FEM analysis of large thermo-deflection of strips being processed in a continuous annealing furnace

No matter what the flatness of a strip is, flat or defective, at an annealing furnace entrance, the strip can not keep its original shape and a remarkable change of its shape can be seen at the annealing furnace exit. By investigating this phenomenon at the 2030 mm continuous annealing line which belonged to Baosteel, a finite element model of thermo-mechanical buckling deformation of strips in a continuous annealing furnace were established, and the mechanism of flatness changing and the contributing factors were researched by the finite element software ANSYS.

Effect of roller shapes on strip buckling in a continuous annealing furnace

The effect of roller shapes on strip buckling in a continuous annealing furnace was focused on. The tensile stress distribution, the transverse compressive stress, and the critical buckling stress of the strip were studied by the finite element method （FEM） when the flat roller, crown roller, single taper roller, and double taper roller were used, respectively. Simulation results show that strip buckling is most likely to occur with the crown roller, then the double taper roller, and finally the single taper roller. Also, strip buckling can not occur when the flat roller is used. Considering strip snaking, the single taper roller and double taper roller are suggested in the continuous annealing fur-nace. The double taper roller with a better strip snaking-prevention ability should be applied in the sections with high strip temperature, and the single taper roller with a better buckling-prevention ability should be used in the sections with low strip temperature.

Numerical simulation and combination optimization of aluminum holding furnace linings based on simulated annealing

To reduce heat loss and save cost, a combination decision model of reverb aluminum holding furnace linings in aluminum casting industry was established based on economic thickness method, and was resolved using simulated annealing. Meanwhile, a three-dimensional mathematical model of aluminum holding furnace linings was developed and integrated with user-defined heat load distribution regime model. The optimal combination was as follows: side wall with 80 mm alumino-silicate fiber felts, 232 mm diatomite brick and 116 mm chamotte brick; top wall with 50 mm clay castables, 110 mm alumino-silicate fiber felts and 200 mm refractory concrete;and bottom wall with 232 mm high-alumina brick, 60 mm clay castables and 68 mm diatomite brick. Lining temperature from high to low was successively bottom wall, side wall, and top wall. Lining temperature gradient in increasing order of magnitude was refractory layer and insulation layer. It was indicated that the results of combination optimization of aluminum holding furnace linings were valid and feasible, and its thermo-physical mechanism and cost characteristics were reasonably revealed.

Enhancement of GMI Effect in Silicon Steels by Furnace Annealing

The ratio and sensitivity of giant magnetoimpedance （GMI） in grain oriented silicon steels （Fe-4.5%Si） are improved after furnace annealing in air for 20 min. By annealing at 800℃, the GMI sensitivity rises from 1.29%/Oe to 1.91%/Oe and the ratio increases from 237% to 294% with decreasing characteristic frequency. The results are attributable to an increase in the transverse magnetic permeability during the heat treatment. From simulation by finite element method, the GMI effect can be interpreted as the modification of the current distribution by the applied magnetic field via the transverse permeability. In the case of annealed samples,the larger transverse permeability allows a higher GMI ratio and sensitivity.

Detection and analysis of gas tightness of continuous annealing furnaces

When a cold rolled strip is being treated in a continuous annealing furnace which is full of protective gas, the gas tightness of the furnace body, the connected facilities and the gas channels become an important indicator that directly affects the product＇s surface quality and shows the technical level of the design, the manufacture and the installation. By considering the problems of the gas tightness of a vertical annealing furnace in the installation and maintenance, this thesis evaluates the gas tightness indicator and gas tightness related level of the furnace body and the circulation duct, while studying and analyzing the technologies of negative-pressure leak detection and sealing.

Application of the waste heat recovery system and energy-saving in the strip continuous annealing furnace

The common problem of cold strip continuous annealing furnaces is high exhaust gas temperature and great energy consumption. Taking the cold-strip continuous annealing furnaces of Baosteel No. 4 cold mill plant as an example, several waste heat recovery systems in the annealing furnaces are compared and their advantages and disadvantages are analyzed through different energy-saving technologies.

Comparison of Poly-Si Thin Films Prepared by Conventional Furnace Annealing and Pulsed Rapid Thermal Annealing

Amorphous silicon films prepared by PECVD on glass substrate were crystallized by conventional furnace annealing(FA) and rapid thermal annealing(RTA),respectively. From the Raman spectra and scanning electronic microscope(SEM),it found that the thin films made by RTA had smooth and perfect structure,while the thin films annealed by FA had a higher degree of structural disorder.

Cause analysis of and solution to furnace roller pick-up in the high strength automotive steel sheet processing line

Cold-rolled high strength steel sheets for automobiles contain more Mn and Si based alloy elements, which, under the reducing atmosphere in the annealing furnace, will get enriched on the strip surface. Since the furnace rollers and the strips contact frequently, alloy elements on the roller surface will form hard protuberance. We call this protuberance ＂pick-up＂. In addition, with the increase of the amount of dust in the furnace atmosphere, the occurrence of furnace roller pick-up will also increase. Through chemical reaction and physical accumulation analysis combined with practical experience, the causes of pick-up in different furnace sections were analyzed. Methods of preventing furnace roller pick-up in the high strength steel sheet processing line were discussed and solutions to improving the strip surface quality in the continous annealing furnace were provided.

Application and practice of regenerative combustion technology on radiant-tube furnace

High Temperature Air Combustion(HTAC) based on regenerative theory has been used in developed countries in recent years,it has many advantages such as efficient recovery of waste heat,high temperature preheating air,low pollution discharge,and so on.This Technology can be used in various furnaces in mechanical,petroleum,chemical industry.To rebuild traditional radiant-tube combustion system with HTAC technology has become important.In the transformation process,The biggest difficulty encountered is that the stability of burner combustion and control system. Because the exhaust gas heat is absorbed by the regenerator,exhaust gas discharge can be controlled at a very low temperature to realize maximum waste heat recovery.At the same time,it improves the temperature uniformity and improve the heating intensity.Thermal efficiency of the device can reach more than 80%.And compared to the traditional air preheating,21.55%energy can be saved. Revamping on traditional radiant-tube combustion system is technically feasible,but a lot of problems will be involved since the rebuild work is on the old system,this article discusses on the main problem encountered in rebuild process in site. to optimize temperature control and obtain not so high exhaust gas temperature,digital combustion control system is necessary.This control loop consists of big loop and small loop,Big loop controls the load distribution of all burners in each heating zone.Small loop controls each heating zone burner's burning time. Compared performance of tradition radiant-tube heater with regenerative radiant-tube heater,result that regenerative radiant-tube heater have many advantage in consume fuel.Accordance with experience of replacing tradition radiant-tube heater with regenerative type,give a proposition in combustion control system, pilot burner,flame detection and prevent trouble to rebuild work of CAPL and CGL. It is recommended to use regenerative combustion technology in new annealing Line.Although the investment is 1/3 much more than the traditional combustion system,the energy saving effect is obvious and operating costs decreases.Revamping can be taken step by step according to different heating zones.Although taking a long time,it is safer and it influences the production less. Regenerative combustion burner revamping has become successful.However,the revamping work on different furnaces,particular on continuous annealing furnace with high request for temperature control,need further exploration and research.

The application of the regenerative combustion technology to a radiant-tube furnace and its practice

This study compares the regenerative radiant-tube heater with the traditional radiant-tube heater, showing the regenerative radiant-tube heaters have many advantages in fuel consumption. Based on the experience of changing a heating system with traditional radiant-tube burners to a heating system with regenerative combustion, propositions are given for the combustion control system, pilot burner, flame detection and for trouble prevention in rebuilding the continuous annealing production line（CAPL） and the continuous galvanizing line（CGL）.

The Inspection of Spheroidized Annealing on SCM435 Cold-Forging Quality Steel Wires with Protective Atmosphere

A cold-forging quality steel rod is usually applied for manufacturing wire which is generally produced by drawing wire coil into wire, followed by spheroidized annealing treatment to achieve the necessary formability for cold forging. The subcritical and intercritical processes are usually used to spheroidize the steel wires. The cold-forging quality SCM435 alloy medium carbon steel wires are widely used to manufacture high tension bolts for mechanical and heavy industry. In this study, the spheroidized annealing experiments on SCM435 alloy steel wires are conducted in a commercial bell furnace with a protective atmosphere of nitrogen or hydrogen. The mechanical properties of annealed steel wires are measured by tensile and Rockwell hardness tests and the process capability is evaluated. It is experimentally revealed that, for SCM435 alloy medium carbon steel wires, the wire quality with intercritical annealing is much better than that with subcritical annealing and is markedly affected by furnace atmospheres. The intercritical annealing quality on SCM435 alloy steel wire in hydrogen atmosphere furnace is better than in nitrogen atmosphere furnace. A comparison between the results obtained using the intercritical annealing with hydrogen atmosphere and the measures using the subcritical annealing shows that the intercritical annealing effectively improves the performance measures of low strength and high ductility over their values at the subcritical annealing. The results presented in this study could be a reference for fasters wire manufacturers.

Characteristic Analysis and Comprehensive Control for the Horizontal Stripes of High-Grade Automotive Panels in Continuous Annealing

As to the horizontal stripes defect which exist on the surface of the high-grade automotive panels in continuous annealing process, an effective comprehensive control method is proposed on the basis of full consideration of the equipment and technological features of continuous annealing line. With five field tests as basis, the generation mechanism of the defect was analysised in detail and the comprehensive control measures were put forward. According to actual situation, a detailed technical plan was worked out .Then the relevant technologies were applied to a 1850 continuous annealing line. The statistics shows that this program acquired good effects. The incidence of horizontal stripes defect decreased from 100% to 2.78%. Meanwhile, the surface quality of strip also improved effectively, which created a larger economic benefit.

硅钢退火炉炉辊炭套结瘤机理研究及解决对策

冷轧硅钢在连续退火炉中进行脱碳、再结晶退火时,炭套辊表面经常出现结瘤,在高温下极易造成带钢产生凹坑缺陷,影响硅钢片的叠装系数,是硅钢成品的致命缺陷。本文通过对硅钢退火炉炉辊炭套结瘤进行深入机理研究分析,并据此提出控制炭套结瘤的解决对策。

安钢冷轧1550 mm连退炉内张力控制与分析

结合安钢冷轧连退机组实际工艺流程,以安钢冷轧1 550 mm连退机组退火炉为研究平台,分析与研究了其炉内带钢张力,这对于薄带钢高速运行低张控制优化具有一定指导意义,可实现冷轧连退薄带钢高效化生产。

中国古代铸铁退火技术研究综述

铸铁退火工艺可显著改善铸铁机械性能,拓展铁器应用范围,在中国古代生铁制钢技术体系中发挥承上启下的作用,是铁器时代开启的重要因素。20世纪50年代开始,自然科学方法的引入让古代钢铁史研究从文献学、类型学跨越到材料学。20世纪80年代,随着铁器考古工作大规模的开展,发现多处大型古代冶铁遗址,再加上一些新兴科技手段与考古研究的深入结合,研究者对古代铸铁退火技术有了充分认识。在冶铁遗址中发现具有退火功能的炉窑,其形制与烘范窑相似。研究者通过模拟古代温度开展实验,借助理论分析汉代球墨铸铁的退火工艺。综合已有研究,宜在最大限度地复原古代的条件下开展铸铁退火模拟实验,从工艺、成本、效果等综合研究古代铸铁退火生产流程,这对加深对铸铁退火工艺的认识有重要的参考价值。

基于BSCWEformer的退火炉内分组式辊速序列预测

退火炉内带钢的长度受到温度、张力等因素的影响而变化,导致辊的转速改变以及焊缝位置的不确定,从而威胁生产安全.为了准确预测辊的转速以计算焊缝的实时位置,本文提出基于带状稀疏柯西自注意力的BSCWEformer (banded sparse Cauchy weight enhanced Transformer)模型.模型采用带状稀疏的、使用基于相对位置计算的柯西分布权重值增强的自注意力结构,在提高相邻输入序列的重要性的同时,将自注意力的复杂度由二次方降低为线性.通过实际生产数据进行实验,并与LogSparse Transformer、Transformer、RNMT+等模型进行对比,得出本文所提出的BSCWEformer模型在退火炉内分组式辊速序列预测任务上具有较高的预测精度.

基于模糊自整定PID算法的退火炉温度调节技术

由于未考虑到退火炉温度偏差值的影响,导致超调量较高,调节效果欠佳。为此,提出基于改进模糊自整定PID算法的真空退火炉温度动态调节技术。依据真空退火炉的工作机理,分析退火炉在工作中的温度变化曲线,采用双曲正切函数求取温度调节过程中的温度偏差值,从而对其动态温度进行设定,采用改进模糊自整定PID算法构造温度模糊控制器,通过对设计的温度模糊控制器内部控制参数进行优化,从而对控制器结构进行更新,并将退火炉的相关参数作为输入量,目标温度作为输出量,由此实现对退火炉温度的动态调节。实例应用结果显示,所提方法可以有效实现对真空退火炉温度的动态调节,且超调量较低,调节效果较好。

基于改进灰狼优化模糊PI的退火炉流量控制系统研究

为解决铝退火炉燃烧过程中空气和燃气流量控制效果不佳,导致空燃比不稳定的问题,提出一种以双交叉限幅、模糊PI控制器及Smith预估器相结合的控制模型,并引入改进灰狼优化算法对双交叉限幅中偏置因子和模糊控制器中的量化因子、比例因子进行寻优的控制方法。首先,通过对双交叉限幅的控制来降低空燃比变化幅度,从而稳定燃烧过程;其次,结合铝退火炉流量系统模型的特点,通过Smith预估器提高系统响应速度,并结合PI和模糊控制的优点,建立模糊PI控制系统模型;然后,利用改进灰狼优化算法的迭代寻优能力,对双交叉限幅偏置因子以及模糊PI量化和比例因子进行优化;最后,以铝退火炉常用的燃气流量30 m3·h-1为例,在Simulink中对所设计的控制模型进行仿真。仿真结果表明,所提出的控制方法无超调量、无振荡,相较于传统的PI控制流量,调节时间有所减少,并且提高了铝退火炉燃烧过程中流量的控制精度。

武钢废钢全流程一体化协同管控系统的建设

随着国家大力推进智慧制造,借助数字化转型来推动钢铁企业废钢管理升级优化,是钢铁企业降低生产成本、实现绿色低碳发展的必然选择。建立了武钢废钢全流程一体化协同管控系统,支撑废钢全流程管控精细化,实现物流、质检、库区岗位操作智能化,建立废钢计划需求及区间配送调度模型,全流程全要素可视化,实现管理岗位决策智慧化。

退火炉氮气用量大的原因与对策

退火炉开启旁冷系统后,炉内氧含量会上升至1.0%~1.5%,而退火工艺要求炉仓内氧含量稳定在0.2%以下,因此需要消耗大量氮气来降低氧含量。经过分析,对旁冷系统加装氮气进气管路,排气管路及相应阀门和传感器等。在旁冷系统开启前充入氮气,排出原有的空气,同时排除氮气流经途径上可能的泄漏。采取这些措施后,每台退火炉每年约降低氮气使用量9763.2 m^(3),同时提高了产品质量。