微结构表面三维椭圆振动超精密抛光新方法的研究

The vibration ultra-precision polishing has very attractive application prospect because high quality surface can be obtained for hard and brittle difficult to machine material by using this method. However, the existing two dimensional elliptical vibration ultra-precision polishing have many difficulties for rather improving surface quality. Exploring better vibration type and revealing action mechanism is an urgent key question now. A new three dimensional elliptical vibration ultra-precision polishing method of micro structured surface is put forward in this project. Modern tribology theory, discrete element method, molecular dynamics method are used in this research. Firstly, when polishing tool vibrates along three dimensional ellipse trajectory, polishing trajectory and pressure are analyzed from kinematics, solid-liquid two phase flow are simulated using discrete element method, the effects of vibration parameters on abrasive particle motion and workpiece surface quality are investigated, which will reveal the effect mechanism of three dimensional elliptical vibration on micro structured surface. The material removal model concluding vibration parameters and polishing parameters is established using multi-scale method and with the help of kinds of measure instruments, at the same time micro optical lens array mold surface is machined using the three dimensional elliptical vibration ultra-precision polishing method. The effects of different parameters on surface topography feature and surface quality are analyzed, which reveal material removal mechanism in three dimensional vibrations ultra-precision polishing. The research results are of great scientific importance, which can provide theoretical basis for realizing manufacture technology of free-form surface characterized by high accuracy.

振动超精密抛光对硬脆难加工材料微结构表面高质量的获得具有十分诱人的应用前景，但现有二维椭圆振动超精密抛光对微结构表面几何完整性的进一步提高还存在不足，迫切需要探索更好的振动方式，并揭示其作用机理，为此，本项目创新性地提出一种微结构表面三维椭圆振动超精密抛光方法。基于现代摩擦学等理论，运用有限元和分子动力学等仿真技术，首先从运动学角度分析三维椭圆振动的抛光轨迹和接触区应力分布，对固液两相流进行离散元模拟，研究磨粒的分布状态与运动特性，探索振动参数对磨粒切削行为和加工表面形貌的影响规律，揭示三维椭圆振动对微结构表面的作用机理；采用多尺度研究方法，借助显微表征手段，建立包含振动参数和抛光参数的材料去除模型，进行微透镜阵列结构表面三维椭圆振动超精密抛光实验，分析参数变化对表面形貌特征和几何完整性的影响规律，揭示材料去除机理。研究成果为掌握高精度的微结构表面制造技术提供理论基础，具有重要的科学意义。

运用磨粒切削和概率论理论，建立了表面粗糙度预测模型，通过仿真和实验分析了抛光压强、磨料粒度等对表面粗糙度和表面轮廓最大高度的影响规律。建立了包含关键工艺参数（抛光压力、进给速度、工具转速和磨料粒度等）的材料去除轮廓模型，分析了工艺参数对材料去除轮廓的影响规律。采用离散元法建立了抛光工艺模型，研究了振动对磨粒运动速度和非平衡力的影响，发现高频大幅值的振动能够提高加工效率和快速改善表面质量。建立纳米抛光碳化硅的分子动力学模型，研究了线性改变抛光压力对材料去除的影响机理。研究了抛物线型柔性铰链的弯曲刚度和拉伸刚度模型，获得了不同尺寸参数对应的解析解；分析了铰链刚度对结构参数的依赖程度，发现了其具有明显的尺寸效应。设计了一种压电驱动柔性铰链机构的三维运动平台，采用柔度矩阵法和有限元法对机构进行了静力学和动力学分析；对三维运动装置进行响应性能和各向解耦性能测试分析；通过实验获得了输出末端的空间运动轨迹。根据振动叠加原理，设计了一种三维超声振动变幅杆，应用有限元法对其进行了模态分析、瞬时动力学分析和振动轨迹分析；研制了三维超声振动加工装置并进行性能测试。根据三维振动抛光微结构自由曲面的运动学关系，分别采用切平面法和平行平面法对三维振动轨迹的理论生成方法进行了研究，具体给出了不同振动参数下采用平行平面法抛光谐波网格表面的振动轨迹，通过对铣削获得的结构型表面进行抛光实验以验证该算法的有效性。采用四种抛光工具系统深入研究了振动幅值变化对抛光力的影响规律，发现其变化范围与抛光力初始值有密切关系。提出了采用三维振动抛光创成结构型表面的方法，运用压电驱动柔性铰链的三维振动装置进行了抛光实验验证。