機械設計與制造畢業(yè)設計論文中英文翻譯外文翻譯-機械設計-資料下載頁
2025-05-11 23:46本頁面
【導讀】承正常運轉(zhuǎn)的機會是能夠被提高的。在軸承的使用過程當中，過分的忽視會導致軸承的過。熱現(xiàn)象，也可能使軸承不能夠再被使用，甚至完全的破壞。通過一些細致的偵察工作，我們可以采取行動來避免軸承的再。摩擦系數(shù)和保持軸中心位置固定的機件。它的主要功能是支撐機械旋轉(zhuǎn)體，用以降低設備在傳動過程中的機械載荷摩擦系數(shù)。環(huán)境溫度適宜而且變化幅度不大，絕對無固體塵埃、有害氣體和水分侵入軸承，軸承的潤滑充分而又恰到好處，潤滑劑絕。材料達致電疲勞極限，產(chǎn)生疲勞剝落而無法繼續(xù)使用。難以根絕的軸承污染問題而發(fā)生磨損失效。種破壞稱為低荷振蝕。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。持緊密的接觸，并且對防止在設備運輸中產(chǎn)生的低荷振蝕也有幫助。銹是濕氣污染的一種形式，它的出現(xiàn)常常表明材料選擇不當。
【正文】 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. 11 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 in the grinding operation 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 (from 3 to 9), 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.
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