JPH081319A - Lower nozzle for sliding nozzle - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to improve the durability by applying it to steel grades, etc., where the durability was low in the conventional nozzle composed of only one material, and it is possible to keep the nozzle manufacturing cost low . [Structure] Two or more different materials are intentionally mixed and placed in one upper nozzle solid, and molded, no calcination process is required, and mortar, castable, etc. are used for joining the different materials. It is characterized by not going through. [Effects] The lower nozzle according to the present invention enables durability and cost reduction by combining a material having high corrosion resistance in an important part and a cheap material in an unimportant part. This can contribute to the reduction of the original unit price in the steelmaking process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lower nozzle used as a sliding nozzle for controlling the flow rate of molten steel.

[0002]

2. Description of the Related Art When flowing molten steel from a ladle to a tundish, or from a tundish to a mold, a sliding nozzle plate (hereinafter referred to as an SN plate) installed at the bottom of the ladle or tundish is used. The flow rate is controlled.

The SN is generally constructed by disposing an upper nozzle and a lower nozzle above and below the plate as a center. Conventionally, the lower nozzle disposed here is mainly made of a material such as high alumina or alumina carbon. However, the following problems occur when such a single material is used.

Due to the flow of molten steel and the oxygen cleaning at the time of cleaning the residual molten steel in the nozzle hole, the nozzle hole diameter increases (melting loss) and the risk of molten steel leakage arises. In order to prevent this melting loss, a method of increasing the fire resistance of the raw material forming the nozzle is generally used. However, if the refractory level is increased, a rapid thermal shock due to the molten steel flow causes a crack around the nozzle hole, which increases the risk of leakage of the molten steel.

From the above viewpoints, the lower nozzle used for the SN is required to have thermal shock resistance and excellent melting damage resistance. However, it is difficult to satisfy the above with a single material as described above.

[0006]

As a means for solving the above problems, a method (so-called ring method) in which a material having a high refractory degree (a zirconia or the like) formed in a cylindrical shape only around the nozzle hole is arranged is used. Is well known. The material of the outer edge is joined via mortar or castable. However, in the case of this ring system, the wall thickness of the ring becomes thin, or the wall thickness of the outer edge portion becomes thin. In this case, it is difficult to secure the strength of each part, and cracks may occur due to thermal shock due to molten steel, causing leakage of molten steel. Further, the work of joining the rings and the work of casting by casting are troublesome and cause a cost increase.

[0007]

SUMMARY OF THE INVENTION The present invention aims to solve the above problems. The details are given below. INDUSTRIAL APPLICABILITY The present invention is arranged and molded in one upper nozzle solid without intentionally mixing two or more different materials, does not require a firing step, and joins the different materials with mortar or castable. It is characterized by not going through.

[0008]

The refractory material forming the nozzle brick is selected from alumina carbonaceous material, high alumina material, magnesia material, zirconia material, etc., and the combination of the material systems is not limited (for example, alumina carbon material and alumina carbon material). , A combination of alumina carbon quality and magnesia carbon quality, etc.). In general, a material having more excellent melting damage resistance is selected for the important portion around the nozzle hole, and a relatively inexpensive material is applied to the outer edge portion thereof. A nozzle in which these materials are combined is formed by a high pressure press at the same time as molding, and then used without undergoing a step such as firing.

In the product of the present invention, a material having excellent melting resistance is selected for the important portion around the nozzle hole, so that it can be applied to steel grades, etc., which had a low durability in the nozzle composed of only one material in the past, and the durability is improved. It is possible to Further, a relatively inexpensive material can be applied to the non-important portion of the outer edge portion, and since the casting work such as mortar set and castable may be eliminated, the manufacturing cost of the nozzle can be kept low. Examples will be described below with reference to the drawings.

[0010]

EXAMPLE As shown in Table 1, two different material combinations were applied to the nozzle hole peripheral portion 1 and its outer edge portion 2, and the unfired lower nozzle formed simultaneously during molding was actually used. As a result, the durability improvement as shown in Table 2 was obtained.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

As described above, in the lower nozzle according to the present invention, by combining a material having high corrosion resistance in the important part and a cheap material in the non-important part, the durability and cost can be reduced. This can contribute to the reduction of the original unit price in the steelmaking process.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of a lower nozzle of the present invention.

FIG. 2 is a vertical cross-sectional view of another embodiment of the lower nozzle of the present invention.

FIG. 3 is a vertical sectional view of another embodiment of the lower nozzle of the present invention.

FIG. 4 is a vertical sectional view of another embodiment of the lower nozzle of the present invention.

[Explanation of symbols]

 1 Nozzle hole peripheral part (important part) 2 Outer edge part (non-important part) 3 Nozzle hole 4 Iron skin

Claims (3)

[Claims] 1. A lower nozzle for a sliding nozzle, characterized in that the peripheral portion (important portion 1) and the outer edge portion (non-important portion 2) of a nozzle hole through which molten steel passes are made of different materials. 2. The lower nozzle for a sliding nozzle according to claim 1, wherein the material is unfired. 3. The lower nozzle for a sliding nozzle according to claim 1, wherein the joint portion of the materials 1 and 2 is formed simultaneously at the time of molding without using mortar, castable or the like.