US2710494A

US2710494A - Grinding machine

Info

Publication number: US2710494A
Application number: US240378A
Authority: US
Inventors: Herbert A Silven
Original assignee: Norton Co
Current assignee: Saint Gobain Abrasives Inc
Priority date: 1951-08-04
Filing date: 1951-08-04
Publication date: 1955-06-14
Anticipated expiration: 1972-06-14

Description

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GRINDING MACHINE 'Filed Aug. 4. 1951 15 Sheets-Sheet 15 F E E D OF UPPER SLIDE 4496 TACK/N6 FEED T?!Untar 'HERBERT A. S/LVEN istanze/V United States Patent Office 2,710,494 Patented June 14, 1955 GRINDING MACHINE Herbert A. Silven, Worcester, Mass., assignor to Norton (lomlasny, Worcester, Mass., a corporation of Massac use Application August 4, 1951, Serial No. 240,378

22 Claims. (Cl. 51-50) The invention relates to grinding machines, and more particularly to a universal-type grinding machine.

One object of the invention is to provide a simple and thoroughly practical grinding machine for grinding or regrinding a wide variety of workpieces. Another object is to provide a grinding machine whereby workpieces may be ground either on centers or may be ground while mounted on a face plate. Another object is to provide a double swivel wheel head whereby a wide variety of angular surfaces on a workpiece may be ground.

A further object of the invention is to provide hydraulically actuated grinding Vwheel carriage and grinding wheel slides with hydraulically actuated nut and screw mechanism for traversing the carriage to position the grinding wheel relative to the work to be ground, and also to feed the grinding wheel transversely to grind the workpiece to the desired and predetermined extent. Another object is to provide a hydraulically actuated electrically controlled mechanism for remotely controlling the positioning movement of the grinding wheel carriage. Another object is to provide a hydraulically actuated electrically controlled mechanism independently to feed both of the cross slides by a remote control thereof. Another object is to provide independent manually operable remote control mechanisms for the grinding wheel carriage traversing mechanism and for both an upper and lower cross slide feeding mechanisms in which there is no mechanical connection between the control mechanism and the actuating mechanism therefor whereby the carriage and slides may be precisely adjusted during a grinding operation. A further object is to provide a tacking-type feed mechanism whereby an angularly arranged wheel spindle may be manually adjusted axially to impart a precise transverse feeding movement of the grinding wheel. Other objects will be in -part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, arrangements of parts, as will be exemplified in the structure to be hereinafter described, and the scope f the application of which will be indicated in the following claims.

One embodiment of the invention has been illustrated in the drawings, in which:

Fig. 1 is a front elevation of the improved grinding machine;

Fig. 2 is a fragmentary plan View of the grinding machine with the upper control panels .and mounting therefor removed; f

Fig. 3 is a combined electric and hydraulic diagram of the actuating mechanismsof the machine and the controls therefor; f

Fig. 4 is an hydraulic diagram, on an enlarged scale, of the controls and actuating mechanism for the longitudinally movable carriage; j l l Fig. 5 is a combined electrical and hydraulic diagram, on an enlargedscale, of the controls and actuating mechanism for the'upper slide;`

, Fig. 6 is a combinedlelectrical 'and hydraulic diagram on an enlarged scale, of the controls and actuating mechanism for the lower slide;

Fig. 7 is a vertical sectional view, on an enlarged scale, through the headstock;

Fig. 8 is a vertical cross-sectional view, on an enlarged scale, taken approximately on the line 8 8 of Fig. 1, through the grinding machine;

Fig. 9 is a fragmentary detail View, on an enlarged scale, of the grinding wheel carriage traversing and positioning mechanism; y

Fig. 10 is a fragmentary front elevation, partly in section on an enlarged scale, of the reversing control mechanism for the longitudinally movable carriage;

Fig. l1 is a plan View of the mechanism shown in Fig. 10;

Fig. 12 is a fragmentary cross-sectional view, taken approximately on the line 12--12 of Fig. 1l;

Fig. 13 is a fragmentary vertical sectional view, on an enlarged scale, through the nut and screw feed mechanism for the upper and lower slides;

Fig. 14 is a fragmentary detail view, on an enlarged scale, of the tine adjusting mechanism for controlling thev swivelling movement of the upper slide and its supporting slide;

Fig. 15 is a vertical sectional view, taken approximately 0n the line 15-15 of Fig. 14;

Fig. 16 is a fragmentary front elevation, on an enlarged scale, of the lower control station on the front of the machine, having the cover removed so as to show the control valves;

Fig. 17 is a fragmentary vertical sectional view, taken approximately on the line 17-17 of Fig. 16, through the manual control for the upper slide;

Fig. 18 is a fragmentary sectional view, taken approximately on the line 18-18 of Fig. 17;

Fig. 19 s a fragmentary front elevation, on an enlarged scale, of the upper control station on the longitudinally movable carriage, having the casing removed to show the control valves;

Fig. 20 is a plan view of the upper control station as shown in Fig. 19;

Fig. 2l is a vertical sectional view, on an enlarged scale, through the grinding Wheel head, showing the wheel spindle positioning mechanism;

Fig. 22 is a vertical sectional view, taken approximately on the line 22-22 of Fig. 21, through the wheel spindle actuating mechanism;

Fig. 23 is a front elevation of an internal grinding attachment removably mounted on the front of the wheel head;

Fig. 24 is a left-hand end elevation of the internal grinding attachment as shown in Fig. 23;

Fig. 25 is a diagrammatic view showing the grinding machine set-up to employ a tacking feed;

Fig. 26 is a diagrammatic view showing the grinding machine set-up for a shoulder or side face grinding operation;

Fig. 27 is a diagrammatic View showing the grinding machine set-up for a surface grinding operation; and

Fig. 28 is a diagrammatic view showing the grinding machine set-up for an internal grinding operation.

The improved grinding machine has been illustrated in the drawings comprising a base 10 which supports a swivel table 11. The swivel table 11 is arranged to pivot on a stud 12 which is tixedly supported on the base 10. A pair of guides and clamping

blocks

13 and 14 are provided on the base 10 for engaging and clamping opposite ends of the swivel table 11 in adjusted position to the base 10.

The swivel table 11 serves as a support for a headstock 15 and a footstock 16 is rotatably supporting a workpiece during a grinding operation (Fig. 7).

The headstock is provided with a rotatable headstock spindle 17 which is journalled in

anti-friction bearings

18 and 19 within the headstock 15'. The headstock spindle 17 is provided with a headstock center 20 for rotatably supporting the left-hand end of a workpiece. The footstock 16 is similarly provided with a footstock center 21 for rotatably supporting the righthand end of a workpiece during a grinding operation.

A suitable driving mechanism is provided for the headstock spindle comprising an electric motor 25 mounted on top of the headstock 15. The motor 25 is provided with an armature shaft 26 having a multiple V-groove pulley 27 which is connected by multiple V-belts 28 with a pulley 29 mounted on a shaft 30. The shaft 30 also supports a multiple V-groove pulley 31 which is connected by multiple V-belts 32 with a multiple V-groove pulley 33 mounted on a rotatable shaft 34. The shaft 34 is connected by means of a sprocket and link chain (not shown) with a sprocket 37 which is journalled on anti-friction bearings 38 on the wheel spindle 17. The spindle is arranged so that it may be operated as a live spindle headstock or a dead center headstock. The sprocket 37 is connected by a stud 35 with a face plate or driving plate 39. In the position as illustrated rotary motion transmitted to the sprocket 37 will be imparted to rotate the work driving plate 39 while the work center remains stationary, The driving plate 39 is provided with a driving pin 40 which is arranged to engage either a portion of the workpiece to be ground or a work driving dog mounted thereon.

A suitable mechanism is provided for holding the headstock spindle 17 stationary when it is desired to operate the headstock for dead center grinding. This mechanism may comprise a gear 41 which is keyed on the spindle 17 (Fig. 7). A slidably mounted locking pin 42 is arranged to be moved into engagement with the teeth of the gear 41 to lock the spindle 17 or may be withdrawn from engagement therewith if a live spindle grinding operation is to be performed. The locking pin 42 is slidably mounted within an aperture 43 formed within the headstock 15. The locking pin 42 is connected by a screw 44 with a block 45 having a cylindrical aperture 46 therein which engages an eccentric portion 47 of a rotatable shaft 48. The shaft 48 is journalled in bearings 49 and S0 which are mounted in the headstock 15. An actuating knob 51 is mounted on the right-hand end of the shaft 48 to facilitate actuation of the locking pin 42.

If it is desired to operate the headstock 15 as a live spindle headstock, the stud 35 may be moved toward the left (Fig. 7) into engagement with a hole in a plate 36 which is keyed to the headstock spindle 17. The actuating lznob .5l is then rotated to withdraw the locking pin 42 thereby unlocking the spindle 17. ln this position of the parts, it will be readily apparent that rotary motion transmitted to the sprocket 37 will be imparted through the stud 35 to rotate the work driving plate 39 and also to rotate the plate 36 and the headstock spindle 17.

The headstock 1S is also provided with a relatively large face plate which is mounted on the left-hand end of the headstock spindle 17 (Fig. 7). It is desirable to provide a suitable swivel adjustment for the headstock 15 so that the parts may be shifted to facilitate either a center type grinding operation or a face plate type grinding operation. The headstock 15 is pivotally supported by a vertically arranged stud 56 carried by a base plate 57 which is clamped onto the upper surface of the swivel table 11. A pair of clamping

bolts

58 and 59 are mounted on diametrically 0pposite sides of the pivot stud 56. The clamping

bolts

58 and 59 pass through clearance holes in the headstock 15 and their heads are slidably supported in a circular T-slot 60 formed in the base plate 57j. It will be readily apparent from the foregoing disclosure that.

by loosening of the clamping

bolts

58 and 59, the headstock 15 may be swivelled through 360 so as to present either the driving plate 39 and the work center 20 into an operative position, or to position the headstock 15 so that the face plate 55 is in the desired position for a grinding operation.

The grinding machine as illustrated, is a travelling wheel type machine in which the grinding wheel to be hereinafter described is supported by a longitudinally traversable grinding wheel carriage 65 which is arranged to slide longitudinally on a V-way 66 and a flatway 67 (Fig. 8) formed on the upper surface of the base 10. The grinding wheel carriage 65 is provided with a suitable traversing mechanism comprising a nut 68 depending from the underside of the carriage 65. The nut 68 meshes with a rotatable screw 69. The screw 69 is journalled in spaced

bearings

70 and 71 supported by the base 10. The rotatable screw 69 is provided with a gear 72 which meshes with a gear 73 mounted on a rotor shaft 74 of a fluid motor 75. Fluid under pressure is admitted to and exhausted from the uid motor 75 through a pair of

pipes

301 and 302 in a manner to be hereinafter described.

The grinding wheel carriage 65 is provided with a transversely arranged V-way and a atway 81 which serve as supports for a cross slide 82. The upper portion of the cross slide 82 is circular in shape and supports a swivel plate 83. The swivel plate 83 is arranged to swivel about a vertically arranged pivot stud 84. The swivel plate 83 is provided with a transversely arranged V-way 85 and a atway 86 which are arranged to support a transversely movable wheel slide 87. The upper portion of the wheel slide 87 is circular in shape and is arranged to support a wheel head 88. The wheel head 8S is arrranged to swivel about a vertically arranged pivot stud 89 carried by the wheel slide 87. The wheel head 88 serves as a support for a rotatable wheel spindle 90 which is journalled in suitable bearings 420 and 421 (Fig. 21) mounted within the wheel head 88. The wheel spindle 90 supports a pair of grinding

wheels

91 and 92 at opposite ends thereof. The spindle 90 may be driven by any suitable mechanism such as for example a motor 93 mounted on the upper portion of the wheel head 88. The motor 93 is provided with a motor shaft 94 carrying a multiple V-groovc pulley 95. The pulley 95 is connected by multiple V-belts 96 with a multiple V-groove pulley 97 mounted on the wheel spindle 90. It will be readily apparent that actuation of the motor 93 will transmit a rotary motion to the grinding

wheels

91 and 92.

A nut andscrew feeding mechanism is provided between the carriage 65 and the lower cross slide 82 whereby a transverse movement of the wheel head together with the intermediate parts may be obtained. This mechanism comprises a rotatable screw 100 Fig. 13) which is supported by a pair of spaced

anti-friction bearings

101 and 102 mounted in the base 10. The screw 100 meshes with a nut 103 which is tixedly mounted on the under side of the cross slide 82. The feed screw 100 carries a gear 104 which meshes with a gear 105. The gear 105 is mounted on a rotor shaft 106 of a fluid motor 107. Fluid under pressure is conveyed to and from the fluid motor 107 through a pair of

pipes

282 and 283 in a manner lto bc hereinafter described.

A nut and screw feeding mechanism is provided between the swivel plate 83 and the upper slide S7. A rotatable feed screw 110 is supported at one end in anti-friction bearings 111 in a slidable sleeve 112 which is keyed within a cylindrical aperture 113. The other end of. the feed screw 110 is slidably keyed within a rotatable sleeve 114. The sleeve 114 is journalled in

anti-friction bearings

115 and 116 which are supported by the swivel plate 83. A reduced cylindrical portion 117 of the feed screw 110 is slidably keyed within an aperture 118 in the sleeve 114 to to facilitate an axial movement' of the feed'screw 110 for rapidly moving the Wheel slide 87 and the wheel head 88 into an .operative or inoperative position.

In order to impart a feeding movement to the upper slide 87, a bevel gear 124 is keyed on the right-hand end of the sleeve 114 (Figs. 3 and 13). The bevel gear 124 meshes with a bevel gear 125 carried by a shaft 126. The shaft 126 is connected by a pair of

bevel gears

127 and 128 with a rotor shaft 129 of a fluid motor 130. Fluid under pressure is admitted to and exhausted from the motor 130 through a pair of

pipes

131 and 132 in a manner to be hereinafter described. It will be readily apparent from the foregoing disclosure that a double swivel adjustment is provided, namely, the wheel head 88 may be swivelled relative to the upper slide 87 and the swivel plate 83 may be swivelled relative to the lower slide 82 to facilitate grinding angular and shouldered or side faces on a workpiece being ground. In any position of the swivel plate 83, the wheel head 88, the lower slide 82 may be fed transversely relative to the base and the upper slide 87 may be fed transversely relative to Vthe swivel plate 83. By a combination of feeding movements, any angular surface may be ground on a workpiece either mounted on the work centers and 21 or on the face plate 55.

A fluid pressure system is provided for supplying fluid under pressure to the various operating mechanisms of the machine. This system may comprise a motor driven fluid pump 135 (Fig. 3) which draws fluid through a pipe 136 from a uid reservoir 137. The pump 136 forces fluid under pressure through a pipe 138 to the various operating mechanisms of the machine. A pressure relief valve 139 is connected with the pipe line 138 so that excess fluid under pressure may be bypassed through a pipe 140 into the reservoir 137.

It is desirable to provide a rapid approaching movement for the upper slide 87 to facilitate rapidly moving the grinding wheels to and from an operative position before and after a grinding operation. A hydraulically operated mechanism is provided comprising a cylinder 145 which is arranged in axial alignment with the feed screw 110. The cylinder 145 contains a slidably mounted piston 146 which is connected to one end of a piston rod 147. The other end of the piston rod 147 is iXedly connected to the slidably mounted sleeve 112 (Fig. 13) so that movement of the piston 146 will cause an axial movement of the feed screw 110 rapidly to move the upper slide 87 to and from an operative position. A suitable control mechanism is provided for controlling the admission to and exhaust of fluid from the cylinder 145. This control mechanism may comprise a control valve 148 having a slidably mounted valve member 149 which is arranged to be shifted by means of fluid under pressure admitted to and exhausted from chambers formed in the opposite ends of the valve 148 (Figs. 3 and 8). A pilot valve 150 is provided for controlling the shifting movement of the valve member 149. The pilot valve 150 is normally-held in a right-hand end position by means of a compression spring 151. A solenoid S8 is provided for shifting the pilot valve into a left-hand end position so as to admit fluid under pressure into the left-hand end chamber to shift the valve member 149 toward the right so as to change the direction of fluid under pressure passing through a pair of

pipes

152 and 153 which connect the valve 148 with the cylinder 145. A switch PB9 ora switch PB10 may be actuated to energize a relay switch CR11 to energize the solenoid S8 to initiate a rapid forward movement of the upper slide 87. A throttle valve 158 (Fig. 3) is provided for controlling the return of fluid exhausting from the valve 148 into the pipe 188 and the reservoir 137. -A switch PB11 or a switch PB12 may be actuated to breakv the circuit thereby deenergizing the solenoid S8 to return the upper slide 87 to a rearward position.- Y

It is desirable to provide suitable meansfor slowing down the rapid approaching movement before the piston 146 reachesthe end of its stroke in either direction. This is preferably accomplished by provision of a pair of throttle valves 154 and 155 which are arranged to control the admission of uid into the cylinder after the main port has been closed. A pair of ball check valves 154a and 155a are provided to allow uid under pressure to pass in one direction unrestricted by bypassing around the throttle valves 154 and 155 respectively.

In a large universal type machine, such as disclosed, it is desirable to provide adequate controls for the various mechanisms of the machine so that the operation thereof may be readily controlled from the front of the machine base or from an operators control station 160 or 161 on the longitudinally reciprocable carriage 65 (Fig. 2). A control unit 162 is mounted on the front of the machine base (Figs. l and 16). This control unit is provided with a plurality of hand wheels consisting of a hand wheel 163 for controlling the movement of the upper slide 87, a hand wheel 164 for controlling the lower slide 82 and a hand wheel 165 for controlling the carriage 65. An electrical control panel 166 is mounted above the control unit 162 (Figs. 1 and 16) whereby the various units may be controlled from the front of the machine base.

A similar control unit 162a is mounted on a bridgetype frame 168 (Figs. l and 19) which is supported on the longitudinally movable carriage 65. The control unit 162a also is provided with a plurality of hand wheels, a hand wheel 1630: for controlling the upper slide 87, a hand wheel 164a for controlling the lower slide 82 and a hand wheel 165a for controlling the movement of the carriage 65. An electrical control panel 166a is mounted on the upper portion of the control unit 162a to facilitate controlling the electrical units of the machine. An electric light bulb 156 on the upper control unit 162a is connected in series between the solenoid S3 and one side of the power lines which is illuminated when the solenoid S8 is energized visibly to indicate that the upper slide is in a forward position.

In order that the upper control unit 162a may be readily accessible and within easy reach of either the control station 160 or 161, the control unit is preferably pivotally mounted on a pivot stud 167 (Fig. 20) supported on the bridge-type frame 168. The bridge-type frame 158 is provided with an arcuate shaped plate 169 which serves as a slideway for the control unit 162a. A clamping screw 170 (Figs. l and 19) passes through an elongated arcuate slot 171 (Fig. 20) formed in the plate 169 and s screw threaded into a nut 172 carried by the unit 162a. It will be readily apparent from the foregoing disclosure that by loosening of the clamping screw 170, the control unit162a together with the electrical control panel 166e may be readily swivelled on the pivot stud 167 so as to bring the hand wheels 163:1, 164a and 165a together with the push buttons on the electrical control panel 166a within easy reach of the control station 160 or 161.

The

hand wheels

163, 163a, 164, 164a, 165 and 165a are each operatively connected to actuate independent control valves in a manner to be hereinafter described. The mechanical connections between these hand wheels and the respective control valves are identical on construction, consequently only one of these mechanisms has been illustrated in detail. As shown in Figs. 16, 17 and 18, the hand wheel 163 is keyed on a sleeve 174 which is in turn rotatably supported on a fixed shaft 175. A gear 176 is keyed on the sleeve 174 and meshes with a rack bar 177. The rack bar is connected by means of a rod 178 with a valve stem 179 of a control valve 180. A compression spring 181 is provided normally to hold the valve stem 179 and the associated parts in a central position. A cam 182is keyed on the sleeve 174 and is arranged to actuate either in actuating arm 183 or an actuating arm 184 of a limit switch LS1 or a limit switch and the cross slide 82, respectively, are preferably swashplate type rotary motors, such as, manufactured by Sundstrand Machine Tool Co. of Rockford, illinois, and covered by U. S. patent to G. A. Wahlberg, No. 2,285,476 dated June 9, 1942.

In order to provide precise and positive control of the

fluid motors

107 and 130 for controlling transverse movements of the lower slide 82 and the upper slide 87, rcspectively, balanced fluid under pressure is normally supplied through valves 200-260 to both pipes 131-132 and 282-283 leading to each of the

uid motors

130 and 107 respectively to hold the motors stationary. When it is desired to impart a feeding motion either to the lower slide 82 or the upper slide 87, the fluid pressure to one side or the other of the motor is opened to the exhaust thereby allowing the motor to transmit the desired feeding movement to either the feed screw 100 or the feed screw 110.

Actuation of either the control wheel 164 or 16411 in a counter-clockwise direction serves to actuate limit switches LS3 or LS7 respectively which are connected in parallel to energize S3 to shift the pilot valve 254 toward the right thereby shifting the valve member 261 toward the left so that pressure from the pipe 138 passes through the pipe 282 to apply pressure to one side of the Huid motor while cutting it off from the other side. At the same time movement of the control wheels 164 and 164a in a counterclockwise direction serves to shift the valve 240 or 240:1 respectively toward the right to allow exhaust of fluid from the other side of the motor 107 through the pipe 283. If either the control wheel 164 or 164a (Fig. 5) is turned only a slight distance, iluid passes through a chamber in the valve 240 or 240a out through a port 245 or 2450 and through a throttle valve 247 and through the exhaust pipe 188 to cause the motor 107 to rotate at a slow speed to cause an inching feed movement of the lower slide 82 in one direction. If either the hand wheel 164 or 164g is moved to a greater extent in a counter-clockwise direction, the Valve 240-240a is shifted further toward the right so that uid exhausting through the pipe 132 passes unrestricted through the ports 256 or 256:1 directly to the exhaust pipe 188 to cause a fast feeding movement of the slide 82 in the same direction.

If either the control wheel 164 or 164a is rotated in a clockwise direction, the limit switch L84 or L58 is actuated to energize solenoid S4 to shift the pilot valve 264 toward the left so that the valve member 261 is shifted toward the right. Fluid from the pressure pipe 138 passes through the pipe 283 to the opposite side of the motor 107. At the same time the valves 180-180.@ are moved toward the left to uncover the ports 249-2490' or the ports 257-257a to obtain either a slow or a fast exhaust of fluid from the uid motor 107 through the pipe 283 to control the speed of the movement of the motor 107 in the reverse direction.

Actuation of either the control wheel 163 or 163a in a counter-clockwise direction serves to actuate limit switches LS1` or LS5 respectively which are connected in parallel to energize S1 to shift the pilot valve 204 toward the right thereby shifting the valve member 201 toward the left so that pressure from the pipe 138 passes through the pipe 131 to apply pressure to one side of the fluid motor 130 while cutting it oif from the other side. At the same time movement of the control wheels 163 and 163a in a counter-clockwise direction serves to shift the valve 180 or 18011 respectively toward the right to allow exhaust of fluid from the other side of the motor 130 through the pipe 131. If either the control wheel 163 or 163:1 (Fig. 6) is turned only a slight distance, uid passes through a chamber in the valve 180 or 180a out through a port 185 or 185a and through a throttle valve 187 and through the exhaust pipe 188 to cause the motor 130 to rotate at a slow speed to cause an inching feed movement of the upper slide 87 in one direction.

If either the hand wheel 163 or 163a is moved to a greater extent in a counter-clockwise direction, the valve -180:1 is shifted further toward the right so that fluid exhausting through the pipe 132 passes unrestricted through the port 196 or 196:: directly to the exhaust pipe to cause a fast feeding movement of the slide 87 in the same direction.

If either the control wheel 163 or 163a is rotated in a clockwise direction, the limit switch LSZ or LSG is actuated to energize solenoid S2 to shift the pilot valve 204 toward the left so that the valve member 201 is shifted toward the right. Fluid from the pressure pipe 138 passes through the pipe 132 to the opposite side of the motor 130. At the same time the valves 180-180:1 are moved toward the left to uncover the ports 189-189a or the ports 197-197a to obtain either a slow or a fast exhaust of fluid from the uid motor 130 through the pipe 131 to control the speed of the movement of the motor 130 in the reverse direction. By control of the throttle valve 187, the rate of rotation of the feed screw 110 may be readily varied as desired. A similar port 189 is provided so that when the hand wheel 163 is rotated in a clockwise direction, the valve stem 179 will be shifted so as to open the port 189 which allows uid to exhaust from the other side of the motor through the same throttle valve 187 into the exhaust pipe 188 to control the rotation of the feed screw 110 in the opposite direction.

A suitable mechanism is provided normally to limit the rotation of the hand wheel 163 in either direction so that only sufficient movement is imparted to the valve stem 179 to open either the port 18S or the port 189 depending upon the direction of rotation of the hand wheel 163. This mechanism may comprise a slidably mounted stop pin (Fig. 17) which is supported by the hand wheel 163. The right-hand end of the pin 190 rides with an elongated arcuate slot 191 having a pair of stop surfaces 193 and 194 formed in a plate 192 which is fxedly mounted relative to the valve 180.

For a rapid transverse movement of the upper slide 87, it is desired to bypass uid around the throttle valve 187 so that a rapid movement of the upper slide 87 may be obtained when desired. A rock arm is pivotally supported on the hand wheel 163. When it is desired to obtain a rapid movement of the upper slide 87, the rock arm 195 may be rocked in a clockwise direction (Fig. 17) to withdraw the pin 190 from the slot 191 so that an increased rotary motion of the hand wheel 163 is permitted. The increased rotary motion of the hand wheel 163 serves to cause an increased motion of the valve stem 179 in either direction depending upon the direction of rotation of the hand wheel 163 so as to open either an exhaust port 196 or an exhaust port 197 which exhaust fluid from the motor 130 directly through the pipe 188 into the reservoir 137.

The hand wheel 163a is supported on a shaft 175i: carried by the upper control unit 162:1. A cam 18251 is keyed to rotate with the hand wheel 163g and is arranged to actuate the actuating arms 18311 and 184 of a pair of limit switches LSS and LS6 respectively when the hand wheel is rotated in either direction. A gear 17651 is keyed to rotate with the hand wheel 163n aud meshes with a rack bar 177a. The rack bar 177a is connected by a rod 17811 with a valve stem 179a of a control valve 180er. A compression spring 181a serves normally to hold the valve stem 179a in a central position. The valve 180g is identical in construction with the valve 180 and is provided with ports 185:1, 1.89m. 196g and 1970 which are connected with the pipes 1851-1 and 188 respectively. In the normal operation of the hand wheel 163a that is for an inching feed, the hand wheel 163a is rotated either in a clockwise direction or counter-clockwise direction to open either the port 189.11 or the port 1,854 SQ that tuid may exhaust through the pipe 186a, through the common throttle valve 187 and out through the exhaust pipe 188., If itis desired to cause a rapid movement of the upper wheel slide, therock arm 19511 is rocked to withdraw the slide pin (not shown) to allow a further rotary motion of the hand wheel 163:1 so as to open either the ports 196a or 19711 so that fluid exhausting from the system may bypass .the throttle valve 187 and pass directly into the exhaust pipe 18S. The hand wheels 163 and 163a as above described are connected in parallel so that actuation of either hand wheel operates to control the stopping and starting of the upper slide motor 130. The mechanisms above described controlled by the hand wheels 163 and 163:1 serve to provide a continuous slow or fast infeed of the upper slide in either direction.

It is desirable to provide a pick feed mechanism where? by the upper slide may be advanced in a forward or rearward direction by a predetermined increment each time the mechanism is actuated. This mechanism is preferably arranged so that a pick or incremental feed may be obtained either in a forward direction for an external grinding operation or in a rearward direction for an internal grinding operation as desired. This mechanism may consist of a fluid actuated control valve 200 having a slidably mounted valve member 201 which is normally held in a central position by a pair of compression springs 202 and 203 located in the opposite end chambers of the valve 200. A pilot valve 204 is provided for controlling the shifting movement of the valve 200. The pilot valve 204 is normally held in a central position as illustrated in Fig. 5 by opposed compression springs.

A solenoid S1 and a soleneoid S2 are provided to shift the pilot valve 204 in opposite directions to control the direction of flow of uid to the fluid motor 130. When the solenoid S1 is energized, the valve 204 is shifted toward the right to pass fluid into the right-hand end chamber of the valve 200 to shift the valve member 201 toward the left so that fluid under pressure from the pressure pipe 138 may pass through a valve chamber 205 and out through the pipe 131 so that when fluid is exhausted from the other side of the motor a transverse feeding movement may be obtained in a forward direc.

pair of pushbutton switches PB7 on the upperrcontrolunit 162a and PBS on the lower control unit 162. 'Ehepushbutton switches PB7 and yPB8 are connected in parallel to start an electric timer- 221 to close a circuit. A selector switch SL2 is provided so that either a magnetic switch CR@ or amagnetic switchCRlO maybe actuated to energize the solenoids S1-v and S2 respectively so as to cause either a feeding movement in a forward or rearward direction depending upon the set-up of the machine. Ifthe selector switch is rotated in aclockwise direction, the magnetic switch CRS is connected so that when either the pushbutton switch PB7 or PBS are actuated the timer 221 will be started to energize the switch CRS thereby energizing the solenoid VS1 to .shift the valve member 201 to cause a forward feeding increment of the upper slide motor 130.

Similarly if the selector switch is rotated in a counter clockwise direction the magnetic switch CRll.)l is connected so that when the timer 221 is set in motion `the magnetic switch CR10 is closed to energize the solenoid S2 so as toshift the valve member 201 in a directiontoward the right to pass fluid under pressure so as to cause a rearward feeding increment of the motor 130.. The electric timer 221 is adjustable so that the duration of the pick or increment may be adjusted as desired.

After the timer has run for the set period-magneticl switch CRS o r the magnetic switch CR10`is deenergizedk thereby deenergizing either the solenoid S1 or the solenoid S2 to allow the valve member 201 to return to a central or neutral position.

In order to give a precise control of the pick or incremental feed, a suitable mechanism is provided for conz trolling the exhaust of fluid from the motor 130. This from the pipe 13S passes through a valve chamber in y which is actuated by the hand wheels 164 and 16411.

thevalve 209, through a pipe 220 into a left-hand end chamberV of the valve 213 to maintain the valve 213 in its extreme right-hand end position. When either the magnetic switch CRS or CR10 is energized, contactors therein serve to close a circuit to energize the solenoid S5 so that uid from the pressure pipe 138 may pass through the valve 209, through a pipe 214, through a throttle valve 215 into the right-hand end chamber of the valve 213 to move the valve 213 toward the left. During this longitudinal shifting movement of the valve 213, fluid may exhaust from the motor 130 through the valve 200, through the pipe 212, through a valve chamber 216 in the valve 213 through a pipe 217, a ball check valve 218 and a throttle valve 219 and pass through the pipe 220, through they valve 209 into the common exhaust line 188. The speed of movement of the valve 213 is regulated by the setting of the throttle valve 215 so that a predetermined amount of fluid may be metered there- 1 through. The rate Vof exhaust of uid from the motor 1 30 is controlled by the setting of the throttle valve 219. A signal light 222 is provided so that the operator may know when the pick or incremental feed is in operation. A second pick feed cannot be obtained until the first pick feed has been completed and the timer reset to its initial position. An electric light bulb 222 on the upper control unit 162a is connected in series between the magnetic switches CR8-CR10 and the solenoid S5 and also connected in series between switches CRS-C117 and the solenoid S6 visibly to indicate that the pick feed of the upper slide 87 or the lower slide 82 is operative under control of the timer 221 or the timer 281 respectively. A similar set of controls is provided for controlling the slow and rapid feeding movement of the lower slide S2 A pair of pushbutton switches PBI and FB2 are provided forcontrolling a pick feed of the lower slide 82 as will bte-hereinafter described.

kThe handv wheel 164 mounted ou a shaft 235 on the lower control unit 162 is connected to rotate a cam 242 which is arranged to actuate the

control arms

243 and 244 of a pair of limit switches LS3 and LS4 respectively when. the hand wheel is rotated either in a counterclockwise or aclockwise direction. The hand wheel 164 is t also connected to rotate a gear 236 which meshes with aslidably 4mounted rack bar 237. The rack bar 237 is connected by a rod 238 to a valve stem 239 of the control Avalve 240. A compression spring 241 serves normally to hold the valve stem 239 in a central position. The control valve 240 is provided with a pair of ports 2.45 and 249 for controlling the slow feed of the lower slide 82. The valve 240 is also provided with a second pair of

ports

256 and 257 for controlling the rapid feedingmovement of the lower slide 82. A slidably mounted stop pin, identical with that illustrated in connection with the hand wheel 163, is provided normally to limit the rotary motion of the hand wheel 164 so that either the Vport 245 or the port 249 is opened to allow iiuid to exhaust through a pipe 246, through a throttle valve 247 and-.out-thr'ough the common exhaust pipe 188. The