To solve the problems that when a punching load is relatively low, electric power is wasted in a general kondorfer start or reactor start of a conventional electric motor for punching device since start torque is large for the load and that even when stalling torque is not necessary on a site where the punching load is relatively low, a power generator having generator capacity which is larger than needed should be prepared for a conventional machine.
A transformer or reactor coil of a punching device is configured to have multiple stages of taps, a multi-stage voltage switching circuit for start from a low voltage is provided to raise a voltage up to a voltage in primary operation, and a conventional type or the multi-stage system type is optionally selected according to a punching load.
TANAKA YUSUKE
KIMURA AKIRA
| JPH0468499U | 1992-06-17 | |||
| JPS58159676A | 1983-09-22 | |||
| JPS5918586U | 1984-02-04 |