微型轴承的失效模式及其对策

通过寿命试验揭示微型轴承的一种失效模式－－在边界润滑状态下，高速旋转轴承的粘着磨损和磨粒磨损，并探讨了目前常用的几种工程解决方案。     

航空发动机轴承失效模式分析

轴承寿命内失去其应有的使用性能，导致故障或不能正常工作的现象，称轴承失效。轴承的失效分为两类，止转失效和丧精失效。航空发动机轴承的失效模式主要有，滚动接触失效、开裂和断裂失效、旋转爬行失效、轴承磨损失效、塑性变形失效、微动磨损失效等。分析研究轴承的失效模式目的是为制定预防失效措施提供理论依据。     

航空发动机主轴轴承失效模式分析

航空发动机圆柱滚子主轴承常常因为工作条件恶劣,发生失效。采用光学显微镜、扫描电镜、能谱仪、X射线光电子能谱等对服役后的圆柱滚子轴承进行失效分析。结果表明:根据失效机制与微观形貌对失效模式,可以将圆柱滚子轴承的失效模式分为8种不同的失效模式,包括划伤和擦伤、打滑蹭伤、压坑凹坑、疲劳剥落、振纹、受热变色、内圈烧伤、保持架镀银层磨损。对打滑蹭伤、烧伤和保持架镀银层磨损等失效模式的轴承进行分析,结果表明:在打滑蹭伤的轴承表面发现O元素,表明打滑蹭伤过程中发生了氧化磨损;在烧伤轴承表面发现了Fe的氧化物FeO和Fe₂O₃,表明轴承在烧伤时温度较高,润滑油膜被破坏,滚子和内圈互相接触发生剧烈磨损;保持架表面银层脱落,部分磨损区域露出铜表面,表明保持架在服役过程中发生了摩擦磨损。     

混合型静压轴承

机床主轴运动精度的提高在很大程度上取决于轴承的性能,现在超精密轴承中静压轴承非常引人注目目。静压轴承即使在起动和停止时,轴和轴承间也无金属性接触,可以获得连续长期稳定工作的性能,但是,要想进一步提高可靠性,还必须防止润滑系统的故障及超载引起的烧伤,并采取相应的对策。     

新型空气静压轴承

随着科学技术的发展,轴承的种类也越来越多,如各种液体润滑轴承、液体静压轴承、固体润滑(如石墨、二硫化钼)轴承、磁力轴承以及空气或其它气体润滑轴承。现介绍空气静压轴承。空气轴承就是利用气体的粘性提高间隙中气体的压力,从而将物体悬浮起来的轴承。空气轴承分动压型、静压型和压膜型三种。动压型空气轴承的两个面相对移动,且间隙呈楔状,沿移动方向间隙逐渐变小,由于相对移动,气体因其粘性作用,被拖带压入楔形间隙中从而产生压     

航空发动机轴承失效模式分析

轴承寿命内失去其应有的使用性能,导致故障或不能正常工作的现象,称轴承失效.轴承的失效分为两类,止转失效和丧精失效.航空发动机轴承的失效模式主要有,滚动接触失效、开裂和断裂失效、旋转爬行失效、轴承磨损失效、塑性变形失效、微动磨损失效等.分析研究轴承的失效模式目的是为制定预防失效措施提供理论依据.     

圆锥滚子轴承终磨内滚道潜在失效模式分析

介绍了潜在失效模式分析方法,分析圆锥滚子轴承内圈终磨工序的潜在失效模式及失效后果,制定了合理的过程控制改进措施,有效降低了失效产生的几率,提高了产品质量.     

轴承倾斜微动磨损与失效分析

轴承的倾斜微动由径向微动和水平微动叠加而成,且水平微动分量的振幅大于径向振幅,叠加而成的倾斜微动振幅大,倾斜微动磨损速率高,产生光亮的磨损形态。基于案例分析,对轴承倾斜微动磨损的定义、产生机理、常见分布、磨损特征等进行了详细介绍,分析指出：倾斜微动磨损痕迹能够表明对磨件之间处于倾斜状态,对轴承运转姿态识别,工作载荷分布识别和失效分析具有重要意义。     

风电轴承失效模式研究进展

轴承是风电机组的关键部件,在恶劣工况下工作容易出现过早失效。首先,以风电机组的主轴、变桨与偏航、齿轮箱、发电机等轴承应用部位作为出发点,对风电轴承的应用形式进行了总结;其次,介绍了风电轴承的主要失效形式(微剥落、微动磨损、白蚀裂纹、电蚀)并对失效原因和解决措施进行了分析;然后,从研究方式的角度,阐述了有限元法与试验法的研究成果;最后,提出风电轴承力学特性的分析以及失效模式的形成机理研究有待进一步深入,后续研究应注重于建立考虑设计及装配参数的耦合动力学模型,并进行更完善的试验设计以深入分析轴承的失效机制。     

Analysis of hydrostatic thrust bearings under non-axisymmetric operation

Analyses of the pressure distribution, the load capacity and the lubricant flow rate for a laminar flow hydrostatic thrust bearing in a symmetrical operation are presented. In a symmetrical operation the supported surface rotates about an axis parallel to but offset from the bearing axis. These bearings are commonly used as circular saw guides in the forest products industry. Bearing pressure and load and the lubricant flow are strong functions of a non-dimensional bearing number λ, the film thickness variation ? and the bearing offset $\text{L}\text{?}$ from the rotation axis.     

On the wear and failure of high speed roller bearings

A laboratory bearing test rig was constructed to study wear and failure mechanisms in high speed roller bearings under different conditions of loading and lubrication. The design of the rig permitted three bearings to be tested simultaneously. A test run of 720 h duration was performed during which wear of the bearings was monitored using ferrography and atomic absorption oil analysis. Wear debris particles collected from the bearings by ferrography were studied with scanning electron microscopy using energy-dispersive X-ray analysis. The results of ferrography were correlated with the metallographic observations made on the worn bearings.It was found that for lightly loaded high speed roller bearings rolling contact fatigue including surface pitting is not a significant wear or failure mechanism. However, misalignment due to shaft deflection above a critical point cannot be tolerated. Wear of high speed engine bearings can successfully be monitored by ferrography but, as the wear condition accelerates, frequent oil sample collections are beneficial.     

Design of tilted hydrostatic thrust bearings

Hydrostatic bearings are usually designed to operate under parallel conditions, but structural and thermal deformations cause tilting of the pad. A semianalytical solution of the pressure equation is used. It is shown that tilting of hydrostatic thrust bearings gives rise to negative pressures and that cavitation may occur depending on the tilt parameter. The characteristic values of the bearing are found to be strong functions of the tilt parameter and of the bearing number.     

Abrasive wear of rolling bearings

Various mechanisms of microslip are discussed; abrasive wear is considered the most important. An equation to predict the wear rate of rolling bearings is presented, based on previous work, and illustrated by an example     

Ultrasonic motorized spindle with hydrostatic bearings

Ultrasonic and acoustic axial spindle oscillations improve the productivity and product quality in machining, reduce the cutting forces, and increase the tool life in the grinding, milling, and boring of structural components, including those made from materials that are hard to machine. Industrial prototypes of motorized spindles with axial spindle oscillations have been developed by specialists at Siberian Federal University and AO NPP Radiosvyaz and patented in Russia. These spindle units include contactless hydrostatic bearings, a resonant-frequency generator (a piezo generator for ultrasonic spindles and a hydromechanical generator for acoustic spindles), and a local concentrator for the spindle’s longitudinal intrinsic waves.     

Design of multirecess hydrostatic oil journal bearings

This paper presents computer generated design data in terms of load capacity and oil flow for multirecess hydrostatic journal bearings. The Reynolds equation for a finite bearing was solved on a high speed digital computer satisfying appropriate boundary conditions and using the finite difference method. Results for various L/D ratios, recess to bearing area ratios, number of recesses etc are presented for capillary and orifice compensated bearings.     

Manufacturing of cast monolithic hydrostatic journal bearings

In this work a self-compensating hydrostatic journal bearing design, which eliminates all but one precision-manufacturing step, was manufactured and tested. Novel manufacturing methods for different sizes are introduced. The bearing sensitivity to manufacturing errors was analyzed computationally using statistical methods. These results were used to show that the introduced manufacturing methods are more cost effective than the traditional precision manufacturing methods for hydrostatic bearings, even when the performance variation is taken into account. Manufactured bearings were tested and the experimental results were compared with theoretical results and satisfactory agreement was achieved.     

Eccentric operation of conical hydrostatic thrust bearings

A theoretical study of the behaviour of capillary-compensated annular recess conical hydrostatic thrust bearings under conditions of eccentricity and rotation is reported. The influence of aspect ratios, cone angles and resistance ratios on the static and dynamic characteristics is discussed.     

Modeling of hydrostatic bearings by electrical analogy

Models of various dynamic systems may be constructed by electrical analogy. As an example, the operation of an open hydrostatic guide is analyzed. The optimal relations between the dynamic parameters are established on the basis of modeling.     

Non-parallel operation of rectangular hydrostatic thrust bearings

A theoretical study of the behaviour of capillary-compensated rectangular hydrostatic thrust bearings with tilt and sliding was made. The influence of the aspect ratio on the load-carrying capacity, flow and stiffness and damping characteristics is discussed.