| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of thermal fusion of a wire electrode without lowering machining efficiency in electric discharge machining. SOLUTION: A wire-cut electric discharge machine 1 is provided with a wire breakage preventing circuit 11 for preventing the breakage of a wire electrode 2 due to thermal fusion. The wire breakage preventing circuit 11 consists of a voltage detection circuit 12 for measuring voltage between the wire electrode 2 and a workpiece 4, a switching element 15 arranged between the wire electrode 2 and the workpiece 4 and a control circuit 13 for controlling the switching element. The control circuit 13 controls the switching element in such a manner that the switching element 15 is kept in an ON state over a preset bypassing time when voltage measured by the voltage detection circuit 12 does not exceed a lower limit value for normally rising voltage in the course of a monitoring time.
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