US2511541A - Hydraulic press control circuit embodying fluid pressure intensifying means - Google Patents

Description

June I3, 1950 H. M. PURCELL 2,511,541

HYDRAULIC PRESS CONTROL CIRCUIT EMBODYING FLUID PRESSURE INTENSIFYING MEANS Filed July 8, 1947 2 Sheets-Sheet l M INVENTOR a NE D Mn PUWCfiLL ATTORNEYEM June 13, 1950 H. M. PURCELL 2,511,541

HYDRAULIC PRESS CONTROL CIRC UIT EMBODYING FLUID PRESSURE INTENSIFYING MEANS Filed July 8, 1947 2 Sheets-Sheet 2 ITEA- 7 WORK gwucxnfot, HOWARD M. PURCELL Patented June 13, 1950 HYDRAULIC PRESS CONTROL CIRCUIT EM- BODYING FLUID PRESSURE INTENSIFY- ING MEANS Howard M. Purcell, Philadelphia, Pa., assignor to H-P-M Development Corporation,

Wilmington,

DeL, a corporation oi Delaware Application July 8, 1947, Serial No. 759,674

8 Claims. (01. 60-52) This invention relates to hydraulic press actuating systems, and especially to such systems characterized by high pressures.

The particular object of this invention is to provide an improved high pressure actuating circuit for a hydraulic press.

It is another object of this invention to provide a high pressure actuating circuit for a hydraulic press which employs a minimum of valves.

Another object'of this invention is to provide a press actuating circuit including a hydraulic intensifier which may be made operative in either direction of movement of the press ram.

Still another object is to provide a hydraulic press actuating circuit in which the press ram is normally operated by the discharge from a pump and in which there is an intensifier which becomes operative automatically at a predetermined pressure in either direction of movement of the press ram.

A still further object is to provide a press operating circuit including a pressure intensifier in which the shift over from low to high operating pressures is accomplished smoothly and positively.

These and other objects and advantages will become more apparent uponv reference to the following description taken in connection with the accompanying drawings in which:

Figure 1 is a diagrammatic view of a press operating circuit according to this invention;

Figure 2 is a diagrammatic wiring diagram of.

This invention generally is concerned with a hydraulic press actuating circuit in which there is a pump connected to supply eitherthe advancing or the retracting side or a press ram. This pump is preferably a reversible type pump but itwill be understood that a one way delivery pump and a reversing valve could be employed in place of a reversible pump if desired.

v The aforementioned reversible pump is connected between the advancing and retracting means and there is preferably a solenoid which may be energized to bring about the delivery of the said pump to the advancing means. Upon de-energizing the said solenoid, the delivery of the pump is automatically reversed to bring about a supply to the retracting means of the press ram. Connected between the opposite ports of the pump is a check valve which has therein a. movable member. The check valve also comprises a third port and in response to a pressure at either of the first two ports the movable valve member of the check valve moves to connect the third port therewith. In this manner, the discharge side of the pump is always connected with the third port of the check valve.

The aforementioned third port is connected with the inlet of a hydraulic intensifier which discharges to a valve that is automatically operable to direct the said discharge eitherto the advancing means of the press rain or the retracting means thereof, depending upon which direction the press ram is moving. A motor is connected with the intensifier and is selectively operable to drive the intensifier for making it efiective in response to a predetermined pressure acting on which ever of the advancing or retracting means of the press ram the pump is supplying at the time. A hydraulic intensifier of this nature is fully shown and described in the U. S. Patent to Warren R; Tucker, No. 2,486,079, issued October 25, 1949, and assigned to the same assignee as the instant application.

The arrangement briefly described above includes no shiftable valves except for the check valvegwhich are directly responsive to pressures in the conduits connected therewith. These valves are of simple construction and there is little likelihood that they will warp and bind under the high pressures passing therethrough as isthe case with ordinary operating valves such as fourway piston type valves, or rotary valves.

Structural arrangement Referring more particularly to the drawings,

there is shown a press cylinder at Ill within which.

pump I4 is connected through a valve generally indicated at IS with the retracting side of the ram.

The valve 18 comprises a body portion 20 havin; ports opening from the top and bottom thereof, and also having a port opening from the side intermediate the said top and bottom ports. Within the valve body 26 there is a valve member 22 which, as shown, may comprise a ball. The valve member 22 is movable toward either end of the body 26 to disconnect the port at that end from the port opening from the side of the valve and to connect the said side opening port with the port in the other end of the valve body. As shown there is a spring 24 which normally urges the ball upwardly to seat against the port in the upper end or the body 20.

Connected between the two ports of the pump l4 there is another valve 26 which has a side opening port 26 therein connected with the inlet of the pressure intensifier 36. The valve 26 is provided with a valve member or ball which is movable within the valve in response to positive pressures at either of the ports of the pump I4 to connect the pressure port of the pump with the inlet of the intensifier 30. The discharge port of the intensifier 30 is connected with the side opening port of a third valve 32 which is constructed similarly to the valves l8 and 26. The upper port of the valve 32 is connected to the discharge side of the check valve it while the lower port is connected with the upper port of the valve i8.

For supplying make-up fluid to the pump [4 in either direction of delivery thereof there are a pair of check valves 36 which have their outlets connected with opposite sides of the ram l2 by way of valves l6 and I8 and their inlets connectedby a conduit 38 with the reservoir 40.

The exhaust conduit 42 of the intensifier also discharges directly into the reservoir 40.

The advancing side of the press ram is adapted for being connected directly with the reservoir by means of a surge valve 44. This valve is normally closed but may open by suction in the advancing means for permitting fluid to flow thereto from the reservoir 40, or will open in response to predetermined pressure conducted thereto by the conduit 46 leading to the retracting means for theram l2.

As shown in more detail in Fig. 4, the surge valve 44 has formed therein a lower chamber 44a which communicates with the advancing area of the ram by way of the ports 44b.- Slidably carried within the lower chamber 44b of the valvev is the lower head 44c of a movable valve memadvancing area of the ram, and in response to such a suction, the lower head 440 of the valve 44 is displaced from its normal position of closure with respect to the channel 440 to permit make-up fluid to enter the advancing area of the ram. Thereafter, as thepress platen meets the work and pressure within the advancing area builds up, the valve will once again close and permit pump pressure to work upon the ram. As mentioned before, the surge valve 44 is also effective upon a retraction stroke to open the advancing area of the ram to the reservoir. This latter opening of the valve is eifected by a predetermined pressure build-up within the retracting area of the ram, which pressure is transferred through the conduit 46 to act upon the upper head 44c of the valve member and thereby to displace the same downwardly and unseat the lower head 440. This provision is made for the purpose of rapidly exhausting fluid from the relatively larger ram-advancing area during the introduction of pressure fluid within the smaller ram-retracting area thereof.

Connected with the conduit between the check valve it and the advancing means of the ram l2 there is a pressure switch indicated as PSI and which is operable in response to a predetermined pressure to close a pair of contacts.

Similarly, there is also a pressure switch PS2 connected with the conduit leading from the valve it! to the retracting means of the ram I2 and also operative in response to a predetermined pressure to close a pair of contacts. Still a third pressure operated switch indicated at T is connected with the advancing means of the spective cylinders and there is no passage of fluid ber 44d which is also provided with an upper.

enlarged head member 44c. The upper head 44c of the valve member is reciprocable in a second chamber 44f formed in the upper end of the valve casing. Communicating with the upper end of the chamber 441 is one end of the conduit 46 which, as beforementioned, has its opposite end connected with the retracting area of the ram 12. Extending through the valve casing and communicating with the interior of the reservoir 40 is a Y-shaped channel or port 449 which is also adapted to communicate with the lower chamber 44a of the valve. I

In operation, the lower head 44c of the movable valve member normally closes the channel 44c-with respect to the lower chamber 440 and the advancing area of the ram l2, due to the action of the compression spring 44h which is mounted between the lower wall of the chamber 44a and the under side of the lower head 440. During an advancing stroke, 'where' the weight of the ram and press aid the pump discharge, there often times occurs a suction within the through the intensifier. Thus, there is a motor M connected with the valve member of the intensifier and which,'when energized, brings about a transfer of fluid from the side port of the valve 26 at one pressure to the side port of the valve 32 at an intensified pressure.

The operating principle of the intensifier 36 is diagrammatically illustrated in Figure 5, wherein only one of a plurality of the pressureintensifying pistons 36a contained in the intensifler is shown in relation to the driven rotaryvalve member or distributor 30b. In operation, rotation of the distributor 3812), upon energization of the motor M, is effective to alter- I nately direct fluid under pressure of the pump 14 against the two pressure areas 340 and 36d of the piston 36a while at the'same time connecting the opposite area Me with exhaust and the smaller opposite area 36! with the work. Thus, pump pressure applied to two faces of the .piston causes fluid discharged from the one smaller area It] to'be more highly pressurized as the single area 301 is absorbing the total force produced by the pump pressure acting upon the opposite two faces 30c and 30d. It will be understood, that the interconnecting of the separate pressure faces 30c, d, e and I of the various pistons of the intensifier with the pump inlet, work outlet and exhaust ports, respectively, is accomplished solely by means of a suitable system andarrangement of ports within the rotary fluid distributor III) in connection with a system of channels or passages within the housing of the intensifier leading to the separate intensifier pistons 30a, and that the proper distribution of fluid to and from the pistons is accomplished entirely within the intensifier casing and thence to the respective work and exhaust outlets thereof.

It will further be understood that the illustration of the intensifier as shown in Figure is intended only as a graphic illustration of only one cycle in the operation of one of a plurality of identical piston stages, and that the intensifier during operation is capable of constantly discharging fluid at a higher-than-pump' pressure, but at a reduced volume due to the loss of fluid to exhaust.

The pump it has connected therewith any suitable linkage for reversing its delivery. v As shown there is a linkage ill which includes a-lever 52 having a solenoid SI connected therewith which, when energized will actuate the linkage to shift the pump to bring about the delivery therefrom to the advancing means oi the ram i2. When the solenoid SI is de-energized the spring 54 brings about the delivery of the pump to the retracting means of the ram l2. When the ram has retracted a predetermined amount an arm 56 on the platen 58 connected with the ram i 2 actuates the linkage 50 to place the pump in neutral delivery position thereby to halt the pres ram and platen.

The electrical circuit for controlling the energization of the solenoid SI and the motor M connected with the intensifier valve member is shown in Figure 2. Between the power lines Li and L2 and in series with the normally'opened push button station 60 there is a contactor coil A. Bypassing the push button 60 there is a pair of normally opened contacts adapted for being connected by actuation-of the blade Al by energization of the contact coil A and the normally closed pressure switch '1. Parallel withcoil A is the pump shifting solenoid SI. Also connected between the power lines Li and L2 is the motor M in series with the paralleled and normally open pressure switches PSI and PS2. Upon closure of either of these pressure switches the motor M will be energized to drive the intensifier 30 and thereby to make the same effective.

In Figure 3 there is illustrated another type of check valve which may be used in place of any of the valves iii, 26 or 32. The valve shown in Figure 3 is essentially identical with the aforementioned check valves but includes a cylindrical valve member 62 rather than a ball.

Operations In operation, the advancing stroke of the ram i2 is commenced by closing the Push button 60 whereupon the contactor coil A and the solenoid Si are energized and a holding circuit therefor is established by the contactor blade At. The pump now delivers through the check valve IE to the advancing side of the rain l2. The retracting side of the ram l2 discharges through the valve l8 to the lower port of l4. The initial movement by the ram l2 takes place as rapidly as the pump it withdraws fluid from beneath the ram 12 and the advancing'means is partially filled through the surge valve 44. When the ram engages the work further movement thereof takes place by the delivery of the pump it to the advancing means thereof and at this time make-up fluid enters the pump through the lower of the check valves 38.

When pressure rises on the advancing means of the ram suificiently to close the pressure switch PSI, the motor M commences to operate and the intensifier 30 delivers high pressure fluid to the side port of the valve 32. It will be noted that at this time the valve member of the valve 32 is in its lowermostposition so that the pressure fluid supplied by the intensifier flows directly to the ram advancing means.

Upon the accomplishment of a predetermined higher pressure on the ram advancing means, the switch T opens and de-energizes the coil A and the solenoid SI. This permits the spring 54 to move the pump to deliver to the retracting means of the press ram. The ram I! now moves upwardly with fluid being deliveredthereto from the lower port of the pump l4 through the valve l8, and with the advancing means thereof exhausting through the surge valve 44 which is piloted open by pressure conducted thereto through theconduit 46.

Should the press ram meet resistance during its retracting movement, the pressure switch PS2 willclose and again make the intensifier 3D effective to deliver a high pressure fluid to the side port of the valve 32. At this time, the valve member of the valve 32 is in its uppermost position and the high pressure fluid thus flows to the upper port of the valve l8. This moves the valve member 22 thereof downwardly and directs'the said high pressure fluid to the ram retracting means. vShould the resistance encountered by the ram drop, then the pressure both the advancingand retracting means of the pressr'am.

As a modified arrangement, the springs shown in the check valves l8 and 32 could be eliminated by so positioning the valves that the valve members thereof were normally positioned by gravity toward the" end to which they are biased by their respective springs as shown in the draw lugs.

It will be understood that this invention is susceptible to modification in order to adopt it to different usages and conditions and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. In a hydraulic circuit; a fluid motor having a pair of ports; a reversible source of pressure fluid connected to supply pressure fluid to either of the ports of said motor; a fluid pressure intensifier having an inlet and an outlet and operable to receive fluid at the said inlet and to redischarge it from said outlet at increased pressure;

. valve means connected between the inlet of said intensifier and the opposite sides of said source and operable to connect said inlet with the delivery side of said source; a'second valve means connected between the discharge side of said intensifier and the ports of said motor and operable to connect the said discharge side with whichever oi said ports is under pressure; and means responsive to the accomplishment or a predetermined pressure at either of said motor ports for bringing about the delivery oi high pressure fluid thereto from said intensifier.

2. In a hydraulic circuit; a fiuid'motor having a pair of ports; a reversible pump connected between said ports; a fluid pressure intensifier having an inlet and an outlet and also having a valve member which must be driven to make said intensifier effective; a first valve responsive to pressure at either side oi said pump for connecting that side with the inlet or said intensifier; other valve means responsive to pressure at either of said motor ports for connecting that port with the discharge side oi said intensifier; and means responsive to a predetermined pressure developed at the motor port with whlclr'theflehaige side of said intensifier is connected for actuating said drivable valve member to make said intensifier effective. 7

3. In a hydraulic circuit; a fluid motor having a pair of ports; a reversible pump connected between said ports for supplying fluid pressure.

thereto; a fluid pressure intensifier having an inlet and an outlet and also having a valve inem her which must be driven to make said intensifier eii'ective; a shuttle valve connected between the opposite sides of said pump and the inlet 01' said intensifier and operable automatically for conoutlet-oi said intensifier with whichever port of said motor is under pressure, and to disconnect said pump therefrom; and means responsive to the accomplishment ot a predetermined pressure at the port of the motor connected with the outlet or said intensifier ioractuating said drivable valve member thereby to make said intensifier efiective.

4. In combination; a reversible delivery source of pressure fluid; a fluid pressure intensifier having a low pressure inlet and a high pressure outlet; and a shuttle valve connected between the opposite sides of said source and the inlet oi said intensifier and including a valve member responsive to pressure at either or said sides for connecting the said side with the inlet of said intensifier.

5'. In combination; a reversible delivery pump;

a fiuid pressure intensifier having a low pressure inlet and a high pressure outlet; a valve connect'ed between the opposite sides or said pump and said inlet; and a valve member in said valve responsive to pressure at either side oi said pump for connecting that side with said inlet while simultaneously interrupting communication between said inlet and the other side 0! said pump.

6. In a hydraulic circuit; a fluid motor having a pair of ports; a reversible source of pressure fluid connected between said ports for supplyingr actuating fluid to saidmptor; a fluid pressure 8 intensifier having an inlet and an outlet and adapted for receiving fluid at the said inlet and redischarging it from sald outlet at increased pressure; means responsive to the accomplishment 01' a predetermined pressure at either of said motor ports for bringing about the delivery of high pressure fiuid from said intensifier, and

.means responsive to the accomplishment oi a said motor ports for bringing about the delivery necting said inlet with the pressure side of said pump; other valve means operable to connect the of high pressure fluid from said intensifier, means responsive to the accomplishment of a predetermined higher pressure at one oi said motor ports for reversing the source of preaure fluid, said fluid motor having a ram, and means carried by the ram to place the source oi fluid pressure inneutral when the ram i r'etracted a predetermined amount.

8. ma hydraulic control circuit; a fluid motor having a pair of ports; a reversible source of pressure fluid connected between said ports ior supplying actuating fluid to said motor; a driven fluid pressure intensifier having an inlet and an outlet and operable when driven to receive fluid at the said inlet and redischarge at least a part of said fluid from said outlet at increased pressures; a first valve means connected between said source and the inlet of said intensifier for directing pressure fluid discharged from said source to the inlet of said intensifier; other valve means connected between the outlet or said intensifier and the ports or said motor for establishing communication between the outlet of said intensifier and whichever of said ports is receivihg pressure from said source during operation 01' said intensifier; and means responsive to a given maximum pressure at either of the ports of said motor for bringing said intensifier into operation.

HOWARD M.PURCELL.

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

UNITED STATES PATEN'rs Number Name Date 2,255,560 Fieber Sept. 9, 1941 2,308,712 Peterson Jan. 19, 1943 2,366,388 Crosby Jan. 2,1945

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