【正文】 Bearings fail for a number of reasons， but the most mon are misapplication，contamination， improper lubricant， shipping or handling damage， and misalignment. The problem is often not difficult to diagnose because a failed bearing usually leaves telltale signs about what went wrong． However， while a postmortem yields good information， it is better to avoid the process altogether by specifying the bearing correctly in The first place． To do this，it is useful to review the manufacturers sizing guidelines and operating characteristics for the selected bearing. Equally critical is a study of requirements for noise, torque, and runout, as well as possible exposure to contaminants, hostile liquids, and temperature extremes. This can provide further clues as to whether a bearing is right for a job. 1 Why bearings fail About 40% of ball bearing failures are caused by contamination from dust, dirt, shavings, and corrosion. Contamination also causes torque and noise problems, and is often the result of improper handling or the application environment． Fortunately, a bearing failure caused by environment or handling contamination is preventable， and a simple visual examination can easily identify the cause． Conducting a postmortem il1ustrates what to look for on a failed or failing bearing． Then， understanding the mechanism behind the failure, such as brinelling or fatigue, helps eliminate the source of the problem. Brinelling is one type of bearing failure easily avoided by proper handing and assembly. It is characterized by indentations in the bearing raceway caused by shock loading－ such as when a bearing is droppedor incorrect assembly. Brinelling usually occurs when loads exceed the material yield point(350,000 psi in SAE 52100 chrome steel)． It may also be caused by improper assembly, Which places a load across the races． Raceway dents also produce noise， vibration， and increased torque. A similar defect is a pattern of elliptical dents caused by balls vibrating between raceways while the bearing is not turning． This problem is called false brinelling. It occurs on equipment in transit or that vibrates when not in operation. In addition, debris created by false brinelling acts like an abrasive, further contaminating the bearing. Unlike brinelling, false binelling is often indicated by a reddish color from fretting corrosion in the lubricant. False brinelling is prevented by eliminating vibration sources and keeping the bearing well lubricated. Isolation pads on the equipment or a separate foundation may be required to reduce environmental vibration. Also a light preload on the bearing helps keep the balls and raceway in tight contact. Preloading also helps prevent false brinelling during transit. Seizures can be caused by a lack of internal clearance, improper lubrication, or excessive loading. Before seizing, excessive, friction and heat softens the bearing steel. Overheated bearings often change color， usually to blueblack or straw colored． Friction also causes stress in the retainer， which can break and hasten bearing failure． Premature material fatigue is caused by a high load or excessive preload． When these conditions are unavoidable， bearing life should be carefully calculated so that a maintenance scheme can be worked out． Another solution for fighting premature fatigue is changing material． When standard bearing materials， such as 440C or SAE 52100， do not guarantee sufficient life， specialty materials can be remended. In addition， when the problem is traced back to excessive loading， a higher capacity bearing or different configuration may be used． Creep is less mon than premature fatigue． In bearings． it is caused by excessive clearance between bore and shaft that allows the bore to rotate on the shaft． Creep can be expensive because it causes damage to other ponents in addition to the bearing． 0ther more likely creep indicators are scratches， scuff marks， or discoloration to shaft and bore． To prevent creep damage， the bearing housing and shaft fittings should be visually checked． Misalignment is related to creep in that it is mounting related． If races are misaligned or cocked． The balls track in a noncircumferencial path． The problem is incorrect mounting or tolerancing， or insufficient squareness of the bearing mounting site． Misalignment of more than 1/4不過，經(jīng)驗表明，穩(wěn)定的潤滑膜可以擴大他們之間的平行滑動面，一般由于某些機制，放寬一種或一種以上的對經(jīng)典理論的假設。 [ 11 ]實驗表明，增加一倍的承載能力為表面紋理設計的反應離子刻蝕碳化硅平行推力軸承滑動在水中。該本文件的目的是調查實驗模型的有效性所描述的檔號。這亦是有趣地注意到，從圖 2，我們看到用軟件仿真的部分表面微觀造型的優(yōu)勢。第二定子（二）是一個雙向定向版本的部分反演軸承有兩個平等的紋理部分 1/2，對每一項墊結束。 一個單臂反應壓力與負載單元相互作用，從而許可證的摩擦力矩測量阻止自由旋轉這個機架。然后最低的軸向載荷應用，供水閥打開及汽車開啟?？梢钥闯?，雙方間的協(xié)議模型和實驗是好的，與不同的不到 10 ％ ，只要負荷是 150 以上的 12 月31 日在較低載荷測量的實驗清拆要遠遠大于模型預測，尤其是在較高的速度， 3000 rpm的情況下，在 120 n實測關是 20 的 LM ，這是約 60 ％ ，高于預測值。轉子表面粗糙度仍然存在，原因，即 的 LM ?？梢钥闯觯瑥膱D 7 ，這個比例約三倍，贊成部分 第 1 軸承是保持在整個負荷范圍?？梢钥闯觯Σ料禂?shù)的兩個部分反演軸承是非常類似的與略低的價值觀，在部件較有高效率的單向軸承。診斷失效的原因并不困難，因為根據(jù)軸承上留下的痕跡可以確定軸承失效的原因。 只要使用和安裝合理，軸承的剝蝕是容易避免的。此外，低荷振蝕產(chǎn)生的碎屑的作用就象磨粒一樣，會進一步損害軸承。 消除振動源并保持良好的軸承潤滑可以防止低荷振蝕。剝蝕通常是在載荷超過材料屈服極限時發(fā)生的。為了做到這一點，再考察一下制造廠商的尺寸定位指南和所選軸承的使用特點是非常重要的。在 1500 RPM 的（圖 9 ）和最高負荷 460 n摩擦系數(shù)的 untextured軸承是約 ，約為第 1軸承 。在這種情況下，反演參數(shù) sp= α = 和 。比較是在兩種速度的 1500 和 3000 RPM 的。因此，假設油膜上，解決這一雷諾方程的標準形式。軸承的速度和水溫監(jiān)測整個測試的任何違規(guī)行為。感應探頭是附加到較低的持有人的定子，讓上線的測量清拆變化之間的轉子和定子由于水動力影響的原因軸向運動的房屋，其中定子持有人，這是 一個固定的。壓痕 深度 ，壓痕直徑 和壓痕面積密度 sp = 。 第三章 實驗 測試軸承組成燒結碳化硅磁盤 10 毫米厚，有八十 五毫米外徑和 40 毫米內徑。 第二章 背景 基本模型的橫截面用標準分析了 [ 12 ]是表現(xiàn)在圖 1。由于平行滑動他們的表現(xiàn)較差，比更先進的錐形或加強軸承。這些措施包括波紋形 [ 1 ]和凸起微粗糙 面 [ 24 ]。 insufficient lubrication between ball and retainer wears and weakens the retainer． In this situation， lubrication is critical if the retainer is a fully machined type． Ribbon or crown retainers， in contrast， allow lubricants to more easily reach all surfaces． Rust is a form of moisture c