JP2017177180A - Tundish for continuous casting, and continuous casting method using the tundish - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tundish capable of suppressing variation in molten steel temperatures among respective strands in a tundish.SOLUTION: A tundish 1 comprises: right/left/upward runners 9a, 9b; horizontal or downward runners 9c, 9d; and a bottom part arranged below lower ends of outlets 10c, 10d of runners 9c, 9d; and satisfies relational expressions, d≤0.3,D≤0.3,x≥0.1z+D/2,θ≤60,ztanθ-0.1z/cosθ≥H/3,ztanθ+D+0.1z/cosθ≤H,x≥0.1(z+z)+(d+D)/2,x≥0.1z+d/2 (where d: runners 9c, 9d longitudinal diameter; d: runners 9c, 9d lateral diameter; D: runner 9a. 9b longitudinal diameter; D: runner 9a, 9b lateral diameter; x: distance from intersection of runners 9a, 9b to intersection of casting mold injection hole 6; θ: horizontal angle of runners 9a, 9b on strand chamber 5 lateral center side; θ: upward angle of runners 9a, 9b).SELECTED DRAWING: Figure 2A

Description

  The present invention uses a tundish for continuous casting in which a runner (weir hole) for circulating molten steel from an injection chamber to a strand chamber is provided in a partition weir that partitions an injection chamber and a strand chamber, and the tundish. The present invention relates to a continuous casting method.

Conventionally, in a continuous casting machine, the molten steel produced from a converter, secondary refining equipment, etc. is transported to the tundish by a ladle, and the molten steel in the ladle is poured into the tundish, and then this tundish. The molten steel is continuously cast by supplying molten steel to the mold.
In order to efficiently operate continuous casting, it is necessary to make the molten steel temperature uniform between the strands when smoothly flowing the molten steel from the injection chamber to the strand chamber in the tundish.

As means for making the temperature of the molten steel in such a tundish uniform, there are those disclosed in Patent Documents 1 to 3.
Patent Document 1 aims to reduce variations in molten steel temperature between strands in a multi-strand tundish. Specifically, in a T-type tundish where the injection chamber and the strand chamber are partitioned by a weir, the weir has two holes (runners) open so that the direction of the hole is between the predetermined strands. Thus, variations in molten steel temperature between the strands are reduced.

  Patent Document 2 aims to reduce molten steel temperature variation between strands in a three-strand tundish. Specifically, in the tundish in which the injection chamber and the strand chamber are partitioned by a weir, the weir is provided with a molten steel flow path, and a plasma heating device for heating the molten steel is provided. The steel output temperature is made uniform.

  Patent Document 3 aims to reduce variations in molten steel temperature between strands in a multi-strand tundish. Specifically, the tundish is composed of an injection chamber and two strand chambers, each of which is partitioned by a weir between the injection chamber and the two strand chambers. An induction heating device is installed in the intermediate weir hole, and the molten metal in the two strand chambers is soaked by the induction heating device.

Further, in order to efficiently operate continuous casting, it is necessary to prevent inclusions in the tundish from flowing out into the mold.
As means for preventing the outflow of inclusions in the tundish, there are those disclosed in Patent Documents 4 to 6.
Patent Document 4 aims to prevent large inclusions in a tundish from flowing into a mold when molten steel is distributed. Specifically, in a tundish where an injection chamber and a strand chamber are partitioned by a weir, one or two holes are opened in the weir. The direction of the weir hole is such that the outflow region where the molten steel flows directly into the mold injection hole and the direct feed flow of the molten steel to the mold injection hole is easily removed is removed. By setting the direction of such a weir hole, outflow of large inclusions is prevented.

  Patent Document 5 aims to improve the floating separation of inclusions in a tundish into which molten steel has been injected. Specifically, in a tundish where a low weir is installed at the bottom between the pouring position from the molten steel pan and the mold pouring chamber, the weir has one hole facing the mold pouring chamber (molten steel channel) Is open. In front of the dam hole, a collision member having an inclined surface rising from the bottom toward the mold injection chamber side is installed so that the flow from the molten steel pan is not directly sent to the dam hole. Is flowing to the upper part of the tundish, thereby promoting the floating separation of inclusions.

  Patent Document 6 aims to improve the floating separation of inclusions in a tundish into which molten steel has been injected. Specifically, an inclined portion having a surface rising from the bottom toward the mold injection chamber side is provided on the inner wall surface side between the pouring position from the molten steel pan and the mold injection chamber, and the molten steel is used as the inclined portion. The upward flow of molten steel is promoted by keeping along.

JP 2014-113634 A JP-A-6-142855 Japanese Utility Model Publication No. 3-106243 JP 2005-131661 A JP 2003-245757 A JP 2008-254028 A

In Patent Document 1, since the direction of the weir holes (runners) is directed between the predetermined strands, the molten steel can be smoothly circulated, and variations in the molten steel temperature between the strands are reduced.
However, in this document, it is only a regulation that the direction of the weir hole is aimed so that the molten steel flows between the predetermined strands, so it is very rare, but depending on the conditions of actual operation It is conceivable that a direct flow of molten steel to the mold injection hole occurs. Therefore, it is possible that the molten steel temperature varies, although the possibility is low.

On the other hand, since Patent Document 2 does not clearly define the target position of the molten steel flow in the strand chamber so that the molten steel flows smoothly in the strand chamber, depending on the actual operation conditions, the molten steel in the mold injection hole There is a risk that a direct flow of this will occur.
Therefore, there is a great possibility that the variation in molten steel temperature becomes large. Even if a plasma heating apparatus is used, unless the direction of the molten steel flow is optimized, there is a possibility that the variation in molten steel temperature between the strands will increase.

In Patent Document 3, the molten metal in the two strand chambers is soaked by an induction heating device to reduce variations in molten steel temperature between the strands.
However, in the weir hole provided between the left and right strand chambers, the flow of molten steel is weak, so that inclusions that flow into the weir hole are retained, so the inner diameter of the weir hole becomes gradually narrower. There is a possibility that the inside will be clogged by many accumulated inclusions.

In addition, depending on the direction of the weir hole between the injection chamber and the strand chamber, there is a possibility that the molten steel flows into the mold injection hole on one side and a direct feed flow of the molten steel occurs. Therefore, the variation in molten steel temperature between the strands may increase.
In the above technique, in the multi-strand tundish, the molten steel flowing out from the injection chamber to the strand chamber preferentially flows into the mold injection hole (strand) near the injection chamber, including the direct feed flow, and is close to the injection chamber. In the mold injection hole, the molten steel temperature becomes high. On the other hand, in the mold injection hole far from the injection chamber, the molten steel having a low temperature flows. That is, there is a possibility that the variation of the molten steel temperature in the multi-strand tundish becomes large.

In addition, in the mold injection hole far from the injection chamber, the molten steel having a low temperature flowing in is solidified, so that the inner diameter of the mold injection hole is narrowed, which may cause nozzle clogging.
Although Patent Document 4 prevents the direct flow of molten steel to the mold injection hole, there is a risk that the variation in molten steel temperature between the strands may increase depending on the actual operating conditions. In the technique of the same document, since the jet flow from the weir hole does not exceed the mold injection hole near the weir, especially when it is applied to a tundish of 4 strands or more, the variation of the molten steel temperature in the tundish is reduced. It is impossible to make it happen.

Patent Documents 5 and 6 prevent direct flow of molten steel to the mold injection hole, but are techniques applicable to a tundish provided with one mold injection hole in each strand chamber. When it is applied to the multi-strand tundish, it is considered that variations in molten steel temperature cannot always be reduced.
Therefore, in view of the above problems, the present invention has a difference in arrival time of molten steel flowing in each mold injection hole in a T-shaped tundish in a plan view, which has an injection chamber and a strand chamber having a plurality of mold injection holes. The purpose of the present invention is to provide a continuous casting tundish capable of suppressing variations in molten steel temperature between strands in the tundish and a continuous casting method using the tundish. .

In order to achieve the above-described object, the present invention takes the following technical means.
The tundish for continuous casting according to the present invention includes an injection chamber into which molten steel from a ladle is poured, a front side of the injection chamber, which is elongated in the left-right direction from the injection chamber, and the molten steel at the bottom. A strand chamber having a plurality of mold injection holes for charging the mold into the mold, a partition weir for partitioning the injection chamber and the strand chamber, and provided in the partition weir and linearly penetrates from the injection chamber to the strand chamber In the tundish provided with a runner, the runner is shifted to the left obliquely in the horizontal direction in plan view, and in the side view, from the bottom side of the injection chamber, from the inner wall surface of the partition weir to the upper part of the strand chamber Side, the first runner penetrating linearly toward the inner wall surface of the partition weir, and the horizontal side obliquely shifted to the right in plan view, and the bottom side of the injection chamber in side view, the interior of the partition weir From the wall to the upper side of the strand chamber A second runner penetrating linearly toward the inner wall of the partition weir, and the runner is between the first runner and the second runner, A third runner that moves horizontally or downward from the pouring chamber toward the strand chamber in a side view and penetrates linearly in a front-rear direction in a plan view, and is disposed adjacent to the third runner Has a fourth runner that moves horizontally or downward from the injection chamber toward the strand chamber in a side view and penetrates in a straight line in a front-rear direction in a plan view, One of the plurality of mold injection holes includes a point where an extension line of a central axis that faces the horizontal direction of the third runner intersects the front side wall surface, and a center that faces the horizontal direction of the fourth runner An extension line of an axis is provided in a region between two points with respect to a point intersecting the front side wall surface, and the other mold The entrance hole is located in a region on the outer side in the left-right direction with respect to the extension line of the central axis facing the horizontal direction of the first runner facing upward and the extension line of the central axis facing the horizontal direction of the second runway facing upward. And the bottom of the strand chamber connected to the outlet of the third runner and the outlet of the fourth runner is located below the lower end of the outlet of the third runner and the outlet of the fourth runner, and (1) to (8) are satisfied.

d ₁ ≦ 0.3 [m] (1)
D ₁ ≦ 0.3 [m] (2)
_{x 1 ≧ 0.1z 1 + D 2} /2 [m] ··· (3)
θ ₁ ≦ 60 [deg.] (4)
z ₂ tanθ ₂ -0.1z ₁ / cosθ ₂ ≧ H / 3 [m] (5)
z ₂ tanθ ₂ + D ₁ + 0.1z ₁ / cosθ ₂ ≦ H [m] (6)
x ₂ ≧ 0.1 (z ₁ + z ₃ ) + (d ₂ + D ₂ ) / 2 [m] (7)
_{x 4 ≧ 0.1z 3 + d 2} /2 [m] ··· (8)
d ₁ : Length of the third and fourth runners
d ₂ : Horizontal diameter of the third and fourth runners
D ₁ : Length of the first runway and the second runway
D ₂ : Horizontal diameter of the first runway and the second runway
x ₁ : The point where the extension of the central axis of the first runway and the second runway facing upward intersects with the front wall surface of the strand chamber, and the vertical direction of the mold injection hole on the nearest side to the partition weir Distance from the point where the horizontal extension line passing through the central axis intersects the front wall surface of the strand chamber
θ ₁ : Extension of the central axis of the first runner and the second runner facing upward The horizontal angle on the center side in the width direction of the strand chamber at the point intersecting the front wall surface of the strand chamber
θ ₂ : upward angle of the first runway and the second runway facing upward
z ₁ : The horizontal length of the strand chamber on the extension line of the axial center of the first runner and the second runner facing upward
z ₂ : Horizontal distance from the front end of the injection chamber to the front side wall surface of the strand chamber in the axial center of the first runner and the second runner facing upward
z ₃ : Horizontal length of the strand chamber on the extension line of the axis of the third or fourth runway that faces horizontally or downward
H: Depth of molten steel
x ₂ : The extension line of the central axis of the first runway or the second runway intersects the front side wall surface of the strand chamber, and the extension line of the central axis of the third runway or the fourth runway is the front side of the strand chamber Distance between wall and intersection
x ₄ : The point where the extension line of the center axis of the third runway or the fourth runway intersects the front side wall surface of the strand chamber and the center facing the vertical direction of the mold injection hole located in the region between the two points The distance from the point where the horizontal extension line passing through the shaft intersects the front wall surface of the strand chamber Preferably, the strand chamber is in front of the injection chamber and abuts the front wall surface of the strand chamber. The protrusions are provided so as to stand upward from the bottom of the strand chamber, and the protrusions are provided in a pair on the left and right sides with a predetermined interval, and the expressions (9) to (12) are provided. It is good to meet.

y ≧ 0.1 [m] (9)
L ≧ 0.2 [m] (10)
_{d 1 + 0.1z 1 ≦ h ≦} z 2 tanθ 2 -0.1z 1 / cosθ 2 [m] ··· (11)
_{x 3 ≧ 0.1z 3 + d 2} /2 [m] ··· (12)
y: Length of the protrusion in the front-rear direction
L: Width of protrusion
h: Height of protrusion
x ₃ : The point where the extension line of the central axis of the third or fourth runway intersects the front side wall surface of the strand chamber, and the extension line side of the central axis of the third or fourth runway in the projection. The distance from an edge part The continuous casting method concerning this invention is characterized by performing continuous casting using said tundish for continuous casting.

  According to the present invention, in a T-shaped tundish in a plan view having a pouring chamber and a strand chamber having a plurality of casting mold injection holes, by controlling the difference in arrival time of the molten steel flowing in each casting mold hole, It is possible to suppress variations in molten steel temperature between the strands in the tundish.

It is a top view of the tundish for continuous casting of the present invention. It is the figure which expanded a part of tundish of this invention, and is a top view which shows the shape of a partition weir. It is side sectional drawing to which a part of tundish of this invention was expanded. It is the 1st figure showing the shape of the bottom of a strand room. It is a 2nd figure which shows the shape of the bottom part of a strand chamber. It is FIG. 3 which shows the shape of the bottom part of a strand chamber. It is the figure which showed the shape of the runner formed in the tundish of this invention. It is the figure which showed the maintenance condition of the tundish in case the penetration shape of the runway of a partition weir is made into linear form. It is the figure which showed the maintenance condition of the tundish when it is set as the penetration shape bent in the middle of the runway of a partition weir. Is a plan view showing an example of a shape of the first runner and a second runner to the present invention _{(x 1 ≧ 0.1z 1 + D} 2/2). It is a plan view showing an example of out of the specified range in the shape of the first runner and a second runner _{(x 1 <0.1z 1 + D} 2/2). It is a top view which shows the horizontal angle of the 1st runway and the 2nd runway concerning this invention ((theta) ₁ <= 60). It is a top view which shows an example outside the regulation range in the horizontal angle of a 1st runway and a 2nd runway ((theta) ₁ > 60). It is a side sectional view showing the vertical angle of the first runner and a second runner according to the present invention _{(z 2 tanθ 2 -0.1z 1 /} cosθ 2 ≧ H / 3). It is a side sectional view showing an example of out of the specified range in the vertical direction of the angle of the first runner and a second runner _{(z 2 tanθ 2 -0.1z 1 /} cosθ 2 <H / 3). Is a side sectional view showing the vertical angle of the first runner and a second runner according to the present invention _{(z 2 tanθ 2 + D 1} + 0.1z 1 / cosθ 2 ≦ H). It is a side sectional view showing an example outside the specified range in the vertical angle of the first runner and the _second runner (z ₂ tanθ ₂ + D ₁ + 0.1z ₁ / cos θ ₂ > H). Is a plan view showing an example of a shape of the first runner to fourth runner to the present invention _{(x 2 ≧ 0.1 (z 1} + z 3) + (d 2 + D 2) / 2). Is a plan view showing an example of out of the specified range in the shape of the first runner to fourth runner _{(x 2 <0.1 (z 1} + z 3) + (d 2 + D 2) / 2). Is a plan view showing an example of a shape of the third runner and a fourth runner to the present invention _{(x 4 ≧ 0.1z 3 + d} 2/2). It is the figure which expanded a part of tundish of this invention, and is a top view which shows the shape of the partition weir and the shape of the protrusion provided in the bottom part of the strand chamber. It is the figure which expanded a part of tundish of this invention, and is sectional drawing which shows the shape of the protrusion provided in the bottom part of the strand chamber. It is a top view which shows an example of the shape of the protrusion concerning this invention (y> = 0.1). It is a top view which shows an example outside the regulation range in the shape of a protrusion (y <0.1). It is a top view which shows another example of the shape of the protrusion concerning this invention. Is a side sectional view showing an example of the shape of a projection according to the present invention _{(h ≦ z 2 tanθ 2 -0.1z} 1 / cosθ 2). Is a side sectional view showing an example of out of the specified range in the shape of the projection _{(h> z 2 tanθ 2 -0.1z} 1 / cosθ 2). Is a side sectional view showing an example of the shape of a projection according to the present invention _{(d 1 + 0.1z 1 ≦ h} ). It is a side sectional view showing an example outside the regulation range in the shape of the projection (d ₁ + 0.1z ₁ > h). It is side sectional drawing which shows another example of the shape of the protrusion concerning this invention. Is a plan view showing an example of a position of the protrusion according to the present invention _{(x 3 ≧ 0.1z 3 + d} 2/2). Is a plan view showing an example of out of the specified range in the position of the projection _{(x 3 <0.1z 3 + d} 2/2). It is a figure which shows the measurement position of the molten steel temperature T in a tundish. It is a figure which shows the shape of the tundish used when carrying out water model experiment. It is a figure which shows the tundish of the shape A used when calculating numerically. It is a figure which shows the tundish of the shape B used when calculating numerically. It is a figure which shows the tundish of the shape C used when calculating numerically. It is a figure which shows the tundish of the shape D used when calculating numerically. It is the figure which showed the calculation result of (DELTA) T in a tundish, and is a figure which shows the relationship of the difference ((DELTA) T) of the molten steel temperature in a tundish with the index ((DELTA) t / _tr ) of an arrival time difference. It is a conceptual diagram of the continuous casting apparatus to which the tundish for continuous casting of the present invention is applied.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 23, the tundish 1 for continuous casting rises from the bottom portions 2a and 2b provided with the mold injection holes 6 (strands) for inserting the molten steel 14 into the mold 17 and the peripheral edges of the bottom portions 2a and 2b. A peripheral wall 3 is provided. Hereinafter, it may be simply referred to as tundish 1.

  The tundish 1 has a plurality of strands 6 in which the molten steel 14 in the ladle 16 is poured, and a strand 6 that is in front of the casting chamber 4 and in which the molten steel 14 is charged into the mold 17 at the bottom 2b. And the strand chamber 5 in which the molten steel 14 is cast into the mold 17 via the strand 6, and the partition weir 8 that partitions the injection chamber 4 and the strand chamber 5. It is assumed to be long in the direction.

That is, the object of the present invention is a multi-strand tundish having a T shape in plan view and having a plurality of strands 6. The number of strands 6 is an odd number of 5 or more.
The injection chamber 4 has a bottom 2a where no strands 6 are provided, three peripheral walls 3 standing upward from each of the three peripheral edges of the bottom 2a, and a partition that divides the strand chamber 5 so as to be divided. It is composed of a portion surrounded by the weir 8. On the other hand, the strand chamber 5 includes a bottom portion 2b in which a plurality of strands 6 are provided, a peripheral wall 3 erected upward from each peripheral edge of the bottom portion 2b, and a partition weir 8 that partitions the strand chamber 5 and the injection chamber 4 from each other. It is composed of the part surrounded by.

FIG. 2A is a diagram showing the configuration of the tundish 1 of the present invention, and is an enlarged plan view of a part of the injection chamber 4 and the strand chamber 5 partitioned by the partition weir 8. 2B is a partial cross-sectional view of the strand chamber 5 (a part of the AA cross-section of FIG. 1).
3A and 3B are sectional views of the injection chamber 4 and the strand chamber 5 (cross section AA in FIG. 1). 3C is also a cross-sectional view of the injection chamber 4 and the strand chamber 5, and corresponds to the AA cross section of FIG.

First, an outline of the runner 9 (weir hole) provided in the tundish 1 of the present invention will be described with reference to FIGS. 2A, 2B, 3A, and 3B. 2A and 2B, the shape and dimensions of the runner 9 and the protrusion 11, that is, the characteristic configuration of the tundish 1 of the present invention will be described in detail later.
As shown in FIGS. 2A, 2B, 3A, and 3B, the partition weir 8 that partitions the injection chamber 4 and the strand chamber 5 is provided with a runner 9 that linearly penetrates from the injection chamber 4 to the strand chamber 5. ing. That is, the injection chamber 4 and the strand chamber 5 are connected by the runner 9 opened at the lower part of the partition weir 8.

In the partition weir 8 of the tundish 1, a plurality of runners 9 for communicating the injection chamber 4 and the strand chamber 5 are formed.
The runner 9 is shifted obliquely to the left in the horizontal direction as it goes from the injection chamber 4 to the strand chamber 5 in plan view, and in the side view, on the bottom 2a side of the injection chamber 4 and the lower end of the inner wall surface of the partition weir 8 (partition A runner 9a (first runner) penetrating in a straight line from the lower end of the rear wall of the weir 8 to the upper side of the strand chamber 5, toward the inner wall of the partition weir 8 (front wall of the partition weir 8), and a plane As viewed from the injection chamber 4 toward the strand chamber 5, it moves to the diagonally right side in the horizontal direction, and in the side view, from the bottom 2 a side of the injection chamber 4, from the lower end of the inner wall surface of the partition weir 8 to the upper side of the strand chamber 5, A runner 9b (second runner) penetrating linearly toward the inner wall surface of the partition weir 8 is provided.

  Furthermore, the runner 9 is between the first runner 9a and the second runner 9b, and moves in a horizontal or downward direction from the injection chamber 4 to the strand chamber 5 in a side view, and is flat. The runner 9c (third runner) penetrating in a straight line so as to connect the bottom 2a of the injection chamber 4 and the bottom 2b of the strand chamber 5 so as to face in the front-rear direction, and disposed adjacent to the runner 9c The bottom portion 2a of the injection chamber 4 and the bottom portion 2b of the strand chamber 5 are shifted from the injection chamber 4 to the strand chamber 5 in a side view and are moved horizontally or downward in a side view and in the front-rear direction in a plan view. The runner 9d (fourth runner) that penetrates in a straight line is connected.

Here, when the bottom portion 2b of the strand chamber 5 which is connected to the outlets 10c and 10d of the runners 9c and 9d is viewed, the inner surface of the bottom portion 2b is the outlet 10c of the runners 9c and 9d. It is located below the lower end of 10d.
That is, in the present invention, the bottom 2b of the strand chamber 5 connected to the outlets 10c, 10d of the runners 9c, 9d is the same height as the lowermost end of the outlets 10c, 10d of the runners 9c, 9d (FIG. 3A). Or a position lower than the lowermost ends of the outlets 10c and 10d of the runners 9c and 9d (see FIG. 3B).

As described above, the present invention is directed to the tundish 1 having the structure illustrated in FIGS. 3A and 3B.
On the other hand, FIG. 3C shows a case where the runners 9c and 9d are formed in the partition weir 8 and when the bottom 2b connected to the outlets of the runners 9c and 9d is seen, the bottom 2b is connected to each runner 9c, The tundish in the case where it is located above the lower end of the exit of 9d is shown.

However, in the present invention, the tundish having the structure shown in FIG. 3C is excluded. In other words, in the present invention, the bottom 2b of the strand chamber 5 is not intended to be higher than the lowermost end of the outlets of the runners 9c and 9d.
FIG. 4 is a cross-sectional view of the partition weir 8 taken along the width direction and perpendicularly (BB cross section in FIG. 1). As shown in FIG. 4, the cross-sectional shape of the runner 9 (the first runner 9a to the fourth runner 9d) formed in the partition weir 8 may be a circle, an ellipse, or a quadrangle. Or it may be a flat circle.

By the way, when the tundish 1 is maintained, the tundish 1 is tilted by approximately 90 degrees, and then oxygen or the like is blown from the oxygen pipe 20 so that the heat of combustion of oxygen enters the runway 9 (weir hole). Melt the attached metal and remove the metal.
As shown in FIG. 5A, if the runner 9 has a shape penetrating linearly from the injection chamber 4 to the strand chamber 5, the metal in the runner 9 is removed without causing the partition weir 8 to melt. Can do.

However, as shown in FIG. 5B, when the runner 9 connecting the injection chamber 4 and the strand chamber 5 has a penetrating shape bent in the middle, the partition weir 8 may be melted depending on the maintenance situation. .
Therefore, the runner 9 (the first runner 9a to the fourth runner 9d) needs to penetrate the partition weir 8 linearly from the injection chamber 4 to the strand chamber 5.

Hereinafter, the configuration of the tundish 1 of the present invention will be described in more detail with reference to the drawings.
Henceforth, let the front-back direction of the strand chamber 5 be a depth direction, and let the left-right direction of the strand chamber 5 be the width direction. This coincides with the front-rear direction and the left-right direction of the tundish 1.
The first runway 9a is referred to as a first dam and the second runway 9b is referred to as a second dam. In addition, the third runway 9c is referred to as a first bottom dam hole, and the fourth runway 9d is referred to as a second bottom dam hole.

2A and 2B, one of the plurality of strands 6 provided in the bottom portion 2b of the strand chamber 5 has an extension line of the central axis facing the horizontal direction of the first bottom dam hole 9c, and the front wall 7 a point of intersection with respect to, between two points of the point where the extension line of the center axis oriented in the horizontal direction of the second bottom Sekiana 9d crosses with respect to the front wall 7 (between intersections a ₆ and the intersection a ₇₎ Is provided in the area.
That is, one of the strands 6 is disposed in front of the center in the left-right direction of the partition weir 8 in plan view.

The other strands 6 are located in a region on the left side outside the extension line of the central axis facing the horizontal direction of the first dam hole 9a in plan view. Moreover, the strand 6 is located in the area | region on the right outer side from the extension line of the central axis which faces the horizontal direction of the 2nd dam hole 9b.
That is, the strand 6 is provided at the bottom 2b of the strand chamber 5 and outside the extension line of the central axis of the first dam hole 9a and the extension line of the central axis of the second dam hole 9b.

As shown in FIG. 4, “d ₁ ” is an inner diameter (vertical diameter) in the vertical (up and down) direction when the first bottom dam hole 9 c and the second bottom dam hole 9 d are vertically sectioned.
The vertical diameter “d ₁ ” of each bottom weir hole 9c, 9d is 0.3 m or less as shown in the equation (1).
d ₁ ≦ 0.3 [m] (1)
However, when the vertical diameter d _{1 of} each bottom dam hole 9c, 9d exceeds 0.3 m, most of sand etc. that has fallen from the nozzle when the nozzle of the ladle 16 is opened passes through each bottom dam hole 9c, 9d. Therefore, it becomes easy to flow into the strand chamber 5. If a large amount of sand at the time of opening the ladle 16 enters the strand chamber 5 through the bottom dam holes 9c and 9d, inclusion defects tend to occur.

From the above, by setting the vertical diameter d ₁ of the first bottom dam hole 9c and the second bottom dam hole 9d to 0.3 m or less, the sand can be floated not on the strand chamber 5 but on the injection chamber 4 side.
“D ₂ ” is the horizontal inner diameter (lateral diameter) when the bottom weir holes 9 c and 9 d are cut vertically.
Further, as shown in FIG. 4, “D ₁ ” is an inner diameter (vertical diameter) in the vertical (up and down) direction when the first dam hole 9 a and the second dam hole 9 b are vertically sectioned.

The vertical diameter “D ₁ ” of the first dam hole 9a and the second dam hole 9b is 0.3 m or less as shown in the equation (2).
D ₁ ≦ 0.3 [m] (2)
However, if the longitudinal diameter d ₁ of the longitudinal diameter D ₁ of the first Sekiana 9a and the second Sekiana 9b exceeds 0.3 m, the majority of the sand dropped from the nozzle at the opening of the nozzle of the ladle 16 It becomes easy to flow into the strand chamber 5 through each dam hole 9a, 9b. If a large amount of sand at the time of opening of the ladle 16 enters the strand chamber 5 through the weir holes 9a, 9b, inclusion defects are likely to occur.

Thus, each weir holes 9a facing upward, the vertical diameter D ₁ of the 9b by below 0.3 m, it is possible to float the sand in strand chamber 5 without injection chamber 4 side.
As shown in FIG. 2A and FIG. 6A, “x ₁ ” indicates that the central axis of the first dam hole 9 a and the second dam hole 9 b in a plan view is the front wall surface 7 (front wall) of the strand chamber 5 facing. The distance between the intersecting point and the point that intersects with the front wall 7 of the strand chamber 5 is the straight line that faces the front and rear direction passing through the center of the strand 6 that is closest to the partition weir 8 (the above-described left and right outer region). That is, the distance “x ₁ ” is the distance between the intersection point a ₁ and the intersection point a ₂ or the distance between the intersection point a ₃ and the intersection point a ₄ .

This distance “x ₁ ” satisfies Expression (3).
_{x 1 ≧ 0.1z 1 + D 2} /2 [m] ··· (3)
However, “z ₁ ” is the distance from the outlet of each weir hole 9a, 9b to the front wall 7 of the strand chamber 5 on the extension line of the central axis (axial center) of the first weir hole 9a and the second weir hole 9b. (The length of the strand chamber 5).

“D ₂ ” is an inner diameter (lateral diameter) in the left-right direction when the transverse diameters of the first dam hole 9 a and the second dam hole 9 b are vertically sectioned (see FIG. 4).
Formula (3) is a formula representing the relationship between the jet flow (upward jet flow) flowing out from the outlets of the respective weir holes 9 a and 9 b and the position of the strand 6 closest to the partition weir 8. “0.1z” is the theoretical formula for the spreading width (one side) of the upward jet, and is described in “N. Rajaratnam, translated by Nomura Yasumasa:“ Jet ”Morikita Publishing (1985) p.43”. .

However, as shown in Fig. 6B, the distance x ₁ is below than above provisions _{(x 1 <0.1z 1 + D} 2/2) If, Kakusekiana 9a, is upward jet flowing out from the outlet of 9b, the strands The distance between the position colliding with the front wall 7 of the chamber 5 and the strand 6 near the partition weir 8 will be too close. That is, the distance between the intersection point a ₁ and the intersection point a ₂ (the intersection point a ₃ and the intersection point a ₄ ) is shortened.
If it becomes such a positional relationship, the upward jet flow which flowed out and spread will deviate in the left-right direction in front of the front wall 7. As a result, a direct flow to the strand 6 near the partition weir 8 is likely to occur.

As shown in FIGS. 2A and 7A, “θ ₁ ” is an extension of the central axis of the first dam hole 9 a and the second dam hole 9 b facing upward in plan view, and the front wall 7 of the strand chamber 5. Is the angle in the horizontal direction (horizontal angle), and represents the angle on the center side in the width direction of the strand chamber 5.
That is, the equation (4) is an equation representing a horizontal angle at which the upward jet flowing out from the outlets of the respective weir holes 9 a and 9 b collides with the front wall 7 of the strand chamber 5.

This horizontal angle “θ ₁ ” satisfies Expression (4).
θ ₁ ≦ 60 [deg.] (4)
However, as shown in FIG. 7B, when the horizontal angle θ ₁ exceeds 60 [deg.], The upward jet that collides with the front wall 7 is difficult to spread outward in the left-right direction. As a result, the temperature difference of the molten steel 14 is likely to occur between the strand 6 near (the nearest side) the partition weir 8 and the strand 6 far from the partition weir 8.

As shown in FIG. 2B and FIG. 8A, the upward flowing out from the outlet 10a of the first dam hole 9a and the outlet 10b of the second dam hole 9b provided on both outer sides of the partition weir 8 in a side sectional view. The lower end position (the lower end height of the upward jet viewed from the bottom 2b) when the jet collides with the front wall 7 of the strand chamber 5 satisfies the formula (5).
z ₂ tanθ ₂ -0.1z ₁ / cosθ ₂ ≧ H / 3 [m] (5)
However, “θ ₂ ” is an angle on the inner side in the vertical direction at the point where the extension line of the central axis of each weir hole 9a, 9b facing upward in the side sectional view intersects the front wall 7 of the strand chamber ( Upward angle).

“Z ₁ ” is the horizontal length (horizontal distance) of the strand chamber 5 on the extension of the axial center of each weir hole 9a, 9b facing upward.
“Z ₂ ” is a horizontal distance from the front end of the injection chamber 4 to the front wall 7 of the strand chamber 5 in the axial center of each of the weir holes 9 a and 9 b facing upward.
“H” is the depth of the molten steel 14 in the strand chamber 5.

However, as shown in FIG. 8B, when the value is lower than the above (z ₂ tanθ ₂ −0.1z ₁ / cosθ ₂ <H / 3), the upward jet that collides with the front wall 7 does not become an upward flow, and the partition A direct flow to the strand 6 near the weir 8 is likely to occur. As a result, the temperature deviation increases between the strand 6 near the partition weir 8 and the strand 6 far from the partition weir 8.
As shown in FIG. 2B and FIG. 9A, the upward flowing out from the outlet 10a of the first dam hole 9a and the outlet 10b of the second dam hole 9b provided on both outer sides of the partition weir 8 in a side sectional view. The upper end position (the upper end height of the upward jet viewed from the bottom 2b) when the jet collides with the front wall 7 of the strand chamber 5 satisfies Expression (6).

z ₂ tanθ ₂ + D ₁ + 0.1z ₁ / cosθ ₂ ≦ H [m] (6)
However, as shown in FIG. 9B, when the above-mentioned regulation is exceeded (z ₂ tanθ ₂ + D ₁ + 0.1z ₁ / cosθ ₂ > H), the upward jet flows on the molten steel surface before colliding with the front wall 7. It will reach and a downward flow will occur. As a result, the direct flow to the strand 6 near each dam hole 9a, 9b is likely to occur.

As shown in FIG. 2A and FIG. 10A, “x ₂ ” is the position where the upward jet flowing out from the outlet 10 a of the first weir hole 9 a facing upward in plan view collides with the front wall 7. The distance from the position where the bottom jet flowing out from the outlet 10c of the first bottom dam hole 9c collides with the front wall 7, or the position where the upward jet flowing out from the outlet 10b of the second dam hole 9b collides with the front wall 7, This is the distance from the position where the bottom jet flowing out from the outlet 10d of the second bottom weir hole 9d collides with the front wall 7.

In other words, the distance “x ₂ ” indicates that the extension line of the central axis of the first dam hole 9a intersects the front wall 7 of the strand chamber 5 and the extension line of the central axis of the first bottom dam hole 9c, The distance between the point intersecting the front wall 7 of the strand chamber 5 or the extension line of the central axis of the second weir hole 9b intersects the front wall 7 of the strand chamber 5, and the second bottom weir hole The extension line of the central axis of 9d is the distance between the front wall 7 of the strand chamber 5 and the point where it intersects.

That is, the distance “x ₂ ” is the distance between the intersection point a ₁ and the intersection point a ₆ or the distance between the intersection point a ₃ and the intersection point a ₇ .
This distance “x ₂ ” satisfies Expression (7).
x ₂ ≧ 0.1 (z ₁ + z ₃ ) + (d ₂ + D ₂ ) / 2 [m] (7)
However, “z ₃ ” is the horizontal length in the front-rear direction of the strand chamber 5 on the central axis of each bottom weir hole 9c, 9d that faces horizontally or downward.

However, as shown in FIG. 10B, when the value is lower than the above-mentioned regulation (x ₂ <0.1 (z ₁ + z ₃ ) + (d ₂ + D ₂ ) / 2), it flows out from the outlet 10a of the first dam hole 9a. The upward jet and the bottom jet that flows out from the outlet 10c of the first bottom dam hole 9c, or the upward jet that flows out from the outlet 10b of the second dam hole 9b, and the outlet 10d of the second bottom dam hole 9d The bottom jets interfere with each other, and the bottom jets are less likely to be an upward flow. As a result, the direct flow to the strands 6 near the respective weir holes 9a and 9b is likely to occur.

As shown in FIG. 11, "x _4" are that the bottom Sekiana 9c, the extension line of 9d central axis intersects the front wall 7, between two points (between intersections a ₆ and the intersection a ₇₎ Of the strand 6 arranged in front of the center in the left-right direction of the partition weir 8 and the distance from the point where the horizontal extension line passing through the central axis facing the vertical direction intersects the front wall 7. is there. That is, the distance “x ₄ ” is the distance between the intersection point a ₅ and the intersection point a ₆ or the distance between the intersection point a ₅ and the intersection point a ₇ .

This distance “x ₄ ” satisfies Expression (8).
_{x 4 ≧ 0.1z 3 + d 2} /2 [m] ··· (8)
However, below a defined above _{(x 4 <0.1z 3 + d} 2/2) where each bottom Sekiana 9c, the bottom jet from 9d, and in front of the partition weir 8, the first bottom Sekiana 9c Direct flow to the strand 6 arranged in the region between the extension line of the central axis and the extension line of the central axis of the second bottom dam hole 9d is likely to occur.

As shown in FIGS. 12A and 12B, in the tundish 1 of the present invention, on the front inner wall surface (front wall 7) side of the strand chamber 5 on the front side of the injection chamber 4 side, The protrusion 11 (step part) which contact | abutted and was erected upright from 5 bottom part 2b of a strand chamber is provided.
The protrusions 11 are provided in a pair of left and right sides with a predetermined interval, and are substantially rectangular in a side sectional view.

As shown in FIGS. 12A and 13A, “y” is the length in the front-rear direction of the protrusion 11 provided on the front wall 7 of the strand chamber 5 in plan view. That is, “y” is the thickness of the protrusion 11.
This thickness “y” satisfies Expression (9).
y ≧ 0.1 [m] (9)
In addition, the space between the protrusions 11 provided on the left and right sides, that is, the concave portion in plan view, is the flow of the bottom jet that flows out from the outlets 10c and 10d of the bottom weir holes 9c and 9d (thick line arrows in FIG. 13A). It plays the role of a guide to make an upward flow.

However, as shown in FIG. 13B, when the thickness y of the projection 11 is less than 0.1 m, that is, when the thickness y of the projection 11 is small, the space (concave portion) sandwiched between the left and right projections 11 provided. Therefore, the role of the guide that makes the bottom jet flowing out from the bottom weir holes 9c and 9d upward is weakened. That is, it becomes difficult for the bottom jet to become an upward flow.
12A and 13A, “L” is the length in the left-right direction of the protrusion 11 in plan view. That is, “L” is the width of the protrusion 11.

This width “L” satisfies Expression (10).
L ≧ 0.2 [m] (10)
However, when the width L of the protrusion 11 is less than 0.2 m, the durability of the protrusion 11 is lowered, and the molten steel flow tends to cause erosion / deficiency.
In addition, about the shape in the horizontal cross section view (plan view) of the protrusion 11, a rectangular shape may be sufficient as shown to FIG. 12A and FIG. 13A, and a circular arc shape may be sufficient as shown in FIG.

As shown in FIGS. 12B, 15A, and 16A, “h” is the height of the protrusion 11 in a side sectional view.
As shown in FIG. 15A, the height “h” satisfies (h ≦ z ₂ tan θ ₂ −0.1z ₁ / cos θ ₂ ). Also, as shown in FIG. 16A, the height “h” satisfies (d ₁ + 0.1z ₁ ≦ h).
That is, the height “h” satisfies the expression (11).

_{d 1 + 0.1z 1 ≦ h ≦} z 2 tanθ 2 -0.1z 1 / cosθ 2 [m] ··· (11)
However, as shown in FIG. 15B, the width height h of the projection 11 exceeds the specified above _{(h> z 2 tanθ 2 -0.1z} 1 / cosθ 2) where each facing upward weir hole 9a, The upper end of the projection 11 becomes higher than the lower end of the upward jet flow that flows out from the outlets 10a and 10b of the 9b, and the upward jet flow from the dam holes 9a and 9b is obstructed.

As a result, the upward jet that has collided with the front wall 7 becomes weak in the flow spreading outward in the strand chamber 5 (tundish 1), and a direct flow to the strand 6 near each dam hole 9a, 9b is likely to occur. Become.
Further, as shown in FIG. 16B, when the width h of the protrusion 11 is lower than the above-mentioned regulation (d ₁ + 0.1z ₁ > h), from the upper ends of the bottom jets flowing out from the bottom weir holes 9c and 9d The upper end of the protrusion 11 is lowered, and the role of the guide for making the bottom jet flow from the bottom dam holes 9c and 9d upward is weakened. That is, it becomes difficult for the bottom jet to become an upward flow.

In addition, as shown in FIG. 17, about the shape in the vertical cross sectional view (side cross sectional view) of the protrusion 11, what is necessary is just a substantially rectangular shape, and a corner | angular part may be made into a chamfer (roundness).
As shown in FIG. 12A and FIG. 18A, “x ₃ ” indicates that the extension line of the central axis of the first bottom dam hole 9 c or the second bottom dam hole 9 d intersects the front wall 7 and one of the protrusions 11. It is the distance between the ends.
Specifically, the extension line of the central axis of the first bottom dam hole 9c intersects the front wall 7, and the right end of the protrusion 11 arranged on the left side in plan view (on the bottom dam hole 9c side). Or the point where the extension line of the central axis of the second bottom weir hole 9d intersects the front wall 7 and the left end of the projection 11 arranged on the right side in plan view ( Distance from the bottom dam hole 9c side).

In other words, “x ₃ ” means the position where the bottom jet flowing out from the first bottom weir hole 9 c collides with the front wall 7 of the strand chamber 5 and the right end of the protrusion 11 arranged on the left side in plan view. Or the position where the bottom jet flowing out from the second bottom weir hole 9d collides with the front wall 7 of the strand chamber 5 and the left end of the projection 11 arranged on the right side in plan view. is there.
That is, the distance “x ₃ ” is the distance between the intersection point a ₆ and the intersection point a ₈ , or the distance between the intersection point a ₇ and the intersection point a ₉ .

This distance “x ₃ ” satisfies Expression (12).
_{x 3 ≧ 0.1z 3 + d 2} /2 [m] ··· (12)
However, as shown in FIG. 18B, the distance x ₃ falls below a defined above _{(x 3 <0.1z 3 + d} 2/2) where each bottom Sekiana 9c, than the spread of the bottom jet flowing out 9d, Since the space between the pair of left and right projections 11 is narrow, the role as a guide for changing the bottom jet flow into the upward flow is weakened.

As shown in FIG. 12A, “x ₅ ” indicates the center of the strand 6 located in the region on the left side of the extension line of the central axis facing the horizontal direction of the first dam hole 9a in plan view. The distance from the point where the straight line passing in the front-rear direction intersects the front wall 7 and the left end (the other end) of the protrusion 11 arranged on the left in plan view, or the second weir hole 9b A straight line facing the front-rear direction passing through the center of the strand 6 located in the region on the right side of the extension line of the central axis facing the horizontal direction intersects the front wall 7 and is arranged on the right side in a plan view. This is the distance from the right end (the other end) of the protrusion 11 that is present.

By the way, when the temperature of the molten steel 14 poured into the mold 17 is too high, there is a possibility that a breakout occurs in which the solidified shell is broken below the mold 17 and the unsolidified molten steel leaks downward.
When a breakout occurs, the leaked bullion adheres to the roll stand of the continuous casting apparatus 15 and an operation for removing it occurs. If it is difficult to remove the bullion, the roll stand must be replaced. When such a problem that requires extra work occurs, a great restoration cost of the continuous casting apparatus 15 is required, which greatly affects the production of the slab 19.

Therefore, in order to suppress the breakout described above, the molten steel temperature in the tundish 1 is controlled in a range of + 20 ° C. to 40 ° C. with respect to the liquidus temperature of the steel.
On the other hand, in continuous casting using a multi-strand tundish, a deviation occurs in the temperature of the molten steel 14 injected from each strand 6 to each mold 17. Therefore, in order to prevent breakout, the molten steel temperature in the tundish 1 is controlled based on the high temperature side of the temperature deviation of the molten steel 14.

For example, when the deviation of the temperature of the molten steel flowing out from each strand 6 installed at the bottom 2b of the strand chamber 5 is large, the molten steel is immersed in the immersion nozzle 13 installed below the strand 6 on the low temperature side of the temperature deviation of the molten steel 14. 14 may solidify and nozzle clogging may occur.
Thus, in the strand 6 where nozzle clogging has occurred, continuous casting must be stopped, which greatly affects the production of the slab 19.

From the above, it is necessary to reduce the temperature deviation of the molten steel 14, that is, to control the molten steel temperature in the tundish 1.
FIG. 19 is a diagram showing measurement positions of the molten steel temperature in the tundish 1. As shown in FIG. 19, in the present embodiment, the molten steel temperature at a depth of 0.3 m from the molten steel 14 surface is measured just above the strand 6.

  Table 1 shows the relationship between the measured deviation of the molten steel temperature in the tundish 1 and nozzle clogging in the submerged nozzle 13 generated by the influence of the molten steel 14 whose temperature has been lowered.

As can be seen from Table 1, when the temperature deviation of the molten steel 14 measured above the strand 6 in the tundish 1 and at a depth of 0.3 m from the molten metal surface is controlled to 7 ° C. or less, the molten steel is lowered in temperature. It can be confirmed that nozzle clogging due to the influence of 14 does not occur.
If the tundish 1 of the present invention described above is used, the temperature deviation of the molten steel 14 can be reduced, that is, variations in the molten steel temperature between the strands 6 in the multi-strand tundish can be suppressed, so the temperature is low. The nozzle clogging in the strand 6 into which the molten steel 14 flows (low ΔT side) and the breakout below the mold 17 by the strand 6 into which the molten steel 14 having a high temperature flows (high ΔT side) can be suppressed.
[Example]
First, a water model experiment will be described.

In the water model experiment, water was considered as molten steel 14 and the experiment was conducted with a 1/3 model similar to the actual machine. The tundish 1 used in the water model experiment was a T-type tundish shown in FIG. The number of strands 6 was five.
Further, in the tundish 1 of the water model experiment, the first dam hole 9a and the second dam hole 9b provided in the partition weir 8 are obliquely left and right in the horizontal direction in a plan view from the injection chamber 4 to the strand chamber 5. And extending linearly from the bottom side inner wall surface of the injection chamber 4 toward the upper side inner wall surface of the strand chamber 5 in a side view.

Furthermore, the first bottom dam hole 9c and the second bottom dam hole 9d are between the first dam hole 9a and the second dam hole 9b, and are horizontal or horizontal from the injection chamber 4 to the strand chamber 5 in a side view. It is assumed that the transition is directed downward and penetrates linearly in the front-rear direction.
Further, the outlet 10c of the first bottom dam hole 9c and the bottom 2b of the strand chamber 5 connected to the second bottom dam hole 9d outlet 10d are positioned below the lower ends of the outlets 10c, 10d of the respective bottom dam holes 9c, 9d. ing.

  Table 2 shows the physical property values of the liquid (water) in the water model experiment.

Regarding the water flow rate, the water flow rate per unit time per strand was 9 [L / min / str], and the water flow rate per unit time in 5 strands (5 str) was 45 [L / min].
The method of water model experiment was as follows.
1) Fill the tundish 1 with water as a model of the molten steel 14, and allow water to flow through the fluid number approximation.

2) Add 50 ml of ink to the injection position of the injection chamber 4 (marked with x in FIG. 20), take a picture of how the ink flows through a video camera, and reach each strand 6 in the strand chamber 5 after adding the ink. Measure the time to complete.
The temperature deviation is large when the difference in time to reach each strand 6 is large, and the temperature deviation is small when the difference in arrival time of the strand 6 is small.

Next, numerical calculation (numerical simulation) will be described.
As numerical calculation conditions, thermal fluid analysis software: Fluent, calculation model: k-ε was used. In this numerical calculation, the 1/1 model was used which is almost the same as the actual machine. The tundish 1 used in the numerical calculation was a T-type tundish shown in FIGS. The number of strands 6 was four and five.

The tundish shown in FIG. 21A has no partition weir 8 (comparative example, shape A).
Although the tundish shown in FIG. 21B is provided with a partition weir, since the height is low, the injection chamber 4 and the strand chamber 5 are not clearly partitioned. Moreover, the runner 9 is not provided in the partition weir. That is, in the tundish shown in FIG. 21B, the molten steel 14 injected into the injection chamber 4 gets over the low partition weir and flows into the strand chamber 5 (comparative example, shape B).

A tundish 1 shown in FIG. 21C has the shape and configuration of the present invention, and is provided with a partition weir 8 that clearly separates the injection chamber 4 and the strand chamber 5 from the runner 9 (the first runner 1). Four dam holes 9a, second dam holes 9b, first bottom dam holes 9c, and second bottom dam holes 9d) are provided (Example, shape C).
The first weir hole 9a provided in the partition weir 8 has a linear shape extending upward from the injection chamber 4 toward the strand chamber 5 and extending outward in the left direction. The second weir hole 9b has a linear shape extending upward from the injection chamber 4 toward the strand chamber 5 and extending outward in the right direction.

Further, the first bottom dam hole 9 c and the second bottom dam hole 9 d have a straight shape extending horizontally or downward from the injection chamber 4 toward the strand chamber 5.
The bottom 2b of the strand chamber 5 connected to the outlet 10c of the first bottom dam hole 9c and the outlet 10d of the second bottom dam hole 9d is positioned below the lower ends of the outlets 10c and 10d of the bottom dam holes 9c and 9d. Yes.

  A tundish 1 shown in FIG. 21D has the shape and configuration of the present invention, and is provided with a partition weir 8 that clearly partitions the injection chamber 4 and the strand chamber 5, and a runner 9 (first channel) is formed in the partition weir 8. Four dam holes 9a, second dam holes 9b, first bottom dam holes 9c, and second bottom dam holes 9d) are provided. In addition, a pair of protrusions 11 are provided on the front wall 7 in the strand chamber 5 (Example, shape D).

The first weir hole 9a provided in the partition weir 8 has a linear shape extending upward from the injection chamber 4 toward the strand chamber 5 and extending outward in the left direction. The second weir hole 9b has a linear shape extending upward from the injection chamber 4 toward the strand chamber 5 and extending outward in the right direction.
Further, the first bottom dam hole 9 c and the second bottom dam hole 9 d have a straight shape extending horizontally or downward from the injection chamber 4 toward the strand chamber 5.

The bottom portion 2b of the strand chamber 5 connected to the outlet 10c of the first bottom dam hole 9c and the outlet 10d of the second bottom dam hole 9d is positioned below the lower ends of the outlets 10c, 10d of the bottom dam holes 9c, 9d. ing.
Table 3 shows calculation conditions in the numerical calculation. Tables 4 and 5 show details of dimensions and configurations of the shapes A to D of the tundish 1.

In order to estimate the temperature deviation of the molten steel 14 between the strands 6 from the deviation of the tracer arrival time to each strand 6 in the water model experiment, the relationship between the tracer arrival time and the temperature deviation of the molten steel 14 is obtained by numerical calculation. It was.
The tracer set particles having the same density as the molten steel 14 and put it into the injection position of the injection chamber 4 (marked with x in FIGS. 21A to 21D).

  Table 6 shows the results of numerical calculation of the molten steel temperature in the tundish shape B and the results when the molten steel temperature in the actual machine (tundish shape B) was actually measured.

“T _min ” is the lowest temperature of the molten steel 14 among the temperatures of the molten steel 14 above the strand 6 (0.3 m depth from the molten metal surface). “T _max ” is the highest temperature of the molten steel 14 among the temperatures of the molten steel 14 above the strand 6 (0.3 m depth from the molten metal surface). “ΔT” is a difference (T _max −T _min ) between the maximum temperature and the minimum temperature of the molten steel 14.
As shown in Table 6, as a result of actual measurement, ΔT (= T _max −T _min ) was calculated as 8 ° C., and as a result of numerical calculation, ΔT was calculated as 10 ° C. Thus, it can be confirmed that the result of the numerical calculation of the molten steel temperature has a small difference from the actually measured result and can accurately reflect the phenomenon of the actual machine.

Table 7 and FIG. 22 show the relationship between (Δt / t _r ) and ΔT in the shapes A to D of the tundish 1.

“T _r ” is the average residence time of the molten steel 14 in the tundish 1 (capacity / throughput of the tundish 1).
“T _min ” is the shortest dwell time from when the tracer (ink ink) is introduced to the injection position (A to D in FIG. 21) of the injection chamber 4 until the strand 6 is reached. “T _max ” is the longest residence time from the introduction of the tracer (ink ink) to the injection position of the injection chamber 4 until the strand 6 is reached. “Δt” is a difference (t _max −t _min ) between the longest residence time and the shortest residence time of the tracer.

It can be seen from Table 7 and FIG. 22 that (Δt / t _r ) between the strands 6 needs to be 0.18 or less in order to set ΔT to 7 ° C. or less shown in Table 1.
Note that the greater the value of (Δt / t _r ), the greater the difference in timing at which the tracer reaches each strand 6.
Next, examples and comparative examples of the tundish 1 for continuous casting in the present invention will be described.

Tables 8 to 10 show examples of the tundish 1 for continuous casting according to the present invention.
In addition, the Example of Table 8 and Table 9 is converted into a real machine based on the result by the water model shown in Table 10.

As shown in Tables 8 to 10, in the examples (No, 1 to No, 14), the number of strands 6 is five, and the number of runners 9 provided in the partition weir 8 is four. is there.
In the examples (No, 8) and thereafter, the front wall 7 is provided with a pair of left and right projections 11.
Referring to No. 1 and Table 1 (Example) in Tables 8 to 10, the cross-sectional shape of the runner 9 is circular.

Each bottom Sekiana 9c, longitudinal diameter d ₁ of 9d is 0.3 m, satisfies the formula (1). Moreover, the vertical diameter D1 of _each dam hole 9a, 9b is 0.2 m, and Formula (2) is satisfy | filled.
Distance x ₁ is 0.3 m, so and _{(0.1z 1 + D 2/2} ) is a 0.19 m, satisfies the formula (3). The horizontal angle θ ₁ is 50 [deg.], Which satisfies Expression (4).
Since (z ₂ tan θ ₂ −0.1z ₁ / cos θ ₂ ) is 0.38 and (H / 3) is 0.27 m, the expression (5) is satisfied.

Since (z ₂ tan θ ₂ + D ₁ + 0.1z ₁ / cos θ ₂ ) is 0.77 m and the depth H of the molten steel 14 is 0.8 m, the formula (6) is satisfied. Since the distance x ₂ is 1.02 m and (0.1 (z ₁ + z ₃ ) + (d ₂ + D ₂ ) / 2) is 0.46 m, Expression (7) is satisfied.
Distance x ₄ is 0.3 m, so and _{(0.1z 3 + d 2/2} ) is a 0.27 m, satisfies the equation (8).

Since (Δt / t _r ) is 0.16 and is 0.18 or less, it can be seen that the temperature deviation is small and the temperature variation of the molten steel 14 is suppressed. Moreover, it turned out that the outflow of the inclusion to the casting_mold | template 17 is also suppressed.
With reference to Nos. 2 and 2 (Examples) in Tables 8 to 10, the cross-sectional shape of the runner 9 is a flat circular shape (elliptical shape) (for example, see FIG. 4).

The vertical diameter d _{1 of} each bottom dam hole 9c, 9d is 0.2 m, which satisfies the formula (1). Moreover, the vertical diameter D1 of _each dam hole 9a, 9b is 0.2 m, and Formula (2) is satisfy | filled.
Distance x ₁ is 0.3 m, so and _{(0.1z 1 + D 2/2} ) is a 0.21 m, satisfies the formula (3). The horizontal angle θ ₁ is 60 [deg.], Which satisfies Expression (4).
Since (z ₂ tan θ ₂ −0.1z ₁ / cos θ ₂ ) is 0.33 and (H / 3) is 0.27 m, the formula (5) is satisfied.

Since (z ₂ tan θ ₂ + D ₁ + 0.1z ₁ / cos θ ₂ ) is 0.71 m and the depth H of the molten steel 14 is 0.8 m, the formula (6) is satisfied. Since the distance x ₂ is 0.73 m and (0.1 (z ₁ + z ₃ ) + (d ₂ + D ₂ ) / 2) is 0.45 m, Expression (7) is satisfied.
Since (Δt / t _r ) is 0.18, it is understood that the temperature deviation is small and the temperature variation of the molten steel 14 is suppressed. Moreover, it turned out that the outflow of the inclusion to the casting_mold | template 17 is also suppressed.

Referring to Nos. 8 and 8 (Examples) in Tables 8 to 10, the cross-sectional shape of the runner 9 is a quadrangular shape (for example, see FIG. 4).
The height (vertical diameter) d _{1 of} each bottom weir hole 9c, 9d is 0.2 m, which satisfies the formula (1). Moreover, the height (vertical diameter) D1 of _each dam hole 9a, 9b is 0.2 m, and Formula (2) is satisfy | filled.
Distance x ₁ is 0.3 m, so and _{(0.1z 1 + D 2/2} ) is at 0.2 m, satisfies the formula (3). The horizontal angle θ ₁ is 45 [deg.], Which satisfies Expression (4).

Since (z ₂ tanθ ₂ −0.1z ₁ / cosθ ₂ ) is 0.3 m and (H / 3) is 0.27 m, the formula (5) is satisfied.
Since (z ₂ tan θ ₂ + D ₁ + 0.1z ₁ / cos θ ₂ ) is 0.71 m and the depth H of the molten steel 14 is 0.8 m, the formula (6) is satisfied. Since the distance x ₂ is 1.08 m and (0.1 (z ₁ + z ₃ ) + (d ₂ + D ₂ ) / 2) is 0.42 m, Expression (7) is satisfied.

Distance x ₄ is 0.3 m, so and _{(0.1z 3 + d 2/2} ) is a 0.22 m, satisfies the equation (8).
Moreover, the thickness y of the protrusion 11 is 0.2 m, which satisfies the formula (9). The width L of the protrusion 11 is 0.2 m and satisfies the formula (10).
The height h of the protrusion 11 is _{0.3m, (d 1 + 0.1z 1} ) is 0.3m, since it is 0.3m is _{(z 2 tanθ 2 -0.1z 1 /} cosθ 2), Expression (11) is satisfied. Distance x ₃ is 0.98 m, so and _{(0.1z 3 + d 2/2} ) is a 0.22 m, satisfies the formula (12).

Since (Δt / t _r ) is 0.06 and is 0.18 or less, it can be seen that the temperature deviation is very small and the temperature variation of the molten steel 14 is suppressed. Moreover, it turned out that the outflow of the inclusion to the casting_mold | template 17 is also suppressed.
Referring to Nos. 9 and 9 (Examples) in Tables 8 to 10, the cross-sectional shape of the runner 9 is circular.

The vertical diameter d _{1 of} each bottom dam hole 9c, 9d is 0.2 m, which satisfies the formula (1). Moreover, the vertical diameter D1 of _each dam hole 9a, 9b is 0.2 m, and Formula (2) is satisfy | filled.
Distance x ₁ is 0.3 m, so and _{(0.1z 1 + D 2/2} ) is at 0.2 m, satisfies the formula (3). The horizontal angle θ ₁ is 45 [deg.], Which satisfies Expression (4).
Since (z ₂ tan θ ₂ −0.1z ₁ / cos θ ₂ ) is 0.38 m and (H / 3) is 0.27 m, the formula (5) is satisfied.

Since (z ₂ tan θ ₂ + D ₁ + 0.1z ₁ / cos θ ₂ ) is 0.79 m and the depth H of the molten steel 14 is 0.8 m, the formula (6) is satisfied. Since the distance x ₂ is 1.08 m and (0.1 (z ₁ + z ₃ ) + (d ₂ + D ₂ ) / 2) is 0.42 m, Expression (7) is satisfied.
Distance x ₄ is 0.3 m, so and _{(0.1z 3 + d 2/2} ) is a 0.22 m, satisfies the equation (8).

Moreover, the thickness y of the protrusion 11 is 0.2 m, which satisfies the formula (9). The width L of the protrusion 11 is 0.4 m and satisfies the formula (10).
The height h of the protrusion 11 is _{0.38m, (d 1 + 0.1z 1} ) is 0.3 m, since it is 0.38 m is _{(z 2 tanθ 2 -0.1z 1 /} cosθ 2), Expression (11) is satisfied. Distance x ₃ is 0.88 m, so and _{(0.1z 3 + d 2/2} ) is a 0.22 m, satisfies the formula (12).

Since (Δt / t _r ) is 0.07, it can be seen that the temperature deviation is very small and the temperature variation of the molten steel 14 is suppressed. Moreover, it turned out that the outflow of the inclusion to the casting_mold | template 17 is also suppressed.
As mentioned above, it turns out that the Example (No, 1-No, 14) shown in Table 8-Table 10 is excellent.

On the other hand, Tables 11 to 13 show comparative examples of tundish.
In addition, the comparative example of Table 11 and Table 12 performs numerical calculation based on the result by the water model shown in Table 13, and converted into an actual machine.

As shown in Tables 11 to 13, in the comparative examples (No, 1 to No, 9), the number of strands 6 is five and the number of runners 9 is four.
As for the comparative example (No, 9), the front wall 7 is provided with a pair of left and right projections 11.
Referring to Nos. 4 and 4 (comparative examples) in Tables 11 to 13, the cross-sectional shape of the runner 9 is circular. Distance x ₁ is 0.15 m, and _{(0.1z 1 + D 2/2} ) is because it is 0.19 m, does not satisfy the equation (3). Since (Δt / t _r ) is 0.22 and exceeds 0.18, the temperature deviation is large and the temperature variation of the molten steel 14 is not suppressed.

Referring to Nos. 8 and 8 (comparative examples) in Tables 11 to 13, the cross-sectional shape of the runner 9 is circular. Distance x ₄ is 0.15 m, so and _{(0.1z 3 + d 2/2} ) is a 0.19 m, does not satisfy the equation (8). Since (Δt / t _r ) is 0.19 and exceeds 0.18, the temperature deviation is large and the temperature variation of the molten steel 14 is not suppressed.
Referring to Nos. 9 and 9 (Comparative Example) in Tables 11 to 13, the cross-sectional shape of the runner 9 is circular. The horizontal angle θ ₁ is 70 [deg.] And does not satisfy Expression (4). Since the distance x ₂ is 0.35 m and (0.1 (z ₁ + z ₃ ) + (d ₂ + D ₂ ) / 2) is 0.39 m, Expression (7) is not satisfied. Since (Δt / t _r ) is 0.23 and exceeds 0.18, the temperature deviation is large and the temperature variation of the molten steel 14 is not suppressed.

As described above, according to the present invention, in the T-shaped tundish 1 having a pouring chamber 4 and a strand chamber 5 having a plurality of strands 6, the difference in arrival time of the molten steel 14 flowing in each strand 6 is controlled. By doing so, it is possible to suppress variations in molten steel temperature between the strands 6 in the tundish 1.
Further, according to the present invention, the nozzle clogging of the immersion nozzle 13 in the low ΔT side strand 6 can be suppressed, and the breakout in the high ΔT side strand 6 can be suppressed.

The continuous casting tundish 1 of the present invention described above can be applied to a continuous casting method using the continuous casting apparatus 15 as shown in FIG.
As shown in FIG. 23, the continuous casting apparatus 15 is an apparatus for continuously casting the molten steel 14 after the secondary refining process, for example, the tundish 1 into which the molten steel 14 in the ladle 16 is poured, A mold 17 for casting the molten steel 14 in the tundish 1 and a support roll 18 for supporting a cast piece 19 formed by the mold 17 are provided. In addition, the shape of the slab 19 cast by the continuous casting apparatus 15 is not limited, and may be a slab, a bloom, a billet, or the like.

  It should be noted that matters not explicitly disclosed in the embodiment disclosed this time, such as operating conditions and operating conditions, various parameters, dimensions, weights, volumes, and the like of a component, deviate from the range normally practiced by those skilled in the art. However, matters that can be easily assumed by those skilled in the art are employed.

1 Tundish 2a Bottom (infusion chamber)
2b Bottom (Strand chamber)
3 peripheral wall 4 injection chamber 5 strand chamber 6 mold injection hole (strand)
7 Front side wall (front wall)
8 Divider weir 9 Runway 9a First runway (first weir hole)
9b Second runway (second weir hole)
9c Third runway (first bottom dam)
9d Fourth runway (second bottom weir)
10a 1st runner exit 10b 2nd runner exit 10c 3rd runway exit 10d 4th runner exit 11 Protrusion (step)
13 Immersion nozzle 14 Molten steel 15 Continuous casting device 16 Ladle 17 Mold 18 Support roll 19 Slab 20 Oxygen pipe

Claims (3)

A plurality of casting chambers into which molten steel from a ladle is poured, and a plurality of casting holes that are in front of the casting chamber, are elongated in the left-right direction from the casting chamber, and in which the molten steel is charged into the mold at the bottom. In a tundish comprising a strand chamber having a partition weir that partitions the injection chamber and the strand chamber, and a runner that is provided in the partition weir and linearly penetrates from the injection chamber to the strand chamber,
The runner is shifted to the left in the horizontal direction in plan view, and in the side view, from the bottom side of the injection chamber, from the inner wall surface of the partition weir to the upper side of the strand chamber, toward the inner wall surface of the partition weir A first runway penetrating in a straight line;
Shifted to the right side in the horizontal direction in a plan view, and penetrated in a straight line from the bottom side of the injection chamber, from the inner wall surface of the partition weir to the upper side of the strand chamber, and to the inner wall surface of the partition weir in a side view And a second runway
Furthermore, the runner is between the first runner and the second runner, and is shifted horizontally or downward from the injection chamber toward the strand chamber in a side view, and in plan view. And a third runway that runs straight in the front-rear direction,
A fourth that is disposed adjacent to the third runner and moves horizontally or downward from the injection chamber toward the strand chamber in a side view, and linearly penetrates in a front-rear direction in a plan view; And have a runway,
One of the plurality of mold injection holes includes a point where an extension line of a central axis that faces the horizontal direction of the third runner intersects the front side wall surface, and a center that faces the horizontal direction of the fourth runner An extension line of the shaft is provided in a region between two points with a point intersecting the front side wall surface;
The other mold pouring holes are in the left-right direction from the extension line of the central axis facing the horizontal direction of the first runner facing upward and the extension line of the central axis facing the horizontal direction of the second runway facing upward Located in the outer area,
The bottom of the strand chamber connected to the outlet of the third runner and the outlet of the fourth runner is located below the lower end of the outlet of the third runner and the outlet of the fourth runner, and the formula ( 1) -tundish for continuous casting characterized by satisfying formula (8).
d ₁ ≦ 0.3 [m] (1)
D ₁ ≦ 0.3 [m] (2)
_{x 1 ≧ 0.1z 1 + D 2} /2 [m] ··· (3)
θ ₁ ≦ 60 [deg.] (4)
z ₂ tanθ ₂ -0.1z ₁ / cosθ ₂ ≧ H / 3 [m] (5)
z ₂ tanθ ₂ + D ₁ + 0.1z ₁ / cosθ ₂ ≦ H [m] (6)
x ₂ ≧ 0.1 (z ₁ + z ₃ ) + (d ₂ + D ₂ ) / 2 [m] (7)
_{x 4 ≧ 0.1z 3 + d 2} /2 [m] ··· (8)
d ₁ : Length of the third and fourth runners
d ₂ : Horizontal diameter of the third and fourth runners
D ₁ : Length of the first runway and the second runway
D ₂ : Horizontal diameter of the first runway and the second runway
x ₁ : The point where the extension of the central axis of the first runway and the second runway facing upward intersects with the front wall surface of the strand chamber, and the vertical direction of the mold injection hole on the nearest side to the partition weir Distance from the point where the horizontal extension line passing through the central axis intersects the front wall surface of the strand chamber
θ ₁ : Extension of the central axis of the first runner and the second runner facing upward The horizontal angle on the center side in the width direction of the strand chamber at the point intersecting the front wall surface of the strand chamber
θ ₂ : upward angle of the first runway and the second runway facing upward
z ₁ : The horizontal length of the strand chamber on the extension line of the axial center of the first runner and the second runner facing upward
z ₂ : Horizontal distance from the front end of the injection chamber to the front side wall surface of the strand chamber in the axial center of the first runner and the second runner facing upward
z ₃ : Horizontal length of the strand chamber on the extension line of the axis of the third or fourth runway that faces horizontally or downward
H: Depth of molten steel
x ₂ : The extension line of the central axis of the first runway or the second runway intersects the front side wall surface of the strand chamber, and the extension line of the central axis of the third runway or the fourth runway is the front side of the strand chamber Distance between wall and intersection
x ₄ : The point where the extension line of the center axis of the third runway or the fourth runway intersects the front side wall surface of the strand chamber and the center facing the vertical direction of the mold injection hole located in the region between the two points Distance from the point where the horizontal extension line passing through the axis intersects the front wall surface of the strand chamber The strand chamber is provided in front of the injection chamber, abutting against the front side wall surface of the strand chamber, and provided with a protrusion standing upward from the bottom of the strand chamber,
2. The tundish for continuous casting according to claim 1, wherein the protrusions are provided in a pair on the left and right sides at a predetermined interval and satisfy Expressions (9) to (12).
y ≧ 0.1 [m] (9)
L ≧ 0.2 [m] (10)
_{d 1 + 0.1z 1 ≦ h ≦} z 2 tanθ 2 -0.1z 1 / cosθ 2 [m] ··· (11)
_{x 3 ≧ 0.1z 3 + d 2} /2 [m] ··· (12)
y: Length of the protrusion in the front-rear direction
L: Width of protrusion
h: Height of protrusion
x ₃ : The point where the extension line of the central axis of the third or fourth runway intersects the front side wall surface of the strand chamber, and the extension line side of the central axis of the third or fourth runway in the projection. Distance to end   A continuous casting method, wherein continuous casting is performed using the continuous casting tundish according to claim 1.