【正文】 。ABEC標準只定義了諸如孔、外徑、振擺等尺寸公差。中頻噪聲的特征是軸承每旋轉(zhuǎn)一周不規(guī)則變化出現(xiàn)10~60次。缺陷還可以根據(jù)軸承每轉(zhuǎn)動一周出現(xiàn)的不規(guī)則變化的次數(shù)加以鑒定。根據(jù)經(jīng)驗，觀察者可以根據(jù)聲音辨別出微小的缺陷。噪聲的分析是用安德遜計進行的，該儀器在軸承生產(chǎn)中可用來控制質(zhì)量，也可對失效的軸承進行分析。當污染物處于滾珠和軸承圈之間時，其作用和金屬表面之間的磨粒一樣，會使軸承磨損。在許多工業(yè)產(chǎn)品中，污染是不可避免的，因此常用密封或遮護裝置來保護軸承，使其免受灰塵或臟物的侵蝕。在工業(yè)中一般是根據(jù)具體的應(yīng)用來選擇不同類型和精度等級的軸承。因此，要根據(jù)不同的用途來選用潤滑劑。扭矩要求是由潤滑劑、保持架、軸承圈質(zhì)量（彎曲部分的圓度和表面加工質(zhì)量）以及是否使用密封或遮護裝置來決定。如果某一材料經(jīng)檢驗適合工作要求，那么防止生銹的最簡單的方法是給軸承包裝起來，直到安裝使用時才打開包裝。如果滾珠和保持架之間潤滑不良也會磨損并削弱保持架。軸承就會過早地失效。蠕動與安裝不正有關(guān)。軸承的蠕動是由于軸和內(nèi)圈之間的間隙過大造成的。另一個解決辦法是更換材料。過熱的軸承通常會改變顏色，一般會變成藍黑色或淡黃色。給設(shè)備加隔離墊或?qū)Φ鬃M行隔離可以減輕環(huán)境的振動。這種破壞在運輸中的設(shè)備和不工作時仍振動的設(shè)備中都會產(chǎn)生。如果安裝不正確從而使某一載荷橫穿軸承圈也會產(chǎn)生剝蝕。弄清諸如剝蝕和疲勞破壞一類失效的機理，有助于消除問題的根源。在球軸承的失效中約有40%是由灰塵、臟物、碎屑的污染以及腐蝕造成的。導致軸承失效的原因很多，但常見的是不正確的使用、污染、潤滑劑使用不當、裝卸或搬運時的損傷及安裝誤差等。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 contamination and often indicates the wrong material for the application．If the material checks out for the job，the easiest way to prevent rust is to keep bearings in their packaging，until just before installation．2. Avoiding failuresThe best way to handle bearing failures is to avoid them．This can be done in the selection process by recognizing critical performance characteristics．These include noise，starting and running torque，stiffness，nonrepetitive runout，and radial and axial play．In some applications, these items are so critical that specifying an ABEC level alone is not sufficient．Torque requirements are determined by the lubricant，retainer，raceway quality(roundness cross curvature and surface finish)，and whether seals or shields are used．Lubricant viscosity must be selected carefully because inappropriate lubricant，especially in miniature bearings，causes excessive torque．Also，different lubricants have varying noise characteristics that should be matched to the application. For example，greases produce more noise than oil．Nonrepetitive runout(NRR)occurs during rotation as a random eccentricity between the inner and outer races，much like a cam action．NRR can be caused by retainer tolerance or eccentricities of the raceways and balls．Unlike repetitive runout, no pensation can be made for NRR.NRR is reflected in the cost of the bearing．It is mon in the industry to provide different bearing types and grades for specific applications．For example，a bearing with an NRR of less than is used when minimal runout is needed，such as in disk—drive spindle motors．Similarly，machine—tool spindles tolerate only minimal deflections to maintain precision cuts．Consequently, bearings are manufactured with low NRR just for machinetool applications．Contamination is unavoidable in many industrial products，and shields and seals are monly used to protect bearings from dust and dirt．However，a perfect bearing seal is not possible because of the movement between inner and outer races．Consequently，lubrication migration and contamination are always problems．Once a bearing is contaminated, its lubricant deteriorates and operation bees noisier．If it overheats，the bearing can seize．At the very least，contamination causes wear as it works between balls and the raceway，being imbedded in the races and acting as an abrasive between metal surfaces．Fending off dirt with seals and shields illustrates some methods for controlling contamination．Noise is as an indicator of bearing quality．Various noise grades have been developed to classify bearing performance capabilities．Noise analysis is done with an Anderonmeter, which is used for quality control in bearing production and also when failed bearings are returned for analysis. A transducer is attached to the outer ring and the inner race is turned at 1,800rpm on an air spindle. Noise is measured in andirons, which represent ball displacement in μm/rad.With experience, inspectors can identify the smallest flaw from their sound. Dust, for example, makes an irregular crackling. Ball scratches make a consistent popping and are the most difficult to identify. Innerrace damage is normally a constant highpitched noise, while a damaged outer race makes an intermittent sound as it rotates.Bearing defects are further identified by their frequencies. Generally, defects are separated into low, medium, and high wavelengths. Defects are also referenced to the number of irregularities per revolution.Lowband noise is the effect of longwavelength irregularities that occur about to 10 times per revolution. These are caused by a variety of inconsistencies, such as pockets in the race. Detectable pockets are manufacturing flaws and result when the race is mounted too tightly in multiplejaw chucks.Mediumhand noise is characterized by irregularities that occur 10 to 60 times per revolution. It is caused by vibration that produces balls and raceways. Highhand irregularities occur at 60 to 300 times per revolution and indicate closely spaced chatter marks or widely spaced, rough irregularities.Classifying bearings by their noise characteristics allows users to specify a noise grade in addition to the ABEC standards used by most manufacturers. ABEC defines physical tolerances such as bore, outer diameter, and runout. As the ABEC class number increase, tolerances are tightened. ABEC class, however, does not specify other bearing characteristics such as raceway quality, finish, or noise. Hence, a noise classification helps improve on the industry standard.中文翻譯 自然界苛刻的工作條件會導致軸承的失效，但是如果遵循一些簡單的規(guī)則，軸承正常運轉(zhuǎn)的機會是能夠被提高的。尤其在課題設(shè)計的前期準備階段，韓老師提出許多寶貴的設(shè)計意見，在最后的測試修改階韓老師在百忙之中抽出時間為我們提供了必要的幫助，這樣使得我們