| 摘要 |
PURPOSE:To prevent production of burrs on the periphery of a prepared hole and to enable machining of the prepared hole, having a smooth surface, by performing excellent electric discharge, by a method wherein energy of a discharge pulse is increased with the progress of machining by using a low energy discharge pulse during the starting of machining. CONSTITUTION:When a prepared hole for a wire electrode is machined, a machining solution is injected and fed through the interior of a fine tube electrode 1 to a machining gap. Simultaneously, a discharge pulse is applied on a machining gap by a source circuit 2 according to a predetermined program. Namely, during the starting of machining, a voltage pulse having a pulse duration number mus is fed at a low voltage of approximate 40V, and pulse duration is gradually increased together with an applied voltage with the progress of machining. This method prevents burrs, produced due to hardening of the splash of a molten metal to a workpiece, from being produced on the peripheral edge of a prepared hole, and forms a prepared hole 6, having a smooth machined surface, in a manner to be extended through the workpiece.
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