横向稳态磁场作用下微束等离子电弧数值分析

Numerical analysis of micro-plasma arc under the action of transverse steady state magnetic field

为分析外加横向稳态磁场作用下电弧特性与电弧对工件热、力输入的变化规律,本文建立了微束等离子电弧三维模型,将外加磁场简化为背景场添加至模型,使用有限元分析软件COMSOL进行求解计算。结果表明:外加横向稳态磁场作用下,喷嘴内部各项特性均未发生较大变化,喷嘴下方电弧等离子体在洛伦兹力的作用下向x负方向移动,电弧温度、等离子体速度与电流密度等均发生相应的偏转,因此造成电弧对工件的热输入减小、压力降低。最后在薄壁件上进行了焊接试验,试验过程中拍摄的电弧轮廓与仿真电弧形态基本一致,加磁区域堆焊层余高增加、熔宽减小,焊缝向两侧"下塌"现象消失。外加横向稳态磁场可减小电弧对熔池的热、力输入,进而改变焊缝形貌,抑制薄壁件堆焊过程中由于热、力输入过大而产生的"下塌"现象,有利于薄壁件的堆焊成形。

In order to analyze the characteristics of the arc,and the evolution of the heat and force input from the arc to the workpiece under the external transverse steady-state magnetic field,a three-dimensional numerical model of the micro-plasma arc was established in this paper.The external magnetic field is simplified as a background and added to the model.The finite element analysis software COMSOL is used for calculation.The results show that under the external transverse steady-state magnetic field,the arc characteristics in the nozzle have not changed greatly,but the arc plasma under the nozzle moves to the x-negative direction due to Lorentz force,and all the arc temperature,plasma speed and current density deflect correspondingly,resulting in the decrease of heat input and pressure of the workpiece caused by the arc.Finally,the welding test of the thin-walled parts was carried out.The arc profile captured during the test was basically the same as the simulated one.The residual height of the cladding layer increased,the fusion width decreased,and the downward collapse of weld line on both sides disappear in the magnetic field.The external transverse steady-state magnetic field can reduce the heat and force input of the arc to the molten pool,thereby causing the shape change of the weld,and suppressing the downward collapse caused by excessive heat and force input during the welding of thin-walled parts,which is beneficial to the cladding of thin-walled parts.