JPH05277659A - Method for continuously casting clad steel sheet by twin rolls - Google Patents

Abstract

PURPOSE:To provide a casting method for continuously producing a clad steel sheet by composing the different kinds of molten metals by twin roll type continuous casting for producing a cast strip. CONSTITUTION:Two pieces of pouring nozzles 4a, 4b having different lengths are immersed into a molten metal pouring basin part 3 formed by two rolls 1 and side weirs 2 arranged at both end surfaces of the rolls, and the different kinds of the molten metals are poured into the pouring nozzles, respectively to form two molten metal layers 3a, 3b at the upper and the lower parts. Then, the outer layer solidified shell 6a by the molten metal at the upper layer contacting with the roll and the inner layer solidified shell 6b by the molten metal at the lower layer are formed and the solidified shells in these inner and outer layers are integratedly composed at a roll kiss point 7 or at the front or the rear parts thereof to produce the clad steel sheet. By this method, the formed solidified shells are composed at the roll kiss point, and the complex layer cast sheet having the prescribed sheet thickness is continuously obtd. and the process of hot-rolling, etc., can be saved and the improvement of the productivity and the reduction of the cost are 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 an alternative technology,
Recently, a technique of directly producing a multi-layer metal material, that is, a clad steel plate by continuous casting has been adopted.

FIG. 2 is a diagram showing an example of this technique.
Two long and short injection nozzles 12a in a rectangular cooling mold 11,
12b is dipped, and different kinds of molten metal are injected into the injection nozzles, respectively, and the molten metal layer 13 of upper and lower two layers is formed in the pool 13.
a and 13b are formed.

In this case, molten metal having a relatively low density is injected from a short injection nozzle 12a immersed in the upper layer side of the basin 13 to form an upper molten metal layer 13a,
Molten metal having a high density is injected from a long injection nozzle 12b immersed in the lower layer side to form a lower molten metal layer 13b.

Here, first, the upper molten metal layer 13a is cooled by the cooling mold 11, is drawn downward while forming the outer layer solidified shell 14a, and then the lower molten metal layer 13b is cooled by the outer layer solidified shell 14a. The inner layer solidified shell 14b is formed inside the outer layer solidified shell 14a, and the inner layer solidified shell 14b is integrally pulled out to form a multilayer cast slab 1
It becomes 5.

[0007]

By the way, the multi-layer cast slab 15 produced in this manner is an extremely thick slab having a cast thickness of 100 mm or more. To make this a practical clad steel plate, Furthermore, it is necessary to go through processes such as hot rolling and cold rolling, and many problems are involved and the problem of high cost cannot be solved.

The present invention has been made in view of the above problems.
Provided is a continuous casting method for producing a clad steel plate by twin roll type continuous casting for producing a thin plate slab.

[0009]

According to the present invention, two pouring nozzles having different lengths are immersed in a molten metal pool formed by two rolls and side dams provided on both end faces of the rolls, and the pouring is performed. Injecting different kinds of molten metals into the nozzles to form upper and lower two layers of molten metal in the pool, and forming an outer layer solidified shell by the upper layer of molten metal in contact with the roll,
A continuous casting method for a clad steel sheet by twin rolls, characterized in that an inner layer solidified shell is formed by the molten metal of the lower layer, and the clad steel sheet is manufactured by integrally compounding the solidified shells of the inner and outer layers at or before and after the roll kiss point. Is.
Further, in the present invention, the density of the molten metal in the upper layer needs to be lower than the density of the molten metal in the lower layer.

[0010]

According to the present invention, in a continuous casting apparatus for twin-roll thin plate slabs known as the Bessemer method, the length of the molten metal pool formed by two rolls and side weirs provided at both end faces of the rolls. 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.

In this case, the molten metal having a relatively low density is injected from the short injection nozzle immersed in the upper layer side of the basin to form the upper molten metal layer, and the long injection nozzle immersed in the lower layer side. A molten metal having a high density is injected from the above to form a lower molten metal layer.

Here, the upper molten metal layer is first guided downward while being cooled by a roll to form an outer layer solidified shell, and the lower molten metal layer cooled by the subsequently formed outer layer solidified shell is then outer layer solidified. An inner layer solidified shell is formed inside the shell, and the solidified shells of the inner and outer layers are integrally compounded at the roll kiss point or before and after the roll kiss point to form a multi-layer cast piece, and a clad steel plate is manufactured.

As the molten metal injected here, the molten metal forming the upper molten metal layer, that is, the outer layer solidified shell is more than the lower layer molten metal forming the inner layer solidified shell in order to avoid mixing in the pool. Also needs to be a metal with a low density.

[0014]

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 end faces of the rolls. The molten metal of different types is injected from both nozzles, respectively, and the molten metal layers 3a and 3 of the upper and lower two layers are filled in the pool 3 of the molten metal.
b is formed.

In this case, the molten metal having a relatively low density is injected from the short injection nozzle 4a which is immersed in the upper layer side of the basin 3 to form the upper molten metal layer 3a, which is then immersed in the lower layer side. The molten metal having a high density is injected from the long injection nozzle 4b to form the lower molten metal layer 3b.

Here, first, the upper molten metal layer 3a is cooled by the roll 1, starts to solidify from the solidification start point 5a in contact with the molten metal surface, and is guided downward while forming the outer layer solidification shell 6a.

The lower molten metal layer 3b cooled by the subsequently formed outer layer solidified shell 6a begins to solidify from the solidification start point 5b at which the molten metal layer 3 of the lower molten metal layer 3 contacts the outer layer solidified shell 6a and the inside thereof. Inner layer solidified shell 6b
The solidified shells 6a and 6b of the inner and outer layers are integrally compounded at the roll kiss point 7 or before and after the roll kiss point 7 to form a multi-layer cast slab 8 to manufacture a clad steel plate.

The clad steel plate manufactured in this manner is formed into a thin-plate multi-layer cast slab having a substantially predetermined plate thickness at the roll kiss point 7. Therefore, the clad steel sheet can be sufficiently put into practical use only after a few cold rolling steps without further steps such as hot rolling.

[0020]

As described above, according to the present invention, two pouring nozzles are immersed in the molten metal pool, and different kinds of molten metals are injected into the pouring nozzles to form solidified shells for the inner and outer layers. This is an integrated composite that directly produces a clad steel plate from molten metal, and a thin-plate multi-layer slab of approximately the specified plate thickness can be obtained at the roll kiss point, so steps such as hot rolling are omitted. Therefore, the productivity of the clad material can be improved and the manufacturing cost can be gradually reduced.

[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 side view showing an example of a conventional continuous casting apparatus for producing a clad steel material.

[Explanation of symbols]

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

Claims (2)

[Claims] 1. A basin formed by two rolls and side weirs provided on both end faces of the rolls has different lengths.
The book injection nozzle is dipped, and different kinds of molten metals are injected into the injection nozzles to form upper and lower two molten metal layers in the pool, and the outer layer solidified shell is formed by the upper molten metal in contact with the roll. And the inner layer solidified shell is formed by the molten metal of the lower layer, and the solidified shell of the inner and outer layers is integrally compounded at or before and after the roll kiss point to produce a clad steel sheet. Casting method. 2. The continuous casting method for a clad steel plate by twin rolls according to claim 1, wherein the method is carried out under the condition that the density of the molten metal in the upper layer is smaller than the density of the molten metal in the lower layer.