【作者】 王凯；

【导师】 剡昌锋；

【作者基本信息】 兰州理工大学 ， 机械设计及理论， 2019， 硕士

【摘要】 滚动轴承是各类旋转机械中极其重要的起传递运动和承受负载作用的基础元件,其工作性能会影响整机的运行效率,甚至造成灾难性的损失。轴承内部复合故障、滚动体滑动、轴和轴承座与轴承之间的耦合激励、时变位移激励等因素的影响,以及滚动轴承在实际运行中经常处于变速和变载等条件下,直接影响了对轴承振动激励机理和响应特征的认知水平;初期局部缺陷故障的形态和长度等形貌特性与轴承振动冲击响应之间的关联分析并不透彻,这在某种程度上影响了机械系统早期故障判断的可靠性。因此,为了更加准确地监测轴承的健康状态,降低因轴承突发故障而导致的损失和伤亡,开展滚动轴承动力学行为实验和理论研究,具有重大的现实意义。本文以深沟球轴承为例,模拟了滚动体的接触和运动。基于Hertz接触理论,对深沟球轴承开展了动力学行为研究,探究了轴承各组件间的非线性接触机理,分析了轴承表面单、多点缺陷所诱发的激励。论文主要开展了以下研究工作:(1)考虑滚动体经过轴承故障区域时接触和运动的复杂性,对轴和轴承座与深沟球轴承之间的接触进行了模型简化,对滚动体经过轴承故障区域进行了全过程分析,用时变位移和时变刚度来描述滚动体的运动状态,建立了时变位移激励、时变刚度激励和局部缺陷尺寸的数学关系,探究了缺陷诱发的位移激励和力激励的耦合关系。(2)构建了4自由度深沟球轴承单、多点故障动力学复合模型,验证了所建动力学模型的可靠性。分析了基于复合故障、轴和轴承座与轴承之间的激励、时变位移激励、时变刚度激励和滚动体滑动等诱发的轴承振动动力学特性。(3)分析了轴承内圈有单故障、外圈有单故障和轴承内、外圈同时有单故障即多点故障之间振动响应的关系。研究发现:多点故障的振动特性是由内、外圈单故障的振动响应耦合作用的结果。(4)探究了轴承表面局部缺陷的激励机理,揭示了在一定范围内缺陷尺寸、转速和载荷对深沟球轴承振动特性的影响规律。研究结果表明:缺陷尺寸增大、转速增高和载荷增强均会使复合故障轴承的振动幅值增大,影响其运行状态,进而加速轴承的失效,降低轴承的使用寿命。更多还原

【Abstract】 Rolling bearing is a very important basic element in all kinds of mechanical equipment,which can transmit motion and bearing load.The rolling bearing’s working performance will affect the efficiency of the whole machine and even cause catastrophic loss.In order to diagnose and identify the early faults of rolling bearings,it is necessary to solve the basic scientific problem of vibration mechanism and vibration response characteristics of the bearings.However,internal composite rolling bearing faults,sliding roller,shaft and bearing and the bearing coupling between motivation,time-varying displacement excitation,the influence of such factors as well as the actual operation of the rolling bearing in frequently at variable speed and variable load conditions,have a direct and great impact on the response characteristics of bearing vibration excitation mechanism and the acknowledge level.Thus,it makes the real-time performance of the rolling bearing modeling and simulation very difficult.The correlation analysis between the shape and length of the initial local defect fault and the bearing vibration impact response is not thorough,which affects the accuracy and reliability of the early fault judgment of the mechanical system to some extent.Therefore,it is of great practical significance to carry out dynamic behavior experiments and theoretical studies on rolling bearings in order to more accurately monitor the health status of bearings and reduce the loss and casualties caused by sudden failures of bearings.Taking deep groove ball bearing as an example,the contact and motion of rolling body are simulated in this paper.Based on Hertz contact theory,the dynamic behavior of deep groove ball bearings was studied,and the nonlinear contact mechanism between various components of the bearings was explored,and the excitation induced by single or multi-point defects on the bearing surface was analyzed.The paper mainly carried out the following research work:(1)Considering rolling body through contact bearing fault zone and the complexity of the movement,the shaft and bearing and deep groove ball bearings to simplify the model of contact between of rolling element bearing fault zone are analyzed in the whole process,with time-varying displacement and time-varying stiffness to describe the motion state of rolling element,established the time-varying displacement and time-varying stiffness incentives and the mathematical relationship of local defect size,explores the defects induced by the coupling relationship between displacement and force of incentives.(2)The dynamic compound model of single and multi-point fault of 4-DOF deep groove ball bearing was established,and the reliability of the dynamic model was verified.The dynamic characteristics of bearing vibration induced by composite faults,excitation between shaft and bearing,excitation by time-varying displacement,excitation by time-varying stiffness and sliding of rolling body are analyzed.(3)The relationship between single failure of bearing inner ring and single failure of outer ring and single failure of bearing inner ring and outer ring at the same time,that is,multi-point failure,is analyzed.(4)The excitation mechanism of local defects on the bearing surface is investigated,and the influence of the size,speed and load of defects on the vibration characteristics of deep-groove ball bearings is revealed within a certain range.The results show that the increase of the size of the defects,the increase of the speed and the increase of the load will increase the vibration amplitude of the composite fault bearing,affect its running state,and then accelerate the failure of the bearing,reduce the service life of the bearing.更多还原