WIRE CUT ELECTRIC DISCHARGE METHOD AND APPARATUS

摘要

A wire cut electric discharge method adapted to make a slit (74), which is opposed to predetermined paths (70) each of which is straight or curved, in a workpiece (W) by electric discharge while moving one of a wire electrode (22) and the workpiece (W) relatively to the other along the predetermined paths on the basis of a NC program which is an aggregate of program blocks determined as a segment of the predetermined paths includes the steps of storing a position of a wire electrode which gets out of the predetermined paths after a process has been stopped, designating one segment out of an aggregate of segments of predetermined paths, determining a connecting position (82) in which the wire electrode is connected to the designated segment (80) with the position of the wire electrode the shortest distance away therefrom, and moving the wire electrode to the connecting position so as to return the wire electrode to predetermined paths. When a perpendicular line can be drawn from the position of the wire electrode to the designated segment, the connecting position corresponds to an intersection of the segment and the perpendicular line, and, when not, the connecting position corresponds to one of both ends of the segment which is nearer to the position of the electrode.