| 摘要 |
PURPOSE:To provide accurate and efficient eletrical discharge machining (EDM) for deburring etc. by detecting the increase and decrease of the number of discharge pulses according to the change of EDM area to detect whether the machining level position has been reached to the predetermined level. CONSTITUTION:The bur 14 around the bottom through hole 13 of a workpiece 11 is removed by EDM. A pulse power source 16 is connected between an electrode 12 and a workpiece 11, and a discharge detector 17 is connected in a series with the pulse source 16. With a discharge occurring in machining gap, its detecting signal S1 becomes a pulse signal and is counted by a counter 20. The counting data D1 counted with a pulse generating period of a gate pulse generator 19 is memorized in No.1 memory and the counting data D2 for one period before D1 is memorized in No.2 memory 25, and the difference between D1 and D2 is found by a reduction calculator 26. A discriminating signal S2 is output when the difference exceeds the predetermined number, enabling the detection of the electrode reaching the bottom surface. |
