JP6668567B2 - Tundish for continuous casting and continuous casting method using the tundish - Google Patents

Description

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

Conventionally, in continuous casting equipment, molten steel output from a converter or secondary refining equipment is transported by a ladle to a tundish, and the molten steel in the transported ladle is poured into the tundish. The molten steel is continuously cast by supplying the molten steel to the mold from.
In order to operate the continuous casting efficiently, it is necessary to equalize the temperature of the molten steel between the strands when smoothly flowing the molten steel from the pouring chamber to the strand chamber in the tundish.

As means for making the temperature of the molten steel in the tundish uniform, there are those disclosed in Patent Documents 1 to 3.
Patent Literature 1 aims to reduce variation in molten steel temperature between strands in a multi-strand tundish. Specifically, in a T-type tundish in which an injection chamber and a strand chamber are separated by a weir, two holes (runners) are opened in the weir, and the direction of the holes is directed between predetermined strands. Thus, variations in the temperature of the molten steel between the strands are reduced.

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

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

In addition, in order to efficiently operate continuous casting, it is necessary to prevent inclusions in the tundish from flowing out to the mold.
Means for preventing such inclusions from flowing out of the tundish are disclosed in Patent Documents 4 to 6.
Patent Document 4 aims to prevent large inclusions in a tundish from flowing out to a mold when distributing molten steel. Specifically, in a tundish in which an injection chamber and a strand chamber are separated 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 directly flows into the mold injection hole and in which the direct flow of the molten steel to the mold injection hole is likely to occur is removed. By setting the orientation of the 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 in which a low weir is installed at the bottom between the casting position from the molten steel pot and the mold pouring chamber, the weir has one hole facing the mold pouring chamber (the molten steel channel). Is open. A collision member having an inclined surface rising from the bottom toward the mold injection chamber is installed in front of the weir hole so that the flow from the molten steel pot does not directly flow into the weir hole. Flow to the upper part of the tundish to promote 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, on the inner wall side between the casting position from the molten steel pot and the mold pouring chamber, an inclined portion having a surface rising from the bottom toward the mold pouring chamber side is provided, and the molten steel is inclined to the inclined portion. By following, the upflow of molten steel is promoted.

JP 2014-113634 A JP-A-6-142855 Japanese Utility Model Publication No. 3-106243 JP 2005-131661 A JP 2003-245775 A JP 2008-254028 A

In Patent Literature 1, since the direction of the weir hole (runner) is directed between the predetermined strands, the molten steel can be smoothly circulated, and the variation in the temperature of the molten steel between the strands is reduced.
However, in this document, since it is specified only that the direction of the weir hole should be such that the molten steel flows between the predetermined strands, it is very rare, but depending on the conditions of actual operation, It is conceivable that molten steel flows directly into the mold injection hole. Therefore, it is conceivable that the molten steel temperature will vary, although it is unlikely.

On the other hand, Patent Literature 2 discloses that the target position of the molten steel flow in the strand chamber is not clearly defined such that the molten steel flows smoothly in the strand chamber. Therefore, depending on the conditions of actual operation, the molten steel flows into the mold injection hole. There is a possibility that the direct flow of the air may occur.
Therefore, there is a great possibility that the variation in the molten steel temperature will increase. For example, even if a plasma heating device is used, there is a possibility that the variation of the molten steel temperature between the strands will increase unless the direction of the molten steel flow is optimized.

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

Further, 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 or a direct flow of the molten steel occurs. Therefore, there is a possibility that the variation of the molten steel temperature between the strands becomes large.
In the above technique, in a multi-strand tundish, molten steel that has flowed out of the injection chamber to the strand chamber, including the direct flow, flows preferentially into the mold injection hole (strand) close to the injection chamber, and is close to the injection chamber. In the casting hole, the temperature of the molten steel increases. On the other hand, in the mold injection hole far from the injection chamber, molten steel having a lowered temperature flows. That is, there is a possibility that the variation in the temperature of the molten steel in the multi-strand tundish becomes large.

Further, in the mold injection hole far from the injection chamber, the molten steel having a low temperature flowing therein solidifies, so that the inner diameter of the mold injection hole becomes narrower, which may cause nozzle clogging.
By the way, Patent Document 4 prevents direct flow of molten steel to the mold injection hole, however, depending on the conditions of the actual operation, there is a possibility that the variation of the molten steel temperature between the strands becomes large. Also, in the technology of the same document, since the jet from the weir hole does not exceed the mold injection hole near the weir, especially when applied to a tundish with four or more strands, the variation of the molten steel temperature in the tundish is reduced. It is impossible to make it happen.

Patent Literatures 5 and 6 prevent direct flow of molten steel into a mold injection hole, but are techniques applicable to a tundish in which one strand injection hole is provided in each strand chamber. It is considered that when applied to a multi-strand tundish, the variation in molten steel temperature cannot always be reduced.
In view of the above problems, the present invention provides a T-shaped tundish having a pouring chamber and a plurality of mold pouring holes in a T-shaped dish in plan view, the difference in arrival time of molten steel flowing through each mold pouring hole. The object of the present invention is to provide a continuous casting tundish capable of suppressing the variation of the molten steel temperature between the strands in the tundish by controlling the tundish, and a continuous casting method using the tundish. .

In order to achieve the above object, the following technical measures have been taken in the present invention.
The tundish for continuous casting according to the present invention has an injection chamber into which molten steel from a ladle is injected, and a front side of the injection chamber, which is longer in the left-right direction than the injection chamber, and has a molten steel at a bottom portion. A strand chamber having a plurality of mold injection holes for charging the mold into a mold, a partition weir for partitioning the injection chamber and the strand chamber, and a linear weir provided in the partition weir and linearly penetrating from the injection chamber to the strand chamber. And a runner, wherein the runner shifts obliquely leftward in the horizontal direction in plan view, and the bottom side of the injection chamber and the upper side of the strand chamber from the inner wall surface of the partition weir in side view. A first runner that penetrates in a straight line toward the inner wall surface of the partition weir, and shifts diagonally in the horizontal direction to the right in plan view, and at the bottom side of the injection chamber in the side view, inside the partition weir Upper side of the strand chamber from the wall A second runner that penetrates in a straight line toward the inner wall surface of the partition weir, and the runner is between the first runner and the second runner; A third runner that transitions horizontally or downward from the injection chamber toward the strand chamber in a side view, and penetrates linearly in a front-rear direction in a plan view, wherein the first runner is The second runner is provided on the left side of the third runner in plan view, and the second runner is provided on the right side of the third runner in plan view, and the mold injection hole faces upward. An extension of a central axis of the first runner in the horizontal direction and an extension of the central axis of the second runner in the horizontal direction facing upward, located in a region laterally outward of the extension of the central axis in the horizontal direction; The bottom of the strand chamber connected to the outlet of the third runner is located below the lower end of the outlet of the third runner, and satisfies Expressions (1) to (7). And wherein the are.

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 / cos θ ₂ ≧ H / 3 [m] (5)
z ₂ tan θ ₂ + D ₁ + 0.1z ₁ / cos θ ₂ ≦ H [m] (6)
x ₂ ≧ 0.1 (z ₁ + z ₃ ) + (d ₂ + D ₂ ) / 2 [m] (7)
d ₁ : vertical diameter of the third runner
d ₂ : lateral diameter of the third runner
D ₁ : Vertical diameter of the first runner and the second runner
D ₂ : lateral diameter of the first runner and the second runner
x ₁ : The point where the extension line of the central axis of the first runner and the second runner that faces upward intersects the front wall surface of the strand chamber, and the vertical direction of the mold injection hole closest to the partition weir. Distance between the point where the horizontal extension line passing through the central axis intersects the front wall surface of the strand chamber
θ ₁ : Horizontal angle at the center side in the strand chamber width direction at the point where the extension line of the central axis of the first and second runners facing upward intersects the front wall surface of the strand chamber.
θ ₂ : upward angle of the first runner and the second runner facing upward
z ₁ : Horizontal length of the strand chamber on the extension of the axis 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 wall surface of the strand chamber at the axis of the first runner and the second runner facing upward.
z ₃ : Horizontal length of the strand chamber on the extension of the axis of the third runner that is horizontal or downward
H: Depth of molten steel
x ₂ : the point where the extension of the central axis of the first or second runner intersects with the front wall surface of the strand chamber and the point where the extension of the central axis of the third runner intersects with the front wall of the strand chamber. Preferably, in the strand chamber, a protrusion that is in front of the injection chamber, abuts against the front wall surface of the strand chamber, and stands upward from the bottom of the strand chamber. It is preferable that a pair of right and left protrusions are provided at a predetermined interval and that the expressions (8) to (11) are satisfied.

y ≧ 0.1 [m] (8)
L ≧ 0.2 [m] ・ ・ ・ (9)
d ₁ + 0.1z ₁ ≦ h ≦ z ₂ tan θ ₂ -0.1z ₁ / cos θ ₂ [m] (10)
_{x 3 ≧ 0.1z 3 + d 2} /2 [m] ··· (11)
y: Length of the protrusion in the front-rear direction
L: Width of protrusion
h: Height of protrusion
x ₃ : distance between the point where the extension of the central axis of the third runner intersects the front wall surface of the strand chamber and the end of the projection on the extension side of the central axis of the third runner The casting method is characterized in that continuous casting is performed using the tundish for continuous casting.

  According to the present invention, in a T-shaped tundish having a pouring chamber and a strand chamber having a plurality of mold pouring holes in a T-shape in plan view, by controlling a difference in arrival time of molten steel flowing in each mold pouring hole, It is possible to suppress the variation of the 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 the side sectional view which expanded a part of tundish of the present invention. Fig. 1 is a first diagram showing a shape of a bottom portion of a strand chamber. It is the 2nd figure which shows the shape of the bottom of the strand room. It is the 3rd which shows the shape of the bottom of the strand room. It is a figure showing the shape of the runner formed in the tundish of the present invention. It is the figure which showed the maintenance situation of the tundish in case the penetration shape of the runner of a partition weir is made into a straight line. It is the figure which showed the maintenance condition of the tundish in the case of making it into the penetration shape bent in the middle of the runway of the 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). Is a plan view showing an example of a horizontal angle of the first runner and a second runner according to the present invention (θ ₁ ≦ 60). It is a top view which shows an example outside the defined range in the horizontal angle of a 1st runner and a 2nd runner ((theta) ₁ > 60). It is a side sectional view showing an example of a 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 an example of a 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). 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 + D 1} + 0.1z 1 / cosθ 2> H). Is a plan view showing an example of a shape of the first runner and a second runner to the present invention _{(x 2 ≧ 0.1 (z 1} + z 3) + (d 2 + 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 2 <0.1 (z 1} + z 3) + (d 2 + 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 a strand chamber. It is the figure which expanded a part of tundish of the present invention, and is a side sectional view showing the shape of the projection provided in the bottom of the strand room. 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 of the shape of a protrusion outside the prescribed range (y <0.1). It is a top view showing another example of the shape of the projection concerning the present invention. It 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). FIG. 4 is a side cross-sectional view showing an example of a shape of a protrusion outside a specified range (h> z ₂ tan θ ₂ -0.1z ₁ / cos θ ₂ ). It 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} ). FIG. 4 is a side cross-sectional view showing an example of a shape of a protrusion outside a specified range (d ₁ + 0.1z ₁ > h). It is a side sectional view showing another example of shape of a projection concerning the present 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 performing the water model experiment. It is a figure which shows the tundish of the shape A used at the time of performing numerical calculation. It is a figure showing the tundish of shape B used at the time of performing numerical calculation. It is a figure which shows the tundish of the shape C used at the time of performing a numerical calculation. It is a figure showing the tundish of shape D used at the time of performing numerical calculation. 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. 22, the tundish 1 for continuous casting rises from the bottoms 2a, 2b provided with the mold injection holes 6 (strands) for charging the molten steel 14 into the mold 17, and the periphery of the bottoms 2a, 2b. And a peripheral wall 3. Hereinafter, it may be simply referred to as tundish 1.

  The tundish 1 also has a plurality of injection chambers 4 into which a molten steel 14 in a ladle 16 is injected, and a plurality of strands 6 in front of the injection chamber 4 and at the bottom 2b for charging the molten steel 14 into a mold 17. And, it has a strand chamber 5 for casting the molten steel 14 into the mold 17 via the strand 6, and a partition weir 8 for partitioning the injection chamber 4 and the strand chamber 5; It is long in the direction.

That is, an 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 the strands 6 is four or more even numbers.
The injection chamber 4 has a bottom 2 a where no strand 6 is provided, three peripheral walls 3 erected upward from each of three peripheral edges of the bottom 2 a, and a partition for dividing the strand chamber 5 so as to be divided. It is composed of a portion surrounded by a weir 8. On the other hand, the strand chamber 5 includes a bottom portion 2b provided with a plurality of strands 6, a peripheral wall 3 erected upward from each peripheral edge of the bottom portion 2b, and a partition weir 8 for partitioning the strand chamber 5 from the injection chamber 4. It consists of the part enclosed by and.

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

First, the outline of the runner 9 (dam hole) provided in the tundish 1 of the present invention will be described with reference to FIGS. 2A, 2B, 3A, and 3B. The specification of the shape and dimensions of the runner 9 and the projection 11 shown in FIGS. 2A and 2B, that is, the characteristic configuration of the tundish 1 of the present invention will be described later in detail.
As shown in FIGS. 2A, 2B, 3A, and 3B, a partition weir 8 that separates the injection chamber 4 from 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 moves obliquely leftward in the horizontal direction from the injection chamber 4 toward the strand chamber 5 in plan view, and the bottom 2a side of the injection chamber 4 and the lower end of the inner wall surface of the partition weir 8 (partition) in side view. A straight runner 9a (first runner) penetrating linearly from the lower end of the rear wall of the weir 8 to the upper side of the strand chamber 5 and to the inner wall surface of the partition weir 8 (front wall of the partition weir 8); As viewed from the injection chamber 4 toward the strand chamber 5, it shifts obliquely rightward in the horizontal direction, and when viewed from the side, the bottom 2 a side of the injection chamber 4, the lower end of the inner wall surface of the partition weir 8, the upper side of the strand chamber 5, There is a runner 9b (second runner) penetrating linearly toward the inner wall surface of the partition weir 8.

Further, the runner 9 is located between the first runner 9a and the second runner 9b, moves horizontally or downward from the injection chamber 4 toward the strand chamber 5 in a side view, and is flat. It has a 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 in the front-rear direction as viewed.
Here, when viewing the bottom 2b which is the bottom 2b of the strand chamber 5 and is connected to the outlet 10c of the third runner 9c, the inner surface of the bottom 2b is located below the lower end of the outlet 10c of the third runner 9c. are doing.

That is, in the present invention, the bottom 2b of the strand chamber 5 connected to the outlet 10c of the third runner 9c is the same height as the lowermost end of the outlet 10c of the third runner 9c (see FIG. 3A), or It is a position lower than the lowermost end of the outlet 10c of the third runner 9c (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 third runner 9c is formed in the partition weir 8, and when the bottom 2b connected to the outlet of the runner 9 is viewed, the bottom 2b is the lower end of the outlet of the third runner 9c. The tundish when it is positioned higher than that is shown.
However, in the present invention, the tundish having the structure shown in FIG. 3C is out of scope. In other words, the present invention does not cover the case where the bottom 2b of the strand chamber 5 is higher than the lowermost end of the outlet of the third runner 9c.

FIG. 4 is a cross-sectional view when the partitioning weir 8 is cross-sectioned in the width direction and perpendicularly (cross-section BB in FIG. 1). As shown in FIG. 4, the shape of the runner 9 (first runner 9 a to third runner 9 c) formed in the partitioning weir 8 in a sectional view is circular, elliptical, or square. Or 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 the oxygen causes the tundish 9 to flow into the runner 9 (weir hole). The ingots are melted to remove the ingots.

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 can be removed without melting the partitioning weir 8. Can be.
However, as shown in FIG. 5B, if the runner 9 connecting the injection chamber 4 and the strand chamber 5 has a penetrating shape that is bent in the middle, there is a possibility that the partition weir 8 may be melted depending on the maintenance situation. .

Therefore, the runner 9 (the first runner 9a to the third runner 9c) needs to linearly penetrate the partition weir 8 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.
Hereinafter, the front-back direction of the strand chamber 5 is defined as a depth direction, and the left-right direction of the strand chamber 5 is defined as a width direction. This coincides with the front-back direction and the left-right direction of the tundish 1.

The first runner 9a is called a first dam, and the second runner 9b is called a second dam. The third runner 9c is referred to as a bottom dam hole.
2A and 2B, the strand 6 provided in the tundish 1 of the present invention is located in a region outside the leftward direction from an extension of the horizontal center axis of the first dam 9a in a plan view. positioned. In addition, the strand 6 is located in a region on the right side outside the extension of the center axis of the second dam hole 9b in the horizontal direction.

That is, the strands 6 are provided at the bottom 2b of the strand chamber 5 and outside the extension of the center axis of the first dam 9a and the extension of the center axis of the second dam 9b.
As shown in FIG. 4, “d ₁ ” is an inner diameter (vertical diameter) in a vertical (vertical) direction when the bottom dam 9 c is vertically sectioned.
The vertical diameter “d ₁ ” of the bottom dam 9 c is 0.3 m or less as shown in Expression (1).

d ₁ ≦ 0.3 [m] ・ ・ ・ (1)
However, when the vertical diameter d ₁ of the bottom dam 9 c exceeds 0.3 m, most of the sand and the like dropped from the nozzle of the ladle 16 when the nozzle is opened flows into the strand chamber 5 through the bottom dam 9 c. Easier to do. If a large amount of sand at the time of opening the ladle 16 enters the strand chamber 5 via the bottom dam 9c, inclusion defects are likely to occur.

As described above, the longitudinal diameter d ₁ of the bottom Sekiana 9c by below 0.3 m, it is possible to float the sand in strand chamber 5 without injection chamber 4 side.
“D ₂ ” is a horizontal inner diameter (lateral diameter) when the bottom dam 9 c is vertically sectioned.
Further, as shown in FIG. 4, “D ₁ ” is an inner diameter (vertical diameter) in the vertical (up-down) direction when the first dam 9a and the second dam 9b are vertically cross-sectioned.

The vertical diameter “D ₁ ” of each of the first dam 9 a and the second dam 9 b is 0.3 m or less as shown in Expression (2).
D ₁ ≦ 0.3 [m] ・ ・ ・ (2)
However, the first Sekiana 9a and second Sekiana if vertical diameter D ₁ of the 9b exceeds 0.3 m, most of the sand dropped from the nozzle at the opening of the nozzle of the ladle 16 each weir holes 9a, It easily flows into the strand chamber 5 through 9b. If a large amount of sand at the time of opening the ladle 16 enters the strand chamber 5 through the weir holes 9a and 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 FIGS. 2A and 6A, “x ₁ ” indicates that the central axes of the first and second dam holes 9 a and 9 b in plan view are equal to the front wall surface 7 (front wall) of the strand chamber 5 facing the same. The intersection point and the straight line in the front-rear direction passing through the center of the strand 6 closest to the partitioning weir 8 (the above-described laterally outer region) is the distance between the intersection point with the front wall 7 of the strand chamber 5.

That is, the distance "x _1" is the distance between the intersection _{a 1} and the intersection point _{a 2,} or is the distance between the intersection _{a 3} and the intersection _{a 4.}
This distance “x ₁ ” satisfies Expression (3).
_{x 1 ≧ 0.1z 1 + D 2} /2 [m] ··· (3)
However, “z ₁ ” is a horizontal distance from the outlet of each of the weir holes 9 a and 9 b to the front wall 7 of the strand chamber 5 on an extension of the central axis (axis) of the first and second weir holes 9 a and 9 b. The distance (the length of the strand chamber 5).

“D ₂ ” is an inner diameter (lateral diameter) in the left-right direction when the horizontal diameter of the first dam 9 a and the second dam 9 b is vertically cross-sectioned (see FIG. 4).
Expression (3) is an expression representing the relationship between the jet (upward jet) flowing out from the outlet of each of the weir holes 9a and 9b and the position of the strand 6 closest to the partition weir 8. "0.1z" is a theoretical expression of the spread 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, the upward jet flowing out from the outlet of 9b, the strands The distance between the location where the front wall 7 of the chamber 5 collides with the strand 6 near the partitioning weir 8 becomes too short. That is, the distance of an intersection _{a 1} and the intersection point _{a 2} (intersection _{a 3} and the intersection point _{a 4)} is shortened.
With such a positional relationship, the upward jet that has flowed out and spread is deviated 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 FIG. 2A and FIG. 7A, “θ ₁ ” is an extension of the central axis of the first dam 9 a and the second dam 9 b facing upward in plan view, and the front wall 7 of the strand chamber 5. And the angle in the horizontal direction (horizontal angle), which expresses the angle on the center side in the width direction of the strand chamber 5.
That is, Expression (4) is an expression representing the horizontal angle at which the upward jet flowing from the outlets of the 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 theta ₁ is greater than 60 [deg.], Upwards jet collides with the front wall 7 is less likely spread outward in the left-right direction. As a result, a temperature difference of the molten steel 14 is likely to occur between the strand 6 near (the nearest side to) the partition weir 8 and the strand 6 far from the partition weir 8.

As shown in FIG. 2B and FIG. 8A, an upward flow which flows out from an outlet 10a of a first dam 9a and an outlet 10b of a second dam 9b provided on both outer sides of the partition weir 8 in a side sectional view. The lower end position when the jet collides with the front wall 7 of the strand chamber 5 (the lower end height of the upward jet as viewed from the bottom 2b) satisfies Expression (5).
z ₂ tanθ ₂ -0.1z ₁ / cos θ ₂ ≧ H / 3 [m] (5)
Here, “θ ₂ ” is the angle inside the vertical direction at the point where the extension line of the central axis of each of the weir holes 9 a and 9 b 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 axis of each of the dam holes 9a and 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 at the axis of each of the dam 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-mentioned specification (z ₂ tan θ ₂ -0.1z ₁ / cos θ ₂ <H / 3), the upward jet colliding with the front wall 7 does not become an upward flow, Direct flow to the strand 6 near the weir 8 is likely to occur. As a result, the temperature deviation between the strand 6 near the partition weir 8 and the strand 6 far from the partition weir 8 increases.
As shown in FIG. 2B and FIG. 9A, an upward flow flowing out of an outlet 10 a of a first dam 9 a and an outlet 10 b of a second dam 9 b 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 tan θ ₂ + D ₁ + 0.1z ₁ / cos θ ₂ ≦ H [m] (6)
However, as shown in FIG. 9B, when the above-mentioned specification is exceeded (z ₂ tan θ ₂ + D ₁ +0.1 z ₁ / cos θ ₂ > H), the upward jet flows onto the molten steel surface before colliding with the front wall 7. It reaches and a downflow occurs. As a result, a direct flow to the strand 6 near each of the weir holes 9a and 9b is likely to occur.

As shown in FIGS. 2A and 10A, “x ₂ ” is an upward jet flowing out of the outlet 10 a of the first dam 9 a or the outlet 10 b of the second dam 9 b facing upward in plan view. Is the distance between the position at which the bottom jet collides with the front wall 7 and the position at which the bottom jet flowing out from the outlet 10c of the bottom dam 9c collides with the front wall 7.
In other words, the distance “x ₂ ” is determined by the point at which the extension of the central axis of the first dam 9 a or the second dam 9 b intersects the front wall 7 of the strand chamber 5 and the center axis of the bottom dam 9 c. Is the distance between the point of intersection with the front wall 7 of the strand chamber 5.

That is, the distance "x _2" is the intersection _{a 1} or intersection _{a 3,} a distance between the intersection _{a 5.}
This distance “x ₂ ” satisfies Expression (7).
x ₂ ≧ 0.1 (z ₁ + z ₃ ) + (d ₂ + D ₂ ) / 2 [m] (7)
Here, “z ₃ ” is the length in the front-rear direction of the strand chamber 5 on the central axis of the bottom dam 9 c. That is, “z ₃ ” is the horizontal length of the strand chamber on the extension of the axis of the bottom dam 9 c which is horizontal or downward.

However, as shown in FIG. 10B, when the value is lower than the above-mentioned specification (x ₂ <0.1 (z ₁ + z ₃ ) + (d ₂ + D ₂ ) / 2), the outlet 10 a of the first dam hole 9 a or the second The upward jet flowing out of the outlet 10b of the weir 9b and the bottom jet flowing out of the outlet 10c of the bottom weir 9c interfere with each other, and it becomes difficult for the bottom jet to become an upward flow. As a result, a direct flow to the strand 6 near each of the weir holes 9a and 9b is likely to occur.

As shown in FIGS. 11A and 11B, in the tundish 1 of the present invention, the front wall 7 is provided on the front inner wall surface (front wall 7) of the strand chamber 5 in front of the injection chamber 4. There is provided a projection 11 (step portion) which is in contact with and stands upright from the 5 bottom portion 2b of the strand chamber.
The protrusions 11 are provided in a pair at right and left at a predetermined interval, and have a substantially rectangular shape in a side sectional view.

As shown in FIGS. 11A and 12A, “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 (8).
y ≧ 0.1 [m] (8)
The space sandwiched by the pair of left and right projections 11, that is, the concave portion in plan view, converts the flow of the bottom jet flowing out of the outlet 10c of the bottom dam 9c (the thick arrow in FIG. 12A) into an upward flow. Plays the role of guide.

However, as shown in FIG. 12B, 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, a space (recess) sandwiched between the pair of left and right projections 11 is provided. Is reduced, and the role of the guide for making the bottom jet flowing out from the outlet 10c of the bottom dam hole 9c an upward flow is weakened. That is, it becomes difficult for the bottom jet to become an upward flow.
As shown in FIGS. 11A and 12A, “L” is the length of the protrusion 11 in the left-right direction in plan view. That is, “L” is the width of the projection 11.

This width “L” satisfies Expression (9).
L ≧ 0.2 [m] ・ ・ ・ (9)
However, when the width L of the projection 11 is less than 0.2 m, the durability of the projection 11 is reduced, and the molten steel flow tends to cause erosion and breakage.
The shape of the protrusion 11 in a horizontal sectional view (plan view) may be a rectangular shape as shown in FIGS. 11A and 12A, or an arc shape as shown in FIG.

As shown in FIG. 11B, FIG. 14A, and FIG. 15A, “h” is the height of the protrusion 11 in a side sectional view.
As shown in FIG. 15A, the height “h” satisfies (d ₁ + 0.1z ₁ ≦ h). Also, as shown in FIG. 14A, the height “h” satisfies (h ≦ z ₂ tan θ ₂ −0.1z ₁ / cos θ ₂ ).
That is, the height “h” satisfies Expression (10).

d ₁ + 0.1z ₁ ≦ h ≦ z ₂ tan θ ₂ -0.1z ₁ / cos θ ₂ [m] (10)
However, as shown in FIG. 14B, when the height h of the protrusion 11 exceeds the above-mentioned specification (h> z ₂ tan θ ₂ -0.1z ₁ / cos θ ₂ ), each of the dam holes 9a and 9b facing upward. The upper ends of the protrusions 11 are higher than the lower ends of the upward jets flowing out of the outlets 10a and 10b, thereby obstructing the upward jets from the weir holes 9a and 9b.

As a result, the upward jet colliding with the front wall 7 has a weaker flow spreading outward in the strand chamber 5 (the tundish 1), and a direct flow to the strand 6 near each of the weir holes 9a and 9b tends to occur. Become.
Further, as shown in FIG. 15B, when the height h of the protrusion 11 is smaller than the above-mentioned specification (d ₁ + 0.1z ₁ > h), the upper end of the bottom jet flowing out from the outlet 10c of the bottom dam 9c is formed. Accordingly, the upper end of the projection 11 becomes lower, and the role of the guide for making the bottom jet from the bottom dam 9c an upward flow is weakened. That is, it becomes difficult for the bottom jet to become an upward flow.

In addition, as shown in FIG. 16, the shape of the protrusion 11 in a vertical sectional view (side sectional view) may be substantially rectangular, and the corner may be chamfered (rounded).
As shown in FIGS. 11A and 17A, “x ₃ ” is the distance between the point where the extension of the central axis of the bottom dam 9 c intersects the front wall 7 and one end of the protrusion 11. .
Specifically, the point where the extension line of the central axis of the bottom dam hole 9c intersects the front wall 7 and the right end portion of the protrusion 11 provided on the left side in plan view (the end portion of the bottom dam hole 9c side). ) Or the distance from the left end (the end on the side of the bottom dam 9c) of the protrusion 11 provided on the right side in plan view.

That is, “x ₃ ” indicates the position at which the bottom jet flowing from the outlet 10 c of the bottom dam 9 c collides with the front wall 7 of the strand chamber 5, and the left and right ends of the protrusion 11 on the bottom dam 9 c side. Is the distance.
This distance “x ₃ ” satisfies Expression (11).
_{x 3 ≧ 0.1z 3 + d 2} /2 [m] ··· (11)
However, as shown in FIG. 17B, the distance x ₃ falls below a defined above _{(x 3 <0.1z 3 + d} 2/2) case, the bottom jet flowing out of the bottom Sekiana 9c than spread, a pair of left and right Since the space between the protrusions 11 is narrow, the role as a guide for changing the bottom jet into an upward flow is weakened.

As shown in FIG. 11A, “x ₅ ” indicates the point at which a straight line passing in the front-rear direction passing through the center of the strand 6 closest to the partition weir 8 intersects the front wall 7 and the right-left direction of the projection 11. This is the distance from the other end (the side farther than the bottom dam 9c).
If the temperature of the molten steel 14 injected into the mold 17 is too high, the solidified shell may break below the mold 17 and a breakout may occur in which unsolidified molten steel leaks downward.

  When a breakout occurs, the leaked metal adheres to the roll stand of the continuous casting apparatus 15, and an operation for removing the metal occurs. If it is difficult to remove the bullion, it is necessary to replace the roll stand. When such a problem that extra work is required occurs, a large recovery cost of the continuous casting apparatus 15 is required, and the production of the cast slab 19 is greatly affected.

Therefore, in order to suppress the above-mentioned breakout, 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 into each mold 17. Therefore, in order to prevent breakout, the temperature of the molten steel in the tundish 1 is controlled based on the high temperature side of the temperature deviation of the molten steel 14.

For example, if the deviation of the temperature of the molten steel flowing out of each strand 6 installed at the bottom 2 b of the strand chamber 5 is large, the molten steel is immersed in the immersion nozzle 13 installed below the strand 6 on the lower temperature side of the temperature deviation of the molten steel 14. 14 may be coagulated to cause nozzle clogging.
As described above, in the strand 6 in which the nozzle clogging has occurred, the continuous casting must be stopped, which greatly affects the production of the slab 19.

As described above, it is necessary to reduce the temperature deviation of the molten steel 14, that is, to control the temperature of the molten steel in the tundish 1.
FIG. 18 is a diagram showing the measurement position of the molten steel temperature in the tundish 1. As shown in FIG. 18, in the present embodiment, the temperature of the molten steel was measured almost directly above the strand 6 and at a depth of 0.3 m from the molten metal surface of the molten steel 14.

  Table 1 shows the relationship between the measured deviation of the molten steel temperature in the tundish 1 and the nozzle clogging in the immersion nozzle 13 caused by the effect of the molten steel 14 having a lowered temperature.

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 whose temperature has decreased It can be confirmed that nozzle clogging due to the influence of No. 14 does not occur.
By using the tundish 1 of the present invention described above, the temperature deviation of the molten steel 14 can be reduced, that is, the variation of the molten steel temperature between the strands 6 in the multi-strand tundish can be suppressed, so that 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 due to the strand 6 into which the high temperature molten steel 14 flows (high ΔT side) can be suppressed.
[Example]
First, a water model experiment will be described.

In the water model experiment, an experiment was performed using a 1/3 model in which water was regarded as molten steel 14 and the actual machine was similar. The tundish 1 used in the water model experiment was a T-type tundish shown in FIG. The number of the strands 6 was four or six.
Further, in the tundish 1 of the water model experiment, the first weir hole 9 a and the second weir hole 9 b provided in the partition weir 8 are obliquely left and right in the horizontal direction from the injection chamber 4 to the strand chamber 5 in plan view. And extends straight from the inner wall surface on the bottom 2a side of the injection chamber 4 to the inner wall surface on the upper side of the strand chamber 5 in a side view.

Further, the bottom weir 9c is located between the first weir 9a and the second weir 9b, moves horizontally or downward from the injection chamber 4 toward the strand chamber 5 in a side view, and moves back and forth. It faces in the direction and penetrates linearly so as to connect the bottom 2 a of the injection chamber 4 and the bottom 2 b of the strand chamber 5.
The bottom 2b of the strand chamber 5 connected to the outlet 10c of the bottom dam 9c is positioned below the lower end of the outlet 10c of the bottom dam 9c.

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

As for the water flow rate, the water flow rate per unit time per strand is 9 [L / min / str], and the water flow rate per unit time for four strands (4str) is 36 [L / min]. The water flow rate per unit time in the strand (6str) was set to 54 [L / min].
The method of the water model experiment was as follows.
1) The tundish 1 is filled with water used as a model of the molten steel 14, and water is allowed to flow by approximating the Froude number.

2) 50 ml of black ink was added to the injection position of the injection chamber 4 (marked by X in FIG. 19), and the flow of the black ink was photographed with a video camera, and reached each strand 6 of the strand chamber 5 from the time when the black ink was added. Measure the time to do so.
The temperature difference is large when the difference in the time to reach each of the strands 6 is large, and the temperature deviation is small when the difference in the time to reach the strands 6 is small.

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

The tundish shown in FIG. 20A has no partitioning weir 8 (comparative example, shape A).
The tundish shown in FIG. 20B is provided with a partition weir, but the height is low, so that the injection chamber 4 and the strand chamber 5 are not clearly partitioned. Further, no runner 9 is provided in the partition weir. That is, in the tundish shown in FIG. 20B, the molten steel 14 injected into the injection chamber 4 flows over the low partitioning weir into the strand chamber 5 (comparative example, shape B).

The tundish 1 shown in FIG. 20C 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. Three dam holes 9a, second dam holes 9b, and bottom dam holes 9c) are provided (Example, shape C).
The first weir hole 9a provided in the partition weir 8 has a straight 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 straight shape extending upward from the injection chamber 4 toward the strand chamber 5 and extending outward in the right direction.

Further, the bottom dam 9 c is formed in a straight line extending horizontally or downward from the injection chamber 4 to the strand chamber 5.
The bottom 2b of the strand chamber 5 connected to the outlet 10c of the bottom dam 9c is positioned below the lower end of the outlet 10c of the bottom dam 9c.
The tundish 1 shown in FIG. 20D 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. Three dam holes 9a, second dam holes 9b, and bottom dam holes 9c) are provided. Also, a pair of left and right 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 straight 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 straight shape extending upward from the injection chamber 4 toward the strand chamber 5 and extending outward in the right direction.
Further, the bottom dam 9 c is formed in a straight line extending horizontally or downward from the injection chamber 4 to the strand chamber 5.

The bottom 2b of the strand chamber 5 connected to the outlet 10c of the bottom dam 9c is positioned below the lower end of the outlet 10c of the bottom dam 9c.
Table 3 shows the calculation conditions in the numerical calculation. Tables 4 and 5 show the dimensions and configuration details 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 (ink) arrival time on each strand 6 in the water model experiment, the relationship between the tracer arrival time and the temperature deviation of the molten steel 14 was obtained by numerical calculation. Was.
The tracer set particles having the same density as that of the molten steel 14 and injected them into the injection position of the injection chamber 4 (the crosses in FIGS. 20A to 20D).

  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 (the tundish shape B) was actually measured.

Note that “T _min ” is the lowest temperature of the molten steel 14 among the temperatures of the molten steel 14 above the strand 6 (at a depth of 0.3 m 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 (at a depth of 0.3 m 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, ΔT (= T _max -T _min ) was calculated to be 8 ° C. as a result of the actual measurement, and ΔT was calculated to be 10 ° C. as a result of numerical calculation. As described above, the result of the numerical calculation of the molten steel temperature has a small difference from the actually measured result, and it can be confirmed that the phenomenon of the actual machine can be accurately reflected.

Table 7 and FIG. 21 show the relationship between (Δt / _tr ) and ΔT in the shapes A to D of the tundish 1.

“T _r ” is an average residence time of the molten steel 14 in the tundish 1 (capacity of the tundish 1 / throughput).
“T _min ” is the shortest residence time from when a tracer (ink) is supplied to the injection position (indicated by A to D in FIG. 20) in the injection chamber 4 to when it reaches the strand 6. “T _max ” is the longest residence time from when the tracer (ink) is supplied to the injection position in the injection chamber 4 to when it reaches the strand 6. “Δt” is the difference between the longest and the shortest residence time of the tracer (t _max -t _min ).

From Table 7 and FIG. 21, it is understood that (Δt / t _r ) between the strands 6 must be 0.18 or less in order to make ΔT 7 ° C. or less shown in Table 1.
Note that the larger the value of (Δt / t _r ), the greater the difference in the timing at which the tracer reaches each strand 6.
Next, examples and comparative examples of the tundish 1 for continuous casting according to the present invention will be described.

Tables 8 to 10 show examples of the tundish 1 for continuous casting of the present invention.
Note that the examples in Tables 8 and 9 were converted to actual machines based on the results of the water model shown in Table 10.

As shown in Tables 8 to 10, in the examples (No, 1 to No, 5, No, 7 to No, 9, No, 11 to No, 14), the number of the strands 6 is four, The number of the runners 9 provided in the partition weir 8 is three. In addition, about an Example (No, 6, No, 10), the number of the strands 6 is six.
In the embodiment (No. 7) and thereafter, a pair of left and right protrusions 11 are provided on the front wall 7.

Referring to Nos. 1 and 1 (Example) in Tables 8 to 10, the cross section of the runner 9 is circular.
Longitudinal diameter d ₁ of the bottom Sekiana 9c is 0.3 m, satisfies the formula (1). Further, the vertical diameter D1 of _each of the dam holes 9a and 9b is 0.2 m, which satisfies the expression (2).
Distance x ₁ is 0.3 m, so and _{(0.1z 1 + D 2/2} ) is a 0.19 m, satisfies the formula (3). Horizontal angle theta ₁ is 50 [deg.], Satisfies the equation (4).

Since (z ₂ tan θ ₂ -0.1z ₁ / cos θ ₂ ) is 0.38 and (H / 3) is 0.27 m, Expression (5) is satisfied.
Since (z ₂ tan θ ₂ + D ₁ +0.1 z ₁ / cos θ ₂ ) is 0.77 m and the depth H of the molten steel 14 is 0.8 m, the expression (6) is satisfied. Distance x ₂ is 1.15 m, so and _{(0.1 (z 1 + z 3} ) + (d 2 + D 2) / 2) is a 0.41 m, satisfies the formula (7).

Since (Δt / _tr ) is 0.15 and 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. It was also found that the outflow of inclusions into the mold 17 was also suppressed.
Referring to Nos. 2 and 2 (Examples) in Tables 8 to 10, the cross section of the runner 9 is a flat circular shape (elliptical shape) (for example, see FIG. 4).

Longitudinal diameter d ₁ of the bottom Sekiana 9c is 0.2 m, satisfies the formula (1). Further, the vertical diameter D1 of _each of the dam holes 9a and 9b is 0.2 m, which satisfies the expression (2).
Distance x ₁ is 0.3 m, so and _{(0.1z 1 + D 2/2} ) is a 0.21 m, satisfies the formula (3). Horizontal angle theta ₁ is 60 [deg.], Satisfies the equation (4).
Since (z ₂ tan θ ₂ -0.1z ₁ / cos θ ₂ ) is 0.33 m and (H / 3) is 0.27 m, Expression (5) is satisfied.

Since (z ₂ tan θ ₂ + D ₁ +0.1 z ₁ / cos θ ₂ ) is 0.71 m and the depth H of the molten steel 14 is 0.8 m, the expression (6) is satisfied. Distance x ₂ is 1 m, so and _{(0.1 (z 1 + z 3} ) + (d 2 + D 2) / 2) is at 0.4 m, which satisfies the equation (7).
Since (Δt / _tr ) is 0.18, it can be seen that the temperature deviation is small and the temperature variation of the molten steel 14 is suppressed. It was also found that the outflow of inclusions into the mold 17 was also suppressed.

Referring to Nos. 7 and 7 (Examples) in Tables 8 to 10, the cross section of the runner 9 is circular.
Longitudinal diameter d ₁ of the bottom Sekiana 9c is 0.2 m, satisfies the formula (1). Further, the vertical diameter D1 of _each of the dam holes 9a and 9b is 0.2 m, which satisfies the expression (2).
Distance x ₁ is 0.3 m, so and _{(0.1z 1 + D 2/2} ) is at 0.2 m, satisfies the formula (3). Horizontal angle theta ₁ is 45 [deg.], Satisfies the equation (4).

Since (z ₂ tan θ ₂ -0.1z ₁ / cos θ ₂ ) is 0.38 m and (H / 3) is 0.27 m, Expression (5) is satisfied.
(z ₂ tan θ ₂ + D ₁ +0.1 z ₁ / cos θ ₂ ) is 0.79 m, and the depth H of the molten steel 14 is 0.8 m, so that the expression (6) is satisfied. Distance x ₂ is 1.3 m, so and _{(0.1 (z 1 + z 3} ) + (d 2 + D 2) / 2) is a 0.37 m, satisfies the formula (7).

The thickness y of the projection 11 is 0.1 m, which satisfies the expression (8). The width L of the protrusion 11 is 0.3 m, which satisfies Expression (9).
Since the height h of the projection 11 is 0.3 m, (d ₁ + 0.1z ₁ ) is 0.3 m, and (z ₂ tan θ ₂ -0.1z ₁ / cos θ ₂ ) is 0.38 m, Equation (10) is satisfied. Distance x ₃ is 1.15 m, so and _{(0.1z 3 + d 2/2} ) is a 0.17 m, satisfies the formula (11).

Since (Δt / t _r ) is 0.09 and 0.18 or less, it can be seen that the temperature deviation is very small and the variation in the temperature of the molten steel 14 is suppressed. It was also found that the outflow of inclusions into the mold 17 was also suppressed.
Referring to Nos. 10 and 10 (Examples) in Tables 8 to 10, the number of the strands 6 is six, and the cross section of the runner 9 is a square shape (for example, see FIG. 4).

The height of the bottom Sekiana 9c (longitudinal diameter) d ₁ is 0.2 m, satisfies the formula (1). The height (longitudinal diameter) D1 of _{each of} the dam holes 9a and 9b is 0.2 m, which satisfies the expression (2).
Distance x ₁ is 0.5 m, so and _{(0.1z 1 + D 2/2} ) is at 0.2 m, satisfies the formula (3). Horizontal angle theta ₁ is 45 [deg.], Satisfies the equation (4).
Since (z ₂ tan θ ₂ -0.1z ₁ / cos θ ₂ ) is 0.38 m and (H / 3) is 0.27 m, Expression (5) is satisfied.

(z ₂ tan θ ₂ + D ₁ +0.1 z ₁ / cos θ ₂ ) is 0.79 m, and the depth H of the molten steel 14 is 0.8 m, so that the expression (6) is satisfied. Distance x ₂ is 1.3 m, so and _{(0.1 (z 1 + z 3} ) + (d 2 + D 2) / 2) is a 0.37 m, satisfies the formula (7).
The thickness y of the projection 11 is 0.2 m, which satisfies the expression (8). The width L of the protrusion 11 is 1.53 m, which satisfies Expression (9).

Since the height h of the projection 11 is 0.35 m, (d ₁ + 0.1z ₁ ) is 0.3 m, and (z ₂ tan θ ₂ -0.1z ₁ / cos θ ₂ ) is 0.38 m, Equation (10) is satisfied. Distance x ₃ is 0.17 m, so and _{(0.1z 3 + d 2/2} ) is a 0.17 m, satisfies the formula (11).
Since (Δt / t _r ) is 0.09 and 0.18 or less, it can be seen that the temperature deviation is very small and the variation in the temperature of the molten steel 14 is suppressed. It was also found that the outflow of inclusions into the mold 17 was also suppressed.

As described above, it can be seen that Examples (No, 1 to No, 14) shown in Tables 8 to 10 are excellent.
On the other hand, Tables 11 to 13 show comparative examples of tundish.
The comparative examples in Tables 11 and 12 are obtained by performing numerical calculations based on the results of the water model shown in Table 13 and converting the results to actual machines.

As shown in Tables 11 to 13, in the comparative examples (No, 1 to No, 6, No, 8), the number of strands 6 is four and the number of runners 9 is three.
In addition, about the comparative example (No, 7), the number of the strands 6 is six. Further, in the comparative example (No. 8, 8), the front wall 7 is provided with a pair of left and right protrusions 11.
Referring to Nos. 5 and 5 (Comparative Example) in Tables 11 to 13, the cross section of the runner 9 is circular. Since (z ₂ tan θ ₂ -0.1z ₁ / cos θ ₂ ) is 0.26 m and (H / 3) is 0.27 m, Expression (5) is not satisfied. Since (Δt / _tr ) is 0.23 and exceeds 0.18, the temperature deviation is large, and the variation in the temperature of the molten steel 14 is not suppressed.

Referring to Nos. 7 and 7 (Comparative Examples) in Tables 11 to 13, the cross section of the runner 9 is circular. Distance x ₂ is 0.27 m, so and _{(0.1 (z 1 + z 3} ) + (d 2 + D 2) / 2) is a 0.29 m, it does not satisfy the equation (7). Since (Δt / _tr ) is 0.22 and exceeds 0.18, the temperature deviation is large and the variation in the temperature of the molten steel 14 is not suppressed.
Referring to Nos. 8 and 8 (Comparative Example) in Tables 11 to 13, the cross section of the runner 9 is circular (for example, see FIG. 4). A horizontal angle theta ₁ is 70 [deg.], It does not satisfy the equation (4). Since (Δt / _tr ) is 0.2 and exceeds 0.18, the temperature deviation is large, and the variation in the temperature of the molten steel 14 is not suppressed.

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

The tundish 1 for continuous casting of the present invention described above is applicable to a continuous casting method using a continuous casting device 15 as shown in FIG.
As shown in FIG. 22, the continuous casting device 15 is, for example, a device that continuously casts the molten steel 14 after the secondary refining process, and includes the tundish 1 into which the molten steel 14 in the ladle 16 is injected, A mold 17 for casting 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. The shape of the slab 19 cast by the continuous casting device 15 is not limited, and may be a slab, a bloom, a billet, or the like.

In the embodiments disclosed this time, items not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weight, volume, and the like of the components deviate from the range usually performed by those skilled in the art. Instead, it employs items that can be easily assumed by a person skilled in the art.

1 Tundish 2a Bottom (injection chamber)
2b Bottom (Strand room)
3 peripheral wall 4 injection chamber 5 strand chamber 6 mold injection hole (strand)
7 Front wall surface (front wall)
8 partition weir 9 runner 9a first runner (first weir hole)
9b 2nd runner (2nd dam)
9c 3rd runner (bottom weir)
10a Exit of first runner 10b Exit of second runner 10c Exit 11 of third runner Projection (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 injection chambers into which molten steel from a ladle is injected, and a plurality of mold injection holes which are forward of the injection chamber, are elongated in the left-right direction from the injection chamber, and have bottoms for charging the molten steel into the mold. In a tundish having a strand chamber having, a partition weir for separating the injection chamber and the strand chamber, and a runner provided in the partition weir and linearly penetrating from the injection chamber to the strand chamber,
The runner moves obliquely leftward in the horizontal direction in plan view, and the bottom side of the injection chamber from the side view, 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 runner penetrating in a straight line,
Transition to the diagonally right side in the horizontal direction in plan view, and penetrate in a straight line from the bottom side of the injection chamber, the inner wall surface of the partition weir to the upper side of the strand chamber, and the inner wall surface of the partition weir in a side view. And a second hot water running,
Further, the runner is located between the first runner and the second runner, transitions horizontally or downward from the injection chamber toward the strand chamber in a side view, and is viewed in a plan view. Has a third runner that penetrates in a straight line in the front-rear direction,
The first runner is provided on the left side of the third runner in plan view,
The second runner is provided on the right side of the third runner in plan view,
The mold pouring hole is an extension of a horizontal central axis of the first runner facing upward, and a horizontal outer side of an extension of a horizontal central axis of the second runner facing upward. Located in the area,
The bottom of the strand chamber connected to the outlet of the third runner is located below the lower end of the outlet of the third runner and satisfies Expressions (1) to (7). Tundish for continuous casting.
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 / cos θ ₂ ≧ H / 3 [m] (5)
z ₂ tan θ ₂ + D ₁ + 0.1z ₁ / cos θ ₂ ≦ H [m] (6)
x ₂ ≧ 0.1 (z ₁ + z ₃ ) + (d ₂ + D ₂ ) / 2 [m] (7)
d ₁ : vertical diameter of the third runner
d ₂ : lateral diameter of the third runner
D ₁ : Vertical diameter of the first runner and the second runner
D ₂ : lateral diameter of the first runner and the second runner
x ₁ : The point where the extension line of the central axis of the first runner and the second runner that faces upward intersects the front wall surface of the strand chamber, and the vertical direction of the mold injection hole closest to the partition weir. Distance between the point where the horizontal extension line passing through the central axis intersects the front wall surface of the strand chamber
θ ₁ : Horizontal angle at the center side in the strand chamber width direction at the point where the extension line of the central axis of the first and second runners facing upward intersects the front wall surface of the strand chamber.
θ ₂ : upward angle of the first runner and the second runner facing upward
z ₁ : Horizontal length of the strand chamber on the extension of the axis 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 wall surface of the strand chamber at the axis of the first runner and the second runner facing upward.
z ₃ : Horizontal length of the strand chamber on the extension of the axis of the third runner that is horizontal or downward
H: Depth of molten steel
x ₂ : the point where the extension of the central axis of the first or second runner intersects with the front wall surface of the strand chamber and the point where the extension of the central axis of the third runner intersects with the front wall of the strand chamber. Distance between The strand chamber, in front of the injection chamber, is provided with a protrusion that abuts against a front wall surface of the strand chamber, and that stands upright 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 at right and left sides with a predetermined interval, and satisfy Expressions (8) to (11). 3.
y ≧ 0.1 [m] (8)
L ≧ 0.2 [m] ・ ・ ・ (9)
d ₁ + 0.1z ₁ ≦ h ≦ z ₂ tan θ ₂ -0.1z ₁ / cos θ ₂ [m] (10)
_{x 3 ≧ 0.1z 3 + d 2} /2 [m] ··· (11)
y: Length of the protrusion in the front-rear direction
L: Width of protrusion
h: Height of protrusion
x ₃ : distance between the point where the extension of the central axis of the third runner intersects the front wall surface of the strand chamber and the end of the protrusion on the extension side of the central axis of the third runner   A continuous casting method using the tundish for continuous casting according to claim 1 or 2.