US2636433A

US2636433A - Control device for hydraulic presses

Info

Publication number: US2636433A
Application number: US90363A
Authority: US
Inventors: Wennberg Olov Carl Gustav
Original assignee: Svenska Flygmotor AB
Current assignee: GKN Aerospace Sweden AB
Priority date: 1946-03-13
Filing date: 1949-04-29
Publication date: 1953-04-28
Anticipated expiration: 1970-04-28

Description

.April 28, 1953 o. c. G. WENNBERG 2,636,433

y CONTROL DEVICE FOR HYDRAULIC PRESSES Filed April 29, 1949 Patented Apr. 28, 1953 CONTROL DEVICE FOR l HYDRAULIC PRESSES'- i Olov Carl Gustav Wennberg, Karlstad, Sweden, assignor to Svenska, Flygmotor Aktiebolaget, Trollhattan, Sweden, a corporation of Sweden :Application April 29, 1949, serial No. 90,363 I In Sweden March 13, 1946 2 Claims. (C1. 10U-48) s 1 The present invention relates to platens for hydraulic presses, particularly presses of the type operating at a high pressure and requiring a great accuracy as to the correct engagement betweenl the usually large press platens, a stationary one and a movable one, and the articlev to be pressed therebetween. More specifically the invention may be adapted to presses for stamping matrices.

The movable press platen can be caused to press in an oblique position, i. e. a position in which it is not parallel with the stationary platen, for example, by an article of any kind being located at the margin of the platen, whereby in case of high pressures the accuracy of the press- -ing operation can be entirely jeopardized, if there is no protection against the consequence of the nonuniiorm pressing. An object of the invention is to provide means, by which said disadvantages may be avoided and by which a correct self-adjustment of the movable platen relatively to the stationary one can be obtained.

A further object of the invention is to provide means, by which the pressing operation may be immediately interrupted at an initiation to an oblique position of the movable platen as a consequence of an uneven load, whereby the platen is prevented from pressing in an oblique position.

A still further object of the invention is to provide means permitting universal adjustment of the movable press platen relatively to the press plunger and to provide spring means of such a nature as to tend to keep the platen in a position correct for the pressing operation.

The 'invention will be more particularly described hereinafter and illustrated by way of example in the accompanying drawing in which:

Fig. 1 is a front elevation of the press, the lower parts being shown in a vertical section, and

Fig. 2 is a horizontal section along the line II-II in Fig. l and illustrates a top view of the movable platen.

In the drawing, I designates the press platen mounted stationary in the frame of the press, 2 being the movable platen having a spherical bearing 3 seated and universally movable in a corresponding spherical seat 4 in the press plunger 5, which is vertically reciprocable in the press cylinder or frame B. A pressure conduit 1 extends from a pump such as a screw pump or gear pump 'la driven by an electric motor 1b to the press chamber 8, a packing 9 being conventionally mounted between the walls of the chamber 8 and the plunger 5. An outlet branch 'lc comprising an operating valve 'Id extends from the conduit 1, and the pump has an inlet pipe 1e. Four helical springs I I-are mounted between the platen 2,

which is square in the present case, and a correspondingly square portion I0 made integral with the press plunger 5. yThe springs are located in theproximity of the corners of the platenas shown in the drawing, i. e. at a considerable dis-5 tance from the centre of the table, whereby the springs are made very sensibly responsive to a possible movement of the platen to an oblique position, i. e. to deviations of the platens from their correct parallel position. Each spring I I is seated in recesses I Ia, I Ib in the platen 2 and in the portion I0 projecting from the press plunger. Each spring II is mounted on a bolt I2 having a head I3 engaging the top of a ring I4, which forms an upper support for the spring, the lower end of which is seated on a shoulder I5 in the bottom of the recess I Ib. Screwed up on the lower screw-threaded end of the bolt I2 to engagement with the bottom of the portion I0 are nuts I6 by which the prestrain of the spring, as mentioned above, may be adjusted. Below each bolt I2 is a switch I'I supported by the cylinder 6 or frame and coupled in the circuit of operation of the press. There are four switches Il (indicated by block diagrams in Fig. 1) coupled in series by leads I8, I9 the former of which is connected to one terminal 2li of the motor 'Ib and the latter to one terminal of a source of current 2|, a further lead 22 connecting the other motor terminal 23 to the other terminal of the source of current 2 I. The switch has an operating portion 24 adapted to be actuated by the bolt and being located in alignment therewith in the proximity of the end thereof.

In operation the pump 'Ia delivers pressure me-f dium such as oil to conduit 'I and chamber 8, valve ld being closed. The plunger 5 rises and moves the press platen 2 toward the press platen I, thereby compressing the work. Should the press platen 2 tilt, one or more of the bolts I2 will be displaced, and as a result the corresponding switch or switches are actuated to cause an interruption of the circuit controlling motor 1b. After such circuit interruption and following the stop of the pressing operation the press chamber 8 is emptied from pressure liquid by opening valve ld, whereupon the springs II will be able to restore the platen 2 to a position which is correct for the future pressing operation.

The detailed construction of the device may of course be changed without departing from the principles of the invention.

What I claim is:

1. A control device for a hydraulic press comprising a press plunger, a press platen cooperating with the plunger to contact centrally with the plunger. said plunger and platen having a central spherical bearing whereby the plunger and platen Vwill have relative tilting movement, a plurality of switches-1t` arranged rxoncentrallyifrelativetoA the press plunger land platen, means tos'upplyhydraulic pressure fluid to the plunger which is in to said means to thereby interrupt the flow of pressure fluid to the plunger; and. anboltfsur-' f rounded by a pre-strained springoreaclz-'switchf with the bolt contacting the pressfpl'ateriant'the` switch, said spring being interposedl between-the:

platen and plunger. Y v

2. A control device for a hydraulic press com,- prising .a press plunger, a press platen cooperating with the plunger to contact centrally with the plunger; said Vplunger and' yplatenhavinga een trai' spherical bearing whereby Vthe"plunger-and platen will 'have relative-tilting movement, a plurality ofswitches arranged nonecentrally relatveto the press plunger and platen, means'to supply hydraulic pressure -fluid to the plunger which is in electrical connection with the switches so that when the press platen tilts relative to the plunger one of the switches will be operative relative to said means to thereby interrupt ,.theiflowf of pressure-fluidf'tof the plunger, and a. bolt surrounded by a ,spring for' each switch with the spring pre-strained between the press platen and the plunger, the bolt being interposed betweenatheswitch and the platen, said plunger being substantially rectangular with a switch provided in each corner.

` OLOV CARE GUSTAV WENNBERG.

RefrenccsfCited-'in the le of this patent UNITED STATES PATENTS Number Name Date 610,524: Cleveland Sept. 13, 1898 1,932,556 Meranda Oct. 31, 1933 Y 2,309,944- Flowers Feb.. 2, ,1943 2,343,167 .Bench -Feb 29,19%l

FORFHGNTPATENTS Number Country Date 253,735' Germany; Nov.' 15,1912