Wire electric discharge machine capable of detecting machining state

摘要

A voltage is applied to a machining gap between a wire electrode and a workpiece for a period of one microsecond or less with a quiescent time longer than the duration of voltage application between each two adjacent cycles of voltage application provided, and the number of duty cycles and a machining-gap voltage are detected. An open-circuit state in which electric discharge does not occur after the voltage is applied is identified by the detected machining-gap voltage, and the number of open-circuits is counted. An average machining-gap voltage is obtained based on the numbers of duty cycles and open-circuits and the supply voltage or an average voltage for each duty cycle.

主权项

1. A wire electric discharge machine configured to apply a high-frequency voltage to a machining gap between a wire electrode and a workpiece located at a predetermined distance from the wire electrode, thereby generating electric discharge to machine the workpiece, the wire electric discharge machine comprising:
a voltage application unit configured to apply a bipolar voltage to the machining gap between the wire electrode and the workpiece for a period of one microsecond or less with a quiescent time longer than the duration of voltage application between each two adjacent cycles of voltage application provided; a machining-gap voltage detection unit configured to detect a machining-gap voltage produced in the machining gap; a duty cycle number counting unit configured to count the number of duty cycles of the voltage applied by the voltage application unit for each unit time; an open-circuit state identification unit configured to identify an open-circuit state where no electric discharge occurs after the voltage is applied, based on the machining-gap voltage detected by the machining-gap voltage detection unit; and an open-circuit number counting unit configured to count the number of open-circuits identified by the open-circuit state identification unit for each unit time, wherein an average machining-gap voltage is obtained based on (i) the number of duty cycles per unit time counted by the duty cycle number counting unit, (ii) the number of open-circuits per unit time counted by the open-circuit number counting unit, and (iii) a supply voltage or an average voltage for each duty cycle.