Numerical Simulation Of Constricted TIG Arc By Insulating Solid Wall In Ultra-narrow-gap Welding

Combines the advantages of TIG welding method and Ultra-narrow gap welding technology,Ultra-narrow gap TIG welding has higher production efficiency and better mechanical properties of the joint.However,the groove sidewall of Ultra-narrow gap changes the electrical field distribution,causing the arc current to shunt to the sidewall,which is likely to cause the lack of fusion on the corner of square groove.The method is proposed to control the arc in ultra-narrow gap welding process with combined regulation of sheet tungsten electrode and insulating solid wall,and the three-dimensional quasi-steady state mathematical model of insulated solid wall constrained sheet tungsten electrode arc in ultra-narrow gap welding is presented based on the fluid dynamic equations and Maxwell equations.On this basis,distribution of the constrained arc physics under different welding process parameters were investigated with FLUENT and the numerical simulation data agree well with the test data.The results show that the constriction effect of insulting sheet,the sheet slanting tungsten electrode to lead the current density and the arc lags behind sheet slanting tungsten electrode's motion are the main factors that changes the distribution of arc physics;The temperature field,velocity field,electric field and current density of arc are symmetric in the width direction of the groove.The distribution range of temperature field and electric field expand in length direction of the groove,and the higher temperature in arc,cathode jet and current density shift along this direction.The stronger the constriction effect of insulting sheet will make the arc high temperature zone,cathode jet and current density shift more,and the peak temperature,flow velocity and current density will increase with the increase of restraint.Adjusting the constraint height can increase the arc current density and limit the sidewall shunt,while changing the constraint width can only increase the current density.Larger current can increase the peaks of arc temperature,flow rate and current density,while arc high temperature zone,cathode jet and current density will further shift to the small discharge gap;smaller arc length will make ultra-narrow gap groove The temperature field of the arc in the longitudinal direction shrinks,and the peak of arc temperature and the current density are increased.