外文翻译(机械类)-在冷轧厂工作轴过早发生故障的分析

在冷轧厂工作轴过早发生故障的分析 澳大利亚，新南威尔士州2522，Wollongong，Wollongong大学，机械学院，材料和机械电子工程 济南钢铁有限公司技术中心，济南250101，中国 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日网上提供 概述 在本文中，对几个冷连轧机工作轴过早失效进行了调查。为了研究工作轴 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 面特性和破坏机理，化学成分，微观结构和轧轴材料的硬度进行了研究。已计算在工作轴剥落面积的压力，确定应力状态。在研究中，轧轴磨损和损坏的原因已经查明。对工作轴表面图像进行了研究，发现了已损坏的轧轴磨损特性的特点。人们已经发现，经营的因素和冶金缺陷将影响在冷轧带钢轧轴的使用寿命。 2007 Elsevier B.V保留所有权利。 关键词：穿；工作轴冷轧；应力分布 1.介绍 目前，冷轧带钢生产上的冷连轧带钢轧机或倒车的冷连轧机工作轴破坏为[1]非圆形变形[2]。应用于冷连轧，板形好，型材和平整度[3,4]得到控制模型的基础上。在冷连轧机工作轴发挥主导作用，使带钢的变形来实现所需的形状，轮廓和尺寸。然而，工作轴在极其恶劣的条件下运作，在经营成本的冷连轧机的最重要环节之一，是有关工作轴[5]。工作轴磨损的材料，变形，热凸度，氧化铁皮及带钢表面粗糙度等的影响，[6-14]已查处，并为混合润滑摩擦模型[15]。工作轴的磨损，影响热轧带钢质量和工作轴使用寿命显着。在轧钢工作轴的过程中，受高循环荷载和水平高的耐磨性。与热轧相比，冷轧钢轧制材料的抗变形能力是非常高。在轧轴咬轧轴表面受到高压力是大于10000 MPa和进一步剪应力产生摩擦[16]在轴/带接口。 工作轴过早失效滚动不仅增加成本，而且还轧机停机时间，生产力显着影响。伪造合金钢工作轴过早失败的原因可能是操作技术和冶金轧轴因素的综合影响。经营的因素，包括轧制负荷，润滑，轧制速度，运营商的经验，如轧制参数的选择。工作轴的质量，包括非金属夹杂物的存在，铸造缺陷和相变[16]。 在本文中，冷连轧机工作轴过早失效。作者对轴的化学成分，显微组织和硬度轧轴材料进行了审查使用收集剥落样品，并进行了拉伸试验。在剥落面积的应力状态也已确定找到的轧轴磨损和剥落损坏的原因。工作轴表面图像进行了研究，并已确定为损坏的轧轴磨损的特点。人们已经发现，冶金缺陷和运行参数的影响在冷轧带钢轧轴使用寿命。 2.轧制工艺和参数 图1.A2-的立场的汇接寒冷的带钢轧机。 （1）成卷 #2（2）张力计，（3）激光测速仪，（4）测厚仪，（5）支撑＃2，（6 ）支撑1，（7）卷取机＃1（8）开卷机。 图1概述了2支撑的紧凑型冷轧带钢轧机的原理。热轧带钢是这四轴冷连轧机的初始原料。热轧钢卷厚度约1.5-5.0毫米，宽度和重量35吨，在900-1680毫米。前滚酸洗的热轧带钢氧化铁皮被删除。最大的酸洗速度是60米/分钟和酸浴的温度大约是70-85摄氏度。酸洗过程中不影响随后的结果。在轧制过程中采用的AGC液压控制，厚度上线控制，自动测量速度。 润滑剂使用的是quakeroln680-2-BPD。 工作轴锻造铝合金钢含有约4％的铬，HSC硬度为83至85。在工作轴CVC的个人资料。表1和表2显示的轧制参数和工作轴。 3.结果与讨论 3.1 工作轴取样 其竞选期间的剥落工作轴的标本，他们被切断，并准备利用扫描电子显微镜和光学显微镜观察。表面缺陷图像被从四个不同的使用的轧轴，金属焊接，绑扎，并在他们的竞选剥落显着。所有的工作轴，用于在不同的立场。轧轴表面粗糙度，Ra，测量的工作轴轧机安装之前和之后。 3.2.剥落 图2（a和b）显示了被剥落工作轴工作轴缺陷的部分和在D-D轴的情况下，似乎是一条曲线，这是在轧轴表面的长度约18毫米的剥落。然而，裂纹有没有深度，根据超声波测试。然而，对轴e的损害可能是在第一阶段的轧轴A. 表1 轧制参数   纸架直径（毫米） 冷轧带钢 （毫米） 减少（％） 轴分离力（kN） 轧制速度（米/分） 轧制长度（公里） A 1449 1.35×1240 34 19,890 867 4.515 B 2448 0.85×1500 35 19,932 960 13.64 C 1449 1.1×1240 28.5 17,652 498 5.139 D 2449 0.61×1240 28.2 17,528 679 11.304               表2 工作轴参数   轧轴化学成分（wt％） 粗糙度 （微米） 硬度（HSC） 碳 锰 镍 硅 铬 钼 工作前 工作后 A 0.81 0.36 0.27 0.40 3.97 0.51 0.8 0.729 83-85 B 0.82 0.32 C 0.83 0.55 D 0.87 0.47                     图2.工作轴剥落。 （A）轴剥落A和  （B）轴剥落D. 典型的剥落面积大小已剥落面积为1430毫米的长度，周长353毫米和85毫米深度的最大的轧轴A.测量。轧轴过早失效后，4.515公里的连轧服务就是比轧轴四轴材料的微观结构工龄进行了检查，光学显微镜，如图3所示。由此可以看出，有一个深度为75毫米硬化区的工作轴，因此所采取的微观结构的区域与中心的工作轴A.图是从轧轴表面的距离。 3（a）是一个区接近表面，（b）约在深度75毫米从表面上看，和（c）从表面深度约85毫米。可以看出，晶粒尺寸从11.5至20米不等。更重要的是，粗粮底下发现轧轴表面，这是保证最低硬化深度为85毫米少75毫米。 图3.工作轴材料的微观结构。 （a）地区靠近面，（b）约75毫米的表面深度（c）表面深度约85毫米。 图4.打击轴A. 斯特朗试验机上进行拉伸试验与平板标本。对样品进行了削减从??大剥落件从英斯特朗试验机轴A.结果表明，抗拉强度和屈服强度低于制造商的要求。图4显示了裂纹工作轴A.正常工作轴的压力和剪切应力，分别由赫兹分析计算。计算的正应力和剪应力[17]开发与带钢接触的结果显示在图5和图6中可以看出。图5讲的一些组件（SXX =σR）和（SZZ =σZ，）达成一项在表面的大值。 两轴A和D是新轴。穿的工作轴或支承轴后面的个人资料可能不实际的因素，促进轧轴损坏。然而，在领先的边缘或由于折叠带钢的冷轧厚度增加一倍局部高负荷可能超过轧轴表面的剪切强度。这是有可能形成一个或多个压力裂缝，在靠近表面的地方超载领域。裂缝轴轴的方向平行，但在一个非径向方向传播（图2（b））。由于轧机扭转滚动功能，裂缝可能会逐步传播（图4）。因内部不当的微观结构（图3（b）），内的工作轴表面裂纹扩展开发。因此，发生大的表面剥落。这样可以减少工作轴使用寿命显着（见图7，热轧带钢轧轴公里长度很短，工作轴前被损坏）。 图5.正常讲开发与热轧带钢接触的结果 图6.剪应力与热轧带钢接触的结果 图7.前滚失败和表面粗糙度的冷轧带钢的长度之间的关系 3.3.地带的焊接 图8显示了轧制，轧机的第二站，第三遍后，将工作轴B轧轴表面上的金属焊接。坐落在热轧带钢的边缘，损害和它的面积约650毫米，宽度和周长707毫米。不正确的轴形或条状不佳，可能会导致在具体的轧制压力，这反过来又导致当地高轴表面温度。因此增加缩进形式的轧轴表面的塑性变形，甚至剥落，是造成这些超载严重的热开发的地方增加了炽裂或瘀伤。 取出后由于去除轧轴表面焊接绑扎部分，工作轴可连续使用。然而，工作轴的磨损是这种情况下，具有重要意义，如图所示。与其他案件相比，7轴表面粗糙度降低显着（见轴B）。 B轴的使用寿命无明显影响，由于其连续使用。 3.4.带状 重去皮明亮的区域出现的形式与一个非常粗糙的表面圆周方向上工作轴?面向，如图9所示。删除层厚度约0.1毫米和0.9毫米之间。它被广泛接受，带是典型的表面损伤，高铬钢工作轴时，他们使用更长的运行时间后，在相同的关键立场和位置。然而，案件发生在第一遍后运动时间短滚动轴?。 带起源发生交替交替热负荷超过疲劳的表面材料的剪切强度时，组合中的摩擦力。据推测，表面裂缝内主要炽裂发展和传播剪从轴，直到炽裂地区的深度。当轧轴表面局部恶化，峰值剪切力是诱导和领导到周围轴筒去皮带的发展速度非常快，导致轧轴磨损。 图8.剥离工作轴的焊接 图9.带工作轴 图9展出的情况轴使用寿命上有重大影响力和轧轴磨损，这表明，轧轴表面粗糙度的降低在短期公里冷轧带钢长度显着（见图7，轴C）。因此，这一缺陷显着提高了轧轴磨损。 4.结论 本文3种在冷轧厂工作轴表面缺陷进行了调查。它的结论是讲一些组件达到在表面的大值，这可能会导致工作轴裂纹，降低使用寿命的结果。在此期间，冶金缺陷，如不当编写的微观结构，提高轧轴表面剥落材料的风险。地带焊接轧机操作不正确造成的。提高工作轴温度控制和喂养条状，可避免此类事件。捆扎是第三次在这项研究中遇到的轧轴表面损伤。据认为，更好的轧轴冷却与润滑，可减少损坏的风险，并提高工作轴使用寿命。 致谢 第一作者想感谢Wollongong大学大学研究生奖（UPA）的当前工作的支持。笔者也想感谢T. Silver博士的协助下，完成了这篇文章。 参考文献 [1] P. Montmitonnet, E. Massoni, M. Vacance, G. Sola, P. Gratacos, Modelling for geometrical control in cold and hot rolling, Ironmaking Steelmaking 20 (1993) 254–260. [2] J. Shi, D.L.S. McElwainand, T.A.M. Langlands, A comparison of methods to estimate the roll torque in thin strip rolling, Int. J. Mech. Sci. 43 (2001) 611–630. [3] E.N. Dvorkin, M.A. Cavaliere, M.B. Goldschmit, Finite element models in the steel industry. Part I: Simulation of flat product manufacturing processes, Comput. Struct. 81 (2003) 559–573. [4] Z.Y. Jiang, A.K. Tieu, X.M. Zhang, C. Lu, W.H. Sun, Finite element simulation of cold rolling of thin strip, J. Mater. Proc. Technol. 140 (2003) 542–547. [5] R. Col′.rez, I. Sandoval, J.C. Morales, L.A. Leduc, Damage in as, J. Ram′hot rolling work rolls, Wear 230 (1999) 56–60. [6] S. Iwadoh, H. Kuwamoto, S. Sonoda, Investigation about the mechanism of work roll wear at the cold rolling, J. Iron Steel Inst. 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Analysis of premature failure of work rolls in a cold strip plant Hongchun Li, Zhengyi Jiang, Kiet , Tieu , Weihua Sun School of Mechanical, Materials and Mechatronic 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, premature 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 calculated, 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 factors 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 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 achieve 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 surface roughness, etc., on the wear of work roll [6–14] 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 cyclic 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 friction [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 operating 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 transformations [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 spalled 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 affected 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 schematically 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 1.5–5.0 mm in thickness, 900–1680 mm in width and 35 tonnes in weight. The oxide scale on the hot strip was removed by pickling before rolling. The maximum pickling speed is 60 m/min and the temperature of acid bath is about 70–85 .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 680-2-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 sampling 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, banding 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 on 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 Stand Diameter (mm) Rolled strip (mm) Reduction (%) Roll separating force (kN) Rolling speed (m/min) Rolled length (km) A 1449 1.35×1240 34 19,890 867 4.515 B 2448 0.85×1500 35 19,932 960 13.64 C 1449 1.1×1240 28.5 17,652 498 5.139 D 2449 0.61×1240 28.2 17,528 679 11.304               Table 2 Work roll parameters   Roll Chemical composition (wt%) Roughness (μm) Hardness (HSC) C Mn Ni Si Cr Mo Before working After working A 0.81 0.36 0.27 0.40 3.97 0.51 0.8 0.729 83-85 B 0.82 0.32 C 0.83 0.55 D 0.87 0.47                     Fig. 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 spalled 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 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, 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. (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 the roll A. Results obtained from the Instron testing machine indicate that the tensile and yield strengths are below the manufacturer’s 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 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 = σr) and (szz = σz) reach a large value at the surface. Both rolls A and D are new rolls. Worn profile of either the work 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 of 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 propagation 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).