JPS6360070A - Molten metal vessel having weir - Google Patents

Abstract

PURPOSE:To efficiently catch and remove the inclusion, to prevent the development of biased flow and to improve the quality of cast slab by arranging a weir forming many holes near a molten metal discharging hole in molten metal vessel and a gas supplying means supplying inert gas at these holes. CONSTITUTION:At the time of pouring the molten steel into a tundish 20 from a ladle as a weir 32 is arranged almost horizontally, the molten steel 21 passing through each hole 33, becomes to uniform flow speed. As argon gas is supplied through gas supplying pipe 34 at the lower part of holes 33, the gas rises the holes 33 and so it becomes to resistance to the molten metal flow falling the holes 33 and the flow-out speed of molten steel 21 becomes to slow. The passing through sectional area of molten steel 21 is possible to change by adjusting supplying quantity of gas 35, to control the flow-out rate of molten steed 21. In this way, the flow rate adjusting operation for a sliding nozzle 26 is lightened and the biased flow developed at the time of adjusting the flow rate of the sliding nozzle 26, is avoided. Further, as the uniform flow speed over the whole weir 32 is obtd., the catching efficiency of inclusion is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a molten metal container such as a tundish or a ladle, and in particular to a weir that efficiently removes inclusions from the flowing molten metal while controlling the amount of molten metal flowing out. The present invention relates to a molten metal container equipped with a molten metal container.

[Prior Art] In a conventional continuous casting tundish, as shown in FIG.
Molten m2 is injected into the chamber from a ladle (not shown). A weir 7 is provided in the tandish 1, and this weir 7 is provided from one longitudinal side wall of the tundish 1 to the other longitudinal side wall, and runs approximately vertically from the bottom of the tundish 1 to the vicinity of M (not shown). It is extending. The inside of the tundish 1 is partitioned by the weir 7 into a molten steel injection area and a molten steel outflow area, and impurities such as slag are prevented from flowing from the injection area to the outflow area. Weir 7
A plurality of holes 8 are provided at various heights in the weir 7, and the holes 8 penetrate the weir 7 approximately horizontally, so that the molten steel 2 injected from the ladle nozzle 9 into the tundish 1 flows from the injection area to the outflow area. It is designed to flow to. Also, Tanditshu 1
A cylindrical porous nozzle 5 is disposed at the bottom of the nozzle 5, and a molten steel outlet 6 is formed by this nozzle 5. A sliding nozzle 10 having a flow rate adjustment function is provided at the bottom of the outlet 6, and an immersion nozzle 14 is provided at the bottom of the slide plate 12 of the sliding nozzle 10.
is attached, and the lower part of this nozzle 14 is immersed in the molten steel in the mold 17.

In such a tundish 1, when molten steel 2 is injected into the tundish 1 from a ladle (not shown) through the ladle nozzle 9, the molten steel 2 flows approximately horizontally along the longitudinal direction of the tundish 1. This horizontal flow passes through holes 8 in weir 7. At this time, inclusions such as alumina floating in the molten steel 2 adhere to the wall surface near the outlet of the hole 8. Therefore, the molten steel 2 with few inclusions is injected into the mold 17 while its flow rate is adjusted by the sliding nozzle 10, and is cooled by the mold 17 to form the solidified shell 19.

[Problems to be Solved by the Invention] However, in the conventional tundish 1, the weir 7 and the outlet 6 are separated from each other, and inclusions and holes generated between the weir 7 and the outlet 6 are removed. Large inclusions that aggregated after passing through step 8 cannot be removed. In addition, since the weir 7 is installed vertically, inclusions that have passed through the holes 8 are easily suppressed by the flow of molten steel, and even if the inclusions have adhered to the wall of the weir 7, once they are peeled off, they will be mixed with the molten steel. The inclusions will flow out into the mold 17, reducing the efficiency of collecting inclusions. Furthermore, the flow rate of the molten steel in the tundish 1 is non-uniform, for example, the flow rate is faster in the upper hole 8 and slower in the lower hole 8, so the flow rate is uneven throughout the weir 7. There is a drawback that inclusions cannot be collected uniformly. Therefore, especially when alumina-based inclusions flow into the mold 17, there is a problem in that they are captured by the solidified shell 19 and significantly impair the surface quality of the slab.

In addition, as shown in FIG. 8, a sliding nozzle 10
In order to adjust the amount of molten steel injected by moving the slide plate 12 in the direction of the arrow 13, the center of the molten steel passageway 15 and the center of the outlet 6 are shifted from each other. Therefore, the flow of molten steel in the molten steel passageway 15 becomes non-uniform, and the same amount of molten steel does not flow out from the pair of discharge ports 16a and 16b at the bottom of the nozzle 14.

When such a drift occurs, the molten steel surface is stirred on the discharge port 16b side where the discharge amount is large, and the powder 1 covering the surface is agitated.
There are reports that the molten steel becomes involved and becomes inclusions in the steel, and that the injected molten steel remelts the solidified shell 19, causing breakouts and deteriorating the quality of the slab.

Furthermore, at the end of the casting stage, the molten metal level in Tanditsh 1 was approximately 4.
If the height is lower than 00■, a problem arises in that a vortex is generated in the area directly above the outlet 6, entraining the slag floating on the surface of the hot water, and causing the slag to flow into the mold 17.

This invention was made in view of such circumstances, and
To efficiently remove inclusions in the molten metal, to avoid the occurrence of drifting by adjusting the molten metal meteor separately from the sliding nozzle, and to effectively prevent slag entrainment at the final stage of casting. The purpose of the present invention is to provide a molten metal container equipped with a weir that allows for.

[Means for solving the gap] The molten metal container equipped with the weir according to the present invention has a molten metal outlet at the bottom, and the stored molten metal is removed from other objects through the sliding nozzle attached to the molten metal outlet. In the molten metal container equipped with a weir for removing inclusions in the molten metal while supplying the molten metal to a member, a large number of holes arranged substantially horizontally in the molten metal near the molten metal outlet and opening substantially vertically are provided. A weir is formed and a gas supply means for supplying an inert gas to the many holes is used, and the molten metal passes through the holes while being resisted by the inert gas and flows out from the molten metal outlet. shall be.

[Function] In the molten metal container equipped with a weir according to the present invention, since the weir is disposed in the molten metal near the molten metal outlet, most of the inclusions generated or grown in the container pass through the weir. As a result, the amount of inclusions flowing out is reduced, and when the hot water level drops, the weir suppresses the generation of vortices. In addition, since the weir is arranged approximately horizontally, inclusions are collected almost evenly over the entire surface of the weir without being affected by differences in vertical flow velocity within the container. . Further, since the inert gas is supplied by the gas supply means to the many holes formed in the weir, the molten metal flow cross-sectional area of the holes is reduced, and the flow rate of the molten metal passing through the holes is restricted. By adjusting the amount of inert gas, the flow rate of the molten metal flowing out from the outlet can be adjusted.

[Embodiments] Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.

FIG. 1 is a partial sectional view showing a continuous casting apparatus in which a molten metal container equipped with a weir according to a first embodiment of the present invention is applied to a tundish. The tandish 20 has a box shape extending in the direction of an arrow 29 in the figure, and has a refractory material 22 on the inside.
The inside is lined with steel, and the outside is covered with iron skin 23. Near the center of the tundish 20 is a molten steel injection area where molten steel is injected into the tundish 20 from a ladle (not shown), and near the side wall 39 facing the longitudinal direction of the tundish 20 is a molten steel injection area where the molten steel is injected into the tundish 20 from a ladle (not shown). 21 is a molten steel outflow area. A cylindrical porous nozzle 24 is fitted into the bottom 38 near the side wall 39, and the nozzle 24 forms a molten steel outlet 25. And molten steel outlet 2
A sliding nozzle 26 is provided at the bottom of 5. This nozzle 26 has a fixed plate 27 and a slide plate 28. The fixed plate 27 is fixed to the iron shell 23, and the slide plate 28 is slidably provided below the fixed plate 27. Further, a cylindrical immersion nozzle 42 is attached to the lower part of the slide plate 28. The lower part of the nozzle 42 is the mold 4
Injecting molten steel into the mold 44 through a pair of discharge ports 43a and 43b opened in the side wall of the mold 44,
It is designed to prevent oxidation of injected molten steel. Further, the hot water surface inside the mold 44 is covered with powder 48, and the mold 44 is covered with powder 48.
This prevents oxidation of the molten steel within, and improves the lubricity between the cast wall and the solidified shell 46.

On the other hand, a weir member 30 is provided to surround the molten steel outlet 25. The weir member 30 has a cylindrical support column 31 and a disc-shaped weir 32, and the support column 31 is connected to the outlet 25.
It is fixed on the lining refractory 22 of the bottom part 38 with the support pillar 31 supporting the weir 32 and blocking the inflow of molten steel from the sides of the weir member 30.

The installation height of the weir 32 is, for example, approximately 110 cm.

FIG. 2 is a perspective view of the weir 32. A large number of holes 33 are formed in the weir 32 and open in the thickness direction thereof. Weir 32
For example, it is made of calcium oxide (CaO)-based refractory material, and has a diameter of approximately 400 mm and a thickness of approximately 60 mm.
The diameter of the hole 33 is approximately 30ff111.

3 to 5 are schematic diagrams illustrating the respective flows of molten steel and argon gas in the hole 33. The lower peripheral wall of the hole 33 is formed of a cylindrical porous brick 36, and the supply port of the gas supply pipe 34 is communicated with the brick 36. The gas supply pipe 34 is connected to an argon gas supply source (not shown) having a flow rate adjustment function, and is configured to supply an appropriate amount of argon gas to the hole 33 through the brick 36.

In the tundish 20 configured in this way, when molten steel is injected into the tundish 20 from the ladle, a horizontal flow (direction of arrow 29) is generated in the tundish 20 along its longitudinal direction. The flow velocity of this horizontal flow differs depending on the depth of the molten steel, and for example, there is non-uniformity in the flow velocity such that the flow velocity is faster near the scene and slower near the bottom 38. By the way, since the weir 32 is installed substantially horizontally, the molten steel 21 flowing through the hole 33 is not affected by uneven flow velocity of the molten steel 21 in the vertical direction.
The flow velocity is approximately uniform. After passing through the hole 33, the molten steel 21 flows out from the outlet 25 into the mold 44 via the sliding nozzle 26 and the immersion nozzle 42. Third
As shown in the figure, the gas supply pipe 34 and the porous brick 3
Since argon gas is supplied to the lower part of the hole 33 through the hole 33, this supplied gas rises through the hole 33, and this acts as a resistance to the flow of molten steel descending through the hole 33, slowing down the outflow speed of the molten n421. In addition, as shown in FIG.
1 flows through the hole 33, sufficient contact between the inner wall and the molten steel 21 is ensured, and the cross-sectional area of the molten steel 21 flowing through the hole 33 becomes smaller, reducing the amount of flow of the molten steel 21. This molten steel 2
The flow cross-sectional area of 1 can be changed by adjusting the amount of gas 35 supplied, thereby increasing or decreasing the amount of molten steel 21 flowing out.

FIG. 5 is a schematic diagram showing the vicinity of the hole 33 when molten steel flows therethrough. Since the hole 33 is opened in a substantially vertical direction,
The molten steel flowing approximately horizontally in the direction of arrow 29 in the tundish 20 changes direction in the vertical direction and descends through the hole 33. When this downward flow passes through the hole 33, a small vortex is generated near the exit side of the hole 33, and inclusions 40 in the molten steel adhere to the lower surface of the weir 32. The attached inclusions 40 may be peeled off afterwards, but the peeled inclusions 40 stay on the lower surface of the weir. Therefore, the inclusions 40 in the molten steel that have passed through the holes 33 are efficiently captured by the weir 32.

On the other hand, when the injection of molten steel into the ladle is stopped at the end of casting and continuous casting is continued while adjusting the flow rate of molten steel 21 by the sliding nozzle 26, the level of the molten steel in the tundish 20 begins to drop. Normally, when the height of the molten metal falls below about 400 a+m, a vortex will be generated in the area directly above the outlet 25, but since a weir member 30 is installed in this vortex generation area, the weir member 30 will prevent the molten steel from flowing. Swirling flow is prevented and generation of vortices is suppressed.

As described above, in this embodiment, by supplying argon gas to the numerous holes 33 of the weir 32, the flow rate of molten steel is controlled to a flow rate range of about 0 to 50% of the steady state flow rate (that is, a range of about half the steady flow rate). The flow rate adjustment operation of the sliding nozzle 26 can be reduced. Therefore, it is possible to avoid the occurrence of a biased flow when adjusting the flow rate of the sliding nozzle. Furthermore, since the weir 32 is installed approximately horizontally, the flow velocity is approximately uniform throughout the weir 32 without being affected by unevenness in the vertical flow velocity of molten steel, so that inclusions 40 can be captured. The collection efficiency can be improved, and the generation of vortices at the final stage of casting can be effectively prevented. Therefore, the outflow of inclusions and slag into the mold 44 is slightly reduced, and the amount of impurities trapped in the solidified shell 46 can be reduced, making it possible to improve the quality of the slab by improving its surface properties, etc. can.

FIG. 6 is a partial sectional view showing a continuous casting apparatus in which a molten metal container equipped with a weir according to a second embodiment of the present invention is applied to a tundish. Descriptions of parts that are common between the first embodiment and the second embodiment will be omitted. In this second embodiment, in the molten steel outflow region of the tundish 50, the bottom 54 near the side wall 52 is lower than the bottom 53 in other regions, and a box-shaped recess 56 is formed.

A weir 60 is fitted substantially horizontally into the upper part of this recess 56 so as to be flush with the upper surface of the bottom part 53.

A large number of holes 61 opening in the vertical direction are formed in the weir 60, and the molten M51 flows into the recess 56 through the holes 61. One end of a gas supply pipe 62 penetrating the side wall 52 is communicated with the side surface of the weir 60 from outside the tundish 50. The other end of this gas supply pipe 62 is connected to an argon gas supply source (not shown) equipped with a flow rate adjustment function. On the other hand, a porous nozzle 24 is provided approximately at the center of the bottom 54 of the recess 56, thereby forming a molten steel outlet 25.

The tundish 50 configured in this manner generates a horizontal flow in the direction of the arrow 57 within the tundish 50 by pouring molten steel into the ladle, and when the molten steel in the horizontal flow reaches the upper part of the weir 60, it is sucked into the hole 61 and forms a recess. This becomes a downward flow that enters the area 56. Argon gas 63 is supplied to this hole 61, and as the gas 63 rises, the flow rate and flow rate of the molten steel 51 decrease. The molten steel 51, whose flow rate has been adjusted by passing through the weir 60, flows into the recess 56, and then flows out from the outlet 25 into the mold 44 through the nozzle 26.42.

In this second embodiment, since the weir 60 is provided between the bottom 53 and the road surface, most of the stored molten steel 51 can be flowed out, reducing the amount of remaining steel in the tundish 50. be able to. Also, the bottom 5 of other areas
Since the bottom part 54 of the molten steel outflow area is lower than in 3, the depth of the molten steel to the molten steel surface at the outflow port 25 increases, and the generation of layers and vortices is suppressed, reducing the entrainment of slag. The amount can be reduced. Furthermore, since the weir 60 can be installed simply by fitting into the upper opening of the recess 56, manufacturing can be made even easier.

In the above embodiment, the present invention is applied to a tundish, but the present invention is not limited to this, and can be applied to other molten metal containers such as a ladle.

Further, in the above embodiment, a CaO-based refractory is used as the material for the weir member, but the present invention is not limited to this, and other refractories such as zirconia-based refractories may also be used.

Furthermore, the weir shown in the first embodiment is not limited to a circular shape, but can also be square. Furthermore, the installation height of the weir should be approximately 30 to 300 mts, and the diameter of the weir should be approximately 200 to 80 mts.
0 ass, the thickness of the weir at least about 201 m, and the diameter of the hole within the range of about 10 to 80 ml, the same effect can be obtained.

[Effects of the Invention] According to the present invention, since the weir is provided near the molten metal outlet, most of the inclusions present in the container pass through the weir, and the inclusions can be efficiently collected. In addition, it is possible to suppress the generation of vortices when the scene is lowered. In addition, since the weir is installed approximately horizontally, inclusions can be collected almost evenly over the entire surface of the weir without being affected by uneven flow velocity of the molten metal that occurs in the depth direction. Even if the inclusions attached to the underside of the weir peel off, they remain on the underside of the weir, which prevents the peeled inclusions from flowing out from the outlet, improving the efficiency of collecting inclusions by the weir. can be done. Therefore, it is possible to reduce the amount of inclusions flowing into other members such as the mold, and it is possible to improve the quality of the product, such as improving the surface properties of the product. In addition, since inert gas is supplied to the hole and the flow rate of the molten metal flowing through the hole can be adjusted, the amount of flow adjustment operation of the sliding nozzle can be reduced, and the occurrence of uneven flow can be avoided. . Therefore, casting troubles such as remelting of the solidified shell and inclusion of impurities can be avoided, and the quality of the slab can be improved.

[Brief explanation of drawings]

1 is a partial sectional view showing a continuous casting apparatus in which a molten metal container equipped with a weir according to a first embodiment of the present invention is applied to a tundish; FIG. 2 is a perspective view showing the weir; FIG. Fourth
The figure is a schematic diagram explaining the respective flows of gas and molten steel in the hole, FIG. 5 is a schematic diagram showing the vicinity of the hole when molten steel flows, and FIG. 6 is a diagram according to a second embodiment of the present invention. FIG. 7 is a partial sectional view showing a continuous casting apparatus in which a molten metal container equipped with a weir is applied to a tundish, FIG. 7 is a partial sectional view showing a conventional tundish, and FIG. 8 is a sectional view showing the vicinity of a sliding nozzle. 20.50; Tanditshu, 25; Molten steel outlet, 30
Weir member, 31; Support column, 32, 60; Weir, 3B, 61
; Hole, 34, 62; Gas supply pipe, 36; Porous brick. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] In the molten metal container, the molten metal container is equipped with a molten metal outlet at the bottom and a weir for removing inclusions in the molten metal while supplying the stored molten metal to other members via a sliding nozzle attached to the molten metal outlet. A weir having a large number of holes disposed substantially horizontally in the molten metal near the molten metal outlet and opening substantially vertically, and a gas supply means for supplying inert gas to the large number of holes. 1. A molten metal container having a weir, wherein the molten metal passes through the hole while receiving resistance from an inert gas, and flows out from the molten metal outlet.