滾動(dòng)軸承故障診斷的基本方法及故障診斷理論畢業(yè)設(shè)計(jì)

滾動(dòng)軸承故障診斷的基本方法及故障診斷理論畢業(yè)設(shè)計(jì),滾動(dòng)軸承,故障診斷,基本,方法,法子,理論,畢業(yè)設(shè)計(jì) 英 文 翻 譯學(xué)生姓名：學(xué) 號：專業(yè)班級：學(xué) 部：指導(dǎo)教師：- 1 -第一章 緒論1.1 本課題研究的主要意義機(jī)械故障診斷技術(shù)是近 40年來發(fā)展起來的識(shí)別機(jī)器或機(jī)組運(yùn)行狀態(tài)的科學(xué)。它是適應(yīng)工程實(shí)際需要而形成的多學(xué)科交叉的綜合學(xué)科。它研究的是機(jī)器或機(jī)組運(yùn)行狀態(tài)的變化在診斷信息中的反映，它是由機(jī)器運(yùn)行中的物理現(xiàn)象（聲音、振動(dòng)、聲發(fā)射、熱現(xiàn)象等）出發(fā)來推斷機(jī)器內(nèi)含故障的技術(shù)，是一種典型的反向工程。從 20世紀(jì) 60年代開始，機(jī)械故障診斷技術(shù)隨著機(jī)器的不斷完善、復(fù)雜化和自動(dòng)化組建發(fā)展起來，并與當(dāng)代科技的前沿科學(xué)結(jié)合，取得了令人矚目的成績。滾動(dòng)軸承是各種旋轉(zhuǎn)機(jī)械中應(yīng)用最廣泛的一種通用部件，也是機(jī)械設(shè)備中的易損零件，許多機(jī)械的故障都與滾動(dòng)軸承的狀態(tài)有關(guān)。據(jù)統(tǒng)計(jì)，在使用滾動(dòng)軸承的旋轉(zhuǎn)機(jī)械中，大約 30％的機(jī)械故障是由于滾動(dòng)軸承的損壞造成的。可見，滾動(dòng)軸承的好壞對機(jī)械系統(tǒng)工作狀況的影響極大。由于設(shè)計(jì)不當(dāng)和安裝工藝不好或軸承的使用條件不佳，或突發(fā)載荷的影響，使軸承運(yùn)轉(zhuǎn)一段時(shí)間后會(huì)產(chǎn)生各種各樣的缺陷，并且在繼續(xù)運(yùn)行中進(jìn)一步擴(kuò)大，使軸承運(yùn)行狀態(tài)發(fā)生變化。因此，滾動(dòng)軸承的故障診斷一直是研究的熱點(diǎn)。而與其它零部件相比，滾動(dòng)軸承有一個(gè)很大的特點(diǎn)，這就是其壽命離散性很大。由于在材料、加工精度、熱處理及裝配質(zhì)量等各方面不可能完全相同，使得一批類型、尺寸相同的軸承，即使在相同條件下工作，各個(gè)軸承的壽命也是不同的，壽命最大相差可達(dá)幾十倍。由于軸承的這個(gè)特點(diǎn)，在實(shí)際使用中就出現(xiàn)這種情況：有的軸承已大大超過設(shè)計(jì)壽命卻依然完好地工作；有的軸承遠(yuǎn)未達(dá)到設(shè)計(jì)壽命就出現(xiàn)故障。所以，如果按照設(shè)計(jì)壽命對軸承進(jìn)行定時(shí)維修，則出現(xiàn)以下情形：一方面，對超過設(shè)計(jì)壽命而完好工作的軸承拆下來作為報(bào)廢處理，造成浪費(fèi)；另一方面，未達(dá)到設(shè)計(jì)壽命而出現(xiàn)故障的軸承堅(jiān)持到定時(shí)維修時(shí)拆下來報(bào)廢，使得機(jī)械在軸承出現(xiàn)故障后和拆下來這段時(shí)間內(nèi)工作精度下降，未到維修時(shí)間就出現(xiàn)故障，導(dǎo)致整個(gè)機(jī)械出現(xiàn)嚴(yán)重事故。由此看來，對重要用途的軸承來說定時(shí)維修是很不科學(xué)的，要進(jìn)行工況監(jiān)測與故障診斷，改傳統(tǒng)的定期維修為預(yù)知性維修，這樣既能經(jīng)常保持設(shè)備的完好狀態(tài)，又能充分利用軸承的使用壽命，從而延長大修時(shí)間，縮短大修時(shí)間，減少故障停機(jī)損失。因此，滾動(dòng)軸承的工況監(jiān)測與故障診斷引起國內(nèi)外許多科技人員的重視。- 2 -1.2 滾動(dòng)軸承故障診斷方法滾動(dòng)軸承的工況監(jiān)測與故障診斷就是通過對滾動(dòng)軸承在各種工況下表現(xiàn)出來的振動(dòng)、噪聲、溫度、工作參數(shù)、氣味、泄漏等信息的監(jiān)測和綜合分析來對其工作狀態(tài)、故障類型和故障嚴(yán)重程度進(jìn)行綜合評價(jià)的過程，主要包括檢測試驗(yàn)技術(shù)、信號處理技術(shù)、模式識(shí)別技術(shù)和預(yù)測評估技術(shù) 4項(xiàng)基本技術(shù)，從而實(shí)現(xiàn)檢測和發(fā)現(xiàn)異常、診斷故障狀態(tài)和部位、分析故障類型、提出診斷方案和診斷結(jié)論的目的。目前，根據(jù)故障監(jiān)測和診斷技術(shù)機(jī)理的不同，滾動(dòng)軸承的故障診斷技術(shù)主要包括：1. 振動(dòng)信號監(jiān)測診斷技術(shù)在各種軸承故障診斷方法中，振動(dòng)檢測是最常用的一種方法。軸承元件的工作表面出現(xiàn)疲勞剝落、壓痕或局部腐蝕時(shí)，軸承運(yùn)行中會(huì)出現(xiàn)周期性的脈沖信號。這種周期性信號可由安裝在軸承座上的傳感器(速度型或加速度型)來接收，通過對振動(dòng)信號的分析就可以實(shí)現(xiàn)對滾動(dòng)軸承運(yùn)行狀態(tài)的監(jiān)測與診斷。2. 噪聲信號監(jiān)測診斷技術(shù)這種方法是通過滾動(dòng)軸承在運(yùn)行過程中的噪聲來判斷其故障。用噪聲法進(jìn)行軸承的故障檢測，優(yōu)點(diǎn)是不必接觸受測軸承就可得到檢測信號；其弊端就是很難從周圍環(huán)境的各種雜音中分離出軸承異常的聲音信號。所以，噪聲法一般很少被采用。但成功的例子也是有的，就是在方向性強(qiáng)的拋物線型音響器上安裝傳聲器，收集軸承發(fā)出的聲音信號，并用反向?yàn)V波器排除其它雜音，檢測出軸承異音。3. 溫度信號監(jiān)測診斷技術(shù)通過安裝在軸承座(或箱體)處的溫度傳感器監(jiān)測溫度，判斷軸承工作是否正常。溫度監(jiān)測對軸承載荷、速度和潤滑情況的變化反映比較敏感，尤其是對潤滑不良而引起的軸承過熱現(xiàn)象很敏感。所以，由于這種場合比較有效。但是，當(dāng)軸承出現(xiàn)諸如早期點(diǎn)蝕、剝落、輕微磨損等比較微小的故障時(shí)，溫度監(jiān)測基本上沒有反映，只是當(dāng)故障達(dá)到一定的嚴(yán)重程度時(shí)，用這種方法才能監(jiān)測到。所以，溫度監(jiān)測不適用于點(diǎn)蝕、局部剝落等所謂的局部損傷類故障。4. 油樣分析監(jiān)測診斷技術(shù)油樣分析法油樣分析法有光譜分析與鐵譜分析兩大類。軸承磨損顆粒與其工作狀況有密切的聯(lián)系。光譜分析方法有多種，但共同點(diǎn)是利用光譜分析，測定油液中所含各種金屬元素的成分和含量，以判斷含有被測元素的零部件的磨損狀況和程度。鐵譜分析方法是將帶有磨損顆粒的潤滑油通過一強(qiáng)磁場，在強(qiáng)磁場的作用下，磨粒- 3 -按一定的規(guī)律沉淀在鐵譜片上，鐵譜片可在鐵譜顯微鏡上做定性觀察或在定量儀器上測試，據(jù)此判斷軸承的工作狀況。油樣分析法適合于用潤滑油潤滑的軸承的故障診斷，對使用脂潤滑的軸承較困難。另外，這種方法易受其它非軸承損壞掉下的顆粒的影響；多用于離線監(jiān)測方式，這樣會(huì)導(dǎo)致一定信息丟失；信息量大且雜，即有圖像又有數(shù)字，依靠人力來管理是十分困難的。所以，這種方法具有很大的局限性。5. 油膜電阻監(jiān)測診斷技術(shù)潤滑良好的軸承，由于油膜的作用，內(nèi)、外圈之間有很大的電阻。故通過測量軸承內(nèi)、外圈之間的電阻，可對軸承的異常作出判斷。其特點(diǎn)是對不同的工況條件可使用同一評判標(biāo)準(zhǔn)，適用于旋轉(zhuǎn)軸外露的場合，對表面剝落、壓痕、裂紋等異常的診斷效果比較差。隨著科學(xué)技術(shù)的不斷發(fā)展，一些新的監(jiān)測技術(shù)不斷出現(xiàn)并應(yīng)用于滾動(dòng)軸承的工況監(jiān)測與診斷中，例如：聲發(fā)射技術(shù)、光纖技術(shù)等。但是由于種種原因和局限性，這些技術(shù)真正普及應(yīng)用于實(shí)際的滾動(dòng)軸承故障診斷還有一段距離。1.3 滾動(dòng)軸承故障診斷技術(shù)的發(fā)展概況滾動(dòng)軸承的故障診斷技術(shù)大概開始于 20世紀(jì) 60年代。最原始的軸承故障診斷方法是將聽音棒接觸軸承部位，依靠聽覺來判斷有無故障。后來逐步采用各式測振儀器、儀表并利用振動(dòng)位移、速度或加速度的均方根值來判斷軸承有無故障。隨著對滾動(dòng)軸承的運(yùn)動(dòng)學(xué)、動(dòng)力學(xué)的深入研究，對于軸承振動(dòng)信號中頻率成分和軸承零件的幾何尺寸及缺陷類型的關(guān)系有了比較清楚的了解，加之快速傅立葉變換(FFT)技術(shù)的發(fā)展，開創(chuàng)了用頻域分析法來檢測和診斷軸承故障的有效途徑。在幾十年的發(fā)展時(shí)間里，各種方法與技巧不斷產(chǎn)生、發(fā)展和完善，應(yīng)用的領(lǐng)域不斷擴(kuò)大，診斷的有效性不斷提高.總的來說，滾動(dòng)軸承故障診斷的發(fā)展經(jīng)歷了以下幾個(gè)階段：第一階段：利用低頻信號接收法診斷階段20世紀(jì) 60年代中期，由于快速傅立葉變換(FFT)技術(shù)的出現(xiàn)(1965 年)和發(fā)展，低頻信號接收法得到了很大的發(fā)展。低頻信號接收法是將軸承上由傳感器檢測到的寬頻信號直接進(jìn)行頻譜分析，或者信號經(jīng)過低通濾波，去除高頻成分后在作頻譜分析，從頻譜上觀察主要譜峰。如果某一譜峰對應(yīng)的頻率與理論計(jì)算軸承元件的間隔頻率相一致，則表示該元件上存在故障。這種方法對于低頻成分能量較大，外來干擾較小的信號，理論上說應(yīng)該是可行的，但實(shí)際運(yùn)行中的軸承，因?yàn)楣收蠜_擊的能量很小，而軸承、齒輪的工藝誤差誘發(fā)的振動(dòng)能量比它要大得多。因此，直接利用- 4 -低頻信號接收法得到的譜圖往往譜線密集，模糊不清，很難鑒別出故障信號。目前很少直接用這種方法去識(shí)別軸承故障，有些僅是用這種頻譜來確定軸承元件的固有頻率。第二階段：利用沖擊脈沖法診斷階段在 60年代末期，首先由瑞典 SPM儀器公司開發(fā)出沖擊脈沖計(jì)，根據(jù)沖擊脈沖的最大幅值來診斷軸承故障。滾動(dòng)軸承在運(yùn)轉(zhuǎn)中，如果滾動(dòng)體接觸點(diǎn)進(jìn)入表面缺陷區(qū)（剝落、裂紋、凹坑和高低不平的粗糙區(qū)） ，就將發(fā)生低頻沖擊，并且以不連續(xù)的沖擊脈沖波形式傳遞到軸承座上。雖然沖擊脈沖波形很快被衰減下去，累積的能量很小。然而，在這個(gè)沖擊力作用下，軸承元件或結(jié)構(gòu)的某一部分可能被激發(fā)起它的固有頻率。盡管沖擊脈沖的重復(fù)頻率遠(yuǎn)低于軸承的固有頻率，但只要這個(gè)沖擊產(chǎn)生的高階頻率落在軸承固有頻率的通帶內(nèi)，也會(huì)激起軸承系統(tǒng)的共振現(xiàn)象。共振的高頻波中包含了低頻沖擊和隨機(jī)干擾的幅值調(diào)制波，經(jīng)過窄帶濾波和包絡(luò)檢波后的信號幅值大小就反映了沖擊力的大小，也就反應(yīng)了滾動(dòng)軸承工作表面的故障狀況。第三階段：利用共振解調(diào)法診斷階段共振解調(diào)法也稱為包絡(luò)檢波頻譜分析法。1974 年，美國波音公司的 DR Harting發(fā)明了一項(xiàng)叫做“共振解調(diào)分析系統(tǒng)”的專利，這就是我國現(xiàn)在統(tǒng)稱的“共振解調(diào)技術(shù)”的雛形。共振解調(diào)法與沖擊脈沖法的基本原理類似，但能做到更精確的診斷。沖擊脈沖法只能給出軸承損傷程度的指標(biāo)，一般來說并不能判斷軸承的損傷部位；而共振解調(diào)法不僅能判斷軸承的損傷程度，還可以通過頻譜分析指示出軸承的損傷部位。共振解調(diào)法也是利用軸承或檢波系統(tǒng)作為諧振體，把故障沖擊產(chǎn)生的高頻共振響應(yīng)波放大，通過包絡(luò)檢測方法變?yōu)榫哂泄收咸卣餍畔⒌牡皖l波形，然后采用頻譜分析法找出故障的特征頻率（間隔頻率） ，從而確定故障的類型以及故障發(fā)生在軸承的哪一元件上。共振解調(diào)法適用于軸承故障的早期診斷。因?yàn)樵缙诠收戏浅］p微，它引起的沖擊脈沖強(qiáng)度非常小，所以其振動(dòng)響應(yīng)信號的故障特征很不明顯，用一般方法很難辨別出來。采用共振解調(diào)技術(shù)由于放大(諧振)和分離(帶通濾波)了故障特征信號，極大地提高了信噪比，所以能比較容易地診斷出故障來。第四階段：開發(fā)以微機(jī)為中心的滾動(dòng)軸承故障診斷系統(tǒng)階段20世紀(jì) 90年代以來，隨著微機(jī)技術(shù)迅猛發(fā)展，開發(fā)以微機(jī)為中心的滾動(dòng)軸承故障診斷系統(tǒng)引起了國內(nèi)外研究者的重視。微機(jī)信號分析和故障診斷系統(tǒng)不但具有靈活性高，適應(yīng)性強(qiáng)，易于維護(hù)和升級的特點(diǎn)，而且易于推廣和應(yīng)用。- 5 -1.4 滾動(dòng)軸承故障診斷技術(shù)的發(fā)展方向近些年，故障診斷的新技術(shù)和新方法層出不窮，人工智能和計(jì)算機(jī)在軸承故障診斷中的應(yīng)用越來越廣泛，今后的發(fā)展方向主要體現(xiàn)在以下方面：1. 時(shí)域分析和頻譜分析在軸承故障診斷中的應(yīng)用將日趨完善；2. 對于軸承故障診斷的理論和方法進(jìn)一步深入研究，并且各種研究成果將會(huì)逐步應(yīng)用到實(shí)際生產(chǎn)；3. 故障診斷智能系統(tǒng)進(jìn)一步的深入研究，多種軸承故障分析方法相結(jié)合，如小波神經(jīng)網(wǎng)絡(luò)、模糊識(shí)別與小波分析相結(jié)合等新分析方法應(yīng)用智能專家系統(tǒng)，提高診斷的效率和準(zhǔn)確率；4. 隨著計(jì)算機(jī)和網(wǎng)絡(luò)技術(shù)的發(fā)展，遠(yuǎn)程故障診斷將是現(xiàn)代故障診斷發(fā)展的一個(gè)重要的方向。1.5 本課題主要研究內(nèi)容本文分析研究了滾動(dòng)軸承的常見失效形式及其特征，總結(jié)滾動(dòng)軸承的振動(dòng)機(jī)理和振動(dòng)信號特點(diǎn)，研究了滾動(dòng)軸承信號處理及故障診斷的方法，搭建了滾動(dòng)軸承故障診斷系統(tǒng)，采用較為先進(jìn)、成熟的故障診斷方法，對滾動(dòng)軸承進(jìn)行故障診斷。本文的主要內(nèi)容如下:第一章：緒論。簡要介紹了本課題研究的意義、滾動(dòng)軸承故障診斷方法、滾動(dòng)軸承故障診斷技術(shù)發(fā)展概況、發(fā)展方向。第二章：滾動(dòng)軸承的故障特征分析。分析滾動(dòng)軸承的主要失效形式和原因，分析計(jì)算滾動(dòng)軸承的理論特征頻率和固有振動(dòng)頻率，研究滾動(dòng)軸承的故障信號特征。第三章：滾動(dòng)軸承故障診斷方法研究。包括時(shí)域方法、頻域方法，對各種方法的特點(diǎn)進(jìn)行了比較。第四章：滾動(dòng)軸承故障診斷系統(tǒng)總體設(shè)計(jì)。在滾動(dòng)軸承故障診斷方法理論的基礎(chǔ)上搭建基于 Matlab的滾動(dòng)軸承故障診斷系統(tǒng)，對軟件系統(tǒng)進(jìn)行總體設(shè)計(jì)。第五章：滾動(dòng)軸承實(shí)測信號分析。通過對采集的滾動(dòng)軸承實(shí)測信號分析，驗(yàn)證各種診斷方法的優(yōu)劣和滾動(dòng)軸承的故障特征。- 6 -第二章 滾動(dòng)軸承的故障特征分析2.1 概述滾動(dòng)軸承是旋轉(zhuǎn)機(jī)械中的重要零件，它在各個(gè)機(jī)械部門中的應(yīng)用最為廣泛。它的運(yùn)行質(zhì)量直接影響整臺(tái)設(shè)備的工作性能（包括精度，可靠性，壽命等） 。一般來說對滾動(dòng)軸承采用以設(shè)計(jì)壽命為限的定時(shí)進(jìn)行維修。但是，如前文所述這種維修制度會(huì)對設(shè)備的連續(xù)運(yùn)行帶來一定的影響。一方面，對超過設(shè)計(jì)壽命而運(yùn)行完好的滾動(dòng)軸承拆下來作報(bào)廢處理，造成浪費(fèi)；另一方面，已處于失效狀態(tài)的軸承繼續(xù)使用會(huì)造成整機(jī)運(yùn)行性能的下降，甚至?xí)劤蓢?yán)重的事故。因此必須加強(qiáng)滾動(dòng)軸承的監(jiān)測工作，改傳統(tǒng)的定期維修為預(yù)知性維修，最大限度地發(fā)揮軸承的工作潛力，提高設(shè)備的運(yùn)行效率。2.2 滾動(dòng)軸承的典型結(jié)構(gòu)滾動(dòng)軸承是有內(nèi)圈、外圈、滾動(dòng)體和保持架等元件組成。內(nèi)圈、外圈分別與軸頸及軸承座孔裝備在一起。在大多數(shù)情況下外圈不動(dòng)，而內(nèi)圈隨軸回轉(zhuǎn)。滾動(dòng)體是滾動(dòng)軸承的核心元件，它使相對運(yùn)動(dòng)表面間的滑動(dòng)摩擦變?yōu)闈L動(dòng)摩擦。滾動(dòng)體的形式有球形、圓形、錐柱形和鼓形等。滾動(dòng)體可在內(nèi)、外圈滾道上進(jìn)行滾動(dòng)。2.3 滾動(dòng)軸承的主要失效形式及原因由于滾動(dòng)軸承的材料缺陷，加工或裝配不當(dāng)，潤滑不良，水份和異物侵入，腐蝕以及過載等原因都可能導(dǎo)致早期損壞。當(dāng)然，即使在安裝、潤滑和使用維護(hù)都正常的情況下，經(jīng)過一段時(shí)間的運(yùn)轉(zhuǎn)，軸承也會(huì)出現(xiàn)疲勞剝落和磨損等現(xiàn)象影響機(jī)器的正常工作。概括起來滾動(dòng)軸承的主要故障形式有:1. 塑性變形軸承轉(zhuǎn)速 時(shí)，其損壞形式主要失效形式是塑性變形，這與接觸min1r?表面的最大擠壓應(yīng)力有關(guān)（如工作負(fù)荷過重，熱變形影響，過大的沖擊載荷等） 。按彈性理論分析，接觸表面的最大擠壓應(yīng)力發(fā)生在受力最大的一個(gè)滾動(dòng)體與軸承內(nèi)圈的接觸點(diǎn)處，其損壞的特征是滾道上形成一個(gè)個(gè)小圓穴（凹痕） ，使軸承在運(yùn)轉(zhuǎn)時(shí)產(chǎn)生很大的振動(dòng)和噪聲。2. 疲勞剝落- 7 -滾動(dòng)體在滾道上由于反復(fù)承受載荷，工作到一定時(shí)間后，首先在接觸表面一定深度處形成裂紋（該處的切應(yīng)力最大） ，然后逐漸發(fā)展到接觸表面，使表層金屬呈片狀剝落下來，形成剝落凹坑，即形成疲勞剝落。疲勞剝落使軸承在工作時(shí)發(fā)生沖擊性振動(dòng)。在正常工作條件下，疲勞剝落是軸承的主要失效形式。3. 磨損或擦傷滾動(dòng)體與滾道之間的相對運(yùn)動(dòng)以及外界污物的侵入，是軸承工作表面產(chǎn)生磨損的直接原因。潤滑不良，裝配不正確均會(huì)加劇磨損或擦傷。磨損量較大時(shí)，軸承游隙增大，不僅降低了軸承的運(yùn)轉(zhuǎn)精度，也會(huì)帶來機(jī)器的振動(dòng)和噪聲，對精密機(jī)械用的軸承，磨損量就成為決定軸承使用壽命的主要因素。4. 銹蝕和電蝕銹蝕是由于空氣中或外界的水分帶入軸承中，或者機(jī)器在腐蝕性介質(zhì)中工作，軸承密封不嚴(yán)，從而引起化學(xué)腐蝕。銹蝕產(chǎn)生的銹斑使軸承工作表面產(chǎn)生早期剝落，而端面生銹則會(huì)引起保持架磨損。電蝕主要是轉(zhuǎn)子帶電，在一定條件下，電流擊穿油膜產(chǎn)生電火花放電，使軸承工作表面形成密集的電流凹坑。5. 斷裂軸承零件的裂紋和斷裂是最危險(xiǎn)的一種失效形式，這主要是由于軸承超負(fù)荷運(yùn)行、金屬材料有缺陷和熱處理不良引起的。轉(zhuǎn)速越高，潤滑不良，軸承在軸上壓配過盈量太大以及過大的熱應(yīng)力會(huì)引起裂紋和斷裂。6. 膠合膠合指滾道和滾動(dòng)體表面由于受熱而局部融合在一起的現(xiàn)象。常發(fā)生在潤滑不良、高速、重載、高溫、起動(dòng)加速度過大等情況下。由于摩擦發(fā)熱，軸承零件可以在極短時(shí)間內(nèi)達(dá)到很高的溫度，導(dǎo)致表面灼傷，或某處表面上的金屬粘附到另一表面上。7. 保持架損壞通常，由于裝配或使用不當(dāng)而引起保持架發(fā)生變形，從而就可能增加保持架與滾動(dòng)體之間的摩擦，甚至使某些滾動(dòng)體卡死而不能滾動(dòng)，或者由于保持架與內(nèi)外滾道發(fā)生摩擦等均可能引發(fā)保持架損壞，導(dǎo)致振動(dòng)、噪聲與發(fā)熱增加。- 8 -Chapter I Introduction1.1 The main significance of this researchMachinery fault diagnosis technology has developed to identify scientific machine or running state in nearly 40 years. It is to adapt to the need of the actual engineering and the formation of interdisciplinary comprehensive discipline. What it studies is the machine or the unit running status change in the diagnostic message reflection. It is the technology by the machine run in physical phenomenon (sound, vibration, sound launch, hot phenomenon and so on) embarks infers the machine content breakdown and is one kind of typical reverse engineering. Started from the 1960s, along with the machine consummates, the complication and the automation unceasingly the mechanical fault diagnosis technology has developed, and with the contemporary science's and technology's front science union, has made the amazing progress.The rolling bearing is one kind of general part in each kind of revolving machinery applies. Rolling element bearing is one of the most widely used general part of rotating machinery,and one of the most easily damaged parts of mechanical equipment. A lot of mechanical failure is relevant to the state of rolling element bearings. It is estimated that about 30 percent of mechanical failure is caused by its fault in the rotating machine with rolling element bearings. It is obvious that the quality of rolling element bearings has a great impact on the working condition of electromechanical systems. Because of wrong design, poor working condition or a jump heavy load, bearing will be damaged and worse during the running time. So at present, the fault diagnosis of rolling element bearings is a research hotspot.But compares with other spare parts, the rolling bearing has a very major characteristic, this is its life leaves the divergence to be very big. Because in the material, the working accuracy, the heat treatment and the assembly quality and so on various aspects is impossible identical, causes one batch of types, the size same bearing, even if works under the same condition, life is different for each bearing, and difference up dozens of times. As a result of bearing's this characteristic, it has this - 9 -kind of situation in the actual use: Some bearings have significantly exceeded design life and work is still intact; some bearings have not achieved the design life to present the breakdown. Therefore, if carries on according to the design life to the bearing fixed time services, then has the following situation: On the one hand, the bearing surpasses the design life, but works complete the bearing opens down takes abandonment processing, creates the waste; On the other hand, the bearing has not achieved the design life to present the breakdown to insist fixed time services when dismantles the incoming telegram to be waste, causes the machinery after the bearing presents the breakdown and opens down in this period of time to work the precision to drop, has not presented the breakdown to the maintenance time, causes the entire machinery to present the serious accident. Therefore, to the important use's bearing settled when the service is very unscientific, must carry on the operating mode monitor and the failure diagnosis, changes traditional the regular service is the forecasting service, like this both can maintain equipment's sound condition frequently, and can use bearing's service life fully, thus the extension overhaul time, reduces the overhaul time, reduces the disaster dump to lose. Therefore, rolling bearing's operating mode monitor and the failure diagnosis bring to the domestic and foreign many technical personnel's attention.1.2 Rolling bearing failure diagnosis methodRolling bearing's operating mode monitor and the failure diagnosis are through to the rolling bearing information and so on vibration which, noise, temperature, operational parameter, smell, divulging displays under each kind of operating mode monitors and the generalized analysis to its active status, the breakdown type and the breakdown order of severity carry on the quality synthetic evaluation the process, mainly includes the examination experiment technology, the signal processing technology, the pattern recognition technology and the forecast appraisal technology 4 basic strokes, thus realizes the examination and the discovery exceptionally, the diagnosis malfunction and the spot, the analysis breakdown type, proposes the diagnosis plan and the diagnosis conclusion goal.- 10 -At present, according to the breakdown monitor and the diagnosis technology mechanism's difference, rolling bearing's failure diagnosis technology mainly includes:1. Vibration signal monitor diagnosis technologyIn each bearing failure diagnosis method, the vibration examination is the most commonly used one method. When the bearing part's active face presents weary flaking, the indentation or the localized corrosion, in the bearing movement will present the periodic signal impulse. This kind of periodic signal may by install the sensor (speed or acceleration) receives on the bearing seat, through to vibrates the signal the analysis to be possible to realize to the roll axis undertakes to transport the row state the monitor and the diagnosis.2. Noise signal monitor diagnosis technologyThis method is judges its breakdown through rolling bearing's in movement process noise. Carries on bearing's failure detection with the noise law, the merit does not need to contact was measured that the bearing may obtain the detection signal; its malpractice is separates the bearing unusual sound signal very difficultly from environment each kind of static. Therefore, the noise laws are very generally few are used. But the success example also has, is installs the microphone on the directive strong parabola sounder, collects sound signal which the bearing sends out, and removes other static with the reverse filter, examines the bearing different sound.3. Temperature signal monitor diagnosis technologyThrough installs in the bearing seat (or box body) place temperature sensor monitor temperature, judges the bearing to work whether normally. The temperature monitoring to the bearing load, the speed and the lubrication situation's change reflection is quite sensitive, particularly the bearing overheated phenomenon which causes to the insufficient lubrication is very sensitive. Therefore, because this kind of situation is quite effective. But, when the bearing presents such as the early pitting, flaking, the slight attrition and so on quite small breakdown, the temperature monitoring basically had not reflected that is only when the breakdown achieves certain order of severity, can monitor with this method. Therefore, the temperature monitoring is not suitable for the pitting, partial flaking and so on so-called partial - 11 -damage class breakdown.4. Oil type analysis monitor diagnosis technologyThe oil type analytic method oil type analytic method has the spectral analysis and the hard spectrum analyzes two broad headings. The bearing attrition pellet has close contacting with its working condition. The spectral analysis method has many kinds, but the common ground uses the spectral analysis, determines in the fat liquor to contain each metallic element ingredient and the content, judges includes is measured the element the spare part wear condition and the degree. The hard spectrum analysis method has the attrition pellet lubricating oil through a strong magnetic field, under the strong magnetic field's function, the abrasive precipitates according to certain rule on the hard spectrum piece, the hard spectrum piece may make the qualitative observation or on the hard spectrum microscope tests on the quota instrument, according to the above judges bearing's working condition.The oil type analytic method suits in using the lubrication oil lubrication bearing's failure diagnosis, for uses the bearing which the fat lubricates to be difficult. Moreover, this method easily the pellet influence which falls down other non-bearing failure; Uses in the off-line monitor way, like this will cause certain bit drop-out; The information content is big and is mixed, namely has the image also to have the digit, depends upon the manpower to manage is very difficult. Therefore, this method has the very big limitation.5. Lubricant film resistance monitor diagnosis technologyThe bearing has the good lubricates, as a result of the lubricant film function, between the addendum circle has the very big resistance. Therefore through surveys between the bearings, the addendum circle resistance may exceptionally make the judgment to the bearing. Its characteristic is may use the identical judgment standard to the different operating mode condition, is suitable situation which appears externally in the rotation axis, to the surface scaling, the indentation, the crack and so on unusual diagnosis effect is quite bad. Along with science's and technology's unceasing development, some new monitor technology appears unceasingly and applies in rolling bearing's operating - 12 -mode monitor and the diagnosis, for example: Sound launch technology, optical fiber technology and so on. But with the limitation, this technical true popularization applies for various reasons in the actual rolling bearing failure diagnosis also has section of distances.1.3 Rolling bearing failure diagnosis technology development surveyRolling bearing's failure diagnosis technology started probably in the 1960s. The most primitive bearing failure diagnosis method is listens the stick contact bearing portion, whether there is depends upon the sense of hearing to judge the breakdown. Afterward used various types vibration meter gradually, the measuring appliance and using the vibration displacement, whether there is the speed or the acceleration root-mean-square value judges the bearing breakdown. Along with to rolling bearing's kinematics, the dynamics deep research, vibrated the signal medium frequency ingredient and the bearing part geometry size and the flaw type relations regarding the bearing had the quite clear understanding, in addition the fast Fournier transformation (FFT) technology's development, founded examined and the diagnosis bearing breakdown efficient path with the frequency range analytic method. In several dozens year development time, each method and the skill have, the development and the consummation unceasingly, the application domain expand unceasingly, the diagnosis validity enhances unceasingly. Generally speaking, the rolling bearing failure diagnosis's development has experienced the following several stages:The first stage: Uses the low-frequency signal reception diagnosis stageIn the mid-1960s, because the fast Fournier transformation (FFT) technology's appearance (in 1965) and the development, the low-frequency signal reception obtained the very big development. The low-frequency signal reception is the broadband signal which examines from the sensor carries on directly the bearing on the spectral analysis, or signal after low-pass filtering, after elimination high-frequency component, in makes the spectral analysis, observes the main spectrum peak from the frequency spectrum. If some spectrum peak correspondence frequency with theoretical calculation bearing part's spacing frequency consistent, then - 13 -expresses on this part to have the breakdown. This method is big regarding the low frequency ingredient energy, the external disturbance small signal, should be theoretically speaking feasible, but actual moves the bearing, is very small because of the breakdown impact's energy, but the bearing, gear's craft error suggestion's vibrational energy must be much bigger than it. Therefore, the direct use low-frequency signal reception obtains the spectrogram the spectral line is often crowded, slurred, very difficult to distinguish crashes the signal. At present are very few distinguishes the bearing breakdown directly with this method, some is only determines the bearing part's natural frequency with this kind of frequency spectrum.The second stage: Using shock pulse law diagnosis stageIn the late 60s, first develops the shock pulse idea by Sweden SPM Instrument Company, diagnoses the bearing breakdown according to shock pulse's greatest peak-to-peak value. Rolling bearing in revolution, if the rolling body contact point enters the surface defect area (flaking, crack, pit and uneven rough area), will have the low frequency impact, and transmits on the bearing seat by not the continual impact pulse wave form. Although the shock pulse profile weakens very quickly, the accumulation energy is very small. However, under this impact action of force, the bearing part or structure some part is possibly stimulated its natural frequency. Although shock pulse's recurrence rate is lower than bearing's natural frequency far, but the higher order frequency which, so long as this impact produces falls on the bearing natural frequency pass band, also will arouse the bearing system's resonance effect. In the resonating high-frequency wave has contained the low frequency impact and the random disturbance peak-to-peak value modulating wave, has reflected the impulse size after the narrow band filtering and envelope detection's signal peak-to-peak value size, also responded the rolling bearing active face breakdown condition.The third stage: Using resonating demodulation law diagnosis stageThe resonating demodulation law is also called the envelope detection frequency spectrum analytic method. in 1974, US Boeing's DR Harting has invented a named “the resonating demodulation analysis system” the patent, this is our country is called now “the resonating demodulation technology” the embryonic form. The resonating - 14 -demodulation law and shock pulse's method basic principle