关键词: 熔滴复合电弧增材制造, 熔池行为, 熔滴过渡模式, 聚并, 堆积层表面形貌

Abstract:

The interaction of the tilted Tungsten Inert Gas （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 deposition morphology， a three-dimensional numerical model based on Computational Fluid Dynamics （CFD） was developed to investigate the molten pool behaviors during droplet-arc hybrid additive manufacturing. Deposition experiments 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. The results show that when droplet transfer mode changes from low-frequency large droplet to high-frequency small droplet， the coalescence behavior between the droplet and the TIG arc molten pool shifts from partial coalescence to complete coalescence. As a result， the “fish scale” pattern characteristic on the surface of the deposited layer is significantly reduced. This study provides a perspective in understanding the physical phenomena involved in droplet-arc hybrid additive manufacturing and lays the foundation for the optimization of process parameters.

Key words: droplet-arc hybrid additive manufacturing, molten pool behaviors, droplet transfer mode, coalescence, surface morphology of deposited layers