【作者】 杜平；

【导师】 刘相华； 胡贤磊；

【作者基本信息】 东北大学 ， 材料加工工程， 2008， 博士

【摘要】 纵向变厚度扁平材是一种节约型钢材,在国外已经得到了应用,国内对纵向变厚度扁平材轧制技术研究较少。本文对纵向变厚度扁平材轧制理论和控制策略进行研究,阐述纵向变厚度扁平材楔形段轧制理论,推导实际应用的变厚度轧制尺寸预测公式,研究轧制过程的多点设定和厚度控制。将开发的模型和控制策略通过编程实现,嵌入现有的基础自动化和过程控制程序中,在轧机上进行变厚度轧制实验和在线应用,取得了满意的控制效果,主要工作和进展如下：(1)阐述了扁平材纵向变厚度轧制过程的基本轧制理论。对比常规轧制和变厚度轧制过程,分析扁平材纵向变厚度轧制过程的金属变形、金属流动规律和纵向变厚度轧制过程的特点。将纵向变厚度轧制分为增厚轧制和减薄轧制,证明纵向变厚度扁平材的出口位置同轧辊轴心的连线与上下工作轧辊轴心连线的夹角等于楔形段的倾斜角。从变厚度轧制过程的变形、运动学、力学条件出发,推导出楔形段轧制过程咬入条件、中性角、接触弧长度和前滑等轧制参数公式。各轧制参数非线性变化,倾角和压下量越大,非线性越明显。(2)进行了纵向变厚度扁平材轧制的尺寸预测。分析纵向变厚度轧制过程中的宽展成因和影响因素,根据现有的半理论半经验宽展公式,引入了宽展体积系数,在扁平材纵向变厚度轧制过程的笛卡尔坐标系内,取纵向变厚度扁平材轧制方向上一微单元进行分析,利用体积不变定律推导出以长度为变量的纵向变厚度轧制过程的宽度函数。采用离散化的方法按照纵向进行分段,对各段延伸量求和,得到沿纵向变厚度扁平材轧制后钢板长度公式。(3)针对纵向变厚度扁平材轧制过程厚度和辊缝变化规律,提出了多点动态设定方法。厚度线性变化的钢板轧制过程中的辊缝为非线性变化,单点静态设定法不能满足纵向变厚度轧制过程要求,必须在轧制方向上进行多点动态设定。将设定点分为恒定厚度的普通轧制段设定点和连续变厚度楔形段轧制设定点两大类,着重分析了楔形段设定点的确定机理,采用惩罚函数法对设定点求解,逐步让设定辊缝逼近目标辊缝。(4)分析中厚板轧制过程平面形状、变宽度和LP钢板纵向变厚度轧制过程设定点的确定方法,推导设定点的厚度、轧制力、辊缝和压下速度等轧制参数的计算公式,计算相邻设定点间辊缝线性化后的动态调节量。在纵向变厚度轧制前要对设定点的轧制力和转矩进行校核,保证压下速度和轧制速度匹配,并且辊缝变化量在液压缸有效行程内才能进行轧制。(5)建立了长度方向上的精确微跟踪和轧制过程动态厚度控制策略。对纵向变厚度扁平材进行计算机离散化处理,采用牛顿迭代法,建立纵向变厚度轧制过程的微跟踪模型。利用P-H图分析了纵向变厚度轧制过程厚度变化规律和变厚度轧制过程的厚度控制特点。纵向变厚度扁平材轧制过程厚度变化分为变厚度轧制过程外扰引起的厚度变化量和轧制出目标厚度需要增加或者减少厚度调整量。根据实测轧制力和目标厚度,通过ABS-AGC计算调整过程的被动辊缝变化,由液压缸控制系统进行纵向变厚度轧制过程带载多目标辊缝调整,完成动态厚度控制。分析中厚板变厚度轧制过程基于过程控制的宏观跟踪,利用西门子SIMATIC TDC或者FM458在中厚板轧机上实现变厚度轧制过程的微跟踪和动态厚度控制。(6)纵向变厚度轧制技术的实验和工业应用。在实验室四辊可逆轧机上编写动态多点设定和动态辊缝带载压下程序,进行了单向单道次、双向单道次、单向多道次、双向多道次纵向变厚度轧制实验。记录轧制过程的辊缝、轧制力,测量轧后的钢板厚度,对实验测量值与设定值进行比较,结果表明多点设定模型和动态辊缝调整策略能够满足纵向变厚度轧制过程的要求。在国内自主开发的中厚板生产线上,进行平面形状控制的成形MAS纵向变厚度轧制工业应用,得到了良好的钢板形状,采用指数型补偿曲线在钢板头部进行纵向变厚度轧制补偿,效果明显。本文建立的扁平材纵向变厚度轧制基本理论和控制策略为变厚度轧制技术在国内的应用和推广提供了重要理论依据,纵向变厚度轧制实验为工业应用提供了实验依据和参考数据。现场平面形状控制的MAS轧制和钢板头部变厚度补偿控制的应用取得了良好的控制效果,有较高的经济效益。更多还原

【Abstract】 Longitudinally profiled flat steel is a kind of saving type steel products which has been applied oversea, but rolling technologies of longitudinally profiled flat steel was hardly studied in domestic rolling line. Rolling theory and control strategy of longitudinally profiled flat steel were studied in this dissertation. Rolling theory of longitudinally profiled flat steel was expounded and rolling dimension prediction formulas were developed, and multiple-point setup method and thickness control in the rolling process were studied. Experiment and application were done in mill by the programs which were inset PLC and process control programs. Good control effect was obtained. The main works are as follows:(1) Basic rolling theory of longitudinally profiled flat steel was expounded. According to comparison between conventional rolling and longitudinally profiled flat steel rolling, metal flow law and metal deformation were analyzed, and rolling characters were given. Longitudinally profiled flat steel rolling process is classified as thickening rolling and thinning rolling. The radius angel both link line between contact point and working roller center and link line of two working roller centers equals to the taper slop angle. Beginning with deforming and kinematics and mechanics condition, rolling parameters such as Biting condition, steady rolling condition, neutral angle, contact arc and forward slip were analyzed and their formulas were deduced. Variation of rolling parameters is nonlinear, and the bigger is the slope of taper section, the more obvious is non-linearity of rolling parameters.(2) Dimension forecasting of longitudinally profiled flat steel was done. Cause and influencing factors of spread for longitudinally profiled flat steel were analyzed. By semi-theory and semi-empirical formulas and introducing spread volume coefficient, micro-element was selected and analyzed along longitudinal direction in longitudinally profiled flat steel. Width function of longitudinally profiled flat steel was deduced by volume constancy. Longitudinally profiled flat steel was divided into multiple segments and total length was calculated by length of each segment.(3) The method of multiple-point dynamic setup was presented according to the varying laws of thickness and gap in the longitudinally profiled flat steel rolling process. The thickness of taper plate is linear, but gap variation is nonlinear. The traditional signal-point static setup is not suitable for longitudinally profiled flat steel, so multiple-point dynamic setup is necessary. Because longitudinally profiled flat steel is usually composed of the taper segments and common segments, rolling setup points are divided into two classes:taper segment setup points and common segment setup points. Mechanism of multiple-point setup was analyzed. Intermediate setup point is solved by penalty function method, and multiple-point dynamic setup assures that setup gap approaches target gap.(4) Decision method of setup points was respectively discussed in plan view pattern control and variable width plate rolling and longitudinally profiled plate rolling. Rolling parameters formulas of setup points such as rolling force and thickness and gap etc. were deduced. Dynamic adjusting amount of gap between nearby setup points was considered as linear variation, and was calculated by linear equation. Rolling force and rolling moment were checked by equipment ability. Matching of screw speed and rolling speed and effective travel of cylinder should be considered before longitudinally profiled flat steel was rolled.(5) Precise micro-tracking along length and dynamic thickness control strategy in the longitudinally profiled flat steel rolling process were built. Based on discrete disposal of the length of longitudinally profiled flat steel, longitudinal micro-track model was established by Newton’s iteration method. The rules of gap variation and the characters of gauge control for taper plate in the longitudinally profiled flat steel rolling process were analyzed by use of P-H drawing. The variation of thickness is divided into passive thickness variation which is caused by external disturbance and active thickness variation which is necessary in taper segment. According to actual rolling force and target thickness, passive gap adjustiment was calculated by ABS-AGC. Multiple target gaps control was done by hydraulic cylinder control system in order to control dynamic varying thickness. Macro-tracking based on process control in plate mill line was analyzed. Micro-tracking and dynamic thickness control stragety were implemented by use of SIMATIC TDC or FM458 in plate rolling line.(6) Experiment and application of longitudinally profiled flat steel were done. Programs of dynamic multiple-point setup and dynamic adjustment of gap were complied in the four-high pilot rolling mill. Different kinds of longitudinally profiled flat steel were rolled in mill under different rolling condition, including single direction and single pass, and two-direction and single pass, and single direction and several passes and two-direction and several passes. Gap and rolling force were recorded, and delivery thickness was measured by micrometer calipers. Multiple-point setup model and control strategy can meet rolling requirement of longitudinally profiled flat steel by comparison between setup data and actual data. The forming MAS rolling process of plan view pattern control is applied in domestic heavy and medium plate rolling line. Rectangle figure of pate with forming MAS rolling is obtained. Exponential curve is adopted in varying thickness compensation at the head of plate, and compensation effect is obvious.Basic theory and control strategy built in the dissertation are important in the longitudinally profiled flat steel rolling process, and rolling experiment of longitudinally profiled flat steel supplies experimental basis and data reference for industry application. Good control effect and economic benefit are obtained in the MAS rolling process and varying thickness compensation control at head of plate.更多还原