Z轴离焦量对激光熔覆成形的影响

为了深入探究Z轴离焦量对激光熔覆成形的影响，综合考虑Z轴离焦量导致的熔池粉末利用率、激光能量密度等因素对熔覆成形的影响，通过改变激光功率、扫描速度、气流量、离焦量4个因素进行L16（44）正交试验，以及Z轴离焦量变化的单因素试验，揭示激光功率、扫描速度、气流量、离焦量4个因素对熔覆成形的耦合作用规律.正交试验结果表明，离焦量、激光功率、扫描速度、气流量在激光熔覆成形中都扮演着重要角色，对熔覆效率的因素影响主次为：激光功率>气流量>离焦量>扫描速度.Z轴离焦量单因素试验结果表明:激光熔覆过程需要一定的离焦量才能获得最佳熔覆质量；当离焦量为5mm时，熔覆层的高度最高；当离焦量小于或大于5mm时，熔覆层高度降低；当Z轴离焦量逐渐增加时，粉末利用率先逐渐增加再逐渐减少.
Abstract：The variation of distance between laser head and substrate (named defocus distance) has a considerable effect on powder utilization efficiency and energy density, therefore affecting the laser cladding forming (LCF) process. Orthogonal experiments L16 (44) of the four parameters: laser power, scanning speed, gas flow rate and defocusing distance and single factor experiment of the defocusing distance along Z axis were conducted to investigate the coupling effects of these parameters on LCF process. The result of orthogonal experiment suggests that all four parameters play important roles in LCF, and the order of factors which affect the cladding efficiency is: laser power>gas flow rate>defocusing distance>scanning speed. The result of the single factor experiment indicates that the optimal cladding quality occurs when the defocusing distance reaches a certain level. The maximum cladding layer height can be achieved when the defocusing distance is 5mm. The cladding layer height is reduced when the defocusing distance is less or larger than 5mm. It is proved that the powder utilization efficiency gradually increases and then decreases when the defocusing distance keeps increasing.