US3019563A

US3019563A - Grinding machine

Info

Publication number: US3019563A
Application number: US805337A
Authority: US
Inventors: Dana W Martin
Original assignee: Norton Co
Current assignee: Saint Gobain Abrasives Inc
Priority date: 1959-04-09
Filing date: 1959-04-09
Publication date: 1962-02-06
Anticipated expiration: 1979-02-06

Description

Feb. 6, 1962 D. w. MARTIN GRINDING MACHINE Filed April 9, 1959 l ZZ 5 Sheets-Sheet 1 INVENTOR DAMA W. MART/N ATTORNEY Feb. 6, 1962 D. w. MARTIN 3,019,563

GRINDING MACHINE Filed April 9, 1959 3 Sheets-Sheet 2 Oh? u) INVENTOR \9 DA/VA W/VAETN Feb. 6, 1962 D. W. MARTIN 3,019,563

GRINDING MACHINE Filed April 9, 1959 5 Sheets-Sheet 3 ZOO /qo/ INVENTOR DANA M/.MART/N Wwem ATTORNEY Unite tates te 3,019,553 GRINDING MACHINE Dana W. Martin, Northbero, Mass., assigner to Norton Company, Worcester, Mass., a corporation of Massai chusetts Filed Apr., 9, 1959, Ser. No. 805,337 14 Claims. (Cl. SI-Stl) The invention relates to grinding machines and more particularly to a grinding wheel feeding mechanism.

One object of the invention is 4to provide a simple and thoroughly practical grinding wheel feeding and positioning mechanism. Another object is to provide a means to feed the grinding Wheel transversely to size a work piece after which the grinding wheel is fed axially to finish grind the work piece. Another object is to provide a grinding wheel spindle reciprocating mechanism to reciprocate the grinding wheel axially during both the transverse and axial feeding movements.

Another object is to provide a manually controlled grinding wheel truing apparatus for truing the peripheral face of the grinding wheel. Another object is to provide an automatically operated means to stop the wheel spindle reciprocation during a wheel truing operation. Other objects will be in part obvious or in part pointed out hereinafter.

In the accompanying drawings in which is shown one of various possible embodiments of the mechanical features of the invention:

FIG. l is a fragmentary view partly in section of a grinding machine embodying the invention;

FIG. 1A is a fragmentary View of the grinding wheel of the instant invention disposed in operative relation to a different type of workpiece;

' FIG. 2 is a fragmentary sectional View, taken approximately on the line 2 2 of FIG. 1;

l FIG. 3 is a cross-sectional view through the grinding machine, showing the grinding wheel feeding mechanisrn; and

FIG. `4 is a combined hydraulic and electric diagram of the actuating mechanisms and the controls therefor.

A cylindrical grinding machine has been illustrated in the drawings comprising a base 19 which supports a longitudinally movable work table 11 on a flat way 12 and a V-way 13 `formed on the upper surface of the base 10. The table 11 is provided with a rotatable work support comprising a motor driven head stock 14, and afoot4 stock (not shown) for rotatably supporting a work piece 15 to be ground. As shown in FIG. l, the head stock 14 is provided with a work supporting center 16 and the foot stock is provided with a center 17 for supporting the opposite ends of the cylindrical work piece 15.

The base 10 also serves as a support for a transversely movable wheel slide 20 which is arranged to slide transversely relative to the base on a V-way 21 and a flat way (not shown) formed on the upper surface of the base 10. The Wheel slide 20 is provided with a wheel spindle 22 having a grinding wheel 23 mounted on one end thereof. The grinding Wheel 23 is preferably driven by an electric motor 24 mounted on the upper surface of the wheel slide 20. The motor 24 is provided with a motor shaft 2S having a multiple 'rl-groove pulley 26 which is connected by multiple V-belts 27 with a multiple V-groove pulley 28 mounted on the other end of the wheel spindle 22. The wheel spindle 22 is journaled in suitable bearings 3] and 3l. so that it may be rotated and also moved axially relative thereto during a grinding operation, in a manner to be hereinafter described.

A wheel feeding mechanism is provided comprising a rotatable feed screw 35 which is rotatably supported 2 at its right hand end by anti-friction bearings 3-5 carried by a slidably mounted sleeve 37. The sleeve 37 is arranged to slide within a cylindrical aperture 38 formed within the base 1G. The left hand end of the feed screw is formed with a reduced cylindrical portion 39 which is slidably connected within a rotatable sleeve 40 which is journaled in anti-friction bearings 41 mounted within the base 1li.

A manually operable feed wheel 42 is provided 'for imparting a rotary motion to the feed screw 35. The feed wheel 42 is provided with an old and well known micrometer feed adjusting mechanism 43. The feed wheel 42 is rotatably supported on a shaft 44 which carries a gear 45 meshing with a gear 46. The gear 6 is mounted on the left hand end of a rotatable shaft 47. The shaft 47 is journaled in anti-friction bearings 48. The right hand end of the Shaft 47 is slidably connected Within the rotatable sleeve 4d.

A hydraulically operated mechanism is provided for actuating the feed screw 35 comprising a cylinder S0 which contains a slidably mounted piston 51. The upper face of the piston 51 is provided with rack teeth 52 which mesh with a gear 53 mounted on a shaft S4. The shaft 54 is also provided with a gear d5 which meshes with the gear 46. It will be readily apparent from the foregoing disclosure that when the piston 51 is moved longitudinally within the cylinder 50, a rotary motion will be imparted to the feed screw 35.

The Wheel slide 20 is provided with a depending bracket S6 which carries a feed nut 57 meshing with the feed screw 35. It will be readily apparent that rotary motion of the feed screw 35 either by manual actuation of the feed wheel t2 or by longitudinal movement of the piston 51 will be imparted to produce a transverse feeding movement of the wheel slide 20 and the grinding wheel 23.

A clutch mechanism is provided to facilitate disconnesting the piston 51 during manual actuation of the feed mechanism. As illustrated in FG.. 3, the gear 5'3y is mounted in a pair of spaced anti-friction bearings 6G and 6].. The shaft 54 supporting the gear 55 passes through a central aperture formed `within the gear S3. An external gear 62 is mounted in fixed relation with the gear 53 and is arranged to mesh with an internal gear 63 which is iixedly mounted on the shaft 54. When it is desired to declutch the piston 51, the sha-ft 54 may be moved `toward the right (FIG. 3) to throw the internal gear 63 out of mesh with the external gear 62. When the clutch parts are in this position, the feed wheel 42 may be rotated manually without the necemity of overcoming fluid within the hydraulic cylinder 50.

As shown `best in FIG. 4, the feed wheel 4Z is provided with a stop abutment 70 which is adjustable by means of the micrometer adjusting mechanism 43. The stop abutment 7) is arranged in the path of a stop surface 71 formed on the upper end of a stop pawl 72 which is pivotally mounted on a stud on the front of a machine hase 10. A cam 73 carried by the stop abutment 7i? is arranged to engage -a cam face 74 formed on the pawl arm 72 and serves to rock Ithe pawl arm. 72` after the feed wheel has been rotated in a counter clockwise direction Ithrough a predetermined extent before the stop abutment 7? engages the stop surface 71 positively to limit the infeeding movement of the grinding wheel slide 29 and the grinding wheel 23.

Referring again to FIG. 3, a hydraulically operated mechanism is provided for rapidly moving the wheel slide Ztl and the grinding wheel 23 to and from an operative position before and after grinding. This mechanism comprises Aa cylinder 78 which is arranged in axial alignment with the feed screw 35 and the sleeve 37. The cylinder 78 contains a slidably mounted piston 76 which is connected to the right hand end of a piston rod 77. The left hand end of the piston rod 77 is xedly connected to the sleeve 37. It will be readily apparent from the foregoing disclosure that when the piston 76 is moved in either direction within the cylinder 78, a corresponding axial movement will be imparted to the feed screw 35 to move the wheel slide 2t? and the grinding wheel 23 rapidly either toward or from an operative position.

Turning to FIG. 4, a control valve 39 is provided for controlling the admission to and exhaust of fluid from the cylinder 78. The valve S is preferably piston type valve comprising a valve stem 31 having a plurality of spaced valve pistons formed integrally Itherewith to form a pair of spaced valve chambers d2 and 85. A comp-ression spring 84 serves normally to hold the valve stem 81 in a right hand end position. A solenoid S1 is provided for shifting `the valve stem he into a left hand end position. Fluid under pressure passing through a pressure pipe 85 enters the valve chamber 82 and passes through a passage 86, through a port S7 into fa cylinder chamber 88 to move the piston 76 toward the right. At the same time fluid passing through the passage 86 passes through a pipe 89, through both a throttle valve 99 and a ball check valve 91, through a pipe 92 and a port 93 into the cylinder chamber 33. During movement of the piston 76 toward the right, fluid within a cylinder chamber 94 exhausts through ya pipe 95 into the valve chamber 83 and through a pipe 9d into a fluid reservoir 97.

A fluid pressure system is provided for supplying fluid under pressure to the actuating mechanism of the machine `comprising a motor driven iiuid pump 98 which draws uid through a pipe 99 and forces fluid under presstue through the pipe 35. A relief valve 101) is provided in the pipe S to facilitate exhausting excess fluid under pressure directly through a pipe 1111 into the reservoir 97 to facilitate maintaining a substantially uniform pressure within the uid system.

During the rearward rapid movement of the piston 7d, that is, toward the right, `a dash pot piston 162 is provided for cushioning the rapid movement of the piston 76 as it appro-aches the right hand end of its stroke. Movement of the dash pot piston 102 toward the right exhausts fluid under pressure from a dash pot chamber 103 through a throttle valve 164 into the pipe or passage 95. By regulating the throttle valve '164, the rate of cushioning may be varied as desired.

When it is desired to initiate a forward approaching movement of the wheel slide 211 and the grinding wheel 23, the solenoid S1 is energized to shift the valve stem 81 ltoward the left so that fluid under pressure in the pipe 85 passes into the valve chamber d3, through the pipe or passage 95 into the cylinder chamber 94 to move the piston 7 6 rapidly toward the left. During this movement duid under pressure passing through the pipe 95 passes into the dash pot chamber 103 to move the dash pot piston 102 toward the left into a reset position. The rapid approaching movement of the piston 76 continues until the piston 76 closes the port 87 after which fluid within the .cylinder chamber SS must exhaust through the port 93, through the pipe 92, through the throttle valve 90, through the passage 86 into the valve `chamber 82 and through the exhaust pipe 95 into the reservoir 97. By manipulation of the throttle valve 9G the rate of cushioningror slowing down of the piston 76 may be regulated as desired.

A shuttle type valve 11i) is provided lbetween the feed control valve 8i) and the cylinder 5G. This valve comprises a slidably mounted valve member 111 having a plurality of spaced valve pistons to form spaced

valve chambers

112, 113, 114, and 115. A pipe 116- is connected between the valve Sti and the left hand end of the valve 110. A pipe 117 is connected between the valve 80 and the right hand end of the valve 116. A pipe 118 is connected between the valve 11d and a bypass valve 119. Similar-ly a pipe 12) is connected between the valve 110 `and the bypass valve 119'.

The bypass valve 119 is a piston type valve having a slidably mounted valve member 121 having a' plurality of spaced valve pistons to form a plurality of

chambers

122 and 123. A compression spring 124 serves normally to hold the valve member 121 in a left hand end position. `In this position of the valve 119 iluid passing through the pipe 12d enters the valve chamber 123 and passes through a passage 125 into a cylinder chamber 126 to move the piston 51 toward the left at the termination of a grinding cycle. During this movement fluid within a cylinder chamber 127 passes through a passage 128 into the valve chamber 122, through the pipe 118 into the valve chamber 113 and through the pipe 96 into the reservoir 97.

When the solenoid S1 is energized to initiate a grinding cycle, fluid under pressure is passed through the pipe 11d to shift the valve member 111 toward the right so that iuid passes through the pipe 11S into the valve chamber 122, through the passage 123 into the cylinder chamber 127 to start movement of the piston 51 toward the right thereby imparting a rotary motion to the feed screw 35 to feed the grinding wheel 23 into the work piece 15.

lf it is desired to actuate the feeding mechanism manually, a valve 131i` in the pipe 85 may be opened to pass pressure into the left hand end of the valve 119 to move the valve member 121 toward the right thereby blocking the ports at the ends of the pipes 113 and 120 and opening the passages and 12S to the valve chamber 122 so that when the feed wheel 42 is rotated manually luid may readily bypass between the cylinder chamber 126 and the cylinder chamber 127.

A control valve is provided to facilitate controlling the rate or" movement of the piston 51 so that during the initial grinding operation the grinding wheel 23 may be fed at a normal grinding rate, and reduced to an ultra-fine rate before the final size has been reached. The valve 14h is a piston type valve comprising a slidably mounted valve member 141 having a plurality of pistons formed integrally therewith to form

valve chambers

142, 143, 144, 145, and 146. The valve member 141 is provided with a central passage 147 which interconnects the valve chamber 142 with the valve chamber 143. A compression spring 148 serves normally t0 hold the valve member 141 in a left hand end position.

The feed pawl 72 is provided with a downwardly extending arm 151) which supports an adjustable stop screw 151. The screw 151 is arranged in alignment with the valve member 141. When the feed wheel 42 is rotated in a counter clockwise direction, either manually or by movement of the piston 51, the grinding wheel advances at a normal grinding rate until the cam 73 engages the cam face '74 to rock the pawl 72 and the arm 150 in a counter clockwise direction to shift the valve member 141 thereby reducing the normal grinding feed to an ultra-fine feed, as will be hereinafter described. Fluid exhausting from the cylinder chamber 126 during the normal grinding feed exhausts into the valve chamber 114, passes through a pipe 152, through a needle valve 154 which may be adjusted to control the rate of infeed during normal grinding. Fluid passing through the valve 154 passes into the valve chamber 143, through the centrai passage 147, into the valve chamber 142, through a pipe 153 and a pipe 96 into the reservoir 97. Fluid may also pass from the valve 154 through the ultra-tine feed throttle valve 155 directly into the pipe 153 during the normal grinding feed.

As the work piece approaches final size, the cam 73 rocks the feed pawl 72 together with the depending arm in a counter clockwise direction so that the stop screw 151 shifts the valve member 141 toward the right so that a valve piston 156 blocks the port at the end of the pipe 152 so that thereafter all uid exhausting from the cylinder chamber 126 must pass through the ultrane feed control throttle valve 155 into the pipe 153 and through the pipe 96 into the reservoir 97.

1n some grinding operations it is desirable to grind the surface to be finished by a transverse feeding movement of the grinding wheel after which the wheel is traversed in an axial direction to iinish grind the surface. As shown in FIG. l, the Urinding wheel 23 may be a standard grinding wheel or may have one side portion 23A which is of a coarser different structure than the side 23B. The initial grinding is accomplished by feeding the portion 23A transversely, that is, in a direction normal to the axis of the wheel spindle 22. After the wheel has been fed in this direction to a predetermined extent, the wheel spindle 22 may be traversed axially to traverse the finish grinding portion 23B into operative contact with the surface being ground.

In order to accomplish this result, a wheel spindle reciprocating and traversing mechanism may be provided comprising a worm 175 mounted on the wheel spindle 22, as shown in FIGS. l and 2. The worm 170 meshes with a worm gear 171 which is carried by a shaft 172. The shaft 172 is provided with an eccentric stud 173 which rotates within an aperture formed in an eccentric bushing or collar 174. An actuating arm 175 is provided with an enlarged end having a hole 176 which mates with the eccentric collar 174. The other end of the arm 175 is provided with a U-shaped slot 177 within which a stud 178 slides. The stud 178 is xedly mounted on the upper end of a pivotally mounted arm 179 which is pivotally supported by a stud 180 carried by the wheel slide 21B.

The arm 179 is preferably yoke-shaped having a pair of diametrically opposed studs 181 which support a thrust ring 132 which rides within a groove 183. A tension spring 184 is connected between a stud 185 mounted on` the arm 179 and a stud 186 mounted within the wheel slide 24'?. It will be readily apparent from the foregoing disclosure that the tension of the spring 184 serves normally to urge the arm 179 in a clockwise irection to maintain the stud 178 in engagement with the right hand end of the U-shaped slot 177. In this position of the parts, rotary motion of the wheel spindle 22 will be imparted through the worm 170, the worm gear 171 to rotate the shaft 172 thereby revolving the eccentric stud 173 to impart an axial reciprocatory movement to the wheel spindle 22.

It is desirable to arrange the spindle actuating mechanism so that the spindle 22 and the grinding wheel 23 may be reciprocated during the transverse movement of the wheel slide while reducing the diameter of the work piece to the required extent and also to continue the reciprocation during movement of the wheel spindle axially toward the left (FIG. l) While nish grinding the surface of the work piece. This is preferably accomplished by mounting the shaft 172 on a pivotally mounted arm 19t) which is pivoted at -its lower end on a stud 191. The tension of the spring 184 normally maintains the arm 190 against a plunger 192 during the initial grinding operation. The spring maintains the plunger or piston 192 against the right hand end of a cylinder 193. When it is desired to feed the wheel spindle 22 toward the left, fluid under pressure is passed through a pipe 194 through a throttle valve 195, through a pipe 196 into a cylinder chamber formed at the right hand end of the cylinder 193 to move the piston 192 toward the left thereby swinging the arm 19t? together with the arm 179 in a counter clockwise direction to traverse the grinding Wheel 23 across the face of the work piece so that the iinish grinding section of the wheel performs a finish `grinding operation on the Work piece 15. During this time the stud 173 is maintained in engagement with the right hand end of the slot 177 so that during the traversing movement the wheel spindle 22 is also reciprocated. The continuous reciprocation of the wheel during the entire grinding operation is a common well known feature used in plunge cut grinding operations.

A ball check valve 197 is provided to bypass the throttle valve 195 when fluid is exhausted from the cylinder 193 through the pipe 196.

During a grinding wheel truing operation, it is desirable to stop reciprocation of the grinding wheel. This is preferably accomplished by a cylinder 200 which contains a slidably mounted piston 201. When fluid under pressure is passed through a pipe 202 into a cylinder chamber 203, the piston 201 engaging a stud 204 on the arm 179 rocks the arm 179 a further distance in a counter clockwise direction so that the stud 178 is moved toward the left out of engagement with the end of the slot 177. A stop screw 295 carried by the arm 179 moves into engagement with a stop surface 206 formed within the wheel slide 2i). In this position of the parts, the stud 178 moves into position 178B. A truing operation may then be accomplished While the Wheel spindle 22 and the grinding wheel 23 are held against axial motion.

A grinding wheel truing apparatus has been diagramatically illustrated in FIG. 4 comprising a longitudinally reciprocable truing tool 210 mounted on the right hand end of a piston rod 211. The piston rod 211 is connected to a piston 212 which is slidably mounted within a cylinder 213. A control valve 214 is provided for controlling the admission to and exhaust of fluid from the opposite ends of the cylinder 213. The valve 214 comprises a slidably mounted valve member 215 having a plurality of Valve pistons formed integrally therewith to form a plurality of spaced

valve chambers

216, 217, and 218. The valve member 215 is provided with a central aperture or passage 219 which interconnects the valve chamber 216 with the valve chamber 21S. A compression spring 220 serves normally to maintain the valve member 215 in a `left hand end position. A solenoid S2 is provided which when energized serves to shift the valve member 215 into a right hand end position. A push button starter switch PBS is manually closed to energize a relay switch CRZ to close two pair of contacts 221 and 222. The closing of contacts 221 setup a holding circuit to maintain the relay switch CR2 energized after the push button switch P133 is released. The closing of contacts 222 energizes the solenoid S2 to shift the valve member 215 toward the right so that :fluid under pressure passing through the pipe enters the valve chamber 217 and passes through a pipe 223 into a cylinder chamber 224 to move the piston 212 toward the right thereby traversing the diamond'or truing tool 210 across the periphery of the grinding wheel. At the same time fluid under pressure passing through the pipe 223 also passes through the pipe 202 to rock the arm 179 in a counterclockwise direction to stop wheel spindle reciprocation.

During movement of the truing tool 210 toward the right, fluid within the cylinder chamber 22-6 exhausts through the pipe 225 into the valve chamber 216, through a pipe 230, through a throttle valve 231 and through a pipe 232 into the reservoir 97. By manipulation of the valve 231, the rate of movement of the truing tool 210 may be varied as desired.

The truing tool 210 continues moving toward the right until it engages and opens a normally closed limit switch LS1 which breaks a holding circuit thereby deenergizing the solenoid S2 to allow the released compression of the spring 220 to move the valve member 215 toward the left. In this position of the valve, fluid under pressure entering the valve chamber 217 passes through a pipe 225 into a cylinder chamber 226 to move the piston 212 together with the truing tool 210 toward the left to pass the truing tool again across the operative peripheral face of the grinding wheel.

When the piston 212 engages the left hand end of the cylinder 213, the truing cycle stops. During the left hand movement of the piston 212 fluid within the cylinder chamber 213 exhausts through the pipe 223 into r1 4 the valve chamber 218, through the central passage 219 into the valve chamber 216 and through the pipe 230, the throttle valve 231 and the pipe 232 into the reservoir 97. With this setting of the parts, the truing tool 21) makes one complete reciprocation across the face of the wheel and then stops.

A solenoid valve S3 is provided in the pipe 202 to prevent exhaust of fluid from the cylinder chamber 263 during movement of the truing tool toward the left. A relay switch CRS is energized by actuation of the limit switch LS1 at the righthand end of the truing tool stroke to make a circuit to energize the solenoid valve S3 thereby cutting olf exhaust of iluid to hold the spindle 22 against reciprocation during a truing operation. A holding `circuit is set up through the normally closed contacts of limit switch LS2 to maintain relay switch CRS energized during the traverse of the truing tool toward the left. At the left hand end of the truing tool stroke, the limit switch LS2 is actuated to break the holding circuit thereby deenergizing relay switch CR3 and the solenoid valve S3 to allow fluid to exhaust from cylinder chamber 203 thereby permitting reciprocation of the wheel spindle 22.

If it is desired'to cause a continuous truing operation, a switch SW3 is closed so that when the piston 212 approaches the left hand end of its stroke, a normally open limit switch is closed thereby again energizing the relay switch CRZ to energize the solenoid S2 and to thereby start another reciprocation of the truing tool 210. When the relay switchCRZ is again energized a holding circuit is setup to maintain the solenoid S2 energized during the traversing movement of the truing tool toward the right. It will be readily apparent from the foregoing disclosure that as long as the switch SW3 yremains closed a continuous reciprocation of the truing tool 210 will be obtained. In either case to initiate a truing cycle it is necessary initially to close the switch PB3. A stop switch PB4 is provided to facilitate stopping the truing cycle at any time during its operation if desired.

It is desirable to provide a cycle control mechanism for 'controlling the duration of the grinding cycle. This is preferably accomplished by providing an electric timer T1 which is arranged to control the duration of the entire cycle. A manually operable control lever 235 is pivotally supported on the front of the machine base. When the lever 235 is rocked in a counter clockwise direction the starter switch FB2 is closed to energize the timer T1. The timer T1 may be any of the well known commercial timers such as, for example, the Microliex Automatic Reset Timer manufactured by the Signal Electric Company of Molene, Illinois. The energizing of the timer T1 closes the contacts CC1 and CCZ. The closing of the contact CCI serves to complete a circuit to start the work drive motor 9 which is mounted on the upper surface of the headstock 14. The closing of the contact CC1 serves to energize the solenoid S1 to shift the feed control valve 80 toward the left so that fluid under pressure is passed to cause a rapid approaching movement of the grinding wheel. Fluid under pressure is also passed through the pipe 116 to shift the valve member 111 toward the -right thereby passing fluid under pressure into the cylinder chamber 127to start the piston 51 toward the right thereby imparting :an infeeding movement to the wheel slide and the grinding wheel 23. The grinding cycle continues until the timer T1 times out at which time the contacts CCI and CCZ open to stop the work drive motor 9 and to deenergize the solenoid S1 thereby shifting the valve stem 81 toward the right due to the released compression of the spring 84. In this position of the valve 80, duid under pressure is passed, in a manner above described, into the cylinder chamber 8S to move the piston 76 toward the right thereby moving the grinding wheel 23 and the wheel slide 29 toward the right (FlG. 3) into an inoperative position.

The operation of the improved grinding machine will be kreadily apparent from the foregoing disclosure. The switch SW1 is closed manually to start the motor driven fluid pump 98. The switch SWZ is closed to start the wheel driving motor 24. When it is desired to start a grinding cycle the control lever 235 is rocked in a counter clockwise direction to close the switch FB2 thereby causing a rapid approaching movement o-f the grinding wheel in a manner as above described and at the same time passing fluid into the cylinder chamber 127 to move the piston 51 toward the right thereby imparting a rotary motion to the feed screw 35 to impart a grinding feed to the wheel 23. During the feeding movement of the grinding wheel, a reciprocating movement is imparted to the wheel spindle 22 so as to provide a break-up motion during the plunge-cut feed of the wheel.

As the work piece approaches the predetermined size, the cam 73 engaging the cam 74 rocks the feed pawl 72 together with the arm 15@ in a counter clockwise direction so as to shift the valve stem 141 toward the right against the compression of the spring 143. Fluid under pressure passing through the pipe enters the valve chamber 14S and passes through the pipe 194 into the right hand end of 'the cylinder 193 so as to move the piston 192 toward the left at a rate controlled by the valve 195 to traverse the grinding wheel 23 toward the left, so that the coarse grinding wheel moves out of engagement with the surface being ground, and the fine grinding or finish grinding portion of the wheel moves into opera-tive engagement with the surface being ground. The movement of the piston 192 toward the left serves to swing the arm 19) together with the arm 179 in a counter clockwise direction until a stop plunger 250 on the arm 190 engages a stop surface 251 within the wheel slide 2?.

During the axial `feeding movement of the wheel spindle 22, reciprocation of the spindle continues. The arm 175 and the forged portion 177 thereof shifts the stud 173 into position 17311 in which position it remains during the remainder of the grinding cycle. When the timer T1 times out and the wheel slide is moved to a rearward or inoperative position, the pawl arm 72 together with the arm swings in a clockwise direction thereby releasing the compression of the spring 148 which returns the valve member' 141 into a left hand end position. During this movement iluid exhausts from the right hand end of the cylinder 193 through the ball check valve 197, into the valve chamber 146 and through the pipe 153 and the pipe 96 into the reservoir 97 so as to reset the parts for the next grinding cycle.

When it is desired to true the operative face of the grinding wheel 23, the push button switch PBS is closed to start the truing operation. If switch SW3 is opened, the truing tool 21.1)l makes one complete reciprocation across the face of the wheel 23 and then stops. If the switch SW3 is closed the truing tool 210 will continue its reciprocatory motion across the wheel of the face until the circuit is broken by either actuating the switch 13134 or opening the switch SW3. s

It is desirable during'a truing operation to stop the wheel reciprocation. This is accomplished when the valve member 215 is shifted toward the right to pass fluid through the pipe 223 to start movement of the piston toward the right, fluid passes at the same time through the pipe 2&2 into the cylinder chamber 20G to move the piston 261 toward the left thereby swinging the arm 179 in a counter clockwise direction relative to the arm 19) so that stud 178 moves into position 17Sb out of contact with the right hand end of the notch 177. The arm will continue to oscillate but no motion will be imparted to the wheel spindle 22. The swinging movement of the member 179 in a counter clockwise direction continues until the stop screw 205 engages the stop surface 206. The parts remain in this position as long as the valve member 215 remains in the right hand end position. W ier1 the truing operation is stopped by actuation of the switch PB4 or in case of continuous truing by opening the switch SW1, the solenoid S2 is deenergized thereby releasing the compression of the spring 220 4so that fluid within the cylinder chamber 203 exhausts through the pipe 202 into the valve chamber 218, through the central passage 219 into the valve chamber 216 and through the pipe 230, the throttle valve 231 and the pipe 232 into the reservoir 97 thereby permitting the released tension of the spring 184 to swing the arm 179 in a clockwise direction so that the stud 178 engages the right hand end of the forged portion 177 of the arm 175. In this position of the parts the reciprocation of the wheel spindle is resumed.

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 may be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. A grinding machine having a grinding wheel rotatable about a given axis and movable transversely of its axis of rotation, said grinding wheel including a lirst portion for rough grinding and a second portion for nish grinding disposed in axial juxtaposition, a rotatable work support, means to feed said grinding wheel transversely of a workpiece to rough grind a cylindrical surface on a workpiece with the first portion of said grinding wheel, means operable at a predetermined point in the grinding operation to displace the grinding wheel axially for traversing the grinding wheel across the cylindrical face of a workpiece to finish grind the workpiece with the second portion of the grinding wheel, and means for reciprocating said grinding wheel axially during the entire grinding operation.

2. A grinding machine as claimed in claim 1, and, in addition, a grinding wheel truing apparatus including a reciprocable truing tool, means to reciprocate said truing tool across the operative face of the grinding wheel, and means to render said means for reciprocating the grinding wheel and said means for traversing the grinding wheel inoperative to hold the wheel spindle against axial movement during the grinding wheel truing operation.

3. A grinding machine as claimed in claim 1, and in addition, a grinding wheel truing apparatus including a reciprocable truing tool, a piston and cylinder to reciprocate said tool across the operative face of the grinding wheel, a control valve for controlling the admission to and exhaust of fluid from said cylinder, manually operable means to initiate a truing cycle, and means actuated by said control valve to render said means for reciprocating the grinding wheel inoperative during the truing cycle.

4. A grinding machine, as claimed in claim l, and, in addition, a grinding wheel truing apparatus including a longitudinally reciprocable truing tool, a first piston and cylinder to reciprocate said tool, a control valve therefor, manually operable means to actuate said valve to initiate a truing cycle, a second piston and cylinder arranged to render said means for reciprocating the grinding wheel inoperative to hold the grinding wheel against axial movement during the truing cycle and operative connections between the control valve and the second said cylinder to stop wheel spindle reciprocation at the start of a truing cycle.

5. A grinding machine having a rotatable work support, a transversely movable wheel slide, a wheel spindle rotatably supported upon said wheel slide, a grinding wheel mounted on and rotatable with said spindle, said grinding wheel including a first portion for rough grinding and a second portion for finish grinding, means to feed said wheel slide transversely of a workpiece to grind a cylindrical surface on a workpiece to a predetermined size CTI with the first portion of said grinding wheel, means to limit the infeeding movement, means operable when the infeeding movement is substantially completed to feed the wheel spindle in an axial direction to traverse the grinding wheel across the face of the work piece to finish grind the surface thereon with the second portion of said grinding wheel, and a wheel spindle reciprocating mechanism continuously to reciprocate said spindle .and grinding wheel axially during both the rough and finish grinding operations as well as the axial traversing movement of the wheel spindle.

6. A grinding machine as claimed in claim 5, wherein the means to feed said spindle axially includes a piston and cylinder operatively connected to feed said wheel spindle and grinding wheel axially to traverse the grinding wheel across the face of a workpiece to position the second portion of the grinding wheel to iinish grind the surface of a workpiece, and a control valve actuated by and in timed relation with the wheel slide feeding means to control the admission to and exhaust of fluid from said cylinder.

7. A grinding machine having a transversely movable rotatable grinding wheel, a rotatable work support, means to feed said wheel transversely at a normal grinding speed to grind a cylindrical surface on a workpiece, means to axially reciprocate said grinding wheel continuously during the entire grinding operation, means operable in response to a predetermined infeeding movement of the grinding wheel to feed the grinding wheel axially a predetermined first amount to traverse the grinding wheel across the face of the workpiece to iinish grind the same.

S. A grinding machine as claimed in claim 7, and, in addition, a grinding wheel truing apparatus including a reciprocable truing tool, means to reciprocate said truing tool across the operative face of the grinding wheel, means to displace the grinding wheel axially a second additional amount to render said means to reciprocate said grinding wheel and said means to feed the grinding Wheel axially inoperative, and means to hold the wheel spindle against axial movement during the grinding wheel truing operation.

9. A grinding machine as claimed in claim 7, and, in addition, a grinding wheel truing apparatus including a reciprocable truing tool, a piston and cylinder to reciprocate said tool across the operative face of the grinding wheel, a control valve for controlling the admission to and exhaust of fluid from said cylinder, manually operable means to initiate a truing cycle, and means actuated by said control valve to render said means to reciprocate the grinding wheel and said means to feed the grinding wheel axially inoperative during the truing cycle.

l0. A grinding machine as claimed in `claim 7, and, in addition, a grinding wheel truing apparatus including a longitudinally reciprocable truing tool, a first piston and cylinder to reciprocate said tool, a control valve therefor, manually operable means to actuate said valve to initiate a truing cycle, a second piston and cylinder arranged to render said means to reciprocate the grinding wheel and said means to feed the grinding wheel axially inoperative, means to hold the grinding wheel against axial movement during the truing cycle, and operative connections between the control valve and the second said cylinder to stop wheel spindle reciprocation at the start of a truing cycle.

l1. A grinding machine having a rotatable work support, a transversely movable wheel slide, a wheel spindle rotatably supported upon said wheel slide, a grinding wheel mounted on said spindle for rotation about a given axis, means to feed said wheel slide at a grinding rate to rough grind a cylindrical surface on a workpiece to a predetermined size with a tirst portion of said grinding wheel, means operable in response to a predetermined infeeding movement to displace the Wheel spindle in an axial direction to traverse the grinding wheel across the face of the workpiece to finish grind the surface thereon with a 11 second portion of said grinding wheel, and means for reciprocating said spindle continuously to reciprocate said spindle and grindingl wheel axially during the rough grinding operation, the axial traversing movement of the wheel spindle, and the iinish grinding operation,

12. A grinding machine as claimed in claim ll, wherein the means to displace said spindle axially includes a piston and cylinder operatively connected to displace said wheel spindle and grinding wheel axially to traverse the grinding wheel across the face of a workpiece to finish grind the surface thereon, and a control valve actuated by and in timed relation with the Wheel slide feeding means to control the admission to and exhaust of uid from said cylinder.

13` A grinding machine having a grinding wheel rotatable about a given axis and movable transversely of its axis of rotation, said grinding Wheel including a rst portion for rough grinding and a second portion for finish grinding disposed in axial juxtaposition, a rotatable work support, means to feed said grinding wheel transversely of a workpiece to grind a cylindrical surface on a workpiece with the rst portion of said grinding wheel, means operable at a predetermined point in the grinding operation to displace the grinding wheel axially to traverse the grinding wheel across the cylindrical face of a workpiece to finish grind the workpiece with the second portion of the grinding wheel, means selectively effective for reciprocating said grinding wheel axially operable during the entire grinding operation, and means operable to displace said grinding wheel axially a predetermined amount in 12 one direction selectively with concurrent reciprocation and without concurrent reciprocation.

14. A grinding machine having a grinding wheel rotatable about a given axis and movable transversely of its axis of rotation, said grinding wheel including a iirst portion for rough grinding and a second portion for nish grinding disposed in axial juxtaposition, a rotatable work support, means to feed said grinding wheel transversely of a workpiece to grind a cylindrical surface on a workpiece with the rst portion of said grinding wheel, means operable at a predetermined point in the grinding operation to displace the grinding wheel axially to traverse the grinding wheel across the cylindrical face of a workpiece to nish grind the workpiece with the second portion of the grinding wheel, means selectively effective for reciprocating said grinding wheel axially activated when the grinding wheel is rotated, means operable to displace said grinding wheel axially a first predetermined amount and disposed so as to maintain said grinding wheel reciprocating means eiective, and means operable to displace said grinding wheel axially a second predetermined amount and disposed so as to render said grinding wheel reciprocating means ineffective.

References Cited in the iile of this patent UNITED STATES PATENTS 1,584,717 Belden et al May 18, 1926 1,808,401 Cook et al. lune 2, 1931 2,648,172 Silven Aug. 11, 1953 2,758,426 Comstock Aug. 14, 1956