publish time：2017-01-04 clicks：728
Tandem Wires Narrow-Gap Automatic Submerged Arc Welding Machine
Application: It is mainly used for automatic welding of the main circumferential joints in of heavy pressure vessels. The groove depth is 100- 600mm, with the gap width of 18-24 mm.
Double-sidewall tracking and height tracking ensure a constant distance between the welding wires and sidewall as well as a constant wire extension, helpful in improving the welding quality.
During the tandem wire welding process, the straight wire is upright down while the curved wire points to the side-wall. The two arcs form jointly one molten pool lead to a wider and thinner bead, which can utilize the heat of the subsequent bead to heat-treat the HAZ of the former one. As the welding heat input to the sidewall is less, the mechanical properties of the welded joint, especially the toughness of the heat-affected zone, are much better than those of the traditional submerged arc welding and even better than those of single wire narrow gap SAW.
Since the welding process is automatically conducted with two beads per layer, fine bead shape and smooth bead surface could be achieved. The slag crust could (fall off by themselves) detach automatically without manually cleaning.