困油压力对滑动轴承润滑状态的影响

为研究困油压力对轴承润滑状态的影响,在一个困油周期内,基于纯流体润滑状态设计要求,提出轴承-轴颈间所必需的承载量系数计算公式;依据泵样机参数,提出轴承-轴颈间所能提供的承载量系数的多项式拟合式;由所必需的承载量系数公式等于所能提供的承载量系数的定值优化方法,建立出困油压力与最小油膜厚度间的对应关系。通过一案例,对是否考虑困油压力的润滑状态计算结果进行比较和分析。案例分析结果表明:困油压力导致径向力增加45%～59%;导致最小油膜厚度降低19.6%～24.3%;困油压力造成轴承-轴颈间处于混合润滑状态,达不到原始的纯流体润滑状态设计要求。因此,困油压力对润滑状态影响较大,在泵轴设计中应充分考虑困油压力的影响,从而在结构上尽量缓解困油压力。     

旋涡泵中叶轮与泵体间动压场的应用研究

根据流体动力润滑理论，在旋涡泵叶轮两侧环形壁上，加工多个浅腔楔面，当叶轮转动时，其两侧环面和泵体壁之间形成多个流体动压区。保证了叶轮两侧问隙的均等性，使叶轮轴系转动的平稳性得到提高。根据侧隙泄漏量和功率损耗量得到了叶轮和壳壁之间的最佳间隙取值范围。     

钻机用重载齿轮减速器润滑系统解决方案

变频交流钻机的齿轮减速器主要采用链传动的润滑方案，在油田使用时齿轮减速器的润滑问题较为突出。针对这一问题，提出了润滑问题的两种解决方案，可供油田用户和设计者选择。     

高速牵引电机轴承试验原理及实践

介绍了“北京交通大学-NTN牵引电机轴承试验站”试验台的功能、性能指标以及各主要组成部分的结构与原理。列举了试验台建立以来主要完成的试验项目，并给出了典型的试验结果。本试验台可为轴承生产企业、高速牵引电机的设计等单位提供轴承、润滑油脂的性能测试服务。     

Aqueous lubrication of polymers: Influence of surface modification

We have investigated the influence of surface modification of an elastomer, poly(dimethylsiloxane) (PDMS), on its aqueous lubrication properties. A dramatic reduction in frictional forces has been observed upon hydrophilization by oxygen-plasma treatment or by surface coating with amphiphilic co-polymers, when PDMS was slid against PDMS in an aqueous environment. This effect is attributed to the removal of the strong hydrophobic interaction between PDMS surfaces in water, thereby enabling the isoviscous-elastic lubrication (or soft EHL) mechanism to predominate. This study demonstrates the significance of surface modification in allowing effective soft EHL of an elastomer.     

Investigation of Tribo-chemistry by means of Stable Isotopic Tracers: TOF-SIMS Analysis of Langmuir–Blodgett Films and Examination of their Tribological Properties

Deuterium-substituted and ¹³C-substituted octadecanoic acids were applied to study tribo-chemistry of binary-component Langmuir–Blodgett film deposited on Si(100) surfaces. Time-of-flight secondary ion mass spectroscopy was employed to study structure of the film. The isotopic tracers give typical fragment ions composed of the isotopes. Among these typical fragment ions, we paid attention to quasi-molecular ions and deuterium ion as “fingerprint region” of the film structure. The tribological properties of the binary-component film were evaluated by ball-on-plate type tribo-testers. The combination of octadecanol with octadecanoic acid affords good tribological properties, whereas the combination of octadecylamine with the acid gave poor results. The surface analysis of the plate after the tribo-test revealed that the alcohol and the acid were retained on the track even after the rubbing. On the other hand simultaneous removal of the acid and the amine from the surfaces were observed. Interactions between the acid and the amine were considered by the results of the tribo-tests and the surface analysis of the binary-component film.     

Dependence of the friction process on the molecular structure and architecture of thin polymer films

The frictional properties of a homologous series of poly(n-alkyl methacrylates) (PnAMA) and a series of poly(methyl methacrylate) (PMMA) films, cast from a variety of solvents, are characterized. The choice of polymer film was driven by the consideration of the possible mechanisms for the accommodation of a macroscopically applied shear stress by molecular entities. Two possible mechanisms are proposed: (i) the relative flexibility of the polymer backbone chain. For this purpose the PnAMAs have been chosen. By varying the length of the substituent chain, the relative molecular freedom around the backbone chain is altered. These molecular differences are sensed in the frictional properties at the macroscopic level, and (ii) the molecular organization is also proposed to be a factor in determining the friction response of a particular polymer film. For this purpose, the frictional properties of PMMA films cast from different solvents are investigated. There is observed to be a strong influence of the molecular organization on the frictional properties of the solvent cast PMMA films. The molecular probe employed to characterize the molecular environment is vibrational spectroscopy. Conformationally sensitive vibrational modes are used to determine the relative flexibility of the backbone chain and the organization of the chain network.     

On the steady-state performance of misaligned hydrodynamic journal bearings lubricated with micropolar fluids

The present work deals with the micropolar lubrication theory to the problem of the steady-state characteristics of hydrodynamic journal bearings considering two types of misalignment, e.g. axial (vertical displacement) and twisting (horizontal displacement). Using a finite difference method, the steady-state film pressures are obtained by solving modified Reynolds equation based on the micropolar lubrication theory. With the help of the steady-state film pressures, the steady-state performance characteristics in terms of load-carrying capacity, misalignment moment and friction parameter of a journal bearing are obtained at various values of eccentricity ratio, degree of misalignment and micropolar fluid characteristic parameters viz. coupling number and non-dimensional characteristic length.     

Thermo-elastohydrodynamic lubrication of an involute gear

This paper analyses the thermo-elastohydrodynamic lubrication on an involute spur gear tooth surface and the influence of the inlet temperature of the lubricant. The oil film temperature distribution shows a minimum near the point where the pressure distribution is a maximum and the energy loss a minimum. Then the temperature increases slightly in the outlet region. Calculated results show a decrease of a few percent in the maximum pressure distribution compared with an oil film on a rigid surface. Based on oil film thickness and gear tooth deflection, the load sharing coefficient and the relative transmitting errors are calculated. The behaviour of the oil film due to the variation of the normal tooth load at the transition point of the meshing is investigated also     

On the friction and wear behavior of PTFE composite filled with rare earths treated carbon fibers under oil-lubricated condition

Carbon fibers (CF) were surface treated with air-oxidation, air-oxidation followed by rare earths (RE) treatment and RE treatment, respectively. The friction and wear properties of the polytetrafluoroethylene (PTFE) composites filled with differently surface treated carbon fibers, sliding against GCr15 steel under oil lubrication, were investigated on a reciprocating ball-on-disk UMT-2MT tribometer. The worn surfaces of the PTFE composites were examined using a scanning electron microscopy (SEM). Experimental results revealed that surface treatment of carbon fibers reduced the wear of CF-reinforced PTFE composites. Among all the treatments to carbon fibers, RE treatment was the most effective and lowest friction and wear rate of CF-reinforced PTFE composite was exhibited, owing to the effective improvement of the interfacial adhesion between the carbon fibers and PTFE matrix.