基于全局尺寸的超精密气静压轴径向气膜厚度设计与控制技术研究

Ultra precision aerostatic bearing spindle is one of the key parts of ultra precision meachine tools and measuring instruments. Owing to that the rotary accuracy and stiffness of the aerostatic bearing spindle is higher and higher,the conventional tolerance design method and manufacturing process are not suitable for the need of design and batch manufacturing of ultra aerostatic bearing spindles. Based on simulation and experimental methods, through the global size feature extraction and evaluation of the ultra aerostatic radial bearing's hole and its suitable shaft, some issues on optimization of the global size feature extraction paths of hole and shaft and their characteristic parameters, and the influence of the global sizes on the performances of ultra precision aerostatic bearing spindle, and so on, will be studied. The optimal extraction path and its characteristic parameters of the global size will be gained, and the evaluation model of the effects of global sizes on the performaces and the optimal tolerance design model of ultra precision aerostatic bearing spindle may be built. According to the requirement of the different gas file thicknesses, based on the optimal telerance design model of global sizes, some samples of ultra aerostatic radial bearing are designed and manufactured. According to the tested results of the bearings' performances on the test-bed of the aerostatic bearing spindle's performances, the models of the performances' evaluation and the optimal global size tolerance design of ultra precision aerostatic bearing spindle may be modified. Through the grouped assembly process, the uniformity control technique of the radial gas film thickness of ultra precision aerostatic bearing spindle will be researched. The project may has important scientific significance and practical value for improving the design and batch manufacturing capability of ultra aerostatic bearing spindles.

超精密气静压轴是超精密机床与测量仪器的关键部件之一，由于对其回转精度和刚度要求越来越高，传统的公差设计和工艺已不能适应超精密气静压轴设计和批量制造的需要。本项目采用仿真和试验方法，通过对超精密气静压径向轴承和与其相配轴的全局尺寸要素的提取和评定，研究孔、轴全局尺寸要素提取路径及其特征参数的优化、全局尺寸对超精密气静压轴性能的影响等问题，获得全局尺寸要素提取优化的路径及其特征参数，建立基于全局尺寸的超精密气静压轴性能影响评价模型和全局尺寸公差优化设计模型；按不同气膜厚度要求，采用全局尺寸公差优化设计模型，对超精密气静压径向轴承进行设计制造，在气静压轴性能试验台上进行试验，根据试验结果，修正超精密气静压轴性能评价和全局尺寸公差优化设计等模型；采用组合装配工艺，研究批量生产中超精密气静压轴径向气膜厚度一致性控制技术。本项目对提高超精密气静压轴的设计与批量制造能力具有重要的科学研究意义与实用价值。

针对超精密气静压轴批量制造的需要，对气静压轴径向气膜厚度设计与控制技术进行了较系统的研究。主要研究内容如下：.1）系统地研究了轴线的偏心和倾斜对全局尺寸测量结果的影响，建立了相应的误差补偿模型和适应六种轮廓提取方案的圆柱体全局尺寸的评定模型，对圆柱体直径与形位误差测量仪进行了改造；建立了圆柱体全局尺寸的测量不确定度评定模型；提出了基于伪全局尺寸（伪计算尺寸）和神经网络回归评定全局尺寸（计算尺寸）的方法。.2）基于精密圆柱零件车（磨）削加工机床的结构，建立了圆柱体要素提取模型；提出了圆柱体要素仿真特征参数的确定方法，特征参数值对圆柱体的全局尺寸、形状误差的评定影响较大，采样点数对全局尺寸影响不大，但对圆柱度误差影响较大。.3）对具有不同几何误差的气体静压主轴的承载力与刚度值和基于全局尺寸获得的气体静压主轴的刚度和回转精度进行了仿真分析，对于最小二乘直径、最小外接直径和最大内切直径，基于最小二乘直径得到的气体静压主轴的刚度与回转精度较适用于气体静压主轴性能的评定。.4）给出了基于尺寸链的气体静压径向轴系公差设计流程；分别研究了基于皮肤模型配合和全局尺寸配合的气体静压轴承的性能；采用遗传算法，研究了基于成本—公差函数模型的轴承和转子的几何公差分配方法；在模块化主轴性能试验台上对小孔节流气体静压轴承的承载力进行了实验，并与基于全局尺寸和皮肤模型获得的气静压轴承的性能进行了对比。.5）提出了基于轮廓测量的非理想圆柱表面建模方法；研究了气静压轴径向气膜建模与控制问题；对气静压轴的轴承和转子进行了分组装配、性能仿真和实验，研究结果表明，用最小二乘直径评定气膜的厚度较适用于气体静压主轴综合性能控制的需要，但轴承孔和转子的几何误差对气静压轴的综合性能影响较大；研制了高速精密气静压转台和模块化主轴综合性能试验台。.本项目成果为ISO 14405-1的贯彻实施和超精密气静压轴的设计与批量制造能力的提升奠定了良好的技术基础。