激光制造, 同轴送粉, 送粉喷嘴, 载气卸载, 结构优化

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. 