基于增材制造的激光焊接保护喷嘴设计

Design of Laser Welding Protective Nozzle Based on Additive Manufacturing

针对钛合金等化学活性强的金属焊接易氧化,导致焊接质量严重下降的问题。以钛合金激光焊接试验保护装置为研究对象,以获得良好焊接保护效果为目的,设计了一种双层同轴激光焊接保护喷嘴。运用Fluent流场仿真软件对双层同轴保护喷嘴的内外层壁面结构、外层保护喷嘴进气口数量、进气口角度、出气口处有无螺旋结构以及保护气流量等参数进行了仿真优化,通过对比保护区域气流的保护效果,获得了最终的保护喷嘴结构。采用增材制造技术对优化后的保护喷嘴进行了加工制造,通过改变内外层喷嘴保护气体的流量对所设计的激光焊接保护喷嘴进行了钛合金激光焊接试验验证,并与旁轴喷嘴的保护情况进行对比。结果表明:具有弧型内外壁面结构、4个45°进气口以及出口处有倾角为30°螺旋结构的保护喷嘴,仅对内层喷嘴通入保护气体时,保护范围有限,焊缝颜色为深黄色,氧化污染严重。随着外层保护气体流量的不断增加,焊缝颜色变为黄色、银白色、蓝色。在内外层保护气体流量分别通入为10 L/min和20 L/min时焊接保护效果最好。且保护效果不受焊接方向变化的影响,能够对工件形成良好的气体保护环境。

Aiming at the problem of easy oxidation in welding of chemically active metals such as titanium alloy,which leads to serious deterioration of welding quality.Taking the protective device of titanium alloy laser welding as the research object,to obtain a good welding protective effect,a kind of double coaxial laser welding protection nozzle is designed.The flow field simulation software Fluent is used to simulate and optimize the parameters of the double-layer coaxial protection nozzle,including the inner and outer layer wall structure,the number of the outer protection nozzle inlet,the inlet Angle,whether there is spiral structure at the outlet and the flow rate of the protection nozzle.The final protection nozzle structure is obtained by comparing the protection effect of the airflow in the protection area.The optimized protective nozzle is fabricated by additive manufacturing technology.The titanium alloy laser welding experiment is carried out on the designed laser welding protective nozzle by changing the flow rate of the protective gas of the inner and outer nozzle,and the protection condition is compared with that of the side-axis nozzle.The results show that for the protective nozzle with an arc shaped inner and outer wall structure,four 45°air inlets,and a 30°spiral structure at the outlet,the protection range is limited when protective gas is only applied to the inner nozzle,and the weld color is dark yellow,resulting in severe oxidation pollution.As the flow rate of the outer protective gas continues to increase,the weld color changes to yellow,silver white,and blue.The welding protection effect is best when the flow rates of the inner and outer protective gases are respectively 10 L/min and 20 L/min.And the protection effect is not affected by changes in welding direction,which can create a good gas protection environment for the workpiece.