High Speed DCEN TIG Welding of Very Thin Aluminium Sheet with Magnetic Control for Arc

Abstract

The butt welding of very thin aluminium sheets by the ordinary inverter controlled TIG welder are performed at ultra high welding speed 24, 000 mm/min. In the experiment, the polarity is DCEN, fine 2% ThO₂-W electrodes and the magnetic control of arc are used. The base metals are clamped between two heavy copper plate to reduce the heat flow to the preceding area which causes deflection of the thin base metal. The results obtained are as follows:
1) As the arc is dragged backward at the welding speed 6, 000 mm/min, the welding can be done at the narrow range of current. But the arc can be corrected by the magnetic control, consequently the welding is possible at the wide range of current.
2) To correct arc deflection the rectangular electromagnetic tip is more efficient than the circular one.
3) In the butt welding results of the electrode tip angles from 30° to 120° with the magnetically controlled arc, the angle 60° of electrode tip is found to be suitable for 6, 000 mm/min welding speed.
4) Without magnetic control the butt welding of 0.3 mm thin aluminium sheets is impossible at more than 12, 000 mm/min speed, but becomes possible at 12, 000∼24, 000 mm/min speed with magnetic control.