US2241634A - Automatic infeed mechanism for grinding machines - Google Patents

Description

J. DECKER May 13, 1941.

AUTOMATIC INFEED MECHANISM FOR GRINDING MACHINES 4 Sheets-Sheet 1 Filed April 12, 1940 INVENTOR. JYcofi Die m? ATTORNEY.

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AUTOMATIC INFEED. MECHANISM FOR GRINDING MACHINES Filed April 12, 1940 4 Sheets-Sheet 2 INVENTOR. JF/toa flfcmw WWW A TTORNEY.

J. DECKER May 13, 1941.

Filed April 12, 1940 4 Sheets-Sheet 4 HH HI HIHH H H F .0 H H hHl F RV M5 0 No sh; .8 a R km l a 6% l a F raw: O m AT .w \NM m m5 M A. Y u. .v 8 M0 bb. L Q? F R? 5: Mm. 3 Vk a Q. W Q9 MIN v Mn 3% M\\ 4... 0 ,1 QR 4w mm v Q H ,1 z \\\\M\F M an n Patented May 13, 1941 is? i ATENT .iKITOMATIG INFEEE ems Jacob Decker, Cincinnati, Ohio, assignor to cm cinnati Grinders Incorporated, Cincinnati, Ohio, a corporation of Ohio Application April 12, 1940, Serial No. 329,333

12 Claim.

This invention relates to grinding machines and more particularly to automatic cycle control mechanism therefor.

nism which is simple and rugged in construction and positive in operation.

A further object of this invention is to provide an improved mechanical mechanism for infeeding a grinding wheel support which is powered hydraulically whereby the positive features of mechanical operation and the advantages hydraulic control may be obtained in a single structure.

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.

Referring to the drawings inwhich lifie reference numerals indicate like or similar parts:

Figure 1 is an elevational view partly in section of a machine embodying the principles of this invention. 7

Figure 2 is an enlarged detail section on. the line 2-4 of Figure 1.

Figure 3 is a section on the line 8-3 of Figure 2.

Figure 4 is a section on the line Q4 of Figure 3.

Figure 5 is a diagrammatic view of the hydraulic control circuit.

Referring to Figure 1 of the drawings the reference numeral Ill indicates in, general the bed of the machine, and the reference numeral H in- .dicates the work support which is slidably supported by the flat and. V guides l2 and 63 respectively formed on the bed. A grinding wheel H is rotatably mounted on a grinding wheel support or slide I5 which is relatively movable with respect to a sub-support l6 toward and from the work support II. The grinding wheel It may be powered in a conventional manner by an electric motor I! carried by the support l5.

This invention deals with an-hnproved automatic infeed cycle control mechanism. for effecting plunge cut grinding operations on surfaces whose axial length is less than the width of the grinding wheel face. In view of this, no mechanism has been shown for traversing the table since such mechanism forms no part of the present invention but it will be understood that any suitable traversing mechanism may be employed for that purpose.

The final driving elements of the inieeding mechanism of this invention consist of a rack it which, as shown in Figure 1 is integral with. the slide l5. and a pinion it supported in engagement with the rack by a shaft 28, the shaft passing centrally through the support it whereby the subsupport i6 may be rotatably adjusted about the axis of the shaft 2|! to vary the plane of rotation of the grinding wheel.

Referring to Figure 2, the shaft 2% has a gear 2! keyedthereto in a position to intermesh with rack teeth 22 formed on the side of an elongated piston 23 slidably mounted in a cylinder A set screw 25 engages a longitudinally extending groove 2e formed in the piston for preventing rotation thereof and maintaining the rack teeth being mounted in a housing 29.

in proper mesh with the gear 25. The piston it constitutes a fluid operable member for shifting the grinding wheel support at a rapid traverse rate as well as at a feed rate, there being addi tional mechanism provided for controlling the rate of feed as will be described hereeitsr.

This additional. mechanism includes a worm wheel 21 and an intermeshing worm fit, the worm The worm is has integral reduced bearing portions 3% and hi projecting axially from opposite ends thereof, which are supported by anti-friction needle been ings 32 in sleeves 33 and 3d. The sleeves arse held against rotation by set screws 35 winch engage longitudinally extending slots 33$ out in the periphery of the sleeves. Although the bearing portions rotate relative to the sleeves, washers 31 are provided on the bearing portions so that the worm andsleeves move as a unit in the bore 38 of the housing. This bore is provided with end stops 39 and 40 which engage the ends of the sleeves to define the amount of social movement of the worm.

Since the worm. wheel 27 is keyed to the shaft 20 for movement thereby it will be apparent that these and stops define the amount of movement that can be imparted to the wheel slide by the piston 23.

The end stop 39 determines the return position of the wheel slide which is also the starting p0- sition for an automatic inieed cycle. This position may be varied, however, relative to the worm by rotating the worm through the shaft ii which has a telescoping spline connection with the shaft H which, as shown in Figure l, is provided with a gear 42 which intermeshes with a pinion 48 mounted on the end of a manually'rotatable shaft 44. This shaft extends to the front of the machine and is provided with a hand wheel 45 as well as a pick feed wheel 48. By rotating the hand wheel 45, the worm wheel 21 may be rotated without changing the axial position of the worm whereby the grinding wheel slide and the piston 28 are caused to take up a new return position. Therefore, the cylinder 24 is made sufilciently long to accommodate all the positions which the grinding wheel slide might have. -When the wheel slide is in a return position hydraulic pressure is always connected to the left end of cylinder 24 whereby the worm wheel 28 is held against positive stop 88, thereby preventing axial movement of the worm during rotation thereof to effect movement of the wheel slide. It will thus be apparent that the hand wheel 45 changes the zone of movement of the piston 23.

An automatic cycle is initiated by moving the valve plunger 41 of the cycle control valve 48 to the left as viewed in Figure 5. This valve has two pressure ports 48 and 58 which are connected by a common channel 5i to a pump 52 which has an intake 58 through which fluid is drawn from a reservoir 54. The channel 5i has a branch 55 leading to pressure port 58 of the feed control valve 51.

In the stop position the valve plunger 58 is to the right whereby the annular groove 58 interconnects port 58 to port 58' and thereby to channel 88 which leads to port 8I located in the left hand end of the cycle control valve 48. It will thus be "apparent that fluid pressure entering opposite ends of the valve casing 48 through ports 58 and-5I acts on opposite ends of the valve plunger but since the area 82 of the left end of the plunger is larger than the area 83 there is a differential which holds the plunger in its right hand position defined by the detent 84. Thus, when the operator throws the starting lever 85 he must overcome this differential pressure in order to throw the valve plunger in a running position. when this has been accomplished, the port 48 is connected by the annular groove 88 to port 81 whereby fluid flows through branch channels 88 and 88 which are connected through a common channel 18 to port The channel 88 terminates in a port 1| located in the right hand end of the cylinder 24 causing movement of piston 23 to the left whereby the wheel slide will advance at a relatively rapid rate. At the sametime the port 12 located in the left end of cylinder 24 is connected to reservoir through channel 18, interconnected ports 14 and 15 of the cycle control valve 48 and channel 18 which leads to the reservoir 54.

The branch channel 88 terminates in ports 11 and 18 of a main pilot valve 18 and port 88 of an auxiliary pilot valve 8i. The main pilot valve 18 has a valve plunger 82 which is held in its right hand position as shown in Figure 5 by a spring 83. In this position an annular groove 84 formed in the plunger 82 interconnects port 11 with port 85 whereby the pressure fluid continues through channel 86 to port 81 located in the right hand end of the auxiliary pilot valve 8i. This causes a shiftin'gof the auxiliary pilot valve plunger 88 to the left. against the compression of a spring 88 whereby the pressure port 88 is interconnected by the annular groove 88 to port 8i causing fluid to now through channel 82 to port 88 located in the right hand end of the feed control valve housing 51. By" this time the piston 23 has completed the rapid traverse movement of the wheel slide and the worm 28 has been shifted axially by rotation of the worm wheel 21 until the-end of the bearing portion 8i abuts the end of a follower 84 of a cam 85. This positively stops the rapid movement of the wheel slide. 1

- The cam 85, as shown in Figure 3, is keyed to the upper end of a rotatable shaft 88 which is supported for rotation. in a. housing 81. The

cam 85 has a receding peripheral surface 88' whereby upon rotation in a counterclockwise direction it will permit further advance of the worm 28 toward the right under the pressure of the fluid in the right hand end of cylinder 24 acting This piston is slidably mounted in a cylinder I I82 which has ports I88 and I84 located at opposite ends thereof. The port I88 is connected by a channel I85 to port I88 of the feed control valve 51. An adjustable throttle valve I81 is serially arranged'in this channel for varying the feed rate. A check valve I88 is connected in parallel across the throttle valve, and so positioned as to stop flow to'the feed piston while permitting return flow therefrom.

when the plunger 58 of the feed control valve 51 is shifted'to the left by fluid pressure entering port 88 the port I88 is connected by the annular groove I88 to pressure port 58. This will cause fluid to enter the feed cylinder I 82 at a rate de- .termined by the setting of the throttle valve I81 and cause rotation of the cam 88 to produce a slow rate of advancing movement of the grinding wheel slide. The receding surface 88 is of such contour thatby the time the piston I8I- has reached the end of its cylinder it willhave moved out of engagement with the follower 84 due to 'the fact that in the meantime the worm 28 has hit the positive stop 48. It will thus be apparent that although the cam acts to control the feed rate it does not act as a positive stop for determining the final infeed position of the grinding wheel slide. I

It will be obvious that during rotation of the cam 85, its supporting shaft 88 to which it is keyed will also be rotated, and this shaft is provided with a pinion portion I I8 which is engaged engage the end of the main pilot valve plunger 82.

This will shift the plunger against the compression of spring 83 until the annular groove to areservoir port III. The result of this is that the fluid which shifted the feed control .valve plunger is now exhausted to reservoir, and

pump pressure is connected through port Ill and an adjustable throttle or delay valve II8 position.

to port m of valve housing 51 tending to um:

the plunger 58 to theright. It will thus be obvious that while the plunger 58 is slowly moving to the right, that the grinding wheel slide has advanced the full length of its movement and is gradually sparking out.

t The length of time that the grinding wheel will be finishing the surface will depend upon the setting ofthe delay valve III. When the 'valve plunger 58 has completedv substantially one -half of its movement, or in other words as soonas the valve spool Ill cracks the port fluid pressure will flow to port 59' and branch 'IIS to the auxiliary cylinder I20 located in the left hand end of the valve housing 51 so that pressure will act on the end I2I of theplunger 53 more effectively and the further the plunger 53 moves to the' right the faster will the fluid pressurerun into the chamberl20 whereby the plunger 58 becomes self-actuating tocomplete the last half of its shifting movement.

.When the plunger 58 has returned, the pressure fluid now being admitted to channel 60 through port 59 will enter port SI of the starting valve and shift plunger 41 to the right:

The fluid entering the left end of the housing .33 will continue through port I22 after it has been uncovered and channel I23 to port I of the feed cylinder I02. Shifting of the plunger 41 will also reverse the connections to cylinder 24, port 1I now being connected to reservoir versely varying the length of the rapid traverse stroke and the feed stroke, it being remembered through port I24 and port 12 being connected to pressure through the interconnectionof ports l3 and 14. Thus, the piston 23 and the feed piston IIJI will rapidly return to their starting positions.

Since the amount of excess stock on work coming to a grinding machine hasa wide variation, provision is made for varying thelength of the feed stroke so that the-machine may be oper'ated efliciently'at all times. scribed, the feed controlcam has 'a receding surface which means that the radius of the periphery gradually reduces from the radial line I26,

I which is coincident with the axis of the follower when the feed piston. IOI is in its maximum return position, to the radial line I26 which is coincident with the axis of the follower when the feed piston is in its maximum advanced Therefore, if the feed piston is not to return to its maximum return position but some distance short of that position, the length of the particular cam radius which is coincident with the axis of the follower will be less than the radius I25, which means that the rapid traverse movement of the wheel slide will be greater, and therefore the grinding wheel will approach the work a greater distance before its rate of movement is changed to a feeding rate. Means are, therefore, provided for varying the return position of the feed piston thereby of the cam 98 whereby the length of the rapid traverse movement-may be increased and the length of the feed movement correspondingly permitted v .40 As previously de- King an intermeshing worm and worm gear,'

, able means forrotating said worm to adj IIII and that the sum of these two distances must always be equal to the total movement permitted by the positive stops 33 and 40 for the worm 28, is moreparticularly shown in Figure 4.

This mechanism comprising a rack plunger I21 which is slidably guided in a bore I23 of the housing 9.1 and in intermeshing relation with I30 connects this threaded stop through gearing I I3I, to a manually adjustable dial I32 located on the front of the machine as shown in Figure 1. This dial may be suitably graduated to indicate the length of feed movement which should approximate the amount of excess stock to be removed from awork piece. Thus, by means oi. this mechanism the starting position of the cam may be varied and by such variation the relative lengths of the rapid movement and the feed movement are inversely changed.

Attention is invited to the fact that the starting valve 48 is in effect a reversing valve for the rapid traverse piston and a control valve for one end of the feed piston. In other words, it controls the admission of fluid pressure to effect the return stroke of the feed piston, but since the port I22 is closed during the advance of the feed piston a check valve I33 is so connected to channels I23 and 60 as to by-pass exhaust fluid around the closed port. An additional check valve I34 is provided in parallel with the throttle ord'elay valve-I I6 to permit exhaust of fluid to reservoir through port II 1 of the feed control valve when the plunger 58 is shifted to the left to start thetfeeding movement.

There has thus been provided an improved infeed control mechanism for a grinding machine which is simple and rugged in construction, easy to adjust, and efiicient in operation.

What is claimed is:

1. In a. grinding machine having a work .support anda grinding wheel support, the combination of an infeeding mechanism therefor includmotion transmitting means connecting the worm gear to the movable support, a manually,operuist the support through the worm gear, a fluid operable piston for shifting the movable support at a rapid 7 rate whereby said worm is shifted axially by reaction of the worm gear thereon, a-cam for limiting the extent of axial movement of said worm, and means to actuate said cam to produce additional-movement of the support by the piston at a feeding rate under control of said cam.

decreased in accordance with the stock removal requirements of a given work piece.

The total fall in the arcuate periphery of the cam between the radii I25 and I26 represents, of course, the maximum length of feeding move- .ment, and has been determined'to take care of the maximum requirements ofthe machine, and the means referred to above have been provided for reducing the fall in accordance with particular requirements. The mechanism for in- 2. In a grinding machine having a work support and a grinding wheel support, the combina tion of means for effecting relative movement between the supports including a power operable member, motion transmitting means connecting the memberfor. movementcfone of said supports at a rapid rate, a feed control cam, a part shiftable jointly with the support into abutting engagement with said cam for stopping said rapid movement, means to actuate said cam to permit further movement of said. part and thereby of said support at a feed rate, a positive stop, said cam having a receding profile of such extent that the cam will eventually move out of engagement with saidpart whereby said positive stop will determine the final infeed position, of said support.

3. In a grinding machine having a work support and a grinding wheel support, the combination of means for effecting a relative infe'eding movement of the grinding wheel support including a first power operable member for effecting a rapid advance movement oi. said support, means for positively stopping said advance movement including a cam. and a part movable with said support and engageable with said cam, a second power operable member for actuating said cam, said cam having a receding surface to permit further advance of said support at a feed rate, and a final positive stop effective independently of said cam for determining the final infeed position of said support.

d. In a grinding machine having a work support and a grinding wheel support, the combination of an infeeding mechanism including power operable means for effecting a rapid advance oi the grinding wheel support, means subsequently operable for producing a feeding movement including an inieed control cam, a cam i'ollower movable with the support into engagement with said cam, a fluid operable piston for actuating the cam to produce a feeding movement, means trip operable by the piston for reversing its direction 01' movement, and adjustable means ior determining the extent of the return movement of the piston and thereby the starting position of said cam.

5. In a grinding machine having a work support and a grinding wheel support. the combination of an infeeding mechanism including power operable means for effecting a rapid advance oi the grinding wheel support, means subsequently operable for producing a feeding movement including an inteed control cam, a cam follower, movable with the support for engaging said cam and stopping the rapid movement, a iiuid operable piston for actuating the-cam to produce the feeding movement, means trip operable by the piston for reversing its direction of movement, and adjustable means for determining the extent of said return movement and thereby the starting position of said cam, said adjustable means including a threaded stop and a plunger movable in synchronism with the piston for engagement with said stop.

6. In a grinding machine having a work support and a grinding wheel support, the combination of means for moving one of said supports toward and from the other including a worm wheel and a rotatable axially movable worm, a housing supporting said worm and having positive stops at each end for determining the extent of axial movement of said worm and thereby the extent of movement of said support for either rotation or axial shifting of the Worm, power operable means for effecting part of said, axial movement at a rapid rate, and additional means for causing the rest of said movement to tnlse place at a feed rate. r

7. In a grinding machine having a work support and a grinding wheel support, the combination of a hydraulic control circuit for efiecting a relative infeeding movement between said supports including a rapid traverse piston, a feed piston, a source of pressure, a starting valve for connecting fluid pressure to said rapid traverse piston, a feed control valve, a pilot valve and an auxiliary pilot valve, means operable by the starting valve for connecting fluid pressure to said pilot valves, means in the main pilot valve to efiect hydraulic shifting of the auxiliary pilot valve and thereby eiIect a connection of shifting pressure to the feed control valve, means operable by the feed control valve for connecting pressure to said feed piston, and means operable by the feed piston for shifting said main pilot valve to cause return movement of both of said pistons.

8. In a-grinding machine having a work support and a grinding wheel support and means intervening said supports permitting a relative movement in a direction toward and from each other, of means for eflecting said relative movement including a first actuating piston having an extended axial movement, a second member having a limited axial movement, means inter connecting said axially movable elements, whereby the member having limited movement determines the extent of movement oi the piston, and means ifor varying the phase relationship 01 said parts whereby the potential zone of axial movement of the piston is varied, and additional means interconnecting the piston and one of the supports for efiecting movement of the support in accordance with and through the selected zone of activity of the piston.

9. In a grinding machine having a work support and a grinding wheel support and means intervening said supports permitting a relative movement in a direction toward and from each other, of means for effecting said relative movement including a. first actuating piston having an extended axial movement, a second member having a. limited axial movement, means interconnecting said axially movable elements, whereby the member having limited movement determines the extent of movement of the piston, and means for varying the phase relationship of said parts whereby the potential zone of axial movement or the piston is varied, additional means interconnecting the piston and one o! the supports for effecting movement of the support in accordance with and through the selected zone of activity or the piston, a shittable abutment having a portion projecting to engage the axially movable member, and an additional piston mechanism reacting on the abutment for variably determining the positioning thereof and thus the rate of movement of the shiftable support.

10. In a grinding machine having a work support and a grinding wheel support and means intervening said supports permitting a relative movement in a direction toward and from each other, 0! means for effecting said relative movement including a first actuating piston having an extended axial movement, a second member having a limited axial movement, means interconnecting said axially movable elements, whereby the member having limited movement determines the extent of movement of the piston, and means for varying the phase relationship oi! said parts whereby the potential zone of axial movement of the piston is varied, additional means interconnecting the piston and one of the supports for eflecting movement of the support in accordance with and through the selected zone of activity of the piston, a shiftable abutment having a portion projecting to engage the axially movable member, an additional piston mechanism reacting on the abutment tor variably determining tional means for variably determining the limit of movement of the second piston and thus the ultimate position of the abutment controlled theicby.

11. In a machine of the character described, the combination with a pair of relatively adjustable supports, of means for effecting relative rapid traverse feed movements thereof including a drive shaft, a hydraulic motor for effecting rotation of .the shaft, a driving connection from the shaft to the movable support, and means for determining theextent and rate of rotation of the shaft including a worm wheel carried by the shaft, a worm housing in fixed relation to one of the supports, a worm rotatably and translatably mounted in the housing, means for rotating the worm to effect through the worm gear rotary adjustment of the shaft and coupled hydraulic motor and thus the position of the movable support, a first means for limiting the axial movement orthe worm, a variable positionable abutment proiectable into the path of movement of the worm, and means including a variable speed hydraulic motor coupled with the abutment for determination of the positioning thereof, whereby said latter motor by reaction on the worm determines the rate of feeding movement of the shiftable support. a

of the supports, a worm rotatably and trans latably mounted in the housing, means for rotating the worm to effect through the worm gear rotary adjustment of the shaft and coupled hydraulic motor and thus the position of the movable support, a first means for limiting the axial movement of the worm, a variable positionable abutment projectable into the path of movement of the worm, means including a variable speed hydraulic motor coupled with the abutment for determination of the positioning thereof, whereby' said latter motor by reaction on the worm determines the rate of feeding movement of the shiftable support, and means for variably limiting the extent of movement of the abutment controlling motor and thus the ultimate positionin of the worm and support. a Y

JACOB DECKER.

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