Patent ID: 8525068

Claim:
A plasma torch for plasma-arc welding comprising: a rod-shaped electrode; a first cylindrical nozzle surrounding the electrode and configured to inject a plasma gas; and a second cylindrical nozzle surrounding the first nozzle and configured to inject a shielding gas, wherein an injection opening of the second nozzle spreads in a substantially parallel direction relative to an axial direction of the electrode or in a direction away from the electrode, wherein a plurality of groove portions inclining with respect to the axial direction of the electrode are formed in an outer circumferential surface of the first nozzle or an inner circumferential surface of the second nozzle, and wherein the plasma torch is configured such that when butt-welding together two workpieces having different thicknesses, including a thinner workpiece and a thicker workpiece, the grooves incline so as to direct a flow of the shielding gas toward the thinner workpiece.