機械設計與制造畢業(yè)設計外文翻譯-機械設計-在線瀏覽
2025-03-24 06:07本頁面
【正文】 cated. 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． 6 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但 ABEC等級并不能反映其他軸承特性，如軸承圈質(zhì)量、粗糙度、噪聲等。 ABEC 標準只定義了諸如孔、外徑、振擺等尺寸公差。軸承每旋轉(zhuǎn)一周高頻不規(guī)則變化出現(xiàn) 60~300 次，它表明軸承上存在著密集的振痕或大面積的粗糙不平。 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。軸承每轉(zhuǎn)一周這種不規(guī)則變化可出現(xiàn) ~10次，它們是由各種干涉（例如 軸承圈滾道上的凹坑）引起的。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。 軸承缺陷可以通過其頻率特性進一步加以鑒定。 根據(jù)經(jīng)驗，觀察者可以根據(jù)聲音辨別出微小的缺陷。測量噪聲的單位為 anderon。 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。 噪聲是反映軸承質(zhì)量的一個指標。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。 一旦軸承受到污染，潤滑劑就要變質(zhì)，運行噪聲也隨之變大。 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。同樣，機床主軸只能容許最小的振擺，以保證切削精度 。 在工業(yè)中一般是根據(jù)具體的應用來選擇不同類型和精度等級的軸承。保持架的尺寸誤差和軸承圈與滾珠的偏心都會引起 NRR。因此，要根據(jù)不同的用途來選用潤滑劑。另外，不同的潤滑劑的噪聲特性也不一樣。 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。這可以在選用過程中通過考慮關(guān)鍵性能特征來實現(xiàn)。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。相比之下，帶狀
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