Influence of strip non-flatness on the coil stress-strain state

Abstract

Reducing the specific consumption of raw materials and materials in rolling shops is always an urgent task. Therefore, it is also important to improve the mathematical apparatus, which is a tool for optimizing technology in rolling shops. Most of the time, the metal in the rolling mills is coiled. Moreover, the coil is a complex object. The coil shape is maintained due to non-linear contact stresses distributed over the thickness and width, arising during the winding process. At the same time, the processes taking place in the metal do not stop with its winding into coil. First, stress relaxation occurs and the strip is deformed due to the creep effect. This is most important for cooling hot rolled coils and processing in bell furnaces due to the high temperature. In coils in a cold state, the processes of shaping do not proceed, but the roll may lose stability. This can lead to defects in the shape of the roll such as “birdie” or “settled coil”. Considering the above, modeling the stress-strain state of a coil is an urgent task. This article presents a mathematical model of the stress-strain state of the coil, taking into account the combined effect of non-flatness, roughness and gage thickness variation of the strip. The influence of the nonflatness of the coiled strip on the stress-strain state of the coil is considered in detail. The characteristic distribution of radial and tangential stresses in the roll after removing the roll from the drum is shown for various variants of the initial non-flatness. Taking into account the non-planarity in the mathematical model of the stress-strain state of the coil provides important advantages. First, to improve the accuracy of mathematical models for changing the shape of a strip in a roll. Secondly, to determine the critical values of the non-flatness of the strip, leading to the loss of stability of the coil.