从实验研究角度探讨了激光精微打孔过程中孔深度方向上的几何特征随激光工艺参数的变化规律。为更精确描述深度方向上孔型几何特征的变化, 采用不同深度位置上的孔直径、局部锥度作为激光成孔的几何量化指标并加以研究。实验工艺参数包括激光束的离焦量和脉冲个数。通过实验, 建立了孔型几何参数与激光工艺参数之间的量化关系。研究发现, 离焦量对孔型几何特征具有显著的影响, 上锥度随离焦量的增加呈近似线性递减的趋势, 最终趋于零锥度; 而下锥度随离焦量的增加呈先下降后上升的趋势, 在-0.5 mm～＋0.5 mm的离焦量范围内出现零锥度。脉冲个数对孔几何形状的影响在大离焦的情况下才比较明显, 并且一旦形成通孔, 脉冲个数将不会对孔形状产生任何影响。

The effect of laser process parameters on hole geometry variation along longitudinal axis in laser percussion drilling is investigated experimentally. For more detail depiction of geometry characteristics change along the longitudinal axis, diameters and local tapers at different depth of the hole are selected as the hole shape indexes and target research functions. Experimental process parameters include the amount of laser beam defocus and the number of pulses. The quantitative relationship between the geometrical parameters of the hole and the process parameters of the laser has been established. The results show that the amount of defocusing has a significant effect on the hole geometry. The upper taper tends to decrease approximately linearly with the increase of defocusing distance, and finally tends to zero taper, while the lower taper tends to decrease first and then increase with the increase of defocusing power, and zero taper occurs within the defocusing range of -0.5 mm ~ + 0.5 mm. The effect of the number of pulses on hole geometry is only noticeable in the case of large defocusing and once the through-hole is formed, the number of pulses will have no effect on hole geometry.