Heating Form of Faying Edges and Effect of Convergence-Angle

Experimental Studies on Manufacture of High-Frequency-Induction-Welded Aluminum-Alloy Tube (Report I)

Abstract

This study has been performed on the heating form of the faying edges to be welded and the effect of the convergence-angle at the vee-shape which affect remarkably on the quality of weld in high-frequency-induction-welded aluminum-alloy tube with 20 mm outside-diameter.
The results show that the heating form of the faying edges assumes a kind of flash near the apex of the vee-shape. This seems to be the part where the high-frequency current converges and short-circuits, and the faying edges are heated most intensively. It is necessary to supply power input enough to form the flash with sufficient brightness in order to melt the faying edges successfully.
The flash form is significantly affected by the convergence angle. The angle narrower than 5° causes the unstalbe flash. It is recommended that the angle wider than 6°should be maintained to obtain the stable flash.
On the other hand, the quality of the weld is, too, affected by the-angle. The reasons are the flash form mentioned above and resulting effect of welding-cycle time. The same recommendation is offered about the angle to produce the desirable quality.
The angle recommended is wider than that in welded steel tubes. It appears that the high-frequency current does not so concentrate at the faying edges resulting from proximity effect in the wider angle. Therefore, it is extremely important to control the convergence-angle constantly.