Numeral Simulation Of Variable Polarity Plasma Arc Welding Of Aluminum Alloy Based On Fluent

Variable polarity keyhole plasma arc welding has great potential in aluminum alloy welding,which can fully penetrate aluminum alloy plates with middle thickness by one single pass and get high welding quality.It is even known as the "zero defect" welding method.However,to obtain high weld quality,the ranges of appropriate plasma arc welding parameters are narrow,and the tolerance is less,which limits applications in national manufacturing.Through studying the theory and the physical process of variable polarity plasma arc welding,the ranges of appropriate welding parameters were expanded with higher process stability and welding quality.The numerical simulation software is used to simulate and analyze the process of variable polarity plasma arc welding,the perforation process of variable polarity plasma arc welding is studied theoretically.In this study,Fluent,a numerical simulation software for fluid dynamics,is used to build a transient three-dimensional model for the key-holing process of variable polarity plasma arc welding.Based on the theoretical analysis of the characteristics of heat source and arc force in the process of variable polarity plasma arc welding.A mathematical modeling for the heat and force on the welding pool is established,which has great influence on the formation of weld pool.The coupling arc force and heat are applied to the weld pool of the variable polarity plasma arc welding by the user-defined function of fluent.The keyhole shape and dimensions are tracked by using multiphase flow model and volume of fluid method.It displays the changes of the key-holing process of variable polarity plasma arc welding and discuss the influence of welding parameters on the stability of variable polarity plasma arc welding process preliminary.Based on this force-thermal coupling model of variable polarity plasma arc welding,extensive simulations are processed to explore the actual relationship between the welding process parameters and simulation parameters.Correspondence of parameters of variable polarity plasma arc welding with actual ones are find out finally.The numerical simulation of plasma arc welding key-holing process of 2219 aluminum alloy with thickness of 6 mm is achieved.Simulation analyze the effect of plasma gas flow rates on key-holing of variable polarity plasma arc welding preliminarily and reveal the regularity of plasma arc pressure before and afar all open keyhole is formed.It studies the influence of welding parameters on the arc pressure of variable polarity plasma arc welding quantitatively.This numerical simulation can use to analyze the physical phenomena that cannot be observed directly by the experiments.It has accumulated experience for the study of variable polarity plasma arc welding.It has a guide significance for engineering application.