JPS633731Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the structure of a continuous casting tandy, which is a buffer container located between a molten steel ladle and a continuous casting mold.

Conventionally, the molten steel flow in the tandate is directed upward,
Weirs made of refractories are often installed for the purpose of promoting the floating of inclusions, and as shown in Figure 1, weirs are installed at the location where the long nozzle 3 of the molten steel ladle 2 is inserted and at the bottom of the tundish 1. Continuous casting nozzle 4
In many cases, an upper weir 6 and a lower weir 7 which cross the tundish are provided between the tundish so that the upper weir 6 is on the long nozzle 3 side, and the inclusions are stopped by the upper weir 6. Note that 8 is molten steel. This structure is made of continuous cast material,
Especially in cold header material, the surface layer of the slab is approximately 10
This is to solve problems such as cracks occurring during secondary processing of wire rods due to inclusions trapped on the order of m/m.

Inclusions in slabs are caused by oxidation of molten steel due to splash when pouring molten metal from a pot into a tundish, falling off of tundish lining material, oxidation of molten steel when pouring molten metal from a tundish into a mold, incorporation of powder, etc.

A tundish with the above-mentioned structure has conventionally been used to reduce the inclusion of inclusions generated in the tundish. However, in order to minimize the amount of molten metal remaining in the tundish at the end of casting, Although the height is limited and a low weir is effective during steady operation, i.e. when the tundish hot water level is stable, a low weir is effective when the hot water level is low at the beginning or end of casting when changing the ladle. Because the weir is low, it is not possible to take the necessary time for the inclusions to float in the tundish, and the inclusions end up entering the mold from the tundish. As a result, the level of the molten metal in the mold fluctuates, and the inclusions that flow into the mold from the tundish and are captured by the powder are thrown into the molten steel. In this way, the effectiveness of the weir is reduced during unsteady operations such as when changing the pot, at the beginning of casting, and at the end of casting.

Furthermore, since the lower weir is provided, even if the height of the lower weir is low, it is inevitable that molten metal will remain in the tundish at the end of casting, and there is a drawback that the casting yield cannot be improved.

The purpose of the present invention is to provide a molten metal container such as a tundish that solves the above-mentioned drawbacks.
As a countermeasure against inclusions, a weir 5 was installed to prevent splashing and a weir to create a floating flow was installed in order to suppress the generation of inclusions, and an opening was provided at the bottom of the weir as a measure against yield reduction.

Therefore, the present invention provides a container for molten metal that is lined with refractory material and is equipped with a weir made of refractory material, and has a molten metal outlet at the bottom of the container between the receiving side and the tapping side. This is a container for molten metal, which is provided with a lower weir and whose outlet is shielded by a metal plate that melts into the molten steel.

Next, one embodiment of the present invention will be described using FIGS. 2 to 4.

Generally speaking, there are two methods for pouring molten steel from a ladle into a tundish: one uses a long nozzle to prevent molten steel from oxidizing, and the other uses an air-insulated immersion pipe.

To explain the case of the long nozzle shown in FIG.
m, the inner diameter is 200 to 300 m/m, and the thickness is about 50 m/m, and an upper weir 6 and a lower weir 7 made of refractory are provided between the continuous casting nozzle 4 and the cylindrical weir 5.

A semicircular (diameter 80 m/m) molten metal outlet 12 is provided in the lower central part of the lower weir 7 as shown in FIG.
As shown in FIG. 4B, the iron plate 13 is fixed with a castable 14. On the other hand, when injecting using the gas-insulated immersion pipe 9 shown in FIG. 3, a cylindrical weir 5 having the shape shown in FIG.
600~800m/m, inner diameter is 300~400m/m, thickness is
It is fixed at about 70m/m. A lower weir 7, an upper weir 6, a lower weir 11, an immersion pipe 9, and a silica pump 10 made of refractories are provided in order from the continuous casting nozzle side between the continuous casting nozzle 4 and Each has a semicircular shape (diameter 80m/
m) is provided with a molten metal outlet 12;
One side of the cable is covered with an iron plate 13, and fixed with a castable cable 14 as shown in FIG.

The reason why the outlet 12 was shielded by the iron plate 13 is that if pouring is performed with the outlet 12 open from the beginning of casting, molten metal and slag at the initial stage of pouring will flow in. The outflow port 12 is shielded with an iron plate 13,
Shield it with iron plate 13 until a certain amount of hot water is formed,
After the molten steel 8 reached a certain level (temperature level of about 300 m/m), an iron plate (5 m/m) was selected and used. Since the iron plate 13 melts into the cut-off portion of the initial slab, it is made of a low-grade material, and in the embodiment, SS41 was used.

Due to the configuration of the lower weir described above, a pool of molten steel is created by the lower weir for the molten steel flow at the initial stage of injection, and the time (approx.
30sec~40sec), the lower weir outlet 12
The iron plate 13 melts, and the molten steel at the bottom of the pool flows. As the injection continues, the molten metal reaches the upper weir 6 as shown in Fig. 2A, which calms the molten steel flow and prevents splashing.At the end of the injection, the molten metal does not stagnate in the lower weir and flows through the outlet 12. Casting nozzle 4
The yield problem is solved because it is poured until the end. Since the yield problem can be solved by providing the outlet 12 in the lower weir, the lower weir can be made higher than conventional ones, and time can be taken for inclusions to float in the initial and final stages of casting.

Using the tundish with the above-mentioned configuration, the first
As a result of casting the steel type CH45K shown in the table, inclusions were found in conventional weirs intended only for slag flotation, and when the slime method was used to investigate particles with a diameter of 37μ or more within 10m/m under the skin, 80 were found in the unsteady part. /Ten
Kg. What used to be steel is now 40mm thick with this device.
pieces/10Kg. steel, reducing inclusions.

In addition, products (wire rods) cast using the molten metal container of the present invention and rolled have cracks during processing at wire rod secondary processing manufacturers, which used to occur at around 1.0%, but now the cracks have decreased to 0.5% and 1. It was possible to reduce it to /2. According to the present invention, the above-mentioned great effects can be achieved with a simple device.

[Brief explanation of the drawing]

FIG. 1 is an overall schematic explanatory diagram of a conventional continuous casting tundish, and FIG.
B shows the cross-sectional view of A in the same figure, and C shows the shape of the cylindrical weir. FIG. 3 shows an overall schematic explanatory diagram of the continuous casting tandate of the present invention for injection using an air-insulated immersion tube,
Figure 4 (a) is a schematic diagram showing the outlet provided in the lower dam, and (b) shows the state of shielding with an iron plate. 1...Tandaitsuyu, 2... Molten steel pot, 3...
Long nozzle, 4... Continuous casting nozzle, 5... Cylindrical weir, 6... Upper weir, 7... Lower weir, 8... Molten steel, 9...
...Immersion pipe, 10...Silicaps, 11...Lower weir,
12... Molten metal outlet, 13... Steel plate, 14...
...castable.

Claims (1)

[Scope of Claim for Utility Model Registration] A container for molten metal that is lined with refractory material and equipped with a weir made of refractory material, with a molten metal outlet provided at the bottom of the container between the receiving side and the tapping side. 1. A container for molten metal, which is provided with a lower dam having a lower weir and whose outlet is shielded by a metal plate into which molten steel melts.