GB803041A - Improvements in and relating to hydraulic presses - Google Patents

Abstract

803,041. Stamping. SVENSKA AEROPLAN A. B. Nov. 9, 1956 [Nov. 10, 1955], No. 34275/56. Class 83 (4). In a press for forming sheet-metal blanks 26 between a form 80 and an elastic wall 15 under hydraulic pressure in a chamber 14 to which pressure is applied by a plunger 20 entering the chamber 14 the assembly of the chamber 14, elastic wall 15 and plunger 20 is mounted in a press head 2 which can be raised from the operating position at which it is normally locked. The press-head 2 is slidably mounted on columns 5 and carries a cylinder 19 to which pressure is applied through a pipe 25 connected above a piston 21 to force the plunger 20 into the chamber 14 and deform the elastic wall 15 over the metal blank 26. The press-head 2 is normally locked in the lowered position by split collars 37, 38 surrounding each column 5 and engaging below adjustable nuts 39 which are locked in position by nuts 40 when the cross-head 2 is set at the correct height. For raising the cross-head a pneumatic cylinder 3 attached to the tops of the columns 5 is supplied with compressed air so that its piston 29 lifts the cross-head 2 to which it is attached through a connecting-rod 30. For lowering the cross-head 2 pressure is supplied to an hydraulic cylinder 4 mounted above the cylinder 3 and containing a piston 33 which is coupled to the piston 29 through a connecting-rod 34 and over-rides the pneumatic lifting pressure. The split collars 37, 38 are pivoted on pins 41, 42 and rotated through arm 45 to open and release the crosshead 2. Hydraulic cylinders 36 actuate the arms 45, all of which are coupled together for simultaneous operation through links 46 and a radial armed member 48 which rotates about the link 30. The former 80 is mounted within a tool holder 12 on the press table 1. A blank holding ring 81 surrounds the former 80 and is yieldingly supported by pins 11 resting on a disc 55 engaged by a piston 54 in a cylinder 52 to which pressure is normally applied from an hydraulic accumulator through a line 60 during actuation of the press or to eject the blank 26. If higher pressures are required, a pneumatically actuated valve 66 with an intensifier portion 65 raises the return pressure from the cylinder 52. Locking of the ejection means during a portion of the upward stroke of the press is provided by an hydraulic piston 67 connected to the piston 54 through a rod 58, and held in position when required by a solenoid-operated valve 77 which prevents fluid-flow through passages 70, 71 interconnecting the fluid above and below the piston 67. Specification 771,257 is referred to.