JPS63248550A - Method for cooling cast slab - Google Patents

Abstract

PURPOSE:To uniformly cool a cast slab by inclining a rectangular injection hole of a spray nozzle to width direction of a cast slab, so that injection flows from adjoining spray nozzles are not mutually overlapped and cooling the cast slab by the overlapping injection flow accopanied with advancing direction of the cast slab. CONSTITUTION:The rectangular injection hole of the spray nozzle 1 is arranged as inclining by angle alpha to the width direction of the cast slab. The injection flows from the adjoining spray nozzles 1 are not mutually overlapped and the cast slab is cooled by ellipse-state injection flows 3 having inclination to the advancing direction of the cast slab and mutually some slippage. Further, the injection angle gamma2 of the spray nozzle 1 is larger than usual, to enlarge cooling area per one of the nozzle. By this method, distribution of the injection flows to the width direction of the cast slab is stabilized and the cast slab can be uniformly cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for cooling a slab in a secondary cooling zone of continuous casting.

(Prior art and its problems) In continuous casting, the slab whose surface layer has solidified in the mold is cooled by a spray nozzle (water spray or water/air mist spray nozzle) placed between the rolls in a secondary cooling zone. are doing.

The jet hole of this spray nozzle is elongated in the width direction of the slab due to the narrow roll interval, and as shown in FIG.
When two or more of these are arranged in the width direction of the slab, the jets 2 ejected from adjacent nozzles 1 directly overlap each other. In such lapped portions, the droplets interfere with each other and the diameter of the droplets becomes large, making the jet distribution unstable, making it difficult to obtain uniform cooling, and making it easy for slab surface defects to occur.

This invention was proposed to solve these problems, and its purpose is to provide a cooling method that can stabilize the jet flow distribution in the width direction of the slab and uniformly cool the slab. be.

(Means for Solving the Problems) The cooling method according to the present invention is such that the horizontally elongated jet holes of the spray nozzles are inclined with respect to the width direction of the slab, so that the jets from adjacent spray nozzles do not overlap directly with each other, and The slab is cooled by a jet that tilts in one direction and wraps at a different angle.
The jet flow distribution in the slab width direction is stabilized.

(Embodiment) The present invention will be described below based on an illustrative embodiment.

As shown in Fig. 1, the horizontally elongated jet holes of the spray nozzles 1 are inclined at an angle α with respect to the width direction of the slab so that the jets from adjacent spray nozzles 1 do not overlap directly with each other but are inclined in the direction of slab movement. Cooling is performed by elliptical jets 3 that are offset from each other. Furthermore, the spray nozzle 1 injection angle θ2 was changed from the conventional θ
, to increase the cooling area per nozzle.

In this way, approximately the same amount of cooling water can be obtained at each point in the width direction of the slab except for both ends, and the jet flow distribution in the width direction of the slab can be made almost constant. Cooling can be performed.

As a result, surface defects on the slab can be reduced as shown in FIG.

Next, a specific example in which a long-term actual machine test was conducted using the cooling method of the present invention will be described.

As shown in FIG. A large number of nozzles are arranged in the third segment, nozzle spacing 17 (1+++, nozzle height 13Qmyx, θ,
, = 100°, α = 200. This is an example in which the spray width was 31ON, and when the width diameter was 1ON, θ = 830. α=0°
It is.

In the present invention, a substantially uniform water density distribution as shown in FIG. 4 is obtained, and as a result, the incidence of horizontal cracks in the conventional case shown in FIG. 6 is reduced as shown in FIG.

Additionally, since the cooling area is larger than in the past, it is especially advantageous to control the cooling of a portion of the corner of the slab.

(Effects of the Invention) As described above, according to the present invention, the oval jets are inclined in the width direction of the slab, and the adjacent jets are not lapped directly, but are cooled by shifting and wrapping. ,
The jet flow distribution in the width direction of the slab is stabilized, and uniform cooling of the slab becomes possible, thereby reducing surface flaws in the slab.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing a cooling method according to the present invention;
Figures 2 and 3 show the uniformity effect of the slab surface temperature of the present invention,
Graph showing the effect of reducing cracks on the surface of slabs Figure 4 shows a specific example of the present invention, (5) is a perspective view, (B) is a graph, Figure 5 is a graph showing the effect of reducing the crack incidence rate of the present invention , 6th
The figure is a schematic diagram showing an example of arrangement of nozzles, and FIG. 7 is a schematic perspective view showing a conventional example. 1. Spray nozzle, 2. Elliptical jet 3. Elliptical jet.

Claims (1)

[Claims] (1) In a method in which a plurality of spray nozzles having horizontally elongated jetting holes in the slab width direction are arranged in the slab width direction and the slab is cooled by a jet stream from the spray nozzles, the horizontally long jetting holes of the spray nozzles are A slab is cooled by jets that are inclined with respect to one side width direction so that the jets from adjacent spray nozzles do not directly overlap each other, but are tilted in the slab advancing direction and overlap with a deviation. Cooling method.