GB1399308A - Bending press - Google Patents

Abstract

1399308 Bending presses G PICCINI 12 Sept 1973 [14 Sept 1972] 42902/73 Heading B3E [Also in Division B5] A bending press comprises a stationary lower beam 2 carrying a lower tool 8 and a reciprocable upper beam 3 carrying an upper tool 6 with at least one of the tools being supported by pistons 10 of a plurality of vertical hydraulic supporting cylinders 11 fastened on the respective beam and distributed uniformly over the length of the press, and means for bringing the cylinders into communicatoin with each other to form a closed hydraulic system. A support plate 9, which is resilient and flexible, may be interposed between the pistons and the tool 8 and is joined to the tool carrier bed 7 using bolts 12. The upward displacement of each piston is limited by a fixed stop (13), Fig. 4 (not shown), which co-operates with a lateral shoulder on the piston and each piston has a central vent bore (16) which is closable using a ball valve (15) and screw (17). The individual cylinders 11 are connected together by pipes 18 and a common connecting pipe 19. They are also connected to a reservoir cylinder 21 by way of non-return valves 24 interposed between shut-off valves 23 in pipe 19. An adjustable safety pressure release valve 26 is provided in pipe 25 and has an outlet 126 to a chamber 121 filled with hydraulic fluid. A pneumatic adjusting cylinder 30, connected to a source of compressed air via pipe 36, is used to move pistons 230, 221 to pressurize the hydraulic fluid. When a workpiece 37 is being bent, any variations in workpiece thickness and/or any deflection of the beams is accommodated by the cylinders 11. The cylinders can be individually disconnected to allow bending of workpieces which do not extend the full length of the press and also they can be maintained in position for series production of workpieces 37 under constant conditions by closing the valves 23 after the first working stroke of the press.