大口径超轻量化碳化硅反射镜超精密铣磨技术(特邀)  

Ultra-precision milling technology of large-aperture ultra-lightweight SiC mirror(invited)

作　　者：殷龙海 李延伟 李骏驰 李鑫 黄贺 谢新旺 房圣桃 张斌智 Yin Longhai;Li Yanwei;Li Junchi;Li Xin;Huang He;Xie Xinwang;Fang Shengtao;Zhang Binzhi(Ji Hua Laboratory,Foshan 528200,China)

机构地区：[1]季华实验室,广东佛山528200

出　　处：《红外与激光工程》2023年第9期23-30,共8页Infrared and Laser Engineering

基　　金：季华实验室自主立项项目(X200021TC200)。

摘　　要：在分析了超轻量化大口径碳化硅(SiC)反射镜(轻量化率≥90%)表面去除原理和难点的基础上,为了实现此类型反射镜的快速加工,提出了一种采用有限元分析进行验证的五轴高效超精密铣磨方法。通过对反射镜铣磨过程中产生共振的机理进行分析,解释了共振的原因,利用有限元分析方法进行仿真模拟,验证了加工过程镜面不会被破坏且系统不发生共振,设计环形工装支撑并对口径Ф510 mm、壁厚4 mm、轻量化率92%的SiC反射镜进行快速铣磨加工。反射镜初始面形峰谷(PV)值为956.1μm,镜面去除量为1 mm,加工时间仅为48 h,相较于人工研磨研制周期降低了90%。通过检测,反射镜面形PV值为3.5μm,满足反射镜抛光前面形精度优于4μm的要求。Objective With the increasing requirement of satellite imaging quality,the aperture of the main mirror of the optical system is also increasing,and the large-aperture mirror must be designed with lightweight structure.In order to improve the processing efficiency,the main mirror needs to be roughed before polishing to remove the surface allowance during the sintering casting of the mirror embryo,but the ultra-thin and lightweight design of the mirror makes roughing very difficult.On the one hand,the ultra-thin mirror increases the brittleness of the mirror itself,and it is easy to crack the mirror surface by excessive stress during processing.On the other hand,the design of the lightweight hole on the back of the mirror will reduce the stiffness and natural frequency of the mirror,resulting in the mirror easily resonating with the processing system during the milling process,so that the mirror is destroyed.At present,manual grinding or ultrasonic vibration milling methods are generally used for rough machining,but these two processing methods have low surface removal efficiency and long processing cycle,which can't meet the needs of space optical systems for development cycle.Therefore,it is necessary to establish a milling method with higher surface removal efficiency and accuracy.For this purpose,an ultraprecision milling technology of large-aperture ultra-lightweight SiC mirror is established in this paper.Methods A five-axis high-efficiency milling ultra-precision machining method was proposed by using finite element analysis.Through the analysis of the resonance mechanism in the milling process of the mirror,the causes of resonance were explained(Fig.4).The finite element analysis method was adopted to simulate and verify that the mirror would not be damaged and the system would not have resonance during the machining process(Fig.6-8).An ultra-lightweight SiC mirror was quickly milling(diameter is 510 mm,the wall thickness is 4 mm,the lightweight rate is 92%)with the support of designed ring tooling(Fig.10).

关 键 词：铣磨 SiC反射镜 有限元分析 超轻量化 

分 类 号：TN305.2[电子电信—物理电子学]