JPH09122855A - Nozzle for continuously casting beam blank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To widen a spouting hole area and the nearest interval with a mold and to improve a casting quality even if the casting quantity is increased, with respect to a nozzle for pouring molten metal into the mold for a beam blank. SOLUTION: The nozzle for continuously casting the beam blank has an almost similar outer surface shape in minimized triangle shape 7 which forms the circle in contact with a flange part 2 and a fillet part 3 in the inner surface of the mold as the inscribed circle 6 and forms the flange part 2 as the one side, and the shape with the suitable round corner parts 5 in this cross section. The spouting hole area is widened in comparison with the conventional cylindrical type nozzle which has the same thickness and nearest interval with the mold, by forming such cross sectional shape. Further, in the case of the same spouting hole area as the cylindrical type nozzle, this nozzle is made wide in the nearest interval with the mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle for continuous beam blank casting.

[0002]

2. Description of the Related Art A conventional beam blank continuous casting nozzle has a cylindrical shape as shown in FIG. 3, and as a dipping nozzle between a flange portion 2 and a fillet portion 3 of a mold as shown in FIG. It is pouring as a semi-immersion nozzle. The inner diameter of the nozzle is 20 to 30 mm. The nozzle was closest to the mold fillet portion 3 and the flange portion 2 in the mold (FIG. 4).

The immersion nozzle is a type of continuous casting nozzle in which the upper surface is connected to a tundish and the lower surface is immersed in the molten metal of the mold for pouring.
The semi-immersion nozzle is a nozzle for continuous casting of the type in which the upper surface is released from the tundish, the funnel-shaped receiving port receives the molten metal, and the lower surface is dipped in the molten metal of the mold and poured.

[0004]

In order to increase the amount of beam blank casting (increased casting speed) or decrease the nozzle discharge flow velocity, it is necessary to increase the area of the nozzle discharge port. When expanding the discharge port with the conventional nozzle shape, the closest distance between the outer surface of the nozzle and the fillet part 3 of the mold becomes small, and the shell is washed by the discharge flow of the melt and the melt on the surface between the nozzle and the mold is melted. Problems such as the generation of bridges (bare metal) due to solidification occur. For this reason, in the cylindrical nozzle, there is a minimum distance to be held in the closest distance, and the maximum ejection port area is restricted by the mold shape.

The present invention is a beam blank for a nozzle for pouring molten metal into a beam blank mold, which has a large discharge port area and a widest distance between the nozzle and the mold so that the casting quality can be improved while increasing the casting amount. An object is to provide a nozzle for continuous casting.

[0006]

The present invention adopts a nozzle having the following structure in order to solve the above problems in a continuous casting nozzle for pouring molten metal into a beam blank mold.

(1) In order to prevent slab defects due to the growth of metal, a distance between the outer surface of the nozzle and the inner surface of the fillet portion is secured (for example, 20 mm or more), and the cross-sectional shape of the outer surface of the nozzle outlet is triangular. Approach to.

(2) The triangular shape is a substantially similar triangular shape in which a circle in contact with the fillet portion and the flange portion is an inscribed circle and the flange portion is one side, and is reduced by a predetermined distance between the inner surfaces.

(3) The surface corresponding to the fillet portion may be a substantially triangular shape which is a curve having an equal distance from the fillet portion.

In the nozzle for continuous beam blank casting according to the present invention, by making the outer cross-sectional shape of the discharge port close to a triangular shape as described above, the discharge port is compared with a cylindrical nozzle having the same wall thickness and the closest contact distance with the mold. The area becomes large.
Further, when the discharge port area is the same as that of the cylindrical nozzle, the nozzle according to the present invention can widen the closest distance to the mold.

Therefore, in the nozzle of the present invention, since the nozzle outlet surface area can be increased with the same distance between the nozzle outer surface and the mold inner surface, the casting speed can be increased to the conventional outlet flow velocity level even with the same mold cross-sectional area. I can do things. As described above, according to the beam blank continuous casting nozzle of the present invention, it is possible to widen the closest distance to the mold while maintaining the same ejection opening area as that of the cylindrical nozzle, thereby causing a casting trouble due to metal growth in the nozzle. Can be prevented.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a nozzle for continuous beam blank casting according to the present invention will be specifically described based on the embodiment shown in FIGS. In the following embodiments, the same components as those of the conventional device shown in FIG. 4 are designated by the same reference numerals for simplification of description.

(First Embodiment) First, a beam blank continuous casting nozzle according to the first embodiment shown in FIG. 1 will be described. The nozzle shown in FIG.
A circle 7 in contact with the flange portion 2 and the fillet portion 3 on the inner surface of the mold is an inscribed circle 6, and the triangle 7 has the flange portion 2 as one side.
Is a substantially similar outer surface shape in which the corner portion 5 has an appropriate radius R.

A casting test was conducted using a mold nozzle having a cross-sectional shape as shown in FIG. The mold is a near net shape having a mold length of 800 mm, a web thickness a and a chip thickness b of 50 mm, and the closest distance between the mold inner surface flange portion 2 and the fillet portion 3 is 20.
A semi-immersion nozzle was inserted so that the size became mm.

The nozzle has a cross section of the inner hole of the base of 43 mm and a height of 22.
mm isosceles triangle shape, corner radius 5 mm, wall thickness 20 mm
And Equivalent to S20C as a casting material (0.20%
C, 0.3% Si, 0.8% Mn, 0.02% P, 0.
02% S), casting temperature 1550 ° C., casting speed 3.
It was set to 0 m / min.

With this nozzle shape, the discharge cross-sectional area is increased by 60% and the nozzle outlet flow velocity is decreased by 40% as compared with the conventional cylindrical nozzle having the same wall thickness and the closest distance to the mold. The number of cracks that occurred was reduced. Further, as a result of the flow in the web direction and the flange direction, there was no rise in the molten metal surface at the nozzle / mold closest point, and uniform solidification was achieved with a smooth meniscus shape.

Further, the surface flow of the solidified shell is made uniform, and the adhered inclusions are uniformly removed and floated, so that the amount of inclusions in the cast piece is reduced. As a result of the above, it was possible to obtain a high-quality H-section steel that was uniformly solidified with few cracks and inclusions.

(Second Embodiment) Next, a beam blank continuous casting nozzle according to a second embodiment shown in FIG. 2 will be described. As in the case of the nozzle shown in FIG. 1, this nozzle has a cross-sectional shape of a triangle 7 having a circle in contact with the flange portion 2 and the fillet portion 3 on the inner surface of the mold as an inscribed circle 6 and the flange portion 2 as one side. Is a substantially similar outer surface shape in which the corner portion 5 has an appropriate radius R.

However, in the nozzle shown in FIG. 2, among the three triangular sides of the cross section, the side facing the fillet portion 3 is a curve which is separated from the curve of the fillet portion by a predetermined equal distance. As a result, the closest distance to the mold is increased.

The present invention has been specifically described above based on the illustrated embodiments, but the present invention is not limited to these embodiments, and its specific structure is within the scope of the present invention shown in the claims. Needless to say, various modifications may be added to the configuration.

[0021]

As described above, the nozzle for continuous beam blank casting according to the present invention has an outer surface cross-sectional shape in which the circle contacting the flange portion and the fillet portion on the inner surface of the mold is an inscribed circle and the flange portion is one side. Since the shape is substantially similar to the triangular shape, the discharge flow velocity can be reduced by increasing the nozzle discharge port area. As a result, it is possible to prevent the occurrence of slab breakage and breakout due to shell washing by the pouring flow. Also, the casting amount can be increased.

As described above, in the beam blank continuous casting nozzle according to the present invention, the closest distance to the mold can be made wider than that of the cylindrical nozzle having the same nozzle discharge port area, so that it is generated between the nozzle and the mold. Bridging can be prevented and the quality of the slab is improved.

Furthermore, since the continuous casting nozzle according to the present invention has a nozzle discharge port shape extending in the direction of the web and the flange, the molten metal flows in these directions, and the closest portion between the nozzle and the mold is formed. Smooth meniscus shape without rising of the molten metal surface (3m / in case of cylindrical nozzle)
It was almost 0 that there was a rise of about 5 mm at the casting speed of min. ), Which results in a uniformly solidified shell. In addition, the shell washing flow rate becomes uniform, and the removal of adhering inclusions during solidification occurs uniformly, leading to an improvement in slab quality.

[Brief description of the drawings]

FIG. 1 is a transverse cross-sectional view showing a beam blank continuous casting nozzle according to a first embodiment of the present invention at a position where it is arranged in a mold.

FIG. 2 is a partial horizontal cross-sectional view showing a beam blank continuous casting nozzle according to a second embodiment of the present invention at a position where it is arranged in a mold.

FIG. 3 is a cross-sectional view showing a conventional beam blank continuous casting nozzle, in which (a) is a vertical cross-sectional view and (b) is a horizontal cross-sectional view.

FIG. 4 is a cross-sectional view showing a conventional beam blank continuous casting nozzle at a position where it is arranged in a mold.

[Explanation of symbols]

 1 chip 2 flange part 3 fillet part 4 web 5 corner part 6 inscribed circle 7 triangle a web thickness b chip thickness

Claims (1)

[Claims] 1. A nozzle for pouring molten metal into a beam blank mold, the lower end of which is immersed in the molten metal in the mold,
A discharge port for discharging the molten metal downward is provided at the tip of the nozzle, and the cross-sectional shape of the outer surface of the nozzle is such that the circle in contact with the flange portion of the mold inner surface and the fillet portion is an inscribed circle and the flange portion is one side. Nozzle for continuous casting of beam blank, which has a shape substantially similar to the triangular shape.