基于正反问题的机床主轴轴承动态预紧力创成机理与测试方法研究

The preload of bearings is the key factor of spindle performance and life. In working condition, the measuring and testing techniques of spindle bearing preload are one of the difficulties of study at present. Theoretically, the value of preload can be deduced by comparing the axial force-displacement curve of preloaded bearing (measurement) with the axial force-displacement curve of non-preloaded bearing (theory). However, the theoretic curve could not be precisely obtained as theoretic calculations do not consider the influence of the working conditions. This project takes direct-inverse method as breakthrough point and getting the axial force-displacement curve of non-preloaded bearing under working condition as the core. In science, the effect of working condition (magnitude of interference, rotating speed, temperature) on the geometric dimensions and profile of the angular contact rolling bearings would be researched, and the stiffness analysis model of rolling bearing would be established considering the effect of working condition, then the calculation model of matched spindle bearings would be developed to reveal generating mechanism of bearing dynamic preload. In engineering, the simplified computing method of matched bearings stiffness, the generating technology of theoretic axial force-displacement curve based on testing data and SVM theory and the displacement measuring equipment based on electromagnetic loading and new measuring principle would be researched. This project has scientific significance and obvious value on engineering application of the spindle assembly, running, and maintenance.

轴承预紧力是影响主轴性能及寿命的关键，主轴运行状态下轴承动态预紧力测试技术也是当前研究的难点问题之一。理论上，通过比较预紧轴承轴向力-位移曲线（实测）和零预紧轴承轴向力-位移曲线（理论），可推知预紧力大小。但目前理论计算未全面考虑工况的影响，无法准确得到理论曲线。本项目以正（理论曲线）反（实测曲线）问题相结合的思想为切入点，以解决实际工况条件下零预紧轴承的轴向力-位移曲线（刚度曲线）为核心，在科学问题层面，研究工况因素（过盈量、转速、温度）对角接触球轴承几何尺寸与轮廓的影响，建立综合考虑工况因素的轴承刚度分析模型，进而发展主轴组配轴承的刚度计算模型，揭示轴承动态预紧力的创成机理；从工程技术层面，研究组配轴承刚度简化计算方法、基于实测数据与支持向量机技术的理论轴向力-位移曲线生成技术、基于电磁加载及新型测量原理的位移测试装置。研究具有科学意义，对主轴装配、运行及维护具有明显的工程应用价值。

角接触球轴承预紧力是影响主轴性能及寿命的关键，而运行状态下动态预紧力测试是高性能主轴研发急需解决的关键问题之一。本基金利用理论建模（正问题分析方法）与实验测试（反问题分析方法）相结合的方法，对主轴轴承动态预紧力测试原理与技术展开研究，旨在突破传统的机床主轴轴承预紧力静态测试模式、解决实际工况条件下轴承动态预紧力测试难题。. 首先针对预紧力尚缺乏有效准确测试措施的问题，引入参数识别技术，提出了基于理想曲线与实测曲线相对比的动态预紧力测试新技术。其次针对理论力-位移曲线计算问题，提出了装配过盈、温度、转速、轴承配置形式等对轴向力-位移关系（刚度）影响的分析模型。针对轴承组配形式多样化问题，建立了考虑工况因素的组配轴承刚度综合分析模型，提出了显式与隐式结合的求解方法，揭示了实际工况因素对主轴轴承刚度的影响规律，结果显示转速、轴承配置等因素对轴承刚度影响较为明显。基于该模型，研究了主轴在轴向拉、压力作用下的接触角变化特点及力-位移曲线变化规律，发展了更精确的理论轴向力-位移曲线生成方法。然后，针对轴向力-位移曲线测量问题，在对比分析非接触与机械加载装置优缺点的基础上，研发了三代轴向载荷加载装置，先后解决了加载稳定性、测试准确性及自动测量等关键问题。同时探索了轴向位移的径向测量方法。基于前述技术，利用MATLAB与LABVIEW软件混合编程技术，开发了相应的测试软件系统。最后搭建了定位、定压预紧主轴预紧力测试实验台，实际验证了动态预紧力测试新方法的可行性和准确性，并在多家企业开展了预紧力测试机构的应用验证工作，显示测试结果稳定准确，表明了所研发系统具有良好的应用价值。. 本项目所形成的主轴刚度分析模型及方法为实际工况条件下主轴性能分析提供了有意义的参考，所开发的主轴轴承动态预紧力测试系统很好的解决了行业对预紧力无法测试的难题，为主轴生产质量控制、主轴维修等提供了有效的技术手段；同时为预紧力相关实验研究提供了有效的测量手段。