US2039893A - Control means for hydraulic press operating circuits - Google Patents

Description

W. ERNST May 5, 1936.

CONTROL MEANS FOR HYDRAULIC PRESS OPERATING CIRCUITS Filed Sept. 13, 1932 'Patented' May 5, 1936 UNITED STATES PATENT. ort-ICE CONTROL MEANS FOR HYDRAULIC PRESS OPERATING CIRCUITS Walter Ernst, Mount Gilead, Ohio, assignor, by mesne assignments, to The Hydraulic Press Corporation, Inc., Wilmington, Del., a corporation of Delaware Application september 1s, 1932, serial No. 632,986 7 claims. (c1. en -52) This invention relates to control means for hypartly in vertical section oi?v a pump and control draulic press operating circuits,vand more parmechanism embodying the invention, a hydraulic ticularly to control means for press operating cirmotor and circuit to which the pump is connected cuits including variable discharge pumps. being shown somewhat diagrammatically; and

Pumps of this general description are of vari- Figure 2 is a fragmentary longitudinal vertical 5 ous constructions, and, generally stated, the pressectional view of a modiiled form of pump control ent invention relates in part to control mechamechanism. Y nism adapted for use in connection with a num- A practical embodiment of the invention is ber of different types of variable discharge pumps. illustrated in Figure 1 of the accompanying draw- For the purposes of illustration one embodiment ing as being connected to a pump A of the radial, 1o of the invention will be disclosed in connection reversible, variable discharge type, the pump being with a pump of the radial, reversible, variable connected in hydraulic circuit with a hydraulic discharge kindnow well known in the art. motor or press B.

Pumps of this kind are exemplified by the pump As shown, the pump A includes a casing I, a disclosed in the patent to Elek K. Benedek, No. shaft 2 which may be driven from any suitable 15 1,964,244, issued June 26, 1934. Briefly stated, source of power, and combined intake and dissuch pumps include a plurality of radially archarge pipes 3 and 4. The pipe 3 is connected Y ranged cylinders and pistons, the rate and directo the upper or pressing cylinder 5 of the press tion of discharge effected by which depend upon B and the pipe 4 is connected to the lower or the eccentricity of the cylinders or pistons relapush back cylinders 6 thereof. When the pump 20 tive to each other. The cylinders or pistons usuis discharging through the pipe 3, the ram 1 of ally are adapted to be positioned by a iloating ring the press will be moved downwardly to perform or =the like, which, by means of a control elea pressing or other like operation, the pump at ment, may be shifted to vary the eccentricity of this time receiving its intake principally from the the cylinders or pistons and thereby to effect concylinders 6. When the pump is reversed so as trol of the pump discharge. Various other kinds to discharge in the opposite direction, that is, of variable discharge pumps are known in the through the pipe 4, uid will be drawn from the art, and it will be understood that the present cylinder 5, and delivered under pressure to the invention relates to control mechanism for use in cylinders t to move the push back rams 8 and connection with pumps differing in some reram 1 to their upper positions. A compensating 30 spects from the pump illustrated herein. valve 9 of the kind fully disclosed in the United More specifically the present invention relates States patent tov Walter Ernst 1,653,350, dated to a novel arrangement of servo-motor control December 20, 1927, -is connected across the pipes means for varying the rate of discharge and/or 3 and 4 and has its central chamber I0 connected reversing the direction of discharge of a pump of to a tank II by means of a pipe I2 for compen- 35 the general character referred to so that an imsating for the unequal eective cross sectional proved and simplified arrangement of press-opareas of the cylinder 5 and the cylinders 6 in a 'erating circuit and fluid pressure supplying pump manner well understood in the art. may be had. The pump A includes a floating ring Il mount- An object of the invention is to provide a simed in the casing I, this ring being movable radialf; 40 ple and eiiicient control mechanism of the general ly with respect to the pump shaft for varying character stated. i pump discharge. A rod I4 is connected to Another object is to provide, in such a control ring I3 and extends through a packed opening I5 mechanism, novel means for limiting adjustably in one side of the casing. A cylinder body I6 is the maximum rate of discharge of the pump and mounted on the pump casingand is formed with the maximum discharge pressure thereof, the cylinder chambers Il and I8 separated bya dividarrangement being such that each adjustment ing wall I9. 'Ihe outer end of the rod I4 is encan be made without disturbing the other. larged to provide a resultant shoulder 20 disposed A further object is to provide an improved and in the cylinder chamber I1, the enlarged part f simplified servo-motor control for a pump conof the rod being iitted for sliding movements nected in circuit with a hydraulic press. Other within the bore defined by the dividing wall I9, objects will become apparent from a reading oi and the extreme outer end of the rod being prothe following description, the appended claims, vided with a piston 2l fitted for sliding moveand the accompanying drawing, in which: ments within the cylinder chamber IB. The outer Figure 1 is a view partly in front elevation'and end of this chamber is closed by a cover 22 pro- 55 vided with a vent 2l. For a purpose to be described later, the cylinder body is formed with a port 28* which opens into the cylinder i8 adjacent but slightly spaced from the inner end oi the cylinder, and with a port 29" which opens into thecylinder I8 at its extreme inner end. A check valve 28 is located in the port 2lb and is adapted to permit flow through the port inwardly towards the vcylinder I8 but not in the reverse direction.

In the embodiment o! the invention illustrated in Figure 1, a rod 24 is connected to the ring I9 on the side opposite the rod I4 and is provided with an enlarged part 25 forming a resultant shoulder 29, the enlarged part 2l being mounted for sliding movement within a bore 21 formed in the pump casing. 'I'he pump casing is likewise provided with a counter bore 28 through and beyond which the outer end oi' the rod 24 extends. A guide bracket 29 is secured to the pump casing and is provided with an internally threaded opening for the reception oi an externaly threaded sleeve 99 provided with a bushing 8| which rcceives the rod 24 i'or sliding movements. 'I'he inner end o i' the sleeve lll is adapted to cooperate with the shoulder 26 on the rod for limiting movement of the latter to the left in order to tix deiinitely the maximum rate oi' discharge by the pump. By rotating the sleeve 99 within the opening in the bracket 29, the position of the sleeve with respect to the pump casing may be changed and the rate of discharge limit thereby varied. A lock nut 92 having threaded connection with the sleeve 88 is adapted to lock the sleeve in adjusted position.

'I'he outer end of the rod 24 is threaded as at 89 for the reception ci a hand wheel nut 84 the inner iace oi which has cooperative connection with a spring seat through the medium oi' an anti-friction bearing 99. A spring 31 is mounted in surrounding relation to the rod 24 and is interposed between the spring seat and the inner end of the bracket 29 adjacent the sleeve I8. A guide member 3l is secured to the spring seat 98 and is mounted for sliding movements within the bracket 29 for cooperating with the latter to assist in maintaining the rod 24 against ilexing and for enclosing the spring 91 against the entrance of dust.

As will be described later, iluid pressure may be admitted to the cylinder I8 for moving the piston 2|, the rod I4, and the ring I8 to the right to cause the pump to discharge through the pipe 4 and the push back cylinders 8 to cause a return stroke of the platen. Ii, now, the iluid pressure in the cylinder i8 is relieved, the spring 91 will move the rod 24 to the left until the shoulder 26 on the rod engages the inner end o! the sleeve 80, whereupon movement of the rod 24 and the ring I9 to the left will be arrested, the sleeve thereby constituting a stop for limiting delinitely the maximum rate of discharge by the pump through the pipe I. By adjusting the position of the sleeve 89 to the right, the maximum rate of discharge of the pump through the pipe 3 can be reduced. For example, if the sleeve 39 is moved to the right so that its inner end will be disposed approximately hali' way between the inner and outer ends of the counter borev 28, the maxi- Figurelpositiontoraisethemaximumdischarge' pressure, or to the lett of its Figure i position to decrease the maximum discharge pressure. It will be observed that the sleeve 88 may be adjusted'to vary themaximum rate o; discharge without eecting the adjustment oi the maximum discharge pressure, and that the hand wheel 84 may be adjusted to vary the maximum discharge pressure without disturbing the adjustment oi the maximum discharge rate as determined by the position of the sleeve Il.

For supplying iluid pressure tothe cylinder I 8 for moving the piston 2| and the ring I8 to the right, a source of fluid pressure and means for controlling the application of pressure from such source to the cylinder is provided. In the illustrative embodiment of the invention, a low pressure pump l! is employed as a source of pressure referred to. This pump is arranged to receive uuid from the tank Il through a suction pipe 40 and to discharge lluid into the cylinder I8 through the medium o! a pipe 4I which provides constant communication between the discharge side oi' the pump I8 and the outer ends oi' the ports 22 and 23h, which communicate with the cylinder I8. A branch pipe 42 leads from the pipe 4I to a control valve generally designated 43 mounted on the press head, and thence through a pipe 44 to the tank Il. The control valve 43 includes a casing 4l provided with a central bore in which is mounted a piston valve 44, the casing being formed with chambers 41 and 48 both communicating with the central bore and communieating respectively with the pipes 42 and 44, a control bore portion 48 intervening between the chambers 41 and 48 in the valve casing. The piston valve 48 comprises spaced heads ll-Il slidable within the central bore, and the head 59 normally is positioned in the bore portion 49 intervening between the chambers 41 and 48 so as to cut on communication between the chambers. When the piston valve is moved upwardly to the position shown in Figure l. communication between the chambers 41 and 48 is established, so that iiuid may flow from the pipe 42 through the control valve and the pipe 44. It is desirable, in order that delicate control of the operation of the press may be eiiected. i'or the rate of ow of huid through the control valve to be susceptible to variation in small increments by comparatively large movements oi' the piston valve. To this end the head I8 of the piston valve is formed at its lower end with a V notch l2. Obviously, when the valve is moved from its closed to its open position, the rst flow of huid will take place through the top oi the V notch and will be quite small. Further upward movements of the piston valve will result in very small increases in the rate of ilow until the head I8 has cleared the bore portion 49 completely.

The lower head 8i of the valve extends down through packing 59 in the bottom end of the casing and is connected by a collar I4 with an operating rod 88 which extends through an arm 56 connected to the ram and through a guide bracket 51 on the press base. A spring I8 is intez-posed between the arm 88 and the collar I4 for transmitting motion to the operating rod and valve when the ram approaches the limit o! lits upward travel. y

For controlling the position ot the piston valve manually, a hand lever I9 is pivoted on a bracket aosasoa 60 carried by the press base and is provided with an arm 6I having a rounded end disposed between collars-6262 secured to the lower end`of the operating rod 55.

As will be described in detail hereinafter, the piston valve 46 is in a position below that shown in Figure 1 at certain stages of the operation, so that no flow can take place through the bore portion 49 connecting the chambers 41 and 48 whereby pressure is applied through the pipe 4I to the piston 2i in the cylinder I8. During Such stages of operation, it is necessary that the fluid discharged by the pump 39 be returned to the tank II, and for accomplishing this purpose a relief valve is connected in parallel with the valve controlled bore portion 49. In the form shown, the relief valve is incorporated in the casing of the control valve 43. As shown, the valve casing'45 is provided with a passage 63 disposed between the chambers 41 and.48. A plunger valve 64 has its lower end mounted for sliding movements in the passage 63 and has a head 65 enclosed within a spring chamber 66, the head and valve being held down by a spring` 61 interposed between the head and a cap 68 having threaded connection in the casing at the upper end of the spring chamber. In operation, when the bore 49 is closed and when the piston 2i has been moved to its extreme right hand position so that there can be no further flow of fluid through the pipe 4|, fluid pressure in the chamber 41 will raise the spring loaded plunger valve, whereby fluid will be by-passed through the passage 63 and thence into the chamber 48 and through the pipe 44 to the tank II, the pipe 42, the valve 43, and the pipe 44 thereby constituting an exhaust conduit connected between the cylinder I8 and the tank II.l In order that the maximum pressure of the fluid discharged by the pump A will not exceed a predeter mined value, a branch pipe 698L is connected between the pipe 3 and the cylinder chamber I1, the arrangement being such that the shoulder 29 on the rod I4 will be acted on by the same unit pressure as exists ln the pipe line 3 and the pressing cylinder 5 at all times. Y

In order that the cooperative relation of the various parts of the arrangement described above be clear, a complete operating cycle will be set forth briefly. It will be assumed that the parts are in the positions shown in Figure l and that the pumps A and 39 are being driven. The ram is in its upper position wherein the arm 56 cooperates with the spring 58 to maintain the piston valve 46 elevated so as to provide communication between the valve chambers 41 and 48 through the medium of the bore 49. The communication through the bore 49 is restricted so that the pump 39 will discharge against back pressure which will act through the pipe 4I, the ports 23B and 23h, and on the piston 2| so as to maintain the ring I3 in a substantially neutral or zero discharge position against the urge of the spring 31 which tends to move the ring I3 to the left. In order to produce a down stroke of the ram, the hand lever 59 will be turned in a counterclockwise direction, thereby raising the piston valve to such a position as to permit substantially unobstructed flow through the bore portion 49. This will permit free by-passing of fluid from the pump 39 through the pipe 42, the valve chamber 41, the bore portion 49, the valve chamber 48, and the pipe 44 to the tank II, so that the pressure in the pipe 4I and cylinder I8 will drop, after which the spring 31 will move the rod 24 and the ring I3 to the left so as to cause the pump to discharge through the pipe '-3 into the cylinder 5 and to initiate the downward movement of the ram. y

If it is desired that the ram move slowly on its downward stroke, the hand lever 58 is ma-V nipuiated so as to cause a slight throttling of the 'fluid passing through the bore as. This will resultl in the building up of back pressure in the pipes 42 and 4I and the cylinder I8, this building up of back pressure being dependent upon the degree of throttling effected. This back pressure, acting on the ypiston 2 I, will move the latter and the ring I3 toward the right against the urge of the spring 31 so as to reduce the rate of discharge of the pump through the pipe 3. It will be seen that, by shifting the piston valve to.eifect diiferent degrees of throttling of fluid flowing through the bore 49, it is possible to create any desired back pressure in the cylinder I8, and that to each back pressure thus created there belongs a deilnite corresponding spring pressure which will balance the back pressure and which will hold the ring I3 in a definite position. Any slight change in the position of the piston valve will result in a corresponding change in the position of' the ring I3, so that the rate of discharge by the pump may be varied readily.

When the ram encounters the work so that pressure builds up in the cylinder 5, this pressure will act through the pi'pe 69* and in the cylinder I1 to move the rod I4 and the ring I3 to their sure of fluid discharged by the pump. 'I'his pressure may be varied by adjusting the hand wheel 34.

When it is desired to produce a return movement of the ram, the operaing lever is turned in a clockwise direction so as to lower the piston valve and to close the bore 49. This will cause immediately the building up of a back pressure in the pipes 42 and 4I and the cylinder I8, resulting in movement of the piston 2l and the ring I3 to the right against the urge of the spring 31, thereby reversing the ow of fluid through the pump so that the latter will discharge through the pipe 4v into the push back cylinders 6 to start the ram on its upward movement. .When the piston 2I has been moved to its extreme right hand position, the pressure responsive relief valve 64 will open to permit by-pass of fluid from the pipe 42 through the chamber 41, the passage 63, r

hand position against the urge of the spring 31.

As the ram approaches the end of its return stroke, the arm 56, acting through the spring 58 and the collar 54, will raise the piston valve so as to permit more free flow of fluid through the bore 49 and to reduce the pressure acting on the piston 2|, thereby permitting the spring 31 to move the ring' I3 toward neutral. 'I'he ram finally will come to rest preventing further opening of the piston valve. The ram normally will be maintained at rest in its upper position, but if there is a tendency for the ram to drift downwardly there will result a lowering of the piston valve and a further throttling of the bore 49, whereby back pressure again will build up in the pipes 42 and 4I and the cylinder I8, causing the tion of a nut 80 keyed to a hand wheel Il.

4 aosaeos through the check valve controlled port 23", the

entrapped fluid will serveto cushion the piston 2l and to bring it to rest without the occurren of shocks. When pressure builds up in the pipe 4| ,after the piston valve has been closed, the

check valve 23 will open so as to permit fluid to flow through the port 2lb into the left hand end of the cylinder I4 so as to move the piston to the right.

Figure 2 illustrates a modincation of the means for adjustably limiting the maximum rate of discharge and the maximum discharge pressure of the pump. In this modification the iloating ring I3, the rod 24 connected thereto and providedwith an enlarged part 25 forming a shoulder 26, and the casing bore 21 in which the rod is mounted for sliding movements are the same as those parts as disclosed in Figure 1. In the Figure* 2 construction, a bracket 69 bolted to the pump casing is provided with an inwardly extending flange 1li which receives for sliding movements a sleeve 1I the inner end. of which is provided with a peripheral ange 12 adapted to cooperate with the ilange 10 to limit the movement of the sleeve to the left, the flanges 10 and 12 constituting stops. The sleeve 1I is threaded as at 13 for the reception of a hand wheel equipped nut 14 which has cooperative connection with a spring seat 1l through the medium of an anti-friction bearing 16, the spring seat including a guide portion 11 arranged for sliding movements within the guide bracket 69. A spring 10 is mounted in surrounding relation to the sleeve 1I and is interposed between the spring seat 1I and the flange 1li of the bracket 89.l

'I'he rod 24 is slidable within the sleeve 1i and is threaded at its outer end as at 19 for the recep- 'I'he nut is provided at its inner end with a peripheral ilange 82, the inner face of which abuts against the end of the sleeve 1I and the outer face of which is in. engagement with the inwardly directed flange 83 of acoupling nut B4 secured to the sleeve 1|, .whereby the nut lli may rotate with respect to the sleeve 1I but is held against 'axial movement with respect thereto.

In operation, the spring 1I tends to move the sleeve 1| to the left and the end of the sleeve, acting on the nut 80, will tend to move the latter and the rod 24 to the left. 'I'he extent to which the rod 24 can be moved to the left under the urge of the spring is' dependent upon the adjust- `ment of the nut 8l axially with respect to the rod 24. This is due to the fact that, when the ange 12 on the sleeve 1I engages the ilange10 on the bracket 89, there can be no further movementl of the sleeve to the left, and hence no further movement of the rod 24. The position to which the rod 24 has been moved when the flange 12 engages the flange 1li therefore depends on the relative axial adjustment of the nut 80 with respect to the rod 24. If it is desired to vary the maximum discharge pressure, the load on the spring 18 is changed by rotating the hand wheel nut 14, it being obrved, however, that this adjustment of the spring loading does not change or in any way atleet the adjustment determining the maximum rate or discharge. similarly. um"

maximum rate of discharge can bechanged by rotating the hand wheel Il without aifecting in any way the adjustment of the maximum dis charge pressure.

From the foregoing it will be apparent that my improved control means not only is of simple construction but also is capable of eifecting very accurate servo-motor control of a variable discharge pump whereby a ram connected in circuit with the pump can be operated under delicate control of speed and pressure. The importance of the advantage due to the entirely independent adjustments of maximum discharge rate and maximum discharge pressure will be apparent to those skilled in this art. The circuit and control apparatus disclosed herein may be used in connection with various specific kinds of 4rpumps other than that illustrated herein, and it will be understood that numerous changes may be made in the specific construction and relative arrangement of the parts without departing from the spirit of the invention as defined in the claims.

I claim:

l. In combination in a hydraulic circuit, a fluid-actuated machine, a variable delivery pump connected thereto and having a shiftable nowcontroln element, pressure responsive shifting means connected to said shiftable'eiement, a source of iluid pressure uninterruptedly connected to said shifting means, and a normalhv-closed valve in a conduit leading from said source, saidV valve being arranged to be operated manually and also by movement of. an element of said machine and adapted to alter the pressure therein slowly during the rst part of its stroke and more rapidly during the remainder thereof so as to consequently alter the position of said shifting means and the delivery of said pump.

2. In combination .in a hydraulic circuit, a fluid-actuated machine, a variable delivery pump connected thereto and having a shiftable flowcontrol element, pressure responsive shifting means connectedtosaid shiftable element, a source of fluid pressure uninterruptedly connected to said shifting means, and a normally-closed valve in a conduit leading from said source, said valve be ing arranged to be operated manually and also by movement of an element of said machine and adapted to alter the pressure therein more rapidly at one part of its stroke than at another part so as to consequently alter the position of said shifting means and the delivery of said pump.

3. In combination in a hydraulic circuit, a hydraulic machine with a reciprocating ram, a variable delivery pump having hydraulic connections only therewith and having a shiftable flow-control element. iluid pressure responsive shifting means connected to said shiftable element, said shifting means being operated in one direction only by said iluid pressure and urged in the opposite direction by yielding means, and a control valve for controlling the operation of said shifting means mounted on said machine and arranged when shifted at an even speed to pass iiuid therethrough more rapidly at one part of its stroke than at another part thereof, said control valve being adapted to be operated manually and also automatically by said ram. A

4. In combination in a hydraulic circuit, `a fluid-actuated machine, a variable delivery pump connected thereto and having a shiftable owcontrol element, pressure responsive shifting means connected to said shiftable element, a

source of uid pressure uninterruptedly connected to said shifting means, and a normallyclosed valve in a conduit leading from said source, said valve being arranged to be operated manually and also by movement of an element of said machine and adapted when opened at an even speed to pass the fluid therethrough at an accelerated rate of quantity delivery during one part of its stroke and at a constant rate of quantity delivery during the remainder of its stroke so as to consequently alter the position of said shifting means and the delivery of said pump.

5. In combination in a hydraulic circuit, a duid-actuated machine, a variable delivery pump connected thereto and having' a shiftable flowcontrol element, pressure responsive shifting means connected to said shiftable element, a source of fluid pressure uninterruptedly connected to said shifting means, and a normally-closed valve in a conduit leading from said source, said valve being arranged to be operated manually and also by movement of an element of said machine and adapted when opened at even speed to pass the fluid at differently-accelerated rates of quantity delivery during different parts of its stroke so as to consequently alter the position of said shifting means and the delivery of said pump.

6. In combination in a hydraulic circuit, a fluid-actuated machine, a variable delivery pump connected thereto and having a shiftable nowcontrol element, pressure responsive shifting means connected to said shiftable element, a source of fluid pressure uninterruptedly connected to said shifting means, and a normally-closed valve in a conduit leading from said source, said valve being arranged to be operated manually and also by movement of an element of said machine and adapted when opened at an even speed to permit a regular increase of the rate of quantity delivery of. fluid passed up to a certain point and then to change to a different quantity rate of delivery so as to consequently alter the position of said shifting means and the delivery of said pump.

7. In combination in a hydraulic circuit, a duid-actuated machine, a variable delivery pump connected thereto and having a shiftable flowcontrol element, pressure responsive shifting means connected to said shiftable element, a source of fluid pressure uninterruptedly connected to said shifting means, and a normally-closed valve in a conduit leading from said source, said valve being arranged to be operated manually and also by movement of an element of said machine and said valve having a piston valve member with an enlarged port-controlling portion abutting a reduced portion, the shoulder therebetween being provided with a V-notch whereby said valve when opened at an even speed passes fluid at a slowly increasing quantity rate of, delivery during the first part of its stroke and afterward at a different regular rate so as to consequently alter the position of said shifting means and the delivery of said pump.

WALTER ERNST.

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