【作者】 刘栋；

【导师】 李建平； 孙涛；

【作者基本信息】 东北大学 ， 材料加工工程， 2019， 硕士

【摘要】 由于市场对高质量、高性能的钢铁需求量日渐增大,市场中生产的高性能冷轧板已经难以满足市场的需求,因此钢铁企业和相关研究机构亟需一种连续退火模拟实验机对冷轧产品进行研发。和生产线相比,模拟设备不仅能够对加热的温度、时间等进行有效的控制和调节,实验过程灵活性和可操作性较强,还能够有效的降低研究费用,提高研究效果。试样温度控制精度是模拟退火实验机的核心指标之一,以东北大学轧制技术及连轧自动化国家重点实验室为攀钢研究院开发的连续退火模拟实验机为背景,以单片小试样为研究对象,开发了快速加热控制前馈模型,形成了快速热处理实验工艺技术。本文基于典型冷轧带钢连续退火生产工艺特点,在连续模拟退火实验机上完成了针对单片薄带钢试样的快速热处理实验系统的方案架构设计,依据电阻快速加热方法和金属传热学基础理论,重点针对带钢电阻快速加热工艺和温度控制过程稳定性进行了动态计算,通过大量的实验数据优化模型参数,获得了较好的应用效果。具体内容如下:(1)在模拟实验机上采用电阻加热方式对试样进行加热,通过控制可控硅的导通角,进而控制加热变压器原侧电压,调整流通试样的电流实现温度控制。进行了大量加热实验,根据电阻快速加热原理,建立了加热前馈控制数学模型,获得试样相对电阻R1、电缆相对电阻R0、试样的尺寸以及加热速率等参数与前馈控制量U之间的变化关系。(2)将加热前馈控制数学模型应用于连续退火模拟实验机,在实际应用过程中进行参数优化调整,获得了较好的控制精度:升温阶段温度均控制在±5℃之内,拐点温度均能控制在±8℃之内,保温阶段温度均能控制在±3℃之内;四条热电偶的实测温度差小于5℃,温度均匀性较好。(3)通过对比常规PID加热方式和具有前馈模型的组合加热方式,具有前馈模型的组合加热方式具有提前预判功能,在温度曲线拐点处避免了温度曲线的跟不上或超调现象;在适应较大范围的试样宽度、厚度变化和升温速率变化方面具有显著优势,控制系统稳定,温度波动小,稳定性好。(4)在连续退火试验机上进行了多种冷轧带钢试样加热实验研究,采集了大量试验数据,确定试样温度均热区,通过对典型试样温度均热区的均匀分布位置的金相实验观测组织晶粒尺寸和硬度测试,结果表明,80%以上平均晶粒尺寸集中在2～5μm,平均硬度值较为接近,组织和硬度均匀性较为良好。更多还原

【Abstract】 Due to the increasing demand for high-quality and high-performance steel in the market,it is difficult for the high-performance cold-rolled sheet produced in the market to meet the market demand.Therefore steel enterprises and related research institutions urgently need a continuous annealing simulator for the development of cold-rolled products.Compared with the production line,the continuous annealing simulator can not only control and regulate the heating temperature,time,etc.,the experimental process flexibility and operability is strong,but also can effectively reduce the research cost and improve the research effect.The temperature control accuracy of the specimen is one of the core indexes of the continuous annealing simulator,with the continuous annealing simulator developed by the state Key laboratory of Rolling and Automation in Northeastern University as the background,and the single-piece small sample as the research object,developed the rapid heating control feed-forward model,and formed the rapid heat treatment experimental technology.Based on the characteristics of the typical cold-rolled strip steel continuous annealing production process,the design of the scheme structure for the rapid heat treatment experimental system for the single sheet thin strip steel specimen is completed on the continuous annealing simulator,according to the resistance rapid heating method and the basic theory of metal heat transfer.The dynamic calculation of the fast heating process and temperature control process stability of the belt steel resistance is focused on,and optimizes the model parameters through a large number of experimental data,and obtains better application results.The details are as follows:(1)The specimen is heated by resistive heating on the continuous annealing simulator,and the temperature control is achieved by controlling the angle of the silicon controlled rectifier,and then controlling the original side voltage of the heating transformer and adjusting the current of the circulation specimen.According to the principle of rapid heating of resistance,a heating feed-forward control mathematical model was established to obtain the changing relationship between the sample relative resistance R1,cable relative resistance R0,sample size,heating rate and feed forward control quantity.(2)The mathematical model of heating feed-forward control is applied to the continuous annealing simulator,and the parameter optimization adjustment is obtained in the course of practical application,and the control accuracy is obtained:The temperature at the heating stage can be controlled within ±5℃,the temperature at the inflection point can be controlled within±8 ℃,and the temperature at the insulation stage can be controlled within±3℃;The measured temperature difference of four thermocouples is less than 5℃,and the temperature uniformity is good.(3)By comparing the conventional PID heating method with the combined heating method with feed-forward model,it is found that the combined heating method with feed-forward model has the function of early prediction,and avoiding the temperature curve can not keep up or overshoot at the inflection point of the temperature curve;it has obvious advantages in adapting to a wide range of sample width,thickness variation and heating rate change,stable control system,small temperature fluctuation and good stability.(4)A variety of cold-rolled strip steel sample heating experiments were carried out on the continuous annealing simulator,a large amount of test data were collected,and determine the average heat zone for the sample temperature,and the grain size and hardness test of the metallographic test observation organization in the uniform distribution location of the average temperature of the typical sample temperature were tested,and the results showed that the average grain size of more than 80%was concentrated in 2μm-5μm.The average hardness value is relatively close,and the organization and hardness uniformity are good.更多还原