AC PLASMA WELDING METHOD OF ALUMINUM MATERIAL

摘要

PROBLEM TO BE SOLVED: To improve the quality of the plasma welding of aluminum material by providing the shield gas consisting of the inert gas of argon or helium in which oxygen and nitrogen of the prescribed per cent is mixed. SOLUTION: A discharging electrode 8 is provided at a center position in a cylindrical torch 1. A gas flow passage is formed in the side of the discharging electrode 8, and the plasma gas is ejected into a space between the gas flow passage and a tip 5 to surround a lower end part of the discharging electrode. The plasma gas is ejected outside the torch through a gas ejection port 5A. An outer circumferential surface of the tip 5 is covered by a shield cap 10, the shield gas is fed between the tip 5 and the shield cap 10, and the shield gas is discharged toward the aluminum material 2 through a ring-shaped ejection port in a tip edge circumference 7 of the tip 5. The shield gas consists of the inert gas of argon or helium in which 0.3-6% oxygen and 1-10% nitrogen is mixed. A beautiful bead in which blowholes are controlled, and the surface is flat can be obtained.