US2356394A

US2356394A - Grinding machine

Info

Publication number: US2356394A
Application number: US469085A
Authority: US
Inventors: John I Garside
Original assignee: Norton Co
Current assignee: Saint Gobain Abrasives Inc
Priority date: 1942-12-15
Filing date: 1942-12-15
Publication date: 1944-08-22
Anticipated expiration: 1961-08-22

Description

Aug. 22, 1944. J. l. GARSDE GRINDING MACHINE Filed Dec. 15, 1942 3 Sheets-Sheet l Aug, 22, 1944.

J. I; GARSIDE GRINDING MACHINE Filed Dec. 15', 1942 3 Sheets-Sheet 2 Syvum 75 JDH/v f. E'HHE/DE ISI Aug. 22, 1944` J, l. csARslDE- GRINDING MACHINE s sheets-sheet. 5

Filed Dec. 15, 1942 F IG. 7

Patented Aug. 22, 1944 GRINDING MACHINE John I. Garside, West Boylston, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application December 15, 1942, Serial No. 469,685

6 Claims.

The invention relates to grinding machines and more particularly to a cylindrical type grinding machine adapted for successively grinding a plurality of shouldered portions on a work piece.

One object of the invention is to provide an improved hydraulically operated shouldered type grinding machine for precisely grinding a plurality of spaced shoulders on a Work piece. Another object of the invention is to provide a multiple stop feeding mechanism for precisely feeding the grinding wheel for grinding a plurality of spaced shoulders of different diameters. Another object of the invention is to provide a hydraulically actuated electrically controlled feeding mechanism having a plurality of stops or gauge blocks in which an electrical interlock is provided to prevent initiating an infeeding movement of the grinding wheel except when a predetermined gauge block is in a-n operative position. A further object of the invention is to provide a work table stop mechanism which is interlocked with the feed control so that the work table may be precisely positioned for grinding a predetermined shoulder on the work piece. Other objects will be in part obvious or in part pointed out hereinafter.

The invention. accordingly consists in the features of construction, combinations of elements, and arrangements of parts, as will be exemplied 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 various possible embodiments of the mechanical features of this invention,

Fig. l is a front elevation of an improved grinding machine embodying this invention;

Fig. 2 is a fragmentary front elevation on an enlarged scale of the control lever and table posifoning dog mechanism;

Fig. 3 is a fragmentary piping and wiring diagram, showing the hydraulically operated system for controlling the feeding movement of the grinding wheel together with the electrically operated control mechanism therefor;

l is a fragmentary sectional view taken app oximately on the line 4 4 of Fig. 3;

F V. 5 is a fragmentary rear elevation on an enlarged scale, of the feed stop mechanism;

Fig. 6 is a fragmentarycross sectional View, on an enlarged scale, taken approximately on the line {5 -6 of Fig. 5;

Fig. l is a fragmentary cross sectional view, approximately on the line 'i-'l of Fig. 3, taken through the control lever and showing the limit switch actuated thereby; and

Fig. 8 is a fragmentary elevation partly in section of the parts shown in Fig. 5 showing the relationship betweenthe feed gauge blocks and the hydraulically operated feed mechanism.

A grinding machine has been illustrated in the drawings comprising a base I9 which supports a longitudinally traversable Work supporting table ll. The work supporting table Il is arranged to slide transversely on a fiat way l2 and a V way (not shown) formed on the upper surface of the base Hl. The work supporting table ll serves as a support for a headstock I3 and a footstock ll which are provided with Work supporting centers l5 and I 'i respectively. The work supporting centers I5 and lG serve rotatably to support a work piece ll having a plurality of shouldered cylindrical portions to be ground.

The base l@ also serves as a support for a transversely movable Wheel slide 2S. The wheel slide 2li rotatably supports a Wheel spindle 2| in suitable bearings (not shown), A grinding Wheel 22 is mounted at one end of the Wheel spindle 2l. The grinding Wheel 22 is preferably driven by an electric motor 23 which is mounted on the upper surface of the Wheel slide 2B. A driving pulley Zil is mounted on the outer end of a motor shaft 25. The pulley 24 is preferably a multi- V-groove pulley which is connected by a multi-V belt 26 with a multiple V groove pulley 2l mounted on the right hand end of the wheel spindle (Fig. 1). The wheel slide Z!) is arranged to slide transversely relative to the base l0 on suitable ilat and V Ways (not shown) which is a well known and common feature in the grinding art.

The Work supporting table l I may be traversed longitudinally by means of a manually operable traversing mechanism comprising a manually operable traverse wheel 30 which is supported on the outer end of a shaft 3l. The inner end of the shaft 3l is provided with a gear 32 which meshes with a gear 33 mounted on a rotatable shaft 34. The shaft 34 also carries a gear 35 which meshes with a rack bar 36 depending'frcm the underside of the Work table Il. It Will be readily apparent from the foregoing disclosure that the rotation of the hand Wheel 3E! Will be imparted through the gear mechanism just described to traverse the table ll longitudinally in either direction, the direction of movement of the table'being determined by the direction of rotation of the traverse wheel 33.

lf desired, the table ll may be traversed or reciprocated longitudinally by a hydraulically operated mechanism comprising a hydraulic cylinder 40 w ich is Xedly supported on the under side of the table li. The cylinder 4t contains a pair of pistons ll and 42. 'I'he pistons 4l and 'are connected by hollow piston rods 43 and ifi respectively with

hollow brackets

45 and 45 respectively which are in turn xedly mounted on the opposite ends of the base I0.

A reversing lever 6'! is supported on a rock shaft 43 which is connected to actuate a control valve (not shown) located Within the machine base I9. A manually operable stop and start lever 49 is also mounted on the front of the machine base and is arranged to actuate a stop and start valve (not shown) to Stop and start the traversing or reciprocating movement of the work supporting table I I. The details of this hydraulic traversing or reciprocating mechanism have not Wheel feeding mechanism A wheel feeding mechanism is provided for controlling the infeeding movement of the grinding wheel 22. The wheel slide 20 is provided with a depending half nut 55 which meshes with a rotatable cross feed screw 56. The feed screw 56 is rotatably supported at one end by a bearing 51 which is supported in fixed relationship to the base I9. The other end of the feed screw 56 is rotatably journalled in a slidably mounted bearing member 58 which is slidably keyed within a cylindrically shaped aperture 59 formed within the base I9 of the machine. The feed screw may be rotated manually for adjusting the position of the grinding wheel slide 29 in setting up the machine by means of a manually operable feeding mechanism to be hereinafter described.

A reduced forward end portion 59 of the feed screw 56 is slidably keyed within a rotatable sleeve 6I which is fxedly connected to a shaft 62 which supports a gear B3. Gear 63 meshes with a gear G4 mounted on the inner end of a shaft 65 the outer end of which supports a manually operable feed wheel 66. By rotation of the feed wheel 56, the screw 58 may be rotated in either direction to cause the grinding wheel 22 and its supporting slide to move either toward or from the work piece I1. A stop pawl B1 is pivotally mounted on the front of the machine base and is arranged in the path of a stop abutment 68 to facilitate precisely stopping the infeeding movement of the grinding wheel.

In order that the wheel slide 29 may be rapidly moved toward the work supporting table II to grind a work piece I1 by the plunge-cut method, the feed screw is connected to a piston rod 10. A fluid pressure cylinder 'II is formed within the base I9 of the machine and contains a slidably mounted piston 12 which is connected with or formed integral with the piston rod 19. As illustrated in Fig. 3, the other end of the piston rod 19 is fixedly connected to the slidably mounted bearing member 58 so that when fluid under pressure is admitted to either end chamber of the cylinder 1I, the endwise movement of the piston rod 19 will be transmitted to produce an axial endwise movement of the feed screw 56 which in turn transmits this motion to produce a transverse feeding movement of the grinding wheel slide 29 and the rotatable grinding wheel 22.`

A motor driven fluid pressure pump 121 is `arranged to pump fluid through a pipe from a reservoir 1B which is located within the base I9 of the machine. The pump 14 forces fluid under pressure through a pipe 11 to a feed control valve 18. The feed'control valve 18 is preferably a piston type 'valve comprising a valve stem 19 having formed integrally therewith a plurality of valve pistons. In the position of the valve 18 (Fig. 3) fluid under pressure passing thro-ugh the pipe 11 passes through a passage 89 into a cylinder chamber 8| to move the piston 'i2 together with the wheel slide 20 and the grinding wheel 22 to a rearward or inoperative position. During the passage of fluid under pressure into the cylinder chamber 8 I, fluid is exhausted from a cylin der chamber 82 through a passage 83 and out through an exhaust pipe 84 into the reservoir 1G.

Similarly when the valve stem is shifted toward the left (Fig. 3), the direction of flow of fluid within the feed cylinder 1| will be reversed. In this position of the Valve, fluid under pressure passing through the pipe 11 will pass through the valve 18, through the passage 83 into the cylinder chamber 82 to initiate a movement of the piston 12 toward the left which in turn transmits a movement toward the left o-f the wheel slide 29 and the grinding wheel 22 to cause an approaching movement of the grinding wheel 22 toward the work piece I1.

The forward end of the valve stem 19 is provided with a spool shaped member 85 which is connected by a pin 81 with a lever 88. Lever 88 is pivotally supported by a stud 89. The lower end of the lever 88 is connected by a stud 90 and a link 9| with a pull type electric solenoid 92. The valve stem 19 is normally held in its right hand end position by means of a tension spring 93 which is connected at one end by a stud 94 with the lever 88 and is connected at the other end to stud 95 which is fixed relative to the base I9 of the machine. When it is desired to cause an infeeding movement of the grinding wheel, the solenoid 92 is energized in a manner to be hereinafter described which serves to rock the lever 88 in a counterclockwise direction to shift the valve stem 19 toward the left to initiate an infeeding movement of the grinding wheel 22.

Dash pot The piston and cylinder mechanism, above described, serves to cause the grinding wheel 22 rapidly to approach or recede from the work piece. In order to reduce the rapid approaching movement to a predetermined grinding feed, it is desirable to provide a wheel feed controlling or regulating mechanism, such as a dash pot mechanism, including a pair of dash pot pistons 91 and 98 which may be rendered effective when the grinding wheel 22 is about to engage and contact with the surface of the work to be ground. The dash pot pistons 91 and 98 are normally held in a rearward or right hand end position by means of compression springs. During the rapid approaching movement of the grinding wheel 22 the dash pot pistons 91 and 98 are inoperative.

The piston rod 19 extends toward the rear of the machine. A sleeve 99 is adjustably supported on the piston rod 19 and contains a pair of integrally formed diametrically opposed arms |98 and IDI each of which is provided with a boss which are arranged to engage the dash pot pistons 91 and 98. respectively. An adjustable collar |93 is adjustably mounted on a threaded portion |94 formed on the rear end of the piston rod 19. When fluid under pressure is admitted into the cylinder chamber 82 to cause the grinding wheel 22 to move toward the work piece I1, the rapid approaching movement continues until the adjustable collar |03 engages the end of the sleeve 99. Continued movement of the piston I2 is resisted by the dash pot pistons 91 and 98 which force fluid under pressure from the dash pot cylinders through an adjustable needle valve H35 into a reservoir |06. By adjustment of the needle valve |95, the exhaust of fluid from the dash pot cylinders may be readily controlled to produce the desired infeeding movement so that the grinding wheel 22 -will be moved into the workpiece Il to grind the same at the desired rate of speed. This dash pot mechanism is substantially the same as that shown in the United States Patent to R. A. Cole and C. H. Amidon, No. 2,191,799, dated December 7, 1937, and since this feature is not considered to be a part of the present invention, the details of the disclosure have not been completely illustrated and described herein. For details of disclosure not contained herein, reference may be had to the prior patent above mentioned.

Positive stop In order to grind a work piece I'I to a predetermined size, `it is necessary to feed the grinding wheel 2 2 toward the work piece to grind the same and then to stop the infeed and allow the grinding wheel 22 to grind out or to allow the sparks to die out in order to round up the Work so that it will be ground to a true cylindrical surface of a predetermined size. In the present disclosure, the machine as set up is provided with an adjustable stop sleeve |96 which surrounds the sleeve 99 and is held in anadiusted position thereon by means of a lock nut or collar II'I. The positive stop sleeve |96 is arranged to engage the end face of the dash pot cylinder head I S8 positively to limit the infeeding movement of the wheel slide 20 and the grinding wheel 22.

M ulti-stop It is desirable to provide a multi-stop mechanism for limiting the infeeding movement of the Wheel slide 29 so as to limit the infeeding movement of the grinding wheel 22 to facilitate successively grinding a plurality of shouldered portions on the work piece I'I to predetermined sizes. This multi-stop mechanism is preferably arranged so that it may be manually actuated and is preferably interlocked with the table traversing or reciprocating movement of the Work table II to position successive shoulders in operative relation with the grinding Wheel 22. As illustrated in the drawings (.F'ig. 5) a bracket I I|J is fixedly mounted on the rear of the machine base and is provided with a downwardly extend.-

ing portion having a bearing (not shown) Which serves as a suppo-rt for a rockshaft III. Rock shaft III supports a sector-shaped frame H2. The frame I|2 serves as a support for apair of arcuate shaped members I3 and I I4 which form an elongated slot or aperture H5 surrounding the threaded portion of the piston rod 1li. The arcuate shaped members H3 and H4 are. removably mounted on the frame I I2 so that they may be readily interchanged if desired. The arcuate shaped members H3 and H4 serve as supports for a plurality of pairs of .stop blocks or gauge blocks H6, IIBa, H1, I|'Ia,-||8 IIBa, H9, IIBa, |2|I and IZa which are arrangedso that they may be successively swung into an operative position between the stop collar |03 andthe end of the sleeve 99. The stop blocks or gauge blocks H6, HSa, III, II'Ia, H8, llaa, H9, |I9a,'|2|l and |2iio,V are resiliently supported on the arcuate members H3 and H4. The successive pairs are interposed between the collar |03 and sleeve 99, so as, to successively limit the infeeding movement of the grinding wheel 22 to produce shouldered cylindrical portions on the work piece I'I of predetermined diameters.

A manually operable mechanism is provided for shifting the'frame I I2 successively to position the feed stop or gauge blocks in operative positions comprising a manually operable lever |25 which is mounted on the forward end of a rock shaft |26. The front end of the rock shaft |25 is supported in suitable bearings (not shown) formed in the base I of the machine. The rear end of the rock shaft I 2S is supported in a bearing formed integral with the bracket H0 which is fastened to the rear of the machine base. A lever |21 is fixedly mounted on the rear end of the shaft |25' and is connected by a stud |23 with one end of a link |29. The other end of the link |29 is connected by a stud I3|l with the sectorshaped plate H2. It will be readily apparent from the foregoing disclosure that when the lever |25' is moved ineither direction, a corresponding movement will be imparted to the plate H2.

In order to facilitate locating the pairs of stop blocks successively Yin operative positions, the notched plate ISI is fixed-ly mounted on the front of the machine base adjacent to its right hand end (Figs. 1 and 3). The plate or bracket I 3| is provided with a plurality of notches |32, |33, |34, I 35 and |36. In the position illustrated in Figs. l' and 2, the lever I25a is positioned opposite the slot |34 thus locating the plate H2 with ie stop or gauge blocks I I8 and I |8a in operative position. `When it is desired to shift to grind a newl shoulder'on the work piece II, the lever |25 may be rocked in either direction to bring it into alignment with successive notches on the plate or bracket I3I. l

The upper portion of the lever |25 is pivotally mounted so that it may be readily movedA into operative engagement with the notches on the plate I3 I. A pivotally mounted lever I25a is pivotally supported by a stud I3? and is arranged so that the upper end of the lever I25a may be swung into operative engagement with the notches |32 to I 36 inclusive when desired.

Table positioning In order to precisely positionthe work piece II and the work table to precisely locate the successive shoulders on the Work piece II to be ground, a table stop mechanism is provided comprising a stop dog. |38 which is adjustably supported by the T-slot 52 on the front edge ofthe table I I. The right. hand end of the stop dog |38 is provided with a plurality of stepped shoulders or stop surfaces |39, Illl and III! which are arranged successively to positionv the work piece I1 and table i l for grinding shouldered portions I'Ia, I'Ib, and lic respectively on the Work piece Il. The notched .plate ISI also serves as a support for a plurality of stop studs |42, |43, |44, M5 These stop pins or studs are normally held in an inoperative position out of the path of the stop dog I 38 by compression springs I 4'! (Fig. 4). When the lever |25 is shifted into the desired position opposite a notch in the plate EiI corresponding'to the shoulder on the work piece to be ground, the lever |250, is rocked into engagement with the notch |34. which moves the stop stud |44 toward the right (Fig. 4) so that the stop'plunge'r It!! lies in the path of the shoulder |43 on the dog |33 so as to position the sh-ouldered portionv I Ib in operative position relative to the grinding wheel 22. After the lever |25a has been shifted into operative engagement An electrically operated wheel feed control mechanism is provided comprising a manually operable lever 50 which is pivotally supported by a stud 5| on the frontl of the machine base. When it is desired to initiate an infeeding movement of the grinding wheel, the lever |50 is rocked in a counterclockwise direction to close a switch |52 (Fig. 2) which is arranged to close a circuit to energize the solenoid 92 if the other parts of the mechanism are in an operative position. The closing of the switch |52 also starts an electrical time delay relay |53 which is arranged to control the over-all duration of the grinding cycle, that is, the rapid approach, the slow grinding feed and the period of dwell after the feed has stopped. After a predetermined time interval has elapsed the time relay operates to break the circuit to de-energize the solenoid 92 whereupon the released tension of the spring 93 shifts the valve 18 into the position illustrated in Fig. 3 to cause a rearward movement of the grinding Wheel 22. If it is desired to stop grinding at any time during the cycle, the lever |50 may be rocked in a clockwise direction to open a switch |54 thus energizing the solenoid 92 and allowing the electric time delay relay |53 to reset itself on the next operation.

Electrical interlock It is desirable to provide a suitable interlocking mechanism so that a wheel feeding movement cannot be initiated Unless the worktable has been moved to position the predetermined stop plunger in the path of the steps on the stop dog |38a. This interlock may comprise a limit switch |55 which is carried by the control lever |25. The actuating plunger |56 of the switch |55 is normally held down to hold the switch open by means of a lug |51 carried by the lever |25a. The limit switch |55 is a normally closed switch so that when the lever |25a is brought into engagement with a notch on the bar |3| the limit switch will be closed to close an electric circuit. The limit switch |55 is preferably connected in series with the wheel feed starting switch |52 so that if the lever |50 is moved to close switch |52 to initiate an infeeding movement of the grinding wheel, the feeding movement cannot be initiated until lever |25a is moved into an operative position with one of the notches on the bar |3| thus preventing a longitudinal movement of the table while grinding a predetermined shouldered portion on the work piece I1. When the lever |25a has been rocked in a counterclockwise direction (Figs. 3 and 4) into an operative position within one of the notches in the bar |3|, the switch |55 closes thus rendering the electric circuit operative so that when the feed control lever |50 is rocked to close the push button switch |52 a circuit will be completed to energize the solenoid 92 to initiate an infeedng movement of the grinding wheel 22 and at the same time to start the time delay relay |53 in operation.

In case it is desired to grind a plurality of steps |161, |1e, |1f and Hg on the left hand end of the work piece |1 (Fig. l), a plurality of stop shoulders |60, |6|, |62 and |63 are provided on the left hand end of the table stop dog |38. The table may be moved toward the right (Fig. 1) to position the successive shoulders |1d, |1e, |1f and |19 successively in operative position with respect to the grinding wheel 22. The stop studs or plungers |43, |44, |45 and |46 successively are actuated by the control lever |25a to limit the position of the table to facilitate grinding the shouldered portion on the left hand end of the work piece |1.

The operation of the improved grinding machine will be readily apparent from the foregoing disclosure. Assuming all of the mechanisms to have been previously adjusted, a work piece |1 is moved into position on the work centers |5 and i6 and the grinding wheel and work piece are then rotated. The control lever |25a is then shifted into position opposite one of the notches |32, |33, |34, |35 or |36 depending upon the shoulders to be ground. The control lever |25a is then moved into engagement with the predetermined notch after which the table start and stop lever 49 is shifted to start the movement of the table toward the right to bring a shoulder on the dog |30 into engagement with the stop stud which has been moved by the lever |25a into an operative position, the direction of movement of the table being determined by the position of the reversing lever 41. During a shoulder grinding operation. the normal table reversing dogs |50 and |5| are moved to inoperative positions out of operative relation with the reversing lever 41. The feed control lever |50 may then be rocked in a counterclockwise direction (Fig. 3) to close the starting switch 52, the switch |55 having been previously closed by actuation of the lever |25a, which serves to energize the solenoid 92 to shift the feed control valve 18 to admit the fluid under pressure in the cylinder chamber 02 to initiate a forward feeding movement of the grinding wheel 22. The forward feeding of the grinding wheel to grind a portion proceeds in the manner above described. At the same time the solenoid 92 is energized, the electrical time delay relay |53 is set in motion to govern the over all infeeding movement of the grinding wheel 22. After the predetermined time interval has elapsed the time relay |53 serves to break a circuit thus de-energizing the solenoid 92 which allows the released tension of the spring 93 to return the feed control valve 18 into the position illustrated in Fig. 3. The feed control valve 18 as illustrated in Fig. 2 admits fluid under pressure to the cylinder chamber 8| to cause a rearward movement of the piston 12, the grinding wheel slide 20, and the grinding wheel 22. After one shoulder on the work piece |1 has been ground to the desired predetermined size, the levers |25a and |25 may be shifted either toward the right or toward the left into an operative position with respect to notches in the notched plate to locate the corresponding pairs of stop blocks H6, |l1, H8, ||9 or |20 in operative position to govern the necessary infeeding movement of the grinding wheel to grind the next shoulder on the work piece to the desired and predetermined size. The other operations are then completed to grind the second shoulder and the entire cycle of operations is then completed to grind successive shoulders on the right hand end of the work piece ll'.

It will be readily apparent; from the foregoing disclosure that the limit switch |55 serves as an interlock to prevent initiating an infeeding movement of the grinding wheel unless the successive stop blocks H6, lll, H8, H9 or E26 are in operative position to control the necessary inieeding movement of the grinding wheel.

t will thus be seen that there has been provided by this invention 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 or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a grinding machine having a longitudinally movable Work supporting table, a transversely movable grinding Wheel slide, a rotatable grinding Wheel thereon, means to move said table longitudinally to feed said slide transversely including a plurality of feed stops precisely to locate said grinding Wheel successively to grind a plurality of spaced shoulders on a Work piece, an adjustable table dog, means including a plurality of table locating plungers cooperating with said dog precisely to locate said table successively in predetermined positions for said Shoulder grinding operations, and means including a control lever which is arranged when moved in one direction to actuate said feed stops to facilitate grinding a predetermined portion of the work piece to a predetermined size and when moved in another direction to actuate said table locating plungers to facilitate location of a predetermined portion of a work piece in operative relation with the grinding Wheel.

2. In a grinding machine having a longitudinally movable work supporting table, a transversely movable grinding Wheel slide, a rotatable grinding wheel thereon, means to move said table longitudinally, means to feed said slide transversely, a movable frame, means including a plurality of feed stops on said frame precisely to locate said grinding wheel successively to grind a plurality of spaced shoulders on a work piece to predetermined diameters, an adjustable table dog, means including a plurality of normally inoperative table locating plungers cooperating with said dog precisely to locate said table successively in predetermined positions for said shoulder grinding operations, and an interlock including a manually operable control lever which is movable in one direction to move said frame successively to position said feed stops in an operative position and in a second direction successively to move said table locating plungers into an operative position.

3. In a grinding machine having a longitudinally movable work supporting table, a transversely movable grinding wheel slide, a rotatable grinding wheel thereon, means to move said table longitudinally, means to feed said slide transversely, a pivotally mounted frame, means including a plurality of feed stops on said frame precisely to locate said grinding wheel successively to grind a plurality of shoulders on a work piece, an adjustable stepped dog on said table, means including a plurality of normally inoperative slidably mounted table locating plungers each of which in an operative position is in the path of one of the steps on said dog precisely to locate said table successively in predetermined positions for said shoulder grinding operations, and an interlock including a manually operable control lever which is operatively connected when moved in one direction to swing said frame successively to locate said feed stops in an operative position and when moved in a second direction successively to move said table locating piungers into operative position with relation to the stepped dog on said table.

4. In a grinding machine having a longitudinally movable work table, a transversely movable grinding wheel slide, a rotatable grinding wheel thereon, means to move said table longitudinally, means including a solenoid to initiate an infeeding movement of the grinding wheel, a plurality of spaced stops successively to limit the infeeding movement of the grinding wheel to facilitate grinding a plurality of stepped shoulders on ya work piece, a notched bar having a plurality of notches corresponding with said spaced feed stops, a pivotally mounted support for said stops, a pivotally mounted lever to actuate said stops which is arranged when in an operative position to engage one of said notches, and an interlock including an electric switch which is actuated by movement of said lever into an operative position to energize said solenoid to initiate an infeeding movement of the grinding wheel.

5. In a grinding machine having a longitudinally movable table, a transversely movable grinding wheel slide, a rotatable grinding wheel thereon, means to move said table longitudinally, means including a solenoid to initiate an infeeding movement of the slide, a plurality of spaced stops successively to limit the infeeding movement of the grinding wheel to facilitate grinding a plurality of stepped shoulders on a Work piece, a notched bar having a plurality of spaced notches corresponding with said spaced feed stops, a pivotally mounted support for said stops, a pivotally mounted lever to actuate said support and stops which is arranged when in an operative position to engage one of said notches, and an interlock including an electric switch which is actuated by movement of said lever into an operative position to energize said solenoid to initiate an infeecling movement of the grinding wheel only when said lever is in engagement with one of said notches.

6. In a grinding machine having a longitudinally movable work table, a transversely movable grinding wheel slide, a rotatable grinding wheel thereon, means to move said table longitudinally, means including a solenoid to initiate an infeeding movement of the slide, a movable support having a plurality of feed stops successively to limit the infeeding movement of the grinding wheel for grinding a plurality of shoulders on a work piece, a stepped adjustably supported dog on said table, the steps of said dog corresponding with spaced shoulders on a work piece, a plurality of plungers each of Which is positioned in the path of one of said steps on said dog, means normally to hold said plungers in an inoperative position, and a pivotally mounted control lever which is arranged so that movement in one direction serves successively to position the feed stops in an operative position and movement in another direction serves to move the corresponding table stop plunger into an operative position.

JOHN I. GARSIDE.