粒子流约束冲蚀抛光薄型光学镜机理与技术研究

With greater diameter-thickness ratio, lower stiffness, thin or ultra-thin mirrors were difficult to fabricate individually, because they were fragile under pressure. In this study, we proposed a rheological field constraint fluid erosion polishing technology based on fluid erosion and rheology, with the versatility of abrasive fluid machining and controllability of rheological finishing. It can polish thin mirror flexibly with low stress and at the same time improve the mid-and-high frequency errors of optical surface. In this project, we study the mechanical model of the thin mirror, which was polishing by the fluid erosion firstly. Then, through analysis of effect on material removal of different particles, the removal mechanism of fluid erosion is to be studied and removal model can be established. Next, a principle prototype must be designed and manufactured to constraint abrasive particle using magnetic field or electric field. At last, experimental studies are on schedule for thin mirror with diameter thickness ratio between 100 and 200, and therefore a polishing technique of high-precision and controlling mid-and-high frequency errors can be acquired by optimizing process parameters of particle flow erosion. This project will get a technological breakthrough in fluid erosion polishing technology, and improve computer controlled thin mirror flexible polishing .

薄型超薄型光学镜具有径厚比大、刚度小、易变形等特点，单独难以加工。本项目提出一种基于流体冲蚀和流变学原理的粒子流约束冲蚀抛光技术，集成了流体抛光的柔性和流变抛光的可控性特点，可实现薄型超薄型光学镜的低应力柔性抛光，并对表面中高频误差进行控制。项目将研究薄型镜在粒子流冲蚀作用下的力学模型；通过分析不同粒子对抛光固液界面的作用方式和粒子间模型，研究粒子流冲蚀对表面材料的去除机理，进而建立冲蚀抛光去除模型；设计研制具有粒子约束及控制能力的实验平台，针对径厚比100-200的典型光学超薄镜开展工艺研究，优化粒子流冲蚀抛光工艺参数，寻求中高频误差控制的工艺路线。本研究将在流体冲蚀抛光工艺与方法上取得具有自主知识产权的技术突破和掌握，为丰富计算机控制薄型镜的柔性加工技术提供储备。

项目按照任务书按期完成了预定的研究内容和研究目标。项目主要完成了三方面的研究内容：（1）针对约束粒子进行冲蚀抛光过程的建模研究方面，理论分析了外加磁场作用下粒子受到的剪切屈服应力，揭示了冲蚀模式下材料去除机理，建立了束流冲蚀模式的抛光模型， 并通过有限元对冲蚀抛光过程中流场进行分析，获得了此模式下材料去除函数；（2）针对发生材料去除的固液界面上磨料粒子的微观作用模型进行了理论和实验研究，确定了适用于项目的液体配比，然后建立了固液接触界面上液体各组分微粒与磨料微粒的体心结合模型和微粒间的有效作用力模型，揭示了微观状态下各微粒之间的状态；（3）针对光学表面残差频谱误差特性分析与规律研究方面，在驻留时间求解时引入频谱目标函数进行优化；提出了速度检测和平滑方法以优化机床的速度和加速度超限，提出多区域优化策略和路径非球面优化方法以改善表面残差的频率域。最后项目进行了200mm口径的薄平面进行加工实验，并采用研究的优化策略，光学表面PSD曲线得到全面下降和改善。项目研究的抛光技术目前的去除率和效度虽然仍较低，由于集成了流体抛光的柔性和流变抛光的可控性特点，经过技术积累会形成一种新的低应力抛光方法。项目完成了预期研究成果，在Applied Optics和Journal of Intelligent Material Systems and Structures等SCI刊源期刊发表论文8篇（第一作者5篇），获得授权中国发明专利3项，参加国际学术会议2次；培养研究生2名。