全熔透钨极惰性气体保护电弧焊熔池表面变形动态过程的数值分析

Numerical Analysis of Dynamic Surface-deformation of Fully-penetrated Gas Tungsten Arc Welding Molten Pool

基于能量守恒和质量守恒原理,并依据能量最小化理论,推导出全熔透钨极惰性气体保护电弧焊(Gas tungsten arc welding,GTAW)熔池自由上、下表面变形的控制方程组,并探讨与文献给出的熔透熔池上、下表面变形控制方程组的异同,给出控制方程组中将熔池上表面变形和下表面变形耦合为一个统一整体的拉格朗日参数的求解方案。分别对GTAW焊接不锈钢和低碳钢薄板从引弧到熔透并达到准稳态的全过程中熔池上、下表面变形的动态演变进行预测和分析,从中提取出了可用于表征工件熔透与否的参数,为基于正面视觉检测的背面熔透智能控制提供了依据。

Based on the principles of energy and mass conservation as well as energy minimization theory within a whole system of fully-penetrated gas tungsten arc welding（GTAW） molten pool,the governing equations are derived to describe the pool surface-deformation on both sides.The solution scheme for determining the Lagrange parameter is given for the coupled upper and bottom pool surface-deformation equations which are unified with a single Lagrange parameter.Through predicting and analyzing the dynamic variation processes of both upper and bottom pool surface-deformation during the period from the weld pool formation to its quasi-steady state for GTAW stainless steel and low carbon steel,the variables are extracted to characterize and judge the condition whether the workpiece is penetrated or not.It lays foundation for realizing welds penetration control based on front-side vision inspection.