二辊铝板带热轧机轧辊热效应研究及凸度自动控制系统开发

发布时间：2018-03-24 20:32

本文选题：板带凸度　切入点：分段冷却　出处：《北京科技大学》2016年博士论文

【摘要】：热轧铝板带的凸度是影响热轧产品质量的关键因素,而在对其进行理论研究与控制的过程中,轧辊热效应是必须要考虑的因素。现有的热轧板带凸度控制装置对轧机的基础设备要求较高,且设备投入大,适用于先进的铝板带热轧机,但即使热轧机配有多种先进的板形控制手段,也未能实现铝板带凸度的精确控制。此外,国内热轧铝板带企业多为中小型企业,生产条件和轧机设备相对落后。因此,寻求简单、经济、高精度的热轧铝板带凸度控制方法是十分必要的。本文在理论和实验研究的基础上,提出一种间接式热轧铝板带凸度自动检测和控制系统,并应用于二辊铝板带热轧机上,实现了板带凸度的检测与控制。其主要研究内容如下：(1)基于湍流射流理论,建立轧辊与冷却液间流-热耦合模型,在模型仿真分析的基础上,优化轧机冷却系统的结构参数,提高其冷却性能。并在此基础上,开发该轧机的分段冷却系统,包括先导型常闭电磁阀的设计以及分段冷却系统的结构设计。最后通过针对性的现场实验对该冷却系统的冷却能力进行验证。(2)对轧辊热效应进行深入研究。利用有限元方法建立轧辊三维温度场模型,分析轧制过程和轧制间歇期内轧辊热效应的变化规律,以及冷却液流量、轧制速度、冷却液分布等因素的影响。在板带与轧辊之间接触换热系数的计算中考虑了板带变形热和摩擦热,基于有限元方法计算相应轧制条件下二辊铝板带热轧机轧辊与冷却液间的对流换热系数,计算过程中轧辊温度和板带温度均为在线实测值,最终得到更为精确的轧辊热效应分析结果。(3)利用红外传感器的测温原理,考虑热轧铝板带生产过程中冷却液以及轧辊表面氧化铝等外界因素对温度测量结果的影响,研发了轧辊温度在线测量系统和热轧铝板带温度在线测量系统,包括机械结构和控制系统的设计,实现轧制过程中轧辊和板带温度的在线检测。(4)基于人工神经网络理论,并在轧辊测温系统研发成功的基础上,提出热轧铝板带凸度的间接检测方法。综合考虑预测模型的收敛速度和预测精度,建立自适应PSO-BP神经网络模型,并利用实际轧制过程中的轧制参数训练该网络模型,从而得到热轧铝板带凸度预测模型,最终实现根据轧辊温度及相关轧制参数间接检测板带凸度的目的。(5)基于模糊控制理论,研发轧辊分段冷却闭环模糊控制系统,该系统以轧辊温度预设定模型为目标,以轧辊测温系统为反馈环节,分段冷却系统为执行机构。在此基础上,结合热轧铝板带凸度影响因素的理论分析,提出了热轧铝板带凸度的间接控制方法,并将其应用于实际的热轧生产中,通过针对性的现场实验验证了控制方法的有效性。
[Abstract]:The crown of hot rolled aluminum strip is the key factor to affect the quality of hot rolled products, and in the process of theoretical research and control, The hot effect of roll is the factor that must be considered. The existing hot strip crown control device requires high basic equipment of rolling mill, and it is suitable for advanced aluminum strip hot rolling mill. But even if hot rolling mill is equipped with many advanced flatness control methods, it can not realize the accurate control of aluminum strip crown. In addition, domestic hot rolling aluminum strip enterprises are mostly small and medium-sized enterprises, and the production conditions and rolling equipment are relatively backward. It is necessary to seek a simple, economical and high precision control method for the crown of hot rolled aluminum sheet and strip. Based on the theoretical and experimental research, an automatic detecting and controlling system for the crown of aluminum strip in indirect hot rolling is proposed in this paper. The main research contents are as follows: 1) based on the turbulent jet theory, the fluid-heat coupling model between roll and coolant is established, and based on the simulation analysis of the model, the flow and heat coupling model between roll and coolant is established. The structural parameters of the cooling system of the rolling mill are optimized to improve its cooling performance. On this basis, the segmented cooling system of the mill is developed. It includes the design of pilot type normally closed solenoid valve and the structural design of segmented cooling system. Finally, the cooling capacity of the cooling system is verified by field experiments. Three dimensional temperature field model of roll is established by finite element method. The variation law of roll thermal effect during rolling interval and cooling fluid flow rate and rolling speed are analyzed. In the calculation of contact heat transfer coefficient between strip and roll, deformation heat and friction heat of plate and strip are considered. Based on the finite element method, the convection heat transfer coefficient between the roll and the coolant of the two-roll aluminum strip hot rolling mill is calculated under the corresponding rolling conditions. The roll temperature and the strip temperature are measured on line in the process of calculation. Finally, a more accurate analysis result of roll thermal effect is obtained. The temperature measurement principle of infrared sensor is used to consider the influence of cooling fluid and aluminum oxide on the temperature measurement results in the process of hot rolling aluminum strip production. The on-line measuring system of roll temperature and the on-line temperature measurement system of hot rolled aluminum sheet and strip, including the design of mechanical structure and control system, are developed to realize the on-line measurement of roll and strip temperature in rolling process based on artificial neural network theory. On the basis of the research and development of roll temperature measuring system, an indirect testing method for the crown of hot rolled aluminum strip is proposed. Considering the convergence speed and precision of the prediction model, an adaptive PSO-BP neural network model is established. The neural network model is trained by the rolling parameters in the actual rolling process, and the prediction model of the crown of hot rolled aluminum sheet and strip is obtained. Finally, the goal of indirectly detecting the strip crown according to the roll temperature and the relative rolling parameters is realized based on the fuzzy control theory. The closed loop fuzzy control system for roll subsection cooling is developed. The system takes the roll temperature pre-setting model as the target, the roll temperature measurement system as the feedback link and the piecewise cooling system as the executing mechanism. Based on the theoretical analysis of the factors affecting the crown of hot rolled aluminum sheet and strip, the indirect control method of the crown of hot rolled aluminum sheet and strip is put forward, and it is applied to the actual hot rolling production. The effectiveness of the control method is verified by the targeted field experiments.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG334.9

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