基于扇形段受力预测模型的动态辊缝控制技术

扇形段辊缝的优化设计与控制是连铸生产中的重要工艺。通过有限元仿真及样机实测对扇形段拉杆变形及框架挠度进行评估,分析了浇铸过程中影响扇形段变形主要铸坯反力,提出了基于扇形段受力预测模型的动态辊缝控制方法,实现了扇形段变形动态补偿。生产结果表明,扇形段辊缝控制精度达±0.15 mm,板坯厚度规格满足工艺要求,生产钢种铸坯中心偏析稳定控制在C15/M30以下。     

宽厚板连铸动态轻压下工艺

在工业试验的基础上,对宽厚板连铸机实施动态轻压下后连铸坯中心偏析严重的原因进行了探讨与分析。研究发现：扇形段辊缝实测值与位移传感器测量值之间存在差值,且每个位置差值的偏差较大,导致压下量的实际执行量存在较大偏差,是产生严重中心偏析的重要原因。通过扇形段开口度测量与标定方法的优化改进,将每个扇形段不同位置的辊缝实际值与位移传感器测量值的差值保持在标准差值a,连铸机扇形段的辊缝得到了精确控制,动态轻压下工艺参数得到了精确执行,连铸坯内部质量得到了较大改善。     

连铸机扇形段辊缝控制技术

为满足铸坯规格多样化和提高铸坯产品质量的要求,连铸机扇形段需要具备辊缝自动调节功能。为此,江西新余钢铁公司的厚板坯连铸机使用扇形段辊缝控制技术,通过辊缝折算获得精确的扇形段辊缝反馈,采用位置控制、同步控制和框架变形补偿等方法实现扇形段辊缝的自动控制;同时还通过压力闭环和位置补偿的策略使扇形段的压下力尽量保持平衡,实现"软夹紧"功能,确保设备安全。实际应用效果表明,该辊缝控制技术可以适应多种规格的连铸坯,并能大幅提高产品质量。     

基于压力反馈检测铸坯凝固液芯末端的动态轻压下方法

<正>专利号:ZL201010241895.X专利权人:河北钢铁股份有限公司邯郸分公司本发明涉及基于压力反馈检测铸坯凝固液芯末端的动态轻压下方法,属冶金连铸控制技术领域。首先在连铸机上建立各扇形段远程辊缝自动调节的控制平台,再利用安装在各扇形段上的压力传感器检测结果,计算铸坯在不同扇形段区域所受压力;通过变化各扇形段辊缝收缩大小,检测辊缝变化时各扇形段内铸坯受     

板坯连铸机ASTC动态辊缝精度控制实践

为解决中心偏析、疏松及裂纹对连铸坯表面及内部质量造成的影响及避免连铸机拉坯阻力过大导致的夹坯事故,对连铸机辊缝精度低下的原因进行了分析,提出了解决方法,通过采取控制连铸辊零部件及其装配精度、辊子堆焊表面硬度、提高扇形段维修安装对弧精度、计算并分析在线辊缝校正规律等措施,提高了连铸机产品的质量。     

宝钢分公司4#连铸机的扇形段控制

连铸机扇形段起着支撑和导向铸坯的作用,是在铸坯凝固过程中直接与之接触的设备,对铸坯表面质量和内部质量有很大的影响.扇形段控制的目的主要是使其根据工艺需求确保准确和稳定的辊缝.介绍了宝钢4#板坯连铸机扇形段控制系统的组成和特点,从控制周和位置传感器这两个决定辊缝控制系统稳定和精度的关键点入手,阐述了提高系统稳定性和精确性的措施;最后介绍了利用扇形段控制来优化连铸工艺流程的理论和实践.     

无间隙辊缝调节扇形段的研发及运用

针对三铰链点结构型式扇形段存在的不足之处,研发了无间隙辊缝调节扇形段,并在连铸生产中进行了应用。在研发过程中通过有限元仿真分析和样机的测试,掌握了扇形段强度、刚度及倾动对辊缝精度的影响,并提出补偿措施,达到对扇形段辊缝精确控制的目的。新扇形段辊缝精度较铰链点结构型式扇形段有显著提升,在线辊缝精度达到±0.5mm以内,消除了二冷导向段锯齿形辊缝现象,使辊缝收缩更平滑。在动态轻压下实施过程中,消除了辊缝升降过程中的累计误差,能够对扇形段的弹性变形量进行补偿,对压下量的控制更精确。扇形段在生产中辊缝控制更稳定,维护更方便。     

提高扇形段在线辊缝控制精度影响因素分析及对策研究

针对影响提高扇形段在线辊缝控制精度的问题，分析对比了扇形段的主要几种结构型式及存在的不足，研发出了具有自主知识产权的无间隙辊缝调节扇形段，并在多台板坯连铸机上成功运用。对于扇形段刚度引起的辊缝控制偏差，基于仿真分析与样机测试相结合的方法，获得了扇形段在不同夹紧液压缸压力条件下的弹性变形量，通过该变形量对辊缝进行补偿，提高了在线辊缝控制精度，获得良好的应用效果。对于扇形段不同倾动角度的影响，通过对扇形段在不同倾动角度条件下的受力分析，推导获得了扇形段不同倾动角度与进出口辊缝偏差之间的补偿关系。研究所提出的改进方法对实现扇形段辊缝的在线精准控制具有重要的指导意义。     

板坯凝固收缩与扇形段辊缝优化设计研究

针对炼钢厂铸机扇形段寿命随着高强度钢的生产日益降低的问题,采用数值模拟的方法对铸机浇铸高强钢过程中的铸坯凝固传热和凝固收缩问题进行研究,利用钢种的热膨胀系数对铸坯自由凝固收缩变形行为进行分析。通过计算分析发现钢种的凝固收缩特性与其相变过程的质量密度密切相关,利用铸坯温度场和钢种热收缩特性研究铸坯在铸机扇形段内厚度方向的收缩,优化扇形段辊缝设置。通过调整辊缝调整适应铸坯缩量,减少铸坯对扇形段负载,降低拉坯阻力。通过以上措施的应用,铸机扇形段更换量得到降低,水平段更换量降低了32%,驱动辊扭矩由调整前的25.15%下降到调整后的18.8%。     

SMART／ASTC技术的冶金、操作和经济效果

铸坯锥度自动控制(ASTC)技术与SMART智能扇形段联合实施，通过减轻中心偏析而显著改善连铸坯内部质量。辊缝锥度可以远程调节，借助动态轻压下能够满足在过渡浇铸条件下的特殊要求。SMART／ASTC技术可理想地用于各钢种的板坯和大方坯连铸生产。     

连铸二级扇形段智能控制系统

介绍了鞍钢鲅鱼圈分公司连铸扇形段系统的总体结构。介绍了连铸二级系统动态辊缝控制、轻压下及软夹紧模型的应用。介绍了应用过程控制系统来实现连铸机辊缝的合理设定,从而实现提高板坯质量的目的。     

连铸辊缝仪测量原理及测量图形分析

使用连铸辊缝仪能有效检测连铸机设备状况,确保设备辊列精度处于受控状态,也是检测钢坯质量、探测缺陷的重要环节。根据宝钢罗泾炼钢厂连铸机辊缝仪测量原理及使用情况,结合现场管理实绩,分析设备功能精度管理中辊缝仪测量数据超标现象;以及通过对辊缝测量图形的分析,研究设备冷热态变化、离线对中等因素可能对辊缝开口度超标及弧度偏大的影响。     

直上钢Q235B板坯高拉速下中间裂纹的形成与调控

 基于凝固数值模拟和板坯应变计算分析了直上钢Q235B连铸中间裂纹的形成机理和影响因素，并根据实际生产条件提出了铸坯高拉速质量控制策略。研究发现，辊缝和对中精度为Q235B铸坯中间裂纹形成的主要因素，两者应变之和占凝固前沿总应变60%以上；而表面回温高于50 ℃/m的铸机前段冷却也有重要影响，其应变占比最高约40%。当辊缝的邻辊正偏差为1.5 mm时，通过强化冷却和控制回温可使铸坯凝固前沿总拉应变整体降低约20%；当辊缝的邻辊正偏差为0.5 mm时，冷却优化对凝固前沿拉应变的影响较小。随着拉速增大，辊缝精度对铸坯中间裂纹的影响愈加显著。当前工况下，将锰硫比提高到25,坯壳可最多承受1.4 m/min时邻辊正偏差 1.5 mm、对中偏差±0.5 mm和回温不超过50 ℃/m带来的附加应变。为抑制1.5 m/min以上高拉速下直上钢Q235B铸坯的中间裂纹，建议将辊缝整体精度控制在±0.5 m且邻辊正偏差控制在0.5 mm以内。     

宝钢三铰链点扇形段辊缝间隙控制技术应用

宝钢湛江2 300 mm连铸机由罗泾原2台单流连铸机改造建设而成,由于其扇形段固有的三铰链点结构,实际在线辊缝精度通常超过±2 mm,有时甚至高达±5 mm,不能满足生产要求。根据扇形段辊缝控制原理,通过辊缝折算获得精确的辊缝反馈值,实现对扇形段辊缝的自动控制。对辊缝间隙产生原因进行分析,提出辊缝间隙控制技术。实际应用表明,该辊缝间隙控制技术可以使扇形段辊缝离线和在线精度分别控制在±0.2和±0.5 mm以内,有效保证设备功能精度和状态稳定,为2 300 mm连铸机提高产品质量和发挥产能优势创造有利条件,并对扇形段设计和改造具有一定的借鉴意义。     

Optimisation of pinch roll load in thin slab continuous casting

Abstract

An analytical model has been developed to investigate the optimum pinch roll load and resulting slab thickness reduction during the continuous casting of a steel, constant thickness, thin slab in a vertical type machine. The pinch roll unit consists of two driven pinch roll sets, which support the solidified hot slab weight and take up the reaction forces owing to slab bending. Optimum conditions prevail when the pinch roll load required to support the slab weight is equally shared by the two pinch roll sets and has the minimum value allowing proper control of the slab speed. The model has been validated by being applied to an existing industrial case of thin slab continuous casting of plain low carbon steel. The effects of pinch roll radius, slab thickness, casting speed, slab temperature and the material carbon percentage on minimum pinch roll load and slab thickness reduction ratio have been investigated. Expressions have been obtained for the optimum pinch roll load and slab thickness reduction ratio related to the prevailing process parameters, which the plant operator can directly apply to determine the optimum pressure setting for the hydraulic cylinders fitted to the movable roll ends. The bending roll load is shown to be small compared with the pinch roll load.     

软件控制辊缝对连铸板坯质量的影响

钢铁行业的发展过程中,产品的质量一直以来都是困扰人们的首要问题。自动化控制技术出现后,越来越多的软件控制技术被应用到质量控制当中。计算机软件动态控制板坯连铸机辊缝调节,使得板坯有效避免中心偏析,提高板坯质量。     

板坯连铸实时跟踪动态控制模型的开发与应用

基于耦合多元合金两相区凝固计算的板坯连铸凝固传热数学模型,并采用以恒定间距方式进行离散化的切片单元法开发了板坯连铸实时跟踪动态控制模型CCPS ONLINE.可根据合理的冶金准则并结合铸坯的在线跟踪信息对板坯连铸浇铸过程中的关键工艺参数(二冷水量、扇形段辊缝)进行动态调整,以获得稳定可靠的浇铸工艺条件和良好的铸坯质量.模型已投入工业应用,现场工作表明,其控制算法合理、仿真精度良好,具有较好的可靠性和实用性.     

New approach for prediction of roll force in rod rolling

Abstract

An approximate model is presented in which the equation for computing roll force in an oval-round (or round-oval) pass rolling sequence has been formulated with a new approach. The fundamental idea considered is to introduce the concept of a weak plane strain condition which gives a two-dimensional approximation of the three-dimensional deformation problem in rod or bar rolling. The generality and robustness of the model have been examined by conducting a two-pass low speed bar rolling experiment and a four-pass continuous high speed rod rolling test with various rolling temperatures, roll gaps (pass height), rolling speeds, and steel grades. The predicted roll forces were in good agreement with those experimentally measured, although the prediction was less good when the roll gap (pass height) varied. The proposed model was very fruitful in solving the three-dimensional deformation problem in rod or bar rolling.     

Fundamental phenomena governing heat transfer during rolling

To quantify the effect of roll chilling on the thermal history of a slab during hot rolling, tests were conducted at the Canada Center for Mineral and Energy Technology (CANMET) and at the University of British Columbia (UBC). In these tests, the surface and the interior temperatures of specimens were recorded during rolling using a data acquisition system. The corresponding heat-transfer coefficients in the roll bite were back-calculated by a trial-and-error method using a heat-transfer model. The heat-transfer coefficient was found to increase along the arc of contact and reach a maximum, followed by a decrease, until the exit of the roll bite. Its value was influenced by rolling parameters, such as percent reduction, rolling speed, rolling temperature, material type,etc. It was shown that the heat-transfer coefficient in the roll gap was strongly dependent on the roll pressure, and the effect of different variables on the interfacial heat-transfer coefficient can be related to their influence on pressure. At low mean roll pressure, such as in the case of rolling plain carbon steels at elevated temperature, the maximum heat-transfer coefficient in the roll bite was in the 25 to 35 kW/m² °C range. As the roll pressure increased with lower rolling temperature and higher deformation resistance of stainless steel and microalloyed grades, the maximum heat-transfer coefficient reached a value of 620 kW/m² °C. Obviously, the high pressure improved the contact between the roll and the slab surface, thereby reducing the resistance to heat flow. The mean roll-gap heat-transfer coefficient at the interface was shown to be linearly related to mean roll pressure. This finding is important because it permitted a determination of heat-transfer coefficients applicable to industrial rolling from pilot mill data. Thus, the thermal history of a slab during rough rolling was computed using a model in which the mean heat-transfer coefficient between the roll and the slab was determined from an estimate of the rolling load. It was found that the heat loss of a slab to the roll was 33 pet of the total, which emphasizes the importance of accurately characterizing the heat-transfer coefficient in the roll bite during hot rolling.     

Adhere to the direction of detailization in CC technology and equipment

Since the excessive capacity in steelmaking and continuous casting at present,and the limited development margin of CC technology and equipment in scale,the further development must be made in a profound and detailized way.This paper enumerates the items of CC technology and equipment,which need to be detailized from several aspects such as roll arrangement design,equipment design and production operation,and it points out that detailization is the future direction of CC technology and equipment.The items in roll arrangement design include eliminating periodic meniscus fluctuation by adjusting space between rolls reasonably;taking special measures to avoid dangerous regions of casting speed,in order to reduce the center porosity and centerline crack of slab;optimizing the major radius and the length of outer arc of caster before straightening point to avoid dangerous region of casting speed.The items in equipment design include choosing a suitable structure of support and guiding roll according to the concrete conditions of caster;according to bulging shape of slab,thinking more about restriction of shell to bulging force, discussing the force on rollers,optimizing split roll to support slab;safety factor should be considered together with calculation method of the bearing nominal static load.The items in aspects of continuous casting operation include the delicacy division and the function-positioning of operation modes for CC machine due to the consideration of dynamic soft reduction;monitoring and controlling system of CC machine must be further detailized to improve the stability of production operation and slab quality.In addition to the three aspects mentioned above,this article points out many other items also,such as homogenization of secondary cooling of slab,quality control of surface and internal of slab,and so on.This article emphasizes,some key technologies need to be researched also,and all these researches will never stop.