Lubricant oils additivated with polymers in EHD contacts: Part 2. Tests using a four‐ball machine

A mineral oil of low viscosity was additivated with different concentrations of low‐density polyethylene. The wear behaviour of the additivated samples and the base oil was evaluated using a four‐ball wear tester at constant speed and variable load. Steel and ceramic (silicon nitride) were chosen for the balls. The scuffing resistance of the ceramic balls was higher than that of the steel balls. No scuffing appeared in the case of an upper steel ball in contact with lower ceramic balls. As far as the minimum wear‐scar diameter on the lower balls was concerned, an optimum concentration of polymer added to the base oil was found from the experimental data, for both types of ball. For the systems investigated, the optimum concentration was about 1.0% polyethylene.     

圆锥滚子轴承有效壁厚计算程序的开发

轴承套圈有效壁厚其选材和热处理工艺的制定具有重要意义。而类似于圆锥滚子轴承之有效壁厚往往不能一目了然,对于此问题可使用部分程序软件使其计算过程程序化,以达输入部分参数,瞬间即可得其结果之效,从而提高工作效率。     

Performance of synthetic oils in the hydrodynamic regime ‐ II. Generalisation

In Parti I the results of an extensive experimental investigation of the performance of environmentally adapted oils in the hydrodynamic regime were reported. Four oils were tested in a tilting‐pad thrust bearing for different combinations of load, shaft speed, and supply oil temperature. In this second part, details of a generalisation procedure are described. A number of parameters representing the physical properties of an oil, such as viscosity and viscosity‐temperature coefficient, are adopted. The influence of each of these parameters on minimum oil film thickness, maximum temperature rise, and bearing power loss is then analysed. It is shown that viscosity measured at the supply oil temperature is the most important parameter. The effects of the viscosity‐temperature coefficient and oil thermal conductivity are less pronounced and yet significant. It is also shown that it is not possible to select an optimum oil that yields maximised oil film thickness, minimised temperature rise, and minimised power loss at the same time.     

汽车驱动桥主减速器圆锥滚子轴承滚子接触应力分析

对汽车驱动桥主减速器圆锥滚子轴承进行弹性流体动力润滑分析,根据润滑油的物理参数和滚子承受的载荷,求出了油膜压力和摩擦因数.然后利用有限元软件对受载荷最大的滚子进行了有限元分析,得出了滚子在外部载荷和惯性力作用下的接触应力分布,得出驱动桥主减速器工作时的惯性力对圆锥滚子轴承的影响是必须考虑的因素.     

圆锥滚子轴承阻尼的计算方法

在对圆锥滚子轴承进行受力分析的基础上,利用弹性流体动力润滑理论,得到承载最大滚子与内、外滚道间的最小油膜厚度计算式,并将其引入滚动轴承阻尼计算过程,建立了包含轴承滚子阻尼和油膜阻尼的轴承综合阻尼计算模型.     

FEA在圆锥孔四列圆锥滚子轴承径向游隙设计中的应用

在圆锥孔四列圆锥滚子轴承径向游隙的设计中，利用有限元分析（FEA)方法对过盈配合而导致的内圈膨胀量的差异进行了分析、计算，得到了该类轴承的各列径向游隙相互差，为轴承的游隙设计提供了依据。     

Lubricant oils additivated with polymers in EHD contacts: Part 1. Rheological behaviour

This paper reports on the influence of a polymer additive on the traction behaviour of a mineral oil investigated using a two‐disc machine at different temperatures and contact pressures. A semi‐empirical approach was used for determining the effective lubricant rheological parameters ‐ the elastic shear modulus, the viscosity of the lubricant, and the limiting and Eyring stresses ‐ in elastohydrodynamic contacts. Using this approach, the effect of polymer concentration on the rheological parameters that appear in both the Johnson‐Tevaarwerk and Bair‐Winer models was quantified. The influence of operating conditions, such as pressure, oil temperature, and polymer concentration, on the traction coefficient, limiting shear stress (from the Bair‐Winer model), Eyring stress (from the Johnson‐Tevaarwerk model), shear modulus, and apparent viscosity was also investigated.     

Viscosity–pressure–temperature behaviour of mineral and synthetic oils

A new high‐pressure viscometer that can measure viscosity at pressures up to 0.8 GPa has been developed in the authors' laboratory. The ‘modulus equation’ has been used to compare the behaviour of mineral and synthetic lubricants. Among the oils investigated there was one ester that biodegraded rapidly both before and after ageing in a long‐term test‐rig operation. To facilitate a comparison or application of the results to other oils, an analysis of the correlation between the viscosity—pressure coefficient and the kinematic viscosity measured at atmospheric pressure has been provided. A prediction of lubricant film thickness based on high‐pressure viscosity data is compared with film thickness measurements in a roller bearing.     

A study of the rheological behaviour of multigrade oils

The rheological behaviour of four blends of multigrade oils containing different commercial viscosity index improvers has been studied for increasing shear rate and temperature. Polyalkylmethacrylate has been found to demonstrate different behaviour to styrene-isoprene, styrene-butadiene and ethylene-propylene copolymers. Oil blends for all these hydrocarbon copolymers have shown non-Newtonian behaviour with increasing shear rate (0 to 35,000 s⁻¹) at low and moderate temperatures (−15 to 40°C), i.e. their viscosities were subject to a significant decrease, while the viscosity of the polyalkyl-methacrylate blend showed a limited decrease. With increasing shear rate at high temperature (100°C), all the formulated blends behaved as Newtonian fluids, i.e. with nearly constant viscosities. Increasing shear rate can also change the behaviour of some hydrocarbon copolymers from thickeners to viscosity index improvers.     

基于最小油膜厚度的航空圆柱滚子轴承修正寿命研究

建立航空圆柱滚子轴承寿命计算的数学模型,比较ISO281:1990和ISO281:2007两种标准中关于滚动轴承寿命计算方法及修正系数的差异。针对航空轴承样本少、修正系数取值困难等问题,通过采用道森-希金森方程计算最小油膜厚度,确定滚动轴承的修正系数。通过某型直升机传动系统圆柱滚子轴承寿命的计算研究,验证了该方法的可行性。     

圆锥轴承内圈大挡边与滚子基面摩擦和噪声分析

通过对设计和设备的改进,内圈大挡边与滚子球基面之间的滑动摩擦及滑动摩擦部位的振动噪声都得到很大地改善。     

降低圆锥滚子轴承摩擦力矩的方法

分析了圆锥滚子轴承摩擦力矩的产生原因，指出：在不改变其设计结构，不减小轴承额定载荷的前提下，通过加大内滚道、外滚道和滚子的凸度，合理选择凸度形状，有效控制滚子球基面半径的散差和挡边角度，降低挡边和球基面的粗糙度，可大幅度降低圆锥滚子轴承的摩擦力矩。     

Rheological properties of high‐viscosity‐index mineral base oils for automotive engine lubricants

Viscosity‐pressure‐temperature relations for paraffinic mineral base oils at pressures up to 0.7 GPa and temperatures between 30 and 90°C were determined using a falling‐ball‐type viscometer. The oils used were solvent refined oils, hydrocracked oils, and an oil produced by a wax isomerisation process. The viscosity at pressures higher than those possible with the viscometer was then derived by applying a simplified solution to the traction curves determined using an elastohydrodynamic disc‐on‐ball tester. When the measured viscosity and the calculated viscosity were plotted against pressure, for the oils with a viscosity index higher than 120 the viscosity derived from traction measurements followed the curve extrapolated to the high‐pressure region using either the Yasutomi or Roelands equations (the parameters for which were obtained using the viscometer). However, the calculated viscosity for the lower‐viscosity‐index oils deviated upwards from the extrapolated curve.     

圆锥滚子轴承套圈精密辗扩

介绍了圆锥轴承套圈精密辗扩机的结构、控制原理及各主要组成部分的设计特点。经试验验证，其机械、电气、液压等系统工作可靠，机床调整简单，辗扩后的毛坯尺寸精度高，车加工余量小。冷辗后的套圈金属流线分布合理，内部组织致密，提高了轴承的使用寿命。     

Correlation of structure and properties of groups I to III base oils

The understanding of the relationship between molecular structure and viscosity–temperature behaviour of a lubricant system is a subject of considerable importance. The quantitative distribution and types of different classes of hydrocarbons such as aromatics, paraffins (normal and iso) and naphthenes determine the physico‐chemical behaviour of a lubricant system. The study of molecular structure and molecular alignment of hydrocarbons constituting a lubricant helps in the development of lubricating oil with desired physico‐chemical properties. The present study highlights the application of nuclear magnetic resonance spectroscopic technique for deriving detailed hydrocarbon structural features present in API groups II and III base oils produced through catalytic hydrocracking/isodewaxing processes. The viscosity–temperature and viscosity–pressure properties, such as viscosity index, pour point, elastohydrodynamic film thickness and cold cranking simulator viscosity, were determined. The structural features of these base oils such as various methyl branched structures of isoparaffins and branching index, which are characteristics of high performance molecules, were correlated with the above‐mentioned properties to explain their physico‐chemical properties, particularly low temperature properties. The molecular dynamics parameters such as diffusion coefficient and T₁ relaxation times estimated from the nuclear magnetic resonance spectral studies have provided sufficient evidence for the dependence of these properties on these high performance molecules present in various types of methyl structures of isoparaffins of groups II and III base oils compared with conventional group I base oils. Results are explained on the basis of molecular structural differences of hydrocarbons present in these base oils and diffusion measurement studies. On the basis of the studies, molecular engineering concept for the designing of a high performance base oil molecule is proposed. Copyright © 2012 John Wiley & Sons, Ltd.     

圆锥滚子轴承内圈滚道磨削和质量控制

圆锥滚子轴承内圈滚道存在凸滚道和直滚道两种磨削方式,内滚道的磨削加工要根据产品性能要求控制滚道有关尺寸、精度等各质量参数,对凸滚道要检查滚道凸出量、凸出形状和位置。     

Partial EHL analysis of rib-roller end contact in tapered roller bearings

A partial EHL analysis was performed for the tapered rib/spherical roller end contact in tapered roller bearings. The average Reynolds equation, the elasticity equation and the pressure-viscosity relation were solved simultaneously. The effects of the surface roughness as well as the peculiar geometrical and kinematics parameters of the rib-roller end contact on the friction torque and film thickness were investigated. The optimal ratios of radius of curvature of roller end to rib face were deduced, which confirm the previous finding with the theory of smooth surfaces. The significant range of surface roughness, and the optimal surface roughness for the roller big end were obtained. It was found that asperity contacts extend into the outlet zone. The results are significant for the design of rib faces and roller ends. The theoretical treatment is validated by its good correlation with the existing experimental data for smooth surface contact.     

全密封轧辊轴承密封结构的改进

针对全密封特大型轧辊轴承传统密封结构存在的问题,改进了密封组件的结构,并探讨了密封圈主要结构参数的选取。改进后挡边的厚度大大减小,而且保持架小端可以向密封方向延伸,大大释放了滚子可利用的空间,使轴承的整体结构更加紧凑,轴承的承载能力、使用寿命和润滑性能得到了有效提高。     

Temperature rise of double-row tapered roller bearings analyzed with the thermal network method

Based on generalized Ohm׳s law, the thermal network model (TNM) is developed for double-row tapered roller bearing lubricated with grease, which is commonly used in high-speed railway. The load distribution and kinematic parameters in bearing are obtained by developing a quasi-static model. The temperature of bearing at different speeds, filling grease ratios and roller large end radius are investigated. The results show that large rotating speed and filling grease ratio result in high temperature rise, especially at roller large end/flange contacts. Besides, an optimal roller large end radius is presented and its mechanism has been explored.     

发动机圆柱滚子轴承载荷分析及刚度计算

在发动机圆柱滚子轴承拟静力学分析的基础上,建立了基于轴承径向游隙和油膜厚度的圆柱滚子轴承刚度计算模型。研究了圆柱滚子轴承的刚度特性,分析了圆柱滚子轴承的载荷分布和受载变形情况,为发动机轴系有限元分析中边界条件的处理提供了依据。