【作者】 章健；

【导师】 彭艳；

【作者基本信息】 燕山大学 ， 机械设计及理论， 2011， 博士

【摘要】 热轧板带作为高技术含量的钢铁产品，其产量和性能反映了一个国家的钢铁工业水平。在生产过程中，提高轧制线设备的稳定性是保证板带产品质量的重要条件。但是，由于各种因素的影响，热轧生产设备在工作时经常发生失效破坏，进而对产品的质量和生产效率造成影响，因此对于易损部件进行失效机理分析并提出相应优化措施成为当前板带钢生产研究的热点之一。扇形板是热轧卷取机卷筒的关键部件，在使用过程中经常会发生磨损失效和裂纹失效。本文以扇形板的失效机理为研究对象，通过分析其工作过程中的磨损机制和裂纹机制，建立起磨损计算模型和寿命预测模型，提出裂纹失稳扩展的判定条件，并得到外部载荷、结构形状等对扇形板破坏形式及破坏程度的影响规律，在此基础上给出减轻磨损程度及控制裂纹扩展的优化措施，为最终延长扇形板的使用寿命、提高卷取机的工作稳定性提供了理论依据和实际参考。本文建立了扇形板的动力学有限元模型，模拟工作过程中的径向压力，与现有多种计算模型进行对比，确定了周国盈公式在热轧卷取条件下的适用性，为进行深入的受力分析奠定基础。建立扇形板热力耦合模型，模拟卷取中各阶段的温度场、应力场及变形分布规律，得到温度分布不均、变形不均及应力集中的具体形式，为其强度校核及失效分析划定了研究范围并提供了计算依据。建立起扇形板磨损计算模型和寿命预测模型，并采用实验的方法模拟失效部位特定工作条件下的摩擦磨损行为，通过磨损后试件的观察及测量，判断出卷取过程中的磨损机制和外载条件对磨损机制转化所产生的影响。另外，改变模拟过程中的参数设定，对材料的耐磨性进行研究，得到其磨损性能受法向压力、环境温度、滑动速度等因素的影响规律，为合理设定卷取工艺及冷却工艺提供了理论指导。研究扇形板裂纹的萌生与扩展机理，通过断口分析判断出失效裂纹的性质及断裂机制，考虑材料性能、结构形状、使用环境等因素的影响，计算出材料的断裂韧性和裂纹尖端应力场强度，提出扇形板裂纹失稳扩展的判定条件，得到引起裂纹失效的主要原因，其结论可作为卷取工艺改进及结构优化的设计依据。在失效机理分析的基础上进行延寿优化研究，以控制扇形板易损部位的变形不均及应力集中为目标提出改进措施，主要分结构和冷却两方面，其中，结构改进涉及到变形余量及部件自由度的调整，而冷却工艺则主要针对应力场分布的均匀化程度实施最优时间的比例分配，模拟及工业验证结果显示，优化措施在降低磨损程度、抑制局部裂纹的产生和扩张方面可以取得良好的效果，最终达到延长扇形板使用寿命的目的。总体而言，本文进行的热轧卷取机扇形板失效机理分析及延寿优化，考虑了卷取工艺制度、材料性能、制造工艺及结构形状等多方面因素的影响，对有效延长扇形板的使用寿命，提高热轧厂钢卷产品质量及生产效率等具有一定的理论价值和实际参考意义。更多还原

【Abstract】 As a high-tech steel products, the output and property of hot rolled strip reflect thelevel of iron and steel industry of a country. In the process of production, improve thestabilization of device of rolling line is an important condition of safeguard on productquality. But due to various factors, devices of hot rolling line often occurs failure damage,come to have an affect on product quality and production efficiency. Therefore, carry outfailure mechanics analysis on part which tends to be destroyed and put forwardcorresponding optimization measures is one of the hot research on production of strip atpresent.Segment is one of key components of hot rolling coiler, wear failures and crackfailures usually happen in working process. This paper takes the failure mechanics ofsegment as research object, analyze the wear mechanism and crack mechanism of parts,put forward the judging criterion of wear failure and crack extend out of control, establishwear loss model and life prediction model, intensive research influencing regularities ofexternal conditions and internal structure on strength character of materials. On that basis,put forward optimization measures of relief wear and fracture-arrest, in the end providetheoretical foundation and practical reference for extend the working life of segment andimprove the working stabilization of hot rolling coiler.Establish dynamics finite element model, simulate the radial pressure of segment inworking process, corresponding with many existing calculation model, in the enddetermined the applicability of ZHOU Guo-ying formula on radial pressure calculation ofhot rolling coiler, lay a foundation intensive force analysis.Establish thermal–mechanical coupling model, simulate the regulation oftemperature field, stress field and deformation distribution in each phase, gets theconcrete form of temperature uneven distribution, deformation uneven distribution andstress concentration, demarcate research range and provide computation basis for strengthcheck and failure analysis.Put forward wear failure judging criterion, establish wear calculation model and life prediction model, simulates fiction and wear behavior under special working condition byexperimental, through observe and measure to worn specimen, judge out the wearmechanism in coiling process and the influence of external loading conditions to wearmechanism transformation. Furthermore, change the parameters setting in experimental,research the wear resistance of materials, gets the influence regularity of normal load,ambient temperature and sliding speed to wear performance, provide theoretical guidancefor setting coiling process and cooling process reasonable.Research the generation and extending mechanism of crack, judge out the propertyof failure crack and fracture mechanism through fracture analysis. Consider the influenceof material properties, structural shape and application environment, calculate the fracturetoughness and stress field intensity of crack tip, put forward the judging criterion of crackextending out of control, get the reason of crack failure, the conclusion can used as designbasis of process improvement and structure optimization.Perform optimization on extending working life on the basis of failure mechanics,provide optimization measures take controlling the deformation uneven distribution andstress concentration as the goal. Divided into two groups of structure and cooling process,which structure optimization include adjustment of distortion allowance and degree offreedom, and the cooling process optimization mainly distribute time to homogenizing thestress distribution. The results of simulation and industrial verification show that theoptimizations can get favorable effects on relief the level of wear loss, inhibit thegeneration and extending of crack, in the end attain the expected purpose of extendingworking life.On the whole, the research on failure mechanics and extending working lifeoptimization of segment of hot rolling coiler, consider the influence of many factors suchas coiling process institution, material properties, manufacturing process and structuralshape, having a certain theoretical value and practical reference significance on extendingworking life of segment, improve the product quality and production efficiency in hotrolling mill.更多还原