连续波状粗糙度对直齿轮热弹流润滑的影响

工程实践中没有理想光滑的表面,在齿轮弹流润滑中,油膜的厚度通常与某些切削工艺形成的金属表面粗糙度处于同一数量级,所以表面粗糙度对齿轮弹流润滑的影响是不应该忽略的。在考虑不同啮合点处的曲率半径、卷吸速度、轮齿载荷随时间变化的基础上,考虑轮齿表面连续波状粗糙度对弹流润滑的影响,利用多重网格技术求得齿轮瞬态微观热弹流润滑的完全数值解。结果表明,连续波状粗糙度会造成齿轮瞬态弹流润滑的油膜压力和温升产生振荡,并使最小膜厚变薄,最高压力变大,最大温升增大。轮齿间振荡的高压和高温会造成齿轮振动疲劳破坏,所以连续的波状粗糙度对齿轮的润滑是不利的。     

AutoCAD下的斜齿圆柱齿轮三维模型系统的开发方法

介绍了在AutoCAD2000环境下,用Autolisp语言编程在计算机上建立斜齿圆柱齿轮三维模型的方法,它操作简便,造型精确,可大大提高设计效率。     

齿廓修形斜齿轮沿接触线的弹流润滑计算

应用多重网格法，在三条接触线上同时获得具有典型弹流润滑特征的压力分布和油膜形状，进而计算了接触线上的载荷分布：通过修形，改善了齿面的润滑状况。提高了齿轮的抗胶合能力。     

螺旋角对双圆弧齿轮弹性流体动压润滑的影响

分析了螺旋角对双圆弧齿轮弹性流体动压润滑（EHL）油膜厚度的影响,并选择合适的螺旋角,使圆弧齿轮具有更好的润滑性能。     

N次谐波凸轮-挺柱副的润滑特性分析

将线接触弹流润滑理论应用于发动机配气机构,计算了某N次谐波凸轮-挺柱副润滑的稳态最小膜厚、膜厚比等参数,分析了凸轮．挺柱副稳态润滑在设计转速下随凸轮转角的变化特征,比较和讨论了发动机转速变化对润滑性能的影响。结果表明,凸轮桃尖区多为部分弹流润滑状态和边界润滑,工作段其它部分多为部分弹流、完全弹流和动力润滑状态。曲轴转速提高一般情况下对增加稳态最小膜厚有利,但由此导致的载荷波动量增加对最小膜厚的稳定性不利,从而使表面摩擦和磨损的可能性增加。     

橡胶滑块与镀镍钢环的水润滑机理分析

对水润滑橡胶轴承在完全水润滑条件下的标准实验模型进行了弹流理论建模,应用多重网格技术对理论模型进行了数值计算和结果分析。结果表明:完全水润滑条件下,在高速轻载时形成了弹流润滑,而在低速重载时,即使在完全水润滑条件下橡胶滑块与镀镍钢环之间也较难形成稳定的弹流润滑。计算结果与实验结果基本一致。     

基于Pro/E的斜齿轮三维造型技术研究

介绍在Pro/E环境下实现斜齿轮造型的通用方法--扫描成型法.该方法应用Pro/E生成端面和法面齿廓线,并沿螺旋线扫描生成斜齿轮轮廓面.通过裁剪扫描体得到单个轮齿,然后通过阵列生成全部轮齿,最后利用PROGRAM实现斜齿轮自动化设计.     

影响弹流润滑偏离经典弹流润滑理论的三种因素

详述了在高速、重载和大滑滚比下，影响弹流润滑偏离经典弹流润滑理论的三个因素，即温度效应，润滑剂的非牛顿效应和表面粗糙度效应，并指出了今后的发展方向。     

基于滚道表面粗糙的高速圆柱滚子轴承弹流的理论分析

建立了基于表面粗糙的高速圆柱滚子轴承非稳态时变热弹流分析模型,分析了轴承滚道与滚动体接触表面粗糙度幅值大小及其方向对轴承弹流性能的影响。理论分析表明：轴承接触表面粗糙纹理方向、粗糙度幅值及其粗糙度波长对高速圆柱滚子轴承的弹流特性具有显著的影响;合理选择轴承接触表面粗糙度幅值、波长及纹理方向,可以有效改善高速圆柱滚子轴承的弹流特性。     

The Influence of Surface Roughness on the Lubrication Properties of Adsorbing and Non-Adsorbing Biopolymers

The lubrication properties of a glycoprotein (pig gastric mucin or PGM) and a high-molecular-weight hydrosoluble polymer (guar gum) have been studied. Friction has been measured over a wide range of entrainment speeds and Stribeck curves have been obtained spanning the boundary, mixed and hydrodynamic lubrication regimes. The adsorption properties of the polymers have also been assessed using evanescent wave spectroscopy. The results show that the polymer that adsorbs on solid surfaces is able to reduce friction in the boundary lubrication regime (PGM). Guar, which does not adsorb on surfaces, shows high friction in boundary lubrication but still promotes the onset of mixed lubrication; thus friction starts to fall from its boundary values at low speeds. These results can be explained in classical terms of entrainment of polymer solution into the thin film conjunction and associated shear thinning in the contact inlet. With roughened surfaces, a shift of the Stribeck curves towards high speed is observed.     

斜齿圆柱齿轮啮合刚度的一种简化计算

从直齿轮和斜齿轮数学模型的相似性方面入手,提出一种在已知直齿轮啮合刚度的基础上,确定相应斜齿轮啮合刚度的方法。     

Anomalous Low Friction Under Boundary Lubrication of Steel Surfaces by Polyols

We present here anomalous low friction obtained with highly polished steel on steel hard contact lubricated by glycerol under severe mixed and boundary regimes (λ ratio below 1). We investigated the effects of contact pressure, sliding speed, and temperature on friction coefficient and electrical contact resistance. The mechanism of low friction (typically below 0.02) is thought to have two origins: first a contribution of an ultrathin EHL film of glycerol providing easy shear under pressure, second the chemical degradation of glycerol inside the contact when more severe conditions are attained, generating a nanometer-thick film containing shear-induced water molecules. This new mechanism, called “H-bond Network model”, is completely different from the well-accepted “Monolayer” model working with polar molecules containing long aliphatic chains. Moreover, we show outstanding superlubricity (friction coefficient below 0.01) of steel surfaces directly lubricated by a solution of myo-inositol (also called vitamin Bh) in glycerol at ambient temperature (25 °C) and high contact pressure (0.8 GPa) in the absence of any long chain polar molecules. Mechanism is still unknown but could be associated with friction-induced dissociation of inositol and H-bond interactions network of water-like species with steel surface.     

蜗杆传动的润滑分析

通过对蜗杆传动的润滑、效率与表面微峰接触载荷的分析,提出了一个新的蜗杆传动胶合失效判断因子,它综合考虑了润滑油膜破裂、微峰塑性变形与摩擦发热三种因素;基于Chittenden等的油膜厚度公式分析了蜗杆传动的油膜厚度,理论计算结果表明这一新的胶合因子在蜗杆传动润滑分析中具有指导意义,但对新的胶合因子仍需进一步实验验证。     

Friction Reduction in Mixed Lubrication

Minimization of frictional losses in the drivetrain of heavy-duty vehicles is important from both consumer satisfaction and environmental perspectives. Approaches to friction reduction in these components can be evaluated using simulation-based investigations. However, nearly all drivetrain components operate in the mixed lubrication regime which is difficult to model because both hydrodynamic lubrication and surface contact are significant and therefore, the total friction consists of hydrodynamic friction due to lubricant shearing and boundary film friction at asperity contact locations. Recent advances in simulation methods for mixed elastohydrodynamic lubrication (EHL) have enabled improved virtual design tools, such as those developed by Zhu and Hu and further improved by Liu et al. Here, these simulation tools are used to evaluate friction reduction and predict the effects on a mixed EHL interface under severe operating conditions. Three practical means of friction reduction are discussed based on the experimentally validated mixed lubrication friction model and its predictions made for representative, sample cases.     

水润滑塑料合金轴承的弹流润滑分析

建立水润滑塑料合金轴承的数学模型,对水润滑条件下塑料合金轴承的弹流润滑问题进行数值模拟,讨论转速和载荷对水润滑膜压力和膜厚的影响。结果表明:在水润滑条件下,转速对水润滑膜的压力影响不明显,而膜厚及最小膜厚随转速的增大而明显增大;随载荷的增大,压力峰值有明显增大,而在入口区压力随载荷增大而减小,膜厚及最小膜厚随载荷增大而减小。     

乏油工况下斜齿轮热弹流润滑特性研究*

建立斜齿轮的乏油热弹流润滑模型,并讨论供油量、转速和齿面粗糙度对润滑性能的影响。结果表明:乏油工况下增大入口区供油量,润滑区的膜厚增大而摩擦因数、温升和次表面应力幅值降低;随着供油量增大,乏油润滑特性逐步趋于全膜润滑状态下特性;随着转速升高,润滑膜厚增大但幅度有限,相应温度场增大和次表面应力场增大;齿面粗糙度会使油膜压力出现剧烈的波动,在油膜压力峰位置的次表面会出现应力集中。     

润滑理论中卷汲速度的概念辨异及结果分析

指出有关齿轮润滑的文献中用两轮牵连速度的合速度作为卷汲速度,在概念上隐藏着错误,而据此概念导出的结果只在某些特殊条件下才是正确的。提出卷汲速度应定义为两表面相对于收敛棒相对速度的合速度这一概念,给出了有关公式,讨论了影响卷汲速度的因素和润滑弱点存在的条件。     

时变性对圆柱齿轮弹流润滑的影响

基于有限长线接触弹流理论，分析了时变性对圆柱直齿轮弹流润滑的影响，研究了动力粘度、卷吸速度与曲率半径的变化对弹性流体动力润滑油膜厚度的影响，探讨了其中的规律，得到了时变条件下齿轮弹流润滑的基本规律，提出了改进齿轮润滑效果的措施。     

有限长线接触斜齿轮副瞬态弹流润滑研究

采用统一Reynolds方程建立斜齿轮有限长线接触瞬态弹流润滑模型,研究瞬态效应与表面粗糙度对润滑特性的影响。结果表明:考虑瞬态效应的斜齿轮副润滑参数在单齿啮合区域剧烈变化,其接触区域膜厚较低且摩擦因数较大,容易处于混合润滑状态;在单齿啮合区域,瞬态解有效承载区变窄且二次压力峰明显增大。当前算例表明全膜弹流润滑状态下,粗糙度对斜齿轮副的瞬态弹流润滑特性影响较少,仅在双齿啮合区域考虑粗糙度的平均膜厚较大,且对应接触压力与膜厚围绕光滑解波动。