal joint was assembled.

In the machining of the original constant velocity joint, a keyway was built into the stock of the workpiece; this keyway

facilitated the alignment and centering of the workpiece. After the original grinding was completed, the keyway was ground off. Thus, in the regrinding procedure, there exists a need for an alternative means of aligning and centering the workpiece in the grinding machine.

In one preferred embodiment, the means for aligning and centering the workpiece includes a means to accurately adjust the horizontal position of the workpiece in the chuck mechan¬ ism. This means is illustrated in Figure 22. Referring to Figure 22, it will be seen that horizontal alignment adaptor 48 comprises right-hand slide nut 67 and left-hand slide nut 68, both of a size appropriate for the particular constant velocity joint size. The slide nuts are fastened to screw shaft 70. Foot-plate 71 and jig rest buttons 69 are posi¬ tioned on the surface of the steel tooling plate of the rotat¬ able arm of the grinding machine. This positioning causes the horizontal alignment adapter to align along the horizontal plane. Since the axis of the screw shaft is parallel to the foot-plate, the workpiece will then be aligned along a hori¬ zontal centerline parallel to the rotatable arm plate. Actual centering of the outer race occurs by turning the screw shaft, which advances the right-hand slide nut and the left-hand slide nut away from the center of the screw shaft and into the inner diameter of the outer race. The chuck mechanism is then tightened. The horizontal alignment adaptor is then removed. The horizontal alignment of the inner race may utilize a similar procedure, except that the right-hand slide nut and the left-hand slide nut contact the outer diameter grooves of the inner race.

In one preferred embodiment, horizontal alignment is neces¬ sary because grinding is always done on the horizontal plane; however, in some alternative embodiments, grinding may occur on a vertical plane, and in these cases a means for vertical alignment (similar to the means for horizontal alignment) would be required. The vertical alignment adaptor is similar

to the horizontal alignment adaptor with the exception that the screw shaft is mounted perpendicular (rather than paral¬ lel) to the foot-plate.

While grinding machine 20 has been illustrated for use with constant velocity universal joints, it will be understood that this machine may also be used with other workpieces where precisely controlled, accurate grinding is needed. A grinding bit with a diameter larger than the diameter of the replace¬ ment ball bearings and a length equal to the distance measured from the variable chuck mechanism to the grinding bit tip is preferred for accurate grinding.

Figure 23 illustrates one preferred process of the inven¬ tion. This preferred process is enabled by a microprocessor and sequential programming appropriate to the workpiece being ground based on an extensively compiled database of specifica¬ tions for regrinding the wide variety of constant velocity universal joint configurations according to the many manufac¬ turers, and models and years of cars from which they are removed for repair.

Referring to Figure 23, and data entry block 76, the ma¬ chine operator should enter model number information on the joint to be remanufactured into the control computer via a keyboard. In one preferred embodiment, this is an interactive procedure in which the microprocessor screen displays a series of questions and, using the keypad, the machine operator responds accordingly. Typical questions might relate to the manufacturer of the workpiece, the model type and year, and sizing.

Based upon the responses made by the operator, the dimen¬ sions of and other specifications of the particular joint to be operated upon are looked up in a database stored on appro¬ priate computer memory media, and the proper program for grinding the workpiece is then selected in microprocessor operation 88. The cathode ray tube display screen (or other suitable display medium) will instruct the operator in display

operation 78 as to how to chuck the outer race component in the chuck on the rotatable table, and the manual operation 79 must then be completed. Operating control function 80 will then detect the workpiece in position and enclosure locked, and the grinding operation rotational movement will be entire¬ ly controlled and directed by the preprogrammed instructions from the microprocessor according to the specifics of the workpiece dimensions, both controlling movement of the rotat¬ ing table and chuck (and thus the workpiece into the grinding bit) and further indexing the workpiece to position each groove in relation to the grinding bit for sequential grinding operations until the entire part and all of the grooves have been worked. At completion, display operation 81 instructs the operator to remove the workpiece, and a similar operation¬ al sequence 82-85 is repeated for the inner race component. Thereafter, a similar operational sequence 86-89 is repeated for the intermediate bearing cage component.

Thus, the computer program automatically provides complete control and instructions according to the specific dimensions of any selected joint, and it precisely accomplish¬ es the regrinding operations of each of the three components by rotating the grinder table through the predetermined pat¬ tern of movement which grinds the grooves of the workpiece. Grinding is preferably controlled within a tolerance of at least about plus or minus one-thousandths of an inch.

It is to be understood that the aforementioned description is illustrative only and that changes can be made in the apparatus, in the ingredients and their proportions, and in the sequence of combinations and process steps, as well as in other aspects of the invention discussed herein, without departing from the scope of the invention as defined in the following claims. Thus, the present invention is not limited to the procedures set forth above. The grinding machine 20 has been designed to be programmed to operate on various sizes and shapes of workpieces; and, as such, the process for grind-

ing a specific component may deviate from that which was discussed above while still retaining the essence of the invention, which allows the entire remanufacturing operation.

The regrinding machine disclosed herein provides for a self-contained means of automatically regrinding the various components of a variety of constant velocity universal joints. The single station regrinding machine of this invention can regrind any component with a single piece of tooling, a grind¬ ing bit.