基于表面特征的滚动轴承振动模型研究

针对轴承制造过程中形成的粗糙度、波纹度、圆度等影响轴承振动的主要因素,利用Lagrange动力学方程建立了具有表面特征的滚动轴承系统的振动模型.该模型可用于分析轴承各部件的表面特征对轴承振动的影响,同时也可用于分析轴承各部件表面存在加工缺陷时系统的振动特性.以轴承内外圈和滚动体表面的波纹度为例,从理论上推导了波纹度阶数与系统振动频率的关系,仿真结果验证了该模型的正确性,所得的结论对轴承振动理论研究和指导低噪声轴承生产有重要意义.     

关于滚动轴承钢球精研的试验研究

本文在试验研究的基础上,对滚动轴承钢球精研后的精度与表面质量问题作了较详细的分析,指出为降低滚动轴承的振动和噪声、提高轴承寿命,必须首先提高滚动体—钢球的精度和表面质量,而采用两次精研工艺是提高钢球的几何精度和降低表面波纹度与表面粗糙度、减少表面划伤的重要的工艺措施。文中列入了测试数据,并对钢球表面波纹度的产生机理与影响因素进行了论述和分析,为降低表面波纹度,从而为降低轴承振动值获得了良好的效果。     

滚动表面误差激励的球轴承振动分析

本文研究滚动表面误差所产生的球轴承振动特性,提出了用等效误差来描述轴承各零件滚动表面误差的方法,建立了由误差引起的球轴承振动模型,讨论了误差的空间谱与振动频谱之间的关系。采用实验方法测试并确定模型参数。本文的分析方法对指导低噪声轴承设计具有一定的理论意义,还可进一步推广应用于滚动轴承的状态监测领域。     

小波分析在滚动轴承故障诊断中的应用研究

为了能有效识别滚动轴承的故障信号,利用滚动轴承滚动体故障模型,构造相应的小波基;研究提升小波的预测器和更新器算法;利用小波基对故障特征信号敏感的特点,对轴承故障信号进行检测和分析.实验和仿真结果表明,利用提升小波对滚动轴承振动信号进行N层分解后,可在细节信号中容易地发现突变信号,再根据模极大值原理,有效地判断轴承故障是否存在;进一步对细节信号作Hilbert包络,检测功率谱中的故障特征频率,可准确判断滚动轴承滚动体是否存在损伤点.     

基于切片双谱分析的滚动轴承故障识别研究

针对滚动轴承故障识别问题，提出基于共振解调理论和高阶谱分析相结合的新方法.讨论了双谱理论和双谱对角切片的特性，分析了故障滚动轴承振动信号的特点.利用希尔伯特（Hilbert）变换构造原始振动信号的解析信号，求取信号的包络，计算包络信号的对角切片双谱，提取由于滚动轴承二次相位耦合产生的非线性特征，得到滚动轴承的故障特征频率，识别滚动轴承的故障模式.试验和理论分析表明，利用该方法可以有效地将正常轴承和内滚道伤轴承、外滚道伤轴承的振动信号进行分离.该方法保留了信号的相位信息, 并且能够有效地抑制噪声，在降维的同时简化了算法.     

表面波纹度对球轴承振动影响的模拟分析

本文采用计算机模拟的方法，分析了球轴承各部件接触表面的波纹度对轴承系统振动的影响，所得结论对于理论研究和实际生产都具有重要意义。     

水润滑橡胶轴承动态刚度和阻尼测试方法研究

针对水润滑橡胶轴承动态刚度和阻尼测试过程中信号混杂等问题,采用了频谱分析法来测定其动力参数,从而有效避免来自外部环境中的信号干扰,使得试验结果更加准确、可靠。试验采用两次激振法对正置结构的水润滑橡胶轴承试验台进行两次不同频率激振,与以往的激振输入输出不同,该测试方法的输入量为位移激振,输出量为力,然后通过频谱分析法,计算出水润滑橡胶轴承的动力特性。最后,利用该方法研究了载荷和转速对水润滑橡胶轴承动力特性的影响。研究表明该方法能有效避免旋转轴涡动产生的径向不平衡力所造成的激振力难以准确控制等问题,提高了测试精度和准确度,为水润滑橡胶轴承动态刚度和阻尼测试提供了新手段。     

基于振动响应机理的轴承故障定量诊断及量化分析

为了解决轴承损伤尺寸难以诊断的问题,建立滚动轴承非线性振动的动力学模型,并通过解析法求解轴承4种不同大小的故障振动信号响应,根据故障轴承响应信号的双冲击时间间隔对轴承故障进行定量分析,分析结果表明了该定量分析方法的准确性.进而对多组不同故障大小的轴承数据进行统计学分析,建立了轴承外圈损伤程度区间.滚动轴承外圈实验结果验证了提出的基于故障机理的轴承故障定量诊断方法的有效性.     

基于ADAMS的滚动轴承参数化建模与动力学仿真

为了更加精确地进行轴承动力学设计,优化高速轴承的动力学特性,本文采用虚拟样机分析软件对滚动轴承进行参数化建模,给出滚动轴承参数化过程,同时建立了深沟球轴承动力学参数化模型并进行仿真分析,仿真结果表明,当对滚动轴承施加一定重载荷时,滚动体因受迫速度增大一些,滚动体与内外圈及保持架的接触力也会增大,但由于滚动体的直径减小,施加的载荷不足以使轴承的变形达到增加接触力效果,所以在对轴承模型施加1000N载荷后,参数化模型分析结果与实际要求相符合。提高了建模效率,方便了用户不用考虑模型内部之间的关联变动对模型进行快捷修改。该方法对研究滚动轴承动力学特性具有重要作用。     

磁悬浮轴承磨床电主轴中拍振现象的分析

为减小拍振现象对高速精密磨床电主轴加工精度的影响,利用磁悬浮轴承自身的传感器及数字信号处理部件,在不外加其他设备的情况下对电主轴中的拍振进行了观察实测。通过时域、频域分析以及小波变换,提取振动信号的特征,经分析发现拍振现象是由转子机械不平衡以及转子动态偏心共同引起的。在磁悬浮轴承电主轴拍振机理的分析基础上,通过磁悬浮轴承系统的主动控制调节主轴动态特性,有针对性地对拍振现象进行抑制,可以有效改善高速精密磨床磁悬浮电主轴系统的稳定性和精密度。     

Vibration analysis of a single row angular contact ball bearing with the coupling errors including the surface roundness and waviness

Roundness and surface waviness are main manufacturing errors on the components of single row angular contact ball bearings(ACBBs). An analytical study for vibrations of the ACBBs with coupling errors including the roundness and waviness can be useful for the vibration control of the rotating machinery. However, most previous works only focused on the single error modelling method. In this paper, an improved time dependent displacement excitation(TDDE) model is proposed to consider the coupling errors including the roundness and waviness on the inner and outer races of an ACBB. The TDDE model for the roundness and waviness is established by using a combination of several sinusoidal functions. A dynamic model in the previous study is improved to consider the influences of coupling errors including the roundness and waviness. The Hertzian contact theory and Dowson's method are adopted to calculate the bearing contact stiffness. The time-and frequency-domain vibrations for the experimental and simulation results are compared to show some model validation. The influences of roundness orders and waviness amplitudes on the vibrations of the ACBB are analysed. The obtained results show that the coupling errors including the roundness and waviness have some influence on the time-domain impulse waveform and frequency-domain spectrum characteristics of the bearing accelerations. The differences of the vibrations between the coupling errors and sing error are from 4% to 42%. This paper can provide a useful guidance for the accurate diagnosis of surface imperfections in the ACBBs.     

A comparative study of surface waviness models for predicting vibrations of a ball bearing

Surface waviness models utilized to describe the excitation events in the ball bearings(BABs) play an important role in predicting the vibrations of the ball bearing systems. This work proposes a comparative study on the most relevant existing surface waviness models. One model is named as time-varying displacement(TVD) model, which can only describe the time-varying displacement excitation(TDIE). Another model is named as TVDS model, which can describe the TDIE and time-varying contact stiffness coefficient excitation(TCSE). The influences of the wave number, maximum amplitude, nonuniform distribution on the contact stiffness coefficients are studied, as well as vibrations of the BAB. The comparative results demonstrate that the time-varying displacement and stiffness(TVDS) model can provide a more accurate impulses caused by the uniform and nonuniform surface waviness on the races of the BABs. It also seems that the surface waviness distribution has a significantly influence on vibrations of the BABs.     

Dynamic analysis of traction motor in a locomotive considering surface waviness on races of a motor bearing

The traction motor is the power source of the locomotive. If the surface waviness occurs on the races of the motor bearing, it will cause abnormal vibration and noise, accelerate fatigue and wear, and seriously affect the stability and safety of the traction power transmission. In this paper, an excitation model coupling the time-varying displacement and contact stiffness excitations is adopted to investigate the effect of the surface waviness of the motor bearing on the traction motor under the excitation from the locomotive-track coupled system. The detailed mechanical power transmission path and the internal/external excitations (e.g., wheel–rail interaction, gear mesh, and internal interactions of the rolling bearing) of the locomotive are comprehensively considered to provide accurate dynamic loads for the traction motor. Effects of the wavenumber and amplitude of the surface waviness on the traction motor and its neighbor components of the locomotive are investigated. The results indicate that controlling the amplitude of the waviness and avoiding the wavenumber being an integer multiple of the number of the rollers are helpful for reducing the abnormal vibration and noise of the traction motor.

     

机床工作台上刀具工作点的轴向振动分析

在考虑轴承的支承作用、工作台与丝杠以及工作台与导轨的接触变形的情况下,全面分析了预拉伸丝杠的横向振动、纵向振动和扭转振动以及工作台的振动,利用拉格朗日方程建立了滚珠丝杠传动系统的动力学方程,用振型叠加原理和隆格-库塔法进行求解,按正交试验计算分析了系统参效对工作台上刀具工作点轴向振动的影响,优化组合了系统参数,为滚珠丝杠传动系统参数的选择以及装配调整提供了理论依据,为提高机床轴向定位精度奠定了基础。     

深沟球轴承复合故障动力学特征

为提高状态监测水平,诊断和识别轴承的早期故障,降低因轴承故障导致的损失, 针对径向载荷作用下复合故障激励的滚动轴承振动机理的复杂性问题,基于Hertz接触理论,考虑复合故障、轴和轴承座与轴承之间的耦合激励、时变位移激励和滚动体滑动等因素,提出了4自由度复合故障深沟球轴承动力学模型. 模型描述了滚动体在滚道表面上的接触和运动,探究了轴承表面复合故障激励机理,分析了3种工况条件下滚动轴承复合故障对系统动力学振动响应的影响,为轴承状态监测和诊断提供了理论依据. 实验和模拟研究结果表明,复合故障的振动响应是由内、外圈单故障的振动响应耦合作用的结果,在频谱图中可以明显地分辨出内、外圈故障特征频率及倍频成分,与单故障相比较,其对应的幅值增大. 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.     

早期故障信号基于调制随机共振的核主元检测

针对淹没在强噪声中具有高频多周期成分的早期故障信号,提出了并联调制随机共振与核主元分析系统.将信号的特征频率通过调制共振系统进行增强,并将功率谱组成多元统计向量,通过非线性映射,在高维空间进行特征提取,利用T2统计量和F分布的控制限进行检测.利用仿真的轴承转子振动信号与滚动轴承冲击信号进行了验证,实验表明系统能够及时地对早期故障进行预警.     

A bearing fault diagnosis method based on sparse decomposition theory

The bearing fault information is often interfered or lost in the background noise after the vibration signal being transferred complicatedly, which will make it very difficult to extract fault features from the vibration signals. To avoid the problem in choosing and extracting the fault features in bearing fault diagnosing, a novelty fault diagnosis method based on sparse decomposition theory is proposed. Certain over-complete dictionaries are obtained by training, on which the bearing vibration signals corresponded to different states can be decomposed sparsely. The fault detection and state identification can be achieved based on the fact that the sparse representation errors of the signal on different dictionaries are different. The effects of the representation error threshold and the number of dictionary atoms used in signal decomposition to the fault diagnosis are analyzed. The effectiveness of the proposed method is validated with experimental bearing vibration signals.     

润滑油黏度对高速球轴承性能及损伤的影响

为探究高速工况下润滑油黏度对轴承润滑状态及性能的影响,试验研究了Si_3N_4陶瓷和GCr15轴承钢材质的7014C型角接触球轴承在不同润滑油黏度条件下的温升和振动特性.结果表明,轴承温升及振动随润滑油黏度的增大呈现出先下降后上升的趋势,影响程度随转速的增大而增大.同时,陶瓷轴承较钢制轴承在不同润滑油黏度条件下均表现出更优越的性能.将试验结果与轴承润滑状态分析结合,讨论了润滑油黏度、润滑状态、轴承性能三者的关系,为高速角接触球轴承适用润滑油黏度的选择提供了重要依据.此外,本文还对不同润滑条件下的轴承滚动面损伤进行了分析.结果显示,全膜弹流润滑条件下,陶瓷轴承与钢制轴承滚动面损伤较小且差异不明显.部分膜弹流润滑条件下的轴承滚动面损伤严重,表面出现大量凸峰和凹谷,轴承滚动体及外滚道表面损伤较内滚道严重,钢制滚动体的表面划痕较陶瓷滚动体密且深.