摘要 |
A power supply (100) and a method for electric discharge machining by repeatedly providing a current pulse to a working gap (3) formed between a tool electrode (1) and a workpiece (2) includes a d.c. power source (E), first switching elements (Tr1-Trn) connected between the d.c. power source and the working gap, capacitors (C1-C8) connected in parallel with the working gap, second switching elements (67) for controlling current flow from the capacitor to the working gap, a detector (50) for detecting start of an electric discharge, and a controller (20) for controlling the first switching elements and the second switching elements in response to the detector. Current is supplied from the d.c. power source through the first switching elements to the working gap only for a first time interval (&tgr; ON) starting from the commencement of electric discharge, and a current is supplied from the capacitor through the second switching elements to the working gap for only a second time interval (T) is shorter than the first time interval, starting from the commencement of an electric discharge.
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