JP2001018037A - Method and apparatus for continuously casting complex layer cast slab - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously cast a complex layer cast slab at a low cost by pouring molten steel for inner part into a hollow part surrounded with a solidified shell which pours, cools and forms molten steel for surface layer into a space formed with a mold for cooling the outer surface and a mold for cooling the inner surface while cooling the outer surface and the inner surface of the surface layer part in the cast slab, and cooling the molten steel for inner part with the solidified shell of the surface layer part. SOLUTION: The molten steel 5 for surface layer part of the cast slab, is poured into the space formed with the mold 2 for cooling the outer surface of the surface layer part in the cast slab and the mold 3 for cooling the inner surface of the surface layer part in the cast slab. The outer surface and the inner surface of the surface layer part 1 in the cast slab are cooled to form the solidified shell 4 of the surface layer part in the cast slab. When the solidified shell 4 is drawn out downward from the mold, the hollow part surrounding the periphery with the solidified shell 4 is formed. The molten steel 11 for inner part in the cast slab is poured into the hollow part and cooled with the solidified shell 4 to form the solidified shell 10 of the inner part in the cast slab. The solidified shell 4 of the surface layer part in the cast slab and the solidified shell 10 of the inner part in the cast slab are integrally and continuously drawn out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for continuously casting a multilayer slab in which the composition of the surface layer of the slab differs from the composition of the inside of the slab.

[0002]

2. Description of the Related Art Conventionally, when manufacturing a multilayer slab having a composition different from that of a surface layer portion, the metal material for slab interior is placed at the center of an ingot casting mold, and the metal material and the mold And a method of injecting and solidifying molten steel for a slab surface layer portion. Since this method is limited to the ingot making method, the productivity is low and the yield is low. Moreover, since the temperature of the metal material for the inside of the slab placed in the mold is low, there is a problem that it does not sufficiently adhere to molten steel.

In the case of producing a multilayer slab by a continuous casting method, there is a method of producing a multilayer slab by providing an electromagnetic brake in a mold and separating and retaining molten steel having different components in the mold. . In this method, it is difficult to sufficiently separate the molten steel in the mold by the electromagnetic brake, and the injection amount of the molten steel and the casting speed of continuous casting must be controlled in order to control the thickness of the surface layer. There is a problem in practical use.

Japanese Patent Application Laid-Open No. 63-268543 discloses a pouring nozzle of a continuous casting machine for producing a solid cast piece by passing a core material through the center of the cast piece and injecting molten steel around the core material. I have.
However, also in this case, there is a problem that the core material does not sufficiently adhere to the molten steel because the temperature of the core material passing through the center of the slab is low as in the ingot making method described above.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a continuous method of producing a multi-layer cast slab in which the composition of the surface layer portion and the inner portion differ from each other at low cost and in large quantities. It is an object to provide a casting method and apparatus.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method of continuously casting a multilayer slab in which the composition of the surface layer of the slab is different from the composition of the inside of the slab. Inject the molten steel for the slab surface layer into the space formed by the mold and the inner surface cooling mold that cools the inner surface of the slab surface layer, and cast the molten steel for the slab surface layer into the outer surface cooling mold and the inner surface cooling mold. Cooling to form a solidified shell, then injecting molten steel for slab internal into the hollow part surrounded by the solidified shell on the slab surface layer, Is cooled to form a solidified shell inside the slab, and the solidified shell at the surface layer of the slab and the solidified shell inside the slab are integrally pulled out.

The present invention also provides an outer surface cooling mold for cooling the outer surface of a slab surface layer and an inner surface cooling mold for cooling an inner surface of the slab surface layer portion, wherein the outer surface cooling mold and the inner surface cooling mold are provided. A slab surface layer part immersion nozzle and a slab surface layer part tundish for injecting the slab surface layer part molten steel into the space formed by This is a continuous casting apparatus in which a slab internal immersion nozzle for injecting slab internal molten steel and a slab internal tundish are provided in a portion.

[0008]

FIG. 1 is a longitudinal sectional view showing a main part of a continuous casting apparatus for a multilayer cast slab according to the present invention. FIG. 2 shows the arrangement of the mold 2 for cooling the outer surface of the slab surface layer 1, the mold 3 for cooling the inner surface of the slab surface layer 1, the immersion nozzle 8 for the slab surface layer, and the immersion nozzle 14 for the slab interior. It is a cross section showing an example.

The molten steel 5 for the surface layer of the slab is fed from the tundish 6 for the surface layer of the slab to the sliding nozzle 7 for the surface layer of the slab.
And, through the slab surface layer part immersion nozzle 8, it is injected into a space formed by the outer surface cooling mold 2 and the inner surface cooling mold 3 of the slab surface layer part 1. Thus, the outer surface and the inner surface of the slab surface layer portion 1 are cooled, and the solidified shell 4 is formed.

When the mold needs to be oscillated, the outer surface cooling mold 2 and the inner surface cooling mold 3 of the slab surface layer portion 1 perform oscillation in conjunction with each other. When the solidified shell 4 of the slab surface layer portion 1 is pulled out below the mold, a hollow portion surrounded by the solidified shell 4 is formed. The slab internal molten steel 11 is injected into the hollow portion. Molten steel for inside of slab 11
Is injected from the slab inside tundish 12 into the hollow portion through the slab inside sliding nozzle 13 and the slab inside immersion nozzle 14. Injected slab internal molten steel 11
Is cooled by the solidified shell 4 of the slab surface layer 1 to form a solidified shell 10 inside the slab 9.

The molten steel 5 for the surface layer of the slab and the molten steel for the inside of the slab
11 has a different composition. Accordingly, a dedicated tundish (that is, a tundish 6 for the slab surface layer portion and a tundish 12 for the slab interior), a sliding nozzle (that is, a sliding nozzle 7 for the slab surface layer portion and a sliding nozzle 13 for the inside of the slab), and an immersion nozzle (That is, the immersion nozzle 8 for the slab surface layer and the immersion nozzle 14 for the interior of the slab) and the like.

The solidified shell 4 of the slab surface layer 1 and the solidified shell 10 of the inside 9 of the slab thus formed are continuously and integrally withdrawn, whereby continuous casting of a multilayer slab can be performed. is there. The slab is a continuous casting machine guide roll 15
Is sent to a straightening machine, a cutting machine or the like in a later process. When starting the continuous casting of the multilayer slab, as shown in an example in FIG. 3, the dummy bar head 16 is attached to the tip of the dummy bar 17 in a state where the injection of the molten steel is stopped.
The mold 2 for cooling the outer surface and the mold 3 for cooling the inner surface of the slab surface layer 1
And into the space formed by

Then, the sliding nozzle 7 for the surface layer of the slab is slid to move the molten steel 5 for the surface layer of the slab from the tundish 6 for the surface layer of the slab through the immersion nozzle 8 for the surface layer of the slab. Outer surface cooling mold 2 and inner surface cooling mold 3 of surface layer
And injected into the space formed. By pulling the dummy bar 17 downward while pouring the molten steel 5 for the slab surface layer portion, a hollow portion surrounded by the solidified shell 4 of the slab surface layer portion 1 is formed.

Then, a sliding nozzle for the inside of the slab
13 by sliding the molten steel 11 for slab inside from the tundish 12 for slab inside through the immersion nozzle 14 for slab inside, and the hollow portion surrounded by the solidified shell 4 of the slab surface layer 1 Inject into In order to prevent harmful impurities from being mixed between the inner surface of the slab surface layer 1 and the outer surface of the slab interior 9, between the inner surface cooling mold 3 of the slab surface layer 1 and the solidified shell 4 It is desirable to use a graphite-based solid lubricant (for example, repseed oil or the like) as the lubricant to be supplied to the device. Generally used powder contains metal oxide as a main component, so that nonmetallic inclusions are generated inside the slab, and the slab surface layer 1 and the slab interior 9
Not only does this significantly impair the adhesion to the steel, but also causes defects during rolling after continuous casting.

[0015]

[Example] JIS standard SM4 as molten steel 5 for slab surface layer
Continuous casting of a multilayer cast slab was performed using molten steel having a composition equivalent to 00 and molten steel 11 for the inside of the slab as the molten steel 11 for slab internals. The cross section size of the multilayer slab is 310mm in thickness and width
The casting speed was 0.4 m / min. As a lubricant supplied to the molten steel 5 for the slab surface layer portion, repseed oil was used.

As a result, the thickness change of the slab surface layer 1 is ± 2.
mm, and the variation was suppressed to about 1/10 compared to the continuous casting method using an electromagnetic brake. The productivity was more than 10 times that of the ingot making method.

[0017]

According to the present invention, a multi-layered slab in which the surface layer portion of the slab and the inside of the slab having different compositions are sufficiently adhered can be mass-produced at low cost by continuous casting.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a continuous casting apparatus for a multilayer cast slab according to the present invention.

FIG. 2 is a cross-sectional view showing an example of the arrangement of an outer surface cooling mold, an inner surface cooling mold, a slab surface layer immersion nozzle, and a slab interior immersion nozzle of the present invention.

FIG. 3 is a cross-sectional view showing a state in which a dummy bar head and a dummy bar are inserted into the continuous casting apparatus for a multilayer slab of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 cast slab surface layer 2 mold for cooling the outer surface of slab surface layer 3 mold for cooling the inner surface of slab surface layer 4 solidified shell of cast slab surface layer 5 molten steel for cast slab surface layer 6 tundish for cast slab surface layer 7 casting Sliding nozzle for single surface layer 8 Immersion nozzle for surface layer of slab 9 Inside slab 10 Solidified shell inside slab 11 Molten steel for slab inside 12 Tundish for slab inside 13 Sliding nozzle for slab inside 14 For slab inside Immersion nozzle 15 Guide roll 16 Dummy bar head 17 Dummy bar

Claims (2)

[Claims] In a continuous casting method of a multilayer slab having a composition of a slab surface layer portion and a composition of a slab interior portion different from each other, an outer surface cooling mold for cooling an outer surface of the slab surface layer portion and the slab surface layer portion The slab surface layer portion molten steel is poured into a space formed by the inner surface cooling mold that cools the inner surface of the slab, and the slab surface layer portion molten steel is cooled using the outer surface cooling mold and the inner surface cooling mold. To form a solidified shell, and then inject molten steel for the inside of the slab into a hollow portion surrounded by the solidified shell of the slab surface layer portion, and the inside of the slab is solidified by the solidified shell of the slab surface layer portion. Cooling the periphery of the molten steel for use to form a solidified shell inside the slab, and integrally pulling out the solidified shell at the surface layer of the slab and the solidified shell inside the slab. A continuous casting method for slabs. 2. An outer surface cooling mold for cooling an outer surface of a slab surface layer portion and an inner surface cooling mold for cooling an inner surface of the slab surface layer portion, wherein the outer surface cooling mold and the inner surface cooling mold are provided. And a slab surface layer part immersion nozzle and a slab surface layer part tundish for injecting the slab surface layer part molten steel into the space formed by the slab surface layer part, and the periphery was surrounded by the slab surface layer part. A continuous casting apparatus for a multilayer slab, comprising a slab interior immersion nozzle for injecting a slab interior molten steel into a hollow portion and a slab interior tundish.