GB769308A - Improvements relating to pressure controlling or cushioning appliances - Google Patents

Abstract

769,308. Cupping. BRETTELL, Ltd., T. & J., and CARTER, A. Dec. 23, 1954 [Sept. 26, 1953; Oct. 8, 1954], Nos. 26539/53 and 28994/54. Class 83 (4). [Also in Group XXIX] Means giving a controlled resisting pressure to the downward movement of the draw ring 3 of a press for the cupping of sheet metal articles from blanks, comprises a main ram 2 in a cylinder 1 which during a working stroke of the press forces liquid into an intensifier cylinder 10 to displace a piston 12 connected to a larger piston 15, thus compressing air in a cylinder 16. The air thus compressed serves to restore the displaced liquid to the cylinder 1 when the applied force on the ram 2 is relieved. A oneway throttle prevents too rapid a return of the ram 2. To compensate for leakage from the cylinders 1, 10, the piston 12 has an axial bore 25 containing a stationary piston 26. The space above the piston 26 communicates with a reservoir 29, and the space beneath the piston communicates with the space above the piston 12 through a port 34, bore 33 and non-return valve 35. On a downstroke of the piston 12, the spaces above and below the piston 26 intercommunicate through a passage in the piston 26; on an upstroke of the piston 12, when the passage through the piston 26 is closed by a narrow part of the bore 25, the liquid beneath the piston 26 is forced into the cylinder 10.