US2190755A - Hydraulic press - Google Patents

Description

2 Sheets-Sheet 1 h. w. DINZL amnwmc PRESS Filed March 6, 1937 &

Feb. 20, 1940. I

INVENTOR Eacrmzn W DINZL 2 Sheets-Sheet 2 R. W. DINZL HYDRAULIC PRESS Filed March 6, 1937 Feb. '20, 1940.

Patented Feb. 20, 1940 2,190,755 HYDRAULIC PRESS Richard W. Di'nzi, Nan-berth, Pa., assignor, by

mesne assignments, to

The Baldwin Locomotive Works, a corporation of Pennsylvania 7 Application March 6; 1937, Serial No. 129,355-

9 Claims.

This invention relates generally to hydraulic presses and more particularly to an improved arrangement of draw and main rams with which improved filling and distributing valves are combined.

In hydraulic presses, particularly high speed presses for sheet metal work, it is desirable to have a relatively small ram-and cylinder for drawing the sheet metal and to have a relatively large ram and cylinder to effect the final pressing action. Various arrangements have heretofore been suggested and used but the same have involved structural and operating complications and expense, it being understood that these factors are of considerable importance in presses of large capacity where the presses may be of large physical size and ponderous weight.

It is an object of my invention to provide an improved arrangementof draw and main rams in combination with an improved combined filling and distributing valve mechanism.

Another object is to provide improved control and operating means for the combined filling and distributing valve mechanism especially when the valve mechanism is employed in combination with my improved draw and main ram arrangement.

Other objects and advantages will be more apparent to those skilled in the art from the following description of the accompanying drawings in which:

Fig. 1 is a digrammatic elevation of a hydraulic press employing my improvements;

Fig. 2 is an enlarged vertical section showing a portion of the cylinder, rams and filling tank together with my improved filling and distributing valve mechanism and its control;

Fig. 3 is a fragmentary sectional view of the combined distributing and filling valve shown in an intermediate position during its upward movement.

In the particular embodiment of the invention such as is disclosed herein merely for the purpose of illustrating one specific form among possible others that the invention might take in practice, I have shown in Fig. 1 a conventional type of press having a base or lower platen l suitably supporting an upper crosshead 2 through side columns or tie rods 3. A movable platen 4 is suitably secured to a main ram 5 which is received in a cylinder 6 supported upon the stationary crosshead. The main ram 5 is hollow to receive a stationary draw ram 1 for effecting a draw stroke of relatively low power compared to the final stroke which is effected by the relatively large main ram 5. Combined with the main and draw ram arrangement is an improved combined check and distributing valve mechanism and operating means therefor disposed partially within a filling tank 8 which is suitably supported upon 5 the upper end of main cylinder 8. The main cylinder, Fig. l, is adapted during a down ram stroke to be supplied from filling tank 8 with low. pressure filling fluid through passages and ports 9 and lfl,.the ports l0 being formedv in a 10 v structure ll formed integral with and depending from a cylinder head I2. Draw ram 1 is suitably secured to the structure H. The passage 9 is controlled by a filling valve l3 having an upward- 1y projecting stem l4 slidably supported in the upper end of a pilot cylinder I5 while the lower end it of the valve stem is slidably supported within draw ram 1. The valve has a cylindrical wall 11 adapted to have a relatively close telescopic lit with the lowerwall portion l8 .of pas- 20 sage 9 thereby to close this passage durlngcertain periods of operation. The lower side of valve I3 is provided with a reduced circular portion l9 whose lower surface is adapted to seat against the upper end of draw ram 1 to cushion 25 the valve at the end of its lower stroke which is the position shown in Fig. 2. The lower stem I6 is of larger diameter than the upper stem II for reasons to be explained later. A passage 20 extends through both stems for communication 30 with a draw ram passage 2| leading to .the lower end of the draw ram cylinder 22 while radiaLports 23 communicate with passage 20. The remaining structure will be readily understood in connection with the-description of the mode of op- 35 eration of the press as a whole. a

Operation In the position of the parts as shown in Fig. 2, it can be assumed that thepress is held by fluid 40. pressure supplied from a' preferably constant speed positivedisplacement pump 24 through a four way reversing valve 25 and thence through a pipe 26 to a pullback mechanism 21. 'Simultaneously pump fluid is supplied, Fig. 1, to a 45 port 28 which is now closed by a pilot piston 29' held in its lowermost position in a manner to be described later. To start the press down, reversing valve 25 is shifted to the left to connect l pullback cylinders to the suction side 30 of pump 50 24 as through pipe 26a, ports 25a and b and valve passage 25c. Simultaneously fluid pressure from the upper end of pilot cylinder 3| is discharged. through a check valve 32 and a pipe 261) to the pump suction preparatory to a subsequent closing to tact oi the die with the sheet material or. other. work piece, a relatively low force will be'created in draw cylinder 22 to close filling valve 3! and move the main ram and platen I downwardly to I The resistance to the draw stroke gradually increases as the drawing oper a' efiect a draw stroke.

tion nears completion, thereby causing pump pressure to increase. The increased pump pressure acts upon the lower end of valve stem 16 and, when the. pressure'reaches a predetermined value, 'it overcomeslthe action oi." a spring and also thepum'p pressure" acting on the upper end of the smaller diameter stem I4, thereby to raise themovablevalve structure l3. As shown in Fig. 2, the cylindrical valve portion l1 enters passage ,I8 before ports 23 move out of the upper end oi the: draw ram-1. Flow of filling fluid to the main cylinder is thereby discontinued and upon further upward movement of the valve structure, ports 23 are uncovered to supply pump pressure through passage 20, ports23 and H) to the main cylinder to increase the pressure therein. 'Ihisfincreased-main cylinder pressure immediately a'ctsfupon theunder side of valve l3 to move the same'to itsfull closed position against the Icornbined'forc'e of the relatively low liquid pressure in filling'tank 8, the spring 35 and the pump pressure onthe top of valve stem' ll. The main ram is thereupon moved downwardly under full pumpfpress'ure acting thereon and also under full pump pressure acting within the draw ram cylinder- 22 to' efiect the finalpress operation. the foregoing down stroke, pressure fluid is supplied irom filli g tank 8 through pipe 30a topumhsuction pipe 30. To reverse the press, valve25 is moved so as to connect the pump discharge pipe 31 to pipes 26 and 261; but fullpump pressure'cannot build up.

in the pullback cylinders 21 because pipe 2661s in communication with an annular rccess 33 in the now raised pilot piston 29, the recess in turn com.- municating with ableed or bypass port 40 leading to filling tank 8. The pump pressure is thereby maintained at a predetermined low value. This low pump pressure is transmitted from recess 39 upwardly through ports H to the upper end 01' pilot'cylinder l5 which pressure together with spring 35 is sufllcient to'movevalve l3 downwardly to open the'same. When valve 25 is first moved to its reversing'position, the main cylin der 6 is initially subjected to the pump suction pressure through'ports 23, passage 20 and pipe 33, although dueto the large volume of. displaced fluid from the main cylinder on the up stroke the pump suction cannot handle it entirely. Also, by maintaining a relatively low pump pressure in the pullback cylinders, the upward force exerted thereby on the main ram as through platenl, will not create a large pressure in the main cylinder. Hence the filling'valve can readily open against this small main. cylinder pressure. As the filling valve moves down; it"finally approaches the upper end of draw ram' 1, but the flat valve shoulder suri'ace l9 will trap sufilcient liquid to provide a cushioning effect as i this liquid is laterally squeezed out between the surfaces. This cushioning eflect is supplemented by having annular passage 39 gradually cut oii port 28, thereby retarding flow 0t actuating fluid to the upper end of pilot cylinder l5. When port 28 is fully cut oil so that bleed port 40 is no longer effective, it is seen that pump pressure can build up to any amount'necessary to raise the pullback mechanism together with the platen and main ram.

From the foregoing disclosure it is seen that I have provided not only a relatively simple, compact and eflective draw and main ram arrangement but have also provided a combined distributing and filling check valve adapted to be brought into complete structural and functional cooperation with my improved ram arrangement in such a manner as to reduce the cost of construction, while still retaining positiveness of operation together with the necessary degree of sensitivity of the operating parts to insure maximum speed. While the general type of pilot cylinder and piston disclosed herein constitutes the invention as set forth in the appended claims.

I claim:

1. A hydraulic press for effecting draw and final pressing operations comprising, in combination, a main cylinder, a hollow main ram having a draw cylinder internally thereof, a stationary draw ram disposed within said draw cylinder and supported bythe outer end of said main cylinder, movable means having a passage therein for initially supplying operating fluid to said draw cylinder, and means for thereafter simultaneously supplying operating fluid through the passage in said movable means to said draw and main cylinders.

2. A hydraulicpress tor efiecting draw and final pressing operations comprising, in combination, a main cylinder, a hollow main ram forming a ,draw cylinder internally thereof, a stationary draw ram disposed within said draw cylinder and suppor ed by the outer end of said main cyl inder, a fluid passage within said draw'ram for conducting operating fluid to the draw cylinder, a movable element provided with a passage internally thereof and having coaxial telescopic engagement with said draw ram and communicating with said fluid passage, and means providing a port controlled by relative slidable movement between said passage element and draw ram for supplying operating fluid to said main cylinder.

3. A hydraulic press for effecting draw and final pressing operations comprising, in combination, a main cylinder, a hollow main ram having a draw cylinder internally thereof, a stationary draw ram disposed within said draw cylinder and supported by the outer end of said main cylinder, a fluid passage within saiddraw ram for conducting operating fluid to the draw cylinder, a movable element provided with a pasmeans associated with saiddraw ram for controlling the opening and closing of said radial ports upon movement of said passage element whereby operating fluid is adapted to be supplied solely to the draw ram cylinder when said passage element is in its fully telescoped position with the draw ram and is adapted to supply operating fluid to said main cylinder when the passage element is moved outwardly to uncover the radial ports.

4. A hydraulic press for effecting draw and final pressing operations comprising, in combination, a main cylinder, a hollow main ram having a draw cylinder internally thereof, a stationary draw ram disposed within said draw cylinder and suported by the outer end of said main cylinder, a fluid passage within said draw ram for conducting operating fluid tothe draw cylinder, a movable element provided with a passage and having telescopic engagement with said draw ram and communicating with said fluid passage and adapted when in a certain position to have communication with the main cylinder, and means associated with the upper end of said draw'ram for cooperation with said passage element to prevent said communication with the main cylinder when the passage element is in i'ull telescopic relation with the draw ram thereby to supply operating fluid solely to the draw cylinder, said passage element having communication with said main cylinder upon outward movement of said passage element thereby to supply operating fluid simultaneously to both the draw and main cylinders.

5. A hydraulic press for eiiecting draw and final pressing operations comprising, in combination, a main cylinder, a hollow main ram having a draw cylinder internally thereof, a stationary draw ram disposed within said draw cylinder and supportedby the outer end of said main cylinder, a filling tank, an element having a passage leading therefrom to said main cylinder, a combined distributing and filling check valve comprising a single movable element with a passage internally thereof for controlling said filling passage and sequentially supplying operating fluid through said internal passage to said draw cylinder and then to the main cylinder.

6. A hydraulic press for efiecting draw and final pressing operations comprising, in combination, a main cylinder, a hollow main ram having a draw cylinder internally thereof, a stationary draw ram disposed within said draw cylinder and supported by the outer end of said main cylinder, a filling tank, a communicating passage between said tank and main cylinder, a filling valve adapted to be telescopically received in said communicating passage, a distributing valve operatively associated with said filling valve and adapted to supply operating fluid solely to said draw cylinder when said filling valve is either open or partially closed and to supply operating fluid to the main cylinder when the filling valve is fully closed, means for moving said filling valve into an initial telescopic relation with said communicating passage, and means whereby an additlonal closing force is imparted to said filling valve after said initial telescopic relation is eflected.

'7. A hydraulic press for effecting draw and I final pressing operations comprising, in combination, a main cylinder, a hollow main ram having a draw cylinder internally thereof, a stationary draw ram disposed within said draw cylinder and supported by the outer end of said main cylinder, a filling tank, a communicating passage between said tank and main cylinder, a filling valve formed as an integral part of said element for sequentially distributing operating fluid through said supply passage first to said draw cylinder and then through said supply passage to said main cylinder, means for operating said distributing and filling valves so as to close said communicating passage when operating fluid is supplied to the main cylinder, pullback mechanism, means for supplying operating fluid to said pullback mechanism upon completion of a pressing operation, actuating means for opening said filling valve, and means for maintaining the pullback operating pressure below a predetermined value until said filling valve is open and thereafter permitting pullback pressure to build up to return the press to its initial position.

8. A hydraulic press for effecting draw and final pressing operations comprising, in combination, a main cylinder, a hollow main ram having a draw cylinder internally thereof, a stationary draw ram disposed within said draw cylinder and supported by the outer end of said main cylinder, a filling tank, a communicating passage between said tank and main cylinder, a filling valve for controlling said communicating passage, a distributing valve for controlling supply of operating fluid to said draw and main cylinders, means for operating said distributing and filling valves so as to close said communicating passage when operating fluid is supplied to the main cylinder, pullback mechanism, means for supplying operating fluid to said pullback mechanism upon completion of a pressing operation, actuating means for opening said filling valve, means for maintaining said pullback operating pressure below a predetermined value while said filling valve is being opened, and means for retarding opening movement of said filling valve and simultaneously permitting pullback pressure to build up to return the press to its initial position.

9. A hydraulic press for eflecting draw and,

supply passage, and a unitary element having a, filling check valve for controlling said filling fluid passage and having means controlling distribution of operating fluid through said supply passage to said main cylinder and draw cylinder, said operating fluid supply passage being formedin said unitary element.

RICHARD w. nnvzn.

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