碳化硅反射镜柔带磨削方案设计与验证

Design and Verification of Soft Belt Grinding Scheme for Silicon Carbide Mirror

碳化硅材料比刚度高、导热性好、热稳定性好,是一种优良的反射镜材料,在空间光学遥感器中有着广泛的应用。同时,它具有硬度高、脆性大的特点,给反射镜加工带来困难,且加工周期长。比较了碳化硅材料不同加工技术的优缺点,选择了机器人柔性砂带磨削技术作为研究对象。针对某1550mm直径碳化硅反射镜坯加强筋的去除要求,设计了一套新型机器人柔带磨削系统,利用有限元方法对加工中的镜体应力进行了分析,并完成了某镜坯加强筋的去除,残余筋高度0.5~1mm。反射镜镜坯在完成镜面精磨、镀膜等处理后,利用干涉仪测试面形RMS为0.0157λ(λ=632.8nm),满足使用需求。遥感器于2020年发射,反射镜在轨运行表现良好。

Because of the high specific stiffness,the excellent thermal conductivity and thermal stability,Silicon Carbide(SiC)is widely used as the main mirror material of space optical remote sensor.At the same time,it has the characteristics of high hardness and brittleness,resulting in difficulty of mechanical machining and long processing cycle.In this paper,the machining technology of silicon carbide material is analyzed,the advantages and disadvantages of machining technology schemes are compared,and the robot flexible belt grinding is selected at last.Aiming at the requirement of removing the blank ribs of a 1550mm diameter SiC mirror,a new robot soft belt grinding system is built.The stress of the mirror blank in processing is analyzed by using the finite element method,and the removal of the ribs of SiC mirror is completed.The residual height of ribs are between 0.5~1mm.After the polishing and coating process,the surface RMS of the mirror is 0.0157λ(λ=632.8nm),which is measured by the interferometer.The mirror has good performance in orbit,which is launched in 2020.