38CrSi自配副的摩擦磨损性能

采用自制的销盘式摩擦磨损试验机研究了38CrSi自配副干滑动时的摩擦因数、磨损率随滑动速度和载荷的变化规律;利用SEM观察了磨损面的微观形貌,分析了摩擦磨损机理。结果表明:其摩擦因数随着载荷和速度的增加而减小;磨损率随着载荷的增加而增大,随着速度的增加先增大后减小,和常用材料的磨损率随速度增加而增大的规律不同;磨损机理为磨粒磨损和粘着磨损。     

38CrSi自配副的摩擦磨损性能

采用自制的销盘式摩擦磨损试验机研究了38CrSi自配副干滑动时的摩擦因数、磨损率随滑动速度和载荷的变化规律;利用SEM观察了磨损面的微观形貌,分析了摩擦磨损机理。结果表明：其摩擦因数随着载荷和速度的增加而减小;磨损率随着载荷的增加而增大,随着速度的增加先增大后减小,和常用材料的磨损率随速度增加而增大的规律不同;磨损机理为磨粒磨损和粘着磨损。     

石墨增强的聚酰亚胺复合材料摩擦学性能研究

利用SST-ST销/盘摩擦试验机,研究质量分数15%石墨增加的聚酰亚胺复合材料在68#液压油介质中的摩擦磨损行为。结果表明：聚酰亚胺复合材料摩擦因数随摩擦时间的增加有减小趋势;平均摩擦因数随PV值的增加而减小;磨损率随PV值的增大呈现先减小后增大的变化趋势;磨损机制在低PV值条件下主要为磨粒磨损和材料塑性变形,随PV值的增加,磨损机制逐渐转变为以黏着磨损为主。     

石墨增强聚酰亚胺复合材料摩擦学性能研究

利用SST-ST销/盘摩擦试验机,研究质量分数15%石墨增加的聚酰亚胺复合材料在68#液压油介质中的摩擦磨损行为。结果表明:聚酰亚胺复合材料摩擦因数随摩擦时间的增加有减小趋势;平均摩擦因数随PV值的增加而减小;磨损率随PV值的增大呈现先减小后增大的变化趋势;磨损机制在低PV值条件下主要为磨粒磨损和材料塑性变形,随PV值的增加,磨损机制逐渐转变为以黏着磨损为主。     

位移幅值对ZG230-450铸钢微动磨损行为的影响

在不同位移幅值(60～140μm)下对ZG230-450铸钢进行微动磨损试验,研究了位移幅值对摩擦因数、磨损体积和磨损机制的影响.结果表明:随着位移幅值增大,铸钢的微动磨损行为由混合滑移转变为完全滑移,耗散能逐渐增大;混合滑移状态下,摩擦因数经过上升阶段后就迅速进入稳定阶段,而完全滑移状态下的摩擦因数经历了上升阶段、波动阶段和趋于稳定阶段,位移幅值越大,进入稳定阶段需要的往复运动次数越多;随着位移幅值增大,磨痕面积和磨损体积均增加,磨损机制由黏着磨损和剥层磨损向磨粒磨损和剥层磨损过渡.     

超音速火焰喷涂锡青铜-钢基双金属材料摩擦性能

采用超音速火焰喷涂QWFSn8Zn3粉末制备钢背双金属材料。研究不同润滑介质、不同表面粗糙度和不同摩擦载荷对超音速喷涂锡青铜-钢基涂层摩擦性能的影响。分析锡青铜涂层的磨损形貌和磨损机制。研究结果表明:抗磨液压油润滑条件下,涂层有最小的摩擦因数0.093,30#润滑油、液体石蜡和固体MoS2润滑下涂层摩擦因数分别为0.099、0.107和0.099;随表面粗糙度减小,喷涂锡青铜-钢基涂层摩擦因数逐渐减小;随着摩擦载荷的增加,喷涂层摩擦因数逐渐减小;不同润滑介质条件下,涂层存在磨粒磨损、黏着磨损和疲劳磨损共同作用的磨损机制。     

AZ91D镁合金微动磨损特性研究

采用液压高精度材料试验机考察了平面一球面接触的AZ91D镁合金摩擦副的微动磨损行为，分析了位移幅值、法向载荷和频率等参数对摩擦因数和磨损体积的影响，考察了不同实验条件下的磨斑形貌，并探讨了其磨损机理。结果表明：AZ91D镁合金的微动区域可分为部分滑移区、混合区和滑移区3个区域，粘着磨损、疲劳磨损和磨粒磨损分别是3个区域的主要磨损机制；磨损体积随着位移幅值和法向载荷的增加而增大，但却随着频率的增大而减小。在微动部分滑移区和混合区，摩擦因数随着位移增大迅速增加；在微动滑移区，摩擦因数随法向载荷的增大而减小，而位移幅值和频率对摩擦因数的影响较小。     

磨粒磨损的模型化分析

磨粒磨损作为磨损的主要类型之一,影响机械使用寿命。针对犁沟磨损机制,用球形、圆锥形和圆台形磨粒模型分析其磨粒磨损的磨损率和摩擦因数,考虑磨粒数量与磨粒尺寸间的指数关系,分析磨损率随磨粒数量和磨粒尺寸的变化,计算平均摩擦因数随磨粒数量及其参数的变化。研究结果表明,球形磨粒模型的磨损率随着磨粒的减小和磨粒数量的增加而减小,其摩擦因数随着磨粒数量的增多而增大;圆锥形磨粒模型的磨损率随着磨粒的增大与数量的增多而增大,其摩擦因数随着倾斜角的增大而增大;圆台形磨粒模型的磨损率变化趋势与球形磨粒一致,但其摩擦因数变化的趋势与球形磨粒相反。     

Inconel718与硬质合金摩擦磨损特性的实验研究

利用UMT-2多功能摩擦磨损试验机对镍基合金Inconel 718与硬质合金刀具对偶时的摩擦磨损特性进行研究,揭示法向载荷和滑动速度对摩擦副摩擦因数的影响,通过SEM观察试样摩擦形貌并分析磨损机制.研究结果表明:摩擦副的摩擦因数随着法向载荷的增大而减小,随滑动速度的增大而增大;Inconel 718镍基合金与硬质合金对偶时的磨损机制主要为黏着磨损、磨粒磨损和氧化磨损.     

温度对6061铝合金摩擦磨损行为的影响

采用球盘摩擦磨损试验机研究了温度(25,200,300,400,500℃)对6061铝合金摩擦磨损行为的影响,通过分析铝合金磨损后的表面形貌和微区成分研究了其在不同温度下的磨损机制。结果表明:随温度升高,摩擦因数呈先增大后减小的趋势,磨损率显著增加,磨损机制从磨粒磨损逐渐变为氧化磨损、粘着磨损以及严重的塑性变形磨损。     

Experimental studies on the effects of reduction in gear tooth stiffness and lubricant film thickness in a spur geared system

Gears are one of the most common mechanisms for transmitting power and motion and their usage can be found in numerous applications. Studies on gear teeth contacts have been considered as one of the most complicated applications in tribology. Depending on the application, the speed and load conditions of teeth may change triggering several types of failures on teeth surface such as wear, scuffing, micro-pitting and pitting. The above-mentioned faults influence changes in vibration and acoustic signals, due to changes in operating conditions such as increase in temperature and decrease in lubricant film thickness and specific film thickness. These abnormal changes result in cumulative effects on localised or distributed faults on load bearing surfaces of gears. Such damages cause reduction in tooth stiffness and severity of damage can be assessed by evaluating the same using vibration-based signals.This paper presents the results of experimental investigations carried out to assess wear in spur gears of back-to-back gearbox under accelerated test conditions. The studies considered the estimation of operating conditions such as film thickness and their effects on the fault growth on teeth surface. Modal testing experiments have been carried out on the same gear starting from healthy to worn out conditions to quantify wear damage. The results provide a good understanding of dependent roles of gearbox operating conditions and vibration parameters as measures for effective assessment of wear in spur gears.     

Friction and Wear Characteristics of TiN Coated Vane for the Rotary Compressor in a R410A Refrigerant©

HFC is a potential alternative refrigerant for CFC, which depletes the ozone layer. The rotary compressor has been widely used for refrigeration and air-conditioning systems due to its compactness and high-speed operation. R410A, an HFC refrigerant, is used in a refrigerator compressor, but its frictional characteristic is not established. In this study, the influence of R410A refrigerant on the roller-vane surfaces was studied, and friction and wear characteristics of the TiN coated vane were investigated. The friction and wear data were obtained with a specially designed high-pressure wear tester. A testing environment charged with HFC refrigerant more closely simulates the operating conditions of a real rotary compressor. In pure oil without R410A, wear of the TiN coated vane was larger than that of the uncoated vane. But when the refrigerant was dissolved in oil, wear of the uncoated vane was larger than that of the TiN coated vane. This showed that a TiN coated vane is good relative to wear resistance in the refrigerant/lubricant mixed environment. As the rotating speed of the frictional motion increased, wear increased. But in the high-velocity region, wear decreased because the boundary lubrication is changed into the mixed lubrication in the lubrication region. As the pressure grew larger, wear volume and coefficient of friction became larger. This is because the amount of the refrigerants dissolved in oil increased and the viscosity of oil dropped as the pressure increased.     

Detection and diagnosis of surface wear failure in a spur geared system using EEMD based vibration signalanalysis

Gears are used for transmission of power, motion or both. Under increased power and higher speeds, tribological failures such as scuffing, pitting, mild wear and tooth breakage are of major concern. This paper presents the results of experimental investigations carried out to assess wear in spur gears of a back-to-back gear box under accelerated test conditions. The studies considered the estimation of specific lubricant film thickness and its effects on the fault growth on gear teeth surface. Ensemble empirical mode decomposition (EEMD) technique is used to extract the fault related features from the vibration signals acquired from the gearbox. The results highlight the advantage of EEMD technique for effective assessment of wear in spurgears.     

A new fault diagnosis algorithm for helical gears rotating at low speed using an optical encoder

Helical gears are widely used in gearboxes due to its low noise and high load carrying capacity, but it is difficult to diagnose their early faults based on the signals produced by condition monitoring systems, particularly when the gears rotate at low speed. In this paper, a new concept of Root Mean Square (RMS) value calculation using angle domain signals within small angular ranges is proposed. With this concept, a new diagnosis algorithm based on the time pulses of an encoder is developed to overcome the difficulty of fault diagnosis for helical gears at low rotational speeds. In this proposed algorithm, both acceleration signals and encoder impulse signal are acquired at the same time. The sampling rate and data length in angular domain are determined based on the rotational speed and size of the gear. The vibration signals in angular domain are obtained by re-sampling the vibration signal of the gear in the time domain according to the encoder pulse signal. The fault features of the helical gear at low rotational speed are then obtained with reference to the RMS values in small angular ranges and the order tracking spectrum following the Angular Domain Synchronous Average processing (ADSA). The new algorithm is not only able to reduce the noise and improves the signal to noise ratio by the ADSA method, but also extracts the features of helical gear fault from the meshing position of the faulty gear teeth, hence overcoming the difficulty of fault diagnosis of helical gears rotating at low speed. The experimental results have shown that the new algorithm is more effective than traditional diagnosis methods. The paper concludes that the proposed helical gear fault diagnosis method based on time pulses of encoder algorithm provides a new means of helical gear fault detection and diagnosis.     

航空装备液压舵机主泵振动及噪音原因探析

一般在航空装备液压系统中,通常会产生一种和振动相随的噪音问题。虽然噪音不属于系统本身故障,但是对于航空装备来说,却能在很大程度上降低飞行员的舒适性,增加被敌方侦测到的风险,损坏液压系统部件,严重的话还会影响飞行安全。基于此,本文主要针对航空装备液压舵机主油泵振动以及噪音问题,详细分析其具体产生原因。     

润滑和载荷状态对聚甲醛齿轮服役性能的影响

基于齿轮耐久性能试验台开展了一系列干接触/油润滑下POM(聚甲醛)-POM齿轮副承载能力试验,并测量了服役过程中的轮齿温度、磨损量、齿廓精度和齿面形貌。试验发现,POM齿轮失效形式与载荷和润滑方式有关。通过对齿面微观形貌和磨屑表征,确认干接触下POM齿轮主要磨损模式为黏着磨损与磨粒磨损,而油润滑下POM齿轮失效形式为接触疲劳失效。由于润滑油减少了齿面摩擦,降低了运行温度,延缓了齿面劣化程度,因此POM齿轮在油润滑下的承载能力明显提高。     

螺杆泵驱动装置磨损状态监测系统

螺杆泵驱动装置受力复杂,振源众多,轴承和齿轮的磨损类故障较为频繁,而常规的单项指标测试只能进行定性分析,诊断精确度不高。为此,开发了磨损状态监测系统。该系统由传感器、诊断仪主机和便携式计算机组成。通过建立设备信息库、故障模式库实现了故障特征自动提取;通过建立磨损状态分级模型,实现了部件的故障诊断及整机磨损状态的评判。实际应用中,诊断出了电机轴承磨损和驱动装置大、小齿轮磨损的故障,表明系统具有较高的应用价值。     

旋挖钻机设备油液智能分析与健康监测

为了提高油液中与设备运行状态相关信息的提取效率，获取更为完整的信息来评估设备的当前状态，提出一种设备油液监测技术——全谱技术。基于全谱法制备油液污染颗粒全谱片，首先，利用图像分割技术、自动计数算法、模糊支持向量机模型实现谱片分析流程的自动化，完成谱片信息的智能提取，以此获取反映设备运行状态的关键信息；其次，将该技术应用到旋挖钻机设备的状态监测诊断中，通过对设备液压油、齿轮油中悬浮颗粒的定性、定量分析，实现了设备当前润滑、磨损状态的定性评估，为旋挖钻机的维修维护提供了指导。结果表明，油液全谱技术能够完整、快速、准确地提取油液中包含的信息来反映设备的运行状态，具有检测效率高、分析内容丰富的特点，可进一步推广应用到其他设备的油液监测诊断工作中。     

重型汽车中桥减速器润滑油中磨损颗粒分析

重型汽车中桥减速器在工作过程中其摩擦副接触表面因相对运动而产生的磨损颗粒进入润滑油中,导致润滑油性能下降;磨损颗粒随润滑油进入摩擦副接触表面,摩擦副磨损加剧。根据重型汽车的运行特点,每隔一定里程数对减速器润滑油进行取样,综合分析在用润滑油中磨损颗粒物的大小、形貌及成分。结果表明：减速器在用润滑油中磨损颗粒主要成分是铁屑和铜屑,磨损颗粒主要来自于球面垫片（铜）及其配副的摩擦以及齿轮副间的摩擦。具体分析磨损颗粒产生过程及形成机制,为重型汽车中桥减速器中运动摩擦副的设计及制造提供理论依据。     

[设备健康管理]深度置信网络在齿轮故障诊断中的应用

针对齿轮传动系统中齿轮等零部件易出现故障或失效等问题,提出了一种基于深度学习理论的齿轮传动系统故障诊断方法。首先利用深度置信网络强大的特征自提取能力,对齿轮传动系统的振动信号进行特征提取,然后通过DBNs的复杂映射表征能力对故障信号进行故障判别。诊断实例表明,若不对齿轮振动的原始时域信号进行特征提取,直接利用DBNs对其进行诊断时,故障识别正确率只能达到 60%左右;如果对时域信号进行简单的傅里叶变换后,再利用 DBNs 对处理后的振动信号频谱进行诊断分析,正确率能达到 99.7%,从而证明了所提故障诊断方法的简易性和有效性。