高性能滑动电接触实验机的设计与研制

为了对电力机车受电弓滑板与接触网导线的载流磨耗特性进行实验研究,分析了磨耗稳定态出现的规律,制作了一台高性能滑动电接触实验机。实验机实现了电气化铁路受电弓滑板与接触网导线之间的实际载流磨耗运行环境的模拟,在不同的配对关系和实验条件下,通过下位机检测出所有待测量参数并与上位机进行串行通信。上位机对采集数据进行分类保存,并对测量结果进行分析处理,生成所需各种波形曲线。结果表明,实验机结构设计合理、参数测量准确,能够模拟多种实际运行环境。     

多功能摩擦传动实验机研制与实验研究

针对目前摩擦学实验台接触形式单一、实验范围狭窄及边界条件不统一等问题,设计了一种新型多功能摩擦传动实验机。通过采用两个可在径向载荷作用下作可控相对运动的独立电机驱动主轴,实现多种接触形式的试件装卡,从而在高度统一的边界条件下进行摩擦磨损、传动性能测试及疲劳寿命检测等多种实验。实验结果表明:该实验机可为滑滚接触条件下典型零部件的摩擦与润滑机理研究、传动系统性能检测与动力学分析等提供可靠的实验平台,满足设计要求。     

基于机器学习的受电弓滑板磨耗预测模型

为研究受电弓滑板摩擦磨损性能的影响因素,根据磨耗演变规律对磨耗进行预测,采用置信区间估计法,确定滑板历史磨耗数据统计值上下界和基准训练集,建立机器学习的线性回归模型,以梯度下降法使代价函数趋于最小对模型进行优化。通过对该模型及方法的应用,预测滑板剩余厚度限集,并通过与某型车实测磨耗数据比较。结果表明：预测数据与实测基本一致,可为有效减少动车段对受电弓滑板维护工作量提供依据。     

基于虚拟仪器的尼龙轴承摩擦磨损实验机设计

介绍了所设计的基于虚拟仪器技术的水润滑轴承摩擦磨损实验机。该系统除了具有传统水润滑轴承试验机的功能外,在实验机的测量和控制过程中还采用了“虚拟仪器”技术。该实验机已经应用于尼龙轴承极限值的检测中,并且取得了良好的效果。     

双滑板受电弓磨耗的超声波检测方法

超声波检测滑板磨耗是以DSP TMS320LF2407A控制超声波传感器测量受电弓滑板的磨耗值,然后将获取的数据传输到检测主机.现在大部分电力机车都采用双滑板受电弓,因此超声波检测应能够检测前后两个滑板.在超声波检测单滑板受电弓的基础上,主要通过修改下位机的控制程序便可实现双滑板受电弓滑板的磨耗检测.     

多功能摩擦磨损实验机的研制

介绍了用于超硬材料工具性能参数检测分析的多功能摩擦磨损实验机的研制,该实验机通过分析金刚石工具在不同转速、压力、转矩下的磨损量,进行其工艺、配方的优化,为揭示超硬材料制品的工作机理和失效原因提供科学的实验数据,有助于开展更深层次的研究。     

摩擦实验机数据采集系统的研制与实验

基于LabVIEW图形化编程语言设计了多用途摩擦传动实验机实时信号数据采集系统,实现参数设置界面和结果曲线显示界面,包括转速、扭矩、振动和温度等信号的采集和同步显示,摩擦系数、vonMises应力、接触压力和油膜厚度等参数的计算和显示,后台以一定格式实时存储数据。通过试验验证该测试系统各项功能运行良好,能够满足采集基础信号需求,并有效解决摩擦学测试中缺少应力和润滑状态监测的现状,对摩擦学实验数据采集具有较广泛的适应性和应用价值。     

基于摩擦温升效应的地铁车轮磨耗特性研究

踏面制动引起车轮温度急剧上升,影响车轮材料性能和轮轨接触状态,加剧车轮磨耗。基于Archard磨耗模型,建立一个考虑摩擦温升效应的地铁车轮磨耗预测模型。模型中根据车轮材料属性与温度之间的关系,考虑摩擦温升对接触斑大小、黏滑区划分和磨耗深度的影响,可实现对高温下的车轮磨耗特性的研究。相对以往的车轮磨耗预测模型,该模型能反映温度对磨耗影响的物理本质,适合研究轮轨接触界面有较大温度(如踏面制动)时的车轮磨耗演化机理。用所建立的车轮磨耗数值预测模型,计算对比不同温度下的轮轨接触状态和车轮磨耗深度。结果表明,轮轨接触斑和滑动区面积随温度的升高而增加;温度升高使接触斑单元磨耗深度增加,当踏面温度从常温25℃增加到最高温度300℃时,最大磨耗深度0.4 nm,增幅为28.4%;车轮转动一圈后,其径向磨耗深度也随温度的升高而明显增加,最大径向磨耗深度15 nm,增幅为28.2%,同时,车轮横向位置的磨耗范围增加5.8%,为踏面制动形式的地铁车轮磨耗预测研究提供更加准确的理论模型。     

基于OpenGL的受电弓磨耗检测系统图像化设计

采用超声波传感器检测受电弓滑板磨耗能实现在线检测.该检测系统以DSP TMS320LF2407A控制超声波传感器测量受电弓滑板的磨耗值,然后将获取的数据传输到检测主机.为了能从任意角度观察磨耗曲线图形,在屏幕模式下通过简单的鼠标拖动实现对图形的移动、缩放和自由旋转.     

地铁刚性弓网系统接触线磨损特性试验研究

为研究地铁刚性接触网系统接触线磨损的规律,以地铁刚性接触网系统常用的浸金属碳滑板/铜银合金接触线作为摩擦副,通过模拟地铁弓网系统运行参数,使用载流摩擦磨损试验机研究有、无电火花放电情况下,浸金属碳滑板与铜银合金接触线直流电滑动过程中磨损量、摩擦因数、载流效率随滑动距离的变化。试验结果表明：电火花放电会使得接触线与浸金属碳滑板磨损量显著上升,出现电火花放电时摩擦因数较小,弓网系统载流效率会明显降低同时出现大幅波动。试验后对碳滑板和接触线表面形貌的观察可知：电火花放电会使得浸金属碳滑板表面烧蚀坑数量和尺寸大小增加,同时会出现滑板材料大面积剥落和表面裂纹增多的问题,接触线表面形貌变得更加粗糙。     

Thermal wear and electrical sliding wear behaviors of the polyimide modified polymer-matrix pantograph contact strip

In the present study, the polyimide resin (PI)/cashew-modified resin (YM) polymer-matrix pantograph contact strip (PMPCS) was prepared by using hot repressing, hydro-solidification and dipping treatment processes. The thermal properties of cured resins were studied by thermogravimetry analyzer and differential scanning calorimetry. The thermal wear and electrical sliding wear behaviors of PMPCS against copper were evaluated by a ring block wear tester at elevated temperature under dry sliding conditions and a wear tester which simulated the train motion under laboratory conditions, respectively. Worn surfaces and wear debris of PMPCS were analyzed by scanning electron microscopy and energy dispersive spectrometer, and the wear mechanism was discussed. It has been found that the thermal stability of the PI/YM is superior to that of the YM under the same testing conditions. The results also showed that PI/YM-PMPCS had superior wear resistance than that of YM-PMPCS at elevated temperature and with electrical current. At elevated temperature, the wear mechanism of tribological pair evolved from adhesive wear to oxidative wear with mild delamination wear. Arc erosion wear, oxidative wear, and adhesive wear were the dominant mechanisms of tribological pair during the electrical wearing process.     

高速电气化铁路弓/网系统的摩擦磨损研究进展

概述了高速电气化铁路弓/网系统接触线与滑板材料的研究与应用现状,分析了其摩擦磨损过程,综述了国内外对弓/网摩擦副的摩擦与磨损行为及机制的研究现状,并指出了该方向研究的严重滞后性以及今后需要重点研究的方向。     

Sliding wear performance of different polyimide formulations

Sliding wear studies on different polyimide (PI) formulations against hardened, smooth steel were conducted using a pin-on-ring testing facility. Contact pressure p was varied in such a way that for three different sliding velocities v (0.6, 1.5 and 3.0 m s⁻¹) two pv levels could be maintained (1.7 and 5.0 MPa m s⁻¹). The best results were achieved with a PI formulation containing 15 wt% graphite filler and 10 wt% fluorocarbon resin having a wear factor

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. This material was also superior to newly developed high performance thermoplastics, in particular polyetheretherketone (PEEK) and thermotropic liquid crystal polymers (LCP), even when the latter contained about 20 vol.% of short glass or carbon fibre reinforcement.     

Effect of metallised carbon content of collector strip on the wear of contact wire–collector strip pair in railway systems

Among the topics related to the interaction between the contact wire of the overhead line and the collector strip, the wear that takes place at the contact interface, depending on both electrical and mechanical quantities, represents an important aspect of maintenance costs, affecting the mean lifetime of collectors, in terms of travelled kilometers (in terms of tenth of thousands), and contact line duration, in terms of years (between 15 and 40). Due to its importance in the global maintenance of both rolling stock and infrastructure, this topic deserved the attention of several regulations in the last decade. In order to investigate the effects of electro-mechanical wear on both contact wire and contact strip, a new test equipment has been designed and installed at Politecnico di Milano. A series of tests have been performed, involving different kinds of collector strip materials and contact conditions, tested at varying speeds and current intensities. This investigation concerned different collector strip configurations intended for 3kV D.C. lines. The combination of different contents of copper and metallised carbon in the collector has been found to influence the wear rate of both collector strip and contact wire. Differences in wear up to four times for the former and up to six times for the latter have been found depending on the composition of the collector. Copyright © 2006 John Wiley & Sons, Ltd.     

基于虚拟样机技术的三辊斜轧机变速器动力学仿真

渐开线齿轮在啮合传动过程中含有明显的动载荷,在齿轮精度不变时,随着转速的增大,动载荷波动幅度增大,变速器冲击振动增加;因此,不能单靠增加轧制速度来提高轧制生产率.仿真结果与理论计算比较结果表明,二者数据比较吻合,证实了虚拟样机模型构建合理,仿真正确.     

A system for wear prediction in lubricated sliding contacts

A system of analysis is developed to predict the rate of wear in sliding contacts. The essence of the approach is the proposal that the rate of wear can be predicted only in probabilistic terms. Therefore, the estimation of the probability of wear, which can be regarded as synonymous with the probability of surface asperity contacts, precedes the calculation of the wear rate. Further, recognising the fact that wear takes place within the actual area of contact, it is argued that this area consists of plastic and elastic contacts between asperities which, in turn, have different shear strengths and contribute differently to the wear process. In the case of lubricated contact, a frictional film defect represents the influence of a lubricant on the wear process. Moreover, as in this type of contact the load is supported by both lubricating film and contacting asperities, a special procedure is provided to estimate the load supported by the asperities, because it is only that part of the load which contributes to the wear. The catastrophic form of wear in lubricated contacts, that is termed ‘scuffing’, is also considered, and the probability of scuffing, under a given set of operating conditions, is estimated. The predictive system has been tested and its predictions are compared with available experimental results.     

The effect of rolling direction reversal on the wear rate and wear mechanism of pearlitic rail steel

The effect of different single and multiple rolling direction reversal (RDR) regimes on wear rate and mechanism is studied in this paper. Changes in structure deformation morphology and accumulated plastic strain are also analysed. Evidence that unidirectional rolling sliding contact can result in directional mechanical properties of the deformed layer is given. Results obtained under the test conditions used show that RDR has a beneficial effect on the wear rate of pearlitic rail steel. Multiple short RDR resulted in the lowest wear rate, less than half the unidirectional value.