| 摘要 |
PURPOSE:To reliably detect a short circuit between an electrode and a work even if power supply conditions are changed during discharge machining by making the reference voltage to be compared with the divided voltage across the electrode and the work the reference voltage proportional to the servo voltage. CONSTITUTION:During discharge machining, when power supply conditions such as the ON/OFF duty, peak power supply, etc. are strong, machining is performed at high servo voltage; and when the power supply conditions are weak, machining is performed at low servo voltage. Accordingly, when the power supply conditions are strong such as during rough machining, the servo voltage VS is high, the divided voltage of the voltage VS is fed to a comparator 6 as the reference voltage for short-circuit detection, thus the reference voltage becomes high naturally. When the power supply conditions are weak such as during finish machining, the servo voltage is low, and as a result, the reference voltage fed to the comparator 6 becomes low, thus the short-circuit detection level between the electrode P and the work W can be kept optimum. |
