To improve welding productivity twin wire welding has attracted extensive attention. Nowadays, the most frequently used twin wire welding mainly includes twin wire gas metal arc welding, TANDEM twin wire welding, and submerged arc welding (SAW). The primary problem in twin wire welding process is the interference between the two arcs which directly affects the welding quality. The interference between the two arcs induces the variance of respective arc morphology which further leads to the change in thermal space allocation.
Here both the wires (M & T-shown in figure) are anode. Therefore, serious interference exists due to the electromagnetic force, which results in mutual offset in arc area. The arc length also changes slightly, which further leads to the arc voltage change. This phenomenon can be simply explained by the deviation formula simplification model (shown below).
The center offset of M and T arcs can be expressed using the following formulas,
The above offset expressions demonstrate that the offset of one arc is proportional to the other arc’s current and the square of its own arc length, while being inversely proportional to its own current and the arc distance. Furthermore, the arc shifts due to the electromagnetic force.
Due to the effect of arc interaction, twin wire welding droplet transfer frequency increases quickly and the droplet size becomes smaller. At the same time, wire extension length decreases which indicates that the welding point changes. Moreover, due to the heating effect of T arc welding wire, the melting heat increases, which increases the welding wire melting rate. As wire feeding rate keeps unchanged, the droplet size becomes smaller. Thus leading to poor quality of weld bead.
Reference: Arc Interference Behavior during Twin Wire GMAW Process
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