带钢冷连轧材料变形抗力模型研究

针对冷连轧轧制过程的特点,变形程度是影响变形抗力的一个重要因素。建立了变形抗力的机理模型,并将理论模型与实际数据相结合。采用某钢厂生产的低碳钢08AlA稳定轧制时的现场实测数据,利用最小二乘逐次回归变形抗力模型中的各个参变量,并选用不同的方法来获得摩擦系数,选出与实际生产数据相吻合的最佳模型。将回归出的不同变形抗力模型,分别代入轧制力迭代公式进行计算,通过比较与实测轧制力的误差,选出最优的形抗力模型应用于实际生产中轧制力和前滑的预设定。     

冷连轧过程控制系统的自适应功能实现

针对冷连轧过程控制系统的模型设定计算的特点与需求,建立了轧制力、前滑、扭矩和辊缝自适应系数的计算模型,同时给出了冷连轧过程摩擦因数和变形抗力参数的反馈计算模型,进而完善和优化冷连轧轧制参数模型。为实现实测数据的采集与处理,设计了基于事件、计时器和消息的3种实测数据采集方法。最终完成冷连轧过程控制的自适应功能开发,并将其应用到生产实践中。结果表明,该自适应功能模块有效保证了在线模型设定计算的快节奏,大大提高了原始模型的计算精度,有利于提高系统稳定性和运算效率,适合于工业生产实践。     

一种新型的基于最小二乘回归St14钢变形抗力模型的方法

冷连轧的主要工艺参数为轧制力和前滑,而轧制力和前滑设定计算的精度取决于轧件的变形抗力和摩擦因数的精度,变形程度是影响变形抗力的一个重要因素,将所选变形抗力回归模型经过取对数等变换成线性函数,以鞍钢生产的St14钢为例,利用现场实际数据通过最小二乘来逐次拟合变形抗力回归模型中的系数。在同一轧制条件下,摩擦因数用3种不同的获得方法,其中前2种是由实测前滑值反算得到的,以使所得模型能够很好地与实际生产的数据相吻合。用回归出的3种不同变形抗力模型,分别带入轧制力迭代公式进行计算,所得轧制力基本与实测轧制力相符,其中由斯通公式拟合出的变形抗力回归模型计算出的轧制力平均误差很小,由此可以选出最优的变形抗力模型来应用于实际生产中轧制力和前滑的预设定。     

冷连轧过程控制数学模型研究

轧制力的计算受变形抗力、摩擦系数、轧辊压扁等多种轧制因素影响,是一个非线性关系.对冷连轧轧制力模型进行了研究,考虑轧制变形区内金属塑性变形和入、出口弹性变形,采用将变形区离散化的方法,建立冷连轧机轧制力数学模型.经实践数据检验,该轧制力模型的计算结果误差小,能较好的满足生产需要.     

基于EXCEL的冷连轧模型调试工具

建立一套可靠的离线模型调试工具,为实际生产提供技术依据十分重要。依据冷连轧轧制力模型公式、辊缝模型公式、轧辊压扁半径计算模型等公式,在EXCEL下建立了各个模型之间的关系。通过先调整变形抗力参数,再调整摩擦因数可以使轧制力自适应系数达到1;通过采集实际的轧制力,用实际轧制力公式反推摩擦因数,达到调整模型参数的目的。     

TSCR流程生产无取向电工钢的冷轧变形抗力模型

利用MTS880、WE-300拉伸试验机对采用TSCR流程生产的3种不同Si+Al含量的无取向电工钢冷轧变形抗力进行了研究,分析了可逆轧制和连轧过程生产方法对变形抗力的影响,并通过试验数据建立了变形抗力数学模型,并对模型判定系数分析和回归计算结果与实际测试结果进行比较,结果表明此模型具有良好的曲线拟合特性。     

精冲带钢冷连轧生产过程的卷取分析

实现厚规格精冲带钢的顺利卷取是精冲钢冷连轧生产工艺成功应用的关键。利用4辊可逆冷轧机进行轧制试验,在MMS-200热模拟试验机上测定精冲钢的应力-应变曲线,建立精冲钢冷轧终态变形抗力模型。针对1750mm冷连轧机组配置的卡罗塞尔卷取机,进行精冲带钢卷取过程的机理分析和卷取状态的受力分析,为精冲钢冷连轧极限厚度卷取能力的分析和计算提供理论支撑。在此基础上,完成了不同摩擦条件下多规格精冲钢冷连轧生产卷取机的极限厚度计算,并给出相应的安全卷取厚度窗口。该研究适合于工业生产实践,对精冲钢冷连轧生产工艺研究具有重要意义。     

基于实测值置信度的冷连轧轧制力模型自适应

 采用数值积分方法建立了冷连轧在线轧制力模型,确定了轧制力模型自适应的执行条件和计算流程。针对轧制力模型自适应指数平滑算法中难以用固定增益系数适应轧制状况变化的问题,提出了一种根据实测数据动态调整增益系数的方法,建立了增益系数与测量值等效置信度之间的数学关系式。该轧制力模型自适应算法已应用在某1450mm 5机架冷连轧机组上,通过比较自适应前后的计算值与实测值的均方差可知,采用模型自适应后,轧制力模型的计算精度显著提高。     

梅钢1420冷连轧机轧制力模型的开发及应用

梅钢1420轧制力模型在Hill方程基础上,分解提炼3个关键因子,建立了显函数的轧制力模型,并进行变形抗力参数和摩擦系数参数的自适应修正以提高轧制力模型精度.经生产实践数据检验,该模型自适应系数在0.9～1.1以内,满足模型在线控制要求.     

热轧相变过程变形抗力模型研究与开发

 对精轧阶段存在相变的热轧钢种,因变形抗力随轧制温度的变化规律与常规的奥氏体轧制钢种显著不同,使得传统变形抗力模型的预报误差较大,严重影响这类钢种的轧制稳定性。为此,研发了一种热轧相变过程变形抗力模型,通过在原变形抗力模型基础上添加一个新的相变趋势项,该修正项为轧制温度的二次多项式函数,并根据钢种分类来精细优化适应不同钢种轧制的多项式待定参数。该模型目前已成功应用于涟钢CSP热连轧生产线变形抗力在线计算,实际生产应用表明,新模型上线后,变形抗力与轧制力的预报精度显著提高,轧制力模型预报误差12%以内的比例从83.3%提高到96.7%,满足了热连轧精轧相变带钢的稳定生产要求。     

超高强钢冷轧过程轧制力计算的改进模型

 为了解决采用圆弧模型计算超高强钢冷轧过程轧制变形区轧辊压扁曲线误差较大的问题,充分考虑到超高强钢的轧制特点,通过分析不同压扁半径下轧辊压扁曲线的变化规律,构造出新型轧辊压扁曲线函数模型,给出了该函数中轧制变形区接触弧长特性参数与轧辊压扁曲线特性参数的求解方法。基于此,根据弹塑性理论中的变形与应力关系,推导了入口弹性变形区、塑性压下变形区以及出口弹性变形区单位轧制压力分布计算过程,建立了超高强钢冷轧过程总轧制力计算模型。并将其推广应用到某钢厂2030冷连轧机组,验证了该模型的计算准确度。结果表明,超高强钢冷轧过程轧辊压扁曲线用二次函数表示,更能准确反映轧辊压扁状态,其计算结果与实际值具有较高的吻合度。同时,为冷连轧机组生产超高强钢产品极限轧制能力的评估与轧制规程的制定提供了理论依据。     

Prediction and Control of Thermal Scratch Defect on Surface of Strip in Tandem Cold Rolling

The thermal scratch significantly influences the surface quality of the cold rolled stainless steel strip.In order to establish a precise mathematical model of oil film thickness in deformation zone,the lubrication in cold rolling process of B443 NT stainless steel strip was studied in the laboratory.According to the principle of statistics,a mathematical model of critical oil film thickness in deformation zone for thermal scratch was built,with fitting and regression analytical method,and then based on temperature comparison method,the criterion for deciding thermal scratch defect was put forward.Storing and calling data through SQL Server 2005,a software on thermal scratch control was developed in the Microsoft Visual Studio 2008 environment by MFC technique for stainless steel in tandem cold rolling,and then it was used into the practical production.Statistical results demonstrated that the hit rate of thermal scratch arrives at 91.47%,the occurrence rate of thermal scratch is decreased by 87.81%,and rolling speed is increased by 7.3%.The developed software is of significance to the control of products quality of stainless steel strips,and the analysis and solution to the problem of thermal scratch defects in tandem cold rolling.     

A novel approach to improve the computing accuracy of rolling force and forward slip

In cold strip rolling control system, rolling force and forward slip are the prerequisites for the model setting calculation, and the deformation resistance and friction coefficient are the main parameters that affect their predictions. A new method based on objective function is first proposed in this paper to improve the calculation accuracy of rolling force and forward slip, and the deformation resistance and friction coefficient are taken as optimisation variables. Using the multi-population co-evolutionary algorithm to solve the objective function, the required rolling force and forward slip are obtained. The pre-set values of rolling force and roller line speed are compared with the actual measured ones in a 1450?mm five-stand tandem cold mill and other researcher’s method. Results show that the calculated values are in fair agreements with the on-line measured ones, and the thickness and flatness accuracy of the final product are improved.     

Application of cationic emulsion in stainless steel cold rolling

Emulsion,obtained by cationic emulsifiers,allows much larger oil droplets with narrower particle distribution,slows down the contamination from iron fines to the oil droplets,and is further enhanced with higher boundary and elastohydrodynamic lubrication for a relatively slower rolling process but high rolling force.As a result,it is suitable for the cold rolling of stainless steel.Cationic emulsion is now applied in a 1 750 mm 5-stand tandem cold rolling mill of Baosteel to roll stainless steel and carbon steel.The production process is stable and the product quality satisfies customer requirements.     

提高轧制力设定精度的一种离线优化方法

轧制力参数设定是轧机设定模型的核心参数之一,对决定成品卷的厚度精度及板型质量至关重要。京唐酸轧二级模型计算轧制力时采用Bland-Ford-Hill公式,经分析确定影响轧制力计算精度的参数主要为变形抗力和摩擦力因数。因此提出了一种利用特定钢种的初始历史实际轧制数据离线调整其变形抗力和摩擦力因数的方法,从而提高本钢种在线轧制力模型的设定精度。实际应用表明,使用通过此方法优化后的变形抗力和摩擦力参数计算轧制力,轧制力设定模型的精度得到了明显提高,能够满足在线控制需求。     

Evaluation on some important force models for cold strip rolling

To improve the accuracy of rolling force prediction, some important force models were evaluated through applied computation for cold rolling of low carbon steel and aluminum alloy according to measured data on lab mill. The effects of model structure and three important variables ‐ flow stress, contact length and friction coefficient ‐ on the precision of computed force were quantitatively studied. Flow stress was measured with plane‐strain compression test, contact length was based on elastic flattening of work‐roll by Hitchcock, and friction‐coefficient was determined by rolling strain and numerical iteration. In steel rolling Bland & Ford integration model and Bryant & Osborn algebraic equation are better in accuracy than Ekelund and Parkins. In aluminum rolling all the models produce large deviations ΔF_R = 10–20% if flow stress, contact length and friction coefficient are determined with the same method as steel rolling. The elastic deformation of aluminum strip is now taken into account for its low elastic modulus. An effective method to determine plastic and elastic contact has been developed in this investigation. The accuracy of force computation is obviously improved for aluminum rolling.