| 摘要 |
PURPOSE:To detect disconnection of a wire electrode of a wire cutting machine in a short period of time by switching off processing power source when momentary value of processing voltage became higher than an average value of peak values by more than a key content value. CONSTITUTION:When a wire electrode 2 is disconnected during processing operation, an area between the wire electrode 2 and a work 1 in the processing space becomes decreased, and leak current travelling between them is also decreased increasing equivallent resistance. As a result, a capacitor 18 in a processing power source 14 is charged rapidly allowing a voltage Vg between the wire electrode 2 and the work 1 to go up and it becomes much higher than an average value Vp of the peak values. And therefore, an input V0 of a comparator 56 becomes higher than a constant voltafe Vr making an output of a detection signal e0. In other words, if a wire electrode 2 was disconnected during processing operation, there is an immediate output of a direction signal e0 to detect disconnection of the wire and at the same time an output of a processing power source 14 is switched off. |
