无取向电工钢横向同板差产生的原因及控制方法

新钢冷轧无取向电工钢存在横向同板差偏大的问题,经过试验和分析,采取了以下措施:首先是适当降低无取向电工钢的热轧凸度,将凸度设定为30~40μm;二是降低热轧原料的楔形,将楔形控制在25μm以内;三是冷轧S1和S2机架采用倒角高度0.3~0.5mm的工作辊。通过上述措施,各牌号无取向电工钢的横向同板差不大于10μm的合格率提高到94%以上,取得了较好的效果。     

冷轧卷隆起缺陷分析及改进

为了消除首钢京唐公司冷轧卷的隆起缺陷,从热轧原料、冷轧工艺对冷轧隆起缺陷的原因及控制措施进行了研究。降低冷轧卷隆起缺陷发生率的措施:一是控制热轧卷局部高点的大小;二是提高热轧卷凸度值,控制热轧卷凸度大于楔形;三是优化酸轧第5机架压下率分配;四是降低酸轧卷取张力,隆起缺陷发生率大幅降低。     

冷连轧机组吉帕级高强钢专用中间辊CVC辊形的优化

在吉帕级高强钢的生产过程中,现有的弯辊及窜辊达到最大值时仍无法补偿轧辊的弹性变形。即在原CVC轧辊配型制度下,中间辊窜辊量达到200 mm时,等效凸度仅为0.8 mm,轧机的辊缝凸度调控域不能满足超高强钢板形的控制要求。只有辊缝凸度调控域能够覆盖超高强钢的板形控制需求时,才能解决超高强钢板形不良的问题。本文对超高强钢生产专用中间辊辊形进行技术探索,当窜辊量达到120 mm时,等效凸度就达到了0.8 mm,最大等效凸度为1.075 mm,其凸度调节范围高于国内同类型冷轧厂CVC辊形板形控制能力。通过改进轧辊辊形配置,拓宽了辊缝凸度调控域,凸度调节能力同比提升34.75%,且板形调节响应较快,能较好地弥补常见中间辊辊形在冷轧超高强钢生产过程中板形控制能力不足的问题。超高强钢生产专用中间辊辊形应用后,带钢平直度值由20 IU降低到4 IU以内,板形改善幅度达80%以上。     

带钢起筋现象原因分析与解决措施

针对热轧带钢在下工序冷轧过程中出现的起筋现象,从热轧角度进行分析,从冷轧带钢起筋位置分析出与热轧带钢断面局部高点、凸度和楔形之间的对应关系.通过对热轧工艺参数的调整,实现了带钢断面大凸度、小楔形和适当的局部高点,减少了冷轧带钢起筋现象,改善了产品质量.     

冷轧基板起筋成因分析及控制实践

针对1 450、2 032 mm热连轧线生产的冷轧基板在下游工序出现的批量起筋缺陷，结合两条热轧线的装备控制特点,从板形控制、轧制工艺规范管控的变化对其产生原因和机理进行分析，得出热轧带钢凸度控制失稳是导致起筋的重要原因。通过进行HVC板形控制模型的优化及生产工艺管理制度的调整，实现轧制过程的“均匀变形、板凸度一致”控制，保证带钢断面质量及凸度命中效果，冷轧产品起筋缺陷发生率同比下降95.12%，产品质量得到明显改善。     

提高热连轧板板形质量的方法与措施

通过分析楔形、凸度、平直度等板形控制机理,结合莱钢热连轧工艺装备和板形质量特点,优化原始辊型、换辊周期、负荷分配等工艺,制定出与产品质量相关联的换辊制度、换辊模式、轧制计划安排等控制策略,改善了产品断面形状,板凸度由-20～250μm改善到30～70μm,板形异常卷控制在0.25%以下,薄规格比重提高到总产量的30%～40%。     

1780 mm热连轧厚规格窄断面小凸度控制研究与实践

针对安钢1780 mm热连轧生产线厚规格窄断面带钢凸度控制精度不高的问题,分析了轧制负荷、弯辊力、轧制计划编排、轧辊磨损、带钢边降和楔形对凸度的影响规律.根据分析结果并结合安钢的生产实际,提出了轧制10～16 mm规格的小凸度要求产品时采用直热装,轧制里程限制在50块以内,故障时关闭精轧机架冷却水,改进F2-F4的CV...     

冷轧带钢边鼓治理

介绍了唐山建龙公司冷轧带钢边鼓缺陷的特点,分析认为冷轧产生边鼓的原因主要是受来料板形的影响。通过优化曲线辊辊型和换辊制度、强化轧制过程控制、增大工作辊冷却水压力等措施,冷轧带钢边鼓缺陷降级量明显降低。     

宽薄规格冷硬卷起筋原因分析与改进

介绍了宽薄规格320GD酸轧过程中出现的起筋缺陷的宏观形貌,并分析了热轧原料和冷轧参数对轧制的影响.认为酸轧过程中手动增加正弯辊力、轧机自学习参数设定不合理,导致了窜辊值逐步增大,从而引起带钢中部延伸过大,卷取过程中产生起筋缺陷.通过控制原料凸度和楔形,开发轧制力弯辊力跟随程序,降低冷轧生产过程中各机架弯辊力、4#机架...     

带钢"起筋"成因分析与对策

对热轧带钢在冷轧过程中产生的"起筋"缺陷进行了分析.通过大量统计数据,分析了"起筋"位置、成因、"起筋"卷局部高点、凸度以及楔形之间的关系,并对热轧工艺进行了改进,取得了很好的效果,保证了断面适当的大凸度、小楔形和适当的局部高点,大大降低了带钢"起筋"率,改善了产品质量.     

VCR back-up roll and negative work roll contour design for solving roll spalling and transfer bar profile problems in hot strip mill

Abstract

During the first year of production in the 2250 mm hot strip mill of Qian'an Iron and Steel Company of Shougang Steel Corporation, roll spalling and broken rolls were frequent occurrences, especially on the second stand of roughing mill (R2), and resulted in enormous economic losses. In addition, improvements to strip shape were required. One of the factors resulting in strip shape defects after finish rolling is that the transfer bar usually had an unsound profile such as a large wedge, camber or negative crown after roughing rolling. To solve these problems, a variable contact back-up roll contour curve with six order of polynomials and negative crown contour was designed and applied to the back-up roll and work roll of roughing mill stands R1 and R2 instead of a conventional flat roll contour. After the application, roll spalling, crown and wedge quality of the transfer bar and strip quality all improved.     

冷轧钢卷起筋量的测量及其影响因素的研究

在大量现场试验的基础上，首次提出了“起筋”量的实用测量方法，建立了一套计算“起筋”量的数学模型，同时通过“起筋”量的计算值与现场实测值的对比验证了模型的准确性，并定量分析了局部高点的大小、带材厚度、卷径、卷取张力、粗糙度等因素对“起筋”量的影响，得出了影响“起筋”量的相关规律，为现场“起筋”缺陷的治理提供了坚实的理论基础。     

Nonlinear Spline Finite Element Method for Ribbing of Cold-Rolled Coils

 The ribbing problem has serious influence on the steel product quality, which produces additional shape waves on the surface of uncoiled steel strip on the process of curl. Nonlinear spline finite element method (n-spline FEM) is adopted to establish the relationship between the ribbing height and deflection of additional shape wave, for example, post-buckling deformation. The proposed spline FEM is more effective and convenient than traditional finite element method in the buckling analysis. Using the spline FEM, the shape wave caused by the ribbing is calculated, and then the ribbing values can be obtained which are difficult to measure in practice. At the same time, the judgment rule is also given for estimating the strip quality according to the ribbing value.     

2250mm宽带钢热连轧生产线凸度控制优化

 首钢迁钢2250mm热连轧生产线在达产初期出现了带钢凸度控制稳定性差的问题,甚至出现负凸度现象。对此热轧生产线的生产数据进行了分析,同时对轧辊温度与辊形进行了实际测量。究其原因为CVC辊形对热凸度和磨损辊形较为敏感,工作辊冷却水能力不足引起的轧辊热凸度过大破坏了CVC辊形曲线的板形控制能力。由于改造轧辊冷却水系统费用较高,需要停产,为了解决凸度控制稳定性问题,采用了辊形优化设计的方法。对精轧机组的CVC工作辊辊形进行了优化,空载辊缝凸度调控范围从［－0.7mm,0.7mm］增大到［－1.2mm,12mm］。同时,为了改善CVC工作辊与支撑辊辊间接触状态,设计并应用了CVC支撑辊辊形。此CVC辊形配置解决了首钢迁钢2250mm热轧线凸度控制稳定性差的问题,板形控制精度由原来的67%提高到了93％以上。     

Wedge Anchorage for CFRP Strips

For several decades wedge anchorages have been used with great success for the prestressing of steel strands in civil engineering structures. Due to the anisotropy of carbon fiber-reinforced plastics (CFRP) these wedges are not efficient with CFRP tendons. High lateral and shear stress values develop in the CFRP–wedge interface that lead to a premature failure of the CFRP. A comparison of different anchorage methods corroborates the outstanding advantages of wedge anchorages over other anchoring techniques. To benefit from these advantages, a new wedge design is presented that eliminates the high lateral and shear stress values in the CFRP–wedge interface of conventional wedges. Numerical simulations were performed to show the advantageous lateral and shear stress distributions. Tensile tests on 1.2?mm thick CFRP strips and a bonded CFRP–wedge interface reached ultimate loads higher than the guaranteed tensile load. The tests on 2.5?mm thick CFRP strips were performed with an adhesively bonded wedge–CFRP and a friction only interface. The ultimate loads in the tests were for the adhesively bonded interface 84 and 87% of the guaranteed tensile load, whereas the friction only interface was even able to anchor 93% of the tensile load.     

Large concave roll technology for hot rolled silicon steel

It has a strict demand for the transverse thickness difference of silicon steel. To reduce the transverse thickness difference of the cold rolled strip, it must reduce the crown and the wedge of the hot rolled strip. 7-Stands continuously variable crown (CVC) hot rolling mills are conventionally applied to roll silicon steel. However, the CVC rolling mills have many defects to roll silicon steel as a result of the strict demands for the crown and the wedge and the characteristics of the CVC rolling mill. The large concave roll (LCR) technology was puts forward to solve that problem. The LCR technology includes the design of the roll contour and the roll free shifting strategies. The results of simulations and experiments show that the LCR technology can not only ensure the crown target of silicon steel, but also enlarge the coil quantity in a rolling schedule and improve the hot rolled strip edge-drop in the late of rolling schedule. This technology provides guidance for the crown control of the hot rolled silicon steel.     

横向温度分布对无取向电工钢热轧板形的影响

摘要： 电工钢热轧凸度和楔形难以满足日益增高的板形质量要求。为了揭示横向温度分布对无取向电工钢热轧板形的影响规律,建立了三维弹塑性有限元模型,有限元模型中的带钢材料模型以其热塑性本构模型为依据进行设定。通过有限元仿真计算分别研究了电工钢热轧过程两相区和单相区轧制温度条件下带钢横向温度抛物线分布、边部温度下降和横向温度倾斜分布3种典型温度分布特征对板形的影响规律。研究发现,两相区轧制时,横向温差易引发凸度增大、边降增高等板形问题;单相区轧制时,横向温差则会导致凸度减小甚至下凹、边部翘起等问题;较小的横向温度倾斜分布即会引发巨大的楔形缺陷。电工钢热轧过程应严格控制横向温差,以降低其对板形的不良影响。