HYDRAULIC DIE CUSHION DEVICE OF PUNCHING HYDRAULIC PRESS OF STEPPED FORGING

摘要

PURPOSE: To provide an optimum die cushion device for a punching press of a stepped forging. ;CONSTITUTION: A piston rod 3 which is elevatably penetrated in a die 1 which is stepped and provided with a through hole 13 and in a bolster 2 where the die is loaded and a through hole 22 is provided consists of an upper rod 31, a piston 32 and a lower rod 33. Oil chambers A, B, C connected to a hydraulic cushion circuit to control the position of an upper end surface 35 of the piston rod in the range below the upper surface 21 of the bolster in the lowest level, and in the range where the forging is pushed up higher than the upper surface of the die in the highest level are provided in the cylinder 4 which is lowered/ elevated in an integrated manner. Thus, the position of the tip of the piston rod is adjusted by the relatively simple combination of mechanical members difficult to cause failures, and three points of the knock-out point, the starting point of the cushion effect, and the die exchanging point are specified, and the intensity of the cushion pressure can be controlled. The stepped punching and forging becomes possible, the productivity is greatly improved, defects are reduced, and the effect to improve the yield is remarkable.;COPYRIGHT: (C)1995,JPO