Plasma arc welding method and plasma arc welding apparatus

摘要

PROBLEM TO BE SOLVED: To provide a plasma arc welding method and a plasma arc welding apparatus which can prevent electrode oxidation and plasma nozzle stain due to metal vapor.SOLUTION: In a plasma arc welding method where an electrode 11 for igniting arc and a plasma nozzle 13 arranged outside the electrode 11 via a space are provided to ignite a main arc between an electrode 11 and a base material M after a pilot arc is ignited between the electrode 11 and the plasma nozzle 13 while a plasma gas is being fed to the inside of the plasma nozzle 13, and to weld or cut the base material M with ignited main arc, the arc pressure of the pilot arc inside the plasma nozzle 13 is strengthened by increasing the flow rate of the plasma gas fed to the inside of the plasma nozzle 13 after the extinction of the main arc.SELECTED DRAWING: Figure 2