US2367759A - Grinding machine - Google Patents

Description

Jan. 23, 1945. DECKER ETAL 2,367,759

GRINDING MACHINE Filed Aug. 13, 1942 6 Sheets-Sheet 1 INVENTORS.

Jan. 23, 1945. J. DECKER ET AL 5 5 GRINDING MACHINE Filed Aug. 15, 1942 a Sheets-Sheet 2 Jan 23, 194-5. DECKER ETAL 2,367,759

- GRINDING MACHINE Filed Aug. 13, 1942 6 Sheets-Sheet 5 mill-lull A770 NEX Jan. 23, 1945. J. DECKER ETAL 2,367,759

GRI NDING MACHINE Filed Aug. 13, 1942 6 Sheets-Sheet 4 Jan. 23, 1945.

Filed Aug. 15, 1942 6 Sheets-:Sheet 5 Jan. 23, 1945. J. DECKER ET AL GRINDING MACHINE 6 Sheetg-Sheet 6 Filed Aug. 13, 1942 INVENTORS. J4co5 pfC/Tf? fiafp/i-Kfiaamy BY M W/W.

Patented Jan. 23, 1945 GRINDING MACHINE Jacob Decker, Cincinnati, and Albert D. C. Stuckey, Hamilton, Ohio, assignors to The Cincinnati Milling' Machine Co., Cincinnati, Ohio, a corporation of Ohio Application August 13, 1942, Serial No. 454,682

17 Claims.

This invention relates to grinding machines and more particularly to an improved automatic infeeding mechanism for the grinding wheels of such machines.

One of the objects of this invention is to provide an improved automatic infeeding mechanism for controlling the movement between a grinding wheel and a work piece in such a manner that the grinding wheel will execute a complete cycle of rapid advancing to the work, moving at a slow feed rate to grind the work to size and of automatically returning to its starting position.

Another object of this invention is to provide improved hydro-mechanical transmission for executing infeed cycles in which the actuating force is hydraulic and the controlling force is mechanical. Y

A further object of this invention is to provide an improved power operated infeed mechanism which is suitably interlocked with the table traverse mechanism so that inadvertent power or manual movement of the table is prevented during operation of the cycle.

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 mad 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.

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

Figure 1 is a front elevation of a grinding machine embodying the principles of this invention.

Figure 2 is a, vertical section through the machine shown in Figure l with suitable parts broken away to show the mechanical part of the transmission for feeding the grinding wheel.

. Figure 3 is a vertical section through the machine as viewed on the line 33 of Figure 1 showing the table traversing mechanism.

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

Figure 5 is a diagrammatic View of part of the hydraulic control circuit.

Figure 6 is a diagrammatic view of the remainder of the hydraulic control circuit and more particularly the table control mechanism.

Figure '7 is a section on the line 1-1 of Fig ure 2.

Figure 8 is a section on the line 8-8of Figure-7.

Figure 9 is an enlarged detail view of amultiple position stop for determining the angularity of th feed rate control cam.

Referring to Figure 1 of the drawings thereierence numeral 10 indicates the bed of a grinding machine embodying the principles of this invention. The upper part of the front of the bed is provided with a pair of guideways II and I2 as more particularly shown in Figure 3 for ree ceiving and guiding a work table l3 which is .utilized for traversing a work piece relative tolthe grinding wheel l4 shown in Figures 1 and,2,. The grinding. wheel is suitably supported for re} tation on the wheel slide l5 and conventional means. not shown are carried by the slide for driving the grinding wheel. v

The table [3 is actuated by a hydraulic motor in the form of a cylinder l5 and a piston it, Figure 6, the piston being connected by a piston rod I! to the table I3. The admittance and exhaust of fluid pressure to the cylinder l5 iscon trolled by a table control valve, various sections through which are indicated by the reference numerals l8, I9, 20 and 2| in Figure 6 of the drawings. This valve has a rotatable plunger 23 to which the control lever 24, shown in Figure l, is operatively connected through gearing 24', whereby the lever rotates in an opposite direction to the valve plunger 23. This lever has a central or stop position which is the position shownf,-'-a running position indicated by the dash 'and 'do t line 25 which is to the left of the stop position, and a third position indicated by the dash and dot line 26 which is to the right of the stop position and which is utilized to efiect automatic retraction of the grinding wheel.

The wheel head is provided with a cylinder -27, Figures 2 and 5, for receiving a rack piston 28. A pinion 29 is secured to the upper end of avertical shaft 30 in mesh with the rack portion 3| of the piston 28 and the lower end of the shaft is provided with a worm wheel 32 whichinter meshes with a worm 3s. Attention isinvited to the fact that the shaft 30 is journaled in the bed l0 and therefore isincapable of anyrelative bodily movement with respect to the bed'while" the rack piston is capable of relative bodily movement with respect to the wheel head [5.

Also the worm 33 is supported for relative axial movement withrespect to the bed I 0 by a piston 34 and a journal 35 which are formed integral with opposite ends of theworm. The piston3 i slides, ina cylinder 36 While the journal 3-5 is capable of rotation or axial movement relative to the bearing 3? which is carried by the bed.

The piston and cylinder 21, 28 are utilized in effecting rapid traverse movement of the wheel head, while the axial movement of the worm 33 is utlized for effecting feeding movements of the wheel head. Rotation of the worm 33 -is utilized for effecting adjustment of the wheel head relative to its actuating mechanism to change the final or size determining position of the grinding wheel.

In an automatic infeed cycle of the grinding wheel, the wheel head is first advanced at a rapid traverse rate to bring the wheel up to the work. A feed rate is then instituted which causes the work to be ground to size and then after a slight dwell to allow the grinding wheel to clean up, automatic reversal takes place causing the wheel head to be returned and stopped.

The hydraulic control circuit in Figure 5 has the various parts shown in the position which they assume just prior to the automatic reversal. In order to more clearly understand how these movements are obtained let itbe assumed that the wheel head is in a retracted position. Since the cylinder 21 is divided into two portions the forward portion of thezcylinder will be indicated by the reference numeral 38 and the rear portion of the cylinder will be indicated by the reference numeral 39. The piston portion which slides in the cyliner 38 will be indicated by the reference numeral 40 and the piston portion which slides in the cylinder 39 will be indicated by the reference numeral 4!. When the wheel head is in a retracted position, fluid pressure has been connected to the cylinder 39. Since the pinion 29 is held against rotation by its locking connection with the worm 33, which in turn holds the rack piston 28 and thereby the piston 4| against bodily movement, pressure in cylinder 39 will force the slide l5 to the rear.

It must be remembered, however, that the forward end of the piston 40 will engage the end of cylinder 38 to limit or stop the movement and that once contact is established between. the piston 40 and the end of cylinder 38, the rack pisten 28 and slide 15 may be considered as a single entity so that torsional strain on the pinion 29 is immediately relieved. Further, the pinion 29 may be rotated to effect bodily movement of the wheel head IS in either direction and the only resistance is the friction of the slide.

It has been stated that the worm 33 was capable of axial movement relative to the bed, but this movement is limited in extent and only sufficient to effect the feed or stock removal operation. The cylinder 36 is connected to a source of pressure at al times, and *since the cylinder is part of. the bed the piston 34, as well as the worm 33, are constantly urged toward the right as viewed in Figure 2. An anti-friction thrust bearing 42 is interposed between a shoulder 43 formed on. the. end of the: journal 35, and a thrust plate 44' attached to the staface recedes sufficiently at the end of its stroke to permit the worm to engage the positive stop.

If any additional movement is necessary, the worm must be rotated by the handwheel 46 which is connected through gearing 41 to the shaft 48. The shaft 48 is connected to the piston rod 49 of piston 34 by a slidable joint 50 which permits relative axial movement between the shaft 48 and the rod 49,

It will thus be seen that the rack 28 is normally locked with the wheel head and that the worm 33 is locked between the cam 45 and the hydraulic pressure acting on the piston 34 so that during rotation of the hand wheel the effect is the same as if no sliding connections existed between the various parts and the wheel head may be adjusted in either direction. Such adjustment changes the zone of operation of the grinding wheel as for different sizes of work without changing the length of its rapid traverse or feed movements.

'I'o effect automatic operation of the wheelhead, fluid pressure is admitted to the forward cylinder 38 and the rear cylinder 39 is connected to exhaust whereby the fluid pressure reacts against the piston which is held against movement by the pressure in cylinder 36. The wheel head advances relative to the rack piston 23 until it hits the rear end of piston 41 whereby it is positively stopped and once again the piston and the wheel head become a single unit. Further advancing is effected at a feeding rate by moving the cam in the direction of arrow 5| as viewed in Figure 5, thereby causing the face of the cam to recede whereby the fluid pressure in cylinder 36 will urge the worm 33 toward the right and cause movement of the wheel head through the rack piston 28 toward the left, all as viewed in Figure 5, thereby feeding the grinding wheel l4 toward the work.

The length of the rapid traverse movement may be varied by adjusting the set screw 52 which is threaded in the end of cylinder 39 and locked in position by a locking nut 53. Normally, once this adjustment has been made it would not be necessary to change it. The length of the rapid traverse movement should, of course, be so adjusted as to permit sufflcient clearance between the wheel and the work when the wheel head is in its extreme rear position to permit loading and unloading of the work without danger of hitting the wheel,

The control circuit shown in Figures 5 and 6 are for governing these movements automatically and sequentially whereby the grinding wheel will execute a complete automatic cycle of rapid traversing and feeding in to the required size and returning after the grinding operation has been completed. This cycle is initiated by the operator who throws a lever to a starting position after which the cycle is executed and the lever automaticaly returned to its stop position.

This cycle control lever is indicated by the reference numeral 54 in Figure 1 where it is shown mounted on the right hand side of the machine. This lever is connected to the end of a valve plunger 55, a control portion of which is indicated by the reference numeral 56 in Figure 5. The valve is indicated generally by the reference numeral 51 and is provided with a constant pressure port 58 which is supplied through channel 59 from a pump which has an intake 6| for withdrawing oil from a reservoir 62. A relief valve 33 is connected to the output channel 59 of the pump for controlling the pressure therein. The valve is shown in a running position at which time the lever 54 assumes the position indicated by the dot and dash line 64. In the stop position of the valve, the lever assumes the position indicated by the line 65, and the vane 66 assumes a position in which the port 58 is connected to a port 61 and thereby through channel 68 to cylinder 49. This holds the wheel head in its retracted position as previously explained. By rotation of the lever from the position 65 to the position 64, the pressure port 58 is connected to port 69 and thereby to channel 1.0 to start the automatic infeed cycle.

The channel 10 has a branch connection H to port 12 of an infeed control valve 13 but the plunger 14 of this valve is normally held in a right hand position by a spring I and therefore the port I2 is closed. The fluid in channel Il may continue, however, through the annular groove 16 in the sleeve of the valve 13 to passage I! and port I8 of a reversing valve 19.

The plunger 80 of this valve is normally held in the position shown to close the port 18 by pressure from the pump 60 which is connected to port BI and thereby through annular groove 82, and radial port 83 to an internal bore 84 which serves as a cylinder, the bore being closed by a fixed piston rod 85.

The channel is also connected through a re sistance 86 to port 81 of a footstock control valve 88 whereby the fluid pressure enters the upper end of the valve and forces the plunger 89 downward against a spring 90. The fluid pressure entering the chamber 9| in the upper end of the valve is able to continue through port 92, after the plunger moves down, and through channel 93 to port 94 located in the right hand end of the infeed control valve 13, and to pressure switch 95, operation of which initiates rotation of the machine headstock.

Shifting of the footstock valve plunger 89 also interconnects a pair of ports 99 and 97, the latter being connected by channel 98 to a tailstock center operating cylinder 99. Normally, the port '91 isconnected to the pressure port I99 by the annular groove IllI whereby pressure exists in cylinder 99 to hold the tailstock center I02 in a retracted position against the resistance of a spring I93. In other words. a piston I94 responsive to the pressure in cylinder 99 actuates the tailstock center through a pivoted crank which is rotatable about a fixed pivot I95. The port 96 is connected to a return line Iill which leads to the reservoir 62. A low pressure relief valve I98 is connected in this line to maintain a very low pressure in the exhaust system and thereby insure against air getting into the operating system.

It should now be apparent that when the port 9'! is interconnected to the port 96 that the spring I03 will shift the tailstock center into engagement with a work piece and force the oil out of cylinder 99 into the return channel. the shifting of the footstock valve causes automatic insertion of the tailstock center into the end of the work and automatic startin of the headstock which causes rotation of the work. At the same time the valve 88 connects pressure to the infeed control valve I3, shifting the plunger M to the left as viewed in Figure 5. whereby the port l2 becomes interconnected with port I99.

This results in the admission of pressure to channel I I9 which has a branch connection to port I I I of a start and stop control valve I l2 for the cam actuating piston H3 and a second branch connection to port II4 of the rapid traverse cylinder Therefore 38. The line I I0 is alsoconnected to the cylinder 38 through a parallel branch line connection I I 5 which has a check valve H6 serially arranged therein, the line H5 terminating. in a second port II'I located in the cylinder 38. When the wheel head is in a retracted position the piston 40 covers the port I I4 whereby the first admission of pressure to cylinder 38 must be through the check valve II6 which is set to olier a predetermined resistance to flow whereby the full pump pressure does not enter the cylinder at the beginning of the movement.

This produces a regulated acceleration of the wheel head until it has moved a suflicient distance that the piston 40 uncovers the port II 4 whereby the pressure gradually builds up to full pump pressure and thus a maximum rate of movement of the wheel head.

The fluid in cylinder 39 is forced out to reservoir by movement of the wheel head through a control valve structure carried by the wheel head and comprising a valve sleeve I I8 which is operatively connected to the rack piston 28 by a pin I I9. The sleeve has an internal bore I20 in which is fitted a plunger rod I2I but the plunger rod is threaded at 522 in a fixed part I23 of the wheel head and locked against movement by a lock nut I24. I

The plunger has two spools I25 and I26 separated by an annular groove I21. It should now be apparent that the rack piston 28 and the valve sleeve H8 remain stationary and the rest of the structure moves as a unit relative thereto.

The oil in escaping from the cylinder 39 passes through the passage I28, annular groove I29 and port I30 formed in the sleeve II8 to the annular groove I21 in plunger I2I. The annular groove I21 interconnects the port I36 to port I3I which is drilled in the annular groove I32 of sleeve H8. The annular groove is in constant communication with the port I33 which is the terminus of the channel 68. As the wheel head advances while the piston 28 and the sleeve II8 remain stationary, the spool I26 on the plunger I2I advances to close port I30, thereby trapping the fluid in cylinder 39 which serves to decelerate the wheel head a it reaches the end of its rapid traverse stroke. The exhaust fluid flows through channel 68, interconnected ports 61 and I34 of the start and stop valve 51, and return channel I35 to reservoir 62 through the low pressure relief valve I08.

The channel I I0 which was connected to pressure by valve I3 has a branch connection to port II I of valve II2 as previously mentioned and urges the plunger I36 downwardly as viewed in Figure 5 simultaneously with the rapid traverse movement. This downward movement is retarded, however, by the enlarged piston I31 which operates against the back pressure in line I35. The object of this is to retard the movement of valve plunger I36 until the wheel head has completed its rapid traverse movement, at which time the pressure in channel I ID will rise and thereby shift the plunger I36 faster to connect the pressure port I38 to port I39 and thereby through channel I40 to port MI located in the end of cyl- .inder I42.

The cylinder I42 contains the previously mentioned piston I I3 which actuates the feed rate control cam 45. The piston is connected for operation of the cam in the following manner. Rack teeth I42 are formed longitudinally of the piston and in mesh with pinion I43 for driving the slide I44 which has similarly formed rack teeth I45 engaging the gear I43, Figures 5 and 8.

As viewed in Figure 5, the piston II3'in'm'oving in the direction of arrow II3, causing the slide I44 and cam 45 to move in the direction of arrow SI and the cam face 45, i so inclined as to cause imovement of the follower I45 to the right, thereis connected by annular groove I48 to port I49 and channel I50 which leads to a rate control valve ISI. This valve has a rotatable plunger I52 in which is formed a spiral throttling groove I53 for variably throttling the flow from port I54 to port I55. The port I55 is connected to the return channel I01. The rate valve plunger I52 terminates in a manual control I56 which is located on the front of the machine, as shown in Figure l, and a graduated dial I51 is associated therewith to indicate the rate setting of the throttle valve.

The pinion I43 which transmits motion from the piston II3 to the cam 45 is secured to a shaft I58 and this shaft has keyed thereto a crank arm I59 in the end of which is an adjustable set screw I60 for engaging the end of a trip operated pilot valve plunger I6I which controls the shifting of the cycle reverse valve 19. This plunger has an enlarged central spool I62 and is normally held 'in the position shown by the constant fluid pres sure in chamber I63- which is supplied by a branch channel I64 from channel 68 in which a back pressure exists as determined by the relief valve The crank arm I59 is rotated in a clockwise direction by the pinion I43 simultaneously with the movement of the cam 45 and at the end of the cam stroke it engages the end of the plunger I6I shifting it to the right as viewed in Figure 5. A port I65 which is constantly connected to a source of pressure acts on the enlarged spool I62 to complete the shifting of plunger I6I thereby hydraulically detenting it. The shifting of the plunger connects the port I65 to a port I66 and thereby through channel I61 to the tarry valve I68.

This valve is of the same construction as the rate valve and has a spiral throttling groove I69 for controlling the rate of flow from port I to port I1I. The tarry valve is adjusted by a control knob I12 mounted on the front of the machine as shown in Figure 1 and provided with a dial I13 to indicate the setting thereof. The port IN is connected by a channel I14 to port I located in the left end of the reverse valve 19. The object of the tarry valve is to delay the firing of the reverse valve plunger 80 a suflicient length of time to permit the grinding wheel to clean up the work, that is, to spark out. The pressure at port I 15 must rise to a sufficient degree to overcome the pump pressure which constantly exists in the interior cylinder 84. of the plunger 86 as previously explained.

When this occurs the pressure port SI of valve 19 is connected by annular groove 82-to a port I16 and thereby through channel I11 to port I18 of a fluid operable mechanism for returning the manual control valve and its control lever 54 to a combined reverse and stop position. This :r'n'echanism comprises a pair of telescoping plungers I19 and I80 which are constantly urged apart on which lnterengage the teeth onxa gear I84 which is attached to the valve plunger "0f the valve 51.

Upon admission of pressure to port I18 the telescoping plungers move as a unit, thereby rotating the gear I83 and connected valve in a counterclockwise direction as viewed in Figure 5 and near the end of the stroke the plunger I19 uncovers a port I85 which is connected by channel I86 to an accumulator I81. The accumulator has a spring I88 which is adapted to yield under pressure whereby the plunger actuating fluid is adapted to expand into the accumulator and thereby momentarily reduce its pressure just as the valve reaches the end of its movement, thereby easing the shock on the valve as it reaches a positive stop, limiting its movement.

This rotation of the valve positions the vane 56 midway between the ports 58 and 69 whereby the pressure port 58 now becomes connected to the port 61 so that fluid pressure immediately flows through channel 68 to the rapid traverse piston.

At the same time the port 69 is interconnected to port I34 whereby channel 10 becomes an exhaust line. The spring 15 actin on plunger 14 is of sufficient strength to immediately shift the plunger to the right forcing the fluid through channel 93, valve 88 and resistance 86 to channel 10. This immediately connects channel I II] to exhaust port I93, thereby providing for free ex.- haust of fluid from the rapid traverse motor.

Since th port I30 i closed by the spool I26 the fluid pressure entering the annular groove I32 is forced to go through the passage I89 and check valve I90 to cylinder 39, the check valve causing a pressure drop which starts the wheel head slowly until the spool I26 uncovers the port I30 and opens up a bypass for the fluid around the check valve. The fluid in the other end of the cylinder escapes through port II4 since check valve II6 cannot open and the wheel head will move back at a fast rate until the tapered end I9I of piston 40 throttles the escape of fluid through port H4 and thereby causes deceleration of the wheel head until the piston 40 hits the end of the cylinder 38.

During the rapid return of the wheel head, fluid is continually passing through the resistance 86, lowering the pressure in line 93 to a point at which the headstock switch 95 will open. The spring 90 will then start to move the plunger 89 of the tailstock control valve until the port 91 becomes connected .to the pressure port I00 causing the tailstock center I 02 to be withdrawn from the work.

When the channel H0 is connected to exhaust by valve 13, it reduces the pressure in chamber I II of valve II2 whereby the constant back pressure acting in the cylinder I31 is enabled to shift the plunger I36 upward, thereby connecting the port I39 leading from the upper end of cylinder I42 to exhaust, and port I41 to pressure port I38 whereby actuating fluid will enter the lower end of cylinder I42 and efiect return movement of piston I I3 and connected cam 45.

The cam 45 will effect axial movement of worm 33 against the pressure in cylinder 36 and thereby additional retraction of the wheel head.

At the same time the counterclockwise rotation of the pinion I43 will cause counterclockwise rotation of the crank arm I59 and since constant pressure is now admitted to the cylinder I63 the plunger I6I will be shifted to the left, thereby disconnecting the pressure port I65 from port I66. The latter port becomes connected to port I94 which is connected to the back pressure reservoir line I35 and this maintains the line I61 full of fluid, thereby preventing the admittance of air which might affect the feed rate on the next operation. All the parts have now returned to 1 their starting position.

A brief summary of the sequence of events during an automatic infeed cycle is as follows. The throwing of the lever 54 to its start position connects fluid pressure to the rootstock valve causing the plunger thereof to move at such a rate that the footstock center will engage and pick up a work piece, it being understood that the work will normally be placed upon a suitable work rest of proper height so that the center I02 in moving forward will push the work on to the headstock center and at the same time lift the work sufliciently to clear the work rest. It should be apparent that the work must be properly held between centers before anything else occurs. Having accomplished this, the tailstock center continues its movement and opens port 92 which thereby shifts the infeed control valve plunger and operates the pressure switch 95 to start the work rotating. The infeed control. valve connects pressure to the rapid traverse motor which moves the wheelhead in and at the same time connects pressure to the reversing valve for the feed rate control motor so that as soon as the rapid traverse movement is completed the feeding movement may start.

The feed rate control piston II3 moves the cam 45 at a selected rate as determined by the setting of thecontrol valve I5I and by the time the feeding movement is completed the cam 45 has moved out of engagement with its follower, the worm shaft has engaged the positive stop 44 and the crank arm I59, has tripped the pilot valve IGI. Fluid pressure is now admitted by Way of channel I61 and tarry valve I68 to the reversing valve 19 which eventually shifts to effect return of the control lever 64 to its stop position. This results in port 69 being connected to reservoir and port 61 being connected to pressure whereby the rapid traverse motor immediately starts return movement of the wheel head. Due to the connection of port 69 to reservoir, pressure is immediately relieved in the footstock valve as well as in the infeed control valve and the pressure switch 95 whereby the pressure switch goes off to immediately stop rotation of the work and the infeed control valve plunger 14 shifts to the right to relieve the pressure in valve H2 so that the plunger I36 can shift to connect the pressure port I38 to port I41 and thereby cause return movement of the feed rate piston II3. This produces an additional return movement, in addition to the rapid traverse movement, and the movement of the tailstock valve plunger is timed to be returned when these movements have ceased to withdraw the tailstock center from the work.

In addition to the mechanism for actually effecting the automatic infeed cycle, certain controls and interlocks have been provided whereby this mechanism may be utilized together with, or independent of, the table traversing mechanism. I

The power traversing of the table is controlled by the table start and stop valve which is operated by the lever 24, a reversing valve I95 and a pilot valve I96, Figure 6. The reversing valve I95 has a pressure port I91 to which the pump supply line 59 is connected, and a pair of motor.

ports I98 and I99 which are connected through the table control valve as shown in sections I8 and 20 thereof in Figure 6 to the motor lines 200 and 20I respectively. In other words, the

table start and stop valve has a pair of ports 202 and 203 to which the lines 204 and 205 from ports I98 and I99 are connected, and when.the

valve plunger 23 is rotated clockwise to its start position, port 203 is connected by groove 206 to port 201 and thereby line 20I, and port 202 is connected by groove 208 to port 209 and thereby to line 200.

The reversing valve I has a plunger 2I0 in which is formed a pair of annular grooves 2H and 2I2 for alternately connecting the pressure port to ports I98 and I99 respectively and for simultaneously connecting the remaining port to port 2I3 or 2I4, depending upon the direction of shift of the plunger. These ports are alternately connected to a common return line 2 I5 which leads to a feed rate throttle valve 2I6 by the plunger 2I1 of the ilot valve I96 which also controls the shifting of the reversing valve plunger 2I0.

In other words, the ports 2 I3 and 2I4 are connected by channels 2I8 and 2I9 to ports 220 and 22I of the pilot valve and the annular grooves 222 and 223 in the pilot valve plunger are alternately positioned to connect the ports 220 and 22I to the common exhaust port 224 to which the line 2I5 is connected. The pilot valve also has a pair of pressure ports 225 and 226 whereby as the plunger shifts and immediately after it passes through its center position it will connect a shot of pressure to the exhausting side of the table motor to assist in stopping it before the reversing valve is shifted.

The pilot valve has a pressure port 221 which is flanked by a pair of ports 228 and 229 which are connected by channels 230 and 23I to ports 232 and 233 located in opposite ends of the reversing valve housing I95. The plunger 2I1 is provided with an enlarged spool 234 which is movable relative to the pressure port 221 so that after passing the port a force component sufficient to complete the shifting of the plunger 2I1 is produced. This acts in the nature of a hydraulic detenting mechanism. A crank arm 235 is operatively connected'to the plunger for shifting the same, the crank arm being keyed to the end of a trip shaft 236 which carries a trip lever 231 on the upper end thereof as shown in Figure 1 for actuation by trip dogs 238 and 239 carried by the table I3.

It is desirable that a delayed reversing action be effected in the table and to that. end each of the channels 230 and 23I have delay valves 240 and MI serlally arranged therein. These valves operate to restrict the now to the reversing valve but any return flow is by-passed around these valves by means or check valves 242 and 243 which are directionally connected to open under a return iiow from the reversing valve, but which will close upon a now to the reversing valve and thereby force the fluid to pass through the delay valves. The ports 228 and 229 are alternately connected to exhaust ports 244 and 245 which are connected to the return line I01.

In addition to enecting shifting of the reversing V valve, the pilot valve also functions to effect actuation of a power operable pick feed mechanism, indicated generally by the reference numeral 246 in Figure 5 of the drawings. This mechanism comprises a reciprocable piston 241 which is slidably mounted in a cylinder 248.

The opposite ends of the cylinder are connected by channels 249' and 250 to a reversing valve 25L The reversing valve has a plunger 252, the shifting of which is controlled by the table pilot valve I96 by connecting the end ports 253 and "254 to the pilot valve ports 228 and 229 by channels 255 and 256. Each of the channels 255 and 256'has a pair of parallel connected check valves 251 and 258 but oppositely directed whereby one valve *an armQSO-thatcarries a' pawl 28L The pawl 28lha's-a heel-282 which ls'a'dapted to engage an closes and the other opens upon a flow to the 10 reversing valve, and vice versa upon a flow from the reversing valve. The channels 255 and 256 also conduct pressure for shifting the piston 241. With the parts in the position shown it will be noted that the pressure port 221 of the pilot valve is connected'to channel 255 and this channel has branch connections to ports 259 and 269 of the reversing valve. With the plunger 252 in the position shown the port 260 is connected by annular groove 26l to port 262 and thereby to channel 259 whereby the fluid pressure'from port.

plunger 210 of this valve in the position shown the port 268 is'conriec'ted by an annular groove 21| to port 212 and channel 249 to the cylinder 248. The channel 249 has a resistance 213 serially arranged therein to retard operation of the piston 241 sufliciently to prevent hammering.

It will now be apparent that upon shifting of the pilot valve, fluid pressure is immediately admitted to cylinder 248, causing actuation of the piston 241 and thereby operation of the pickfeed mechanism, the check valve'25'l functioning to retard the admittance of pressure to port 254 and thereby the shifting of the plunger '252' until the piston 241 has completed its movement. When this occurs the p1un-ger'252 completes its shift-' ing movement, closing port 263 but opening port 264. This port then becomes'connected byway of annular groove 214 to port 215 and thereby to channel 259. This admits fluid pressure to the other end of cylinder 248 and returns the piston 241 to its starting position. Therefore upon a single shifting movement of the pilot valve plunger the piston 241 is caused to execute a complete reciprocation.

The same eifect is produced when the pilot valve plunger 2 I 1 is shifted in the other direction, only the pressure is connected this time to channel 255 and the plunger 252 is in position to connect port 259 to port 216 whereby the fluid will again flow to channel 261 and from' there on through the same path to the cylinder 248 shifting the pist0n 241 to the left. While this is going on, pressure will be slowly leaking through the check valve 251 to shift the plunger '252 toward the right and when the piston 241 reaclresth'e end of its stroke the pressurewill rise to complete the shifting movement. This will close the 'port'259 and will interconnect port 269 to port 262 and rotation on-a shaft 219. The gea'ris integral'with' abutment 283 upon counterclockwise rotation of the arrn-280 and thus serves to'withdraw the pawl'from engagement with the periphery of a ratchet wheel 284.

Upon clockwise rotation of the -arm='280 the pawl 28l will drop into engagement with the ratchet wheel 284 and effect rotation of the shaft 219. Theratchet wheel 284 has a gear'285 formed integral therewith and this gear intermeshes with a gear 286 which is supported on a shaft 281 and is adapted to be connected to'the shaft for rotation of the gearing 41 and thereby of the worm 33.

The gear 286 carries means for stopping operation of the pick-feed mechanism which cornprises a button-288 which is so positioned that it will engage the pointed end of the plunger 210 and shift'the same to the left as viewed in Figure 5. The plunger'carries an enlarged spool 289 i which is movable relative to a pressure port 29!! whereby after the spool passes the pressure port the'admittance of pressure to the other side of the spool will completethe shifting movement in the direction in which the plunger happens to be moving. This functions as a hydraulic detent mechanism to hold the plunger in either one of its two positions. When the plunger'210 is shifted to theleft it closes the port 268 and interconnects the port 212 with a'return port 29!.

The result of this is to stop the hydraulic impulses in line 261 from being communicated to the piston 241 and at the same time to connect the channel 249 to the back pressure exhaust line whichmaintains sufficient fluid in channel 249 to prevent the entrance of air into the system.

It will beapparent that it is impossible to reset the plunger 210 manually and therefore hydraulic means'are provided'for this purpose after the 0 gear 286 has been rotated to remove the button 288' from the path of the plunger.

nism comprises a resetvalve 292 which has a This mechapressure port 293,'an exhaust port 294 and a "third port 295 which is connected by channel 296 'to'port'291 located in' the left end of the valve The plunger 296 is held in the position shown by a spring'299 and a shoulder 300 formed on "the end of the plunger for engaging the end of thesleeve 30!. "This positions the valve to conl'n'ect the port 295 to the exhaust port 294 whereby the plunger 210 may be shifted to the left without undue "resistance. When the plunger 298 is depressed, the 'p'ort'2 95 is connected to the pressure port 293 which thereby'admits fluid pressure to -the port 291L's'hiftirig the plunger216 to the right. It will be understood that'after the pick feed mechanism has stopped operating that the table to both ends of the'cylinder 15. thereby equaliz- "mg the pressure on both ends of the piston and prises'a hand wheel 302 which is fixed to the end of a shaft'303 that carries a gear 304. The shaft "303 is adapted to be axially'mo'ved in its bearings 305 and 36B whereby thegeai 306 may be engaged with a gear 301 for slow operation of the table 13 or may be interengaged with internal gear teeth 338 of a gear 303 to effect fast movement of the table. A spring pressed detent 310 is provided for holding the shaft in either one of its two positions. When the gear 364 is intermeshed with the gear 301 the drive is then through a train comprising a gear 31 l integral with the gear 33'1', gear 339, pinion 312, gear 313 and gear 314 which is integral therewith, and idler 315 which is interposed between the gear 314 and a rack 31% which is attached to the underside of the table.

When the shaft 3133 is shifted to the right, the gear 3341 engages the internal gear 308 in the manner of a clutch whereby the gear 309 is rotated directly by the shaft 303. Since the gear 312 is integrally connected to the gear 309 the drive is then through gear 313, pinion 314 and idler M to the rack 313. The gears 313 and 314 are capable of axial movement but are normally held in the position shown by a spring 3 I l which is interposed between them and extends into bores 318 and 319 formed in the opposing faces thereof. A spacing rod 323 is mounted within the spring to limit the movement of the gear 313. The purpose of this construction is to shift gears 313 and 31 d to the left and thereby disengage the gear 313 from the gear 315 so that it is impossible to attempt to effect manual operation of the table while it is being power driven, or on the other hand to prevent rotation of the hand wheel 392 during power actuation of the table.

The gear 3 it has an elongated hub 32! by which it is journaled in the bearing 322 and the hub has a reduced portion 323 which slides in a bearing 32 5 and also extends into a chamber 325 to act as a piston for shifting the two gears, the gear 3M being pinned to the reduced portion 323. The chamber 325 is connected by a channel 326 to port 321 of the table start and stop control valve. When this valve is in the stop position in which it is shown the port 321 is connected to an exhaust port 323 which thereby relieves the pressure in chamber 325 but when the valve is rotated in a clockwise direction the pressure port 329 is connected to the port 321 and thereby to the chamber 325. Thus, there is an interlock to disconnect the manual actuating mechanism from the work table during power actuation thereof.

There is an additional interlock on the table start and stop control valve which prevents the starting of the table until the wheelhead has been moved into engagement with the positive stop 44. This is a precautionary measure to insure that all sizing of the work is done with the wheelhead in engagement with the same stop. To this end the valve plunger 23 is provided with a locking notch 330 which is adapted to be engaged by a spring pressed locking plunger 331 which when in position will prevent clockwise rotation of the plunger 23 to a starting position. The locking plunger is slidably mounted in a housing 332 and is normally held in position by a spring 333 located between an enlargement 334 on the plunger and the end of the housing. The enlargement 334 being greater in diameter than the locking portion 331, serves to provide a dilferential area 335 which may serve as a piston to effect withdrawal of the pin 331 against the resistance of the spring 333. To this end the housing is provided with a port 336 to which is connected a channel 33?, that is, a branch of the channel 140 that supplies the infeed piston 113 as shown in Figure '5. Therefore, when the infeed piston 113 is being actuated under pressure the locking pin 331 is withdrawn so that the start and stop valve may be operated. The purpose of this is that during an infeed grinding operationit may be desirable to effect a small reciprocation or oscillation of the work with respect to the grinding wheel, especially in cases where the axial length of the sur-- face being ground is a little greater than the width of the grinding wheel.

For conventional reciprocating grinding opera tions the infeed rate valve 152 is opened wide and the tarry valve 168 is closed with the result that when the infeed start lever 53 is thrown to the start position the rapid traverse piston and the infeed piston 113 move quickly to their end positions without delay whereby the positive stop is immediately engaged to insure a positive positioning of the grinding wheel.

, It should be noted that this operation also causes engagement of the tailstock center as well as the closing of the headstock switch which produces rotation of the work and since the interlock pin 331 has been withdrawn the operator may now throw the lever 24 to its start position to cause reciprocation of the table. The wheel 15 is now rotated to move the gringing wheel into engagement with the work and then the pick feed mechanism is set into operation t complete the grinding operation.

It should be noted that'the positive stop serves as the ultimate limit of movement of the grinding wheel during an infeed grinding operation, but during a reciprocating cycle it serves merely as a positive abutment from which to start the infeeding of the grinding wheel.

When a reciprocating cycle has been completed the operator may move the grinding wheel out of engagement with the work and simultaneously stop the table by a single movement of the table control lever 24. This is accomplished by moving the lever, not only t the stop position but to a third position previously referred to as the dash and dot line 26 shown in Figure 1. The effect of this is to rotate the valve plunger 23 a sufficiently additional distance in a counterclockwise direction to connect a pressure port 338 to port 339 in section 21 of the valve and thereby to channel 340which leads to port 115 of the reversing valve '19 shown in Figure 5. The shifting of this valve as previously explained in connection with the infeeding cycle, connects pressure to the channel Ill which results in the throwing of the infeed cycle control lever 54 to its stop position, thus causing immediate retraction of the grinding wheel.

When the wheel head is returned in this manner it can only be brought back in again by operation of the infeed control level 54. It is to be noted that any time this lever is utilized to advance the wheel head and the feed rate throttle valve 152 is set for a feed rate, that the throttle valve may be by-passed to obtain a fast rate of movement by merely throwing the lever beyond its normal infeed position. When this is done a drilled passage 341 in the valve plunger interconnects port 332 which is branch connected to line with exhaust groove 343 and port 61 t the return line 135. This provides an open passage to reservoir, thereby momentarily eliminating the effect of the feed rate valve.

In addition to adjusting the feed rate by the throttle valve 152, major changes may be made in the rate'by changing'the angularity of the cam without changing the setting of the throttle valve. Angularity changes are made more partie cularly, however, for changing the length of the feed movement.

The means for changing the angularity of the cam is shown more particularly in Figures 7, 8 and 9. The cam 45 is mounted in a U-shaped holder 344 as shown in Figure 8. The holder bears against two rollers 345. and 346 and is 'operatively connected to the rack I44 by a pin 341. The pin carries a block 348 which fits in a slot 349 formed in the back of the cam 45 for transmitting motion to the cam. The cam is backed up by two stops 350 and 35l and held against thestops by the hydraulically actuated follower roller I45. The stop 35l is keyed at 352 to an adjusting shaft 353.

The various sides of the hexagon are, different distances from the center beginning with the side 354 which is closest to center and which effects the smallest angularity of the cam. The distances of the sides 355, 356, 351, 358 and 359 from the center increase by the same increment in the order named.

The shaft 353 has a knurled operating knob 360 whereby the stop 35! may be rotatably adjusted to any one of six positions to obtain different lengths of infeed for thesame length of movement of the cam.

A stop screw 36! limits the movement in one direction which is the feeding movement whereby the cam always stops in the same position and which is such that the cam is just out of engagement with the follower roller so that the positive stop 44 shown in Figure 2' is always effective.

The length of cam stroke is determined by an adjustable stop 362 shown in Figure 5 and having a threaded connection with the shaft 363 which is actuated through bevel gears 364 and 3.65 from the hand wheel 366 mounted on the end of shaft 361 splined in gear 365. The shaft 363 has a splined connection with gear 364 so that a piston 368 On the end of the shaft sliding in cylinder 369 may act as a dashpot to cushion the shock. The cylinder is connected to pressure at all times.

Referring to Figure 4, the length of the infeed increments effected by the pick feed mechanism may be varied by adjusting the stop 310 longitudinally of the cylinder 248. The stop has an angular end 31! engaging the angular surface 312 on the threaded member 313. A threaded adjusting shaft 314 interengages therewith and has an operating knob 315.

The shaft 314 has a gear reduction connection 316 to a graduated dial 311. Thus, by rotating the knob 315, the stop is adjusted and the dial rotated simultaneously.

There has thus been provided an improved actuating and control mechanism for a grinding machine which greatly improves the operation thereof, and which is highly selective whereby the various types of grinding operations may be carried out automatically.

What is claimed is:

1. In a grinding machine having a fixedsupport, a work support and a grinding wheel suptransmitting movement to the grinding wheel support, said connection including a rack piston slidably mounted in the grinding wheel support, means to apply fluid pressure to said piston to effect rapid movement of the grinding wheel support, and means to move said cam to effect a feeding movement of the grinding wheel support.

2. In a grinding machine having a fixed support, a work table and a wheelhead mounted on said support for relative movement in angularly related directions, a headstock and a tailstock carried by the table including centers for supporting work for relative rotation with respect to the grinding wheel carried by the wheel head. the combination of control means for governing movement of the wheel head including a rapid traverse piston and a feed piston,'a source of fluid pressure, a start and stop valve adapted said source of pressure to the rapid traverse pising valve for connecting fluid pressure for shiftfeed piston for lmpartmg a slow rate of movegaging thev worm and operatively connected for when moved to a starting position to connect ton, fluid operable means for retracting the tailstock center, a tailstock control valve normally in a position to connect said source of pressure to said fluid operable means, means in the starting said tailstock control valve to release the presslue on said tailstock center, resilient means for advancing the tailstock center when pressure released, an infeed control valve fluid actuated upon shifting of the tailstock control valv for connecting pressure to the rapid traverse piston, a reversing valve for the feed piston adapted to be shifted by said pressure to initiate operation of the feed piston, and means operable by the merit to the wheel head.

3. In a grinding machine having a work supporting table and a grinding wheel slide, the combination of a table motor, a rapid traverse motor and a feed motor for the wheel head, a source of fluid supply for all of said motors, a first valve for connecting said source to the rapid traverse motor to effect quick advance of the wheel head, additional valve means automatically operable to connect fluid to said feed motor to effect additional advance of the wheel head, means to regulate the rate of movement of said feed motor to a slow rate for infeed grinding purposes, or at a rapid rate for traverse grinding purposes, a third valve for connecting said source of pressure to the table motor, means normally locking said third valve, and fluid operable means controlled by said additional valve means for releasing said locking means after the wheel head has completed its rapid traverse movement.

4. In a grinding machine having a fixed support, a work table slidably mounted on the support, and a wheel head slidably mounted on the support for movement toward and from the table, the combination of means for advancing and retracting the wheel head relative to the table including a cylinder formed in the wheel head, a piston slidably mounted in the cylinder, means in the fixed support for holding the piston against movement whereby the admission of pressure to either end of the cylinder will cause movement of the wheel head, a valve member slidably mounted in the wheel head and operatively connected to said piston, portings in the wheel head controlled by said valv member during advance of the wheel head to decelerate the wheel head, and bypass [check valve connections paralleling said portings to initiate return movement at a prescribed accelerated rate.

5. In a grinding machine having a fixed support, a work table slidably mounted thereon, and a wheel head supported for movement toward and from 'the work table, the combination of means for shifting the wheel head including a worm mounted in the fixed support for rotation and axial movement, means operatively connecting the worm to the wheel head, means for holding the worm against axial movement including a cam mounted at one end of the worm and a hydraulic piston mounted at the other end of the worm for holding the same against the cam, means to move the cam at a prescribed rate to eflect axial shifting of the worm and thereby infeeding of the Wheel head, and a fixed positive stop for ultimately limiting movement of the worm independent of the cam.

6. In a grinding machine having a fixed support, a work table slidably mounted thereon and a wheel head supported for movement toward and from the work table, the combination of means for shifting the wheel head including a worm mounted in the fixed support for rotation and axial movement, means operatively connecting the Worm to the Wheel head, means for holding the worm against axial movement including a cam mounted at one end of the worm and a hydraulic piston mounted at the other end of the worm for holding the same against the cam, means to move the cam at a prescribed rate to efiect axial shifting of the worm and thereby infeeding of the wheel head, fluid operable means for shifting said cam, and a throttle valve for said fluid operable means to determine the rate of cam movement.

7. In a grinding machine having :a fixed support, a work table slidably mounted thereon, and a wheel head supported for movement toward and from the Work table, the combination of means for shifting the Wheel head including a worm mounted in the fixed support for rotation and axial movement, means operatively connecting the worm to the wheel head, means for holding the worm against axial movement including a cam at one end and a hydraulic piston at the other end of the worm, means to move the cam at a prescribed rate to effect axial shifting of the worm and thereby infeeding of the wheel head, a fixed positive stop for ultimately limiting movement of the worm independent of the cam, and means to rotate said Worm to change the relative position of the wheel head with respect to the actuating mechanism and thereby change the zone of movement relative to the work.

8. In a grinding machine having a bed, a table and a grinding wheel support slidably mounted on the bed, and a grinding wheel rotatably mounted on the grinding wheel support, the combination of means for advancing and retracting the wheel relative to the table for either infeed or traverse grinding operations including a fluid operable motor, supply and return lines for the motor having a reversing valve'interposed therein, fluid operable means for shifting said valve including a trip operated pilot valve, a delay valve interposed between the pilot valve and reversing valve for delaying the shifting of the latter, and means to close said delay valve for preventing operation of the reversing valve when the motor is utilized for advancing the wheel head for traverse grinding operations.

9. In a grinding machine having a bed, a Work support mounted on the bed for traverse movement, and a grinding wheel support, the combination of means for advancing the grinding wheel support to and from the Work support including a fiuid operable motor, a fluid control circuit for said motor including a cycle control valve, manually operable means for positioning said valve to initiate a cycle, a pilot valve, a cycle reversing valve and a motor reversing valve arranged in said circuit, means operable by the motor for shifting said pilot valve to effect shifting of the cycle reverse valve, and means responsive to shifting of the cycle reverse valve for shifting the motor reversing valve to reverse the actuation of said motor.

10. In a grinding machine having a Work supporting table and a grinding wheel support, the combination of a control circuit for controlling relative movement between the supports including a table operated pilot valve, a table reversing valve, a pick feed mechanism for the grinding wheel support including a reversing valve therefor, means controlled by the pilot valve to efiect shifting of said table reversing valve, said pick feed mechanism including a fluid operable piston, a cylinder containing said piston, a pair of channels leading to opposite ends of the cylinder, a blocking valve in one of said channels, and means trip operable by the pick feed mechanism for shifting said blocking valve to stop operation of the pick feed mechanism.

11. In a grinding machine having a work supporting table and a grindingwheel support, the combination of a control circuit for controlling relative movement between the supports, comprising a pick feed mechanism for the grinding wheel support including a reversing valve therefor, said pick feed mechanism including a fluid operable piston, a cylinder containing said piston, a pair of channels leading to opposite ends of the cylinder, a blocking valve in one of said channels, means trip operable by the pick feed mechanism for shifting said blocking valve to stop operation of the pick feed mechanism, a hydraulic detent for holding said blocking valve in a stop position and fluid operable means including a control valve for resetting said blocking valve in running position.

12. In a machine tool having relatively movable work and tool supports, the combination of means for effecting a relative idling movement between said supports in a direction to bring the tool on the tool support into engagement with the work on the work support including a constant stroke piston and cylinder mechanism, a manually operable control valve for connecting pressure to said mechanism to cause said movement, a second piston operatively connected for shifting said mechanism as a unit for causing additional movement of the support, a control cam opposing movement by said second piston and a fluid operable control circuit for feeding said cam at a constant predetermined rateto control the rate of movement imparted by said second piston.

13. In a machine tool having a work support and a tool support, the combination of an inIeeding mechanism for causing a relative inieeding movement between said supports including a constant stroke piston and cylinder mechanism, a manually operable control valve for connecting pressure thereto, a second piston for imparting additional movement at a feed rate including a reversing valve therefor normally held in one position, a cycle control valve remotely controlled by said manually operated control valve for connecting pressure to shift said reversing valve, and pilot control means trip operated by the secondnamed piston to cause power actuation of said erse mechanism, and means for subsequently and automatically connecting power to the feed mechanism and simultaneously to said interlocking means to effect release of the interlock whereby the work support may be traversed during the feeding movement of the grinding wheel support. a

'15. In a machine tool having movable work and tool supports, power operable means for moving one of said supports and other power operable means for moving the other of said supports,

thecombination with a control for starting and stopping the first-named-power operable means,

of an interlock normally positionable for holding the control in its stop position, a second-control member shiftable for connecting power to said other power operable means and'simultaneously efiecting withdrawal of said interlock whereby onesupport may-be traversed during movement of the "other support.

16. In a grinding machine having a work support, a grinding wheel support and power operable means including a control lever for starting and stopping traversing of the work support, the combination with an interlocking member normally positioned to hold the control lever in a stop position, of a first fluid operable means for moving the grinding wheel support at a fast rate,

a second fluid operable means for controlling movement of the grinding wheel support at a feed rate, means for connecting fluid pressure to said first-named fluid operable means, a'control valve responsive to the fluid pressure connected to said first-named fluid operable means for connecting fluid pressure to said second-named fluid operable means, a fluid pressure actuator for releasing said interlocking member, said control valve also connecting fluid pressure for releasing said interlock.

17. In an infeed mechanism for the grinding wheel support of a grinding machine having a pressure operated member operatively connected to the support for producing an infeeding movement thereof, the combination of means for controlling the rate of operation of said movement including a slidable feed control cam, a cam follower. urged by said fluid pressure operated member into engagement withsaid cam normal to its direction of movement thereof, a pivotal support for one end of said cam, an adjustable stop member engaging the other end of said cam for varying the angularity thereof about its pivot and thereby the length of feeding movement effected for a given movement of the cam, and control power operable means for shifting the cam mechanism transversely to the axis of said follower.

JACOB DECKER.

ALBERT D. C. STUCKEY.

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