保护气体成分对双丝旁路耦合电弧GMAW旁路熔滴过渡形式的影响

双丝旁路耦合电弧GMAW的旁路焊枪选择了正极性接法即焊丝接电源负极,旁路熔滴仅依靠重力向熔池过渡,旁路熔滴尺寸较大且过渡过程并不稳定.针对这一问题,采用已建立的双丝旁路耦合电弧焊接过程信号控制与高速摄像采集系统,采集了纯氩气保护时旁路熔滴过渡形式,并分析了旁路熔滴尺寸较大且过渡过程不稳定的原因.在此基础上,采用80% Ar+20% CO₂为保护气体进行了焊接试验.结果表明,焊接过程中,保护气体中的O元素在旁路熔滴表面形成了氧化膜,旁路电弧在旁路熔滴表面的氧化膜上稳定燃烧,从而使电磁收缩力重新作用在旁路熔滴上并促进旁路熔滴向熔池过渡,因此焊接过程中旁路熔滴尺寸明显减小,熔滴过渡过程更加稳定.

Effects of different protective gas on bypass metal transfer in consumable double-electrode gas metal arc welding process

In consumable double-electrode gas metal arc welding process,since the bypass welding wire is connected to the negative electrode of the welding power supply,only gravity promotes the bypass droplet transfer to the weld pool by using pure argon as protective gas. So the size of the bypass droplet is large and the metal transfer process is unstable. A high-speed camera acquisition system and a welding control system of the consumable double-electrode gas metal arc welding have been built to collect and analyze the bypass metal transfer process. On this basis,a welding test was carried out by using the 80% Ar+20% CO₂ mixture gas as protective gas. The results showed that the bypass arc burned stably on the oxide film of bypass droplet formed by CO₂ in protective gas,so the electromagnetic force and the gravity promoted the bypass metal transfer together and the size of the bypass droplet was significantly reduced.