JPH04104254U - Tundish for continuous casting - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent slag in the tundish for continuous casting from flowing into the mold. [Structure] A weir is installed in the tundish to separate the inflow chamber into which molten steel flows from the ladle and the outflow chamber into which molten steel flows out into the mold. It is installed facing upwards against the flow. [Effect] Due to the relationship between the inner diameter of the communicating hole, the angle of inclination, and the thickness of the weir, the slag on the surface of the molten steel does not go over the inclined communicating hole, so it stays in the inflow chamber and the slag does not flow into the mold. .

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to a tundish for continuous casting.

0002

[Conventional technology]

In continuous casting, molten steel is charged from a ladle into a tundish. It is then cast into a mold. The role of the tundish is to control the level of hot water inside the mold. In addition, prevent slag or nonmetallic inclusions contained in molten steel from flowing into the mold. Trapping the sea urchin in the tundish and, in case of continuous casting, between ladle changes. , to hold the molten steel to be supplied to the mold, etc.

0003 In order to prevent the above slag or non-metallic inclusions from flowing into the mold, A weir is installed inside the tundish. Molten steel is placed in the mold at the bottom of the tundish. There is an immersion nozzle for casting the ladle, but inside the tundish there is a weir that prevents the ladle from being cast. It is divided into a chamber that receives molten steel (inflow chamber) and a chamber equipped with an immersion nozzle (outflow chamber). be divided. The height of the weir is higher than the molten metal level, and a hole for communicating molten steel is provided at the bottom. There is. If there is no weir, the slag that has entered the tundish will be washed away by the vortex along with the molten steel. Flow into the mold.

0004 In a steady state, the hot water level in the tundish is higher than the communicating hole, so the tundish The slag that flows into the weir is blocked, stays in the inflow chamber, and does not come out of the weir. No leakage into the mold. Also, if the hot water level drops when replacing the ladle, the communication hole is installed at the bottom of the weir, so slag does not come out of the weir.

[0005]

[Problem that the idea aims to solve]

However, in order to improve the yield of slabs relative to molten steel, casting is finished. When squeezing the molten steel in the tundish to pour as much as possible, or when changing the ladle. When the molten metal level drops below a predetermined level during replacement, slag flows out of the weir and into the mold. There may be an influx.

[0006] The present invention was developed in view of the above circumstances, and the top layer with the communicating hole is Even if the hot water level drops below the level, there is less risk of slag flowing out of the weir. , thus preventing slag from flowing into the mold. The aim is to provide support.

[0007]

[Means and actions to solve the problem]

The tundish for continuous casting according to the present invention is a continuous casting tundish in which molten steel is injected from a ladle. an outflow chamber that communicates with the inflow chamber and flows out the molten steel into the mold; A plurality of channels are provided between the outlet chambers and are inclined upward from the inflow chamber to the outflow chamber. It has a weir with a through hole and an intermediate weir that divides the upper part of the inflow chamber into two chambers, and has a tank. The dish wall is characterized by having a slag outlet for removing slag in the inflow chamber.

[0008] The communication hole is provided diagonally, and the slag that accumulates in the inflow chamber is removed from the tundish. The melt level is lowered because the melt is removed from the opening in the wall and kept below a predetermined thickness. There are almost no cases where the slag is thick enough to cross over the slanted communication hole. This reduces the risk of slag flowing out of the weir.

[0009]

【Example】

Embodiments of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 is FIG. 3 is a longitudinal cross-sectional view of the tundish of this embodiment. Also, Figure 2 shows the tandem shown in Figure 1. In the AA cross-sectional view of the dish 10, molten steel is omitted for clarity. In Figure 1, 8 is a nozzle that flows the molten steel 13 from the ladle 1 into the tundish 10; A submerged nozzle 15 for pouring molten steel into the mold 2 is provided at the bottom of the mold 10. slab In continuous casting, there are usually two immersion nozzles, but in continuous bloom casting, there are two immersion nozzles. The above are provided. The molten steel 13 poured into the mold 1 is absorbed by the mold wall or cooling water. The surface is cooled to form a solidified shell 4.

0010 The tundish is used to prevent oxidation of the molten steel 13 in the tundish and heat dissipation. The shell 10 is provided with a lid 20. This tundish 10 has two molds. However, the present invention is limited by the number of immersion nozzles 15. It's not something you can do. As shown in FIGS. 1 and 2, the inside of the tundish 10 is divided into three chambers by two weirs 21. In other words, the melt flows from the nozzle 8. The inflow chamber 11 into which steel is charged and the communication hole 22 provided from the inflow chamber 11 to the weir 21 are connected. There are two outflow chambers 12 through which the molten steel communicates. In Figure 2, 5 is the immersion nozzle 1 The openings at the bottom of the tundish 5, 6a and 6b remove the slag in the inflow chamber 11. Therefore, the slag outlet 6c provided in the tundish wall is excluded from the openings 6a and 6b. An overflow gutter 7 for guiding the removed slag is located at the inner bottom of the tundish 10. be.

[0011] The vertical cross section of the communication hole 22 is circular, and the weir 21 is provided with a plurality of communication holes 22. Ru. The vertical cross section of the communication hole 22 is not necessarily limited to a circular shape, but may be an ellipse. It's okay. 14 is slag, which is caused by oxidation of molten steel, floating of nonmetallic inclusions, or slag from the ladle. This was caused by the inflow. The intermediate weir 25 provided in the center transfers the slag 14 to the weir 2. This is to keep it between the ladle 1 and the weir 25, and when the ladle is replaced, the next ladle nozzle is inserted into the middle. When inserted into the adjacent inlet chamber separated by the interstitial weir 25, the slug 14 of the previous charge The slag is removed from the opening 6 using a steel rake. This charges the slag. Slag does not accumulate over time, and the thickness of slag can be kept below a predetermined thickness. .

0012 In addition, the lower part of the intermediate weir 25 is higher than the bottom of the tundish 10. As a result, the molten steel in the inflow chamber flowing from the ladle is freely communicated under the intermediate weir, and 2 Molten steel is supplied to each outflow chamber on average.

[0013] FIG. 3 is an enlarged vertical cross-sectional view of the weir 21. As shown in FIG. Are the communication holes 22 both inflow chambers 11? It is provided upward toward the outflow chamber 12.

[0014] The operation of the tundish 10 for continuous casting of this embodiment configured as described above is as follows. explain about. The slag 14 in the inflow chamber 11 is in a steady state where the hot water level is shown in FIG. If the level is , the hot water enters the outflow chamber 12 while remaining deposited on the surface of the inflow chamber 11. There isn't.

[0015] Regarding the behavior of slag, for example, when changing the ladle during continuous casting, A case will be explained in which the melt level falls below the steady state level at the end of casting. Figure 3 Then, the level of the hot water level is at the upper end level L1 inside (inflow chamber side) of the uppermost communicating hole 22a. Consider the case where the value drops to . The slag thickness is S, the inner diameter of the communication hole 22a is D, and the weir 22 is T, and the angle between the communication hole and the horizontal plane is α, then the communication on the outflow chamber 12 side The height H of the opening of the hole 22a is H=D/cosα. of the opening on the outflow chamber side. Assuming that the lower end level is L2, in order to prevent the slag 14 from entering the outflow chamber, (L1 The level of +S) needs to be lower than the level of L2. That is, Ttanα>S+D/cosα……(1) The following conditions are necessary.

[0016] The condition of equation (1) above is not limited to the communication hole 22a, but applies to all communication holes. This is a condition common to 22. Also, as can be easily seen from equation (1) above, the conventional In the horizontal communication hole, α = 0, so regardless of the slag thickness, the outside It flows out to the side.

[0017] Considering the outflow of the slag 14 to the outside of the weir 21, the larger α is better. However, when α is increased, the upper and lower ends of the opening of the communication hole 22 become acute angles, causing mechanically weakening, or the number of holes 22 must be increased to ensure the flow rate of molten steel. You have to think about what you need to do. From this perspective, the upper limit of the inclination angle α is can be determined. Furthermore, all of the communication holes 22 do not necessarily have to be sloped. , the lower communication hole 22 may be horizontal. That is, due to the inclination of the communication hole 22 There is a risk that the molten steel heading toward the outflow chamber 12 will flow upward and be exposed on the molten metal surface. This may promote oxidation of the molten steel. Depending on the operating conditions, it may not be possible to In some cases, ashealing may not be performed sufficiently, so in such cases, the slag thickness should be taken into consideration. Therefore, it is also possible to provide the lower communication hole 22 horizontally or to reduce α. It is effective.

[0018] Next, one specific numerical example of this embodiment will be given. In this example, the ladle exchange Since the slag is removed each time it is replaced, S=about 5 to 15 mm can be set. Also, communication Assuming that the inner diameter of the hole D = 75 mm and the thickness of the weir T = 190 mm, the inclination angle for this example is Determining α from equation (1) above, when S = 5 mm, α > 25°, and S = 15 mm, , α>about 28°. From this value, taking into account fluctuations in the slag thickness S or the molten metal level, , in this example, α=30° would be appropriate.

[0019]

[Effect of the idea]

According to the tundish for continuous casting according to the present invention, the tundish wall is The weir has an opening to remove the molten steel, and a communication hole in the weir so that the flow of molten steel is directed upward. Therefore, the amount of slag flowing out from the tundish into the mold is reduced.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a tundish of this embodiment.

FIG. 2 is a sectional view taken along line AA of the tundish shown in FIG. 1;

FIG. 3 is an enlarged vertical cross-sectional view of the weir shown in FIG. 1;

[Explanation of symbols]

1 Ladle 2 Mold 6a, 6b Slag drainage port 8 Ladle nozzle 10 Tundish 11 Inflow chamber 12 Outflow chamber 13 Molten steel 14 Slag 15 Immersion nozzle 21 Weir 22 Communication hole 25 Intermediate weir

Claims (2)

[Scope of utility model registration request] 1. An inflow chamber into which molten steel is poured from a ladle; an outflow chamber communicated with the inflow chamber and outflows the molten steel into a mold;
A weir provided between the inflow chamber and the outflow chamber and having a plurality of communication holes inclined upward from the injection chamber toward the inflow chamber, and an intermediate weir that divides the upper part of the inflow chamber into two chambers. A tundish for continuous casting, characterized in that the tundish wall has a slag discharge port for removing slag in the inlet chamber. 2. The tundish for continuous casting according to claim 1, wherein, where H is the height of the opening on the outflow chamber side of the communicating hole, Ttanα−H>S.