纵向交变磁场及脉冲电流下TIG焊接电弧模拟

Numerical Simulation of TIG Welding Arc with External Longitudinal Alternate Magnetic Field and Pulse Current

以建立的二维轴对称TIG焊电弧模型为基础,研究外加纵向交变磁场及脉冲电流对电弧所产生的影响。研究表明,当外加磁场强度为0.03T,交变频率为1000 Hz的纵向磁场时,电弧随磁场方向的改变而发生周期性变化。当磁场方向为正时,电弧呈现收缩下压趋势,存在中空现象;当磁场方向为负时,电弧呈现拉长趋势,阴极斑点有所上移。当同时施加一脉冲频率为1000 Hz且与交变磁场相匹配的脉冲电流时,电弧根据电流大小可分为两个阶段,即工作阶段与维弧阶段。当电弧处于工作阶段时,磁场方向为正,电弧收缩下压,更有利于母材熔化;当电弧处于维弧阶段时,磁场方向为负,电弧能量大大下降,仅能维持电弧存在。

Based on the two-dimensional axisymmetric TIG welding arc model, the influence of external longitudinal alternating magnetic field and pulse current on arc was studied. The results show that when the external magnetic field intensity is 0.03 T and the alternating frequency is 1000 Hz, the arc changes periodically with the direction of magnetic field.When the direction of the magnetic field is positive, the arc contracts and exhibits a hollow bell shape. When the direction of the magnetic field is negative, the arc tends to be elongated and the cathode spot moves up. When a pulse current with the pulse frequency of 1000 Hz is applied at the same time and it matches the alternating magnetic field, the arc can be divided into two stages according to the current, the working stage and the pilot arc stage. When the arc is at the working stage, the magnetic field direction is positive and the arc contracts, which is more conducive to the melting of the parent material. When the arc is at the pilot arc stage, the magnetic field direction is negative and the energy of arc drops greatly, which can only maintain the existence of arc.