高精度冷连轧厚度控制策略的研究与应用

发布时间：2018-08-20 18:25

【摘要】：厚度精度是冷连轧带钢最主要的尺寸精度之一,厚度自动控制一直是冷连轧生产中不可缺少的组成部分。本文以某薄板科技有限公司1450mm五机架冷连轧机建设项目为背景,通过对模型设定系统、液压执行机构控制系统、机架间张力控制系统和厚度自动控制系统等进行研究,建立了一套综合的冷连轧厚度控制策略,并将其应用于生产实际,且取得了良好的效果。主要研究内容如下：(1)依据冷连轧工艺特点,研究了可在线工程应用的数学模型。为了保证模型设定的精度以及解决传统方法难以求解的问题,采用了简易有限元法对轧制参数进行计算。为了提高辊缝预设定的精度,采用了一种新型的冷连轧机弹跳模型。综合考虑了冷连轧过程中的重要因素,开发了一种基于成本函数的多目标轧制规程优化模型。(2)研究了液压执行机构和机架间张力的控制系统。对液压压上系统的位置控制模式、轧制力控制模式和单侧控制模式进行了分析,并对液压弯辊系统和液压轧辊横移系统的控制策略进行了深入分析。针对伺服非线性和伺服零偏等特性,开发了相应的补偿控制策略。提出了基于动态张力阈值的机架间张力控制策略,分别对正常张力控制闭环和极限张力控制闭环进行了深入研究。(3)结合轧机的仪表配置,设计并建立了五机架冷连轧厚度自动控制系统。通过在第1和第2机架设置多种类型的AGC,将大部分尖峰性的厚度偏差在前部机架消除。在末机架采用多种AGC控制策略,针对不同的轧制策略保证了成品厚度精度。开发了末机架轧制力补偿控制,在优化了厚度和张力控制方式的基础上保证了末机架轧制力的控制精度。提出了动态负荷平衡控制,防止了某个机架的负荷过大。开发了速度修正控制以保障AGC对机架速度的调节过程得到高效合理的执行。(4)为了提高监控AGC系统的性能,将改进型Smith预估补偿控制和辅助反馈迭代学习控制引入了监控AGC系统。建立了监控AGC内环系统的理论模型。为了解决由于控制器单一性造成的常规Smith预估监控AGC系统响应速度和调节精度不佳的问题,提出了Smith预估补偿控制的改进型策略。在此基础上设计了基于辅助反馈迭代学习控制的改进型Smith预估监控AGC系统,有效地弥补了Smith预估监控AGC系统性能过度依赖模型精度的缺点。通过仿真实验对以上三种监控AGC系统的控制效果进行分析。(5)采用现场实际曲线分析了液压压上系统和机架间张力控制系统的控制效果,并对典型厚度规格带钢和极薄规格镀锡卷的厚度控制效果进行了分析,对该厚度控制策略的效果作了有说服力的评价。本文的研究结果针对冷连轧过程的厚度控制,具有较强的实用性。目前,已将该厚度控制策略成功应用于某薄板科技有限公司1450mm五机架冷连轧机,对开发我国具有自主知识产权的冷连轧厚度控制系统具有重要意义。
[Abstract]:Thickness accuracy is one of the most important dimensional accuracy of cold continuous strip rolling, and automatic thickness control is always an indispensable part in cold tandem rolling production. In this paper, based on the construction project of 1450mm five-stand cold tandem mill in a thin sheet Science and Technology Co., Ltd., the model setting system, hydraulic actuator control system, inter-stand tension control system and thickness automatic control system are studied. A comprehensive control strategy for the thickness of cold continuous rolling is established and applied to the production practice, and good results are obtained. The main contents are as follows: (1) according to the characteristics of cold continuous rolling process, the mathematical model of on-line engineering application is studied. In order to ensure the precision of model setting and solve the problem that the traditional method is difficult to solve, a simple finite element method is used to calculate the rolling parameters. In order to improve the precision of roll gap pre-setting, a new spring model of cold tandem mill is adopted. An optimization model of multi-objective rolling schedule based on cost function is developed by considering the important factors in the process of cold continuous rolling. (2) the control system of tension between hydraulic actuator and stand is studied. The position control mode, rolling force control mode and single side control mode of hydraulic pressing system are analyzed, and the control strategies of hydraulic bending roll system and hydraulic roll transverse movement system are deeply analyzed. Aiming at the characteristics of servo nonlinearity and servo zero offset, the corresponding compensation control strategy is developed. Based on the dynamic tension threshold, the inter-stand tension control strategy is proposed, and the normal tension control closed-loop and the limit tension control closed-loop are studied respectively. (3) combined with the instrumentation configuration of the rolling mill, The automatic thickness control system of five stand cold continuous rolling mill is designed and established. By setting various types of AGCs in the first and second stands, the thickness deviation of most of the spikes is eliminated in the front frame. Various AGC control strategies are used in the final stand and the thickness accuracy of the finished product is ensured according to different rolling strategies. The rolling force compensation control of the end stand is developed and the control precision of the rolling force is ensured on the basis of optimizing the thickness and tension control mode. A dynamic load balancing control is proposed to prevent the overloading of a frame. In order to improve the performance of AGC system, the modified Smith predictive compensation control and auxiliary feedback iterative learning control are introduced into the monitoring AGC system to ensure the efficient and reasonable execution of the speed adjustment process of the frame by using the speed correction control. (4) in order to improve the performance of the monitoring AGC system, the improved Smith predictive compensation control and the auxiliary feedback iterative learning control are introduced into the monitoring AGC system. The theoretical model of monitoring AGC inner loop system is established. In order to solve the problem of poor response speed and adjustment precision of conventional Smith predictive monitoring AGC system caused by the singularity of controller, an improved strategy of Smith predictive compensation control is proposed. Based on this, an improved Smith predictive monitoring AGC system based on auxiliary feedback iterative learning control is designed, which effectively makes up for the shortcoming that the performance of Smith predictive monitoring AGC system depends on the model accuracy. Through the simulation experiment, the control effect of the three kinds of monitoring AGC system is analyzed. (5) the control effect of hydraulic pressure control system and frame tension control system is analyzed by using the field actual curve. The thickness control effect of typical thickness gauge strip steel and extremely thin tinning coil is analyzed, and the effect of the thickness control strategy is evaluated persuasively. The research results of this paper have strong practicability for the thickness control of cold continuous rolling process. At present, the thickness control strategy has been successfully applied to the 1450mm five-stand tandem cold rolling mill in a thin sheet Science and Technology Co., Ltd., which is of great significance to the development of the thickness control system with independent intellectual property rights in China.
【学位授予单位】：东北大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TG334.9

【相似文献】