JPH0683144U - Tundish weir for continuous casting - Google Patents

Abstract

(57) [Summary] [Purpose] When pouring molten steel into a tundish from a ladle in a continuous casting operation, there is a gap between the long nozzle and the bottom of the tundish, causing initial air oxidation and temperature drop. Also, molten steel is scattered, which is prevented. [Structure] Two-piece weir made of lightweight refractory is installed near the injection point of the ladle of the tundish. In order to secure strength against the flow of molten steel, it is installed in a convex state on the injection side. The H-type tundish alternately injects two ladles, but at this time it floats due to the difference in specific gravity from the molten steel, and does not affect the subsequent molten steel flow. [Effect] The molten steel is not scattered at the initial stage, and the long nozzle is immediately immersed, so that air oxidation is reduced and the quality of the cast piece is improved. Further, since the fully open SN injection can be performed, it becomes possible to prevent the molten steel temperature from lowering and to stabilize the operation.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a tundish weir for continuous casting.

[0002]

[Prior art]

 In continuous casting work, it is usual to supply molten steel from the ladle to the tundish and then to the mold. To supply the tundish from this ladle, the molten steel in the ladle is dropped through a long nozzle connected to the bottom of the ladle, but the distance from the tip of the nozzle to the bottom of the tundish is about 200-300 mm. There is an interval, and when the molten steel falls, the molten steel scatters quite radically.

For this reason, (1) throttling injection is required, and the injection flow becomes a divergence, resulting in deterioration of steel quality and temperature decrease due to air oxidation, (2) safety concern for workers, and (3) scattering to nearby facilities. There are problems such as adverse effects. This situation continues until the tundish is filled with molten steel and the tip of the long nozzle is fully submerged in the molten steel, after which no scattering occurs.

As an example, the inner diameter of a tundish having a capacity of 60 t is about 1000 mm (width) × 20 m (length) × 700 mm (depth), and it takes about 4 minutes for the molten steel surface to fully immerse the tip of the long nozzle. The above adverse effects are unavoidable. Japanese Patent Laid-Open No. 1-34551 has been proposed as a proposal for shortening this adverse effect time. This aims to prevent molten steel from scattering by providing a weir near the long nozzle and immersing the tip of the nozzle below the molten metal surface in the shortest possible time.

[0005]

[Problems to be Solved by the Invention] The weir proposed in Japanese Unexamined Patent Publication No. 1-34551 is made of iron, and its surface is oxidized during preheating of the tundish as a preparation for receiving hot water in the tundish. Generates a scale. This scale enters the molten steel and causes the [O]% of the molten steel to rise significantly. In addition, during heating, uneven heating of the weir is likely to occur, and deformation of the iron plate causes a decrease in mounting accuracy, which may make it difficult to secure the molten steel pool time. Further, since it is made of iron, it is a heavy material, and there is a problem that the burden on the operator is great for forming the weir.

[0006]

[Means for Solving the Problems]

 The present invention has been made in order to solve the above problems in an advantageous manner, and its purpose is to provide a weir that separates the tundish receiving part and the outflow part from the vicinity of the receiving point. It has a plane shape with a convex shape toward the hot water receiving point and is higher than the lower end of the long nozzle, and has a height that allows overflow after forming the required amount of hot water pool. This is a weir for a continuous casting tundish, which is made of a light refractory that rises and disappears when the heights of the molten metal surface and the molten metal surface become almost equal.

[0007]

[Action]

 In the present invention, the fact that the weir shape is planar toward the hot water receiving point and the central portion is convex is related to the fact that the material of the weir is a lightweight refractory, and the weir has rigidity to withstand the heavy pressure of molten steel. This is to get it. That is, as shown in FIG. 1 of the embodiment described below, the molten steel poured into the first tank injection point (reception point) 2a first reaches the top of the flow weir 4 as indicated by the arrow. Although the heavy pressure of the molten steel is applied to the top portion, this heavy pressure is strongly applied to the side surface of the tundish 1a and escapes due to the shape of the weir 4, so that it is possible to sufficiently withstand the heavy pressure of the molten steel and form a pool.

The material of the weir is a lightweight refractory, which may rise due to the specific gravity at the time when the molten metal fills the hot water receiving part and the hot water discharging part and the pressures on the hot water receiving side and the hot water discharging side become substantially equal. Possible lightweight refractories are needed. This is because even if the molten steel flows from the tundish to the mold, if the molten steel remains in the pool, it will be cooled and solidified, and the loss and post-treatment will be great. Furthermore, the weir needs to be a material that does not contaminate the molten steel and disappears after it floats. This is to allow the molten steel to flow freely in the tundish.

From this point of view, as a result of various investigations by the inventors of the present application, a refractory sleeve mainly composed of MgO is very convenient, and a bulk specific gravity thereof of about 1.5 to 2.0 is preferable. When installing in the tundish, the refractory sleeve made of the above material is mortar-joined in a V shape, and the bottom surface and both ends are similarly fixed to the inner surface of the tundish with mortar. A lightweight refractory weir made of such a refractory sleeve does not undergo thermal deformation during tundish preheating that is applied before the start of use, so that a molten steel pool can be reliably formed.

[0010]

【Example】

 FIG. 1 is a plan view of an H-type tundish described in Japanese Patent Application Laid-Open No. 61-119358 previously proposed by the applicant of the present application. The first tank tundish 1a is the hot water receiving side and the The second tank tundish 1b is connected by a tunnel 6. 2a is a 1-pot pouring point, 2b is a 2-pot pouring point, and 3a and 3b are pouring points into a mold. Reference numeral 4 denotes a weir of the present invention, in which two MgO-based refractory sleeves are butt-mortar-joined and the central portion is convex toward the pouring point. The weir has a thickness of 70 mm and a height of 300 mm, and this is fixed to the tundish 1a with mortar. 5 is an iron plate weir having a thickness of 22 mm.

Then, as shown in FIG. 2 (AA ′ arrow view of FIG. 1), one ladle is poured from the ladle 7 through the long nozzle 8. The lower end of the long nozzle 8 is located 200 mm from the bottom of the tundish 1a, a molten steel pool is formed on the side of the pouring point partitioned by the weir 4, and the molten steel is effectively prevented from scattering. The molten steel applies heavy pressure to the flow weir 4 as shown by the arrow in FIG. 1, but the shape of the weir 4 can sufficiently withstand this heavy pressure.

The molten steel that overflows the weir 4 is blocked by the iron plate weir 5, flows through the tunnel 6 to the tundish (melting side) of the second tank, and is supplied to the mold from the injection points 3a and 3b. Then, when the pouring from the ladle on the side of 1st pan is completed, continue pouring from the pouring point 2b on the side of 2nd pan in the same manner as on the side of 1st pan. As a result, the weir 4 floats up and disappears when the molten metal levels on both sides of the weir 4 become substantially equal. The iron plate weir 5 also disappears when the molten metal pools on both sides of the weir 5 become substantially equal after the formation of the pool.

FIGS. 3 and 4 are examples in which the weir of the present invention is arranged in a one-tank type tundish, FIG. 3 is a plan view, and FIG. 4 is a side view. In the figure, 10 is a tundish, 11 is a molten steel pouring point, 12a and 12b are injection points into a mold, 13a and 13b are weirs of the present invention, which have the same material, size and shape as the weir 4 of FIG. The distance between the tip of the long nozzle 8 arranged at the bottom of No. 7 and the bottom of the tundish 10 is 200 mm. Formation of a puddle after pouring molten steel from the ladle 7 and floating and disappearance of the weirs 13a and 13b proceed in the same manner as in FIG.

[0014]

[Effect of device]

 As described above, according to the present invention, unlike the iron plate weir, no scale is generated during preheating of the tundish, so that molten steel contamination does not occur and thermal deformation does not occur, so that the function of the weir can be reliably exhibited. For this reason, molten steel scattering and air oxidation are greatly improved.

Further, since it is lightweight, the burden on the weir forming operator is small, and the cost can be reduced to 1/2 or less of the iron plate weir, which is a great industrial effect.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment applied to a two-tank type tundish.

FIG. 2 is a view taken along the line AA ′ of FIG.

FIG. 3 is a plan view showing an example of application to a one-tank tundish.

FIG. 4 is a side view showing an example of application to a one-tank type tundish.

[Explanation of symbols]

1a: 1st tank tundish, 1b: 2nd tank tundish, 2a: 1 pot side pouring point, 2b: 2 pot side pouring point, 3a, 3b: mold injection point, 4: lightweight refractory weir , 5: iron plate weir, 6: tunnel, 7: ladle,
8: Long nozzle, 10: Tundish, 11: Pouring point, 12a, 12b: Mold injection point, 13a, 13
b: Lightweight refractory weir.

Claims (1)

[Scope of utility model registration request] 1. A weir for partitioning a hot water receiving part and a hot water discharging part of a tundish, which is provided in the vicinity of the hot water receiving point and has a planar shape with a convex central part toward the hot water receiving point and a lower end of the long nozzle. It is taller than the position and has a height that allows overflow after the required amount of basin is formed. From a lightweight refractory that rises and disappears when the height of the molten metal in the hot water receiving part and the hot water discharging part become almost equal. A tundish weir for continuous casting, which is characterized by