Wire electrical discharge machining apparatus, wire electrical discharge machining method, and wafer manufacturing method

A wire electrical discharge machining apparatus that generates electrical discharge between a plurality of cutting wire parts that are running and a workpiece to perform electrical discharge machining on the workpiece with energy generated by the electrical discharge, and simultaneously cuts a plurality of wafers from the workpiece, the wire electrical discharge machining apparatus comprising:

• a wire electrode including the plurality of the cutting wire parts spaced apart from each other in parallel and including a portion facing the workpiece;
• power feed circuitry to generate electrical discharge between the plurality of cutting wire parts and the workpiece;
• a pair of wire parallel guide rollers disposed on both sides of the workpiece so as to sandwich the workpiece, in each of which a plurality of wire guide grooves are formed on an outer peripheral side surface thereof at equal intervals, the plurality of wire guide grooves causing the plurality of cutting wire parts that are running to fit therein and restricting movement of the plurality of cutting wire parts;
• parallel wire extension position measurement circuitry to measure a distance between a measurement reference surface set parallel to a virtual plane including the plurality of cutting wire parts and the wire electrode constituting the plurality of cutting wire parts;
• wire guide groove detachment detection circuitry to detect occurrence of a change in the distance on a basis of a measurement result obtained by the parallel wire extension position measurement circuitry;
• wire state determination circuitry to determine whether it is a wire detachment state where at least one of the cutting wire parts is detached from the wire guide groove or a wire contact state where all the cutting wire parts are in contact with the wire guide grooves, on a basis of a detection result obtained by the wire guide groove detachment detection circuitry;
• and
• machining control circuitry to control stop or continuation of electrical discharge machining on a basis of a determination result obtained by the wire state determination circuitry.