Gas jet cooling device for continuous annealing furnace

Abstract

Non-uniformity in the temperature distribution in the width direction of a steel strip and fluttering of the steel strip when gas is discharged at a high speed are reduced. A gas-jet cooling apparatus for a continuous annealing furnace includes a plurality of tubular pressure headers having a length that is larger than a width of the steel strip, the pressure headers being arranged so as to face each of front and back surfaces of a steel strip along a longitudinal direction of the steel strip at a pitch L; and a plurality of nozzles protruding from the pressure headers, the nozzles being 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. Positions of the pressure headers on the front and back sides of the steel strip are arranged so as to be displaced in the longitudinal direction of the steel strip such that a distance, in the longitudinal direction of the steel strip, between the pressure headers on the front side of the steel strip and the pressure headers on the back side of the steel strip is equal to or greater than 1 / 3 and equal to or smaller than 2 / 3 of the pitch L of the pressure headers in the longitudinal direction of the steel strip. The nozzles on the front and back sides of the steel strip are arranged so as 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 the other of the front and back sides of the steel strip is equal to or greater than 1 / 6 and equal to or smaller than 1 / 3 of the pitch W of the nozzles in the width direction of the steel strip.

Description

technical field [0001] The invention relates to a gas jet cooling device for a continuous annealing furnace. Background technique [0002] In the continuous annealing furnace, the steel strip is continuously heated, soaked and cooled, and over-aging is performed as necessary. In order to make the properties of the steel strip desired, it is important to uniformly and rapidly cool the steel strip in addition to the heating temperature and soaking time. In recent years, the development of high-strength steel such as automotive materials has progressed, and rapid cooling from an annealing temperature of 900-800°C to about 300-150°C has been performed in order to achieve desired tensile strength, bending properties, and elongation properties. process development. [0003] In the cooling of the steel strip, various cooling media are used, and the cooling speed of the steel strip is also different according to the choice of the refrigerant. [0004] If water is used as the cool...

Images