US2671293A - Internal grinding machine - Google Patents

Description

March 9, 1954 P. A. GROBEY INTERNAL GRINDING MACHINE 6 Sheets-Sheet 1 Filed Aug. 23, 1949 March 9, 1954 P. A. GROBEY INTERNAL GRINDING MACHINE 6 Sheets-Sheet 2 Filed Aug. 23, 1949 fizz/2% 2 55315,? WW w March 9, 1954 P. A. GROBEY INTERNAL GRINDING MACHINE 6 Sheets-Sheet 3 Filed Aug. 23, 1949 2m L J Z #0 Z March 9, 1954 P. A. GROBEY INTERNAL GRINDING MACHINE 6 Sheets-Sheet 4 Filed Aug. 23, 1949 Ji Wei? March 9, 1954.

P, GROBEY 2,671,293

INTERNAL GRINDING MACHINE- Filed Aug. 2a, 1949 e Sheets Sheet s 1 I I I \V E W E 1 fil flulmhpl March 9, 1954 P. A GROBEY INTERNAL GRINDING MACHINE 6 SheetsSheet 6 Filed Aug. 25, 1949 imN Patented Mar. 9, 1954 INTERNAL GRINDING MACHINE Paul A. Grobey, Springfield, Vt., assignor to Bryant Chuck-ing Grinder Company, Springfield, Vt., a corporation of Vermont Application August 23, 1949, Serial No. 111,779

13 Claims.

This invention relates to internal grinding machines and has for one object to provide a machine having an automatic cycle of operations, the automatic cycle being controlled mechani cally by cams, thus eliminating the complications incident to hydraulic and electrical controls and presenting a machine which can be serviced by mechanically trained men without requiring special knowledge of hydraulic or electrical equipment.

A further object of the invention is to provide a machine particularly suitable for grinding the interior side face and the base of a cup-like mem ber, the base being ground by a grinding wheel mounted for plunge cutting and the interior side wall being ground by the same wheel while it is being given a rapid traverse motion.

Other objects and advantages will appear from a description of an embodiment of the invention shown in the accompanying drawings in which Figure 1 is a front elevation of the machine.

Figures 2 and 4 are detail sectional views on lines 2-2 and 44, respectively, of Figure 1.

Figure 3 is a top plan view of the machine.

Figure 5 is a detail sectional view on line 5-'5 of Figure 4.

Figure 6 is a left end elevation of the machine.

Figure 7 is a detail sectional view on line '!--I of Figures 1 and 3.

Figure 8 is a detail sectional view on line 8-8 of Figure 3.

Figure 9 is a detail sectional view on line 9-43 of Figure 7.

Figure 10 is a detail sectional view on line l0lil of Figure 9.

Figure 11 is a fragmentary end elevation showing the facing diamond holder.

Figure 12 is a detail sectional view on line l2-i2 of Figure 6.

Figures 13 and 14 are detail sectional views to a larger scale on lines l3-i3 and i i-M, re spectively, of Figure 12.

Figure 15 is a detail sectional View on line 15-45 of Figure 3, but showing the wheel slide in advance position and the rapid traversing mechanism in operative condition.

. Figure 16 is a fragmentary top plan View of the parts shown in Figure 15.

Figure l? is a fragmentary view partly in top plan and partly broken away and in section through the work spindle and to a larger scale than Figure 3.

Figure 13 is-a perspective view of one of the controlling cams and showing by legends the angular positions ofthe cam corresponding to 1various portions of a suggested cycle of operaion.

Referring first to Figures 1, 3 and 6, the machine comprises a base I on which is mounted for linear motion a work head 2 and a wheel head 3. The work head 2, as shown, is mounted for sliding motion on a pair of spaced bars 4 and 5, the bar 4 being rigidly supported on the base I and the bar 5 being carried by a pair of vertical supports 6 mounted for yielding motion toward and from the bar 4 as at their weakened portions 2'. Preferably one of these bars 3 or -i is provided with spaced sets of balls and the other provided with a single set of balls for supporting the work carrier 2. However, this particular mounting of the carrier is not per se part of the present invention, forming subject matter of Arms et al., United States Letters Pat-v ent No. 2,631,067 granted March 10, 1953, for Carriage Mounting.

The wheel head is similarly mounted but for motion at right angles to the line of motion of the work head on a pair of bars l0 and H and in a manner similar to mounting of the work head. This mounting provides for relative motion between the work and wheel heads in directions at right angles to each other. The direction of motion of the work head is at right angles to the axis of a rotary work spindle l5 carried thereby and-shown best in Figure 17.

This work spindle is provided with a spindle nose It at its forward end for the reception of a work-holding chuck ll. As shown in Figure 17, this work-holding chuck is provided with collet jaws l8 cooperating with matingly inclined faces of a ring is secured to the chuck body H as by screws 20, axial motion of the jaws 18 serving to clamp or release a work piece 21 between jaw elements 22 carried by the jaws IS. A spring pressed work ejector plunger 25 is slidably mounted in a holder 26 having radially extending fingers Zi projecting through slots 28 in the jaw members I8 and engaged in an annular socket 29 in the chuck body by set screws 30, each having a tapered inner end 3| adapted to wedge the fingers 2? back into the annular socket 29. A plug 32 threaded into the rear end of the member 26 provides an abutment for a spring 33 which tends to press the ejector 25 outwardly and throw the work piece out from the chuck as soon as it has been released. The clamping jaws is are moved axially in directions to tighten the jaws against the work by a coil spring 35 reacting against a shoulder 36 thereon and an annular shoulder 31 projecting inwardly from the spindle l6. The rear end of the portion 36 projects from the rear end of the head 2 and is adapted to be engaged at suitable times by a roller 38 on an actuating lever 39, pressure to the right of which as viewed in Figure 17, serving to push the clamping jaws l8 forwardly, releasing the work by the inherent bias of these jaws l8 outwardly. The work spindle i is rotated by any suitable means, a motor 23 being shown for the purpose, belt connected to the spindle pulley 24.

The wheel head 3 carries a motor to the armature of which may be secured a grinding wheel 4|. This motor 40 with the grinding wheel may be mounted for adjustment angul'arly on the support 3 so as to bring the wheel axis parallel to the axis of the work spindle, in which case th periphery of the wheel will be cylindrical as shown in Figures 1 and 12, or at an angle to this axis in which case the wheel periphery will be tapered as shown in Figures 3 and 17.

Means are provided for relatively moving the wheel head and the work .head between positions at which the wheel is in operative .relation to the work and positions wherein the wheel is retracted from the work, and means are provided for advancing the wheel toward the work to effect a plunge cut thereon so that the end face of the grinding wheel arranged transverse to the axis of rotation of the work spindle grinds an end face of the work and to produce a rapid oscillation of the wheel relative to the work while the side face of the wheel is in engagement with the side face of the Work. This means as shown is connected to move the wheel head. .As shown 1 best in Figures 12 and 13, the wheel head 3 is provided with a downwardly extending bracket 43 to which is attached an end portion of a rod 44.. This rod 44 passses beneath the work head mounting and at its opposite end it is pinned into a member 45 provided with a yoke portion 46. The member 45 is provided intermediate its ends with a transverse slot 41' within which rides a block 48 held within the slot by the two portions of the forked extremity 49 of an actuating lever 50. The two prongs of the extremity 49 straddle the member 45 and the block 48 is held therebetween, being ,journaled on a pin 51 secured in one of the extremities of the fork as by a set screw 52. The pin 5| has an enlarged diameter portion 53 which carries the inner raceway 54 of a ball bearing within a slot 55 of one of the forked extremities 49. The outer raceway 56 of this ball bearing projects outwardly from one side of its supporting fork for a purpose which will later appear. The position of the block 48 longitudinally of the slot 4? may be adjusted by turning a shaft 60 threaded through a nut portion 6| of the member 45 and hearing at its inner end against a side face of the block 48.

This shaft 60 extends through the yoke 46 and outwardly thereof may carry a graduated hand wheel 62 by which it may be turned by measurable angular distances determined by reference to the graduations on the wheel 62.. The inner limit of motion of the lever 59, which determines the retracted limit of motion of the grinding wheel, is determined by a stop bar 65 threaded through a block 56 which may engage a fixed wall member 5'5. The left hand end of the bar 85 may be adapted to be engaged by a stop abutment 58 on the lever 5%]. By turning the bar 65 as by turning of the hand wheel 69 thereon, the retracted limit of motion of the lever 50 may be adjusted as desired. This lever 56 is 4 fulcrumed to the bed at its lower end at 500 and intermediate its ends it carries a cam follower roll 69! bearing against an edge cam 69!! on the shaft 550. The cam 690 which controls the motion of the wheel slide may be contoured as shown in Figure 18, and the various portions of a possible machine cycle, using this cam, are indicated .by legends as the corresponding angular portions of this cam come into action. Since the end face of the grinding wheel is employed to grind an inner end face of the work piece, the position of this end face of the grinding wheel is important and as this face must be trued from time to time, provision is made by which this end face after truing is in a predeterinined position when in retracted position and because of the uniform plunge stroke imparted thereto, the advance limit of motion of this grinding wheel face is also accurately determined.

To provide for wear and truing of the end face of this grinding wheel, means are provided for automatically adjusting the position of the block 48 prior to a truing operation. To this end the shaft 50 is provided between its ends with a hub member 10 having a ratchet wheel portion 1]. This ratchet wheel portion is adapted to be engaged by a ratchet dog 72 pivoted at 120 on a forked arm '53 rockably mounted on the shaft 69. The dog '12 has a tail portion 14 connected through a spring 15 with a bracket portion 16 on an arm Ti integral with a forked member 18 which is pivoted on a pivot shaft 15 to the member .5. The arm H has an abutment in position to strike against the adjustable abutment sleeve 8| threaded onto a rod 82 which passes through the block 66 and is held to its right hand position as far as permitted by a collar 83 pinned thereto and abutting against the block 66 by a spring 85 secured to a rod 86, which is pivoted at 81 to the rod 82. This spring is anchored at its opposite end to the machine bed and tends to hold the collar 83 in the position shown in Figure 12. The wheel head is yieldingly pressed toward its retracted position by a coil spring 830 which surrounds the rod 44 and reacts between a collar 84 secured to this rod and a fixed collar 850.

Whenever the lever 59 is swung to the right, as viewed in Figures 1, l2 and 13, by the action of the spring 830 the abutment 80 is brought into contact with the abutment sleeve 81, and the forked member 78 is rocked in a clockwise direction, bringing a follower roll 88 carried by an arm 83 thereof into contact with an extension 90 from the fork l3, rocking this fork '13 in a clockwise direction as viewed in Figure 14 and causing the dog 12 to engage and step around the ratchet wheel H thus to turn the shaft 60 in a direction to advance slightly the retracted position of the wheel head so that when the wheel end is trued it will take the same position regardless of wheel wear and truing preparatory to a subsequent advance movement toward the work. Reverse direction of rocking of the fork 13 returns the dog #2 without affecting the wheel 1!.

The work head is arranged to be moved transverse to the direction of motion of the wheel head previously mentioned, and this transverse motion, which is a feed and retracting motion, is controlled by mechanism shown best in Figures 1, 5 and 6. As shown in Figure 4, the work head 2 has a vertical wall portion provided with a hardened abutment lfll which is pressed against the rounded end of a feed shaft 102 (see also Figure v5) and this is accomplishedby means of a weight I03 connected through a flexible element I04 which passes over a pulley I05 to a wall member I 06 of the work head. The feed shaft I02 is threaded for a portion of its length and engaging the threaded portion is a nut H0, and for the purpose of taking up backlash between the mating threads of the nut and threaded portion of the shaft, a portion of this nut is split as at I I I and the split parts are joined by a screw I I2, by the tightening of which the split portions may be brought together and take up any lost motion between the mating threads. This nut H butts against and acts as a lock nut for an internally threaded sleeve H which is provided with a reduced diameter portion H6 keyed into an arm H1 which may be caused to oscillate as will later appear. One limit of such oscillation is provided by a screw I I8 threaded into a lug H9 on a bracket I extending upwardly from the machine bed I and the other limit by a stop screw in the lug I2I as shown best in Figure 1. The sleeve H5 is held against axial motion by a clamp plate H4 which holds a flange I22 on the sleeve against a stationary bearing portion The feed shaft I02 has keyed thereto a spiral gear I25 with which meshes a spiral gear I26 carried by a shaft I21. This shaft I21, as shown best in Figure 1, has a hand wheel I28 by which it may be turned as desired. It is also arranged for automatic intermittent turnin motion by means of a ratchet and pawl feed mechanism I29 shown best in Figure 2 and comprising a ratchet wheel I33 fixed to the shaft I21 and a ratchet dog I34 pivoted to one arm of a bell crank lever I35 fulcrumed on the shaft I21 and yieldingly pressed against the ratchet wheel I33 by a spring I38 connected to an arm I29 of the bell crank lever I35 which is actuated by up and down motion of a link I39.

By raising and lowering of the link I30, the shaft I21 is turned intermittently in one direction which turns the feed screw I02 in a corresponding direction and produces intermittent feed of the work head transverse to the axis of rotation of the work and compensates for wear and truing of the periphery of the grinding wheel. Also by rocking the arm H1, which is connected to the nut I I5, the feed shaft I 02 may be caused to move axially in one and then in the opposite direction by a small amount, producing a corresponding feed and retraction of the work holder. The amount of this feed and retraction may be indicated by the extentof movement of the arm II1 across a graduated arcuate scale I32, as shown in Figure l, which extent may be regulated by adjustment of the stop screw in the lug I2 I.

The various motions of the work head and wheel head are produced by cams fixed to a rotary shaft I50. This shaft is driven from a motor I5I through a belt I52 which engages about a pulley I53 carried by a shaft I54. The shaft I54 car ries a worm I55 which meshes with a worm wheel I56 fixed to the cam shaft I50. A cam I50 carried at the right hand end of the shaft I59, as viewed in Figure 6, actuates a follower I5I (Figure 1) on a lever arm I62 fulcrumed at I53 on a bracket I04 carried on the machine bed and this lever I82 is pivoted at I55 to the lower end of the link I30. A cam I10 adjacent to the cam I60 and also carried by the shaft I 50 cooperates with a follower roll I1I on a bell'crank lever I12 fulcrumed on the fulcrum shaft I13, the other arm I14 of this bell .crank lever being connected through an adjustable link I15 to the arm II 1. This produces an intermittent feed and retraction of the work holder with reference to the wheel. Next to the cam I10 is a cam I which acts upon a follower roll I8I on a lever arm I82. This arm is also fulcrumed on the fulcrum shaft I13 and its upper extension I carries a roll I86 which engages the free end portion of the lever 39 carrying the follower roll 38 which acts at suitable times in the cycle to open the chuck for the discharge of the finished work piece and th reception of a work piece to be ground. As shown best in Figures 3 and 6, the arm 39 is fulcrumed at I81 to a bracket I88 carried by the work head 2.

Next left to the cam I80 is a cam I90 engaging a follower on the lower end of a lever I9I. The upper end of this lever I9I is forked as at I92 where it is pivotally connected to a block I93 having a pin and slot connection to the end of a bar I94 which passes through a guide member I95 mounted on the work head 2. At the forward end of the bar I94 it engages a cross head I91 which is mounted for sliding motion on a pair of spaced stationary guide bars I98 and I99 (see Figures 1 and 7). Between end plates 280 and 20I of this crosshead the bar I94 has pivoted thereon an arm 205 and at its upper end this arm is provided with a work piece loading plunger 206 formed with a yieldable periphery which may be engaged in the hole of an unground work piece. This loading plunger is actuated by axial motion of the rod I94 and rocking motion produced by means which will later appear, to engage in the lowest cup-shaped work piece 2| arranged in a stack in a magazine 201 of U cross section, the plunger 208 being arranged to engage in such a work piece, remove it from the lower end of the magazine 201 and present it into the chuck into the position shown in Figure 17. The extent of rocking motion is adjustably fixed by the screw stops 208 and 209 which may engage portions of the cross head I 91.

The rocking motion of the loading arm 205 is produced by the action of another cam 220, also fixed to the cam shaft I50, and in the left hand group of cams shown in Figure 6. This cam220 acts on a follower roll 22I at the lower end of a lever 222 also fulcrumed on the shaft I13. The upper end of the lever 222 is connected to the rear end of a link 223, the forward end of which is connected to a bell crank lever 224 (see Figure 3), one arm 225 of which is connected through a link 226 to an extension 221 of the arm 205 (see Figures 3 and 7). The arm 225 of the bell crank lever 224 is also connected through the connecting pivot of a pair of togglelinks 228 and 229, to a divider pin carrier having a divider pin 230 which enters into the space between the lowest work piece 2| in the supply magazine and the one just above, and lifts the one just above with those above it sufiiciently for the lowest work piece to be removed, after which the divider pin is retracted sufficiently to allow the work pieces above it to descend to bring the lowest work piece into position to be removed on the next actuation of the work feed device.

Since the grinding wheel periphery operates upon the inside face of a work piece, and its end face operates on the base of the hole within the work piece, a truing mechanism for each of these portions of the wheel is provided. The end face truing device, which is shown best in Figures 3 and 8, is mounted in fixed axial relation to the work piece and swung down and acrosstthe 7 end face of the wheel when this wheel is retreated. This truing device 249 is carried at the end of a bar 241 mounted foraxial sliding mo tlon within a casing 242, this casing being secured to an am 243 pivoted to rock about an axis 244. An adjustable stop screw 245 carried in a fixed arm 246 may be contacted by an abutment 241 on the arm 243 to limit the downward swing of the arm 243 to a position where the dressing diamond 240 is substantially in the horizontal axis of the work piece as shown in dotted lines in Figure 8. The rear end of the bar 241 has fastened therewith one arm of a bracket 248, another arm sliding between forks of a bracket 249 extendin from the casing 242. The bar 241 is thereby held against turning about its longitudinal axis.

The bracket 243 is connected at 250 to a link 251 of adjustable length which, in turn, is pivoted as on the pin 252 to one arm of a bell crank lever 253 (see particularly Figure 3). The other arm of this lever 253 is connected by a link 254 with the upper end of a lever arm 255 fulcrumed on the pivot shaft 113 and carrying at its lower end a follower roll 256 bearing on a cam 260 which is the outermost cam in the group of cams at the left hand portion of the cam shaft 150 as viewed in Figure 6. When this lever 255 is rocked to dress, moving the link 254 to the right, as shown in Figure 3, the first action is to depress the casing 242 from the upwardly inclined position shown in full lines in Figure 3 to a substantially horizontal position, bringing the abutment 24? into contact with the adjustable stop 245. Further motion of the lever 255 in the some direction causes the bar 241 to be moved lengthwise within the casing 242, causing the truing device to be passed across the end face of the grinding wheel from its periphery to substantially its axis of rotation. Swinging of the cam lever 255 in the reverse direction causes the bar 241 to be retracted axially and then the bar and the casing 242 to be tilted up out of the way into the full line position of Figure 8.

The truing device or diamond for truing the position. Means are provided for adjusting the diamond holder 263, such means comprising a graduated disk 233 provided with a hand wheel 25? securedto a threaded shaft 268. This shaft bears against a flat portion of an arm 239 extending from a rockably mounted shaft 310. This shaft 318 has a cut away portion 311 within which engages a projection 312 from a block 313 carrying the fulcrum shaft 265. This block 313 is supported on a pair of spaced reeds 314 carried by a bracket 315 fixed to the work head 2. As the graduated disk 2% is turned the shaft 310 is turned and the block 313 is correspondingly moved about one-sixth the distance of the screw adjustment toward or from the work axis.

The outside diameter truing device holder is rocked between its two positions and for this purpose the rear end of the .holder 264 is pivoted as at 238 to a limit 291 of adjustable length, the upper end of which is pivoted to one arm of a bell crank lever 292. The other arm 293 of this hell to the grinding wheel.

8 crank lever is pivotally connected by a link 234 to the upper end or an arm 295, which is 1111- crumed on the pivot shaft 113 and which carries at its lower end a follower I011 296 which bears against a cam 300 also secured to the cam shaft 150.

As before noted, means are provided for producing a rapid oscillatory traverse motion of the grinding wheel relative to the work when the periphery of the grinding wheel is acting upon the side wall of the work piece at which time the grinding wheel does not quite reach its end facing position. To this end the motor 15! is connected by a belt 305 to a pulley 306 (see F18- ure 6). This pulley 306 is carried at the outer end of a shaft 301 (see particularly Figures 13 and 15) provided with a worm 308 at its inner end. This worm meshes with a worm wheel 399 carried by a shaft 310 arranged at right angles to the shaft 301. This shaft 301 carries on its outer end an eccentric cam 311 which may have its peripheral portion formed as the outer raccway of a ball bearing. This portion is in the same plane with the ball bearing raceway 56 of the wheel traversing mechanism shown in Figures l3, l5 and 16 and when it is desired to produce the oscillatory traverse, which is when the grinding wheel is in its advanced position, a spacing bar 315 mounted for axial motion in a sleeve 314 is interposed between the eccentric cam, which is continuously rotated, and the raceway 56. This causes the rotation of the eccentric cam to impart an oscillatory longitudinal motion to the bar 44 and thus an oscillatory traverse The sleeve 314 which carries the spacing bar 315 is mounted on an arm 316. This arm 316 is fulcrumed at 311 (see Figure 6) and is normally held with the bar 315 elevated in inoperative position by a spring 318 secured at its lower end to the arm 316 and at its upper end to a fixed point 319. The opposite end of the arm 316 has bearing thereon the rear end of an arm 320 which is pivoted at its upper end to an arm 321 having a cam follower 322 riding on a cam 330 also carried by the cam shaft 150. This cam 330 is so shaped that at suitable times inthe cycle it interposes the bar 315 between the raceway 56 and the eccentric cam 311. Each of the lever arms 112, 182, 191, 222, .255, 295 and 3.2] fulcrumed on the shaft I13 is pressed with its follower roll toward its actuating cam by individual coil springs attached .to the lever arms at one end and to a fixed portion of the bed at the opposite end.

For the purpose of dressing the outside diameter or periphery of a new grinding wheel. it is necessary to move the wheel carrier from its retracted position toward its advanced position by hand and this may be done by swinging to the left, as viewed in Figure 3, a hand lever 335 fulcrumed at 336 on the top of the machine base and having a roll 331 which engages a lug 339 upstanding from the wheel carriage. When this is done, however, it is important that the outside diameter truing diamond 262 be down and that the loader arm be raised out of the way. The latter two functions are accomplished by the operator swinging a hand lever 340 (see Figures 1 and 6) from the position shown in Figure 1 to bring the projections 342 on its pivot shaft 343 over against the arms 222 and 295, thus holding their followers out of contact with their cams. At the same time that this is done, a part on the handle .340 engages a stop switch 345 which throws oi! the power to the machine'except tor the wheel motor 40 which continues to operate. The end facing diamond is up at this time but may be brought down and across the end face of the grinding wheel by pulling on the lever 253 by hand while the wheel slide is in its retracted position. A facing feed is applied by rocking the lever I96 carried by a rock shaft 346 connected through an arm 341 to the link 86.

In order that the end face of the work piece which is ground may have a superior finish, the grinding wheel axis may be adjusted at a slight angle to the work axis as shown in Figures 3 and 17. This cuts down the area of contact between the end of the work and the wheel and theoretically to a straight line. The face truing device will then true off the end of the wheel in a flat cone shape which will engage the work on one side only of its axis, and the outside diameter truing device will ,true the wheel tapered with its larger diameter facing the work. A cylindrical wheel with its axis parallel to the work axis is shown in Figures 1 and 12. Particularly where a considerable amount of stock has to be removed from the bottom face of the work, there has been found a tendency to burn the work where the plunge cut is unrelieved. This can be avoided and an improved finish produced by retracting the wheel from this face at short intervals which allows the coolant to get in between the wheel and the work for washing and cooling. This may be done by providing a series of fiats or scallops on the wheel slide actuating cam 690 as shown at 350 in Figure 18.

The machine may be operated in accordance with various cycles as desired, depending upon the contours of the cams used and their relative angular relationships on the cam shaft l50. One such cycle, starting from fully retracted position of the wheel head and with a work piece in the closed chuck may be as follows.

The wheel slide cam 690 moves the wheel slide from retracted position into grinding position through the cam rise a to b. A gradual rise on the cam from b to causes the grinding wheel to plunge grind the bottom face of the work, the flats or scallops 350 relieving the end face of the wheel from the work periodically as previously described. During this portion of the cycle, the feed cam I actuates the cross feed for plunge grinding of the internal diameter of the work piece to rough size. The cross feed then backs off and the wheel slide moves to the right from c to d, and the outside diameter of the wheel is trued by the truing diamond 262 which comes down and goes back again as the wheel proceeds back into the work from d to a when dressing has been completed. The cam 330 now causes the lever 316 to descend and interposes the spacer 3l5 between the eccentric 3H and the wheel slide lever 59, the wheel slide retracting slightly to allow the eccentric 3 to take charge between I and g, while final grinding of the inside diameter of the work piece is effected and while the feed caml'lll feeds the work up to finish size, the bottom face of the work not being touched during this final grinding. The wheel slide is now retracted from h to y to its extreme right hand position where the facing diamond 240 moves across the end face of the grinding wheel immediately after the facing compensator has acted to advance the full retracted position of the wheel. At the same time the chuck is opened and the inserts a new piece to be ground.

From the foregoing description of an embodi-- 1O ment of this invention, it will be evident to those skilled in the art that various changes and modifications may be made without departing from its spirit or scope.

I claim:

1. A grinding machine having a work head, rotatable chuck means on said head for supporting a work piece for rotation about the axis of rotation of said means, a grinding wheel head, a grinding wheel mounted for rotation on said wheel head and having an end face arranged to grind a surface perpendicular to said axis as said wheel is rotated, means for moving said wheel head parallel to said axis between an advanced wheel head position in which a wheel carried by said wheel head is operative on work on said work head and a retracted position wherein said wheel is removed from the work, a wheel truing device mounted in fixed axial relation to said chuck means for motion transverse to said axis and positioned to true ofi said end face of said wheel when said wheel head is in retracted position and said truing device is so moved, and means for adjusting said moving means to advance the wheel toward the work preparatory to a wheel dressing operation whereby after said dressing operation said trued end face will be in predetermined relation to the work piece when said wheel is returned to said advanced position.

2. A grinding machine having a work head, means on said head for supporting a work piece for rotation about an axis, a grinding wheel head, means for moving said wheel head between an advanced wheel head position in which a wheel carried by said wheel head has an end face in predetermined relation to a work piece on said work head with said end face arranged to grind a surface of the work piece perpendicular to the axis of rotation of said work piece and a retracted position wherein said wheel is removed from the work, said moving means including a member adjustable in effective length secured at one end to said wheel head and an actuating element operatively engaging the opposite end of said member, means connected thereto for moving said element through a path of definite extent to thereby move said wheel head between advanced and retracted positions, a truing device mounted for motion across the end face of said grinding wheel at a predetermined distance from said work head, and means operatively connected thereto for adjusting the effective length of said member when said wheel head is retracted to adjust said wheel end face toward advanced position by a corresponding amount providing on a truing motion of said truing device compensation for wheel wear and truing of said end face preparatory to moving said wheel head to advanced position;

3. A grinding machine including a work head, a grinding wheel head, a grinding wheel on said grinding wheel head, a rotary work spindle on said work head, a chuck carried by said spindle, means for opening and closing said chuck, means for moving said heads relatively, means for truing said wheel, a cam shaft, and cams on said shaft operatively connected thereto for actuating said chuck opening and closing means, said head moving means, and said truing means.

4. A grinding machine including a work head, a grinding wheel head, a grinding wheel on said grinding wheel head, a rotary work spindle on said work head, a chuck carried by said spindle, means for opening and closing said chuck, means for moving said heads relatively, means for'truof said cam produces traverse between the wheel and the work, and means connected thereto for actuating said lateral moving means during such traverse to feed said wheel against the Work.

3. A grinding machine having a work head, means on said head for supporting a work piece for rotation about an axis, a grinding wheel head, means for moving said wheel head between an advanced wheel head position in which a wheel carried by said wheel head has an end face in predetermined relation to a work piece on said work head and a retracted position wherein said wheel is removed from the work, said moving means including a member adjustable in effective length secured at one end to said wheel head and an actuating element operatively engaging the opposite end of said member, means connected thereto for moving said element through a path of definite extent to thereby move said wheel head between advanced and retracted positions, a truing devic mounted for motion across the end face of said grinding wheel at a predetermined distance from said work head, means for adjusting the efiective length of said member when said wheel head is retracted to adjust said wheel end face toward advanced position by a corresponding amount providing on a truing motion of said truing device compensation for wheel wear and truing of said end face preparatory to moving said wheel head to advanced position, said member comprising a pair of parts threaded together, a ratchet mechanism for turning one of said parts relative to the other of said parts, a fixed abutment, and ratchet actuable means carried by said 14 member and contacting with and moved by said abutment as said wheel head is moved to fully retracted position to rotate said one part relative to the other by a predetermined amount,

PAUL A. GROBEY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 302,525 Stehli July 22, 1884 550,477 Bradley Nov. 26, 1895 888,675 Ward May 26, 1908 1,226,302 Brightman May 15, 1917 1,412,140 Schreier Apr. 11, 1922 1,559,206 Van Norman Oct. 27, 1925 1,602,680 Knowles Oct. 12, 1926 1,812,313 Arter Jun 30, 1931 1,933,213 Guild Oct. 31, 1933 2,070,283 Lewis Feb. 9, 1937 2,127,210 Dunbar Aug. 16, 1938 2,154,681 Jefiries Apr. 18, 1939 2, 87,227 Flanders Jan. 16, 1940 2,285,717 Indge June 9, 1942 2,293,100 Baumgold Aug. 18, 1942- 2,414,182 Wessman Jan. 14, 1947 2,429,830 Ljunggren Oct. 28, 1947 2,431,671 Arms Dec. 2, 1947 2,442,683 Green June 1, 1948 FOREIGN PATENTS Number Country Date 573,117 Germany Mar. 28, 1933 596,378 Germany May 14, 1934

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