US3599376A

US3599376A - Apparatus for automatic grinding

Info

Publication number: US3599376A
Application number: US778208A
Authority: US
Inventors: Howard W Renner; Rolf Grzymek
Original assignee: Milacron Inc
Current assignee: Milacron Inc
Priority date: 1968-11-22
Filing date: 1968-11-22
Publication date: 1971-08-17
Anticipated expiration: 1988-08-17

Abstract

A grinding wheel is moved to a reference position by a hydraulic piston, which carries a stepping motor therewith. The stepping motor advances the grinding wheel into the workpiece at varying rates and for various distances depending on the desired size of the workpiece. After completion of advancement of the grinding wheel into the workpiece, the grinding wheel may be retracted to a predetermined distance before dwell occurs.

Description

FIG.

INVENTORS HOWARD W RENNER ROLF GRZYMEK ATTORNEY PATENIED Anal 7 l9?! SHEEY 02 0F 15 PATENTED M101 7 l97| SHEET 03 0F 15 PATENTED AUGI 712m saw on HF 15 FIG. 4

PATENTEU AusI H97! 3.599376 SHEET D7 0F 15 /|OO STOCK REMOVAL '09 /IO' Y J I MANUAL 0 CLE o3 SELECT I04 COARSE sTART I PIcKFEED HI INCREMENT FORWARD REVERSE CYCLE J MANUAL RA ID STOP I5I I55 7 PM P i sET SET MoToR MoToR RAP'D y FoRwARD REVERSE WHEELHEAD TO MACHINE FORWARD I I GRIND RETRAcT PosITIoN PosITIoN LIMIT sw. 73 LIMIT sw. 77

,. COARSE RATE souARE wAvE I T OSCILLATOR 1 /IO8 '07 RAPID RATE sQuARE WAVE HAS BEEN AMPLIFIER T OSCILLATOR SELECTED sET GAP ELIM. DOWN couNT MOTOR 7 RATE so. WAVE T PICKFEED cm. I FORWARD OSCILLATOR AND MoToR L L 1 H2 SET PICKFEED STOP AT PICKFEED V PICKFEED COUNTER COUNTER ZERO I V sET STOCK W. STOP AT vA REMOVAL No. STOCK REMO L ZERO IN IN COUNTER COUNTER couNTER I SET GAP ELIM. DowN couNT A MoToR RATE so. WAVE STOCK REM. cm.

REvERsE OSCILLATOR AND MoToR l RAPID u- WHEELHEAD TO MACHINE BACK FIG. 8

PATENTEU IuII I7 IIIII SHEET 08 0F 15 I00 STOCK REMovAL MED. FEED FINE FEED 5 H7 CYCLE |O9-\1-'nn [-1|] [Tn/H6 SELECTOR START ,1 l 4 l REV.FEED CYCLE Ill STOP -L- I wEAR coMP. STOP L CONTINUOUS CYCLING RAPID RETRACT L WHEELHEAD TO MACHINE I CONTINUE SINGLE CYCLING CYCLE CONTINUE I I UNLESS IT Is I TIME TO TRUE I LOAD N0.oN sET To MACHINE wEAR COMP. WEAR COMP. PART DIGISW. No.

PART SET MOVE D I=RoM MAcI-IINE MOTOR wEAR COMP. LOADE FORWARD AMOUNT I i l|2 RAPID WEAR GAP ELIM. wI-IE LIIEAD --To MAcI-IINE COMP. RATE SQUARE FORWARD COMPLETE WAVE osc.

DowN couNT WH AD EELHE GRIND PosITIo COUNTER FORWARD LIMIT SWITCH AND MOTOR SET STOCK REMovAL AND fl 1 C I MOTOR NUMBER STOCK REMOVAL ouNTER 0N AT 1 H8 DIGISWITCH I. NO. COUNTER ZERO OFF ON U (H2 GAP E GAP DOWN COUNT R COUNTER V |M AT RATE SQ.WAVE EL m OR OSCILLATOR AND MOTOR I FIG. 90 v I PATENTEU A1181 1 Ian SHEET 09 0F 15 I I I SURGE FINE FEED PART NQHAS BEEN CONTACT MACH'NE REACHED I I |O6\ I L COARSE COARSE DOWN COUNT TIME RATE SQUARE COUNTER TO To RATE WAVE osc. AND MOTOR TRuE MACHINE Y U I MEDIUM MEDIUM DowN COUNT sET NO ON FEED NO.HAS --RATE SQUARE w COUNTER COMP. COMPD BEEN REACHED wAvE osc. AND MoToR NUMBER DIGISWITCH I f I I FINE FEED FINE RATE DowN COUNT MovE SET NQHAS BEEN SQUARE couNTER COMP. MOTOR REAcHED wAvE osc. AND MOTOR AMOUNT FoRwARD i I24 ll2 REsET ND. COMP. AND GAP END U 0N STOCK TRUING ELRlxlgAsTgR FEED S WZII COMPLETED wAvE osc j l27 T sET No. ON REVERSE TRUING DowN COUNT REvERsE REVERSE FEED No. COMPLETE COUNTER FEED NO. FEED DIGISW. couNTER FROM MACHINE AND MDTDR sET COUNTER 7 MOTOR AT REVERSE ZERO ll2 I v AMPLIFIER RETRACT GAP ELIM. DOWgJm8UNT REvERsE RATE so. FEED AMT. wAvE osc. ffim g 'g RF. COUNTER TARRY TIMER BETTA-I AT zERo T'MER OUT I Y I.

RETRAcT RAPID RATE DowN couNT MOTOR AND so. wAvE COUNTER WHEELHEAD TO MACHINE OSCILLATOR AND MOTOR I Ioa WHEELHEAD Fl .90

BACK AND UNLOAD To MACHINE G [MOTOR BACK PART F 9 b couNTED A35 )ZCOUNTED A37 2 OUT ouT 9b PATENIEUAUBIIIBTI 3.5991376 sum 10 0F 1 STOCK REMOVAL MED. FEED 1 rloo GAGE CYCLE /H5 GRIND START SELECTOR L L COARSE FINE wEAR COMP H3 125 /-H| CYCLE STOP TRUING \I36 I COMPENSATION I33 STOP SINGLE MULTI- m CON- m w TINUOUS CYCLE CYCLE q cYcLE 1 9 Q l34 I I38 CONTINUE SINGLE CYCLE CYCLE [E I oAD T0 MACHINE P 22; FROM MACHINE RAPID {E'fg TO MACHINE FoRwARD WHEEL- HEAD GRIND POSITION FORWARD LIMIT SWITCH 73 |Io SET STOCK NUMBER COUNTER g5 gg N STOCK REMOVAL AT FORWARD DIGISW- COUNTER ZERO H8 k? I H 0 OFF ON GAP DOWN III II R 88KER EL'M'NATOR wAvE os. AND MOTOR I I I I I I I I FIG. HO

PATENTED AUG I 7 IQTI SHEET 1-1 0F 15 1 A II III I I II I I PART SURGE MED. FEED {SWITCH 0N NO HAS BEEN CONTACT MACHINE REACHED I I I I COARSE coARsE RATE DOWN RATE so.wAvE COUNT OSCILLATOR fig ug Eg I I Ioe MED. FEED v NQ HAS BEEN AD ANCE TO MACHINE REAcHEo GAGE Y l GAGE FROM ADVANCED MACHINE A06 coARsE DOWN COUNT I RATE so, '9' COUNTER FINE wAvE 050. AND MOTOR l4l f ,E FINE RATE DOWN COUNTF" E so. WAVE COUNTER DWELL '43 2 4 osc. AND MTR. I42 I Ll/J44 TARRY TIMER I IIII BO TIMER 1 RETRAcT sET TO LOAD+TB E MOTOR POSITION REVERSE sET No. STOCK ON REM. No. DIGISW. 408 RETRAcT RAPID RATE DOWN COUNT T MOTOR 7 so. WAVE c uN ER TO zERo osc. AND MOTOR I WHEELHEAD RETRACT BACK AND GAGE T0 MACHINE MOTOR BACK L UNLOAD I T0 MACHINE PART 135 I37 COUNTED -couNTEo a OUT 9 I OUT FIG. lOb

PATENTEU NIB I 7 IQII sum 12: 0F 15 SET MOTOR CONTINUE FORWARD IOU UNLESS ITIS TIME TO TRUE I FIG. lOc SET wEAR No.oN COMPENSATION WEAR coMR NUMBER DIGISW. FIG.

l {--I move GAP. ELIM. DOWN COUNT A wEAR coMP- RATE so. COUNTER AMOUNT wAvE osc. AND MOTOR G d I ll2 wEAR COMP. COMPLETE AMPLIFIER TIME T0 ---T0 MAcI-IINE TRUE i SET No. ON COMPENSATION COMP.

NUMBER DIGISWITCH SET I MOTOR FORWARD A 32 MOVE EI.IMI N A ToR cw? COMPENSAT'ON RATE so. COUNTER A AMOUNT wAvE osc. AND MOTOR I nz I 0C COMPENSATION AND TRUING COMPLETE TRUING COMPLETE I FROM MACHINE PATENTED III; I 7 Ian SHEET 13 0F 15 PIcKFEED STOCK REMOVAL p INcREMENT '5] '50 PICKFEED CYCLE GRIND sTART SELECTOR TRUING EAD PASS wEAR COMP. COMPENSATION TABLE REVERSAL ,III

CYCLE A54 STOP 136 1 I38 I {I33 |34\I I STOP SINGLE MULTI- CONTINUOUS CYCUNG CYCLE CYCLE CONTINUE SINGLE CYCLING CYCLE FEED SKIP TABLE J [N REvERsAI.

AFTER LOAD TO zERo MoToR STOP I PART T0 MACHINE GAP DOWN ELIMINATOR couNT SQUARE wAvE couNTER PART OSCILLATOR AND MoToR FROM MACHINE LOADED H2 Y I RAPID w E TO MACHlNE FORWARD I l WHEELHEAD A 4 GRIND POSITION IIO FORWARD LIMIT SWITCH 73 I I I II SET NUMBER COUNTER E STOCK ON E STOCK REMOVAL AT SET f 'fmg k DIGISW couNTER ZERO PICKFEED I I I I INCREMENT f NUMBER ON DIGISW. ||8 I52 RESET PICKFEED couNTER PICKFEED INCREMENT AT INCREMENT couNTER ZERO OFF ON V I I VI PATENTEDAUBIHQH 3599376 SHEET 1n 0F 15 CONTINUE sET H0 UNLESS IT I Is TIME MOTOR TO TRUE FORWARD I I c SET wEAR N0. ON wEAR FIG |b COMPENSATION COMPENSATION NUMBER 1 DIGISWITCH MOVE wEAR GAP ELIM. DOWN COMPENSATION RATE so. SSKQE AMOUNT WAVE OSC. AhD MOTOR WEAR H2 COMPENSATION COMPLETE AMPLIFIER TIME f To To MACHINE TRUE sET NUMBER COMPENSATIQN oN COMP.

NUMBER DIGISWITCH MovE sET COMPENSATION MOTOR AMOUNT FORWARD GAP DOWN ELIMINATOR COUNT RATE so. coUNTER wAvE 050. AND MOTOR FIG. I I0 COMPENSATION TRUING AND TRUING COMPLETE COMPLETE FROM MACHINE v PATENTED AUG! 7 l9?! FIG. Ilb

SHEET 15 HF 15 i T T GAP GAP DOWN COUNT ELIMINATOR STOCK REM. ELIMINATOR RATE so. COUNTER v 2/ wAvE 050 AND NoToR j sTo CK PART SURGE sw. REMOVAL T couNTER ACT oN MACHINE AT ZERO WAIT FOR T TABLE TABLE REVERSAL REv. L.$. L.S. 0N MACHINE MOVE GAP DOWN STOP PICK FEED ELIMINATOR COUNT BOTH WHEN EITHER RATE so. couNTERs couNTER INCREMENT wAvE osc. AND MOTOR- AT zERo STOP FEED v sET pEAo NUMBER DEAD PASS COUNTER PASS TABLE 0N TABLE REV. AT

REVERSAL DIGISW. couNTER zERo Ty sET MoToR REVERSAL. RETRAcT I 12 -33 To MACHINE 55 NUMBER REMOVAL" f I NUMBER DIGISW.

I08 RETRAcT RAPID DOWN C NT MOTOR To RATE $0. Egfi g ZERO WAVE OSC. AND MOTQR WHEELHEAD UNLOAD BACK AND To MACHINE MOTOR BACK PART COUNTED COUNTED OUT ouT 9 F APPARATUS FOR AUTOMATIC GRINDING ln presently available grinding machines, a manual handwheel is normally connected to the feed system of the machine. This requires a complicated and complex mechanism which has many mating members, thus reducing the overall rigidity of the feed system. The reduction of rigidity of the drive increases the possibility that chatter may occur, for example, whereby damage of the workpiece, which is being ground, would occur. Additionally, the lack of rigidity has an effect on the final size of the workpiece since the spring of the system increases with a reduction in rigidity.

The present invention satisfactorily solves the foregoing problem by utilizing a unique arrangement for the infeed mechanism for a grinding wheel. In the infeed mechanism of the present invention, a relatively small moment arm exists between the axis of the grinding wheel and the axis of the feed screw. This is accomplished by eliminating any requirement for a manual handwheel to control movement of the grinding wheel toward and away from the workpiece. The present invention' utilizes an automatic control for movement of the grinding wheel toward and away from the workpiece so that the complicated structure of the handwheel and its connecting means is eliminated.

In presently available grinding machines in which the manual handwheel is disposed at the front of the machine and the feed screw extends rearwardly therefrom beneath the coolant trough, the feed screw must pass through the support structure for the workpiece so that there is interference therebetween. Accordingly, if a different type of support structure is required for the workpiece, substantial modification may be required. In the present invention, the infeed mechanism is mounted only on the rear base of the machine so that it does not have any structure extending forward of the rear base. As a result, the present invention permits any type of support structure for the workpiece to be readily utilized with the rear base, which has the infeed mechanism and the wheelhead supported thereon.

in presently available grinding machines, the grinding wheel is fed into the workpiece at one or more different decreasing feed rates as the final size of the workpiece is approached. The grinding wheel must not be fed into the workpiece the entire distance that it is desired to reduce the workpiece because of the windup or spring in the grinding machine and workpiecesystem due to the feed force of the grinding wheel since this windup or spring must be removed upon completion of grinding of the workpiece. Therefore, in presently available grinding machines, advancement of the grinding wheel into the workpiece is stopped short of the desired position to which it would be moved to obtain the final desired workpiece size. The grinding wheel is retained in this position for a period of time to finally finish the workpiece as the workpiece and the grinding wheel release their spring or windup due to the grinding wheel no longer exerting a feed force on the workpiece.

In the present invention, the grinding wheel may be continuously fed into the workpiece for the distance required to produce the final size-of the workpiece. Then, the grinding wheel is retracted from the workpiece a predetermined distance before tarry or dwell occurs. Thus, when the grinding wheel is retracted from the workpiece, the windup or spring in the workpiece results in the workpiece remaining in engagement with the grinding wheel so that the desired size and finish of the workpiece is obtained. Therefore, the present invention reduces the time required to grind a workpiece and permits better control of the desired size and finish of'a workpiece than is presently available.

When utilizing an automatic grinding machine, the grinding wheel is normally advanced from a reference position for its infeed. Since the size of the grinding ,wheelreduces as wear occurs, it is desirable to be ableto-compensate for this wear at various times before truing of the grinding wheel is required.

The present invention satisfactorily meets this problem by including means to automatically compensate for wear of the grinding wheel so as to change the reference position from which the grinding wheel is fed into the workpiece. Therefore more uniformity of the size of the finished workpieces, which are produced by the automatic grinding machine of the present invention, is obtained than has been previously available.

Instead of changing the feed rate of the grinding wheel toward the workpiece at various predetermined, distances from the reference position, the feed rate of the grinding wheel toward the workpiece may be controlled by a gage. This gage would stop the final feed rate of the grinding wheel toward the workpiece when the gage indicates that the workpiece is of the desired size. Thus, instead of relying upon predetermined distances from a reference position for obtaining the desired final size of the workpiece, the present invention permits the utilization of a gage for automatically controlling when the final size of the workpiece is reached.

An object of this invention is to provide an apparatus for automatically grinding a plurality of workpieces to substantially the same size.

Another object of this invention is to provide a unique infeed mechanism for a grinding wheel.

Other objects of this invention will be readily perceived from the following description, claims, and drawings.

This invention relates to a mechanism for producing relative movement toward and away from each other between a grinding wheel and a workpiece. The invention includes a feed member adapted to be connected to one of the support means for the workpiece and a wheelhead or the like on which the grinding wheel is supported and fluid-responsive means. Means, which is connected to the feed member and to the fluid-responsive means, moves the feed member both independently of the fluid-responsive means and simultaneously therewith. The fluid-responsive means moves the feed member at a faster rate than the connected means with the connected means being movable with the fluid-responsive means to move the feed member.

This invention also relates to a mechanism for controlling the grinding of a workpiece by a grinding wheel. The mechanism includes means to feed one of the grinding wheel and the workpiece toward the other whereby one of the grinding wheel and the workpiece is a movable member and the other of the grinding wheel and the workpiece is a fixed member. The feed means feeds the movable member for a predetermined distance from a reference position with means to automatically stop feeding by the feed means when the movable member has been advanced toward the fixed member the predetermined distance from the reference position. Means retracts the movable member a predetermined distance after the stop means is actuated with the grinding wheel and the workpiece remaining in engagement with each other in the retracted position of the movable member. The movable member is held at the retracted position for a predetermined period of time by suitable means.

This invention further relates to a mechanism for controlling the grinding of a workpiece by a grinding wheel including means to feed one of the grinding wheel and the workpiece toward the other whereby one of the grinding wheel and the workpiece is a movable member and the other of the grinding wheel and the workpiece is a fixed member. The feed means feeds the movable member from a reference position with means to measure the size of the workpiece being ground. The measuring means has means to reduce the feed rate of the feed means when the workpiece has been reduced to a predetermined size by the grinding wheel as determined by the measuring means. Feeding of the movable member by the feed means is stopped by suitablemeans when the workpiece has further been reduced by the grinding wheel as determined by the measuring means.

This invention still further relates to a grinding machine including front and rear bases connected to each other with a grinding wheel mounted on the rear base by suitable means for movement relative to the rear base. The front base has workpiece support mans mounted thereon and the grinding wheel is moved toward and away from a workpiece on the workpiece support means by feed means, which is supported only on the rear base.

The attached drawings illustrate a preferred embodiment of the invention, in which:

FIG. 1 is a sectional view, partly in elevation, of the automatic grinding machine of the present invention showing the infeed mechanism;

FIG. 2 is an end elevational view of a portion of the automatic grinding machine of the present invention including the infeed mechanism;

FIG. 3 is a sectional view taken substantially along line 3-3 of FIG. 2; 7

FIG. 4 is a side elevational view of a portion of the structure of FIG. and taken from the left side of FIG. 2;

FIG.'5 is a side elevational view of the structure of FIG. 2 and taken from the right side of FIG. 2;

FIG. 6 is an enlarged sectional view, partly schematic, of a portion of the structure of FIG. 2 and showing the fluid arrangement for rapid movement of the wheelhead;

FIG. 7 is an enlarged sectional view of a clutch for connecting the feed screw to a motor;

FIG. 8 is a schematic diagram illustrating the logic when the automatic grinding machine is in the manual mode;

FIGS. 9a and 9b are schematic views illustrating the logic of the automatic grinding machine whenthe automatic grinding machine is in a plunge grind mode:

FIG. 90 is a schematic view illustrating the arrangement of FIGS. 9a and 9b;

. FIGS. 10a10c are schematic views illustrating the logic when the automatic grinding machine of the present invention is in a gage grind mode;

FIG. 10d is a schematic view illustrating the arrangement of FIGS. 10a10c;

FIGS. l1a-1lc are schematic views illustrating the logic when the automatic grinding machine of the present invention is in a pickfeed grind mode; and

FIG. 1 1d is a schematic view illustrating the arrangement of FIGS. l1a--11c.

Referring to the drawings and particularly FIG. 1, there is shown an automatic grinding machine of the present invention. The automatic grinding machine of the present invention includes a'grinding wheel 10, which is rotatably mounted on a wheelhead 11. The wheelhead 11 is adapted to be moved along ways 12 (see FIG. 2) in a rear base 14 of the grinding machine of the present invention.

The grinding wheel 10 is adapted to be advanced into engagement with a workpiece 15, which is mounted between a headstock l6 and a tailstock (not shown), for example. The headstock 16 and the tailstock are supported on a swivel table 17, which is swivelly mounted on a sliding table 18. The sliding table 18 is mounted on ways 19 of a front base 20 for movement transversely to the grinding wheel 10.

The front base 20 and the rear base 14 form the machine base of the present invention. Each of the front and rear bases is readily usable with other bases since the structure supported by each is completely separate.

The infeed mechanism for moving the grinding wheel 10 into and away from grinding engagement with the workpiece 15 includes a feed screw 21, which is connected to the wheelhead 11 through a feed or ball nut 22, a plate 23 (see FIG. 3), and a substantially U-shaped bracket 24. The bracket 24, which is fixedly secured to the wheelhead 11 by screws 25, has the plate 23 secured thereto by screws 26. Since the plate 23 has the ball nut 22 secured thereto by screws 27, the feed screw 21 is connected to the wheel head 1 1 for causing movement thereof along the ways 12.

The ball nut 22 comprises a pair of nuts 28 and 29, which are spaced from each other by a spacer 30 that determines the preload on the nuts 28 and 29. The nuts 28 and 29 and the spacer 30 are secured to each other by the screws 27, which also connect the ball nut 22 to the plate 23.

This arrangement allows the feed screw 21 to be rotatably movable relative to the feed nut 22 to transmit its rotation into axial movement of the wheelhead 11. The arrangement also allows axial movement of the wheelhead 11 by the feed screw 21 when it is axially moved by a hydraulic piston 31 (see FIG. 3).

The feed screw 21 is rotatably driven by a stepping motor 32 through a reducing unit 33. One suitable example of the stepping motor 32 is the electric stepping motor sold by Superior Electric Company as Type I-ISSO. One suitable example of the speed-reducing unit 33 is sold by United Shoe Machinery Company as Model HDUC-ZO-IOO. It should be understood that the speed-reducing unit 33 may be formed with various ratios of speed reduction depending upon the type of machine upon which the workpiece is to be ground.

The stepping motor 32 is carried on one end of the movable hydraulic piston 31, which is slidably disposed in a chamber 33' (see FIG. 6) within a hydraulic cylinder housing 34. The hydraulic cylinder housing 34 is fixedly secured against move ment by being secured to the rear base 14 by ears 35 (see FIG. 2) on the cylinder housing 34 being connected to ears 36 on the rear base 14 by screws 37.

Thus, whenever the hydraulic piston 31 is advanced from the position of FIG. 3, the wheelhead 11 will be moved along the ways 12 so that the grinding wheel is moved toward the workpiece 15. Thus, the hydraulic piston 31 allows a rapid ad vance of the grinding wheel 10 to a reference position, which is selected by the operator, from which the stepping motor 32 may be employed for advancing the grinding wheel 10 into engagement with the workpiece 15 at the desired feed rate. The stepping motor 32 is secured to the piston 31 through a 'sup port 38, which is secured to the end of the piston 31 by screws 39. The stepping motor 32 is fixed to the support 38 by screws 40.

The support 38 carries a pair of

cam rollers

41 and 42 on its flange 43. The

cam rollers

41 and 42 ride on opposite sides of a rail 44, which is supported by the hydraulic cylinder housing 34. Thus, the

cam rollers

41 and 42 and the rail 44 insure that any rotation of the feed screw 21 by the stepping motor 32 is transformed into axial motion of the wheelhead 11 and the grinding wheel 10. Furthermore, the

cam rollers

41 and 42 cooperate with the rail 44 to insure that only axial movement of the hydraulic piston 31 occurs when the hydraulic piston 31 is actuated.

In addition to rotation of the feed screw 21 by the stepping motor 32, the'feed screw 21 also may be rotated by an AC induction motor 45, which is supported on the rear base 14. The induction motor 45 drives the wheelhead 11 at a more rapid rate than is available with the stepping motor 32. The motor 45 has its output shaft connected through a shaft 45a having flexible couplings therein to a vertically disposed shaft 45b, which is rotatably supported by the base 14, through a worm 450 on the shaft 45a and a worm wheel 45d on the lower end of the shaft 45b. Accordingly, the motor 45 rotates the shaft 451:.

The upper end of the shaft 45b has a bevel gear 46 mounted thereon for meshing with a bevel gear 46a, which is secured to an annular member 46b (see FIG. 7). The member 46b is secured to a member 46c having a thin annular section 46d forming a 'wall of a recess 46e within the

members

46b and 46c. Fluid is supplied to the recess 46e through an annular passage 46f, which is in communication with a source of fluid under pressure, in the member 46b.

The member 460 is mounted in surrounding relationship to a bushing 47, which has splines on its inner surface for cooperation with a splined shaft 48. When fluid is supplied to i the recess 46e, the thin annular section 46d is deflected inwardly to grip the bushing 47 and cause rotation of the shaft 48 through the splined, connection on the shaft 48 and in the bushing 47.

Whenever there is no fluid pressure in the recess 46c, the torque motor 45 cannotrotate the feed screw 21. However, rotation of the feed screw 21 by the stepping motor 32 can occur and result in the splined shaft 48 rotating without any effect n the drive from the motor 45 since the thin annular section 46d is not gripping the bushing 47. Additionally, the bushing 47 allows axial movement of the feed screw 21 and the splined shaft 48 relative thereto when the wheelhead 11 is ad- .vanced by the piston 31.

It should be understood that the logic circuit of the present invention prevents actuation of the motor 45 if the motor 32 is energized and vice versa. Thus, there can be no inadvertent attempt by the

motors

32 and 45 to simultaneously drive the feed screw 21.

The actuation of the hydraulic piston 31 is controlled through a suitable fluid system. The system includes a pump 50, which supplies fluid from a reservoir 50', connected to an inlet port of a valve 51, which is controlled by a solenoid 52. When the solenoid 52 is not energized, the valve 51 is disposed in the position shown in FIG. 6 whereby the pump 50 communicates through the valve 51 with a line 53, which leads to a valve 54. The valve 54 is disposed in the position of FIG. 6 when a solenoid 55, which controls the position of the valve 54, is not energized. In the position of the

valves

51 and 54 as shown in FIG. 6, the fluid is supplied from the pump 50 to cause retraction of the piston 31 so as to retract the grinding wheel rapidly away from the workpiece 15. This fluid is supplied from the'pump 50 through a line 56 to the interior of the housing 34 to act on the piston 31.

When it is desired to advance the grinding wheel 10 toward the workpiece 15, the solenoid 55 is energized whereby the fluid from the pump 50 is supplied through a line 57 to the interior of the hydraulic cylinder housing 34. This acts on the piston 31 to rapidly move the grinding wheel 10 toward the workpiece 15. However, the amount. of movement of the piston 31 is such that the grinding wheel 10 is not moved into engagement with the workpiece 15. i

As shown in FIG. 6, the piston 31 is beveled at each end. Accordingly, when fluid is supplied through the line 57 to advance the grinding wheel 10 toward the workpiece 15, the fluid passes from the line 57 through a chamber 58 in the housing 34, a line 59, a valve 60, and a line 61. As the piston 31 advances through the chamber 33' in the housing 34 to the right as shown in FIG. 6, the fluid on the right side of the piston 31 exits therefrom through a line 62, a valve 63, and the line 56.

As soon as the solenoid 55 is energized, fluid under pressure is supplied to the line 57 and to the left side of a freely movable piston 69, which is disposed within the chamber 58 in the housing 34. Because the chamber 58 communicates with the line 56 through a line 75, the right side of the piston 69 is exposed to exhaust pressure. Thus, as fluid is applied to the left side of the piston 69, the piston 69 is driven to the right to allow fluid to pass through the

lines

59 and 61 to the left side of the piston 31.

As the piston 31 approaches the end of the chamber 33' in the housing 34 in which it is movable, it gradually closes the line 62 causing the wheelhead 11 to be decelerated. After the line 62 is closed by the piston 31, the fluid exits from the chamber 33 through a line 64 into the valve 63. The line 64 communicates with the line 56 through a ball valve 65, which forms part of the valve 63, and is resiliently biased by a spring 66 into engagement with one end of a threaded stud 67. By adjusting the position of the threaded stud 67, the position of the ball valve 65 within housing 68 of the valve 63 is changed.

Thus, the position of the threaded stud 67 in the valve housing 68 regulates the final approach rate of movement of the piston 31 as it completes its advance movement.

A control rod 70, which is slidably mounted within the housing 34, has a clamping ring 71 adjustably mounted thereon. The clamping rod 71 is engaged by a member 72, which is carried by the support 38 so as to be movable with the piston 31. Thus, as the piston 31 advances to the right in FIG. 6, the member 72 on the support 38 engages the clamping ring 71 and starts movement of the control rod 70. This moves the rod 70 into the chamber 58 as indicated in dotted lines.

When the piston 31 completes its forward movement, a switch 73, which is carried on the housing 34, has its arm 73' engaged by a pin 74 (see FIG. 4) on the support 38. This indicates to the logic circuit of the present invention that the piston 31 has completed its forward movement and the stepping motor 32 may now be energized.

When it is desired to retract the piston 31 from its forwardmost position, the solenoid 55 is deenergized to change the position of the valve 54 to allow fluid to be supplied to the chamber 33' through the line 56 and exhausted from the chamber 33' through the line 57. The fluid initially enters the chamber 33' by flowing form the line 56 past the ball valve 65 in the valve housing 68 into the line 64. This results in the fluid acting on the beveled portion of the piston 31. i

As the piston 31 is retracted by the pressurized fluid, the line 62 is'uncovered. As a result, the fluid flow past the ball valve 65 and through the line 64 becomes negligible.

As the piston 31 retracts, the fluid flows from the chamber 33 through the line 61, the valve 60, and the line 59 to the chamber 58 and then through the line 57. At this time, the piston 69 is not disposed in the solid line position of FIG. 6. However, the chamber 58, which has the piston 69 therein, is receiving fluid from the line 56 through the line 75, which provides communication from the line 56 to the chamber 58. Therefore, fluid pressure acts on the right side of the piston 69 to cause it to move the control rod 70 to the left. The amount of movement of the control rod 70 by the piston 69 is limited by the clamping ring 71 engaging the member 72 on the support 38. Since the member 72 is moving with the piston 31, the piston 69 cannot move the control rod 70 any further than the piston 31 has moved. i

As the piston 31 retracts, the control rod 70 is continued to be moved by the piston 69 until the piston 69 blocks the line 59 from communication with the line 57. When this occurs, fluid exhausting from the chamber 33 through the line 61 is stopped so that retraction of the piston 31 by fluid entering the chamber 33' from the line 56 is stopped. Therefore, as soon as the piston 69 blocks the line 59 from communicating with the line 57, retraction of the piston 31 is stopped.

The piston 69 has its left end beveled so that the flow from the line 59 to the line 57 is cut off smoothly. Thus, a smooth deceleration of the piston 31 occurs.

When the retraction of the piston 31 is stopped, a switch 76, which is carried by the housing 34, is actuated through having its arm 77 engaged by a clamping ring 78; the ring 78 is mounted on the control rod 70 on the opposite side of the member 72 from the ring 71. The actuation of the switch 76 provides a signal to the logic circuit of the grinding machine to indicate that retraction of the piston 31 has stopped. This results in energization of the solenoid 52 to move the valve 51 to a position in which the fluid on each side of the piston 31 is trapped therein so as to prevent any further movement of the piston 31.

Whenever it is desired to reduce the amount of retraction of the piston 31, it is only necessary to move the clamping ring 71 to the right. As a result, the control rod 70 will not be moved by the piston 31 as far to the right during its advancement. Thus, the piston 69 does not have to move as far to the left to block the line 59 from communication with the line 57 during retraction.

When it is desired to retract the piston 31 the complete length of the chamber 33', it is necessary to prevent fluid flow from the line 56 into the chamber 58 through the line 75. To accomplish this, the line 75 has a plug 79 therein to cause the fluid flowing through the line 75 to have to pass through a valve 80, which is controlled by a solenoid 81. During normal operations, the solenoid 81 is deenergized to allow flow through the line 75. Y When it is desired to retract the piston 31 the entire length of the chamber 33, the solenoid 81 is energized whereby the line 75 no longer provides communication from the line 56 to the chamber 58. As a result, the piston 69 is not moved by fluid pressure to block communication between the

lines

57 and 59.

Therefore, fluid continues to escape from the chamber 33 through the line 61, the valve 60, and the line 59 to the line 57 until the line 61 is blocked by the piston 31. When the line 61 is blocked, a line 82, which communicates with the line 59 through a passage in housing 84 of the valve 60 in which a ball valve 83 is disposed, has fluid flowing therethrough to the line 59. The position of the ball valve 83, which is resiliently biased against one end of a threaded stud 85 by a spring 86, is adjusted by the threaded stud 85 in the housing 84 to regulate the final approach rate of movement of the piston 31. It should be noted that the left side of the piston 31 is beveled in the same manner as the right side to aid in deceleration of the piston 31 during full retraction.

When the piston 31 is completely retracted, this position of the piston 31 is indicated to the logic circuit of the present invention through actuating a switch 87 (see FIG. 4), which is supported on the housing 34, by having its arm 88 engaged by the pin 74 on the support 38, which is carried with the piston 31. This allows the logic circuit to proceed with the additional operations of the grinding process.

In order to limit rearward movement of the feed screw 21, a limit switch 89 (see FIG. 2) is mounted on the support 38 by a bracket 90. When a roller 91 on an arm 92 of the limit switch 89 is engaged by a setscrew 93 on the wheelhead 11, the limit switch 89 indicates this to the logic circuit and stops further rearward movement of the stepping motor 32 or the motor 45. Accordingly, neither the stepping motor 32 nor the motor 45 can be energized to cause further rearward movement of the feed screw 21 once the switch 89 has been actuated.

Forward movement of the feed screw 21 is stopped by a limit switch 94, which is mounted on the support 38 by a bracket 95. When a roller 96 on an arm 97 of the switch 94 is engaged by a block 97' on a rod 98, which is supported by the wheelhead 1 l, the switch 94 is actuated to indicate to the logic circuit that forward movement of the feed screw 21 must be stopped. Accordingly, neither the stepping motor nor the motor 45 can be energized to cause further forward movement of the feed screw 21 once the switch 94 has been actuated. The rod 98, which is supported within passages in cars 99 and 990 (see FIG. on a flange 99b of the bracket 95, is actuated by the wheelhead 11 when the feed screw 21 has been advanced the permissible maximum by the stepping motor 32 or the motor 45. When the rod 98 is moved by the wheelhead 1 1, the block on the rod 98 actuates the switch 94.

It should be understood that a spring 990, which surrounds the rod 98 between the

ears

99 and 99a, continuously urges the block 97' on the rod 98 away from the roller 96. Thus, after the switch 94 is actuated, rearward movement of the wheelhead 1 1 results in the block 97 on the rod 98 ceasing to engage the roller 96 due to the force of the spring 990.

The infeed mechanism of the present invention may be readily utilized for plunge grinding, gage grinding, or pickfeed grinding. The logic of the grinding machine permits utilization of these various cycles automatically. The operation of the grinding machine of the present invention will be described through schematic diagrams to indicate the logic circuits whereby the various automatic grinding cycles may be carried out.

Referring to FIG. 8, there is shown a schematic block diagram of the logic circuit employed in a manual mode whereby a desired or selected reference position of the stepping motor 32 for each cycle will be determined. After a manual select button 101 is pushed to select the manual mode, actuation of'a cycle start button 100 advances the grinding wheel rapidly toward the workpiece through causing fluid to be supplied to the chamber 33 to act on the piston 31 to advance the piston 31. Thus, actuation of the button 100 causes deenergization of the solenoid 52 (see FIG. 6) and energization of the solenoid 55 whereby the piston 31 maybe rapidly advanced.

When the grinding wheel 10 has been advanced as far as is possible by the piston 31, this is indicated to the logic circuit by the actuation of the switch 73. Only after the switch 73 is actuated can the stepping motor 32 be moved to cause forward movement of the grinding wheel 10 toward the workpiece or part 15.

In the manual mode, only the coarse rate and rapid rate of movement of the stepping motor 32 are utilized and available for moving the grinding wheel 10. While the stepping motor 32 may be moved at medium and fine feed rates, these feed rates are not available in the manual mode. The stepping motor 32 is moved at the rapid rate, which is faster than the coarse rate, by actuating a rapid button 102.

When the manual select button 101 is actuated, the stepping motor 32 may be moved either in a forward or reverse direction through pushing a forward button 103 or a reverse button 104. Since the manual mode is used to set up the movement of the machine for the automatic modes of the present invention, the forward button 103 is normally moved initially. This sets the stepping motor 32 in a forward direction but the logic circuit does not permit actuation of the stepping motor 32 until the switch 73 has been actuated to indicate that the grinding wheel 10 is positioned for grinding; this is indicated in FIG. 8 by a block 105.

Thus, when the switch 73 has been actuated to indicate that the piston 31 has completed advance movement, then the stepping motor 32 may be moved at either the coarse rate or the rapid rate. A coarse rate square wave oscillator 106 is energized whenever the forward button 103 is pushed if the switch 73 has been actuated. The output of the square wave oscillator 106 is supplied through an amplifier 107 to the stepping motor 32 to cause the 'forward stepping of the stepping motor 32 at the coarse rate. When the rapid button 102 is actuated along with the forward button 103, the stepping motor 32 is advanced at a more rapid rate due to energization of a rapid rate square wave oscillator 108.

The stepping motor 32 remains energized by holding the forward button 103 actuated until the grinding wheel 10 has engaged the workpiece 15 sufficiently to clean up the workpiece or part 15 so that it may be measured for size. Then, a stock removal thumbwheel switch 109 has a desired amount of stock removal set thereon and on a stock removal number counter 110.

A cycle stop button 111 is then pushed to cause rapid retraction of the grinding wheel 10 away from the workpiece 15. This is accomplished through the button 111 causing deenergization of the solenoids 55 and 52 (see FIG. 6) through the logic circuit. At the same time, the cycle stop button 111 causes the logic circuit to set the stepping motor 32 to run in the reverse direction, set in the stock removal distance from the switch 109, and run the stepping motor 32 at a frequency of a gap eliminator rate square wave oscillator 112 until the counter reaches zero. Now the size of the workpiece 15 is determined and any additional required reduction in size of the workpiece is added to the stock removal switch 109. Thus, during an automatic mode, the stepping motor 32 is advanced from the selected reference position, which is where it is now positioned, not only the original amount that was placed on the stock removal switch 109 but also the amount that was added by the operator.

In the manual mode of operation, the coarse rate at which the stepping motor 32 is fed may be changed through movement of a coarse dial 113. This alters the output of the coarse rate square wave oscillator 106 through changing the value of a potentiometer in the oscillator 106.

After the stock removal switch 109 has had the desired amount of movement of the stepping motor 32 from its reference position, which has been selected due to the initial amount that the stepping motor 32 was backed off from the workpiece 15 after cleaning up the workpiece 15, registered thereon by the operator, automatic plunge grinding of the workpieces or parts 15 may be accomplished through utilizing the logic circuit of-the present invention as indicated in FIGS.

Claims

1. A mechanism for producing relative movement toward and away from each other between a tool of a machine tool and a workpiece comprising: a feed member; fluid-responsive means including: a housing having a chamber therein; and a piston disposed in said chamber in said housing to produce relative translational movement between said housing and said piston when fluid is supplied to said chamber; said piston having means to rotatably support said feed member; first means connecting said piston to said feed member; said first connecting man including motive means to rotate said feed member relative to said fluid-responsive means; means to prevent relative rotation between said motive means and said housing; said means to connect one of said feed member and said housing to the movable one of the workpiece and the tool and to connect the other of said feed member and said housing to a fixed structure; and said second connecting means including means to convert rotational movement of said feed member to translational movement of the movable one of the workpiece and the tool; said motive means rotating said feed member both independently of movement of the movable one of said piston and said housing due to fluid supplied to said chamber and simultaneously therewith.

2. The mechanism according to claim 1 including means to regulate the rate of movement of said fluid-responsive means.

3. The mechanism according to claim 1 in which: said fluid-responsive means and said motive means are mounted concentrically with said feed member; and said fluid-responsive means is in surrounding relation to a portion of said feed member.

4. The mechanism according to claim 1 in which said motive means is a stepping motor.

5. The mechanism according to claim 1 in which: said second connecting means includes: means to connect said feed member to the movable one of the workpiece and the tool; and means to connect said housing to the fixed structure; and said feed member both rotates and translates simultaneously or independently to impart movement to the movable one of the workpiece and the tool.

6. The mechanism according to claim 5 including: drive means adapted to be connected to said feed member for moving said feed member independently of said motive means and said fluid-responsive means; and means to selectively connect said drive means to said feed member, said drive means moving said feed member at a faster rate than said motive means but a slower rate than said fluid-responsive means.

7. A mechanism for controlling the grinding of a workpiece by a grinding wheel including: mean to feed one of the grinding wheel and the workpiece toward the other whereby the one of the grinding wheel and the workpiece is a movable member and the other of the grinding wheel and the workpiece is a fixed member, said feed means feeding the movable member for a predetermined distance from a reference position; means to automatically stop feeding by said feed means when the movable member has been advanced toward the fixed member the predetermined distance from the reference position; means to retract the movable member a predetermined distance after said stop means is actuated, the grinding wheel and the workpiece remaining in engagement with each other in the retracted position of the movable member; and means to hold the movable member at the retracted position for a predetermined period of time.

8. The mechanism according to claim 7 including means to move the reference position a predetermined distance closer to the fixed member after a predetermined number of the workpieces has been ground.

9. The mechanism according to claim 7 including means to rapidly move the movable member to the reference position.

10. The mechanism according to claim 7 including means to vary the predetermined distance that said retracting means retracts the movable member.

11. The mechanism according to claim 7 including means to vary the predetermined period of time during which said holding means is effective.

12. The mechanism according to claim 7 in which: said feed means comprises: motive means; and speed-reducing means.

13. The mechanism according to claim 12 in which said motive means is a stepping motor.

14. A mechanism for controlling the grinding of a workpiece by a grinding wheel including: means to feed one of the grinding wheel and the workpiece toward the other whereby the one of the grinding wheel and the workpiece is a movable member and the other of the grinding wheel and the workpiece is a fixed member, said feed means feeding the movable member from a reference position; means to measure the size of the workpiece being ground; said measuring means having means to reduce the feed rate of said feed means when the workpiece has been reduced to a predetermined size by the grinding wheel as determined by said measuring means; means to stop feeding of the movable member by said feed means when the workpiece has further been reduced by the grinding wheel as determined by said measuring means; means to retract the movable member a predetermined distance after said stop means is actuated, the grinding wheel and the workpiece remaining in engagement with each other in the retracted position; and means to hold the movable member at the retracted position for a predetermined period of time.

15. The mechanism according to claim 14 including means to vary the predetermined period of time during which said hold means is effective.

16. The mechanism according to claim 5 in which said means connecting said feed member to the movable one of the workpiece and the tool includes means to simultaneously transfer the translation and rotational movement of said feed member to translational movement of the movable one of the workpiece and the tool.

17. The mechanism according to claim 1 in which: said motive means is connected to said piston; said first connecting means includes means connecting said motive means to said feed member; and said preventing means prevents rotation of said motive means and said piston relative to said housing when said motive means is activated.

18. The mechanism according to claim 17 in which said connecting means connecting said motive means to said feed member includes speed-reducing means.

19. The mechanism according to claim 1 in which said motive means comprises means to rotate said feed member in either direction.

20. The mechanism according to claim 19 including means to limit the rotation of said feed member in either direction by said motive means in accordance with the relative position between the workpiece and the tool.

21. The mechanism according to claim 1 including means to selectively change the rate of rotation of said feed member by said motive means during movement of the movable one of the workpiece and the tool.

22. The mechanism according to claim 1 including means to selectively control the amount of relative translational movement between said housing and said piston.