Patent ID: 8480949

Claim:
A gas-jet cooling apparatus for a continuous annealing furnace apparatus comprising: a plurality of tubular pressure headers extending in a width direction of a steel strip and having a length that is larger than a width of the steel strip, wherein the pressure headers are arranged to face each of front and back surfaces of the steel strip along a longitudinal direction of the steel strip at a pitch L; and a plurality of nozzles protruding from the pressure headers, wherein the nozzles are arranged along the width direction of the steel strip at a pitch W and arranged along the longitudinal direction of the steel strip in a staggered manner, wherein positions of the pressure headers on the front and back sides of the steel strip are arranged to be displaced in the longitudinal direction of the steel strip such that a distance, in the longitudinal direction of the steel strip, between pressure headers on the front side of the steel strip and pressure headers On the back side of the steel strip is equal to or greater than ⅓ and equal to or smaller than ⅔ of the pitch L, of the pressure headers in the longitudinal direction of the steel strip, and wherein the nozzles on the front and back sides of the steel strip are arranged to be displaced in the width direction of the steel strip such that a displacement amount, in the width direction of the steel strip, between the nozzles in a nozzle group on one of the front and back sides of the steel strip and the nozzles in a nozzle group on another of the front and back sides of the steel strip is equal to or greater than ⅙ and equal to or smaller than ⅓ of the pitch W of the nozzles in the width direction of the steel strip.