Calculation of Stribeck curves for line contacts

A mixed lubrication model is presented by which Stribeck curves can be calculated. By means of the Stribeck curve the transitions from boundary lubrication to mixed lubrication and the transitions from mixed lubrication to elasto-hydrodynamic lubrication can be predicted and subsequently the lubrication regime in which a particular contact operates can be predicted. Calculations are restricted to line contacts, because of the wide range of applications of line contacts or of very wide elliptical contacts.     

Journal bearing performance under starved lubrication

The hydrodynamic performance of a journal bearing under starved lubrication conditions is studied theoretically and experimentally. When lubricant is supplied to a journal bearing from an oil groove at an insufficient oil flow rate, the hydrodynamic oil film cannot cover the full width of the bearing at the inlet of the convergent bearing clearance, and the covered width increases gradually with the decrease in film thickness in the circumferential direction. This phenomenon affects the static and dynamic performance of the journal bearing. The oil film boundary in the bearing clearance is calculated numerically for a constant load and a constant speed under the assumption of laminar, iso-viscous lubrication. Measurements are in good agreement with predictions. Some more calculations of journal centre loci are given.     

薄膜润滑的分层理论与实验

利用油膜分层理论分析薄膜流体润滑条件下轴承的特性 ,并进行实验对比。说明分层模型在膜厚计算中的可行性 ,从而说明分层模型适用于从厚膜到薄膜的整个润滑区域 ,是全域解。     

中直径水介质高压机械回转密封的研究

分析了新型大直径水介质高压机械回转密封的结构和工作原理,讨论了动密封环的设计计算方法,试验研究表明,该密封理论可行、结构合理、具有密封间隙自动补偿性能、寿命长、泄漏量小、性能稳定,能够满足工业应用的要求,其密封原理可推广到掘进机及高压旋转供液系统的大、中直径密封上,具有良好的应用前景。     

The ideality of polydisperse perfluoropolyether lubricants with application to physical vapor deposition

We have used thermogravimetric analysis (TGA) to measure the evaporation rate as a function of temperature and molecular weight for an alcohol-derivatized perfluoropolyether (PFPE), Fomblin Zdol. We show that the bulk evaporation rate of a polydisperse Zdol solution during temperature ramp TGA can be numerically simulated by combining molecular weight dependent Arrhenius parameters, the initial molecular weight distribution as measured by size exclusion chromatography, and Raoult’s law of vapor pressures. The simulation is shown to be in good agreement with experiment for both a low molecular weight polydisperse Zdol, and for a mixture of the low molecular weight Zdol with a heavier Zdol fraction. Mixtures of Zdol with non-functionalized Z lubricants are shown qualitatively to deviate substantially from ideality. In the disc drive industry, physical vapor deposition (PVD) is receiving renewed interest as an alternative method of applying the PFPE lubricants commonly employed as topical coatings on thin film magnetic media. In a process involving vaporization of a polydisperse liquid phase lubricant, quantitative prediction of deposition rates and vapor phase molecular weight distributions will in general only be possible with accurate knowledge of liquid phase distributions, component evaporation rates, and the ideality of the solution. This revised version was published online in August 2006 with corrections to the Cover Date.     

环境压强对电刷镀In/Ni固体润滑涂层摩擦学性能的影响

为了探索软金属铟在真空环境中的润滑性能,用电刷镀技术在45#钢表面制备了In/Ni复合固体润滑涂层,并对比研究了该复合镀层在大气环境、低真空环境和高真空环境下的摩擦学性能和磨损机制。结果表明,In/Ni镀层具有良好的减摩和抗磨性能,随着环境压强的降低,In/Ni镀层的摩擦学性能明显提高,镀层的磨损机制主要为粘着磨损和疲劳磨损。分析认为,不同环境压强下镀层摩擦学性能的差异,主要与镀层的氧化和软化有关。     

类金刚石薄膜在干摩擦、油和脂润滑条件下的摩擦学性能分析

通过钢/类金刚石(DLC)薄膜摩擦副在干摩擦4、122油和L252脂润滑条件下的球-盘摩擦学试验,对比分析润滑条件、载荷、速度对DLC膜摩擦系数的影响,利用原子力显微镜分析膜层磨损性能,研究润滑条件对膜层磨损寿命的影响。结果表明:油、脂润滑下DLC膜最大静摩擦系数分别减小了17%和38%;从0～2000 r/min转速范围内,DLC膜摩擦系数随转速增加而减小,油润滑下相比干摩擦DLC膜摩擦系数小15%～48%,脂润滑下相比干摩擦DLC膜摩擦系数在0～500 r/min转速范围小,超过500 r/min后干摩擦DLC膜摩擦系数小;油和脂润滑条件下,DLC膜层的磨损程度明显降低,磨损率相比干摩擦条件下分别减小了7.4倍和15.5倍。     

平行滑块表面不同形状复合型织构的润滑性能研究

目的 研究具有仿生硅藻结构的复合型织构对滑动轴承润滑性能的影响.方法 采用流固耦合的方法,对具有复合型织构的单元模型进行研究,依照硅藻的多孔结构,设计出矩形-半球型、矩形-椭球型、圆柱-半球型及圆柱-椭球型等4种类型的织构,建立这几种复合型织构的单个单元模型.在不同面积率和织构深度条件下,分析不同织构类型对滑动表面摩擦...     

铜及铜合金薄带轧制的润滑及冷却分析

铜及铜合金薄带轧制过程中润滑-冷却是一项十分重要的工艺.讨论了轧机润滑冷却系统的组成、工艺润滑的分类和作用原理,工艺冷却的作用;分析了工艺润滑剂的种类、使用要求、品质评价体系以及维护要求和做法,对铜及铜合金薄带轧制润滑油的选择提出了自己的观点.     

铝及铝合金热轧用乳化液应用技术

热轧产品的质量很大程度上取决于起冷却和润滑作用的乳液的性能。通过分析乳液在铝及铝合金热轧过程中的主要作用及原理,介绍了常见的几种润滑形式及热轧粘铝形成机理,同时通过对乳液的重点指标控制,阐述了铝及铝合金热轧产品表面质量的控制手段。此外还介绍了使用Mastersizer颗粒度仪器检测乳化液颗粒度及其维护管理。