基于变约束规划模型的炼钢连铸动态调度

针对炼钢连铸生产过程中时常出现各种扰动, 采用人工调度存在反应慢、调度结果不优化的问题, 在分析各种调整方式基础上, 建立了在线调整非线性规划模型, 通过约束变化满足不同的调整方式要求, 并将模型转化为线性规划模型后对其进行求解. 在国内某大型钢厂应用结果表明: 采用该方法在缩短动态调度时间、减少钢水冗余等待时间、提高设备负荷率方面取得显著成效.     

Control of mold level in continuous casting based on a disturbance observer

Regulating molten steel level in continuous casting is difficult because it suffers from various disturbances, among which the bulging disturbance is the most prominent. Moreover, as the casting speed increases in continuous casting, the phase lag due to the system delay increases. To eliminate the bulging disturbance in the presence of system delay, we propose an adaptive sine estimator based disturbance observer and a phase lead adaptive fuzzy controller. We tested the proposed method using a 1:1 scale hardware simulator and confirmed that the method successfully decreased the bulging disturbance effect from the molten steel level.     

Automatic control of casting speed in ingot casting

A microwave casting speed meter and the automatic casting speed control system that uses it have been developed for the bottom pouring process of steel ingots. The microwave meter is based on the Doppler radar technique, and a circuit of period measurement and reciprocal calculation has been developed to make its response time faster. Also it has a function to measure cast height. The automatic system can be regarded as a sampled-data system with an adaptive control function. Outlines of the microwave meter, the control circuit and the method of adaptive control are presented. The relationship of the crack appearance to the casting speed is studied, and programmed patterns of the casting speed have been prepared to reduce cracking. The programmed ‘pattern casting’ has been achieved by the automatic control system, and the surface quality of the ingot has been improved.     

New approaches in microcasting: permanent mold casting and composite casting

For several years, microcasting was based on investment casting. New approaches are now the permanent mold casting and composite casting of micro parts. Casting was performed with aluminum bronze of the type CuAl₁₀Ni₅Fe₄. Permanent mold casting was commenced with steel mold inserts in a lost mold. The development of a band heater enabled the heating of permanent molds inside the casting machine. This shall ensure sufficient form filling of micro cavities. For permanent mold casting micro structured steel molds and graphite molds were used. Composite casting was investigated for surrounding a micro part by melt, and for pouring a metal melt into a micro structured part. In both cases different materials were combined. For metal–ceramic composite casting ZrO₂, Al₂O₃ or Si₃N₄ were used in connection with Al bronze. For metal–metal composite casting Al bronze was cast around steel. First results for both new approaches are presented.     

Iterative learning control of molten steel level in a continuous casting process

In this paper, an iterative learning control (ILC) method is introduced to control molten steel level in a continuous casting process, in the presence of disturbance, noise and initial errors. The general ILC method was originally developed for processes that perform tasks repetitively but it can also be applied to periodic time-domain signals. To propose a more realistic algorithm, an ILC algorithm that consists of a P-type learning rule with a forgetting factor and a switching mechanism is introduced. Then it is proved that the input signal error, the state error and the output error are ultimately bounded in the presence of model uncertainties, periodic bulging disturbances, measurement noises and initial state errors. Computer simulation and experimental results establish the validity of the proposed control method.     

Self-organizing fuzzy controller for the molten steel level control of a twin-roll strip casting process

The twin-roll strip casting process is a steel-strip production method that combines continuous casting and hot rolling process in a single operation. The quality of strip casting process depends on many process parameters, such as molten steel level in the tundish, solidification position and roll gap. Their relationships are complex and the strip casting process has the properties of nonlinear uncertainty and time-varying characteristics. Hence, it is difficult to establish an accurate process model for designing a model-based controller to monitor the strip quality. In this paper, a model-free control strategy is employed to overcome this problem. The self-organizing fuzzy control (SOFC) strategy is developed to control the molten steel level of a strip casting process. It has on-line learning ability and the rule tables can be modified automatically and continuously for responding to the system’s nonlinear and time-varying behaviors. Since this model-free controller has simple control structure and small number of control parameters, it is easy to implement. Simulation results based on semi-experimental system dynamic model and parameters are executed to show the control performance of the proposed intelligent controller.     

Finite element models in the steel industry: Part I: Simulation of flat product manufacturing processes

In this paper we discuss the finite element models that we developed for simulating several processes used for the production of flat steel products (plates and coils). In particular we discuss the modeling of steel continuous casting processes and of hot rolling processes.     

基于Pro/ENGINEER的铁路货车铸钢摇枕数值模拟

为实现铁路货车铸钢摇枕结构工艺性最优的目标,采用Pro/ENGINEER对摇枕铸造实体建模.选择ZCAST数据库中与铸件相近钢种的热物理参数对模型进行数值模拟.数值模拟计算结果显示出摇枕铸件各部位在浇注和凝固过程中的流场、速度场、温度场和时间场,预测铸件在生产过程中可能产生的缺陷.根据数值模拟结果对产品结构设计不合理的区域和工艺设计过程中存在的问题进行改进.实践表明结构和铸造工艺优化后所生产出的铸件质量满足铁路货车铸钢摇枕的要求.     

Online monitoring of steel casting processes using multivariate statistical technologies: From continuous to transitional operations

This paper describes a state-of-the-art online monitoring system using multivariate statistical technologies for continuous steel casting process, which was commissioned at Dofasco’s No. 2 caster to provide consistent indication of process health for caster’s start-up, continuous production and transitional operations. The paper particularly focuses on development of a novel scheme to synchronize process trajectories for monitoring specific transitional operations such as equipment or steel product grade changes. The proposed scheme is demonstrated by several industrial examples with the results showing good detectability of various process abnormalities. With the aid of this fully integrated, innovative monitoring system, Dofasco has generated significant value through improved productivity and reduced maintenance costs.     

M2M技术在钢铁连铸设备MRO协作平台中的应用

自动、实时、准确、详细地获取钢铁连铸设备的信息,是钢铁连铸设备生产线维修、维护和大修MRO协作平台对设备故障预测的关键。针对此平台的需求构建了基于M2M技术的远程数据采集系统。它不仅能够为钢铁企业提供新的数据源,而且能够在一定程度上改进企业的生产和维修流程。     

基于一体化生产的炼钢一连铸批量计划与调度

基于钢铁企业一体化生产,建立了炼钢—连铸区段炉次和浇次批量计划模型,并通过禁忌搜索算法对模型进行了求解.之后,归纳出了A钢厂3座转炉、6台精炼设备(双工位RH设备3台,CAS设备2台,双环LF设备1台)、3台连铸机流程配置下静态调度的基本原则.最后,提出了一体化生产下炼钢—连铸区段动态调度的策略,并采用规则、算法、数学模型与人机交互相结合的方法解决炼钢一连铸动态调度问题,仿真实验结果表明了此方法的可行性.     

PLC在大功率等离子体炬控制中的应用

连铸技术在钢的生产过程中得到了广泛使用，为了提高铸坯质量，降低转炉出钢温度，提高钢收得率与连铸速度，有必要对连铸中包钢水进行调温控制，实现低过程度恒温浇注。对连铸中包钢水加热的首选方式是等离子体炬加热，本文介绍了这一装置及PLC在其控制系统中的应用。     

全自动钢板抛丸清理系统的研制

针对钢板抛丸清理时各钢板锈蚀程度不同、弹丸流量难于掌控等现状,研制了全自动钢板抛丸清理新系统,提出了系统的总体方案,并对控制系统进行了设计。系统采用工控机做上位监控机,PLC做下位实时控制机,采用智能算法,实时控制弹丸流量,达到抛丸清理的最佳效果。系统运行稳定可靠,操作简便,有一定推广价值。     

Gray-box modeling for prediction and control of molten steel temperature in tundish

To realize stable production in the steel industry, it is important to control molten steel temperature in a continuous casting process. The present work aims to provide a general framework of gray-box modeling and to develop a gray-box model that predicts and controls molten steel temperature in a tundish (TD temp) with high accuracy. Since the adopted first-principle model (physical model) cannot accurately describe uncertainties such as degradation of ladles, their overall heat transfer coefficient, which is a parameter in the first-principle model, is optimized for each past batch separately, then the parameter is modeled as a function of process variables through a statistical modeling method, random forests. Such a model is termed as a serial gray-box model. Prediction errors of the first-principle model or the serial gray-box model can be compensated by using another statistical model; this approach derives a parallel gray-box model or a combined gray-box model. In addition, the developed gray-box models are used to determine the optimal molten steel temperature in the Ruhrstahl–Heraeus degassing process from the target TD temp, since the continuous casting process has no manipulated variable to directly control TD temp. The proposed modeling and control strategy is validated through its application to real operation data at a steel work. The results show that the combined gray-box model achieves the best performance in prediction and control of TD temp and satisfies the requirement for its industrial application.     

宝钢中间包连浇炉数与插铁板关系的探讨

针对尽量提高中间包的连浇炉数,同时降低插铁板的数量,减少连铸生产成本的问题。结合宝钢一连铸实际生产的钢种情况和不同钢种对中间包的使用要求,从生产组织角度上建立了中间包连浇炉数和插铁板次数之间的理论计算关系,得出了在不同生产钢种条件下可以达到的最佳中间包连浇炉数和最佳的插铁板次数,并就插铁板对连浇炉数的影响进行了分析,同时将理论计算和实际结果进行了对比验证,就实际生产组织存在的差距进行了分析。     

炼钢-连铸中作业时间冲突的协调优化方法

炼钢-连铸生产过程中可能因时间扰动导致调度过程出现时间冲突,动态调度后会使得连铸过程出现断浇,从而需要进行拉速与调度的协调优化。针对这2个问题,以断浇时间最小,冗余等待时间最小,连铸机拉速调整时间最小和拉速调整尽量平缓为目标,以生产工艺要求为约束建立数学模型。将模型分为2个部分求解:上层动态调度和连铸机拉速调整。调度部分通过求解简单的线性规划问题可得,拉速优化部分利用极大值原理求得精确解,从实验结果看出该协调优化方法的有效性和优越性。     

Sliding mode control for continuous casting mold oscillatory system driven by servo motor

This paper develops an extended-state-observer-based sliding mode control strategy for continuous casting mold oscillatory system driven by servo motor in the presence of matched and mismatched disturbance. Extended state observers are employed to estimate the compound disturbances, and the requirement of the derivative of the compound disturbances to zero is avoided. In order to counteract the mismatched disturbance and attenuate the chattering phenomenon, a novel sliding surface based on extended state observer is designed for the system. Simulation results illustrate that the proposed controller can achieve better tracking performance and robustness to the compound disturbance.

     

连铸连轧计算机控制系统的设计与实现

连铸连轧系统中的带钢热连轧计算机控制系统是钢铁业乃至所有工业控制系统中最复杂、技术含量最高的计算机控制系统之一。文章介绍了一种应用在珠钢项目上的薄板坯连铸连轧系统的计算机智能控制系统。     

Boundary element stress analysis for copper-based dies in pressure die casting

It has recently been demonstrated that, for pressure die casting, high rates of heat extraction are possible with the use copper–alloyed dies suitably protected with a thermally sprayed steel layer. The structural integrity of dies of this type is paramount as the thermally sprayed layer has the potential to de-bond necessitating repair or retirement of the dies.In this paper, an efficient three-dimensional elastostatic stress model for the pressure die casting process is described. The collocation based boundary element method is used for the prediction of transient stress fields over a thermally stabilised casting cycle. A peculiar feature of the pressure die casting process is that transient thermal penetration into the die is limited to regions close to the surface of the die cavity and nozzle. The presence of a transient thermal field necessitates the evaluation of domain integrals in the boundary element stress formulation. Two methods for evaluating these integrals are presented in the paper: (i) a simplex method on a mesh local to the cavity surface; (ii) a modified reciprocity method utilising Gaussian radial-basis functions, interpolating on a perturbed thermal field. The simplex method is shown to be superior, providing high accuracy, stability and computational efficiency. The dies present a multi-domain environment for stress predictions making it necessary to utilise a suitably constructed coarse preconditioner to enhance numerical stability and provide for efficient computation. A multiplicative Schwarz method is presented that enables parameter matrix accelerated GMRES to be applied on each domain. Numerical experiments are performed to demonstrate the computational effectiveness of the approach. Predicted strain fields are compared with strain gauge measurements obtained on a purpose built rig designed to be representative of the casting process.     

基于SVM算法的薄板坯连铸连轧系统的数学模型研究

连铸连轧系统中的带钢热连轧计算机控制系统是钢铁业乃至所有工业控制系统中最复杂、技术含量最高的计算机控制系统之一,这个控制系统要实现高精度的厚度控制、宽度控制、板形控制、温度控制、层流冷却控制和无头轧制控制等,而实现上述控制的重要基础之一就是建立起轧制生产过程的精确的数学模型。介绍一种应用在珠钢项目上的薄板坯连铸连轧系统的数学模型。