Investigation of arc behaviour and metal transfer in cross arc welding

Abstract

In traditional welding processes, the electrode and the work-piece serve as the two terminals of the arc, cathode and anode, respectively. In addition, their heat and mass inputs are coupled and unable to be freely optimized to suit for the needs from specific applications. A modified arc welding process is thus proposed in this work to establish a cross arc process where two wires are charged by a second power supply and are fed into the main arc (gas tungsten arc (GTA) or plasma arc (PA)) which heats the work-piece. An inter-wire arc can be established between the two wires to heat both wires directly. The heat and mass inputs are decoupled. A high speed camera is used to analyze the metal transfer behavior. The main arc swings regularly among the two wires as the alternating inter-wire arc current switches its priority: the main arc deviates to the cathode of inter-wire arc. The main arc is deviated by the Lorentz force, which is generated by the inter-wire arc current. The PA force and the aerodynamic drag force, thus automatically acts on the droplet on the cathode wire to provide an additional detachment force. The parameters of the two coupled arcs can be adjusted separately to provide the needed deposition rate, force and heat input freely as the capability to increase the productivity while maintaining the base metal heat input at a desired level. Therefore, this new innovative hybrid arc welding process can be used for overlaying by the new heat transfer mechanism.