Patent ID: 8915181

Claim:
A press load controlling apparatus for a mechanical press, comprising: a cylinder-piston mechanism provided in a slide of the mechanical press, the slide having one part of a die and being configured to move the one part of the die toward another part of the die to shape a workpiece; a relief valve configured to act when a pressure of a hydraulic pressure chamber of the cylinder-piston mechanism exceeds a set overload pressure; a hydraulic pump/motor connected to the hydraulic pressure chamber of the cylinder-piston mechanism; an electric servomotor connected to a rotating shaft of the hydraulic pump/motor; a pressure detecting device configured to detect the pressure of the hydraulic pressure chamber of the cylinder-piston mechanism; a pressure commanding device configured to command the pressure of the hydraulic pressure chamber on a basis of a preset press load command; and a controlling device configured to control a torque of the electric servomotor on a basis of a pressure command from the pressure commanding device and the pressure detected by the pressure detecting device, to thereby control the pressure of the hydraulic pressure chamber of the cylinder-piston mechanism.