Computational modeling and control system of continuous casting process

A finite difference model was developed and applied to calculate the temperature distribution and solid shell thickness profile of continuous cast in a steel plant and to control the process of continuous casting. In the developed model, the optimization module of the water distribution of secondary cooling zone was established according to the metallurgical criterion for billet and target temperature controlling principle. The quantitative relation expressions of casting speed and water amount can be regressed by the result data. Meanwhile, the non-linear material properties of specific heat and thermal conductivity as well as phase changes during solidification were considered in the model. The calculated results of the model were in good accordance with measured data in the steel plant. Finally, a continuous casting and control system was developed based on the model. The relations between technology parameters including casting speed, cooling intensity, superheat of melt, and the casting process were analyzed with the system. The system could also be used to predict the optimum process parameters and the water distribution of secondary cooling zone on the new steel grade continuous casting.     

连铸坯的红送

重点介绍了太钢连铸坯红送实施过程中的重要工艺环节、技术及装备,并通过实施后的效果来说明连铸坯红送是一项重要的节能降耗、增产增效工程。     

套类铸钢件凝固特性的数值模拟

用数值模拟法研究了不同壁厚、不同内径的套类铸钢件在普通砂型铸造条件下的凝固时间分布规律和凝固系数的变化,有助于认识此类铸件凝固特性和热节位置,对防止成形过程中产生收缩缺陷十分必要。     

Modelling vertical continuous casting with temperature-dependent material properties

An extension of the analytical model for vertical continuous casting of bars previously developed by the authors (Johnson and Cherukuri. Proc. Roy. Soc. London A 455 (1999) 227) is presented. The new features include temperature dependence of thermal conductivity and the constitutive equations. The model can be used to readily predict the effect of various process parameters such as cooling conditions, liquid pool pressure, casting speed on the solidification process. Consequently, it can be readily implemented in a control system to adjust the process parameters of a typical solidification process. In addition, it can also be used as a guide to gain insight into the nature of the solution prior to conducting more general and expensive finite element simulations.     

Novel technologies for the lost foam casting process

Lost foam casting (LFC) is a green precision casting process categorized as a near net forming technology. Yet, despite its popularity, it still suffers from some technological problems, such as poor filling ability of the castings, coarse and non-dense microstructure, low mechanical properties for the Al and Mg LFC processes, and defective carburization for the low carbon steel LFC process. These drawbacks restrict the development and widespread application of the LFC process. To solve these problems, the present study developed several novel LFC technologies, namely, LFC technologies under vacuum and low pressure, vibration solidification, and pressure solidification conditions; expendable shell casting technology; and preparation technology of bimetallic castings based on the LFC process. The results showed that the LFC under vacuum and low pressure evidently improved the filling ability and solved the oxidization problem of the alloys, which is suitable for producing complex and thinwall castings. The vibration and pressure solidifications increased the compactness of the castings and refined the microstructure, significantly improving the mechanical properties of the castings. The expendable shell casting technology could solve the pore, carburization, and inclusion defects of the traditional LFC method, obtaining castings with acceptable surface quality. Moreover, the Al/Mg and Al/Al bimetallic castings with acceptable metallurgical bonding were successfully fabricated using the LFC process. These proposed novel LFC technologies can solve the current technological issues and promote the technological progress of the LFC process.     

连铸结晶器总成问题研究及设计改进

论述连铸机结晶器总成的设计改进,对结晶器的内冷水套及其结晶铜管的结构部件在使用过程中进行分析调整,使其更具有合理性及适用性.     

Thermal deflection analysis of the solidified shell in continuous casting of slab

The thermal deformation problem in the continuous casting of a slab subjected to thermal loading because of the temperature gradient along the solidified shell thickness is investigated. On the basis of the reciprocal theorem of work or Betti-Maxwell’s reciprocal theorem and the superposition principle, the deflection expressions for a rectangular plate with the two opposite edges simply supported, and the other two opposite edges clamped under the action of the uniformly distributed load and nonuniform temperature field are derived respectively. The meaning of each term in the deflection expression obtained by the reciprocal theorem of work is explained. Then the practical example is given to calculate the thermal deformation and the bulging deformation of the solidified shell under three tension speeds. This research is useful for analyzing the bulging deformation in the continuous casting of a slab under the static pressure of the molten steel and the thermal loading because of the temperature gradient along the solidified shell thickness. Translated from Chinese Journal of Mechanical Engineering, 2006, 42(3): 64–67 [译自: 机械工程学报]     

炼钢大方坯连铸中间包称重装置改造与应用

连铸中间包钢水在线称重装置,用于在冶金炼钢连铸坯浇铸生产中对连铸中间包钢水进行在线称重。该装置构成简便、零部件易于加工、投资小、运行可靠、安装维护方便。具有在称重时承受载荷均匀、稳定,称重准确、快速的特点。本文对炼钢大方坯连铸中间包称重装置的改造与应用情况进行了介绍。     

铸件充型凝固过程的数值模拟研究在国际学术界已占有一席之地

研究了各种铸造条件下缩孔,缩松形成规律及机理,并建立相应判据。提出了定量预测球墨铸铁件缩孔的新方法,即动态收缩膨胀叠加法,并建立了数学模型。根据结晶及相变动力学理论,建立了预测球墨铸铁件铸态组织及机械性能的数学模型。     

塑料薄膜与流延辊换热过程的模拟分析

为实现流延辊辊面温度场的均匀性和稳定性,保证塑料薄膜的高质生产,应用F luent软件对双向回流式螺旋流道的流延辊的换热过程进行了数值模拟;分析了流延膜在流延辊上冷却时的导热、对流、辐射综合的非稳态传热过程,了解了流延膜冷却过程中的传热机理,得出了流延辊内部流道结构、冷却水的流量对流延辊换热强度的影响趋势。研究结果表明,该研究可以为流延辊结构的合理设计、流道参数的优化提供指导。     

基于混合教与学优化算法的炼钢连铸调度

根据炼钢厂的实际生产环境,建立了无等待多工艺路线的炼钢连铸模型,提出一种混合教与学优化算法求解该模型。在混合算法中,引入转换规则的教与学优化算法求解离散问题;采用变邻域搜索调整机器选择,教与学优化算法调整调度顺序的方式,将并行问题串行化。对具体实例进行测试,将人工调度方法、遗传算法、教与学优化和混合教与学优化算法的结果进行比较,验证了所提算法的可行性和有效性。     

连铸辊道冷却系统密封旋转接头泄漏分析

阐述密封旋转接头的工作原理及其失效对系统产生的影响,对密封旋转接头的密封缝隙热变形和机械变形进行分析,也分析了密封旋转接头设计中的重要参数端面比压;同时结合密封旋转接头的结构和现场工况,探讨了泄漏的主要原因,提出解决旋转接头泄漏问题的方法,为提高密封旋转接头的性能提供依据.     

基于脉冲压缩技术的高温连铸坯壳厚度测量EMAT设计及应用

采用非接触电磁超声技术实现高温连铸坯壳厚度测量,实时调整辊压力、冷却喷水量、压下位置和压下速度等工艺参数,避免出现中心偏析和松散问题,具有重要的工程应用价值。为了进一步提高电磁超声换能器(EMAT)在晶粒粗大和表面振痕的高温铸坯中的信噪比和空间分辨率,建立了基于Chirp信号激励的跑道线圈电磁超声检测过程的有限元模型,分析了EMAT设计参数、Chirp信号频宽和脉宽等因素对脉冲压缩后的超声回波信噪比和空间分辨率的影响,并通过实验予以验证。结果表明:经过脉冲压缩后,超声回波的SNR提高19 d B以上,波包宽度减少62. 4%以上; Chirp信号脉宽和永磁体尺寸对信噪比有显著影响,Chirp信号频宽、永磁体间距和宽度、跑道线圈导线直径及其阻抗匹配参数影响空间分辨率。     

伺服电机驱动连铸结晶器振动系统建模与分析

伺服电机驱动连铸结晶器按期望规律振动是一种新型的驱动方式。伺服电机驱动的连铸结晶器振动系统,可避免现有其它方式驱动连铸结晶器振动的不足,具有节能降耗、使用寿命长等优点。为了提高连铸结晶器振动速度或位移的控制精度,保证结晶器振动的平稳性和铸坯质量,建立系统较精确的数学模型是关键。因此,本文首先通过实验研究辨识得到伺服电机转速闭环模型,并推导了机械传动部分的机理模型,从而建立了伺服电机驱动的连铸结晶器振动台系统的数学模型,并给出了一种状态空间表达式;其次,对所建立的模型进行验证,通过相同输入作用下所建模型的仿真输出与实际系统的实测输出的比对,结果表明该模型能较好地反映系统的性能,从而验证了本文所建立模型的有效性;最后对建模误差进行了定量分析,结果表明：模型拟合精度可达94%以上,进一步确认了模型的准确性。所建系统的模型及其误差分析为下一步连铸结晶器位移系统跟踪控制器的设计奠定了良好基础。     

铸件凝固过程数值模拟影响因素研究

对铸件凝固过程数值模拟影响因素及流程进行了研究。并采用华铸和ProCAST软件分别对轴承盖铸件凝固过程进行了分析及软件应用比较。根据凝固模拟的结果及铸造缺陷情况及其与实际浇铸的情况对比,得出了相应的铸型瞬时充满简化假设条件的有效性等结论。     

薄带连铸中CCD液位传感器的快速安装及精确定位技术

介绍薄带连铸CCD（Charge Coupled Device）液位传感器的快速安装及精确定位方法,应用于薄带连铸产业化生产中,以快速度,高精度完成CCD液位传感器的安装,精确地实现对CCD液位传感器预先准确立体标定与校准.这种技术与CCD液位传感器相配套使用,用于钢水液位检测技术,并以较好的方式解决了以后薄带连铸生产中,有关钢水液位检测的成套技术,即新设备加新方法的综合成套使用技术。     

炼钢-连铸智能调度软件的开发及应用

针对大型钢铁企业炼钢-连铸生产调度过程难以控制的问题,将智能优化设定控制策略应用于炼钢-连铸生产调度过程中,将优化调度方法、专家系统、案例推理等技术相结合,研发了集调度计划编制、在线跟踪与调整、人机交互等功能为一体的调度软件。讨论了调度策略、软件的结构和功能,并将所研发的调度软件应用到某大型钢铁联合企业炼钢-连铸生产过程中,取得了显著的成效。工业实验表明,该调度软件具有良好的性能和在工业界广泛应用的前景。     

基于CASTSoft_CAE软件的铸件缺陷预测

以金属凝固理论为基础,I-DEAS和CASTSoft_CAE软件为平台,建立法兰盘凝固过程的三维模型。对法兰盘凝固过程的温度场和凝固过程进行数值模拟,温度最大值出现在法兰盘中心部位,最小值出现在法兰盘边缘。应用新山判据预测铸件可能出现缩孔、缩松等铸造缺陷的位置,发现在法兰盘中心处出现缺陷。     

基于 GPU-CA 异构并行的连铸坯凝固组织软测量模型

铸坯凝固组织结构软测量模型算法复杂,计算量大,求解耗时长,基于中央处理器(CPU)的串行求解方法难以适应大尺寸铸件的预测需求。 为了提高模型的计算效率,提出一种基于图形处理器(GPU)异构并行的元胞自动机(CA)软测量模型。 首先设计 GPU-CA 异构并行算法,消除元胞之间的数据依赖和数据竞争问题,优化数据并行度;其次设计多流任务调度方案,解决单流中独立任务互相等待的问题,提高任务并行度;最后,使用某钢厂大型连铸机生产的两个钢种进行模型测试,预测结果与钢厂实验数据有较高的吻合度,等轴晶率误差约分别为 1% 和 1. 5% ,温度与实测温度的最大相对误差为 1. 37% 。 与 CPU 计算精度相同的情况下,GPU 的计算加速比高达数百倍,极大地提高了模型的计算速度。     

A novel approach to simulate segregation at the centreline of continuously cast steel using laser-scanning confocal microscopy

A concentric solidification technique was employed to simulate the segregation of alloying elements that occur during solidification at the centreline of continuously cast steel. Microstructural development of low carbon steel upon solidification has been observed in situ in a laser-scanning confocal microscope. Sulphide precipitates that formed in the last remaining liquid were identified, and evidence is provided that segregation occurring at the centreline of steel slabs can reasonably be simulated by the use of the concentric solidification technique.