Electric discharge method and its apparatus.

摘要

An electric discharge machining method for machining a workpiece (2) by producing a series of intermittent electric discharges at a gap between a tool electrode (1) and the workpiece (2). A discharge inducting circuit (4) has at least one DC power source (41) for inducting an electric discharge at the gap between the electrodes, a main discharge circuit (3) is for superimposing the main discharge current for machining after the electric discharge, and a switching circuit (6) is for selectively changing the polarity of the discharge inducting voltage of the discharge inducting circuit (4) at the gap. The polarity of the electric discharge voltage applied to the gap can be changed at each electric discharge as a minimum unit period. Therefore, electrolytic effects caused by the application of the discharge inducting voltage can be avoided. <IMAGE>