Experimental Study On Computer Controlled Grinding And Polishing Sic Mirror With Fixed Abrasive

As fast development of space science and technology, space satellite camera is too important to be substituted in national defence and security, its strategic function is obvious day by day. The performance of space satellite camera is decided by the key component of space satellite camera----optical mirror directly. Because of its special circumstance in space, highly restrict has been demanded on the material performance of optical mirror, and SiC material is able to meet most demands in space application, so it is popular in space satellite.Because of high Young's modules and high hardness of SiC material, it is very tough to grind. If the traditional slurry is used to grind and polish SiC material , the results are low machining efficiency, severe waste of slurry, uncontrolled machining quality which cause long machining time, high cost. Fixed abrasive technology not only is able to overcome the disadvantages of traditional slurry mentioned above but also bring the advantages of high speed machining equipment into play and polish the SiC mirror into good surface roughness quickly. So mainly the paper applies the fixed abrasive technology into grinding and polishing SiC mirror, and research the grinding mechanism of fixed abrasive technology, optimize the parameters in the technology, make quantitative analysis on the machining quality of fixed abrasive technology.The research object of paper is grinding and polishing SiC mirror with diamond pellets, beginning from several machining performances of pellet and mirror surface quality and make a series of simulation and experiment researches.(1) Micro removal theory model research of grinding and polishing SiC mirror with fixed abrasive beginning from micro course of grinding and polishing SiC mirror with fixed abrasive, the elasticity force is introduced to judge the contact type between diamond and SiC, quantitatively describe the relationship between SiC material removal rate and several machining parameters. And according to the simulation results, a series of validating experiments have been carried out. Compared theoretical results with experimental data, comparison of results have been analyzed.(2) Removal stability research of fixed abrasive technologyBased on the basic experiments, SiC material removal stability of pellets has been analyzed under different conditions, also the machining results of different pellet type have been compared.(3) Surface quality assess researchThe space frequency of surface polished by pellets has been divided, research point has been set on middle frequency and high frequency. The PSD has been applied to analyse polished surface in middle frequency; the differences between simulation and experimental results have been analyzed, also fractal theory and ANN are introduced to analyse influence of fixed abrasive in high frequency.(4) Study on removal function of SiC mirror polished by fixed abrasiveThe removal function peak theory model has been deduced from theory of chapter two. Combined of wang quandou's theoretical work, removal function model of single pellet has been fixed on. Further more, multi-pellets compound polisher removal function model has been deduced from single pellet model. The multi-pellet model has been analyzed and optimized , the improved measures of technology have been obtained through the analyzed and optimized model.(5) Fixed abrasive technology polishing SiC mirror in full apertureFlat SiC mirror has been polished by improved fixed abrasive technology in full aperture. The stability of improved compound polisher has been checked through a long time polishing course. Final surface removal distributing data have been analyzed under certain machining parameters. The simulation results have been compared to experimental removal distributing data. At last, polishing stability has been compared to traditional slurry transversly.Grinding and polishing SiC mirror with fixed abrasive technology have been researched in detail , especially on removal mechanism, machining stability, polishing surface quality assess ,removal function theory. Fixed abrasive has been improved which established the basis for the engineering.