旁路耦合微束等离子弧堆垛与熔池动态行为数值模拟

Study on the Dynamic Behavior of Molten Pool during the Stationary Pileup of the Double-electrode Micro Plasma Arc Welding

针对旁路耦合微束等离子弧增材制造堆垛过程中熔滴与熔池的动态行为,在考虑自由表面的情况下,建立一个熔滴与熔池耦合作用的传热与传质模型,分析表面张力和熔滴冲击动量共同作用下的熔池瞬态形状和复杂的流体流动行为,并通过试验验证了模型的正确性。研究发现:当熔滴携带热量冲击熔池时,熔池温度升高,熔池中的最大速度可增大到2.06 m/s;随着进入熔池的熔滴数目增加,熔池余高增加,熔宽增加,而熔深基本不变;同时,当旁路电流增大时,母材温度较低,造成更浅的熔深,更高的余高和更小的熔宽,熔池液态金属的流动也不稳定;增加熔滴间隔时间后,每一层的顶部半径随着层数增加而减小。

Aiming at the dynamic behavior of the droplet on the molten pool during the stationary pileup process of the double-electrode micro plasma arc welding,a mathematical model of the coupling effect between the droplet and the molten pool is established,the flow shape of the molten pool and the complex fluid flow are mainly calculated by the combination of surface tension and droplet impact momentum.It is found that,when the droplet carries heat to hit the molten pool,the bath temperature rises.When the droplets impact the pool of the moment,the maximum speed in the pool can be increased to 2.06 m/s.With the increase in the number of droplets entering the molten pool,the bath height increases,the melting width increases,the penetration depth is almost constant.As the bypass current increases,the base metal temperature is low.Resulting in a lighter depth,a higher height and a smaller weld width.Molten pool liquid metal flow is not stable.After increasing the cooling time,the radius of each layer decreases as the number of layers increases.