Electric discharge working method and apparatus

摘要

An electric discharge working apparatus for generating an intermittent electric discharge to an interelectrode space formed between a working electrode (1) and a workpiece (2) to execute a removing work of the workpiece (2) by sending a working current, apparatus comprises an electric discharge inducing circuit (4) for applying to the interelectrode space voltages of a positive polarity and a negative polarity for inducing the electric discharge, a main electric discharge circuit (3) for supplying a working current pulse to the interelectrode space after the electric discharge is started, a detecting means (56) for detecting an average value of the interelectrode space voltage, a comparing means (55), (58) and (59) for comparing the detected value with a reference value, and a control means (5) for outputting a signal for changing an output polarity of the electric discharge inducing circuit (4) responding to an output from the comparing means (55), whereby the average interelectrode voltage is detected, and the polarity of the interelectrode electric discharge inducing voltage is changed in such a manner that the average voltage coincides with 0V. <MATH>