粗轧镰刀弯调整控制方法

粗轧区域主要任务是为精轧输送板型良好的中间坯。粗轧镰刀弯状态,影响粗轧和精轧的轧制稳定,同时由于镰刀弯的延展性,卷取成卷后容易产生塔型缺陷,影响产品的加工成本,所以提高粗轧镰刀弯命中率,减小粗轧中心线偏移,决定整条生产线轧制稳定性和产品质量。     

粗轧板坯镰刀弯评价系统及因素分析

热轧带钢镰刀弯大小是评价产品质量好坏的重要指标之一,而粗轧中间坯镰刀弯状态直接决定了产品镰刀弯程度。针对梅钢1780热轧产线缺少镰刀弯评价的现状,开发了粗轧板坯镰刀弯评价系统,该系统可客观定量地评价粗轧中间坯的板形质量。通过对比试验定量验证了垂直辊系间隙精度、辊面氧化膜均匀性、阶梯垫表面清洁度等因素对粗轧板坯镰刀弯存在显著影响,通过对这些因素的改进,使粗轧板形得到明显改善,头部中心偏移最大值小于40 mm块数命中率从45%提升至75%。     

热连轧运行非对称测控系统研究与应用

常规热连轧运行非对称主要表现为粗轧镰刀弯和精轧机架间带钢跑偏,粗轧镰刀弯会遗传到精轧机组。热轧运行非对称会造成带钢楔形波动与整体中心线偏移,影响轧制稳定性和产品质量。基于目前的生产现状和需求,本文基于机器视觉技术设计开发热连轧运行非对称检测及控制系统,并成功应用于热连轧生产实践,应用结果表明:该测控系统运行稳定,对粗轧镰刀弯和精轧跑偏能够进行在线检测与控制,检测精度满足使用要求,并能有效减少镰刀弯的产生,降低薄规格产品的甩尾率,提高轧制稳定性。     

热轧带钢跑偏原因分析及控制

针对新钢热轧带钢精轧区跑偏现象,分析了热轧带钢跑偏的原因,指出了粗轧测弯大、精轧区机架间凸度比落差大,带钢对中性差及AGC下压不同步是造成跑偏的主要原因,通过优化粗轧、精轧负荷分配,加强设备维护有效的减少了精轧跑偏所造成的故障时间。     

2800精轧板产生旁弯原因的探讨

一、前言旁弯(俗称镰刀弯)是我厂一种较为常见的板形不良。据抽样估计,万能轧后的钢板约5％有不同程度的旁弯。虽然经圆盘剪或火切纵边后保证了最终产品的平直,但其对产量、质量、成材率及经济效益的影响却不可低估。因为轧制过程中产生旁弯,既增加     

变接触支持辊辊形及辊形配置技术在宽带钢热连轧粗轧机组的应用

迁钢公司2250mm热连轧生产线粗轧后中间坯存在镰刀弯、负凸度和楔形大的板形质量问题,导致精轧控制稳定性差,精轧控制稳定性差是板形控制精度较低的主要原因之一。为此,在粗轧四辊轧机R2机架和粗轧二辊轧机R1机架上设计并应用了6次多项式变接触支持辊辊形和负凸度工作辊辊形,取代了原来采用的平辊形。此支持辊辊形与工作辊辊形配置使用,大幅改善了中间坯的凸度、楔形和镰刀弯等板形质量,使热轧产品板形控制精度提高了10％左右。     

粗轧中间坯镰刀弯在线检测系统的研发与应用

为了解决国内热轧产线粗轧阶段镰刀弯检测精度较差或手段缺失的问题,研发了一种基于机器视觉的粗轧中间坯镰刀弯在线检测系统,系统主要由中间件模块、数据库模块和检测模块组成。在国内某厂1 580 mm热轧产线的稳定运行表明,该检测系统可对粗轧中间坯实时检测,输出中间坯的平面形状与镰刀弯信息,并根据相应的判定规则对镰刀弯进行定性分类与定量表征。根据中间坯中心线实测数据和测宽仪测量数据与系统检测结果对比,可知该系统的检测结果能够反映中间坯的弯曲情况并具有较高的检测精度,可为中间坯镰刀弯的控制提供精确的平面形状数据。     

带钢成品宽度控制研究

带钢粗轧中间坯经常出现头尾超宽、镰刀弯、扣头、翘头等问题,受到设备本身功能限制,单纯地调节工艺参数不能解决问题,且问题持续、反复。本文介绍了以提高粗轧宽度控制精度为主线,采取一系列的自动化控制程序的开发及改进。     

粗轧板坯镰刀弯控制模型的研究与应用

针对经常困扰热轧生产的粗轧板坯镰刀弯缺陷,本文结合弹跳方程和解析法,分析了引起板坯镰刀弯的主要因素——轧机两侧纵向刚度偏差、来料楔形及轧件运行走偏,分别计算了其对应的调整量,建立了基于轧机两侧轧制力差的镰刀弯调平控制模型.该模型可反映轧机两侧纵向刚度差、来料楔形及轧件运行走偏等主要因素与镰刀弯的定量关系,进而计算出控制镰刀弯的粗轧机各道次辊缝倾斜调整值.与现场实测值进行离线验证对比,实测值与计算值比值平均为0.977,结果表明镰刀弯调平模型能够预估板坯各道次辊缝倾斜调整值.将模型投入2250 mm热轧机组使用后,板坯镰刀弯弯曲量未达标率从24.88%下降到6.62%,提高了镰刀弯控制效果,使粗轧板坯镰刀弯问题得到了很大缓解.      

基于粗轧镰刀弯的精轧跑偏预控模型及应用

带钢热轧跑偏问题是影响带钢生产与板形质量的重要因素。轧制生产过程中,由于粗轧中间坯头部弯曲导致的精轧堆钢事故频发,不仅严重危害生产稳定性,还造成资源的严重浪费和企业的经济损失。为了解决上述问题,针对粗轧非对称板形影响因素,结合实测粗轧中间坯以及工艺过程数据,建立中间坯头部预控模型,并利用加权最小二乘法与模型自学习对模型增益系数进行优化,最终建立了基于粗轧镰刀弯的精轧跑偏预控模型。将模型计算值应用于现场生产后,有效降低了精轧带钢头部跑偏,具有较好的参考价值和指导意义。     

带钢热轧粗轧机跑偏控制仿真

带钢在粗轧机轧制过程中 ,由于一些因素的影响使带钢轧机左右两侧轧辊受力不对称 ,导致产生带钢跑偏现象 .轧件的跑偏不仅妨碍生产作业 ,还将导致产品出现质量问题 .为了研究跑偏现象的特征 ,以便精确地调整粗轧机 ,使其在最优工况下工作 ,本文应用Matlab软件对带钢热轧粗轧机跑偏过程的控制进行了仿真 ,得到了经过粗轧机控制后的跑偏量、出口厚度、轧制力的调节过程     

轧辊热凸度模型的修正算法

传统热凸度模型忽略了由轧辊轴向温差造成的径向剪应力的影响,而在接近带钢边部位置的轧辊相邻截面温差较大,此处热凸度计算曲线较实际曲线必然存在偏差。带钢轧制过程中存在跑偏现象,假设带钢偏离轧制中心线按正态分布,结合带钢跑偏对传统模型进行修正,使得在线仿真结果更接近于实际曲线。此模型方法简单,计算快捷,在板带轧机生产实践中具有重要的意义。     

Influence of process variables on development of camber during hot rolling of strip steel

Abstract

Experimental design techniques have been used to study the effects of variations in horizontal scale breaker process parameters in relation to camber generation during the early reduction stages in a hot strip mill. A fractional factorial experiment was designed and performed to identify which process variables are most influential to camber generation. The parameters which emerge from this analysis as being significant are: slab wedge, temperature differentials across the strip width, the deviation of the slab from the mill centreline, and mill tilt. A full factorial experiment was then designed and performed to further investigate these significant process parameters to determine where to set influential and controllable variables so that camber is minimised. The results show that none of the process parameters is significant to camber generation when acting alone; however, they are all significant when combined with one or two other process parameters. This study has enabled a predictive equation to be developed which is able to predict camber to within ±4 mm. This equation may be used in conjunction with mill tilting strategies to reduce camber in the early reduction stages of a hot strip mill.     

Differences between Calculated and Measured Long-Term Deflections in a Prestressed Concrete Girder Bridge

The monitoring of five precast, prestressed bridge girders during fabrication and service provided the opportunity to observe changes in camber over time. These camber variations were compared with corresponding strain and temperature measurements. Each of the girders was cast outside during the winter. As a result, the cold ground acted as a heat sink, and a significant temperature gradient existed during curing of each of the instrumented girders. These temperature gradients are believed to have caused the wide range in the short- and long-term cambers. A procedure to calculate the effect that curing temperatures have on girder camber is presented. In addition, the measured camber values are compared with predicted values using the multiplier method, improved multiplier method, and a detailed time-step method. It was found for the long-span girders that the measured camber values were on average within 10% of the predicted values using the detailed time-step method, but ranged from 22% lower to 27% higher for the simpler methods.     

板坯轧制过程中不对称工艺参数对侧弯的影响

在板坯轧制过程中，由于某些因素的影响，使板坯在粗轧阶段的工艺参数发生变化，如冷却不均匀，使板坯两侧存在温度差、板坯具有楔形及在咬入过程中偏离轧辊中心线等，都会使板坯产生侧弯现象。侧弯将导致板形不良和尺寸精度变差，必须用控制系统加以改善。笔者采用影响函数法对板坯不同厚度和宽度下的侧弯量进行了分析和计算，得出了侧弯量与不对称工艺参数之间的定量关系。     

Mechanism generating deviations in the rolling load and strip camber on the plate rolling mill

Both the support force inequality on both ends of the roll and the camber are common drawbacks, those were caused by the static indeterminacy of structure design, backlash and offset setting selection on the plate rolling mill. There are many technical literatures for analysing the reasons for generating of the strip camber, which are mainly the external factor analysis, however, the internal cause of the mill roll system is ignored. The negative effects of offset distance setting and side clearances of about 1?mm between the chocks and side surface of the housing window should be considered on the plate rolling mill. In reality, the primary cause of this deviation and the strip camber lies in the interaction between offset distance setting and cross of the rolls. The greater the offset setting value of the plate rolling mill, the greater the generation probability of pressure difference and the camber. Some measures, involving eliminating offset distance setting, effectively controlling the side clearances between chocks and housing window, eliminating initial cross and dynamic cross phenomenon, should be taken to maintain the rolls parallel and to prevent radically the support force inequality on both ends of the roll and strip camber.     

轧辊交叉对中间坯镰刀弯生成过程的影响

粗轧过程中出现的轧辊两侧轴承间隙差异较大的情况,会造成轧辊交叉,导致板带两侧轧制力失衡,进而引起或加剧中间坯的镰刀弯缺陷,影响最终产品质量精度和后续精轧的轧制稳定性.为研究轧辊交叉对中间坯镰刀弯生成过程的影响,建立了轧辊交叉、偏移的轧件-辊系耦合动态有限元模型,利用模型分析了不同工况条件下,轧辊交叉位置、交叉角度对中间坯楔形、弯曲量及两侧轧制力差的影响,进而总结了由轴承间隙引起的轧辊非对称交叉对中间坯镰刀弯弯曲量的影响规律.结果表明:镰刀弯弯曲量与交叉角、交叉位置比分别呈线性关系,与辊系间隙比呈二次曲线关系.      

焊接H型钢焊接变形的控制与矫正

提出了在焊接 H型钢焊接制作过程中采取预留收缩量、反变形施焊、制定合理的焊接工艺、预制上拱度等措施以控制变形 ,同时介绍了挠曲变形、拱变形、角变形的矫正方法