Electromagnetic stirring device

Abstract

To provide an electromagnetic stirrer easily realizing, in continuously casting in parallel slabs in respective ones of a plurality of molds, inhibition of a nonuniform stirring force imparted to a molten metal within each of the molds.SOLUTION: An electromagnetic stirrer includes magnetic-field intrusion-inhibiting members 430a-430b configured by using an electrically conductive material in at least passage positions of a line of magnetic force of a moving magnetic-field directed toward a hollow of a mold 100b located closest in position to a center in an X-axis direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electromagnetic stirring device, and is particularly suitable for use in continuously casting a slab.

Background Art

[0002] When continuously casting a slab such as a slab, the molten metal supplied from a ladle to a tundish is injected into a hollow portion (region surrounded by a mold) of the mold by an immersion nozzle. Then, the metal whose surface has solidified in the mold becomes a slab and is continuously drawn out from the mold.

[0003] As a device for improving the quality of a slab continuously cast in this way, there is an electromagnetic stirring device. The electromagnetic stirring device is a device that applies a stirring force that circulates in the horizontal plane to the molten metal by generating an alternating magnetic field with respect to the molten metal in the mold by passing an electric current through a coil of an electromagnet.

[0004] The electromagnetic stirring device includes a linear moving magnetic field type electromagnetic stirring device and a rotating magnetic field type electromagnetic stirring device. The rotating magnetic field type electromagnetic stirring device includes a plurality of electromagnets arranged so as to surround the mold with an interval in the circumferential direction of the mold, and generates a rotating magnetic field with respect to the molten metal in the mold from the electromagnets, thereby applying a stirring force that circulates in the horizontal plane to the molten metal. On the other hand, the linear moving magnetic field type electromagnetic stirring device includes a pair of electromagnets arranged so as to face each other with the mold interposed therebetween, and generates a moving magnetic field in opposite directions with respect to the molten metal in the mold from the pair of electromagnets, thereby applying a stirring force that circulates in the horizontal plane to the molten metal (note that the moving magnetic field is also referred to as a traveling magnetic field or the like).

[0005] By the way, for reasons such as improving the production capacity of a slab, a plurality of molds and strands are arranged side by side in the horizontal direction, and slabs are continuously cast in parallel in each of the plurality of molds. As described above, in a rotating magnetic field type electromagnetic stirring device, a plurality of electromagnets are arranged so as to surround a mold. Therefore, in order to continuously cast slabs in parallel in each of the plurality of molds, it is necessary to arrange an electromagnetic stirring device individually for each of the plurality of molds. Therefore, the number of electromagnetic stirring devices required is equal to the number of molds (strands). This leads to an increase in the size and cost of the continuous casting facility, as well as an increase in the workload for manufacturing and installing the electromagnetic stirring device.

[0006] On the other hand, in a linear moving magnetic field type electromagnetic stirring device, a pair of electromagnets arranged so as to face each other with a mold interposed therebetween are arranged. Therefore, it is not necessary to arrange an electromagnetic stirring device individually for each of the plurality of molds. Thus, for example, by using a pair of electromagnets arranged so as to face each other with a plurality of molds interposed therebetween, the number of electromagnetic stirring devices required for continuously casting slabs in parallel in each of the plurality of molds can be reduced to one (however, two or more electromagnetic stirring devices can also be used).

[0007] However, in a linear moving magnetic field type electromagnetic stirring device, the stirring force applied to the molten metal in the mold is greater for the molten metal in the inner (central side) of the mold than for the molten metal in the outer (both end sides) of the mold. Thus, when the stirring force applied to the molten metal in the mold by the mold becomes non-uniform, the quality of the slab also becomes non-uniform.

[0008] Therefore, Patent Document 1 discloses that the number of turns of the coil corresponding to the strands other than the two end strands in three or more strands is set to 0.76 to 0.85 times the number of turns of the coil corresponding to the two end strands.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] However, in the technique described in Patent Document 1, the stirring force on the molten metal for each mold depends on the number of turns of the coil. Therefore, the change range of the stirring force on the molten metal with respect to the change in the number of turns of the coil is large. Thus, there are cases where the non-uniformity of the stirring force on the molten metal for each mold cannot be sufficiently suppressed.

[0011] Further, in the technique described in Patent Document 1, the number of magnetic poles of the electromagnetic stirring device must be a multiple of the number of strands. Therefore, there are restrictions on the number of magnetic poles of the electromagnetic stirring device. Also, when applying the technique described in Patent Document 1 to existing continuous casting equipment, the existing coil must be removed, remanufactured, and reinstalled, resulting in a large work burden. As described above, in the technique described in Patent Document 1, the work burden and restrictions for manufacturing, changing, and installing the electromagnetic stirring device increase.

[0012] The present invention has been made in view of the above problems, and an object thereof is to easily suppress the non-uniformity of the stirring force applied to the molten metal in each mold when continuously casting slabs in parallel in each of a plurality of molds.

Means for Solving the Problems

[0013] The electromagnetic stirring device of the present invention includes a first core and a second core arranged to face each other in the depth direction via three or more plurality of molds arranged in parallel in the width direction in a spaced state, a first coil wound around the first core, and a second coil wound around the second core, and generates a moving magnetic field in opposite directions based on an alternating current flowing through the first coil and the second coil to stir the molten metal continuously cast by generating the moving magnetic field in opposite directions with respect to the molten metal injected into the hollow portion of the mold. The electromagnetic stirring device is an electromagnetic stirring device, and includes a magnetic field entry suppression member configured using a conductive material which is a material through which the moving magnetic field penetrates or a conductive material through which the moving magnetic field does not penetrate and the magnetic field entry suppression member When the magnetic field entry suppressing member is configured using the material through which the moving magnetic field penetrates is 、Among the plurality of molds of at least also the one is arranged at a position where magnetic field lines of a traveling magnetic field directed toward the hollow portion of the mold pass through And when the magnetic field entry suppressing member is configured using the material through which the moving magnetic field does not penetrate, the magnetic field entry suppressing member Among the plurality of molds is disposed at a position where only some of the magnetic field lines of all the magnetic field lines of the moving magnetic field directed toward the hollow portion of at least the first mold pass, and the first mold is the mold closest to the center in the width direction among the plurality of molds .

Advantages of the Invention

[0014] According to the present invention, when continuously casting slabs in parallel in each of a plurality of molds, it is possible to easily suppress non-uniformity of the stirring force applied to the molten metal in each mold.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 3

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Figure 8A

Figure 8B

Figure 8C

Figure 9A

Figure 9B

Figure 9C

Embodiments for Carrying Out the Invention

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that, for comparisons such as length, position, size, interval, etc., when the comparison targets are the same, it includes not only the case where they are exactly the same, but also those that are different within a range that does not deviate from the gist of the invention (for example, those that are different within the tolerance range determined during design). Also, in each figure, for convenience of explanation and notation, a part of the configuration is shown with omission or simplification. Also, in each figure, the X - Y - Z coordinates are for showing the directional relationship in each figure. The symbol with ● in 〇 indicates that it is a coordinate axis where the direction from the back side to the front side of the paper surface is the positive direction (the direction of the tip of the arrow). The symbol with × in 〇 indicates that it is a coordinate axis where the direction from the front side to the back side of the paper surface is the positive direction.

[0017] <An Example of the Configuration of a Continuous Casting Facility> FIG. 1 is a diagram showing an example of the configuration of a continuous casting facility. FIG. 1 is a sectional view when the continuous casting facility is cut perpendicularly to the casting direction (Z - axis direction). FIGS. 2A, 2B, and 2C are sectional views taken along the line I - I, II - II, and III - III of FIG. 1, respectively.

[0018] In FIGS. 1 to 2C, the continuous casting facility includes mold 100a to 100c, back plates 200a to 200c, immersion nozzles 300a to 300c, and an electromagnetic stirring device 400a. Note that, among the continuous casting facilities, the configurations other than the magnetic field entry suppression members 430a to 430b provided in the electromagnetic stirring device 400a are realized by known techniques and are not limited to the configurations exemplified below.

[0019] In the continuous casting equipment, molten metal is supplied from a tundish (not shown) into the immersion nozzles 300a to 300c. Hereinafter, the case where the molten metal is molten steel will be exemplified. The amount of molten steel supplied from the tundish into the immersion nozzles 300a to 300c is adjusted using a sliding nozzle (not shown) disposed at the base end portions of the immersion nozzles 300a to 300c. Also, the amount of molten steel supplied from the tundish into the immersion nozzles 300a to 300c may be adjusted using a stopper (not shown). The stopper is for adjusting the opening area of a region that communicates between the tundish (not shown) and the immersion nozzles 300a to 300c by moving forward and backward within the tundish (not shown).

[0020] As shown in FIG. 2C, the molten steel supplied into the immersion nozzles 300a to 300c is supplied from discharge ports 310 formed on the tip surfaces (surfaces on the negative direction side of the Z axis) of the immersion nozzles 300a to 300c into the hollow portions of the molds 100a to 100c. In the present embodiment, the case where the immersion nozzles 300a to 300c are the same will be exemplified.

[0021] The molds 100a to 100c are molds for continuously casting a slab S having a predetermined width and thickness by cooling molten steel and solidifying it into a predetermined shape. The slab S is, for example, a bloom or a billet. The molds 100a to 100c are configured using, for example, copper. The back plates 200a to 200c are disposed on the outer wall surfaces of the molds 100a to 100c so as to support the molds 100a to 100c. The back plates 200a to 200c are configured using, for example, stainless steel. Flow paths (not shown) through which cooling water passes are formed in the molds 100a to 100c and the back plates 200a to 200c. By flowing cooling water through the flow paths, the molten steel is solidified while cooling the continuous casting equipment. In the present embodiment, the back plates 200a to 200c are an example of a structure connected to the molds 100a to 100c.

[0022] In this embodiment, a case where the molds 100a to 100c are the same is exemplified. Similarly, in this embodiment, a case where the back plates 200a to 200c are the same is exemplified. Note that powder (not shown) may be added to the hollow portions of the molds 100a to 100c. The powder mainly contains, for example, CaO, Al2O3, and SiO2, and has roles such as preventing oxidation of molten steel, collecting inclusions, lubricating between the molds 100a to 100c and the molten steel, and suppressing rapid cooling of the molten steel.

[0023] The molten steel poured into the hollow portions of the molds 100a to 100c is cooled by the molds 100a to 100c, and a solidification shell is formed from its surface and solidifies. A slab S whose surface is a solidification shell but whose interior is not solidified is continuously drawn in the negative direction of the Z-axis with the casting speed controlled from the lower ends of the molds 100a to 100c (see FIGS. 2A to 2C).

[0024] As shown in FIG. 1, the plurality of molds 100a to 100c are arranged in parallel in the width direction (of the continuous casting facility) with an interval. In this embodiment, a case where three molds 100a to 100c are arranged in parallel at equal intervals in the width direction and the continuous casting facility includes three strands is exemplified. The width direction is the direction in which the plurality of molds 100a to 100c are arranged, and is the so-called casting width direction. In the example shown in FIG. 1, the X-axis direction is the width direction. In the following description, the width direction is referred to as the X-axis direction as needed.

[0025] Below the three molds 100a to 100c, secondary cooling zones are arranged respectively. In the secondary cooling zones, support rolls and cooling sprays (not shown) are arranged. The slab S drawn from the lower ends of the molds 100a to 100c is conveyed by the support rolls (not shown). In the process of being drawn from the molds 100a to 100c in this way, the molten steel is cooled by the cooling water sprayed from the cooling sprays (not shown), so that the molten steel solidifies to the inside, and the slab S is manufactured. Note that the casting direction of the slab S is in the negative direction of the Z-axis in the region directly below the molds 100a to 100c, but approaches a direction parallel to the X-Y plane as it moves away from the molds 100a to 100c. Support rolls (not shown) are arranged along the casting direction of the slab.

[0026] In the present embodiment, an example is illustrated in which slabs are continuously cast in parallel using the three molds 100a to 100c as described above. Note that the number of molds (strands) arranged in parallel with intervals is not limited to three as long as it is three or more, and may be four or more. Also, the number of molds (strands) arranged in parallel with intervals may be even or odd.

[0027] <An example of the configuration of the electromagnetic stirring device 400a> In FIGS. 1 to 2C, the electromagnetic stirring device 400a is a device that generates a traveling magnetic field for the molten steel (unsolidified portion) discharged from the immersion nozzles 300a to 300c and filled in the upper part of the hollow portions of the molds 100a to 100c based on the principle of a linear motor, thereby applying an electromagnetic force to the molten steel to impart a stirring force, and generating a stirring flow that circulates along the inner wall surfaces of the molds 100a to 100c to stir the molten steel. The electromagnetic stirring device 400a is a so-called linear traveling magnetic field type electromagnetic stirring device. The electromagnetic stirring device 400a includes a first core 410a, a second core 410b, a first coil 420a, a second coil 420b, magnetic field entry suppression members 430a to 430b, and an AC power source (not shown).

[0028] The first core 410a and the second core 410b are made of a soft magnetic material. The first core 410a and the second core 410b are formed, for example, by laminating soft magnetic plates (e.g., non-oriented electrical steel sheets) having the same shape and size as the cross-section perpendicular to the Z-axis direction of the first core 410a and the second core 410b in the Z-axis direction. In the present embodiment, a case where the first core 410a and the second core 410b are the same is exemplified.

[0029] The first core 410a and the second core 410b are arranged to face each other in the depth direction (of the continuous casting facility) via a plurality of molds 100a to 100c arranged in parallel in the X-axis direction with an interval therebetween. In the present embodiment, a case where the first core 410a and the second core 410b are arranged to have a mirror-symmetric relationship with the plane passing through the axes of the three molds 100a to 100c as the symmetry plane is exemplified. The axes of the molds 100a to 100c are virtual lines passing through the positions of the centers of gravity of the hollow portions of the molds 100a to 100c and extending in the casting direction (Z-axis direction). The depth direction is the direction in which the first core 410a and the second core 410b face each other, and is the so-called casting thickness direction. In the examples shown in FIGS. 1 to 2, the Y-axis direction is the depth direction. In the following description, the depth direction is referred to as the Y-axis direction as necessary.

[0030] Note that in the present embodiment, a case where the first core 410a is not a plurality of cores arranged separately with an interval therebetween but a single core is exemplified. Similarly, a case where the second core 410b is not a plurality of cores arranged separately with an interval therebetween but a single core is exemplified.

[0031] The first coil 420a is wound around the first core 410a. The second coil 420b is wound around the second core 410b. An alternating current is applied to each of the first coil 420a and the second coil 420b to generate the above-described rotating magnetic field. In the present embodiment, a case where a three-phase alternating current is applied from an AC power source to the first coil 420a and the second coil 420b is exemplified. Therefore, each of the first coil 420a and the second coil 420b includes a plurality of coils for each phase. In FIG. 1, a case where the electromagnetic stirring device 400a is a two-pole (number of magnetic poles = 2) electromagnetic stirring device is exemplified. In FIG. 1, +U, +V, +W, -U, -V, -W indicate coils to which alternating currents of the +U phase, +V phase, +W phase, -U phase, -V phase, and -W phase are supplied, respectively. Here, the phase that is delayed by about 60 degrees with respect to the +U phase is the -W phase. Similarly, the phase that is delayed by 120 degrees with respect to the +U phase is the +V phase, the phase that is delayed by 180 degrees is the -U phase, the phase that is delayed by 240 degrees is the +W phase, and the phase that is delayed by 300 degrees is the -V phase. As described above, each of the first coil 420a and the second coil 420b is configured using a plurality of coils through which three-phase alternating currents of each phase flow. Note that the AC power source that generates the three-phase alternating current is not particularly limited. For example, an inverter power source is used as the AC power source.

[0032] When operating the electromagnetic stirring device 400a, for example, by passing a three-phase alternating current through the first coil 420a, a moving magnetic field that moves in the X-axis direction is generated in the region on the side where the first coil 420a is disposed (the positive direction side of the Y-axis) among the regions of the hollow portions of the molds 100a to 100c. Also, by passing a three-phase alternating current through the second coil 420b, a moving magnetic field that moves in the X-axis direction is generated in the region on the side where the second coil 420b is disposed (the negative direction side of the Y-axis) among the regions of the hollow portions of the molds 100a to 100c, and the direction of the moving magnetic field generated by passing a three-phase alternating current through the first coil 420a is opposite. This moving magnetic field generates eddy currents in the molten steel according to Faraday's law and Lenz's law. This eddy current and the moving magnetic field form a stirring force in the molten steel based on Fleming's left-hand rule. Due to this stirring force, a stirring flow (flow of molten steel) that circulates along the inner wall surfaces of the molds 100a to 100c is generated in the horizontal plane (X-Y plane). A method for generating a stirring force in the molten steel by a moving magnetic field is known, for example, as described in Patent Document 1 and Japanese Patent No. 5353883, and thus, a detailed description thereof is omitted here. In this embodiment, a case where the number of turns of the coils of each phase is the same is illustrated. However, it is not necessarily required to be like this as long as the above-described moving magnetic field can be generated to generate a stirring flow. Even when the number of turns of the coils of each phase is made different in this way, the electromagnetic stirring device 400a of this embodiment is not subject to the restrictions on the number of turns as described in Patent Document 1. Also, as long as the above-described moving magnetic field can be generated to generate a stirring flow, the AC power supply is not limited to a three-phase AC power supply.

[0033] Next, an example of the magnetic field entry suppression members 430a to 430b will be described. In a linear moving magnetic field type electromagnetic stirring device, at the ends in the X-axis direction, there are no coils and cores for generating a moving magnetic field ahead of the ends. Therefore, among the plurality of molds arranged in parallel in the X-axis direction, the closer the mold is to the end in the X-axis direction, the smaller the moving magnetic field (magnetic flux) entering the hollow part (molten steel) of the mold, and the lower the magnetic flux density (in other words, the closer the mold is to the center in the X-axis direction, the higher the magnetic flux density in the hollow part (molten steel) of the mold). Thus, the stirring force on the molten steel in the hollow part of the mold located on the center side in the X-axis direction becomes larger than the stirring force on the molten steel in the hollow part of the mold located on the end side in the X-axis direction, and a difference occurs in the stirring force on the molten steel in the hollow part of the mold depending on the position of the mold in the X-axis direction. In the example shown in FIG. 1, the stirring force on the molten steel in the hollow part of mold 100b is larger than the stirring force on the molten steel in the hollow parts of molds 100a and 100c.

[0034] Therefore, the inventors of the present invention have conceived of reducing the magnetic flux density of the moving magnetic field in the hollow part of the mold by arranging a magnetic field entry suppression member made of a conductive material at a position through which the magnetic field lines of the moving magnetic field directed to the hollow part of the first mold, which is the mold closest to the center in the X-axis direction among the plurality of molds, pass. The magnetic field entry suppression member is made of a conductive material. Therefore, by arranging the magnetic field entry suppression member at a position through which the magnetic field lines of the moving magnetic field directed to the hollow part of the mold located on the center side in the X-axis direction pass, eddy currents flow through the magnetic field entry suppression member so as to reduce the moving magnetic field. Thus, the strength of the moving magnetic field entering the mold located on the center side in the X-axis direction becomes smaller than when the magnetic field entry suppression member does not exist. The center in the X-axis direction is the center in the X-axis direction of a straight line (virtual line) having the centers of gravity of the hollow parts of the two molds located at both ends in the X-axis direction among the plurality of molds as both ends.

[0035] As shown in FIG. 1, when three molds 100a to 100c are arranged at intervals in the X-axis direction, among the three molds 100a to 100c, the mold at the position closest to the center in the X-axis direction is the mold 100b, and the mold 100b is an example of the first mold. Therefore, a magnetic field entry suppression member is arranged at a position through which the magnetic field lines of the moving magnetic field toward the hollow portion of the mold 100b pass. By doing so, among the plurality of molds 100a to 100c, the magnetic flux density of the molten steel in the hollow portion of the mold 100b (the mold at the position closest to the center in the X-axis direction), where the magnetic flux density of the moving magnetic field is the highest, can be lowered. Therefore, the difference in the moving magnetic field entering the molds 100a to 100c can be reduced. That is, the difference in the stirring force on the molten steel in the hollow portions of the molds 100a to 100c can be reduced.

[0036] <<Magnetic field entry suppression members 430a to 430b>> FIG. 3 is a diagram conceptually showing an example of the moving magnetic field entering the mold 100b. In FIG. 3, it is assumed that the moving magnetic field progresses from the positive direction to the negative direction of the X-axis (from right to left toward the paper surface). In FIG. 3(a), the magnetic field line M1 indicates the magnetic field line of the moving magnetic field that, at time t1, goes from the magnetic pole surface P1 toward the hollow portion of the mold 100b, enters the hollow portion of the mold 100b, and then reaches the magnetic pole surface P2. In FIG. 3(b), the magnetic field line M2 indicates the magnetic field line of the moving magnetic field that, at a time t2 later than time t1, goes from the magnetic pole surface P3 toward the hollow portion of the mold 100b, enters the hollow portion of the mold 100b, and then reaches the magnetic pole surface P4.

[0037] Note that the ">" attached to magnetic field lines M1 to M2 indicates the direction of the magnetic field lines (magnetic field vectors), showing that they are magnetic field lines directed toward the sharp end side of the ">". In FIG. 3, for the sake of explanation and notation, the number of magnetic field lines is shown to be less than the actual number, and the shape of the magnetic field lines is simplified. For example, the magnetic field lines of the moving magnetic field directed toward the hollow portion of the mold 100b at time t1 exist in addition to the magnetic field lines M1. Similarly, the magnetic field lines of the moving magnetic field directed toward the hollow portion of the mold 100b at time t2 exist in addition to the magnetic field lines M2. Also, in FIG. 3, the magnetic field lines M1 to M2 are shown as being parabolic. However, the actual magnetic field lines are more complex than those shown in FIG. 3.

[0038] In FIG. 3, in the present embodiment, the magnetic field entry suppressing members 430a to 430b are arranged at positions through which the magnetic field lines M1 to M2 of the moving magnetic field directed toward (i.e., entering) the hollow portion of the mold 100b pass. By doing so, eddy currents flow through the magnetic field entry suppressing members 430a to 430b made of a conductive material to reduce the moving magnetic field, and the moving magnetic field entering the hollow portion of the mold 100b can be reduced. As described above, at times t1 and t2, the magnetic field lines of the moving magnetic field directed toward the hollow portion of the mold 100b exist in addition to the magnetic field lines M1 and M2, and the magnetic field entry suppressing members 430a to 430b may be arranged at positions through which a part of the magnetic field lines of the moving magnetic field directed toward the hollow portion of the mold 100b pass. However, the magnetic field entry suppressing member may be arranged at a position through which all of the magnetic field lines of the moving magnetic field directed toward the hollow portion of the mold 100b pass. For example, if the magnetic field entry suppressing member is arranged on the entire outer wall surface of the back plate 200b, the magnetic field entry suppressing member can be arranged at a position through which all of the magnetic field lines directed toward (entering) the hollow portion of the mold 100b pass. As described above, the position through which the magnetic field lines of the moving magnetic field directed toward the hollow portion of the mold 100b pass may be a position through which at least a part of the magnetic field lines of the moving magnetic field directed toward the hollow portion of the mold 100b pass. Note that at least a part of the magnetic field lines means N magnetic field lines (N ≤ M) when the total number of the magnetic field lines of the moving magnetic field directed toward the hollow portion of the mold 100b is M.

[0039] In this embodiment, a case where the magnetic field entry suppressing members 430a to 430b are the same is exemplified. Further, in this embodiment, as shown in FIG. 1, among the three molds 100a to 100c, the mold 100b located at the position closest to the center in the X-axis direction, and between the mold 100b and the adjacent molds 100a and 100c having a space in the X-axis direction (between the molds 100a to 100b and between the molds 100b to 100c), a case where the magnetic field entry suppressing members 430a to 430b are arranged is exemplified. In this way, in this embodiment, the molds 100a and 100c are examples of the second mold. In this way, the magnetic field entry suppressing members 430a to 430b can be arranged using the regions between the two molds 100a to 100b and 100b to 100c. Therefore, changes to the existing configuration of the electromagnetic stirring device 400a and the continuous casting facility are reduced. Further, it is not necessary to arrange a magnetic field entry suppressing member in the region between the electromagnetic stirring device 400a (the first core 410a and the second core 410b) and the molds 100a to 100c. Therefore, the distance (in the Y-axis direction) between the electromagnetic stirring device 400a (the first core 410a and the second core 410b) and the molds 100a to 100c can be shortened. Thus, it is possible to easily and surely secure the stirring force required for stirring the molten steel in the hollow portions of the molds 100a to 100c.

[0040] Further, in this embodiment, a case where the magnetic field entry suppressing members 430a to 430b are respectively arranged so as to contact both end faces (the end face on the positive X-axis direction side and the end face on the negative X-axis direction side) of the back plate 200b in the X-axis direction is exemplified. In this way, it is possible to more surely suppress the traveling magnetic field entering the hollow portion of the mold 100b. Further, since the magnetic field entry suppressing members 430a to 430b may be attached to the outer wall surface of the back plate 200b in the X-axis direction, the installation of the magnetic field entry suppressing members 430a to 430b becomes easy. Note that when the mold is configured so that the strength of the mold can be ensured only by the mold without using a structure such as a back plate, the magnetic field entry suppressing member may be arranged so as to contact the mold.

[0041] Also, as described above, the closer the mold is to the center in the X-axis direction, the higher the magnetic flux density in the hollow portion (molten steel) of the mold. Therefore, in the present embodiment, among the regions between two adjacent molds 100a to 100b and 100b to 100c spaced apart in the X-axis direction, at least in the region closest to the center in the X-axis direction, magnetic field entry suppressing members 430a to 430b are arranged. By doing so, among the plurality of molds 100a to 100c, the magnetic flux density in the hollow portion of the mold 100b where the magnetic flux density of the moving magnetic field is the highest can be made lower more reliably. As shown in FIG. 1, when three molds 100a to 100c are arranged at equal intervals in the X-axis direction, the regions between two adjacent molds 100a to 100b and 100b to 100c spaced apart in the X-axis direction are all regions closest to the center in the X-axis direction.

[0042] Also, in the present embodiment, the magnetic field entry suppressing members 430a to 430b are formed in a plate shape. By doing so, for example, the thickness of the magnetic field entry suppressing members 430a to 430b can be easily adjusted by stacking a plurality of copper plates. The thickness of the magnetic field entry suppressing members 430a to 430b is determined according to the material, size, position of the magnetic field entry suppressing members 430a to 430b, and the frequency of the current flowing through the first coil 420a and the second coil 420b. As the thickness of the magnetic field entry suppressing members 430a to 430b, for example, a thickness selected from the range of 3 mm or more and 25 mm or less, preferably 5 mm or more and 15 mm or less is exemplified. When the magnetic field entry suppressing members 430a to 430b are configured by stacking a plurality of copper plates, the thickness of the magnetic field entry suppressing members 430a to 430b is the total value of the thicknesses of the plurality of copper plates. Also, even when the arrangement space for the magnetic field entry suppressing members 430a to 430b is narrow (for example, when the interval (in the X-axis direction) between two molds 100a to 100b and 100b to 100c is short), the magnetic field entry suppressing members 430a to 430b can be installed. Thus, it is preferable that the magnetic field entry suppressing members 430a to 430b are formed in a plate shape, but the shape of the magnetic field entry suppressing members 430a to 430b is not limited to a plate shape.

[0043] Further, in the present embodiment, as shown in FIGS. 2A and 2B, the casting direction position (Z coordinate) Z1 of the end portion on the upstream side (the positive direction side of the Z axis) in the casting direction of the magnetic field entry suppressing members 430a to 430b is set to be upstream in the casting direction than the casting direction position (Z coordinate) Z2 of the end portion on the upstream side in the casting direction of the first core 410a and the second core 410b (Z1>Z2). In addition to this, the casting direction position (Z coordinate) Z3 of the end portion on the downstream side (the negative direction side of the Z axis) in the casting direction of the magnetic field entry suppressing members 430a to 430b is set to be downstream in the casting direction than the casting direction position (Z coordinate) Z4 of the end portion on the downstream side in the casting direction of the first core 410a and the second core 410b (Z3<Z4).

[0044] By doing so, it is possible to suppress the traveling magnetic field that enters the hollow portion of the mold 100b over as wide a range as possible in the casting direction (Z-axis direction). In addition, the number of the magnetic field entry suppressing members 430a to 430b arranged in the region between the two molds 100a to 100b and 100b to 100c for realizing such suppression of the traveling magnetic field can be made one by one.

[0045] Further, in the present embodiment, as shown in FIG. 1, the Y-axis direction position (Y coordinate) Y1 of the end portion on the first core 410a side (the positive direction side of the Y axis) in the Y-axis direction of the magnetic field entry suppressing members 430a to 430b is the same as, or on the first core 410a side in the Y-axis direction than the Y-axis direction position (Y coordinate) Y2 of the end portion on the first core 410a side in the Y-axis direction of the hollow portion of the mold 100b (Y≧Y2). In addition to this, the Y-axis direction position (Y coordinate) Y3 of the end portion on the second core 410b side (the negative direction side of the Y axis) in the Y-axis direction of the magnetic field entry suppressing members 430a to 430b is the same as, or on the second core 410b side in the Y-axis direction than the Y-axis direction position (Y coordinate) Y4 of the end portion on the second core 410b side in the Y-axis direction of the hollow portion of the mold 100b (Y3≦Y4).

[0046] In this way, it is possible to suppress the traveling magnetic field that enters the hollow portion of the mold 100b as widely as possible in the Y-axis direction. Also, in order to achieve such suppression of the traveling magnetic field, the number of the magnetic field entry suppressing members 430a to 430b arranged in the regions between the two molds 100a to 100b and 100b to 100c can be made one by one.

[0047] Also, in the present embodiment, no magnetic field entry suppressing member is arranged at the positions on the outer sides (the negative direction side and the positive direction side of the X-axis) in the X-axis direction of the two molds 100a and 100c arranged at both ends in the X-axis direction. By doing so, it is possible to make it difficult to suppress the traveling magnetic field that enters the molds 100a and 100c. Therefore, the difference in the traveling magnetic field that enters the molds 100a to 100c can be made smaller (that is, the difference in the stirring force on the molten steel in the hollow portions of the molds 100a to 100c can be made smaller).

[0048] As described above, in the present embodiment, the magnetic field entry suppressing members 430a to 430b are formed using a conductive material, and it is preferable that the conductive material has a low electrical resistivity. This is because heat generation of the magnetic field entry suppressing members 430a to 430b due to eddy currents can be suppressed. As the conductive material constituting the magnetic field entry suppressing members 430a to 430b, for example, 10 -7Materials with an electrical resistivity of less than Ω·m may be used. Also, in this embodiment, the magnetic field entry suppression members 430a to 430b are made of a non-magnetic material so that a traveling magnetic field necessary for stirring the molten steel penetrates through the magnetic field entry suppression members 430a to 430b and a traveling magnetic field enters the hollow portion of the mold 100b. As such a non-magnetic material with a low electrical resistivity, for example, copper is used. It is preferable to configure the magnetic field entry suppression members 430a to 430b using a non-magnetic material in this way. However, it is not always necessary to configure the magnetic field entry suppression members 430a to 430b using a non-magnetic material. For example, the magnetic field entry suppression member may be configured using a ferromagnetic material (for example, iron). However, when the magnetic field entry suppression member is made of a ferromagnetic material, the magnetic field entry suppression member is not arranged at a position through which all the magnetic field lines directed toward (entering) the hollow portion of the mold 100b pass. This is because, if this is done, the traveling magnetic field will not enter the hollow portion of the mold 100b, and the molten steel in the hollow portion of the mold 100b cannot be stirred.

[0049] FIG. 4 is a diagram showing the stirring force ratios in the molds 100a to 100c of each strand. The inventive example represents the stirring force ratio when the magnetic field entry suppression members 430a to 430b are arranged as shown in FIGS. 1 to 2C. The comparative example represents the stirring force ratio when the magnetic field entry suppression members 430a to 430b are not arranged. Here, the stirring forces in the molds 100a to 100c were calculated by performing a computer simulation while differing only in the presence or absence of the magnetic field entry suppression member between the inventive example and the comparative example. As shown in FIG. 1, since the number of magnetic poles (= 2) of the electromagnetic stirring device is not a multiple of the number of strands (molds 100a to 100c) (= 3), the method described in Patent Document 1 cannot be applied to the configuration shown in FIG. 1.

[0050] In FIG. 4, 1st indicates the strand to which the mold 100a belongs, 2nd indicates the strand to which the mold 100b belongs, and 3rd indicates the strand to which the mold 100c belongs. The stirring force ratio is the stirring force when the stirring force on the molten steel in the hollow part of the mold 100a is expressed as 1. As shown in FIG. 4, in the inventive example where the magnetic field entry suppressing members 430a to 430b are arranged, it can be seen that the stirring force on the molten steel in the hollow part of the mold 100b can be reduced compared to the comparative example where the magnetic field entry suppressing members 430a to 430b are not arranged, and the difference in the stirring force on the molten steel in the hollow parts of the molds 100a to 100c can be reduced.

[0051] <Summary> As described above, in the present embodiment, the magnetic field entry suppressing members 430a to 430b are respectively arranged on both end faces in the X-axis direction of the back plate 200b (the end face on the positive X-axis side and the end face on the negative X-axis side). Therefore, without being restricted by the number of turns of the coils 420a to 420b, it is possible to make the stirring force on the molten steel for each of the molds 100a to 100c uniform. Also, it is not necessary to make the number of magnetic poles of the electromagnetic stirring device 400a a multiple of the number of strands (molds 100a to 100c). In addition, the production and installation of the magnetic field entry suppressing members 430a to 430b are easier than the production and installation of the coils 420a to 420c. Therefore, when continuously casting slabs in parallel in each of the plurality of molds 100a to 100c, it is possible to easily suppress the non-uniformity of the stirring force applied to the molten steel in each of the molds 100a to 100c.

[0052] <Modification Example> <<First Modification Example>> As described in this embodiment, among the regions between two adjacent molds 100a to 100b and 100b to 100c having a gap in the X-axis direction, it is preferable to arrange the magnetic field entry suppressing members 430a to 430b at the position closest to the center in the X-axis direction (the region between the molds 100a to 100b and 100b to 100c). This is because, as described in this embodiment, among the plurality of molds 100a to 100c, the magnetic flux density in the hollow portion of the mold 100b where the magnetic flux density of the moving magnetic field is the highest can be more surely reduced.

[0053] However, it is not necessarily required to be like this. FIG. 5 is a diagram showing a first modification of the arrangement of the magnetic field entry suppressing members. FIG. 5 is a diagram corresponding to FIG. 1 and is a cross-sectional view when the continuous casting facility is cut perpendicular to the casting direction (Z-axis direction). In the example shown in FIG. 5, the continuous casting facility includes molds 100d to 100g, back plates 200d to 200g, immersion nozzles 300d to 300g, and an electromagnetic stirring device 400b. The molds 100d to 100g are realized by the same ones as the molds 100a to 100c. The back plates 200d to 200g are realized by the same ones as the back plates 200a to 200c. The immersion nozzles 300d to 300g are realized by the same ones as the immersion nozzles 300a to 300c.

[0054] In FIG. 5, a case where four molds 100d to 100g are arranged in parallel at equal intervals in the X-axis direction is illustrated. The electromagnetic stirring device 400b includes a first core 410c, a second core 410d, a first coil 420c, a second coil 420d, magnetic field entry suppressing members 430c to 430f, and an AC power source (not shown). In FIG. 5, a case where the electromagnetic stirring device 400b is a three-pole (number of magnetic poles = 3) electromagnetic stirring device is illustrated.

[0055] The first core 410c, the second core 410d, the first coil 420c, and the second coil 420d are obtained by expanding the region in the X-axis direction so that a traveling magnetic field is generated with respect to the four molds 100d to 100g with respect to the first core 410a, the second core 410b, the first coil 420a, and the second coil 420b. Also in FIG. 5, similar to FIG. 1, +U, +V, +W, -U, -V, -W indicate coils to which alternating current of the +U phase, +V phase, +W phase, -U phase, -V phase, and -W phase is supplied, respectively.

[0056] In the example shown in FIG. 5, among the regions between two adjacent molds 100d to 100e, 100e to 100f, and 100f to 100g having an interval in the X-axis direction, the region closest to the center in the X-axis direction is the region between the molds 100e to 100f. Also, among the molds 100d to 100g arranged at equal intervals in the X-axis direction, the mold closest to the center in the X-axis direction is the molds 100e to 100f. Also, the molds at the end positions in the X-axis direction (of the electromagnetic stirring device 400b) are the molds 100d and 100g. Therefore, the magnetic field entry suppression members 430c to 430f are arranged at positions where the magnetic field lines of the traveling magnetic field toward the hollow portions of the molds 100e to 100f pass.

[0057] In the example shown in FIG. 5, the magnetic field entry suppressing members 430c to 430d are arranged at positions through which the magnetic field lines of the moving magnetic field directed toward the hollow portions of the molds 100e pass. Further, the magnetic field entry suppressing members 430e to 430f are arranged at positions through which the magnetic field lines of the moving magnetic field directed toward the hollow portions of the mold 100f pass. In this way, if the magnetic field entry suppressing members 430c to 430d and 430e to 430f are arranged on both sides in the X-axis direction of the molds 100e to 100f, which are the positions closest to the center in the X-axis direction, it is preferable because the magnetic flux density in the hollow portions of the molds 100e to 100f where the magnetic flux density of the moving magnetic field is the highest can be made lower. However, the magnetic field entry suppressing members 430c and 430f may be arranged without arranging the magnetic field entry suppressing members 430d to 430e. Conversely, the magnetic field entry suppressing members 430d to 430e may be arranged without arranging the magnetic field entry suppressing members 430c and 430f. For example, depending on the degree of reduction of the magnetic flux density in the hollow portions of the molds 100e to 100f where the magnetic flux density of the moving magnetic field is the highest, which of the magnetic field entry suppressing members 430c to 430f is to be used may be determined. Further, the thicknesses of the magnetic field entry suppressing members 430c to 430f may be made different depending on the degree of reduction of the magnetic flux density in the hollow portions of the molds 100e to 100f where the magnetic flux density of the moving magnetic field is the highest. In this way, in the example shown in FIG. 5, among the regions between two adjacent molds 100d to 100e, 100e to 100f, 100f to 100g having an interval in the X-axis direction, the magnetic field entry suppressing members 430d to 430e do not have to be arranged in the region closest to the center in the X-axis direction (the region between the molds 100e to 100f). Note that how the magnetic flux density in the hollow portion of the mold is can be determined based on, for example, the result of numerically simulating the operation of the continuous casting facility when an electromagnetic stirring device is applied.

[0058] In FIG. 5, the molds 100e, 100 f is , are the molds at the position closest to the center in the X-axis direction and are an example of the first mold. Further, the molds 100d and 100g are the molds adjacent to the first mold with an interval in the X-axis direction and are an example of the second mold.

[0059] Further, in FIG. 5, an example is illustrated where the magnetic field entry suppressing members 430c to 430f are realized by the same members as the magnetic field entry suppressing members 430a to 430b shown in FIGS. 1 to 2C. Also, as described above, examples are illustrated where the molds 100d to 100g, the back plates 200d to 200g, and the immersion nozzles 300d to 300g are also realized by the same members as the molds 100a to 100c, the back plates 200a to 200c, and the immersion nozzles 300a to 300c shown in FIGS. 1 to 2C. Further, as described above, the first core 410c, the second core 410d, the first coil 420c, and the second coil 420d are respectively the regions in the X-axis direction of the first core 410a, the second core 410b, the first coil 420a, and the second coil 420b expanded, and the Y-Z cross sections are the same. Therefore, the cross-sectional views taken along the line I-I and the line II-II, and the cross-sectional views taken along the line III-III and the line IV-IV in FIG. 5 are the same as FIGS. 2A and 2B, respectively (however, the reference numerals indicating the mold, the back plate, the immersion nozzle, the first core, the second core, the first coil, the second coil, and the magnetic field entry suppressing member are replaced with the reference numerals indicating the display objects in each cross-sectional view).

[0060] <<Second Modification Example>> In the present embodiment, an example is illustrated where a magnetic field entry suppressing member is not arranged at a position through which the magnetic force lines of the moving magnetic field that do not go toward the hollow portion of the mold 100b closest to the center in the X-axis direction pass. However, it is not necessarily required to be like this. In addition to the position through which the magnetic force lines of the moving magnetic field that go toward the hollow portion of the mold closest to the center in the X-axis direction pass, a magnetic field entry suppressing member may be arranged at a position through which the magnetic force lines of the moving magnetic field that go toward the hollow portions of other molds (without going toward the hollow portion of the mold) pass.

[0061] FIG. 6 is a diagram showing a second modification example of the arrangement of the magnetic field entry suppressing members. FIG. 6 is a diagram corresponding to FIG. 1 and is a cross-sectional view when the continuous casting facility is cut perpendicular to the casting direction (Z-axis direction). In the example shown in FIG. 6, the continuous casting facility includes molds 100h to 100l, back plates 200h to 200l, immersion nozzles 300h to 300l, and an electromagnetic stirring device 400c. The molds 100h to 100l are realized as the same ones as molds 100a to 100c. The back plates 200h to 200l are realized as the same ones as back plates 200a to 200c. The immersion nozzles 300h to 300l are realized as the same ones as immersion nozzles 300a to 300c.

[0062] In FIG. 6, an example is illustrated in which five molds 100h to 100l are arranged in parallel at equal intervals in the X-axis direction. The electromagnetic stirring device 400c includes a first core 410e, a second core 410f, a first coil 420e, a second coil 420f, magnetic field entry suppression members 430g to 430l, and an AC power source (not shown). In FIG. 6, an example is illustrated in which the electromagnetic stirring device 400c is a four-pole (number of magnetic poles = 4) electromagnetic stirring device.

[0063] The first core 410e, the second core 410f, the first coil 420e, and the second coil 420f are obtained by expanding the region in the X-axis direction so that a traveling magnetic field is generated with respect to the five molds 100h to 100l, as compared with the first core 410a, the second core 410b, the first coil 420a, and the second coil 420b. Also in FIG. 6, similar to FIG. 1, +U, +V, +W, -U, -V, -W indicate coils to which AC currents of the +U phase, +V phase, +W phase, -U phase, -V phase, and -W phase are supplied, respectively.

[0064] In the example shown in FIG. 6, among the regions between two adjacent molds 100h to 100i, 100i to 100j, 100j to 100k, and 100k to 100l having intervals in the X-axis direction, the regions closest to the center in the X-axis direction are the regions between molds 100i to 100j and the regions between molds 100j to 100k. Also, among the molds 100h to 100l arranged at equal intervals in the X-axis direction, the mold closest to the center in the X-axis direction is mold 100j. Further, the molds at the end positions in the X-axis direction (of the electromagnetic stirring device 400c) are molds 100h and 100l. Therefore, the magnetic field entry suppression members 430i to 430j are arranged at positions where the magnetic field lines of the moving magnetic field passing toward the hollow portion of mold 100j pass.

[0065] Also, the magnetic flux density in the hollow portions of molds 100i and 100k, which are between mold 00j, which is closest to the center in the X-axis direction, and molds 100h and 100l, which are at the end positions in the X-axis direction, is lower compared to the magnetic flux density in the hollow portion of mold 100j, but higher compared to the magnetic flux density in the hollow portions of molds 100h and 100l. Therefore, the magnetic field entry suppression members 430g to 430h and 430k to 430l are respectively arranged at positions where the magnetic field lines of the moving magnetic field passing toward the hollow portions of molds 100 type 1 、100 i 、100 k pass.

[0066] Alternatively, the magnetic field entry suppression member 430h may be arranged without arranging the magnetic field entry suppression member 430g. Conversely, the magnetic field entry suppression member 430g may be arranged without arranging the magnetic field entry suppression member 430h. Similarly, the magnetic field entry suppression member 430l may be arranged without arranging the magnetic field entry suppression member 430k, or the magnetic field entry suppression member 430k may be arranged without arranging the magnetic field entry suppression member 430l. Depending on the degree to which the magnetic flux density in the hollow portion of the mold 100j where the magnetic flux density of the moving magnetic field is highest and the magnetic flux density in the hollow portions of the molds 100i and 100k where the magnetic flux density of the moving magnetic field is next highest are reduced, it is only necessary to determine which of the magnetic field entry suppression members 430g to 430l to use. Also, depending on the degree to which the magnetic flux density in the hollow portion of the mold 100j where the magnetic flux density of the moving magnetic field is highest and the magnetic flux density in the hollow portions of the molds 100i and 100k where the magnetic flux density of the moving magnetic field is next highest are reduced, the thicknesses of the magnetic field entry suppression members 430g to 430l may be made different. Thus, in the example shown in FIG. 6, among the two adjacent molds 100h to 100i, 100i to 100j, 100j to 100k, and 100k to 100l having an interval in the X-axis direction, the magnetic field entry suppression members 430g and 430l may be arranged at positions where the moving magnetic field directed toward the hollow portions of the other molds 100i and 100k passes without passing through the hollow portion of the mold 100j located closest to the center in the X-axis direction.

[0067] In addition, in FIG. 6, the mold 100j is a mold located closest to the center in the X-axis direction and is an example of the first mold. Also, the molds 100i and 100k are molds adjacent to the first mold with an interval in the X-axis direction and are examples of the second mold.

[0068] In FIG. 6, a case is illustrated where the magnetic field entry suppression members 430g to 430l are realized by the same members as the magnetic field entry suppression members 430a to 430b shown in FIGS. 1 to 2C. Further, as described above, a case is illustrated where the molds 100h to 100l, the back plates 200h to 200l, and the immersion nozzles 300h to 300l are also realized by the same members as the molds 100a to 100c, the back plates 200a to 200c, and the immersion nozzles 300a to 300c shown in FIGS. 1 to 2C. Furthermore, as described above, the first core 410e, the second core 410f, the first coil 420e, and the second coil 420f are obtained by expanding the regions in the X-axis direction of the first core 410a, the second core 410b, the first coil 420a, and the second coil 420b, respectively, and the Y-Z cross sections are the same. Therefore, the cross-sectional views taken along the I-I arrow, II-II arrow, and III-III arrow in FIG. 6 are the same as those in FIG. 2A, and the cross-sectional views taken along the IV-IV arrow, V-V arrow, and VI-VI arrow in FIG. 6 are the same as those in FIG. 2B (however, the reference numerals indicating the mold, the back plate, the immersion nozzle, the first core, the second core, the first coil, the second coil, and the magnetic field entry suppression member are replaced with the reference numerals indicating the objects to be displayed in each cross-sectional view).

[0069] <<Third Modified Example>> In the present embodiment, a case is illustrated where the magnetic field entry suppression members 430a to 430b are respectively arranged so as to contact both end faces in the X-axis direction of the back plate 200b (the end face on the positive direction side of the X-axis and the end face on the negative direction side of the X-axis). However, it is not always necessary to do so as long as the magnetic field entry suppression member is arranged at a position where the magnetic field lines of the moving magnetic field passing through the hollow portion of the mold to be suppressed from entering the moving magnetic field pass.

[0070] FIG. 7 is a diagram showing a third modification of the arrangement of the magnetic field entry suppressing members. Here, as an example, the case is illustrated where the magnetic field entry suppressing members 430a to 430b of the electromagnetic stirring device 400a shown in FIGS. 1 to 2C are changed to the magnetic field entry suppressing members 430m to 430n shown in FIG. 7 (in this modification, the configuration of the electromagnetic stirring device 400d other than the magnetic field entry suppressing members 430m to 430n is the same as the configuration of the electromagnetic stirring device 400a shown in FIGS. 1 to 2C). FIG. 7 is a diagram corresponding to FIG. 1 and is a cross-sectional view when the continuous casting facility is cut perpendicular to the casting direction (Z-axis direction). As shown in FIG. 7, the magnetic field entry suppressing members 430m to 430n may be arranged in the region between two adjacent molds 100a to 100b and 100b to 100c that are spaced apart in the X-axis direction so as not to contact the molds 100a to 100c.

[0071] From the viewpoint of further suppressing the traveling magnetic field entering the hollow portion of the mold 100b, in the region between two adjacent molds 100a to 100b and 100b to 100c that are spaced apart in the X-axis direction, the magnetic field entry suppressing members 430m to 430n are arranged in the region from the center position of the region in the X-axis direction to the end face of the mold 100b in the X-axis direction. Further, in the region between two adjacent molds 100a to 100b and 100b to 100c that are spaced apart in the X-axis direction, it is more preferable to arrange the magnetic field entry suppressing members 430m to 430n at a position closer to the mold 100b than the center position of the region in the X-axis direction.

[0072] Note that, as in FIG. 1, in FIG. 7, the mold 100b is the mold closest to the center in the X-axis direction and is an example of the first mold. Also, the molds 100a and 100c are molds adjacent to the first mold with a space in the X-axis direction and are examples of the second mold.

[0073] The X-axis positions of the magnetic field entry suppression members 430m to 430n may be determined according to the degree of reducing the magnetic flux density in the hollow portion of the mold 100b. Further, the thicknesses of the magnetic field entry suppression members 430m to 430n may be made different according to the degree of reducing the magnetic flux density in the hollow portion of the mold 100b where the magnetic flux density of the moving magnetic field is the highest. Further, the magnetic field entry suppression members 430m to 430n may be attached to, for example, a structure (not shown) provided in the electromagnetic stirring device 400a (for example, a cooling box installed to cool the electromagnetic stirring device) or a structure of an existing continuous casting facility. Note that the cross-sectional views taken along the line I-I and II-II in FIG. 7 are the same as those in FIGS. 2A and 2B, respectively (however, the reference signs indicating the magnetic field entry suppression members are replaced with the reference signs indicating the display targets in each cross-sectional view).

[0074] <<Fourth Modified Example>> In the present embodiment, the case where the number of the magnetic field entry suppression members 430a to 430b arranged in the regions between the two molds 100a to 100b and 100b to 100c is one each is illustrated. However, the number of the magnetic field entry suppression members arranged in the regions between the two molds 100a to 100b and 100b to 100c may be two or more.

[0075] Figures 8A to 8C are diagrams showing a fourth modification of the arrangement of the magnetic field entry suppression members. Figure 8A is a diagram corresponding to Figure 1 and is a cross-sectional view when the continuous casting facility is cut perpendicular to the casting direction (Z-axis direction). Figures 8B and 8C are cross-sectional views taken along the line I-I and the line II-II of Figure 8, respectively, and are diagrams corresponding to Figures 2A and 2B. In the electromagnetic stirring device 400e of this modification shown in Figures 8A to 8C, two magnetic field entry suppression members 430o to 430p are arranged in a region between two adjacent molds 100a to 100b having a gap in the X-axis direction so as not to contact the molds 100a to 100b, and two magnetic field entry suppression members 430q to 430r are arranged in a region between two adjacent molds 100b to 100c having a gap in the X-axis direction so as not to contact the molds 100c to 100c. This case is illustrated. In such a case, the traveling magnetic field can enter the hollow portion of the mold 100b from the region between the two magnetic field entry suppression members 430o to 430p and 430q to 430r. The size of the region between the magnetic field entry suppression members 430o to 430p and 430q to 430r may be determined, for example, according to the degree of reducing the magnetic flux density in the hollow portion of the mold 100b where the magnetic flux density of the traveling magnetic field is the highest. Further, it is preferable that the central position in the Y-axis direction of the region between the magnetic field entry suppression members 430o to 430p is the same as the central position in the Y-axis direction of the mold 100b. Similarly, it is preferable that the central position in the Y-axis direction of the region between the magnetic field entry suppression members 430q to 430r is the same as the central position in the Y-axis direction of the mold 100b. By doing so, the distribution of the magnetic flux generated in the first core 410a and the second core 410b can be made uniform on the positive direction side and the negative direction side of the Y-axis in the molds 100a to 100c, and the effect of suppressing the non-uniformity of the stirring force applied to the molten steel in the molds 100a to 100c when the magnetic field entry suppression members 430o to 430p and 430q to 430r are divided in the Y-axis direction can be enhanced.

[0076] Note that the positions and thicknesses of the magnetic field entry suppression members 430o to 430p and 430q to 430r in the X-axis direction may be determined as described in the present embodiment and the third modification example. Also, similar to the present embodiment, two magnetic field entry suppression members 430o to 430p may be arranged so as to contact the end face on the negative direction side in the X-axis direction of the back plate 200b, and two magnetic field entry suppression members 430q to 430r may be arranged so as to contact the end face on the positive direction side in the X-axis direction of the back plate 200b. Further, in FIGS. 8A to 8C, the case where the magnetic field entry suppression members 430o to 430p and 430q to 430r are divided into two in the Y-axis direction is illustrated, but the magnetic field entry suppression members may be divided into three or more and arranged. In such a case, it is preferable to arrange the magnetic field entry suppression members evenly in the Y-axis direction (arrange the magnetic field entry suppression members having the same length in the Y-axis direction at equal intervals). Further, in FIGS. 8A to 8C, the case where the magnetic field entry suppression members 430o to 430p and 430q to 430r are divided into a plurality in the Y-axis direction is illustrated, but instead of or in addition to doing so, the magnetic field entry suppression members may be divided into a plurality (two or three or more) in the Z-axis direction.

[0077] <<Fifth Modification Example>> In the present embodiment, the case where the magnetic field entry suppression members 430a to 430b are arranged to be axially symmetric with an axis extending in a direction parallel to the Y-axis direction passing through the position of the center of gravity of the hollow portion of the mold 100b as the axis of symmetry is illustrated. However, it is not always necessary to do so. FIGS. 9A to 9C are views showing a fifth modification example of the arrangement of the magnetic field entry suppression members. FIG. 9A is a view corresponding to FIG. 1 and is a cross-sectional view when the continuous casting facility is cut perpendicular to the casting direction (Z-axis direction). FIGS. 9B and 9C are cross-sectional views taken along the line I-I and the line II-II of FIG. 9, respectively, and are views corresponding to FIGS. 2A and 2B. In the electromagnetic stirring device 400f of the present modification example shown in FIGS. 9A to 9C, a magnetic field entry suppression member 430s is arranged in a region between two adjacent molds 100a to 100b having a gap in the X-axis direction so as not to contact the molds 100a to 100b, and a magnetic field entry suppression member 430r is arranged in a region between two adjacent molds 100b to 100c having a gap in the X-axis direction so as not to contact the molds 100c to 100c.

[0078] In FIG. 9A, an example is illustrated in which the Y-axis direction position (Y coordinate) Y5 of the end portion of the magnetic field entry suppression member 430s on the first core 410a side (positive direction side of the Y-axis) in the Y-axis direction is located on the second core 410b side (negative direction side of the Y-axis) rather than the Y-axis direction position (Y coordinate) Y6 of the end portion of the magnetic field entry suppression member 430t on the first core 410a side (positive direction side of the Y-axis) in the Y-axis direction (Y5 < Y6). Further, an example is illustrated in which the Y-axis direction position (Y coordinate) Y7 of the end portion of the magnetic field entry suppression member 430t on the second core 410b side (negative direction side of the Y-axis) in the Y-axis direction is located on the first core 410a side (positive direction side of the Y-axis) rather than the Y-axis direction position (Y coordinate) Y8 of the end portion of the magnetic field entry suppression member 430t on the second core 410b side (negative direction side of the Y-axis) in the Y-axis direction (Y7 > Y8). The positions of the end portions of the magnetic field entry suppression members 430s to 430t in the Y-axis direction may be determined, for example, according to the degree of reducing the magnetic flux density in the hollow portion of the mold 100b where the magnetic flux density of the moving magnetic field is the highest.

[0079] Note that the positions and thicknesses of the magnetic field entry suppression members 430s to 430t in the X-axis direction may be determined as described in the present embodiment and the third modification example. Further, as in the present embodiment, the magnetic field entry suppression member 430s may be arranged so as to contact the end surface on the negative direction side in the X-axis direction of the back plate 200b, and the magnetic field entry suppression member 430t may be arranged so as to contact the end surface on the positive direction side in the X-axis direction of the back plate 200b.

[0080] <<Sixth Modification Example>> In this embodiment, an example is given where the casting direction position (Z coordinate) Z1 of the end portion on the upstream side (positive direction side of the Z axis) in the casting direction of the magnetic field entry suppressing members 430a to 430b is set to be upstream in the casting direction from the casting direction position (Z coordinate) Z2 of the end portion on the upstream side in the casting direction of the first core 410a and the second core 410b (refer to Z1 > Z2 in FIGS. 2A and 2B). In addition to this, an example is given where the casting direction position (Z coordinate) Z3 of the end portion on the downstream side (negative direction side of the Z axis) in the casting direction of the magnetic field entry suppressing members 430a to 430b is set to be downstream in the casting direction from the casting direction position (Z coordinate) Z4 of the end portion on the downstream side in the casting direction of the first core 410a and the second core 410b (refer to Z3 < Z4 in FIGS. 2A and 2B).

[0081] However, for example, depending on the degree of reducing the magnetic flux density in the hollow portion of the mold 100b where the magnetic flux density of the moving magnetic field is the highest, it is not always necessary to do so. The end portion on the upstream side (positive direction side of the Z axis) in the casting direction of the magnetic field entry suppressing members 430a to 430b may be set to be downstream in the casting direction from the end portion on the upstream side in the casting direction of the first core 410a and the second core 410b. That is, the magnitude relationship between Z1 and Z2 in FIGS. 2A and 2B may be reversed from the relationship shown in FIGS. 2A and 2B. In addition to or instead of this, the end portion on the downstream side (negative direction side of the Z axis) in the casting direction of the magnetic field entry suppressing members 430a to 430b may be set to be upstream in the casting direction from the end portion on the downstream side in the casting direction of the first core 410a and the second core 410b. That is, the magnitude relationship between Z3 and Z4 in FIGS. 2A and 2B may be reversed from the relationship shown in FIGS. 2A and 2B.

[0082] The above also applies to the ends of the magnetic field entry suppressing members 430a to 430b in the Y-axis direction. That is, the ends of the magnetic field entry suppressing members 430a to 430b on the first core 410a side (the positive Y-axis direction side) in the Y-axis direction may be made to be on the second core 410b side (the negative Y-axis direction side) in the Y-axis direction of the hollow portion of the mold 100b, rather than on the first core 410a side of the hollow portion of the mold 100b in the Y-axis direction. That is, in FIG. 1, the magnitude relationship between Y1 and Y2 may be reversed from the relationship shown in FIG. 1. In addition to or instead of doing so, the ends of the magnetic field entry suppressing members 430a to 430b on the second core 410b side (the negative Y-axis direction side) in the Y-axis direction may be made to be on the first core 410a side (the positive Y-axis direction side) in the Y-axis direction of the hollow portion of the mold 100b, rather than on the second core 410b side of the hollow portion of the mold 100b in the Y-axis direction. That is, in FIG. 1, the magnitude relationship between Y3 and Y4 may be reversed from the relationship shown in FIG. 1. Even if each of the above-described modifications is made, the traveling magnetic field entering the hollow portion of the mold 100b can be suppressed as compared with the case where the magnetic field entry suppressing member is not arranged.

[0083] <<Seventh Modification>> As described so far, it is preferable to arrange the magnetic field entry suppressing members 430a to 430b in the region between two adjacent molds 100a to 100b, 100b to 100c having a gap in the X-axis direction. This is because it is easy and certain to ensure the stirring force required for stirring the molten steel in the hollow portions of the molds 100a to 100c as described above. However, taking the configurations illustrated in FIGS. 1 to 2C as an example, the magnetic field entry suppressing member does not necessarily need to be arranged in the region between two adjacent molds 100a to 100b, 100b to 100c having a gap in the X-axis direction, as long as it is arranged at a position where the magnetic field lines of the traveling magnetic field directed toward the hollow portion of at least the mold 100b pass through. For example, even if the distance between the electromagnetic stirring device 400a (the first core 410a and the second core 410b) and the molds 100a to 100c is large, if it is possible to ensure the stirring force for the molten steel in the hollow portions of the molds 100a to 100c, the magnetic field entry suppressing member may be arranged in the region between the first core 410a and the mold 100b or in the region between the second core 410b and the mold 100b.

[0084] As described above, the size, thickness, number, and position of the magnetic field entry suppression member are determined so that both the difference in the stirring force on the molten steel in the hollow portions of three or more molds arranged in parallel in the X-axis direction becomes equal to or less than a desired value and the stirring force on the molten steel in the hollow portions of the molds becomes equal to or more than a desired value, and are not limited to the magnetic field entry suppression members 430a to 430b described in this embodiment. Also, including the modified examples described in the main text of this embodiment, some or all (at least two modified examples) of the above-described modified examples may be combined.

[0085] Note that the embodiments of the present invention described above are merely examples of implementation when implementing the present invention, and the technical scope of the present invention should not be construed as being limited thereby. That is, the present invention can be implemented in various forms without departing from its technical idea or its main features.

Explanation of Reference Numerals

[0086] 100a to 100l molds 200a to 200l back plates 300a to 300l immersion nozzles 310 discharge port 400a to 400f electromagnetic stirring devices 410a, 410c, 410e first cores 410b, 410d, 410f second cores 420a, 420c, 420e first coils 420b, 420d, 420f second coils 430a to 430l magnetic field entry suppression members

Claims

1. A first core and a second core arranged to face each other in the depth direction via three or more plurality of molds arranged in parallel in the width direction with intervals therebetween; A first coil wound around the first core; A second coil wound around the second core; Comprising; An electromagnetic stirring device for electromagnetic stirring of the molten metal continuously cast by generating a moving magnetic field in opposite directions with respect to the molten metal injected into the hollow portion of the mold based on the alternating current flowing through the first coil and the second coil, A magnetic field entry suppressing member made of a conductive material through which the moving magnetic field penetrates, or a magnetic field entry suppressing member made of a conductive material through which the moving magnetic field does not penetrate; When the magnetic field entry suppressing member is made of a material through which the moving magnetic field penetrates, the magnetic field entry suppressing member is disposed at a position where the magnetic field lines of the moving magnetic field directed toward the hollow portion of at least the first mold among the plurality of molds pass; When the magnetic field entry suppressing member is made of a material through which the moving magnetic field does not penetrate, the magnetic field entry suppressing member is disposed at a position where only a part of the magnetic field lines of all the magnetic field lines of the moving magnetic field directed toward the hollow portion of at least the first mold among the plurality of molds pass; The first mold is the mold located closest to the center in the width direction among the plurality of molds, an electromagnetic stirring device.

2. The magnetic field entry suppressing member, The electromagnetic stirring device according to claim 1, which is configured using a non-magnetic and conductive material as the material through which the moving magnetic field penetrates.

3. The magnetic field entry suppressing member, The electromagnetic stirring device according to claim 1 or 2, which is disposed in a region between the first mold and a second mold which is adjacent to the first mold with an interval in the width direction.

4. The magnetic field entry suppressing member, The electromagnetic stirring device according to claim 3, which is disposed at a position closer to the first mold than the second mold.

5. The position in the casting direction of the upstream end of the magnetic field entry suppressing member in the casting direction, Is the same as, or upstream of, in the casting direction, the position in the casting direction of the upstream end of the first core and the second core in the casting direction, and, The position in the casting direction of the downstream end of the magnetic field entry suppressing member in the casting direction, The electromagnetic stirring device according to any one of claims 1 to 4, wherein an end portion on the downstream side in the casting direction of the first core and the second core is located at the same position as, or on the downstream side in the casting direction of, the position in the casting direction.

6. The position in the depth direction of the end portion on the first core side of the magnetic field entry suppressing member in the depth direction is the same as the position in the depth direction of the end portion on the first core side of the hollow portion of the mold in the depth direction, or is located at a position closer to the first core side than that position, The position in the depth direction of the end portion on the second core side of the magnetic field entry suppressing member in the depth direction is the same as the position in the depth direction of the end portion on the second core side of the hollow portion of the mold in the depth direction, or is located at a position closer to the second core side than that position. The electromagnetic stirring device according to any one of claims 1 to 5.

7. The magnetic field entry suppressing member is plate-shaped. The electromagnetic stirring device according to any one of claims 1 to 6.

8. The magnetic field entry suppressing member is arranged in a state of being in contact with the mold or a structure connected to the mold. The electromagnetic stirring device according to any one of claims 1 to 7.

9. The magnetic field entry suppressing member is not arranged at a position outside the mold located at the end in the width direction in the width direction. The electromagnetic stirring device according to any one of claims 1 to 8.

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