| 摘要 |
A hydraulic machine for operation such as for pressurizing a workpiece and molding products from materials by using a reciprocation mechanism comprising a hydraulic cylinder unit. The cylinder unit comprises two types cylinder chambers having different cross-sectional areas, and a third or plural cylinder chambers. Hydraulic oil sent out from a hydraulic pump driven by a servo motor, is fed through a hydraulic circuit into the cylinder unit. The shifting position of the reciprocation movement is detected, and path switching in the hydraulic circuit and revolving operation of the servo motor are controlled on the basis of the detected shifting position. In case the reciprocation movement is used for pressurizing a workpiece by a die, the hydraulic oil is fed to the cylinder chamber for forward of small cross-sectional area until slightly before the die comes into contact against the workpiece, and the die shifts at high speed relative to a workpiece. Subsequently, the path switching is done to lead the hydraulic oil into the cylinder chamber of large cross-sectional area, and the die moves at a low speed relative to the workpiece.
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