Three-Dimensional Model for Strip Hot Rolling

Steel stripis widely usedin many fields such asautomobile ,building,transportation and householdappliance ,etc·. Withthei mprovement in productiv-ity and automation of strip processing,the require-ments for crown and flatness of strip have been in-creasingly severe ,and“crown free”steel strips arerequired for some special applications such as for au-tomobile parts andtinplate cans .In order toi mprovethe strip quality , an effective three-di mensionalmodel is needful to further study on the…     

面向辊形磨削的热带钢连轧机工作辊热变形研究

热带钢连轧机工作辊下机后尚未完全冷却即进行磨削,残存的不均匀热变形导致磨削的工作辊辊形在空冷一段时间上机时很难达到工艺设定值.针对热辊形不易测量的特点,制定合理的物理测量方式,准确地测量了工作辊下机后的温度分布和热辊形.考虑复杂的工作辊换热边界条件,采用有限差分法对工作辊空冷时的温度场和热变形进行了数值模拟,计算结果与测试结果吻合良好.对工作辊下机后不同时刻的热变形进行仿真,通过将目标上机辊形和磨削时热辊形叠加来设定磨削辊形,为实现合理的辊形磨削提供了依据和计算方法.     

Investigation of thermomechanical behavior of a work roll and of roll life in hot strip rolling

An integrated finite element-based model is presented for the prediction of the steady-state thermomechanical behavior of the roll-strip system and of roll life in hot strip rolling. The model is comprised of basic finite-element models, which are incorporated into an iterative-solution procedure to deal with the interdependence between the thermomechanical behavior of the strip and that of the work roll, which arises from roll-strip contact, as well as with the interdependence between the thermal and mechanical behavior. Comparison is made between the predictions and the measurements to assess solution accuracy. Then, the effect of various process parameters on the detailed aspects of thermomechanical behavior of the work roll and on roll life is investigated via a series of process simulations.     

冷连轧机变接触支承辊板形控制性能研究与应用

通过现场跟踪测试和生产实践发现武钢1700冷连轧机组 "酸轧联机"改造工程中存在常规凸度辊形配置方案不合理,由此引起了薄规格轧制的工作辊"压肩"现象和轧制过程欠稳定导致成品板形质量欠佳等问题.采用二维变厚度有限元方法建立辊系弹性变形仿真模型,研制了酸轧联机条件下的VCR变接触支承辊,经过工业轧机现场轧制已成功投入1700冷连轧机实际应用.现场应用表明:改善了轧机板形调控性能,提高了带钢板形质量,增强了薄规格品种轧制能力,支承辊辊形自保持性较好.     

冷轧工作辊热凸度及其对板形影响

冷轧过程中工作辊的热凸度变化是决定带材板形质量的重要因素,研究分析工作辊的热变形及其对板形的影响对于提高带材质量有着重要的意义.以某厂1 450 mm冷连轧生产线为研究对象,运用大型有限元分析软件ANSYS与LS-DYNA分别建立四机架与五机架的工作辊二维热凸度有限元仿真模型和三维有限元轧制仿真模型,并将2个仿真模型相...     

板带轧制过程多参数耦合模拟系统的开发

考虑轧件和辊系间的接触力与变形协调关系，采用一种选代的方案，开发了一个分析三维板带轧制过程的计算机模型。它耦合了计算轧件变形的三维刚塑性有限元法，计算辊系变形的影响函数法和弹性有限元法。该系统可用来精确预报轧制压力横向分布，前后张力横向分布，金属横向流动，以及轧后板带的横向板厚分布，包括板凸度和边部减薄等，并且具有较高的计算效率。     

冷轧平整机板形问题的特点及对策

对某冷轧厂1700mm单机架平整机的板形问题进行了综合研究，发现该轧机在辊形加工、轧辊磨损及弯辊使用等方面存在的问题，并通过有限元模型研究了辊形对板形的作用，分析了平整上弯辊对板厚的影响，指出平整机板形问题的特殊性。针对平整板形的设备工艺特点，提出了新的辊形配置方案并正式投入生产。结果表明，改进后的辊形配置对降低弯辊调整量、改善板形、提高生产过程稳定性效果显著。     

SmartCrown冷连轧机板形控制新技术改进研究与应用

SmartCrown板形控制新技术在宽带钢冷连轧机首次工业应用中存在SmartCrown工作辊窜辊行程利用不充分、工作辊磨损严重且不均匀等问题.采用ANSYS有限元建立辊系三维有限元模型,分析了辊间压力对磨损辊形的影响.在解析掌握1 700冷连轧机引进的SmartCrown辊形基础上,研究开发出了改进的SmartCrown plus新辊形,经过现场工业试验研究,SmartCrown plus工作辊取得磨削量小,且磨损更均匀化,其辊形自保持性良好的明显效果,现已成功投入1 700大型工业轧机实际应用.     

宝钢150t超高功率直流电弧炉用耐火材料

介绍、讨论了宝钢１５０ｔ超高功率直流电弧炉耐火材料的设计特点,以及投产一年多来的使用情况,并根据操作经验认为：（１）造成泡沫渣埋弧操作非常关键;（２）镁铝尖不石底电极套筒砖性能优越;（３）冷态下底电极套砖接长修补是可行的;（４）采用高钙、低硅,适量的铁的烧结镁砂制成的炕底捣打料性能良好;（５）采用热态修补出钢口技术能大大延长出钢口砖寿命;（６）小炉顶的材质建议采用镁碳砖环状砌筑。     

基于有限元与神经网络的板形调控功效

 针对冷连轧机组中的6辊CVC轧机,利用大型非线性有限元软件MSC.Marc建立仿真模型,对多种轧制条件下轧件的弹塑性变形和辊系的弹性变形进行了耦合计算,得到了6辊CVC冷轧机工作辊弯辊、中间辊弯辊、中间辊横移的板形调控功效离散值。研究了不同轧制工艺参数、轧件参数和轧辊参数对各板形调节机构调控功效的影响规律,并得出相应的板形调控功效系数。以有限元计算结果为样本,利用BP神经网络强大的非线性映射功能,建立了板形调控功效的神经网络计算模型,为板形在线闭环控制模型提供高精度的板形调控功效,解决了有限元计算耗时长,难以满足在线控制要求的问题。     

高精度铜带轧机有载辊缝的调控性能分析

利用非线性有限元软件ABAQUS,将高精度铜带轧机辊系及轧件统一考虑建立有限元模型,分别计算了板宽、轧制力、弯辊力、工作辊凸度变化时高精度铜带轧机轧辊的变形,并得出了上述影响因素变化时对有载辊缝凸度的影响规律,分析了板宽对轧制力影响率、弯辊影响率及工作辊凸度影响率的影响,得出的规律可为高精度铜带轧机的有载辊缝的调控提供科学的依据。     

Roll Wear Evaluation of HSS,HiCr and IC Work Rolls in Hot Strip Mill

While it is acknowledged that roll wear is one of the most challenges to hot strip mills (HSM), very few studies which detail an exact prediction model have been published. The aim of this work is to evaluate and compare two prediction models with measured roll wear. The first prediction model, model 1, developed for a plate mill, was modified to use in strip rolling process. The second prediction model, model 2, is a simplified on‐line model. Data of two hot strip mills were used to investigate the influence of different rolling schedules. The rolls and strip properties were described and the rolling conditions were detailed. The influence of hot rolling factors, such as strip strength, roll grades, rolling temperature, rolling force, reduction and contact length, were also studied. When rolling with different work roll materials and strip grades, the modified prediction model has better prediction accuracy than the simplified model. The accuracy of both models becomes better at higher roll wear > 150 μm. HSS work rolls were confirmed to exhibit improvement of roll wear in comparison with HiCr rolls, the wear resistance was 3 to 4 times better. The influence of strip grade on roll wear was shown to be significant, with higher accuracy of the regression statistics for rolling with similar strip grades and lower regressed accuracy for rolling with mixed strip grades. The roll wear was evaluated at the centre of the barrel.     

极薄带轧制变形区轧辊压扁试验与有限元模拟

 极薄带在轧制及平整过程中,工作辊的弹性压扁对轧制压力的分布有很大影响,传统的轧制力模型已经不再适用。为了在极薄带板形板厚控制过程中得到准确的轧制力,Fleck提出了新的轧辊压扁模型。针对Fleck模型进行试验研究,同时进行有限元模拟分析。试验过程中使用合金工具钢轧辊,轧制不同厚度的轧件,通过显微镜测量变形区各部位的厚度,得到变形区轧辊的近似轮廓形状。试验与有限元模拟结果表明,随着轧件厚度的减小,变形区出现了明显的中性区,但是很难出现Fleck模型中提到的弹性卸载区,因此计算极薄带轧制力时可以忽略中性区内的弹性卸载区以简化轧制力模型。     

Development and Experimental Evaluation of Strip Shape Prediction Model for Sendzimir Rolling Mills

It is difficult to obtain the desired strip shape using Sendzimir rolling mills because small diameter work rolls can be easily deformed by the rolling force. To control the strip shape effectively, it is important to understand the relationship between the behavior of the shape actuator and the variation of the strip shape. A numerical model based on the contact element method was proposed for the prediction of strip shape. In this numerical model, the relationships between the actuating forces, the roll deflections, the thickness profiles of the entry and exit sides, and the strip shape were considered. The proposed numerical model for strip shape prediction was evaluated by computer simulation and experiment with respect to various AS-U roll and first intermediate roll positions.     

多参数耦合下冷轧铝带工作辊分段冷却调节特性

为得到多参数耦合下冷轧铝带工作辊分段冷却调节特性,建立了工作辊和轧件的一体化耦合传热模型.耦合传热建模过程包含工作辊和轧件导热微分方程的建立、轧件变形热和摩擦热的求解、换热边界条件的确立、工作辊热辊形的计算及采用二维交替差分对微分方程进行求解.仿真结果表明,同一轧制参数下工作辊分段冷却正负方向调节能力近似相等,但单向调节幅度受轧制参数影响较大,轧制长度、喷射梁工作压力和摩擦系数的增加对分段冷却调控能力具有促进作用,轧制速度的作用则相反.      

Theoretical Analysis of “Slow Hot Rolling” in Direct Linkage with Thin Slab and Strip Continuous Casting

The present investigation was undertaken in context with the development of the single‐belt strip casting process. In this new process the casting is directly connected to hot rolling which must be carried out at lower speed than in conventional hot rolling to match the casting rate. We have used an integrated thermal/mechanical finite element model to theoretically study the effect of rolling speed on rolling parameters. Since the model is general and the question of “slow hot rolling” is of general interest, the computations were carried out for a wide range of volumetric flow rate extending from that in thin slab casting to that in conventional finishing rolling. The results are given on the influence of rolling speed on roll force, torque, power, temperature change of stock and roll, and roll life. The most important effect of slow hot rolling seems to be the increased heat up of the rolls. This causes an increase of plastic strain in the near surface region of the rolls that will intensify the formation of fatigue cracks.     

适用于六辊UCM轧机中间辊侧向横移变凸度的新辊形研发

六辊轧机是目前生产冷轧、箔轧带材常见的机型,主要有UCM及CVC两种类型。针对UCM类型的六辊轧机在轧制较窄宽度和一般宽度带材过程中、通过中间辊时轴向横移板形控制能力较弱的问题,提出了一种中间辊单侧轴向横移变凸度的新辊形,简称SVC(Side Variable Crown)辊形,由此建立普通六辊和SVC辊形六辊的有限元三维仿真模型。通过模型,分析了SVC辊形空载辊缝调节能力,分别比较了在轧制窄宽度和一般宽度带材的两种辊形中间辊轴向横移时的板形调控能力,发现SVC辊形可增强六辊轧机中、窄带材的板形调控能力,增加了轧机的板形调控手段,同时改善辊间接触压力尖峰,可减轻辊间压痕,提高轧辊的使用寿命。     

A kinematic analytical approach to predict roll force,rolling torque and forward slip in thin hot strip continuous rolling

Abstract

A kinematic analytical approach has been developed to predict the roll force, rolling torque and forward slip in thin hot strip continuous rolling under various rolling conditions. The approach is based on formulating a velocity field in the roll bite zone that expresses the effect of interfacial friction on the distribution of axial velocity and longitudinal stresses across the strip thickness. The results obtained from the proposed approach are in fair agreement with finite element simulation results, whereas available analytical methods, which are usually valid for billets and thick plates, have given considerable error in the results. The proposed approach is applied to study the effect of thickness reduction ratio, coefficient of friction, work roll diameter and front and back tensions on the roll force, rolling torque and forward slip in thin hot strip rolling. The main merit of the proposed analytical approach, as compared to finite element simulation, lies in the drastic reduction in the computational time required in finite element simulation, which favours its use in online control of rolling thin strips.     

CSP末机架支持辊辊形研究

针对CSP热连轧F7机架支持辊辊形高、窜辊分布不合理、轧制薄规格时出口板形易出现中间浪、下机磨损不均匀、磨损严重且CVC趋势比较明显等问题,提出与CSP热连轧工作辊辊形相匹配的支持辊新辊形VCR+,采用二维变厚度有限元模型对新辊形的板形控制性能进行了分析,并且在F7机架上进行工业试验。研究结果表明,新辊形VCR+使用后工作辊窜辊分布更加合理,使得出口板形中间浪问题有了明显的改善;轧辊的自保持性能有了显著的提高,从而延长了轧制公里数,降低了生产成本。     

New Method for Evaluating Thermal Wear of Rolls in Rolling Process

A new method was developed by a thermal wear machine to evaluate the thermal wear of roils in steel rolling process. The steel strip and rolls were simulated by upper and lower heating disks. The upper heating disk could he kept at a temperature of over 900 ℃ by induction heating. The pressure between the disks as high as 323.2 MPa could be achieved and the slipping rate could be 12. 7 %. The thermal wear of high speed steel （HSS） roll material, the wear rate of the HSS roll, and the SEM morphology of a worn HSS roll surface were investigated. This method was useful and could be employed to simulate friction and wear between strip and roll during the strip rolling process.