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Phillip John McKerrow 《Computers in Industry》1983,4(1):19-30
In the galvanizing process zinc is coated onto the steel strip to inhibit rusting. Excess zinc is used to ensure that the finished product exceeds coating quality standards. Reducing the excess coating to a minimum while maintaining product quality can significantly reduce a company's zinc bill.A computer based coating-mass control system, installed on a galvanizing line, has reduced zinc consumption by thirteen percent, saving in excess of one million dollars annually. The same system has been installed in a zincalume line with similar results.The most significant time constant in the process is the transport delay between coatingmass control and measurement. Feedforward control, using a simple model and a table of adapted constants, compensate for this during major changes in process conditions. Feedback control, using a self-adapting linear incremental model, maintains the coating-mass within range during steady-state conditions. 相似文献
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为寻求连续热镀锌线气刀吹锌过程中带钢上出现锌波纹的原因,采用大涡模拟(Large Eddy Simulation,LES)方法数值求解三维非稳态气刀射流湍流流场,并结合带钢表面的镀锌层厚度的零维预测模型研究锌波纹产生的机理.结果表明,在气刀射流冲击区域两侧有交替成对出现的漩涡,造成带钢表面的压强和切应力周期性波动分布,从而产生锌波纹. 相似文献
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ArcelorMittal’s hot dip galvanizing line at Florange has developed and commissioned its own coating weight control system. This system automatically controls air-knife pressure and position to give a constant and uniform zinc coating in accordance with customer-order specifications through a model-based feedforward controller and two feedback controllers. Moreover, continuous adaptation of the knife-to-strip distance allows a fast and accurate response to process fluctuations under the entire range of operating conditions. Due to speedy acceptance of this system by line operators, large and rapid benefits, i.e. quality improvement and zinc savings, have been achieved immediately after it was put into production. 相似文献
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The structure of a typical computer-based coating mass control system is derived which incorporates feedback and feedforward controllers based on recently developed adaptive mathematical models for the jet stripping process. Using conventional design techniques, three alternative types of feedback control algorithm are invstigated. The ‘pulse-and-wait’ algorithm is recommended for computer control applications due to its ease of implementation. Typical simulation results are presented for a range of strip speeds with and without errors in the model parameters. Emphasis is placed on the need to adjust some of the controller settings as a function of process conditions. A computer control system based on the previously outlined concepts has been commissioned on a modern continuous galvanizing line operating at speeds up to 170 m/min. Typical results are given illustrating the improvements achieved from manual and automatic control after the installation of a coating mass gauge. 相似文献
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This contribution takes the control performance monitoring (CPM) technology into a new industrial area, the metal processing, where not much work has been done before. It is shown how to explore not yet discovered opportunities for controller performance improvement in this industrially interesting field, where special aspects have to be considered. This includes online vs. batch-wise performance evaluation, time-based vs. length-based assessment, and oscillation diagnosis. The paper presents two industrial case studies of the performance evaluation of control systems in a tandem cold rolling mill: (1) a feedforward/feedback strip thickness controller; and (2) an internal model control of the strip flatness. Routine operating data are analysed to obtain the performance monitoring metrics in terms of minimum variance index, oscillation index, and to suggest improvement measures. A monitoring tool for calculating and displaying the performance indices has been developed, and tailored to the applications in this field. The results indicate that tuning the feedback thickness controller is suggested to better handle entry thickness disturbances for specific coils. The performance of the flatness controller is found to be satisfactory, thus no actions are needed. 相似文献
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《Real》1999,5(1):35-47
This paper describes the development of a flatness inspection system, integrated in the control process of a hot strip mill in the steel industry. The objective of the system is to calculate flatness indexes for every strip, comparing the length of its lateral profiles with the central length. The reconstruction of the profiles is based on a nonlinear triangulation technique. Images of the steel strip, at high temperature and high speed, are sampled every 2 ms at five different points and are processed on-line in order to calculate height displacement values of the strip, which allows the calculation of final flatness indexes for the steel strip. The measurement method developed introduces an innovative geometry in the disposition of the optical elements which increases the measurement range without reducing precision. It also includes a tracking system to compensate for the effects of lateral displacements of the strip. The flatness inspection system has been implemented using a heterogeneous distributed computer system. 相似文献
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在镀锌生产线中垂直带钢水平晃动会造成镀层不均。基于磁悬浮技术能够实现无接触稳定的特点,研制了用于带钢防抖的磁悬浮系统。分析建立了系统的数学模型,设计了PID控制器。研究设计了包括传感器、控制器、功率放大器的磁悬浮电控系统。在模拟试验台上对系统的性能进行了试验研究。通过试验证明了该磁悬浮系统能够稳定地悬浮带钢,减小带钢在外力扰动下的振幅和回到稳态所需的调节时间,并且在激振试验中成功地使带钢的振幅减小了71.4%。 相似文献
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基于递阶遗传算法的RBF神经元网络板形板厚综合控制 总被引:4,自引:0,他引:4
该文首先用递阶遗传算法(HGA)设计RBF神经网络,不仅可以同时确定网络参数(连接权、隐节点中心和宽度),而且解决了网络拓扑结构的优化训练问题,而后针对板带材轧制是一个复杂的非线性过程,板形控制(AFC)和板厚控制(AGC)又是相互耦合的一个综合系统等特点,建立了基于过程最优的权值在线自学习算法的RBF神经元网络的板形板厚多变量综合控制系统,仿真结果证明了此AFC-AGC控制系统具有良好的自适应跟随和抗扰性能,其控制效果优于传统的解耦PID控制。 相似文献
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带钢连续热镀锌退火过程的模型化 总被引:6,自引:1,他引:5
针对大型冷轧带钢连续热镀锌退火过程的模型化和控制难题,本文以目前国内最先进的宝钢热镀锌生产线为对象,建立了用于实进控制的两类新疑数学模型,带温分布模型和带温跟踪模型,仿真和工业运行效果良好。 相似文献
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在热轧带钢生产线上,卷取温度的精确控制对带钢质量是至关重要的。详细研究了一个实际的热轧带钢卷取温度控制系统。建立了一种简化的动态控制模型,并用一个改进的遗传算法在线调整模型的参数。基于该模型提出了一个包括冷却反馈控制、前馈及自适应联合控制算法的控制器。通过建立一个更精确的仿真系统,达到指导现场生产的目的。实践结果证明提出的控制方法是有效的,仿真系统也具有较大的实际意义。 相似文献
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热连轧机厚度最优前馈控制研究 总被引:1,自引:0,他引:1
热连轧机前馈控制是减小带钢厚度公差的有效方法。本文采用前机架带AGC的厚差预报和贝尔曼动态规划最优控制方案,在本钢1700mm热连轧机上实验成功。文中对交馈系统做了深入的分析研究,提出参数选择原则和方法。 相似文献
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A free piston engine removes the mechanical constraint on the piston motion by eliminating the crankshaft. The extra degree of freedom offers many advantages for reducing fuel consumption and emissions. Nevertheless, stability and robustness of the engine operation has been affected in the meantime. To ensure smooth engine operation, an active motion controller, which utilizes robust repetitive control, was developed previously to regulate the piston motion of a hydraulic free piston engine to track pre-defined trajectories. However, the long piston stroke length, high operating frequency and system nonlinearity impose challenges to precise piston motion control. Therefore, feedforward controllers are investigated in this paper to complement the repetitive control to further improve the tracking performance. The first feedforward design involves the inversion of a linear plant model that describes the dynamics of the engine operation, and the second design is based on the flatness approach, which involves the inversion of a nonlinear model of the system. The two feedforward controllers are designed and implemented on the free piston engine. The experimental and simulation results demonstrate the effectiveness of the proposed control under various operating conditions and reference piston trajectories. 相似文献