考虑粗糙度时不同衬层材料水润滑轴承润滑特性比较*

以水润滑轴承为研究对象,考虑表面粗糙度的影响,针对丁腈橡胶（NBR）、赛龙、飞龙、超高分子量聚乙烯(UHMWPE)4种新型非金属衬层材料建立润滑数学模型,并推导水膜厚度方程;采用有限差分法,研究考虑实际表面粗糙度时4种新型衬层材料的衬层变形、水膜厚度和水膜压力的变化规律,分析最大水膜压力和承载力随转速的变化,并与表面光滑轴承进行对比。结果表明：考虑表面粗糙度时水润滑轴承的衬层变形和水膜厚度均呈波状分布,衬层变形减小,最小水膜厚度变薄,而水膜压力有轻微的局部突变,最大水膜压力增大,承载力下降;4种材料的变形量和最小水膜厚度由大到小均依次是NBR、赛龙、飞龙、UHMWPE,水膜压力由大到小依次是UHMWPE、飞龙、赛龙、NBR。在相同工况下,NBR衬层材料比其他3种衬层材料相对容易形成润滑水膜,而UHMWPE衬层材料可以保证系统承受较大的承载力。研究结果对水润滑轴承材料选型和加工装配有一定的参考意义。     

变黏度静压滑动轴承高速时油膜动态润滑特性

静压滑动轴承转台直径大（D=4.5 m）,高转速运行时产生线速度值很大,其内部润滑油膜受压及剪切发热导致油膜变薄进而影响到机床加工精度和运行可靠性。针对新型Q1-205双矩形腔静压推力轴承,采用动网格技术探索变黏度条件静压轴承高速时的油膜动态润滑特性。建立该静压轴承的流量、承载力、油膜温升等理论模型,自定义用于控制边界层网格运动及变黏度的UDF程序,选取外载荷12 t,转速为80~200 r/min（线速度18~48 m/s）高速下的工况条件参数进行动态润滑特性数值模拟,并进行相同工况参数下的试验验证,揭示出高速时油膜厚度变化对油膜温度、油腔压力、封油边处流量的影响规律。研究发现,该型号轴承在承载12 t时,随着膜厚的减小,油膜剪切发热严重,温升加剧,且高速下受润滑油黏度变化影响造成压力损失严重,研究数据为工程上静压轴承可靠运行提供理论依据。     

复合材料水润滑艉轴承结构设计研究

基于ANSYS CFX流固耦合数值计算方法,对水润滑复合材料艉轴承的润滑性能及结构设计开展研究,阐述了不同水槽结构、间隙比、长径比、直径等对轴承承载力以及水膜压力、轴承变形量、最小水膜厚度、轴承摩擦因数的影响规律。并利用水润滑轴承试验台研究了不同水槽结构对轴承启动摩擦转矩、转变速度以及摩擦因数的影响。研究表明,轴承摩擦因数、水膜最大压强、轴承最大变形随水槽数增多而增大;轴承承载力、最小水膜厚度随间隙比增大而减小,随长径比增大而增大。总结了直径为100~500 mm、长径比为2~3、间隙比为0.1%~0.2%的水润滑艉轴承承载力的变化规律,为水润滑艉轴承设计提供一定的理论依据。     

Non‐Newtonian and thermal effects in constant flow valve compensated symmetric hole‐entry hybrid journal bearing

Every high speed machine, demanding high level of perfection, can operate successfully through a precise design of bearings. Such a design can be formulated after carefully studying both static and dynamic characteristics of the journal bearing. The present paper described the study of static and dynamic performance of a hole‐entry hybrid journal bearing system compensated with constant flow valve restrictor by considering the combined influence of thermal effects and non‐Newtonian behaviour of the lubricant. The variation of the viscosity due to the non‐Newtonian behaviour of the lubricant and temperature rise has been considered in the study. The numerical solution of the generalized Reynolds equation governing the flow of the lubricant, having variable viscosity along with the energy and heat conduction equations, was obtained using finite element method. The non‐Newtonian lubricant has been assumed to follow the cubic shear stress law. The study included the performance of a double row symmetric hole‐entry hybrid journal bearing configuration containing 12 holes per row. The results presented in this paper indicate that change in viscosity of lubricant affects the performance of the hole‐entry hybrid journal bearing system quite significantly. Copyright © 2007 John Wiley & Sons, Ltd.     

Performance of slot-entry hybrid journal bearings considering combined influences of thermal effects and non-Newtonian behavior of lubricant

This paper presents theoretical investigations of the thermal and rheological effects of lubricant on the performance of symmetric and asymmetric slot-entry hybrid journal bearing system. FEM has been used to solve the Reynolds equation governing flow of lubricant in bearing clearance space along with restrictor flow equation, energy equation and conduction equation using suitable iterative technique. The thermohydrostatic (THS) rheological performance of slot-entry hybrid journal bearings are studied for small temperature variation of the lubricant. The computed results reveal that variation of viscosity due to temperature rise and non-Newtonian behavior of lubricant affects the bearing performance quite significantly.     

考虑润滑油黏温效应的动压滑动轴承性能分析

滑动轴承的相关研究很多都基于等黏度的情况下,这与轴承的实际工作情况有较大的出入。使用计算流体力学FLUENT通过编写的黏温方程UDF程序进行动压滑动轴承润滑油黏度的计算,并考虑黏温效应对动压滑动轴承性能的影响,比较等黏度与变黏度情况下动压滑动轴承的油膜压力与承载力、油膜的轴向与周向温度分布。结果表明:在考虑黏温效应条件下,轴承的承载力、油膜压力、摩擦力均小于定黏度条件下,这是由于温度升高导致黏度降低,从而减小了油膜静压力和承载力;在轴承轴向方向上,从油膜中心位置向两端部,油膜温度逐渐升高;在轴承圆周方向上,从收敛区到发散区,油膜温度先升高后降低,油膜温度峰值出现在轴承发散区的端部位置。     

水润滑动静压轴承三维压力及温度场分布理论研究

以4腔、毛细节流形式下的深腔动静压轴承为研究对象,采用有限差分数值方法求解了广义雷诺方程,该过程考虑了紊流、粘度和密度随压力及温度变化的影响。研究得到了在水介质润滑下的动静压轴承三维压力分布、温度场分布及动特性系数。结果表明在高速高压水润滑条件下的动静压轴承表现出了与粘度较大的油润滑条件下不同的液腔压力分布、温度分布等特性。水润滑轴承第3和第4个液腔压力较大,第1个液腔主要用来增加其稳定性,而同等条件下的油润滑轴承第2和第3个油腔压力较大,第4个液腔增加其稳定性。相比油润滑轴承,水润滑轴承温升较高,因此对于低粘度介质润滑下的轴承性能研究需要考虑温升影响。     

Variable-viscosity effects in externally pressurized spherical oil bearings

Externally pressurized spherical bearings were analysed considering the rotational inertia of the lubricant and the variation of the lubricant viscosity along the flow. The equations of motion expressed in spherical coordinates were suitably reduced to describe the lubricant flow through the bearing clearance. A numerical solution of the resulting equations, in which the variation of viscosity with temperature was considered, was obtained using the finite-difference technique. The effects of bearing geometry, bearing speed, inlet oil temperature, bearing load, lubricant flow rate and frictional torque on pressure and temperature distributions under adiabatic flow conditions were investigated. Satisfactory agreement between experiment and the adiabatic solution was found for a high speed factor. The theory is applicable to both fitted and clearance-type spherical bearings.     

关节轴承固体润滑处理工艺

介绍一种关节轴承固体润滑处理技术,制备的固体润滑膜以无机盐和活性金属离子为黏结剂,提高了膜层的耐压强度和耐温性能;以石墨和二硫化钼复合材料为润滑剂,提高了关节轴承在不同工况条件下的承载能力和润滑性。经固体润滑处理的轴承内圈外表面润滑膜层均匀、外观细致,实际使用效果良好。经检测,形成的固体润滑膜与金属基体有较强的结合力,在特殊工况条件下能够满足承载和润滑性能的要求。     

镶嵌式复合径向滑动轴承的实验研究

对镶嵌式径向滑动轴承进行了实验研究,通过摩擦磨损实验进行了选材,提出了加工该型轴承的制造工艺,并采用台架试验测试了制得的几种镶嵌式径向滑动轴承的承载能力。结果表明：镶嵌式径向滑动轴承的承载能力比普通径向滑动轴承有较大的提高,其中镶嵌PTFE高分子材料的轴承,因PTFE材料能在其对偶件表面形成较为完全的转移膜,改善了轴承润滑性能,使轴承具有较高的承载能力。     

UHMWPE基水润滑尾轴承润滑特性仿真及试验研究

针对UHMWPE基高分子复合材料水润滑轴承的润滑特性开展研究。采用双向流固耦合算法研究弹性模量和泊松比等材料参数以及转速、负载等工况参数对水润滑轴承偏心率、最大水膜压力、轴承最大变形量、最小水膜厚度、摩擦因数等润滑特性的影响。基于改性UHMWPE高分子复合材料轴承的试验,验证了仿真方法的正确性。研究表明:计入弹性变形的流固耦合算法在研究高分子复合材料轴承性能方面具有更高的精度;随轴瓦材料弹性模量和泊松比的增大,轴承承载力逐渐增大、弹性变形量逐渐减小;随负载增大,轴承最大水膜压力和最大变形量基本呈线性增长;随转速增大,轴承最大水膜压力和轴承最大变形量显著减小;对于高分子复合材料轴承,低速、重载工况下不计入弹性变形的算法误差更大。     

水润滑轴承水膜压力无线测试系统研究

为了深入研究水润滑轴承特性,需要了解轴承真实的水膜压力分布,而传统的滑动轴承润滑膜压力测试无法获得轴承全周水膜压力的连续分布,且采用集流环作为信号传输媒介,其成本较高、对输出信号干扰较大。针对以上不足,研究并设计了一种无线测试系统,可测量水润滑轴承全周水膜压力,并实时监测水润滑轴系的运转情况。介绍了测试系统组成,包括无线采集发射与接收装置、传感器与信号调理模块、测试软件及水润滑轴承试验台,最后应用此系统对八沟槽水润滑平面橡胶轴承的水膜压力进行测试,并与仿真结果对比分析。结果表明,该测试系统实用性良好,可用于测试其他材料和结构的水润滑轴承的水膜压力。     

Velocity analysis for layered viscosity model under thin film lubrication

The lubrication of bearings is directly affected by the flow properties of the liquid lubricant. One key feature of lubricant is its viscosity distribution in the bearing. The distribution is dependent on the adsorbent properties of the surface and the velocity distribution of the lubricant. This paper is only connected with the velocity analysis on the cross-gap flow. Because of increasing the speed, apart from increasing the temperature, the other features of lubricant will be changed. When fluid film is thin, the speed effects become important due to the increased shear rate. This paper describes the fluid velocity profiles produced for the case where layers of greater viscosity than the bulk occur on the bearing surfaces.     

The influence of the lubricant film on the stiffness and damping characteristics of a deep groove ball bearing

This paper experimentally investigates the formation of a lubricant film in a deep groove ball bearing and its effect on the bearing dynamics. A novel test rig is introduced, which allows testing different types and sizes of bearings in real-life conditions. The test rig dynamics are optimised such that the dynamic properties of the bearing are measured in a frequency range below the resonances of the flexible modes. Two properties of the bearing, both its stiffness and damping value in the direction of the static bearing load, are identified. The behaviour of the lubricant film between the rolling elements and raceways is measured based on the electrical resistance through the bearing. For this purpose, the bearing housing is electrically isolated from the surrounding structure. The electrical resistance, stiffness and damping of the test bearing are identified during a speed run-up. The influence of the bearing temperature is analysed as well. During a run-up at constant bearing temperature, the measurement of the electrical resistance describes the formation of the lubricant film. Due to the formation of the lubricant film, the bearing stiffness increases by 3.2% while the damping increases by 24%. During a warm-up of the bearing, the viscosity of the lubricant film decreases strongly. A resulting decrease in electrical resistance, stiffness and damping is measured. Finally, the electrical resistance, stiffness and damping are identified at different speeds, after the bearing has reached a stable temperature at each speed. A combined effect of both rotation and temperature is observed and discussed.     

Calculation of oil‐film thickness in journal bearings running at varying rotational speeds

There are many methods of calculating the properties of lubricated hydrodynamic sliding bearings running at variable loads, but, in some cases, sliding bearings of heavy‐duty machines run under constant load and at variable speeds; this can lead to reduced film thickness in the bearing and boundary lubrication. The minimum oilfilm thickness in such a bearing needs to be calculated so that the proper lubricant viscosity can be selected to reduce solid‐solid contact during machine operation. In this study, a method is presented for calculating the film thickness of sliding bearings operating with alternating rotational directions. The results of the calculations show that the squeeze effect can develop enough load‐carrying capacity to prevent solid‐solid contact between the rubbing surfaces during operation, provided the change of direction of rotation is quick enough.     

立式水润滑可倾瓦轴承-转子试验台设计*

第三代压水堆核电站中广泛采用的立式水润滑轴承技术是制约我国核电发展的关键点之一,因此建立立式轴承试验台进行相关试验有重要的工程价值。提出一种包含加载激励约束系统、供水密封系统、测量系统的立式水润滑可倾瓦轴承试验台设计方案;通过比较卧式轴承试验台和立式轴承试验台在加载时对于轴承约束的不同,给出适合立式轴承试验台的浮动轴承约束机构方案;按照相似准则对AP1000核主泵立式水润滑可倾瓦轴承进行缩比设计,在满足Summerfeld数、宽径比和间隙比要求的条件下,设计出适合试验研究的轴承试件。试验结果显示：研制的立式四瓦可倾瓦水润滑轴承试验台,能够实现试验轴承在不同转速和加载、激励工况下瓦面温度、供水压力、静载荷、水膜脉动压力、转轴涡动等的测量,运转状态稳定,可以满足立式水润滑可倾瓦轴承动静特性的研究要求。     

Hybrid journal bearings with particular reference to hole-entry configurations

There is a spectrum of pressure-fed journal bearings ranging from the purely hydrostatic bearing characteristics, ie zero speed operation, to the purely hydrodynamic bearing characteristics which depend completely on speed. Between these two extremes, hybrid bearing characteristics rely on mixed modes of external pressurisation and speed-dependent pressurisation. Large high speed hydrodynamic bearings require the lubricant to be pumped under pressure for temperature control. It is therefore attractive to use this external source of pressure to enhance the start-up performance by reducing wear and improving stability. Hybrid bearings offer the possibility of improving on both the zero-speed characteristics of hydrostatic bearings and on the whole range of speed characteristics of hydrodynamic bearings. It is concluded that hole-entry bearings may be particularly effective when compared with other bearing configurations for good load support and low energy consumption, when used in any of the four modes of operation including: zero-speed hydrostatic mode; high-speed hydrodynamic mode; zero and high-speed hybrid mode; and jacking mode where areas are pressurised for start-up. A modification to the procedure for solving the Reynolds equation is introduced to cope with cavitated regions. The technique presented for solving the bearing pressures and cavitation boundaries is efficient and has relevance to any type of liquid film bearing     

UHMWPE复合材料水润滑轴承润滑状态转变性能研究

水润滑轴承润滑介质的黏度较低,轴承动压润滑难以形成。研究水润滑轴承润滑状态转变特性,可为水润滑复合材料轴承的设计和优化提供依据。建立水润滑轴承流固耦合计算模型,研究轴承承载力、水膜压力、轴承变形量随工况的变化关系,提出水膜厚度测试方法,研究轴承摩擦因数、水膜厚度随转速、负载的变化规律。研究结果表明:随偏心率和转速增大,轴承承载力、最大水膜压力和最大变形量均逐渐增大;随转速增大,轴承承载力、最大水膜压力和最大变形量的增幅逐渐减小。试验发现随着负载增大,改性UHMWPE轴承从混合润滑向动压润滑转变的膜厚比逐渐减小。     

对称可倾瓦推力轴承的热弹性流体动力润滑

本文对对称可倾瓦推力轴承的热弹性流体动力润滑特性进行了理论分析，考察了温升、轴承零件的弹性变形和热变性，轴承前端的冲击压力、流体的惯性力等四类因素对轴承工作性能的影响。数学模型中的全部方程均用无量纲形式给出，并用数值方法求解，从而得到了给定条件下润滑油膜的压力、形状、温度、速度等的分布规律。     

水润滑动静压滑动轴承的临界温度研究

建立水润滑动静压滑动轴承的弹流润滑几何模型,采用考虑热效应的Reynolds方程,对水润滑动静压滑动轴承进行弹流理论分析,计算一定供水压力下当润滑剂局部最高温度达到临界值时不同的速度、载荷极限值;分析润滑介质、轴瓦材料以及供水压力变化对速度、载荷达到极限值时的临界温度曲线的影响,得到润滑剂局部最高温度达到临界温度时的轴承速度和载荷极限值的临界温度曲线,并通过拟合得到曲线的函数表达式。研究结果显示:海水润滑下的临界温度曲线高于纯水润滑,塑料轴瓦的临界温度曲线高于陶瓷轴瓦;供水压力对不同轴瓦材料的临界温度曲线变化趋势影响不同,对不同润滑介质的临界温度曲线的变化范围影响不同。