| 摘要 |
<p>In electric discharge machining DC voltage pulses are applied between a machining electrode (H) and a workpiece (W) to machine the workpiece (W). A voltage peak detecting circuit (R1, R2, TR2, AS1, R6, C) responsive to discharge voltage between the electrode (H) and the workpiece (W) detects a peak value of the discharge voltage. An A to D converter converts the voltage across a capacitor (C) of the peak detecting circuit into first digital data which is supplied to a first ROM(1). A waiting time detecting circuit is also responsive to the discharge voltage for detecting a waiting time between the start of the DC pulse voltage and the start of discharge and includes a reference voltage source (R7, R8) and a comparator (CP). A second A to D converter converts the wait time signal from the comparator (CP) into second digital data which is supplied to a second ROM(2). A numerical control circuit (NC) supplies compensating data for compensating the first digital data in accordance with a machining condition and the second digital data in accordance with a machining condition to the two ROMs (1 and 2). The ROMs compute the discharge gap signal and an adder (FA) adds the digital data from the ROMs. </p> |
