軋鋼機中英文對照外文翻譯文獻

PAGEIII中英文翻譯基于振動監(jiān)測的設(shè)備故障診斷技術(shù)在大型軋鋼機械上的應(yīng)用摘要對基于振動的設(shè)備故障診斷技術(shù)做了較全面和深入的介紹,通過實例介紹了該診斷技術(shù)在軋鋼機械領(lǐng)域的應(yīng)用。指出該診斷技術(shù)可同時對一個測點進行復(fù)雜的時域、頻域、相關(guān)域、統(tǒng)計域等分析,具有一定的趨勢預(yù)測分析能力。關(guān)鍵詞軋鋼機械;振動監(jiān)測;故障診斷1前言軋鋼機械屬于大型的旋轉(zhuǎn)機械,是軋鋼廠的關(guān)鍵設(shè)備。轉(zhuǎn)軸組件是軋機的核心部分,它包括旋轉(zhuǎn)軸、齒輪傳動件、聯(lián)軸器、滑動和滾動軸承等。人們通過長期觀察和實踐,發(fā)現(xiàn)旋轉(zhuǎn)機械的絕大多數(shù)前期故障都會表現(xiàn)出異常的振動,因此掌握機械振動的一般規(guī)律就能從振動信號中識別出常見的設(shè)備故障。通過對振動信號波形進行簡單的時域、頻域以及小波分析可對振動進行一般的識別,振動的可識別性是對機械故障進行振動噪聲測試分析的技術(shù)前提。因此,采用在設(shè)備診斷技術(shù)領(lǐng)域較成熟的振動分析技術(shù)作為技術(shù)的突破口對軋鋼機進行日常振動狀態(tài)監(jiān)測,就能在設(shè)備運行中或基本不拆卸全部設(shè)備的情況下,掌握軋機運行狀態(tài),判定產(chǎn)生故障的部位和原因,并預(yù)測未來的技術(shù)狀態(tài),從而可在早期有效地發(fā)現(xiàn),以及在后期及時地抑制故障,保障生產(chǎn)的可持續(xù)發(fā)展。2信號識別與獲取任何機器設(shè)備在運行中都會產(chǎn)生振動,機器的振動信號中包含了豐富的機器運行的狀態(tài)信息。當設(shè)備發(fā)生異常或故障時,振動將會發(fā)生變化,一般表現(xiàn)為振幅加大。由不同類型、性質(zhì)、原因和部位產(chǎn)生的故障所激發(fā)的振動具有不同的特征,這些特征表現(xiàn)為頻率成分、幅值大小、相位差別、波形形狀和能量分布狀況等。振動信號的性質(zhì)和特征不僅與故障有關(guān),還與系統(tǒng)的固有特性有關(guān),具體表現(xiàn)為同一故障發(fā)生的部位不同、故障激勵傳遞通道(即傳遞函數(shù))不同,其振動特征和響應(yīng)亦會有較大的差別?？傊?設(shè)備的振動是由故障激勵和系統(tǒng)特性所共同決定的,但很多情況下,振動特征和故障類型之間并不是一一對應(yīng)的關(guān)系,不能簡單地對號入座,這就給振動的識別帶來一定的困難。因此,振動的識別對于設(shè)備診斷技術(shù)的完善是至關(guān)重要的。軋鋼機械工作時軋件是非連續(xù)地被軋制的,其轉(zhuǎn)速并不恒定、功率更是從空載到滿負荷間周期地波動。從原動機到軋輥間有龐大的傳動和減速機構(gòu),可能出現(xiàn)的故障類型很多,因此檢測設(shè)備、測點、點檢方式和點檢時間的選擇對診斷的準確與否起關(guān)鍵作用。為保證所測數(shù)據(jù)具有可比性,在測定數(shù)據(jù)時應(yīng)遵循以下幾點原則:①每次測量要在同一測點進行,否則由于激振源到測點的傳遞函數(shù)不同,而使測量的結(jié)果相差很大。②保持每次測量時機器的工況相同。③保持測量的參數(shù)相同,一般來說,頻率在10～100Hz的振動應(yīng)以位移作為數(shù)采器的輸出參數(shù),頻率在100～1000Hz的振動應(yīng)以速度作為數(shù)采器的輸出參數(shù),頻率在1000Hz以上的振動應(yīng)以加速度作為數(shù)采器的輸出參數(shù)。④使用的儀器相同和測量的方法(如傳感器及其固定方式)相同。在測振過程中,測點的選擇同樣影響監(jiān)測結(jié)果,其選擇原則是:(1)測點應(yīng)選擇在振動信號傳遞的通道上而且路線最短的位置,盡量減少中間傳遞介質(zhì)。(2)測點應(yīng)選在信號反應(yīng)比較敏感的部位,如軸承座、機座等。(3)測點應(yīng)選擇在便于多方位測量的位置。一般測振動要選定三個方向(水平X、垂直Y、軸向A)來評定,特別對低頻振動,更要強調(diào)其方向性(高頻振動對方向不敏感)。(4)對于大型機械設(shè)備,受傳遞函數(shù)的影響,應(yīng)多點檢測。3軋鋼機械等旋轉(zhuǎn)機械的常見故障及其診斷方法旋轉(zhuǎn)機械的常見故障,按轉(zhuǎn)子類型和振動性質(zhì)的不同,可分為:轉(zhuǎn)子不平衡、轉(zhuǎn)子不對中、基座或裝配松動、轉(zhuǎn)子與定子摩擦、感應(yīng)電機振動、滾動軸承故障、齒輪機構(gòu)的振動等。利用振動監(jiān)測技術(shù)對這些常見機械故障可進行較為準確的診斷。3.1轉(zhuǎn)子不平衡不平衡是旋轉(zhuǎn)機械中最常見的一種故障。引起不平衡的原因較多,如安裝不良造成偏心、配合松動、軸彎曲變形、加工制造誤差以及長期運行中產(chǎn)生不均勻磨損等。我們從離心力的計算公式易知,不平衡振動對轉(zhuǎn)速的變化是最敏感的。轉(zhuǎn)子不平衡的振動特征是:剛性轉(zhuǎn)子在啟動時振幅隨轉(zhuǎn)速的增大而增大,柔性轉(zhuǎn)子在啟動時振幅是先增大而后減小。在頻率特征方面,不平衡振動的頻率成分單一而明朗,主要表現(xiàn)為轉(zhuǎn)子的基頻;在相位方面,水平和垂直方向的振動相差90?,且通常水平方向的振動比垂直方向的大、徑向振動比軸向振動要大。3.2轉(zhuǎn)子不對中轉(zhuǎn)子不對中是指轉(zhuǎn)子中心與軸承中心不對中,或多轉(zhuǎn)子系統(tǒng)中各轉(zhuǎn)子的軸線不對中,也是旋轉(zhuǎn)機械的一類多發(fā)性的典型故障。不對中有三種類型,即平行不對中、角度不對中、綜合不對中。其產(chǎn)生的原因有:轉(zhuǎn)子及支座安裝不良、軸承支座不均勻膨脹引起變形、地基變形以及熱不對中等。轉(zhuǎn)子不對中的振動特征是:當轉(zhuǎn)子不對中時將產(chǎn)生一種附加彎矩,形成附加激勵,故軸向振動往往是存在不對中的一種征兆。在振動頻率特征方面,平行不對中主要激起2倍轉(zhuǎn)頻,角度不對中則表現(xiàn)為同頻振動突出,它們的共同點是以旋轉(zhuǎn)頻率的2倍頻或4倍頻為主,尚伴有高次倍頻。在相位特征方面,平行不對中時,轉(zhuǎn)子兩端徑向振動相位相差180?;角度不對中時,聯(lián)軸器兩端軸向振動相位相差180?,而徑向相位相同。3.3基座或裝配松動松動常和不平衡相伴生,表現(xiàn)為非線形的振動特征。地腳松動引起的振動方向特征很明顯,表現(xiàn)在垂直方向的振動很強烈。由零件配合松動引起的振動,其方向特征不明顯。在振幅方面,松動引起的振動隨負荷的增加而增大,但對轉(zhuǎn)速表現(xiàn)出無規(guī)律的變化,忽大忽小,呈跳躍式變化。在振動頻率特征方面,除基頻成分外,基頻的奇數(shù)倍頻突出(常高于基頻的幅值),伴有3倍、5倍、7倍及0.3～0.5倍的諧波成分,頻譜結(jié)構(gòu)成梳狀。3.4轉(zhuǎn)子與定子摩擦此類摩擦屬干摩擦,大多表現(xiàn)為徑向摩擦。摩擦振動屬于非線性振動,頻帶范圍很寬,除基頻外,還有2倍、3倍以及1/3、1/2等諧波成分。在時域波形上,常表現(xiàn)為削波狀態(tài),“截頭余弦”形狀的波形是摩擦故障特有的重要標志。在某些特殊情況下,摩擦還可能激起系統(tǒng)的固有頻率振動。3.5感應(yīng)電機振動故障特征電動機是一種典型的旋轉(zhuǎn)機械,在機械故障的表現(xiàn)方面具有旋轉(zhuǎn)機械的共同特點,如存在轉(zhuǎn)子不平衡、不對中、松動、摩擦等故障類型。感應(yīng)電機的振動故障的一大特點是包括機械和電氣兩方面內(nèi)容,發(fā)生的故障除機械因素外還與電氣相關(guān),如轉(zhuǎn)子與定子間磁隙不均勻、電壓不穩(wěn)定、匝間短路等也會引起電機的異常振動。當電動機在運行中突然給它斷電,其時如果振動立即下降為零,即說明電動機存在電氣方面的故障,否則,屬于機械故障。3.6滾動軸承故障滾動軸承是旋轉(zhuǎn)機械轉(zhuǎn)子系統(tǒng)的重要支撐部件,其基本結(jié)構(gòu)包括外圈、內(nèi)圈、滾動體、保持架等元件。對滾動軸承實施振動診斷的基本方法是頻率分析,因為滾動軸承每一個元件都有其各自的故障特征頻率。理論上,通過頻率分析不但能判斷軸承有無故障,而且可以具體判斷軸承中損壞的元件。滾動軸承的故障特征頻率(簡化計算)為:內(nèi)圈通過頻率F=0.6Z?Fr,外圈通過頻率F=0.4Z?Fr,保持架通過頻率F=0.4Fr,其中Z為滾動體個數(shù),Fr為軸承內(nèi)圈回轉(zhuǎn)頻率。還需指出的是滾動軸承的振動與安裝也有關(guān),如安裝滾動軸承的旋轉(zhuǎn)軸系彎曲、軸承裝歪、軸承緊固過松或過緊都會引起振動,其振動頻率成分也含有滾動體通過頻率和高次諧波。3.7齒輪機構(gòu)的振動特征及診斷齒輪是旋轉(zhuǎn)機械的重要部件,其運行狀態(tài)的好壞直接影響到整個機組的正常工作。在齒輪箱中的各類零件中,失效比例分別為齒輪60%、軸承19%、軸10%、箱體7%、緊固件3%、油封1%,可見在所有零件中齒輪自身的失效比例最大。根據(jù)國外抽樣統(tǒng)計的結(jié)果表明,齒輪的各種損傷的概率為:斷齒41%、齒面疲勞31%、齒面磨損10%、齒面劃痕10%、其它故障8%。在理想漸開線齒形及齒輪剛度無窮大的假設(shè)下,一對齒輪在嚙合運動中是不會產(chǎn)生振動的,但由于制造、安裝及齒輪剛度不可能為無窮大等方面的問題,一對新齒輪在嚙合運動中也會產(chǎn)生振動。通過對齒輪運動方程的分析可知,正常齒輪傳動中由于嚙合剛度的周期性變化會引起參數(shù)振動;由于齒形誤差的隨機激勵可能會引起齒輪彈性系統(tǒng)的共振;當齒輪出現(xiàn)故障時,振動往往會加劇,也會產(chǎn)生一些新的頻率成分,這些都是齒輪的特征頻率。齒輪特征頻率主要有3種,即齒輪嚙合頻率、齒輪自振頻率和齒輪邊頻帶。定軸轉(zhuǎn)動的嚙合頻率為F=Z?Fr,行星輪系的嚙合頻率為F=Z(Fr±Fc),其中Z為齒輪齒數(shù)、Fr為齒輪旋轉(zhuǎn)頻率、Fc為轉(zhuǎn)臂旋轉(zhuǎn)頻率。直齒圓柱齒輪自振頻率為F=,其中k為齒輪副的彈簧常數(shù)、m為齒輪副的等效質(zhì)量,其它類型齒輪的自振頻率一般由試驗測定(不隨轉(zhuǎn)速改變而恒有的頻率分量通常就是系統(tǒng)的固有頻率,齒輪固有頻率一般為1～10kHz)。當齒輪存在故障時,由于載荷波動而產(chǎn)生幅值調(diào)制,由于轉(zhuǎn)速波動而產(chǎn)生頻率調(diào)制,因此在嚙合頻率或固有頻率兩旁產(chǎn)生等間隙(1X)的一簇邊頻。通過振動診斷判別齒輪狀態(tài),最有效可行的方法是分析齒輪振動功率譜的變化,其次是分析倒頻譜(如果儀器的信噪比高,倒頻譜分析效果也很好)。首先看嚙合頻率幅值的消長;二是要看嚙合頻率諧波的分布;三是看邊頻,隨著齒輪故障的發(fā)展和振動能量的增加,邊頻越來越豐富,幅值也增加(邊頻分析通常要先將譜細化)。4診斷實例分析 對軋機進行日常振動狀態(tài)檢測所需的工具主要有振動傳感器、數(shù)據(jù)采集器、配套軟件等,目前市面上已有此類成套的設(shè)備出售。我們選用的是北京圣迪公司的振通904型振動動平衡一體化儀器。它的主要功能是檢測振動信號并進行采集記錄和預(yù)處理,通過RS232C標準串行口與微機(P486以上)通訊后可以將記錄在儀器中的各種數(shù)據(jù)送入微機中,借助儀器附帶的波形分析軟件可對采集到的數(shù)據(jù)進行時域、頻域、統(tǒng)計域等方面的分析,做更精細的設(shè)備故障分析和診斷,建立設(shè)備狀態(tài)數(shù)據(jù)庫,預(yù)報設(shè)備狀態(tài)發(fā)展趨勢等。運用該儀器可以對軋機日常運行時的振動進行檢測,掌握軋機的運行狀態(tài)、發(fā)現(xiàn)和跟蹤軋機的早期故障、提出維修計劃、跟蹤維修質(zhì)量等。以廣鋼連軋廠12#軋機為例,利用基于振動的設(shè)備故障診斷技術(shù)對其進行一次全面的分析診斷。根據(jù)測點選擇原則,我們選取了3個測點(圖6中ZJ12-1、ZJ12-2、ZJ12-3)。2005年3月29日12#軋機被診斷為發(fā)生了齒輪斷齒故障。當天的點檢現(xiàn)象:軋機無異響、但振值和波形有故障跡象,尤其是ZJ12-1測點的信號特別明顯。診斷過程用到了振值表(表1,其數(shù)值為最近6個月內(nèi)的數(shù)值)、時域波形(圖1)、自相關(guān)圖形(圖2)、幅值譜圖(圖3)、概率密度圖(圖4)、倒頻譜圖(圖5)。通過對表1、圖1、圖2、圖3、圖4、圖5和圖6對12#軋機進行的全面分析診斷如下:(1)振值表:在6個月里振值表內(nèi)各項指標沒有明顯增大現(xiàn)象,表明振動級數(shù)和能量在故障前后未有明顯變化,小部分斷齒對振值表內(nèi)各項指標不敏感,這也解釋了故障時設(shè)備無異響的原因。(2)時域波形:在時域波形中可明顯看到振動含有劇烈周期沖擊,沖擊波形突然上升又突然衰減且極其陡峭,極有可能發(fā)生了突發(fā)性故障。經(jīng)計算沖擊周期為65.6ms,即頻率為15.244Hz。當天電機轉(zhuǎn)速為914r/m,轉(zhuǎn)頻為15.244Hz。可見,輸入軸(電機軸)的轉(zhuǎn)頻與沖擊頻率驚人地吻合。由此可判斷沖擊故障就發(fā)生在輸入軸上,加上考慮沖擊特性可初步判定輸入軸的齒輪可能發(fā)生了斷齒。(3)自相關(guān)分析:在自相關(guān)圖上可看到圖形收斂性異常,在T1=63.7和T2=128.9處圖形趨于發(fā)散,可斷定在信號中存在T=65.2周期成分。此周期與時域中的沖擊周期一致,故時域中判定的沖擊在相關(guān)域中得到了證實。(4)概率密度:在統(tǒng)計域中發(fā)現(xiàn)振動信號峭度達4.013,遠遠超出正常范圍(2～3)。峭度指標是一項反映波形尖峭程度和沖擊大小的無量綱指標,峭度超標更證實了振動信號中存在異常的沖擊能量。對正常的軋鋼過程而言,載荷波動會引起峭度輕微超標,峭度達4.013最可能的就是發(fā)生了斷齒。(5)幅值譜分析:將幅值譜細化后可看到在300Hz和440Hz頻率兩旁存在邊頻帶,1X=16,邊頻帶是齒輪和軸承類沖擊故障信號經(jīng)頻率調(diào)制后的特有現(xiàn)象。經(jīng)計算沖擊頻率與輸入軸轉(zhuǎn)頻相等而與軸承的故障特征頻率不等,到此可更肯定地判定時域中發(fā)現(xiàn)的周期沖擊確實為齒輪故障所致。(6)倒頻譜分析:在倒頻譜圖中可看到T=63.5ms處的信號分量很大,此周期與時域中的沖擊周期也吻合得很好。倒譜是一個對測點、傳輸途徑和信號調(diào)制不敏感的量,對判定軸承和齒輪故障很有效。至此,可更肯定沖擊是由斷齒所引起,而不是軸承故障、轉(zhuǎn)子不平衡或不對中等所引起。(7)機械傳動系統(tǒng)原理簡圖(見圖6)。(8)診斷結(jié)論及反饋:通過以上的分析可判定12#軋機在當天有沖擊性的突發(fā)故障,且沖擊異常強烈和尖銳,可排除軸承故障所引起,最有可能的就是發(fā)生了齒輪斷齒故障,計算也表明故障發(fā)生在輸入軸齒輪的可能性最大。后經(jīng)鉗工拆開該軋機檢查發(fā)現(xiàn)為輸入軸錐齒輪發(fā)生了部分斷齒,以上推斷得到了印證。5結(jié)語基于振動監(jiān)測的設(shè)備故障診斷技術(shù)是一門建立在多學(xué)科基礎(chǔ)上的綜合性新技術(shù),是基于大量的數(shù)理統(tǒng)計基礎(chǔ)上形成的數(shù)學(xué)模型的應(yīng)用,其中涉及到了旋轉(zhuǎn)機械振動的一般規(guī)律、檢測設(shè)備的工作機理和技術(shù)應(yīng)用、振動信號的分析方法、旋轉(zhuǎn)機械的常見故障的信號特征和判定等。實際上,此技術(shù)不僅可應(yīng)用在軋機上,還可應(yīng)用于幾乎一切旋轉(zhuǎn)機械上。利用這種技術(shù),可同時對一個測點進行復(fù)雜的時域、頻域,相關(guān)域、統(tǒng)計域等分析,并具有一定的趨勢預(yù)測分析能力。對設(shè)備故障早發(fā)現(xiàn)、早處理,可以避免個別設(shè)備故障的進一步惡化,減少設(shè)備誤產(chǎn)時間,同時也降低了維修工人的勞動強度,體現(xiàn)出巨大的間接效益。外文翻譯APPLICATIONOFVIBRATINGMONITORINGBASEDFAULTDIAGNOSISTECHNOLOGYONTHELARGE-SCALESTEELROLLINGMACHINEAbstractThevibratingmonitoringbasedfaultdiagnosistechnologywasintroducedgenerallyanddeeply.Theapplicationofthediagnosistechnologyonsteelrollingmachineswasalsointroducedbyexamples.Thetechnologycouldsimutaneouslyanalyzedamonitoringpointaboutitstimedomain,frequencydomain,correlationdomainandstatisticdomain.Andithastheanalysesabilityoftrendbasedforcasting.Keywordssteelrollingmachine;vibratingmonitoring;faultdiagnosing1PrefaceRollingmachineisalargerotatingmachinery,isthekeytorollingmillequipment.Shaftcomponentisthecorepartofthemill,whichincludestheaxisofrotation,gearparts,couplings,slidingandrollingbearingsandsoon.Peoplethroughobservationandpractice,foundthatthevastmajorityofrotatingmachineryfaultwillshowthepre-abnormalvibration,thereforethegenerallawofmechanicalvibrationcontrolcanbeidentifiedfromthevibrationsignalsofcommonequipmentfailure.Vibrationwaveformbyasimpletimedomain,frequencydomainandwaveletanalysiscanbeageneralrecognitiononthevibration,thevibrationcanbeidentifiedisamechanicalfaultofnoiseandvibrationtestandanalysisoftechnicalpremise.Therefore,theuseofdiagnostictechnologyinequipmentvibrationanalysisofmorematuretechnology,abreakthroughtechnologyasaroutineofrollingmillvibrationconditionmonitoring,equipmentoperationwillbeabletoremoveallequipmentorbasicallynotthecase,controlmillrunning,determinetheproductionthelocationandcauseoffailure,andpredictthefuturestateoftechnology,whichcanbeeffectiveintheearlydiscoveryandinhibitthebreakdowninthelatertimetoensuretheproductionofsustainabledevelopment.2SignalrecognitionandaccesstoEquipmentintheoperationofanymachinewillhaveavibration,themachinevibrationsignalcontainsawealthofmachineoperatingstatusinformation.Exceptionoccurswhenthedeviceorfailure,thevibrationwillchange,usuallyexpressedasamplitudeincreased.Bydifferenttypes,nature,causesandlocationofthefaultproducedbythevibrationexcitedwithdifferentcharacteristics,suchcharacteristicsasfrequencycomponents,amplitudeofthephasedifferencebetweenwaveformshapeandenergydistributionandsoon.Thenatureandcharacteristicsofvibrationsignalstroublenotonly,butalsotheinherentcharacteristicsofthesystemrelatedtothespecificperformanceofdifferentpartsofthesamefault,faultexcitationtransferchannel(ietransferfunction)isdifferent,thevibrationcharacteristicsandtheresponsewillalsohavegreaterdifference.Inshort,thedeviceisthevibrationcharacteristicsofthefaultsystemofincentivesandjointdecision,butinmanycases,vibrationcharacteristicsandfailureisnotaonetoonerelationshipbetweentypes,notsimplythecondemnation,whichbroughtrecognitiontothevibrationcertaindifficulties.Therefore,identificationofvibrationdiagnosistechnologyforimprovedequipmentisessential.Rollingmillmachineryatworkbenon-continuousrollingrolling,anditsspeedisnotconstant,thepowerisfromnoloadtofullloadtofluctuatebetweenperiods.Rollfromtheoriginalmotivationtodrivebetweenlargeandslowinstitutions,manytypesofproblemsthatmayoccur,sotestingequipment,measuringpoint,point-locationandtimeofInspectiononthediagnosticaccuracyofthechoiceofwhetherornotplayakeyrole.Toensurecomparabilityofthemeasureddata,inthedeterminationoftheprinciplesofdatashouldfollowthefollowingpoints:①eachmeasurementpointinthesamemeasure,ortheexcitationsourcetothetransferfunctionofthedifferentmeasuringpoints,leavingthedifferencebetweenthemeasurementresultsgreat.②eachmeasurementtokeepthemachinethesameconditions.③tomaintainthesameparametersmeasured,ingeneral,thefrequencyofvibrationinthe10~100Hzdataacquisitionshouldbebasedondisplacementastheoutputparameter,thefrequencyin100~1000Hzvibrationdataacquisitionshouldspeedastheoutputparameters,frequencyabove1000Hzvibrationaccelerationshouldbetakenasthenumberofoutputparameters.④usingthesameinstrumentsandmeasurementmethods(suchassensorandafixedway)thesame.Inthevibrationprocess,thechoiceofmeasurementpointsalsoaffectthemonitoringresults,thechoiceofprinciples:(1)Themeasuringpointshouldbeselectedinthevibrationsignaltransmissionchannelandthelocationoftheshortestroutetominimizetheintermediatetransfermedia.(2)Themeasuringpointshouldbeselectedinthemostsensitivepartsofthesignal,suchashousing,frameandsoon.(3)Themeasuringpointshouldbechoseninplacetofacilitatemulti-directionalmeasurements.Generalmeasurevibrationinthreedirectionstobeselected(thelevelofX,theverticalY,axisA)toevaluate,especiallyforlowfrequencyvibration,butalsotoemphasizethedirection(high-frequencyvibrationonthedirectionisnotsensitive).(4)forlargemechanicalequipment,bythetransferfunctionshouldbemoretesting.3steelrollingmachinery,andothercommonfaultsandrotatingmachineryThediagnosisCommonrotatingmachineryfaults,accordingtothenatureoftherotorandvibrationtypecanbedividedinto:rotorunbalance,rotormisalignment,loosebaseorassembly,therotorandstatorfriction,inductionmotorvibration,bearingfailure,vibrationandothergearmechanism.Vibrationmonitoringtechniqueusingthesecommonmechanicalfailurecanbeamoreaccuratediagnosis.3.1RotorimbalanceRotatingMachineryimbalanceisthemostcommonformoffailure.Imbalancecausedbymanyreasons,suchastheeccentricitycausedbypoorinstallation,withtheloosening,axialbending,manufacturingerrors,andgeneratelong-termoperationunevenwear.Ourformulafromthecentrifugalforceiseasytoknow,unbalancevibrationofenginespeedisthemostsensitive.Thevibrationcharacteristicsofrotorimbalanceis:rigidrotorspeedatstartup,theamplitudeincreases,theamplitudeofflexiblerotoratstartupistoincreaseandthendecrease.Inthefrequencycharacteristics,theunbalancevibrationofthefrequencycomponentsofasingle,clear,mainlythefundamentalfrequencyoftherotor;inphase,thehorizontalandverticalvibrationdifference90?,andoftenhorizontalthanverticalvibrationofalarge,radialvibrationislargerthantheaxialvibration.3.2RotormisalignmentRotorisnotinthecenteroftherotorcenterandbearingmisalignment,orrotorsystemaxismisalignmentoftherotorisrotatingmachinerytypicalofaclassofmultiplefaults.Therearethreetypesofmisalignment,namely,parallelmisalignment,angularmisalignment,integratedmisalignment.Thecausesare:badrotorandbearinginstallation,bearingbearingdeformationcausedbyunevenexpansion,grounddeformationandheatdoesnotmoderate.Thevibrationcharacteristicsofrotormisalignmentisthis:Whennotintherotorwillproduceanadditionalmoment,theformationofadditionalincentives,sothereisnotaxialvibrationisoftenasymptomof.Characteristicsofthevibrationfrequency,theparalleldoesnotturnthemainfrequencystir2times,theangledoesnotshowthesamefrequencyofvibrationisprominent,andtheyhaveincommonistherotationfrequencyofthe2octaveor4octave-based,stillaccompaniedbyhigherfrequency.Inthephasecharacteristics,theparallelmisalignment,therotorradialvibrationatbothendsofphase180?;anglemisalignment,thecouplingendsofaxialvibrationofphase180?,andtheradialphaseofthesame.3.3BaseorassemblylooseStudentsoftenaccompaniedbylooseanduneven,showinganon-linearvibrationcharacteristics.FeetdirectionofvibrationcharacteristicscausedbylooseObviously,theperformanceofthevibrationintheverticaldirectionisverystrong.Bythevibrationcausedbyloosepartswithitsdirectionalfeatureisnotobvious.Inamplitude,thevibrationcausedbyloosewiththeincreaseoftheload,butspeedshownochangeinthelaw,suddenlybigsuddenlysmall,waschangingbyleapsandbounds.Characteristicsofthevibrationfrequency,inadditiontofundamentalfrequencycomponents,thefundamentalfrequencyoftheoddharmonicprominent(oftenhigherthanthefundamentalfrequencyamplitude),accompaniedby3times,5times,7timesand0.3~0.5timesHarmoniccomponents,intoacombspectrumstructure.3.4RotorandstatorfrictionSuchfrictionisfriction,mostoftheperformanceoftheradialfriction.Frictionandvibrationisvibration,frequencyrangeisverywide,inadditiontofundamentalfrequency,thereare2times,3timesand1/3,1/2andotherharmoniccomponents.Inthetimedomainwaveform,usuallymanifestedclipping,"truncatedcosine"waveformshapeisanimportantsymboloftheuniquefrictionfault.Insomespecialcases,thefrictionmayprovokethenaturalfrequencyofvibrationofthesystem.3.5VibrationcharacteristicsofinductionmotorMotorisatypicalrotatingmachinery,mechanicalfailureintheperformanceofacommonfeatureofrotatingmachinery,suchastheexistenceofrotorimbalance,misalignment,loosenessandfriction,thefaulttype.Faultinductionmotorischaracterizedbyalargeincludesbothmechanicalandelectricalcontent,exceptmechanicalfailuresandelectrical-relatedfactorsalso,suchasthemagneticgapbetweentherotorandthestatordifferential,voltageinstability,willturntoturnshortcircuitAbnormalvibrationcausedbythemotor.Whenthemotorisrunningitoffsuddenly,thetimeimmediatelydroptozeroifthevibration,whichshowstheexistenceofelectricalmotor'sfault,otherwise,belongtomechanicalfailure.3.6RollingBearingFaultRollingistheimportanceofrotatingmachinerysupportedrotorsystemcomponents,thebasicstructureconsistsofouter,innerring,rollingelements,cageandothercomponents.Bearingvibrationdiagnosisoftheimplementationofthebasicmethodistofrequencyanalysis,becauseeveryelementbearingfaulthasitsowncharacteristicfrequency.Intheory,frequencyanalysiscannotonlyjudgebywhetherorbearingfailure,andcandeterminethebearingofthespecificdamagetocomponents.Rollerbearingfaultcharacteristicfrequency(simplifiedcalculation)is:theinnerringbythefrequencyF=0.6Z?Fr,theouterringthroughthefrequencyF=0.4Z?Fr,cagepassingfrequencyF=0.4Fr,whereZisrollingnumber,Frforthebearinginnerringrotationfrequency.Needstobenotedthatthevibrationofrollingbearingsandinstallationarealsoconcerned,suchastheinstallationoftherotatingbearingshaftbending,bearingmountedcrooked,bearingfasteningtoolooseortootightcancausevibration,thevibrationfrequencycomponentsalsocontainhighfrequencyandbyrollingharmonics.3.7GearvibrationandDiagnosisGearisanimportantcomponentofrotatingmachinery,anditsrunningwillhaveadirectimpactonthenormalworkoftheentireunit.Invariouspartsofthegearbox,thegearfailurerateswere60%,19%ofbearings,shaft10%,box7%,3%offasteners,sealsof1%,showingitselfinallpartsofgearfailurethelargestproportion.Accordingtoforeignsamplesurveyresultsshowthattheprobabilityofallkindsofdamagegearasfollows:41%brokenteeth,toothsurfacefatigue31%,10%oftoothwear,toothsurfacescratches10%,8%ofotherfailures.Intheidealinvolutegeartoothprofileandtheassumptionofinfinitestiffness,apairofmeshinggearsinmotionisnovibration,butduetomanufacturing,installationandgearcannotbeinfinitestiffnessandotherissues,apairofnewgearmovementwillalsohavethemeshingvibration.Equationofmotionthroughthegearanalysis,thenormalgearmeshstiffnessduetothecyclicalchangescauseparametricvibration;theprofileerroroftherandomexcitationmayleadtogeartheresonanceelasticsystem;whenthegearfails,thevibrationtendstointensified,alsohavesomenewfrequencycomponents,whicharethecharacteristicfrequencyofgear.Characteristicfrequencyofthemaingear3,thegearmeshfrequency,thegearandthegearnaturalfrequencysidebands.FixedaxisrotationofthemeshingfrequencyofF=Z?Fr,planetarygearmeshingfrequencyisF=Z(Fr±Fc),whereZisgearteeth,Frforthegearrotationfrequency,Fcarmfortherotationfrequency.SpurgearvibrationfrequencyF=wherekisthespringconstantofgear,mistheequivalentmassofgears,andothertypesofgearnaturalfrequencygenerallydeterminedbythetest(notwiththespeedofconstantchange,somefrequencycomponentsisoftenthesystemnaturalfrequency,thegearnaturalfrequencyisgenerally1~10kHz).Whenthegearthereisafault,duetoloadfluctuationofamplitudemodulation,thespeedfluctuationoffrequencymodulation,sothemeshfrequencyornaturalfrequencyofbothsidesofthegenerationgap,etc.(1X)oftheclusteredgefrequency.Gearvibrationdiagnosticdiscriminationbythestate,themosteffectivemethodistoanalyzethechangeofgearvibrationpowerspectrum,followedbyanalysisofinvertedspectrum(iftheinstrumentsignaltonoiseratiohigh,cepstrumanalysiswasalsoveryeffective.)Firstlookatmeshingfrequencyofthefluctuationamplitude;thesecondistolookatthedistributionofmeshfrequencyharmonics;thirdistolookatside-band,withthegearfaultvibrationenergydevelopmentandincreasing,whilemoreandmorerichfrequency,amplitudealsoincreased(edgefrequencyspectrumanalysisisusuallyfirsttorefine).4DiagnosisCaseStudy Vibrationofthemillroutinetestingtoolsarerequiredforvibrationsensors,dataacquisition,andthesupportingsoftware,currentlyonthemarkethavesuchcompletesetsofequipmentforsale.WeusetheBeijingShengDi'svibrationthroughintegrationof904-typevibrationbalancingequipment.Itsmainfunctionistodetectvibrationsignalsandtheacquisitionandpre-recordedbythestandardRS232CserialportandPC(P486above)afterthecommunicationcanberecordedintheinstrumentinavarietyofdataintothecomputer,thewaveformwiththehelpofinstrumentsAnalysissoftware,thedatacanbecollectedintimedomain,frequencydomain,statisticalanalysisofthedomain,etc.,todomoresophisticatedequipmentfailureanalysisanddiagnosis,theestablishmentofequipmentstatusdatabase,andforecastthedevelopmenttrendofdevicestatus.Theinstrumentcanbeuseddailyoperationofthevibrationmilltodetecttheoperatingstatecontrolmill,rollingmillintheearlydetectionandtrackingfault,maintenanceplan,tracking,maintenanceofquality.WithGuangzhouIronandSteelRollingMillPlant#12,forexample,vibration-basedfaultdiagnosistechnologytoconductacomprehensiveanalysisoftheirdiagnosis.Accordingtotheprincipleofmeasuringpointselection,weselectedthreemeasurementpoints(Figure6ZJ12-1,ZJ12-2,ZJ12-3).March29,200512#millhadbeendiagnosedwithbrokengeartoothfailure.Pointinspectiondayphenomenon:themillwasnoabnormalsound,butthevibrationwaveformvalueandthesignofafailure,especiallyZJ12-1measuringpointofthesignalisparticularlyevident.Thevalueofthediagnosticprocessusedinthevibrationtable(Table1,thevalueofthelast6months,values??),time-domainwaveform(Figure1),sincethecorrelationgraph(Figure2),amplitudespectrum(Figure3),probabilitydensity(Figure4),invertedspectrum(Figure5).ByTable1,Figure1,Figure2,Figure3,Figure4,Figure5andFigure6ofthe12#millcomprehensiveanalysisanddiagnosisareasfollows:(1)Vibrationvaluetable:Insixmonthsthevalueofthetablevibrationoftheindicatorsdidnotsignificantlyincreasethephenomenon,indicatingthatthevibrationenergyintheseriesandnosignificantchangesbeforeandafterfailure,asmallpartofthebrokenteethonthevibrationvalueofthetableindicatorsarenotsensitive,whichexplainsthefailureofequipment,noabnormalsoundreasons.(2)Time-domainwaveform:thewaveforminthetimedomaincanbeclearlyseeninthevibrationcyclewithsevereshock,asuddenincreaseinwave-shapedattenuationofasuddenandextremelysteep,verylikelyasuddenfailure.Calculatedtheimpactofcycle65.6ms,thefrequencyof15.244Hz.Thedayofthemotorspeedis914r/m,turnfrequencyof15.244Hz.Canbeseen,inputshaft(motorshaft)ofthetransferfrequencyandimpactfrequencyamazinglyconsistent.Fromthiswecandeterminetheimpactoffailureoccurredintheinputshaft,withapreliminarydeterminationtoconsidertheimpactoffeatureinputshaftofthegearhasbrokenteethmayoccur.(3)Auto-correlation:thecorrelationdiagramcanbeseenfromtheconvergenceofgraphicanomalies,intheT1=63.7,andT2=128.9處graphicstendtodiverge,itcanbeconcludedinthesignalexistsT=65.2cyclecomponents.Thiscycleandtheimpactofcycletimedomain,andthereforetheimpactinthetimedomaintodeterminetherelevantfieldhasbeenconfirmed.(4)theprobabilitydensity:foundinthestatisticaldomainvibrationsignalkurtosisof4.013,farbeyondthenormalrange(2-3).KurtosisisanindicatorreflectingtheextentandimpactofthesizeofthewaveformJianqiaothedimensionlessindex,kurtosisexceededevenconfirmedtheabnormalvibrationsignalintheimpactenergy.Onthenormalrollingprocess,theloadfluctuationswillcauseaslightexcessivekurtosis,kurtosisof4.013istheplacem