热轧带钢层流冷却控制系统及控制方法

介绍带钢热连轧机层流冷却控制系统的现状、冷却策略及控制技术难点,对热轧带钢层流冷却控制方法进行实例分析。     

热轧层流冷却装置

简要阐述层流冷却装置在热轧机组中的重要性,实例介绍层流冷却装置的结构构成、工作方式及工艺控制特点等。     

热轧带钢更换规格卷取温度分析及其补偿研究

热轧带钢卷取温度是反映热轧带钢性能指标的重要参数之一,介绍了某700 mm热连轧机层流冷却的组成及其工作原理,针对其具体情况,基于实时数据,应用数据挖掘工具,从理论和工艺的角度分析了控冷过程中热轧带钢更换规格温差大问题产生的原因,得出了热轧带钢更换规格的规律,并应用回归统计建立了温度补偿模型,进行了实验研究,实验结果表明,应用数据挖掘技术从立体的现场数据中得出热轧层流冷却控制模型的做法,对提高控冷精度,优化生产工艺具有一定意义。     

650mm热轧窄带钢生产线设备改造

介绍国内某650 mm热轧窄带钢生产线改造项目上的飞剪区、层流冷却区、地下卷取机区机械设备的技术改造。阐述了采用转鼓式飞剪、精轧机后设置层流冷却装置、由卧式全液压四助卷辊卷取机取代传统窄带钢立式卷取机的优越性。     

热轧层冷智能供水控制系统的应用与分析

热轧层流冷却(层冷)系统能源消耗高,自动控制水平低。本文通过热轧层冷系统工艺及能耗的分析,采用变频技术并制定相应的智能控制模型和策略,降低能耗。     

人工神经网络在热轧生产线中的应用

人工神经网络是近年来迅速发展起来的一种新型信息处理手段。简述了热轧生产线的工艺过程和主要设备,分别介绍了神经网络在加热炉、厚度自动控制、层流冷却等热轧生产工艺中的应用。可以看出,神经网络在热轧生产中发挥着重要的作用。     

边部遮挡功能在热轧带钢轧制中的应用

介绍了层流冷却区冷却水梁及边部遮挡功能的应用方法及控制程序。边部遮挡功能在很大程度上解决了热轧带钢的"边浪"问题。     

热轧冷却方式和冷轧压下率对含钛IF钢冷轧板组织和力学性能的影响

以工业生产的、采用层流冷却和超快速冷却的含钛IF热轧板为试验材料,在实验室研究了热轧冷却方式和冷轧压下率对退火后试验钢组织和力学性能影响。结果表明:当冷轧压下率为65%和75%时,与层流冷却相比,超快速冷却试验钢的Rp0.2约低10MPa左右,n值高0.02,r值稍高;当冷轧压率在55%~85%时,试验钢的Rp0.2为100~120MPa;最佳工艺为热轧后采用超快速冷却,PY400温度约为780℃、冷轧压下率为65%~75%、退火温度为730℃;在此最佳工艺下,试验钢具有较低的屈服强度和优良的冲压成型性能。     

控制冷却对含Nb钢组织性能的影响研究

为了进一步提高含Nb钢的强度,降低含Nb钢的开发成本,通过实验室热轧试验研究超快冷、超快冷+层流冷却和层流冷却3种冷却模式对含Nb钢的组织演变和力学性能影响。结果表明,与层流冷却相比,试验钢采用超快冷后组织中出现针状铁素体和贝氏体,晶粒尺寸细化,位错显著增加,析出物粒子更为细小,试验钢力学性能显著提高。超快冷的主要强化机制为相变强化、细晶强化、位错强化和析出强化。超快冷+层流冷却模式下,随着终冷温度的降低,软相组织减少、硬相组织增多,试验钢的强度升高。随着出超快冷温度的降低,多边形铁素体体积分数逐渐减少且晶粒更为细小,针状铁素体体积分数增多,试验钢强度得到提高,断后伸长率略有降低。以上结果为超快冷工艺条件下开发低成本含Nb钢奠定了理论基础。     

层流冷却辊激光熔覆修复及再制造技术

为了提高热轧层流冷却辊的一次修复合格率及在线使用寿命,采用激光熔覆手段在20钢基体表面熔覆合金层,并对熔覆层的成分、硬度和冶金结合效果进行检测。经上线试验,结果表明激光熔覆修复的辊子在线使用周期2年以上,达到进口件的寿命指标。     

Effect of Oscillation Parameters to Flow Field in the Pool during the Oscillating Twin-Roll Strip Casting Process

During the oscillating twin?roll strip casting process, the quality of final products is directly influenced by the flow field distribution of molten metal in the pool. The variation in the flow field is caused by oscillating roller benefits, for homogeneous distribution of strip impurity, and decreasing the grain size. Thus, the quality of the strip could be improved. A numerical model was developed using the multiphase flow technology, coupled with heat transfer, fluid flow, solidification, and oscillation. Furthermore, a transient algorithm was adopted for simulating the oscillating twin?roll strip casting process of AlSi9Cu3 and 3104 aluminum alloy. This paper focuses on the flow distribution in the pool, in comparison with the traditional vertical twin?roll strip casting process, while the amplitude or frequency is chang?ing with the definite value of casting velocity, roller diameter, nozzle angle, and the strip thickness. Consequently, the conclusions were experimentally validated by oscillating twin?roll 3104 aluminum alloy strip casting. Vibrating casting technology can change the flow field in the pool by vibration, which can improve the quality of the strip core.     

A study on the air knife flow with Coanda effect

The coating thickness in hot-dip zinc galvanizing process is of practical importance in determining the quality of product, and its control is often done using the gas wiping through an air knife system. Such a gas wiping method causes a technical problem of splashing from the strip edge to have a harmful effect on the performance of the galvanizing process and the product quality. The present study aims at investigating the effectiveness of Coanda nozzle to reduce the strip splashing problem. A blow-down wind tunnel has been used to experimentally investigate the detailed flow field near the exit of Coanda nozzle and on the strip edge. A computational work has been performed with the help of a computational fluid dynamics method. The three-dimensional, compressible Navier-Stokes equations have been solved using a fully implicit finite volume scheme. The results obtained show that Coanda nozzle effectively reduces the splashing problem, leading to improvement of the whole galvanizing process.     

自控回流阀在乙烯热电联产装置的应用及改进

探讨了乙烯项目热电联产装置高压锅炉给水泵起最小流量保护作用的国产自控回流阀在开工生产过程中出现的振动问题,通过理论计算结合实际解体检查情况分析了故障原因,并以此为依据提出了相应的改进方案。     

Development of friction model for offset strip fin with separated viscous and inertial resistances

To predict the flow resistance of a compact heat exchanger with an offset strip fin, a large number of correlations have been developed and these correlations have been well used in the engineering field. Recently, three-dimensional computational analysis has been frequently used for the design and verification of heat exchangers. To improve the accuracy of three-dimensional numerical analysis and reduce the resources used for the analysis, the fins of compact heat exchangers are assumed to be a porous medium generally. To predict the flow resistance of an offset strip fin assumed to be a porous medium, the resistance must be separated into viscous and inertial resistances. However, the correlations developed so far for the offset strip fin have not been able to distinguish between these resistance types. In this paper, we propose a new friction model that can represent the flow resistance of an offset strip fin as the sum of the viscous and inertial resistances. The new friction correlation model has a maximum error of 10 % compared to existing correlation models. In addition, using the new friction model, the permeability and the Ergun constant for offset strip fins are defined as functions of offset strip fin parameters. Therefore, when predicting the flow resistance of a compact heat exchanger with an offset strip fin using three-dimensional numerical analysis, viscous and inertial resistances can be defined without additional calculations or tests for a porous medium approach.

     

模拟板带轧制三维变形的流面条元法

提出模拟板带轧制过程三维变形的一种新的数值方法——流面条元法。沿着金属的流动轨迹,将变形区划分为若干流面(曲面)条元,为方便分析和计算,又将其映射为平面条元。横向位移和高向位移的纵向分布被分别构造为四次曲线和二次曲线,其横向分布均用三次样条插值函数表示,高向分布均用二次曲线拟合。根据塑性力学流动理论,分析推导了变形区三维变形和应力的数学模型。与曾经提出的流线条元法相比,考虑了应力与变形沿高向的不均匀分布,实现了精确的三维分析和计算。仿真实例表明,该方法和模型符合实际,为板带轧制过程的三维力学仿真提供了一个新的实用工程数值方法。     

20辊轧机轧件截面形状与边部减薄预报软件开发

利用接触元双坐标法（CEM）建立了双AS—U—Roll系统森吉米尔轧机轧制过程中轧件及辊系变形行为的CEM函数矩阵,并开发了SM4SM软件。该软件能够很好地预报各种轧制条件下轧件截面形状、轧件边部减薄、轧制力、轧辊挠曲等功能。文中应用SM4SM,分析了第一中间辊锥角、锥度长度和窜辊长度对轧件截面形状和轧件边部减薄控制的影响。研究结果对冷轧过程控制轧件板形和边部减薄具有重要的参考价值。     

Stream surface strip element method for simulation of the three-dimensional deformations of plate and strip rolling

A new method—the stream surface strip element method (SSSEM)—for simulating the three-dimensional deformations of plate and strip rolling process is proposed. The rolling deformation zone is divided into a number of stream surface (curved surface) strip elements along metal flow traces, and the stream surface strip elements are mapped into the corresponding plane strip elements for analysis and computation. The longitudinal distributions of the lateral displacement and the altitudinal displacement of metal are constructed respectively to be a quartic curve and a quadratic curve, the transverse distributions of them are expressed as the third-power spline function, and the altitudinal distributions of them are fitted to be a quadratic curve. Based on the flow theory of plastic mechanics, the three-dimensional deformations and stresses of the deformation zone are analyzed and formulated. Compared with the streamline strip element method, the SSSEM considers the uneven distributions of stresses and deformations along altitudinal direction, and realizes an accurate three-dimensional analysis and computation. The simulation examples indicate that the method and the model of this paper are in accord with facts, and provide a new reliable engineering-computation method for the three-dimensional mechanics simulation of plate and strip rolling process.     

Development of diagnosis system for knife and strip cutting face in the side trimming process

It is very important to measure and diagnose the state of knife and strip cutting face in real time in the side trimming process due to improvement of quality of strip trimming face. In this study, a diagnosis system for knife and strip cutting face was developed. Two CCD cameras facing each other are mounted at the delivery side (the entry of the bur masher roll) of the side trimmer. This system offers the operator the diagnosis result of state of knife and strip cutting face. With the help of the developed system, the knife breakage has been detected 100% and bad quality of trimming face is significantly decreased. Using CCD cameras, an on-line diagnosis system which can determine knife breakage and bad quality of trimming face in real time is developed in trimming. A diagnosis algorithm determining the state of the strip cutting face is also developed by calculating characteristic values and image processing based on the images of the strip cutting face obtained from CCD camera.     

Control Scheme Using Forward Slip for a Multi-stand Hot Strip Rolling Mill

Forward slip is an important parameter often used in rolling-speed control models for tandem hot strip rolling mills. In a hot strip mill, on-line measurement of strip speed is inherently very difficult. Therefore, for the set-up of the finishing mill, a forward slip model is used to calculate the strip speed from roll circumferential velocity at each mill stand. Due to its complexity, most previous researches have used semi-empirical methods in determining values for the forward slip. Although these investigations may be useful in process design and control, they do not have a theoretical basis. In the present study, a better forward slip model has been developed, which provides for a better set-up and more precise control of the mill. Factors such as neutral point, friction coefficient, width spread, shape of deformation zone in the roll bite are incorporated into the model. Implementation of the new forward slip model for the control of a 7-stand hot strip tandem rolling mill shows significant improvement in roll speed set-up accuracy.