[硕士论文] 热轧带钢精轧机工作辊热变形行为的研究 [复制链接]

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硕士论文-热轧带钢精轧机工作辊热变形行为的研究，共87页

摘 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

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：热轧，温度场，热凸度，有限元，板形

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

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

目 录

摘 要

ABSTRACT

第一章 绪论...... 1

1.1 热轧带钢板形描述 ....... 1

1.2 工作辊热辊形的概念 ... 1

1.3 轧辊热变形行为在板形控制中的地位......... 2

1.4 国内外热变形的研究现状 ...... 4

1.4.1 解析法......... 4

1.4.2 有限差分法. 6

1.4.3 有限元法.... 10

1.4.4 实验方法.... 12

1.5 课题的研究意义和目的 ........ 12

1.6 主要研究内容 .. 13

第二章 热轧工作辊热变形研究的理论基础..... 15

2.1 传热学的基本定律 ..... 15

1.2.1 傅立叶(J.B. Fourier)定律.......... 15

1.2.2 热传导导热定律.. 16

1.2.3 对流传热的牛顿定律..... 17

2.2 工作辊有限元热分析理论 .... 17

2.3 工作辊热变形的计算理论 .... 22

2.4 本章小结 .......... 24

第三章 热轧工作辊温度场和热变形的有限元模型 .... 25

3.1 热轧工作辊温度场模型的简化 ....... 25

3.2 有限元模型的建立 ..... 26

3.2.1 工作辊中心横截面内温度场模型 ....... 26

3.2.2 轴对称平面温度场模型. 27

3.2.3 工作辊热凸度的计算流程......... 28

3.3 边界条件 .......... 29

3.3.1 工作辊与带钢的接触传热(AB 区域) .. 30

3.3.2 带钢与空气的对流换热(EF、GH 区域)........ 32

3.3.3 挡水板积水的换热(CD、IJ 区域)....... 32

3.3.4 冷却水的强制对流(DE、HI 区域)...... 33

3.3.5 工作辊与支撑辊间的传热(FG 区域) ... 36

3.4 本章小结 .......... 37

第四章 热轧工作辊温度场和热变形的仿真与实验分析 ....... 38

4.1 宝钢 1880MM 热轧精轧机组的模型参数 ... 38

4.1.1 轧制工艺参数...... 39

4.1.2 工作辊物性参数和几何尺寸.... 39

4.2 模型边界条件的优化 . 40

4.3 现场测试方案 .. 41

4.4 工作辊温度场的仿真计算 .... 42