双丝窄间隙熔化极气体保护焊的焊接稳定性

Stability of Double Wires Narrow-gap Gas Metal Arc Welding

双丝熔化极窄间隙气体保护焊(NG-GMAW)前后焊丝之间沿焊接方向的距离和夹角、焊丝与坡口侧壁之间的距离等参数都可以独立调节,并对焊接过程稳定性有很大影响。试验发现,双丝沿焊接方向的间距小于15mm或大于50mm时,双电弧处于共熔池或独立状态,焊接过程稳定;而当双丝间距在20～30mm时,处于共熔池向独立熔池过渡阶段,受窄间隙坡口中非均衡分布的电磁力作用,频繁出现断弧现象,焊接过程不稳定。双丝沿焊接方向平行竖直分布时,焊接过程稳定,若前丝后倾则会加剧电弧的偏移,焊接稳定性变差。焊丝与侧壁间距对电弧形态有很大影响,当间距为2.5mm时,电弧在焊丝和坡口底部以及侧壁之间稳定燃烧;而当间距达到1.5mm时,出现侧壁打弧现象,焊接稳定性恶化。

Some special parameters of double wires narrow gap GMAW （NG-GMAW） welding can be adjusted individually, such as the angle and distance between the two wires along the welding direction and the distance between the wire and the sidewall of the groove. These parameters have great influence on the welding stability. Experiments results show that when the distance between the two wires is less than 15 mm or greater than 50 mm, the two welding arcs are in one molten pool or two independent molten pools, and the welding process is very stable. When the distance is 20~30 mm, the molten pool is transforming from single one to two independent one. Under the action of unbalanced electromagnetic force, the arc is compelled to break frequently and the stable welding process is destroyed. When the two wires are parallel along the welding direction, the welding process is stable; if the front wire is inclined to the rear wire, the wandering of the front arc is aggravated. The distance between the wire and the groove sidewall has great influence on the arc modality. When the distance is 2.5 mm, the arc bums stably between the wire and the sidewall as well as the bottom of the groove. But if the distance is less than 1.5 mm, the arc bums between the sidewall or bottom randomly, and the welding stability deteriorates.