超精密飞刀切削加工表面中频微波纹产生机理

Mid-Spatial Frequency Micro-Waviness on Machined Surfaces by Ultra-Precision Fly-Cutting

超精密飞刀切削是一种重要的超精密加工手段,安装大飞刀盘的超精密铣床能够加工大口径超精密光学元件,加工表面具有很高的面形精度和很低的表面粗糙度值.但是加工表面普遍存在中频微波纹(空间周期从100μm到300μm,幅值低于0.1μm),极大影响了光学元件的使用.超精密铣床的主轴旋转精度对加工工件影响很大,尤其是主轴轴线偏转会使安装在大飞刀盘外缘处的刀具产生很大位移.为此,建立了适用于空气静压轴承支撑的立式主轴角位移欧拉动力学方程,推导出方程解析解,得出主轴运动规律及其对表面中频微波纹的影响,并设计实验进行验证.最终给出了抑制中频微波纹的工程措施.

Ultra-precision fly-cutting is an important ultra-precision processing technique and the ultra-precision milling machine with big fly-cutting pan fixed can produce optical components with large diameter,the machined surface of which is high in profile accuracy and low in surface roughness.However,mid-spatial frequency micro-waviness（spatial period from 100 μm to 300 μm and amplitude below 0.1 μm）,which is common on machined surfaces,has great impact on the performance of optical components.The stability of the axes orientation of gas journal spindles has great effect on the cutting precision,especially when the cutter is fixed on the outer edge of the big fly-cutting pan.Euler′s dynamic equations were proposed for angular displacement calculation of gas journal spindles,and the analytic solution of the equations was deduced,so that the movement rule of spindles and its influence on the mid-spatial frequency micro-waviness are concluded and verified with tests.Finally the engineering approach was put forward to restrain the mid-spatial frequency micro-waviness on machined surfaces.