JPH11170011A - Continuous casting tundish - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute the stable casting by providing a weir along the longitudinal direction of a tundish at the bottom part of the tundish between the molten metal dropping part from a molten metal vessel and a pouring hole line into molds and specifying the range of the weir height to effectively eliminate the large kinetic energy of molten metal stream. SOLUTION: The weir 10 along the longitudinal direction of the continuous casting tundish 1, is arranged. Therefore, the weir 10 can be set without interfering with each pouring hole 5, The height of the weir 10 is set as 150-250 mm. In the case of being <150 mm height of the weir 10, the molten metal flow which crosses over the weir 10 and directly reaches the pouring hole line, is too much, and high temp. molten metal is directly supplied into the pouring hole nearest to the molten metal dropping part, and thus, there is fear of developing the abnormal quality of the center segregation and the breakout accident in a cast slab of the strand corresponding to this pouring hole. In the case of exceeding 250 mm of the height of the weir 10, the phenomenon that the supply of fresh molten metal only to a specific strand delays is developed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting tundish for a multi-strand mill for continuously casting molten metal.

[0002]

2. Description of the Related Art Molten metal typified by molten steel is cast into a slab mainly after continuous refining in a converter or an electric furnace, etc., by a continuous casting method. The molten metal that has been refined is stored in a molten metal container called a ladle, then poured into a continuous casting mold via an intermediate container called a tundish, and solidification progresses from four rounds in the process of being drawn below the mold, Finally, it becomes a slab that has been solidified. The reason for using a tundish is to distribute the molten metal to multiple strands at the same time, and in continuous casting, the casting is not interrupted even if the casting for one ladle is completed. The continuation is done,
This is because it functions as an intermediate container for preventing the supply of the molten metal to the mold from being interrupted when the ladle is replaced.

[0003] A tundish is a container for intermediately storing a molten metal, the inner surface of which is covered with a refractory, and has a refractory injection hole at the bottom for injecting the molten metal into a continuous casting mold. . In a multi-strand mill in which casting is performed by a large number of molds at the same time, the number of tundish injection holes is the same as the number of the molds, and they are arranged in a row to form an injection hole row. In each of the injection holes, a stopper or a sliding nozzle made of a refractory, which corresponds to a valve for controlling the opening and closing of the injection flow path and the flow rate of the injection flow, is usually installed.

Since the flow of molten metal from the molten metal container to the tundish dropper has a large kinetic energy,
If this kinetic energy is not effectively eliminated, harmful molten metal flow will occur in the tundish. Particularly in a multi-strand mill in which a large number of injection holes are arranged in a line, if the kinetic energy of the molten metal flow in the dropping portion flows at a high speed through the bottom of the tundish without being attenuated, the injection holes close to the dropping portion have high temperatures. The molten metal is supplied, and the low-temperature molten metal arriving with a time delay is supplied to the injection hole far from the dropping portion. If the temperature of the molten metal in the mold differs for each strand, high-temperature strands can cause quality abnormalities such as abnormal center segregation of the slab, and breakout accidents in which the slab is broken during casting and the molten metal leaks out. The strands having a low temperature may cause an accident such as nozzle clogging. In order to solve such a problem, conventionally, a T-shaped tundish as shown in FIG. 6 has been adopted. The protruding part of the T-shaped tundish is the molten metal dropping part, which is isolated from the part where the row of injection holes into the mold exists, so that the kinetic energy of the flow of the molten metal from the molten metal container reaches the row of injection holes. Not easily transmitted. Also, the bottom of the projection is arranged lower than the bottom of the injection hole row,
Further, by providing a weir between the molten metal dropping portion and the pouring hole row portion, the kinetic energy of the molten metal flow from the molten metal container is completely eliminated in the molten metal dropping portion.

Conventionally, when one continuous casting is completed, the tundish is replaced before the start of the next continuous casting, and the tundish used so far is cooled to repair the refractory. Even if the life of the refractory has not expired in one continuous casting, the refractory on the surface in the tundish spalls during the cooling process.
The refractory on the surface had to be completely rebuilt.

If the refractory in a tundish can be used in a plurality of continuous castings, the cost of the refractory can be reduced. However, even in this case, it is necessary to replace the injection hole into the mold and the stopper, so the residual molten material left in the tundish at the end of continuous casting (slag mixed from the molten metal container, melting in the tundish, etc.) It is necessary to discharge the heat insulating material on the metal surface from inside the tundish. If the method of inverting the tundish by 180 ° and discharging the remaining molten material inside is adopted, a large-scale facility for inversion is required. Therefore, a residual melt discharge hole that can be opened and closed near the bottom of the tundish. It is advantageous if the tundish can be slightly inclined to discharge the residual melt from the residual melt discharge hole.

However, the shape of the tundish is T-shaped as in the prior art, and the bottom of the run-off portion is lower than the bottom of the row of pouring holes. When the tundish was slightly tilted, it was not possible to discharge all of the remaining melt only by slightly tilting the tundish, and the tundish could not be used in multiple continuous castings.

In a continuous slab casting apparatus or a bloom continuous casting apparatus having a large slab cross section, the injection hole extends into the continuous casting mold and uses an immersion nozzle immersed in a molten metal bath in the mold. It prevents the molten metal from coming into contact with the surrounding atmosphere to promote oxidation. However, in a small-section continuous billet continuous casting apparatus, it is difficult to insert the immersion nozzle into the mold due to the small cross-sectional size of the mold, and the injection flow from the injection hole at the bottom of the tundish into the mold below. Must use open injection, which is exposed to the surrounding atmosphere.

When performing an open injection, it is essential that the injection flow has a stable rectification. If the injection flow is not rectified,
When scattering occurs, the surface quality of the produced slab increases due to the progress of oxidation from the surface of the droplet and the instability of the molten metal surface in the mold. Further, when the droplets adhere to and grow on the wall surface of the mold, the solidified shell is broken immediately below the mold, which causes a breakout in which the molten metal inside leaks out. In addition, the adhesion of the droplets to the wall surface of the mold causes an increase in the variation of the surface level of the molten metal due to the malfunction of the surface level detector of the molten metal in the mold and causes the bottom to be lost.

[0010] Of the injection holes of the multi-strand mill, with respect to the injection hole closest to the tundish wall, the molten metal flow rebounding on the wall directly hits the injection hole. This has the problem that the flow of the open injection into the mold is no longer rectified.

Further, as described above, when performing the open injection, it is necessary to rectify the flow of the molten metal from the injection hole to the mold. If the flow rate of the molten metal flow for each strand is controlled using means such as a stopper installed near the injection hole, rectification is impaired, so the stopper etc. should be fully opened during injection,
The injection flow rate control is basically determined only by the static pressure of the molten metal in the tundish and the diameter of the injection hole. Therefore, when a surface wave is generated on the surface of the molten metal in the tundish, the surface wave fluctuates the static pressure of the injection hole.
This causes fluctuations in the injection flow rate. In a continuous casting tundish for a multi-strand mill employing open injection, a conventional tundish cannot prevent surface waves on the surface of the molten metal in the tundish, and the injection flow fluctuates.

[0012]

In order to use the same tundish in the next continuous casting without cooling after the completion of one continuous casting, a stopper or the like disposed at each injection hole into the mold is required. After the injection flow is interrupted by the function of (1), it is necessary to remove the melt such as slag remaining in the tundish. When a residual melt discharge hole having an opening / closing function such as a sliding nozzle or a stopper is provided at one position on the bottom of the tundish, and all the residual melt is to be discharged from the residual melt discharge hole, the tundish is replaced with a conventional one. When the T-shaped protrusion is a molten metal dropping part and the bottom of the protrusion is the lowest part of the bottom in the tundish, the residual melt discharge hole is It must be provided in the protrusion. However, since the protruding portion is also a portion for receiving the injection flow from the molten metal container, it is intensely stirred by the injection flow, so that a space for installing the sliding nozzle cannot be taken, and accidents such as breakage of the stopper cannot be avoided. . Therefore, in the case where continuous use of a tundish is to be realized by a multi-strand mill, it is preferable to adopt a shape without a T-shaped projection.

Further, in order to inject all the molten metal in the tundish through the injection hole when the continuous casting is completed, the bottom of the tundish needs to have a flat surface. Therefore, when a residual melt discharge hole having an opening / closing function such as a sliding nozzle or a stopper is provided at one position on the bottom of the tundish, and all the residual melt is to be discharged from the residual melt discharge hole, the dischargeability is good. In order to achieve this, it is effective to slightly tilt the tundish and to provide a residual melt discharge hole in the lowest portion of the tundish bottom at that time. The residual melt discharge hole may be disposed at the longitudinal end of the tundish. In this case, in the multi-strand mill, since the injection holes into the mold are arranged in a row in the horizontal direction, the tundish has a shape with a large aspect ratio, and the stroke for inclining the tundish becomes long. Therefore, if the stroke cannot be lengthened, the residual melt discharge hole is arranged at the center of the tundish in the longitudinal direction and on the opposite side of the row of injection holes.
If the tundish wall on the opposite side of the injection hole row has a shape bulging outward at the center as shown in, the tundish is rotated and tilted with its longitudinal direction as the rotation axis, so that a slight tilt stroke is achieved. The melt can be discharged from the residual melt discharge hole.

[0014] In this case, it is preferable to dispose the molten metal dropping portion from the molten metal container at a distance from the residual molten material discharge hole. Further, since it is necessary to remove all the residual molten material in the tundish with a slight inclination of the tundish, a pool portion surrounded by weirs on all four sides must not be formed at the bottom of the tundish. However, it is inevitable that a small pool is formed in the injection hole into the mold.

In the tundish designed as described above, there is no mechanism for extinguishing the kinetic energy of the molten metal from the molten metal container unlike the conventional T-type tundish. Intense flow of molten metal in the dish is inevitable. For this reason, in the multi-strand mill, the molten metal still having a high temperature is supplied to the injection hole near the dropping portion, and the molten metal having a lowered temperature is provided to the injection hole far from the dropping portion. Will occur. A first object of the present invention is to solve this problem.

Next, when the residual melt discharge hole is provided at the center in the longitudinal direction of the tundish, and the molten metal dropping portion is arranged to be offset from the central portion of the tundish in the longitudinal direction for the purpose of separating from the residual melt discharge hole, The symmetry of the flow of molten metal in the dish is lost, and the molten metal is supplied excessively to the injection holes on the side where the distance from the dropping part to the end wall is short, and the distribution of the molten metal to each injection hole is not uniform This causes uneven casting speed for each strand. A second object of the present invention is to solve this problem.

A third object of the present invention is to prevent the molten metal from repelling against the tundish wall and adversely affecting the injection of the injection hole closest to the wall when the open injection is employed. I do.

A fourth object of the present invention is to prevent instability of the injection flow based on the surface wave of the molten metal surface in the tundish when the open injection is adopted.

[0019]

The first invention has been made to achieve the first object. That is, the gist is that the bottom of the tundish is flat,
In a continuous casting tundish for a multi-strand mill having no protrusion for a molten metal dropping portion from a molten metal container, a gap between a molten metal dropping portion from a molten metal container and an injection hole array into a mold is provided. At the bottom of the tundish, there is a weir along the longitudinal direction of the tundish, and the height is 150 m.
It is a continuous casting tundish characterized by having a weir of not less than m and not more than 250 mm.

As a result, the molten metal does not directly reach the injection hole closest to the molten metal dropping portion from the molten metal dropping portion, so that the adverse effect of supplying the molten metal having a high temperature is improved. Also,
Since the four rounds of the dropping portion are not surrounded by the weir, no pool portion is formed in the tundish, and the residual molten material can be discharged from one discharge hole. The second invention has been made to achieve the second object. That is, the molten metal dropping portion is located at a position deviated from the central portion in the longitudinal direction of the tundish, and the weir along the longitudinal direction of the tundish melts at the end of the weir on the side where the molten metal dropping portion is biased. The continuous cast tundish according to the first aspect of the present invention, characterized in that the tundish has an L-shape having a bent protruding portion on the side of the metal dropping portion.

As a result, the flow of molten metal at the bottom of the tundish on the side where the molten metal tends to be excessively supplied, where the molten metal falls off, collides with the protruding portion of the L-shaped weir and receives resistance. The flow rates of the left and right molten metal flows in the longitudinal direction are equalized, and the distribution of the molten metal to each injection hole is equalized.

The third invention has been made to achieve the third object. That is, a continuous cast tundish for a multi-strand mill for performing an open injection in which a molten metal stream is exposed to a surrounding atmosphere when the molten metal is injected into a mold,
On the bottom of the tundish near the injection hole closest to the tundish wall, a direction from the injection hole toward the wall near the injection hole and a direction from the injection hole toward the wall on the long side far from the injection hole. The weir is a continuous cast tundish characterized by having an L-shape.

Accordingly, the molten metal flow flowing from the molten metal dropping part in parallel with the longitudinal direction of the tundish rebounds on the wife wall, descends along the wife wall, and obstructs the flow directly hitting the injection hole closest to the wife wall. Therefore, it is possible to prevent a problem that the injection flow from the injection hole is disturbed and rectification is not performed.

A fourth invention has been made to achieve a fourth object. That is, in a continuous casting tundish for a multi-strand mill for performing an open injection in which a molten metal stream is exposed to a surrounding atmosphere when the molten metal is injected into a mold,
A weir arranged so as to bridge between walls on both long sides of the tundish, wherein the lower end of the weir is located above and separated from the bottom of the tundish. A continuous cast tundish characterized by having a weir whose surface is normally present.

The surface wave propagating in the longitudinal direction of the tundish has a natural vibration having a natural period determined by the length of the tundish. When the molten metal is injected from the molten metal container into the tundish, the natural vibration is amplified based on the stirring energy based on the injection, and the surface of the molten metal in the tundish starts to vibrate at a constant cycle. When such a surface wave is generated, the static pressure of each injection hole fluctuates with time, and the flow rate of the injection flow from the injection hole to the mold fluctuates with time. According to the fourth aspect, generation of a natural vibration surface wave in the tundish can be prevented. That is, the surface wave of the surface of the molten metal in the tundish involves periodic movement of the molten metal in the longitudinal direction of the tundish near the surface of the molten metal. Since the weir is located at a position where the molten metal surface in the tundish normally exists during casting, the movement of the molten metal in the tundish longitudinal direction on the molten metal surface is hindered. This is because it can be attenuated. In addition, since the lower end of the weir of the present invention is located above and separated from the bottom of the tundish, the flow of the molten metal discharged from the dropping part in the tundish is not disturbed by the weir, and furthermore, continuous casting is performed. When discharging the residual molten material at the end, the weir does not hinder the discharge.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is effective in a multi-strand continuous casting mill having four or more strands. In a multi-strand continuous casting mill, the continuous casting molds are arranged in one horizontal row, and the tundish injection holes are arranged above the molds of the individual strands, so that the tundish has a long shape. In the boat-shaped tundish of the present invention, which does not have a protrusion for the molten metal dropping portion, the injection hole row is arranged to be biased to one long side wall side of the tundish, and the dropping portion is provided. It is preferable to dispose it on the other long side wall. Furthermore, when the residual melt discharge hole from the tundish is arranged at the center in the longitudinal direction of the tundish, the stopper of the discharge hole is prevented from being damaged by the flow of the molten metal in the melter. Is preferably arranged to be deviated from the central portion in the longitudinal direction of the tundish to one of the end portions. The bottom of the tundish is cast over a perm brick and coated with a refractory coating.

The weirs along the longitudinal direction of the tundish of the first invention are preferably arranged in parallel to the longitudinal direction of the tundish, as shown in FIG. This allows
The weir can be arranged without interfering with each injection hole. The height of the weir is 150 mm or more and 250 mm or less. If the height of the weir is less than 150 mm, too much molten metal flow over the weir and directly reaches the row of injection holes, and the high-temperature molten metal is directly supplied to the injection hole closest to the pouring part. As a result, a quality abnormality such as center segregation of the strand slab corresponding to the injection hole or a breakout accident occurs. When the height of the weir exceeds 250 mm, a phenomenon occurs in which the supply of fresh molten metal only to a specific strand is delayed. It is necessary to keep the height of the weir at an appropriate height in the above range and to maintain a proper flow of molten metal over the weir in order to evenly distribute fresh molten metal to each strand. .

The length of the weir is 1500 mm to 2500 mm
Is most suitable, most preferably 2000 mm. The reason is that the spacing between adjacent strands is usually about 1
000 mm, and the length of the weir is 1.5
By setting the length to 2 to 2.5 times, preferably 2 times, it is possible to avoid the direct flow from the dropping part. An appropriate width of the weir is about 80 mm. The reason is that the weir is required to have a width of about 80 mm so that the weir can withstand the agitation energy of the dropping part without any other support and stand alone. It should be noted that the width of the weir should not be unnecessarily thick in the arrangement of the weir, the dropping part, and the row of injection holes. The reason for this is that if the space between the molten metal dropping portion and the pouring hole row portion is too small, the effect of attenuating the stirring energy is reduced.

The refractory used to form the weir is suitably a cast refractory having an alumina content of 80% or more. Regarding the connection between the weir and the bottom refractory, the base of the weir can be held down by a clay-based patching material to prevent the fall.
In the case where the distance between the bath portion and the row of injection holes is small and the width of the weir cannot be sufficiently secured, a structure as shown in FIG. 8 may be employed as a method for supporting the weir.

The L-shaped weir of the second invention is arranged as shown in FIG. FIG. 7 shows a plan view of the present invention. If the shape of the weir shown in FIG. 7 is changed from L-shape to I-shape, it becomes a diagram showing the first invention. The height of the weir of the protruding portion is preferably the same as that of the portion parallel to the longitudinal direction of the tundish, but may be different. The length of the protruding part is determined by how much the pouring part is arranged in the longitudinal direction of the tundish,
When the flow distribution ratio due to the eccentricity is, for example, 5: 3, it is appropriate that the ratio of the distance from the weir to the tundish wall and the distance from the protrusion to the wall is 5: 3. is there. It is appropriate that the material of the refractory of the weir and the structure of the weir are the same as those of the weir of the first aspect.

The weir of the third invention is arranged as shown in FIG. The height of the weir is suitably between 50 mm and 150 mm. The length of each side of the L-shaped weir is suitably 150 mm to 250 mm. The material of the refractory of the weir and the structure of the weir are preferably the same as those of the first invention.

The weir according to the fourth invention is arranged as shown in FIG. As shown in FIG. 4 (a), the weir has a sufficient effect if one dam is installed on the side where the distance between the hot water drop portion and the tundish wall is short, but as shown in FIG. 4 (b), A higher effect can also be obtained by arranging one on each side of the falling part. The weir includes the surface of the molten metal in the tundish, and the lower part of the weir is 100 m deep from the surface of the molten metal.
It is desirable that the distance be in the range of m to 250 mm. If the position of the lower part of the weir is less than 100 mm in depth from the surface of the molten metal, the weir is not enough to attenuate the surface wave inside the tundish. The flow of metal is obstructed, and proper molten metal flow to each injection hole cannot be obtained. The material of the refractory of the weir,
It is appropriate that the structure of the weir is the same as that of the first invention.

[0033]

EXAMPLE The present invention was applied to a steel billet continuous casting apparatus. The continuous casting apparatus is an 8-strand mill, the mold size is 125 mm × 125 mm, and the casting speed is 2.6.
Casting was performed under the conditions of ~ 3.2 m / min. The tundish capacity is 35 tons. The molten steel refined by the converter refining method is received in a ladle having a capacity of 240 tons, and molten steel is injected from the ladle into the tundish 3 through the long nozzle 7. The eight injection holes are arranged in a line on one side of the tundish, and the distance between adjacent injection holes is 1100 mm. The molten steel dropping portion from the ladle was disposed at a position on the opposite side of the pouring hole row and at a position deviated from the central portion of the tundish in the longitudinal direction by 1.1 m. The dropping part is located at a position 630 mm away from the injection hole row at the shortest distance. Above the injection holes 5, refractory stoppers (not shown) are arranged to control on / off of the injection flow. An open injection method is adopted below the injection hole 5 without using an immersion nozzle reaching the inside of the mold.

Inventive Example No. 1 has a weir of the first invention as shown in FIG. The height of the weir was 200 mm, the length was 2,000 mm, and the width was 80 mm. The center of the weir was placed at a position 300 mm away from the row of injection holes.

Inventive Example No. 2 has the weir of the second invention as shown in FIG. The L-shaped long side of the weir corresponds to the above-mentioned Invention Example No. 1. Same as FIG. 1 except that an L-shaped short side is added to this weir. The height of the short side is the same as the long side, 200m
m, the protruding length is 200 mm. The distance from the tip of the protrusion to the wall of the long side of the tundish is 30
0 mm.

Inventive Example No. 3 has the weirs of the second and third inventions as shown in FIG. The L-shaped weir at the dropping part is the same as in the above invention example No. The L-shaped weir of the third invention was provided in the vicinity of two injection holes having the same shape as that of No. 2 and being closest to the end wall at both ends of the tundish. The height of the weir of the third invention is 1
00 mm and the length of each side is 200 mm, and the production of the weir is the same as that of the first invention.

Inventive Example No. 4 has the weirs of the second to fourth inventions as shown in FIG. Invention Example N
o. The same weir as in No. 3 was added, and a weir of the fourth invention was further added. The weir of the fourth invention is arranged at a position of 1000 mm from the dropping part, and the lower end of the weir is 400 mm below the surface of the molten metal. The depth of the molten metal is 500 mm.

In the comparative example, as shown in FIG. 5, a tundish similar to the above-mentioned invention example is provided without the weir of the present invention.

Table 1 shows the results of casting using the tundishes of the present invention and comparative examples. The slab quality index is an index representing the frequency of occurrence of maintenance based on the center segregation failure and surface flaws of the slab, and the breakout occurrence rate is an index representing the frequency of occurrence of breakout for each strand. Is a dimensionless exponent. In both cases, smaller numbers indicate better performance. The pouring part is eccentric in the tundish, and the third strand and fourth
It is located in the middle of the strand.

[0040]

[Table 1]

In the comparative example, both the slab quality index and the breakout occurrence rate show high figures. In particular, the results of the third and fourth strands closest to the dropping part are poor. On the other hand, in the present invention example No. In No. 1, the performance of each strand is improved compared to the comparative example. Invention Example No. No. 2 is No. As compared with No. 1, the slab quality index of the first and second strands is improved. This is because the distribution of the molten metal to the left and right of the tundish is improved by the L-shaped weir. In addition, No. In No. 2, the breakout occurrence rates of the third and fourth strands are also improved. Invention Example No. No. 3 is No. As compared with No. 2, the slab quality index of the first and eighth strands at both ends of the tundish is improved.
Based on the effect of the weir of the third invention. Invention Example No. 4 is
No. As compared to No. 3, the slab quality index of the second to fourth strands in particular was improved, and the breakout occurrence rate was improved to zero in any of the strands. This is because the effects of all weirs of the present invention have been integrated.

[0042]

According to the present invention, in a continuous casting tundish for a multi-strand mill for using a tundish refractory a plurality of times, large kinetic energy of a molten metal flow from a molten metal container to a tundish is effectively eliminated. And stable casting, stabilizing the quality of continuous cast slabs, reducing breakout accidents, and stabilizing casting when performing open injection.

[Brief description of the drawings]

FIG. 1 is a perspective view (partial cross section) showing a continuous casting tundish of the first invention.

FIG. 2 is a perspective view (partial cross section) showing a continuous cast tundish of the second invention.

FIG. 3 is a perspective view (partial cross section) showing a continuous cast tundish of the second and third inventions.

FIGS. 4A and 4B are perspective views (partial cross-sections) showing the continuous casting tundish of the second to fourth inventions, wherein FIG. 4A is an example in which there is one weir of the fourth invention, and FIG. This is an example of two dams according to the fourth invention.

FIG. 5 is a perspective view (partial cross section) showing a conventional continuous casting tundish.

FIG. 6 is a perspective view (partial cross section) showing a conventional continuous casting tundish.

FIG. 7 is a plan view showing a continuous cast tundish of the second invention.

FIG. 8 is a perspective view showing a continuous casting tundish of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Continuous casting tundish 2 Long side wall 3 Wife wall 4 Bottom part 5 Injection hole 6 Residual molten material discharge hole 7 Long nozzle 8 Molten metal surface 9 Dropping part 10 Weir of the first invention 11 Weir of the second invention 12 Weir of the third invention 13 Weir of the fourth invention 14 Projection part 15 Weir of molten metal part 16 Molten metal flow

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Katsuya Senda, Kimitsu, Kimitsu City, Nippon Steel Co., Ltd. 1 Inside Nitsutsu Works (72) Inventor, Keiji Ogura 1, Kimitsu, Kimitsu City, Nippon Steel Corporation Inside the Tsu Works (72) Inventor Koichi Kudo 1 Kimitsu, Kimitsu City Inside the Nippon Steel Corporation Kimitsu Works

Claims (4)

[Claims] In a continuous cast tundish for a multi-strand mill, wherein the bottom of the tundish is flat and does not have a protrusion for a molten metal dropping portion from the molten metal container, the molten metal from the molten metal container is provided. A weir along the longitudinal direction of the tundish at the bottom of the tundish between the pouring part and the row of injection holes into the mold, and having a height of 150 mm
A continuous cast tundish having a weir of at least 250 mm. 2. The molten metal dropping portion is located at a position deviated from the longitudinal center of the tundish, and the weir along the longitudinal direction of the tundish is an end of the weir on the side where the molten metal dropping portion is deviated. The continuous cast tundish according to claim 1, wherein the portion has an L-shape having a protruding portion bent toward the molten metal dropping portion side. 3. A continuous casting tundish for a multi-strand mill for performing an open injection in which a molten metal stream is exposed to a surrounding atmosphere when the molten metal is injected into a mold, wherein the tundish is in the vicinity of an injection hole closest to a tundish wall. The bottom of the tundish has weirs in two directions: a direction from the injection hole toward the end wall close to the injection hole and a direction from the injection hole toward a long-side wall far from the injection hole. An L-shaped continuous cast tundish. 4. In a continuous casting tundish for a multi-strand mill for performing an open casting in which a molten metal stream is exposed to a surrounding atmosphere when a molten metal is injected into a mold, a bridge is formed between walls on both long sides of the tundish. A weir to be disposed, wherein the lower end of the weir is located above and away from the bottom of the tundish, the weir having a weir at a height at which the surface of the molten metal in the tundish is normally present during casting. Features a continuous cast tundish.