DEVICE FOR PREVENTING PRESSURE OF HYDRAULIC DIE CUSHION FROM RAISING

PROBLEM TO BE SOLVED: To prevent the impact from generating between a die cushion pin and a die cushion pad at the point of time that upper and lower dies attached on a press machine are begun to draw. SOLUTION: A pressure regulating device is installed on a hydraulic die cushion cylinder 2. This pressure regulating device is composed of a pressure regulating piston 3 and a pressure regulating cylinder 4, etc. At the point of time to begin drawing, when a die cushion pad 1a is rapidly energized downward with a die cushion pin 12, the hydraulic pressure inside the hydraulic die cushion cylinder 2 is made instantaneously to raise because a die cushion compression regulating relief valve 8 can be instantaneously responded. Synchronizing to raising of this hydraulic pressure, the pressure regulating piston 3 is lowered resisting the spring force of a spring 5. So, the pressure inside the die cushion cylinder 2 is not raised largely.