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。     

Coupled dynamic modeling of rolls model and metal model for four high mill based on strip crown control

The crown is a key quality index of strip and plate,the rolling mill system is a complex nonlinear system,the strip qualities are directly affected by the dynamic characteristics of the rolling mil.At present,the studies about the dynamic modeling of the rolling mill system mainly focus on the dynamic simulation for the strip thickness control system,the dynamic characteristics of the strip along the width direction and that of the rolls along axial direction are not considered.In order to study the dynamic changes of strip crown in the rolling process,the dynamic simulation model based on strip crown control is established.The work roll and backup roll are considered as elastic continuous bodies and the work roll and backup roll are joined by a Winkler elastic layer.The rolls are considered as double freely supported beams.The change rate of roll gap is taken into consideration in the metal deformation,based on the principle of dynamic conservation of material flow,the two dimensional dynamic model of metal is established.The model of metal deformation provides exciting force for the rolls dynamic model,and the rolls dynamic model and metal deformation model couple together.Then,based on the two models,the dynamic model of rolling mill system based on strip crown control is established.The Newmark-β method is used to solve the problem,and the dynamic changes of these parameters are obtained as follows:(1) The bending of work roll and backup roll changes with time;(2) The strip crown changes with time;(3) The distribution of rolling force changes with time.Take some cold tandem rolling mill as subject investigated,simulation results and the comparisons with experimental results show that the dynamic model built is rational and correct.The proposed research provides effective theory for optimization of device and technological parameters and development of new technology,plays an important role to improve the strip control precision and strip shape quality.     

六辊CVC轧机辊系变形的有限元分析

建立了运用有限元软件ANSYS求解具有特殊辊廓曲线和辊间接触状态的六辊CVC轧机辊系三维弹性变形的有限元模型，合理解决了对辊间接触压扁变形的建模问题，实现了对较复杂变形的求解。以国内某1420冷轧机组为研究对象，结合现场实际数据，运用有限元软件ANSYS求解六辊CVC轧机的辊系三维弹性变形，计算结果与实测数据吻合较好。     

Research and application of non-symmetrical roll bending control of cold rolling mill

The existing research of the flatness control for strip cold rolling mainly focuses on the calculation of the optimum adjustment of individual flatness actuator in accordance with the flatness deviation,which can be used for general flatness control.However,it does not work for some special rolling processes,such as the elimination of ultra single side edge-waves and the prevention of strip break due to tilting roll control overshooting.For the purpose of solving these problems,the influences of non-symmetrical work roll bending and intermediate roll bending on flatness control were analyzed by studying efficiencies of them.Moreover,impacts of two kinds of non-symmetrical roll bending control on the pressure distribution between rolls were studied theoretically.A non-symmetrical work roll bending model was developed by theoretical analysis in accordance with practical conditions.The model was applied to the revamp of a 1250 6-H reversible universal crown mill (UCM) cold mill.Theoretical study and practical applications show that the coordination utilization of the non-symmetrical work roll bending control and tilting roll control was effective in flatness control when there appeared bad strip single side edge waves,especially when the incoming strip was with a wedge shape.In addition,the risk of strip break due to tilting control overshooting could be reduced.Furthermore,the non-symmetrical roll bending control can reduce the extent of uneven distribution of pressure between rolls caused by intermediate roll shifting in flatness control and slow down roll wear.The non-symmetrical roll bending control technology has important theoretical and practical significance to better flatness control.     

STUDY ON STRIP AND ROLL DEFORMATION COUPLING OF COLD STRIP ROLLING ON 4-H MILL

ＳＴＵＤＹＯＮＳＴＲＩＰＡＮＤＲＯＬＬＤＥＦＯＲＭＡＴＩＯＮＣＯＵＰＬＩＮＧＯＦＣＯＬＤＳＴＲＩＰＲＯＬＬＩＮＧＯＮ４ＨＭＩＬＬ①ＬｉｕＨｏｎｇｍｉｎＨｕＧｕｏｄｏｎｇＹａｎｓｈａｎＵｎｉｖｅｒｓｉｔｙＡｂｓｔｒａｃｔＴｈｅｃｏｌｄｓｔｒｉｐｒｏｌ...     

六辊CVC宽带轧机轧辊接触压力横向分布特性的计算机仿真

用条元法分析带材的三维塑性变形,用影响系数法分析辊系的弹性变形,将二者联立,对1850mm六辊CVC轧机冷轧带材轧辊接触压力的横向分布进行了计算机仿真。结果表明,CVC中间辊横向移动、工作辊弯和中间辊弯辊等手段,对轧制压力的横向分布影响很大,对辊间压力的横向分布也有明显影响。在各种情况下,辊间压力都呈S形分布。     

Roll System and Stock’s Multi-parameter Coupling Dynamic Modeling Based on the Shape Control of Steel Strip

The existence of rolling deformation area in the rolling mill system is the main characteristic which distinguishes the other machinery. In order to analyze the dynamic property of roll system’s flexural deformation, it is necessary to consider the transverse periodic movement of stock in the rolling deformation area which is caused by the flexural deformation movement of roll system simultaneously. Therefore, the displacement field of roll system and flow of metal in the deformation area is described by kinematic analysis in the dynamic system. Through introducing the lateral displacement function of metal in the deformation area, the dynamic variation of per unit width rolling force can be determined at the same time. Then the coupling law caused by the co-effect of rigid movement and flexural deformation of the system structural elements is determined. Furthermore, a multi-parameter coupling dynamic model of the roll system and stock is established by the principle of virtual work. More explicitly, the coupled motion modal analysis was made for the roll system. Meanwhile, the analytical solutions for the flexural deformation movement’s mode shape functions of rolls are discussed. In addition, the dynamic characteristic of the lateral flow of metal in the rolling deformation area has been analyzed at the same time. The establishment of dynamic lateral displacement function of metal in the deformation area makes the foundation for analyzing the coupling law between roll system and rolling deformation area, and provides a theoretical basis for the realization of the dynamic shape control of steel strip.     

Study on the improved accuracy of strip profile using numerical formula model in continuous cold rolling with 6-high mill

The quality requirements for thickness accuracy in cold rolling continue to become more stringent. In cold rolling mill, it is very important that the rolling force calculation considers rolling conditions. The rolled strip thickness was predicted using calculated rolling force. However, the prediction of strip thickness in cold rolling is very difficult; in particular, for 6-high mill with shifted intermediate roll (IMR), the accuracy of thickness is not good. In this study, to improve the accuracy of rolled strip thickness, the roll gap flattening can be given based on Hertz contact theory, with contact between rolls and the smooth cylindrical rolls for the rolling elastic deformation. Also, the distribution of the roll gap flattening may be calculated using the contact force of unit transverse length. The strip profile at the continuous cold rolling is calculated by using the numerical analysis model considering the initial strip profile before cold rolling. Hence, we propose that the numerical model can predict the rolled strip profile more quickly and accurately and be applicable to the field. The results of the proposed numerical model were verified by FE-simulation and cold rolling experiments of 6-high mill with five stands.     

Continuous-forming method for three-dimensional surface parts combining rolling process with multipoint-forming technology

Flexible rolling is a novel forming process for three-dimensional surface parts, which combines the rolling process with multipoint-forming technology. This process employs a pair of forming rolls as a forming tool. By controlling the gap between the upper and lower forming rolls, residual stress caused by the longitudinal non-uniform elongation of sheet metal makes the sheet metal generate three-dimensional deformation. In this paper, the improvement of the process is introduced that the middle curve radius of the roll gap is much larger than the transverse curvature radius of the forming surface in the forming process. The forming roll rotates around its own axis easily because of the small bending deformation which is suitable for producing three-dimensional surface parts including the wide sheet metal with a relatively small transversal curvature radius. The forming principle is set forth, and corresponding formulations are presented. Finite element analysis model is established, and spherical and saddle surface are simulated. The forming precision and the causes of the shape errors are analyzed through simulated results. The experimental equipment is designed and their experimental results are obtained. Simulation results are in well agreement with the experimental results, which verifies the feasibility of using simulation to guide the experiment. The results of both numerical simulations and experiments show that the proposed process is a feasible and effective way of forming three-dimensional surface parts.     

计算冷轧带钢工作辊接触压扁的Hitchcock公式的有限元修正

采用弹塑性大变形有限元法对板带冷轧过程中工作辊的接触压扁进行模拟,利用数值手段对轧辊弹性压扁后的形状曲线进行拟合,并对计算轧辊压扁半径的Hitchcock公式进行了修正,大幅提高了轧制力的控制模型精度。     

Analysis of deformation textures of asymmetrically rolled steel sheets

Asymmetric rolling has been studied to obtain the shear deformation texture of bcc steels through the thickness. Asymmetric rolling in which the circumferential velocities of two working rolls are different can be achieved by different roll radii at the same rotation rates, different roll speeds at the same roll radii and single roll drive. The deformation of steel sheets in the three different asymmetric rolling methods was analyzed by FEM. The deformation was used to calculate crystal rotation by full constraints Taylor model to predict the deformation textures. The texture evolution during the asymmetric rolling was measured and analyzed with the emphasis on the effect of shear reversions.     

Numerical simulation and experimental study on geometry variations and process control method of vertical hot ring rolling

The accurate geometry and effective control during the ring rolling process are the prerequisites for the ring products’ precise forming. In this paper, the interaction modes and rules between ring and rolls in vertical hot ring rolling (VHRR) process are analyzed, and the change laws of the ring’s geometry are studied. Based on the ABAQUS/Explicit software and its subroutine VUAMP, the finite element (FE) model of the VHRR process with measurement and control is established. Then, the ring rolling process of a groove-section profile ring is simulated. During the simulation, the ring’s outer diameter, roundness error, and the stability of the rolling process are detected in time, and the close-loop control of feed plan of the drive roll and measuring roll are also employed. The results obtained show the following: (1) Four feed stages are divided by means of a step-down feed movement, that is, bite stage, main rolling stage, precise forming stage, and sizing stage. (2) At bite and main rolling stages of the VHRR process, the ring’s center swings in a spiral line, and the rolling process is unstable, the ring’s roundness becomes worse, while the process is entering the precise forming stage, by means of the guide roll, the rolling process becomes steady and the ring’s roundness tends to be better. (3) The measuring roll contacts with the ring at the main rolling stage, afterwards, it is pushed back at the precise forming stage by ring’s growth. When the measuring roll meets the desired displacement value, a stop feeding command will be fed back, and the ring rolling process enters the sizing stage. At the sizing stage, the ring’s outer diameter still increases a little. (4) A series of VHRR experiments are conducted, and FE results are in good agreement with experimental results. The absolute errors of the ring’s outer diameter and the roundness are within 1 mm. The research results of this paper have practical significance to guide the VHRR production.     

Chatter dynamics in sheet rolling

Two and four degree of freedom (DOF) systems describing chatter in sheet rolling are investigated. In the two DOF case, this includes studying the nonlinear behavior that arises due to the deformation at the work-backup roll interface. The force displacement relation between two cylindrical rolls being pressed together is inherently nonlinear due to the changing contact area. The investigation also includes the additional plastic deformation of the sheet in the roll-bite that is present during chatter. As the work rolls vibrate the gap widens and narrows inducing additional plastic deformation of the sheet.For the two DOF case, one mode of vibration is a motion of the work roll-sheet mass center. The other mode is a squeezing motion of the sheet in the bite by the work rolls. The natural frequencies seem to correspond with fifth octave chatter. The nonlinear theory predicts a small shift in the vibrational frequency. The role of inter-stand tension in triggering instability is also discussed.The four DOF system extends the research of Yarita et al. by providing analytic expressions for the natural frequencies. It appears that this system is capable of predicting third octave chatter, in addition to fifth octave chatter.     

万能凸度轧机中间辊偏移板形调控能力分析

1420单机架万能凸度轧机(Universal crown mill,UCM)轧制极薄带时,中间辊偏移对正向轧制与负向轧制时工作辊弯辊、中间辊弯辊及中间辊窜辊的板形调控特性存在一定的影响,从力学角度分析辊系的受力状态,并运用LS-DYNA有限元软件建立显示动力学模型,定量计算中间辊不偏移轧制与正向偏移轧制及负向轧制时各板形调控手段的调控特性。计算结果显示轧机中间辊不偏移时,工作辊弯辊力与带钢凸度呈线性关系,随着工作辊弯辊力的增大,带钢凸度减小;当中间辊偏移时,工作辊弯辊调控功效要大于中间辊不偏移时,且正向轧制的弯辊调控功效要优于负向轧制;中间辊弯辊调控特性表现出与工作辊弯辊相似的变化趋势。不同中间辊窜辊的板形调控能力变化不大,不偏移轧制与负向轧制调控能力基本相同,正向轧制在窜辊量为15~30 mm范围内,其调控能力好于另外两种轧制工况。     

Fault diagnosis of roll shape under the speed variation in hot rolling mill

The metal processing system usually consists of various components such like motors, work rolls, backup rolls, idle rolls, sensors, etc. Even a simple fault in a single component in the system may cause a serious damage on the final product. It is therefore necessary to diagnose the faults of the components to detect and prevent system failure. Especially, the defects in a work roll are critical to the quality of strip. It is especially difficult to detect faults of a roll by using the existing frequency analysis method if the speed of the roll is changing. In this study, a new diagnosis method for roll eccentricity under the roll speed changes was developed. The new method was induced from analyzing the rolling mechanism by using rolling force models, radius-speed relationship, and measured rolling force, etc. Simulation results by using the field data show that the proposed method is very useful.     

A taper tension profile maker in a converting machine

Winding is an integral operation in almost every web handling process, and a center-wound roll is one of the suitable and general schemes in a winding system. However, improper internal stresses within a center-wound roll can cause damage such as buckling, spoking, cinching, etc. Wound roll quality and performance are known to be related to the distribution of in-roll stresses. It is therefore necessary to analyze the relationship between taper tension in the winding section and internal stress distribution within the center-wound roll to prevent winding failure. But it is hard to compensate for an undesirable winding roll shape such as starring, buckling, and telescoping. This is because the winding section is the final process in a roll to roll system and has no feedback control system to correct winding roll shape directly. A time varying tension profile and accurate control of it in a winding section is one way to shape the fail-safe in-roll stress distribution of a winding roll. In this study, a new taper tension profile making method is aimed for designing high quality wound rolls. A new method to determine the proper taper tension profile was designed by analyzing the winding mechanism which includes the stress model in center-wound rolls, nip induced tension model, relationship between taper tension profile and telescoping, relationship between taper tension type and internal stress distribution. An auto taper tension profile making method was proposed not only to optimize radial stress distribution but also to minimize lateral error (telescoping). Simulation results show that the proposed method is very useful for determining the desirable taper tension profile during the winding process and preventing defects of winding roll shape such as telescoping, starting, and dishing and so on.     

Three-dimensional FE analysis of ring rolling by employing thermal spokes method

This paper investigates the performance of the “Thermal Spokes Method” in modeling the effect of the guide rolls on the ring rolling process. If the guide rolls are not included FE, simulation encounters problems such as tilting of the ring and process instability. Thermal spokes are introduced to withstand any unwanted moment of the resultant rolling forces at the roll gap and to maintain the ring in a centralized location in the mill. By employing the thermal spokes method, much closer predictions for the lateral spread and flow patterns are calculated. This method is able to predict the tilting of the ring with respect to the stiffness of the elements of the adjustment mechanism. It is also possible by this method to predict the point at which the ring changes its support from one guide roll to another one and to study the deformation mechanism outside the roll gap. To verify the validity of the proposed method, the predicted results from this method are compared with some available references. Since the proposed method considers the effect of the guide rolls and consequently offers much closer predictions, it is a very suitable method for ring rolling simulations.     

Modi cation of Roll Flattening Analytical Model Based on the Plane Assumption

Roll flattening is an important component in the roll stack elastic deformation,which has important influence on controlling of the strip crown and flatness. Foppl formula and semi?infinite body model are the most popular analyti?cal models in the roll flattening calculation. However,the roll flattening calculated by traditional flattening models has a great deviation from actual situation,especially near the barrel edges. Therefore,in order to improve the accuracy of roll flattening,a new model is proposed based on the elastic half plane theory. The calculation formulas of roll flatten?ing are deduced respectively under the assumptions of plane strain and plane stress. Then,the two assumptions are combined through the method of introducing an transition coe cient,and the distribution rules of roll flattening for di erent rolling force,flattening width,roll length and roll diameter are analyzed by using the FEM analysis software Marc. Regarding the ratio of the length to roll end and the roll diameter as variable to fit the transition coe cient,the new model of roll flattening is established based on the elastic half plane theory. Finally,the transition coe cient is fitted to establish the model. Compared with the traditional models,the new model can e ectively improve the cal?culation deviation in the roll end,which has important significance for accurate simulation of plate shape,especially for the distribution of rolling force between rolls.     

基于动态轧制力的冷轧机两自由度垂直振动特性

考虑冷轧机轧辊在垂直方向上振动位移动态变化的影响,建立了一种动态轧制力模型,在此基础上考虑轧机机械结构振动的影响,推导出含有动态轧制力的轧机辊系两自由度非线性垂直振动方程,采用多尺度法求解该系统的主共振及内共振幅频特性方程。对轧机实际参数进行仿真,分析了轧机中非线性刚度、阻尼、外扰力等参数变化时的轧机主共振幅频特性以及内共振幅频特性,并研究了轧机工作辊与支承辊的动态分岔特性,发现随着外扰力的变化,轧机辊系均会出现周期、倍周期、混沌运动等一系列复杂的运动状态,并得到了各轧辊出现不同运动状态的条件,为研究抑制轧机振动问题提供了有效的理论参考。     

Analysis of the bending of the rolling material in asymmetrical sheet rolling

In asymmetric rolling the workpiece is often bent to an unexpected shape. Its curvature may be caused by a speed difference, by a lubrication mismatch or a radius difference of the work rolls, and depends on various rolling parameters, such as the ratio of the peripheral velocities of the upper roll and the lower roll, reduction ratio, average radius of the work rolls, initial plate thickness and friction between the rolls and the workpiece. A finite element simulation, which shows the influence of different diameters of the working rolls and of the degree of reduction on the bending of the workpiece, has been performed.