PURPOSE: To reduce a camber shape in the width direction and further to improve a camber and wave in the longitudinal direction by eliminating the temp. difference between the surface and rear faces of steel plate at the time of hot straightening the shape in the manufacture of a thick plate and controlling the camber shape in the width direction of the thick steel plate.
CONSTITUTION: The temp. difference ΔTM between the surface and rear faces and average temp. TS(M) on the surface of the steel plate 2 which is rolled with a finishing mill 1 are measured with a thermometer 3 for surface and rear faces of steel plate. The water-quantity ratio of the upper side to the lower side in slow cooling equipment 4 provided between the finishing mill 1 and a hot shape straightening machine 5 is selected according to the temp. of steel plate and temp. difference between the surface and rear faces at the time of being finished by rolling, the thickness and width of the steel plate and the kind of steel. During a limited transfer time between the finishing mill 1 and the hot shape straightening machine 5, by changing the cooling rate balance between the surface and rear faces of steel plate with this slow cooling equipment and eliminating the temp. difference between the surface and rear faces at the time of hot straightening, the chamber shape in the width direction of steel plate after the steel plate is cooled to the ordinary temp. is reduced and further the camber and wave in the longitudinal direction are also improved as synergistic effect. In this way, the rte of restraightening in the finishing stage is reduced.
OSADA MOTOHIRO
NISHIOKA KIYOSHI
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