畢業(yè)設(shè)計(jì)外文翻譯在冷軋廠工作軸過早發(fā)生故障的分析

1、 本科畢業(yè)設(shè)計(jì)外文翻譯題目：在冷軋廠工作軸過早發(fā)生故障的分析 學(xué) 院:機(jī)電與建筑工程學(xué)院專 業(yè):機(jī)械設(shè)計(jì)制造及其自動(dòng)化學(xué) 號(hào):200806101332學(xué)生姓名: 指導(dǎo)教師: 日 期:2012年2月在冷軋廠工作軸過早發(fā)生故障的分析hongchun li, zhengyi jiang, kiet , tieu , weihua sun澳大利亞，新南威爾士州2522，wollongong，wollongong大學(xué)，機(jī)械學(xué)院，材料和機(jī)械電子工程濟(jì)南鋼鐵有限公司技術(shù)中心，濟(jì)南250101，中國收到2006年9月12日，在2007年1月15日收到，2007年1月18日2007年5月23日網(wǎng)上提供概述在本文

2、中，對(duì)幾個(gè)冷連軋機(jī)工作軸過早失效進(jìn)行了調(diào)查。為了研究工作軸表面特性和破壞機(jī)理，化學(xué)成分，微觀結(jié)構(gòu)和軋軸材料的硬度進(jìn)行了研究。已計(jì)算在工作軸剝落面積的壓力，確定應(yīng)力狀態(tài)。在研究中，軋軸磨損和損壞的原因已經(jīng)查明。對(duì)工作軸表面圖像進(jìn)行了研究，發(fā)現(xiàn)了已損壞的軋軸磨損特性的特點(diǎn)。人們已經(jīng)發(fā)現(xiàn)，經(jīng)營的因素和冶金缺陷將影響在冷軋帶鋼軋軸的使用壽命。2007 elsevier b.v保留所有權(quán)利。關(guān)鍵詞：穿;工作軸冷軋;應(yīng)力分布1.介紹目前，冷軋帶鋼生產(chǎn)上的冷連軋帶鋼軋機(jī)或倒車的冷連軋機(jī)工作軸破壞為1非圓形變形2。應(yīng)用于冷連軋，板形好，型材和平整度3,4得到控制模型的基礎(chǔ)上。在冷連軋機(jī)工作軸發(fā)揮主導(dǎo)作用，使帶

3、鋼的變形來實(shí)現(xiàn)所需的形狀，輪廓和尺寸。然而，工作軸在極其惡劣的條件下運(yùn)作，在經(jīng)營成本的冷連軋機(jī)的最重要環(huán)節(jié)之一，是有關(guān)工作軸5。工作軸磨損的材料，變形，熱凸度，氧化鐵皮及帶鋼表面粗糙度等的影響，6-14已查處，并為混合潤滑摩擦模型15。工作軸的磨損，影響熱軋帶鋼質(zhì)量和工作軸使用壽命顯著。在軋鋼工作軸的過程中，受高循環(huán)荷載和水平高的耐磨性。與熱軋相比，冷軋鋼軋制材料的抗變形能力是非常高。在軋軸咬軋軸表面受到高壓力是大于10000 mpa和進(jìn)一步剪應(yīng)力產(chǎn)生摩擦16在軸/帶接口。工作軸過早失效滾動(dòng)不僅增加成本，而且還軋機(jī)停機(jī)時(shí)間，生產(chǎn)力顯著影響。偽造合金鋼工作軸過早失敗的原因可能是操作技術(shù)和冶金軋軸

4、因素的綜合影響。經(jīng)營的因素，包括軋制負(fù)荷，潤滑，軋制速度，運(yùn)營商的經(jīng)驗(yàn)，如軋制參數(shù)的選擇。工作軸的質(zhì)量，包括非金屬夾雜物的存在，鑄造缺陷和相變16。在本文中，冷連軋機(jī)工作軸過早失效。作者對(duì)軸的化學(xué)成分，顯微組織和硬度軋軸材料進(jìn)行了審查使用收集剝落樣品，并進(jìn)行了拉伸試驗(yàn)。在剝落面積的應(yīng)力狀態(tài)也已確定找到的軋軸磨損和剝落損壞的原因。工作軸表面圖像進(jìn)行了研究，并已確定為損壞的軋軸磨損的特點(diǎn)。人們已經(jīng)發(fā)現(xiàn)，冶金缺陷和運(yùn)行參數(shù)的影響在冷軋帶鋼軋軸使用壽命。2.軋制工藝和參數(shù)圖1.a2-的立場的匯接寒冷的帶鋼軋機(jī)。 （1）成卷 #2（2）張力計(jì)，（3）激光測(cè)速儀，（4）測(cè)厚儀，（5）支撐2，（6 ）支撐1

5、，（7）卷取機(jī)1（8）開卷機(jī)。圖1概述了2支撐的緊湊型冷軋帶鋼軋機(jī)的原理。熱軋帶鋼是這四軸冷連軋機(jī)的初始原料。熱軋鋼卷厚度約1.5-5.0毫米，寬度和重量35噸，在900-1680毫米。前滾酸洗的熱軋帶鋼氧化鐵皮被刪除。最大的酸洗速度是60米/分鐘和酸浴的溫度大約是70-85攝氏度。酸洗過程中不影響隨后的結(jié)果。在軋制過程中采用的agc液壓控制，厚度上線控制，自動(dòng)測(cè)量速度。 潤滑劑使用的是quakeroln680-2-bpd。工作軸鍛造鋁合金鋼含有約4的鉻，hsc硬度為83至85。在工作軸cvc的個(gè)人資料。表1和表2顯示的軋制參數(shù)和工作軸。3.結(jié)果與討論3.1 工作軸取樣其競選期間的剝落工作軸的

6、標(biāo)本，他們被切斷，并準(zhǔn)備利用掃描電子顯微鏡和光學(xué)顯微鏡觀察。表面缺陷圖像被從四個(gè)不同的使用的軋軸，金屬焊接，綁扎，并在他們的競選剝落顯著。所有的工作軸，用于在不同的立場。軋軸表面粗糙度，ra，測(cè)量的工作軸軋機(jī)安裝之前和之后。3.2.剝落圖2（a和b）顯示了被剝落工作軸工作軸缺陷的部分和在d-d軸的情況下，似乎是一條曲線，這是在軋軸表面的長度約18毫米的剝落。然而，裂紋有沒有深度，根據(jù)超聲波測(cè)試。然而，對(duì)軸ð的損害可能是在第一階段的軋軸a.表1軋制參數(shù)紙架直徑（毫米）冷軋帶鋼（毫米）減少（）軸分離力（kn）軋制速度（米/分）軋制長度（公里）a14491.35×12403419

7、,8908674.515b24480.85×15003519,93296013.64c14491.1×124028.517,6524985.139d24490.61×124028.217,52867911.304表2工作軸參數(shù)軋軸化學(xué)成分（wt）粗糙度（微米）硬度（hsc）碳錳鎳硅鉻鉬工作前工作后a0.810.360.270.403.970.510.80.72983-85b0.820.32c0.830.55d0.870.47圖2.工作軸剝落。 （a）軸剝落a和 （b）軸剝落d. 典型的剝落面積大小已剝落面積為1430毫米的長度，周長353毫米和85毫米深

8、度的最大的軋軸a.測(cè)量。軋軸過早失效后，4.515公里的連軋服務(wù)就是比軋軸四軸材料的微觀結(jié)構(gòu)工齡進(jìn)行了檢查，光學(xué)顯微鏡，如圖3所示。由此可以看出，有一個(gè)深度為75毫米硬化區(qū)的工作軸，因此所采取的微觀結(jié)構(gòu)的區(qū)域與中心的工作軸a.圖是從軋軸表面的距離。 3（a）是一個(gè)區(qū)接近表面，（b）約在深度75毫米從表面上看，和（c）從表面深度約85毫米。可以看出，晶粒尺寸從11.5至20米不等。更重要的是，粗糧底下發(fā)現(xiàn)軋軸表面，這是保證最低硬化深度為85毫米少75毫米。圖3.工作軸材料的微觀結(jié)構(gòu)。 （a）地區(qū)靠近面，（b）約75毫米的表面深度（c）表面深度約85毫米。圖4.打擊軸a.斯特朗試驗(yàn)機(jī)上進(jìn)行拉伸試驗(yàn)

9、與平板標(biāo)本。對(duì)樣品進(jìn)行了削減從大剝落件從英斯特朗試驗(yàn)機(jī)軸a.結(jié)果表明，抗拉強(qiáng)度和屈服強(qiáng)度低于制造商的要求。圖4顯示了裂紋工作軸a.正常工作軸的壓力和剪切應(yīng)力，分別由赫茲分析計(jì)算。計(jì)算的正應(yīng)力和剪應(yīng)力17開發(fā)與帶鋼接觸的結(jié)果顯示在圖5和圖6中可以看出。圖5講的一些組件（sxx =r）和（szz =z，）達(dá)成一項(xiàng)在表面的大值。兩軸a和d是新軸。穿的工作軸或支承軸后面的個(gè)人資料可能不實(shí)際的因素，促進(jìn)軋軸損壞。然而，在領(lǐng)先的邊緣或由于折疊帶鋼的冷軋厚度增加一倍局部高負(fù)荷可能超過軋軸表面的剪切強(qiáng)度。這是有可能形成一個(gè)或多個(gè)壓力裂縫，在靠近表面的地方超載領(lǐng)域。裂縫軸軸的方向平行，但在一個(gè)非徑向方向傳播（圖

10、2（b）。由于軋機(jī)扭轉(zhuǎn)滾動(dòng)功能，裂縫可能會(huì)逐步傳播（圖4）。因內(nèi)部不當(dāng)?shù)奈⒂^結(jié)構(gòu)（圖3（b），內(nèi)的工作軸表面裂紋擴(kuò)展開發(fā)。因此，發(fā)生大的表面剝落。這樣可以減少工作軸使用壽命顯著（見圖7，熱軋帶鋼軋軸公里長度很短，工作軸前被損壞）。圖5.正常講開發(fā)與熱軋帶鋼接觸的結(jié)果圖6.剪應(yīng)力與熱軋帶鋼接觸的結(jié)果圖7.前滾失敗和表面粗糙度的冷軋帶鋼的長度之間的關(guān)系3.3.地帶的焊接圖8顯示了軋制，軋機(jī)的第二站，第三遍后，將工作軸b軋軸表面上的金屬焊接。坐落在熱軋帶鋼的邊緣，損害和它的面積約650毫米，寬度和周長707毫米。不正確的軸形或條狀不佳，可能會(huì)導(dǎo)致在具體的軋制壓力，這反過來又導(dǎo)致當(dāng)?shù)馗咻S表面溫度。因此

11、增加縮進(jìn)形式的軋軸表面的塑性變形，甚至剝落，是造成這些超載嚴(yán)重的熱開發(fā)的地方增加了熾裂或瘀傷。取出后由于去除軋軸表面焊接綁扎部分，工作軸可連續(xù)使用。然而，工作軸的磨損是這種情況下，具有重要意義，如圖所示。與其他案件相比，7軸表面粗糙度降低顯著（見軸b）。 b軸的使用壽命無明顯影響，由于其連續(xù)使用。3.4.帶狀重去皮明亮的區(qū)域出現(xiàn)的形式與一個(gè)非常粗糙的表面圓周方向上工作軸Ç面向，如圖9所示。刪除層厚度約0.1毫米和0.9毫米之間。它被廣泛接受，帶是典型的表面損傷，高鉻鋼工作軸時(shí)，他們使用更長的運(yùn)行時(shí)間后，在相同的關(guān)鍵立場和位置。然而，案件發(fā)生在第一遍后運(yùn)動(dòng)時(shí)間短滾動(dòng)軸Ç。帶起

12、源發(fā)生交替交替熱負(fù)荷超過疲勞的表面材料的剪切強(qiáng)度時(shí)，組合中的摩擦力。據(jù)推測(cè)，表面裂縫內(nèi)主要熾裂發(fā)展和傳播剪從軸，直到熾裂地區(qū)的深度。當(dāng)軋軸表面局部惡化，峰值剪切力是誘導(dǎo)和領(lǐng)導(dǎo)到周圍軸筒去皮帶的發(fā)展速度非?？?，導(dǎo)致軋軸磨損。圖8.剝離工作軸的焊接圖9.帶工作軸圖9展出的情況軸使用壽命上有重大影響力和軋軸磨損，這表明，軋軸表面粗糙度的降低在短期公里冷軋帶鋼長度顯著（見圖7，軸c）。因此，這一缺陷顯著提高了軋軸磨損。4.結(jié)論本文3種在冷軋廠工作軸表面缺陷進(jìn)行了調(diào)查。它的結(jié)論是講一些組件達(dá)到在表面的大值，這可能會(huì)導(dǎo)致工作軸裂紋，降低使用壽命的結(jié)果。在此期間，冶金缺陷，如不當(dāng)編寫的微觀結(jié)構(gòu)，提高軋軸表面

13、剝落材料的風(fēng)險(xiǎn)。地帶焊接軋機(jī)操作不正確造成的。提高工作軸溫度控制和喂養(yǎng)條狀，可避免此類事件。捆扎是第三次在這項(xiàng)研究中遇到的軋軸表面損傷。據(jù)認(rèn)為，更好的軋軸冷卻與潤滑，可減少損壞的風(fēng)險(xiǎn)，并提高工作軸使用壽命。致謝第一作者想感謝wollongong大學(xué)大學(xué)研究生獎(jiǎng)（upa）的當(dāng)前工作的支持。筆者也想感謝t. silver博士的協(xié)助下，完成了這篇文章。參考文獻(xiàn)1 p. montmitonnet, e. massoni, m. vacance, g. sola, p. gratacos, modelling for geometrical control in cold and hot rolling

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22、toperation versus manufacture, eng. fail. anal. 7 (2000) 5567. 17 a. boresi, o.m. sidebottom, advanced mechanics of materials, wiley, 1985.analysis of premature failure of work rolls in a cold strip planthongchun li, zhengyi jiang, kiet , tieu , weihua sunschool of mechanical, materials and mechatro

23、nic engineering, university of wollongong, wollongong, nsw 2522, australia technology centre, jinan iron and steel ltd., jinan 250101, pr china received 12 september 2006; received in revised form 15 january 2007; accepted 18 january 2007 available online 23 may 2007 abstract in this paper, prematur

24、e failures of several work rolls on a cold strip mill were investigated. in order to study the work roll surface feature and failure mechanism, the chemical compositions, microstructures and the hardness of roll materials were examined. the stresses in the spalled area of the work roll have been cal

25、culated, and the stress states identified. the causes for the roll wear and damage have been identified in the study. the surface images of the work rolls have been studied, and the characteristics of wear have also been characterised for the damaged rolls. it has been found that the operating facto

26、rs and metallurgical defects affected the roll service life in cold strip rolling. 2007 elsevier b.v. all rights reserved. keywords: wear; work roll; cold rolling; stress distribution 1. introduction at present, the cold rolled strip is produced on a tandem cold strip mill or a reversing cold strip

27、mill where the work rolls are flattened 1 to a non-circular deformed shape 2. based on the control models applied to the cold strip rolling, a good strip shape, profile and flatness 3,4 was obtained. in a cold rolling mill, the work rolls play the dominant role, making the strip deformation to achie

28、ve the desired shape, profile and dimensions. however, the work rolls operate under extremely arduous conditions, and one of the most important segments in operating cost of a cold mill is relevant to work rolls 5. the effects of the material, deformation, thermal crown, oxide scale and strip surfac

29、e roughness, etc., on the wear of work roll 614 have been investigated, and a tribological model for mixed lubrication was developed 15. the wear of work rolls affects the rolled strip quality and the work roll service life significantly. in strip rolling process, work rolls are subject to high cycl

30、ic loading and high levels of abrasion. the deformation resistance of rolled materials is extremely high in cold steel rolling compared with that of hot rolling. the roll surface in the roll bite is subjected to high pressure that is greater than 10,000 mpa and further shear stress generated by fric

31、tion 16 at the roll/strip interface. the premature failure of a work roll increases not only the cost of the rolling but also the down time of the mill, affecting the productivity significantly. the causes for premature failure of the forged alloy steel work rolls can be the combined effects of oper

32、ating techniques and the roll metallurgical factors. operating factors include the choice of rolling parameters such as the rolling load, lubrication, rolling speed, and the experience of operators. work roll quality includes the presence of nonmetallic inclusions, casting defects and phase transfor

33、mations 16. in this paper, the authors investigated the premature failures of work rolls on a cold strip mill. the chemical compositions, microstructures and the hardness of roll materials were examined using the collected spalled samples, and tensile tests were conducted. the stress states in the s

34、palled area have also been determined to find the causes of the roll wear and spall damage. the surface images of the work rolls have been studied, and the characteristics of wear have been identified for the damaged rolls. it has been found that both metallurgical defects and operation parameters a

35、ffected the roll service life during the cold strip rolling. 2. rolling process and parameters fig. 1. a 2-stand tandem cold strip mill. (1) coiling #2, (2) tension meter, (3) laser velometer, (4) thickness gauge, (5) stand #2, (6) stand #1, (7) coiling machine #1 and (8) uncoiling machine. fig. 1 s

36、chematically outlines the 2-stand compact cold strip rolling mills. hot rolled strip was the initial feedstock for this 4-high cold mill. the hot rolled coil is about 1.55.0 mm in thickness, 9001680 mm in width and 35 tonnes in weight. the oxide scale on the hot strip was removed by pickling before

37、rolling. the maximum pickling speed is 60 m/min and the temperature of acid bath is about 7085 .c. the pickling process does not affect the subsequent results. the agc hydraulic control, thickness on-line control, and the automatic speed measurement were adopted in the rolling process. quakeroln 680

38、-2-bpd was used as a lubricant. work rolls were made of forged alloy steel containing approximately 4% cr with hardness from hsc 83 to 85. cvc profile was employed in the work rolls. tables 1 and 2 show the parameters of the rolling and the work rolls. 3. results and discussion 3.1. work roll sampli

39、ng the samples from a spalled work roll during its campaign were obtained, and they were cut and prepared for observation using the scanning electron microscope and optical microscope. surface images of the defects were taken from the four different used rolls, which were marked by metal welding, ba

40、nding and spalling during their campaign. all of the work rolls were used in different stands. roll surface roughness, ra, was measured from the work roll before and after being installed into the rolling mill. 3.2. spall fig. 2 (a and b) shows the defective portion of work rolls that were spalled o

41、n work rolls a and d. in the case of roll d, the spall seems to be a curve which is about 18 mm in length on the roll surface. however, the crack has no depth according to ultrasonic test. nevertheless, the damage on roll d is possibly at the first stage of roll a.table 1 rolling parameters roll sta

42、nd diameter (mm)rolled strip (mm)reduction (%)roll separating force (kn)rolling speed (m/min)rolled length (km)a14491.35×12403419,8908674.515b24480.85×15003519,93296013.64c14491.1×124028.517,6524985.139d24490.61×124028.217,52867911.304table 2 work roll parameters roll chemical co

43、mposition (wt%)roughness (m)hardness (hsc)cmnnisicrmobefore workingafter workinga0.810.360.270.403.970.510.80.72983-85b0.820.32c0.830.55d0.870.47fig. 2. spalling of work rolls. (a) spalled roll a and (b) spalled roll d. typical size of the spalled area has been measured in the case of roll a. the sp

44、alled area is the maximum of 1430 mm in length, 353 mm in circumference and 85 mm in depth. the roll prematurely failed after 4.515 km strip rolling service that is less than the rolling service length of roll d. microstructure of the roll material was examined by an optical microscope, as shown in

45、fig. 3. it can be seen that there is a 75 mm of depth of hardening zone in the work roll, so the area of the microstructure taken was with a distance from the roll surface to the centre of the work roll a. fig. 3(a) is a region close to the surface, (b) approximately 75 mm in depth from the surface,

46、 and (c) about 85 mm in depth from the surface. it can be seen that the size of grain varies from 11.5 to 20 m. what is more, coarse grain was found 75 mm beneath the roll surface, which is less than the guaranteed minimum hardening depth of 85 mm. fig. 3. microstructure of the material of work roll

47、. (a) a region close to the surface, (b) approximately 75 mm in depth from the surface and (c) about 85 mm in depth from the surface. fig. 4. crack on the roll a.tensile tests were carried out on an instron testing machine with flat specimens. the samples were cut from the large spalled pieces of th

48、e roll a. results obtained from the instron testing machine indicate that the tensile and yield strengths are below the manufacturers requirements. fig. 4 shows the crack on the work roll a. the normal stress and shear stress of work roll a were calculated by hertzian analysis. the calculated normal

49、 stress and shear stress 17 developed as a result of contact with the steel strip are shown in figs. 5 and 6. it can be seen in fig. 5 that some of the components of stresses (sxx = r) and (szz = z) reach a large value at the surface. both rolls a and d are new rolls. worn profile of either the work

50、 roll or the back up roll may not be the actual factor contributing to the roll damage. however, high local loads at leading edges or doubling of the rolled thickness due to folding strip may exceed the roll surface shear strength. it is likely that one or more pressure cracks is formed in an area o

51、f local overload near the surface. the cracks are oriented parallel to the roll axis but propagate in a non-radial direction (fig. 2(b). due to the reversing rolling feature of the rolling mill, cracks may progressively propagate (fig. 4). due to the inner improper microstructure (fig. 3(b), crack p

52、ropagation develops within the working surface of the roll. as a result, a large surface spall occurred. this can reduce the work roll service life significantly (see fig. 7, the rolled strip kilometer length for roll a was short before the work roll was damaged). fig. 5. normal stresses developed a

53、s result of contact with the rolled strip.fig. 6. shear stresses developed as result of contact with the rolled strip.fig. 7. relationship between the length of rolled strip before roll failure andsurface roughness.3.3. strip welding fig. 8 shows the metal welding on the roll surface of the work rol

54、l b after the third pass of rolling, serving on the second stand of the mill. the damage was located at the edge of the rolled strip, and its area is about 650 mm in width and 707 mm in circumference. incorrect roll profile or poor strip shape can result in high specific rolling pressure which in tu

55、rn leads to a high roll surface temperature at the local area. consequently increasing the plastic deformation of the roll surface in the form of indentations, or even spalling, is caused in these overloaded areas where the severe heat development adds fire cracks or bruises. after removing the band

56、ing part due to strip welding on the roll surface, the work roll can be used continuously. however, the wear of the work roll is significant for this case, as shown in fig. 7 the roll surface roughness reduces dramatically (see roll b) compared to other cases. the service life of the roll b was not

57、obviously affected due to its continuous usage. 3.4. banding heavily peeled bright areas appear on the work roll c oriented in the circumferential direction in the form of bands with a very rough surface, as shown in fig. 9. the removed layer has a thickness of between about 0.1 and 0.9 mm. it is well accepted that the banding is typical surface damage to high chrome work rolls when they are used after a longer run time in the same critical stands and positi