| 摘要 |
PURPOSE:To make both a large area machining and a finish machining possible by calculating and controlling internal impedances of a power source based on impedances between electrodes so as to supply a constant value of no-load voltage higher than a spark generation voltage. CONSTITUTION:A voltage between electrodes 1 and 2 caused with a dc power source 7 for detection is detected with a detection means 10 and an impedance between the electrodes is calculated with an operation means 11 during a time of a pause. Based on this, internal impedances Rx and Ry of a machining power source 3 are set so as to supply a no-load voltage higher than a spark generating voltage during a time of no load and to supply a required machining current after a discharge generation is detected with a detection means 9. After a specified time of a pause, a series of actions of switching a current restriction resistor array 5 through a power transistor array 4 are repeated and controlled. In this way, the optimum no-load voltage and the required machining current are obtained to make machinings in areas of both a large area machining and a finish machining possible.
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