热连轧机轧辊热辊型及冷却制度研究

针对热带钢连轧机由于带钢规格变化(主要指窄料和宽料)导致轧辊热辊型的大幅度波动,对轧辊温度场、热凸度和冷却效应进行了分析。采用有限差分法对轧辊温度场和热凸度进行了数值模拟,计算值和实测值吻合较好。进而应用该模型根据来料规格、压下规程等因素来确定工作辊冷却水轴向分布,为热带钢连轧机工作辊冷却系统的改造提供了可靠依据。     

热连轧机轧辊热凸度变化分析

研究分析了热轧轧辊温度分布及热凸度变化规律。试验结果表明,轧辊的热凸度变化明显受冷却条件及设备的影响,通过对轧机部分冷却集管和水嘴的改造,调整了冷却水在辊面的分布,使轧辊热凸度变化有了显著改善;经过一个轧制生产的周期,轧制带钢卷数与热凸度的变化规律中,F1工作辊的热凸度最大,F6工作辊的热凸度最小。     

热带钢连轧机工作辊温度场和热凸度预报模型

采用一种具有较高精度的样条有限条法对轧制过程中工作辊的温度场和热凸度进行计算和预报。结果证明，该模型理论计算值与现场实测值吻合较好，可以较准确地计算和预报热带钢连轧机工作辊的热凸度。     

热连轧机组轧辊温度场及热辊型

针对热连轧机组轧辊温度场无法精准预测引起的辊耗及板形问题。为了实现轧辊温度场与热辊型的精确预报来减少异常辊耗和避免重大生产事故的发生,运用数值解析的有限差分法和轧辊热传导方程建立了适合于热轧轧辊温度场与热辊型模型,在此模型基础上引入热轧机组的轧辊冷却水智能分段冷却控制系统,充分考虑复杂状态下冷却水的存在和冷却水流速对轧辊温度场与热辊型的直接影响。结合热连轧轧制过程中的设备参数及其工艺特点,同时考虑轧制钢卷数量递增对轧辊温度场和热辊型的循环叠加作用,编写程序将理论计算公式、模拟调控模型与现场实际工艺设备参数相结合作为分析的研究对象。首先通过现场轧辊测温设备对工作辊和支撑辊进行温度测量,并将测得的实际温度分布值与模型计算值进行对比分析,得到相近的轧辊温度和轧辊凸度变化趋势以及一致的温度和凸度数值,验证了模型计算的准确性和有效性。随后根据结果进行研究分析,得到了钢卷数量变化对轧辊温度和辊凸度的影响,发现了钢卷数增加对温升的叠加影响,同时发现10卷左右将会完成轧辊温度场的温升稳定,同时分析得出冷却水流速在3种不同速度下的轧辊温度沿辊身方向分布情况。最终实现了对工作辊和支撑辊温度场与热辊型的精确...     

1780热连轧机精轧机组辊型优化技术的设计及应用

根据宁波钢铁1780热连轧机精轧机组采用的"窜辊+辊型+弯辊"的技术方案以及设备特点,以板形和板凸度质量和轧辊使用寿命为前提条件,优化设计精轧机组的轧辊辊型曲线。工作辊采用燕山大学连家创教授VCSW专利辊型,支承辊采用平辊+辊端辊型,根据典型规格产品进行辊型优化设计计算。配合燕山大学设计的板形控制系统,经生产考核,带钢板凸度命中率达到96%以上,带钢平直度良好。     

辊芯差温加热的辊型控制

生产优质均匀的热轧带钢的关键之一是,要求轧机工作辊拥有专门的质量保证体系,以便使轧辊凸度控制在最佳范围内。最近,赫施钢铁公司研究成功一种控制轧辊凸度的新方法-辊芯差温加热法。这一方法已在热轧精轧机组支承辊上投入使用。在常规轧制过程中,所轧制的高温金属对轧辊构成了热源,而冷却水则是吸热剂。一般来说,在热轧带钢轧机上轧制5～7块钢坯后,轧辊温度升高,形成热凸度,办法是通过调节冷却水流量来弥补这种热影响;而在冷轧机上,人们习惯采用变化工艺冷润液控制辊型。此外,也曾讨论过使用差温加热轧辊来控制轧辊凸度的做法。     

轧辊凸度及直径对热轧带钢凸度的影响

为建立高精度的热轧带钢凸度计算数学模型，采用影响函数法开发了带钢凸度影响率计算软件，研究了轧辊凸度及轧辊直径对热轧带钢凸度的影响规律，得出了四辊轧机轧辊凸度影响率基本值的5次多项式拟合系数及工作辊凸度影响率的修正指数，建立了轧辊凸度影响率计算数学模型，为优化板形控制模型参数提供了理论依据。     

二次冷轧机组工作辊温度场与热行为仿真研究

轧辊的热行为,特别是工作辊的热凸度及其变化是带钢轧制过程中的主要干扰因素之一,严重影响到轧制过程中尤其对薄板板形的控制。某厂二次冷轧机组主要生产极薄规格DR材产品,带钢最薄可达0. 1mm,由于该机组非冷连轧机组,轧制过程不连续,每卷带钢轧制间歇期较长,导致轧制区热凸度不稳定,影响生产的产品板形质量,故对该机组轧辊热行为研究是需要解决的重要问题。本文以该机组为研究对象,基于ANSYS有限元仿真软件,建立1#机架大小辊工作模式下工作辊温度场与热凸度有限元仿真模型,计算轧制过程中工作辊温度场和热凸度变化,为辊缝控制精度的补偿控制提供了依据,提高机组产品板形质量。     

铝箔中轧机热凸度的数值模拟

本文能量守恒定律出发建立了铝箔中轧机温度场的差分格式，合理地选择轧制油与轧辊之间对流换热系数沿辊身长度方向上的分布，用李普曼方法求解工作辊辊温度场分布，进而计算了热凸度沿辊身长度的分布。     

四辊轧机上板带钢断面,板形和温度的在线控制系统

由瑞典MEFOS(冶金研究基金会)和斯堪的纳维亚钢厂合作,在一个科研项目中开发了用于钢板(热轧带钢)断面和板形在线控制的计算机程序CROW-N。该控制系统的基础是一些独立的模型,它们用来计算轧辊的弹性变形、工作辊的热膨胀和磨损、钢板内的温度分布。当然也考虑了不同的加热温度、压下规程、轧辊弯曲设备和轧辊冷却速率的分布。除带钢断面和板形外,该程序还计算和提供工作辊内部及钢板厚度方向上的温度分布、工作辊凸度(初始凸度加上热凸度再加上磨损)和工作辊与支持辊之间的负荷分布。该程序已经在钢板轧机上得到了验证。理论计算的钢板凸度和试验所得基本一致,即差小于钢板厚度的±0.5％,计算的钢板表面温度与测量温度之差在±10℃之内。     

Finite element analysis of the temperature profile of rolls

The thermal conditions during hot rolling operations can adversely affect the rolls’ service life and the quality of the rolled product. Analysis of the temperature profile of the rolls is an essential step towards the development of precise cooling systems to minimise their surface deterioration and thermal bending or camber. This paper makes an attempt at developing a finite element model for analysing the steady state temperature profile of rolls of varying dimensions. Rolls of large surface area exhibit greater differences in temperature between the surface and the interior as compared to those having smaller surface area and therefore make greater demands on the cooling system.     

Analysis of Strip Temperature in Hot Rolling Process by Finite Element Method

 The program was developed by finite element method to calculate the temperature distribution in hot strip rolling. The heat transfer coefficient of air cooling, water cooling and thermal resistance between work roll and strip were analyzed. A new heat generate rate model was proposed according to the influence of source current density, work frequency, air gap and distance to edge on induction heating by finite element method (FEM). The heat generate rate was considered into the thermal analysis to predict the temperature distribution in the induction heating. The influence of induction heating on the strip temperature was investigated with different strip thicknesses. The temperature difference became more and more obvious with the increase of thickness. The strip could be heated quickly by the induction heating both in surface and center because of the thermal conductivity and skin effect. The heat loss of radiation has important influence on the surface temperature. The surface temperature could be heated quickly with high frequency when the strip is thicker.     

热连轧轧辊瞬态温度场研究

考虑水冷、空冷、轧辊与轧件接触热传导等动边界条件，采用有限差分法，建立了热连轧轧辊瞬态温度场变步长分析计算模型。该模型能实现轧辊温度场的动态分析和精确计算，预测轧制时以及终轧后空冷的轧辊瞬态温度场。试验和仿真结果表明，所建立的分析计算模型考虑因素全面、合理，计算精度较高，计算值与实测值吻合良好，真实地反映了轧辊的温度变化情况。     

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…     

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。     

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.     

Thermal camber model for hot and cold rolling

The MDS profile and flatness control system is based on many physical part models. The thermal camber model is the only one of these part models which, apart from the spatial dimensions, inherently depends on the time dimension as opposed to part models like roll bending or even roll wear. This means that work roll temperature and shape keep changing even if boundary conditions like water distribution or strip contact stay constant. The exact mathematical solution of the resulting dynamic equations Is a very time consuming task usually not suitable for on-line purposes. Here a new mathematical approach is presented, which solves the 2-dimensional Fourier heat conduction equation with 3-dimensional boundary conditions at a speed suitable for on-line applications. Furthermore an approximate solution of the Hooke stress strain relations is derived, which translates the temperature distribution of the roll into an expansion distribution. This thermal camber model has been implemented in several hot and cold rolling mills. Data collected there show good agreement with the model.     

Measurement of Thermal Load on Working Rolls during Hot Rolling

Work rolls in hot rolling mills are thermally and mechanically loaded; both of these loading aspects are difficult to measure. Laboratory tests can be used for the specification of the thermal load in the cooling area; however a thermal load in a roll gap is still difficult to measure. The paper describes an experimental technique developed for monitoring the work roll surface temperature by sensors embedded in the work roll. Continuous hot rolling pilot line trials were performed for different process conditions. One parameter, for example, roll cooling, rolling velocity, reduction, or skin cooling, can easily be changed during the trials, and the effect on the thermal cycle of the work roll can be directly measured. These thermal measurements give very detailed information about the temperature field. An inverse heat‐conduction model has been developed to compute the surface boundary condition from the measured temperatures. The heat flux and heat transfer coefficient distribution along the roll circumference can be obtained afterwards. The results for different rolling velocities and reductions (up to 50%) are shown.     

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。