US2484879A - Hydraulic press equipped with a synchronized stripping plunger - Google Patents

Description

W. ERNST ET AL HYDRAULIC PRESS EQUIPPED WITH A SYNCHRONIZED STRIPPING PLUNGER Filed June 5, 1944 INVENTOR WALTER ERNST BY cums Mining/4 ATTORNEY Patented a. is, 1949 HYDRAULIC PRESS EQUIPPED WITH A SYNCHBONIZED S'I'BIPPING'PLUNGEB Walter Ernst and Clyde Hedriek, Mount Gilead, Ohio, assignors to H-P-M Development Corporation, Wilmington, Del., a. corporation of Delaware Application June 5, 1944; Serial No. 538,879

This invention relates to hydraulic apparatus and, in particular, to hydraulic drawing presses and the like.

In the drawing of sheet metal and similar operations it is often necessary forcibly to re; move the formed workpiece from the punch or die within which it has been shaped. Most often, it is necessary to remove the workpiece from a male die or punch portion carried by the movable platen of the drawing press. To accomplish the stripping oif of the workpiece, a plunger is provided which is urged downwardly through the punch and into engagement with the workpiece thereon.

This invention has for its primary object the provision of an actuating system for such a plunger which synchronizes the action thereof with the movement of the press platen.

It is another object to provide in a hydraulic press a hydraulically actuated stripping plunger and an auxiliary hydraulic circuit therefor.

These and other objects will become more apparent upon reference to the following specification and the accompanying drawings, in which:

Figure l is a diagrammatic view of a hydraulic press having an auxiliary plunger actuated by a hydraulic system according to this invention; and

Figure 2 is a diagrammatic wiring diagram showing the electrical circuit associated with the auxiliary plunger actuating system.

General arrangement In general, a reciprocable ram is supplied with actuating fluid from any suitable hydraulic circuit such as a reversible pump.

The ram is adaptedto reciprocate a die member to form a workpiece. The ram is bored to receive a plunger which is reciprocable within the said bore and is adapted to eject the workpiece from the die member carried by the said ram.

The ejecting or stripping plunger is preferably double acting andhas its retraction area connected with the retraction area of the main ram. The advancing side of the stripping plunger 11 Claims. (01. 11

I taneously with the commencing of the retraction I of the cylinder l0 through the conduit 18.

of the main ram and pressing member carried thereby.

Preferably, the main press ram is controlled by electrical devices which are interlocked with elecq trical control means for the stripping plunger so that the actuation of the former is automatically operable to actuate the latter.

Structural arrangement Referring to Figure 1, there is shown a drawing press comprising a main cylinder ill within which is reciprocable the differential plunger ii. The plunger H has attached thereto a platen I! which is adapted to carry a pressing member (not shown).

The diiferential plunger H defines with the cylinder l0 advancing and retracting chambers which are supplied with actuating fluid from a pump I3 through the conduits ii and I5 respectively. The conduit I5 is connected by a conduit I6 with the inwardly opening check valve I? located within the reservoir or tank l8. Mounted in the top of the cylinder 10 is a surge valve IQ of any suitable construction, the surge valve being actuated by fluid conducted thereto by the conduit 20 which-is connected with the conduit 16. Also mounted within the tank I8 is a valve 21 which is hydraulically connected with the advancing chamber of the cylinder it by a conduit 22 and with the retraction chamber The valve 2| is operable at the moment of reversal is supplied with pressure fluid from an auxiliary '24 to which is fastened the solenoid SI.

of the plunger H at the end of a working stroke to bypass the delivery of the pump I3 while simultaneously releasing the pressure from the adclockwise, and places the pump in position to deliver into the conduit IS. The arm 24 is also adapted to be engaged by the rod 25 attached to the platen 12 so that the pump 13 is automati-- cally moved to no delivery position thereby when the platen l2 and plunger H are in their retracted position. a

The plunger ii is bored as at 30 to receive the double acting plunger 3| the latter being reciprocable through a bore in the platen [2 so as to engage the workpiece or the ejector pins of the pressing member carried by the said platen. The retraction area of the plunger 3| is connected through a bore 32 with the retraction area of the plunger H. The bore 32 includes an adjustable restrictor 33 which may comprise a needle valve or any other suitable type of choke valve. The advancing area of the plunger 3| is connected by a bore 34 in the plunger H with a conduit 35 which is adapted to supply actuating fluid to the said plunger.

Actuating fluid for the plunger 3| is supplied by a pump 36 which is connected to the four-way valve 31. The pump 36 is preferably a one-way delivery type pump and continuously draws fluid from the reservoir l8 and discharges the same into the valve 31. The valve 31 is provided with the pilot cylinders 38 and 39 which are connected,

respectively, by the conduits 40 and 4| with the service ports of a four-way valve 42. The fourway valve 42 is adapted to be shifted into one end position by a spring 43 and, into the other end position by a solenoid S4 when the latter is energized. Pressure fluid may be supplied to the four-way valve 42 in any suitable manner such as by the pump 44.

The valve 31 comprises a pair of service ports one of which is connected by the conduit 45 through the check valve 46 with the advancing chamber of the cylinder Ill. The valve 46 is eifective to permit flow into the said advancing chamber but not therefrom. The other service port of the valve 31 is connected by a conduit 41 to the inlets of the valves 48, 49 and 50, the outlets of these valves being connected to the conduit 35. The valve 48 is a check valve which permits free flow of fluid from the conduit 41 to the conduit 35 but not vice-versa. The valve 49 is a choke valve adapted to create a predetermined restriction from the flow of fluid from the conduit 35 to conduit 41 and the valve 50 is a pressure relief valve adapted to relieve the pressure in the conduit 35 should the same exceed a predetermined amount.

The solenoid S4 is adapted to be energized by a contactor blade S3A which is associated with the solenoid S3. When the solenoid S3 is enerized, the aforementioned contactor blades indicated at 83A closes and the solenoid S4 is energized to shift the valve 42.

- Located in the press frame or in association with the platen l2 so as to be contacted thereby are a plurality of limit switches LSI, LS2, LS3 and LS4. LS2 is a normally open switch which is momentarily closed during the retraction stroke when the said pressure has attained a predetermined value.

Referring to Figure 2 the arrangement of the limit switches and solenoids in the rectrical circult is shown. In Figure 2 the supply lines are indicated at 5| and 5|. Connected to the line 5| is a contactor solenoid indicated at C which is connected at its other end to a switch 52 which in turn is connected with a push button 53. The push button 53 is connected to a junction point 54, the junction point being connected through a normally closed push button 55 and a normally closed temperature responsive switch 56 with the line 5|. The switch 52 is a normally open push button station having means associated therewith for locking t1; switch in a closed position.

Also connected with the line 5| are the solenoids SI and S2 which are connected at their other ends. with the limit switch LS4 which latter connects through the normally closed blade Tl of the switch T, the normally open limit switch LS3 and the normally open blade CI of the contactor solenoid C with the junction point 54. A blade SIA of the solenoid S| is arranged to bypass the limit switch LS3 and the contactor blade CI.

Also connected with the line 5| is the solenoid S3 which has connected to its other end the partil of the press platen. The limit switch LS2 is connected in parallel with a pair of contacts which have associated therewith ablade which is actuated by a solenoid S2. The solenoid S2 is adapted, when energized, to open the contacts and when deenergized to permit the said blade to close the contacts. The limit switch LSI is a normally closed switch which is positioned so as to be opened when the plunger II has completed its retraction stroke. The limit switch LS3 is a normally open switch which is adapted to be closed by the platen when the latter is in its fully retracted position and the switch LS4 is a normally closed switch adapted to be opened by the platen at the end of the working stroke of the press.

' A pressure responsive switch T is hydraulically connected with the conduit l4 so as to be actuated byvthe working pressure on the plunger alleled limit switch LS2 and the blade 82A of the solenoid S2. The blade S2A and the limit switch LS2 are connected together and thence through the limit switch LSI are connected with the junction point 54. The solenoid S3 is adapted to close the blade 83A to complete a circuit from the line 5| through the valve solenoid S4 to the line 5|. A wire 51 connects from between the switches 52 and 53 to a point between the switch LS3 and the blade CI for a purpose which will become more apparent hereinafter.

Operation Assume that the press occupies the position shown in Figure 1, that is, with the plunger fully retracted. A working stroke of the press is instituted by energizing the solenoid S| by depressing the start button 53. Closure of the button 53 completes a circuit through the solenoid S| through the limit switch LS4, the pressure switch Tl, the limit switch LS3, the push button 53, the reverse button 55 and the temperature switch 56 to the line 5|. When the solenoid SI is energized the blades SI A close and thus establish a holding circuit permitting the push button 53 to be released.

Simultaneously with the energization of the solenoid S|,'the solenoid S2 is energized and opens the blades S2A. However, since the limit switch LSI serially connected with the blades SZA was previously opened by the platen, the energization of the solenoid S2 is not immediately efiective.

After the press platen has advanced into and accomplished the work to be done thereby, the solenoid SI is deenergized either through actuation of the pressure switch 'I', the actuation of the limit switch LS4 or the actuation of the push button switch- 55, and the pump |3 shifts to direct fluid to the retraction chamber of the cylinder l0. Simultaneously with the deenergization of the solenoid SI, the solenoid S2 is deenergized thereby permittin the blade 82A to close. Closure of the blade S2A establishes a circuit through the solenoid S3, and the limit switch LSI to the junction point 54 and thence through the switches 55 and 55 to the line 5|.

Energization of the solenoid S3 closes the blade 83A and energizes the valve solenoid S4 so as to shift the valve 42. The shifting of the valve 42 directs pilot fluid from the pump 44 through the conduit 40 to the pilot cylinder 38 thus shifting the valve 31 to direct pressure fluid from the pump 36 to the conduit 41; The pressure fluid delivered to the conduit 41 passes through the check valve 48 and the conduit 35 into th passage and thence to the advancing area of the plunger 3|. Thus, substantially simultaneously with the deenergization of the solenoid SI, actuating fluid is conducted to the advancing side of the strip ping plunger 3|.

.valve 2| while simultaneously relieving the pressure in the advancing chamber through the conduit 22 and the valve 2 I. After a predetermined reduction of the pressure in the advancing chamher, the aforementioned bypass is closed off and the retraction stroke of the plunger Ii com-- stripping is thus accomplished without any delay.

The limit switch LS2, which is connected in parallel with the blade SZA, is adapted to energize the solenoid S3 during the retraction stroke of the platen l2 should it be desired to accomplish the stripping of the workpiece in this manner. It will be apparent, however, that the delay in the actuation of the plunger when the same is controlled by the limit switch LS2, is suflicient to permit the platen l2 to be retracted from the stationary die member so that the workpiece, when ejected, is likely to fall through a distance which may be sufiicient to produce harmful effects. Accordingly, it is preferable to actuate the stripping plunger by means-of the solenoid S2 and the contact blade SZA. I

During the retraction stroke of the plunger l I, the stripping plunger 3| is in its lower position. When the platen reaches its uppermost position a cam carried by the platen engages and opens the limit switch LSI thus deenergizing the solenoid S3. Deenergization of the solenoid S3 permits the blade S3A to open thus deenergizing the solenoid S4. With the solenoid S4 deenergized the spring 43 shifts the valve 42 to direct pilot fluid through the conduit 4| to the pilot cylinder 39 of the valve 37, shifting the latter to direct the discharge from pump 36 through the conduit 45 and into the advancing chamber of the cylinder Ill. The fluid thus directed to the said advancing chamber is discharged, when the press stands idle, through the surge valve i9 and into the tank l8. Shifting of the valve 37 also connects the conduit 41 with the inlet side of the pump 36 whereupon fluid within the chamber above the stripping plunger 3| is withdrawn slowly through the conduit and the choke valve 49 to retract the stripping plunger within the main 6 plunger. The space below the stripping plunger receives liquid upon retraction of the plunger by way of the choke l3. passage 32 and the retracting area of the main plunger.

During the advancing stroke of the plunger l I the discharge from the pump 36 is effective to augment the speed of advance ,of the plunger ll.

Full automatic cycling of the press may be had by locking the button I2 closed. This energizes contactor solenoid C and closes the blades CI. The, when the press platen reaches its Figure 1 position and closes the limit switch LS3, the solenoids SI and S2 are automatically re-energized to commence another advancing stroke of the platen.

It will be apparent that various modifications may be made in the structural arrangement of this invention without in any way departing from the spirit of the invention, and, accordingly, it is desired to comprehend such modifications as may be considered to come within the scope of the appended claims and the invention.

Having thus fully described our invention, what we claim as new and desire to secure by Letters Patent is: a

1. In combination in a drawing press, a fluid operable drawing plunger, a fluid operable ejector plunger, a source of pressure fluid for supplying actuating fluid to said drawing plunger, a first control means effective when actuated to bring about the advancing stroke of said drawin plunger, a source of pressure fluid for supplyin actuating fluid to said ejector means, a second control means effective when actuated to bring about the advancing strokeof said ejector plunger, means interlocking said control means to prevent the actuation of the second thereof when the first thereof is actuated, and means responsive to a predetermined advancing movement of said drawing plunger for simultaneously rendering ineffective said first control means and for actuating said second control means.

2. In combination in a hydraulic press, a drawing plunger having fluid operable advancing and retracting means associated therewith, an auxiliary ejector plunger carried by said drawing plunger and having fluid operable advancing and retracting means associated therewith, means hydraulically connecting the retracting means of said drawing plunger with the retracting means of said ejector plunger, a reversible pump connected with said'drawing plunger for Supplying actuatin fluid thereto, means continuously urging said pump into position to deliver to said retracting means of said plunger, electrical means effective when energized to position said pump to deliver to said advancing means of said drawing plunger, an auxiliary fluid source connected with the advancing means of said ejector plunger, electrical control means effective when energized to permit the supply of fluid from said fluid source to said ejector plunger, an electrical circuit connected vwith said flrst mentioned electrical means and adapted selectively to be energized to bring about the advancing stroke of said drawing plunger, a second electrical circuit connected with said second mentioned electrical means adapted when energized to bring about the advancing stroke of said ejector plunger, and means including a contactor connected in parallel with said first mentioned electrical means for permitting the energization of said second mentioned electrical means simultaneously with the deenergization of said first mentioned electrical means.

3. In combination in a drawing press, a drawing plunger having fluid operable advancing and retracting areas associated therewith, a reversible pump connected with said areas and selectively operable to supply actuating fluid to one or the other, means normally positioning said pump to deliver to said retracting area and a solenoid adapted when energized to position said pump to deliver to said advancing area, a bore in said plunger, a reciprocable ejector plunger mounted in said bore and having fluid operable advancing and retracting areas associated therewith, an adjustable choke valve having its inlet connected with the retracting area of said drawing plunger and its outlet connected with the retracting area of said ejector plunger, a fluid source connected with the advancing area of said ejector plunger for supplying actuating fluid thereto, valvemeans connected with said fluid source and said ejector plunger and normally positioned to exhaust said ejector plunger, electrical actuating means for actuating said valve to bring about the supply of fluid from said fluid source to said ejector plunger advancing means, means for energizing said solenoid to bring about the advancing movement of said drawing plunger, means parallelly connected with said solenoid and operable when energized to prevent the energization of said electrical actuatin means, means for deenergizing said solenoid at the conclusion of the working stroke of said drawing plunger, means operable simultaneously therewith for energizing said electrical actuating means, and means operable at the conclusion of the retraction stroke of said drawing plunger for deenergizing said electrical actuating means.

4. In combination in a drawing press, a fluid operable drawing plunger, a fluid operable ejector plunger carried by said drawing plunger, a-first source of pressure fluid for supplying actuating fluid to said drawing plunger, a first electrical control means effective when energized to bring about the advancing stroke of said drawing plunger, a second source of pressure fluid for supplying actuating fluid to said ejector plunger, a second electrical control means efiective when energized to bring about the advancing stroke of said ejector plunger, means selectively operable for energizing said first control means, a contactor having a normally closed blade serially connected with said second control means con- 4 nected with said first control means so as to be energized simultaneously therewith, means operable at the conclusion of the working stroke of said drawing plunger for deenergizing said first control means and also said contactor, the deenergization of said contactor being adapted to bring about the energization of said second con- 'trol means, and means including a normally closed limit switch serially connected with said second control means for bringing about the deenergization thereof when said drawing plunger has completed its retraction stroke.

5. In combination in a drawing press, a double acting drawing plunger, a double acting ejector plunger carried thereby, a first source of pressure fluid connected with said drawing plunger for supplying actuating fluid thereto, a first electrical control means adapted when energized to bring about the supply of fluid from said first fluid source to the-advancing side of said drawin pl n r, means including an adjustable choke valve hydraulically connecting the retracting side of said drawing plunger wtih the retracting side of said ejector plunger, a second source of pressure fluid for supplying actuating fluid to the advancing side of said ejector plunger, a second electrical control means effective when energized to permit the supply of pressure fluid from said second source to the advancing side of said ejector plunger, an adjustable choke valve serially arranged between said second source and said ejector plunger, means for energizing said first control means to bring about the working stroke of said drawing plunger, means operable at the conclusion of said working stroke for deenergizing said first control means to bring about the retracting stroke of said drawing plunger, and electrical means associated with said second control means for preventing the energization thereof during the advancing stroke of said drawing plunger or when said drawing plunger is in its retracted position.

6. An electrical control system for controlling the movements of a drawing plunger and an ejector plunger in a drawing press which comprises a first electrical means adapted when energized to bring about the working stroke of said drawing plunger, a second electrical control means adapted when energized to bring about the ejecting stroke of said ejector plunger, a contactor adapted when deenergized to permit the energization of said second control means and when energized to prevent the energization of said second control means, said contactor being adapted to be energized and deenergized simultaneously with said first control means, whereby the deenergization of said first control means at the end of a working stroke of said drawing plunger is efiective substantially instantaneously to permit the energization of said second control means.

7. In combination, first and second double acting plungers, fluid pressure supply means for said plungers, first control means for said first plunger movable into a first and a second position for bringing about a supply of fluid to said first plunger in its advancing and retracting movements, respectively, second control means for said second plunger movable into a first and a second position for bringing about the supply of fluid to the advancing area of said second plunger or for exhausting said advancing area, respectively, yielding means continuously urging said control means toward their second positions, first and second electrical means energizable for moving said first and second control means, respectively, into their first positions, other electrical means energizable simultaneously with said first electrical means for interrupting the circuit to said second electrical means and de-energizable simultaneously with said first electrical means to reestablish the circuit to said second electrical means, and switch means responsive-to the movement of said first plunger into its fully retracted position for interrupting the circuit to said'second electrical means.

8. In-a drawing press having a drawing plunger and an ejector plunger, a first electrical means energizable to bring about the working stroke of said drawing plunger and de-energizable to bring about the retracting stroke of said drawing plung-' er, a second electrical means energizable to bring about the ejecting stroke of said ejector plunger and de-energizable to bring about the retracting stroke of said ejector plunger, normally closed switch means in circuit with said second electrical means, means connected in parallel with said first electrical means and operable when energized to open said switch means, and other switch means in circuit with said second electrical means and positioned to be opened by said drawing plunger in its fully retracted position.

9. In combination in a drawing press, a drawing plunger and an ejector plunger each having advancing and retracting means, first electrical means energizable to bring about a supply of fluid to the advancing means of said drawing plunger and de-energizable to bring about a supply of fluid to the retracting means of said drawing plunger, second electrical means energizable to bring about a supply of fluid to the advancing means of said ejector plunger and de-energizable to bring about the exhaust of the advancing means thereof, a circuit interlocking said electrical means whereby the de-energization oi the first thereof substantially instantaneously energizes the second thereof, switch means actuated by said drawing plunger in its fully retracted position for de-energizing said second electrical means, and'channel means connecting the retracting means 01' said plungers.

10. In combination in a drawing press, a drawing plunger and an ejector plunger each having advancing and retracting means, first electrical means energizable to bring about a supply of fluid to the advancing means of said drawing plunger and de-energizable to bring about a supply of fluid to the retracting means of said drawing plunger, second electrical means energizable to bring about a supply of fluid to the advancing 11. In combination in a drawing press, a draw ing plunger and an ejector plunger each having advancing and retracting means, first electrical means energizable to bring about a supply of fluid to the advancingmeans of said drawing plunger and de-energizable to bring about a supply of fluid to the retracting means of said drawing plunger, second electrical means energizable to means, restricted channel means connecting the means of said ejector plunger and de-energizable retracting means of said plungers, and means restricting the exhaust of fluid from the advancing side of said ejector plunger,

WALTER ERNST. CLYDE HEDRICK.

narnaancas crran The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,747,463 Booth .I Feb. 18, 1930 1,930,565 Rode Oct. 17, 1933 2,062,196 Stacy Nov. 24, 1936 2,078,749 Wood Apr. 2'7, 1937 2,173,358 Ernst Sept. 19, 1939 2,200,998 Schnuck May 14, 1940 2,267,644 Ernst Dec. 23, 1941 2,280,849 Pocock Apr. 28, 1942 2,303,628 Geiger Dec. 1, 1942 2,307,544 Robinson Jan. 5, 1943 2,347,272 L0 8fleld Apr. 25, 1944 2,360,007 Muller Oct. 10, 1944 2,363,760 Waldie Nov. 28, 1944

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