US2722088A - Grinding machine - Google Patents

Description

Nov. 1, 1955 o. E. HILL 2,722,088

GRINDING MACHINE Filed Feb. 8, 1954 5 Sheets-Sheet l INVENTOR. O/ VA E. HILL Nov. 1, 1955 o. E. HILL 2,722,088

GRINDING MACHINE Filed Feb. 8, 1954 5 Sheets-Sheet 2 I VENTOR. O/VA HILL HTTOENEY Nov. 1, 1955 o. E. HILL 2,722,083

GRINDING MACHINE Filed Feb. 8, 1954 5 Sheets-Sheet 5 /4 Fig.3 35C: 2

INVENTOR. 01 VA E. H// L H TTOENE Y Nov. 1, 1955 o. E. HILL 2,722,088

GRINDING MACHINE Filed Feb. 8, 1954 5 Sheets-Sheet 5 C INVENTOR. O/l/H H/LL United States Patent GRINDING MACHINE Oiva E. Hill, Worcester, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application February 8, 1954, Serial No. 408,899 10 Claims. (Cl. 51-105) The invention relates to grinding machines and more particularly to a semi-automatic multiple wheel grinding machine.

One object of the invention is to provide a simple and thoroughly practical multiple wheel grinding machine for simultaneously grinding a plurality of spaced portions on a work piece. Another object is to provide a multiple wheel grinding machine which is semi-automatic in operation. Another object is to provide an automatically actuated work loading apparatus for positioning a work piece to be ground in alignment with the work supporting centers before grinding and to remove a work piece therefrom after a grinding operation has been completed. Another object of the invention is to provide a mechanism for automatically moving the footstock center into operative supporting engagement with the work piece. 'Another object of the invention is to provide means for automatically positioning the work piece axially into a predetermined relationship with the grinding wheels. A further object of the invention is to provide work steadying rests which are automatically moved into operative supporting engagement with the work piece by and in timed relation with the wheel feeding mechanism after the work piece has been rough ground to a predetermined extent. Other objects will be in part obvious or in part pointed out hereinafter.

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

Fig. l is a plan view of a multiple wheel grinding machine;

Fig. 2 is a cross sectional view, on an enlarged scale, taken approximately on the line 2-2 of Fig. 1, through the wheel feeding mechanism;

Fig. 3 is a plan view partly in section, on an enlarged scale, of the work loading mechanism;

, Fig. 4 is a cross sectional view, on an enlarged scale taken approximately on the line the work loading mechanism;

Fig. 5 is a cross sectional view, on an enlarged scale, taken approximately on the line 55 of Fig. 3, through the work loader actuating mechanism; and

Fig. 6 is a combined hydraulic and electric diagram of the actuating mechanisms of the machine and the controls therefor.

A multiple wheel grinding machine has been illustrated in the drawings comprising a base 10 having a longitudinally movable work table 11 slidably supported on a flat way 12 and a V-way 13 formed on the upper surface of the base 10. The table 11 serves as a support for a headstock 14 and a footstock 15 having centers 16 and 17 respectively for rotatably supporting a work piece to be ground. The headstock 14 may be driven by an electric motor 18 mounted on the upper surface thereof.

A manually operable traverse mechanism may be provided which may be of the old and well known type such as, for example, that shown in the expired U. S. patent to C. H. Norton No. 762,838 dated June 14, 1904, to which reference may be had for details of disclosure not 44 of Fig. 3, through contained herein. A manually operable traverse wheel 19 is rotatably supported on the front of the machine base 10 for actuating the traversing mechanism (not shown) to position the table 11 longitudinally relative to the base 10 The base 10 also serves as a support for a transversely movable wheel slide 25 supported on a transversely arranged flat way 26 and a V-Way 27 formed on the upper surface of the base 10. The wheel slide 25 rotatably supports a wheel spindle 28 which is journalled in suitable bearings (not shown). The wheel spindle 28 is arranged to support a plurality of spaced grinding wheels 29, 29a, 29b, 29c and 29d. A driving mechanism is provided for the wheel spindle 28 comprising an electric motor 30 mounted on the uper surface of a wheel guard 24. The motor 30 is provided with a motor shaft 31 supporting a multiple V-groove pulley 32 which is connected by multiple V-belts 33 with a multiple V-groove pulley 34 mounted on the right hand end of the wheel spindle 28 (Fig. 1).

A suitable feeding mechanism is provided for feeding the wheel slide 25 transversely relative to the base 10. This mechanism may comprise a rotatable feed screw 35 which meshes with or engages a rotatable feed nut 36. The feed nut 36 is rotatably supported in a pair of spaced anti-friction bearings 37 and 38 which are supported in a housing 39 depending from the underside of the wheel slide 25. The right hand end of the feed screw 35 (Fig. 2) is rotatably supported by a slidably mounted sleeve 40 which is journalled in a cylindrical aperture 41 formed in the base 10. The left hand end of the feed screw 35 is provided with a reduced cylindrical portion which is slidsupport a stop abutment 52a.

'this movement of the pawl 53, the lower end ably keyed within a rotatable sleeve 42. The sleeve 42 is journalled in an anti-friction bearing 43 which is supported by the base It). A rotatable shaft 44 is slidably keyed within the left hand end of the sleeve 42.

A manually operable feeding mechanism is provided for actuating the feed screw 35 to cause a transverse feeding movement of the wheel slide 25. This mechanism may comprise a rotatable feed wheel 45 located on the front of the machine base 10. The feed wheel 45 is arranged to rotate a gear 46 meshing with a gear 47 which is mounted on a rotatable shaft 48. The shaft 48 also supports a gear 49 meshing with a gear 50. The gear 50 meshes with a gear 51 mounted on the left hand end of the rotatable shaft 44. A stop abutment mechanism, is provided for positively stopping the rotary motion of the feed screw 35 thereby limiting the infeeding movement of the grinding wheel 29. This mechanism may comprise a micrometer adjusting mechanism 45a carried by the feed wheel 45 which is arranged to adjustably The micrometer adjusting mechanism is an old and well known mechanism, such as, for example that shown in the expired U. S. patent to C. H. Norton No. 762,838 dated June 14, 1904, and H. L. Swainey No. 2,639,563 dated May 23, 1953, to which reference may be had for details of disclosure not contained herein. It will be readily apparent from the foregoing disclosure that a rotary motion of the feed wheel 45 will be transmitted through the gear mechanism above described to impart a rotary motion to the feed screw 35 thereby transmitting a transverse feeding movement to the Wheel slide 25 and the grinding wheels 29, 29a, 29b, 29c and 29:1. The direction of rotation of the feed wheel 45 serves to determine the direction of the transverse movement of the wheel slide 25.

A cam 52 formed integral with the stop abutment is adjustably supported on the feed wheel 45 and is arranged to engage a cam face formed on the upper end of a pawl 53 to rock the pawl 53 in a counter-clockwise direction about its supporting pivot stud 54. During thereof rocks away from the actuating roller of a normally closed limit switch LS7 and allows the limit switch to close. The closing of the limit switch closes a circuit in a manner to be hereinafter described to move the work steadyrest shoes into operative engagement with the work piece being ground. The steadyrest shoes are moved in an operative position for the finish grinding operation, just a short time before a stop abutment 52a on the feed wheel 45 engages the upper end of the stop pawl 53 to limit the infeeding movement of the grinding wheel slide.

In order to cause a rapid transverse positioning movement of the wheel slide 25 relative to the base 10, a hydraulically operated mechanism is provided comprising a fluid pressure cylinder 55 which contains a slidably mounted piston 56. The piston 56 is connected to the right hand end of a piston rod 57, the left hand end of which is operatively connected to the sleeve 40. When fluid under pressure is passed through a pipe 58 into a cylinder chamber 59, the piston 56 together with the feed screw 35 will be moved rapidly toward the left to impart a corresponding movement to the wheel slide 25 and the grinding wheels 29. During this movement, fluid within a cylinder chamber 60 may exhaust through a pipe 61. A feed control valve 62 is provided for controlling the admission to and exhaust of fluid under pressure from the cylinder 55.

A grinding wheel feeding mechanism may be provided for imparting a slow rotary motion to the feed screw 35 in a manner substantially identical with that shown in my prior U. S. Patent No. 2,648,171 dated August 11, 1953, to which reference may be had for details of disclosure not contained herein. This mechanism may comprise a cylinder 65 (Fig. 6) which contains a slidably mounted piston 66. The piston 66 is provided with rack teeth 67 which meshes with a gear 68 mounted on a shaft 69. The shaft 69 also supports a gear 70 which meshes with the gear 47. When fluid under pressure is passed through a pipe 71 into the left hand end of the cylinder 65, the piston 66 will be moved toward the right to impart a rotary motion to the feed screw 35 so as to cause a forward feeding movement of the wheel slide 25. During this movement of the piston 66 fluid may exhaust from a chamber formed at the right hand end of the cylinder 65 through a pipe 72. The feed control valve 62 serves to simultaneously control the passage of fluid under pressure to both the cylinder 55 and cylinder 65.

The feed control valve 62 is a piston type valve having a slidably mounted valve member 75 formed with a plurality of spaced integral valve pistons to form a plurality of spaced valve chambers 76, 77 and 78. The slidably mounted valve member 75 is also provided with a central passage 79. A pilot valve 80 is provided for controlling the shifting movement of the valve member 75. The pilot valve 80 is normally held in a right hand end position by means of a spring 81. Fluid under pressure passing through a pipe 82, passes through the pilot valve 80, through a passage 83 into an end chamber 84 to shift the slidably mounted valve member 75 toward the left (Fig. 6). During this movement of the valve member 75 fluid within an end chamber 85 may exhaust through the pilot valve 80 and out through an exhaust pipe 86. A solenoid S1 is provided which when energized serves to shift the pilot valve 80 into its left hand end position so that fluid under pressure passing through the pilot valve passes through a passage 87 into the end chamber 85 to shift the slidably mounted valve member 75 toward the right.

A backlash valve 88 is provided to control fluid exhausting from the feed cylinder 65 to allow an initial rapid movement thereof to take up the backlash in the gear train of the feed mechanism.

It is desirable to provide means to facilitate bypassing fluid from one end of the said cylinder 65 to the other to facilitate a manual adjustment of the wheel slide 25. A manually operable rotary valve 90 is provided having a control lever 91. In the position of the valve 90 (Fig. 6) fiuid under pressure from a pressure pipe 92 passes through the valve 90, through the pipe 82 to the pilot valve to control the shifting movement of the feed control valve 62. When it is desired to manually adjust the position of the wheel slide 25 by manual actuation of the feed wheel 45, the control lever 91 is shifted in a counter-clockwise direction into broken line position 91a. In this position of the valve fluid from the pressure pipe 92, passes through the valve 90, through a pipe 93 into a chamber formed at the right hand end of a bypass valve 94. The bypass valve 94 is a piston type valve comprising a slidably mounted valve member 95 which is normally held in its right hand end position by means of a spring 96. In the position of the valve 94 (Fig. 6) fluid under pressure from the feed control valve 62 passes through a ball check valve and through a pipe 101, through the valve 94 and the pipe 72 into the chamber formed at the right hand end of the said cylinder 65. Fluid within the right hand end chamber of the cylinder 65 moves the piston 66 toward the left so that fluid within the left hand end chamber of the cylinder 65 may exhaust through the pipe 71, through the valve 94, through the pipe 97 into the valve chamber 78, through the central passage 79 into the valve chamber 76 and exhaust through a pipe 98. When it is desired to manually feed the wheel by actuation of the feed wheel 45, the control lever 91 is shifted into position 91a so that fluid under pressure is passed through the pipe 93 to cause the valve member 95 to move toward the left so that both the pipe 71 and the pipe 72 are connected with a valve chamber 99. In this position of the valve 94, fluid may readily pass from one end of the cylinder 65 to the other thereby facilitating a manual actuation of the feed wheel 45 for adjusting the wheel slide 25 and the grinding wheel 29.

A fluid pressure system is provided for supplying fluid under pressure to operate the various mechanisms of the machine. This system may comprise a motor driven pump 100 which draws fluid through a pipe 101 from a reservoir 102 and forces fluid under pressure through the pipe 92 to the various mechanisms of the machine. A relief valve 103 is connected to the pipe 92 to facilitate exhausting excess fluid under pressure from the system to maintain the desired operating pressure therein.

A table traversing mechanism is provided for traversing the work table 11 longitudinally to facilitate positioning a work piece to be ground relative to the grinding wheel or wheels. This mechanism is preferably a hydraulically operated mechanism comprising a cylinder 105 which is fixedly mounted to the underside of the table 11. The cylinder 105 contains a slidably mounted piston 106 which is connected to oppositely extending hollow piston rods 107 and 108 respectively. The outer ends of the piston rods 107 and 108 are fixedly connected to brackets 109 and 110 which are fixedly mounted on the machine base 10.

A solenoid operated reversing valve 111 is provided for controlling the admission to and exhaust of fluid from the cylinder 105. The reversing valve 111 as illustrated in Fig. 6 is shown in a central or neutral position. When a solenoid S3 is energized, the valve 111 shifts toward the right so that fluid under pressure in the pipe 92 may pass through the valve 111 and through a pipe 112,

through the hollow piston rod 108 into a cylinder chamber 113 to cause the cylinder 105 and the table 11 to move toward the right. During this movement fluid within a cylinder chamber 114 may exhaust through the hollow piston rod 107, through a pipe 115, through the valve 111 and out through an exhaust pipe 116. Av throttle valve 117 in the exhaust pipe 116 serves to control. the

speed of movement of the table 11 in either direction. Similarly when a solenoid S2 is energized, the valve 111 is moved toward the left so that fluid under pressure from the pipe 92 passes through the valve 111, through the pipe 115, through the hollow piston rod 107 into the cylinder chamber 114 to cause the cylinder 105 and the table 11 to move toward the left. The energization of the solenoids S2 and S3 is automatically controlled in a manner to be hereinafter described.

As shown diagrammatically in Fig. 6, a table dog 118 is arranged to engage the actuating plunger of a limit switch LS4 to hold the contactors in the position illustrated. As the table 11 moves toward the left, a rod 340 which will be more fully described hereinafter is arranged to move into engagement with the actuating plunger of a normally open limit switch LS3.

A hydraulically actuated mechanism is provided for automatically controlling actuation of the footstock 15. This mechanism may comprise a cylinder 120 containing a slidably mounted piston 121. A piston rod 122 is connected to the piston 121. The left hand end of the piston rod 122 is slidably keyed within a sleeve within the footstock spindle and serves when moved toward the left to compress a spring 123 yieldably to move the footstock center 17 into engagement with the work piece to be ground. When fluid under pressure is passed through a pipe 124 into a cylinder chamber 125, the piston 121 together with the footstock center 17 will be moved toward the left, that is, toward an operative position to support one end of the work piece. During this movement fluid within a cylinder chamber 126 may exhaust through a pipe 127.

A solenoid actuated control valve 128 is provided for controlling the admission to and exhaust of fluid from the cylinder 120. The valve 128 is preferably a piston type valve which is normally held in its left hand end position by means of a spring 129.

A solenoid S4 is provided which when energized serves to shift the valve 128 into its right hand end position.

In the position illustrated in Fig. 6, fluid under pressure from the pipe 92 passes through the valve 128, through the pipe 130, through the pipe 127 into the cylinder chamber 126 to cause a pressure against'the left hand side of the piston 121. The piston 121 cannot move because the exhaust of fluid therefrom is blocked by a sequence valve 132 having a slidably mounted valve member 133. Thevalve member 133 is provided with spaced valve pistons forming a valve chamber 134. A check valve 135 is provided integral with the sequence valve 132 and is connected to a passage 136. Fluid under pressure passing through the pipe 130 causes a downward movement of the valve membe'r'133 against the compression of an adjustable spring at the lower end thereof. When the valve member 133 moves downwardly so as to uncover a port at the end of a pipe 131, fluid may then exhaust from the cylinder chamber 125, through the pipe 124 through the valve chamber 134, through the pipe 131, through the valve 128 and out through an exhaust pipe 137. The exhaust pipe 137 contains a throttle valve 138 which regulates the return of exhaust of fluid from the cylinder chamber and thereby regulates the rate of movement of the footstock center 17 toward an inoperative position.

When the solenoid S4 is energized and the valve 128 is shifted to its right hand end position fluid under pressure from the pipe 92 may pass through the pipe 131, through the passage 136 to open the check valve and then pass through the pipe 124 into the cylinder chamber 125 to move the piston 121 toward the left thereby moving the footstock center 17 toward the left into operative supporting engagement with the work piece to be ground. During this movement fluid may exhaust from the cylinder chamber 126, through the pipe 127, through the pipe 130, through the valve 128 and out through the pipe 137 and the throttle valve 138. The throttle valve 138 serves to control the rate of movement of the footstock center 17 toward an operative position. The automatic actuation of thevalve 128 will be described hereinafter.

The footstock spindle is provided with rack teeth 140 which mesh with a gear segment 141 which is supported to rotate on a stud 142. A member 143 fixedly supported to rotate with the gear segment 141 is arranged to move in the path of an actuating roller of a limit switch LS2 which serves in a manner to be hereinafter described to start movement of the table 11 toward the left.

The machine is provided with a pair of spaced work steadying rests and 151 (Fig. 1) which are identical in construction, consequently only one of the steady rests has been shown in detail. The steady rests comprise a steady rest base 152 which supports a pivot stud 153. A steady rest arm 154 is mounted on the pivot stud 153 and is provided with a pair of spaced adjustably mounted work steadying shoes and 156.

A hydraulically operated mechanism is provided for swinging the arm 154 and the steady rest shoes 155 and 156 into operative engagement with a work piece being ground and to maintain it in engagement therewith during the grinding operation. This mechanism may comprise a cylinder 157 which contains a slidably mounted piston 158. The piston 158 is fastened to the lower end of a piston rod 159, the upper end of which is arranged to engage and swing the arm 154. A tension spring 160 serves normally to maintain the arm 154 in operative engagement with the end of the piston rod 159. The steady rest base 152 is preferably adjustably clamped onto a longitudinally movable slide 161 which is supported by a slide rod 162 and a slide bar 163. Both of the steady rest bases are supported on the slide 161 and may be adjusted longitudinally thereon as desired. The parts of the steady rests 150 illustrated in Figs. 1 and 6 have been designated with the same numeral suffixed with the letter a.

it is desirable that the steady rest shoes 155 and 156 remain out of engagement with the work piece during the initial grinding operation and that they be moved automatically into engagement therewith for the final or finishing portion of the grinding. This is preferably accomplished by means of a solenoid-actuated control valve 165. The valve 165 is a piston type valve having a slidably mounted valve member 167 normally held in a left hand end position by a spring 166. A solenoid S7 is provided which when energized serves to shift the valve member 167 toward the right. When the solenoid is energized, fluid from the pressure pipe 92 may pass through the valve 165, through a pipe 168, through a throttle valve 169 to both of the cylinders 157 and 157a to move the steady rest arms 154 and 154a into an operative position with the work steadying shoes in supporting engagement with the work piece being ground. The solenoid S7 is energized by the closing of the normally closed limit switch LS7 when the work piece has been partially ground I automatically to move the steady rest shoes into engagement with the work piece and to maintain the shoes in engagement therewith during the remainder of the grinding operation. When the feed wheel 45 is turned in a clock- Wise direction during the resetting of the feed piston 66, the limit switch LS7 is opened thereby deenergizing the solenoid S7 so that fluid may exhaust from both of the cylinders 157 and 157a thereby withdrawing the steady 7 rest shoes to inoperation positions.

A multiple wheel truing apparatus is provided whereby all of the grinding wheels may be simultaneously trued by means of a manually initiated cycle. This truing mechanism is identical with that shown in my copending application Ser. No. 358,337 filed May 29, 1953, to which reference may be had for details of disclosure not contained herein. This mechanism may comprise a cross slide 186 which is supported on spaced parallel ways 181 v and 182 (Fig. 1) formed on the upper surface of the wheel slide 25. The cross slide is provided with a longitudinal extending dove-tailed slide way 183 for =-guiding a longitudinally traversable slide 184. The

upper surface of the slide 184 is provided with a dovetailed slide way 185 to which a plurality of truing tool units 186, 186a, 186b, 1860 and 186d may be clamped in spaced adjusted positions thereon. Each of the truing tool units are provided with a clamping block 187 to facilitate clamping the units in adjusted positions on the dove-tailed slide way 185.

A suitable feeding mechanism is provided for adjusting the cross slide 180 toward and from the wheel spindle 28. This mechanism may comprise a feed screw 190 which meshes with or engages a rotatable feed nut 191 journalled in anti-friction bearings 192 and 193. A shaft 194 is slidably keyed within the feed screw 190. The left hand end of the shaft 194 is rotatably supported in an anti-friction bearing 195 which serves to hold the shaft 194 against axial movement. The right hand end of the feed screw 190 is journaled in an anti-friction bearing (not shown) within a piston 196. The nut 191 is provided with a spiral gear 197 which meshes with a spiral gear 198. The spiral gear 198 is keyed onto a rotatable shaft 199 the other end of which is provided with a manually operable wheel 200. By rotation of the feed wheel 200, a rotary motion may be imparted through the mechanism just described to rotate the feed nut 191 thereby causing a transverse movement of the cross slide 180.

In order to cause a rapid positioning movement of the cross slide 180, a hydraulically operated mechanism is provided comprising the piston 196 which is slidably mounted within a cylinder 202. The cylinder 202 is fixedly mounted on the wheel slide 25. The right hand end of the feed screw 190 is formed as a piston rod for the piston 196. The feed screw 190 may be moved in an axial direction by the piston 196 to cause a rapid positioning movement of the cross slide 180, or may be rotated in a manner to be hereinafter described to impart a transverse movement to the cross slide 180. When fluid under pressure is passed through a pipe 205 into a cylinder chamber 201, the piston 196 will be moved toward the left (Figs. 2 and 6) to impart a corresponding positioning movement to the cross slide 180 so as to move the truing tool units 186, 18611, 186b, 186:: and 186d into an operative position.

In the preferred construction, a separate independent hydraulic mechanism is provided for moving the cross slide 180 rearwardly to an inoperative position. This mechanism may comprise a cylinder 206 which is fixedly mounted on the cross slide 180. The cylinder 206 contains a slidably mounted piston 207 which is connected to one end of a piston rod 208. The right hand end of the piston rod 208 is fixedly connected to a bracket 209 formed integral with the wheel slide 25. When fluid under pressure is passed through a pipe 210 into a cylinder chamber 211, the piston 207 being anchored, the cylinder 206 moves toward the right (Figs. 2 and 6) to cause a rapid rearward movement of the cross slide 180.

A manually operable rotary-type valve 212 is provided for controlilng the admission to and exhaust of fluid from the cylinders 202 and 206. The valve 212 is provided with a manually operable control lever 213 by means of which the valve rotor 214 may be shifted so as to reverse the flow of fluid when desired. As illustrated in Fig. 6, fluid under pressure from the pressure pipe 92 passes through the pipe 210 into the cylinder chamber 211 to move the cross slide 180 into a rearward or inoperative position and to hold it in this position. When it is desired to effect a truing operation, the lever 213 may be rocked in a counter-clockwise direction into the broken line position 213a (Fig. 6) so that fluid under pressure from the pipe 92 may pass through the pipe 205 into the cylinder chamber 201 to cause a feed positioning movement to the cross slide 180.

A power operated traversing mechanism is provided for traversing the truing tool slide 184 longitudinally in either direction. This mechanism may comprise a feed screw 220 which is rotatably journalled in a bearing 221 fixedly mounted on the cross slide 180. The feed screw 220 meshes with or engages a nut 222 mounted on the left hand end of the slide 184 (Fig. 1). A rotary-type fluid motor 223 is mounted on the cross slide 180. The motor 223 is provided with a rotor shaft having a V-groove pulley 225 which is connected by a V-belt 226 with a V-groove pulley 227 mounted on the left hand end of the feed screw 220. It will be readily apparent from the foregoing disclosure that rotation of the motor shaft will be imparted through the driving mechanism above described to rotate the feed screw 220 and thereby impart a longitudlnal traversing movement to the slide 184. As shown diagrammatically in Fig. 6, the fluid motor 223 is connected directly with the end of the feed screw 220.

A control valve 230 is provided for controlling the admission to and exhaust of fluid from the fluid motor 223 to control the longitudinal movement of the slide 184. The control valve 230 is a fluid actuated valve controlled by a solenoid-actuated pilot valve 231 which is shifted in opposite directions by means of a pair of solenoids S5 and S6. A pipe 232 and a pipe 233 are connected between the control valve 230 and the fluid motor 223. The stroke of the longitudinally movable slide 184 is determined by a pair of spaced lugs 234 and 235 which are either formed integral with or adjustably mounted on the longitudinally movable slide 184. The lugs 234 and 235 are arranged to engage the actuating plunger of a pair of limit switches LS8 and LS9 respectively. A push button start switch 236 is provided for starting the truing cycle and a stop switch 237 is provided to stop the truing cycle at any time if desired.

In order to facilitate truing the grinding wheels a predetermined amount at each pass of the longitudinally movable slide 184, it is desirable to provide an automatic compensator 240 which is arranged automatically to rotate the feed screw 190 by a predetermined increment to advance the truing apparatus cross slide and at the same time to rotate the wheel feed nut 36 relative to the feed screw 35 to compensate for the reduction in diameter of the grinding wheels caused by the truing operation, so that after a truing operation grinding may be resumed without the necessity of resetting the wheel feeding mechanism.

The feed compensator 240 may comprise a fluid motor 241 which is substantially identical with that shown in the prior U. S. Patent No. 2,522,481 to D. W. Martin, dated September 12, 1950, and the compensator as a unit is substantially the same as that shown in the prior U. S. Patent No.'2,522,485 to H. A. Silven and C. G. Flygare dated September 12, 1950, to which reference may be had for details of disclosure not contained herein. A pipe 242 connects with the pipe 232 and a pipe 243 connects with a pipe 233 so that when the control valve 230 is actuated to start the traverse motor 223 of the wheel truing apparatus, fluid is also passed to the compensator motor 241 to impart a compensating adjustment thereto.

The fluid motor 241 is connected by an arm 244 to actuate a pawl and ratchet mechanism to impart an incremental rotary motion to a shaft 246. The shaft 246 is provided with a bevel gear 247 which meshes with a bevel gear 248 mounted on a vertically arranged rotatable shaft 249. The lower end of the shaft 249 is provided with a worm 250 which meshes with a worm gear 251 formed on the periphery of the rotatable feed nut 36. The upper end of the shaft 249 is provided with a worm 252 which meshes with a worm gear 253 mounted on the left hand end of the shaft 194. It will. be readily apparent from the foregoing disclosure that the actuation of the pawl and ratchet mechanism 245 will be imparted through the mechanism just described to impart a compensating adjustment to the feed screw of the truing apparatus and a corresponding compensating adjustment of the rotatable feed nut 36. This compensating adjust ment advances the truing tool cross slide 180 by a desired and predetermined amount for a truing operation and at the same time imparts a compensating adjustment to the wheel slide feeding mechanism so that after a grinding wheel truing operation, grinding may be resumed without the necessity of resetting or adjusting the wheel feed mechanism.

A fluid pressure actuated by-pass valve 255 is provided for controlling the admission to and exhaust of fluid from the compensator motor 241. The by-pass valve 255 is a piston type valve having a plurality of spaced valve chambers 256, 257 and 258. A compression spring 259 serves normally to hold the valve 255 in a left hand end position. In this position of the valve fluid under pressure may pass from the pipe 232, through the valve chamber 257 into the pipe 242. Similarly the fluid within the pipe 233 may pass through the chamber 258 into the pipe 243 so that when the valve 230 is shifted to change the direction of movement of the fluid motor 223, fluid will also be passed through the pipes 242 and 243 to reverse the direction of flow of fluid to the compensator motor 241. The pipe 93 is connected to the left hand end of the by-pass valve 255 so that when the control lever 91 is shifted in a counter-clockwise direction into position 91a to actuate the by-pass valve 94, fluid will also pass through the pipe 93 to actuate the by-pass valve 255. Fluid under pressure passing through the pipe 93 shifts the valve 255 into a right hand end position so that fluid may by-pass from the pipe 232, through the valve chamber 256 into the pipe 233 thereby allowing a by-passage of fluid between opposite sides of the fluid motor 23 and also between opposite sides of the compensator motor 241. This by-pass of fluid between opposite sides of the motors 223 and 241 serves to facilitate manual adjustment of the longitudinal traversing movement of the slide 184 and also of the compensator motor 241.

Each of the truing tool units 186, 186a, 186b, 1860 and 186d is provided with truing tools 260, 260a, 260b, 2600 and 2600! respectively. The truing tools 260 are mounted on a transversely movable member (not shown) which is identical with that shown in my copending application Ser. No. 358,337 filed May 29, 1953, to which reference may be had for details of disclosure not contained herein. A follower 261 is provided on each of the transversely movable truing tools of each of the units 186, 186a, 186b, 1860 and 186d. The followers are arranged to ride upon a forming bar 262 the ends of which are fastened to the transversely movable slide 180. The forming bar serves to control the path of movement of the truing tools. The forming bar may be formed as a plane surface or may be shaped if shaped faces are provided on the grinding wheels.

An independent feed adjusting mechanism 263, 263a, 263b, 2630 and 263d on the truing tool units 186, 186a, 186b, 1860 and 186d respectively to facilitate independently adjusting the position of the truing tools relative to each of the units. A hydraulic mechanism is provided for actuating the said adjusting mechanism 263 in a manner identical with that disclosed in my copending application above referred to. Each of the truing tool units is provided with a cylinder 264, 264a, 264b, 2640 and 264d respectively which contain slidably mounted pistons 265, 265a, 265b, 2650 and 265d. A control valve 266 is operatively connected to control the admission to and exhaust of fluid from the cylinders 265 and 265a. When solenoid S is energized by actuation of a push button switch 269, the valve 266 will be shifted toward the left so as to pass fluid into the cylinder 264 to provide a compensating adjustment to the truing tool 260. Similarly when a solenoid S11 is energized by closing a push button switch 269a, the valve 266 will be shifted toward the right so as to pass fluid to the cylinder 264a to provide a compensating adjustment of the truing tool 260a.

A control valve 267 is provided for controlling the passage of fluid under pressure to the cylinders 26412 and 2640. When a solenoid S12 is energized by closing a push button switch 269b, the valve 267 will be shifted toward the left to pass fluid into the cylinder 264 but to impart a compensating adjustment to the truing tool 26%. Similarly when the solenoid S13 is energized by closing a push button switch 2690, the valve 267 will be shifted toward the right so that fluid under pressure will be passed to the cylinder 2640 to impart a compensating adjustment to the truing tool 2600. v A control valve 268 is provided for controlling the passage of fluid to the cylinder 264d. When a solenoid S14 is energized by closing of a push button switch 269d, the valve 268 will be shifted toward the left so that fluid under pressure will be passed to the cylinder 264d to impart a compensating adjustment to the truing tool 260d. The mechanism just described provides a remote control whereby any of the truing tools may be independently advanced by a predetermined increment to compensate ,for differential in wheel wear. It will be readily apparent from the foregoing disclosure that the actuation of the push button switches 269, 269a, 269b, 2690 and 269d will be imparted, in a manner more fully described in my copending application, to impart compensating adjustments to the truing tools 260, 260a, 260b, 2600 and 260d.

A plurality of dial-type work gages 275, 275a, 275b, 2750 and 275d are provided for independently gaging spaced portions of the work piece during grinding. Each of the dial gages is located opposite the grinding wheel and is arranged to engage the work piece 21 as shown in Fig. 2. These dial gage units are standard commercial units and it is, therefore, not believed necessary to further illustrate or describe them. If the wheel slide is fed toward the work axis to grind a plurality of spaced portions on the work piece 21, the operator observes the readings of the dial indicator 275. If the dial indicators show that one or more wheels require truing to produce predetermined diameters, the grinding operation may be stopped and the wheel truing apparatus moved to an operative position after which one or more of the push button switches 269, 269a, 269b, 2690 or 269d may be actuated to impart a compensating adjutstment to one or more of the truing tools 260. After the compensating adjustment has been made the truing apparatus longitudinally movable slide 184 may be traversed longitudinally to pass the truing tools across the operative faces of the grinding wheels to true the same to the desired and predetermined extent.

A work positioning mechanism is provided to facilitate positioning the work piece being ground axially into a predetermined position relative to the grinding wheels. As illustrated in Fig. 3, the shaft 162 is supported by a plurality of spaced brackets 280, 281 and 282 which are adjustably clamped onto the work table 11. The shaft 162 is supported in brackets 280 and 281 so that it is free to rotate and move axially relative thereto. The bracket 280 is provided with spaced needle bearings 283 and 284 to support the left hand end of the shaft 162. An axial type ball bearing 285 is provided between the needle bearings 283 and 284 to facilitate an axial movement of the shaft 162 relative to the bracket 280.

Similarly the bracket 281 is provided with a pair of spaced needle bearings 286 and 287 between which is located an axial-type ball bearing 288 for supporting the right hand end of the shaft 162 for both a rotary and axial movement.

The slide 161 is provided with a pair of spaced antifriction bearings 289 and 290 which serve to maintain the shaft 162 in a predetermined position relative to the slide 161. The right hand end of the shaft 162 is provided with a tri-lobe portion which is slidably keyed within a correspondingly shaped aperture formed in a gear 292 (Figs. 3 and 5). The gear 292 is rotatably supported by a pair of spaced anti-friction bearings 293 and 294 keyed by the bracket 282.

The shaft 162 forms the actuating shaft for a work loading mechanism comprising a pair of spaced work loader arms 300 and 301. Both of these arms are identical in construction; consequently only one of the arms has been illustrated in detail in Figs. 4 and 5. The Work loader arm 300 comprises an arm 302 which is provided with an integral boss or hub 303 which is adjustably clamped to the shaft 162. The arm 302 is provided with a work supporting surface 304 which supports a work piece 21 when the loader arms are swung into inoperative position, that is, in a clockwise direction (Figs. 4 and 5). In an operative position, the arm 302 is positioned by an adjustable stop screw 305 which moves into engagement with a surface of the work table 11. By adjustment of the stop screw 305, the surface 304 may be adjusted to position the work piece 21 in axial alignment with the work supporting centers 16 and 17. The arm 302 pivotally supports an arm 306 which is connected to the arm 302 by a pivot stud 307. The arm 306 is provided with a work supporting surface 308 (Fig. 4) which supports a work piece 21 when loaded into the machine. A compression spring 309 is interposed between the right hand end of the arm 306 (Fig. 4) and the upwardly extending boss formed integral with the arm 302. The spring 309 tends to rock the arm 306 in a clockwise direction relative to the arm 302 so as to hold the work piece in position on the loader arms 300 and 301 as they are swung from a loading into an operative position. As illustrated in Fig. 4, when the arm 300 is swung into a loading position, a stop surface 310 on the arm 306 engages a surface formed on the upper portion of the table 11 so as to rock the arm 306 in a counter-clockwise direction to separate the work supporting surface 308- 304 to facilitate loading a work piece 21 therein. When the loader arms 300 and 301 are moved in a clockwise direction (Figs. 4 and 5) as the stop surface 310 moves out of engagement with the table 11, the compression of the spring 309 serves to rock the arm 306 so that the work supporting surfaces 308 and 304 approach each other to hold the work piece to be ground on the loader arms during a loading operation.

A fluid pressure operated mechanism is provided which is actuated by and in timed relation with the other mechanisms of the machine to actuate the loader arms 300 and 301. This mechanism may comprise a cylinder 315 (Figs. 5 and 6) which is formed integral with the bracket 282. The cylinder 315 contains a slidably mounted piston 316 having racked teeth 317 formed on the lower surface thereof which mesh with the gear 292. When fluid under pressure is passed through a pipe 318 into a cylinder chamber 319, the piston 316 will be moved toward the right to impart a clockwise rotary motion to the gear 292, to the shaft 162, to the loader arms 300 and 301 to shift a work piece 21 from the loading position illustrated in Fig. 4 into an operative position illustrated in Fig. 5 with the axis of the work aligned with the axis of the work supporting centers 16 and 17. During this movement of the piston 316 fluid Within a cylinder chamber 320 may exhaust through a pipe 321. Similarly when the direction of flow of fluid under pressure is reversed and fluid under pressure is passed through the pipe 321, the piston 316 will be moved toward the left to impart a counterclockwise rotary motion to the work loader mechanism to shift a ground work piece 21 from the position illustrated in Fig. 5 into the position illustrated in Fig. 4.

A solenoid-actuated control valve 325 is provided for controlling the admission to and exhaust of fluid from the cylinder 315. The valve 325 is normally held in its left hand end position by means of a spring 326. A solenoid S9 is provided which when energized serves to shift the valve 325 toward the right so as to reverse the flow of fluid under pressure to the cylinder 315.

The shaft 162 is provided with a collar 330 adjustably mounted on the left hand end thereof. The collar 330 is provided with a stud 331 which is arranged in the path of an actuating roller of a limit switch LS1.

It is desirable to provide a positioning mechanism to position the Work piece together with the table 11 so that the portions of the work piece to be ground are in a predetermined relationship with the grinding wheels.

As illustrated in Figs. 3 and 4, an upwardly extending bracket 335 is mounted on the slide 161. The bracket 335 is provided with a pair of spaced bosses 336 and 337 which are arranged to be engaged by a shouldered locating surface 338 on the work piece 21. The slide 161 is provided with a bracket 339 which supports a rod 340. The rod 340 may be adjusted longitudinally relative to the bracket 339 and clamped in adjusted position relative thereto by means of a pair of nuts 341 and 342.

When the footstock center is moved toward the left into operative engagement with the work piece, continued movement of the footstock center 17 toward the left shifts the work piece 21 axially toward supporting engagement with the headstock center 16. During this movement the surface 338 on the work piece moves into engagement with bosses 336 and 337 after which the bracket 335 together with the slide 161 and the shaft 162 moves toward the left against the compression of a spring 343. When the slide 161 moves toward the left, the rod 340 moves into engagement with an adjustable stop screw 344 carried by a rock arm 345 which is pivotally supported by a stud 346. The screw 344 is arranged to engage the actuating plunger 347 of a dial indicator 348. The rock arm 345 is provided with an adjustable stop screw 349 which is arranged to move in the path of an actuating plunger 350 of a normally open limit switch LS3. The indicator 348 together with the stud 346 and the limit switch LS3 are supported on a bracket 351 which is in turn supported by a bracket 352 fastened to the front of the machine base. The movement of the table 11 toward the left to position the work piece 21 relative to the grinding wheels 29 continues until the limit switch LS3 is closed so as to stop the longitudinal movement of the table 11 in a manner to be hereinafter described with the portions of the work pieces to be ground located opposite to the grinding wheels.

In order to drive the work piece 21, the headstock 14 is provided with a spring pressed driving plunger 355 which is carried by a rotatable face plate 356. When the work piece 21 is moved into supporting engagement with the headstock center, the spring pressed work driving plunger 355 engages a flange surface adjacent to the left hand end of the work piece until the face plate rotates so that the plunger 355 may slide into driving engagement with a notch 357 formed in the peripheral portion of the flange on the work piece 21.

As shown in Fig. 6 a switch 360 is provided for starting the wheel driving motor 30. A switch 361 is provided for starting the motor driven pump 100. A cycle control lever 365 is pivotally supported on the front of the machine base. The lever 365 is arranged when located in a counter-clockwise direction to actuate a cycle start switch 366, or when moved in a clockwise direction to actuate a cycle stop switch 367.

Operation The operation of this improved grinding machine will be readily apparent from the foregoing disclosure. When electric current is turned on, with the table 11 in a right hand end position (as shown in Fig. 6) the relay switch CRIS is energized. The switch 360 is manually closed to start the wheel drive motor 30. The switch 361 is manually closed to start the motor driven fluid pump 100. A work piece 21 is then positioned in the loader arms 300 and 301 as shown in Fig. 4.

The cycle control lever 365 is then rocked in a counter-clockwise direction to close the cycle start switch 366 which serves to close a circuit to energize a relay switch CRll. The energizing of relay switch CRll closes a normally open contactor to energize solenoid S9 to shift the valve 325 toward the right so that fluid under pressure from the pressure pipe 92 passes through the valve 325 through the pipe 318 into the cylinder chamber 319 to move the piston 316 toward the right thereby swinging the loader arms 300-301 in a clockloader arms to an operative position momentarily closes the limit switch LS1. The closing of the limit switch LS1 serves to energize a relay switch CR12.

A normally closed limit switch LS6, being closed sets up a holding circuit to hold the relay switch CH12 energized. The energizing of relay switch CR12 closes a circuit to energize the solenoid S4 to shift the valve 128 toward the right so that fluid under pressure from the pressure pipe 92 may pass through the pipe 131 through the passage 136 in the sequence valve 132. The fluid under pressure in the passage 136 opens the check valve 135 and passes fluid under pressure through the pipe 124 into the cylinder chamber 125 to move the piston 121 toward the left to advance the footstock center 17 toward the left into engagement with the right hand end of the work piece 21. Continued movement of the footstock center 17 toward the left shifts the work piece toward the left so that the left hand end thereof approaches the headstock center 16. During this movement a shouldered face 338 on the work piece 21 engages the bosses 336 and 337 on the bracket 335 and continued movement thereof moves the slide 161 together with the shaft 162 toward the left against the compression of the spring 343. The movement of the footstock center 17 toward the left serves through the arm 143 to actuate the limit switch LS2 which serves to close a circuit to energize a relay switch CHIS. The energizing of the relay CH13 serves to close a circuit through the switch 372 to energize a relay switch CR3b and at the same time to energize the solenoid S2 to shift the valve 111 toward the left so that fluid under pressure from the pressure pipe 92 may pass through the pipe 115, through the piston rod 107 into the cylinder chamber 114 to start the cylinder 113 and the table 11 moving toward the left. Movement of the table toward the left continues until the rod 344) engages the screw 344 to rock the rock arm 345 in a counterclockwise direction thereby swinging the screw 349 away from the actuating plunger 350 of the normally closed limit switch LS3 so as to allow the switch LS3 to close. The closing of the limit switch LS3 closes a circuit to energize a relay switch CR14. When the relay switch CR14 is energized, a normally closed contactor therein breaks a circuit so as to deenergize the relay switch CR3b to deenergize the solenoid S2 thereby allowing the control valve 111 to return to a central position. This movement serves to precisely position the table 11 and the work piece 21 in predetermined relationship with the grinding wheels 29.

The energizing of the relay switch CRM serves to close a normally opened contactor therein to energize the electric timer 370. The energizing f the timer 37d closes a circuit to start the work driving motor 13. The face plate 356 rotates with the drive pin 355 yieldably engaging the end face on the work piece 21 until the drive pin engages a notch 357 formed in the work piece to rotate the work piece for a grinding operation. The energizing of the timer 370 also serves to energize the solenoid S1 to shift the control valve 62 toward the right to pass fluid under pressure into the cylinder chamber 59 to cause a rapid approaching movement of the piston 56 together with the wheel slide 25 and the grinding wheels 29. At the same time fluid is passed through the by-pass valve 94, through the pipe 71 into the fee-cl cylinder 65 to start the feed piston 66 moving toward the right (Fig. 6). The movement of the piston 66 toward the right serves through the gear mechanism previously described to impart a rotary motion to the feed screw 35 so as to advance the wheel slide 25 and the grinding wheels 29 to grind spaced portions on a work piece to a predetermined size. Durin the grinding operation, rotation of the feed wheel 45 serves to move the cam 52 into engagement with a cam face on the pawl 53 to rock the pawl 53 in a counterclockwise direction thereby allowing the normally closed limit switch LS7 to close. The closing of the limit switch LS7 takes place before the grinding operation has been completed to energize the solenoid S7 thereby shifting the control valve 165 toward the right so that fluid under pressure from the pressure pipe 92 may pass through the pipe 168 to the steady rests 159 and 151 to move the work steadying shoes thereof into operative supporting engagement with the Work piece during the finish grinding operation.

When the wheel slide 25 approaches its forward position, it opens a normally closed limit switch LS6 to break the holding circuit so as to deenergize the relay switch CR12. At the same time the limit switch LS6 is opened, the timer 370 times out to break a circuit to deenergize the solenoid S1 to cause a shifting of the control valve 62 so as to move the piston 56 together with the Wheel slide 25 and the grinding wheels 29 to a rearwardor inoperative position. At the same time fluid under pressure is reversed to the cylinder 65 to reset the piston 66 for the next grinding operation. At the same time the timer 370 times out it breaks a circuit to stop the work drive motor 18.

When the wheel slide 25 reaches a rearward or inoperative position it closes a normally open limit switch LS5 which energizes a relay switch CR3a to energize the solenoid S3 to shift the control valve 111 toward the right so that fluid under pressure from the pressure pipe 92 may pass through the pipe 112 into the cylinder chamber 113 to start the cylinder together with the table 11 moving toward the right. When the table 11 approaches the right hand end of its stroke, it actuates the limit switch LS4 to open the normally closed contactors therein so as to deenergize the solenoid S4 thereby allowing the released compression of the spring 129 to return the valve 128 to the position illustrated in Fig. 6. In this position of the valve 128 fluid under pressure from the pipe 92 may pass through the pipe 130 into the cylinder chamber 126 and also into the upper end of the sequence valve 132. The piston 121 cannot start movement toward the right until the sequence valve chamber 134 moves downwardly so that fluid may exhaust from the cylinder chamber through the pipe 124 through the chamber 134 and out through the pipe 131. Movement of the footstock center 17 toward the right into an inoperative position serves to withdraw the arm 143 thereby allowing the normally open limit switch LS2 to open thereby breaking a circuit to deenergize the relay switch C1213.

When the table 11 reaches the right hand end of its stroke, it closes the normally open contactors of the limit switch LS4 to energize the relay switch CRIS. The normally closed contactor of the relay switch CRlS opens to break a circuit thereby deenergizing the solenoid S9 thereby releasing the compression of the spring 326 to return the valve 325 to the position illustrated in Fig. 6. In this position of the valve 325 fluid from the pressure pipe 92 may pass through the valve 325. through the pipe 321 into the cylinder chamber 320 to move the piston 316 toward the left thereby rocking the shaft 162 together with the loader arms 3t)t 31 in a counter-clockwise direction to move the ground shaft 21 from the position illustrated in Fig. 5 into the loading position as illustrated in Fig. 4. The ground shaft 21 may then be removed from the motor arms Nth-391 and a new shaft to be ground inserted there instead. The cycle control lever 365 may then be again actuated to start the next cycle of operation.

In setting up the machine, it may be desirable to actuate the feed mechanism manually. The control lever 91 may be shifted in a counterclockwise direction into position 91a to shift the rotor of the valve 90 so that fluid under pressure is passed through the pipe 93 to shift the by-pas s valve 94 toward the left (Fig. 6) so that fluid may readily by-pass between'the pipes '71 and 72 in order to facilitate a manual rotation of the feed wheel 45 without the necessity of overcoming the fluid within the system.

A truing apparatus has been provided for simultaneously truing all of the grinding wheels 29 when desired. The control lever 213 is shifted in a counter-clockwise direction position 213a so that fluid under pressure is passed through the pipe 205 into the cylinder chamber 201 to move the cross slide 180 together with the entire truing apparatus toward the left (Fig. 6) so that the truing tools 260 are in an operative position relative to the grinding wheels. The truing tools may remain in this position during a grinding cycle if desired. When it is desired to true all of the grinding wheels, the push button switch 236 is closed to energize a relay switch CR2a to energize the solenoid S5 thereby shifting the pilot valve 231 toward the right to pass fluid under pres sure to shift the control valve 230 toward the left so that fluid under pressure is passed through the pipe 233 to start rotation of the motor 223 which in turn serves to impart a rotary motion to the feed screw 220 thereby traversing the longitudinally movable slide 184 to simultaneously pass the truing tools 260 across the peripheries of all the grinding wheels 29. At the same time fluid under pressure passing through the pipe 233 passes through the valve 255 and through the pipe 242 to the compensator motor 241 to impart a compensating adjustment to the shaft 246 thereby imparting a rotary motion to the feed screw 190 to advance the cross slide 180 by a predetermined increment and at the same time to impart a compensating rotary adjustment to the feed nut 36 which advances the wheel slide by an amount equal to the advance of the cross slide 180 so that after a truing operation, the grinding operation may be resumed without the necessity of resetting or readjusting the wheel feed mechanism. The longitudinal movement of the slide 184 is controlled by a pair of lugs 234 and 235 which are arranged to actuate the limit switches LS8 and LS9 respectively. When the truing operation is started, the slide 184 traverses toward the right (Fig. 6) until the lug 235 actuates the limit switch LS9. As the lug 234 moves away from the actuating plunger of the limit switch LS8, the normally closed contacts therein are closed to energize a relay switch CR8. When the slide 184 reaches the right hand end of its stroke it actuates the limit switch LS9 to close the normally open contacts thereof thereby closing a circuit to energize the relay CR9. The energization of the relay switch CR9 closes normally open contactors therein to energize the solenoid S6 thereby reversing the direction of fiow of fluid to the motor 233 to start rotation of the feed screw 220 in the opposite direction to start the traversing movement of the slide 184 toward the left. When the valve 230 is shifted at the right hand end of the stroke of the slide 184, fluid under pressure is passed through the pipe 233 to the motor 223 and at the same time is passed through the pipe 243 to actuate the compensating motor 241 thereby imparting a compensating adjustment to the shaft 246. After one complete reciprocation of the slide 184, that is two passes of the truing tools 26!) across the peripheries of the grinding Wheels 29, the truing apparatus is automatically stopped. If additional truing is desired, the truing start switch 236 may again be actuated to cause the truing apparatus to complete a second cycle of operation.

If during grinding it is found that one or more of the wheels are wearing unevenly, the grinding operation may be stopped and the wheel slide returned to an inoperative position after which any one of the push buttons 269, 269a 269b, 2690 or 269d may be actuated to impart a compensating adjustment to one or more of the truing tools 260 after which the push button switch 236 may be actuated to cause a reciprocation of the truing tools across the peripheries of the wheels. Only the truing tools 260 that have been advanced by closing one or more of the switches 269 will perform any truing operation on the respective wheels.

It 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 em bodiment above set forth, it is to be understood that all matter hereinabove 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 base, a transversely movable rotatable grinding wheel thereon, a longitudinally movable work table on said base, a rotatable work support on said table including a headstock and a footstock each having work supporting centers for supporting opposite ends of a work piece to be ground, means to move said footstock center toward and from the headstock, a pivotally mounted work loader having a pair of spaced work supporting arms, a rock shaft on said table to support said loader, a fluid motor on said table, and a rack and gear mechanism interposed between the motor and rock shaft whereby said motor serves to rock said shaft to swing said loader in one direction to position a work piece to be ground in axial alignment with the work supporting centers before a grinding operation and to swing said loader in the opposite direction to remove a work piece therefrom after a grinding operation has been completed.

2. In a grinding machine, as claimed in claim 1, in combination with the parts and'features therein specified in which movement of the footstock center serves to move the work piece axially into engagement with the headstock center, means including a limit switch actuated by and in timed relation with the movement of the footstock center to start a longitudinal positioning movement of the table, and means including a slidably mounted member on said table which is engaged by said work piece and is operatively connected to stop the longitudinal movement of the table when the work piece is positioned in a predetermined position relative to the grinding wheel.

3. In a grinding machine, as claimed in claim 1, in combination with the parts and features therein specified in which movement of the footstock center serves to move the work piece to be ground into axial engagement with the headstock center, means including a limit switch actuated by and in timed relation with the movement of the footstock center to start a longitudinal positioning movement of the table, means including a slidably mounted member on said table having means coacting with a locating surface on the work piece to be ground during movement of the footstock center, and means including a limit switch actuated by said member to stop the positioning movement of said table when the work piece reaches a predetermined position relative to the grinding wheel.

4. In a grinding machine having a base, a transversely movable wheel slide thereon, a rotatable grinding wheel on said slide, a longitudinally movable table, a rotatable work support thereon including a headstock and a footstock each having a work supporting center, means for moving the footstock center toward and from the headstock to move a work piece axially into engagement with the headstock center and to support the work piece during a grinding operation, means to traverse said table longitudinally, means to feed said wheel slide transversely, a transversely movable work loader on said table, means to move said loader automatically to position a work piece to be ground into axial alignment with the work supporting centers, and a cycle control mechanism including a manually operable lever, means responsive to actuation of said lever to move said loader into an operative position, means responsive to movement of said loader to move said footstock center into operative engagement with the work piece and move it into engagement with the headstock center, means responsive to movement of said footstock center to initiate a longitudinal positioning movement of the table to facilitate positioning a work piece in a predetermined relationship with the grinding wheel, means responsive to said latter movement to stop the longitudinal movement of the table when the work piece is moved to a predetermined position relative to the grinding wheel, means responsive to said longitudinal positioning movement to energize a timer to start the work drive motor and to initiate an infeeding movement of the grinding wheel slide, and means responsive to said timer after a predetermined grinding operation to withdraw said grinding wheel to an inoperative position, to withdraw said footstock center to an inoperative position and thereafter to move said work loader to transfer the ground piece of work to an inoperative position.

5. In a grinding machine having a base, a transversely movable wheel slide thereon, a longitudinally movable table on said base, a rotatable work support thereon, a steady rest on said table having work steadying shoes, means to move said shoes to and from an operative position, a wheel feeding mechanism including a rotatable feed wheel to feed the wheel slide transversely in either direction, means including a stop pawl to limit the rotary motion of the feed wheel and the infeeding movement of said slide, and means including a limit switch actuated by and in timed relation with said feed mechanism to move said steady rest shoes into operative engagement with the work during the finish grinding operation.

6. In a grinding machine having a base, a transversely movable wheel slide thereon, a longitudinally movable work table on said base, a rotatable work support thereon, a steady rest on said table having work steadying shoes, means including a piston and cylinder to move said shoes to and from an operative position, a control valve therefor a wheel feeding mechanism including a rotatable feed wheel to feed said slide transversely in either direction, an adjustable stop abutment on said feed wheel, means including a stop pawl arranged to be engaged by said abutment to limit the infeeding movement of said slide, and means including a limit switch actuated by and in timed relation with movement of said stop pawl to actuate said control valve so as to admit fluid under pressure to move the steady rest shoes into operative engagement with the work during the finish grinding operation.

7. In a grinding machine as claimed in claim 6, in combination with the parts and features therein specified of a cam on said stop abutment which is arranged to rock said stop pawl, and electrically controlled means actuated by said stop pawl to move the steady rest shoes into an operative position during the finish grinding operation.

8. In a grinding machine as claimed in claim 6, in combination with the parts and features therein specified in which the adjustable stop abutment is provided with a cam to rock said pawl before the feed wheel is stopped, a limit switch actuated by movement of said pawl, a solenoid-actuated control valve controlled by said limit switch to admit fluid under pressure to the steady rest cylinder to move the steady rest shoes into operative engagement with the work piece during the finish grinding operation.

9. In a grinding machine, as claimed in claim 1, in combination with the parts and features therein specified in which the rock shaft is arranged parallel to the axis of the work centers, a pair of spaced arms on said rock shaft each having a work supporting surface, a pivotally mounted jaw on each of said arms, yieldable means normally to swing said jaw toward said surface to hold a work piece on said arms during a loading and unloading operation, and a stop surface on said jaws which moves into engagement with said table when the loader is swung to a work loading position to rock said jaws relative to said loader arms so as to facilitate a loading operation.

10. In a grinding machine, as claimed in claim 1, in combination with the parts and features therein specified in which the rock shaft of the work loader is arranged parallel to the axis of the work centers, a pair of spaced arms on said shaft each having a work supporting surface, a pivotally mounted jaw on each of said arms, yieldable means normally to swing said jaws toward said surface to hold a Work piece on said arms during a loading and unloading operation, an adjustable stop on said loader to facilitate positioning the loader and work piece so that the work piece is in axial alignment with the work supporting centers, and a stop surface on each of said jaws which moves into engagement with said table when the loader is suwng to a loading position to rock said jaws relative to said arms so as to facilitate a loading operation.

References Cited in the file of this patent UNITED STATES PATENTS Re.21,582 Klingele Sept. 24, 1940 1,662,546 Steiner Mar. 13, 1928 1,744,587 Steiner Jan. 21, 1930 2,105,841 Ott Jan. 18, 1938 2,229,312 Silven Ian. 21, 1941 2,264,160 Flygare Nov. 25, 1941 2,313,482 Rocks Mar. 9, 1943 2,517,193 Fraser Aug. 1, 1950 2,638,719 Balsiger May 19, 1953

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