US2518600A - Infeed attachment for grinding machines - Google Patents

Description

Aug- 15, 1950 w. A. cox 2,518,600

INFEED ATTACHMENT FOR GRINDING MACHINES Filed Feb. 8, 1947 3 Sheets-Sheet 1 EN TOR.

Wm. r52 /7. Cox BY Aug. 15,1950 w. A. cox

INFEED ATTACHMENT FOR GRINDING MACHINES 3 Sheets-Sheet 2 Filed Feb. 8, 1947 INVEN TOR.

X a w a wn WW Aug. 15, 1950 w. A. cox 2,518,

INFEED ATTACHMENT FOR GRINDING MACHINES 3 Sheets-Sheet 5 Filed Feb. 8, 1947 INVENTOR.

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Patented M 15, 1950 UNITED INFE'ED ATTACHMENT FOR GRINDING MACHINES Walter A. Cox, Cincinnati, Ohio, assignor to The Milling llincinnati Machine '00., Cincinnati,

Ohio, a corporation of 7 Application February 8, 1947, Serial No. 727,436

' machines.

One of the objects of this invention is to provide an improved automatic infeed cycle control mechanism for a grinding machine.

Another object, of this invention is to provide an improved mechanism of the character described which has greater accuracy in sizing the finished work piece over existing mechanisms.

Another object of this invention is to provide a mechanism of the character described which can be built as a compact unit for attachment to existing machines. 1

Other objects and advantages of the present invention should be readily apparent by reference to the following specification, considered in conjunction with the accompanying drawings forming a part thereof, and it is to be understood that any modifications may be made in the exact structural details there shown and described, within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

Releasing to the drawings in which like reference numerals indicate like or similar parts:

Figure l is an elevation of a machine tool emhodying the principles of this invention.

Figure 2 is a section through the mechanism as viewed on the line 2-2 of Figure 1..

Figure 3 is a section on the line 3-3 of Figure l.

Figure 4 is a section on the line 6-5 of Figure 1.

Figure 5 is a detail view of the-feed rate control micrometer as viewed on the line M of .Elgm e 3.

' Figure 6 is a section on the line 6-6 of Figure 4,.

Figure "l is a diagram of the hydraulic control circuit.

Referring to the drawings and more particularly to Figure l the reference numeral l0 indicates the bed of a machine tool in the form of a grinding machine which for explanatory purposes has been ustrated as a centerless grinder. ch a machine has a pair of opposed grinding wheels, the'wheel ll serving the purpose oi a grinding wheel, and the wheel I! acting asa regplating wheel. interposed between these wheels is a work support it which carries a work rest blade it upon which a work piece, indicated by reference numeral 95, is supported during a grinding operation thereupon. The regulating wheel i2 is supported for rotation on a slide it which is reciprocably mounted on a second slide it which, in turn, is reciprocably mounted upon work support i3 relative to the grinding wheel and, after this has been locked in position, the slide I6 is moved relative to the slide II to adjust the regulating wheel I! toward and from the work support N as well as toward and from the grinding wheel whereby the size of the work depends upon how far the regulating wheel is moved toward the grinding wheel.

The slide it may be advanced and retracted by means of a feed screw it which is threaded in a suitable nut member not shown in the slide it, and this screw has a reduced or shaft-like portion l9 which extends through a feed rate control box 20 that is mounted on the end of the bed it. This box contains the mechanism forming the subject matter of this invention. As

shown in Figure 2, the portion i9 is supported in a sleeve 2i by thrust bearings 22, the sleeve being supported in a bore 23 formed in the box but keyed at 24 to a spline groove 25 formed in the bore. The result is that the sleeve 26 is subject to axial movement in the bore but held against rotation, while the portion i9 is subject to free rotation relative to the sleeve 2i and also responsive to axial movement of the sleeve 2 l In addition, the shaft portion i9 has a reduced splined end 26 by which it is operatively connected to a sleeve. 2'] which is supported for rotation in a bracket 28 attached to the end of the box. lhe sleeve Z'lhas a wheel 29 secured thereto whereby rotation of the hand wheel will aiiect rotation of the screw it.

The sleeve 2! may be clamped against rotation by means of a ring 30 which surrounds the sleeve and on one side has a threaded bore 3! in which is threaded a clamping member 32 that carries a shoe 33 for engagement with the periphery of the sleeve whereby, upon rotation of the member 32, the shoe 33 is pulled into clamping engagement with the sleeve. The member 321s supported at its outer end by a spherical bearing 34 mounted in the end of a tubular portion 35 of the bracket 28. A suitable operating knob 36 is secured to the end of the member 32 for imparting rotation thereto.

The hand wheel 29 is utilized for efiecting manual rotation of the screw l8 for set-up and adjusting purposes and also for manual controlled grinding operations, and to facilitate this control the bracket 28 has a disc 31 secured thereto, as by screws 38, and this disc has a, suitable indexmark or reference point for cooperation with graduation marks formed on the beveled face 39 of the hand wheel 29.

the bed it. The slide ll serves to adjust the 56 'Advance and retraction of the wheel I! is eifected by power through the sleeve 2| which is provided with rack teeth 48 engaging with a. pinion 4|. It will now be obvious that rotation of the pinion 4| will effect axial movement of the screw I8 without rotation to thereby cause sliding movement of the support I8. As shown in Figure 6, the pinion 4| is integral with a shaft 42 which is Journaled at 43 and 44 in the housing 20, and this shaft also carries a second integral pinion which meshes'with rack teeth 48, Figure 4, formed on a piston member 41 that is reciprocable in a cylindrical bore 48 formed in the housing 28. It should now be obvious that by introducing pressure to one end of the cylinder 48 and connecting the other end to exhaust that power reciprocation of the piston 41 and thereby power movement of the shaft I9 shown in Figure 2 may be eflected.

The automatic operation of the machine is controlled by the hydraulic. control circuit shown In Figure I to which reference is now had and in that Figure the reference numeral 49 indicates a pump for supplying fluid pressure to the circuit. This pump has an intake 58 through which oil is withdrawn from a reservoir and delivered under pressure into line 52 to which is branch connected a relief valve 53 for determining the high limit of pressure in the system. A

selector valve 54 has a pressure port 55 to which the line 52 is connected, and a pair of ports 56 and 51 to which the port 55 is selectively connected by the valve plunger 58. The port 51 leads to a hydraulic truing circuit indicated generally by the reference numeral 59, but the plunger 58 is normally in the position shown whereby the port 55 is connected to port 56 and channel 58. The channel 88 has a branch connection BI to pressure port 62 of a reversing valve indicated generally by the reference numeral 83.

This valve has an axially movable sleeve 54 in which is formed an annular groove 65 which serves to connect the port 82 with a port 55 when the sleeve is in the position shown. The port 88 is connected by channel 81 through a -check valve 59 to port 69 in one end of the cylfinder 48. It will now be obvious that with the parts in the position shown that the piston 41 will move toward the right at a rapid traverse rate.

Fluid will exhaust from the other end'of cylinder 48 through port 18 and channel II to port I2 of a pilot control valve I3. The port I2 which is in the form of an annular groove has a radially extending port 13' which is in communication with an annular groove I4 formed in an axially reciprocable sleeve I5. In the position shown the annular groove I4 connects the port I3 with a port I6 to which is connected a channel II which leads to a throttle'valve I8. This throttle valve may be adjusted to regulate the rapid traverse rate of advance of the regulating wheel toward the work, the fluid exhausting from the throttle valve through channel I9 to port 88 of the reversing valve. The port 88 is connected by an annular groove 8| formed in the valve sleeve 64 to port 82 and exhaust channel 83 which leads back to the reservoir 5|.

As the piston 41 advances it also causes rotation of a gear 84 which as shown in Figure 6 is integrally formed withthe shaft 42. The pinion 84 is connected through an idler pinion 85, Figure 3, to rack teeth 86 formed on the periphery of a plunger 81 which carries a follower roller 88. Thus, as the piston 41 advances toward the right as viewed in Figure '7 it causes the v 4 plunger 81 to advance and move the roller'88 into engagement with a feed rate control cam 89 which is more clearly shown in Figure3. This cam is pivoted on a pin 98 and carries a shoe 9I in the form of a pin which is adapted to ride determinator tate the cam member 89 in a counterclockwise direction as viewed in Figure 3 about its pivot pin 90 and thereby present an inclined surface to the roller 88. The cam member89 is held in contact with the inclined surface 92 by means of a spring 96 which surrounds a headed pin 91, this pin being secured in the carrier by a set screw 98. Thus, as the cam 93 is shifted upward as viewed in Figure 3 the cam 89 will be caused to move clockwise about its pin 98 and follow up any drop in the surface 92. The cam carrier 95 is provided with a pair of rollers 98 and 99 which ride on the surface I88 formed on a fixed part of the bracket 28. It should now be evident that the surface 94 of the cam carrier 95 constitutes a fixed abutment normal to the direction of movement of the plunger 81.

The member 93 is adjusted downward to incline the cam 89 by threading an actuating rod I8I at I82 in the carrier 95 whereby rotation of the rod I8I will cause the member 93 to be adjusted relative to its supporting member 95. During the actuation of the machine the member 95 is fed upward as viewed in Figure 3 by a feed piston I83 which .is slidable in a cylinder I84, the piston being connected to the carrier 95 by means of a pinion I85 which is interposed between the parts and which interengages with rack teeth I85 formed on the piston I83 and rack teeth I8'I formed on the carrier 95.

The rod IN is adjustable from the outside of the box 28 by means of a micrometer mechanism.

including a sleeve I 88 which is rotatable in a bracket I89 that is secured to the box 28. The sleeve I88 has a splined connection at II8 with the rod I8I whereby rotation of the sleeve will effect adjustment of the member 93 relative to its support 95 but upon movement of the support 95 upwardly as viewed in Figure 3 the rod I8I will slide relative to the bore of the sleeve I88. This sleeve also has a threaded exterior portion III which meshes with a slider or indicator II2 whereby upon rotation of the sleeve the indicator II2 will be moved longitudinally as viewed in Figure 5 relative to some graduations II3 which are formed on the fixed bracket I89. In addition, the fixed bracket has a beveled end surface II4 upon which is a reference mark H5 and the periphery of the sleeve I88 is provided with a series of graduation marks I I6 similar to the barrel on a micrometer to facilitate adjustment and setting of the cam 89.

The cam carrier 95 is shown in its starting position in Figure 3, and it should now be obvious that with the cam member 89 inclined at some angle that the cam will act as a positive stop to limit the rapid traverse movement of the wheel head as effected by the piston 41. When this occurs the pressure in the supply line 81 to the port 69 of the rapid traverse cylinder 48 will naturally'rise, and this increase in pressure will be transmitted through'the branch line I", Figure 7, and resistance II8 to port I I9 of a time delay valve I20. The rise in pressure will overcome the resistance of a spring I2I and move the valve plunger I22 to the left as viewed in Figure 7.

Simultaneously with the engagement of the cam roller 88 with the cam 89 a'set screw I23, Figure 2, is so adjusted relative to its supporting arm I24 that it will engage a pin I25 and shift the pilot valve 15. The trip actuation of the arm- I24 is more clearly shown in Figure 2 from which it will be seen that the arm I24 is slidably mounted on a reduced portion I26 of the member I9 and held against the end wall I2I of the box 20 by a spring I28. The portion I26 carries a ring I29 which is securedthereto by a pin I30 and as the member I25 moves toward the left as viewed in Figure 2 the ring I29 will engage the annular surface I3I on they arm I24 and shift the same toward the left against the resistance of spring I28. It will be noted that there is a certain amount of lost motion between the ring I29 and the surface I3I so that the arm I24 only has a limitedgmovement and the actual timing of the shiftiiigof the valve plunger may be determined by adjusting the set screw I23.

When the valve 15 is shifted to the left, as viewed in Figure 7, it will shift the annular groove 34 sufllciently to the left-to disconnect port 12- from port I6 and thereby close a by-pass which existed around a throttle valve I 32.

This now causes the return oil from cylinder 48 to be forced through the throttle valve I32, thereby decelerating the rapid traverse movement of the wheel head to reduce the impact effect of the follower roller 88 when it engages the cam 89. The shifting of valve plunger I5 will also connect port I33, to which is connected a branch line I34 of the rapid traverse cylinder supply line 61, to an annular groove I35 whereby fiuid pressure may flow behind the piston I5 and shift it the full length of its stroke independent of the pin I25. This will also disconnect the port I33 from'a port I36 to which it was connected by the annular groove I31. When the ports I33 and I36 are connected, fluid pressure flows through the line I38 1% cylindrical space I as and moves plunger I40 against the resistance of a strong spring I 4| tdyhold a valve element I42 in the position in whi it is shown in Figure 7, but upon disconnection of these ports the port I35 becomes connected to port I2 and thereby line II which is at lower pressure than the pump pressure in channel I3t whereby the spring MI is capable of shifting the valve plunger I42 against the pressure in the cylindrical space I39 resulting in the interconnection of a pair of ports I43 and Ito.

The port I44 is connected by a channel I45 to a port I06 located in one end of the'feed cylinder I04. As previously mentioned, this cylinder contains a piston I03 and the other end of this cylinder has a port III which is connected to a branch from line 6? which is under pressure. Therefore, there is an urge on the piston I03 to move downward as viewed in Figure 7, but the line I45 from port I46 located at the other end of the cylinder has been blocked at port I44. By the shifting of the valve member I42 the port-I44 becomes connected to port I43 whereby the fluid in the lower end of cylinder I04 may now pass through line I48 to port I49 of the interlock valve I22. As previously explained, the rise in pressure in line 51, caused by the follower roller 88 engaging its cam 89, will cause shifting of the valve plunger I22, resulting in port I49 being connected by annular groove I50 in the valve member to port I5I and channel I52. This channel has a feed rate throttle valve I53 serially connected therein so that by variably throttling the oil the feeding rate of the feeding piston I03 can be determined. Thus, the shifting of the valve piston I22 institutes the feeding movement of the wheel I 2.

Attention is invited to the fact that the pump pressure supply line 60 has a branch connection I54 to a second port I55 located in the end of cylinder I04, and this port communicates with an axial bore I56 formed in a member I51 which is mounted within the cylinder I 04 and has a telescoping connection with a drilled hole I58- formed in the end of the piston I03. This means that pump pressure continuously exists in the space I58 exerting a continuous urge on the pie-- ton I03 in an upward direction as viewed in Figure 7, but the pump pressure entering the port I41 has a larger area of the piston I03 to work on and therefore will force part of the oil in space I58 back into the supply channel 60 during the feeding movement.

It will thus be seen in the cycle of operation so far that a rapid traverse movement was first instituted, followed by a deceleration of the rapid traverse movement at the time of engagement with the feed cam, and that the pressure still existing in the cylinder 48 also effected the feeding movement but the rate of the feeding movement is controlled by the rate of movement of the cam. The length of the feeding movement is determined by the collar 22 on the sleeve 2! engaging the positive stop 22' which is the closure member for the end of the bore 23. Thus the infeed' movement always stops by engagement of these parts and if the size of the work is not correct, adjustment is made by the hand wheel 29 rotating the screw I 8.

This method of stopping is also independent of the' feed cam, in that the feed cam can still keep on going, and therefore has nothing to do with the final size of the work. The continuation of its movement, however, serves to operate the reversing mechanism to effect retraction of the wheel by means of the following mechanism.

The piston I03 carries a pin I59 which extends into an adjacent loore I60 in which is slidably mounted a trip member I6! for the reversing valve pilot plunger I62. The member ItI has three flats formed in the periphery thereof, one of which has a length as indicated by the line its, the second of which has a length as indicated by the line I64, and the third of which has a length as indicated by the line I55. The member Iti may be rotated to present any one of these three flats to the pin I59 and is adapted to be held in any one of these positions by a spring pressed detent I66 as shown in Figure 3 and engageable with longitudinally extending detent grooves indicated generally by the reference numeral I61.

These different flats provide different lengths of lost motion between the member I6I and the pin I59. It will be noted that the shoulder I68 is the common end wall for all of these flats and is the one which determines the limit of the infeeding strokes may beselected.

when thepin I50 engages the wall I during a feeding movement it shifts the plunger IOI and .spools I10 and I14 slide, and therefore as the spool I10 passes to the other side of the pressure port "I a hydraulic detenting action will take place to complete the shifting of the valve plunger to the end of the enlarged bore I15.

This will result in the connection of pressure from port "I to port I16 and channel I11 to port I10 of a run and return valve I10. This valve has a rotatable valve spool I00 which may be manually rotated by a crank lever IOI secured to the end of the plunger. When the valve plunger I00 is in the position shown, the port I10 is connected to a radial port I02 which communicates with an axial bore I03 formed in the plunger which has a second radial passage I04 which at this time is in communication with a port I05. The port I05 has a channel I06 connected to it which leads to a throttle valve I01 for throttling the flow through line I00 to the end port I00 of the reversing valve cylinder 63. The purpose of the throttle valve I01 is to establish a predetermined delay in the shifting of the reversing ,valve sleeve 64.

The port I00 is connected through an annular groove I00 and radial port IOI to the interior of the sleeve 64 for the purpose of shifting a piston plunger I02 which is slidably mounted in a bore I03 formed in the valve sleeve 04. This plunger has a pair of spools I04 and I05 formed thereon and the plunger is capable of lost motion movement with respect to the sleeve. Thus, upon admittance of pressure through port IOI the plunger this time, but the actual shifting of the reversing valve sleeve 04 cannot be effected until the piston I02 has taken up its lost motion with respect to the sleeve 04, the lost motion at this time being the distance between the shoulder I00 on the piston I02 and the shoulder I01 formed by a disc which is integrally connected with the sleeve. Upon engagement with this shoulder the sleeve 04 is shifted, causing the spool I00 formed on the sleeve to be moved past the pressure port 02, thereby connecting this port to port 00 and at the same time disconnecting port 00 from the exhaust port 02. Fluid pressure will now flow through line 10, bypassing the throttle valve 10 through check valve I00 and channel 11 to port 10 of valve 10.

At the same time, port 06 of the reversing valve is connected to port 200 which has the return channel 20I connected thereto. This relieves the pressure in channel 61 and branch line I04 of valve 13 whereby the fluid in the end of valve 10 may be forced out to reservoir by the spring I31, shifting the valve plunger back to its normal position in which it is shown in Figure 7. This results in the line 11, now under pressure, being connected through the annular groove 14 directly to port 12 and line H whereby the fluid pressure will enter the cylinder 40 and return the rapid traverse piston 41 to its starting position.

for the advance stroke.

Thi will simultaneously cause retraction of the follower roller 00 from its control cam 00 through the rack and gear connection. To prevent the return movement of piston 41 from being at too fast a rate, a throttle valve 202 is connected in parallel with the check valve 00 so that/as the check valve is closed by the returning fluid, the returning fluid is forced to pass through the valve 202. In addition, the end of the cylinder 40 is provided with a dashpot mechanism comprising a central plunger 203 which is caused at all times to follow up the movement of piston 41 by means of a spring 204. It will be obvious then that as the member 200 moved forward it uncovered a port 205 in the sleeve member 200.

The port 200 is in continuous communication with a wide internal annular groove 201 formed in the bracket 200 secured to the outside wall of the box 20, and this groove is connected by radial ports 200 to the end space 2I0 of cylinder 40. The member 200 is threaded in the bracket 200 as shown in Figure 4 for adjustment relative thereto whereby the relative position of the port 205 may be adjusted longitudinally to determine the amount of return of the piston 40, or in other words, to determine its starting position As the plunger 200 is moved to the left by the returning piston 40 it throttles the escape of fluid through the port 200 and thereby builds up a hydraulic cushion to decelerate the movement of the piston 41.

Should the port 205 become closed to such an extent that upon advancing movement of the piston 41 the oil could not return fast enough through the throttled port 205 to the spring space 200' the end of the piston 41 would momentarily leave the end of the plunger 200, in which event the pressure fluid entering the space 2 I 0 would be able to pass through an axial bore 2 formed in the end of the plunger 203 and force itself by the check valve 2I2, thereby forming an auxiliary supply to the cylindrical space 200.

As previously recited the channel 01 which has a branch connection I41 to the feed piston I00 was connected to reservoir on the shifting of the reversing valve, and this relieves the pressure on the upper end of piston I03 as viewed in Figure 7 whereby the constant pressure which exists in the space I50 becomes effective to return the feed piston I00 in an upward direction as viewed in Figure '7. Since the line I40 leading to the lower end of the cylinder might be closed a suction check valve 2I0 is branch connected between the reservoir 5| and the line I40 whereby it the returning movement of the piston I00 is at such a rate that it might tend to cause a vacuum in the lower end of the cylinder I04 oil from the the pilot valve will be connected to port 2 and line 2|! to the cycle start valve 2 I0 having a port 2" which forms the terminus of the line 2". This port is normally disconnected from a port 2I8 which is connected by line.2I0 to port 020 located in the end of the reversing valve 00. It will thus be seen that the reversing valve will not be shifted to a forward position to start a new cycle until the cycle start valve plunger 22,I is manually moved to the right as viewed in Figure 7 so that the annular groove 222 can interconnect the ports 2I1 and 2I0. Thus, the cycle will automatically stop so, that the operator may manually load a new work piece in the machine.

4 -However, if the machine has an automatic loading attachment and the time can be determined that it takes to load a work piece in the machine a delay throttle valve 223 is interconnected to lines 2I5 and 2I9 in parallel relation to the cycle start valve whereby the valve 223 may be adjusted to produce a predetermined timed delay before the reversing valve is shifted to start a new cycle.

In any case, the sleeve 64 in the reversing valve will be in its down position as viewed in Figure 7, and when fluid pressure does enter port 220 it will pass through the radial ports 224 into the annular groove 225 formed in the periphery of sleeve 84 and which at this time is in registry with the ports 224. By means of the radial passages 226 the fluid pressure will flow from the groove 225 into the space 221 and cause upward movement of piston 63 which, in turn, will cause upward shifting of the reversing valve sleeve 84 to its forward running position.

At any time during the operation 01 the machine and especially in case of an emergency the valve I8I may be actuated to cause immediate separation of the grinding wheels. As previously noted, the valve II" is shown in its run position but upon rotation of the valve plunger I80 to its retracted position a port 228 which is continuously connected by a line 229 directly to the pump pressure-will be connected through radial grooves 230 and the axial bore I83 to radial ports 23I which will now be in registry with ports 232 which communicate with a line 233 which is connected in parallel across the throttle valve I81, thus forming a direct connection for the admittance of pump pressure to line I88 and shifting of the reverse valve to its retract position.

Attention is invited to the fact that when the cycle control valve 2I6 is utilized to start the cycle that there is a branch line 234 from the main line 61 which supplies fluid pressure to the rapid traverse and feed cylinders so that immediately upon this line becoming connected to pressure that some of the fluid pressure is-admitted to chamber 235 of the cycle start valve 2; to shift valve plunger 22! automatically to its stop position.

It should also be noted that the reversing valve has a spring 236 mounted in one end which acts on one end of the valve sleeve to hold it in its down position as viewed in Figure 7. When the piston member I92 moves the sleeve up sufficiently to connect pressure port 82 to annular groove 65, the fluid pressure flows through a drilled hole 231 in member I92 to an interdrilled passage 238, in the end of which is slidably mounted a piston pin 239. The hydraulic pressure acting on the pin serves to hold the piston member in its up ward shifted position especially when reversal takes place and the lower end of the valve is connected to reservoir.

Also, when port 62 is connected to groove 65, a-differential hydraulic pressure is created to hold the sleeve up. This is accomplished by making the spool I98 larger in diameter than the adjacent spool, and having it slide in a larger bore, thus creating a shoulder area 240 which is Figure 4 a hydraulic detenting pressure is created mechanism for said support including a first fluid operable device for advancing said support at a rapid traverse rate, means for throttling said device to cause movement at a slower rate, a second fluid operable device for controlling subsequent movement at a, feed rate, a pilot valve operable by said second device, and a revers valve controlled by the pilot valve for are; the direction of movement of both of said devicw to eflect retraction of the wheel support.

2. In an infeeding mechanism for a grinding machine having a wheel support, the combination of a feed screw threaded in the support, a sleeve mounted on the feed screw and interconnected therewith for joint axial movement, independent means for slidably supporting the sleeve and holding the same against rotation, a follower plunger, a fluid reciprocable member, rack and gear connections between said member and said sleeve and said plunger for imparting simultaneous movement thereto, a feed rate control cam arranged transversely of the path of movement of said plunger, power operable means for feeding said cam for controlling the feeding rate at said sleeve and screw effected by said fluid operable member, a positive stop engageable by said sleeve for limiting the advancing movement at said screw, and trip operable means for revers at actuation of the moving parts to a starting pool tion.

3. In a grinding machine having a wheel support, the combination of power operable me for advancing and retracting said support, a source of pressure for said power operable means, a reversing valve for connecting said source 03 pressure with said power operable means includ ing a shiftable valve sleeve, a piston member slidable within said sleeve, a pilot valve operas ble by said power operable means for connecting pressure to said piston member, a lost motion connection between said piston member and sleeve, and a. throttle valve interposed between said pilot valve and said piston member for regulating the movement of said piston member in. taking up said lost motion to thereby control the delay between actuation of the pilot valve and the shifting of said valve sleeve.

4. In a grinding machine having a wheel support, the combination of an infeed cycle control mechanism'for said support, including fluid operable means for reciprocating said support, a source of fluid pressure, a reversing valve for selectively connecting said pressure for reverse operation of said fluid operable means, an autoof sufficient area to hold the sleeve up against matically operable pilot valve for connecting said pressure to effect shifting of said reversing valve, a cycle control valve normally positioned for blocking the flow from the pilot valve to one end of said reversing valve to prevent shifting of the reversing valve to its support advancing position, said cycle control valve being manually shiftable to efiect the interconnection to cause shifting of the reversing valve, and means responsive to subsequent shifting of the reversing valve to automatically efle'ct shifting of the cycle control valve to its blockingposition.

auaeoo to a slide retracting position, and means serially arranged in said last-named connection to connect the source oi pressure directly to said reversing valve independent of the pilot valve to eilfect shitting oi the reversing valve at. will to its slide retracting position.

6, In a grinding machine having a wheel support, the combination oi an inieeding mechanism ior said support comprising fluid operable means for shifting said support, a source oi pressure, a feed control cam for retarding the movement of said support by said fluid operable means to a predetermined feed rate, a fluid operable piston for actuating said cam, means connecting said source of pressure for exerting a constant urge on said piston toward its starting position, valve means for connecting said source of pressure to cause advancing movement of said piston simultaneously with the connection of pressure to said fluid operable means, a channel for conducting exhaust fluid away from the other end of said piston, serially arranged blocking valves in said channel, means responsive to a predetermined advance of said support for releasing one of said blocking valves, a positive stop for limiting the movement to be eflected by said fluid operable means, and means responsive to engagement of said positive stop for releasing the second blocking valve.

7. In a grinding machine having a wheel support, the combination of an ini'eeding mechanism iorfsaid support comprising fluid operable means for shifting said support, a source of pressure, a control cam for retarding the movement of said support by said fluid operable means to a predetermined feed rate, a fluid operable piston for actuating said cam, means connecting said source of pressure for exerting a constant urge on said piston toward its starting position, valve means for'connecting said source of pressure to cause advancing movement or said piston simultaneously with the connection oi pressure to said fluid operable means, a channel for conducting exhaust fluid away from the other end of said piston, serially arranged blocking valves in said channel, means responsive to a predetermined advance. of said support for releasing oneot said blocking valves, a positive stop ior limiting the movement to be eiiected by said fluid operable means, means responsive to engagement 0! said positive stop for releasing the second blocking valve, and a throttle valve in said channel tor controlling the rate of movement of said piston.

8. In a grinding machine having a wheel support, the combination oi an inieed cycle control mechanism for said support including a fluid shii'table piston, motion transmitting connections between said piston and said support, a source of fluid pressure, means to connect said source of fluid pressure to one end of said piston to eflect advancing movement of said support, serially arranged throttle valvesin the return connection from the other end of said piston and sequentially actuable to produce successively diflerent rates oi advancement of the grinding wheel sup-.'

port, means to reverse the connections to said piston and simultaneously by-pass said serially arranged throttles, an additional throttle automatically rendered effective upon reversal of flow to said cylinder to control the rate of support retraction. V

9. In a grinding machine having a wheel support, the combination or an ihfeed cycle control mechanism therefor, including a fluid operable piston for advancing and retracting said support, a source of pressure, a reversing valve for connecting said source of pressure to said piston, said reversing valve having a shiftable sleeve valve member and an internal piston member having a lost motion connection with said sleeve, a spring normally maintaining said sleeve in a support retracting position, said piston being independently actuable to effect shifting of said sleeve, independent means for maintaining said piston in its shifted position, and hydraulic means for maintaining the sleeve in its shifted position.

, WAL'I'ER A. COX.

REFERENCES crrEn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,920,228 Wood Aug. 1, 1933 2,023,704 SiIVen Dec. 10, 1935 2,267,391 Astrowski Dec. 23, 1941 2,294,265 Wortendyke et al. Aug. 25, 1942 2,368,992 Ljunggren Feb. 6, 1945 2,376,236 Decker et al. May 15, 1945 2,376,237 Decker et al. May 15, '1945

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