基于改进热源模型的铝合金MIG焊数值分析

Numerical analysis of MIG welding of aluminum alloy based on improved heat source model

采用CMOS高速摄像机检测和分析铝合金熔化极气体保护焊(MIG焊)熔滴过渡行为,确定MIG焊熔滴的过渡频率和速度.在理论分析MIG焊热源特性、热作用模式以及焊缝形貌前提下,从宏观焊接热过程出发,提出并开发了适用于MIG焊的组合体积热源分布模式,MIG焊电弧被处理描述为经典的双椭球体热源模型,熔滴能量作用模式被表示成均匀球体热源模型.同时,在均匀球体热源模型中加入了熔滴热能和动能,实现了熔滴对MIG焊熔池冲击作用的影响.基于上述热源模型,建立了铝合金MIG焊温度场有限元模型,对厚板铝合金MIG焊温度场进行了模拟.结果表明,模拟获取的焊缝熔合线走势及形貌和实际焊接结果相吻合,证明开发的热源模型能够准确描述MIG焊指状熔深特性和热传导过程.

CMOS high-speed camera was used to detect and analyze the transition behavior of aluminum alloy MIG welding droplets and to determine the transition frequency and speed of MIG droplets.Under the premise of theoretical analysis of MIG welding heat source characteristics,heat action mode and weld seam morphology,a combined volumetric heat source distribution model applicable to MIG welding was proposed and developed from the macroscopic welding thermal process.The MIG arc was treated and described as a classical double ellipsoidal heat source model,and the droplet energy action mode was represented as a uniform spherical heat source model.At the same time,the droplet thermal and kinetic energy are considered and added to the uniform sphere heat source model to realize the effect of droplet on the impact action of the MIG welding pool.Based on the above heat source model,a finite element model of the MIG welding temperature field of aluminum alloy was established.The temperature field of thick plate aluminum alloy MIG welding was simulated nu-merically. The results show that the trend and morphology ofthe weld fusion line obtained by simulation are in good agreementwith the actual welding results. It is proved that the developedheat source model considering droplet thermal and kineticenergy can accurately describe the finger penetration characteristicsand heat transfer process of MIG welding.