Arc behavior and droplet transfer in self-adaptive shunt alternating arc WAAM

The traditional arc welding heat source could't be directly applied to wire and arc additive manufacturing (WAAM) due to high heat input and low deposition rate. A technology for alternating-arc-based additive manufacturing was proposed through self-adaptive shunt. The technology form alternating arcs between the tungsten electrode, workpiece, and welding wire, and induce the alternating arc based on the EN/EP current transition. The heat source utilized the EN arc melting wire with wire anode-tungsten electrode cathode, and the workpiece was cleaned by the EP arc of the tungsten electrode anode-workpiece cathode, achieving decoupling of arc heat and force transfer through proper adjustment. The applicability of the innovative source had been verified, and the influence of welding speed and wire height on arc behavior and droplet transition had been compared and analyzed in this article. The results showed that when the welding speed was 5.7 mm/s and the wire height was 8 mm, the morphology of the deposited layer was better and the droplet transfer was better. Furthermore, compared to traditional VPPA-WAAM, the adaptive-shunt alternating arc significantly increased the deposition efficiency and reduces the heat input to the substrate, while maintaining a balance between additive manufacturing quality and efficiency.