JPH01271032A - Horizontal continuous casting apparatus for double-layer cast billet - Google Patents

Abstract

PURPOSE:To improve the quality of boundary part in a double-layer cast slab by arranging vessels for charging molten metals to come to outer layer and inner layer, respectively, setting a pouring nozzle penerating a mold and arranging a magnet or a solenoid coil at the tip part thereof. CONSTITUTION:A tundish 1 is divided with a partition wall 2 and sectional chambers 4a, 4b for charging the molten metals 3a, 3b forming the inner layer and outer layer. From the sectional chamber 4a, the pouring nozzle 6 extending as penetrating the chamber 4b and the mold 5 is arranged to horizontal direction. Further, the magnet 8 or the solenoid is arranged at outer circumference of the tip part of the nozzle 6, to form static magnetic field at the right angle to the casting direction. By this method, as the boundary flowing of the molten metals 3a, 3b is restrained in the tip part of the nozzle 6, mixture of the metal 3a, 3b is clearly prevented. Therefore, the quality of the doundary part in the double-layer cast slab formed with the solidified shells 7a, 7d is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for producing a slab having a multilayer structure in which an outer layer and an inner layer are clearly separated.

2. Prior Art] As a method for manufacturing multilayer steel materials by continuous casting, two immersion nozzles of different lengths are inserted into a mold, and the discharge holes of each nozzle are arranged at different positions with respect to the casting direction. The method of injecting molten metal was published in Japanese Patent Publication No. 44-2736.
It was introduced in Publication No. 1.

Further, Japanese Patent Publication No. 49-44859 proposes providing a partition wall made of a refractory material to separate the molten metals in order to prevent the molten metals from mixing together.

On the other hand, Japanese Unexamined Patent Publication No. 57-75256 proposes a method of continuously casting such a multilayer slab in a horizontal manner. In this method, a first molten metal is poured from two containers separated by a= into a horizontally arranged mold to form a solidified outer layer, and a second molten metal is poured into the second molten metal. The inner layer is formed by cooling and solidifying inside the solidified shell. Further, an injection nozzle for injecting the second molten metal is arranged to penetrate the inner space of the mold.

[Problem to be solved by the invention]

When manufacturing a slab having a multilayer structure by forming solidification nozzles from different types of molten metals in this way, it is necessary that the outer layer and the inner layer are clearly separated.

In this regard, in the above-mentioned Japanese Patent Application Laid-Open No. 57-75256, in order to prevent mixing of the molten metal for the outer layer and the molten metal for the inner layer,
The external shape of the nozzle provided for injecting the molten metal for the inner layer is set to be separated from the shell that is solidifying around the nozzle by a predetermined distance or more. However, when using a relatively long nozzle horizontally immersed in molten metal such as molten steel, the nozzle becomes eccentric and comes into contact with the solidified shell.
Increased risk of damage. Further, if the molten metal for the outer layer and the inner layer are separated from the inner surface of the surrounding solidified shell by a sufficient distance to avoid this contact, mixing of the molten metal for the outer layer and the inner layer will occur actively. Further, since the flow rate of the molten metal flowing through the mold and the injection nozzle varies mainly depending on the head pressure of the molten metal, it is also difficult to form an outer layer with a required thickness ratio to the inner layer.

Therefore, the present invention applies an electromagnetic brake to the molten metal flow at the tip of the injection nozzle, thereby keeping the outer surface of the nozzle for injecting the molten metal for the inner layer at a sufficient distance from the shell that is solidifying around it. The purpose of the present invention is to manufacture a slab having a multilayer structure in which the inner layer and the outer layer are clearly separated, without causing troubles due to contact between the nozzle and the shell.

[Means to solve the problem]

In order to achieve the objective, the horizontal continuous casting apparatus for multi-layer slabs of the present invention includes a first container containing molten metal that will become the outer layer of the multi-layer slab, and a connection to the side wall of the first container. a second container containing molten metal that will become the inner layer of the multilayer slab, and a second container connected to the second container;
A pouring nozzle extending horizontally through the first container and the mold, and a magnet or solenoid coil for applying an electromagnetic brake disposed around the outer periphery of the tip of the pouring nozzle. shall be.

[Effect]

Hereinafter, the present invention will be specifically explained along with its operation with reference to the drawings.

FIG. 1 is a sectional view schematically showing a continuous casting apparatus of the present invention. This continuous casting device converts the tundish 1 into the partition wall 2.
Accordingly, the multi-layer slab is divided into a compartment 4a which accommodates the molten metal 3a which becomes the inner layer, and a compartment 4b which accommodates the molten metal 3b which also serves as the outer layer. In addition, these compartments 4
In place of a and 4b, independent containers can also be used. Therefore, in the claims of this specification, the term "container" is used to include this independent container and the aforementioned compartments.

The side wall of the tundish L1 on the molten metal 3b side is open, and a horizontally extending mold 5 is connected thereto. Further, from the compartment 4a, an injection nozzle 6 extending through the compartment 4b and the mold 5 is arranged in the horizontal direction. As shown in FIG. 2, which is a sectional view taken along the line II in FIG. 1, one or more injection nozzles 6 are arranged in the width direction of the slab.

The molten metal 3b flowing out from the compartment 4b is cooled and solidified by heat removal through the mold 5, and forms a solidification shelf b on the inner wall of the mold 5. The tip of the injection nozzle 6 is located at the location where the solidified shelf b grows to an appropriate thickness.

The molten metal 3a from the injection nozzle 6 is cooled and solidified after flowing out from the injection nozzle 6, and is deposited as a solidification shelf a inside the solidification shelf b.

Here, a magnet 8 is arranged around the outer periphery of the tip of the injection nozzle 6. This magnet 8 applies a static magnetic field having lines of magnetic force extending in a direction perpendicular to the casting direction to the molten metals 3a, 3b. That is, in FIG. 1, the lines of magnetic force extend in the vertical direction. This static magnetic field causes the injection nozzle 6 to
The flow at the boundary between the molten metals 3a and 3b is braked at the tip of the molten metals 3a and 3b, and an interface 9 is formed between the molten metals 3a and 3b. Therefore, due to the kinetic energy of the molten metal X3a flowing out from the injection nozzle 6, the molten metals 3a, 3
b are not mixed with each other, the solidified shelves a and 7b formed have approximately the same composition as the respective molten gold@3a, 3b.

Note that instead of the magnet 8, a solenoid coil may be wound around the outer periphery of the tip of the large pouring nozzle 6, and a direct current may be applied to this solenoid coil. In this case, lines of magnetic force parallel to the casting direction are generated, waves at the interface 9 are suppressed, and mixing of the molten metals 3a and 3b is prevented. For example, the molten metal 3a flowing out from the injection nozzle 6 will no longer flow backward through the gap between the injection nozzle 6 and the inner wall of the mold 5 and mix with the molten metal 3b.

When such an electromagnetic brake is not applied, both molten metals 3a are separated at the interface 9 due to the injection flow from the injection nozzle 6, the density difference between the molten metals g3a and 3b, thermal convection, etc.

A mixture of 3b occurs. As a result, the obtained multilayer slab is
The boundary between the outer layer and the inner layer becomes unclear.

In order to avoid this, it is possible to increase the diameter of the injection nozzle 6 or use a shielding plate.

However, contact between the injection nozzle 6 or the shielding plate and the solidification shelf a tends to occur, making casting work difficult.

〔Example〕

In FIG. 1, a mold 5 having an internal space of 10,100 mm x 300 mm and a length of 0.5 m was connected to the side wall of the tundish 1. Further, an injection nozzle 6 having an inner diameter of 20 mm, an outer diameter of 40 mm, and a length of 0.8 m was attached to the partition wall 2 by penetrating the compartment 4b and the mold 5. The length of the injection nozzle 6 in the mold 5 is 0.4 m, and the casting speed is 1.
m/min.

And, 5U3304 in compartment 4) of Tanditshu l.
The molten metal 3b of the reed assembly is supplied, and the flow rate 9 is supplied from the injection nozzle 6.
It was injected at a rate of 8 kg/min. On the other hand, molten metal 3a having a composition of ordinary steel is supplied to the compartment 4a, and the molten metal 3a is poured into the mold 5 ut27.
kg/min. And 5000 with magnet 8
A static magnetic field with a Gaussian magnetic flux density is generated, and the molten gold [3
Mixing of a and 3b was prevented.

In this way, the board width is 300mm and the board thickness is 100mm.
of slabs were manufactured. The obtained slab had an outer layer with a thickness of 18 mm. FIG. 3 is a graph showing the change in Cr content in the thickness direction of this slab. Third
As is clear from the figure, the Cr content changes rapidly between the outer layer and the inner layer. This indicates that the outer layer and the inner layer are clearly separated.

On the other hand, when casting was carried out under the same conditions without applying the electromagnetic brake, the Cr content of the obtained slab was found to be gradual in the thickness direction, as shown in Fig. 3 as a comparative example. changed. That is, molten metal 3a, 3
By mixing b, chromium diffused into the interior, resulting in a slab in which the outer layer and inner layer were not clearly separated.

〔Effect of the invention〕

As explained above, in horizontal continuous casting, a magnet or solenoid coil is placed around the outer periphery of the tip of the injection nozzle,
It provides electromagnetic braking force to the injected molten metal. This prevents dissimilar molten metals from mixing with each other, and the solidified shells produced from each molten metal,
As a result, a slab having a multilayer structure in which the inner layer and the outer layer are clearly separated can be obtained. The obtained multilayer slab has the desired composition and
Since it consists of an outer layer and an inner layer with different compositions, it is a product with stable quality.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a continuous casting apparatus of the present invention, FIG. 2 is a sectional view taken along line I-1 in FIG. 1, and FIG. 3 is a graph specifically showing the effects of the present invention. l: Tandish 2: Partition walls 3a, 3b: Molten gold 1iiK 4a, 4b:
Compartment chamber 5: mold 6: injection nozzle 7a,
7b: Solidified shell 8: Magnet 9: Interface ゛Patent applicant: Nippon Steel Corporation (and 1 other person) Agent: Masu Kobori (and 2 others) Figure 1 Figure 2 Figure 3 From the surface of the slab Distance (rrwn)

Claims (1)

[Claims] 1. A first container containing molten metal that will become the outer layer of the multilayer slab, a mold that is connected to the side wall of the first container and extends in the horizontal direction, and molten metal that will become the inner layer of the multilayer slab. a second container containing a molten metal, a pouring nozzle connected to the second container and extending horizontally through the first container and the mold; 1. A horizontal continuous casting device for multi-layer slabs, characterized in that it is equipped with a magnet or a solenoid coil for applying an electromagnetic brake.