JPH05277661A - Method for continuously casting clad steel sheet by twin rolls - Google Patents

Abstract

PURPOSE:To prevent the mixture of molten metals at upper and lower layers by arranging a separating plate to a pouring nozzle at the lower layer side immersed into a molten metal pouring basin part. CONSTITUTION:In two pouring nozzle 4a, 4b having different lengths immersed into the molten metal pouring basin part 3 formed by rolls 1 and side weirs 2 in a twin roll type continuous casting apparatus, the separating plate 5 horizontally extended to the long pouring nozzle 4b for pouring the molten metal is arranged into the lower layer. Then, the molten metal for forming the outer layer solidified shell 7a is poured into the upper layer of the separating plate and the molten metal for forming the inner layer solidified shell 7b into the lower layer and the solidified shells in the inner and the outer layers are integratively composed at a roll kiss point 8 or the front or the rear parts thereof to produce a clad steel sheet. By this method, the mixture of the molten metals at the upper and the lower layers can be prevented and therefore, this method can be applied to the production of the clad steel sheet using the materials having different densities and the clad steel sheet having extremely clear boundary of the inner and the outer layers is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting method for continuously producing a clad steel plate by compounding different kinds of molten metals by twin roll type continuous casting for producing a thin plate slab.

[0002]

2. Description of the Related Art Conventionally, as a technique for producing a clad steel sheet, a method based on a rolling method or an explosion deposition method is known. These techniques are methods in which individually manufactured sheet materials are brought into close contact with each other by rolling or explosive force.

However, the above-mentioned method needs to be individually rolled to manufacture the plate materials to be composited, and it takes a lot of time and cost to combine the composite materials, so that it is not applied so much at present.

As a method for solving the above problems, a continuous casting method of a composite metal material using a rectangular cooling mold has recently been used. However, this method has a slab thickness of 1
This is a technology for ultra-thick slabs with a thickness of 00 mm or more. To make it into a practical clad steel plate, it is necessary to go through steps such as hot rolling and cold rolling, and many steps are required. Still, the problem of high cost still remains.

As an alternative technique, recently, a technique of directly producing a multi-layer metal material having a predetermined plate thickness, that is, a clad steel sheet by twin roll type continuous casting has been considered.

FIG. 2 is a diagram showing an example of a continuous casting method of a clad steel plate by twin rolls. This technique is a pool of water formed by two rolls 11 and side weirs 12 provided on both sides of the rolls. Two injection nozzles 14a and 14b having different lengths are immersed in the portion 13, and different kinds of molten metals are injected into the injection nozzles to form two upper and lower molten metal layers 13a and 13b in the basin 13. ..

Next, the outer layer solidified shell 15a is formed by the upper layer molten metal in contact with the roll 11, and then the inner layer solidified shell 15b is formed by the lower layer molten metal, and the inner and outer layer solidified shells 15a, 15b are formed by roll kiss points 16
Is a continuous casting method for a clad steel plate by twin rolls, in which the clad steel plate 17 is manufactured by being integrally compounded with each other.

[0008]

By the way, this technique is
There is a risk that different kinds of molten metals will coexist in the molten metal pool 13 and the two kinds of molten metals will mix. Therefore, in order to avoid this mixing, it is necessary that the molten metal forming the upper molten metal layer 13a, that is, the outer layer solidified shell 15a has a lower density than the molten metal of the lower layer forming the inner layer solidified shell 15b.

For this reason, this method cannot be applied to the production of a clad steel sheet using a material having a higher density in the outer layer than in the inner layer, for example, a clad steel sheet in which the inner layer is a normal mild steel material and the outer layer is a stainless steel material. ..

The present invention has been made in view of the above problems,
Provided is a continuous casting method for a clad steel plate which prevents the upper and lower layers of molten metal from being mixed in a molten metal pool in twin roll continuous casting.

[0011]

According to the present invention, two pouring nozzles having different lengths are immersed in a molten metal pool portion formed by two rolls and side dams provided on both side surfaces of the rolls, and the pouring is performed. In a continuous casting method for producing a clad steel plate by injecting different kinds of molten metals by nozzles and forming upper and lower two layers of molten metal in the pool, long injection of injecting molten metal into the lower layer of the injection nozzles. The nozzle is provided with a horizontally extending separator, and the molten metal for forming the outer layer solidified shell and the molten metal for forming the inner layer solidified shell are respectively injected on the upper layer of the separator and the solidified shells of the inner and outer layers are roll-kissed. It is a continuous casting method for a clad steel plate by twin rolls, which is characterized in that the clad steel plate is manufactured by integrally combining the points.

[0012]

According to the present invention, in a continuous casting method of thin plate cast pieces by twin rolls known as the Bessemer method, the length of a pool of water formed by two rolls and side dams provided on both side surfaces of the rolls is provided. 2 different injection nozzles are immersed, and different kinds of molten metals are injected into these two injection nozzles to form upper and lower two molten metal layers in the pool.

Further, among the above-mentioned two injection nozzles, a separating plate for horizontally spreading is provided at a separating portion where a molten metal layer of two layers above and below a long injection nozzle immersed in the lower layer is provided, and an outer layer is provided above the separating plate. The molten metal that forms the solidified shell and the molten metal that forms the inner layer solidified shell are respectively injected into the lower layer, and the separator prevents the molten metal in the upper layer and the molten metal in the lower layer from mixing.

If this separator is made too large, it breaks the outer layer solidified shell formed on the surface of the roll and the molten metal flows out to the outside of the apparatus, and if it is made smaller, the gap between the roll and the solidified shell becomes large. The molten metal in the upper and lower layers may mix with each other. Therefore, it is necessary to determine the size in consideration of the thickness of the outer layer solidified shell to be formed.

Then, the outer layer solidified shell formed by being cooled by the roll and the inner layer solidified shell which is formed by being cooled by the outer layer solidified shell and formed inside the outer layer solidified shell are integrally compounded at a roll kiss point to form a multi-layer slab, Steel sheets are manufactured.

By providing the separator plate in this way, both molten metals do not mix even if molten metals having different densities are injected into the upper and lower layers, and the produced clad steel plate is
Since the molten metal does not mix, the boundary between the outer layer and the inner layer becomes a slab with an extremely clear boundary, and an excellent clad steel sheet can be obtained.

[0017]

FIG. 1 is a side view showing an example of a twin roll type continuous casting apparatus for producing a clad steel sheet suitable for carrying out the present invention.

In this continuous casting apparatus, two pouring nozzles 4a and 4b having different lengths are immersed in a molten metal pool 3 formed by two rolls 1 and side dams 2 provided on both sides of the rolls. Each of the nozzles is configured to inject different kinds of molten metal into the molten metal layer 3 into upper and lower two molten metal layers 3a and 3a.
b is formed.

Of the above two injection nozzles 4a and 4b,
On the long injection nozzle 4b side to be immersed in the lower layer, there is provided a separating plate 5 which horizontally spreads at the separating portions of both upper and lower two molten metal layers 3a and 3b which form a boundary.
The molten metal layers 3a and 3b are divided into upper and lower parts by a separator plate 5.

Here, from the short injection nozzle 4a to the separator plate 5
The molten metal poured into the upper pool 3 of molten metal to form the molten metal layer 3a is cooled by the roll 1 and starts solidification from the solidification start point 6a in contact with the molten metal surface, forming the outer layer solidified shell 7a. It is guided downward.

Further, the molten metal that has been injected from the long injection nozzle 4b into the lower pool 3 of the separator 5 to form the molten metal layer 3b is cooled by the outer layer solidification shell 7a, and the separator 5 in the pool 3 is cooled. The inner layer solidified shell 7b is formed inside the outer layer solidified shell 7a with the level as the solidification starting point 6b.

Since the separator 5 is located in the middle of the outer layer solidified shell 7a formed in the two rolls 1, if it is made too large, the outer layer solidified shell 7a formed on the roll surface is broken. , Molten metal flows out of the equipment and becomes a breakout.
Alternatively, the gap between the solidified shell 7a and the solidified shell 7a may become large, and the molten metals in the upper and lower layers may be mixed. Therefore, it is necessary to determine the size in consideration of the thickness of the outer layer solidified shell 7a to be formed.

Then, the solidified shells 7a, 7b for the inner and outer layers are formed.
Are composited together at the roll kiss point 8 to form a multi-layer cast slab 9, and a clad steel plate is manufactured.

Thus, by providing a horizontally extending separator plate in the lower injection nozzle to prevent the molten metal in the upper and lower layers from being mixed, a slab with an extremely clear boundary between the outer layer and the inner layer becomes a superior clad steel sheet. Is obtained.

Further, by providing the separator plate in this way, even if molten metals having different densities are injected into the upper and lower layers, the two molten metals do not mix, and for example, the upper layer or the outer layer has a higher density than the lower layer or the inner layer. This method can also be applied to the production of clad steel plates using large materials.

[0026]

As described above, according to the present invention, by providing the separator plate in the lower layer injection nozzle that is immersed in the molten metal pool, it is possible to prevent the molten metal in the upper and lower layers of the molten metal pool from being mixed. Therefore, it can be applied to the production of a clad steel sheet using materials having different densities in the inner and outer layers, and a slab with a very clear boundary between the outer layer and the inner layer can be obtained, and a high-quality clad steel sheet can be obtained.

[Brief description of drawings]

FIG. 1 is a side view showing an example of a twin roll type continuous casting apparatus for producing a clad steel sheet suitable for carrying out the present invention.

FIG. 2 is a drawing showing an example of a conventional method for producing a clad steel plate by twin roll type continuous casting.

[Explanation of symbols]

 1 Casting roll 2 Side weir 3 Hot water pool 3a, 3b Molten metal layer 4a, 4b Injecting nozzle 5 Separator 6a, 6b Solidification start point 7a, 7b Solidification shell 8 Roll kiss point 9 Multi-layer cast piece

Claims (1)

[Claims] 1. A basin formed by two rolls and side weirs provided on both sides of the rolls has different lengths.
In a continuous casting method of dipping a book pouring nozzle, pouring different kinds of molten metals by the pouring nozzle to form upper and lower two molten metal layers in a pool, and manufacturing a clad steel plate, A long injection nozzle for injecting the molten metal into the lower layer is provided with a horizontally extending separator plate, and the molten metal for forming the outer layer solidified shell in the upper layer of the separator plate and the molten metal for forming the inner layer solidified shell in the lower layer are respectively injected. Then, the clad steel sheet is manufactured by integrally combining the solidified shells of the inner and outer layers at roll kiss points to produce a clad steel sheet.