No abstract

This paper considers the equipment and technological characteristics of continuous annealing process (CAP) to solve the issue of strip buckling. It analyses the mechanism of hot buckling and transverse compressive stresses from internal and external forces. A basic description of strip buckling is given together with a new concept of a buckling index. The critical buckling condition is presented, and the model of strip buckling index in the CAP is proposed. The distribution of strip buckling index in different sections of the process is analysed quantitatively along with the influence of incoming strip shape, transverse temperature difference, roller profile, friction coefficient, set tension and strip processing speed on the strip hot buckling index in CAP. Results show that with the influence of thermal stress, the transverse compressive stress that affects the middle part of the strip is largest in the heating section, which is also where hot buckling occurs most easily; centripetal force is dominant in the soaking and slow cooling sections, and in these sections buckling occurs at the roller shoulder. In different sections, the strip buckling index distribution differs, whereas the influence of other parameters on buckling index remains similar.

This study has fully considered the mechanical and technological characteristics of a continuous annealing and processing line (CAPL) by proposing the concept of in section shape and out section shape, building a set of in section shape and out section shape prediction models, and quantitatively analysing the differences between them. The paper provides a set of comprehensive control models suitable for CAPL, targeting the best overall section shape, the minimum in section shape and the minimum shape difference between unit exit and the goal; develops a set of online prediction and control software for cold rolling strip shape in CAPL and promotes it in practical production to improve the strip conveying stability and accuracy of exit shape control.

The conventional universal crown mill (UCM) temper mill cannot be controlled well for asymmetric high-order complex wave shapes; thus, a novel type of asymmetric universal crown temper mill (AS-UCM) was designed, which was configured for asymmetric bending of the work roll and intermediate roll, as well as asymmetric axial shifting of the intermediate roll. The corresponding shape control technology was established. Taking the typical production process as an example, the present study quantitatively analysed the control effect of AS-UCM and the ordinary UCM temper mill on asymmetric high-order complex wave shapes. Moreover, the related technology was commercially applied to the 750 mm AS-UCM with great economic benefits.

Several problems, such as strip deviation and buckling, are encountered in the continuous annealing process. In this study, equipment and process features of continuous annealing, as well as the advantages and disadvantages of single taper roller and double taper roller in the prevention and treatment of the buckling and strip deviation were considered. Basing on a number of field experiments and theoretical studies, a new set of furnace roller profile curve was proposed and a set of optimisation model suitable for furnace roller was established, with travelling stability of the strip as the objective function. Test results of field production showed that the strip exhibited high speed and stability after optimisation, and the service cycle of the furnace roller was considerably improved. The results of this study provide an important economic benefit for the site and are valuable for further popularisation and application.