钻井液中磨损颗粒在永磁场中的沉降特点

套管磨损在线监测可以通过对钻井液中磨损颗粒的收集和分析来实现.为实现钻井液中磨损颗粒的在线监测,讨论了钻井液中磨损颗粒在受到磁场作用时的沉降特点,分析了影响磨粒沉降运动的各种因素,建立了相应的运动方程,并通过数值分析进行了模拟,为钻井液中磨粒在线监测装置的磁场设计提供了依据.研究结果表明,钻井液中套管磨损磨粒有一定的运动规律,利用其运动方程进行数值计算,可以得出不同磁场条件下颗粒的速度、位移与时间之间的关系;磨粒的沉积规律的分析结果说明,磨粒、钻井液、磁场、磨粒在钻井液中的初始位置等多种因素对颗粒的沉降位置均有影响.     

基于GMR磁传感器的油液铁磁性磨粒在线监测实验研究

为实现对油液中铁磁性磨粒的在线监测,设计搭建一套在线监测装置;基于GMR磁传感器芯片可有效检测微弱磁场的特点,利用GMR磁传感器监测单个铁磨粒被磁化后的剩余磁场;采取"模拟在线"的形式,从GMR磁传感器输出的磁场信号中获取磨粒信息。通过优化装置和试验参数,研究温度、磨粒运动速度对测试系统输出结果的影响,探讨传感器的磨粒检出能力及检出结果的一致性。试验结果显示:在95℃以内的温度和5 cm/s以内的磨粒运动速度条件下,传感器的输出值基本不受影响;运动速度一定时,装置对不同粒度的磨粒输出一致性良好。试验初步表明了GMR磁传感器可用于油液铁磁性磨粒的在线监测,可有效检测出尺寸在75μm以上的铁磨粒。     

新型油液在线监测集成装置

油液在线监测是目前装备润滑磨损状态监测技术发展的重要方向,而监测仪器的开发是这一监测诊断技术研究热点。针对现代远洋船舶流动性工作特点及机械润滑磨损状态监测实时性要求,开发一套集油液磨粒监测和黏度检测的在线监测装置。装置具有结构紧凑、尺寸小、安装方便等特点。调试试验分析表明,该集成装置具有良好的稳定性,能快速实现油液磨粒含量、黏度趋势分析及超限报警。该油液在线监测装置的集成实现,为后续集成如水分、颗粒计数指标以及温度、压力等状态参数提供了研发基础。     

基于在线铁谱图像的磨损机理智能辨识

基于状态的维护(Condition based maintenance,CBM)理念为机器健康状态维护提出了实时监测的新挑战。现有研究由于缺乏在线信息获取手段,磨损状态监测逐渐成为CBM的技术瓶颈。基于特征磨粒的磨损机理判断方法已经被广泛应用在离线磨损分析中,但是在线磨损机理的表征依然是一个很大的问题。针对基于在线铁谱图像的磨损机理开展研究。为了在一副在线铁谱图像中获得分离的磨粒图像,研究磨粒在在线铁谱传感器中的沉积机理。研究结果表明,磨粒链是图像中的主要形态,这是由于先前沉积的磨粒产生的局部磁场所致。设计一种依靠自适应调节沉积时间的在线磨粒沉积方法。运用该方法可以在在线铁谱图像中获得分离的磨粒,为特征磨粒的特征辨识提供了便利。参考分析铁谱知识,提取特征磨粒的4种形态学特征(当量尺寸、长径比、形状因子和分形维数)以综合表征4种典型磨损机理,包括正常、切削、疲劳、严重滑动磨损。采用反馈式人工神经网络构建自动磨损机理辨识模型。采用离线铁谱图像样本验证所建模型,结果表明该模型可以识别在线磨粒图像中的特征磨粒。对在线磨损机理表征方法进行了有意义的探索,所得研究成果将为在线磨损状态表征提供可行方法。     

电感式磨粒传感器中铁磁质磨粒特性仿真研究

针对机械装置的在线监测传感器,模拟了铁磁质磨粒通过传感器过程中传感器线圈的磁场和感应线圈的感应电压瞬态变化特性.考虑了线圈与铁磨粒的材料、线圈匝数和激励线圈的输入电压等因素,应用Jmag Designer I0.4软件建立了传感器的二维有限元模型.仿真结果揭示了磨粒运动过程中线圈磁场与感应线圈中感应电压的变化规律,获得了感应电压与球形磨粒的直径大小的立方成正比,与磨粒运行速度成正比.研究结果对于电感式磨粒传感器的开发具有重要的指导价值.     

磨粒在磨粒探测器中的沉降运动研究

研究了在线铁谱仪磨粒探测器中的磨粒沉降运动规律,建立了磨粒在流道-磁极倾角方案下的运动模型,采用有限元法仿真了直流电磁装置的磁场分布情况,并研究了初始高度y0和磨粒直径D等参数对磨粒沉积位置的影响。结果表明,在油样流动方向和磁极之间存在倾角γ的条件下,磨粒在磨粒探测器中按照尺寸大小有序沉积,且沉积位置和油样入口端之间的距离随着初始高度y0增加而增加。     

油液在线监测系统中的磨粒识别

针对机械设备磨损状态监测要求,构建了基于显微图像分析的油液在线监测系统.根据系统的光路特点,对磨粒图像进行了基于彩色特征的转换,并通过与背景图像的差值处理来快速提取磨粒目标.基于最小二乘支持向量机设计了两类磨粒分类器,并利用粒子群优化算法对最小二乘支持向量机模型中的参数进行了优化选取.在此基础上,根据磨粒识别体系,设计了磨粒综合分类器.最后,利用铁谱分析技术对系统性能和识别效果进行了检验,结果表明,系统的识别精度达到95%以上,满足磨粒在线监测要求.     

一种基于磁力测量的油液铁磁性磨粒监测新方法

针对润滑油中铁磁性磨粒常用监测方法存在的缺点,提出采用磁力测量方法来进行油液铁磁性磨粒的总量监测。分析该方法的测量原理,设计相应的实验装置。实验结果表明,在强磁场作用下,油液中铁磁性磨粒含量与产生的磁力有很好的线性关系,用磁力法监测油液中铁磁性磨粒量是可行的。磁力法对油液中铁磁性颗粒的含量非常敏感,且不受磨粒大小的影响,是一种快速有效的油液铁磁性磨粒监测新方法。     

油液在线监测系统中磨粒识别技术研究

针对磨损状态监测要求,构建了基于显微图像分析的油液在线监测系统。根据系统光路特点,对磨粒图像进行了基于彩色特征的转换,并通过与背景图像的差值处理来快速提取磨粒目标。基于最小二乘支持向量机设计了磨粒两类分类器,并利用粒子群优化算法对最小二乘支持向量机模型中的参数进行了优化选取;根据磨粒识别体系,设计了基于最小二乘支持向量机的磨粒综合分类器。最后,利用铁谱分析技术对系统性能和识别效果进行了检验,结果表明本系统具有较高的检测精度和识别效果。     

铁谱技术中非铁磁性磨损颗粒的监测研究

在使用铁谱技术进行机械工况监测过程中，由于铁谱仪的磁场很难收集到摩擦副产生的非铁磁性磨损颗粒，往往会导致监测结果产生偏差或不正确。以钢一铜试件对磨后获得的油样为例进行铁谱对比实验，研究了磁流体在非铁磁性磨粒监测方面的应用。结果表明，在磁流体的作用下，油液中的非铁磁性磨粒将被磁化而有效沉积到铁谱片上，从而使油液的监测分析结果更为全面和准确。此外，介绍了磁流体的组成，分析了磁流体使非铁磁性磨粒磁化的机理。     

Motion analysis on the particles in a magnetic field detector

This paper, as the title indicates, deals with the depositing mechanism of the particles under the magnetic field in the lubricant for on-line ferrograph or oil analysis. Lubricant, containing ferromagnetic particles, is taken as the multiphasic ferromagnetic fluid in ferrograph detecting. By measuring and regressing, the distribution formulas of magnetic density and magnetic density gradient of an electromagnet are gained. The variance law of viscosity of lubricant in the non-uniform magnetic field is studied and a viscosity formula is put forward. The motion law of ferromagnetic particles in the non-uniform magnetic field is studied and a standpoint is put forward, which is that the ferromagnetic particles cannot achieve a constant sinking velocity in a non-uniform magnetic field. The factors influencing particles motion, such as particle diameter, ratio of particles volume and air bubbles, are also studied. Some results are obtained and discussed, which are of practical significance in the research and design of on-line ferrograph and other methods of on-line oil monitoring.     

油液在线监测传感器技术

油液在线监测是设备润滑磨损状态监测与实时诊断技术的重要发展方向,而监测仪器的开发与选择是这一故障诊断技术实现准确监测应用的关键。在对当前国内外油液磨损颗粒在线监测传感器、油质在线监测传感器、油液多信息集成在线监测仪器及应用技术介绍基础上,给予了当前油液在线监测传感器技术的相关评述,为油液在线监测技术的研究、应用及推广提供一定帮助。     

Shape and texture features in the automated classification of adhesive and abrasive wear particles

In this study the automated classification system, developed previously by the authors, was used to classify wear particles. Two kinds of wear particles, adhesive and abrasive, were classified. The wear particles were generated using a pin-on-disk tribometer. Various operating conditions of load, sliding time and abrasive grit size were applied to simulate adhesive and abrasive wear of different severity. SEM images of wear particles were acquired, forming a database for further analysis. The particle images were divided into eight groups or classes, each class representing different wear test conditions. All eight particle classes were first examined visually. Next, area, perimeter and elongation parameters were determined for each class and the parameters were statistically analysed. The automated classification system, based on particle surface texture, was then applied to all particle classes. The results of the automated particle classification were compared to those based on either the visual assessment of particle morphology or numerical parameter values. It was shown that the texture-based classification system was a more efficient and accurate way of distinguishing between various wear particles than classification based on size and shape of wear particles. It seems that the texture-based classification method developed has great potential to become a very useful tool in the machine condition monitoring industry.     

Research on an on-line wear condition monitoring system for marine diesel engine

This paper introduces a kind of on-line wear condition monitoring system for marine diesel engines. The system consists of three functions i.e. particle detecting, lubricant quality detecting and shaft torque moment and instantaneous rotation velocity detecting. The system detects wear particles in lubricant with an on-line ferrograph so as to judge wear condition of tribo-pairs of the diesel engine. A vertical detector fixed is used for environment of the marine diesel engine in this system, and the rule of distribution of particles in the vertical detector fixed and the horizontal detector fixed are alike in substance. The system detects the relative variation of lubricant quality by the grid capacitance sensors in an on-line way, which consists of an upper capacitance and a lower capacitance and can distinguish the relative variation of the dielectric constant of lubricant caused by pollutants such as water, metal particles etc. The system detects the shaft torque moment and the instantaneous rotation velocity of the diesel engine with photoelectric sensors, and corresponds the wear condition with the power condition by the change of instantaneous rotation velocity due to burning pressure change, which is helpful to judge cylinder wear.     

在线实时监测精轧机润滑油含水装置设计

高速线材生产线冷却水污染润滑系统是目前国内各高线机组最常见的问题。设计一种基于电化学阻抗谱(EIS)的实时监测高线轧机润滑油含水率变化的监测装置,并进行实验室模拟测试。结果表明,该装置能够在线准确地检测出润滑油中的含水率,并能实时监测滑油中水分含量的变化趋势;该测量装置对油液中磨损金属颗粒的反应不太敏感,在使用中可以忽略污染颗粒的影响。     

基于机器视觉的积屑瘤在线监测装置

现代切削工艺中,产生积屑瘤对切削过程和加工表面质量的影响不容忽视,对积屑瘤的在线监测显得尤为重要。设计制作了一种基于机器视觉技术的积屑瘤在线监测装置,能够方便地在机获取切削加工中积屑瘤变化的清晰图像。实验结果表明,该装置简便可靠,为于最终实现刀具磨损在线监测提供了手段。