| 摘要 |
PURPOSE:To decrease the copper loss in a motor and driving circuit under light load and to run a press machine with good efficiency by changing the limit value of the current to be conducted to the driving motor in accordance with the work and pressing stroke speed of the press machine. CONSTITUTION:A CPU9 calculates the one cycle period T and pressing stroke speed of a press machine in accordance with the output signal of a rotary cam switch 10 inputted thereto via an input interface 11. The CPU calculates the work of the press machine in the period T in accordance with the output signal S4 of a current detector 6 inputted thereto via an A/D converter 12. The CPU9 calculates such a signal S5 at which the min. limiting current value corresponding to a press duty flows to the armature coil 1a of a motor in accordance with the work and pressing stroke speed of the press machine. Said signal is outputted via a D/A converter 13 in the next one cycle. |
