JP2021109197A - Electromagnetic agitation device - Google Patents

Abstract

To restrict interaction between a discharge flow and an agitation flow, even when a position in a casting direction of a discharge port of an immersion nozzle and a position in a casting direction of the electromagnetic agitation device overlap.SOLUTION: Iron cores 241, 242 are constituted to include a second region where a casting width direction (an X-axis direction) is a longer direction and a first region where the length in the casting width direction is shorter than that in the second region. A range in the casting width direction of the second region contains a range in the casting width direction of the first region. A range in the casting width direction (the X-axis direction) of the first region contains a range in a casting width direction of an immersion nozzle 230. A range where a range in a casting direction (a Z-axis direction) of the second region overlaps with a range in a casting direction in which a discharge flow from discharge ports 230a, 230b of the immersion nozzle 230 flows is shorter than a range where a range in a casting direction of the first region overlaps with the range in the casting direction in which the discharge flow from the discharge ports 230a, 230b of the immersion nozzle 230 flows.SELECTED DRAWING: Figure 6

Description

The present invention relates to an electromagnetic agitator and is particularly suitable for use in continuous casting of slabs.

When continuously casting slabs and other slabs, the molten metal supplied from the ladle to the tundish is injected into the hollow portion of the mold (the area surrounded by the mold) by the immersion nozzle.
There is an electromagnetic brake as a device for improving the quality of slabs. As described in Patent Document 1, an electromagnetic brake uses a DC magnetic field (static magnetic field) by passing an electric current through a set of electromagnet coils arranged so as to face each other via a long side portion of a mold. By applying it to the molten metal in the hollow portion of, the downward flow velocity of the molten metal is reduced. The technique described in Patent Document 1 is a technique for solving a problem in the case of discharging molten metal from a dipping nozzle in the casting direction (vertically downward) (when a straight dipping nozzle is used).

In addition to such an electromagnetic brake, there is an electromagnetic agitator as a device for improving the quality of slabs. The electromagnetic agitator applies an alternating magnetic field to the molten metal in the hollow portion of the mold by passing an electric current through the coils of a set of electromagnets arranged so as to face each other via the long sides of the mold. The molten metal is electromagnetically agitated by applying a stirring force that orbits the metal in a horizontal plane. As described above, the electromagnetic brake and the electromagnetic agitator both control the flow of the molten metal, but their functions are different.

As a technique relating to the electromagnetic agitator, there is a technique described in Patent Documents 2 to 4.
Patent Document 2 describes that the electromagnetic agitator is arranged so that the position of the upper end of the discharge port of the immersion nozzle is lower than the position of the lower end of the electromagnetic agitator. Further, Patent Document 2 describes that a magnetic shielding plate is provided below the electromagnetic stirring device. The magnetic shielding plate is intended to suppress the turbulence of the flow of molten metal in the hollow portion of the mold due to the magnetic field generated by the electromagnetic agitator.

Patent Document 3 describes that the distance between the iron core of the electromagnetic agitator and the mold is maximized in the central portion of the iron core in the casting direction.

In Patent Document 4, the iron core of the electromagnetic stirrer is a plurality of salient poles arranged at intervals in the direction parallel to the long side portion of the mold, and the tip surface has an interval from the long side portion of the mold. It is described that a plurality of salient poles arranged so as to face each other are provided at the upper and lower sides in the casting direction. Further, Patent Document 4 describes that a coil is wound around each of the salient poles of the iron core.

Japanese Patent No. 2888312 Japanese Patent No. 5073531 Japanese Unexamined Patent Publication No. 2008-173644 JP-A-11-156502 Japanese Patent No. 5335883

However, in the techniques described in Patent Documents 2 to 4, the positional relationship between the immersion nozzle and the electromagnetic agitator is considered when the position of the discharge port of the immersion nozzle in the casting direction and the position of the electromagnetic agitator in the casting direction overlap. Not done.

Further, in the technique described in Patent Document 2, interference between the flow of molten metal (discharge flow) discharged from the immersion nozzle and the flow of molten metal (stirring flow) due to the stirring force applied to the molten metal by the electromagnetic agitator. This technology is based on the premise that the position of the upper end of the discharge port is lower than the position of the lower end of the electromagnetic agitator. Therefore, the technique described in Patent Document 2 cannot control the flow of the molten metal below the upper end of the discharge port at all. In addition, a magnetic shielding plate must be placed inside the mold. Therefore, it is necessary to secure a place for arranging the magnetic shielding plate as well as cost for arranging the magnetic shielding plate.

Further, in the technique described in Patent Document 3, the magnetic flux density distribution of the molten metal in the hollow portion of the mold is flattened, and the distribution of the magnetic flux density in the casting direction is made uniform. Therefore, the distribution of the stirring force applied to the molten metal in the hollow portion of the mold in the casting direction is also made uniform. Therefore, it is not easy to suppress the interference between the discharge flow and the stirring flow.

Further, the technique described in Patent Document 4 is a technique for realizing the function of the electromagnetic brake device and the function of the electromagnetic stirring device with one device. Therefore, the coil must be wound around the salient pole of the mold in a direction perpendicular to the surface of the long side of the mold. Therefore, the space for arranging the coil is limited. Further, the region of the alternating magnetic field generated by the current flowing through the coil is limited to the upper and lower regions in the casting direction. Therefore, the range in which the stirring flow can be controlled is limited.

The present invention has been made in view of the above problems, and even when the position of the discharge port of the immersion nozzle in the casting direction and the position of the electromagnetic stirrer in the casting direction overlap, the discharge flow and the stirring flow The purpose is to be able to suppress interference with.

In the electromagnetic agitator of the present invention, the first iron core and the second iron core arranged at positions facing each other via the long side portion of the mold, and the casting width direction of the mold with respect to the first iron core. The first coil and the second coil, which have a first coil wound around the second coil and a second coil wound around the second iron core in the casting width direction of the mold. By generating a traveling magnetic field based on the AC current flowing through the coil in the casting width direction, the molten metal injected into the hollow portion of the mold is electromagnetically agitated from the discharge port of the immersion nozzle toward the short side of the mold. In the electromagnetic agitator, the first iron core and the second iron core each have a first region and a second region in which the position in the casting direction is different from that of the first region. The range in the casting width direction of the first region includes the range in the casting width direction of the immersion nozzle, and the length of the first region in the casting width direction is the casting width direction of the second region. The range in the casting width direction of the second region, which is shorter than the length of the second region, includes the range in the casting width direction of the first region, the range in the casting direction of the second region, and the immersion nozzle. The range in which the discharge flow, which is the flow of molten metal from the discharge port of the mold to the short side of the mold, overlaps with the casting direction range of the first region is the casting direction range of the first region and the discharge. It is characterized in that the range in the casting direction in which the flow flows is shorter than the overlapping range.

According to the present invention, it is possible to suppress the interference between the discharge flow and the stirring flow even when the position of the discharge port of the immersion nozzle in the casting direction and the position of the electromagnetic stirrer in the casting direction overlap.

It is a figure explaining an example of the flow of molten steel in a general electromagnetic agitator. It is sectional drawing at the 1st position which shows 1st example of the schematic structure of the continuous casting facility. It is sectional drawing at the 2nd position which shows the 1st example of the schematic structure of the continuous casting facility. It is a vertical sectional view at the 1st position which shows 1st example of the schematic structure of the continuous casting facility. It is a vertical cross-sectional view at a second position which shows the 1st example of the schematic structure of the continuous casting facility. It is a figure which shows an example of the structure of the immersion nozzle. It is a figure which shows the 1st example of the structure of an iron core. It is a figure explaining the 1st example of the flow of molten steel. It is a figure which shows the 1st example of the relationship between a stirring force and a position in a casting width direction. It is a figure which shows the modification of the 1st example of the structure of an iron core. It is a vertical sectional view at the 1st position which shows the 2nd example of the schematic structure of the continuous casting facility. It is a vertical sectional view at a second position which shows the 2nd example of the schematic structure of the continuous casting facility. It is a figure which shows the 2nd example of the structure of an iron core. It is a figure explaining the 2nd example of the flow of molten steel. It is a figure which shows the 2nd example of the relationship between a stirring force and a position in a casting width direction. It is a figure which shows the modification of the 2nd example of the structure of an iron core.

(background)
First, the background to the embodiment of the present invention will be described.

FIG. 1 is a diagram illustrating an example of a flow of molten steel in a general electromagnetic agitator. The XYZ coordinates shown in each figure indicate the relationship of orientation in each figure. Symbols with a cross in 〇 indicate the direction from the front side to the back side of the paper. The symbol with ● in 〇 indicates the direction from the back side to the front side of the paper. In the following description, a case where the molten metal is molten steel will be described as an example.

In FIG. 1, the figure on the left side when the paper surface is viewed with the positive direction of the Z axis as the upward direction (the figure showing the XYZ coordinates with the direction perpendicular to the paper surface as the X axis) is a short mold. It is a figure which conceptually shows an example of the discharge flow and the agitation flow when viewed from the side. In the figure on the left side of FIG. 1, the arrow line indicates the discharge flow at time t, and the symbol with x in 〇 and the symbol with ● in 〇 indicate the stirring flow at time t. ..

Further, in FIG. 1, the figure on the right side when the paper surface is viewed with the positive direction of the Z axis as the upward direction (the figure showing the XYZ coordinates with the direction perpendicular to the paper surface as the Y axis) is a template. It is a figure which conceptually shows an example of the discharge flow and the agitation flow when viewed from the long side portion side of the above. In the figure on the right side of FIG. 1, the solid arrow line indicates the discharge flow at time t, and the white arrow line indicates the stirring flow at time t. The longer the arrow line, the faster the flow velocity. In addition, the size of the circle of the symbol with ● in 〇 and the symbol with × in 〇 in the molten steel M indicates the flow velocity of the molten steel M. In the figure on the left side of FIG. 1, since the size of the circle is the same, it is shown that the flow velocities are the same. In the figure on the right side of FIG. 1, only a half region in the casting width direction (X-axis direction) of the mold is shown.

The electromagnetic agitator has iron cores 110 and 120 and coils 130 and 140.
When operating the electromagnetic stirrer, for example, by passing a three-phase alternating current through the coils 130 and 140, the casting width direction is relative to the molten steel M in the region on the end side in the casting thickness direction (Y-axis direction). A traveling magnetic field opposite to each other is generated along (X-axis direction). This traveling magnetic field causes eddy currents in the molten steel M according to Faraday's law and Lenz's law. This eddy current and the traveling magnetic field form a stirring force in the molten steel M based on Fleming's left-hand rule. This stirring force generates a stirring flow (flow of molten steel M) that orbits along the inner wall surface of a set of long side portions 151, 152 and a set of short side portions 153 of the mold in a horizontal plane. Although not shown in FIG. 1, a short side portion having the same configuration as the short side portion 153 is provided so as to be line-symmetric with respect to the short side portion 153 with the axis A of the mold as the axis of symmetry separately from the short side portion 153. Is placed. The electromagnetic agitator prevents air bubbles and foreign substances (inclusions, etc.) from adhering to the surface of the slab continuously cast by the continuous casting facility and remaining in the slab due to such a stirring flow. That is, the electromagnetic agitator is a device for the purpose of improving the quality of the slab surface.

As shown in the figure on the left side of FIG. 1, in a general electromagnetic agitator, the surfaces of the iron cores 110 and 120 of the electromagnetic agitator facing the long sides 151 and 152 of the mold at intervals are in the casting direction ( It is parallel to the Z-axis direction), and the distance between the iron cores 110 and 120 and the long side portions 151 and 152 of the mold is constant. Back plates 161 and 162 are arranged on the back surfaces of the long side portions 151 and 152 of the mold (the surface opposite to the surface located on the molten steel M side) for supporting and cooling the mold. The back plate 163 is also arranged on the back surface of the short side portion 153 of the mold.

Here, a case where the molten steel M discharged from the discharge port 170a of the immersion nozzle 170 is adjusted so that the upper ends of the iron cores 110 and 120 coincide with the molten steel surface (meniscus) of the molten steel M is shown as an example. Further, here, a case where the discharge angle of the discharge port 170a of the immersion nozzle 170 is determined so that the molten steel M is discharged diagonally downward is shown as an example. Here, the discharge flow refers to the flow of the molten steel M discharged from the discharge port 170a of the immersion nozzle 170 before turning into an ascending flow or a descending flow.

In this case, in the region in the hollow portion of the mold from the position of the upper end to the position of the lower end of the iron cores 110 and 120 in the casting direction (Z-axis direction), the stirring force applied to the molten steel M from the electromagnetic stirrer is about the same. Become. Therefore, the flow velocity of the agitated flow is also about the same (see that the lengths of the white arrow lines in the figure on the right side of FIG. 1 are the same). Therefore, in the region where the discharge flow flows, the flow velocity of the molten steel M increases as the stirring flow is added to the discharge flow and approaches the short side portion 153 of the mold. In the case of a fast stirring flow, when the molten steel M accelerated in this way collides with the short side portion 153 of the mold, the ascending flow and the descending flow generated by the collision also become faster. When the ascending flow becomes faster, the fluctuation of the molten metal surface of the molten steel M and the amount of powder P entrained in the molten steel M increase. Further, when the downward flow becomes faster, inclusions and air bubbles penetrate deeply downward, solidify without floating, and the amount remaining on the slab increases. As described above, when a fast stirring flow is applied to the discharge flow, the slab is continuously cast while the powder P, air bubbles and inclusions are caught in the molten steel M, and the quality inside the slab deteriorates.
Further, when the molten steel M accelerated by a fast stirring flow collides with the solidified shell S shown in FIG. 3, the solidified shell S may be redissolved due to the collision. When the solidified shell S is redissolved, the solidified shell S is broken starting from the redissolved portion, which may lead to operational troubles such as molten steel leakage (breakout), in which case productivity is significantly impaired.

In a general electromagnetic agitator, if the stirring flow is slowed down in order to suppress such deterioration of the quality inside the slab or the redissolution of the solidified shell S, the quality of the slab surface, which is the original purpose of the electromagnetic agitator, is improved. It is not possible to make sufficient improvements. On the other hand, if the stirring flow is increased, the stirring flow is added to the discharge flow, impurities remain in the molten steel M, the quality inside the slab cannot be sufficiently improved, and the solidified shell S is redissolved. , Has a negative impact on productivity. As described above, in a general electromagnetic agitator, there is a trade-off relationship between the improvement of the surface quality of the slab, the improvement of the internal quality, and the improvement of the productivity.

Therefore, the present inventors make the discharge flow interfere with the stirring flow in the region close to the position of the immersion nozzle 170 in the casting width direction (X-axis direction), and the discharge flow becomes the stirring flow in other regions. I came up with the idea that stirring should be done so as to suppress interference. By doing so, it is possible to disperse the flow of the molten steel M while suppressing the flow velocity of the molten steel M in the region near the short side portion 153 of the mold. Therefore, the flow velocities of the ascending flow, the descending flow, and the collision flow to the solidification shell S can be slowed down. Therefore, it is possible to reduce the amount of powder P, air bubbles and inclusions entrained in the molten steel M, and further suppress the remelting of the solidified shell S.

The embodiment of the present invention has been made based on the above circumstances. Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the same comparison target such as length, position, size, interval, etc. is not only the case where they are exactly the same, but also the ones which are different within the range not deviating from the gist of the invention (for example, the tolerance determined at the time of design). (Different within the range) shall also be included.

(First Embodiment)
First, the first embodiment will be described.
2A and 2B are cross-sectional views showing an example of a schematic configuration of a continuous casting facility in which the electromagnetic agitator of the present embodiment is arranged. 2A is a cross-sectional view taken along the line II of FIGS. 3A and 3B, and FIG. 2B is a cross-sectional view taken along the line II-II of FIGS. 3A and 3B. 3A and 3B are vertical cross-sectional views showing an example of a schematic configuration of a continuous casting facility in which the electromagnetic agitator of the present embodiment is arranged. 3A is a cross-sectional view taken along the line II of FIGS. 2A and 2B. FIG. 3B is a cross-sectional view taken along the line II-II of FIG. 2A.
In FIGS. 2A, 2B, 3A and 3B, the continuous casting equipment of the present embodiment includes a mold having long side portions 211 and 212 and short side portions 213 and 214, back plates 221 and 224, and a dipping nozzle. It has 230 and an electromagnetic stirrer having iron cores 241 and 242 and coils 251 and 252.

The mold is a mold for continuously casting steel pieces having a predetermined width and thickness by cooling the molten steel M and solidifying it into a predetermined shape. As shown in FIGS. 3A and 3B, a solidified shell S is formed on the inner wall surface side of the long side portions 211 and 212 and the short side portions 213 and 214 in the lower region of the mold. Since the solidified shell S grows with cooling, the thickness of the solidified shell S becomes thicker as it is on the negative direction side of the Z axis. Then, when the whole is solidified, it becomes a slab.

As shown in FIGS. 2A and 2B, the shape of the horizontal cross section in the hollow portion of the mold is rectangular. The lateral (long side) direction (X-axis direction) of the hollow portion of the mold shown in FIGS. 2A and 2B is the casting width direction (width direction of the steel piece). Further, the vertical (short side) direction (Y-axis direction) of the mold shown in FIGS. 2A and 2B is the casting thickness direction (thickness direction of the steel piece). Further, the direction perpendicular to the paper surface of FIGS. 2A and 2B (Z-axis direction) is the casting direction (longitudinal direction of the slab).

The mold having such a configuration has a space between the long side portions 211 and 212 arranged opposite to each other with a space in the casting thickness direction (Y-axis direction) and a space in the casting width direction (X-axis direction). It has short side portions 213 and 214 arranged so as to face each other. By adjusting the positions of the short side portions 213 and 214 in the casting width direction (X-axis direction), the length of the hollow portion of the mold in the long side direction (casting width direction) can be adjusted. The length of the hollow portion of the mold in the long side direction (casting width direction) is shorter than the length in the casting width direction of the electromagnetic agitator (iron cores 241 and 242). On the other hand, the positions of the long side portions 211 and 212 of the mold can also be adjusted, and the positions of the long side portions 211 and 212 can be adjusted and the short side portions 213 and 214 can be replaced with those having a desired size. The length of the hollow portion of the mold in the short side direction (steel piece thickness direction) can be adjusted.

Back plates 221 and 222 are arranged on the back surfaces of the long side portions 211 and 212 of the mold (the surface opposite to the surface located on the molten steel M side) so as to support the long side portions 211 and 212, respectively. Back plates 223 and 224 are also arranged on the back surfaces of the short side portions 213 and 214 of the mold so as to support the short side portions 213 and 214, respectively. A path through which cooling water passes is formed in the mold (long side portions 211, 212, short side portions 213, 214) and the back plates 221 and 224. By flowing cooling water through the path, the molten steel M is solidified while cooling the continuous casting facility.

As shown in FIGS. 2A and 3A, the immersion nozzle 230 is arranged in the hollow portion of the mold. FIG. 3 shows only the region on the tip side of the immersion nozzle 230. The immersion nozzle 230 is arranged so that the axis of the immersion nozzle 230 and the axis of the hollow portion of the mold coincide with each other. FIG. 4 is a diagram showing an example of the configuration of the immersion nozzle 230. Specifically, FIG. 4 is a diagram showing a cross section of the immersion nozzle 230 when the immersion nozzle 230 is cut along the axis of the immersion nozzle 230 and along the casting width direction (X-axis direction). Similar to FIG. 3, FIG. 4 also shows only the region on the tip side of the immersion nozzle 230.

As shown in FIG. 4, discharge ports 230a and 230b are formed in the region of the side wall portion on the tip end side of the immersion nozzle 230 on both sides in the casting width direction (X-axis direction). The discharge ports 230a and 230b have a relationship of line symmetry with the axis of the immersion nozzle 230 as the axis of symmetry. Here, a case where the discharge ports 230a and 230b are opened diagonally downward toward the short side portions 213 and 214 is shown as an example. Therefore, the molten steel M is discharged from the discharge ports 230a and 230b toward the lower side of the mold. Here, the discharge angle θ (at the discharge ports 230a and 230b) of the immersion nozzle 230 is represented by the smaller angle between the horizontal direction and the inclination angle of the discharge ports 230a and 230b. In the example shown in FIG. 4, the discharge ports 230a and 230b are inclined downward (the negative direction of the Z axis). The absolute values of the discharge angle θ at the discharge port 230a and the discharge angle θ at the discharge port 230b are the same.

The position of the immersion nozzle 230 in the height direction of the hollow portion of the mold can be adjusted. Further, in order to prevent the discharge ports 230a and 230b from being clogged, the molten steel M is discharged while blowing an inert gas such as argon gas (Ar gas). The immersion nozzle 230 itself can be realized by a known technique, and is not limited to that shown in FIG.

The electromagnetic agitator applies an electromagnetic force to the molten steel M by generating a traveling magnetic field on the molten steel M (unsolidified portion) discharged from the immersion nozzle 230 and filled in the upper part of the mold, and agitates the molten steel M. This is a device that agitates the molten steel M by applying a force F to generate a stirring flow that orbits along the inner wall surfaces of the long side portions 211, 212 and the short side portions 213, 214 of the mold.

The electromagnetic agitator is a linear motor, and is a coil wound around iron cores 241 and 242 and iron cores 241 and 242 arranged so as to face each other with a distance from each other via long sides 211 and 212. It has 251 and 252.

In this embodiment, a case where a three-phase alternating current is applied to the coils 251 to 252 will be described as an example. Therefore, each of the coils 251 to 252 includes a plurality of coils of each phase. In FIGS. 2A and 2B, U, V, W, −U, −V, and −W are supplied with alternating current of U phase, V phase, W phase, −U phase, −V phase, and −W phase, respectively. Indicates that it is a coil. Here, the phase whose phase is advanced by 60 degrees with respect to the U phase is the −W phase. Similarly, the phase that is 120 degrees advanced with respect to the U phase is the V phase, the phase that is 180 degrees advanced is the -U phase, the phase that is 240 degrees advanced is the W phase, and the 300 degree phase is advanced. The phase that is out is the -V phase. Since the methods for energizing the coils 251 and 252 for generating the stirring flow are known as described in, for example, Patent Document 5, detailed description thereof will be omitted here.

FIG. 5 is a diagram showing an example of the configuration of the iron core 241. Since the iron cores 241 and 242 can be realized by the same ones, the illustration of the iron core 242 is omitted here. The iron cores 241 and 242 have a line-symmetrical relationship with the axis of the mold as the axis of symmetry.

In FIG. 5, the iron core 241 has a substantially T-shaped shape when viewed from the casting thickness direction (Y-axis direction). As described above, the iron core 241 has a shape that is symmetrical in the casting width direction with a surface that passes through the center of the iron core 241 in the casting width direction (X-axis direction) and extends in the casting direction (Z-axis direction) as a symmetrical surface.
Further, the plane of symmetry of the iron core 241 (the surface passing through the center in the casting width direction (X-axis direction) and extending in the casting direction (Z-axis direction)) is parallel to the axis of the immersion nozzle 230, and the immersion nozzle 230 The position of the shaft in the casting width direction and the position of the symmetric plane of the iron core 241 in the casting width direction are the same.

In FIG. 5, the iron core 241 has a comb tooth portion 241a and a joint iron portion 241b.
In the present embodiment, the iron core 241 is a soft magnetic plate (for example, a directional electromagnetic steel plate or a non-directional electromagnetic steel plate) having the same shape and size as the cross section perpendicular to the height direction (Z-axis direction) of the iron core 241. ) Are laminated in the height direction (Z-axis direction). Therefore, at each position of the iron core 241 in the height direction (Z-axis direction), there is no boundary line between the comb tooth portion 241a and the joint iron portion 241b.

The comb tooth portion 241a has a plurality of first rectangular parallelepiped portions 510 and 520 and a plurality of second rectangular parallelepiped portions 530. The plurality of first rectangular parallelepiped portions 510 and 520 and the plurality of second rectangular parallelepiped portions 530 are arranged at equal intervals along the casting width direction (X-axis direction). Further, the plurality of first rectangular parallelepiped portions 510 and 520 and the plurality of second rectangular parallelepiped portions 530 are arranged so as to face each other with a distance from the long side portion 211 (and the back plate 221) of the mold.

The first rectangular parallelepiped portion 510 is arranged on one end side (the positive direction side of the X-axis) of the iron core 241 in the casting width direction (X-axis direction). The first rectangular parallelepiped portion 520 is arranged on the other end side (negative direction side of the X axis) of the iron core 241 in the casting width direction (X-axis direction). The second rectangular parallelepiped portion 530 is arranged on the center side (between the first rectangular parallelepiped portions 510 and 520) of the iron core 241 in the casting width direction (X-axis direction).

From one end side (positive direction side of the X-axis) of the iron core 241 in the casting width direction (X-axis direction), a plurality of first rectangular parallelepiped portions 510, a plurality of second rectangular parallelepiped portions 530, and a plurality of first rectangular parallelepiped portions. The 520s are arranged at equal intervals along the casting width direction (X-axis direction) in this order.

The range of the region from one end to the other end in the casting width direction (X-axis direction) of the second rectangular body portion 530 arranged at equal intervals along the casting width direction (X-axis direction) is the discharge ports 230a and 230b. Includes the range from one end to the other end in the casting width direction (X-axis direction) of the immersion nozzle 230 at the position of the center of gravity (in FIG. 2B, the range in the X-axis direction of the iron core 241 is the X-axis direction of the immersion nozzle 230. See Including the range of).

The height direction of the first rectangular parallelepiped portion 510, 520 and the second rectangular parallelepiped portion 530 is the casting direction (Z-axis direction). The length of the second rectangular parallelepiped portion 530 in the height direction is longer than the length of the first rectangular parallelepiped portion 510 and 520 in the height direction. The shapes and sizes of the first rectangular parallelepiped portions 510 and 520 are the same. The shape and size of the second rectangular parallelepiped portion 530 are the same.

The joint iron portion 241b has one third rectangular parallelepiped portion 540 and one fourth rectangular parallelepiped portion 550.
The surface of the third rectangular parallelepiped portion 540 on the long side portion 211 side (positive direction side of the Y axis) is the long side portion 211 of the mold of the first rectangular parallelepiped portion 510, 520 and the second rectangular parallelepiped portion 530. It connects to the surface opposite to the opposite surface. The surface of the fourth rectangular parallelepiped portion 550 on the long side portion 211 side (positive direction side of the Y axis) of the mold is the surface of the second rectangular parallelepiped portion 530 opposite to the surface facing the long side portion 211 of the mold. Connect. The upper end surface of the fourth rectangular parallelepiped portion 550 (the end surface on the upstream side in the casting direction) is connected to the lower end surface of the third rectangular parallelepiped portion 540.

The lengths of the third rectangular body portion 540 in the casting width direction (X-axis direction) are the first rectangular body portions 510, 520 and the first rectangular body portions 510 and 520 in a state of being arranged at equal intervals along the casting width direction (X-axis direction). It is the same as the length in the casting width direction (X-axis direction) from one end to the other end in the casting width direction (X-axis direction) of the rectangular body portion 530 of 2. The height direction of the third rectangular parallelepiped portion 540 is the same as the casting direction (Z-axis direction).

The one end surface in the longitudinal direction of the third rectangular parallelepiped portion 540 (the end surface on the positive direction side of the X axis) is the first rectangular parallelepiped located most on the one end surface side (located on the most positive direction side of the X axis). It is flush with the end surface of the one end surface side (the positive direction side of the X axis) of the portion 510. The other end surface of the third rectangular parallelepiped portion 540 in the longitudinal direction (the end surface on the negative direction side of the X axis) is the first rectangular parallelepiped located most on the other end surface side (located on the most negative direction side of the X axis). It is flush with the end surface of the other end surface side (negative direction side of the X axis) of the portion 520.

Further, the upper end surface of the third rectangular parallelepiped portion 540 and the upper end surfaces of the first rectangular parallelepiped portion 510, 520 and the second rectangular parallelepiped portion 530 are flush with each other. The height direction of the third rectangular parallelepiped portion 540 coincides with the casting direction (Z-axis direction). The length of the third rectangular parallelepiped portion 540 in the height direction is the same as the length of the first rectangular parallelepiped portion 510 and 520 in the height direction. Of the lower end surfaces of the third rectangular parallelepiped portion 540, the surface connected to the first rectangular parallelepiped portion 510 and 520 and the lower end surface of the first rectangular parallelepiped portion 510 and 520 are flush with each other.

The height direction of the fourth rectangular parallelepiped portion 550 coincides with the casting direction (Z-axis direction). The length of the fourth rectangular parallelepiped portion 550 in the height direction is the same as the length obtained by subtracting the length of the first rectangular parallelepiped portion 510 or 520 in the height direction from the length of the second rectangular parallelepiped portion 530 in the height direction. Is. The upper end surface of the fourth rectangular parallelepiped portion 550 is connected to the lower end surface of the third rectangular parallelepiped portion 540.
There are no boundaries in the interconnected regions of the first rectangular parallelepiped portion 510, 520, the second rectangular parallelepiped portion 530, the third rectangular parallelepiped portion 540, and the fourth rectangular parallelepiped portion 550.

Of the first rectangular parallelepiped portion 510, 520 and the second rectangular parallelepiped portion 530, the coil 251 is arranged in the region between the two rectangular parallelepiped portions adjacent to each other along the casting width direction (X-axis direction) (the relevant). The coil 251 is not arranged on the flat surface of the rectangular parallelepiped portion on the mold 211 side). In this way, the coil 251 is wound in the casting width direction (X-axis direction) of the mold (that is, the axis (coil shaft) of the coil 251 is parallel to the casting width direction (X-axis direction) of the mold). The coil 251 is wound along the surfaces of the first rectangular parallelepiped portion 510, 520, the second rectangular parallelepiped portion 530, the third rectangular parallelepiped portion 540, and the fourth rectangular parallelepiped portion 550. Therefore, the length of the coil 251 is in the casting width direction (X-axis direction) rather than the portion arranged in the region between the two first rectangular parallelepiped portions 510 and 520 adjacent to each other along the casting width direction (X-axis direction). The portion arranged in the region between the two second rectangular parallelepiped portions 530 adjacent to each other along the X-axis direction) is longer.

In FIG. 5, in the present embodiment, the case where the electromagnetic agitator has five magnetic poles P1 to P5 will be described as an example. Three-phase alternating current is supplied to each of the coils (three in this embodiment) in P1 to P5, but P1 to P5 are adjacent to each other along the casting width direction (X-axis direction) of the iron core 241. Are 180 ° out of phase with each other, so each of P1 to P5 can be regarded as one cohesive pole. For example, when the magnetic pole P1 is the N pole, the magnetic poles P2, P3, P4, and P5 are the S pole, the N pole, the S pole, and the N pole, respectively. Further, in the present embodiment, the cross-sectional area of the iron core 241 (perpendicular to the casting width direction (X-axis direction)) is the same as the cross-sectional area surrounded by the portions (coils) constituting the same magnetic poles P1 to P5. To be. This is preferable because it is possible to suppress the occurrence of three-phase imbalance. In FIG. 5, the second rectangular parallelepiped portion 530 between the U phase of the magnetic pole P1 and the −V phase of the magnetic pole P2, and the second rectangular parallelepiped portion between the −U phase of the magnetic pole P4 and the V phase of the magnetic pole P5. The length in the height direction of the 530 may be the same as the length in the height direction of the first rectangular parallelepiped portion 510, and the first rectangular parallelepiped portion may be used. Further, even if the length in the casting width direction of the fourth rectangular parallelepiped portion 550 is shortened by the length in the casting width direction (X-axis direction) of the second rectangular parallelepiped portion whose length in the height direction is changed. good.

In the examples shown in FIGS. 3A and 3B, the positions of the lower end surfaces of the first rectangular parallelepiped portions 510 and 520 and the third rectangular parallelepiped portion 550 in the casting direction (Z-axis direction) and the discharge ports 230a and 230b of the immersion nozzle 230. The position of the upper end portion (the end portion on the upstream side in the casting direction) coincides with the position at position Z2. Further, the iron cores 241 and 242 have a relationship of line symmetry with the axis of the mold as the axis of symmetry. Further, the position in the casting direction (Z-axis direction) of the upper end surfaces of the iron cores 241 and 242 (the upper end surfaces of the first rectangular parallelepiped portion 510, 520, the second rectangular parallelepiped portion 530, and the third rectangular parallelepiped portion 540) is the position Z1. Match with. Further, the positions of the lower end surfaces of the iron cores 241 and 242 (the lower end surfaces of the second rectangular parallelepiped portion 530 and the fourth rectangular parallelepiped portion 550) in the casting direction (Z-axis direction) coincide with each other at the position Z4. Further, the position Z3 in the casting direction (Z-axis direction) of the tip surface (end surface on the downstream side in the casting direction) of the immersion nozzle 230 is lower than the position Z2 and higher than the position Z4.

In the above description, the iron core 242 is the long side portion 211, the back plate 221 and the iron core 241 and the coil 251 replaced with the long side portion 212, the back plate 222, the iron core 242, and the coil 252, respectively. Therefore, a detailed description of the iron core 242 will be omitted here.

FIG. 6 is a diagram illustrating an example of the flow of molten steel in the electromagnetic agitator of the present embodiment. FIG. 6 is a diagram corresponding to FIG. 1, and the notation method is the same as that of FIG. In the figure on the left side of FIG. 6, the larger the size of the circle of the symbol with ● in 〇 and the symbol with × in 〇 in the molten steel M, the greater the stirring force F. Indicates that it is large.

In the present embodiment, the iron cores 241 and 242 are configured so that the shape when viewed from the casting thickness direction (Y-axis direction) is substantially T-shaped. The iron cores 241 and 242 are arranged so that the position of the shaft of the immersion nozzle 230 in the casting width direction (X-axis direction) and the position of the center of the iron cores 241 and 242 in the casting width direction in the casting width direction are the same. Here, the T-shaped horizontal line region is defined as the second region, and the vertical line region is designated as the first region. In the present embodiment, the region above the upper ends of the discharge ports 230a and 230b of the immersion nozzles 230 of the iron cores 241 and 242 is set as the second region, and from the upper ends of the discharge ports 230a and 230b of the immersion nozzles 230 of the iron cores 241 and 242. The lower region is defined as the first region. Therefore, as shown in FIG. 6, in the region above the upper ends of the discharge ports 230a and 230b of the immersion nozzle 230, a fast stirring flow can be generated as in the stirring flow shown in FIG. On the other hand, in the region below the upper ends of the discharge ports 230a and 230b of the immersion nozzle 230, a fast stirring flow can be generated only in the region on the central side in the casting width direction (X-axis direction), and discharge is performed in that region. The discharge flow can be dispersed by interfering the flow with the interference flow. Since the generation of the stirring flow is suppressed in the region on the end side in the casting width direction (X-axis direction), it is possible to suppress an increase in the flow velocity of the discharge flow due to interference between the discharge flow and the stirring flow. Therefore, while suppressing the flow velocities of the ascending flow, the descending flow, and the collision flow to the solidification shell S generated on the short side portions 213 and 214 of the mold, a fast stirring flow is performed in the region above the upper end of the immersion nozzle 230. It is possible to realize the stirring of the molten steel M by the above method. As a result, even when the positions of the discharge ports 230a and 230b of the immersion nozzle 230 in the casting direction and the positions of the electromagnetic stirrer in the casting direction overlap, interference between the discharge flow and the stirring flow can be suppressed, and the slab can be suppressed. It is possible to improve the surface quality, the internal quality, and the productivity at the same time.

Further, the surfaces of the iron cores 241 and 242 (first region and second region) facing the long side portions 211 and 212 of the mold are formed on the iron cores 241 and 242 (of the iron cores 241 and 242) of the long side portions 211 and 212 of the mold. It is preferable to make it parallel to the surface facing the first region and the second region). In this way, the distance between the first region of the iron cores 241 and 242 and the long side portions 211 and 212 of the mold, and the distance between the second region of the iron cores 241 and 242 and the long side portions 211 and 212 of the mold. Can be made constant. Therefore, the electromagnetic steel sheet forming the first region and the electromagnetic steel sheet forming the second region can be realized by the same one, and a stable stirring flow can be generated.

FIG. 7 is a diagram showing an example of the relationship between the stirring force Fx (the X-axis direction component of F) and the position in the casting width direction (X-axis direction). The result shown in FIG. 7 is obtained by performing a numerical simulation of the electromagnetic force generated in the molten steel M in the hollow portion of the actual mold. In all the numerical simulations, the operating conditions including the component of molten steel M were the same.

The stirring force Fx is a stirring force acting on the molten steel M at a position 10 mm inside from the long side of the mold. FIG. 7A shows the stirring force Fx near the molten metal surface (meniscus) (the position in the casting direction (Z-axis direction) is within the range of the second region). FIG. 7B shows the stirring force Fx in the region where the position in the casting direction is the same as that near the lower end of the iron cores 241 and 242 (the region where the position in the casting direction (Z-axis direction) is within the range of the first region).
In FIGS. 7 (a) and 7 (b), graphs 701 and 703 show the stirring force Fx when the electromagnetic stirring device of this embodiment is used. Graphs 702 and 704 show the stirring force Fx when the general electromagnetic stirring device described with reference to FIG. 1 is used.

In a general electromagnetic agitator, the length of the joint iron portion in the casting direction (Z-axis direction) and the length of each square body portion of the comb tooth portion in the casting direction (Z-axis direction) are the same in all regions. The upper end surface and the lower end surface of the joint iron portion are made to coincide with the upper end surface and the lower end surface of each square body portion of the comb tooth portion. The electromagnetic agitator of the present embodiment and a general electromagnetic agitator are the same except for the length of each rectangular parallelepiped portion of the comb tooth portion and the joint iron portion in the casting direction (Z-axis direction).

As shown in the graphs 701 and 702 of FIG. 7A, a large stirring force Fx can be generated in the vicinity of the molten metal surface (meniscus) even in the electromagnetic stirring device of the present embodiment as in the general electromagnetic stirring device. can. Thereby, the quality of the slab surface can be improved.

Further, as shown in graphs 703 and 704 of FIG. 7B, even in a region where the position in the casting direction is the same as that near the lower end of the iron core 241242, in the region on the center side in the casting width direction, the electromagnetic agitator of the present embodiment However, it is possible to generate a large stirring force Fx like a general electromagnetic stirring device. As a result, the discharge flow can be dispersed.

On the other hand, as shown in graphs 703 and 704 of FIG. 7B, in the region where the position in the casting direction is the same as that near the lower end of the iron cores 241 and 242, the electromagnetic wave of the present embodiment is in the region on the end side in the casting width direction. By using the stirring device, the stirring force Fx can be reduced as compared with the case of using a general electromagnetic stirring device. Therefore, the flow velocities of the ascending flow, the descending flow and the collision flow to the solidified shell S can be reduced, and the slabs are prevented from being continuously cast while the powder P, air bubbles and inclusions are caught in the molten steel M. Furthermore, the redissolution of the solidified shell S can be suppressed. Therefore, the quality and productivity inside the slab can be improved.

<Modification example>
In the present embodiment, the second region (first rectangular parallelepiped portion 510, 520 and third rectangular parallelepiped portion 550) including the region of the iron cores 241 and 242 above the upper ends of the discharge ports 230a and 230b of the immersion nozzle 230). As an example, the position of the lower end of the dipping nozzle 230 in the casting direction (Z-axis direction) coincides with the position of the upper ends (upstream end in the casting direction) of the discharge ports 230a and 230b of the immersion nozzle 230 at position Z2. explained. However, it is not always necessary to do this. For example, the position of the lower end of the iron cores 241 and 242 in the casting direction (Z-axis direction) of the lower end of the second region including the region above the upper ends of the discharge ports 230a and 230b of the immersion nozzle 230 is the position Z2 (immersion nozzle 230). From the position of the upper ends of the discharge ports 230a and 230b in the casting direction (Z-axis direction) to the position Z3 (the position of the tip surface of the immersion nozzle 230 (the end surface on the downstream side in the casting direction) in the casting direction (Z-axis direction)). It can be any position in the range of. Since the discharge direction of the discharge flow discharged from the immersion nozzle 230 is diagonally downward, if it is within such a range, a second region including a region above the upper ends of the discharge ports 230a and 230b of the immersion nozzle 230. Even if the position of the lower end of the immersion nozzle 230 in the casting direction (Z-axis direction) is lower than the position of the upper ends of the immersion nozzles 230 in the casting direction (Z-axis direction), the discharge flow and stirring are performed. Since the region where the flow interferes can be reduced, the effect of reducing the flow velocity of the ascending flow, the descending flow, and the impact flow to the solidification shell S generated on the short side portions 213 and 214 of the mold can be exhibited. can.

Further, the position of the lower end of the second region including the region above the upper ends of the discharge ports 230a and 230b of the immersion nozzle 230 in the casting direction (Z-axis direction) is the upper end portion of the discharge ports 230a and 230b of the immersion nozzle 230. Even at a position above (the end on the upstream side in the casting direction), the region where the discharge flow and the stirring flow interfere can be reduced, so that the region occurs on the short side portions 213 and 214 of the mold. This may be done because the effect of reducing the flow velocity of the ascending flow, the descending flow, and the impact flow to the solidification shell S can be exhibited.

However, as in the present embodiment, the position of the lower end of the second region including the regions above the upper ends of the immersion nozzles 230a and 230b in the casting direction (Z-axis direction) is the discharge port of the immersion nozzle 230. By matching the positions of the upper ends of the 230a and 230b, it is possible to more reliably suppress the interference between the discharge flow and the stirring flow, and at the same time, the upper part of the discharge ports 230a and 230b of the immersion nozzle 230 can be twisted. It is more preferable because the stirring force F can be generated in a wide area.

Further, non-magnetic and non-conductive rectangular parallelepiped portions may be arranged under the first rectangular parallelepiped portion 510, 520 and the third rectangular parallelepiped portion 540, respectively. The length of the non-magnetic and non-conductive rectangular parallelepiped portion in the casting width direction (X-axis direction) and the casting thickness direction (Y-axis direction) is the same as the length of the first rectangular parallelepiped portion 510 and 540. The length of the non-magnetic and non-conductive rectangular parallelepiped portion in the casting direction (Z-axis direction) is the length of the fourth rectangular parallelepiped portion 550. Two such non-magnetic and non-conductive rectangular parallelepiped parts are prepared. The lower end surfaces of the first rectangular parallelepiped portions 510, 520 and the third rectangular parallelepiped portion 540 meet with the upper end surfaces of the non-magnetic and non-conductive rectangular parallelepiped portions, and the lower end surfaces of the non-magnetic and non-conductive rectangular parallelepiped portions and the second The non-magnetic and non-conductive rectangular parallelepiped portion is arranged so that the lower end surfaces of the rectangular parallelepiped portion 530 and the fourth rectangular parallelepiped portion 550 are flush with each other. By doing so, the outer shape can be the same as that of the iron cores 110 and 120 of the general electromagnetic agitator shown in FIG.
Further, the comb tooth portion 241a may not be provided. In this case, the surface of the immersion nozzle 230 facing the long side portions 211 and 212 of the mold in the second region including the region above the upper ends of the discharge ports 230a and 230b becomes one plane, and the plane becomes one plane. It is a surface of the first rectangular parallelepiped portion 510, 520 and the second rectangular parallelepiped portion 530, which faces the long side portion 211 of the mold.

Further, in the present embodiment, the case where the discharge direction of the discharge flow discharged from the immersion nozzle 230 is diagonally downward has been described as an example. However, the discharge direction of the discharge flow discharged from the immersion nozzle is not limited to diagonally downward. For example, the discharge direction of the discharge flow discharged from the immersion nozzle may be an obliquely upward direction or a horizontal direction.

Considering the cases where the discharge direction of the discharge flow discharged from the immersion nozzle is diagonally upward, diagonally downward, and horizontal, the casting width direction (X-axis direction) is the longitudinal direction. The second region (the region above the lower ends of the first rectangular parallelepiped portion 510, 520 and the third rectangular parallelepiped portion 540) and the first region (the first region) having a shorter length in the casting width direction than the second region. The iron cores 241 and 242 may be configured so as to have the rectangular parallelepiped portions 510 and 520 and the region below the lower end of the third rectangular parallelepiped portion 540). Here, the range in the casting width direction of the second region may include the range in the casting width direction of the first region. The fact that the range in the casting width direction of the second region includes the range in the casting width direction of the first region means that the first region is included in the coordinate values (X-axis coordinate values) in the casting width direction of the second region. It means that all the coordinate values in the casting width direction of the region are included. Further, the range in the casting width direction (X-axis direction) of the first region may include the range in the casting width direction of the immersion nozzle 230. Such a first region and a second region include a range of the casting direction (Z-axis direction) of the second region and a range of the casting direction in which the discharge flow from the discharge ports 230a and 230b of the immersion nozzle 230 flows. Is arranged at a position where the overlapping range is shorter than the overlapping range of the casting direction range of the first region and the casting direction range in which the discharge flow from the discharge ports 230a and 230b of the immersion nozzle 230 flows. I just need to be there. In this embodiment, the upper end of the first region and the lower end of the second region coincide with each other.

As in the present embodiment, the position of the lower end of the first rectangular parallelepiped portion 510a of the comb tooth portion 241a and the third rectangular parallelepiped portion 550 of the joint iron portion 241b in the casting direction (Z-axis direction) is the position of the immersion nozzle 230. If the positions of the upper ends of the discharge ports 230a and 230b are matched, the range of the casting direction (Z-axis direction) of the first region and the range of the casting direction (Z-axis direction) through which the discharge flow flows overlap. It disappears (see FIG. 6). In this way, the region where the discharge flow and the stirring flow F interfere with each other can be eliminated, so that the ascending flow, the descending flow, and the collision flow to the solidification shell S generated on the short side portions 213 and 214 of the mold can be eliminated. The flow velocity can be further reduced.

Further, considering the case where the discharge direction of the discharge flow discharged from the immersion nozzle is diagonally upward and the case where the discharge direction is diagonally downward, for example, the first region may be defined as follows. That is, when the discharge port of the immersion nozzle is inclined to the first side, the first region includes a region on the second side of the first end portion in the casting direction of the discharge port of the immersion nozzle. The first end of the discharge port of the immersion nozzle is the end on the second side of the discharge port of the immersion nozzle in the casting direction (Z-axis direction). The first side is the thick portion of the immersion nozzle (hatched in FIG. 4) on both sides (upper side and lower side) in the casting direction in the direction in which molten steel is discharged from the immersion nozzle (= toward the discharge port of the immersion nozzle). The part) is on the side in the direction of inclination). The second side is the side (opposite side of the first side) of both sides (upper side and lower side) in the casting direction, which is opposite to the side in which molten steel is discharged from the immersion nozzle. The end of the discharge port of the immersion nozzle is the end at the position of the outer wall surface of the immersion nozzle. That is, it is assumed that it is the contour (edge) of the opening that can be seen when the immersion nozzle is viewed from the outside.
Further, for example, the second region may include a region on the second side of the first end portion in the casting direction of the discharge port of the immersion nozzle.
In the present embodiment, the first end portion of the discharge port of the immersion nozzle in the casting direction is the end portion on the upper side (the positive direction side of the Z axis) of the discharge ports 230a and 230b of the immersion nozzle 230. The first side is the lower side (the negative direction side of the Z axis), and the second side is the upper side (the positive direction of the Z axis).

Further, in the present embodiment, the case where the number of magnetic poles of the electromagnetic agitator is an odd number has been described as an example. However, the number of magnetic poles of the electromagnetic agitator may be an even number. Even when the number of magnetic poles of the electromagnetic agitator is an even number, the cross-sectional area of the iron cores 241 and 242 (perpendicular to the casting width direction (X-axis direction)) is the same as when the number of magnetic poles of the electromagnetic agitator is an odd number. Therefore, it is preferable that the cross-sectional areas surrounded by the portions (coils) forming the same magnetic pole are the same, because the occurrence of three-phase imbalance can be suppressed.

Further, as described above, the cross-sectional areas of the iron cores 241 and 242 (perpendicular to the casting width direction (X-axis direction)) are the same so that the cross-sectional areas surrounded by the portions (coils) constituting the same magnetic pole are the same. This is preferable because it can suppress the occurrence of three-phase imbalance, but it is not always necessary to do so. That is, the cross-sectional area of the iron core (perpendicular to the casting width direction (X-axis direction)) and surrounded by the portions (coils) constituting the same magnetic pole may differ depending on the position in the magnetic pole. ..

Further, in the present embodiment, the case where the lengths of the second rectangular parallelepiped portion 530 and the fourth rectangular parallelepiped portion 550 in the casting direction (Z-axis direction) are all the same has been described as an example. However, as shown in FIG. 8, the lengths of the second rectangular parallelepiped portion and the fourth rectangular parallelepiped portion (the region of the T-shaped vertical line) in the casting direction (Z-axis direction) may be different. Even in this case, as shown in FIG. 8, the cross-sectional area of the iron core (perpendicular to the casting width direction (X-axis direction)) and surrounded by the portions (coils) constituting the same magnetic pole. It is preferable that they are the same as described above (as described above, it is not always necessary to do so).

(Second Embodiment)
Next, the second embodiment will be described. In the first embodiment, the casting width direction (X-axis direction) is the longitudinal direction only on the upper side of the iron cores 241 and 242 (the second side opposite to the direction in which the molten steel is discharged from the immersion nozzle). The case where the region (first rectangular parallelepiped portion 510, 520, third rectangular parallelepiped portion 540) is provided has been described as an example. On the other hand, in the present embodiment, a case where a region (third region) having the casting width direction (X-axis direction) as the longitudinal direction is provided on the lower side in addition to the upper side of the iron cores 241 and 242 will be described. As described above, the structure of the iron core is mainly different between the present embodiment and the first embodiment. Therefore, in the description of the present embodiment, detailed description will be omitted by assigning the same reference numerals as those given in FIGS. 2A to 8 for the same parts as those in the first embodiment.

9A and 9B are vertical cross-sectional views showing an example of a schematic configuration of a continuous casting facility in which the electromagnetic agitator of the present embodiment is arranged. The cross-sectional views taken along the line II of FIGS. 9A and 9B are the same as those in which reference numerals 241 and 242, 251, and 252 are designated as 941, 942, 951, and 952, respectively, and the illustration thereof will be omitted. .. Further, since the II-II cross-sectional views of FIGS. 9A and 9B are the same as those in which reference numerals 241 and 242, 251, and 252 are designated as 941, 942, 951, and 952, respectively, the illustration thereof will be omitted. .. Further, the cross-sectional views of III-III of FIGS. 9A and 9B are the same as those in which the reference numerals 241 and 242, 251 and 252 are designated as 941, 942, 951 and 952, respectively, and the immersion nozzle 230 is eliminated in FIG. 2A. , The illustration is omitted.

FIG. 10 is a diagram showing an example of the configuration of the iron core 941. Since the iron cores 941 and 942 can be realized by the same one, the illustration of the iron core 942 is omitted here. The iron cores 941 and 942 have a relationship of line symmetry with the axis of the mold as the axis of symmetry.
In FIG. 10, the iron core 941 has an approximately E-shaped shape (= H rotated by 90 °) when viewed from the casting thickness direction (Y-axis direction) (the lengths of the upper and lower horizontal lines are the same). Has. The iron core 941 has a comb tooth portion 941a and a joint iron portion 941b.
In the present embodiment, the iron core 941 is a soft magnetic plate (for example, a directional electromagnetic steel plate or a non-directional electromagnetic steel plate) having the same shape and size as the cross section perpendicular to the height direction (Z-axis direction) of the iron core 941. ) Are laminated in the height direction (Z-axis direction). Therefore, at each position of the iron core 841 in the height direction (Z-axis direction), there is no boundary line between the comb tooth portion 941a and the joint iron portion 941b.

The comb tooth portion 941a has a plurality of first rectangular parallelepiped portions 1010 to 1040 and a plurality of second rectangular parallelepiped portions 1050. The plurality of first rectangular parallelepiped portions 1010 to 1040 and the plurality of second rectangular parallelepiped portions 1050 are arranged at equal intervals along the casting width direction (X-axis direction). Further, the plurality of first rectangular parallelepiped portions 1010 to 1040 and the plurality of second rectangular parallelepiped portions 1050 are arranged so as to face each other with a distance from the long side portion 211 (and the back plate 221) of the mold.

The first rectangular body portion 1010 is one end of the iron core 941 in the casting width direction (X-axis direction) on one end side (the positive direction side of the Z axis = the second side) of the iron core 941 in the casting direction (Z-axis direction). It is arranged on the side (the positive direction side of the X-axis). The first rectangular body portion 1020 is formed on one end side (the positive direction side of the Z axis = the second side) of the iron core 941 in the casting direction (Z-axis direction) in addition to the casting width direction (X-axis direction) of the iron core 941. It is arranged on the end side (the negative direction side of the X axis).

The first rectangular body portion 1030 is in the casting width direction (X-axis direction) of the iron core 941 at the other end side (negative direction side of the Z-axis = first side) of the iron core 941 in the casting direction (Z-axis direction). It is arranged on one end side (the positive direction side of the X axis). The first rectangular body portion 1040 is in the casting width direction (X-axis direction) of the iron core 941 at the other end side (negative direction side of the Z-axis = first side) of the iron core 941 in the casting direction (Z-axis direction). It is arranged on the other end side (the negative direction side of the X axis).

The second rectangular parallelepiped portion 1050 is arranged on the center side (between the first rectangular parallelepiped portions 1010 and 1020 and between the first rectangular parallelepiped portions 1030 and 1040) of the iron core 941 in the casting width direction (X-axis direction).

On one end side (Z-axis positive direction side) of the iron core 941 in the casting direction (Z-axis direction), a plurality of iron cores 941 from one end side (X-axis positive direction side) in the casting width direction (X-axis direction). The first rectangular body portion 1010, the plurality of second rectangular body portions 1050, and the plurality of first rectangular body portions 1020 are arranged in this order at equal intervals along the casting width direction (X-axis direction).
On the other end side (Z-axis negative direction side) of the iron core 941 in the casting direction (Z-axis direction), from one end side (X-axis positive direction side) of the iron core 941 in the casting width direction (X-axis direction). A plurality of first rectangular body portions 1030, a plurality of second rectangular body portions 1050, and a plurality of first rectangular body portions 1040 are arranged in this order at equal intervals along the casting width direction (X-axis direction).
The lengths of the first rectangular parallelepiped portions 1010 to 1040 in the casting width direction (X-axis direction) are the same when they are arranged at equal intervals along the casting width direction (X-axis direction).

The positional relationship between the second rectangular body portion 1050 and the mold and the immersion nozzle 230 in the casting width direction (X-axis direction) is described with reference to FIG. 2B, the second rectangular body portion 530 and the mold of the first embodiment. And the positional relationship with the immersion nozzle 230 in the casting width direction (X-axis direction) is the same. Therefore, a detailed description of the positional relationship between the second rectangular parallelepiped portion 1050 and the mold and the immersion nozzle 230 in the casting width direction (X-axis direction) will be omitted.

The height direction of the first rectangular parallelepiped portion 1010 to 1040 and the second rectangular parallelepiped portion 1050 coincides with the casting direction (Z-axis direction). The length of the second rectangular parallelepiped portion 1050 in the height direction is longer than twice the length of the first rectangular parallelepiped portion 1010-1040 in the height direction. The shapes and sizes of the first rectangular parallelepiped portions 1010 to 1040 are the same. The shape and size of the second rectangular parallelepiped portion 1050 are the same.

The joint iron portion 941b has two third rectangular parallelepiped portions 1060 and 1070 and one fourth rectangular parallelepiped portion 1080.
The surface of the third rectangular parallelepiped portion 1060 on the long side portion 211 side (positive direction side of the Y axis) is the long side portion 211 of the mold of the first rectangular parallelepiped portion 1010, 1020 and the second rectangular parallelepiped portion 1050. It connects to the surface opposite to the opposite surface. Further, the surface of the third rectangular parallelepiped portion 1070 on the long side portion 211 side of the mold is opposite to the surface of the first rectangular parallelepiped portion 1030, 1040 and the second rectangular parallelepiped portion 1050 facing the long side portion 211 of the mold. Connect to the surface.
The surface of the fourth rectangular parallelepiped portion 1080 on the long side portion 211 side (the positive direction side of the Y axis) of the mold is on the surface of the second rectangular parallelepiped portion 1050 opposite to the surface facing the long side portion 211 of the mold. Connect. The upper end surface of the fourth rectangular parallelepiped portion 1080 (the end surface on the upstream side in the casting direction) is connected to the lower end surface of the third rectangular parallelepiped portion 1060. The lower end surface of the fourth rectangular parallelepiped portion 1080 (the end surface on the downstream side in the casting direction) is connected to the upper end surface of the third rectangular parallelepiped portion 1070.

The lengths of the third rectangular body portion 1060 in the casting width direction (X-axis direction) are the first rectangular body portions 1010, 1020 and the first rectangular body portions 1010 and 1020 in a state of being arranged at equal intervals along the casting width direction (X-axis direction). It is the same as the length in the casting width direction (X-axis direction) from one end to the other end in the casting width direction (X-axis direction) of the rectangular body portion 1050 of 2. The height direction of the third rectangular parallelepiped portion 1060 is the same as the casting direction (Z-axis direction).
Further, the length of the third rectangular body portion 1070 in the casting width direction (X-axis direction) is the first rectangular body portion 1030, 1040 in a state of being arranged at equal intervals along the casting width direction (X-axis direction). And the length of the second rectangular body portion 1050 in the casting width direction (X-axis direction) from one end to the other end in the casting width direction (X-axis direction) is the same. The height direction of the third rectangular parallelepiped portion 1070 is the same as the casting direction (Z-axis direction).
The lengths of the third rectangular parallelepiped portions 1060 and 1070 in the casting width direction (X-axis direction) are the same when they are arranged at equal intervals along the casting width direction (X-axis direction).

The one end surface in the longitudinal direction of the third rectangular parallelepiped portion 1060 (the end surface on the positive direction side of the X axis) is located most on the one end surface side (the end surface on the positive direction side of the X axis). It is flush with the end face of the 1010 on the one end face side (the positive direction side of the X axis). The other end surface of the third rectangular parallelepiped portion 1060 in the longitudinal direction (the end surface on the negative direction side of the X axis) is located closest to the other end surface side (located on the most negative direction side of the X axis). It is flush with the end surface of the 1020 on the other end surface side (the negative direction side of the X axis).

Further, the one end surface in the longitudinal direction of the third rectangular parallelepiped portion 1070 (the end surface on the positive direction side of the X axis) is located on the one end surface side most (located on the most positive direction side of the X axis). It is flush with the end surface of the rectangular parallelepiped portion 1030 on the one end surface side (the positive direction side of the X axis). The other end surface of the third rectangular parallelepiped portion 1070 in the longitudinal direction (the end surface on the negative direction side of the X axis) is located closest to the other end surface side (located on the most negative direction side of the X axis). It is flush with the end surface of the 1040 on the other end surface side (the negative direction side of the X axis).

The upper end surface of the third rectangular parallelepiped portion 1060 is flush with the upper end surfaces of the first rectangular parallelepiped portion 1010, 1020 and the second rectangular parallelepiped portion 1050. The height direction of the third rectangular parallelepiped portion 1060 coincides with the casting direction (Z-axis direction). The length of the third rectangular parallelepiped portion 1060 in the height direction is the same as the length of the first rectangular parallelepiped portion 1010 and 1020 in the height direction. Of the lower end surfaces of the third rectangular parallelepiped portion 1060, the surface connected to the first rectangular parallelepiped portion 1010, 1020 and the lower end surface of the first rectangular parallelepiped portion 1010, 1020 are flush with each other.

Further, the lower end surface of the third rectangular parallelepiped portion 1070 is flush with the lower end surfaces of the first rectangular parallelepiped portion 1030, 1040 and the second rectangular parallelepiped portion 1050. The height direction of the third rectangular parallelepiped portion 1070 coincides with the casting direction (Z-axis direction). The length of the third rectangular parallelepiped portion 1070 in the height direction is the same as the length of the first rectangular parallelepiped portion 1030 and 1040 in the height direction. Of the upper end surfaces of the third rectangular parallelepiped portion 1070, the surface connected to the first rectangular parallelepiped portions 1030 and 1040 and the upper end surface of the first rectangular parallelepiped portion 1030 and 1040 are flush with each other.

The height direction of the fourth rectangular parallelepiped portion 1080 coincides with the casting direction (Z-axis direction). The length in the height direction of the fourth rectangular parallelepiped part 1080 is obtained by subtracting twice the length in the height direction of the first rectangular parallelepiped part 1010-1040 from the length in the height direction of the second rectangular parallelepiped part 1050. Same as length. The upper end surface of the fourth rectangular parallelepiped portion 1080 is connected to the lower end surface of the third rectangular parallelepiped portion 1060, and the lower end surface of the fourth rectangular parallelepiped portion 1080 is connected to the upper end surface of the third rectangular parallelepiped portion 1070.
There are no boundaries in the interconnected regions of the first rectangular parallelepiped portion 1010-1040, the second rectangular parallelepiped portion 1050, the third rectangular parallelepiped portion 1060, 1070, and the fourth rectangular parallelepiped portion 1080.

Of the first rectangular parallelepiped portion 1010 to 1040 and the second rectangular parallelepiped portion 1050 as described above, the coil 951 is arranged in the region between the two rectangular parallelepiped portions adjacent to each other along the casting width direction (X-axis direction). (The coil 951 is not arranged on the plane of the rectangular parallelepiped portion on the mold 211 side). In this way, the coil 951 is wound in the casting width direction (X-axis direction) of the mold (that is, the axis (coil axis) of the coil 951 is parallel to the casting width direction (X-axis direction) of the mold). .. The coil 951 is wound along the surfaces of the first rectangular parallelepiped portion 1010-1040, the second rectangular parallelepiped portion 1050, the third rectangular parallelepiped portion 1060, 1070, and the fourth rectangular parallelepiped portion 1080.

Here, the region between two rectangular parallelepiped portions adjacent to each other along the casting width direction (X-axis direction) of the first rectangular parallelepiped portion 1010 and the casting width direction (X-axis direction) of the first rectangular parallelepiped portion 1030. The regions between two rectangular parallelepiped portions that are adjacent to each other along the direction) are aligned in the casting direction (Z-axis direction). The two regions that are lined up in the casting direction (Z-axis direction) differ only in the position in the casting direction (Z-axis direction).

Further, a region between two rectangular parallelepiped portions of the first rectangular parallelepiped portion 1020 that are adjacent to each other along the casting width direction (X-axis direction) and a casting width direction (X-axis direction) of the first rectangular parallelepiped portion 1040. ) Are adjacent to each other, and the regions between the two rectangular parallelepiped portions are aligned in the casting direction (Z-axis direction). The two regions that are lined up in the casting direction (Z-axis direction) differ only in the position in the casting direction (Z-axis direction).

A region between two first rectangular parallelepiped portions 1010 and 1020 that are adjacent to each other along the casting width direction (X-axis direction), and a first rectangular parallelepiped portion that is aligned with the region in the casting direction (Z-axis direction). The coil is wound so as to pass through the region between 1030 and 1040. Therefore, the coil is wound so as to pass through the region and the region between the two second rectangular parallelepiped portions 1050 adjacent to each other along the casting width direction (X-axis direction). In some cases, the range of the area where the coil is arranged is the same. Therefore, in the casting width direction (X-axis direction), the lengths of the coils arranged in the region between the two rectangular parallelepiped portions adjacent to each other along the casting width direction (X-axis direction) are made equal (same). be able to.

In FIG. 10, as in the first embodiment, the case where the electromagnetic agitator has five magnetic poles P1 to P5 will be described as an example in this embodiment as well. In the present embodiment, the cross-sectional area of the iron core 941 (perpendicular to the casting width direction (X-axis direction)) is the same so that the cross-sectional areas surrounded by the portions (coils) constituting the same magnetic poles P1 to P5 are the same. do. This is preferable because it is possible to suppress the occurrence of three-phase imbalance. In FIG. 10, the second rectangular parallelepiped portion 1050 between the U phase of the magnetic pole P1 and the −V phase of the magnetic pole P2, and the second rectangular parallelepiped portion between the −U phase of the magnetic pole P4 and the V phase of the magnetic pole P5. The length in the height direction of 1050 may be the same as the length in the height direction of the first rectangular parallelepiped portion 1010-1040, and the first rectangular parallelepiped portion may be used. Further, even if the length in the casting width direction of the fourth rectangular parallelepiped portion 1080 is shortened by the length in the casting width direction (X-axis direction) of the second rectangular parallelepiped portion whose length in the height direction is changed. good.

In the examples shown in FIGS. 9A and 9B, the positions of the lower end surfaces of the first rectangular parallelepiped portion 1010, 1020 and the third rectangular parallelepiped portion 1060 in the casting direction (Z-axis direction) and the upper ends of the discharge ports 230a and 230b of the immersion nozzle 230. The position of the portion (the end on the upstream side in the casting direction) coincides with the position at position Z2. Further, the positions of the upper end surfaces of the iron cores 941 and 942 (upper end surfaces of the first rectangular parallelepiped portion 1010, 1020, the second rectangular parallelepiped portion 1050, and the third rectangular parallelepiped portion 1060) in the casting direction (Z-axis direction) are at position Z1. Match. Further, the positions of the lower end surfaces of the iron cores 941 and 942 (lower end surfaces of the first rectangular parallelepiped portion 1030, 1040, the second rectangular parallelepiped portion 1050, and the fourth rectangular parallelepiped portion 1070) in the casting direction (Z-axis direction) are at position Z4. Match. Further, the position Z3 in the casting direction (Z-axis direction) of the tip surface (end surface on the downstream side in the casting direction) of the immersion nozzle 230 is below the position Z2 and above the position Z4.

Further, the position Z5 of the upper end surface of the first rectangular body portion 1030 and 1040 in the casting direction (Z-axis direction) is the casting direction (Z-axis direction) of the tip surface (end surface on the downstream side of the casting direction) of the immersion nozzle 230. Below position Z3 and above position Z4.
The length ZL [mm] in the casting direction (Z-axis direction) from the position Z1 to the position Z5 preferably satisfies the following equation (1).
ZL ≧ ZD + ZH + {(WD) ÷ 2} × tan θ ・ ・ ・ (1)
Here, ZD [mm] is the length in the casting direction (Z-axis direction) from the molten metal surface (meniscus) to the upper ends of the discharge ports 230a and 230b of the immersion nozzle 230 (see FIGS. 9A and 9B). ZH [mm] is the length of the discharge ports 230a and 230b of the immersion nozzle 230 in the casting direction (Z-axis direction) (see FIGS. 9A and 9B). W [mm] is the distance in the casting width direction (X-axis direction) of the inner wall surfaces of the short side portions 213 and 214 of the mold (see FIG. 2B). D [mm] is the outer diameter at the position of the center of gravity of the discharge ports 230a and 230b of the immersion nozzle 230 (see FIGS. 9A and 9B). θ [°] is the discharge angle θ (at the discharge ports 230a and 230b) of the immersion nozzle 230.

The immersion nozzle 230 and the mold (variables ZD, ZH, W, D, θ on the right side of equation (1)) can be changed. Therefore, it is more preferable that the combination of the immersion nozzle 230 and the mold assumed in the continuous casting facility satisfies the equation (1) in any combination. That is, it is more preferable that the length ZL in the casting direction (Z-axis direction) from the position Z1 to the position Z5 is equal to or more than the maximum value that can be taken as the value on the right side of the equation (1). In this way, assuming that the discharge flow discharged from the immersion nozzle 230 moves linearly, the discharge flow will collide with the short side portions 213 and 214 of the mold and at a position below the position. The upper end surfaces of the first rectangular parallelepiped portions 1030 and 1040 can be positioned. Therefore, the stirring flow formed in the region where the discharge flow discharged from the discharge ports 230a and 230b of the immersion nozzle 230 flows can be further suppressed.

In the above description, the iron core 942 is the long side portion 211, the back plate 221 and the iron core 941 and the coil 951, which are replaced with the long side portion 212, the back plate 222, the iron core 942, and the coil 952, respectively. Therefore, a detailed description of the iron core 942 will be omitted here.

FIG. 11 is a diagram illustrating an example of the flow of molten steel in the electromagnetic agitator of the present embodiment. FIG. 11 is a diagram corresponding to FIGS. 1 and 6, and the notation method is the same as that of FIGS. 1 and 6.

In the present embodiment, the iron cores 941 and 942 are configured so that the shape when viewed from the casting thickness direction (Y-axis direction) is approximately D-shaped. The iron cores 941 and 942 are arranged so that the position of the shaft of the immersion nozzle 230 in the casting width direction (X-axis direction) and the position of the center of the iron cores 941 and 942 in the casting width direction in the casting width direction are the same. Here, the area of the upper horizontal line in the shape of a D is set as the second area, the area of the vertical line is set as the first area, and the area of the lower horizontal line is set as the third area. The region of the iron cores 941 and 942 above the upper ends of the discharge ports 230a and 230b of the immersion nozzle 230 is set as the second region, and the region of the iron cores 941 and 942 below the upper ends of the discharge ports 230a and 230b of the immersion nozzle 230. The region is defined as the first region, and the region below the first region is designated as the third region.

Therefore, as shown in FIG. 11, in the region above the upper ends of the discharge ports 230a and 230b of the immersion nozzle 230, a fast stirring flow can be generated as in the stirring flow shown in FIG. On the other hand, in the region below the upper ends of the discharge ports 230a and 230b of the immersion nozzle 230, a fast stirring flow can be generated only in the region on the central side in the casting width direction (X-axis direction), and discharge is performed in that region. The discharge flow can be dispersed by interfering the flow with the interference flow. Since the generation of the stirring flow is suppressed in the region on the end side in the casting width direction (X-axis direction), it is possible to suppress an increase in the flow velocity of the discharge flow due to interference between the discharge flow and the stirring flow. Further, in the third region, a fast stirring flow can be generated as in the second region. Therefore, in addition to being able to further reduce the flow velocity of the downward flow and the flow velocity of the collision flow to the solidification shell S, the fast stirring flow in the third region allows bubbles and inclusions in the downward flow to enter downward. It can be suppressed and promoted ascent. Therefore, the quality of the slab surface, the internal quality and the productivity can be further improved.

Further, the surfaces of the iron cores 941 and 942 (first region, second region and third region) facing the long side portions 211 and 212 of the mold are formed on the iron cores 941 and 212 of the long side portions 211 and 212 of the mold. It is preferable that the surface is parallel to the surface facing 942 (the first region, the second region and the third region). In this way, the distance between the first region and the long side portions 211 and 212 of the mold, the distance between the second region and the long side portions 211 and 212 of the mold, and the distance between the third region and the long side portion of the mold The distance between the 211 and 212 can be made constant, respectively. Therefore, the electromagnetic steel sheet forming the first region, the electromagnetic steel sheet forming the second region, and the electromagnetic steel sheet forming the third region can be realized by the same ones, respectively, and a stable stirring flow can be generated. Can be done.

Further, the length in the casting width direction (X-axis direction) of the second region of the iron cores 941 and 942 (first rectangular parallelepiped portion 1010, 1020, second rectangular parallelepiped portion 1050 (upper portion) and third rectangular parallelepiped portion 1060). And the length in the casting width direction (X-axis direction) of the third region of the iron cores 941 and 942 (first rectangular parallelepiped portion 1030, 1040, second rectangular parallelepiped portion 1050 (lower part) and third rectangular parallelepiped portion 1070). It is preferable to make it the same as. In this way, the electromagnetic steel sheet forming the second region of the iron cores 941 and 942 and the electromagnetic steel sheet forming the third region of the iron cores 941 and 942 can be shared.

FIG. 12 is a diagram showing an example of the relationship between the stirring force Fx (the X-axis direction component of F) and the position in the casting width direction (X-axis direction). The results shown in FIG. 12 are obtained by performing a numerical simulation of the electromagnetic force generated in the molten steel M in the hollow portion of the actual mold. In all the numerical simulations, the operating conditions including the component of molten steel M were the same. Fx is the same as that described with reference to FIG.

FIG. 12A shows the stirring force Fx near the molten metal surface (meniscus) (the position in the casting direction (Z-axis direction) is within the range of the second region). FIG. 12B shows the stirring force Fx near the center of the iron cores 941 and 942 in the casting direction (Z-axis direction) (the position in the casting direction (Z-axis direction) is within the range of the first region). FIG. 12C shows the stirring force Fx in the region where the position in the casting direction is the same as that near the lower ends of the iron cores 941 and 942 (the region where the position in the casting direction (Z-axis direction) is within the range of the third region).
In FIGS. 12 (a) to 12 (c), graphs 1201, 1203 and 1205 show the stirring force Fx when the electromagnetic stirring device of this embodiment is used. Graphs 1202, 1204 and 1206 show the stirring force Fx when the general electromagnetic stirring device described with reference to FIG. 1 is used. The graphs 702 and 704 shown in FIG. 7 also show the stirring force Fx when the general electromagnetic stirring device described with reference to FIG. 1 is used, but graphs 702 and 704 and graphs 1202, 1204 and 1206 are obtained. The operating conditions at the time are different. Therefore, the graphs 702 and 1204 at the same position do not match. However, as described above, the operating conditions when the graphs 1202, 1204 and 1206 are obtained are the same.

As shown in graphs 1201 and 1202 of FIG. 12A, a large stirring force Fx can be generated in the vicinity of the molten metal surface (meniscus) even in the electromagnetic stirring device of the present embodiment as in the general electromagnetic stirring device. can. Thereby, the quality of the slab surface can be improved.

Further, as shown in graphs 1203 and 1204 of FIG. 12B, even in a region where the positions of the iron cores 941 and 942 in the casting direction (Z-axis direction) are the same as those in the casting direction, the center side in the casting width direction In the region, the electromagnetic stirring device of the present embodiment can also generate a large stirring force Fx as in the general electromagnetic stirring device. As a result, the discharge flow can be dispersed.

On the other hand, as shown in graphs 1203 and 1204 of FIG. 12B, in a region where the positions in the casting direction are the same as those near the center of the iron cores 941 and 942 in the casting direction (Z-axis direction), the region on the end side in the casting width direction. Then, by using the electromagnetic stirring device of the present embodiment, the stirring force Fx can be reduced as compared with the case of using a general electromagnetic stirring device. Therefore, the flow velocities of the ascending flow, the descending flow and the collision flow to the solidified shell S can be reduced, and the slabs are prevented from being continuously cast while the powder P, air bubbles and inclusions are caught in the molten steel M. It is possible to suppress the redissolution of the solidified shell S.

Further, as shown in graphs 1205 and 1206 of FIG. 12C, in a region where the positions in the casting direction are the same as those near the lower ends of the iron cores 941 and 942, a large stirring force Fx is generated as in a general electromagnetic stirring device. Can be made to. Therefore, the floating of powder P, air bubbles and inclusions can be promoted. Therefore, the quality inside the slab can be further improved.

<Modification example>
In the present embodiment, the case where the length ZL in the casting direction (Z-axis direction) from the position Z1 to the position Z5 satisfies the equation (1) has been described as an example. In this way, many regions where the discharge flow is generated can be set as the first region, which is preferable. However, the first region can be determined according to the direction of the discharge flow and the degree of the effect of suppressing the interference between the discharge flow and the stirring flow. For example, the position of the lower end of the immersion nozzle 230 in the casting direction (Z-axis direction) may be the position Z5. Further, the position Z5 may be a position below the position of the lower end of the immersion nozzle 230 in the casting direction (Z-axis direction) within the range satisfying the equation (1). Further, the right side of the equation (1) may be changed to [ZD + ZH + {(WD) ÷ 2} × tan θ] ÷ 2. Further, when the molten steel M is discharged in the horizontal direction from the discharge port of the immersion nozzle, the position of the lower ends of the discharge ports 230a and 230b of the immersion nozzle 230 in the casting direction (Z-axis direction) may be set to the position Z5. In this case, for example, the position in the casting direction (Z-axis direction) of the upper ends (one end) of the discharge ports 230a and 230b of the immersion nozzle 230 is set to position Z2, and the lower ends of the discharge ports 230a and 230b of the immersion nozzle 230 (the other end). The position of the end portion) in the casting direction (Z-axis direction) may be set to position Z5.

Further, in the present embodiment, the case where the lower end surfaces of the iron cores 941 and 942 of the mold are located above the long side portions 211 and 212 of the mold has been described as an example. However, the positions of the lower end surfaces of the iron cores 941 and 942 of the mold in the casting direction (Z-axis direction) are not limited to such positions. For example, the position of the lower end surfaces of the iron cores 941 and 942 in the casting direction (Z-axis direction) may be the same as the position of the lower end surfaces of the long side portions 211 and 212 of the mold in the casting direction (Z-axis direction). In this way, the casting direction (Z-axis direction) of the third region of the iron cores 941 and 942 (first rectangular parallelepiped portion 1030, 1040, second rectangular parallelepiped portion 1050 (lower part) and third rectangular parallelepiped portion 1070). ) Can be made larger. Therefore, the flow velocity of the descending flow can be further reduced, bubbles and inclusions on the descending flow can be further suppressed from entering downward, and ascending can be further promoted. Therefore, both the surface quality and the internal quality of the slab can be further improved.

Further, in the present embodiment, the distance between the second region of the iron cores 941 and 942 and the long side portions 211 and 212 of the mold, the third region of the iron cores 941 and 942 and the long side portions 211 and 212 of the mold are The case where the intervals are the same has been described as an example. However, it is not always necessary to do this. There is less powder P (or no powder P) in the lower part than in the upper part of the mold. Therefore, even if the stirring force applied to the molten steel M is increased, the possibility that the powder P is involved in the molten steel M is lower than that in the upper part of the mold. Therefore, for example, the distance between the third region of the iron core and the long side portions 211 and 212 of the mold may be shorter than the distance between the first region of the iron core and the long side portions 211 and 212 of the mold. Further, the distance between the iron core and the long side portions 211 and 212 of the mold may be shortened as it is located at the lower part. By doing so, it is possible to alleviate improper solidification of the molten steel M by increasing the stirring force F.

Further, in the present embodiment, the case where the lengths of the second rectangular parallelepiped portion 1050 and the fourth rectangular parallelepiped portion 1080 in the casting direction (Z-axis direction) are all the same has been described as an example. However, as shown in FIG. 13, the lengths of the second rectangular parallelepiped portion and the fourth rectangular parallelepiped portion (region of the vertical line in the shape of an E) in the casting direction (Z-axis direction) may be different. In this case, as shown in FIG. 13, the second rectangular parallelepiped portion and the fourth rectangular parallelepiped portion include those arranged at intervals in the casting direction (Z-axis direction). Even in this case, as shown in FIG. 13, the cross-sectional area of the iron core (perpendicular to the casting width direction (X-axis direction)) and surrounded by the portions (coils) constituting the same magnetic pole is It is preferable that they are the same as described above (as described above, it is not always necessary to do so).
Further, also in this embodiment, various modifications described in the first embodiment can be adopted.

It should be noted that the embodiments of the present invention described above are merely examples of embodiment of the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. It is a thing. That is, the present invention can be implemented in various forms without departing from the technical idea or its main features.

211-212: Long side part, 213 to 214: Short side part, 221-224: Back plate, 230: Immersion nozzle, 241-242, 941-942: Iron core, 251-252, 951-952: Coil

Claims (16)

A first iron core and a second iron core arranged at positions facing each other via the long side of the mold,
A first coil wound around the first iron core in the casting width direction of the mold, and
A second coil wound around the second iron core in the casting width direction of the mold, and
Have,
By generating a traveling magnetic field based on the alternating current flowing through the first coil and the second coil in the casting width direction, the hollow portion of the mold is directed from the discharge port of the immersion nozzle toward the short side of the mold. An electromagnetic agitator that electromagnetically agitates the molten metal injected into the
The first iron core and the second iron core each have a first region and a second region which is a region in which the position in the casting direction is different from that of the first region.
The range in the casting width direction of the first region includes the range in the casting width direction of the immersion nozzle.
The length of the first region in the casting width direction is shorter than the length of the second region in the casting width direction, and the range of the second region in the casting width direction is that of the first region. Including the range in the casting width direction
The range in which the range in the casting direction of the second region and the range in the casting direction in which the discharge flow, which is the flow of molten metal from the discharge port of the immersion nozzle toward the short side of the mold, flows, is better. An electromagnetic agitator characterized in that the range of the casting direction of the first region and the range of the casting direction in which the discharge flow flows are shorter than the overlapping range. The first iron core and the second iron core pass through the center of the first iron core and the second iron core in the casting width direction, and are symmetrical in the casting width direction with an axis extending in the casting direction as an axis of symmetry. The electromagnetic agitator according to claim 1, wherein the electromagnetic agitator has a shape of the above. The axis of the immersion nozzle and the axis of symmetry are parallel and
The second aspect of claim 2, wherein the position of the shaft of the immersion nozzle in the casting width direction and the position of the center of the first iron core and the second iron core in the casting width direction in the casting width direction are the same. Electromagnetic stirrer. The surface of the first region and the second region facing the long side portion of the mold is parallel to the surface of the long side portion of the mold facing the first region and the second region. The electromagnetic agitator according to any one of claims 1 to 3, wherein the electromagnetic agitation device is characterized in that it is a surface. The electromagnetic agitator according to any one of claims 1 to 4, wherein a region surrounded by coils forming the same magnetic pole has the same cross-sectional area in a direction perpendicular to the casting width direction. The discharge port of the immersion nozzle is inclined to the first side.
The first region includes a region on the first side of the first end in the casting direction of the discharge port of the immersion nozzle.
The first end in the casting direction of the discharge port of the immersion nozzle is the end on the second side of the discharge port of the immersion nozzle in the casting direction.
The electromagnetic agitator according to any one of claims 1 to 5, wherein the second side is the opposite side of the first side. The electromagnetic agitator according to claim 6, wherein the second region includes a region on the second side of the first end portion in the casting direction of the discharge port of the immersion nozzle. The molten metal is discharged diagonally downward from the discharge port of the immersion nozzle.
The first side is the lower side
The second side is the upper side.
The electromagnetic agitator according to claim 6 or 7, wherein the first end portion in the casting direction of the discharge port of the immersion nozzle is an upper end portion of the discharge port of the immersion nozzle. The position of the lower end of the second region in the casting direction is from the position of the upper end of the discharge port of the immersion nozzle in the casting direction to the position of the lower end of the immersion nozzle in the casting direction. The electromagnetic agitator according to claim 8, wherein the position is any of the above ranges. The first iron core and the second iron core are regions in which the positions in the casting direction are different from the first region, the second region, the first region, and the second region, respectively. Has a third area and
The third region is arranged on the first side in the casting direction with respect to the first region, and the second region is arranged on the second side with respect to the first region.
The electromagnetic agitator according to any one of claims 1 to 9, wherein the first side is the opposite side of the second side. 10. The surface of the third region facing the long side of the mold is a surface of the long side of the mold parallel to the surface of the third region facing the third region. The electromagnetic agitator according to. The electromagnetic agitator according to claim 10 or 11, wherein the length of the second region in the casting width direction and the length of the third region in the casting width direction are the same. The electromagnetic agitator according to any one of claims 10 to 12, wherein the discharge port of the immersion nozzle is inclined toward the first side. The molten metal is discharged diagonally downward from the discharge port of the immersion nozzle.
The position of the lower end of the first region in the casting direction is lower than the position of the lower end of the discharge port of the immersion nozzle in the casting direction or the position of the lower end of the discharge port of the immersion nozzle in the casting direction. The electromagnetic agitator according to any one of claims 10 to 13. ZL [mm] is the length in the casting direction from the end of the second side in the casting direction of the second region to the end of the first side in the casting direction of the third region.
ZD [mm] is the length in the casting direction from the molten metal surface in the hollow portion of the mold to the first end in the casting direction of the discharge port of the immersion nozzle.
ZH [mm] is defined as the length of the discharge port of the immersion nozzle in the casting direction.
W [mm] is defined as the distance in the casting width direction of the inner wall surface of the short side of the mold.
D [mm] is defined as the outer diameter of the immersion nozzle at the position of the center of gravity of the discharge port of the immersion nozzle.
Let θ [°] be the discharge angle of the immersion nozzle.
The electromagnetic agitator according to any one of claims 10 to 14, wherein the electromagnetic agitator according to the following equation (A) is satisfied.
ZL ≧ ZD + ZH + {(WD) ÷ 2} × tan θ ・ ・ ・ (A) The electromagnetic agitator according to any one of claims 1 to 15, wherein the number of magnetic poles composed of the current flowing through the first coil and the second coil is an odd number.

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