| 摘要 |
PCT No. PCT/JP89/01019 Sec. 371 Date May 10, 1990 Sec. 102(e) Date May 10, 1990 PCT Filed Oct. 4, 1989 PCT Pub. No. WO90/03862 PCT Pub. Date Apr. 19, 1990.An automatic wire extension method capable of effecting reliable and smooth wire extension regardless of the size of the diameter of an initial hole and even with use of an inexpensive apparatus, such that during the wire extension through an initial hole having a normal diameter, when a wire electrode is fed while a machining fluid is injected toward a workpiece (50) from a wire extension nozzle (120) attached to an upper wire guide (30) and set apart from the workpiece, the wire electrode is reliably threaded into the initial hole (51) and a wire passage of a three-point support guide (72) accommodated in a lower wire guide, due to a wire guiding function provided by the machining fluid jet. A wire extension through a small-diameter initial hole, when a wire extension nozzle (120) having a nozzle hole (125) with a diameter smaller than that of the initial hole (51) is attached to the upper wire guide, and the wire electrode is fed through the nozzle with the nozzle positioned close to the workpiece and with the supply of the machining fluid interrupted, the wire electrode is threaded into the small-diameter machining hole close to the nozzle, and then into the wire passage of the lower wire guide due to a wire guiding function provided by the initial hole.
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