Forces analysis of droplets and accurate control of metal transfer in GMAW by utilizing droplet resonance

The significant contribution of the droplet resonance to detaching the droplet in gas metal arc welding has been experimentally verified in the previous study. The correlation between droplet natural frequency and droplet size makes droplet resonance a potential method for precise control of droplet size. In this paper, a dynamic analytical model is proposed to analyze the droplet resonance excited by the vibrating solid electrode to promote the realization of precise control of metal transfer. Simulations performed by this model are compared with those performed by the widely used mass-spring model as well as the experimental results. The two models both predict the droplet resonance and the variation of the phase of the oscillating droplet with the growth of droplet size when passing through the resonance region. Simulation results show that the inertial force due to droplet oscillation plays a vital role in detaching the droplet and resulting in metal transfer with a larger frequency compared with the conventional GMAW. The metal transfer parameters predicted by the newly proposed model are in reasonable agreement with the experimental results. The model can be used to conduct the accurate control of metal transfer utilizing droplet resonance.