PURPOSE: To accurately control the hydraulic pressure of the actuator of pressurizing cylinder, etc., of the hydraulic press in this invention.
CONSTITUTION: In order to control the actuator of the pressurizing cylinder 2, etc., of the hydraulic press 1, a pressurizing flow control valve 3 and a pressure reducing flow control valve 6 are arranged parallely on this hydraulic pressure controlling circuit. And either of the pressure, position and speed of the actuator side are detected by a pressure detector 8, a position detector and a speed detector, and the pressure, position and speed corresponding to detected values are set, the deviation between the set values and the detected values are calculated, if the deviation is a positive value, the fluid instruction by the quantity part corresponding to the deviation is outputted to the pressurizing flow control valve 3, if the deviation is a negative value, the fluid instruction of the quantity corresponding to the deviation is outputted to the pressure reducing flow control valve 6, so the actuator is driven and controlled.
UCHIDA KIKUO
KAWAMOTO HARUICHI
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