Hydraulic cushioning system for press, having hydraulic power supply including means for adjusting initial pressure to be applied to pressure-pin cylinders

摘要

A hydraulic cushioning apparatus for a press having an upper and a lower die assembly (3, 9) for forming a sheet-like workpiece (6), including hydraulic cylinders (54) incorporated in one of the upper and lower die assemblies, and pressure pins (52) linked with the respective hydraulic cylinders. The pressure pins are reciprocable to apply a cushioning force (F) to the workpiece, in a pressing action of said die assemblies on the workpiece, so as to force the workpiece against the other die assembly. The apparatus is equipped with a hydraulic power supply device (72, 100, 117, 272) for delivering a pressurized fluid to the hydraulic cylinders (54). The power supply device is capable of changing an initial hydraulic pressure (P0) of the fluid to be applied to the hydraulic cylinders before the pressing action of said die assemblies.