基于激光光斑直径的激光熔覆粉末汇聚特性数值模拟

Numerical simulation of convergence characteristics of laser cladding powder based on laser spot diameters

为了探索激光熔覆过程激光与粉末流的耦合作用机理,通过激光熔覆喷粉数值模拟,研究送粉速度对粉末汇聚特性的影响规律,随着送粉速度的增加,粉末流焦点直径逐渐减小,粉末流获得良好的收敛性。通过分析激光光斑模拟图,研究激光光斑大小与粉末流焦点直径的作用关系,并通过激光熔覆实验进一步验证,当粉末流焦点直径接近激光光斑直径时,熔覆形貌较好,但随着送粉速度的进一步提升,粉末流焦点直径减小,基体热影响区域增大,熔覆表面形貌变差,最终获得最佳送粉速度为17.0 m/s。研究成果为激光熔覆粉末利用率与激光熔覆形貌控制提供理论依据。

This paper aims to explore the coupling mechanism of laser and powder flow in the laser cladding process.The influence of powder feeding speed on powder convergence characteristics was investigated by a numerical simulation of laser cladding powder injection.This simulation demonstrated that the powder flow had good convergence as its focus diameter gradually decreased with the increase of powder feeding speed.Through the analysis of laser spot simulation diagrams,the relationship between the laser spot size and the focus diameter of the powder flow was examined and further verified by a laser cladding experiment.The results indicated that the cladding morphology was better when the focus diameter of the powder flow was approximate to the laser spot diameter,but it became worse as the focus diameter decreased and the heat affected area of matrix increased by speeding up powder feeding.The optimum feeding speed was confirmed to be 17.0 m/s.The findings provide a theoretical basis for the powder utilization ratio and the morphology control of laser cladding.