The hydraulic type processed machine, the hydraulic type press brake and the hydraulic type press brake which

摘要

PROBLEM TO BE SOLVED: To improve energy efficiency by reducing wasteful power consumption in a working machine such as a hydraulic press brake or shear.;SOLUTION: The rotating speed of a pump motor (a three-phase induction motor) 15 driving a hydraulic pump 14 is variably controlled by an inverter 24 to minimize the discharge flow rate of the hydraulic pump 14 for the machining operation. When a ram 1 rests still in the upper limit position, the pump motor 15 is stopped. When the ram 1 lowers from the upper limit position by the dead weight, the pump motor 15 rotates at the minimum rotating speed. When the ram 1 pressurizes a workpiece 5, the pump motor 15 rotates at a medium rotating speed. When the ram 1 is raised, the pump motor 15 rotates at the maximum rotating speed.;COPYRIGHT: (C)2007,JPO&INPIT