Numerical Simulation Of Arc Characteristics In Gas Pool Coupling Active TIG Welding

Gas Pool Coupled Activating TIG welding (GPCA-TIG) is a new method of Activating welding. It overcomes the disadvantages of small penetration, poor weld-forming and low deposition rate of TIG in high speed welding. This method through changing the way of importing active element, shielding gas is stratified flow in the welding torch. The inner layer gas is pure inert gas, and the outer layer gas is gas mixture including active element, and thus this method can achieve purpose for controlling the appearance of weld and increasing depth of penetration, and introducing active elements,this can obtain high quality welding forming,meanwhile, increase the penetration. In this method the electrode tip is divided into four pieces, and coupled arc is formed in the welding process, that is called the Coupling Arc Electrode GPCA-TIG welding. So that the arc pressure can be lowered than the traditional TIG welding. Thus this method can be applied to high current and high-speed welding in order to improve productivity.The arc characteristics of GPCA-TIG welding are different with the arc characteristics of traditional TIG because of stratified flow of shielding gas and special structure of tungsten tip. This paper is focused on numerical simulation of arc characteristics of TPCA-TIG welding. A two-dimensional steady state mathematical model for GPCA-TIG welding arc is established with the help of Computational Fluid Dynamics (CFD) software Fluent6.3. The arc characteristics of ordinary electrode GPCA-TIG welding are studied by means of secondary development for software, and the coupling arc characteristics are also simulated through the simplified model.By simulating ordinary electrode GPCA-TIG welding, distribution of temperature field,flow field,electric potential field and pressure field of arc are obtained. By changing the single welding process parameter, arc characteristics under different welding parameters are also gained, and from the perspective of numerical simulation, this paper analyzes the mechanism of arc pressure decreasing with the increasing of arc length on anode surface.Though simplifying the arc model for Coupling Arc Electrode GPCA-TIG welding. The distribution of temperature field,flow field,and pressure field are achieved by using this simplified model. And by changing the single welding process parameters, arc characteristics under different welding parameters are acquired. Coupling Arc Electrode GPCA-TIG welding can decrease arc pressure significantly by comparing the simulation result of ordinary electrode GPCA-TIG welding. The results of simulation have same trend with the results of experiment under the same parameters of welding.This paper is focused on numerical simulation of arc characteristics of TPCA-TIG welding. The results of simulation can reflect the effect of structure of welding torch on arc characteristics.It can produce a theoretical guidance on structure design of welding torch and development of welding process parameters, and has an important theoretical significance for in-depth study of mechanism of GPCA-TIG welding penetration mechanism and promoting its’ application.