熔滴复合电弧增材制造中，连续可控的单分散熔滴流与倾斜钨极惰性气体（tungsten inert gas welding, TIG）电弧熔池的交互作用，决定了堆积层表面形貌、内部组织和制造缺陷等。为探明熔滴过渡模式对堆积层形貌的影响规律，基于计算流体力学法构建了熔滴复合电弧增材制造过程三维瞬态熔池行为数值模型，与单道单层堆积成形实验结果相结合，比较性地分析了两种典型熔滴过渡模式下的熔滴冲击、聚并、铺展、凝固全过程。研究结果表明，当熔滴由低频大滴模式过渡至高频小滴模式时，熔滴与TIG电弧熔池的聚并行为由部分聚并转变为完全聚并，进而导致堆积层表面的“鱼鳞纹”结构特征明显减小。该研究对于进一步深入理解熔滴复合电弧增材制造机理、优化堆积工艺参数具有重要意义。
The interaction of the tilted TIG welding arc and the continuously controllable droplets is a complex phenomenon, which determines the surface morphology of deposited layers, the microstructure and internal defects of fabricated parts in droplet-arc hybrid additive manufacturing. To reveal the influence law of the droplet transfer mode on the dep-osition morphology, a three-dimensional numerical model based on computational fluid dynamics (CFD) was devel-oped to investigate the molten pool behaviors during droplet-arc hybrid additive manufacturing. Deposition experi-ments were conducted to verify and calibrate the numerical model. The process of drop impact, spreading, retraction and solidification is illustrated and analyzed using calculated results. It was found that when droplet transfer mode changes from low-frequency large droplet to high-frequency small droplet, the significant fish-scale ripples on the top surface of deposited layers occurred from the smaller droplets into the larger ones through partial coalescence. This work provides a perspective in understanding the physical phenomena involved in droplet-arc hybrid additive manu-facturing and lays the foundation for the optimization of process parameters.
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