| 摘要 |
PURPOSE:To obtain an extremely good-quality and uniform machining surface at all times by providing plural switching elements which alternately repeat on and off operations, and obtaining a machining power source having a stable output characteristic with respect to variation in floating capacitance and floating inductance. CONSTITUTION:The on and off operations of switching elements 9 to 12 are alternately repeated at a high frequency of several MHz by means of a driving circuit 3, causing a floating capacitance 8 to repeat changing and discharging. By setting a proper switching frequency with respect to the time constant of the floating capacitance 8, however, a high-frequency voltage having two times the voltage of a DC power source 1 is generated across poles, i.e., on both ends of the floating capacitance 8, to carry out electric discharge machining. In principle, since the voltage at the part across the poles 6 depends on the voltage of the DC power source 1, the variation in the floating capacitance 8 can be neglected, stabilizing the output voltage. Accordingly, a good-quality and uniform machining surface can always be obtained.
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