Cooling apparatus for metal strip and continuous heat treatment facility for metal strip

Abstract

A cooling device for a metal plate includes a plurality of first nozzles and a plurality of second nozzles disposed on both sides of the metal plate, respectively, in a thickness direction of the metal plate across a pass line of the metal plate. The plurality of first nozzles form a staggered array in which a pitch in a width direction of the metal plate is Xn, a pitch in a longitudinal direction of the metal plate is Yn, and an offset amount in the width direction of a pair of first nozzles disposed adjacent to each other in the longitudinal direction is ΔXn. The plurality of second nozzles form a staggered array in which a pitch in the width direction is Xn, a pitch in the longitudinal direction is Yn, and an offset amount in the width direction of a pair of second nozzles disposed adjacent to each other in the longitudinal direction is ΔXn. The staggered array of the first nozzles and the staggered array of the second nozzles are disposed offset from each other such that, a center of the second nozzle is at a position offset by a shift amount S from a center of the first nozzle in the width direction, and the center of the second nozzle is positioned in a region defined by an oval having a semi-axis of ΔXn/4 in the width direction and a semi-axis of Yn/3 in the longitudinal direction. The shift amount S is expressed by S=m×ΔXn/2, where m is an odd number such that S is closest to Xn/2.