无油压缩机气缸-活塞环摩擦磨损特性试验研究

为探究无油压缩机气缸与填充PTFE活塞环的配对摩擦磨损特性，在Rtec-instruments多功能摩擦磨损试验机上对不同表面处理工艺的不锈钢、铝合金气缸材料与不同配方填充PTFE活塞环材料进行配对摩擦磨损试验。通过对摩擦系数时序曲线的变化规律、摩擦副磨损前后表面形貌特征及填充PTFE磨损量的研究，选择最优摩擦学性能的气缸-活塞环的配对摩擦副。结果表明，铝合金与不锈钢表面进行PCVD处理相对于常规阳极氧化和镀铬更易在摩擦表面形成自润滑转移膜；PTFE填充碳纤维时，其摩擦系数时序曲线随磨合过程降低且较为稳定；考虑摩擦系数与相对磨损量，提出了综合摩擦系数作为配对摩擦副选材的依据；PCVD处理的铝合金材料与填充主材碳纤维PTFE的综合摩擦系数为6.1×10^-5，具有较低的综合摩擦系数、稳定的摩擦系数时序曲线和良好的表面形貌特征，可作为气缸-活塞环的配对摩擦副的优选方案之一。     

汽车制动器摩擦副材料选择性配对问题的研究

汽车制动器摩擦副材料的配对一直是被忽视的一个问题。本文对汽车制动器广泛使用的对偶材质和新研制的四种对偶材质分别与石棉、粉末冶金和半金属摩擦片配对进行了试验研究,证实对偶材质不仅影响它本身的摩擦磨损性能,而且显著地影响摩擦片的摩擦磨损性能,理想的对偶能提高双方的耐磨性和增大摩擦系数,同时改善热衰退性能,使摩擦特性更加稳定。摩擦片对其对偶具有选择性配对的特性,对三种摩擦片的对偶研制出较好的配对材料。     

水润滑条件下等离子陶瓷涂层的磨损机理研究

针对纯水液压柱塞泵工况，研究了滴水润滑条件下五种等离子陶瓷涂层和整体烧结氧化铝配对的摩擦磨损情况，考察了摩擦系数和试环的磨损量随时间的变化规律，利用SEM、X射线能量色散谱仪等设备观察和分析了磨损表面的形貌和化学元素组成。     

孔板阀滑阀自锁装置球/盘配对副耐磨性能实验研究

为优选孔板阀滑阀自锁装置配对副耐磨性能影响因素,选取不同球/盘配对副材料、盘粗糙度和润滑条件开展正交滚滑摩擦试验。敏感性分析结果表明,试验优化参数为:盘材料440C,球材料440C,盘粗糙度R_a = 0.4 μm,润滑条件脂润滑。优选参数配对副在试验后运行良好,球/盘表面形貌无明显磨损,摩擦系数无突变,说明优选参数的抗磨性能满足使用寿命需求。     

钢/铜混杂纤维增强摩擦材料摩擦学性能研究

以丁腈橡胶改性酚醛树脂为树脂基体,钢纤维-铜纤维混杂纤维作为变量,经热压烧结制备一种摩擦材料,在干摩擦条件下通过摩擦磨损试验机考察其摩擦学性能,并用扫描电镜(SEM)对摩擦材料的表面磨损微观形貌进行观察分析,以研究钢/铜纤维混杂对摩擦材料摩擦学性能的影响。实验表明:随滑动速率的增大,材料的摩擦系数、磨损率呈现减小趋势;轻载时,材料的摩擦系数、磨损率较高,重载时,摩擦系数、磨损率则相对较低。摩擦过程中,添加钢/铜混杂纤维的材料磨损形式为塑性变形和磨粒磨损;未添加混杂纤维的材料磨损形式主要为粘着磨损。由此可见,钢/铜混杂纤维的加入可以有效提高材料的摩擦系数,降低其磨损率,明显改善材料的摩擦学性能。     

屏蔽泵石墨轴承材料的强度和耐磨性研究

对屏蔽泵的石墨轴承材料的强度、磨损性和摩擦系数进行了实验研究。在DWD-3020电子万能试验机上对普通石墨和浸润树脂石墨材料的弹性模量进行了测定，同时确定了材料的拉伸和压缩强度极限。在Falex摩擦磨损机上对材料进行了磨损试验，得到了转速和载荷对这两种材料磨损的影响，并利用CSM950扫描电子显微镜对其摩擦表面作了形貌分析。     

动力卡盘附件的材料磨损性能研究

以K59250型动力卡盘附件的原材料为对象,采用销盘摩擦配副对动力卡盘附件的材料进行摩擦磨损试验,探讨滑座和楔心套的材料磨损的影响因素.结果表明,随着摩擦配副工作行程的增加,滑座和楔心套配副的摩擦系数无显著变化;滑动速度、盘体的热处理工艺和滑动形式对滑座和楔心套的磨损性能有较大影响.在连续滑动下,与高频淬火盘体配对低速滑座的磨损量低于与调质处理盘体配对高速楔心套的磨损量;在间歇滑动下,滑座和楔心套在一年内磨损量极低,接近于零磨损.     

不同摩擦副在MM3000型试验机和TM-3型台架机上的对比试验研究

在MM3000型试验机和TM-3型台架机上,在0.40-0.50MP制动压力、80-200km/h制动速度下,对比了不同摩擦副干态工况条件的平均摩擦系数与磨损量。结果表明:克诺尔铜基摩擦材料配对钢制动盘的摩擦副在MM3000试验机上的摩擦系数高于在TM-3台架机上的摩擦系数。相反,克诺尔铜基摩擦材料和金属陶瓷摩擦材料配对碳陶制动盘的摩擦副在MM3000试验机上的摩擦系数都低于在TM-3台架机上的摩擦系数。另外,不论是MM3000试验机,还是TM-3台架机,克诺尔铜基摩擦材料配对碳陶制动盘时的磨损量最大,克诺尔铜基摩擦材料配对钢制动盘时的磨损量居中,金属陶瓷摩擦材料配对碳陶制动盘时的磨损量最小。     

层状WC/TiC陶瓷刀具材料与轴承钢的摩擦磨损性能

采用雾化-喷覆液膜-干燥工艺及真空热压烧结技术制备了层状WC/TiC陶瓷刀具材料,在干摩擦条件,将其与GCr15轴承钢进行了摩擦磨损实验,研究了不同滑动速度和不同载荷对其摩擦系数和磨损量的影响规律,并对其摩擦磨损后的表面形貌进行了分析。结果表明:在相同载荷条件下,材料的摩擦系数和磨损量均随滑动速度的升高而减小,当滑动速度为12m/min时,材料的摩擦系数和磨损量最小,其值分别为0.276和0.68×10^-3mm^3;在相同滑动速度条件下,材料的摩擦系数和磨损量也均随载荷的增大而减小,载荷为120N时,材料的摩擦系数和磨损量最小,其值分别为0.157和0.58×10^-3mm^3;材料的磨损机理主要是粘着磨损和磨粒磨损。     

缺套—活塞环材料在往复滑动中摩擦系数的试验研究

为了研究机车柴油机缸套活塞环材料的摩擦学性能，我们设计并制造了一台往复式摩擦磨损试验机。该试验机可在一定范围内实行载荷、速度、润滑量的单因素控制，并可同时定性和定量的显示运动中的摩擦力大小。我们利用该试验机对美国ＧＥ公司采用的软氮化铸铁缸套－表面镀铬铸铁活塞环材料进行了摩擦学性能的试验研究，得出了该配对副在往复滑动中摩擦系数随载荷和速度变化的关系曲线。     

镶嵌式直线深槽流体动压型机械密封性能研究

以端面开有直线深槽的镶嵌式密封结构为分析对象,建立了密封环与润滑液膜间的流固力耦合模型,采用有限差分和有限元法分别求解润滑方程和变形方程,研究了密封压力和转速对润滑液膜的影响规律,分析了操作参数对密封性能的影响。研究结果表明,由于直线深槽作用,密封端面形成了一定的波度和锥度,波度随着压力的升高而变大,但锥度增幅不是很明显,而对波度的变化影响较大。密封端面的波度和锥度随转速的变化不大。密封压力升高时,密封端面间的泄漏率增大,摩擦系数相应地减小;密封转速增大时,密封端面间的泄漏率变化不是很明显,而摩擦系数相应的增大。     

超高速涡轮泵机械密封热弹流润滑特性研究

以超高速涡轮泵用机械密封为研究对象,针对超高速工况下密封界面多场耦合变形行为和热弹流润滑特性不明等问题,建立密封动静环和润滑液膜的耦合数学模型,研究不同转速和密封压力下的密封界面润滑特性和端面变形行为,分析相应的密封性能变化规律。结果表明：超高速工况下密封端面产生沿泄漏方向收敛的液膜间隙,密封动环的高温热变形是主因;随密封压力的增大,液膜间隙的收敛角减小,最大膜厚和泄漏率增大,端面温升明显减小;随着转速的增大,液膜间隙的收敛角、端面温升和泄漏率增大,摩擦扭矩减小。建立的流固热力耦合模型可为超高速涡轮泵用机械密封端面的优化设计提供理论指导。     

表面纹理对旋转轴唇形密封性能的影响

在唇形密封圈唇端两侧设置整齐排列的圆形、正方形和等边三角形3种凹坑纹理形式,建立具有表面纹理的旋转轴唇形密封圈的有限元模型,并分析获得密封面静态接触压力和变形系数矩阵;建立综合考虑混合润滑和空化及表面纹理形状影响、耦合流体场和弹性变形场的唇形密封圈接触区域密封数值计算模型,并建立集有限元分析与数值计算于一体的唇形密封圈接触区域泵吸率计算流程。计算结果表明:表面纹理结构使得密封唇与轴的接触压力相对下降,且有效地增大唇形密封圈的膜厚并改善泵吸效果;相较于圆形和正方形纹理,三角形纹理对唇形密封圈的改善效果最佳。但表面纹理结构在改善密封区域润滑状态的同时,也造成密封动态压力的波动,且三角形纹理的影响更显著。     

Fluid-solid interaction model for hydraulic reciprocating O-ring seals

Elastohydrodynamic lubrication characteristics of hydraulic reciprocating seals have significant effects on sealing and tribology performances of hydraulic actuators,especially in high parameter hydraulic systems.Only elastic deformations of hydraulic reciprocating seals were discussed,and hydrodynamic effects were neglected in many studies.The physical process of the fluid-solid interaction effect did not be clearly presented in the existing fluid-solid interaction models for hydraulic reciprocating O-ring seals,and few of these models had been simultaneously validated through experiments.By exploring the physical process of the fluid-solid interaction effect of the hydraulic reciprocating O-ring seal,a numerical fluid-solid interaction model consisting of fluid lubrication,contact mechanics,asperity contact and elastic deformation analyses is constructed with an iterative procedure.With the SRV friction and wear tester,the experiments are performed to investigate the elastohydrodynamic lubrication characteristics of the O-ring seal.The regularity of the friction coefficient varying with the speed of reciprocating motion is obtained in the mixed lubrication condition.The experimental result is used to validate the fluid-solid interaction model.Based on the model,The elastohydrodynamic lubrication characteristics of the hydraulic reciprocating O-ring seal are presented respectively in the dry friction,mixed lubrication and full film lubrication conditions,including of the contact pressure,film thickness,friction coefficient,liquid film pressure and viscous shear stress in the sealing zone.The proposed numerical fluid-solid interaction model can be effectively used to analyze the operation characteristics of the hydraulic reciprocating O-ring seal,and can also be widely used to study other hydraulic reciprocating seals.     

Thermoelastohydrodynamic Gas Lubrication of Spiral-Groove Face Seals: Modeling and Analysis of Vapor Condensation

Vapor condensation in gas lubrication of high-pressure spiral-groove face seals is analyzed in this article. A mathematical model of vapor condensation elastohydrodynamic lubrication (EHL) is developed taking into account gas humidity and thermoelastic deformation of seal rings. Vapor condensation is numerically predicted at high speed and pressure. It is found that vapor condensation usually occurs in the sealing dam region, where the lubrication state changes from gas lubrication to gas–liquid lubrication. The vapor condensation rate increases with an increase in humidity and seal pressure. Under high-pressure conditions, seal clearance has a significant influence on the vapor condensing rate but the rotational speed does not.     

The effect of tapered edges on lubrication regimes in surface-textured elastomer seals

The paper focuses on modeling a hydraulic elastomer seal cross-section for improving the effect of surface texturing in Soft Elasto Hydrodynamic Lubrication. The model consists of textured elastomer seal having a cross section combined of composite tapered and flat land, sliding relative to a rigid smooth counterpart in the presence of viscous lubricant. The hydrodynamic lubrication and the elasticity problems are solved simultaneously. A parametric analysis is performed to obtain the optimum surface texturing parameters and the improved cross section. Ranges of different possible lubrication regimes are also discussed.     

The effect of tapered edges on lubrication regimes in surface-textured elastomer seals

The paper focuses on modeling a hydraulic elastomer seal cross-section for improving the effect of surface texturing in Soft Elasto Hydrodynamic Lubrication. The model consists of textured elastomer seal having a cross section combined of composite tapered and flat land, sliding relative to a rigid smooth counterpart in the presence of viscous lubricant. The hydrodynamic lubrication and the elasticity problems are solved simultaneously. A parametric analysis is performed to obtain the optimum surface texturing parameters and the improved cross section. Ranges of different possible lubrication regimes are also discussed.     

A Mixed Thermoelastohydrodynamic Lubrication Analysis of Mechanical Face Seals by a Multiscale Approach

This article presents an improvement to a previous multiscale approach used to model the mixed lubrication regime in a mechanical face seal. The physical mechanisms considered by the improved model are the surface roughness effects on the fluid film lubrication, the thermal deformations, and the heat transfer in the seal rings due to viscous and dry friction. The developed numerical model determines the pressure distribution by taking into account the effect of cavitation and contact asperity between the surfaces. Heat dissipation, heat transfer, and deformations are computed from the heat dissipated at the seal interface by a finite element technique. The multiscale model significantly reduces computation time while maintaining the accuracy of the results. The results obtained through a parametric study show that there are different operating zones where the lubricating film thickness is controlled by the roughness height or by the thermal effect.     

往复式低温制冷机的气体润滑

对低温机械应用气体润滑技术的情况进行了综述及讨论,重点针对往复式低温机械活塞密封的气体润滑,分析了低温活塞膨胀机气体润滑活塞密封的结构特点、性能及使用,介绍了低温制冷机迷宫密封的应用概况,反映了微型制冷机中最新研发气体轴承活塞的结构特点及动态.     

双向旋转树型槽密封端面气膜动压特性

基于气体润滑理论,建立了双向旋转树型槽干式气体端面密封的数学分析模型,对比了双向旋转树型槽与螺旋槽密封端面的压力分布,讨论了树型槽的动压开启特性,以及操作参数对密封特性参数的影响规律。结果表明,双向旋转树型槽干气密封不仅能够实现双向旋转,而且具有较好的动压效应。双向旋转树型槽干气密封的动压效应受压缩数、密封压力等操作参数及端面间气膜厚度的影响显著,压缩数增加,动压开启能力增强;密封压力增加,动压开启能力降低。