高速列车转向架构架超窄间隙激光填丝焊熔滴过渡行为研究

Research on drop transfer of ultra narrow gap laser wires filling welding of bogies frame for high speed trains

高速列车转向架结构复杂,焊缝数量多且分布密集。采用超窄间隙激光填丝焊技术焊接转向架用中厚钢板,可以解决传统MAG焊存在的焊道次数多、残余变形及应力大的缺陷,也可以解决激光自熔焊对坡口间隙敏感的缺点。主要研究超窄间隙激光填丝焊的熔滴过渡行为,结果表明:当光丝间距不同时,熔滴过渡形式依次由铺展过渡转变为液桥过渡并最终转为颗粒过渡;当功率不同时,熔滴过渡形式由低功率条件下的铺展过渡转变到高功率条件下的液桥过渡。焊接速度并未影响熔滴过渡形式,依然保持液桥过渡。送丝速度影响激光对焊丝的熔化过程,从而产生不同的熔滴过渡形式。焊接厚板结构时选择负离焦,焊接薄板时选择正离焦。

The structures of bogies are complex and the welds distributed densely and the numbers are lot for the high speed trains. The medium plate welding of frames with ultra narrow gap wire filling laser welding technology can solve the problem of multiple passes,large deformation and residual stress of traditional MAG welding,and it can also solve the problem of the sensitivity of groove clearance of laser welding. This paper is focused on the molten drop transition of ultra narrow gap wire filling laser welding. The results showed that the transition mode of molten drop was first unfold transition and then liquid bridge transition and finally particle transition when the laser wire spacing was different. The transition mode of molten drop changed from unfold transition under lower power to liquid bridge transition under higher power. The welding speed didn’t affect the transition mode and still the liquid bridge transition. The feeding speed would affect the molten period of the wire and then produce different molten transition mode. It should choose negative defocus when welding thick plate and should choose positive defocus when welding thin plate.