滚动转子式压缩机泵体输入功率的计算

在确立的假设条件下,对叶片、滚套、曲轴等滚动转子式压缩机各关键运动部件进行了动力学分析,得出了压缩机泵体的输入功率表达式。为压缩机设计提供了理论基础。     

The Effectiveness of Boundary and Hydrodynamic Lubrication when Cold Rolling Aluminum Metal

How hydrodynamic and boundary lubrication affect a lubricant's film strength when cold rolling aluminum was studied using a laboratory mill. The film strength of the lubricant was determined by increasing the amount of reduction until a rapid rise in load and temperature produced a herringbone pattern on the surface of the metal. The hydrodynamic lubrication was changed by increasing the viscosity of the base oil or by increasing the rolling speed. The boundary lubrication was changed by increasing the concentration of the additives or by changing the type of additives. The results of the test showed that either increasing the amount of the hydrodynamic lubrication or increasing the amount of the boundary lubrication were effective ways to increase the film strength of the lubricant; however, the effectiveness of each decreased as the calculated film thickness of the lubricant increased. It is proposed that this can be explained by the decrease in contact area between the work roll asperities and the surface of the sheet as the thickness of the lubricant film increases.     

采用油膜密封的转子压缩机内间隙泄漏研究

在转子压缩机内转子和气缸之间采用间隙配合，其泄漏通道通过油膜来密封的。考虑到转子径向间隙的动态变化，利用润滑油流动模型来计算它的制冷剂泄漏量，通过保持其它配合间隙不变，只改变转子径向间隙的性能试验来检验油膜的密封效果。结果表明，合理地设计转子径向配合的间隙值，可以有效地降低转子压缩机的泄漏损失。     

Analytical Solution of Piston Ring Lubrication Using Mass Conserving Cavitation Algorithm

A novel analytical approach for piston ring lubrication solution is presented by taking proper account of mass conservation in the cavitated region (JFO boundary conditions). A system of five nonlinear equations is employed to calculate such parameters as oil film thickness, frictional force, power loss, and oil flow rate. For an enclosed cavitation pattern in piston-ring assembly it was found, that JFO boundary conditions give much better accounting of the estimation of friction force, power loss and flow rate. To show the effectiveness of the undertaken approach, the widely accepted Jeng's approach (Jeng, 1992a) was selected, in which the pressure contribution from the cavitated and the second full film regions, as well as the trailing edge pressure, are ignored.     

Analytical Solution of Piston Ring Lubrication Using Mass Conserving Cavitation Algorithm

A novel analytical approach for piston ring lubrication solution is presented by taking proper account of mass conservation in the cavitated region (JFO boundary conditions). A system of five nonlinear equations is employed to calculate such parameters as oil film thickness, frictional force, power loss, and oil flow rate. For an enclosed cavitation pattern in piston-ring assembly it was found, that JFO boundary conditions give much better accounting of the estimation of friction force, power loss and flow rate. To show the effectiveness of the undertaken approach, the widely accepted Jeng's approach (Jeng, 1992a) was selected, in which the pressure contribution from the cavitated and the second full film regions, as well as the trailing edge pressure, are ignored.     

聚酰胺用于压缩机活塞环的试验研究

通过对聚酰胺等材质的摩擦特性试验分析，提出了在一定的条件下，采用填充聚酰胺材质制作压缩机活塞环，可提高其使用寿命和减少摩擦功率的可行方案，并结合应用实例进行了分析。     

发动机活塞环润滑状况分析

活塞环是发动机活塞连杆组的重要部件之一，活塞环工作状况的好坏对发动机的特性有很大影响，本文基于流体动压润滑理论，着重分析活塞环的润滑状况以及影响其润滑状况的因素。     

活塞环的润滑与应力分析

以边界润滑模型分析活塞环－气缸的润滑、摩擦过程,提出活塞环的粘着磨损的模型：计算活塞环的应力分布。活塞环内的应力场的分析结果表明：层状剥落的粘着磨损是活塞环磨损的主要形式。本文提出了对数母线的桶面压缩环设计,探讨活塞环的最优化设计,提高活塞环的抗磨损能力,延长使用寿命。     

基于改进型混合膜润滑模型的金属轧制过程的数值仿真

根据 Wilson和 Chang的粗糙度补偿模型和 Von Mises均匀变形模型 ,在轧制过程中 ,一种新的混合膜润滑模型被建立。一个更精确的平均雷诺方程被用来计算液体动压力。随变形而变化的屈服应力也在模型中被考虑。并编制了程序用来计算接触面积 ,膜厚和流体动压力。该模型使用较少的假设 ,且更切合实际 ,收敛快。它能应用于较宽速度范围的轧制状态     

内燃机活塞裙部配缸间隙对裙部润滑影响的研究

本文建立的数学模型主要是结合动力学方程及缸套 -活塞裙部间的流体动力润滑方程 ,采用数值分析方法来研究活塞的二阶运动 ,并从减小活塞裙部摩擦功耗和减小活塞横向运动的角度 ,对活塞与缸套的最佳油膜间隙进行了确定 ,使得活塞裙部与缸套的间隙更为合理     

Hydrodynamic Lubrication of Surfaces with Asymmetric Microdimple

Surface texturing has been recognized as a feasible method of surface engineering to improve the lubrication properties of mechanical components. This work focuses on the hydrodynamic lubrication properties of the textured surface with asymmetric microdimples. The validity of the Reynolds equation in asymmetric microdimples is discussed based on theoretical analysis and numerical simulation. The effects of modified Reynolds number, motion directions, and parameters of the microdimple profile are investigated. The following results were obtained: Firstly, the Reynolds equation is invalid under almost all of the general conditions used in experiments and industries. Secondly, the ultimate load-carrying capacity can be taken as a new characteristic parameter to assess the lubrication property of a textured surface. Thirdly, the motion directions have a great effect on the lubrication properties. The positive motion can generate more stable load capacity under all of the modified Reynolds numbers employed, even though the load-carrying capacity is smaller than the negative motion’under larger modified Reynolds numbers. Additionally, the asymmetric microdimple can obtain larger load-carrying capacity than a symmetric rectangular microdimple and will become a potential microdimple candidate.     

A Two-Wavelength Model of Surface Flattening in Cold Metal Rolling with Mixed Lubrication

A new model of surface flattening is developed for cold metal rolling in the mixed regime. Longitudinal surface roughness is modeled by two separate wavelengths. The new model follows the asperity crushing analysis of Sutcliffe (1999) for unlubricated rolling but additionally includes a hydrodynamic model to account for the effect of the lubricant. The effect of various parameters including speed, reduction in strip thickness, roughness wavelength and lubricant properties is examined. The results show similar behavior to previous models of mixed lubrication, with a speed parameter A_s having the most influence, and confirm the results for unlubricated rolling that the short wavelength components of the surface roughness persist more than the long wavelength components. The predicted changes in roughness are in good agreement with experiments.     

Mixed Lubrication of Strip Rolling

An analytical model for strip rolling operating in the mixed regime is developed. The model combines analysis for the influence of bulk plastic deformation on the effective hardness of the strip asperities with an approach to allow for the influence of roughness on lubricant flow. An approximate correction for thermal effects is also included. The predictions of the model are compared with experimental measurements of film thickness and slip.     

Analytical Investigation on the Effect of Multigrade Oil in Piston Ring Lubrication

The use of multigrade oil in engine lubrication is being advocated to consumers to minimize viscosity-temperature effect. However, its effect on piston ring-liner contact has not been fully ascertained. In this work, an attempt has been made to evaluate the friction behavior of multigrade oil in piston ring lubrication. The theoretical model developed by the authors predicts thinner oil films as a result of introduction of multigrade oil in the hydrodynamic zone and a larger piston travel distance near the TDC region in the compression-power stroke cycle without any appreciable film thickness. The multigrade oils are known to offer elasticity, and this is also considered in the analysis to evaluate film thickness.     

活塞环-缸套二维润滑特性的研究

基于二维平均流量模型和微凸体接触模型，研究了活塞环的二维润滑特性，并考虑了活塞系统偏摆、润滑油粘度变化及表面粗糙度等因素的影响。通过计算获得了活塞环－缸套间油膜厚度的二维分布。结果表明，油膜厚度沿周向是不均匀的。本文还对活塞环开口位置及偏摆的影响做了定量的分析。     

边界润滑下滑动接触表面破坏行为的数值分析

针对边界润滑条件，本文用有限元方法分析了当滚动接触处于准静态情况下，接触表面覆盖有水边界膜而且接触区内存在微观突起和微观裂纹的接触状态，阐明了液体对表面微观裂纹的影响。分析结果表明液体的存在改变了接触区的受力状态，表面裂纹造成接触区应力分布的不连续；有水存在时，最高接触压力降低并且分布均匀，但造成应力强度因子K1增大，促进裂纹的扩展。     

滑片式压缩机摩擦力密封结构的改进设计

本针对传统滑片式压缩机隔离叶片与缸内孔壁面之间,以及隔离叶片与两侧密封端盖之间存在有较大摩擦和泄漏的毛病,采用旋转缸筒、嵌固隔离叶片和随动端盖的新型结构方案,有效地解决了这些问题。     

活塞压缩机平衡计算和运动仿真

以微型超高压活塞式空气压缩机为研究对象,首先利用UG建模模块对微型超高压活塞式空气压缩机进行三维建模和虚拟装配,并进行相关的干涉检查,然后应用UG运动仿真模块对微型超高压活塞式空气压缩机进行平衡计算和运动学仿真,将其运动参数输出,该分析的意义在于不仅能够很大程度的提高计算精度和设计效率,将繁琐的计算、试验简便化,而且还能得出准确的运动学参数曲线,为研究压缩机的性能提供了一种新的方法,对压缩机的设计、改造有一定的参考价值。     

铜带轧制变形区摩擦润滑状态研究

观察分析了轧制变形区形貌特征,研究了不同方向粗糙度对轧制润滑的影响。在轧制变形区并存边界润滑和流体动压润滑;轧辊与轧制的塑性挤压边界接触是获得高光亮表面的必要条件。轧后轧件表面粗糙度Ｒａ和丰满度Ｋ趋向于满足一定润滑条件的最佳值。     

Feasibility Study of Hydrodynamic Lubrication in Supporting of Rotating Elements of Galvanizing Hardware Submerged in Molten Zinc

Severe wear of sink roll supports in continuous galvanizing lines has been a cause for concern for some years. This wear, which affects the quality of the coating and downtime costs, is a result of a corrosive environment and highly loaded surface contact.

This paper presents results from a feasibility study to use journal bearings lubricated with molten zinc to separate the interacting surfaces. Analytical and experimental investigations were aimed at identifying the load capacity of sink roll bearings when operating in the hydrodynamic regime, as well as the effect of the molten zinc bath environment on bearing performance. This environment includes chemical zinc attack and the presence of inter-metallic particles in the bath.

The study indicates that it is difficult to achieve hydrodynamic bearing operation for the entire range of operating conditions. It also shows that, when selecting materials for journal bearings support to the rotating elements submerged in molten zinc baths, possible contact of the bearing surfaces as well as chemical inertness and resistance to the hard intermetallic particles do need to be addressed.