Study On Models And Application Of Strip Crown And Shape Online Control For Hot Strip Mill

The crown and shape are important quality indicators of the plate and strip, the crown and shape online control technology is the core technology in plate and strip production, which we have been introduced from abroad for a long time. In this paper, strip crown and shape online control technology is studied, and the industrial applications achieved good results. The research results have an important significance in changing the situation of core technology about hot strip mill, which is depending on introducing from abroad.First, the calculation models of the strip crown and shape are studied. The calculation models include the metal plastic deformation model, the roll elastic deformation model, the roll thermal crown model and wear crown model, which can simulate with considering all kinds of factors. In order to test the correctness and accuracy of the calculation models, we conducted a dynamic simulation of load rolling gap with actual data,strip exit thickness distribution calculated and measured values are in good agreement. The results show that the calculation models have good calculate accuracy, it can establishe a foundation for optimizing the roll shape and studying on online control models of strip crown and shape.Second, roll shape optimization of roll shift 4-H hot strip mill and ordinary 4-H hot strip mill are studied. As the strip crown and shape depending on 3-dimentional deformation in load rolling gap, so, the original roll shape play an important role in online control of the strip crown and shape. Basing on different optimizing targets, we completed the work roll and back-up roll optimization for roll shift 4-H hot strip mill and ordinary 4-H hot strip mill. The patent VCSW which invented by Lian Jiachuang professor of Yanshan university is taken as work roll shape and flat body+edge curve is taken as back-up roll shape for roll shift 4-H hot strip mill. The industrial application show that the rollers have used in good condition, strip crown and shape are well controlled. The optimization results well meet the production requirements, the optimized rollers are used in production. The cosine curve is taken as work roll shape and flat body+edge curve is taken as back-up roll shape for ordinary 4-H hot strip mill. The industrial application show that the exit strip shape was improved, the strip crown achieved the expectation, the fatigue spalling of back-up roll edge was restricted. The optimization results well meet the production requirements, the optimized rollers are used in production.Third, the online control system and mathematical model of the strip crown and shape are studied and the industrial applications is carried out. Integrated online control system is presented based on preset control system, strip bite adaptive control system, bending force adjusting follow the roll force control system, discoupling control system of thickness and shape, closed-loop control system of strip crown and flatness and the self-studing and adaptive system. In this paper, every subsystem and its models are discussed, validated industry applications about preset control system, self-studing and adaptive system and strip crown closed-loop control system. The strip crown closed-loop control system used the BP neural network model. After actual parameters debugging, we have made a examination. The results show that the percentage of strip crown hits is more than 96%, the strip online flatness is good. From the results, we can know that online setting and closed-loop control system and models have good adaption and accurancy, which can meet industrial application. Now, the automatic control system has been formally applied. The successful application of the roll shape patent and strip crown and shape online control technology, which have independence intellectual property rights, will play an important significance in changing the situation of core technology and localizing the core technology about large-scale hot strip mill, which is depending on introducing from abroad for a long time.