| 摘要 |
PURPOSE:To make it possible to carry out the renewal of machining liquid rapidly at an appropriate time, by detecting the resistance value of an electric discharge machining gap so that when the thus detected value becomes lower than a set value, a reciprocating motion drive device is controlled for operation to carry out the renewal of machining liquid. CONSTITUTION:An electric discharge machining device feeds a liquid of water group to a machining gap between an electrode 1 and a workpiece 2 while giving a servo-feed, and receives pulses from an arc discharge power source to give arc discharge repeatedly to carry out machining. In this case, a signal which is in proportion to the specific resistance value of machining liquid is generated through a detecting resistance 7, and is compared with a discrimination reference value in a discriminating circuit 8. When the detection signal becomes lower than the reference value, a control circuit 9 delivers a reciprocating signal to a servo/reciprocating motion drive device 4 to rapidly raise the electrode 1. With this arrangement, the machining gap is increased so that the renewal of machining liquid existing in the gap and the flushing of the latter may be smoothly carried out. |
