McDermott, Will & Emery
Wire cut electric discharge method and apparatus
 A wire electrode machining method which machines a slit (74) corresponding to a fixed path in a workpiece by electrical discharges while moving one of either a wire electrode (22) and a workpiece (W) with respect to the other based on an NC program which is a collection of program blocks, which define straight line or curved line segments of a fixed path (70), including a step of recording the position of the wire electrode which has strayed from the fixed path after machining has stopped; a step designating a segment from a collection of fixed path segments; a step determining the connection position (82) at which the wire electrode position can be connected to the designated segment (80) at the shortest distance; and a step of moving the wire electrode to a connection position in order to restore the wire electrode to a fixed path. The connection position is taken to be the intersection of a segment and a vertical line in cases in which it is possible to draw a vertical line from the wire electrode position to that designated segment, and the end of that segment which is closer to the wire electrode position when that is not the case. 
Sodick Co., Ltd.
B
B23H
inventional
Tatsuo Hisanori
Kuroda Yamada