| 摘要 |
PROBLEM TO BE SOLVED: To provide a die cushion device which is inexpensive, easily handled and maintenance-free. SOLUTION: The die cushion device is characterized in that, instead of a conventional die cushion device, the die cushion device is provided with a supporting member to hold a blank, a gas pressure cylinder to energize the supporting member upward, a hydraulic cylinder whose upper rod connects with the supporting member, a pneumatic-hydraulic converter for an auxiliary lift having a piston which separates interiors from an oil sac and a gas sac communicating with the oil sac in the rod side of the hydraulic cylinder, a non-return valve which allows oil the flow from the oil sac opposite to the rod to the rod side oil sac, and a drain port communicating with the oil sac in the rod side of the hydraulic cylinder. When a die passes through a bottom dead center, the drain port is closed, and when the die goes to an upper dead center from the bottom dead center, the pressure of the gas sac in the pneumatic-hydraulic converter for the auxiliary lift is lowered and the piston is shifted to the side of the gas sac.
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