铝合金AC-P-MIG焊接电弧行为及熔滴过渡过程

为了研究交流脉冲熔化极气体保护焊（AC P MIG）焊接过程中电弧形态特征及熔滴过渡控制，采用基于LabView的数据采集系统与高速摄像拍摄系统对焊接过程中电信号、电弧形态及熔滴过渡过程进行同步采集与拍摄.研究过程显示，焊丝为负极性（EN）阶段时电弧左右摆动并“上爬”越过熔滴而包裹焊丝，从而加速焊丝的熔化；焊丝为正极性（EP）阶段时电弧形态为典型的“钟罩形”，在脉冲阶段亮度与面积达到最大.熔滴在EN阶段长大速度加快，并在脉冲下降沿发生熔滴过渡.研究结果显示，EN与EP极性的交替变化，有利于降低电弧等离子流力及电弧对熔池的作用，控制合适的EN比率可以得到较快的焊丝熔化速度与较浅的熔深；控制脉冲阶段电流和时间可以实现稳定的一脉一滴过渡方式.

Arc Behavior and Droplet Transfer Analysis in AC-P-MIG Welding of Aluminum Alloys

The variation in arc behavior, stability and control of droplet transfer in AC P MIG welding were studied by data acquisition system and high speed video photography system. The research reveals that the arc in EN polarity moves around the droplet and climbs up to the wire end, as a result of this behavior the wire melting rate increases, while in EP polarity the shape of arc is a typical “bell jar” and its size and brightness become the largest during the pulse stage. The droplet grows rapidly in EN stage and transfers in falling stage of EP. The alternative transformation between EN polarity and EP polarity is beneficial to the reduction in both plasma arc flow power and welding pool arc force. By controlling the EN ratio, a rapidly wire melting rate and shallow penetration appear; by controlling the pulse stage current and time, a stable one pulse one drop transfer process forms.