基于脂润滑的混合陶瓷球高速主轴轴承早期失效试验

针对脂润滑的混合陶瓷球高速主轴轴承的工作特点,对不同工况下的混合陶瓷球高速主轴轴承进行了早期失效试验,并对其早期失效的原因进行了分析研究。结果表明,高速条件下脂润滑的混合陶瓷球主轴轴承发生早期失效的原因主要是高速运行和快速频繁启停而产生的剧烈冲击、摩擦和较高的工作温度所导致的保持架薄弱部位断裂,其运行时间远未达到轴承寿命理论所预期的疲劳寿命或精度寿命。     

高速陶瓷球轴承脂润滑试验研究

在自行研制的高速轴承试验台上，对型号为6305的三点接触高速混合式陶瓷球轴承在载荷1500N，27000r/min工况下用两种润滑脂进行试验研究，并将筛选结果和油润滑条件下的温升和功耗进行了比较。试验结果表明：KK3润滑脂的可以在高速情况下对混合式陶瓷球轴承实现有效的润滑；同时kk3脂润滑下陶瓷球轴承的功耗比用10号主轴油润滑下的陶瓷球轴承低24.1%，该结果对于简化高速、短寿命轴承的润滑系统和提高轴承可靠性有重要意义。     

轴承保持架动平衡原理性试验

航空发动机主轴轴承呆动平衡精度对轴承的性能至关重要。作者选择结构较为简单的保持架。对其动平衡进行原理性试验，以确定保持架动平衡的基本方法。介绍了动平衡的原理、步骤及试验方法。     

固体润滑轴承的寿命分析

通过对固体润滑寿命理论和试验分析，得出要获得固化润滑轴承更长的寿命，则需使轴承实现转移膜润滑，而合适转移膜润滑的实现与保持架的稳定性，材料的磨损及工况条件等有着密切关系。     

太空用固体润滑轴承试验分析

以轴承的固体润滑为研究对象，进行了轴承跑合试验、轴承寿命及性能试验研究分析，为采用固体润滑技术解决轴承空间润滑问题提供了依据。     

超低温氢氧泵轴承技术研究及进展

液氢／液氧火箭发动机涡轮泵用球轴承工作在超低温高转速重载荷条件下，需要采用合适的材料匹配和可靠的固体润滑。对由9Cr18套圈和政治协商会议组成的钢制轴承，常采用PTFE复合材料保持架及套圈和球上表面溅射PTFE膜层或PVD软金属膜来实现润滑，其主要失效可归纳为磨损、胶合及保持架断裂3种形式。采用氮化硅球的混合式陶瓷轴承以及套圈表面等离子体淹没离子注入Ag润滑膜层的应用，提高了轴承的寿命和可靠性。陶瓷轴承技术和离子改性技术将满足该轴承技术发展的需要。     

新型无保持架角接触球轴承的断油性能试验

轴承的抗断油能力直接影响航空发动机的可靠性。为了探究一种新型无保持架角接触球轴承的干运转性能,设计了轴承环下断油试验方案,构建了断油试验平台及运行程序,分析了断油之后的轴承外观形貌、温度、转速及电流等变化情况。试验结果表明,在高转速、高轴向载荷工况下,新型轴承的干运转时间为51 min,验证了该新型轴承具有良好的抗断油能力,可以在机械工业领域广泛应用。     

电机转子轴承的一次性润滑寿命试验

对电机转子含油保持架轴承进行一次性润滑试验,在试验过程中根据电机运转电流随时间的变化做出了轴承的润滑曲线,结合轴承含油保持架的出油特性,形成电机转子轴承的一次性润滑寿命曲线.通过对该曲线的分析,明确了对电机转子轴承补充供油的时间.     

多孔含油保持架对陀螺电机轴承性能的影响

多孔含油保持架对陀螺电机轴承的润滑、运转稳定性、轴承的寿命和可靠性及陀螺仪精度等都有密切的关系。介绍了多孔含油保持架的结构 ,分析了保持架对陀螺电机轴承性能的影响。附图 3幅 ,表 1个     

陀螺仪电动机转子轴承研究现状与展望

根据研究工作积累和文献资料调研,对陀螺仪电动机转子用滚动轴承的相关研究技术进行了全面的归纳总结和分析评述,内容涵盖转子轴承的优化设计技术、材料、干涸弹流润滑(PEHL)机理、保持架的不稳定性、寿命和可靠性试验、提高转子轴承寿命、轴承测试与试验技术等方面,在此基础上展望了未来值得关注的研究方向,诸如转子轴承的薄膜润滑机理、可减磨延寿的纳米级颗粒润滑添加剂、润滑剂性能评价、使用陶瓷滚动体的优化设计和加速寿命试验技术,分析我国在转子轴承基础理论研究及工程应用中的现状及在技术层面上所面临的各种严峻挑战,并提出相应的对策和该领域发展的一些规划性建议。     

Current Status of Hybrid Bearing Damage Detection

Advances in material development and processing have led to the introduction of ceramic hybrid bearings for many applications. The introduction of silicon nitride hybrid bearings into the high-pressure oxidizer turbopump on the space shuttle main engine led NASA to solve a highly persistent and troublesome bearing problem. Hybrid bearings consist of ceramic balls and steel races. The majority of hybrid bearings utilize Si₃N₄ balls. The aerospace industry is currently studying the use of hybrid bearings and, naturally, the failure modes of these bearings become an issue in light of the limited data available.

In today's turbine engines and helicopter transmissions, the health of the bearings is detected by the properties of the debris found in the lubrication line when damage begins to occur. Current oil debris sensor technology relies on the magnetic properties of the debris to detect damage. Because the ceramic rolling elements of hybrid bearings have no metallic properties, a new sensing system must be developed to indicate the system health if ceramic components are to be safely implemented in aerospace applications. The ceramic oil debris sensor must be capable of detecting ceramic and metallic component damage with sufficient reliability and forewarning to prevent a catastrophic failure.

The objective of this research is to provide a background summary on what is currently known about hybrid bearing failure modes and to report preliminary results on the detection of silicon nitride debris in oil using a commercial particle counter.     

全陶瓷球轴承油润滑特性及其对服役性能影响规律

相比于金属球轴承,全陶瓷球轴承在极端工况下的服役性能更加突出。为了揭示全陶瓷球轴承油润滑特性,提高全陶瓷球轴承的运转性能与使用寿命,以6208CE氮化硅全陶瓷深沟球轴承为例,对其在油润滑工况下所表现出的摩擦、振动、温升等特性进行试验研究,探讨供油量对全陶瓷球轴承润滑状态的影响,并对试验后的全陶瓷球轴承接触微区表层进行解析。研究发现：全陶瓷球轴承油润滑服役过程中,在某个特定工况下存在一个最佳供油量,使得轴承可实现全膜润滑,从而表现出最好的摩擦、振动、温升等特性;小于最佳供油量时,为乏油状态,轴承接触微区存在油-固混合润滑状态;大于最佳供油量时,过多润滑油液会产生的黏滞阻力;相比于载荷,轴承的转速对最佳供油量的取值具有决定性影响。研究成果对于揭示全陶瓷球轴承油润滑特性,丰富其润滑理论与方法具有一定指导意义。     

Comparison of Power Losses and Temperatures between an All-Steel and a Direct Outer Ring–Cooled,Hybrid 133-mm-Bore Ball Bearing at Very High Speeds

Next-generation aircraft engines will have to face more stringent requirements for reliability, thrust to weight, efficiency, environment protection, and profitability. These requirements affect all engine modules and components, including rolling element bearings. To cope with the above-mentioned requirements, next-generation aircraft engine main shaft bearings will operate under higher loads, speeds, and temperatures and increased reliability. In addition, lighter weight components are desirable. Hence, new material and cooling technologies including weight- and stress-optimized designs need to be developed.

In this article, the experimental investigation results of a novel main shaft ball bearing featuring ceramic balls, direct outer ring cooling, squeeze film damping, as well as surface-nitrided raceways are presented. Bearing rig testing under typical aircraft engine flight conditions has been performed. Savings for oil flow quantity of more than 45% and for power loss of more than 15% were identified. Outer ring temperature reductions of more than 20 K were achieved due to the use of ceramic ball material and the direct outer ring cooling concept. The ultra-high-speed capability of the bearing was demonstrated. Rotational speeds of 24,000 rpm were achieved at bearing temperatures below 200°C. The fundamental experimental results including oil and bearing temperature distribution, power dissipation, and bearing efficiency are presented. In addition, experimental power loss and temperature results are compared with data for a conventional all-steel bearing.     

Bearing Fatigue Life Tests of Two Advanced Base Oils for Space Applications Under Vacuum and Atmospheric Environments

Four series of rolling-element bearing fatigue tests were conducted with 51104 size thrust ball bearings with three balls made from SUJ2 (AISI 52100) steel lubricated with two advanced synthetic base oils used for space applications. The test lubricants were perfluoropolyether (PFPE) and multiply alkyated cyclopentane (MAC). Each oil was tested with bearings under vacuum and atmospheric environments. The bearings were tested at a maximum Hertzian stress of 4 GPa on the inner and outer races. The outer race was rotated at a speed of 250 rpm. A pool lubrication system was used. Fresh lubricant was used for each test bearing. Testing in vacuum conditions was at 5 × 10^?2 Pa. The test oils were analyzed to determine whether changes occurred as a result of operating in air and in a vacuum. In a vacuum environment, the PFPE 815Z oil exhibited a longer fatigue life than the MAC 2001A oil. However, in an air environment, the MAC 2001A oil had a longer L₁₀ fatigue life than the PFPE 815Z oil. The fatigue life tests of PFPE 815Z oil in vacuum resulted in a longer L₁₀ life than when tested in an air environment. In an air environment, hydrogen fluoride was generated in the bearing tests with the PFPE 815Z oils. Under vacuum conditions, hydrogen fluoride was not generated with the PFPE 815Z oil, resulting in longer bearing fatigue lives. The fatigue life tests of MAC 2001A oil in a vacuum resulted in shorter L₁₀ fatigue life than in an air environment. The shorter life was attributed to the lower elastohydrodynamic oil film formation with the MAC 2001A oil because of a higher operating temperature and decomposition of the oil in vacuum.     

基于循环提取有效信息的主轴承故障特征增强方法

针对航空发动机主轴承发生故障时特征信息提取不充分的问题,提出一种基于循环提取有效信息的主轴承故障特征增 强方法。 该方法首先对原始振动信号进行小波包分解,计算得到各个节点分量的相关系数值和峭度值,将其进行归一化融合为 一个综合参数 Pi;其次根据特征信息循环提取准则定义一个置信区间,该区间将所有节点分量划分为高信噪比信号、低信噪比 信号和高噪信号 3 个部分;然后不断筛选出高信噪比信号直至达到终止条件;最后重构所有高信噪比信号,并进行包络解调提 取出轴承微弱故障特征。 经仿真信号验证,去噪信号的信噪比相对于去噪前提升了 11. 31 dB。 基于航空发动机中介轴承模拟 试验台所测数据开展了特征信息循环提取方法有效性的综合验证,并对某型航空发动机主轴承振动信号进行了分析。 实践表 明:该方法适用于强背景噪声干扰工况下滚动轴承的特征提取,能准确诊断航空发动机主轴承故障。     

Effect of Silicon Nitride Balls and Rollers on Rolling Bearing Life

Three decades have passed since the introduction of silicon nitride rollers and balls into conventional rolling-element bearings. For a given applied load, the contact (Hertz) stress in a hybrid bearing will be higher than that of an all-steel rolling element bearing. The silicon nitride rolling-element life as well as the lives of the steel races were used to determine the resultant bearing life of both hybrid and all-steel bearings. Life factors were determined and reported for hybrid bearings. Under nominal operating speeds, the resultant calculated lives of the deep-groove, angular-contact, and cylindrical roller hybrid bearings with races made of post-1960 bearing steel increased by factors of 3.7, 3.2, and 5.5, respectively, from those calculated using the Lundberg-Palmgren equations. An all-steel bearing under the same load will have a longer life than the equivalent hybrid bearing under the same conditions. Under these conditions, hybrid bearings are predicted to have a lower fatigue life than all-steel bearings by 58% for deep-groove bearings, 41% for angular contact bearings, and 28% for cylindrical roller bearings.     

润滑油黏度对全陶瓷球轴承腔体温度场分布规律的影响

为揭示全陶瓷球轴承在油润滑条件下内部温度场分布及变化情况,提高全陶瓷球轴承的运转性能与使用寿命,以7007C氮化硅全陶瓷角接触球轴承为研究对象,利用仿真软件模拟分析不同工况和润滑油黏度条件下全陶瓷球轴承腔体内部温度场及润滑油的分布状态;在轴承寿命试验机上进行相同条件下全陶瓷球轴承的动态特性试验,研究在油润滑工况下全陶瓷球轴承的温升特性。结果表明：随着轴承转速的提高,全陶瓷球轴承腔体内温度呈增大趋势,腔体内润滑油体积分数呈减小趋势;更换不同黏度润滑油发现随着润滑油黏度的增大,全陶瓷球轴承腔体内温度场呈现先减小后增大的趋势,存在最优黏度值使全陶瓷球轴承腔体温度达到最小值,轴承服役性能表现最佳。研究成果为实际生产中全陶瓷球轴承最优润滑油的选择提供了技术参考。     

Effect of Rolling Bearing Refurbishment and Restoration on Bearing Life and Reliability

For nearly four decades it has been a practice in commercial and military aircraft application that rolling-element bearings removed at maintenance or overhaul be reworked and returned to service. The work presented extends previously reported bearing life analysis to consider the depth (Z₄₅) to maximum shear stress (τ₄₅) on stressed volume removal and the effect of replacing the rolling elements with a new set. A simple algebraic relationship was established to determine the L₁₀ life of bearing races subject to bearing rework. Depending on the extent of rework and based on theoretical analysis, representative life factors for bearings subject to rework ranged from 0.87 to 0.99% of the lives of new bearings. Based on bearing endurance data, 92% of the bearing sets that would be subject to rework would result in L₁₀ lives equaling and/or exceeding that predicted for new bearings, with the remaining 8% having the potential to achieve the analytically predicted life of new bearings when one of the rings is replaced at rework. The potential savings from bearing rework varies from 53 to 82% that of new bearings depending on the cost, size, and complexity of the bearing.     

Analysis of Thermoelastohydrodynamic Performance of Journal Misaligned Engine Main Bearings

To understand the engine maln bearings’ working condition is important in order to improve the performance of engine. However, thermal effects and thermal effect deformations of engine maln bearings ar...     

Surface roughness measurements as a method for tribological characterisation of ball bearings

A series of experiments using steel or hybrid balls in an SNFA VEX25 type bearing was conducted, at a rotational speed of 50,000 rpm. The race material was 100Cr6 steel, whereas for the balls various steels, coatings, and ceramics were used. The different materials used for the balls as well as the method of lubrication (air/oil or grease) strongly influenced the surface degradation of the ball bearings. Hybrid bearings with ceramic balls showed very little wear of either the balls or the steel races, and so offer potential for high‐speed applications. The degradation of the bearings was examined using scanning electron microscopy, atomic force microscopy, and laser scanning profilometry. The disadvantages and advantages of these methods are given, along with the results of surface roughness measurements.