双辊铸轧机金属熔池液位的优化控制

发布时间：2018-03-09 08:05

本文选题：双辊铸轧　切入点：金属熔池液位控制　出处：《辽宁科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：双辊铸轧是一种先进的金属薄板生产工艺,其特点是在生产过程中金属结晶的同时,完成金属的轧制和塑形,这与传统的热轧工艺相比极大的简化了生产过程,降低了生产所需投资和能耗,同时提高了产品质量,也使双辊铸轧技术在金属成品制造领域中得到了广泛的应用。双辊铸轧技术生产的金属薄板质量与金属的凝固点位置有密切的关系,生产过程中要求凝固点始终在铸轧辊辊缝上方较近处形成,而金属熔池液位对凝固点的形成产生直接影响。由于在双辊铸轧技术生产金属薄板的过程中,熔融金属凝固的速度极快,所以难以实现对辊速、辊缝、塞棒高度等相关工艺参数的人工检测和控制,同时熔池液位控制的工艺参数间存在着强耦合关系,这些因素使控制过程产生了很强的非线性、滞后性和时变性特征。针对液位控制过程的局限性,本文提出采用以模糊数学和控制理论为基础的模糊控制方法对其实现自动化控制。但由于传统模糊控制控制参数的确定极大地依赖于专家经验,这使得控制过程具有了主观性和不确定性。针对模糊控制存在的问题,本文进一步提出了基于具有极强全局寻优能力的遗传算法对模糊控制参数进行同步优化,优化对象包括:隶属度函数参数、控制规则库参数和模糊因子。同时,由于遗传算法本身存在“早熟”现象,所以在算法设计过程中采用自适应策略修正遗传算子,避免了遗传算法自身存在的问题。本文首先对双辊铸轧工艺原理进行了介绍,并分析了熔池液位控制的意义,简述了液位控制的发展;在此基础上,明确熔池液位基本结构,完成其数学模型的推导,同时分析了各工艺参数对熔池液位的影响;然后对模糊控制技术进行了研究,探讨其优点和局限性,结合实际液位控制情况确定传统模糊控制参数;最后详细介绍了遗传算法的基本流程,选择实数编码方法进行编码染色体,并完成个体适应度函数和遗传算子的设计,同时实现了遗传算子自适应修正功能。通过MATLAB软件仿真可证明,与传统的模糊控制相比,基于自适应遗传算法改进的模糊控制控制方法,其动态性能有明显提高,在对双辊铸轧机金属熔池进行控制具有了更高的精确性和稳定性。
[Abstract]:Twin roll casting rolling is an advanced production process of sheet metal, which is characterized by the completion of metal rolling and shaping while the metal is crystallized in the production process, which greatly simplifies the production process compared with the traditional hot rolling process. It reduces the investment and energy consumption required for production and improves the quality of the product. The technology of two-roll casting and rolling has been widely used in the field of metal product manufacture. The quality of metal sheet produced by double-roll casting and rolling technology is closely related to the freezing point of metal. In the process of production, the freezing point should always be formed near the top of the roll gap, and the liquid level of the molten pool has a direct effect on the formation of the freezing point. The solidification speed of molten metal is very fast, so it is difficult to realize the manual detection and control of the relative technological parameters such as roll speed, roll gap, plug rod height and so on. At the same time, there is a strong coupling relationship among the process parameters of molten pool level control. These factors lead to very strong nonlinear, lag and time-varying characteristics of the control process. In this paper, a fuzzy control method based on fuzzy mathematics and control theory is proposed to realize automatic control. However, the determination of traditional fuzzy control parameters depends heavily on expert experience. This makes the control process subjective and uncertain. Aiming at the existing problems of fuzzy control, this paper proposes a genetic algorithm based on strong global optimization ability to synchronously optimize the fuzzy control parameters. The optimization objects include membership function parameter, control rule base parameter and fuzzy factor. At the same time, because genetic algorithm itself has "premature" phenomenon, adaptive strategy is used to modify genetic operator in the process of algorithm design. In this paper, the principle of twin-roll casting rolling process is introduced, and the significance of molten pool level control is analyzed, and the development of liquid level control is briefly described, based on which, the basic structure of molten pool level is clarified. At the same time, the influence of each process parameter on the molten pool level is analyzed, and then the fuzzy control technology is studied, its advantages and limitations are discussed, and the traditional fuzzy control parameters are determined in combination with the actual liquid level control. At last, the basic flow of genetic algorithm is introduced in detail. The real coding method is chosen to code chromosome, and the individual fitness function and genetic operator are designed. At the same time, the adaptive modification function of genetic operator is realized. The simulation of MATLAB software shows that compared with the traditional fuzzy control, the dynamic performance of the improved fuzzy control method based on adaptive genetic algorithm is obviously improved. It has higher accuracy and stability in controlling the molten pool of two-roll casting mill.
【学位授予单位】：辽宁科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG334.9

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