卸载式激光同轴送粉喷嘴的研制

Development on Coaxial Feeding Nozzle with Unloading Carrier Gas for Laser Manufacturing

为了在激光快速成形过程中获得较高的粉末利用率并有效改善同轴喷嘴工作性能,研制了一种新型的载气卸载后送粉的激光同轴送粉喷嘴。应用气固两相流理论对卸载后的粉末被喷射出喷嘴后的粉末流场进行了分析计算,研究不同结构参数对粉末流场浓度分布规律及粉末流的汇聚性能(汇聚焦距和聚焦半径)的影响规律,并进行了送粉试验研究。结果表明:同轴送粉喷嘴的汇聚性能主要受粉末流汇聚角、喷嘴半径和宽度的影响,且汇聚角影响较大;同轴送粉喷嘴采用环形直通道渐缩送粉结构和卸载载气的送粉形式,粉末流的汇聚性能明显提高,可以有效地提高粉末的利用率。建立了粉末流简化物理模型,所建模型对同轴送粉喷嘴的设计和性能优化具有一定参考价值。

In order to obtain high utilization of powder and improve working performance of coaxial nozzle,a new coaxial feeding nozzle with unloading carrier gas was researched.Gas-solid two-phase flow theory was used to analyze and calculate the powder flow injecting from coaxial nozzle in coaxial powder feeding system with unloading carrier gas.The convergent distribution of powder flow and powder convergent performance（focus distance to nozzle exit and focus radius of powder flow） was studied and the powder feeding tests were made.The results indicate that the convergent performance of nozzle is concerned with the convergent angles,exit radius,exit width of nozzle and the convergent angles are of much effects on it,the convergent performance and powder utilization are improved clearly through adopting a structure with one through shrinkage annulus cavity to directly inject particles separated from carrier gas.The powder flow simple model was also presented and the conclusion will be benefit for coaxial nozzle design and performance improvement.