四列角接触球轴承振动特性研究

基于滚动轴承动力学理论,建立了四列角接触球轴承的动力学分析模型,并以某型号四列角接触球轴承为例,对不同结构参数与工况参数下的轴承振动特性进行理论分析。结果表明:对于四列角接触球轴承,根据使用工况选择大、小球列不同的内、外沟曲率半径系数与初始接触角更有利于轴承的减振降噪;对轴承施加一定的轴向预紧量可有效减小轴承振动;存在较为合理的轴向载荷、倾覆力矩及内圈转速范围使四列角接触球轴承在使用时的振动较小。     

The influence of surface roughness on the starved lubrication of ball bearings

Abstract

A theoretical analysis is made for starved lubrication of a rigid point contact under the influence of surface roughness. The results show that both the directional property and the standard deviation of the combined surface roughness can affect the load carrying capacity of the lubricant film as well as the friction on the solid surfaces. The combined effects of speed ratio of the contiguous surfaces and the roughness on starved lubrication are also obtained. The results show that the effects of surface roughness may improve the starvation a little, but that they are not remarkable. A regression equation is found for determining the critically starved lubricant inlet level. Such an inlet level can indicate the minimum limit of lubricant supplied quantity, and, beyond this limit, the load carrying capacity of the lubricant film will decrease sharply. In addition, experiments have been carried out to observe the starved lubrication of a ball rolling on a flat glass disc. It is shown that higher surface speeds may make the starved condition much worse.     

Calculation of hydrostatic plastic medium-lubricated thrust bearings

A procedure is described to calculate operation parameters of hydrostatic plastic medium-lubricated thrust bearings. A comparison is made of predicted and experimental characteristics of bearing operation for plastic and Newtonian lubrication media.Volgograd Polytechnic Institute, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 63, No. 3, pp. 364–367, September, 1992.     

Investigation of tribological and mechanical properties of metal bearings

Copper, aluminum and tin-lead based alloys are widely used as journal bearing materials in tribological applications. Bronze and brass are widely used as journal bearing materials for copper based alloys. Zamacs find applications as journal bearing materials for zinc based alloys, while duralumines are chosen as journal bearing materials for aluminum based alloys. In addition, white metals are widely used as journal bearing materials for tin-lead based alloys. These alloys ensure properties expected from journal bearings. In this study, tribological and mechanical properties of these journal bearings manufactured by metals were investigated. SAE 1050 steel shaft was used as counter abrader. Experiments were carried out in every 30 min for a total of 150 min by using radial journal bearing wear test rig.     

球轴承非线性振动解析

为了便于对球轴承的振动进行定量分析,本文建立了2自由度的球轴承非线性振动模型,对2自由度球轴承振动的非线性微分方程组进行了简化求解,得到近似解的表达式,以及基频的表达式,并与实际实验结果进行了比较。比较结果显示,理论分析与实际结果是一致的。     

基于简化Jones-Harris方法的球轴承接触角研究

作为球轴承重要的结构参数之一,接触角对轴承组件的载荷分布、运动关系、润滑、摩擦等都有重要的影响。将求解惯性力所涉及的变量耦合关系进行简化,提出了用于研究球轴承接触角特性的简化Jones-Harris方法(SJHM),通过预先给定内圈偏转角,克服了直接迭代法难以考虑内圈偏转角对接触角影响规律的不足。以b218轴承为对象,验证了SJHM方法的有效性;在此基础上,分析了多种因素对接触角的影响规律。研究结果表明：相比陀螺力矩的影响,离心力对内、外接触角的影响更加显著;接触角对轴承内圈偏转角的变化非常敏感,内圈偏转角会使同一个滚动体的内、外接触角同时增大或减小。     

Inertia effects on thrust bearings with Michell pads running under thermohydrodynamic conditions

This paper presents an analysis of thrust bearings with Michell pads under steady state conditions at the limits of the laminar flow taking the inertia forces in radial and circumferential directions into consideration and assuming that the bearing operates under, THD, thermohydrodynamic boundary conditions. The governing equations of the problem allowing for temperature rise within the oil film as well heat conduction inside the bearing elements are derived. The velocity components including both inertia terms are derived and inserted into the integrated continuity equation to obtain a Reynolds type differential equation. The whole equation system represents a non-linear systen, because the individual variables depend on each other. The equation system is discretized by means of finite difference method and solved simultaneously by means of an iterative scheme to find the characteristic values of the bearing. The analysis shows that the inertia forces have a pronounced effect on the bearing characteristic values.     

Investigation of rolling contact fatigue cracks in ball bearings

Rolling contact fatigue in a ball bearing is studied using the experimental method. Fatigue pits and spallings on the rolling surface are investigated, and the strain-hardening beneath the contact surface is studied using the microhardness profile. Moreover, surface and subsurface crack layouts and the effect of inclusions on crack nucleation are studied by optical and electron microscopy. Additionally, a simulated model is used to study the influences of the crack inclined angle and the inclusion’s hardness on fatigue damage in bearings.     

表面波纹度对滚动轴承-转子系统非线性振动的影响

分析了考虑滚动轴承内外圈波纹度、径向间隙和非线性赫兹力作用下的滚动轴承-转子系统非线性动力学响应。根据不同参数下的分岔图、功率谱图和庞加莱截面图,研究了轴承表面波纹度最大幅值和转速对系统的非线性振动的影响,找到了不同故障类型的特征频率。根据分形理论应用G-P算法计算了相同转速下不同最大幅值时的关联维数。分析结果表明,当系统处于混沌状态时随着波纹度最大幅值的增加,其关联维数也会相应增大。因此关联维数可以应用于轴承故障的特征提取与定量诊断中。     

Measurement and automatic control of radial clearance in instrument ball bearings

Conclusions The SM-214 automatic machine provides precise sorting of instrument single-row ball bearings with respect to the value of their radial clearance with reliability and convenient utillization.Translated from Izmeritel'naya Tekhnika, No. 5, pp. 18–20, May, 1976.     

Hybrid approach for remaining useful life prediction of ball bearings

Remaining useful life (RUL) prediction plays an important role in predictive maintenance systems to support decision‐makers for arranging maintenance tasks and related resources. We propose a hybrid approach that is combined an exponential weighted moving average (EWMA) control chart for anomaly detection and machine learning models such as support vector regression (SVR) and random forest regression (RFR) with differential evolution (DE) algorithm to predict the RULs of ball bearings. Here, DE algorithm is used to find the optimal hyperparameters of SVR model. The datasets of ball bearings from the Prognostics Data Repository of NASA are used to compare the prediction performance of different methods. The degradation behavior of training data from the anomaly time to the end of life is used to transfer learning for the testing data in the SVR and RFR models. The results indicate that the proposed methods outperform the other four existing methods in terms of score. Therefore, the proposed hybrid approach is a reliable tool for the RUL prediction of ball bearings.     

TEM and nanomechanical studies on tribological surface modifications formed on roller bearings under controlled lubrication conditions

The chemical composition and microstructure of reaction layers formed under the presence of lubricants with low wear protection, high wear and fatigue protection, and high wear but low fatigue protection on thrust cylindrical roller bearings made of 100Cr6 steel were analysed by transmission electron microscopy. Thin cross sections prepared by the focused ion beam technique were investigated. The nanomechanical properties of the different tribological layers were analysed by static and dynamic nanoindentation. Our results indicate that wear protection not only relies on the lubricant induced formation of a reaction layer, but also on the properties of the combined system of a reaction layer and an underlying tribomutation layer. The formation and structure of the layer system varies with the chemical nature of the basic oil. Our investigations show that its ability to protect against wear and fatigue strongly depends on the oil viscosity and the additives.     

Experimental study of the impact of grease particle contaminants on wear and fatigue life of ball bearings

Ball bearings’ rating life is reduced when they are installed, operated and maintained under harsh environmental conditions as they suffer from excessive wear due to debris contaminants in the lubricant. This life reduction is taken into account when calculating the modified rating life but the impact of contaminant’s variables such as size, hardness and concentration level are not determined in detail. In this work, greases contaminated with particles of different sizes and hardness (steel and corundum) are tested to shed new light in the way these parameters and wear’s progress are related. A test rig is utilized and the most recent methods on vibration analysis regarding bearings’ condition and estimated residual life are assessed and evaluated. At the end of the tests, optical inspections using a stereoscope verify the vibration analyses results. It can be concluded that wear is more severe when harder particles are used, but regarding their size, it seems that wear progresses in a different manner depending on particle’s hardness and brittleness as soft ductile particles are rolled over and hard brittle particles are crushed down.     

On the energy characteristics of ball lightning

A compilation of 17 observations of ball lightning showing the most energetic effects is presented along with estimates of their energy content. These observations were chosen from several thousand for the much stronger interaction of each ball lightning on its surroundings, and the method of energy estimation outlined. The case is put that some of the observations show a higher energy than self-contained chemical energy could provide. Comments have been added to the paper, arguing that the energy estimations themselves should be consistent with whatever model is used for ball lightning. For example, the presence of reacting nanoparticles releasing chemical energy may bring about the same observed effects with lower estimated energy.     

Dynamic characteristics of ultra-precision aerostatic bearings

With high acceleration and ultra-precision requirements, the design of aerostatic bearings has been gradually focused on their dynamic performances. In this paper, the dynamic stiffness and damping coefficients of aerostatic bearings are investigated. Due to compressibility of the gas, the dynamic characteristics of aerostatic bearings show nonlinear frequency dependence. Particularly, their nonlinear dynamic behaviors are quite remarkable for
ultra-precision aerostatic bearings with small air gap heights and high supply pressure.     

Towards a complete numerical description of lubricant film dynamics in ball bearings

In this article, we propose a framework for a detailed finite element analysis of elastohydrodynamic lubrication in ball bearings. Our contribution to this field is twofold. First, we present a fully monolithic ALE method for the treatment of fluid–structure interaction. For the lubricant, we use the full Navier–Stokes equations in combination with a pressure-dependent viscosity law and include thermal effects. Second, we introduce a novel method for a fully implicit treatment of the evolution of the lubricants’ free surface using Nitsches method. This allows for arbitrarily large time steps independent of the spatial discretization. Despite the variety of numerical challenges present in this application, such as anisotropy and extreme values of pressure, our approach for the first time shows robustness up to high rotational speeds as required in industrial applications. We describe the numerical ingredients we use in detail and present numerical results that validate our approaches and demonstrate its capabilities.