US2313479A - Feed mechanism - Google Patents

Description

March 9, 1943. R. E. PRICE ET AL.

FEED MECHANISM Original Filed Feb. 28, 1940 5 Sheets-Sheet l Envenfor RALPH E. PRICE 8 HAROLD E. anLslqsn m/Lauzuv A. HQLL'ENQEEEN Gttorneg March 9, 1943.

1 R. E. PRICE ETAL FEED MECHANISM Original Filed Feb. 28, 1940 5 She e ts-Sheet 2 3nventor March 9, 1943.

R. E. PRICE ET AL 2,313,479

FEED MECHANISM Original Filed Feb. 28, 1940 5 Sheets-Sheet 5 EflLP/V 5. PRICE N HAaaLB E- EALSIGEIE bu MIA-BURN a. HOLLE/VQJEEEN attorney March 9, 1943.

R. E. PRICE ET AL 2,313,479

FEED MECHANISM Original Filed Feb. 28, 1940 5 Sheets-Sheet 4 l'mncnfor Patented Mar. 9, 1943 FEED MECHANISM Ralph E. Price, Highfield, Md., and Harold E.

Balsiger and Milburn A. Hollengreen, Waynesboro, Pa., assignors to Landis Tool Company,

Waynesboro, Pa.

Original application Febru ary 28, 1940, Serial No.

321,310. Divided and this application February 6, 1941, Serial No.

8 Claims.

Our invention relates to feed mechanisms for machine tools, particularly grinding machines, and is a division of application Serial No. 321,310 filed February 28, 1940.

An object of our invention is to provide a feed mechanism whereby the tool may be returned repeatedly to the same position within extremely close limits and thus hold a given size without the use of a size control mechanism.

A further object is to provide a feed mechanism which includes a system of gearing wherein all the back lash is taken up in one direction.

A further object is to provide a feed mechanism wherein a worm wheel and feed screw function alternately as a rack and pinion.

Figure 1 is a front elevation of e grinding machine.

Figure 2 is a plan view partly in section to show the feed mechanism.

Figure 3 is a sectional end elevation of the wheel support on the line 3-3 of Figure 2.

Figure 4 is a front elevation of the wheel support partly in section on line 4-4 of Figure 3.

Figure 5 is a sectional view of the relief valve and the feed reversing valve.

Figure 6 is a hydraulic diagram.

In previous feed mechanisms, the manual feed and thepower feed have been substantially independent mechanisms in that the operation of one had no effect on the other. Each mechanism had a certain amount of lost motion iniit and each time the wheel was fed in the sum of the lost motions was different because there was no means for insuring that all the lost motion in each mechanism would be taken up for each cycle.

In our invention there is no movement of the wheel support by the rapid feed piston until back lash is taken up between feed screw 45 and worm wheel 44, between worm wheel 42 and the worm gear on shaft 40, and the thrust between shaft 40 and its bearings and the twist in vertical shaft 43. If the feed movement is effected by the hand wheel, the same amount of back lash must be taken up. If effected by the slow feed piston rotating screw shaft 45, the same amount of back lash must be taken up. If the feed is adjusted by turning the handwheel only enough to take up a portion of the back lash, the change in feed will correspond to the movement of the handwheel.

By means of this construction it is possible to feed the wheel repeatedly to the same position and thus hold work to size within close limits.

In the drawings are shown mechanisms both manual and power operated for moving the wheel support 25 toward and away from a work piece. 65

There are in effect three of these mechanisms: (1) the manual mechanism actuated by handwheel 28; (2) a rapid feed mechanism; (3) a continuous grinding feed mechanism.

The manual means for feeding wheel 26 includes a handwheel 28. Said handwheel is connected thru a system of gears to a shaft 40. Said handwheel is rotatably mounted on a bushing 62 on shaft 40. A ring gear 63 is mounted on a flanged portion of handwheel 28. Said ring gear fits on said handwheel tightly enough to rotate therewith unless held against rotation by some means such as locking pin 68. A second ring gear 64 is keyed to shaft 40. A differential gear consisting of two pinions 65 and 66 is rotatably mounted in a recess in said handwheel. Said gear is supported on a shaft 61 in said handwheel and parallel to the axis thereof. Pinion 65 meshes with ring gear 63 and pinion 66 with ring gear 64. When handwheel 28 is turned with locking pin 68 in back position as shown, the drive from handwheel 28 to shaft 40 is direct, with sand handwheel, ring gear 63, differential pinions 65 and 66, ring gear 64, and shaft 40 turning as a unit. When ring gear 63 is locked by pin 68, the drive from handwheel 28 to shaft 40 is a 10 to 1 ratio. As the handwheel 28 and differential pinions 65 and 66 rotate about the handwheel axis, said pinions are caused to rotate about their own axis by the engagement of pinion 65 with ring gear 63. Pinion 66 thus causes rotation of ring gear 64 and shaft 40 at the rate of one revolution to ten revolutions of handwheel 28. Obviously this ratio of 10 to 1 may be varied to suit any particular case. With this fine feed arrangement in combination with the other features of the feed mechanism to be described later, the operator may accurately and easily effect any change in size directly by setting the hand feed and without measuring a work piece after each of a series of test cuts.

On one end of shaft 40 is cut a worm 4|. Said worm engages a worm gear 42 which is secured to a vertical shaft 43. Both of said shafts are supported in bearings in the wheel support 25. Said handwheel shaft is mounted on three ball bears, one of which supports the worm end thereof. At the lower end of said shaft 43 is secured another worm gear 44. Said worm gear engages a worm or feed screw shaft 45 rotatably and slidably supported in the bed l0. Said screw may be moved rapidly endwise by piston 46 in cylinder 41, or it may be rotated by rack 50 in contact with pinion 5| on said screw shaft, or it may remain stationary while worm gear 44 turned by handwheel 28 moves relative thereto carrying with it the wheel support 25. In either of the first two cases the worm gear 44 becomes in effect a nut because it is held against rotation by worm gear 42 and. the worm on shaft 48. During the rapid feed, the screw shaft 45. worm gear 44, and wheel support 25, are moved-bodily. The backlash between screw 45 and worm gear 44, between worm gear 42 and its worm and the torsional strain in shaft 43 are taken up during the rapid feed movement. When screw shaft 45 is rotated by piston 18 for a grinding feed, gear 44 and wheel support 25 are moved relative thereto while said screw remains motionless axially. The backlash described above may be taken up either in response to rotation of screw. 45 or to rotation of handwheel 28. At the end of the grinding feed, the feeding movement stops and grinding stops as soon as the wheel sparks out. Piston 46 is adjustably mounted on the threaded end 48 of shaft 45 and is prevented from turning thereon by a split nut 48 which has a clamping screw 68 extending beyond said nut into an opening 6| in piston 46.

In addition to rack 58 and pinion the grinding feed mechanism includes a piston 18 integral with said rack. Said piston is mounted for axial movement in cylinder 1|. ment of piston 10, and hence the amount of grinding feed, is determined by the setting of an adjustable positive stop 13 in the head of cylinder 1|. The amount of adjustment of said stop may be determined by a knob 15 graduated in terms of wheel movement. A threaded insert 14 in stop 13 enables the operator to set knob 15 accurately. For example, with piston 18 at the extreme left hand position and knob 15 set at zero, insert 14 may be adjusted until it engages the head of piston 18. In this position there would be no grinding feed because piston 18 could not be returned to a position from which it could rotate screw shaft 45 to effect such a feed. Attention is called to the fact that feed screw 45 and worm gear 44 are common to all three mechanisms.

The meansfor supplying fluid under pressure The extent of move-- of fluid supplied at such speeds does not exceed to cylinder 41 consists of a valve 88 in a housing 8|, said housing is enclosed at both ends by end plates 82 and 83. Fluid under pressure from any suitable source directed thru line 3 may be applied at the right hand end of said valve 88 to shift same to direct other fluid under pressure thru lines 84 and 85 to the head end of cylinder 41. Exhaust pressure or a spring 16 may be applied at the opposite end of said valve. Fluid connections from valve 88 to cylinder 41 include two lines to each end thereof. Lines 84 and 85 lead to the head end of cylinder 41 and lines 86 and 81 lead to the rod end thereof. Check valves 88 and 88 permit the passage of fluid under pressure to cylinder 41 thru lines 85 and. 81 but the exhaust fluid returning thru said lines must pass thru throttle valves 88 and 8|, respectively. Lines 84 and 86, and their corresponding ports in cylinder 41, are located between lines 85 and 81. A piston 46 moves from one end of its stroke to another, the first part of the stroke is open to unrestricted exhaust thru one of the lines 84 or 86, but as the piston 46 continues it cuts off this exhaust line and thereafter the only exhaust is thru lines 85 or 81 depending on the direction of movement, and the throttle valve in each of these lines restricts the flow of exhaust fluid and thus cushions the stopping of the wheel support.

A line 413 from the head end of cylinder 1| to the left hand end of valve housing 8| permits exthe capacity of the bleeder sufllciently to maintain the necessary minimum pressure on the feed piston to keep it moving. With our improved arrangement, valve 88 closes off line 413 durin feeding so that full pressure is exerted against piston 18. Fluid under pressure is directed by any suitable means thru line I I3 to the right hand end of valve 88 shifting same to the left against spring 16. Said valve then directs fluid from pump I32 and line 488 thru lines 84 and 85 to the head end of cylinder 41.

Operation Piston 46 in cylinder 41 and wheel support 25 are moved rapidly to position the grinding wheel 26 close to the surface of the piece to be ground. Fluid is discharged from cylinder 41 thru lines 86 and 81. Line 86 is unrestricted so that piston 46 moves at top speed. After piston 46 has closed line 86 said fluid can exhaust only thru line 81, and throttle valve 8| therein checks the speed of piston 46 and provides a cushioned movement against a positive stop. After passing thru valve 8|, exhaust fluid enters line 86 from which it passes thru valve 88 to exhaust passage I361). On the withdrawal movement, throttle valve 88 in line 85 effects the cushioning. The rapid feed movement is limited by screw 45 engaging a stop Assuming that the grinding operation is a plunge cut, fluid under pressure is directed thru line 412 to the head end of cylinder 1|. Piston 18 in said cylinder moves rack 58 in mesh with pinion 5| on feed screw 45. Said screw rotates in mesh with worm gear 44 on the end of vertical shaft 43. Said screw being rotated against a positive stop can move no further axially, but the rotating movement serves to insure a good bearing against said stop. This is true also of the engagement between screw 45 and gear 44. Shaft 43 and gear 44 are held against rotation by worm gear 42 at the other end of the shaft in mesh with a worm on shaft 48 of handwheel 28. Thus gear 44 and with it the entire wheel support assembly must move relative to screw 45 in response to rotation thereof. when valve 88 is shifted from left to right, fluid under pressure in line 86 which eflects withdrawal of the rapid feed mechanism also enters the rod end of cylinder 1| to reset piston 18 and the grinding feed mechanism. Valve 88 also opens an additional exhaust from the head end of cylinder 1| thru lines 412 and 413 thru said valve 88 to exhaust lines |38a and I38 thus permitting a quick reset of the grinding feed mechanism.

In order to control the amount of stock removed during a grinding cycle, the stroke length of piston 18 and hence of the grinding feed may be adjustably limited by'stop screw 13. The exact amount may be set by graduated knob 15.

To reset the feed mechanism for a change in size, the operator uses the graduations on the handwheel 28 by which he makes a direct setting from one size to another. For example if it is desired to increase or decrease a given size by .010" the change will be counted out on the graduations and the position of the wheel surface will be shifted .005". Thereafter, for each grinding operation the wheel will move in to the same position'and once it has sparked out, it will grind no further.

Lost motion in the feed mechanism exists between worm gear 44 and screw 45, between worm gear 42 and its worm, and the torsional strain in vertical shaft 43. This lost motion is the same for every feed movement and turning handwheel 28 merely changes the position of the grinding wheel at which the lost motion is all taken up. This is true regardless of the direction of movement of the handwlieel or the position of the wheel base. This lost motion is all taken up during the rapid feed movement before the grinding feed begins. Any adjustment of the feed by handwheel 28 takes said lost motion into account and the change in size is that indicated by the movement of the handwheel. The rapid feed movement ends when screw 45 engages a positive stop I! so that when said screw is rotated for a grinding feed it cannot move axially relative to worm gear 44 before said gear begins to move carrying the wheel support with it. Since all lost motion is taken up said gear cannot rotate in response 'to rotation of said screw. Therefore, it becomes in effect a nut and moves bodily along with the wheel base and grinding wheel relative to screw 45.

We claim:

1. In a grinding machine, a bed, a work support, and a grinding wheel support slidably mounted on said bed, a grinding wheel rotatably mounted on said wheel support, mechanism for effecting a relative transverse movement between said supports including a feed screw in said bed, a gear on said wheel support, the teeth on said gear being in mesh with said feed screw, mechanism for moving said screw bodily endwise for positioning said grinding wheel for a grinding operation, mechanism for rotating said screw whereby to cause a slow feeding movement of said gear and said grinding wheel, and mechanism for rotating said gear whereby to adjust the position of said'wheel support relative to said feed screw.

2. In a grinding machine, a work support, a grinding wheel support, a grinding wheel rotatably mounted thereon, mechanism for eifecting a relative transverse movement between said supports including a feed screw, a worm wheel having teeth in operative engagement with threads on said screw, means on said wheel support for rotating said worm wheel to adjust said wheel support to move relative to said screw, and means for rotating said screw to move said worm wheel and said wheel support at a feeding rate.

3. A feed mechanism for a grinding machine including a grinding wheel support movable toward and from operative position, a feed screw, a worm wheel engaging said screw, power means for effecting a rapid endwise movement thereof, power means for rotating said screw for a slow feed movement, a manual feed mechanism including a shaft having a worm gear thereon, a handwheel for rotating said shaft, a worm wheel engaging said worm, and a shaft joining said worm wheels, endwise movement of said screw being effective to rotate said first worm wheel and thus take up backlash in the mechanism.

4. In a grinding machine, a grinding wheel support movable toward and from operative position, power means including a feed shaft for effecting said movement, manual means including a shaft perpendicular to said feed shaft and having a worm wheel thereon in operative engagement with said feed shaft for effecting said movement, and connections between said power means and said manual means including a second worm wheel on said perpendicular shaft whereby all the back lash in both mechanisms is taken up before the wheel support begins to move so that operation of either of said power means or said manual means will take up all the back lash in both systems.

5. In a grinding machine, a grinding wheel support movable toward and from operative position, power means for effecting said movement, manual means for effecting said movement, and connections between said power means and said manual means including a feed screw connected to said power means, a gear on said wheel support connected to said manual means and having teeth in operative engagement with the threads of said screw so that all the back lash in both mechanisms is taken up before the wheel support begins to move whereby operation of either of said power means or said manual means will take up all the back lash in both systems.

6. In a grinding machine, a bed, a work support, a grinding wheel support, a grinding wheel rotatably mounted thereon, mechanism for effecting a relative transverse movement between said supports including a feed screw on said bed, a gear member, manually actuated mechanism on said wheel support for rotating said gear, said gear being in engagement with said screw, and being responsive to axial movement thereof to take up the back lash in said manually actuated mechanism;

7. In a metal working machine, a movable slide, a hydraulic motor for moving said slide including a .piston and cylinder, a supply of fluid under pressure for said motor, a line at one end of said cylinder for permitting the escape of air therefrom, and means for preventing flow of fluid thru said line during a power stroke of said piston.

8. In a metal working machine, a movable slide, a hydraulic motor for moving said slide including a piston and cylinder, a supply of fluid under pressure for said motor, a bleeder line at one end of said cylinder for permitting the escape of air therefrom, and means for preventing flow o1 fluid thru said line when the speed of the carriage is controlled by flow of fluid under pressure toward or from that end of said cylinder.

RALPH E. PRICE. HAROLD E. BALSIGER. MILBURN A. HOILENGREEN.

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