Study On Temperature Field Characteristics Of GMAW With Narrow Gap Oscillating Torch

Gas metal-arc welding with narrow gap is a highly efficient welding technique.In actual production,the swinging arc is often used in narrow gap welding to get the good weld forming.Due to the particularity of the narrow gap weld groove,the welding defects,such as unstable side wall penetration and poor forming quality,are very easy to occur during the welding process.To solve this problem,the welding temperature field can be studied to optimize the welding parameters and improve the welding quality.In order to get more accurate results of the temperature field by numerical simulation,selecting a suitable welding heat source model is very important.By analyzing the swing process of swing arc narrow gap welding,the equivalent heat source model is initially used for numerical simulation to obtain temperature field characteristics.Considering the influence of magnetic blow on the side wall of swing arc,a new heat source model is established based on the derivation process of Gauss heat source model and double ellipsoid heat source model,in which the effect on sidewall fusion was also considered into.At the same time,the different effect of each layer by single pass multilayer welding were considered respectively.A new heat source model based on the first layer welding and another heat source model based on the second,third and fourth level welding were established.A new heat source model considering the influence of temperature,convection,radiation and latent heat of phase change on material physical properties was used to simulate the temperature field of swing arc narrow gap MAG welding using the finite element simulation software COMSOL to verify the rationality of the heat source model.The cross-section of the weld is compared with the side wall section of the temperature field simulation results through actual experiments.It is found that the two depths of the side wall are basically the same,which established the foundation for further research on the influence of weld formation.The temperature field and the regularity of the thermal cycle curve were analyzed in this study through the simulation.By comparing the temperature field under different heat source models,it is found that the new heat source model is more suitable.The side wall fusion of U groove proved to be better after analyzing the temperature fields of different grooves.This study lays a foundation for further research on the influence of the weld formation.