Mechanism analysis of free formation of backing weld by the pulsed MAG-TIG double arc tandem welding

Because of the presence of lower-level automation and efficiency in the backing welding of medium–thick plates,pulse-metalactive-gas–metal-inert-gas(MAG–MIG)dual-arc welding was applied to backing welding of 24-mm-thick Q235-B plate and the process and mechanism of root welding with back formation were investigated.The heating position of the MAG-arc at the front of the molten pool could be adjusted by using the electromagnetic force between the MAG-arc and the MIG-arc,and part of the arc energy could work on the root face directly.By combining the arc-discharge behaviour and analysis of flow in the molten pool,the shear stress of a tungsten inert gas(TIG)arc to the molten pool could make the liquid metal flow backwards.Thus,the quality of the front and bottom liquid metal were reduced,which favored the balance and stability.Continuous and stable back formation with uniform penetration could be achieved by using the pulse MAG–TIG dual-arc welding technology.

P-TIG横焊根部焊道单面焊双面成形影响因素

TIG横焊打底焊作为大型汽轮机焊接转子关键制造技术之一,国外有关公司将其作为Know-How进行严格的技术封锁.文中开展了焊接工艺参数(电弧电压、焊接电流、脉冲频率和送丝速度)对P-TIG横焊单面焊双面成形影响的试验研究.结果表明,焊接电流对根部焊道单面焊双面成形的熔透性起着决定性的作用,其次是电弧电压;脉冲频率对正面焊缝成形的影响较大,而且对于抑制熔池金属的下淌倾向具有良好的效果;送丝速度和电弧电压对背面焊缝成形影响较大,当焊接工艺参数较小时,背面焊缝不能够成形.

单面焊双面成形技术在集装箱生产中的应用

钢制干货集装箱生产中薄板自动焊焊接质量一直不稳定,客户投诉较多。经过现场分析和调研,将加垫板的单面焊双面成形焊接工艺改为自由成形的单面焊双面成形焊接工艺,同时制定了相应的焊接规范。实践证明,通过改变焊接工艺,确保了自动焊焊接质量,尤其对焊前进行喷漆处理的薄板,更是一种行之有效的方法。