| 摘要 |
PURPOSE:To perform a reliable drilling machining by providing an arithmetic unit outputting an AND signal and a logical sum signal of both output signals of a Z axis counter and an insulation detecting device, and a switching device connected to the output side of the unit and outputting a given signal between the AND and the logical sum signals. CONSTITUTION:When the tip of a processing electrode 1 is worn away keeping a generally flat state, a switching device 30 is set so that an AND signal S3 by an arithmetic unit 20 is outputted as a processing stop command S5. When the tip of the electrode 1 penetrates a perforated part of a workpiece 2, an insulation between the electrode 1 and the workpiece 2 is restored, therefore an insulation detecting device 10 sends an output. Furthermore, when the electrode 1 is forwarded to a position Z corresponding to a preset value of a Z axis counter 7, the counter 7 sends an output. And the unit 20 sends the signal S3 by both signals mentioned above, and the command S5 is sent via the switching device 30. The command S5 is inputted into a motor control circuit 35, a motor 4 and the electrode 1 stops, and drilling is completed.
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