
热轧带钢精轧机工作辊热变形行为的研究.pdf
82页上海交通大学硕士学位论文 第 I 页 热轧带钢精轧机工作辊热变形行为的研究热轧带钢精轧机工作辊热变形行为的研究 摘摘 要要 随着汽车、轻工、家电和电气制造等行业对板形质量要求的不断提高,板形已成为热连轧带钢生产中至关重要的一个质量问题带钢板形质量的好坏主要与轧制过程中有载辊缝有关,因此通过控制有载辊缝可以使带钢达到良好的几何精度控制有载辊缝不仅需要知道轧制力作用下轧辊受力变形后辊缝中点的开度,而且需要知道辊缝沿板宽方向的分布情况,这涉及到轧辊的许多方面工作辊的热变形、工作辊的磨损以及工作辊的弯曲变形是决定有载辊缝的三个主要因素,其中热变形对辊缝的影响十分显著热轧过程中,轧辊中部的热膨胀不仅可以带来超过300μm 的热凸度,而且轧辊的热变形在整个生产过程中不断变化,造成了生产过程的不稳定加之其边界条件的复杂性,很难建立适应各种条件的通用模型,所以工作辊的热变形计算很难达到令人满意的精度,准确预报轧辊热变形已成为热轧板形控制技术中的难点因此对其展开研究,建立符合实际情况的热变形计算模型,不仅具有理论意义,更具有实用价值 本文结合宝钢 1880mm 热轧带钢生产实际,根据传热学理论,在全面分析轧辊热量传递的基础上,确定了轧辊内热传导系数、空气对流传热系数、冷却水对流传热系数以及输入轧辊的热量计算方程式。
从能量守恒定律和热传导方程出发, 利用通用有限元软件 ANSYS 建立了两种轧辊二维非稳态温度场的计算模型,包括轧辊中心横截面内温度场模型和上海交通大学硕士学位论文 第 II 页 轴对称平面温度场模型,并给出了轧辊热凸度模拟计算流程图针对热轧过程复杂、边界条件难以确定的难题,深入宝钢 1880mm 热轧生产现场进行了大量的测量与试验,主要是工作辊下机后表面温度和热辊形的跟踪测量然后根据采集的工艺参数,利用建立的计算模型进行了仿真分析,并与现场的实测辊温和辊形数据进行比较,优化了模型边界条件的相关参数,使建立的计算模型满足现场的实际使用要求 利用建立的计算模型对轧制过程中的温度场和热变形过程进行了模拟计算,研究了轧制过程中轧辊表面和内部温度场的变化情况,以及一个单位轧制计划内轧辊总的热凸度和部分热凸度变化规律并分析了轧辊材质、带钢宽度、轧制节奏、轧辊转速、冷却系统等参数与热变形之间的关系及其对带钢板形的影响,得出了有价值的结论,为进一步改进板形控制数学模型,提高板形精度提供了理论依据 关键词:关键词:热轧,温度场,热凸度,有限元,板形 上海交通大学硕士学位论文 第 III 页 RESEARCH ON THERMAL DEFORMATION BEHAVIOR OF WORK ROLL IN FINISHING TRAINS OF HOT STRIP MILL ABSTRACT Along with automobile, the light industrial professions, home appliance and electrical production the unceasing raising that asked for board shape quality, shape of strip has become a most important quality problem in the production of hot strip rolling. Strip shape is mainly connected with the loaded roll gap in the strip production, so it can get strip with high geometry precision by controlling the roll gap. Roll gap control needs to know not only how much the center of roll gap changes under rolling pressure, but also the distribution of roll gap along the width of strip, it involves many factors. The thermal deformation, wear and elastic deformation of roll are the main three factors affecting the loaded roll gap control model. Among these, the thermal deformation of work roll plays significant role on the roll gap, the thermal expansion of roll in the middle plane may be better than 300μm, and the thermal deformation is changed continually in the whole rolling process, which causes the instability in production. And due to the complexity of its boundary condition, it is a difficulty for strip shape control technology to predict the roll thermal deformation well and truly during hot rolling. Therefore, the research on building a model for calculating thermal deformation has the important value of the theory and practice. According to heat transfer theory, associated with the practical practice of 1880mm hot rolling mill in Baosteel, and based on overall analysis to the roll heat transfer, mathematical equations of the coefficient of heat conduction in the roll, the coefficient of heat transfer of air and cooling water, quantity of heat inputting the roll had been deduced. Originated from the energy conservation law and equations of heat conduction, two roll two-dimension 上海交通大学硕士学位论文 第 IV 页 unsteady state’s temperature fields had been established, including temperature field model of middle plane of roll and axial symmetry of roll. And the flow chart for calculating the thermal crown of roll was drawn. Aimed at the complexity of rolling and boundary condition, a series of experiments and tests were carried out on the spot of 1880mm hot rolling mill in Baosteel, including the measurement of surface temperature and thermal profile of work roll after stop rolling. Based on the rolling technological parameters, the temperature field and thermal deformation of work roll were calculated. And the measured data on spot were utilized to test the model to ensure the model’s validity and feasibility. After using the model to simulate the temperature field and thermal deformation in hot rolling process, analyzed the transformation trend of the temperature at roll surface and center, and studied the development trend of total thermal crown and partial thermal crown in a rolling unit. Furthermore, the effect of roll material, width of strip, rolling rhythm, roll velocity, cooling water system parameters on transformation trend of work roll thermal profile were studied. This paper has provided improving the mathematical model of strip shape control and increasing accuracy of strip shape. Keywords: hot strip rolling, work roll, temperature field, thermal crown, finite element method, strip shape 上海交通大学上海交通大学 学位论文原创性声明学位论文原创性声明 本人郑重声明:所呈交的学位论文,是本人在导师的指导下,独立进行研究工作所取得的成果。
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