| 摘要 |
PURPOSE:To sharply improve machining precision at a corner part, by providing a control means which predicts a change in a machining amount at a corner part and corrects a change in a gap between the sides of electrodes occasioned by a change in a machining amount. CONSTITUTION:In finish machining, a discriminator 12 outputs a signal by means of which a control device 14 is actuated when a present machining position is under circular movement of a corner part. The control device 14 selects a new interpole servo reference voltage for machining the preset corner part by means of signals from a discrimator 12 and a discriminator 13 for discriminating finish machining. The control device switches a reference voltage to the new reference voltage, and restores it to its original interpole servo reference voltage upon completion of machining of the corner. For. example, since, in the case of machining of an in-corner, with the increase in a machining amount, a gap between the sides of electrodes is increased to cause overcut, the control device 14 switches a reference voltage to an interpole servo reference voltage, in that the gap between the sides of electrodes is decreased, so that the overcut by a machining integration effect is corrected.
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