PLASMA TORCH AND PLASMA ARC WELDING METHOD

摘要

Disclosed is a plasma torch (1) which is used in plasma arc welding. The plasma torch (1) comprises a rod-like electrode (10), a first cylindrical nozzle (11) that is provided so as to surround the electrode (10) and spurts a plasma gas, and a second cylindrical nozzle (12) that is provided so as to surround the first nozzle (11) and spurts a shielding gas. The second spout (121) of the second nozzle (12) faces the direction that is generally parallel to the axial direction of the electrode (10) or the direction receding from the electrode (10), and the outer circumferential surface of the first nozzle (11) or the inner circumferential surface of the second nozzle (12) is provided with a plurality of grooves that are inclined to the axial direction of the electrode (10). Consequently, the shielding gas is spurted spirally along the arc surface.