METHOD FOR CORRECTING COATING SURFACE DENSITY ON STEEL STRIP, WARP DETECTING METHOD, AND WARP CORRECTING METHOD

摘要

PROBLEM TO BE SOLVED: To correct and unify the hot dip metal coating surface density in the width direction of a steel strip by correcting the warping shape of the steel strip based on the warping shape in the width direction of the steel strip obtained from the experienced value of the distance between a gas wiping nozzle and the steel strip, and the experienced value of the coating surface density on a face side and the back. ;SOLUTION: A steel strip is dipped in a hot dip metal coating bath, it is taken out through a sink roll and a support roll, the coating surface density on a face side and the back is regulated through the gas wiping, and the coating surface density is measured by a coating surface density meter using the fluorescent X-ray spectroscopy, etc., to regulate the gas wiping. The distance from the reference pass line to the surface of the steel strip is calculated to obtain the warping shape of the steel strip in its width direction, and corrected by the formula x=((W1n-W2n)/(W1n+W2n)).D0, where x is the warp, D0 is the experienced value of the distance between the wiping nozzle and the steel strip = (interval of wiping nozzles-thickness of steel strip)/2, n is a constant, and W1, W2 are the coating surface density on the face side and the back of the steel strip, respectively. n=1 when D0α, or n=2 when D0≤α.;COPYRIGHT: (C)2000,JPO