大口径光学元件的机械手抛光

为满足大口径光学元件多模式组合加工技术(MCM)的需要,研制了JP-01型数控抛光机械手。该机械手采用柱坐标结构,ρ-θ极坐标运动方式,ρ、θ两轴联动完成MCM加工所需各种运动。运用齐次坐标变换理论和Preston方程,在分析机械手抛光过程中工件表面上任意一点的相对速度、压强及抛光时间的基础上,建立了机械手抛光的材料去除数学模型,同时求解了JP-01型机械手的位姿转换矩阵。运用所建立的数学模型对MCM加工中修正环带误差和局部误差时单个抛光盘常用运动模式的材料去除特性进行了计算机模拟。应用JP-01型机械手对一口径为240 mm,F数为1.5的球面反射镜进行了确定性抛光实验,最终面形精度达到14.6 nm(RMS)。实验表明,所测得数据与理论分析数据吻合,建立的数学模型能真实反映材料去除分布特性,可以指导抛光实现确定性加工,JP-01型机械手能够提供MCM加工所需运动形式。

Polishing large aperture mirrors by manipulator

To meet the requirement of Multi-mode Combined Manufacturing (MCM) in a large aperture mirror polishing process, a JP-01 NC polishing manipulator was developed. The manipulator adapted cylindrical coordinates with axes of ρ-θ,and the motions of axis ρ and axis θ were linked to realize all trajectories demanded by MCM. Based on the Preston hypothesis, a mathematical model of material removal was established by analysis on the relative velocity, pressure and dwell time at any point of the optical surface. Meanwhile, the position transform matrix of the manipulator was deduced. Furthermore, the model was used to simulate the usual motion modes of a single lap for zonal errors and local errors in the process of MCM and to achieve deterministic processes. A spherical surface with a diameter of 240 mm, and F number of 1.5 was polished by the manipulator and obtained results show that it can offer a surface accuracy of 14.6nm (RMS). The experiments indicate that the theoretical analysis is coincident with observed experiment results.Moreover,the mathematical model can correctly reflect the practical material removal and can conduct deterministic processes. The polishing manipulator provides better motion modes for the MCM in the polishing process.