脉冲MIG焊熔池行为的数值模拟研究

Research on Numerical Simulation of Weld Pool Behavior in Pulsed MIG

基于流体力学、热力学及电磁学等理论建立二维脉冲MIG焊熔池数学模型,在Fluent软件中通过用户自定义程序(UDF)添加模型所需的热源、动量源项以及定义材料的物性参数,对焊接过程进行数值模拟,分析各驱动力对脉冲MIG焊熔池行为的影响以及熔池在脉冲周期内的变化规律。模拟结果表明,在焊接过程中马兰戈尼力对熔池影响最大,其次为电弧压力,然后为电磁力,浮力影响相对较小。在各驱动力复合作用时,熔池表层的熔池形态以马兰戈尼力为主导,熔池内部以电磁力为主要作用力,造成熔池内形成了两种不同方向的环流。熔滴冲击力主要作用于熔池表层,对熔池内部影响较小。脉冲MIG焊高速摄像试验表明,实际熔池形态与模拟结果吻合良好,验证了熔池模型的合理性。

The mathematical model of two-dimensional pulsed MIG weld pool was established based on the theories of fluid mechanics,thermodynamics,electromagnetism and so on.In Fluent software,the user defined program(UDF)was used to add the required heat source,momentum source items of the model and the material property parameters of the defined material,and the welding process was numerically simulated.It was analyzed that the influence of each driving force on the behavior of pulsed MIG welding pool and the change rule of the pool during the pulse period.The simulation results showed that Marangoni force had the greatest influence on the molten pool during welding,the second was arc pressure,followed by electromagnetic force,buoyancy had relatively little effect.Under the combined action of various driving forces,the surface of the molten pool was dominated by Marangoni force,and the internal of the molten pool was dominated by electromagnetic force,which resulted in two kinds of circulation in different directions in the molten pool.The droplet impact force mainly acted on the surface of the molten pool and had little effect on the interior of the molten pool.The pulsed MIG welding high-speed imaging test showed that the actual molten pool morphology was in good agreement with the simulation results,which verified the rationality of the molten pool model.