Influence of Thickness Profile after Sizing Press on Width Profile at Head and Tail Portions of Slab

Abstract

Changing mold width of continuous casting takes long shut down time. Therefore in order to produce various width slabs in roughing mills, sizing press has been installed in most hot strip mills. Installation of sizing press can improve total productivity of continuous casting and hot strip mills.

After sizing press and horizontal rolling, it is known that width around head and tail portions of slab are narrower than that of middle. These narrow portions, which are called “width drop”, cause yield loss. Therefore some technologies have been developed to prevent width drop.

It is said that width drop results from difference of width spread in horizontal rolling depending on distribution of dog bone profile along rolling direction of slab. However some experimental and simulated data in some papers indicated width shrinkage with horizontal rolling of slabs whose cross sectional shape was dog bone profile. Although it is presumed that width drop is influenced by not only width spread but also width shrinkage, there are no papers which describe mechanism of width shrinkage clearly.

In this paper, experiment and FE analysis of horizontal rolling with slabs which have dog bone profile were executed in order to investigate mechanism of width shrinkage. As the result of FE analysis, width shrinkage is influenced by area reduction ratio between width edge part and width center part. Furthermore longitudinal velocity distribution along width direction around head and tail portions cause width shrinkage during horizontal rolling.