HYDRAULIC PROCESSING MACHINE, HYDRAULIC PRESS BRAKE, AND METHOD OF CONTROLLING THE SAME

摘要

A hydraulic processing machine such as a hydraulic press brake and a shear capable of increasing energy efficiency by reducing the wasteful consumption of power and a method of controlling the processing machine and the press brake. The rotational speed of a pump motor (three-phase induction motor)(15) driving a hydraulic pump (14) is variably controlled by an inverter (24) to control the discharged flow rate of the hydraulic pump (14) to a minimum required for processing work. When a ram (1) is stationarily stopped at an upper limit position, the pump motor (15) is stopped. When the ram (1) is lowered from the upper limit position by its own weight, the pump motor (15) is rotated at the lowest rotational speed. When the ram (1) pressurizes a workpiece (5), the pump motor (15) is rotated at a minimum rotational speed. When the ram (1) is raised, the pump motor (15) is rotated at a maximum rotational speed.