Analysis on Buckling of Steel Plates in a Process of On-line Controlled Cooling

Abstract

During on-line controlled cooling of continuous motion type, steel plates are subjected to successive water cooling from the top to the bottom. Therefore thermal gradients in the longitudinal direction necessarily arise. Especially in the cooling which requires a large temperature drop like direct quenching, the plates will buckle by thermal stress generated from the longitudinal temperature gradient and shape problems will occur.
Those plates are flattened by hot leveler, but afterward the buckling may occur during air-cooling, if the temperature in the plates is not uniform just after the leveling.
We carried out the finite element method analysis on buckling caused by thermal stress which arose from the longitudinal temperature distribution during and after the controlled cooling.
The following terms were examined quantitatively.
(1) Effect of the zone length of controlled cooling, the plate thickness and the plate width on the buckling behavior during and after the controlled cooling.
( 2) Arrangement condition of pinch rolls for avoiding the buckling under the controlled cooling.
The knowledge obtained from the analysis contributed to the development of the controlled cooling equipment in the plate factory of NKK's Keihin Works. Now it is useful for the guide in the actual operation.