交流CMT动态电弧特征及熔滴过渡行为分析

Analysis of dynamic arc characteristics and melt transfer behavior of AC CMT

为了研究交流CMT焊接过程中的电弧形态及熔滴过渡过程,采用高速摄像技术结合焊接电参数采集系统,拍摄了清晰的交流CMT电弧及熔滴图像,同步采集了电参数的波形数据,将二者结合起来分析.结果表明,交流CMT电弧经历燃弧—形成熔滴—熄弧过程;正极性阶段焊丝端头电弧集中,工件表面电弧发散,形成"钟罩"形电弧;负极性阶段电弧有"上爬"现象,该现象会加速焊丝熔化;熔滴过渡经历冷—热—冷的转换,无缩颈形成;负极性阶段的焊丝熔化速度相对较快,熔滴过渡周期小于正极性阶段,熔滴直径比正极性阶段的略大.

In order to study the process of droplet transferring and arc behaviors of AC CMT welding,high speed photography was carried out to capture high-definition images of the arc and droplet of AC CMT welding while the electrical parameters waveforms were gathered by welding electric parameters acquisition system,and the images and waveforms were investigated simultaneously. The results show that the arc of AC CMT goes through the process of arcing-forming droplet-arc blowout.During the electrode positive period,arc concentrates at the end of filler wire and spreads on the surface of base metal,like a bell-jar. During the electrode negative period,the arc crawls up along the filler wire in a way to accelerate the melting of filler wire. Droplet transferring goes through the process of cold-hotcold and no necking forms. During the electrode negative period the melding speed is larger,the melt transfer cycles is shorter and the diameter of droplet is larger compared with the electrode positive period.