Oscillating behavior suppression of cross-coupled arc based on high frequency variable polarity current source

Theoretically, the cross coupled arc (CCA) technology can achieve decoupling and independent control of heat and mass transfer during the welding process, and has great development potential. However, in traditional CCA technology, the bypass arc current is generally provided by a low-frequency AC welding heat source. During the working process, the main arc will oscillate as the polarity of the bypass arc changes, resulting in uneven thermal distribution between different arcs and incomplete decoupling of heat and mass transfer. When applied in additive manufacturing, it will face problems such as uncontrollable droplet drop position and low forming accuracy. In order to solve the oscillation problem of the main arc, a CCA welding heat source with a bypass arc as a high-frequency variable polarity arc has been designed and developed. Experimental results show that this welding heat source can effectively suppress the oscillation behavior of the main arc by increasing the variable polarity frequency of the bypass arc. At the same time, the phenomenon of suppressing the oscillation of the main arc is manifested by the high-frequency and small amplitude vibration of the main arc. This effect can theoretically achieve the stirring effect on the molten pool, which is conducive to dendrite fragmentation and promotes the refinement of weld grain.