METHOD FOR CONTROLLING RAM SPEED OF PRESS MACHINE

摘要

PURPOSE:To obtain a method for controlling the ram speed of a press machine which can move easily the ram and does not affect adversely factory hygiene by using an electrical signal to command the vertical movement of the ram and the ram speed. CONSTITUTION:Upper and lower dies are respectively attached to the frame 3 and ram 5 of a press machine 1 and the ram 5 is moved upward or downward to bend a plate material. An electrical signal is obtd. from a potentiometer 23 when a foot pedal FP of a foot pedal device 27 is pushed. The pedal FP for ascending and descending is provided and a selector switch 25 which judges either of ascending or descending is interposed. A meter 23 is used as a detector for the rate and position at and where the pedal FP is treaded. The signal through the switch 25 enters a controller 27 having an amplifier part, feedback control part and slow down control part which applies the control signal to an electromagnetic proportional unloading valve 29. The pressurizing oil from a hydraulic pump P is controlled in pressure by the valve 29 and is fed to a driving means 21 which moves upward or downward the ram 5. The valve 29 can thus be controlled to open or close in proportion approximately with the treading rate of the pedal FP and the ram speed can be controlled according to the degree of the opening or closing thereof.