超宽轧机对不同宽度带钢板形调控特性分析

为分析某2 250 mm热连轧机针对不同宽度带钢的板形调控特性,建立了该轧机下游机架的有限元模型,利用模型计算出下游机架对于不同带钢宽度的板形调控特性.结合现场实际数据验证了模型精度.对现场数据分析后指出当前弯辊力设定范围过小、下游机架的CVC辊形的等效凸度不合理.研究结果可为现场板形控制与辊形改进提供理论支持.     

热轧窄带钢四辊轧机工作辊轴向窜动的原因及解决办法

对马钢400热带轧机的窜辊问题进行了分析,得出窜辊现象与轧制工艺、轧辊装配等因素有关,进而探讨了相应的改进措施.     

WRS轧机工作辊横移方案及辊系变形研究

WRS轧机是一种板形调控能力较强的新型轧机.分析计算了不同工况下工作辊的磨损曲线并确定了最佳横移方案,同时对给定工况下的辊系变形进行了仿真计算.     

热轧工作辊和中厚板工作辊使用的注意事项

除了加强轧辊的使用检测和对相关参数加强分析以外，还应该注意以下几个方面的问题：     

弯辊和串辊对带钢板形影响

基于有限元软件ANSYS建立了冷轧六辊轧机的三维弹塑性有限元参数化模型。将轧机实体模型转换成有限元模型,根据轧机的工作方式提炼出边界条件和载荷条件,施加在有限元模型上。参数化模型采用ANSYS参数化设计语言APDL编写。通过修改程序中的参数,计算分析了弯辊力、中间辊的串辊量以及带钢宽度等参数对带钢形状和辊缝的影响。计算结果表明:当带钢宽度小于1 300 mm时,调整弯辊力对带钢板形的改变较为明显;当带钢宽度大于1 700 mm时,调整弯辊力对改变带钢板形的作用变得非常小,此时通过连续可变凸度轧辊（CVC）的串辊来调节板形更有效。该结论与冷轧厂实践结论一致。     

VC辊平整机板形调控性能的研究

以某厂连续退火平整机为研究对象,利用ANSYS有限元软件建立VC辊系静力学仿真模型,并研究了弯辊力、VC辊油压、轧辊辊径和辊套厚度对连续退火平整机板形控制能力的影响。结果表明,无论内、外弯辊如何配合,都不能达到只改变四次凸度的目的,不可能只通过内、外弯辊的配合来消除高次浪形;外弯辊的调控功效比内弯辊增大42%;VC辊油压的调控效果主要体现在二次凸度的改变上,改变油压后对四次凸度的影响不大;当VC辊承载时,油压不能始终保持辊套向外涨,承载时辊套可能发生反弯,向芯辊内凹陷;与大辊径相比,小辊径弯辊和油压的调控效果会增加,但辊缝横向刚度会降低;辊套壁厚的减小会使VC辊油压的调控能力有所提高。     

热轧辊材料高温滑动磨损特征

本文利用自制的高温磨损装置,研究了高铬铸铁、中Ni—Cr冷硬铸铁、165CrNiMo及9Cr2钢热轧辊材料的高温滑动磨损特征。结果表明,摩擦面呈现犁沟或粘着特征,或同时具有犁沟和粘着;摩擦面亚表层显微组织磨损前后未发生变化,但165CrNiMo及9Cr2钢中产生了塑性变形。根据犁沟特征,高铬铸铁及中Ni-Cr冷硬铸铁中的共晶碳化物能提高高温磨粒磨损抗力。     

UC轧机中间辊非对称弯辊改善辊间压力分布

为了改善UC轧机辊间压力不均匀分布问题,采用中间辊非对称弯辊系统替代原有对称弯辊系统.应用影响函数法计算辊系变形,同时考虑辊缝中金属横向流动对带钢出口张力横向分布的影响,通过迭代方法计算出中间辊两端施加不同弯辊力后的辊间压力分布、出口厚度横向分布与出口张力横向分布.理论分析和实际应用结果表明,中间辊非对称弯辊可以改善辊间压力分布不均,降低轧辊磨损和减少轧辊辊面剥落,且不会影响成品带钢的厚度和板形.     

四辊冷轧机基于机理与工况相结合的工作辊磨损模型研究

在大量的现场试验与理论研究的基础上,充分考虑到冷轧生产过程中的设备与工艺特点,将磨损机理与轧制过程中实际磨损数据的测量结果有机结合,建立了一套既考虑机理又考虑工况、不但适用于对称磨损而且适用于不对称磨损的工作辊预报模型,并将其应用到宝钢冷轧薄板厂1220五机架冷连轧机的生产实践,有效的保证了工作辊磨损的预报精度,为辊型设计、板形控制奠定了坚实的理论基础,提高了产品的板形质量,为企业创造了较大的经济效益,具有进一步推广应用的价值。     

Roll wear on finishing trains of ASP1700 hot strip mills

A great deal of research and practical production indicated that a perfect shape control system needs a precise prediction model of roll wear. According to the practical wear curve of work roll in Angang ASP1700 hot strip mill, which was measured by a roll-profilemeter, the model of wear curve caused by one single strip was estabfished. The prediction of work-roll wear was achieved by combining Fortran language and practical technology parameters. The calculated results agreed well with the measured.     

Improvement on strip flatness of cold temper mills by modifying roll contour shape

A study on roll gap profile (strip profile) control was accomplished in a 1700 mm single-stand temper mill. Some critical problems such as the deviation of work roll contour caused by grinding and wear, the effectiveness of work roll bending were discussed. Using a finite element model, the effects of roll contours (ground and wear) on strip profile were investigated. The roll bending effect on strip thickness was also analyzed. It is pointed out that there are some special features of flatness control in the temper mill: during temper rolling, roll deformation is slight due to small rolling load, and the loaded roll gap profile mainly depends on work roll contour, while the backup roll has a little effect on gap crown; the effect of bending force on gauge can not be ignored due to the coupling between flatness control and gauge control. A new roll contour arrangement adaptable to the mill was presented and has been put into practical production. The application of the new set of rolls showed some good results: larger crown control range of work roll bender, higher rolling stability, better strip profile and flatness quality.     

Comprehensive contour prediction model of work rolls in hot wide strip mill

The predictive calculation of comprehensive contour of work rolls in the on-line strip shape control model during hot rolling consists of two important parts of wear contour calculation and thermal contour calculation, which have a direct influence on the ac- curacy of shape control. A statistical wear model and a finite difference thermal contour model of work rolls were described. The comprehensive contour is the equivalence treatment of the sum of grinding, wear, and thermal contours. This comprehensive contour calculation model has been applied successfully in the real on-line strip shape control model. Its high precision has been proved through the large amounts of actual roll profile measurements and theoretical analyses. The hit rates (percent of shape index satisfying re- quirement) of crown and head flatness of the strips rolled, by using the shape control model, which includes the comprehensive contour calculation model, have about 16% and 10% increase respectively, compared to those of strips rolled by using manual operation.     

Roll shifting strategy with varying stroke and step in hot strip mill

A new roll shifting strategy with varying stroke and varying step was investigated. Two characteristic parameters including cat ear height and gap contour smoothness were introduced to assess the effect of shifting strategy on roll wear, and the relation between characteristic parameters and shifting strategy was established. Both varying stroke and varying step can reduce cat ear height and gap contour smoothness, so the shifting strategy with varying stroke and varying step is better than the one with either varying stroke or varying step. Based on the effect of shifting control parameters on characteristic parameters of roll wear, the selection principle of these shifting control parameters was gained. A case study was conducted to validate the proposed roll shifting strategy, reducing uncontrollable quartic loading gap contour, improving strip profile and extending rolling length of a rolling campaign.     

Backup roll contour of a SmartCrown tandem cold rolling mill

SmartCrown was a new system developed by VAI for improving the strip profile and flatness control first applied in 1700mm tandem cold rolling mills at Wuhan Iron & Steel (Group) Corporation (WISCO). After tracing and testing, the application of the conventional crown backup roll matching the SmartCrown work roll of the production mill led to heavy and nonuniform wear, and the edge spalling of the backup roll often occurred. A 3-dimension finite element model of roll stacks was established, which was used to analyze the above-mentioned problems, and it was found that the main reason was the highly nonuniform contact pressure distribution between the work roll and the backup roll. A new FSR (flexible shape backup roll) was developed and applied in 1700mm tandem cold rolling mills. A lot of good actual effects of FSR, such as evident improvement in profile and flatness of strips,non-occurring edge spalling, wear uniform, and remarkable decrease in roll consumption were validated by long-term industrial applications.     

Application of simulated annealing algorithm to improve work roll wear model in plate mills

Employing Simulated Annealing Alorithm(SAA) and many mesured data,a calculation model of work roll wear was built in the 2800mm 4-high mill of Wuhan Iron and Stell(Group)Co.(WISCO).The model was a semi-theory practical formula,Its pattern and magnitude were still hardly defined with classical optimization methods.But the problem could be resolved by SAA.It was pretty high precision to predict the values for the wear profiles of work roll in a rolling unit.After one-year application,the results show that the model is feasible in engineering,and it can be applied to predict the wear profiles of work roll in other mills.