US2571610A

US2571610A - Hydraulic feed mechanism

Info

Publication number: US2571610A
Application number: US46280A
Authority: US
Inventors: Ralph E Price
Original assignee: Landis Tool Co
Current assignee: Landis Tool Co
Priority date: 1948-08-26
Filing date: 1948-08-26
Publication date: 1951-10-16
Anticipated expiration: 1968-10-16

Description

Oct. 16, 1951 R. E. PRICE HYDRAULIC FEED MECHANISM 2 SHEETS -SHEET 1 Filed Aug. 26, 1948 llmcntor RA-LPH E. PRICE Gttomeg Oct. 16, 195] PR|cE 2,571,610

HYDRAULIC FEED MECHANISM Filed Aug. 26, 1948 2 SHEETSSHEET 2 inventor EAL PH E. Pklcz' (Ittomeg Patented Oct. 16, 1951 UNITED STAT HYDRAULIC FEED MECHANISM Ralph E. Price, Highfield, Md., assignor to Landis Tool Company, Waynesboro, Pa.

Application August 26, 1948, Serial No. 46,280

17 Claims. 1 This invention relates to feed mechanisms for grinding machines, particularly centerless grinders.

The primary object of this invention is to provide an automatic feed cycle. By this is meant a cycle which will be repeated as often as desired without attention from the operator.

A further object is to provide a control mechanism which will function to initiate the cycle as well as cause a dwell at each end of the feed movement.

A further object is to provide a work ejecting mechanism operable in connection with said feed mechanism.

Figure 1 is perspective showing the structure of the feed mechanism.

Figure 2 shows a hydraulic diagram for a feed mechanism and a work ejecting mechanism for a centerless grinder.

Numeral Ill indicates a grinding wheel base slidably mounted on a bed II for movement toward or from operative position. A grinding wheel I2 is rotatably mounted in said base. Said movement may be effected manually or by power.

The manual feeding means consists of a hand wheel [5 for driving through suitable gearing to a worm gear IS on an axially slidable shaft I]. Said worm gear engages a worm wheel I8 on feedscrew shaft I9. All this mechanism is carried in wheel base Ill.

The feedscrew I9 is in operative engagement with a nut 20 in bed II.

Rotation of hand wheel I5 causes rotation of worm l6, worm wheel l8, and feedscrew I9 in nut 20, thus causing feedscrew to move relative to the nut and carrying the wheel base [0 with it.

The power means for moving said wheel base consists of a piston 25 at the opposite end of shaft H from hand wheel I5. Said piston i slidably mounted in a cylinder 26. The stroke of said piston and hence the feed movement of the wheel support In may be adjusted by means of adjustablestop 21.

Fluid under pressure may be introduced alternately to opposite ends of said cylinder as will be described more in detail later.

Movement of piston 25 in response to the introduction of fluid under pressure into cylinder 25 results in an endwise movement of shaft I1 and worm [6. Under these circumstances, worm I6 acts as a rack and thus causes rotation of worm wheel I8 and, hence, feedscrew l9.

While the feed mechanism disclosed herein is applicable to grinding machines of many types, I prefer to illustrate it as applied to a centerless grinder. Accordingly, the diagram Figure 2 in:

cludes a control wheel 30 peripherally opposed to grinding wheel I2. The method .of driving the grinding wheel at the conventional speed and the control wheel at a much slower speed is well known and need not be shown here.

A work piece 35 is supported between the peripheral surfaces of the grinding and control wheels on a work rest 36.

Fluid under pressure is directed alternately through lines and 4| to opposite ends of cylinder 26 to move grinding wheel I2 toward and from operative position. Said fluid under pressure is supplied by a pump 50 through line 5| to a reversing pilot valve 52. Valve 52 directs fluid alternately to opposite ends of a cycle control valve 60 and a reversing valve 10.

Valve 52 is connected through rod 53 to one end of a lever 54. Said lever is pivoted at an intermediate point 55. The other end is in the form of a yoke having spaced opposing adjusting screws 56 and 51. Between said screws is a dog member 80 attached to timer piston 8|. Each end of said valve has an axial bore 82R and 821. and an intersecting radial bore 83R and 831., the function of which will be discussed later.

Pilot valve 52 receives fluid under pressure from pump 50 through line 5| and directs it alternately through lines TI and I2 to opposite end of reversing valve I0. It also directs said fluid alternately through lines BI and 62 to opposite ends of valve Bil.

Reversing valve I0 receives fluid from pump 50 through line EI and in the position shown is directing said fluid through line 40 to the head end of cylinder 26. Exhaust fluid from the opposite end of cylinder 26 passes through line 4| to valve In which directs it to one of the exhaust ports of said valve. When valve 1!] is shifted to the left, fluid from line 5| passes through line M to the right end of cylinder 26 and shifts piston 25 to the left. Exhaust fluid from the left end of the cylinder may pass freely through line 28, check valve 29,

lines

40 and 42 to valve I9 and the left end exhaust passage of said valve. This permits a rapid movement of wheel base II! to place grinding wheel I2 in grinding position. When piston 25 closes off line 28, the only outlet is through line 40 and throttle valve 43 to valve 10, and the left-hand exhaust port. Throttle valve 43 may be set to provide a suitable grinding feed.

Valve While valve I0 directs fluid under pressure to actuate feed piston 25 to the right for backing ofi' wheel I2, valve 60 in the right-hand position shown directs fluid under pressure through line 63 to shift timing piston 8| in cylinder 84 to the right. Said valve receives its supply of fluid from line through line 58. A selector valve 59 in line 58 serves to render valve 55 inoperative so far as the actuation of timing piston 8| is concerned. In one position the fluid under pressure is supplied to valve 60, and in the other position of valve 59 the portion of line 58 between valve 60 and valve 59 is connected with exhaust through valve 59. In this position of valve 59, reversing pilot valve 52 must be actuated manually.

Said piston 8| has a dog member 80 operable between screws 56 and 5! in reversing lever 54. As piston 8| moves to the right, exhaust fluid first passes through line 65 to valve 69 and the left exhaust port therein. As said piston closes line 55, exhaust fluid must by-pass through throttle valve 66, which is set to delay the actuation of reversing lever 54 for an interval suitable for loading a work piece into the machine. Piston 8| has axial passages at each end indicated as 82R and 821. respectively. Said passages connect with radial passages indicated as 8311 and'831. respectively.

The period during which movement of piston 5| is controlled by Valve 66 provides time'for backing ofi grinding wheel I2, removing a finished work piece and placing an unground work piece in the machine. As soon as paSsage 83R comes into line with line .65, exhaust fluid from the righthand end of cylinder 84 may pass freely throu h line 55 and valve 60 to the left end exhaust port. Piston .8! then moves quickly to the end of its stroke and dog 89 engages screw 5'! to shift lever 54 and valve 52 to the left. For a continuous cycle, screw 5'! is adjusted so that dog 86 engages it just after passage 83R comes into line with line 65. If it is desired to have the wheel base l0 stop in the inoperative position, screw 51 may be backed off so that dog 85 does not engage it at the end of the movement of piston 3|. When screw 51 is adjusted in this manner, the wheel base I0 will reverse automatically at the end of the grinding operation; but it will stop in the back position and remain" there until the operator shifts lever 54 to the left.

Assume that valve 59 and screw 51 are adjusted for a complete automatic cycle. When pilot valve 52 is shifted to the left, valves 50 and are also shifted to the left. Valve '10 directs fluid through line 4| to the right-hand end of cylinder'26 and piston moves to the left, turning feed-screw 9 at a rapid rate until piston 25 cuts off line 28 through which exhaust fluid may pass freely to check valve 29, line 42, line 40 and the left end exhaust line from valve l8. Thereafter, exhaust fluid from the left end of cylinder 26 is passed through line 40 and throttle valve 43 which determines the rate of movement of piston 25 during the grinding operation. From valve 13 fluid passes through another portion of line 40 to valve 10 which directs it to the left exhaust port of said valve.

Exhaust fluid in line 40 also acts on the left end of valve 90 to shift it to the right against spring 9|. Check valve 29 is held in closed position by a spring, not shown, slightly heavier than spring 9| so as to assure suflicient pressure toactuate valve 8|]. Valve 95 is held in this position by exhaust pressure during the entire feeding stroke. F

At the end of the feeding stroke, piston 25 comes to rest against adjustable stop 21. In the absence of movement of piston 25, exhaust pressure in line 40 disappears and spring 9| returns valve 90 to the left-hand position.

In the left-hand position of valve 60 fluid under pressure from line 58 is directed through line I00 to valve 90. So long as valve is in the righthand position, the fluid in line I00 can move no further. At the end of the feeding stroke, valve 90 returns to the left-hand position, connects line I00 with line |Ei| leading to the right-hand end of timing cylinder 84 and starting the timing movement of piston 8|. 'Thus, the timing period begins not with the movement of piston 25, but after the piston reaches the end of its stroke and the feeding movement of the grinding wheel is stopped. Timing piston 8|, therefore, times only the spark out period. The duration of this period is determined by throttle valve I02 through which exhaust fluid from the left end of cylinder 84 and line 63 must pass to reach line 64, which is connected through valve Bl] with the left end exhaust port of said valve. A description of the quick initial and final movements of piston 8| has been omitted here, since it is identical with that described in connection with the movement of this piston in the opposite direction.

Work ejector The ejecting mechanism isshown for the purpose of illustration as a cylinder |0 having slidably mounted therein a piston A piston rod H2 on said piston'exten'ds from the cylinder into the space between the grinding wheel l2 and control wheel 35. Said piston may be actuated by fluid under pressure at the left end of said cylinder to move said piston and piston rod to the right against the action of spring '||3. When so moved, rod H2 pushes work piece 35 out of the grinding throat. "Piston III is actuated in'timed relation with the movement of wheel base ID toward and from operative position. This timed relation is effected by hydraulic connection between cylinder 26 and a pair of valves H5 and H5. These valves are shifted from one position to another hydraulically. However, they control a supply of air under pressure for the operation of piston I. The supply of air under pressure enters valve I I5 throughlin'e' I25 from which it is directed through line I25 to valve H6. Valve H6 connects line 126 with line I21 leading to cylinder H). The only time air from line |25 can reach cylinder H0 is with valve I I5 in the right-hand position as shown and valve H6 in the left-hand position or opposite to that shown.

During the feeding stroke of piston 25, fluid under pressure is directed from valve 10, line 4| to the right end of cylinder 26. The fluid under pressure from line 4| also passes through line I20 to the right end of valve I I5 and through throttle valve |2| to the right end of valve I I6. Valve I5 is shifted to the left position immediately and cuts off the supply of air from line I25 through line I'Zi; to valve Hi. The movement of valve 1 I6 is delayed due to the setting of throttle valve I2 I, sothat the air is sure to be shut off before said valve reaches the left-hand position in which it connects the air supply of line |26'with line 121, leading to ejector cylinder Ill. It is necessary to delay the action of valve H6 so that it does not move simultaneously with valve H5; or even ahead of it, and thus connect said ejector cylinder with the air supply before it has been cut of! by valve I5. Thus, out of time operation of the ejector is prevented. 1

After a work piece has been ground and piston 25 moves from left to right to withdraw the grinding wheel'from grinding position, said piston uncovers line I30 leading to the left-hand end of valves H5 and H6. Valve H5 moves immediately to the right and connects air line I25 with line I26. Valve I I6 moves more slowly than valve H5 because of throttle valve I2I through which the exhaust fluid from valve H6 must pass. Thus, before valve H6 has an opportunity to break the connection between line I25 and I21, ejector piston III and rod H2 have been moved to the right and work piece 35 is ejected. Piston II I is held in the right-hand position until valve IIB reaches its right-hand position, connecting line I21 with exhaust port I28. Spring H3 then shifts piston I I I and rod I I2 to the left in which position rod H2 serves as a locating means for the next work piece.

I claim:

1. In a machine tool, a hydraulic system including a motor for shifting a machine element, a supply of fluid under pressure for actuating said motor, a reversing mechanism for determining the direction of movement of said motor, including a pilot valve and a reversing valve, an actuating mechanism for determining the interval during which said motor remains stationary at either end of its movement, including, a motor for actuating the pilot valve and a reversing valve also actuated by said pilot valve for directing fluid under pressure alternately to opposite ends of said pilot valve operating motor.

2. In a machine tool, a hydraulic system including a motor for shifting a machine element, a supply of fluid under pressure for actuating said motor, a reversing mechanism for determining the direction of movement of said motor, including a pilot valve and a reversing valve, an actuating mechanism for' determining the interval during which said motor remains stationary at either end of its movement, including a motor for actuating the pilot valveand a second reversing valve also actuated by said pilot valve for directing fluid under pressure alternately to opposite ends of said pilot valve operating motor, and means for cutting off the supply of fluid to said second reversing valve whereby to prevent operation of said timing mechanism.

3. In a hydraulic system, a motor for shifting a machine element, a supply of fluid under pressure for actuating said motor, a reversing mechanism for determining direction of movement of said motor, a timing mechanism for determining the interval during which the motor is stationary at either end of its movement, a timing valve operated by said reversing mechanism for actuating said timing mechanism and a valve between said timing valve and one end of said timing mechanism operable at the end of said motor movement in one direction for initiating operation of said timing mechanism.

4. In a machine tool, a hydraulic system including a motor for shifting a machine element, a supply of fluid under pressure for actuating said motor, a reversing mechanismv for determining the direction of movement of said motor, a timing mechanism for determining the interval during which said motor remains stationary at either end of its movement, a timing valve for directing fluid to actuate said timing mechanism, and a pressure operated valve between said timing valve and said timing mechanism for preventing operation of said timing mechanism until said motor has moved to a predetermined position.

5. In a machine tool, a hydraulic system, a motor for shifting a machine element, a supply of fluid under pressure for actuating said motor, a reversing mechanism for determining the direction of movement of said motor, a timing mechanism for determining the interval during which said motor remains stationary at either end of its movement, a timing valve for directing fluid to actuate said timing mechanism, and a pressure operated valve between said timing valve and said timing mechanism and responsive to movement of said motor for determining the starting time of said timing mechanism.

6. In a machine tool, a hydraulic system including a motor for shifting a machine element, a supply of fluid under pressure for actuating said motor, a reversing mechanism for determining the direction of movement of said motor, including a pilot valve and a reversing valve, an actuating mechanism for determining the interval during which said motor remains stationary at either end of its movement, including a motor for actuating the pilot valve and a reversing valve also actuated by said pilot valve for directing fluid under pressure alternately through opposite ends of said pilot valve operating motor, and a valve actuated by exhaust fluid from said first motor during the feeding movement for preventing operation of said pilot valve actuating motor until the end of said feeding movement.

7. In a hydraulic system, a motor for shifting a machine element, a supply of fluid under pressure for actuating said motor, a reversing mechanism for determining direction of movement of said motor, a timing mechanism for determining the interval during which the motor is stationary at either end of its movement, a timing valve operated by said reversing mechanism for actuating said timing mechanism, a spring loaded cutoif valve between said timing valve and timing mechanism which is operated by back pressure of exhaust fluid from said motor in one direction of its movement to prevent actuation of the timing mechanism until said motor reaches the end of its stroke in one direction.

8. In a machine tool, a base, a support slidably mounted on said base for a movement toward and from operative position relative to a work piece, a cutting tool on said support, power means for efiectingsaid movement including a piston and cylinder, a supply of fluid under pressure therefor, a work ejecting mechanism, and connections between said cylinder and said work ejecting mechanism for actuating said mechanism, including a pair of valves, one of which is shifted instantly to direct fluid t the second valve, said second valve directing said fluid to said ejector and then moving to position to connect said ejector with exhaust.

9. In a machine tool, a base, a support slidably mounted on said base for a movement toward and from operative position relative to a work piece, a cutting tool on said support, power means for effecting said movement including a piston,

and cylinder, a supply of fluid under pressure therefor, a work ejecting mechanism and connections between said cylinder and said work ejecting mechanism for actuating said mechanism including a separate source of fluid under pressure for actuating said ejector, a valve for controlling the flow of said fluid to said ejector and means for actuating said valve after said tool has started to move from operative position.

10. .In a machine tool, a base, a support slidably mounted on said base for a movement toward and from operative position relative to a work piece, a cutting tool on said support, power means for 7 effecting said movement including a piston and cylinder, 9. supply of fluid under pressure therefor, a work ejecting mechanism and connections between said cylinder and said work ejecting mechanism for actuating said mechanism including a separate source of fluid under pressure for actuating said ejector, a valve for controlling the flow of said fluid to said ejector and a conduit for conducting fluid under pressure from said cylinder to actuate said ejector valve.

11. A grinding machine including peripherally opposed grinding and control wheels, a work rest for rotatably supporting a work piece in operative relation to said wheels, a work positioning and ejecting mechanism for locating a work piece in and ejecting it from said operative relation with said wheels, including a piston and a cylinder therefor, means for effecting a feeding movement of one of said wheels toward the other, including a second piston and cylinder and a conduit from a point in said feed cylinder intermediate the ends thereof for conducting fluid under pressure to effect operation of said ejector piston after a predetermined movement of said feed piston.

12. In a machine tool, a base, a support slidably mounted on said base for a movement toward and from operative position relative to a work piece, a cutting tool on said support, power means for effecting said movement including a piston and cylinder, a supply of fluid under pressure therefor, a work ejecting mechanism, and connections between said cylinder and said work ejecting mechanism for actuating said mechanism, including a pressure-operated valve operable at a controlled rate in one direction and having spaced ports for first directing fluid under pressure to actuate said ejector and thereafter directing said fluid to reset said ejector.

13. In a machine tool, a base, a support slidably mounted on said base for a movement toward and from operative position relative to a 'WOI'k piece, a cutting tool on said support, power means for effecting said movement including a piston and cylinder, a supply of fluid under pressure therefor, a, work ejecting mechanism, and connections between said cylinder and said work ejecting mechanism for actuating said mechanism, including a valve operable at a controlled rate for first directing fluid under pressure to actuate said ejector and thereafter directing fluid to reset said ejector, and a second pressure operated valve for controlling the supply of fluid to said ejector valve.

14. In a machine tool, a base, a support slidably mounted on said base for a movement toward and from operative position relative to a work piece, a cutting tool on said support, power means for effecting said movement including a piston and cylinder, a supply of fluid under pressure therefor, a work ejecting mechanism including a piston and cylinder and an ejector actuated by said piston, resilient means for urging said piston in one direction, a pressure-operated valve oper- 8 able at=a controlled rate and having spaced ports for first directing fluid to actuate said ejector piston and thereafter permitting the discharge of fluid from said ejector cylinder independently of the movement of said first-mentioned piston.

15. In a machine tool, a base, a support slidably mounted on said base for a movement toward and from operative position relative to a work piece, a cutting tool on said support, power means for effecting said movement including a piston and cylinder, a supply of fluid under pressure therefor, a work ejecting mechanism, and connections between said cylinder and said work ejecting mechanism for actuating said mechanism, including a valve operable after said piston moves said tool toward inoperative position for directing fluid under pressure to actuate said ejector and means for retarding the movement of said valve whereby fluid under pressure is first directed to said ejector cylinder and thereafter said ejector cylinder is connected to an exhaust line.

16. In a machine tool, a tool support, a feed mechanism for moving said support toward and from operative position, comprising a piston and cylinder, a supply of fluid under pressure for driving same, control means including a reversing valve, a timing mechanism comprising a free piston having a lost motion connection with said reversing valve, means actuated at the end of the movement of said feed piston toward operative position to initiate the operation of said timing piston, and means actuated by said timing piston after a predetermined interval for shifting said reversing valve to return said tool to inoperative position.

17. In a machine tool, a tool support, a feed mechanism for moving said support toward and from operative position comprising a piston and cylinder, a supply of fluid under pressure for driving same, control means including a reversing valve, a timing mechanism, means actuated in response to a drop in exhaust pressure at the end of the movement of said piston for shifting said tool into operative position to initiate the operation of said timing mechanism, and means actuated by said timing mechanism after a predetermined interval for shifting said reversing valve to return said tool to inoperative position.

RALPH E. PRICE.

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

UNITED STATES PATENTS Number Name Date 2,000,614 Roehm May 7, 1935 2,004,426 Booth et al June 11, 1935 2,117,917 Silven May 17, 1938 2,214,394 Wood Sept. 10, 1940 2,295,342 Graf et al. Sept. 8, 1942 2,364,300 Koplin et a1. Dec. 5, 1944 2,419,940 Balsiger et a1 May 6, 1947