| 摘要 |
PURPOSE:To prevent damage of electrode and restore interpole to normal condition rapidly by preventing abnormal short-circuiting by removing sludge by controlling speed of separation of electrode from a work to be machined based on output of an interpole condition discriminating means. CONSTITUTION:When short-circuiting occurs, a short-circuiting signal SB becomes 1, and an adding signal of frequency coincident with unstable degree from a pulse generator 106 whose frequency is controlled by an output signal SA of a counter 26 is input through an AND gate 105 out of two gates 104 and 105 into an address counter 101. This signal is high frequency in unstable condition and it is low frequency in stable condition. When short-circuiting is removed and the short-circuiting signal SB becomes zero, a counter 101 starts substraction and when the counter shows zero, that is, the back locus comes to the initial position, substraction is stopped. Therefore, machining content becomes unstable and interpole condition is deteriorated, and when short- circuiting occurs, a wire electrode starts to retire to the machining start point along the machining locus up to the time at a speed corresponding to the machining condition just before, and break of the wire electrode can effectively be prevented. |
