使用优化的固着磨料磨盘全口径加工碳化硅反射镜

为提高碳化硅非球面反射镜的加工质量,对加工中涉及的固着磨料工艺去除函数进行了研究。在早期的实验中测试了圆形丸片的去除函数,引入填充因子的概念来评价实验所获得的去除函数,定量获得了丸片结构与填充因子之间的关系。为了提高填充因子和磨盘的加工特性,根据圆形丸片的实验结果优化了磨头的结构并基于Matlab软件模拟了新型磨头的去除函数。在全口径范围考察了磨头工作的稳定性,并在相同加工参数条件下完成了固着磨料和散粒磨料的加工实验。为了对理论模拟和实验结果进行比较,引入结构相似度指数的概念来评价全口径反射镜去除量模拟结果与实验结果之间的相似程度。结果显示,实验得到的结构相似度指数达到了0.425 7,证明优化后的固着磨料磨头在大口径碳化硅反射镜加工方面极有应用前景。

Fabrication of SiC mirror in full aperture with optimized fixed abrasive polishing pad

To improve the fabricating quality of a SiC aspheric mirror, this paper researched the removal function in fixed abrasive technology involved in the mirror fabrication. The removal function was tested in the earlier round-pellet polishing pad, then a filling factor was introduced to evaluate the removal function obtained from the experiments and the relation between round-pellet pad structure and filling factor was established. To improve the filling factor and the characteristic of polishing pad, the pad structure was optimized according to the experimental results of the round-pellet pad .The removal function of the new polishing pad was simulated by MATLAB. A stability experiment in the full aperture was performed, and the both fixed abrasive and slurry abrasive polishing experiments were conducted under the same fabricating conditions. Finally, the Structural Similarity Index (SSI) was introduced to evaluate the similarity between simulations and experiments for the removal of large aperture mirror, and the best SSI of multi-square-pellet pad is 0.425 7. The comparison results are acceptable and positive, which shows that the optimized fixed abrasive polishing pad is highly promising for fabrication of large aperture SiC mirrors.