Method and apparatus for electrical discharge machining using variable capacitance and variable inductance

摘要

An electric discharge machine having a source of pulse power, optionally including bipolar pulses, which is connected to an electrode which forms a gap with a workpiece and is operative to provide both machining and finishing processes. Switching of power to the machining gap and impedance matching at the machining gap, in order to suppress the influence of the capacitance of the high-speed machining feeder cables connected to the machining gap in finishing, is provided so that machining can be performed at high accuracy with a properly timed and shaped discharge current. Impedance matching is provided by selectively switching among plural capacitances or inductances, which may be in the form of cables or printed patterns on a circuit board which have predetermined values, such as a geometric series values of which coefficient is 2.