| 摘要 |
PURPOSE:To prevent stagnation of sludge, by detecting abnormal electric discharge occurring between electric discharge electrodes and by carrying out pumping control in such a way that the rates of pressure of machining liquid fed from upper and lower machining liquid jet nozzles are alternately changed in accordance with the detection signal. CONSTITUTION:An abnormal discharge detecting circuit 14 delivers an abnormal discharge detection signal if abnormal electric discharge having a voltage less than a predetermined value successively occurs, exceeding a predetermined frequency within a predetermined period. Further, a valve opening degree control circuit 15 changes the opening degrees of valves 16, 17, alternately in accordance with the above-mentioned abnormal discharge detection signal to control the amount of liquid so as to manage the pumping management of machining liquid 10 so that the rates of the machining liquid jetted from upper and lower machining liquid jet nozzles 7, 8 are alternately changed. Accordingly, sludge produced between electrodes is discharged without stagnating, so that the discharge efficiency is enhanced. As a result, it is possible to substantially eliminate breakage of a wire electrode 1 so that a machining process may be carried out with a high degree of efficiency.
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