材料夹杂对滚动轴承精度保持性的影响研究

As the important supporting part of the transmission system, precision of the rolling bearing has significant effects on the performance of equipments. However, the precision retentivity of rolling bearing often becomes degraded during operation, not only due to the wear and deformation of the races/rolling elements and but also due to the quality of bearing materials such as inclusions etc. This project dedicates the study of the precision retentivity of rolling bearing from the viewpoint of material inclusions. The project focuses on the following researches: (1) Modelling the lubricated contact problems with considering the inclusions based on equivalent inclusion method, and developing the fast solving algorithms; (2) Systemically studing the effect of material inclusions on the lubricated contact behaviors of mating pairs; (3) Developing dynamic model of rolling bearing with considering the inertial effect, gyroscopic moment and the friction force between rolling elemments and races etc, which will accurately predict the contact conditions in bearing and its dynamic behaviors; (4) Based on the coupling between the lubricatd contact model of material inclusins and dynamic model of rolling bearing,studying the effect of materail inclusions on the dynamic behaviors of bearing, finally exploring the laws and mechanisms of effect of material inclusions on precision retentivity of rolling bearing. Experimental tests for lubricated contacts of inclusions and dynamic behaviors of bearing will also be conducted to validate the theoretical models and results.The study will provide theoretical support for improving the precision retentivity of rolling bearing, and technical demands for the inclusion of bearing material.

作为传动系统的重要支撑部件，滚动轴承的精度直接影响装备的质量。滚动轴承精度保持性存在退化的问题，一方面源于工作状态下的磨损和变形，另一方面源于轴承材料的质量如均匀性和夹杂等。本项目从轴承材料夹杂角度研究滚动轴承精度保持性退化问题。研究内容包括：（1）基于等效夹杂方法，建立非均匀材料润滑接触模型，发展快速求解算法；（2）探索接触体材料夹杂对润滑接触行为影响的一般规律和机制；（3）建立完备的滚动轴承动力学模型，模型中考虑高速重载等工况下惯性力、陀螺力矩以及接触副润滑摩擦性能对轴承动力学行为的影响，从而准确模拟不同接触副的载荷和速度等工况条件及其动力学行为；（4）耦合夹杂材料润滑接触模型和轴承动力学模型，结合轴承性能实验，揭示材料夹杂对轴承动力学行为的影响，进而揭示材料夹杂影响轴承精度保持性的规律和机制。研究成果将为提高滚动轴承精度保持性提供理论依据，为轴承材料夹杂提出技术指标。

高性能滚动轴承的精度退化直接影响装备的质量，但当前轴承材料对精度保持性的影响尚未得到重视。本项目建立了考虑材料杂质的多因素耦合润滑接触模型、考虑材料杂质的滚动轴承动力学模型，研究和揭示了材料非均质性对滚动轴承润滑接触性能及振动的影响规律和机制。（1）建立了摒弃滚道控制假设的滚动轴承拟动力学模型，进而建立了考虑各元件相互作用和油气环境的滚动轴承动力学模型，揭示了滚动轴承打滑机理，建立了轴承打滑发生条件，提出了轴承滚道沟道曲率半径的优化方案；（2）建立了考虑材料非均匀性、表面粗糙度以及塑性变形等耦合影响的弹塑性接触分析模型，发展了基于共轭梯度法和快速傅里叶变换的高效稳定求解算法，研究了材料杂质、非高斯粗糙表面特征参数、热处理硬化层等对接触性能的影响规律。硬杂质导致接触表面产生凸起，增大局部接触压力，软杂质与之相反，高应力区域硬杂质容易产生应力集中；提出了表面粗糙度影响次表面应力波动的评估公式；热处理硬化层深度应至少大于十倍的Hertz接触半径，硬度沿深度接近线性分布。（3）建立了考虑了材料杂质、供油条件、表面粗糙度以及塑性变形等多因素耦合润滑接触分析模型。计算表明：与表面粗糙度相比，杂质对接触压力及油膜厚度的影响较小；对于表层下应力，粗糙度的影响基本局限于表面附近，而杂质的影响局限于杂质内部及其附近区域；油气条件下微油滴的大小和位置对润滑性能有显著影响。（4）建立了考虑轴承材料杂质影响的滚动轴承动力学模型，系统地研究了套圈内部杂质对轴承振动的影响。不同尺寸、深度、形状、数量以及分布的杂质对轴承振动特性的影响研究表明：内圈杂质使系统周期运动变为多周期运动甚至混沌运动，系统出现更多低幅边频振动，系统运动行为更加复杂；外圈杂质对系统运动影响较小；不同尺寸及深度的杂质对轴承系统振动影响差异明显，较大较浅的杂质导致系统振动加剧，而杂质的形状及数量对系统振动的影响较小。杂质至少位于表面下2倍Hertz接触半径。