直流正接MAG焊电弧及熔滴过渡特性

Arc and Drop Transfer Behaviors of MAG Welding Process with Direct Current Electrode Negative

借助高速摄像手段研究不同保护气氛下(Ar+CO2和Ar+O2)、不同焊接电流大小的直流正接MAG焊的电弧及熔滴过渡特性,分析电弧烁亮球的成因及其对直流正接MAG焊接过程稳定性的影响特点,并在此基础上确立直流正接MAG焊的工艺区间,同时比较焊丝极性对MAG焊焊丝熔化系数的影响。试验结果表明,当保护气体采用Ar+CO2时,熔滴过渡方式基本上呈大滴排斥过渡,焊接过程不稳,飞溅较大,难以应用;当保护气体采用98%Ar+2%O2时,稳定的直流正接MAG焊的熔滴过渡方式可分为小电流滴状过渡和大电流射流过渡,其中前者为下垂滴状过渡,并且熔滴尺寸随着焊接电流的增大而减小,而熔滴过渡频率相应提高,后者的电弧烁亮区分为上下相串联的两部分,调节电弧电压可以控制电弧烁亮球的活动范围并能改善焊接过程的稳定性。

By using the high speed camera, the arc and drop transfer behaviors of direct current electrode negative MAG welding process with different protecting atmospheres and different welding current levels are researched. The formation reason of bright arc ball and its influence on the stability of MAG welding process are analyzed. On this basis, the process interval of direct current electrode negative MAG welding is determined. Also the influences of wire polarity on wire melting coefficient are compared. By using 80%At plus 2%CO2 as shield gas, the drop transfer style belongs to large drop repulsion transfer, so the spatter is too large. But when the shield gas is 98%Ar plus 2%O2, the stable drop transfer style can be divided into dropwise transfer with low current and streaming transfer with large current. For the former one, with the increase of welding current, the droplet dimension reduces and the drop transfer frequency increases. For the latter one, the arc is divided into two parts in series. Both the moving domain of the bright arc ball and the stability of the welding process can be controlled by adjustment of arc voltage.