GB758480A - Improvements in or relating to hydraulic presses and control means therefor - Google Patents

Abstract

758,480. Forging presses. UNITED ENGINEERING & FOUNDRY CO. Feb. 16, 1954 [Feb. 16, 1953], No. 4557/54. Class 83 (4). [Also in Group XXIX] A die-forging press is provided with means for ensuring parallel movement of a platen. A press has a platen 14 movable towards a fixed platen 11 by single-acting pistons. Double-acting pistons 18a, 19a, 21a, 22a for effecting the return movement are provided at the corners of the platen 14 and slide in cylinders fixed to the platen 11. Diagonally opposite pistons 18a, 21a are fixed to racks 18c, 21c which mesh with pinions 18d, 21d, connected to opposite sides of a planetary gear 23. Pistons 19a, 22a in like manner are connected to opposite sides of a similar planetary gear. During a working stroke of the press suppose, for example, the platen 14 tilts so that the corner associated with piston 18a moves more rapidly than the opposite corner. A ring gear 23a of gear 23 is then rotated in such a direction that a valve 29, to which it is operatively connected, is moved to the left. Liquid under pressure is admitted to a chamber 31a and exhausted from a chamber 31b, of a cylinder 31, thus moving a piston 32 to the right. The end 32b of the piston 32 moves further into a cylinder 37 and the pressure above piston 21a and below piston 18a is thus increased and the platen 14 is brought parallel to platen 11. To effect the return stroke of platen 14, valves 53, 54, 55 are adjusted to admit liquid under pressure from an accumulator to the cylinders below pistons 18a, 21a, the liquid above the pistons passing through valves 46, 51 to exhaust.