METHOD OF CONTROLLING HYDRAULIC CYLINDER AND METHOD OF CONTROLLING HYDRAULIC CYLINDER OF PRESS BRAKE AS WELL AS CONTROLLER

摘要

PROBLEM TO BE SOLVED: To provide a method of controlling a hydraulic cylinder which is capable of improving productivity by generating a high pressure in spite of a fluctuation in load and the method of controlling the hydraulic cylinder in a press brake.;SOLUTION: A directional control valve 17 moves to locate a lower table 5L in a command position and the lower table 5L is vertically moved by the hydraulic cylinder 3. There is however a difference between the command position and the actual ram position detected by ram position detecting means 11 and usually a controller 131 controls the directional control valve 17 so as to diminish this difference. In shifting from the fast feed operation of the lower table 5L of the press brake 1 to a pressurization operation, the pressure of the hydraulic cylinder 3 is detected by pressure detecting means 25 and when the pressure rises above the prescribed threshold, the directional control valve 17 is clamped in the pressurization operation position regardless of the amount of the deviation between the command position with respect to the lower table 5L and the actual position of the lower table 5L, by which the pressurization operation is continued.;COPYRIGHT: (C)2002,JPO