保护气流对CO2激光焊接铝合金的影响

利用3 kW高功率CO2激光器,通过改变保护气体流量和流动方向,对2 mm厚的A5083铝合金薄板进行了焊接实验研究.研究发现,小孔的稳定存在取决于保护气体对等离子体云的抑制效果,而侧吹保护气体对等离子体云的抑制效果主要取决于所形成的气流方向,从而影响焊接熔化特性.利用有限元法对激光焊接时保护气体在小孔内部和表面气流状况进行了数值模拟,通过对不同焊接条件下模拟形成的小孔气动扰流的气流场和压力分布云图的分析,解释了采用逆向侧吹保护气体吹除等离子体的方法,可以更有效地抑制等离子体云的产生,防止小孔塌陷,有利于维持小孔的稳定性.

Influence of Shielding Gas Flow on Welding Quality for CO2 Laser Welding of Aluminum Alloy

By changing the shielding gas flow rate and direction,laser welding of A5083 aluminum alloys with high power CO_2 laser is experimentally studied in this paper.The results show that under determinate welding condition,an additional plasma control secondary gas helps to suppress the formation of plasma.It is demonstrated that melting behavior is greatly affected by the gas flow rate and its direction.At the same time,the gas flow acting on the keyhole is simulated by finite element method(FEM).The gas flow fields of pneumatic circumferential motion and pressure distribution nephograms around and in the keyhole are obtained.Analysis shows that when plasma is blown backwards i.e.,in direction towards the trailing edge of the weld pool,plasma can be eliminated better.Plasma elimination is not the only advantage of this configuration.Keyhole is prone to stable and the generation of porosities is likely to be reduced greatly.