Mathematical model and magnetic-control mechanism of the stability of rotating spray transfer

To realize stable rotating spray transfer in the region of high constant current is the key of realizing high deposition rate MAG welding process without helium in shielding gas and extending the welding current range of traditional MAG welding process. In this paper, the magnetic control mechanism of the rotating spray transfer is stated and mathematical model is given. Theoretic basis is established, which implements high deposition rate MAG welding process with magnetic control instead of helium in shielding gas.

Three‑Dimensional Numerical Study on the Metal Rotating Spray Transfer Process of High‑Current GMAW

A three-dimensional numerical model based on the volume-of-fluid(VOF)method is typically preferred for studying high-current gas metal arc welding(GMAW)metal transfer mechanism and then controlling it.It is informed that the rotating spray transfer is extremely complicated,and some researchers have focused on simplified models without considering the energy conservation to make analysis manageable for the unstable metal transfer process.Using our created numerical model,the metal transfer of high-current GMAW with shielding gas of different conductivities has been studied by analyzing acting forces and fluid flows in the metal liquid column,especially for the contributions of the self-induced electromagnetic force,equivalent volume force of the capillary pressure of the surface tension(Named surface tension force in this work),static arc pressure.It is found that the unbalanced electromagnetic force greatly promotes the metal rotating motion in 500 A metal inert gas(MIG)welding with pure argon shielding gas and it pushes the metal liquid column to rotate.Considering the arc constricting effect in active shielding gas by simply changing the arc conductivity,it is found that the metal liquid column no longer rotates,it turns to swing since the unbalanced electromagnetic force is large enough to break the rotating motion.The calculated results of the metal liquid column deflected angle and rotating/swing frequency agree well with the experiment of high-speed camera observations.