GB730286A - Improvements relating to presses for drawing or bending metal blanks or sheets - Google Patents

Abstract

730,286. Cupping. RHODES, C. J., and RIDGWAY, H. Dec. 12, 1952 [Dec. 13, 1951; June 27, 1952], Nos. 29254/51 and 16309/52. Class 83(4). A cupping press comprises a crank-operated ram device consisting of an inner ram carrying a forming plunger and also a number of cylinders on which pistons are movable against pressure fluid and an outer ram which includes a number of piston rods connected with said pistons and carrying a blank holder, the said piston rods and blank holder being movable with the inner ram during the first part of the working stroke of the ram device but being movable with respect to the ram device against the action of the pressure fluid when the blank holder engages a blank or sheet being worked. The press comprises a slide movable in guides 1 by means of a crank (not shown). The slide has an inner ram 2 carrying a forming plunger 2a and is surrounded by an outer ram constituted by piston rods 6 attached to a blank holder 3 the pistons 5 .(Fig. 2) of said rods working in hydraulic cylinders 4 carried by the inner ram. In operation, when the blank holder contacts the blank on the lower die of the press (not shown) the pistons move upwards, against the fluid pressure in the cylinders which can be regulated by a control valve the setting of which is adjustable. A device for adjusting the control valve comprises a spring - loaded pressure - controlling spindle 11 (Fig. 5), supported in an adjusting nut 13 screwed into an adaptor 14, said nut bearing on a collar 15 on the spindle so that the pressure setting of the valve is manually adjustable. The outer end of the spindle is rounded to form a cam-follower 17 which engages an adjustable cam track 18 on the downward movement of the slide to move the spindle against the spring 12 and so progressively close the control valve to increase pressure on the blank. During the return stroke dogs, or arrester rods (not shown) engage the blank holder to position it for the next working stroke. Oil reservoirs 21 maintain the level of liquid in the cylinders 4. In a drawing press (Fig. 6) fluid pressure cylinders 22 are clamped to both sides of a reciprocating dieholder 23 and'the piston rods forming the outer ram are attached to a pressure plate 24.