PLASMA CUTTING METHOD AND NC PLASMA CUTTING APPARATUS

摘要

This invention relates to a plasma cutting method and a NC plasma cutting apparatus, which enable the quality of a bore-cut product obtained by using transferred plasma arc to be improved, and the productive efficiency of such a product to be improved. The transferred plasma arc is switched to non-transferred plasma arc in a position immediately before a cutting finishing point and a position in the vicinity of a position in which cutting lines cross each other. Simultaneously with this switching operation, a moving speed of the plasma torch is varied in accordance with the variation of a plasma arc current. A transferred plasma arc current is reduced in a position immediately before a cutting finishing point and a position in the vicinity of a position in which cutting lines cross each other. The moving speed of the plasma torch may be varied in accordance with the reduction of this arc current. At the cutting starting time and during a cutting operation, the voltage detecting function is stopped, and an operation of this function is started in a position immediately before a cutting finishing point and a position in the vicinity of a position in which cutting lines cross each other.