US3277691A

US3277691A - Drop forge press or the like with a pressure medium drive

Info

Publication number: US3277691A
Application number: US490527A
Authority: US
Inventors: Beche Hans
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-09-28
Filing date: 1965-09-27
Publication date: 1966-10-11
Anticipated expiration: 1983-10-11
Also published as: DE1292108B; GB1104782A

Description

Oct. 11, 1966 H. BficHE 3,277,691

DROP FORGE PRESS OR THE LIKE WITH A PRESSURE MEDIUM DRIVE Filed Se t. 27, 1965 Dis fn'bufor k 26 I A Hans Bch Time, IN VEN TOR.

BY CKML 3295s 3: 90 Attorney United States Patent 3,277,691 DROP FORGE PRESS OR THE LIKE WITH A PRESSURE MEDIUM DRIVE Hans Bch, 29 Gardelenbergstrasse, Huckeswagen, Rhineland, Germany Filed Sept. 27, 1965, Ser. No. 490,527

Claims priority, application Germany, Sept. 28, 1964,

B 78,693 4 Claims. (Cl. 72-453) This application is a continuation-in-part of my copending application Ser. No. 316,373 filed October 15, 1963.

My present invention relates to a press for forging, stamping or otherwise deforming metallic bodies between dies of which one may be stationary while the other is carried on a fluid-operated ram reciprocably guided on the press frame.

In my above-entitled copending application I have disclosed a press of this character having a ram or tup integral with a piston slidably received in a main cylinder which communicates with an auxiliary cylinder accommodating a fluid-actuated plunger whose effective surface area is a fraction of that of the piston and which, conversely, has a stroke length representing a corresponding multiple of the piston stroke. When this plunger is accelerated to a relatively high speed within its cylinder, it transfers its momentum to the plunger and ram by way of a constant volume of hydraulic fluid present in the two communicating cylinders. The kinetic energy of the plunger is rapidly translated into a forward motion of the ram at a rate greatly exceeding the operating speed of conventional forging presses so that a heated workpiece placed between the dies will not undergo appreciable cooling before being deformed by the ram stroke.

While the system disclosed in my copending application is generally satisfactory, a press so constructed is subject to stresses and vibration resulting from an uncompensated force component acting in the direction of the working stroke of the ram; thus, if R=A/a is the ratio of the effective surface area A of the piston to the effective surface area a of the plunger, a fraction P/R of this pressure will not be absorbed by the walls of the main cylinder but will be propagated as a shock wave through the ram, the dies and the press bed to the foundation of the press frame. It should be understood that this shock wave is distinct from the impact of the ram motion upon the workpiece which is dissipated as a permanent deformation of the latter.

Since in a typical press of this character the driving pressure may be on the order of 1,000 tons, with a piston ratio R equal to about 6 to 8, the force of the shock wave may range between approximately 125 and 175 tons which is not negligible, especially when iteratively generated in rapid succession.

It is, therefore, the principal object of the present improvement to provide means for eliminating the aforedescribed shocks in a press of the character disclosed in my copending application.

This object is realized, in conformity with my present invention, by the provision of two oppositely moving plungers (or sets of plungers) in the auxiliary cylinder, means being provided for symmetrically and concurrently actuating the plungers at substantially equal pressures and speeds so that their otherwise uncompensated force components balance each other with respect to their effect upon the surrounding structure.

Advantageously, according to a further feature to this invention, the auxiliary cylinder extends at right angles to the ram stroke so that residual shocks, resulting from imperfect balance, will not be communicated directly to 3,277,691 Patented Oct. 11, 1966 the workpiece. The invention is particularly applicable to presses with hydraulically driven plungers and, in that case, advantageously provides at least one auxiliary plunger which is positively connected with one of the two working plungers and acts upon a hydraulic fluid in a conduit terminating at the other plunger whereby a forward motion of the first plunger under hydraulic pressure is instantly communicated to the second plunger so as to result in the desired synchronous advance of the working plungers toward each other.

The invention will be described in greater detail with reference to the accompanying drawing whose sole figure constitutes a partly diagrammatic view of -a representative embodiment, the press proper being shown in sectional elevation.

As illustrated in the drawing, a press frame 1 has a bed 12 supporting a stationary die 13 which co-operates with a movable die 14 and a ram 15. The ram 15 is integral with a piston 2 normally withdrawn upwardly into a main cylinder 16 which communicates via a bore 17 with an auxiliary cylinder 18 partly occupied by two horizontally reciprocable plungers 4 and 5. These plung ers are normally retracted into symmetrically opposite positions at the ends of cylinder 18 which perpendicularly intersects the axis of bore 17 coinciding with the direction of vertical reciprocation of piston 2, ram 15 and upper die 14.

Plunger 4 terminates in a head 4a and is provided with a central bore 4b receiving the outlet end of a supply conduct 6 fixedly secured to the wall 3 of cylinder 18. A source of operating fluid is represented by a vessel 20 containing a quantity of hydraulic liquid 21, e.g., oil. A pump 22 continuously withdraws oil from the vessel 20 and, in the inoperative condition of the press, returns it to the vessel 20 via a pipe 23 and a distributor 24 controlled by a timer 25. Conduit 6 extends from distributor 24 so as to be supplied with oil under pressure from pump 22 during the first part of an operating cycle of the timer 25. A further conduit 26 extends from distributor 24 and divides into two

branches

26, 26" terminating at a pair of auxiliary cylinders 11', 11" with pistons 27', 27 bearing from below upon the ram 15; the cylinders 11', 11", which are drained concurrently with the supply of hydraulic fluid to the conduit 6 so that the ram 15 may descend in the performance of a working stroke, are resupplied with pressure fluid in the latter part of the operating cycle of timer 25 to restore the ram to its withdrawn position during a return stroke.

A piston rod 7 rigid with plunger head 4a terminates in an auxiliary plunger 28 which is horizontally reciprocable, in step with working plunger 4, within a conduit 8 whence a pipe 9 extends to the opposite end of a cylinder 18; a tube 10, similar to the discharge end of conduit 6, projects through the head 5a of plunger 5 into a bore 5b of said plunger. Thus, whenever distributor 24 admits oil into conduit 6 to drive the plunger 4 to the right, auxiliary plunger 28 in channel 8 displaces a body of incompressible hydraulic fluid 29 within the conduit system 8-10 so that working plunger 5 is moved at like speed and in the opposite direction (i.e., to the left) toward the bore 17 whereby another body of incompressible hydraulic fluid 30 occupying the passages 16-18 is displaced to exert downward pressure upon the piston 2, the ram 15 and the movable die 14. A workpiece (not shown) positioned between the

dies

13, 14 is thus deformed as the kinetic energy of the plungers 4, 5 is imparted to the slower-moving and more massive piston and

ram

2, 15. The horizontal components of the driving force applied to the two working plungers balance each other so that no uncompensated shock waves will be generated Within the structure.

In order to maintain the space between plungers 4, and piston 2 fully occupied by the body of liquid 30, a reservoir 31 containing a supply of oil 30a communicates with the cylinder 18 via a discharge pipe 32 and an intake pipe 33. Pipe 32 is connected to the high-pressure port of a pump 34 in reservoir 31 and also contains a check valve 35 preventing the return flow of oil from the cylinder to the reservoir. Pipe 33 opens into the reservoir 31 below the level of liquid 30a and has an entrance port 33a in the wall 3 of cylinder 18 located just beyond the working face of plunger 4 when the latter is in its withdrawn position. Pump 34, accordingly, continuously circulates fluid along a closed path 31-32183331 so that the

cylinders

16 and 18 are always filled with oil under pressure. When the plungers 4, 5 start moving inwardly under the control of timer 25, port 33a is immediately obstructed by the advancing plunger 4 so that the liquid is trapped within the cylinders, the check valve 35 preventing any outflow by way of pipe 32. Naturally, a similar fluid-circulating system could also be provided for maintaining the supply of liquid 29 in channels 8-10.

The circulation system 31-35 may also be used to prevent the initiation of an operating cycle by the timer 25 until the plungers 4, 5 and the ram are in their illustrated withdrawn positions. To this end I have shown a conduit 37 branching off the pipe 33 and terminating at a hydraulic relay 38 whose spring-loaded plunger 39 is displaced toward the right by the fluid pressure prevailing in pipe 33 when the port 33a is unblocked. In this condition the timer is enabled and responds to the operation of an actuator, such as a pedal 40, to apply the outflow of pump 22 first to the conduit 6 for the initiation of a working stroke and then to the conduit 26 for the return stroke by suitably shifting the distributor 24. If, however, plunger 39 is displaced to the left by its biasing spring in the absence of a countervailing fluid pressure, the timer 25 is nonresponsive to any operation of pedal 40.

In a typical construction as shown in the drawings, the

cross-sectional area of cylinder 18 may range between about hi to of the cross-sectional area of cylinder 16 so that the hydraulic pressure acting upon the piston 2 will be substantially six to eight times the pressure jointly exerted upon the fluid cushion by the two plungers 4 and 5. Since the piston 2 normally occupies virtually the entire main cylinder 16, its initial acceleration under the pressure of'the fluid in bore 17supplemented by its own weight upon the Venting of cylinders 11', 11"- will be relatively great.

I claim:

1. A fluid-operated press comprising a frame forming a bed adapted to support a first die; a ram reciprocably guided on said frame and adapted to support a second die confronting said first die; a main cylinder rigid with said frame; a piston in said main cylinder integral with said ram; an auxiliary cylinder on said frame communicating with said main cylinder; supply means for maintaining a substantially constant volume of hydraulic fluid in said communicating main and auxiliary cylinders; first and second plunger means confrontingly disposed at opposite ends of said auxiliary cylinder for symmetrical reciprocating motion toward and away from each other, each of said plunger means having a stroke length substantially exceeding that of said piston, the combined effective surface area of said plunger means being a fraction of that of said piston; ram-actuating means including a source of fluid pressure for concurrently driving said first and second plunger means toward each other at substantially equal pressures and speeds, thereby expelling hydraulic fluid from said auxiliary cylinder into said main cylinder and displacing said piston toward said bed; and restoring means operable for returning said piston to a normal position remote from said bed with simultaneous return of said first and second plunger means to normal positions of maximum separation from each other.

2. A press as defined in claim 1 wherein said auxiliary cylinder is disposed at right angles to said main cylinder.

3. A fluid-operated press comprising a frame forming a bed adapted to support a first die; a ram reciprocably guided on said frame and adapted to support a second die confronting said first die; a main cylinder rigid with said frame; a piston in said main cylinder integral with said ram; an auxiliary cylinder on said frame communicating with said main cylinder; supply means for maintaining a substantially constant volume of hydraulic fluid in said communicating main and auxiliary cylinders; first and second plunger means con-frontingly disposed at opposite ends of said auxiliary cylinder for symmetrical reciprocating motion toward and away from each other, each of said plunger means having a stroke length substantially exceeding that of said piston, the combined effective surface area of said plunger means being a fraction of that of said piston; ram-actuating means operable to admit a hydraulic fluid under pressure to said first plunger means for driving same toward said second plunger means; coupling means operatively interconnecting said first and second plunger means for translating the motion of said first plunger means into an opposite motion of said second plunger means at substantially the same pressure and speed, thereby expelling hydraulic fluid from said auxiliary cylinder into said main cylinder and displacing said piston toward said bed; and restoring means operable for returning said piston to a normal position remote from said bed with simultaneous return of said first and second plunger means to normal positions of maximum separation from each other.

4. A press as defined in claim 3 wherein said coupling means comprises conduit means terminating at said second plunger means and auxiliary plunger means positively connected with said first plunger means for exerting pressure upon said second plunger means through a hydraulic fluid in said conduit means.

References Cited by the Examiner UNITED STATES PATENTS 1,007,349 10/1911 Gerdav 259 1,054,194 2/1913 Gerdav 100-269 1,068,243 7/1913 Iversen 100269 1,230,492 6/1917 Kristufek 100 269 2,729,943 1/1956 Clarke 72453 CHARLES W. LANHAM, Primary Examiner. G. P. CROSBY, Assistant Examiner.

Claims

1. A FLUID-OPERATED PRESS COMPRISING A FRAME FORMING A BED ADAPTED TO SUPPORT A FIRST DIE; A RAM RECIPROCABLY GUIDED ON SAID FRAME AND ADAPTED TO SUPPORT A SECOND DIE CONFRONTING SAID FIRST DIE; A MAIN CYLINDER RIGID WITH SAID FRAME; A PISTON IN SAID MAIN CYLINDER INTEGRAL WITH SAID RAM; AN AUXILIARY CYLINDER ON SAID FRAME COMMUNICATING WITH SAID MAIN CYLINDER; SUPPLY MEANS FOR MAINTAINING A SUBSTANTIALLY CONSTANT VOLUME OF HYDRAULIC FLUID IN SAID COMMUNICATING MAIN AND AUXILIARY CYLINDERS; FIRST AND SECOND PLUNGER MEANS CONFRONTINGLY DISPOSED AT OPPOSITE ENDS OF SAID AUXILIARY CYLINDER FOR SYMMETRICAL RECIPROCATING MOTION TOWARD AND AWAY FROM EACH OTHER, EACH OF SAID PLUNGER MEANS HAVING A STROKE LENGTH SUBSTANTIALLY EXCEEDING THAT OF SAID PISTON, THE COMBINED EFFECTIVE SURFACE AREA OF SAID PLUNGER MEANS BEING A FRACTION OF THAT OF SAID PISTON; RAM-ACTUATING MEANS INCLUDING A SOURCE OF FLUID PRESSURE FOR CONCURRENTLY DRIVING SAID FIRST AND SECOND PLUNGER MEANS TOWARD EACH OTHER AT SUBSTANTIALLY EQUAL PRESSURE AND SPEEDS, THEREBY EXPELLING HYDRAULIC FLUID FROM SAID AUXILIARY CYLINDER INTO SAID MAIN CYLINDER AND DISPLACING SAID PISTON TOWARD SAID BED; AND RESTORING MEANS OPERABLE FOR RETURNING SAID PISTON TO A NORMAL POSITION REMOTE FROM SAID BED WITH SIMULTANEOUS RETURN OF SAID FIRST AND SECOND PLUNGER MEANS TO NORMAL POSITIONS OF MAXIMUM SEPARATION FROM EACH OTHER.