变桨轴承微动磨损分析与沟道参数确定

在交变和振动载荷的作用下,风力发电机组变桨轴承的主要失效形式为钢球和沟道之间的微动磨损。分析了变桨轴承微动磨损产生的原因、损伤形式及微动运行模式,为降低变桨轴承的微动磨损,通过试验对其沟道参数的取值进行了研究。结果表明:变桨轴承的沟道曲率半径系数为0.53左右,初始接触角为45°左右时,可提高变桨轴承的抗微动磨损能力,减缓沟道微动磨损损伤。     

润滑因素与滚动轴承失效的关系研究

为分析润滑因素与滚动轴承失效之间的关系,通过对滚动轴承失效形式的统计,分析各种失效形式与润滑之间的相互作用机制;采用实验方法从轴承本身和润滑脂方面分析滚动轴承的失效机制;阐述润滑因素对滚动轴承寿命的影响。研究结果表明：表面磨损是滚动轴承失效的主要表现形式;润滑脂润滑性能达不到要求是导致滚动轴承达不到额定寿命的主要原因;滚动轴承失效通常伴随着润滑脂的润滑性能下降、油膜压力和厚度的分布发生变化,而润滑脂的这种变化会促使滚动轴承失效的加剧,轴承寿命缩短。     

风电机组变桨轴承漏脂分析及改进措施

针对风电机组变桨轴承漏脂问题,从密封圈密封性能、变桨轴承内部结构设计、润滑脂的选择及填充用量等方面进行分析,通过选择抗老化和抗磨损性能好的密封圈材料,把密封圈的双唇结构改为多唇结构,沟底增加矩形沟槽,改善轴承脂孔尺寸与分布,增加轴承排脂孔外侧连接螺纹孔的直径和深度,改善润滑系统控制策略,设计变桨轴承运行时注脂的频率、时...     

滚针轴承的微动磨损分析

在变速器中,微动磨损是滚针轴承的主要失效形式之一。为预防微动磨损,对微动磨损的机制以及影响因素进行了全面的分析。滚针轴承的微动磨损与它所承受的径向载荷、轴向往复位移、润滑条件等因素密切相关。通过对各影响因素的分析,从设计角度提出了几种预防滚针轴承微动磨损的方法。     

风机变桨轴承齿面磨损与齿轮可靠度分析

针对风电机组变桨轴承内齿面出现较大程度磨损的情况,基于齿轮啮合原理和Hertz接触理论对齿面磨损进行分析,得到变桨轴承齿面接触应力和出现微动磨损的角度范围;根据齿轮承载能力分析,得到齿轮可靠度与磨损量的计算关系,并通过某机型变桨轴承内齿面磨损实例分析验证该方法的可靠性。     

润滑状态对轧机圆锥滚子轴承接触特性的影响

针对梅钢五机架连轧六辊轧机工作辊的圆锥滚子轴承磨损和烧损问题,介绍了脂润滑滚动轴承的润滑机制;为了选择合适的轴承润滑脂,建立了面向润滑分析的4列圆锥滚子轴承有限元模型,并对3组不同润滑脂润滑后的轴承进行了有限元仿真;通过不同润滑状态下轴承接触特性模拟结果的比较,发现聚脲脂可明显改善轧机轴承的接触特性。现场使用结果表明,聚脲脂润滑可大大降低轧机轴承的磨损和烧损失效发生概率。     

振动刀套625Z轴承失效分析

用于高速旋转振动刀套的625Z滚动轴承在寿命期内经常发生提前失效,为了获取失效原因,对轴承的失效形式做了统计,得出不同失效形式所占的比例;校核了轴承的额定寿命,并对轴承进行拆套检查,发现润滑脂颜色异常,综合分析得出润滑失效是造成轴承提前失效的主要原因。润滑脂需根据实际的工况条件进行选择,同时要保证轴的制造精度以及与轴承的安装配合精度。     

桨-毂轴承材料扭动微动磨损行为研究

采用面接触扭动微动形式,以动力定位系统可调距螺旋桨桨-毂轴承摩擦副材料(CuNiAl-42CrMo4)为对象,以不同的角位移幅值模拟海水波动影响下的微动磨损行为,并结合扫描电子显微镜和超景深三维显微镜对磨痕形貌进行分析,探究桨-毂轴承摩擦副材料扭动微动磨损规律。结果表明,随着角位移幅值的增加,扭动微动依次运行于部分滑移区、混合区、滑移区,摩擦因数减小,同时磨损量增加,微动损伤中剥层机制所占的比例逐渐增加,且由于疲劳裂纹扩展的不利影响,实际运行过程中要尽量避开混合区。     

红外波谱技术在轴承润滑脂分析上的应用

探讨了红外波谱分析技术在轴承润滑脂分析及鉴别中的应用。除了分析脂中各类基础油、添加剂及稠化剂的特征波谱外，还讨论了利用波谱技术的结果来表征轴承润滑脂化学劣变参数，研究不同环境、试验条件及各类污染物对脂润滑机械部件失效的影响。波谱分析技术是一种快速、可靠和极为有效地分析手段，可应用于各类脂润滑的磨损监测及轴承的失效分析。     

基于润滑优化的重载牵引电动机轴承长寿命技术研究

随着机车朝着高速重载方向发展,牵引电动机轴承的载荷及冲击振动急剧增大,给轴承疲劳寿命周期带来了新挑战,在轴承服役寿命周期内轴承出现了早期疲劳剥落,导致轴承提前失效,给机车运行带来安全隐患。针对某款机车牵引电动机深沟球轴承外圈沟道面剥落失效进行了分析,失效原因主要为润滑不良导致的疲劳剥落,提出了改换极压型润滑脂的寿命优化技术方案,经过实车运行考核评估,优化方案有效提升了轴承寿命及润滑状况。     

关于微动磨损与微动疲劳的研究

微动磨损与微动疲劳是２种主要的微动模式,造成的损伤在工业中相当普遍,并可能引发灾难性的后果。主要研究了们移幅度、压力和疲劳应力３个基本微动参数,并以获得的微动区域、微动图为基础,分析了微动磨损与微动疲劳的运行机制和破坏规律。为更好地了解微动磨损与微动疲劳之间的内在联系,进一步探讨了接触磨损与局部疲劳、局部疲劳与整体疲劳之间的竞争机制。     

Fretting wear

This review covers developments in fretting wear over the past three years. The threshold amplitude of slip at which fretting damage becomes apparent is found to be in the region of 0.5 μm. Very low amplitudes of slip and low frequencies (0.001 Hz) are particularly damaging in electrical contacts, leading to high resistances resulting from oxide build-up. In high temperature fretting, oxide formation can give protection. In titanium alloys this can be improved by ion implantation, particularly with bismuth. In aqueous solutions, such as sea water, fretting stimulates the chemical dissolution of material, which accounts by far for the major part of the wear.     

Fretting of glass

Fretting damage to a glass surface in contact with a steel ball was investigated. In the initial stage of fretting, severe wear occurred on the steel ball and considerable wear debris was transferred to the glass surface. The coefficient of friction increased during this stage by 80%. Fatigue cracks were observed on the glass surface under conditions of high normal load and tangential force. The mechanism of fretting fatigue and fretting wear is discussed in relation to a brittle material. Finally the effect of thin metal foil inserts in reducing fretting damage is described.     

Triboacoustic Control of Fretting

In the paper, we have presented experimental results on the real-time triboacoustic control of the integrity of a nominally motionless friction joint under fretting conditions. The disturbance in the integrity of the tribosuppression as a result of wear has been reliably detected both by the change in the shape of the acoustic histograms of the operating noise and by the change in the noise spectrum due to the appearance of strong mid-frequency modes of the contact gap. The appearance of two oppositely directed wave energy cascades in the regime of fretting has been observed, i.e., the direct cascade from the pumping modes toward the high frequencies and the reverse cascade toward the low infrasonic frequencies. The former has been associated with microplastic deformations in the zones of actual contact, while the latter has been associated with the dynamic generation of slow angular motions in the friction system.     

Fretting in hostile environments

Metallic materials for use in corrosive environments are almost entirely of the type which derive their corrosion resistance from a protective oxide film which may withstand the effects of fatigue and creep, but which is completely disrupted by fretting. This may have serious consequences, for example, in a nuclear reactor where a stainless steel structure may be operating at a high temperature in an oxidising atmosphere. Not only will disruption of the normally protective oxide film allow corrosion to continue, it may also enhance corrosion since the protective film is rich in chromium and the metal surface is therefore depleted in chromium and has a lower corrosion resistance than the original surface. In certain designs of diesel engine lands on the outer surface of the cylinder liner bear on corresponding lands on the cylinder block forming a seal separating the region of the exhaust gases and the region of the cooling water which may contain antifreeze. Fretting due to vibration allows these environments to gain access to the seal surfaces resulting in accelerated fretting damage with rapid breakdown of the seal. A third example is that of the surgical implant. The importance of corrosion resistance here is that corrosion products can be toxic to surrounding tissue. Fretting between the surfaces of screwholes in the implant and the underside of the heads of screws used to fix it into the bone can result in toxic soluble corrosion products being released into the body fluid.     

微动图和能量的方法在微动研究中的应用

介绍了微动的两种研究方法：微动图和能量的方法。归纳了微动图的组成、分类、作法及其在减轻微动损伤方面的作用。讨论了能量的方法在微动摩擦学研究中的应用，包括微动磨损体积与摩擦过程中释放的总能量的关系及能量分布在解释微动实验现象中的成功运用。最后指出微动摩擦学的研究仍然面临巨大挑战。     

微动疲劳参数对钢丝微动疲劳磨损演化的影响*

微动疲劳易引起钢丝表面磨损和横截面积损失,进而造成钢丝断裂失效并缩短钢丝绳使用寿命。不同微动疲劳参数（接触载荷、疲劳载荷、钢丝直径和交叉角度）引起差异的钢丝微动疲劳磨损特性,故研究微动疲劳参数对钢丝微动疲劳磨损演化规律影响至关重要。基于摩擦学理论和Marc仿真软件构建钢丝微动疲劳磨损模型,探究接触载荷、疲劳载荷、交叉角度和钢丝直径对钢丝微动疲劳磨损演化的影响规律。结果表明：钢丝微动疲劳磨损体积主要与接触载荷和疲劳载荷有关;疲劳钢丝的磨损深度、磨损率及磨损体积随着接触载荷的增加而增大,且不同接触载荷下疲劳钢丝磨损体积均随着循环次数的增加而呈线性增加;随疲劳载荷幅值的增加,疲劳钢丝的磨损深度、磨损率及磨损体积均呈增加趋势;在不同疲劳载荷范围下疲劳钢丝的磨损体积均随着循环次数的增加而呈线性增加;当接触载荷、疲劳载荷及钢丝间摩擦因数相同时,不同交叉角度和不同加载钢丝直径下疲劳钢丝的磨损体积相同。     

Fretting wear in seawater

Fretting tests of bearing steel (SUJ-2) and ceramics (Al₂O₃ and Si₃N₄) were carried out in the following environments: air, deionized water, 3.07% NaCl solution, synthetic seawater and natural seawater. Also, investigations to determine the optimum fretting wear resistant material for ships, marine equipment and offshore structures were conducted. The results showed that (1) the corrosion products formed in seawater behaved as a lubricant and reduced the fretting damage at large amplitudes, but the fretting damage was not greatly influenced by the different environments at very small amplitudes (such as 14 μm), (2) instead of natural seawater, synthetic seawater was adequate for the investigations of fretting wear, but 3.07% NaCl solution was found not to be and (3) the ceramic Al₂O₃ was a potentially useful material against fretting wear under light loads in seawater.