飞秒激光加工对熔覆层侧壁粗糙度的影响

Effect of femtosecond laser micromachining on the roughness of cladding sidewalls

针对熔覆成型件表面粗糙的难题,提出了在成形过程中对熔覆层侧壁进行飞秒激光精密加工的方法,重点研究了精密加工过程中飞秒激光的能量密度、能量分布、光斑重叠率对熔覆层侧壁粗糙度的影响规律,结果表明:当焦平面处飞秒激光的能量为高斯分布,加工得到的熔覆层侧壁表面粗糙度Ra<3μm时,激光能量密度介于0.12~0.34 J/cm^2之间;当能量为平顶分布并且加工后熔覆层侧壁表面粗糙度Ra<3μm时,最佳能量密度范围为0.13~0.66 J/cm^2;同等参数条件下,平顶能量分布激光加工得到覆层侧壁粗糙度小于能量高斯分布时的粗糙度数值。熔覆层侧壁粗糙度随光斑重叠率的增加先减小后增大,实验获得的最佳重叠率范围为78%~85%。

In order to enhance the surface finish of Laser Direct Deposition of metallic components, a method that applies femtosecond laser to fabricate the cladding layer was proposed in this paper. The effects of the energy density, distribution, and the overlapping ratio of the laser on the sidewall quality of the cladding layer were studied in experiment. The experiment results show that the roughness of the achieved cladding side-wall layer can be smaller than 3 μm once the energy density in the region is 0.12-0.34 J/cm2 for the Gaussian-shape laser or 0.13-0.66 J/cm2 for the rectangle-shape laser. And the cladding sidewall layer fabricated by Gaussian-shape laser possessed more excellent surface quality than the product fabricated by rectangle-shape laser with same parameters. The roughness of the cladding sidewall layer decreases and then increases with the increase of the laser overlapping ratio, and the optimal region of overlapping-ratio is 78%-85%.