US2740236A

US2740236A - Grinding machine

Info

Publication number: US2740236A
Application number: US368060A
Authority: US
Inventors: Carl G Flygare; Richard F Wilder
Original assignee: Norton Co
Current assignee: Saint Gobain Abrasives Inc
Priority date: 1953-07-15
Filing date: 1953-07-15
Publication date: 1956-04-03
Anticipated expiration: 1973-04-03

Description

April 3, 1956 c. G. FLYGARE ET AL GRINDING MACHINE Filed July 15, 1953 4 Sheets-Sheet l Z 26 2b 2&3

INVENTORS CA EL 6 F1. YGAEE Emu/pea F W/LDEE BY WWW A T'TORNE Y C. G. FLYGARE ETAL GRINDING MACHINE April 3, 1956 2,740,236

Filed July 15 1953 4 Sheets-Sheet 3 INVENTORS CARL G. FL YGAEE' lg /c/m ED A W/LDER Mm-wan.

HTTOENEY April 3, 1956 c. G. FLYGARE ET AL 2,740,236

GRINDING MACHINE Filed July 15, 1955 4 Sheets-Sheet 4 Fig. 6 q /6 INVENTORS C'A EL 6. F4 YGAEE 85/ c HA ED F W/LDEI? WA D-sot ATTORNEY United States Patent O GRINDING MACHINE iCarl G..Flygare and Richard F. Wilder, Worcester, Mass.,

'assignors to Norton Company,'Worcester, Mass., a corporation of Massachusetts Application July 15, 1953, Serial No. 368,060

7 Claims. (Cl. 51-92) The invention relates to grinding machines, and more particularly toan automatically operated surface grinding machine.

a machine for grinding the plane faces on opposite side faces of a pair of integral splines or keys which project diametrically from opposite sides of a work piece.

Another object is to provide an automatically actuated index mechanism for indexing the work piece 180 after each reciprocation .of the work supporting table, alternately to present opposite faces of the work piece for a grinding operation. Another object is to provide an automatically controlled cycle to stop the grinding operation after a predetermined grinding has takenplace on opposite faces of a work piece. Another object is to provide an electric counter controlled mechanism for stopping the grinding-operation after apredetermined number of reciprocations of the work piece relative to the grinding wheel, and thereafter automatically to true the operative face of the grinding wheel. Other objects 'will'be in part obvious or in'part pointed out hereinafter.

One form of the invention has been illustrated in the accompanying drawings in which like'referencenumerals indicate like parts:

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

Fig. 2 is a right hand end elevation of the machine, on an enlarged scale, having parts broken away and shown in section to clarify the illustrations;

Fig. 3 is a fragmentary vertical sectional-view, on an enlarged scale, through the work support, work indexing, and grinding wheel truing mechanism;

.Fig. 4 is a fragmentarysectional view, on an enlarged scale, taken approximately onthe line 4-4 ofFig. 3, showing the adjustable mechanism for the truing tool;

Fig. 5 is a left hand end elevation of the parts shown in Fig. 3 showing a portion of the work indexing mechanism; and

Fig. .6 is a combined electrical hydraulic-diagram of the actuating mechanisms of the machine.

Agrinding machine has been illustrated in the drawings which is of the surface grinding machine type having a base which supports a vertically movable wheel slide 11. The wheel slide 11 is supported by a pair ofspaced vertically arranged slideways 12 on the base 10, onlyone of which has been illustrated in the drawings. This wheel slide arrangement is substantially the same as that shown in the prior U. S. Patent No. 2,080,976to Wallace H. Wood dated May 18, 1937, to which reference may be had for details ofdisclosure not containedherein.

The wheel slide 11 serves as a. support. for a horizontally arranged rotatable wheel spindle 13 which is rotatably journalled in bearing (notshown) supported in -a hori- "ice zontally arranged projection 14 formed integral with the wheel slide 11. The wheel spindle 13 supports a wheel mounting 15 on itsleft hand end which is arranged to support a pair of spaced

grinding wheels

16 and 17 for simultaneously grinding spaced portions on a work piece.

A suitable driving mechanism is provided for the wheel spindle 13 comprising an electric motor 18 mounted on a bracket 19 which is adjustably fastened to the lower end of the wheel slide 11 by a plurality of screws 20. The screws 20 pass through elongated slots (not shown) formed in the bracket 19 and are screw threaded into the wheel slide 11 to facilitate adjusting the position of the bracket 19 and the motor 18 to tension the driving belt. The motor 18 is provided with a driven pulley 21 which is connected by means of a belt 22 with a pulley 23 mounted on the right hand end of the wheel spindle 13 (Fig. 2).

A suitable feeding mechanism is provided for imparting a vertical feeding movement to the slide 11 relative to the base 10. This mechanism may comprise a rotatable feed screw 25 carried by the wheel slide 11 which meshes with a nut '26 fastened to a portion of the base 10. The upper end of the feed screw 25 is rotatably journalled in an anti-friction bearing 27 carried by the wheel slide 11. The feed screw 25 is provided with a bevel gear 28 which meshes with a bevel gear 29 mounted on the right hand end of a rotatable shaft 30. The shaft 30 is journalled in a pair of spaced anti-friction bearings 31 and 32. A manually operable feed wheel 33 is mounted on the left hand end of the shaft 30. It will be readily apparent from the foregoing disclosure that a rotary motion of the feed wheel 33 will transmit a vertical feeding adjustment to the wheel slide 11. The direction of rotation of the feed wheel 33 will determine the direction of movement of the Wheel slide 11.

The base 10 is provided with a transversely adjustable carriage which is arranged to slide transversely relative to the base 10 on a pair of spaced flatways 41 and 42 and a centrally located gibbed slideway (not shown) which is identical with that shown in the above mentioned prior patent. A suitable feeding mechanism provided for imparting a transverse movement to the carriage 40 comprises a rotatable feed screw 43 which is journalled in spaced

anti-friction bearings

44 and 45 carried by the carriage 40. The feed screw 43 meshes with or engages a half nut 46 fixedly mounted on the base 10. A hand wheel 47 is mounted on the left hand end of the feed screw 43. A rotary motion of the hand wheel 47 will be transmitted through the screw 43 and the nut 46 to impart a transverse movement to the carriage 40. The direction of rotation of the feed wheel 47 serves to determine the direction of movement of the carriage 40 relative to the base 10.

The carriage 40 serves as a support for a longitudinally movable work table 50 which is slidably supported on a V-way 51 and a flatway 52 (Fig. 2) formed on the upper surface of the carriage 40. The table 50 may be traversed longitudinally in a conventional manner by means of an old and well known manually operable traversing mechanism comprising a rotatable traverse Wheel 55 supported on the outer end of a rotatable shaft 56. The shaft 56 is connected by gearing (not shown) with a rack bar 57 fixedly mounted on the underside of the table 50.

A suitable power operated mechanism may be provided for reciprocating the table 50 longitudinally relative to the carriage'40. This mechanism may comprise a hydraulic cylinder 60 which is preferably fixedly mounted' on the carriage 40. The cylinder 60 contains a slidably mounted (piston 61 having

piston rods

62 and 63 projecting from oppositesides thereof. The outer ends of the

piston rods

62 and 63 are connected to a pair of spaced depending

brackets

64 and 65 depending from the under side of the table 50 and at opposite ends thereof.

A reversing valve 66 is provided for controlling the admission to and exhaust of fluid under pressure from the cylinder 60. The valve 66 is arranged so that it may be actuated either manually or automatically by means of a reversing lever 67. A pair of adjustable table dogs 68 and 69 (Figs. 1 and 6) are provided to facilitate automatic operation of the reversing valve 67. A combined start-stop and table speed control valve 70 which is actuated by a knob 71 is provided for controlling the stopping and starting of the table movement and also for controlling the speed thereof. These valves are substantially the same as those disclosed in the above mentioned prior patent, to which reference may be had for details of disclosure not contained herein.

In order to start reciprocation of the table 50, the knob 71 is pulled outwardly, that is, downwardly in Fig. 6, to open the V-port to start a reciprocating movement of the table 50. The reciprocatory stroke of the table 50 is governed by the position of the table dogs 63 and 69. The right hand table dog 69 is positioned so that the table reverses at a point where the grinding

wheels

16 and 17 are directly over a truing apparatus to be hereinafter described. The left hand table dog is positioned to determine the position of the grinding wheel relative to the work piece being ground at the other end of the table stroke.

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 72 which draws fluid through a pipe 73 from a reservoir 74 and forces fluid under pressure through a pipe 75. Pressure relief valve 76 is connected to the pipe 75 so that excess fluid under pressure may be exhausted directly to the reservoir 74 through a pipe 77 so as to maintain a substantially uniform operating pressure in the pipe line 75.

The table 50 serves as a support for a work supporting apparatus comprising a frame 85 which supports a rotatable hollow spindle 86 in a pair of spaced

anti-friction bearings

87 and 88. The left hand end of the hollow spindle is enclosed by a bushing 89 which is screw threaded into the spindle aperture. The hollow spindle 86 supports a longitudinally movable work spindle 90, the right hand end of which is supported by preloaded ball hearings to facilitate a free axial movement of the work spindle 90. The preloaded ball bearings 91 are supported within an aperture 92 formed within the hollow spindle 86. A compression spring 93 surrounds a reduced portion of the spindle 90 and is interposed be tween a shoulder 94 on the spindle 90 and the right hand end face of the bushing 39. The compression spring 93 serves normally to exert a pressure toward the right to maintain a frusto-conical nose face 95 on the spindle 90 in operative supporting engagement with a hollow end of a work piece 96. A hydraulically operated mechanism is provided for moving the spindle 90 to the left to facilitate loading and unloading work pieces to be ground. This mechanism may comprise a hydraulic cylinder 97 which contains a slidably mounted piston 93. The piston 98 is mounted on the left hand end of the spindle 90. When fluid under pressure is passed through a pipe 99, through a port 100 into a cylinder chamber 101, the piston 93 together with the spindle 90 will be moved toward the left against the compression of the spring 93 to withdraw the frusto-conical nose portion from engagement with a work piece 96.

The work piece 96 is a hollow cylindrical-type work piece having two diametrically opposed splines S and 106 to be ground. As illustrated in Fig. 4, the grinding

wheels

16 and 17 are positioned simultaneously to grind the upper faces 107 and 108 of the splines 105 and 106 respectively when the table 50 is reciprocated longitudinally. After grinding the

surfaces

107 and 108, the table 50 returns to the left hand end of its stroke, in which position, the work piece 96 is indexed through 180 to position the

surfaces

109 and 110 of the splines 105 and 106 respectively in position for grinding by the

grind ing wheels

17 and 16 respectively.

A suitable indexing mechanism is provided for indexing the spindle 86 automatically in timed relationship with the other operations of the machine. A rotarytype fluid motor is mounted on the upper portion of the frame 85. The motor 115 is provided with a motor shaft 116 having a gear 117 keyed thereon. The gear 117 meshes with a gear 118 keyed onto the left hand end of the spindle 86. An index plate 119 is also keyed onto the spindle 86 adjacent to the gear 118. The index plate 119 is provided with diametrically opposite stop surfaces 120 and 121 which are engaged by an index pawl 122 precisely to position the work piece 96 in grinding positions. The index pawl 122 is formed integral with a piston 123 slidably mounted within a cylinder 124. A compression spring 125 serves normally to maintain the pawl 122 in operative engagement with the periphery of the index plate 119. When it is desired to impart an indexing movement to the work piece 96, fluid under pressure is passed through a pipe 126 into a cylinder chamber 127 to withdraw the index pawl 122 from engagement with the index plate 119 against the compression of the spring 125.

A suitable control valve 130 is provided for controlling the admission to and exhaust of fluid from the cylinder chamber 127. This valve 130 is preferably a pistontype valve comprising a valve stem 131, the end of which is maintained in operative engagement with the periphery of a cam 132. The cam 132 is fastened to the side face of the index plate 119. A compression spring 133 serves normally to maintain the end of the valve stem 131 in operative engagement with the cam 132. When fluid under pressure is passed through a pipe 134, it passes through the valve 130, through the pipe 126 into the valve chamber 127 to withdraw the index pawl 122 from operative engagement with the stop surface 120. Fluid under pressure is continuously passed through a pipe 138, through a throttle valve 139, through a ball check valve and through. a pipe 141 to the motor 115 so as to normally exert a pressure tended to rotate the motor shaft together with the index plate 119 and the cam 132 in a clockwise direction (Fig. 6). Fluid under pressure exhausting from the motor 115 exhausts through a pipe 142 and through a relief valve 143 into the reservoir 74. By regulating the throttle valve 139, the speed of the motor 115 may be varied as desired.

A control valve 135 is provided for controlling the admission of fluid to the valve 130. The valve 135 is normally held in a left hand end position by means of a compression spring 136. In the position of the valve 135 (Fig. 6) fluid under pressure from the pressure line 75 passes through a pipe 137 into a valve chamber 144. The valve 135 is provided with a solenoid S5 which when energized serves to shift the movable valve member toward the right against the compression of the spring 136 so that fluid under pressure entering the valve chamber 144 may pass through the pipe 134, through the valve 130, through the pipe 126 into the cylinder chamber 127 to Withdraw the index pawl 122 from engagement with the surface 120 of the index plate 119. The motor 115 having pressure thereon immediately starts a rotary mo tion of the index plate 119 and the cam 132 in a clockwise direction. During the clockwise rotation of the cam 132, the valve stem 131 rides along a flat surface on the cam 132 thereby gradually depressing the valve stem 131 to cut off the passage or" fluid from the pipe 126 so that fluid within the cylinder chamber 127 may exhaust through the pipe 126, through the valve 130 and exhausts through a pipe 145 into the reservoir. The released compression of the spring 125 then moves index pawl 122 into engagement with the periphery of the index plate 119. The rotary indexing movement conso that'the stop surface 121 engages the pawl 12210 stop the rotary indexing mo\ ement of the spindle '86 to locate the work piece 96 in an indexed position for grinding the opposite side face of the splines 105 and 106 respectively. It will be readily apparent from 'the foregoing disclosure that each time the solenoid S5 is energized, an indexing movement will be imparted to the index plate 119 and the work piece. The energizing of the solenoid S5 is automatically timed as will be hereinafter described.

A power operated downfeeding mechanism is provided for the wheel slide 11. The upper end of the feed screw 25 is suspended by a pair of spaced

anti-friction bearings

150 and 151 which are in turn supported by a non-rotatable sleeve 152. The periphery ofthe sleeve 152 is screw threaded and meshes with a surrounding rotatable nut 154. The nut 154 is rotatably journalled in spaced

anti-friction bearings

155 and 156. A 'gear 157 is fixedly mounted on the periphery of the nut 154 and meshes with rack teeth 158 formed on a piston 159. The piston 159 is slidably mounted within a cylinder 160. When fluid under pressure is passed through a pipe 161 into a cylinder chamber 162 formed at the left hand end of the cylinder 160, the piston 159 will be moved toward the right. An adjustable stop screw 163 serves to limit the movement of the piston 159 toward the right thereby limiting the power operated downfeed of the grinding

wheels

16 and 17.

A manually operable control valve 164 actuated by a knob 165 is provided for controlling the admission of fluid under pressure to both the downfeed cylinder 160 and also to the cylinder chamber 101 for retracting the headstock spindle 90. The control valve 164 is provided with a valve chamber 166. In the position of the valve 164 (Fig. 6) fluid from the pressure line 75 passes through the valve chamber 166 and through a pipe 167 to the cylinder chamber 101 to retract the frusto-conical nose portion 95 of the spindle'90 to a loading position, that is, toward the left (Fig. 3). During this movement fluid may pass from the pipe 167 through a ball check valve 171, through a pipe 174 into a cylinder chamber 173 to move the piston 159 toward the left. During this movement fluid within vthe cylinder chamber 162 may exhaust through the pipe 161, through a valve chamber 169 and out through an exhaust pipe 170 into the reservoir 74.

When it is desired to initiate a downfeeding movement of the wheel slide 11, the knob 165 is moved toward the left so that fluid under pressure may pass through the valve chamber 166, through the pipe 161 into the cylinder chamber 162 to cause the piston 159 .to move toward the right thereby imparting a rotary motion, through the rack bar 158, to the gear 157 to rotate the nut 154 and thereby to impart a downfeeding movement to the grinding wheel slide 11. During this movement fluid may exhaust from the cylinder chamber 101, through the pipe 167, through a central passage 168 in the valve 164 into the valve chamber 169 and out through the exhaust pipe 170. The exhausting of fluid from the cylinder chamber 101 serves to release the compression of the spring 93 so that the frusto-conical nose portion 95 of the spindle 90 moveshinto operative driving .engagement with the hollow end of the work piece 96.

It is desirable to impart an. incremental rotation to the nut 154 so as to cause a controlled downfeed of the wheel slide 11 at one or both ends of the reciprocatory stroke of the table 50. This is preferably accomplished by means of a shuttle-type metering valve 175 which controls the exhausting of fluid from the cylinder chamber 173. The shuttle valve 175 contains a slidably mounted valve member 176 having a valve chamber 177 formed therein. During a longitudinal shifting .move ment of the slidably mounted valve member 176, a predetermined metering of fluid from the cylinder cham- "ber 173 "is obtained 'to exhaust -'a metered "amount of fluid through an exhaust pipe 178 into the reservoir 74.

A control valve 179 is provided for controlling actuation of the shuttle valve 175. The control valve 179 is normally held in a left hand end position by a compression spring 180. A solenoid S4 is provided for shifting the control valve 179 into a right hand'endposition, as will be hereinafter explained. A pipe 181 conveys fluid from the pressure line 75 into a valve chamber 182. In the position of the valve 179 (Fig. 6), fluid entering the valve chamber 182 passes through a pipe 183 through both a needle valve 184 and a ball check valve 185, through a pipe 186 into an end chamber 187 in the shuttle valve to cause the slidably mounted valve member 176 to move toward the left into aleft hand end position. As the valve chamber 177 passes across the port at the end of the'pipe .174, a predetermined quantity of fluid is metered from or allowed to exhaust from the cylinder chamber 173. During this shifting movement of the valve member 176 toward the left (Fig. 6) fluid may exhaust from an end chamber 188, through a pipe 189, through a throttle valve 190 into a valve chamber 191, through a central passage 192 within the valve 179 into a'valve chamber 193 and out through an exhaust pipe 194 into the reservoir 174. The rate of movement of the slidably mounted valve member 176 may be regulated by manipulation of the throttle valve 190 so as to control the quantity" of fluid metered through the valve chamber 177.

When the solenoid S4 is energized, the valve 179 is shifted into a right hand end position so that fluid under pressure entering the valve chamber 182 of the valve 179 passes out through the pipe 189, through both the throttle valve 190 and a ball check valve 195 into the end chamber 188 to shift the slidably mounted valve member 176 toward the right. As the chamber 177 passes across the port at the end of the pipe 174 a predetermined quantity of fluid will be again metered from the cylinder chamber 173 so as to provide a further incremental downfeed to the wheel slide 11. 'Duringthe shifting movement of the valve member 176 toward the right fluid within the end chamber 187 may exhaust through the pipe 186, through the throttle valve 184, through the pipe 183 into the valve chamber 193 -and out through the exhaust pipe 194 into the reservoir 74. By regulating the throttle valve 184, the rate of movement of the valve member 176 toward the right may be readily controlled so as to regulate the quantity of fluid metered from the cylinder chamber 173. It will be' readily apparent from the foregoing disclosure that by manipulation of the

throttle valves

184 and 190, a different-increment of feed may be obtained at either stroke of the member 176. The solenoid S4 is'energized in timedrelation with other mechanisms of the machine as will'be hereinafter described.

The work holding frame 85 also supports a footstock 200 which is adjustably clamped thereon by a plurality of "screws 199 (Fig. 1). The footstock 200 supports'a footstock center 201 which is preferably of the'old and well known ball bearing type. The footstock center 201 supports the right'hand endof a work holder 202 which fits within a central aperture within'the workpiece 96. The right hand end of the work holder 202 is provided with a frusto-conical face which engages a correspondingly shaped aperture within the work piece 96. The left hand end of the work holder 202 is providedwith a sleeve 203 which is fastened to the work holder 202by means of a pin. .The sleeve203 fits within a central aperture 204 formed in the nose portion of the spindle 90. The sleeve 203 is provided with atransverselyextending notch 205 which is arranged to .mate with .a fiat-workdriver .206 carried within the aperture 204 of the. spindle .90. To load a work piece into the machine, thehollow work piece 96 is slid .ontothe workholder 202 after which the work holder 202 and the work piece 96 are placed in position on the footstock center 201, which is fastened against longitudinal movement. The spindle 90 is then withdrawn toward the left to move the nose portion 95 toward the left so that the work piece together with the work holder may be swung into axial alignment with the spindle 90 so that when the spindle 90 is released, the released compression of the spring 93 will move the spindle so that the aperture 204 slides over the sleeve 203 and the driver 206 moves into engagement with the notch 205.

A grinding wheel truing apparatus is provided so that the peripheries of the grinding

wheels

16 and 17 may be trued periodically either by a manually initiated cycle or automatically after a predetermined number of grinding operations have been performed. A truing apparatus 210 is adjustably mounted on the right hand end of the work supporting frame 85. The truing apparatus 218 includes a vertically arranged plate 211 which is provided with a pair of clamping

screws

212 and 213 which pass through

clearance holes

214 and 215 respectively. The clearance holes serve to facilitate a vertical adjustment of the plate 211 for setting up the apparatus and repositioning the truing tools when required. The plate 211 is guided in a vertical direction by a plurality of

keys

216, 217, 218 and 219 (Fig. 4). In order to facilitate a vertical adjustment of the plate 211, a slide bar 229 is slidably supported at one end in a bearing 221 carried by the frame 85. At the other end, the bar 220 is provided with a screw-threaded projection 222 which meets with or engages a rotatable nut 223 also carried by the frame 85. The slide bar 220 slides within a clearance groove 224 formed in the frame 85. The bar 220 projects beyond the vertical plane surface of the frame 85 so that a portion of the bar 220 mates with a slot 224a formed in the vertical plane face of the plate 211. It will be readily apparent from the foregoing disclosure that a rotary motion of the nut 223 serves to cause an endwise movement of the bar 22% thereby transmitting a vertical adjustment to the plate 211 so as to raise or lower the truing apparatus 210.

A pivotal adjustment is provided for the truing apparatus 210 comprising a pivot stud 225 which pivotally supports the truing apparatus 216 on the plate 211. A pair of adjusting screws 226 and 227 (Fig. 4) are provided to facilitate an angular adjustment of the truing apparatus 210 to vary the path of the truing tool as desired. After the truing apparatus has been adjusted, the truing apparatus may be locked to the plate 211 by means of a plurality of clamping screws 228 only one of which has been illustrated in Fig. 3.

A diamond truing tool 236 is mounted on a slide bar 231 which is preferably supported by a plurality of rollers (Fig. 3) to facilitate a traversing movement of the diamond or truing tool 230 in a direction parallel to the axis of the grinding

Wheels

16 and 17. The bar 231 is connected by a link 232 with left hand end of a piston rod 233 (Fig. 6). The other end of the piston rod 233 is connected to a piston 234 slidably mounted within a cylinder 235. The piston and cylinder 235 being arranged to impart a reciprocating movement to the slide bar 231 for a'truing operation. A control valve 236 is provided for controlling the admission to and exhaust of fluid from the cylinder 235. The valve 236 is normally held in a left hand end position by means of a compression spring 237. A solenoid S2 is provided which when energized, serves to shift the valve 236 into a right hand end position. In the position shown in Fig. 6 fluid under pressure passing through a pipe 238 enters a valve chamber 239 in the valve 236 and passes through a pipe 240, through a throttle valve 241 and a ball check valve 242 into a cylinder chamber 243 to move the piston 234 toward the left. During this movement fluid within a cylinder chamber 244 may exhaust through a throttle valve 245, through a pipe 246, into a valve chamber 247,

through a central passage 248 into a valve chamber 249 and out through an exhaust pipe 250 into the reservoir 74. The throttle valve 245 serves to control the rate of exhaust of fluid from the cylinder chamber 244 so as to control the rate of movement of the piston 234 and the truing tool 230 as they are moved toward the left. A ball check valve 251 is provided so that when the flow of fluid is reversed in the pipe 246 fluid under pressure may bypass the throttle valve 245.

When the solenoid S2 is energized and the valve 236 is shifted into a right hand end position fluid under pressure from the pipe 238 passes into the valve chamber 239 and through the pipe 246, through both the throttle valve 245 and the ball check valve 251 into the cylinder chamber 244 to cause the piston 234 together with the truing tool 236 to move toward the right. During this movement fluid within the cylinder chamber 243 is exhausted at a rate controlled by the throttle valve 241 into the pipe 240, through the valve chamber 249 and out through the exhaust pipe 250. It will be readily apparent from the foregoing disclosure that by manipulation of the throttle valves 24-1 and 245, the rate of movement of the truing tool may be independently regulated during its travel in either direction.

A limit switch LS4 having a pair of normally open and a pair of normally closed contacts is arranged to be actuated by and in timed relation with reciprocation of the truing tool carrier rod 231.

It is desirable to provide an automatic downfeeding movement of the grinding wheel to compensate for truing and wheel wear. The downfeed previously described serves to cause an axial down movement of the feed screw 25 for controlling the infeeding movement of the grinding wheels into the Work. The present feeding mechanism is arranged to impart a rotary motion to the feed screw automatically to compensate for wheel Wear and truing. This mechanism may comprise a ratchet wheel 26% to rotate with the manually operable feed wheel 33. A pivotally mounted arm 261 (Figs. 2 and 6) carries a pawl 262 which is arranged when moved in one direction to ride idly over the ratchet teeth of the ratchet wheel 26th and when moved in the opposite direction to impart a rotary motion to the ratchet wheel 260.

A power operated mechanism is provided for actuating the pawl 262 comprising a cylinder 263 containing a slidably mounted piston 264 which is connected to one end of a piston rod 265. The piston rod 265 is operatively connected by a stud 266 with the arm 261. A compression spring 268 serves normally to hold the piston 264 in a right hand end position. An adjustable stop screw 26) is provided for limiting the movement of the piston 264 toward the right. A stop screw 270 mounted on the left hand end of the piston rod 265 is arranged to engage and actuate the actuating plunger 271 of the limit switch LS3. When fluid under pressure is passed through a pipe 272 into a cylinder chamber 273, the piston 264 will be moved toward the left to impart a counterclockwise rotary motion to the ratchet wheel 260 so as to impart a rotary motion to the feed screw 25 thereby providing a compensating feed to the grinding

wheels

16 and 17.

A controlling valve 275 is provided for controlling the admission to and exhaust of fluid through the pipe 272. The valve 275 is normally held in a left hand end position by means of a compression spring 276. When fluid under pressure is passed through a pipe 277 into a valve chamber 278 fluid is retained therein. When a solenoid S3 is energized, the valve 275 is shifted toward the right (Fig.6) so that fluid under pressure entering the valve chamber 278 may pass through the pipe 272 into the cylinder chamber 273 to cause a compensating feed. In the position of the parts as illustrated in Fig. 6, fluid may exhaust from the cylinder chamber 273, through the pipe 272 into a valve chamber 279, through a central passage 'valve 285 into a right hand end position. In the position illustrated in Fig. 6 fluid under pressure from the pressure line 75 may pass through a pipe 287 into a valve chamber 288 and pass through a pipe 238 to both the control valve 236 and thecontrol valve 275 which serve to control the operation of the grinding wheel truing mechanism above described. Whenthe solenoid S1 is energized and the valve 285 is shifted to a right hand'end position, fluid under pressure entering the valve chamber 288 passes through a pipe'289 to the table reciprocation reversing valve 66 to control the reciprocatory movement of the longitudinally movabletable 50.

The operation of this improved grinding machine will be readily apparent fromthe foregoing disclosure. After a grinding operation the work table 50 stops in a left hand end position, in which position the grinding

wheels

16 and 17 are trued in a manner above described. The knob 165 is pushed-in,'that is, toward the right into the position illustrated in Fig. 6 so that fluidunder pressure is passed through the pipe 167 into the cylinder chamber 101 of the cylinder 97'to withdraw the work supporting and driving spindle 90 toward the left so that the ground work piece 96 maybe removed from the machine. At

the same time fluid under pressure passing through the pipe 167 passes through the ball check valve 171 into the cylinder chamber 173 to move the piston 159 toward theleft into the position illustrated in Fig. 6 to move the 'feed screw 25 upwardly to a startingposition.

The pump 72 is started and the knob 71 pulled outwardly so as to render the control valve 70 operative. The table 50, however, does not start'moving since fluid under pressure cannot pass through the'valve 285 until thesolenoid S1 is energized. A work piece 96 is mounted on the work holder 202 and then inserted in the machine by placing the right hand end thereof in engagement with the footstock center 201 and swinging the headstock end downwardly so that a flat surface 290'on the work piece 96 rests on the work loading guide 291 and the left hand end of the work piece is supported by a V-shaped guide '292. The V-shaped guide 292 positions the work holder 202 so that when the spindle 90 is released the spindle will move into supportingengagement with the sleeve 203 and the driver 206 carried by the spindle 90 is released the spindle will move into supporting engagement with the sleeve 203 and the driver 206 carried by "the spindle 90 will move into driving engagement with the notch 205 formed in the left hand endof the sleeve 203. vIn this position of the parts, the knob 165 is moved outwardly, that is, toward the left (Fig; 6) 'so that'fiuid under pressure may pass through the valve 164 and through the pipe 161'so that the piston 159 is ready for a downfeeding movement. The piston 59, however, cannot move until the solenoid S4 is energized as will be hereinafter described. When the knob 165 is shifted toward the left fluid under pressure may exhaust from the cylinder chamber 101 thereby releasing the compression of the spring 93 to move'the work spindle 90 toward the right into driving and supporting engagement with the work piece 96 and the work holder 202.

A cycle start switch 293 may then be closed to energize the clutch coil 294 of an electric counter 295. The counter'295 may be any of the well known commercial electric counters, such as for example, the Microflex counter manufactured by the Signal Electric Company of Moline, Illinois. At the same time'the cycle switch 293 is actuated, a' start switch 296 is closed to render the grinding wheel truing mechanism operative so that the truing opera- "tion of the grinding wheels will functionautomatic'ally as controlled by the counter 295. This'cycle start switch 293 is a momentary contact switch which renders the clutch coil 294 operative and at the same time energizes the relay CR1 Which closes the contactors of the relay switch CR1 to energize the solenoid S1 which shifts the control valve 285 toward the right and at the same time sets up a holding circuit to hold the clutch coil 294 energized during the cycle. The energizing of the solenoid S1 serves to pass fluid through the pipe 289 to the table reversing valve 66 to start the table 50 moving toward the right. At the end of the table stroke toward the right, the dog 68 shifts the reversing lever'67 in a clockwise direction into a reverse position thereby shifting the reversing valve 66 and changing the direction of movement of the table 50. The shifting of the reverse lever closes the normally open limit switch LS1 to energize'a relay switch CR4 and thereby energizing the solenoid S4 "shuttle valve member 176toward the right ata rate controlled by the throttle valve 184. During the movement of the valve member 176 toward the right a predetermined quantity of fluid may exhaust through the pipe 174 thereby releasing fluid under pressure within the pipe 161 to cause the piston 159 to move toward the right by an amount governed by the fluid exhausted from the cylinder chambe: 173 to cause a downward movement of the feed screw 25 thereby feeding the grinding

wheels

16 and 17 downwardly as the table 50 starts to move toward the left. The grinding wheels 16and 17

grind surfaces

107 and 108 as the table moves from aright hand to a left hand end position. When the table'ap'proaches the left hand end of its stroke the table dog 69'shifts the reversing lever 67 in a counter-clockwise direction and thereby shifts'the reversing valve to start the table moving from left to right. At the same time counter-clockwise movement 'of the reversing lever 67 actuates the limit switch LS2 to energize the relay switch CR5 thereby energizing the solenoid S5 to shift the valve 135 toward the right so that fluid under pressure is passed through the pipe 134, through the valve 130, through the pipe 126 into the cylinder chamber .127 to withdraw the index pawl 122 from engagement with the stop surface 120. Fluid under pressure is continually supplied through the pipe 141 to the motor so that as soon as the pawl 122 is withdrawn, the index plate 119 together with the work piece 96 is indexed through 180". Shortly after the indexing movement is started, the cam 132'riding on the valve stem 131 shifts the valve'130 so that fluid may exhaust from the cylinder chamber 127 thereby releasing the compression of the spring so that the pawl 122 rides upon the periphery of the index plate 119 during the remainder of the indexing movement. The indexing continues until the stop-surface 121 on the index plate 119 rides into engagement with the pawl 122. At the time the limit switch LS2 is closed, the count coil of the counter 295 is energized. The table traverses from the left to the right to a third reversal. When the reversing lever is shifted in a counterclockwise direction to initiate a left to right movement of the table, the limit switch-LS1 is opened to deenergize relay switch CR4 thereby deenergizing the solenoid S4 to shift the valve 179 into the position illustrated in Fig. 6so that fluid underpressure will pass into the chamber 187 to shift the shuttle valve memher 176 toward the left at a rate controlled by the throttle valve 190 thereby allowing a metered exhaust of fluid from the cylinder chamber 173 to cause a further downfeed of the feed screw 25 before the table starts its movement from left to right. Each time the table 50 is reversed at the left hand end of its reciprocatory stroke, the indexing mechanism operates to index the work piece 96 through so as to alternately'present the faces 107408and 109-110 to the grinding

wheels

16 and 17. "Several passes of the faces 107-408 and 109-110 relative to the grinding

wheels

16 and 17 are made. The number of passes being determined by the setting of the counter 295.

The table 50 continues reciprocation in the manner above described with the grinding wheels being fed downwardly each time the table starts its movement from right to left until the electric counter 2% counts out thereby deenergizing relay switch CR1 and the solenoid S1 to cut off the flow of fluid through the pipe 289 to the table reversing valve 66 to stop the table movement at the left hand end of its stroke in a position for a grinding wheel truing operation, that is, with the truing tool or diamond 230 located in a vertical plane directly below the axis of the grinding

wheels

16 and 17. At the time solenoid S1 is deenergized, solenoids S2 and 33 are energized. The deenergized solenoid S1 stops movement of the table 50. Energizing solenoid S3 passes fluid under pressure into the cylinder chamber 273 to actuate the pawl 262 to cause a compensating feed, that is, rotation of the feed screw 25. Energizing of the solenoid S2 starts a truing cycle causing fluid under pressure to pass through the pipe 246 to traverse the piston 234 together with the diamond 23d toward the right (Fig. 6) so as to pass the diamond 230 across the peripheral surfaces of the grinding

wheels

16 and 17. When the diamond 23% reaches the end of its stroke toward the right (Fig. 6), the normally open contacts of the limit switch LS4 are closed thereby operating a circuit to deenergize the solenoid S2 so that fluid under pressure passes through the pipe 24% into the cylinder chamber 243 to cause the piston 234 to move toward the left thereby starting a right to left traverse of the truing tool 230. Before the truin tool 236 starts the right to left traversing movement, the solenoid S3 is again energized to again pass fluid through the pipe 272 into the cylinder chamber 273 to again actuate the feed pawl 262 to cause a further compensating rotation of the feed screw 25 before the right to left traverse of the truing tool 236.

After the faces 107-108 and res-11a of the work piece 96 have been ground to the desired extent, the grinding

Wheels

16 and 17 are automatically trued and the table 50 is stopped in a left hand end position. The knob 165 of the valve 164 is pushed in so as to pass fluid under pressure through the pipe 167 into the cylinder chamber 101 to move the piston 98 together with the spindle 90 toward the left to withdraw the conical nose portion 95 from engagement with the workpiece $6 to facilitate removal of the ground work piece from the machine. Fluid under pressure passing through the pipe 167 also passes through the ball check valve 171 through the pipe 174 into the cylinder chamber 173 to move the piston 159 toward the left thereby raising the feed screw 25 together with the wheel slide 11 and the grinding

wheels

16 and 17 upwardly to their initial positions for the next grinding cycle.

it will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabovc set forth together with many thoroughly practical advantages are successfully achieved. As many embodiments may be made of the above invention and as many changes might be made in the embodiments above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

We claim:

1.. In a grinding machine having a base, a transversely movable carriage thereon, means to feed said carriage transversely relative to the base, a longitudinally reciprocable table on said carriage, a piston and cylinder on said carriage operatively connected to reciprocate said table, a reversing valve therefor, means including a reversing lever and a pair of adjustable table dogs to actuate said valve, a vertically movable wheel. slide, a horizontally arranged wheel spindle thereon, a pair of spaced grinding wheels on said spindle for grinding spaced plane surfaces on a work piece, means including a manually operable feed screw and nut to feed said slide vertically, an inde- 12 pendent hydraulically actuated nut and screw mechanism operatively connected to impart an axial feeding movement to said feed screw incrementally to feed the grinding wheel toward and from the work at one end of the table stroke, a rotatable work support including an indexable headstock spindle and a footstock to support a work piece to be ground, an electrically controlled means actuated by and in timed relation with the table reciprocation automatically to index said headstock spindle after each reciprocation of the table at the other end of the table stroke so as to alternately grind spaced faces on opposite sides of a work piece.

2. In a grinding machine as claimed in claim 1, in combination with the parts and features therein specified in which the work index mechanism comprises a fluid motor operatively connected to impart a continuous rotary thrust to said headstock spindle, an index plate on said spindle, an index pawl slidably supported on said headstock normally to hold said plate against the thrust of said motor, a spring normally to maintain said pawl in engagement with said index plate, a piston and cylinder operatively connected momentarily to withdraw said pawl to facilitate an indexing movement of said spindle, a valve on said headstock to control the admission to and exhaust of fluid from said cylinder, a cam on said spindle to actuate said valve, and means including a control valve actuated by and in timed relation with the table reciprocation to admit fluid under pressure to said pawl cylinder automatically to index said spindle after each reciprocation of the table.

3. In a grinding machine as claimed in claim 1, in combination with the parts and features therein specified in which the work index mechanism comprises a fluid motor operatively connected to impart a rotary indexing movement to said headstock spindle, means continuously to pass fluid under pressure to said motor, an index plate on said spindle, an index pawl slidably mounted on said headstock normally to hold said index plate stationary against the thrust of said motor, yieldable means normally to maintain said pawl in engagement with the said index plate, a piston and cylinder operatively connected momentarily to withdraw said pawl to facilitate an indexing movement of said spindle, a cam on said headstock spindle, a normally open piston-type valve on said headstock actuated by said cam and operatively connected to con trol the admission to and exhaust of fluid from said pawl cylinder, said valve having a valve stem which rides in engagement with said cam, and means including a control valve actuated by and in timed relation with the table reversing lever to admit fluid under pressure to said pawl cylinder to index the headstock spindle after each complete reciprocation of the table.

4. In a grinding machine as claimed in claim 1, in com bination with the parts and features therein specified of a piston and cylinder to actuate said nut and screw mechanism, a shuttle-type metering valve to control the exhaust of fluid from said cylinder so as to control the downfeed of the grinding wheel, a solenoid-actuated control valve operatively connected to actuate said shuttle valve, and means including a limit switch actuated by said reversing lever to actuate said control valve so as to cause a downfeed of the grinding wheel at table reversal.

5. In a grinding machine as claimed in claim 1, in combination with the parts and features therein specified of a grinding wheel truing apparatus on said table including a reciprocable truing tool, a piston and cylinder operatively connected to reciprocate said tool, a control valve operatively connected to control the admission to and exhaust of fluid from opposite ends of said cylinder, a pawl and ratchet mechanism to impart a rotary motion to said feed screw, a piston and cylinder operatively connected to actuate said pawl, a second control valve operatively connected to control the admission to and exhaust of fluid from said pawl cylinder, a third control valve operatively connected to said table reversing valve and to said first and second control valve, said third valve in one position serves to convey fluid under pressure to the table reversing valve and in another position to convey fluid under pressure to the first and second control valves to control the grinding wheel truing operation, and means including a limit switch actuated by and in timed relation with the table reciprocation after a predetermined grinding operation to actuate said third control valve so as to initiate a grinding Wheel truing cycle.

6. In a grinding machine as claimed in claim 1, in combination with the parts and features therein specified of a control valve to convey fluid under pressure to the table reversing valve, an electric counter operatively connected to actuate said valve, and means including a switch actuated by and in timed relation with the movement of said table to impart an impulse to said counter after each reciprocation of the table, said counter serving at countout to actuate said control valve to stop the table in a loading position after a predetermined number of complete reciprocations.

7. In a grinding machine as claimed in claim 1, in combination with the parts and features therein specified of a control valve to convey fluid under pressure to the table reversing valve, an electric counter operatively connected to actuate said valve, means including a switch actuated by the table reversing lever to impart an impulse to said counter after each reciprocation of the table, said counter serving at count-out to actuate said control valve to stop reciprocation of the table in a truing position after a predetermined number of complete reciprocations, and automatically actuated truing apparatus including a hydraulically reciprocated truing tool, a control valve therefor, a hydraulically actuated pawl and ratchet mechanism to rotate said feed screw to impart a compensating feed to said grinding wheel relative to the truing tool before each traversing movement thereof, an independent control valve for controlling the truing traverse and for actuating the picker feed, said counter serving at the count-out to actuate said latter control valve to initiate a grinding wheel truing cycle.

References Cited in the file of this patent UNITED STATES PATENTS 1,850,799 Junge Mar. 22, 1932 1,925,740 Ward Sept. 5, 1933 1,973,329 Bullows Sept. 11, 1934 2,004,426 Booth et al. June 11, 1935 2,080,976 Wood May 18, 1937 2,099,674 Bullock et al. Nov. 23, 1937 2,156,970 Burns May 2, 1939 2,183,490 Flygare Dec. 12, 1939 2,192,308 Greiner et al. Mar. 5, 1940 2,206,492 Westenberger et al. July 2, 1940 2,292,588 Terbrueggen Aug. 11, 1942 2,442,635 Bennett June 1, 1948 2,454,591 Brady et al. Nov. 23, 1948 2,535,183 Wilson Dec. 26, 1950 2,600,960 Benjamin et al. June 17, 1952 2,639,563 Swainey May 26, 1953