Piezo-driven short-circuiting metal transfer in GMAW

Gas metal arc welding (GMAW) is one of the most commonly used welding process. The strong coupling characteristics of its heat and mass transfer makes it difficult to produce stable droplet transfer under small current. This paper proposes a piezoelectric actuator based high dynamic wire lock-release control process, in which the piezoelectric actuator expands to lock the welding wire, and its contraction releases the wire. During the wire lock-release process, the droplet can be actively driven to short-circuit the molten pool, and the inertial force generated during this dynamic process can be used to actively neck and break the short-circuit liquid bridge. The research results show that the addition of the combined piezoelectric actuator can significantly improve the short-circuit transfer in GMAW under low current, and the start and end of the short-circuit are both stable and controllable, avoiding the occurrence of random short-circuits, and no longer relying on the rapid rising of short-circuit current to force the necking of the liquid bridge. The short-circuit transfer frequency is significantly improved, up to 130 Hz under DCEP 100 A welding current, and up to 100 Hz under DCEN mode.