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1、 畢業(yè)設(shè)計文獻翻譯與原文 題目： 鐵路車輪對的輔助磁檢測 學(xué) 院： 測試與光電工程學(xué)院 專業(yè)名稱： 測控技術(shù)與儀器 班級學(xué)號： 學(xué)生姓名： 指導(dǎo)教師： 二〇一五年四月 鐵路車輪對的輔助磁檢測 摘要：在工件制作的過程中，車輪對檢測可以采取許多不同的缺陷檢測方法。然而這些方法在車輪在役使用時是不

2、夠的。這篇論文旨在介紹一種針對車輪對的圓弧表面磁參數(shù)變化的檢測案例。這些圓弧表面磁參數(shù)的變化是由于材料的老化，而材料老化是由于材料疲勞造成的。 1.簡介： 到目前為止測試車輪制造過程中通過x射線(RT),超聲波(UT),渦流(ET)和磁(MT)。洛氏、布氏硬度測試也是非常重要的。在鐵路車輛操作的基本方法診斷車輪超聲和渦流的方法。然而,即便是這種復(fù)雜的檢驗流程的使用確保轉(zhuǎn)向架的完整可靠性和底盤和車輪組關(guān)節(jié),作為鐵路的記錄在分析已知的情況下失敗。本文給出的方法要求鐵路輪對的進一步診斷。該方法測試PKP車輛維護植物。提出測試是基于鋼的鐵磁特性以及magneto-mechanical效應(yīng)和磁過程發(fā)

3、生在材料由于疲勞和引起的退化。這個新的診斷是一個獨特的有價值的補充的檢驗,特別是車輪的滾動表面測試。額外的測試基于測量的切向分量在滾動表面磁場強度檢測有害內(nèi)應(yīng)力及其發(fā)展隨著時間的推移以及材料的物理參數(shù)的變化由于操作不當。 2. 制造過程中的缺陷檢測 控制輪集,車輪中心、實心輪子和輪胎的復(fù)雜過程，非常有限的概率失敗的組件使用。不同的診斷方法通常應(yīng)用[1]。如Tab.1表示。 制造過程的車輪組成分測試 檢測元素 檢測方法 射線 硬度測試 幾何測量 超聲檢測 磁檢測 渦流檢測 輪胎 X X X X X 車輪中心 X X X X X 實

4、心輪 X X X X X 車輪組 X X X X X 這些方法導(dǎo)致消除塊材料不連續(xù)(缺陷),微觀結(jié)構(gòu)變化和由輪或輪中心材料硬度的變化而引起的內(nèi)部應(yīng)力。UT和RT可以用來檢測散裝材料,而磁檢測則用來檢測材料的表層和次表層。 3.車輪組在役檢測 對于高速列車的輪組在役檢測，主要是集中在循環(huán)檢查,當滾動表面的幾何已經(jīng)被評估過的時候。滾動表面的磨損情況表明,了車輪和軌道的相互作用。在檢查或維修的期間,磁檢測和超聲檢測大多用于車輪組檢測(車輪組保留或拆除)——Tab.2。 車輪組成分的在役檢測 待檢測元素 檢測方法 射線檢測 硬度測試 幾何測

5、量 超聲檢測 磁檢測 渦流檢測 車輪 X X X 車輪組 X X X 超聲波(UT)可以穿透車輪輪胎并且檢測深度范圍為10毫米甚至更深層次,而渦流測試(EC)可以覆蓋表面開始向下10毫米的厚度層。選擇適當?shù)臏u電流探針頻率檢測到材料的不連續(xù)而非結(jié)構(gòu)性變化。在選擇的頻率范圍內(nèi)這種變化并不是“可見”。 4在役疲勞檢測 當車輪組在使用時,滾動面上層容易出現(xiàn)變化。這些都是結(jié)構(gòu)變化以及磁性和力學(xué)參數(shù)的變化。這些可以表明在使用過程中在輪組的滾動表面積累的疲勞應(yīng)力。常見的診斷程序?qū)Σ牧辖Y(jié)構(gòu)不敏感。車輪材料進行調(diào)查的

6、幫助下BEMI(巴克豪森噪聲和渦流顯微鏡)的弗勞恩霍夫研究所(Saabrucken,德國)。用頻率大于1,5 MHz的渦流檢測模塊(3、4)(圖2)檢測接觸載荷引起的材料結(jié)構(gòu)的變化(圖1)。 表一，輪胎材料結(jié)構(gòu)樣品PA和PB 表二本pA和pB 以及振幅軌跡曲線在不同的操作頻率下的BEMI渦流圖像樣 5. 以漏磁場作為診斷媒介的檢測 曲面表面的磁漏磁場測量是按照材料的反映了不同機械材料的條件的磁導(dǎo)率來進行的。這可能也就解釋了顯示初始磁化曲線的變化:材料樣本取自一個新的車輪(已經(jīng)聚集在方向盤前)和材料樣品接觸影響加載在?阿姆斯勒試驗臺(Fig.3a)。硬材料樣本來自一組車輪在方

7、向盤上(Fig.3b) 圖2.材料的磁參數(shù)的變化進行變形和硬化(a)新鮮和退化的材料(b)+ 圖3.材料的磁參數(shù)的變化進行變形和硬化(a)新鮮和退化的材料(b)+ 在這兩種情況下矯頑力Hc的增加和材料磁導(dǎo)率的減少是可觀察的[5]。可以檢測可塑體沿著滾動表面的變化,內(nèi)部壓力的影響[5]以及相變材料由于材料的磁參數(shù)和磁化強度的變化而引起的變化是可以測量的。為了達到這個結(jié)果，測量車輪的滾動表面在外部磁場(例如地球磁場)的磁場強度是必要的(Ht)。然而,重復(fù)測量只是確保當?shù)嘏c標準磁場磁軛磁化和探針(校準)檢測磁化強度的變化,如圖4所示。 材料的磁性參數(shù)的變化的檢測擴展了已知

8、的輪軸檢測方法。目前在鐵路工程部門，實驗室和鐵路維修和保養(yǎng)工作都在進行研究。一些博士論文也提到了這種研究。圖5顯示:測試的數(shù)值模擬,b)測試平臺,c)新車輪磁漏磁場測量的結(jié)果,和d)的磁漏磁場測量結(jié)果輪表面受損(物質(zhì)結(jié)構(gòu)的變化)。在磁測量過程中的車輪組的附加信息提高了診斷的可靠性,特別是在輪軸操作。這反過來增加了鐵路運輸安全。 6.結(jié)論 在輪對診斷中引入附加的磁性測試為材料的不連續(xù)以及結(jié)構(gòu)性變化(同質(zhì)性)檢測提供了附加的信息。在確保適當?shù)母咚倭熊嚨陌踩院筒僮髦?，這是必要的。表3列出了能提高診斷的可靠性的新的測試方法, 檢測元素 檢測方法 幾何測量 超聲檢測 磁檢

9、測 渦流檢測 車輪 X X X X 車輪組 X X X X 提出的可靠性檢驗應(yīng)該被鐵路安全當局驗證。擴大現(xiàn)有的測試平臺通過添加一些測試探頭，并沒有顯著增加質(zhì)量成本。 SUPPLEMENTARY MAGNETIC TESTS FOR RAILWAY WHEEL SETS Summary: During manufacturing process the wheel set is subjected to many different flaw detection methods; however, these methods are

10、 not sufficient while the wheel set is in service. The paper presents an example of monitoring of magnetic parameters changes of wheel set rolling surface (changes result from material degradation due to material fatigue). 1. INTRODUCTION So far testing the wheels during the manufacturing process

11、has been done by X-ray (RT), ultrasound (UT), eddy currents (ET) and magnetic (MT) . Rockwell or Brinell hardness tests are also very important. During rail vehicle operation the basic methods of diagnosing the wheels are ultrasound and eddy current methods. However, even the uses of such sophistic

12、ated inspection processes do not ensure full reliability of the bogie and undercarriage and the wheel set in articular, as documented in analysis of known cases of railway failures. The method presented in the paper asks for a further step in the railway wheel sets diagnostics. This method is teste

13、d in the PKP rolling stock maintenance plants. Proposed tests are based on the ferromagnetic properties of the steels as well as on magneto-mechanical effects and magnetic processes occurring in the material and caused by degradation due to fatigue. This new diagnostics is a distinct valuable supple

14、ment of the wheel inspection and especially of the wheel rolling surface tests. Additional tests based on the measurement of the tangential component of the magnetic field intensity at the rolling surface detect harmful internal stresses and their development with time as well as change in the physi

15、cal parameters of the material due to improper operation. 2. WHEEL SET DIAGNOSTICS DURING MANUFACTURING PROCESS The complex process of controlling wheel sets, wheel centers, monobloc wheels and wheel tires has tremendously limited the probability of failure of the used components. Different diagno

16、stic methods are usually applied [1]. They are indicated in Tab.1. Wheel set components testing during manufacturing process These methods result in eliminating pieces with material discontinuities (flaws), microstructure changes and internal stresses defined by change in wheel or wheel centre

17、 material hardness. UT and RT allow to inspect the bulk material, while by MT a check of the surface and subsurface layers is only performed. 3. WHEEL SET OPERATIONAL DIAGNOSTICS Wheel set operational diagnostics (for high speed trains) is mostly focused on cyclic inspections,when the rolling surf

18、ace geometry is assessed. Rolling surface wear shows how wheel and track interact. During inspection or repair cycles ET and UT are mostly used for wheel set testing (wheel sets either remain in place or are dismantled) – Tab.2. Ultrasonic waves (UT) penetrate the wheel tire material and inspect

19、a depth range of 10 mm and deeper, while eddy currents tests (EC) can cover the 10 mm thick layer beginning at the surface. Eddy current probe frequencies are selected so that the tests will detect any material discontinuity rather than structural changes. Such changes are not “visible” in the frequ

20、ency range under consideration. 4. FATIGUE PROCESSES DETECTION When the wheel set is in operation, changes emerge in the rolling surface upper layer. These are structural changes as well as magnetic and mechanical parameter changes. These can indicate the fatigue processes which accumulate in the

21、wheel set’s rolling surface. The common diagnostics procedures are not sensitive to the material structure. The wheel set materials were investigated with the help of BEMI (Barkhausen Noise and Eddy Current Microscope) in the Fraunhofer Institute (Saabrücken, Germany). Detection of contact load ind

22、uced changes in the material structure (Fig.1)were detected by the implemented eddy current module for frequencies greater than 1,5 MHz [3,4](Fig.2). 5. MAGNETIC LEAKAGE FIELD USED AS A DIAGNOSTIC MEDIUM The magnetic leakage field measured at the rolling surface varies in accordance

23、with material’s magnetic permeability, which in turn reflects the mechanical material’s condition. This may be explained by example showing changes in initial magnetisation curves:Material sample taken from a new wheel tire (before it has been assembled at the wheel) and material sample subjected to

24、 contact oads at AMSLER test rig (Fig.3a).Hardened material sample taken from a wheel tire set on the wheel (Fig.3b) In both cases also a significant increase in the magnetic coercion Hc and a decrease in material’s magnetic permeability are observed [5]. It is possible to detect changes in plastic

25、 strains along the rolling surface, impact of internal strains [5] as well as the phase changes of the material due to changes in material’s magnetic parameters and magnetisation. In order to attain this result it is sufficient to measure magnetic field intensity (Ht) only along the wheel’s rolling

26、 surface in the external magnetic field (e.g. Earth’s magnetic field). However, a good measurement repeatability is only ensured by a local yoke magnetisation and with standard field probes (calibration), detecting magnetisation changes as shown in Fig.4. Detection of changes in material’s magnet

27、ic parameters extends the range of known wheel set testing methods. Research is currently carried out in the Railway Engineering Department on a laboratory scale and in railway repair and maintenance works. Some investigation is performed also within a Ph.D. thesis. Fig.5 shows: a) the numerical si

28、mulation of the test, b) the test rig, c) the results of the magnetic leakage field measurements for a new wheel, and d) the results of the magnetic leakage field measurements for a wheel with a damaged surface (change in material structure). Additional information on the wheel set condition orig

29、inating from magnetic measurements increases the diagnostic reliability, in particular during wheel set operation. This in turn increases rail transport safety. 6. CONCLUSIONS Introducing additional magnetic tests to operational wheel set diagnostics provides additional information on material dis

30、continuity as well as on structural changes (homogeneity). This is essential in order to ensure proper safety and operation of high speed trains. Table 3 sets out new testing methodology which will increase diagnostic reliability The reliability of the proposed inspection should be validated by railway safety authorities.Expanding existing test rigs by adding some test probes does not significantly increase the quality costs。