HYDRAULIC DRIVE FOR PRESS Russian patent published in 1997 - IPC

FIELD: plastic working of metals. SUBSTANCE: drive has working hydraulic cylinder 1 and return hydraulic cylinders 2 with plungers 3,4 connected to movable cross-piece 5. Decompression device 6 is positioned outside working hydraulic cylinder 1. Movable separating member of decompression device has two pistons 7,8 extending between liquid and gas cavities 9,10. Gas cavity 10 may be hermetically locked. Stems 11,12 of pistons 7,8 are interconnected through mechanical transmission 13 providing for correspondence of lower transmission ratio value to higher value of coordinate of piston 7 of liquid cavity 9, with coordinate being read from position of piston 7, at which liquid cavity 9 has minimum volume. Working cavity 14 of hydraulic cylinder 1 is communicated through hydraulic line 16 and inlet valve 17 with high-pressure working liquid source 18 and through filling line 19 and filling-drain valve 20 with filling unit 21. Working cavity 14 of hydraulic cylinder 1 is communicated through controlled valve 22 with liquid cavity 9 of decompression device 6. Press drive has pressure relay 23 connected to working cavity 14 of cylinder 1 and adapted to control additional drain valve 20. Mechanical transmission 13 has sensor 24 for directing motion of piston 7 with stem 11 controlling operation of valve 22. According to other version, liquid cavity 9 of decompression device 6 is connected through additional controlled valve with filling line 19 at inlet of filling-drain valve 20. EFFECT: increased efficiency and enhanced reliability in operation. 7 cl, 2 dwg