基于印压断裂力学理论分析了磷酸二氢钾晶体表面缺陷面积与中位裂纹深度的关系.在刀具参量和主轴转数一定的情况下, 采用不同切削深度和进给速率对磷酸二氢钾晶体进行单点金刚石飞切加工实验, 并计算晶体表面单位面积缺陷的占比系数.实验结果表明, 晶体表面缺陷深度与面积占比系数成正相关, 与理论分析结果相符, 进而提出了利用计算晶体表面缺陷占比系数估测缺陷深度的方法.最后基于该方法得到高效率切削步骤, 并加工获得了表面粗糙度算术平均值优于5 nm的超光滑晶体表面.

On the basis of the theory of indentation fracture mechanics, the relationship between the surface defect area and median crack of potassium dihydrogen phosphate crystals were analyzed theoretically. In the machine tool parameters and spindle speed in certain circumstances, the potassium dihydrogen phosphate crystal was processed by single point diamond turning under different cutting depth and feedrate. And then the ratio coefficient of unit area defect on the surface of the crystal was calculated. The experimental results show that the depth of surface defect is proportional to the ratio coefficient of area, which is consistent with the theoretical analysis, so the estimation method for the depth of surface defects by calculating the ratio coefficient of the surface defect area was processed. Finally, the high efficiency cutting process based on this method was proposed, the obtained arithmetic mean height value of surface roughness is better than that of 5 nm by the actual processing.