Method for controlling driving of a ram of a hydraulic cylinder of a hydraulic press equipment

摘要

It is possible for the present invention to operate with the optimal control to prevent a ram from overshooting in a case that a load acting on the ram is decreasing rapidly, like a stamping machining process. Linking a hydraulic circuit which consists of a hydraulic pump 3 and a hydraulic cylinder 2 to make the ram 1 for the hydraulic press equipment move upward and downward and a full-bridge hydraulic circuit with four proportional sheet valves V1 through V4, the working timings of the proportional sheet valves V1 through V4 are controlled by a NC controller 9. In the normal operation, operating the proportional sheet valves V2 and V3 with the turn-on-off control system and with the meter out control system, oil pressure PU acting on the upper chamber 2U of the hydraulic cylinder 2, driving the ram 1 by the piston 10 moving downward, a work is stamped out. The NC controller 9 detects the running by inertia of the ram 1 in the instance of having stamped out a work in the stamping out machining process. As soon as the NC controller 9 detects the rapidly large speed fluctuation by a speed detecting sensor, the NC controller 9 commands the pilot valve 8 of the proportional sheet valve V1 in order to prevent the running by inertia of the ram 1 by controlling the back pressure PL of the lower chamber 2L of the hydraulic cylinder.