Invention Grant

Die cushion device
Abstract:
There is provided a die cushion device that includes a cushion pad, a hydraulic cylinder configured to lift the cushion pad, and a hydraulic closed circuit connected to a die cushion pressure creation chamber of the hydraulic cylinder. The hydraulic closed circuit includes a pilot drive type logic valve that is operable as a main relief valve at the time of the die cushion operation, and a pilot relief valve configured to create pilot pressure for controlling the logic valve. Hydraulic oil is filled in the hydraulic closed circuit, in a pressurized manner, and the hydraulic oil in the hydraulic closed circuit is pressurized by only die cushion force applied from the cushion pad through the hydraulic cylinder, in one cycle period of the cushion pad.
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