US2464142A

US2464142A - Infeed for grinding machines

Info

Publication number: US2464142A
Application number: US710083A
Authority: US
Inventors: Veikko J Marshall
Original assignee: Norton Co
Current assignee: Saint Gobain Abrasives Inc
Priority date: 1946-11-15
Filing date: 1946-11-15
Publication date: 1949-03-08
Anticipated expiration: 1966-03-08

Description

March 8, 1949. v. J. MARSHALL INFEED FOR GRINDING MACHINES 2 Sheets-Sheet 1 Filed Nov. 15, 1946 March 8, 1949. I v, MARSHALL 2,464,142

INFEED FOR GRINDING MACHINES Filed Nov. 15, 1946 2 SheetsSheet 2 NNN Giza-M I !//////////A 1/ I Z Yl/l/l/ll/ll VE/KKO .LJ. MARSHALL Patented Mar. 8, 1949 UNITED STATES PATENT OFFICE INFEED FOR GRINDING MACHINES Application November 15, 1946, Serial No. 710,083

15 Claims.

The invention relates to grinding machines and more particularly to cylindrical grinding machines.

One object of the invention is to provide an improved cylindrical grinding machine for grinding cylindrical surfaces wherein the finished size may be automatically controlled with great accuracy. Another object is to improve the machine of U. S. Patent No. 2,267,391 to Astrowski. Another object of the invention is to provide a readily controlled apparatus for rapidly moving the grinding wheel and the work relatively toward and away from each other. Another object is to provide automatically controlled and variable slow speed grinding wheel infeed during the grinding operation after rapid relative approach of the wheel and the work with automatic separation of the wheel and the work when desired work size is reached. Another object is to provide smooth grinding infeed action of the grinding wheel relative to the work at various grinding infeed speeds with or without automatic work size control within extremely fine limits of accuracy. Another object is to provide increased production in finish grinding. Another object is to provide apparatus of the character indicated which may be economically manufactured and compactly assembled on a standard grinding machine and which will give accurate and depend-able operation over a long period of time.

Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combination of elements,

and arrangement of parts, as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which is shown one of many possible embodiments of the mechanical features of this invention,

Fig. 1 is a longitudinal sectional view of the apparatus of the invention mounted upon the wheel feed shaft;

Fig. 2 is an end view of the apparatus;

Fig. 3 is a vertical sectional view of the apparatus of the invention and associated mechanism together with a wiring diagram and a fluid diagram.

As conducive to a clearer understanding of the invention, it is noted that the illustrative embodiment discloses an improvement of a type of apparatus now commonly in use for moving the grinding wheel relative to the work. Such a machine has a work table upon which is mounted a headstock and a tailstock to hold a cylindrical work piece and rotate it against the grinding wheel for cylindrical grinding. Such a machine also has fluid pressure means for rapid infeed and retraction and for normal grinding infeed and slow grinding infeed.

The terms rapid infeed and retraction as used herein mean positioning of the grinding wheel relative to the work preparatory to grinding and retracting it rapidly from the work when grinding is completed. The term normal grinding infeed means feeding the wheel against the work during rough grinding, and the term slow grinding infeed means feeding the wheel against the work for the final finishing cut.

According to the present invention additional fluid pressure means hereinafter described are provided whereby after the wheel slide has rapidly approached the work piece and is ready to grind, a very finely controlled smooth and accurate slow grinding infeed is provided with uniformity within close tolerances and with automatic stopping of the grinding infeed and rapid retraction of the wheel slide relative to the work when size is reached.

As illustrated in the drawings the machine of the invention comprises a base I0 which supports a wheel slide 1 l for transverse movement thereon 0n the V-ways l2 which in turn rotatably supports a grinding wheel L3. The base In also supports a longitudinally movable work supporting table (not shown) which is arranged to slide on ways.

Work rotation A cylindrical work piece 14 may be held between a power driven headstock and a tailstock mounted upon the longitudinally movable work supporting table (none of these being shown) so that it can be rotated against the grinding wheel l3 when the latter is in position to grind, and moved longitudinally across the grinding face of the wheel to grind a cylindrical surface on the work piece l4.

Grinding Wheel Drive Mechanism The grinding wheel I3 is mounted on a spindle l5 which is journalled in bearings in the top of the wheel slide I l, and it is driven by any con venient source of power such as an electric motor I! which may be mounted on the wheel slide I l to drive a pulley 18 mounted on the motor shaft IS, a belt 20 and a pulley 2| on the wheel spindle l5.

Grinding wheel rapid infeed mechanism of the hand wheel in one direction feeds the wheel slide II and grinding wheel I3 into the work, and in the other direction" retracts the Wheel slide II. For rapidly moving the grinding wheel I3 to and from a grinding. position,.f1uid= pressure means are provided comprising a. cylinder 3| which is either formed. as an integralpart of the base I9 or fixedly mounted thereon; The? shaft 29 is aligned with the axis of the cylinder and serves as a piston rod. A piston 35 is slidablymounted'within the cylinder 3| and isfixedly.

supported by suitable meanson the piston. rod 29. It will be apparent that when the piston 35 is movedendwlse, it will transmita feeding movementto the grinding wheel I3 through the rod.

29, its enlarged portion 28, the feedscrew 21v and half nut 25 to move the wheel slide I I. The feed screw 27 is arranged so that itmay be rotated relative to the piston 35 so that the operator, by manual rotation of the feed screw 2'! may readily adjust the position of the grinding wheel- I3 relative to-the fluid pressure mechanism.

Grinding infeed mechanism A fluid pressure actuated face cam mechanism 59 is provided in alignmentwith and assembled about" an extended portion of. the-feed shaft 29 for accurate control of grinding wheelinfeed during the grinding operation and positive stopping thereof upon grinding of the work piece to desired size.

A fluid motor casing. 55 concentric with the shaft 5| is mounted upon a head 56 of the cyline A motorvane 58 is secured by bolts 6I- der 3|. and 62m a sleeve 64 which is rotatable on shaft 5I. motor casing 55 from. av position against aface 66 of a stop 67 through the substantial'partofa. circle to. a. position against a face 68 of. the. stop,- 61 by fluid pressure applied to one side of: it. As viewed in Fig; 2,

within the motor casing 55; when fluidpressure is applied in'a passage ID-and allowed to exhaustfrom a passage 'II the motor vane 58 will rotate counter clockwize from theface 66 to the face 68. When pressure is applied in the passage II and allowed to exhaust from the passage I9, the motor vane 58 will rotate clockwise from the stop face 681 .to thestop face.

61. Rotation of the motor vane. 58" rotates: the sleeve 64 with it. A face cam driving member- 15 is keyed to the sleeve64 by a key'l6; so. as tov rotate with the sleeve 64; The face. cam driving.

member I5 is slidable endwise. of the sleeve 64; the key I6 being'slidable in a keyway I8.

can slide endwise of the sleeve. 64 are. determined by a pin flil'mounted in the face cam driving'member 1.5, which rides inaslot. 8| in the sleeve 64.

The pin 89 is held inplaceby a lockscrew 82. A.

face cam 85 is secured by a plurality, of bolts, of whichone 86 is shown, to'the face cam. driving member 15 to turn with it. The? face cam. 85

rides against a pair of conically shaped rollers 88 and 89 which in turn roll against.asecondfacev cam 99 which is secured to the end plate 92 of The motor vane 58 may be rotatedwithin the.

The limits to which the face camdriving member I5 the vane motor casing 55 by a plurality of bolts of which one 94 is shown. The face cams and 99 have helical surfaces which are bevelled. The rollers 88 and 89 are secured to a roller ring 95 by means of threaded studs 98 and 99 respec tively. The studs 98 and 99 may be adjusted so that the rollers are exactly equidistant from the axis of rotation ofthe face cam 85. The roller ringv 95 is rotatable and slidable endwise. on the cylindrical portion 9'! of the face cam driving member 75. The studs 98 and 99 are locked in place by lock screws NH and I92. The rollers 88 and 89'ride'on ball bearings I93 and I94. When the motor vane158, sleeve 64, cam driving member 15' andface. cam85. are caused to rotate about the shafttl by fiuid pressure in the fluid motor casing,55,.in. a counter clockwise direction in this instance as viewed in Fig. 2, the cam driving uniti15 moves to the right as viewed in Figs. 1 and 3 a distance sufficient for grinding infeed. The cam driving unit I5 has a thrust. bearing assembly comprising a bearing'member I95*abut:- ting the member 15, bearing I86 and an abutment:- member I97 which rides upon the. ball bearings I.96.. The thrust bearingassembly, is heldin:place;- against the face H3 of the cam driving member;- 75, by a ring I99 and bolts I19. An: adjustable;' stop collar. II5'having a splitlocking-portion. I16: is mounted upon a threaded portion N8? of the? feed shaft 5 I- and serves. as. an abutting; member." which is abuttedby the, abutment member. IIlz'I' when the wheel. slide II moves to thebright...

When fluidv pressure-is exertedin. the cylinder? 3I to drive the. wheel It. to the right, tozpositionz. it for. grinding, the collar; II 5. makes. contactiwitna and stops against theabutment member.- I91 of; the thrust bearing. assembly. Although a. full. head of pressure is. maintained. in. the; cylinder: 3|; the wheel can go no further until fluid.pres;--- sure is admitted to actuate. the motor'vane 58:. Thereupon a very fine'grinding infeed ispermitted; due. to a slight motionof the. abutment member. I01. and camdriving unit E5 to the right, Fig..1i An: adjustable split stop ring I28. having; as shown. in Fig. 2, a. locking. bolt I.2I in: a boss I22. is. mounted upon the outsideperiphery of thecam driving'member fi; A limit stop I25 is mounted onthe base I9 ofthe machine by suitablebolts' I26; The split stop ring I'29is so positionedkthati. its-surface I2'I will-abut the stop I25'at the limit of the possible grinding infeed stroke, and it may beadjusted' to afford a positive grindnig infeed stop at a predetermined finished: work sizeiwhen. the grinding machine is .t'o-be 'usedwithout a work sizing device;

In such fine and" precisely measured grinding:- infeed itis apparent that. for exact uniformity; itis necessary that the face-cam 85, the rollers 88 and 89 and the. face: cam. 98i beiin' exactly the; same relative position. atithej. beginning offeachv grinding. infeed. cycle, and. to, that: end means? to; reposition accurately the rollers68and; 89.: relattive to the. two. face cams85and- 99are: provided; The. cam 85 can easily be returned to t'heisame, position each time by reversing the'fiuid; motor; until themotor. vane.58.stops.against the face.66 of the: stops. 61. It' will be:recalled= thatthe. cam driving: member 75'is keyed'to. and slidableendwiseon sleeve 69. A plurality of compression." springs of which one I35 is shown are provided? and seatedin. holes I 86 inthe'sleeve'. 64;, These springs I35; bear against the" bearing member. I95 of thethrust bearing assembly,,and through. the ballbearingsv I 03, abutment. member I91 and holding: ring. I 89 they move. the. entire: cam= driv ing unit 15 to the left as shown relative to the sleeve 64 when pressure upon the thrust bearing abutment member I01 by collar H5 is released by reversing fluid pressure in the cylinder 3I to retract the wheel I3 from the work. Furthermore a friction ring I40 attached to the cam driving member 15 bears against the roller ring 95 and as the member 15 is pushed to the left by the springs I35 the friction ring I40 pushes the roller ring 95 to the left with it causing separation of the rollers 88 and 89 from the surface of the face cam 90. The friction ring I40 is slidable end-wise of the surface 91 of the driving member 15 and it is urged against the roller ring 95 by a plurality of compression springs of which one I42 is shown, which are seated in holes I43 in the ring I40 and which thrust against an annular ring I46 which is secured to the cam driving unit 15 by suitable bolts I41. The annular ring I46 is rotatable and slidable upon the surface of the sleeve 64. The friction ring I40 is connected to be rotated with the cam driving unit 15 by a drive pin I49. When the wheel I3 is retracted by reversing fluid pressure in the cylinder 3|, the fluid pressure is also reversed in the vane motor casing 55 causing the motor vane 58, cam driving member 15, and cam 85 to move clockwise to reposition the cam 85. As the pressure of the collar II5 on the abutting member I01 of the thrust bearing assembly is released, the cam driving unit 15 and cam 85 move slightly to the left by spring action as described. The friction ring I40 pressing against the roller ring 95 separates the rollers 88 and 89 from the surface of cam 90 but holds them pressed against the surface of the face cam 85. Therefore as the face cam 85 rotates to be repositioned, the rollers 88 and 89 move with it and relative to the face cam 90 until they are in their original starting position. This point is determined by a limit stop I55 formed by the end of an annular groove I52 in the face cam 90. A pin I54 in the roller ring 95 rides in the groove I52 and upon reaching its end the roller ring 95 and rollers are in the predetermined starting position for grinding infeed. They no longer rotate with the face cam 85 which continues on to its starting position, the face cam 85 now rolling upon the rollers 88 and 89 and the friction ring I40 sliding over the roller ring 95 as the latter is stopped by the pin I54. Since the face cam 65 rotates twice as far as the rollers 88 and 89 during grinding infeed, it must carry the rollers back half way of its rotation to reposition them and continue its full distance to the original startin position.

When fluid pressure is introduced in the cylinder 3I to cause rapid infeed, the collar II5 on shaft 5! finally makes contact with the thrust bearing abutment member I01 and compresses the cam driving member 15 and cam 85 against spring compression to the right until the rollers 88 and 39 are in contact with both

cams

85 and 90 so that cam action may take place when the vane motor is operated.

Fluid pressure control A fluid pressure control valve I60 is provided to regulate the admission of fluid to the cylinder 3! and the vane motor casing 55. This valve is preferably of the balanced piston type having a valve stem I-JI and a plurality of valve pistons I 62, I63 and I54 which are slidably mounted in the valve I60. The ports in the valve I60 are so arranged that fluid from a reservoir I66 is forced by a pump I68 through a conduit I into either of two valve chambers I12 and I13. As the valve stem I6I is shifted from one extreme to the other extreme position, the fluid flow may be changed from one side of the piston 35 to the other to reverse the direction of movement of the wheel slide, and from one side of the motor vane 58 to the other to reverse its direction of movement. The pump I60 has a relief valve I14 on its outlet side so as to maintain a constant pressure into the valve I60 and to drain off excess oil which is not pumped into the fluid pressure system. In the construction shown, with the valve stem I6I normally positioned to the left by means of a spring I15 the valve I60 is set to retract the wheel slide. When the valve stem I6l is set to the right against the sprin I15 it is in the rapid and grinding infeed position wherein fluid under pressure enters the valve chamber I13 at the left side of the valve piston I63 and goes to the left side of the piston 35 through a conduit I16. It may also enter the fluid motor casing 55 through a check valve I18, a conduit I60 and the passage 10 on the left side of the mechanism as viewed in Figure 2 to drive the motor vane 58 counterclockwise. Fluid is exhausted from the right side of the piston 35 through a conduit I82, the valve chamber I12 and back into the reservoir I66 through a conduit I84, a hand adjusted valve I86 and also through a conduit I88 and a solenoid operated valve I90 which is kept normally open by a spring I92.

Fluid is exhausted also from the right side of the motor vane 58 (as viewed in Figure 2) through the passage H, a conduit I94, a solenoid operated metering valve I96, the conduit I82 and back to the reservoir I66 by way of the conduit I84 as described. With rapid infeed to position the wheel I3, it is desirable to slow the action down somewhat just before the collar II5 makes contact with the abutment member I01 so as to avoid jarring of the mechanism. To this end the solenoid operated valve I90 is provided. While normally open to allow rapid exhaust from the cylinder 3I durin infeed, it is momentarily closed just before the collar II5 makes contact with the abutting member I01. When the valve I90 is closed, exhaust fluid is metered through the hand adjusted valve I86 to slow down the infeed action.

The movement of the motor vane 58 is delayed while the piston 35 is actuated for rapid infeed because the solenoid operated metering valve I96 is normally almost closed to allow only a very flne stream of exhaust fluid from the vane motor housing 55 to pass through it as rapid infeed and slow grinding infeed take place. It is only opened for normal grinding infeed after the collar I I5 has made contact with the abutting member I61. The valve I96 has a stem I98 having a wedged slot 200, which when normally positioned to the right as shown, meters fluid through it at a slow rate which is adjustable by a set screw 202 to allow only a very slow grinding infeed by slow cam action of the face cams and 90. When the valve stem I98 is to the left, fluid is metered at a more rapid rate for normal grinding infeed. Positive stopping of the grinding wheel infeed is immediately brought about by reversing the flow of fluid through the cylinder SI and in the vane motor casing 55 by reversing the solenoid operated valve I60.

During retraction of the piston 35 and repositioning of the motor vane 58, fluid delivered from the reservoir I66 by the pump I68 under pressure passes through the valve chamber I12 andrthe-conduit' I82 to. the right-side off-thepiszton:35.. It also passesthrough acheckzvalve 2Mv Whichcis; provided in a shuntconduit266: across:

thermetering valve I96 between. the conduits I82 and. I 94,. and into, the vane. motor. casing; 55 through the passage 1 I under full head to reposition'the. face cam 85 rapidly toits initialstarting. position. The cylinder 3| exhausts fromthelefti. side. of; piston throughthe conduit. I16; the valve? I60 and a hand adjusted. meteringjvalve.

28B torthe-reservoir: I66. The valve 208. is.=pro:-

videdto adjust the. speed. of retraction of: the:

piston v35, and. the exhaust. from the. vane. motor during repositioning. of. the cams. also: passes; through it. The exhaust rate from the-vane md tor'casing'55 during repositioning is also. adjust.-

able. when: it passes. through a handi adjusted valve2l0 into. the line 5.. While: the. speed of rapidinfeed and grinding, infeed may 'b'e'. con-- trolled by closing the valves I98 andv I96, the

speed of. retraction is unafiected by the valves which are bypassed when the main valve Ifiilis.

reversed so that retraction and repositioning speeds may be set as high as desired by the hand operated. valves 208- and 2 I0.

Electrical control Themain solenoid operated control valve. IE5.

is. normally positioned by the springv I75 tore:- tract. the: wheel slide from the Work.. By energizing its solenoid 2I2, rapid and grinding infeed;

are effected. Thisisdone by'movinga mainxoperatingiswitch lever 21. 5 to the rightwhich closes.

a main switch contact 2I6, another 2I8' being normally closed.

An electric circuit is then. completed across. two wires. 220'. and 222 from an alternating cur:-

rent power source whichmay be onehundred and ten. volts. The currentfi'om wire 22!] runs through a.wire'224, switch contacts 2I8'and 2H5; a wire. 225, a relay operated sWitch 226 Which is normally closed, a wire 22?; through a relay 228; wires: 230' and 232 to wire 222 to energize the relay'228.. A relay operated switch 23% is then closed to complete the circuit fromv the wire 224- by wayrof wire 238 through thesolenoid 2I2 to energize it and through the wire 232 to wire 222. When the relay 228 was energized it also-closeda relay operated switch 240 to form a holding circuit so that when hand pressure is released on the lever 2M to reopen the contact 2I6 which is normally open, the circuit energizing solenoid 228.wil1 nevertheless remain closed. The wheel slide III and shaft 5i now start'rapidly to the right. Just before the collar II5 makes contact with the abutment member I01 of the thrust bearingassembly a plate 242 which is adjustabl'y mountedon the end of shaft 5| engages an arm 244 of a limitswitch 2% to close it. The arm abutment member IN. The circuitis. completed; from the wire. 22!! through a Wire 250, thesolenoid'.

2 38, a wire252, the switch 246 and a wire 254 to'the wire 222. contact with the abutment member I Ill, the plate 242 rides over the arm 2% to reopen thezrlimit;

switch. 246 and the valvev I90. At this instant the plate 242 also engages an arm 256 of a limit switch.

258-to energize a solenoid 268 and open the :valve I96 to allow exhaust from thevane motor casing-.-

This momentarily energizes a Just as the collar H5 makes.

55" at. normal I grinding; infeed: rate. Thee circuitsis; completed from the wire:-222 through;a wire.262;. theswitch 258; a wire 264, the:solenoid:.26L0;,.a..wire: 26:6,..a relay operated switch 268 andiaawire. 269 to: the. wirer22tl... Therelay; operated; switch 288..is; normally closed and the. trip-switch; 258i remains; closed. during the remainder; of: the grinding; in feed: cycle.

A standardelectrical work sizing gage: 210 is;

S. .A: Foster, N o. 2,267,5'5 9, having? double contacts;

whichare. normally open. and. which 0105355118 cessively; as Worksizeis reduced. The; gage; 210:

is. available: as. a. complete unit.. The: first; cone tacts to. closehaveterminals-zl 2- and 21.4 andare adjusted to close when work sizedszreducedi to. the; point. when it: is desired to'chang-e from normal grinding. infeed rate. to slow grindingginfeed rate;- The second" pair of. contacts have. terminals. 216' and 2.I8:'and are adjusted to close whe'nthework hasbeenground to finished size. As work size. is reduced at. normal grinding infeed' speed, the" first cont'acts having terminals 212 andl 2-l4lclose= tocomplete the circuit from the' wire 222loy way 1- of.

wires

232, 239 and 28%, across thet'erminals- 2l2and2'i l, awire 28-2; a relayzfl l and the

wires

292, 293 and 2 68 to the wire 220'. This'energizes the relay 28 i toopen the switch 268; The-solenoid 269 is deenergized' and the'valve I96 closes; to-rneteroil at theslow grinding infeedsrate. A's; thework. is ground to its predetermined finished size theseconclpair of contacts of the gage 210 havingthe terminals Z'Iiiand 2T8- close to-complete the circuit from the wire 222 by way-of-wires 2'32, 238"; and23l across the terminals 2'iIFand'2'I8, through a wire 286- to arelay- 2'88 aud t-hence through the wires-2%; 293 and 289410 the wire 220-. This-energizes the relay 288',- opens the 'relayoperated switch 223 to break the circuit through the relay 228 by way'of the wire 221; thereby allowingthe relay operated switch 234 to open and deenergize the solenoid 2I2; The'main valve- I'fii isthen reversed, grinding; infeed comes to a positive instantaneous stop and-the 'Wheel' I 3'-is retracted from the-Work I4 To' operate the machine; starting with the grinding wheel in retracted position, I place a. cylindrical work piece I4 in the headstock and footstock and set the gage 270 to change the grinding infeed from normal to slow or finish, grinding rate at the requiredsize; and to stop the" grinding at the required finishedsize; I start'the work piece rotating'and throw-the startingswitch' lever 2 I4 tothe-right foran instant; Thewheeli I3 starts rapidly toward the work' (to; the right; as-=shown)-. As the collar H5 is about to make. contact with the abutment member I91; the. plate- 242- hits the arm 244 of 'the switch 246} andthe motion issloweddown until" the collar II5'- actually-makes contact with the abutting'member" I 01. At that instant the collar H5 actuates the-arm 256 to close the switch 258 and open the metering valve I98. The wheel now" makes contact with the work and grinds at normal grinding infeed speed until the gage contacts-across

terminals

212 and 214 close. This shuts down the metering valve I96 sothat' only a small stream of oil is'exhausted from the vanemotor casing 55 and the motor vane 58 continues rotating at" a slower rate to allow afinish grinding infeed'rate: When the work: is ground to the desired predetermined size, the gage contacts across the terminals: 216' and. 218i close. The: valve I 60" is. instantly reversed to." retract. the: wheel: from: the: work-iand: the-motor. vane 58, cama and camp provided suchas thatdisclosedin :U. S. Ratentto;

rollers 88 and 89 are repositioned so that a new cycle of operation may be started. A new work piece may then be inserted and the operation repeated. I may want to use the machine without an electric sizing gage. In that case I adjust the split stop ring 120 about the periphery of the cam driving unit 15 so that its face 52! will stop against the limit stop 125 when the predetermined work size is reached in grinding. In that case I use only one grinding infeed speed, and the wheel is retracted by hand operation of the lever 2|4 to the left which opens the contact 2 i8 and reverses the valve I60.

The mechanism of the invention provides smooth, finely controlled grinding infeed action in a compact unit which may be mounted upon any standard machine. Pressure exerted between the face cams B and 90 is evenly balanced upon the double cam rollers 88 and 89.

It will thus be seen that there has been provided by this invention an apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved.

As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth as shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a grinding machine a cross slide mounted on ways, a feed shaft connected to said cross slide, means to move said cross slide in either direction and to urge it in one direction, abutment means precisely to control final movement of said cross slide in one direction including a collar on said shaft, an abutment member to abut said collar, a rotatable cam driving member, fluid pressure means to rotate said cam driving member and face cams arranged in connection therewith whereby rotation of said cam driving member allows further movement of said cross slide.

2. In a grinding machine a cross slide mounted on ways, a feed shaft connected to said cross slide, power means to move said cross slide in either direction and to urge it in one direction, abutment means precisely to control final movement of said cross slide in one direction including an adjustable collar on said shaft, an abutment member to abut said collar, a rotatable cam driving member, a vane motor to rotate said cam driving member and face cams arranged in connection therewith whereby rotation of said cam driving member allows further movement of said cross slide.

3. In a grinding machine a cross slide mounted on ways, power means to move said cross slide in either direction and to urge it in one direction, abutment means precisely to control final movement of said cross slide in one direction, face cams to control movement of said abutment means, rollers between said face cams and fluid pressure means to rotate one of said face cams.

4. In a grinding machine a cross slide mounted on ways, power means to move said cross slide in either direction and to urge it in one direction, abutment means precisely to control final movement of said cross slide in one direction including an abutment member to abut said cross slide, face cams to control movement of said abutment member, rollers between said face cams, fluid pressure means to rotate one of said face cams and means to reposition said rollers and said cam.

5. In a grinding machine a cross slide mounted on ways, a feed shaft connected to said cross slide, means to move said cross slide in either direction and to urge it in one direction, abutment means precisely to control final movement of said cross slide in one direction including a collar on' aid shaft, an abutment member to abut said collar, a rotatable cam driving member, fluid pressure means to rotate said cam driving member, face cams arranged in connection therewith whereby rotation of said cam driving member allows further movement of said cross slide and an adjustable stop whereby said cross slide may be stopped at any predetermined location.

6. In a grinding machine a cross slide mounted on ways, a feed shaft connected to said cross slide, power means to move said cross slide in either direction and to urge it in one direction, abutment means precisely to control final movement of said cross slide in one direction including an adjustable collar on said shaft, an abutment member to abut said collar, a rotatable cam driving member, a vane motor to rotate said cam driving member, face cams arranged in connection therewith whereby rotation of said cam driving member allows further movement of said cross slide and an adjustable stop whereby said cross slide may be stopped at any predetermined location. 4

7. In a grinding machine a cross slide mounted on ways, power means to move said cross slide in either direction and to urge it in one direction, abutment means precisely to control final movement of said cross slide in one direction, face cams to control movement of said abutment means, rollers between said face cams, fluid pressure means to rotate one of said face cams and an adjustable stop whereby said cross slide may be stopped at any predetermined location.

8. In a grinding machine a cross slide mounted on ways, power means to move said cross slide in either direction and to urge it in one direction, abutment means precisely to control final movement of said cross slide in one direction, face cams to control movement of said abutment means, rollers between said face cams, fluid pressure means to rotate one of said face cams and means to reposition said rollers and said cam.

9. In a grinding machine a cross slide mounted on ways, power means to move said cross slide in either direction and to urge it in one direction, an adjustable abutting member attached to said cross slide, abutment means precisely to control final movement of said cross slide in one direction including an abutment member to abut said abutting member, face cams to control movement of said abutment member, means to rotate said face cams in timed relation with said power means and an adjustable stop whereby said cross slide may be stopped at any predetermined location.

10. In a cross slide controlling mechanism, a main shaft whose axial position determines the position of the cross slide, a sleeve around said main shaft, a vane connected to said sleeve, a circular casing in which said vane is located, a rotatable member keyed to said sleeve including a face cam, rollers engaging said face cam, said face cam having a helical surface, abutment means connecting sa d main shaft to said rotatable member, flud pressure means to move said vane in said casing, and means to urge said shaft in an axial direction, the rotation of the face cam by the vane causing a controlled movement of the main shaft.

311. in agrinding machinezacrosssslidemounted .;on ways, power :means '.to move said :cross .slide in either -'di1-'.e'ctionand tomrgeitinrone direction, and mechanism .to .limit and wontrol :the movermentgof :s aid crossislide in :the direction :in which :it is urged in order :to gpl'OdlICB 1a :fine feed, said mechanism comprising a rotatable .iface cam, a :roller :ring mounted coaxial with said iface cam,

;rollers-,o'n: saidring :in engagement -.with ;.said face :cam,*and a stationaryutrackrin.theoform-of a ring positioned to fbe-engagedEbysaid rollers on :the sides thereof opposite said Jface cam to :take the ithrust, the ;power means @urging the face warn against the rollers "which =thrust against :said atraek.

r12. 'Ina grinding machine :as claimed .-in;c1aim F11, the combination with the -pa1 ts and features therein-specified, .of theifurther-feature thatasaid :rollers "are fIUStO-BOHES and said *faee cam :and said track are also @fruSto-conitial, :these three .sparts being .of such-relative frusto-hconicalwshape that an accurate rolling engagement between them .isxa chieved.

:13. In a grinding :machine as :claimed vin :claim ,11, the combination with the :parts and features stherein specified, of resetting m'eanszfor the roller @ring comprising .a .friction device connected to \said face cam.

14. In a grinding machine as claimed in claim :12, @the combination with the pants and features vvtherein Qsnecified, LOf :resetting means :for the moiierring comprisingeaifrictionalevice :connected '15. :In-a grinding machineaa crossssiidem'ounted con ways, po-wenmeans lto move said; cross slide in :either :direction and to urge sit in :zone :direction, abutment means precisely to :control 2 final movement of said cross:slideinonezdirection including :a .movable abutment :member which allows an- ;other member to move slowly, :and mechanism :forfeedingvsaid movablezabutm'ent memberslowly thus vto produce a. finefeed comprising a face .cam',

:fluid pressure means :to crotate esaid .face "cam, a

roller ring coaxial with said face cam, rollers on saidring en aging said face cam, :means to'take the reaction i of-said rollers, -.-and iresetting :means ior the roller ring --\comprising a friction device connected .to .saidiface cam. J. MARSHALL.

REFERENCES CITED The following :references are of record in the UNITED STATES PATENTS