GMAW短路过渡过程的二次引弧现象

Secondary arc striking during short circuit transfer of GMAW

传统的短路过渡过程一般认为整个过程只存在一次引弧.但是文中通过对GMAW短路过渡的高速摄像照片进行观察发现了一个新现象——即短路过渡过程并不是一次引弧完成的,而是存在二次引弧现象.结果表明,当熔滴颈缩断裂的瞬间,焊丝端部与脱落熔滴尾部之间存在一定浓度的高温金属蒸气,会发生一次短暂的电弧燃烧过程.此电弧随着脱落熔滴逐渐没入焊接熔池而消失.随后会以保护气体作为介质进行下一次引弧(二次引弧),此次引弧也是传统短路过程的引弧阶段.由电流波形可知,在熔滴颈缩附近存在两次短路电流波形,一次波形为传统的短路峰值电流,二次波形则是由于金属蒸气短暂引弧造成的.

Short circuit transfer process of conventional GMAW is generally believed that only the first arc striking is formed.However,a new phenomenon was found that the secondary arc striking occurred at the short circuit transfer,but not only the first arc striking,by observing the high-speed photographic images in the GMAW process.The results showed that when the droplet necking was broken,the high-temperature metal vapor with a certain concentration was formed between the end of the wire and the dropped droplet,which led to a transient arc burning.This arc along with the melting droplet gradually dropped and then disappeared in the melting zone,while the protecting gas acted as the medium and then the secondary arc striking happened.This arc striking was the arc striking stage during the conventional short-circuiting transfer process.The current waveform showed that two short circuit current waveforms appeared in the vicinity of the melt necking.The first waveform was the conventional short circuit peak current,while the secondary waveform was caused by the temporary arc-striking induced by the metal vapor.