Self-equalizing Transition between Electro-magnetic Force and Surface Tension in Short Circuit CO₂ Welding

A new method of self-equalizing transition between Electro-magnetic force and surface tension using automatic adapting static characteristics for short-circuit transfer CO₂ welding is put forward in This paper. Based on the simplified model presenting the changing pattern of the surface shape during liquid bridge shrinking procedure,the character of surface tension in different form of the bridge is analyzed. Being considered the radius and height disturbance caused by the weld pool oscillation,the unstability in welding processing would be arise when the liquid bridge is not blown up in time if the shrinking is forced only by surface tension. In view of the relationships of shrinking force with its radius and current and the relationship of resistance of bridge with the radius, the method is designed. The experiment results showed that the damping speed of current during shrinking could be boosted to decrease the power accumulated before the bridge breaking up and to let up the spatter by using the method. Moreover the electro-magnetic force and surface tension are automatically equalized to confirm the drop transferring smoothly and the bridge is blown up in time so as to improve the welding stability greatly.