精密球轴承不可重复跳动影响主轴动特性的预测

将精密球轴承不可重复跳动(NRRO)的研究引入到主轴系统分析中,阐述了主轴系统NRRO的概念。应用滚动轴承几何学、弹性力学和滚道控制论,给出了高速角接触球轴承由内圈、外圈、钢球几何误差与球数变化所引起的NRRO的数值计算公式。为了在设计阶段揭示NRRO对精密主轴的影响规律,建立了考虑NRRO效应的主轴系统动态预估模型。计算实例和理论分析表明:球轴承中当一个钢球误差较大时,NRRO值随着球数增加而降低;内、外圈的几何误差对系统NRRO的影响较小;钢球本身的表面几何误差对系统NRRO的影响比较显著。针对现有轴系设计方法的不足之处,在预估模型基础上,提出了基于响应面的主轴系统NRRO抑制设计方法,为精密轴承系统研究提供了一定的理论依据和参考。

基于有限单元法的连续挤压机主轴系统结构强度分析

连续挤压设备主轴系统各零件的接触计算是目前尚未解决的难题,导致各零件准确的强度分析难以实现。分别通过Pro/E和Hyper-Mesh建立了主轴系统的实体模型和有限元模型,最后通过ANSYS成功地模拟了主轴系统的工作过程,得到了主轴系统中各接触对的接触性能和零件的应力分布。通过对主轴系统进行接触分析求出预紧力下接触区域内的接触压力和接触摩擦力的分布规律,并研究得出接触压力与接触摩擦力之间的数值关系,为合理施加预紧力提供了参考。在此基础上,计算分析了主轴系统中轴套、主轴芯轴和挤压轮的应力,为主轴系统结构强度优化设计提供了基础。

Study of the thermal influence on the dynamic characteristics of the motorized spindle system

The severe internal heat generation of the motorized spindle system causes uneven temperature dis- tribution, and will affect the vibration characteristics of the system. Based on the thermal analysis about the motorized spindle by finite element method （FEM）, the thermal deformations of the spindle system are calculated by the thermal structure coupling simulation, and the thermal deformations of the rotor and the bearing units are extracted to analyze the bearing stiffness changes so that the modal characteristics of the rotor can be simulated in different thermal state conditions. And then the rotor thermal deformation experiment and the modal experiment of spindle by exciting with hammer are performed. The result shows that the thermal state of the motorized spindle system has a significant influence on the natural frequency of the rotor, which can be carefully treated when a spindle system is designed.