Stability analysis of CO2 gas shielded welding short-circuit transition process based on GMAW dynamic model

Base on the arc phase and short-circuit phase and their relationship,the paper considers the changes of the extension of wire,the arc length,liquid bridge resistance and mass of liquid bridge,combines the improved"mass-spring"model with the loop model of welding power system,puts forward the critical judgment condition of droplet transition,and establishes a more accurate dynamic model for describ-ing the short-circuit transition process.The dynamic changes of short-circuit transfer frequency,welding current and voltage,contact droplet and residual droplet equivalent radius and droplet equivalent radius at different wire feeding speeds were calculated and analyzed,and com-pared with the experimental results.It shows that the fluctuation of droplet displacement,velocity and wire extension length at the optimal arc starting point is the smallest.The smaller the initial liquid bridge curvature radius is,the better the stability of short-circuit transfer is.