Analysis of Temperature Field and Thermal Crown of Roll During Hot Rolling by Simplified FEM

Thermal crown of roll is an important factor, which affects strip profile. It is necessary to analyze the temperature field and thermal crown of roll for hot strip mill. A new simplified finite element method （FEM） was used to analyze the temperature field and thermal crown of roll, and corresponding models were built according to the practical boundary conditions. Transient roll temperature field and thermal crown were simulated by ANSYS FEM software with considering transient thermal contact and complex boundary condition. Temperature and thermal crown variations on roll surface nodes were obtained. The thermal crown results of roll obtained by FEM simulation were in good agreement with the measured data, indicating that simplified FEM models and results were correct.

Numerical simulation and model of control-efficiency of thermal crown of work rolls in cold rolling

Aiming at accuracy control of the thermal crown of work rolls in cold rolling,new parameters such as regulation domain and control-efficiency factors were proposed and a numerical analysis model of the thermal crown of work rolls was established using finite difference method to study roll's thermal deformation.Based on simulation results,the influences of control-efficiency factors on thermal crown are presented and the thermal crown of work rolls is analyzed after taking sub-cooling of sprinkling beam into consideration.It has been found that the control-efficiency factor of any position on the roll's surface is linear function of the temperature and the control ability of water temperature is stronger than other control parameters.In addition,the verification of the model has been carried out based on the producing technology data in some factories and the numerical simulation results coincide well with the experimental data.Therefore,this work has important value for on-line control of roll's crown in cold rolling.

Analysis of the change of roll thermal crown in 1750 mm hot strip mill

Studied the distributing of roll temperature and the change rule of thermal crown in 1 750 hot strip mill,the result of the test showed that the change of roll thermal crown was affected by the condition of roll cooling and equipmentthe roll thermal crown was obviously improved after altering the pipe and water nib of cooling equipment.From the rule of roll thermal crown changing with the number of strip rolling know that the thermal crown of work roll of Standi is the largest,and Stand 6 is the smallest one in a period of rolling.

Thermal Crown Model and Shifting Effect Analysis of Work Roll in Hot Strip Mills

Considering the effect of work roll shifting on roll temperature field,a finite difference method of PR format for roll temperature field was presented,which can meet the requirements of accuracy and speed of online calculation.The step-by-step accumulation method was used to simulate the roll temperature field and thermal crown,and the evolution of roll thermal crown in a rolling campaign was studied.And then,the effects of strip width,rolling rhythm and work roll shifting on roll thermal crown were analyzed.It is found that work roll shifting can disperse the thermal expansion of the roll body especially the edge to make roll thermal contour uniform.The effect of work roll shifting on roll thermal crown is mainly concentrated in regions around twice of roll shifting stroke,and the change range of roll thermal crown is±30μm or so in the same roll body location.

Analysis of the thermal profile of work rolls in the hot strip rolling process

A 2-dimension axisymmetric model was developed by the finite-differencemethod, which can be used to predict the transient temperature field and thermal profile of workrolls in the hot strip rolling process. To demonstrate the accuracy and reliability of the solutiondeveloped, the calculation results were compared with the production data of a 1700 mm hot striprolling mill and good agreement was found between them. The effect of strip width and roll shiftingon the thermal expansion of the work rolls was studied. It is found that the strip width has markedeffect on the efficient thermal crown. Initially, when the rolling strip changes from narrow towide, a bigger efficient thermal crown can be quickly achieved; afterwards, when the rolling stripchanges from wide to narrow, not only the influence of uneven wear can be reduced but also theexcessive efficient thermal crown can be avoided. It is also found that the work roll shifting has adeterminate but not obvious effect on the reduction of the efficient thermal crown, and will makethe strip shape unstable without being used properly.

Wear and Thermal Stress Analysis of Side Dam for Twin Roll Strip Casting

The simulation of the work roll temperature field was carried out by means of ANSYS software, and the thermal crown of the roll along its axis was obtained. The thermal-structural coupled element and contact element were introduced. In the simulation of work roll temperature field, the convert boundary condition and the transient thermal contact between the roll and strip were studied. Besides, the dynamic variation of the work roll temperature and the transient temperature distribution of the work roll during hot rolling were investigated. The calculated results were in good agreement with the measured data.

Enhanced Effect of Montmorillonite on Overall Properties of Polyimide-crown Ether Complex

Organically modified montmorillonite(OMMT) was incorporated into the complex of 18-crown-6(CE) and polyimide-croum ether(PI[CE]), and its effect on the properties of the complex was evaluated in terms of thermal behaviors, coefficient of thermal expansion, mechanical properties, dynamic mechanical properties and water absorption. The results indicate that the overall properties of PI[CE] complex are obviously enhanced. A very low coefficient of thermal expansion of 17.9 ppm/K, a high tensile strength of 124.5 MPa, and toughness of 30.8 MJ/m3 can be achieved for the OMMT/PI[CE] nanocomposite with 3 wt% OMMT. Meanwhile, the thermal stability of the PI[CE] complex is improved, and its 5% weight loss(T_(d5%)) and Tg increase by 10.6 and 23.0 ℃, respectively, and the water absorption rate decreases from 1.73% to 1.13%. The homogeneous dispersion and strong interactions of OMMT with PI[CE] matrix are responsible for the superior properties of the nanocomposites according to SEM and XRD results.

一种液驱冷轧机辊热凸度动态SVR预测模型

辊热凸度是当轧件发生变形或因摩擦作用生成热量而引起轧辊温度上升并由此产生轧辊外形尺寸改变的现象。为了降低液驱冷带轧机辊随温度的变化影响,综合分析了辊热凸度因素引起的变形效果差异性。选择液驱轧机作为测试对象,从热凸度作用原理方面考虑,同时根据实际获得的监测参数探讨了辊热凸度情况受到外部因素的影响程度。建立基于支持向量机的液驱冷带轧机辊热凸度动态预测模型,该模型结构较简单,并且可以获得优异的性能。对于辊热凸度的预测表现出了明显的优势。利用SVR模型以及交叉验证的方式确定参数,结果形成了一致的变化趋势与周期性特征。拟合优度与均方根误差分别为0.84与0.0153,获得了较理想的预测性能。该研究对提高板材的控制精度以及轧机节能具有较好的实际指导意义。

CVC六辊冷轧机轧制3102合金空调箔边紧肋松缺陷控制措施研究

对2300 mm CVC六辊冷轧机轧制3102合金空调箔边紧问题进行分析研究,主要因为轧辊边部散热大,热凸度不均,导致边紧肋松缺陷。通过调整输入宽度,增加板型辊测量环覆盖率,调整前后张力,增大C4和A16板形目标曲线系数,有效改善边紧肋松板形缺陷,并将裂变宽度由10 mm控制到5 mm以内,提高了空调箔坯料成品率。

1700热连轧机轧辊温度场及热凸度研究

研究了国内某1700热连轧机轧辊温度场有限差分模型及热凸度模型,采用C++语言编制离线仿真程序,计算某一轧制周期工作辊温度场及热凸度,得到轧制过程不同时刻工作辊表面温度及热变形情况.F2,F3和F4轧辊上表面在轧制结束后最高温度分别为58.1,73.1和81.2℃;表面最大变形量(半径方向)分别为193.979,275.259和333.433μm.对CVC轧辊而言,轧辊表面温度分布及热变形变化明显受到轧辊横移的影响.将程序计算得到的轧辊表面温度与实测值比较,两者吻合较好,表明轧辊温度场模型及热凸度模型具有较高的计算精度.

轧辊温度场及轴向热凸度有限元计算

采用大型有限元分析软件 ANSYS对四辊轧机工作辊的温度场进行了模拟 ,在模拟过程中 ,考虑了轧辊和轧件间的瞬态热接触和对流边界 ,动态分析了热轧时工作辊的升温过程 ,预测了工作辊的瞬态温度分布 ,并将所得的温度分布用于热凸度的近似计算中 。

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。

超薄快速铸轧机铸轧辊温度场和热凸度仿真及实验

轧辊热凸度是影响板形的一个重要因素 ,其计算精度直接影响到成品的板凸度和板形精度。采用轴对称差分法计算了超薄快速铸轧机铸轧辊温度场和热凸度 ,计算结果与现场测试结果相吻合 。

热轧带钢局部高点产生机理及控制研究

针对迁钢2250mm生产线热轧卷出现局部高点的问题,分析了轧辊辊间接触压力、轧制计划编排、工作辊热凸度等因素对产生带钢局部高点的影响规律,提出了优化末机架工作辊辊型、合理编排轧制计划、严格冷却水喷嘴管理制度、控制轧辊热凸度、调整精轧轧制工艺等措施,改善了轧辊的不均匀磨损程度,使带钢局部高点控制在10μm以下。

连退炉导向辊热凸度对辊形及带钢应力分布的影响

为了更有效地控制连退炉内导向辊热凸度和改善带钢的跑偏及瓢曲变形,以单锥度辊为研究对象,运用MARC有限元软件,定量计算了在加热段和快冷段不同导向辊温差时的导向辊热凸度及其对导向辊辊形和带钢应力分布的影响.研究发现:导向辊热凸度随导向辊温差增大呈直线上升的趋势.在加热段,随着导向辊温差的增大,导向辊产生热凸度后的形状分别为双锥度辊、单锥度辊和"M"型辊,带钢张应力和带钢最大应力分布随着导向辊温差的增大而改变;在快冷段,导向辊产生热凸度后变为双锥度辊,导向辊热凸度会影响带钢张应力值和最大应力值,但不影响其分布.

热带钢连轧机工作辊温度场和热凸度计算

工作辊热凸度是影响热带钢连轧机负载辊缝的一个重要因素，其计算精度直接影响到成品的板凸度和板形精度分．作者采用轴对称隐式差分法，模拟了从开轧一直到轧辊达到热平衡状态的过程，并计算出了稳态后的工作辊温度场及热凸度．

工作辊横移对工作辊温度场及热凸度的影响

采用有限差分的方法 ,计算了四辊轧机在工作辊横移方式下的工作辊温度场及其热凸度 ,并与传统轧制方式下的结果进行了对比和分析 ,为研究工作辊横移方式下的带钢板形提供了参考和依据。

用原始辊型法改善热带板形的工艺研究

采用本城恒模型计算了太原钢铁(集团)有限公司1549mm热连轧机精轧机组工作辊的弹性变形,并用二维模型计算了其热凸度。在此基础上确定了精轧机组工作辊宜采用的原始辊型。生产实践表明,该辊型能明显改善热轧带钢的板形质量。

热连轧机工作辊热辊形仿真研究

采用差分法建立了轧辊二维瞬态温度场及热辊形的预报模型 ,可用于实际生产的在线热辊形预报 ;利用实际生产参数模拟轧制和空冷过程中的工作辊热辊形 ,计算结果与实测值相符 ;就不同条件下工作辊热变形规律进行了分析 ,对热轧生产的工艺安排。

2种粘结剂及粘结方法对CAD/CAM全瓷冠抗折强度的影响

目的研究不同粘结方法及冷热循环对Cerec全瓷冠粘结后抗折强度的影响。方法选择离体前磨牙80颗，进行Cerec全瓷冠预备及制作。随机分为1～4组，每组20颗，分别使用Variolink N树脂粘结剂＋硅烷偶联剂粘结、Variolink N树脂粘结剂粘结、BiscoChoice 2树脂粘结剂＋硅烷偶联剂粘结、BiscoChoice 2树脂粘结剂粘结；每组再分为A、B小组，分别不进行和进行冷热循环。8组试件均用万能力学实验机测试其全瓷冠最大抗折裂强度，观察所有标本粘结破坏形式；进行统计分析。结果使用Variolink N树脂粘结剂＋硅烷偶联剂组粘结的Cerec全瓷冠抗折裂强度最高；全瓷冠抗折强度A组（非冷热循环）高于B组。差异有统计学意义（P〈0．05）。结论双重固化树脂粘结系统是牙科长石质陶瓷粘结的理想选择，可以获得较高的抗折裂强度。冷热循环降低Cerec全瓷冠抗折裂强度。