JPH0331474Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a tundish for continuous casting that can reduce the amount of remaining metal in the tundish at the end of casting in continuous casting operations.

(Prior art) It is generally well known that in continuous casting operations, when multiple different charges are continuously cast using the same tandate, quality deterioration occurs at the joint between the charges due to air oxidation and slag suspension. It is being

In addition, when carrying out multiple casting, the components of the front charge and the after charge are different, so-called different composition multiple casting, in order to reduce the occurrence of component-defective slabs due to the mixing of components in the tundish, the molten steel of the previous charge is It is preferable to minimize the amount of remaining hot water.
However, conventional tandates have a flat-bottomed shape and a uniform depth, so if the remaining molten steel is too small, the slag floating on the surface of the tandate will be caught up in the injection flow and flow into the mold, significantly deteriorating the quality of the slab. In order to prevent slag from flowing out, ensure that there is enough remaining hot water in the tundish to prevent slag from flowing out.
It is customary to perform multiple casting with different components by discarding or demoting the component-defective slab portion of the component mixture caused by this residual metal.

However, Japanese Unexamined Patent Publication No. 1458/1983 is known as a method proposed to improve such problems.

As shown in Fig. 5, this method is made by sequentially pouring molten metal into a mold and continuously casting, while preventing the mixing of different molten metals in a tundish with a movable weir 5d. The aim is to reduce the occurrence of

However, in the case of this movable weir type tundish, in addition to the increase in the cost of the tundish equipment, it is necessary to move the movable weir every time a different type of molten metal is poured, and maintenance of the refractories of the tundish and the movable weir is required. This mobile weir has the drawback that it requires a lot of manpower in actual operation, such as the need to carefully perform the steps, and the distance between the ladle nozzles cannot be minimized due to the presence of ladle nozzles, so the amount of mixed molten metal is small. Currently, the number of slabs with defective components has not been significantly reduced.

(Problems to be solved by the invention) In view of the above, the present invention is capable of eliminating component-defective slabs through mixing in multiple continuous casting of different components, while avoiding an increase in the cost of tundish equipment and without requiring operational manpower. The aim is to minimize the amount generated.

(Means for Solving the Problems) The present invention has been made to advantageously solve the above-mentioned problems, and its gist is that in a tundish for continuous casting, the part that receives molten steel from the ladle. , at least one weir is provided between the portions of the injection holes in the mold, and a local recess is provided immediately below the weir that extends on both sides of the weir and is deeper than the bottom of the tundish, and the bottom of the weir is connected to the recess. This invention relates to a tundish for continuous casting characterized by being constructed by immersion.

(Example) The present invention will be explained in detail below using examples shown in the drawings.

Figure 1a is a side view showing the configuration of the present invention, and Figure 1b is a plan view thereof.In the figure, 1 is a ladle, 2 is a long nozzle for injecting molten steel from ladle 1 into tundish 3, and 4 is a long nozzle for injecting molten steel from ladle 1 into tundish 3. Bottom, 5a, 5
b and 5c are weirs that separate the part that receives molten steel from the ladle and the part that has the injection hole into the mold.The illustrated example shows one weir on the left side and two weirs on the right side, with the center of tandem 3 as the border. However, it is intended that one or two sheets may be placed on each side.

6 is an injection nozzle connected to an injection hole provided in the tundish 3; 7 is a stopper that opens and closes the injection hole by moving up and down, and stops the supply of molten steel in the tundish to the mold.

Reference numerals 8a, 8b, and 8c are local recesses formed directly below the weirs 5a, 5b, and 5c, respectively, on both sides of the weirs, and deeper than the bottom surface 4 in a part of the bottom of the tundish 3. In addition, as shown in FIG. 1a and FIG.
The bottom of each of a, 5b, and 5c is the tundish tray 3.
They are formed so as to protrude from the bottom and be immersed in the recesses 8a, 8b, and 8c.

As will be described later, the size of the concave portions 8a, 8b, and 8c corresponds to the amount of remaining metal at the end of pouring, and the larger the size, the more component-defective slabs will be produced during continuous casting of different components, so they should be made as small as possible. is essential.

However, the tundish 3 formed in this way
When the pre-charged molten steel is supplied from the injection nozzle to the mold using the
Molten steel is inside the bottom surface 4 of the tundish 3 in b and 8c.
Since the remaining metal reaches the height of , the recesses 8a, 8
By the weirs 5a, 5b, and 5c immersed in the weirs 5a, 8c, the slag existing on the surface of the molten steel is reliably prevented from flowing out to the injection hole side and remains inside the weir partitioned by the weirs.

As a result, the molten steel in the tundish 3 can be almost completely cast without increasing inclusions in the slab and leaving only a very small amount of residual metal in the recessed portion.

Next, the post-charge molten steel, which has a different composition from the pre-charge, is passed from the ladle 1 through the long nozzle 2 to the weir 5.
When the molten steel is supplied between a and 5b, there is no pre-charged molten steel in this area, only slag exists, and there is no pool of molten steel, so the supplied molten steel is hardly suspended in the slag. The slag is swept aside by the injection flow, but is blocked by the weirs 5a and 5b, and does not flow toward the injection hole, leaving only the molten steel in the concave portion 8.
It passes through the weirs 5a and 5b whose bottoms are immersed in the weirs 5a and 8b, flows out to the injection hole side, and is supplied to the mold from the injection nozzle 6, where continuous casting of different steel types is performed.

However, since only a very small amount of molten metal remains in the recesses 8a and 8b from the pre-charge in the tundish 3, compositional defects may occur due to mixing with the molten steel from the post-charge, which has a different composition. The length of the slab is affected by the amount of remaining molten metal corresponding to the internal volume of the concave portions 8a and 8b, and is equal to the amount of molten steel to be charged after charging.The position where the weir and concave portion are installed is, in the case of a general circular tundish. As shown in FIG. 1, one or more locations may be installed so as to intersect at right angles to the line connecting the ladle injection point and the mold injection point.

Further, one weir may have only one recess, but one or more recesses may be provided as long as the total amount of remaining hot metal does not increase. It is preferable to form the recess at a position where the molten steel from the long nozzle 2 is not directly injected into the recess in order to prevent inclusions in the slab from increasing.

Next, FIGS. 3 and 4 show other embodiments of the present invention, in which the pouring tank from the ladle is independent from the tundish 3.

In FIG. 3, reference numeral 9 denotes independent injection tanks 10a and 11a attached to the tundish 3, which are weirs and recesses formed between the injection tank 9 and the tundish 3.

Normally, only these 10a and 11a are needed, but if it is necessary to further prevent slag from getting mixed in and make the steel clean, weir 10 is added to the tundish 3 as shown in Figure 1.
b. It is preferable to provide a concave portion 11b.

Furthermore, the example shown in Fig. 4 shows the case of a tundish where an injection tank 12 of almost the same shape as the tundish 3 is installed independently, forming a J-degree H-shape. A ladle can be placed at each end at the same time. 1 in the diagram
3a and 14a are the injection tank 12 and the tundish 3
There is a weir and a recess provided in between.

Note that 13b and 14b are provided to have the same meaning as 10b and 11b in FIG. That is, weir 13
Even if multiple casting of different components is carried out by simply arranging one set of the slag a and the concave portion 14a, the slag only remains in the injection tank 12 and does not flow into the tundish 3. If even higher cleanliness is required, a weir 13b and a concave portion 14b are arranged within the tundish 3.

Next, we will give an example of operation.

The tundish used is the one shown in Fig. 1 (the supporting weir 5c and the concave part 8c are omitted), and the amount of molten steel received is 15.
tmax. The volumes of the concave portions 8a and 8b were each 0.07 m ³ (each weighing 0.5 t in terms of molten steel weight).

When the pre-charged molten steel was completely poured into the mold from the injection nozzle 6, a total of 1.0 t of molten steel remained as residual metal only in the concave portions 8a and 8b.

In contrast, a conventionally known movable weir 5 shown in FIG.
In the case of a tundish with the same capacity in which slags 5d and 5d are arranged, the limit amount of remaining hot water that can be injected into the mold from the injection nozzle 6 without causing slag to flow out is the amount remaining at the movable weirs 5d and 5.
3.5t even when d is brought closest to long nozzle 2
It was hot.

(Effects of the invention) As explained in detail above, according to the invention, not only can the occurrence of slabs with defective composition be greatly reduced during continuous casting of different steel types, but also the presence of residual metal from the previous charge at the injection point during post-charge injection. Therefore, suspension of molten steel and slag does not occur. Furthermore, since the combination of the weir and the concave part allows automatic separation of slag and molten steel, non-metallic inclusions in the slab are greatly reduced and the quality of the slab is significantly improved. In addition, since there is no need to move the weir in terms of equipment, it can be done at low cost, and there is no need for any manpower to move the weir, resulting in great industrial effects.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an embodiment of the present invention, Fig. 2 is a partial explanatory diagram showing the configuration of the present invention, Figs.
The figure is an explanatory diagram showing another embodiment of the present invention, and FIG. 5 is an explanatory diagram showing a conventional example of a tundish equipped with a moving weir. DESCRIPTION OF SYMBOLS 1... Ladle, 2... Long nozzle, 3... Tundishu, 4... Bottom surface, 5... Weir, 6... Injection nozzle, 7... Stopper, 8... Recessed part, 9...
...Injection tank, 10...Weir, 11...Concave part, 12...
...H-type tundish, 13...Weir, 14...Concave part.

Claims (1)

[Scope of utility model registration request] In a tundish for continuous casting, at least one weir is provided between the part that receives molten steel from the ladle and the part where the injection hole to the mold is located, and the bottom of the tundish is provided directly below the weir and extends on both sides of the weir. 1. A tundish for continuous casting, characterized in that a deeper local recess is provided and the bottom of the weir is immersed in the recess.