等离子弧焊中电弧反翘现象的数值模拟

Numerical simulation of arc reflection in plasma arc welding processing

根据流体的质量、动量、能量守恒方程,建立了穿孔等离子弧焊接过程中的等离子电弧三维数学模型,用磁矢量法求解磁场问题。模型包括了一部分喷嘴和钨阴极,小孔也被包含进模型中。利用ANSYS有限元分析软件求解模型,得到等离子电弧的温度分布,以研究等离子弧焊中电弧反翘现象。结果表明,等离子电弧反翘随小孔尺寸的增大而减弱,电弧尾焰随小孔尺寸的增大而增强;而适当的增加焊接速度以使小孔轴线与电弧轴线之间形成一定的偏差是形成等离子电弧反翘现象的必要条件;焊接电流主要是通过改变小孔尺寸而对电弧反翘产生影响。

A three-dimensional mathematical arc model in keyhole PAW(plasma arc welding) process was established based on the mass,momentum and energy conservation equations.Magnetic-vector method was employed to solve the magnetic problem.A part of nozzle and tungsten electrode,as well as keyhole,were included into the model.The model was solved with ANSYS software.The simulated temperature was taken to indicate the arc reflection occurring in PAW processing.The plasma arc can be divided into main body,arc reflection and arc wake flame,which can be obtained from the simulated result.The effects of the keyhole dimension and offset between the arc axis and keyhole axis on the arc reflection were studied.The simulated results show that the arc reflection gets weaker and arc wake flame gets stronger with the increase of keyhole dimension,and a higher welding velocity to induce the offset between the arc axis and keyhole axis is necessary to the appearance of arc reflection,and the effects of welding current on the arc reflection are exentedmainly through changing the keyhole dimension.