Background Art Machines for manufacturing or repairing one or more of the components of constant velocity universal joints are well known. Thus, e.g., United States patents 5,197,228 and 5,359,814 disclose a machine for regrinding such components which contains means for holding the component part, a grind- ing bit, a rotatable support means, a motorized grinding tool, means for adjusting the position of the motorized grinding tool in the Y axis and the Z axis, and a lubricating fluid in- jection system.

These prior art machines are not adapted to readily and efficiently grind the housings of constant velocity uni- versal joints.

It is an object of this invention to provide a grind- ing machine which can readily and effectively grind the hous- ings of constant velocity universal joints.

Summary of the invention In accordance with this invention, there is provided a grinding machine for grinding a housing of a constant veloc- ity joint.

The machine of this invention comprises a grinding bit, spindle means, a lubricating fluid injection system, means for moving a housing in the X axis, in the Z axis, and simultaneously in the X and Z axes, and means for rotating the housing.

Brief description of the drawinqs The present invention will be more fully understood by reference to the following detailed description thereof, when read in conjunction with the attached drawings, wherein like reference numerals refer to like elements, and wherein: Figure 1 is a front view of one preferred grinding ma- chine of the invention; Figure 2 is a side view of the grinding machine of Figure 1; Figure 3 is a front view of the base of the machine of Figure 1; Figure 4 is a side view of the base of Figure 3; Figure 5 is a top view of the base of Figure 3; Figure 6 is another side view of the base of Figure 3; Figure 7 is an exploded view of the machine of Figure 1; Figure 8 is a sectional view of a universal constant velocity joint; Figure 9 is an exploded, perspective view of the uni- versal constant velocity joint of Figure 8; Figure 10 is a front view of the machine of Figure 1 shown with its multiple cage holding fixture in place; Figure 11 is partial top view of the grinding machine of Figure 1; Figure 12 is a side view of the grinding bit used in the grinding machine of Figure 1; Figure 13 is a front view of the grinding bit of Figure 12; Figure 14 is an enlarged sectional view of a portion of the grinding bit of Figure 12; Figure 15 is a front view of a preferred alignment tool used in the system of the invention, illustrating such alignment tool being used in conjunction with the multiple cage holding fixture; Figure 16 is a top view of a preferred alignment tool depicted in Figure 15; Figure 17 is a front view of one preferred multiple cage holder of this invention; Figure 17A is a front view of the shaft of the multi- ple cage holder of Figure 17; Figure 17B is a front view of the shaft of Figure 17A with a first ball cage loaded onto it; Figure 17C is a front view of the shaft of Figure 17B with a conical clamp disposed so that it is contiguous with the first ball cage of Figure 17B; Figure 17D is a front view of the shaft of Figure 17C with a datum plate disposed so that it is contiguous with the first conical clamp of Figure 17C; Figure 17E is a front view of the shaft of Figure 17D with a second ball cage disposed so that it is contiguous with the datum plate of Figure 17D; Figure 18 is a front view of another preferred multi- ple cage holder of this invention; Figure 19 is a perspective view of the grinding bit of Figure 12, showing how such a grinding bit is typically disposed within the window of a ball cage; Figures 20, 21, 22, and 23 illustrate the cage of Fig- ure 19 with the grinding bit of Figure 19 being disposed with- in it in various positions; Figure 24 is a front view of a portion of another pre- ferred grinding machine of this invention; Figure 25 is a side view of the grinding machine of Figure 24; Figure 26 is a sectional view of a portion of the ma- chine of Figure 24; Figure 27 is a side view of the grinding bit assembly used in the machine of Figure 24; Figure 28 is an exploded view of the grinding bit as- sembly of Figure 24; Figure 29 is a partial perspective view of the machine of Figure 24, illustrating a universal joint housing being ground; Figure 30 is front view of the machine of Figure 29; Figure 31 is a schematic view illustrating the grind- ing of a universal joint housing; Figure 32 is a schematic view of the grinding assembly of Figure 29; Figure 33 is a perspective view of a grinding wheel assembly; Figure 34 is a front view of a preferred grinding ma- chine utilizing the grinding wheel assembly of Figure 33; Figure 35 is side view of the machine of Figure 34; Figure 36 is a perspective view of another preferred grinding bit; Figure 37 is a front view of another preferred grind- ing machine of this invention; and Figure 38 is a top view of a portion of the grinding machine of Figure 37.

Figure 39 is a schematic view of one preferred housing grinding machine of this invention.

Figures 40A, 40B, 40C, 40D, 40E, 40F, 40G, 40H, and 40I illustrate the relative positions of a grinding bit and a housing at various portions of the cycle using the machine of Figure 39.

Figure 41 is a schematic view of a preferred coolant injection system disposed vis a vis a tool bit.

Figure 42 is a front view of the coolant injection system of Figure 41.

Figure 43 is an enlarged front view of the coolant injection system of Figure 41.

Description of the preferred embodiments Figures 1-38 provide some of the background material which is useful for understanding the apparatus of this inven- tion. They are fully described in United States patent 5,681,209, the entire disclosure of which is hereby incorpo- rated by reference into this specification. These Figures 1- 38 will be more briefly described in this specification.

Figure 1 is a front view of multiple cage grinding ma- chine 10 comprised of base assembly 12, cover 14, oil mist removal unit 16, key pad/display unit 18, multiple cage holder 20, and grinding spindle 22.

The key pad/display unit 18 is preferably connected to an indexer which is the control unit for the stepper motors 90, 92, and 106.

With the use of known ball cages of known dimensions disposed on a cage holding fixture in known or ascertainable positions, the control unit is capable of determining the precise location of the window openings on such cages and where and how to grind them.

Panel 24 is removably attached to the base 26 by conventional fastening means. Hingably attached to panel 24 is door 28.

Grinding machine 10 is comprised of a coolant fan inlet 29. Air is drawn through a filter in fan inlet 29 by a fan, and the filtered air thus produced is used to cool the electrical assembly disposed within cabinet 31.

A preferred base 26 which may be used in the grinding machine 10 is shown in more detail in Figures 3, 4, 5, and 6.

In this embodiment, it will be seen that base 26 is preferably constructed from a multiplicity of rectangular hollow steel tube members. Vertical members 30 preferably are 2" x 2" steel tubing with a length of 24 inches, and vertical member 32 is 2" x 4" steel tubing with a length of 24 inches. Each of vertical members 30 and 32 is supported by (and welded to) steel feet 34, which preferably are 2" x 6" steel tubing with a height of 6 inches.

Disposed between, and welded to, steel feet 34 is lower longitudinal member 36, which is 2" x 2" steel tubing.

The top section 38 of base 26 is comprised of longitu- dinal members 40 and 42, each of which is preferably con- structed from 2" x 4" steel tubing. The length of members 40 is preferably about 52 inches, and the width of members 42 is preferably about 24 inches. Angle irons 44 and 46 extend from one longitudinal member 40 to the other longitudinal member 40. A panel 48 is preferably welded in place onto the top portion 38 of base 26. The base 26 preferably has a natural frequency of at least about 800 hertz.

The load carrying capacity of base 26 is preferably at least about 400 pounds and, more preferably, is at least about 1,500 pounds.

The torsional stiffness of base 26 is preferably at least about 500 foot-pounds per radian.In one preferred em- bodiment, the torsional stiffness is at least about 5,000 pounds per radian. In another embodiment, the torsional stiffness is at least about 50,000 pounds per radian.

In one embodiment, not shown, one or more of the chambers within hollow structural members 30, 32, 34, 36, 40, and 42 may be filled with vibration reducing material such as, e.g., sand, concrete, and the like.

Grinding machine 10 is preferably comprised of oil mist removal unit 16, which preferably can remove at least about 95 percent of the oil mist in an air sample flowing through it at a rate of at least 250 cubic feet per minute.

Removable cover 14 is comprised of an opening 60 within which is disposed a sliding glass door assembly 62.

In the embodiment depicted in Figure 1, cover 14 is not me- chanically attached to sliding glass door assembly 62 and, thus, can be readily removed from the base 24. Because cover 14 is preferably attached to base 12 by conventional fasteners (such as screws), it can readily be detached from base 12 to obtain more ready access to the innards of the machine 10.

Figure 2 is side view of the grinding machine 10 of Figure 1 with the exterior panels (such as panel 24) removed to better illustrate the structure of the device 10. Cover 14 sits upon base members 40 and 42 and is attached to such base members 40 and 42 by conventional fasteners. Upon removal of these fasteners, cover 14 can readily be removed to furnish access to the grinding cabinet 64 of machine 10.

Grinding cabinet 64 is formed by sheet metal panels 66 welded together. The sliding glass door assembly 62 may be attached to the grinding cabinet 64 by conventional means.

Oil mist removal unit 16 is connected to grinding cabinet 64 by means of flexible seal 68. Air flows in the direction of arrows 72 and 74 around baffle 70 and thence through orifice 76 into air mist removal unit 16.

Grinding cabinet 64 is attached to base plate 78 by conventional means.

Rotary table 80 is mounted on bracket 82 which, in turn, is mounted on X,Z slide 84.

One may use any conventional means for moving bracket 82 in the X and Z axes. Thus, slide 84 is comprised of stepper motors 90 and 92. Stepper motor 90 moves bracket 82 in the direction of arrows 94 and 96 by means of a ball screw on slide 98. Stepper motor 92 moves bracket 82 in the direction of arrows 100 and 102 by means of a ball screw on slide 104.

Rotary table assembly 80 is comprised of a stepper motor which is operatively connected to bracket 82 and rotates it in either a clockwise or a counterclockwise direction.

Referring to Figure 2, machine 10 is comprised of coolant delivery system 88 which is comprised of a pump, oil inlet line 114, oil return line 108, and oil catch basin 110.

Oil caught in catch basin 110 is returned to coolant delivery system 88 via line 108, filtered by conventional means in such coolant delivery system 88, and returned via a pump via oil delivery line 114 to machine 10.

The oil mist captured in oil mist separator unit 16 is separated from air and other fluid in separator 16 by conven- tional means. The oil mist thus separated is then returned to the coolant delivery system tank 88 via return line 112.

Referring to Figure 7, cover 14, grinding cabinet 64, and sliding glass door assembly 62 can be readily removed from base plate 78 by removing any fasteners and/or seals securing said units and lifting the unit in the direction of arrows 116. A fluorescent light fixture 118 is preferably disposed within grinding cabinet 64.

Figure 8 is a sectional view of a typical constant ve- locity universal joint 120 which is comprised of outer race spline 122, outer race body 124, cut off axle shaft 126, inner race splines 128, inner race 130, cage 132, and bearing balls 134. Figure 9 is an exploded view of some of these compon- ents.

Spindle 22 is preferably fixed in place by means of its attachment to pedestal 136 by means of spindle mount 138.

Pedestal 136 is preferably attached to base plate 78 by means of conventional fasteners. In one preferred embodiment, pedestal 136 and spindle mount 138 consist essentially of aluminum. Spindle mount 138 preferably is attached to spindle pedestal 136 by conventional means.

Spindle 22 is preferably adapted to rotate at a speed of at least about 25,000 revolutions per minute and, more preferably at a speed of from about 30,000 to about 50,000 revolutions per minute. These high speed spindles are well known in the art and are discussed, e.g., in United States patents 5,322,494, 5,145,298, 4,979,853, 4,867,619, 4,681,492, 4,519,734, 4,148,246, 4,131,054, 3,567,975, and the like.

The spindle 22 rotates grinding bit 140, which rotates while being maintained in substantially the same vertical and horizontal position. The grinding bit 140 contacts cages 132 (shown in dotted line form in Figure 10) when they are moved into the appropriate positions vis-a-vis grinding bit 140.

Cages 132 are preferably mounted in a multiple cage holding device (see element 160 or element 161 of Figure 17 or Figure 18); and the multiple cage holding device is preferably moved so that the grinding bit 140 is disposed in the appropriate positions within the windows of cages 132.

The ball cages in constant velocity universal joints generally contain six windows 212, each of which are substan- tially congruent with each other.

The cage windows 212 must be disposed vis-a-vis grind- ing bit 140 so that the grinding bit 140 is capable of grind- ing the appropriate surfaces of each of the windows. In the process of this invention, this is accomplished by disposing a multiplicity of cages in fixed, stacked relationship to each other and to specified reference points so that the congruent windows on one stacked cage are vertically aligned with the congruent windows on a vertically adjacent stacked cage, and so that the distance of the congruent cages in any particular stacked cage can readily be determined by reference to speci- fied reference points.

In a preferred process of this invention, at least two cages are mounted upon a cage holding fixture 160 or 161.

These cages generally have the same size and shape, and the windows in each of the cages are substantially congruent with each other.

The process of this invention is designed to align the congruent windows of one cage with the congruent windows of another cage. Furthermore, because the height 141 of differ- ent ball cages 132 varies, the process of this invention is adapted to mount the cages on a holder at specified reference points to compensate for such variances in height. The dis- tance between any stacked cage 132 in cage holder 160 and the center of any of the windows in such cage can readily be determined by the process of this invention even if variations in the heights of vertically adjacent stacked cages 132 exist.

Figure 12 is a side view of a preferred grinding bit 140, which is a substantially integral structure which con- sists of a base 142 of high tensile steel and a tip 144 which is plated with an abrasive such as cubic boron nitride.

It is preferred that base 142 consist essentially of high tensile strength alloy steel with a tensile strength of from about 60,000 to about 150,000 pounds per square inch, a yield strength from about 40,000 to about 120,000 pounds per square inch, and a hardness (Rockwell C) of from about 20 to about 40.

Grinding bit 140 preferably has a length 146 of at least about 2.75 inches and, more preferably, from about 2.75 to about 5.0 inches. The grinding bit 140 preferably has a diameter 148 of from about 0.25 to about 1.0 inches and, more preferably, from about 0.3 to about 0.6 inches.

In one embodiment, grinding bit 140 is comprised of a mark 150, which often is left by a machining center.

Referring again to Figure 12, grinding bit 140 is comprised of an unplated section 152 and a plated section 144.

The length 156 of the plated section 144 is preferably from about 0.25 to about 1.5 inches and also preferably is at least about 40 percent of the length 158 of the unplated section.

It is preferred that the coating on plated section 144 consist essentially of cubic boron nitride. In one embodi- ment, a single crystal layer of cubic boron nitride is elec- troplated onto said steel substrate. In another embodiment, a single crystal layer of cubic boron nitride is brazed onto the steel substrate.

Figure 15 is a front view of one preferred embodiment of an alignment tool. Multiple cage holder fixture 160 is adapted to hold four cages 132. Multiple cage holder fixture 161 is adapted to hold three cages 132.

Multiple cage holding fixtures 160 and 161 are each preferably comprised of a shaft 162 comprised of threaded portions 164 on its exterior surface. Fixedly mounted on shaft 162 are datum plates 166, 166', and 166".

The distance between base 172 and datum plate 166 is a fixed, known quantity, as is the distance between datum plate 166 and datum plate 166', and as is the distance between datum plate 166' and 166". Because the grinding machine knows what these distances are, regardless of height of the cage 132 mounted on the fixture 160, it also knows that a specified distance from either base 172, or datum plate 166, or datum plate 166', it will find a window on the stacked cage.

Also mounted on shaft 162 are clamping cones 168 which, preferably, have a substantially conical shape. Each of such movable clamps 168 preferably contain internal threads 170 which are adapted to mate with external threads 164 on shaft 162 at specified portions of said shaft. As the clamp is rotated in a clockwise or a counterclockwise manner, its position vis-a-vis the nearest datum plate 166 will vary.

Figure 17A is a front view of a preferred embodiment of shaft 162 which differs in structure from the shaft 162 de- picted in Figures 15, 17, and 18. Referring to Figure 17A, it will be seen that shaft 162 is preferably an integral struc- ture preferably made of hardened steel. Shaft 162 preferably has a substantially conical shape and increases in diameter from its top 163 to its bottom 165.

Disposed along the length of shaft 162 are several an- nular ledges 167, 169, and 171 which are used to support datum plates 166. Shaft 162 is also comprised of base 175, which is used to support the first cage 132 loaded onto the shaft.

Top 163 of shaft 162 is comprised of external threads 173. External threads 173 are also disposed beneath each of ledges 167, 169, and 171.

Shaft 162 also is comprised of a base 175 comprised o recesses 177 and 179. Recesses 177 and 179 are adapted to engage with, and be disengaged from, spring-loaded plungers.

Referring to Figure 17B, cage 132 is positioned until it is contiguous with base 175. Thereafter, clamping cone 168 is disposed on shaft 162 until its internal threads 181 and 183 are contiguous with external threads 173 of shaft 162.

Rotation of clamping cone 168 in a clockwise direction moves it downwardly in the direction of arrow 185 and thus presses against, centers, and secures cage 132.

In the next step of the process, a datum plate 166 is then disposed on shaft 162 until it is contiguous with and rests on the ledge 171. This datum plate 166 can now serve the same function for cage 132' (see Figure 17E) as does base 175 serve for cage 132.

In the next step of the process, cage 132' is now disposed on shaft 162 until it is contiguous with datum plate 166. Because the system knows the location of the ledges 167, 169, and 171 as well as the location of the datum plates 166, it also knows the distance between the distance 197 between the centers of windows 212' and 212" of adjacent cages.

The fixtures 160 and 161 are preferably configured by first sliding the first cage to be mounted down the shaft until it impacts base 172. Because the clamps are configured so that they get bigger fro top to bottom, the first cage can readily be pushed towards base 172.

Once the first cage has been disposed between base 172 and the next adjacent clamp 168, the fixture 160 and/or 161 may be mounted on alignment tool 158. Section 174 of shaft 162 is preferably disposed within orifice 176 of base 178 of alignment tool 158 while finger 180 is in raised position 182.

In one embodiment, illustrated in Figure 16, the cage fixture 160 or 161 containing one or more cages disposed on it has its portion 174 of shaft 162 disposed within orifice 176.

Thereafter cage fixture 160 or 161 is rotated in a counter- clockwise direction from about 15 to about 45 degrees until spring loaded alignment fingers 191 and 193 mate with recesses in the base of fixture 160 or 161, thereby locking said fix- ture into place.

Once the radial alignment of the windows of a particu- lar cage has been effected by the manner described, the multi ple cage holding fixture 160 or 161 can be unlocked by press- ing down on it while rotating it counterclockwise. Thereaft- er, when the fixture 160 or 161 has been fully loaded, it may be removably attached to the rotary table 80.

In the alignment process, the cage is rotated to allow alignment finger 180 to become disposed within a cage window, thereby aligning it such window; and the cage is then tight- ened in place by rotating the adjacent movable clamp 168 clockwise to lock the first cage into place. Thereafter, alignment finger 180 is then raised, the multiple cage holding fixture 160 or 161 is then removed from the alignment tool 158, a second cage 132 is then disposed on top of the next adjacent datum plate 166', the assembly is then mounted again in alignment tool 158, the finger 184 is then disposed within the window of cage 132' to align it, the adjacent movable clamp 168 is then turned clockwise to fix the cage in place, and the process is then repeated for the third cage 132".

Because fingers 180, 184, 186, and 188 are vertically aligned with each other, the cages 132, 132', 132", and 132''' aligned with alignment tool 158 will each have their cage windows vertically aligned.

Figure 16 is a top view of alignment device 158. Base 178 of this device contains orifices 190, 192, 194, and 196 which can be used, together with conventional fasteners, to fixedly attach alignment tool 158 to any work table.

Device 158 preferably is comprised of at least one thumb screw 198 which allows one to removably attach each alignment body 200 on specified positions on arm 202 which correspond to the heights of the cages 132 on cage apparatus 160 or 161.

Arm 202 is swingably attached to base 178 by means of pivot pin 204, thereby allowing the fingers 180, 184, 186, and 188 to be moved away from or towards the windows on the cages 132 mounted on fixture 160 or 162.

It is preferred to attach fingers 180, 184, 186, and 188 to bodies 200 by means of a bolt 206 and nut 298. It is preferred that each of such fingers 180, 184, 186, and 188-188 be spring-loaded.

The cage holding fixture 160 and/or 161 with the cages aligned in it may be attached to (or detached from) the rotary table 80 (see Figure 11) in substantially the same manner as it is attached to (or detached from) alignment tool 158.

Thus, referring to Figure 11, the loaded cage holding fixture 160 or 161 containing one or more cages disposed on it has its portion 174 of shaft 162 (see Figures 17 and 18) disposed within orifice 199. Thereafter cage fixture 160 or 161 is ro- tated clockwise from about 15 to about 45 degrees until spring loaded alignment fingers 201 and 203 mate with recesses 177 and 179 in the base of 175 fixture 160 or 161 (see Figures 17A to 17F), thereby locking said fixture into place. To disen- gage the cage holding fixture 160 or 161 from the rotary table 80, it may be turned counterclockwise to disengage spring loaded fingers 201 and 203.

Figure 19 illustrates grinding bit 140 disposed within a window 212; in this embodiment, the center of each window 212 is preferably located about 60 degrees away from the cen- ter of each adjacent window; and the windows 212 are substan- tially symmetrically disposed around the perimeter of cage 132.

The grinding bit 140 rotates, but it is fixed in the X, Y, and Z axis. The cage may be moved in the direction of arrows 214, 216, 218, 220, 222, and/or 224 to change the position of the cage and its window 212 vis-a-vis grinding bit 140.

The relative position of tool bit 140 can be changed in the left or right direction by rotating cage 132 which, in turn, is effected by rotating the cage fixture 160/161 at- tached to rotary table 80 a specified number of degrees, depending on the length of the cage windows 212 and 212'. By comparison, the relative position of tool bit 140 may be changed in the up or down position by moving in the cage fixture 160/161 in the Z axis of the XZ slide 84. When it is desired to remove the grinding bit 140 from window 212, this may be effected by moving the XZ slide 84 in the X axis.

When grinding bit 140 is in the position depicted in Figure 20, the multiple cage fixture 160 or 161 in which the cage is mounted may be moved in the direction of arrow 220 until the grinding bit is in the position depicted in Figure 21.

When the grinding bit 140 is in the position depicted in Figure 21, the multiple cage holder 160 or 161 on which the cage 132 is mounted can be moved in the direction of arrow 224 to remove the grinding bit 140 from window 212, the multiple cage holder 160 or 161 can then be rotated counterclockwise the appropriate number of degrees in the direction of arrow 216, and the grinding bit 140 can be inserted into window 212' to assume the position depicted in Figure 22 by moving the multiple cage holder 160 or 161in the direction of arrow 222.

When the grinding bit is in the position depicted in Figure 22, it may be moved to the position depicted in Figure 23 by moving the multiple cage holder 160 or 161 in the direc- tion of arrow 216.

Figure 24 is front view of a grinding machine 89 uti- lizing substantially all of the elements of the grinding ma- chine depicted in Figures 1-23 but with these components ar- ranged in a different configuration. In the machine 89 of Figure 24, the rotary table 80 is mounted vertically to the XZ slide 84 rather than horizontally, and a different grinding tip 226 is used.

Figure 26 is a partial top view of Figure 24, illus- trating tool tip 226 grinding one track of housing 124. Hous- ing 124 is attached to rotary table 80.

Figures 27 and 28 illustrate a grinding bit which can be used to grind the housing 124. The grinding bit is com- prised of an arbor 228 which, preferably, consists essentially of carbide material. The grinding bit is also comprised of grinding tip 226 which is coated with cubic boron nitride material 232. It is preferred that the front of the grinding plated portion 232 be substantially spherical Figure 29 illustrates how plated portion 232 of the grinding tip is disposed vis-a-vis the tracks 230 of housing 124. The rotary table 80 which holds such housing 124 may be moved in the X axis and/or the Z axis to separate the housing 124 from the tool bit 228. Thereafter, the housing 124 may be rotated by the rotary table 90 in the direction of arrow 232 or 234, and the housing 124 may then be moved in the X axis and/or the Z axis to reposition the tool bit 128 in another track 230.

Figure 32 shows that housing 124 can be made to move in a substantially arcuate path (see arrows 236 and 238) by simultaneously coordinating motion in the X and Y axis. Many other motions can be created by such simultaneous coordina- tion. Tool bit 226 attached to arbor 22 can be caused to grind a substantially arcuately shaped track 230 in housing 124.

Figure 33 shows an inner race 130 of a constant veloc- ity universal joint being ground by a grinding wheel assembly 240.

Figure 34 is a front view of an grinding machine 91 utilizing the grinding assembly of Figure 33. Figure 35 is a side view of the grinding machine 91 of Figure 34 in which a sliding glass door assembly 62 has been omitted for the pur- poses of illustration. A YZ slide 242 is used in place of the XZ slide 84 in the embodiment depicted.

Figure 36 is a perspective view of grinding bit com- prised of grinding tip 226 attached to arbor 228.

Figure 38 illustrates a preferred embodiment of grind- ing apparatus 252 which is comprised of YZ slide 242, spindle 22, tool bit 226 arbor 228, housing 124, rotary table 80, stepper motor 92, ball slide 98, base plate 78, bracket 82, spindle bracket 138.

Figure 39 is a schematic view of a preferred housing grinding machine. Controller 302 is operatively connected to stepper motor 90 via line 304. Stepper motor 90, in turn, is connected to slide 98 and thus is capable of moving housing 124 in the Z axis in the directions of arrows 306 and 308.

A separate line from controller 302, line 310, is connected to stepper motor 106, which in turn, is connected to slide 98 which, in turn, is connected to slide 104. The housing is mounted on rotary table 80, which is mounted to Z axis slide 98; and the whole assembly can be moved in the X axis by stepper motor 92 in the directions of arrows 312 and 314. As will be seen from Figure 39, stepper motor 92 is also operatively connected to controller 302 via line 316.

Controller 302 also can cause housing 124 to rotate either clockwise or counter clockwise through its connection to stepper motor 106.

Controller 302 can simultaneously move housing 124 in both the X and Z axes. When this occurs, the resultant move- ment of the housing is a product of the two different move- ments.

Referring to Figure 40A, and at the start of one cycle, grinding bit 226 is disposed substantially outside of the center 318 of housing 124. The sectional view of housing 124 depicts two opposed ball tracks 320 and 322. However, as will be apparent to those skilled in the art, such housings preferably have 6 such ball tracks, each disposed at about 60 degrees from the adjacent ball tracks.

The grinding bit 226 is not positioned to grind ball track 320. Thus, housing 124 must be moved in the direction of arrow 308 in order to reach the starting position depicted in Figure 40B.

Referring to Figure 40B, the grinding bit 226 is im- pacting ball track 320 only at starting point 326. In order for it to grind the arcuate path necessary for ball track 320, housing 124 must simultaneously be moved in the direc- tions of arrows 312 and either arrow 308 (when an ascending arcuate path is desired) or 306 (when a descending arcuate path is desired).

Figure 40C illustrates the situation when housing 124 has been moved in the direction of arrows 312 and 308. Figure 40D illustrates the situation when housing 124 has been moved in the directions of arrows 312 and 306.

After track 320 has been ground, housing 124 may be moved in the direction of arrow 306 until the grinding bit 226 is substantially aligned with center line 318. Thereafter housing 124 may be rotated 60 degrees until a new unground track 321 is uppermost (see Figure 40F). Thereafter, by moving housing 124 in the directions of arrows 308 (Figure 40E), and/or 308 and 314 (see Figure 40G), and/or 306 and 314 (see Figure 40H), and 306 (see Figure 40H), one may repeat the grinding cycle depicted in Figures 40A through 40E.

Thereafter, after the second track 321 has been ground, the housing may be rotated another 60 degrees and the repeated for a third track.

The relative rates at which housing 124 is simultane- ously moved in both the X and Z axes will dictate what type of compound movement is produced.

Figure 41 illustrates a preferred cooling system of this invention. Mtorized high speed spindle 22 is mounted in spindle mount 136 with bracket 138. These parts are commer- cially available. Thus, one may use as motorized spindle 22 a spindle identified as CVS-3920 by the Constant Velocity Sys- tems Company of Clifton Park, New York. Similarly, one may use as spindle mount 136 and bracket 138 Constant Velocity's part CVS-0115.

Referring again to Figure 41, it will be seen that secondary nozzle has an orifice 344 which directs fluid (not shown) at the perimeter 346 of tool bit 226.

The cooling system 341 also is comprised of a primary nozzle 342 with an orifice 345 which also directs fluid (not shown) towards the perimeter 346 of tool bit 226.

In the embodiment depicted in Figure 42, the tool bit 226 is rotating in the direction of arrow 348. Fluid from primary nozzle 342 flows in a direction similar to the direc- tion of rotation 348, whereas fluid from secondary nozzle 340 flows in a direction opposite to the direction of rotation 348. This is more clearly illustrated in Figure 43.

Secondary coolant nozzle 340 preferably has an outside diameter of about 0.25 inches, whereas primary coolant nozzle 342 preferably has an outside diameter of about 0.375 inches.

It is preferred that the primary coolant nozzle 342 has a volumetric flow rate which is at least about 2 times as great as the volumetric flow rate of the secondary coolant nozzle 340.