JP7389339B2 - electromagnetic stirring device - Google Patents

Description

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

When continuously casting slabs or other slabs, molten metal supplied from a ladle to a tundish is injected into a hollow part of a mold (an area surrounded by the mold) by a submerged nozzle.
An electromagnetic brake is a device for improving the quality of slabs. As described in Patent Document 1, the electromagnetic brake applies a DC magnetic field (static magnetic field) to the mold by passing current through a set of electromagnetic coils that are arranged to face each other through the long sides of the mold. By applying the force to the molten metal in the hollow portion, the downward flow velocity of the molten metal is reduced. Note that the technique described in Patent Document 1 is a technique for solving the problem when discharging molten metal from an immersed nozzle in the casting direction (vertically downward) (when using a straight immersed nozzle).

In addition to such an electromagnetic brake, there is an electromagnetic stirring device as a device for improving the quality of slabs. An electromagnetic stirring device stirs molten metal by applying an alternating current magnetic field to the molten metal in the hollow part of the mold by passing an electric current through the coils of a set of electromagnets arranged to face each other through the long sides of the mold. The molten metal is electromagnetically stirred by applying a stirring force that causes it to rotate in a horizontal plane. Thus, although both the electromagnetic brake and the electromagnetic stirring device control the flow of molten metal, their functions are different.

As techniques related to electromagnetic stirring devices, there are techniques described in Patent Documents 2 to 4.
Patent Document 2 describes that the electromagnetic stirring device is arranged so that the upper end of the discharge port of the immersion nozzle is lower than the lower end of the electromagnetic stirring device. 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 disturbance of the flow of molten metal within the hollow part of the mold due to the magnetic field generated by the electromagnetic stirring device.

Patent Document 3 describes that the distance between the core of the electromagnetic stirring device and the mold is the largest at the center of the core in the casting direction.

Patent Document 4 discloses that the iron core of an electromagnetic stirring device is a plurality of salient poles arranged at intervals in a direction parallel to the long sides of the mold, and the tip surface has a distance from the long sides of the mold. It is described that the method includes a plurality of salient poles arranged to face each other at 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.

Patent No. 2888312 Patent No. 5073531 Japanese Patent Application Publication No. 2008-173644 Japanese Patent Application Publication No. 11-156502 Patent No. 5353883

However, the techniques described in Patent Documents 2 to 4 take into account the positional relationship between the immersion nozzle and the electromagnetic stirring device when the position of the discharge port of the immersion nozzle in the casting direction and the position of the electromagnetic stirring device in the casting direction overlap. I haven't.

In addition, in the technology described in Patent Document 2, interference between the flow of molten metal discharged from a submerged nozzle (discharge flow) and the flow of molten metal (stirring flow) due to the stirring force applied to the molten metal by an electromagnetic stirring device In order to suppress this, this technique is based on the premise that the upper end of the discharge port is located lower than the lower end of the electromagnetic stirring device. Therefore, with the technique described in Patent Document 2, it is completely impossible to control the flow of molten metal below the upper end of the discharge port. Additionally, a magnetic shielding plate must be placed inside the mold. Therefore, the cost for arranging the magnetic shielding plate is high, and a place for arranging the magnetic shielding plate must be secured.

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

Further, the technique described in Patent Document 4 is a technique for realizing the functions of an electromagnetic brake device and an electromagnetic stirring device in one device. Therefore, the coil must be wound around the salient poles of the mold in a direction perpendicular to the long sides of the mold. Therefore, the space for arranging the coil is limited. Further, the area of the alternating current magnetic field generated by the current flowing through the coil is limited to the upper and lower areas 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-mentioned problems, and even when the position of the discharge port of the submerged nozzle in the casting direction and the position of the electromagnetic stirring device in the casting direction overlap, the discharge flow and the stirring flow are The purpose is to suppress interference with

The electromagnetic stirring device of the present invention includes a first iron core and a second iron core arranged at positions facing each other across the long sides of the mold, and a casting width direction of the mold with respect to the first iron core. a first coil wound around the second iron core, and a second coil wound around the second iron core in the casting width direction of the mold; By generating a traveling magnetic field in the casting width direction based on an alternating current flowing through a coil, the molten metal injected into the hollow part of the mold from the discharge port of the immersion nozzle toward the short side of the mold is electromagnetically stirred. In the electromagnetic stirring device, the first core and the second core each have a first region and a second region having a different position in a casting direction from the first region. The first region is a region whose range in the casting direction is a part between both ends of the first core and the second core in the casting direction, and the first region is a region in the casting width direction of the first region. The range includes the range of the immersion nozzle in the casting width direction, and the length of the first area in the casting width direction is shorter than the length of the second area in the casting width direction, and The range in the casting width direction of the 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 range from the outlet of the immersion nozzle to the short side of the mold. The range in which the casting direction of the first region overlaps with the range in the casting direction through which the discharge flow, which is the flow of molten metal toward, overlaps with the range in the casting direction in which the discharge flow flows. It is characterized by being shorter than the range.

According to the present invention, even when the position of the discharge port of the immersion nozzle in the casting direction and the position of the electromagnetic stirring device in the casting direction overlap, interference between the discharge flow and the stirring flow can be suppressed.

It is a figure explaining an example of the flow of molten steel in a general electromagnetic stirring device. FIG. 2 is a cross-sectional view at a first position showing a first example of a schematic configuration of continuous casting equipment. FIG. 2 is a cross-sectional view at a second position showing a first example of a schematic configuration of continuous casting equipment. FIG. 2 is a longitudinal cross-sectional view at a first position showing a first example of a schematic configuration of continuous casting equipment. FIG. 2 is a longitudinal cross-sectional view at a second position showing a first example of a schematic configuration of continuous casting equipment. It is a figure showing an example of the composition of the immersion nozzle. It is a figure showing the 1st example of composition 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 stirring force and the position of casting width direction. It is a figure which shows the modification of the 1st example of a structure of an iron core. It is a longitudinal cross-sectional view at the 1st position showing the 2nd example of the schematic structure of continuous casting equipment. It is a longitudinal cross-sectional view at the 2nd position showing the 2nd example of the schematic structure of the continuous casting equipment. It is a figure which shows the 2nd example of a structure of an iron core. It is a figure explaining the 2nd example of the flow of molten steel. FIG. 7 is a diagram showing a second example of the relationship between stirring force and position in the casting width direction. It is a figure which shows the modification of the 2nd example of a structure of an iron core.

(background)
First, the circumstances leading to the embodiment of the present invention will be explained.

FIG. 1 is a diagram illustrating an example of the flow of molten steel in a general electromagnetic stirring device. The XYZ coordinates shown in each figure indicate the directional relationship in each figure. A symbol with an x inside a circle indicates the direction from the front side to the back side of the page. A symbol with a ● inside a circle indicates the direction from the back of the page to the front. In the following explanation, a case where the molten metal is molten steel will be described as an example.

In Figure 1, when looking at the page with the positive direction of the Z-axis pointing upwards, the left side figure (the figure in which the FIG. 3 is a diagram conceptually showing an example of a discharge flow and a stirring flow when viewed from the side side. In the diagram on the left side of Fig. 1, the arrow line indicates the discharge flow at time t, and the symbol with an x in the circle and the symbol with a ● in the circle indicate the stirring flow at time t. .

In addition, in Figure 1, when looking at the page with the positive direction of the Z-axis pointing upwards, the right side figure (the figure in which the X-Y-Z coordinates are expressed with the direction perpendicular to the page being the Y-axis) is the mold. It is a figure which conceptually shows an example of the discharge flow and stirring flow when seen from the long side part side. In the diagram 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. Further, the size of the circle of the symbol with a ● inside the ○ and the symbol with an x inside the ○ in the molten steel M indicates the flow velocity of the molten steel M. In the diagram on the left side of FIG. 1, the sizes of the circles are the same, indicating that the flow velocities are the same. Note that the right side view of FIG. 1 shows only a half area of the mold in the casting width direction (X-axis direction).

The electromagnetic stirring device has iron cores 110 and 120 and coils 130 and 140.
When operating the electromagnetic stirring device, for example, by passing a three-phase alternating current through the coils 130 and 140, the molten steel M in the end region in the casting thickness direction (Y-axis direction) is stirred in the casting width direction. (X-axis direction) to generate mutually opposite traveling magnetic fields. This traveling magnetic field generates 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 circulates along the inner wall surfaces of a set of long sides 151, 152 and a set of short sides 153 of the mold in a horizontal plane. Although not shown in FIG. 1, in addition to the short side part 153, there is a short side part having the same structure as the short side part 153 so as to be line symmetrical with respect to the short side part 153 with the axis A of the mold as the axis of symmetry. is placed. The electromagnetic stirring device uses such a stirring flow to prevent air bubbles and foreign matter (inclusions, etc.) from adhering to the surface of a slab that is continuously cast in continuous casting equipment and remaining within the slab. That is, the electromagnetic stirring device is a device whose purpose is to improve the quality of the surface of the slab.

As shown in the diagram on the left side of FIG. 1, in a general electromagnetic stirring device, the surfaces of the iron cores 110 and 120 of the electromagnetic stirring device that face the long sides 151 and 152 of the mold with a gap in the casting direction ( Z-axis direction), and the distance between the iron cores 110, 120 and the long sides 151, 152 of the mold is constant. Note that back plates 161 and 162 are arranged on the back surfaces of the long sides 151 and 152 of the molds (the surfaces opposite to the surfaces located on the molten steel M side) for supporting and cooling the molds. A back plate 163 is also arranged on the back side of the short side portion 153 of the mold.

Here, an example is shown in which 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 M level (meniscus). Further, here, a case will be exemplified in which 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. Here, the discharge flow refers to the flow of molten steel M discharged from the discharge port 170a of the submerged nozzle 170 before changing to an upward flow or a downward flow.

In this case, the stirring force applied to the molten steel M from the electromagnetic stirring device is the same in the region within the hollow part of the mold from the upper end position to the lower end position of the iron cores 110, 120 in the casting direction (Z-axis direction). Become. Therefore, the flow velocity of the stirring flow is also approximately the same (see that the lengths of the white arrow lines in the right-hand diagram 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 upward flow and downward flow generated by the collision also become faster. As the upward flow becomes faster, fluctuations in the level of the molten steel M and the amount of powder P involved in the molten steel M increase. Furthermore, when the downward flow becomes faster, inclusions and bubbles penetrate deeper downward, solidify without floating, and the amount remaining in the slab increases. As described above, when a fast stirring flow is added 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 the fast stirring flow collides with the solidified shell S shown in FIG. 3, the solidified shell S may be remelted due to the collision. When the solidified shell S is remelted, the solidified shell S is torn starting from the remelted portion, which may lead to operational troubles such as molten steel leakage (breakout), and in this case, productivity is significantly inhibited.

In a general electromagnetic stirring device, if the stirring flow is slowed down to suppress the deterioration of the quality inside the slab or the remelting of the solidified shell S, the original purpose of the electromagnetic stirring device is to improve the quality of the slab surface. Unable to make sufficient improvements. On the other hand, if the stirring flow is made faster, the stirring flow will be added to the discharge flow, causing impurities to remain in the molten steel M, making it impossible to sufficiently improve the quality inside the slab, and causing the solidified shell S to be remelted. , negatively impacting productivity. As described above, in a general electromagnetic stirring device, there is a trade-off relationship between improving the surface quality of the slab and improving the internal quality and productivity.

Therefore, the present inventors made the discharge flow interfere with the stirring flow in a region close to the position of the submerged nozzle 170 in the casting width direction (X-axis direction), and in other regions, the discharge flow interfered with the stirring flow. I came up with the idea that stirring should be done in a way that suppresses interference. In this way, the flow of the molten steel M can be dispersed 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 speeds of the upward flow, the downward flow, and the flow colliding with the solidified shell S can be slowed down. Therefore, it is possible to reduce the amount of powder P, air bubbles, and inclusions caught in the molten steel M, and further to suppress remelting of the solidified shell S.

The embodiments of the present invention have been made based on the above circumstances. Embodiments of the present invention will be described below with reference to the drawings. Note that the comparison objects are the same in terms of length, position, size, spacing, etc., as well as cases in which they are strictly the same, and items that are different within the scope of the invention (for example, due to tolerances determined at the time of design). This shall also include items that are different within the scope.

(First embodiment)
First, a first embodiment will be described.
FIGS. 2A and 2B are cross-sectional views showing an example of a schematic configuration of continuous casting equipment in which the electromagnetic stirring device of this embodiment is installed. 2A is a sectional view taken along line II in FIGS. 3A and 3B, and FIG. 2B is a sectional view taken along line II-II in FIGS. 3A and 3B. FIGS. 3A and 3B are vertical cross-sectional views showing an example of a schematic configuration of continuous casting equipment equipped with the electromagnetic stirring device of this embodiment. FIG. 3A is a sectional view taken along line II in FIGS. 2A and 2B. FIG. 3B is a sectional view taken along line II-II in FIG. 2A.
2A, 2B, 3A, and 3B, the continuous casting equipment of this embodiment includes a mold having long sides 211, 212 and short sides 213, 214, back plates 221, 224, and an immersion nozzle. 230, and an electromagnetic stirring device having iron cores 241, 242 and coils 251, 252.

The mold is a mold for cooling and solidifying the molten steel M into a predetermined shape and continuously casting a steel piece having a predetermined width and thickness. As shown in FIGS. 3A and 3B, a solidified shell S is formed on the inner wall surfaces of the long sides 211 and 212 and the short sides 213 and 214 in the lower region of the mold. Note that since the solidified shell S grows as it cools, the thickness of the solidified shell S increases as it goes toward the negative direction of the Z-axis. When the entire piece solidifies, it becomes a slab.

As shown in FIGS. 2A and 2B, the horizontal cross-section of the hollow part of the mold is rectangular. The lateral (long side) direction (X-axis direction) of the hollow part of the mold shown in FIGS. 2A and 2B is the casting width direction (width direction of the steel billet). Further, the longitudinal (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 billet). Further, the direction (Z-axis direction) perpendicular to the paper plane of FIGS. 2A and 2B is the casting direction (longitudinal direction of the slab).

A mold having such a configuration has long side portions 211 and 212 that are arranged facing each other with a gap in the casting thickness direction (Y-axis direction), and long side portions 211 and 212 that have a gap in the casting width direction (X-axis direction). The short side portions 213 and 214 are arranged to face each other. By adjusting the positions of the short sides 213 and 214 in the casting width direction (X-axis direction), the length of the hollow part of the mold in the long side direction (casting width direction) can be adjusted. Note that the length of the hollow portion of the mold in the long side direction (casting width direction) is shorter than the length of the electromagnetic stirring device (iron cores 241, 242) in the casting width direction. On the other hand, the positions of the long sides 211 and 212 of the mold can also be adjusted, and by adjusting the positions of the long sides 211 and 212 and replacing the short sides 213 and 214 with ones of the desired size, The length of the hollow part of the mold in the short side direction (thickness direction of the steel piece) can be adjusted.

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

As shown in FIGS. 2A and 3A, a submerged nozzle 230 is placed in the hollow part of the mold. In FIG. 3, only the region on the tip side of the submerged nozzle 230 is shown. The immersion nozzle 230 is arranged so that the axis of the immersion nozzle 230 and the axis of the hollow part of the mold coincide. 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 immersed nozzle 230 when the immersed nozzle 230 is cut along the axis of the immersed nozzle 230 and along the casting width direction (X-axis direction). Similarly 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 side wall region on the tip 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 line-symmetric relationship with the axis of the immersion nozzle 230 as an axis of symmetry. Here, an example is shown in which the discharge ports 230a and 230b open diagonally downward toward the short sides 213 and 214. Therefore, molten steel M is discharged downward from the mold from the discharge ports 230a and 230b. Here, the discharge angle θ of the immersion nozzle 230 (at the discharge ports 230a, 230b) is represented by the smaller angle between the horizontal direction and the inclination angle of the discharge ports 230a, 230b. In the example shown in FIG. 4, the discharge ports 230a and 230b are inclined downward (negative direction of the Z axis). The absolute values of the ejection angle θ at the ejection port 230a and the ejection angle θ at the ejection port 230b are the same.

Note that the position of the immersion nozzle 230 in the height direction of the hollow part of the mold can be adjusted. Furthermore, in order to prevent the discharge ports 230a and 230b from becoming clogged, the molten steel M is discharged while blowing inert gas such as argon gas (Ar gas). The immersion nozzle 230 itself can be realized using a known technique, and is not limited to that shown in FIG. 4.

The electromagnetic stirring device applies 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 filling the upper part of the mold, thereby stirring the molten steel M. This device stirs molten steel M by applying force F to generate a stirring flow that circulates along the inner wall surfaces of long sides 211, 212 and short sides 213, 214 of the mold.

The electromagnetic stirring device is a linear motor, and includes iron cores 241 and 242 that are arranged to face each other with a gap between them via long sides 211 and 212, and coils that are wound around the iron cores 241 and 242. 251 and 252.

The present embodiment will be described using an example in which three-phase alternating current is applied to the coils 251 to 252. Therefore, each of the coils 251 to 252 includes a plurality of coils for each phase. In FIGS. 2A and 2B, U, V, W, -U, -V, and -W are supplied with U phase, V phase, W phase, -U phase, -V phase, and -W phase alternating current, respectively. Indicates that it is a coil. Here, the phase whose phase is 60 degrees ahead of the U phase is the -W phase. Similarly, the phase that is 120 degrees ahead of the U phase is the V phase, the phase that is 180 degrees ahead of the U phase is the -U phase, the phase that is 240 degrees ahead of the U phase is the W phase, and the phase that is 300 degrees ahead of the U phase is the -U phase. The current phase is -V phase. Note that the method of energizing the coils 251 and 252 for generating the stirring flow is well known, as described in Patent Document 5, for example, so detailed explanation thereof will be omitted here.

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

In FIG. 5, the iron core 241 has a generally T-shape when viewed from the casting thickness direction (Y-axis direction). In this way, the iron core 241 has a shape that is symmetrical in the casting width direction, with the plane of symmetry passing through the center of the iron core 241 in the casting width direction (X-axis direction) and extending in the casting direction (Z-axis direction).
Further, the symmetry plane of the iron core 241 (the plane passing through the center of 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 axis of the immersion nozzle 230 is The position of the shaft in the casting width direction and the position of the symmetry 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 yoke portion 241b.
In this embodiment, the iron core 241 is made of a soft magnetic material plate (for example, a grain-oriented electrical steel sheet or a non-oriented electrical steel sheet) that has the same shape and size as the cross section perpendicular to the height direction (Z-axis direction) of the iron core 241. ) are stacked in the height direction (Z-axis direction). Therefore, at each position in the height direction (Z-axis direction) of the iron core 241, there is no boundary line between the comb tooth portion 241a and the yoke portion 241b.

The comb tooth portion 241a has a plurality of first rectangular parallelepiped portions 510, 520 and a plurality of second rectangular parallelepiped portions 530. The plurality of first rectangular parallelepiped parts 510, 520 and the plurality of second rectangular parallelepiped parts 530 are arranged at equal intervals along the casting width direction (X-axis direction). Moreover, the plurality of first rectangular parallelepiped parts 510, 520 and the plurality of second rectangular parallelepiped parts 530 are arranged to face the long side part 211 of the mold (and the back plate 221) with a gap therebetween.

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

The area from one end to the other end in the casting width direction (X-axis direction) of the second rectangular parallelepiped portion 530 arranged at equal intervals along the casting width direction (X-axis direction) is the discharge port 230a, 230b. (In FIG. 2B, the range in the X-axis direction of the iron core 241 is the area in the X-axis direction of the immersion nozzle 230. ).

The height direction of the first rectangular parallelepiped sections 510, 520 and the second rectangular parallelepiped section 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 portions 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 section 530 are the same.

The yoke section 241b has one third rectangular parallelepiped section 540 and one fourth rectangular parallelepiped section 550.
The surface of the third rectangular parallelepiped part 540 on the long side 211 side of the mold (the positive direction side of the Y axis) is the same as the long side part 211 of the mold of the first rectangular parallelepiped part 510, 520 and the second rectangular parallelepiped part 530. Connects to the opposite side and the opposite side. The surface of the fourth rectangular parallelepiped section 550 on the long side 211 side of the mold (the positive direction side of the Y axis) is the surface opposite to the surface of the second rectangular parallelepiped section 530 that faces the long side 211 of the mold. Connect. The upper end surface of the fourth rectangular parallelepiped section 550 (the end surface on the upstream side in the casting direction) is connected to the lower end surface of the third rectangular parallelepiped section 540.

The length of the third rectangular parallelepiped portion 540 in the casting width direction (X-axis direction) is the same as that of the first rectangular parallelepiped portions 510, 520 and It is the same as the length in the casting width direction (X-axis direction) from one end to the other end of the rectangular parallelepiped portion 530 of No. 2 in the casting width direction (X-axis direction). The height direction of the third rectangular parallelepiped portion 540 is the same as the casting direction (Z-axis direction).

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

Further, the upper end surface of the third rectangular parallelepiped section 540 and the upper end surfaces of the first rectangular parallelepiped sections 510, 520 and the second rectangular parallelepiped section 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 section 540 in the height direction is the same as the length of the first rectangular parallelepiped sections 510 and 520 in the height direction. Among the lower end surfaces of the third rectangular parallelepiped section 540, the surfaces connected to the first rectangular parallelepiped sections 510 and 520 are flush with the lower end surfaces of the first rectangular parallelepiped sections 510 and 520.

The height direction of the fourth rectangular parallelepiped portion 550 coincides with the casting direction (Z-axis direction). The length of the fourth cuboid part 550 in the height direction is the same as the length of the second cuboid part 530 minus the length of the first cuboid part 510 or 520 in the height direction. It is. The upper end surface of the fourth rectangular parallelepiped section 550 is connected to the lower end surface of the third rectangular parallelepiped section 540.
There is no boundary line in the areas where the first rectangular parallelepiped parts 510, 520, the second rectangular parallelepiped part 530, the third rectangular parallelepiped part 540, and the fourth rectangular parallelepiped part 550 are interconnected.

Of the first rectangular parallelepiped parts 510, 520 and the second rectangular parallelepiped part 530, the coil 251 is arranged in a region between two rectangular parallelepiped parts adjacent to each other along the casting width direction (X-axis direction). The coil 251 is not arranged on the plane of the rectangular parallelepiped portion on the side of the mold 211). In this way, the coil 251 is wound in the casting width direction (X-axis direction) of the mold (that is, the axis (coil axis) 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 sections 510 and 520, the second rectangular parallelepiped section 530, the third rectangular parallelepiped section 540, and the fourth rectangular parallelepiped section 550. Therefore, the length of the coil 251 is longer than the length of the coil 251 in the casting width direction ( The portion disposed in the region between the two second rectangular parallelepiped portions 530 that are adjacent to each other along the X-axis direction is longer.

In FIG. 5, this embodiment will be described using an example in which the electromagnetic stirring device has five magnetic poles P1 to P5. Three-phase alternating current is supplied to each coil (three in this embodiment) of P1 to P5, and P1 to P5 are adjacent to each other along the casting width direction (X-axis direction) of the iron core 241. are out of phase with each other by 180 degrees, so each of P1 to P5 can be regarded as one unified pole. For example, when the magnetic pole P1 is the north pole, the magnetic poles P2, P3, P4, and P5 are the south pole, the north pole, the south pole, and the north pole, respectively. In addition, in this embodiment, the cross-sectional area (perpendicular to the casting width direction (X-axis direction)) of the iron core 241 surrounded by the parts (coils) constituting the same magnetic poles P1 to P5 is the same. I will make it happen. This is preferable because it is possible to suppress the occurrence of three-phase unbalance. In addition, in FIG. 5, a second rectangular parallelepiped section 530 between the U phase of the magnetic pole P1 and the -V phase of the magnetic pole P2, and a second rectangular parallelepiped section 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 530 may be the same as the length in the height direction of the first rectangular parallelepiped part 510, and the first rectangular parallelepiped part may be formed. Alternatively, the length of the fourth rectangular parallelepiped part 550 in the casting width direction may be shortened by the length of the second rectangular parallelepiped part in the casting width direction (X-axis direction) whose length in the height direction has been changed. good.

In the example shown in FIGS. 3A and 3B, the positions of the lower end surfaces of the first rectangular parallelepiped parts 510, 520 and the third rectangular parallelepiped part 550 in the casting direction (Z-axis direction) and the discharge ports 230a, 230b of the immersion nozzle 230 are The position of the upper end (the end on the upstream side in the casting direction) coincides with the position Z2. Further, the iron cores 241 and 242 have a line-symmetrical relationship with the axis of the mold as an axis of symmetry. Further, the position of the upper end surfaces of the iron cores 241 and 242 (the upper end surfaces of the first rectangular parallelepiped parts 510 and 520, the second rectangular parallelepiped part 530, and the third rectangular parallelepiped part 540) in the casting direction (Z-axis direction) is at position Z1. matches. Further, the positions of the lower end surfaces of the iron cores 241 and 242 (the lower end surfaces of the second rectangular parallelepiped section 530 and the fourth rectangular parallelepiped section 550) in the casting direction (Z-axis direction) coincide at position Z4. Further, a 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 long side portion 211, the back plate 221, the iron core 241, and the coil 251 are replaced with the long side portion 212, the back plate 222, the iron core 242, and the coil 252, respectively. Therefore, 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 stirring device of this embodiment. FIG. 6 is a diagram corresponding to FIG. 1, and the notation method is the same as in FIG. In addition, in the diagram on the left side of Fig. 6, the larger the size of the circle with a ● inside the ○ and the symbol with an × inside the ○ in the molten steel M, the greater the stirring force F. Indicates that it is large.

In this embodiment, the iron cores 241 and 242 are configured so that the shape when viewed from the casting thickness direction (Y-axis direction) is approximately T-shaped. The iron cores 241 and 242 are arranged so that the position of the axis of the immersion nozzle 230 in the casting width direction (X-axis direction) is the same as the position of the center of the casting width direction of the iron cores 241 and 242 in the casting width direction. Here, the T-shaped horizontal line area is defined as the second area, and the vertical line area is defined as the first area. In this embodiment, the region above the upper ends of the discharge ports 230a, 230b of the submerged nozzles 230 of the iron cores 241, 242 is defined as the second region, and Let the area below be the first area. Therefore, as shown in FIG. 6, in the region above the upper ends of the discharge ports 230a, 230b of the submerged nozzle 230, a fast stirring flow can be generated, similar to 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 central region in the casting width direction (X-axis direction), and the discharge in this region The discharge flow can be dispersed by interfering with the interference flow. Since the generation of stirring flow is suppressed in the end region 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 velocity of the upward flow, downward flow, and flow colliding with the solidified shell S generated on the short sides 213 and 214 of the mold, a high stirring flow is maintained in the region above the upper end of the immersion nozzle 230. It is possible to realize stirring of the molten steel M by. As a result, even if the positions of the discharge ports 230a and 230b of the immersion nozzle 230 in the casting direction and the position of the electromagnetic stirring device in the casting direction overlap, interference between the discharge flow and the stirring flow can be suppressed, and the slab It is possible to simultaneously improve surface quality, internal quality, and productivity.

In addition, the surfaces of the iron cores 241, 242 (the first region and the second region of the molds) facing the long sides 211, 212 of the molds are 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, 242 and the long side portions 211, 212 of the mold, and the distance between the second region of the iron cores 241, 242 and the long side portions 211, 212 of the mold. can be kept constant. Therefore, the electromagnetic steel sheets constituting the first region and the electromagnetic steel sheets constituting the second region can be the same, and a stable stirring flow can be generated.

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

The stirring force Fx is a stirring force that acts on the molten steel M at a position 10 mm inside from the long side of the mold. FIG. 7(a) shows the stirring force Fx near the molten metal surface (meniscus) (a region whose position in the casting direction (Z-axis direction) is within the range of the second region). FIG. 7B shows the stirring force Fx in a region where the position in the casting direction is the same as the vicinity of the lower ends of the iron cores 241 and 242 (a region whose 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 stirring device, the length of the yoke part in the casting direction (Z-axis direction) and the length of each rectangular parallelepiped part of the comb tooth part in the casting direction (Z-axis direction) are the same in all areas. The upper and lower end surfaces of the yoke portion are made to coincide with the upper and lower end surfaces of each rectangular parallelepiped portion of the comb tooth portion. The electromagnetic stirring device of this embodiment is the same as a general electromagnetic stirring device except for the length in the casting direction (Z-axis direction) of each rectangular parallelepiped portion of the comb tooth portion and the yoke portion.

As shown in graphs 701 and 702 in FIG. 7(a), the electromagnetic stirring device of this embodiment can generate a large stirring force Fx near the hot water surface (meniscus) like a general electromagnetic stirring device. can. Thereby, the quality of the slab surface can be improved.

Furthermore, as shown in graphs 703 and 704 in FIG. 7(b), even in a region where the position in the casting direction is the same as near the lower end of the iron core 241242, in the region on the center side in the casting width direction, the electromagnetic stirring device of this embodiment However, it is possible to generate a large stirring force Fx like a general electromagnetic stirring device. This allows the discharge flow to be dispersed.

On the other hand, as shown in graphs 703 and 704 in FIG. 7B, in the region where the position in the casting direction is the same as that near the lower ends of the cores 241 and 242, in the region on the end side in the casting width direction, the electromagnetic By using the stirring device, the stirring force Fx can be reduced compared to the case where a general electromagnetic stirring device is used. Therefore, the flow speeds of the upward flow, the downward flow, and the impinging flow against the solidified shell S can be reduced, and it is possible to prevent the slab from being continuously cast while the powder P, bubbles, and inclusions are caught in the molten steel M. Furthermore, re-dissolution of the solidified shell S can be suppressed. Therefore, the quality and productivity of the inside of the slab can be improved.

<Modified example>
In this embodiment, the second region (first rectangular parallelepiped portions 510, 520 and third rectangular parallelepiped portion 550) includes the region above the upper ends of the discharge ports 230a, 230b of the immersion nozzle 230 of the iron cores 241, 242. Let us take as an example the case where the position of the lower end in the casting direction (Z-axis direction) coincides with the position of the upper end (end on the upstream side in the casting direction) of the discharge ports 230a, 230b of the immersion nozzle 230 at position Z2. explained. However, it is not necessary to do this. For example, the position in the casting direction (Z-axis direction) of the lower end of the second region of the iron cores 241, 242, which includes the region above the upper ends of the discharge ports 230a, 230b of the immersion nozzle 230, is at position Z2 (of the immersion nozzle 230). From the position of the upper end of the discharge ports 230a, 230b in the casting direction (Z-axis direction) to position Z3 (the position of the tip surface of the immersion nozzle 230 (downstream end surface in the casting direction) in the casting direction (Z-axis direction)) The position can be anywhere in the range. Since the discharge direction of the discharge flow discharged from the immersion nozzle 230 is diagonally downward, within such a range, the second region including the 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 in the casting direction (Z-axis direction) is lower than the position of the upper end of the discharge ports 230a, 230b of the submerged nozzle 230 in the casting direction (Z-axis direction), the discharge flow and stirring Since the area where the flow interferes can be reduced, the effect of reducing the flow velocity of the upward flow and downward flow generated on the short sides 213 and 214 sides of the mold and the flow colliding with the solidified shell S can be achieved. can.

Further, the position in the casting direction (Z-axis direction) of the lower end of the second region including the area above the upper ends of the discharge ports 230a, 230b of the immersion nozzle 230 is the upper end of the discharge ports 230a, 230b of the immersion nozzle 230. (the upstream end in the casting direction), it is possible to reduce the area where the discharge flow and the stirring flow interfere, so that the interference occurs on the short sides 213 and 214 of the mold. This may be done because the effect of reducing the flow velocity of the upward flow, downward flow, and flow colliding with the solidified shell S can be achieved.

However, as in the present embodiment, the position 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 discharge port of the immersion nozzle 230. By aligning the positions of the upper ends of the immersion nozzles 230a and 230b, interference between the discharge flow and the stirring flow can be more reliably suppressed, and the upper end of the discharge ports 230a and 230b of the submerged nozzle 230 This is more preferable because the stirring force F can be generated over a wide area.

Furthermore, non-magnetic and non-conductive rectangular parallelepiped sections may be arranged below the first rectangular parallelepiped sections 510 and 520 and the third rectangular parallelepiped section 540, respectively. The lengths of the non-magnetic and non-conductive rectangular parallelepiped portion in the casting width direction (X-axis direction) and casting thickness direction (Y-axis direction) are the same as the lengths of the first rectangular parallelepiped portions 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 nonmagnetic and nonconductive 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 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 meet the second The non-magnetic and non-conductive rectangular parallelepiped portion is arranged so that the lower end surfaces of the fourth 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 cores 110 and 120 of the general electromagnetic stirring device shown in FIG.
Further, the comb tooth portion 241a may not be provided. In this case, the surface facing the long sides 211 and 212 of the mold in the second region including the region above the upper ends of the discharge ports 230a and 230b of the immersion nozzle 230 becomes one plane, and the plane is This becomes the surface of the first rectangular parallelepiped section 510, 520 and the second rectangular parallelepiped section 530 that faces the long side section 211 of the mold.

Moreover, in this 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 the diagonally downward direction. For example, the discharge direction of the discharge stream discharged from the immersion nozzle may be diagonally upward or horizontally.

Considering cases in which the discharge direction of the discharge flow discharged from the immersion nozzle is diagonally upward, diagonally downward, or horizontal, the direction of discharge flow discharged from the immersion nozzle is considered to be in the casting width direction (X-axis direction) as the longitudinal direction. 2 (a region above the lower ends of the first rectangular parallelepiped parts 510, 520 and the third rectangular parallelepiped part 540), and a first region (the first region) whose length in the casting width direction is shorter than the second region. The cores 241 and 242 may be configured to have rectangular parallelepiped portions 510, 520 and a region below the lower end of the third rectangular parallelepiped portion 540). Here, the range of the second region in the casting width direction may include the range of the first region in the casting width direction. 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 coordinate value (X-axis coordinate value) of the second region in the casting width direction includes the first region. This indicates that all coordinate values in the casting width direction of the region are included. Further, the range of the first region in the casting width direction (X-axis direction) may include the range of the immersion nozzle 230 in the casting width direction. The first region and the second region are defined by a range in the casting direction (Z-axis direction) of the second region and a range in the casting direction in which the discharge streams from the discharge ports 230a and 230b of the immersion nozzle 230 flow. The overlapping range is shorter than the overlapping range between the casting direction range of the first region and the casting direction range in which discharge flows from the discharge ports 230a and 230b of the immersion nozzle 230 flow. All you have to do is stay there. Note that in this embodiment, the upper end of the first region and the lower end of the second region coincide.

As in this embodiment, the positions in the casting direction (Z-axis direction) of the first rectangular parallelepiped parts 510 and 520 of the comb tooth part 241a and the third rectangular parallelepiped part 550 of the yoke part 241b are aligned with the immersion nozzle 230. By aligning the positions of the upper ends of the discharge ports 230a and 230b, the range of the first region in the casting direction (Z-axis direction) and the range of the casting direction (Z-axis direction) in which the discharge flow flows overlap. (See Figure 6). In this way, the area where the discharge flow and the stirring flow F interfere can be eliminated, so that the upward flow, the downward flow, and the collision flow against the solidified shell S generated on the short sides 213 and 214 of the mold can be eliminated. The flow rate can be further reduced.

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

Further, in this embodiment, the case where the number of magnetic poles of the electromagnetic stirring device is an odd number has been described as an example. However, the number of magnetic poles of the electromagnetic stirring device may be an even number. Even if the number of magnetic poles of the electromagnetic stirring device is an even number, the cross-sectional area (perpendicular to the casting width direction (X-axis direction)) of the iron cores 241 and 242 is the same as when the number of magnetic poles of the electromagnetic stirring device is an odd number. Therefore, it is preferable that the cross-sectional areas surrounded by the parts (coils) constituting the same magnetic pole be the same, since it is possible to suppress the occurrence of three-phase unbalance.

In addition, as described above, the cross-sectional areas (perpendicular to the casting width direction (X-axis direction)) of the iron cores 241 and 242, which are surrounded by the parts (coils) constituting the same magnetic pole, are made to be the same. Although it is preferable to do so because it can suppress the occurrence of three-phase unbalance, it is not necessary to do so. In other words, the cross-sectional area of the iron core (perpendicular to the casting width direction (X-axis direction)), which is surrounded by the parts (coils) that constitute the same magnetic pole, may differ depending on the position within the magnetic pole. .

Furthermore, in the present embodiment, the second rectangular parallelepiped section 530 and the fourth rectangular parallelepiped section 550 have been described using an example in which the lengths in the casting direction (Z-axis direction) are all the same. However, as shown in FIG. 8, the lengths in the casting direction (Z-axis direction) of the second rectangular parallelepiped part and the fourth rectangular parallelepiped part (the T-shaped vertical line area) may be made different. In this case, as shown in Figure 8, the cross-sectional area of the iron core (perpendicular to the casting width direction (X-axis direction)), which is the cross-sectional area surrounded by the parts (coils) that constitute the same magnetic pole. As mentioned above, it is preferable that the values are the same (as mentioned above, it is not necessarily necessary to do this).

(Second embodiment)
Next, a second embodiment will be described. In the first embodiment, only the upper side of the iron cores 241 and 242 (the second side opposite to the direction in which molten steel is discharged from the immersion nozzle) is provided with a second tube whose longitudinal direction is the casting width direction (X-axis direction). The explanation has been given by taking as an example the case where the regions (first rectangular parallelepiped parts 510, 520, and third rectangular parallelepiped part 540) are provided. In contrast, in this embodiment, a case will be described in which a region (third region) whose longitudinal direction is the casting width direction (X-axis direction) is provided not only above the iron cores 241 and 242 but also below them. As described above, this embodiment and the first embodiment differ mainly in the configuration of the iron core. Therefore, in the description of this embodiment, the same parts as in the first embodiment will be given the same reference numerals as those shown in FIGS. 2A to 8, and detailed explanation will be omitted.

FIGS. 9A and 9B are vertical cross-sectional views showing an example of a schematic configuration of continuous casting equipment equipped with the electromagnetic stirring device of this embodiment. Note that the II cross-sectional views in FIGS. 9A and 9B are the same as those in FIG. 2A in which the symbols 241, 242, 251, and 252 are replaced by 941, 942, 951, and 952, respectively, so illustration thereof will be omitted. . Also, the II-II cross-sectional views in FIGS. 9A and 9B are the same as those in FIG. 2B where the symbols 241, 242, 251, and 252 are replaced by 941, 942, 951, and 952, respectively, so their illustration is omitted. . Also, the III-III cross-sectional views in FIGS. 9A and 9B are the same as those in FIG. 2A, with the symbols 241, 242, 251, and 252 replaced with 941, 942, 951, and 952, respectively, and the immersion nozzle 230 removed. , illustration thereof is omitted.

FIG. 10 is a diagram showing an example of the configuration of the iron core 941. Note that since the iron cores 941 and 942 can be realized by the same thing, illustration of the iron core 942 is omitted here. The iron cores 941 and 942 have a line-symmetric relationship with the axis of the mold as an axis of symmetry.
In FIG. 10, the iron core 941 has an approximately E-shaped shape (the length of the upper and lower horizontal lines is the same) (= a shape obtained by rotating H by 90 degrees) when viewed from the casting thickness direction (Y-axis direction). has. The iron core 941 has a comb tooth portion 941a and a yoke portion 941b.
In this embodiment, the iron core 941 is made of a soft magnetic material plate (for example, a grain-oriented electrical steel sheet or a non-oriented electrical steel sheet) that has the same shape and size as the cross section perpendicular to the height direction (Z-axis direction) of the iron core 941. ) are stacked in the height direction (Z-axis direction). Therefore, at each position in the height direction (Z-axis direction) of the iron core 841, there is no boundary line between the comb tooth portion 941a and the yoke 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 sections 1010 to 1040 and the plurality of second rectangular parallelepiped sections 1050 are arranged at equal intervals along the casting width direction (X-axis direction). Further, the plurality of first rectangular parallelepiped parts 1010 to 1040 and the plurality of second rectangular parallelepiped parts 1050 are arranged to face the long side part 211 (and back plate 221) of the mold with a gap therebetween.

The first rectangular parallelepiped portion 1010 is located at one end of the iron core 941 in the casting direction (Z-axis direction) (positive direction side of the Z-axis = second side) and on one end of the iron core 941 in the casting width direction (X-axis direction). side (positive direction side of the X axis). The first rectangular parallelepiped portion 1020 is located at one end side (the positive direction side of the Z axis = second side) in the casting direction (Z-axis direction) of the iron core 941 and at the other end in 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 parallelepiped portion 1030 is located at the other end side (the negative direction side of the Z axis = first side) in the casting direction (Z-axis direction) of the iron core 941 and in the casting width direction (X-axis direction) of the iron core 941. It is arranged on one end side (the positive direction side of the X axis). The first rectangular parallelepiped portion 1040 is located at the other end side (the negative direction side of the Z axis = first side) in the casting direction (Z-axis direction) of the iron core 941 and in the casting width direction (X-axis direction) of the iron core 941. It is arranged on the other end side (the negative direction side of the X axis).

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

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

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

The height directions of the first rectangular parallelepiped sections 1010 to 1040 and the second rectangular parallelepiped section 1050 coincide 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 portions 1010 to 1040 in the height direction. The first rectangular parallelepiped portions 1010 to 1040 have the same shape and size. The shape and size of the second rectangular parallelepiped section 1050 are the same.

The yoke section 941b has two third rectangular parallelepiped sections 1060 and 1070 and one fourth rectangular parallelepiped section 1080.
The surface of the mold long side 211 of the third rectangular parallelepiped part 1060 (the positive direction side of the Y axis) is the same as the mold long side 211 of the first rectangular parallelepiped part 1010, 1020 and the second rectangular parallelepiped part 1050. Connects to the opposite side and the opposite side. Further, the surface of the third rectangular parallelepiped section 1070 on the long side 211 side of the mold is opposite to the surface of the first rectangular parallelepiped section 1030, 1040 and the second rectangular parallelepiped section 1050 that faces the long side section 211 of the mold. Connects to the surface.
The surface of the fourth rectangular parallelepiped section 1080 on the long side 211 side of the mold (the positive direction side of the Y axis) is the surface opposite to the surface of the second rectangular parallelepiped section 1050 that faces the long side 211 of the mold. Connect. The upper end surface of the fourth rectangular parallelepiped section 1080 (the end surface on the upstream side in the casting direction) is connected to the lower end surface of the third rectangular parallelepiped section 1060. The lower end surface (end surface on the downstream side in the casting direction) of the fourth rectangular parallelepiped section 1080 is connected to the upper end surface of the third rectangular parallelepiped section 1070.

The length of the third rectangular parallelepiped portion 1060 in the casting width direction (X-axis direction) is the same as that of the first rectangular parallelepiped portions 1010, 1020 and It is the same as the length in the casting width direction (X-axis direction) from one end to the other end of the rectangular parallelepiped portion 1050 of No. 2 in the casting width direction (X-axis direction). 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 parallelepiped portion 1070 in the casting width direction (X-axis direction) is equal to the length of the first rectangular parallelepiped portions 1030 and 1040 arranged at equal intervals along the casting width direction (X-axis direction). and the length of the second rectangular parallelepiped 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). The height direction of the third rectangular parallelepiped portion 1070 is the same as the casting direction (Z-axis direction).
The lengths in the casting width direction (X-axis direction) of the third rectangular parallelepiped portions 1060 and 1070, which are arranged at equal intervals along the casting width direction (X-axis direction), are the same.

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

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

The upper end surface of the third rectangular parallelepiped section 1060 and the upper end surfaces of the first rectangular parallelepiped sections 1010, 1020 and the second rectangular parallelepiped section 1050 are flush with each other. 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 section 1060 in the height direction is the same as the length of the first rectangular parallelepiped sections 1010 and 1020 in the height direction. Among the lower end surfaces of the third rectangular parallelepiped section 1060, the surface connected to the first rectangular parallelepiped sections 1010, 1020 is flush with the lower end surface of the first rectangular parallelepiped sections 1010, 1020.

Further, the lower end surface of the third rectangular parallelepiped section 1070 and the lower end surfaces of the first rectangular parallelepiped sections 1030, 1040 and the second rectangular parallelepiped section 1050 are flush with each other. 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 section 1070 in the height direction is the same as the length of the first rectangular parallelepiped sections 1030 and 1040 in the height direction. Among the upper end surfaces of the third rectangular parallelepiped section 1070, the surfaces connected to the first rectangular parallelepiped sections 1030 and 1040 are flush with the upper end surfaces of the first rectangular parallelepiped sections 1030 and 1040.

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 cuboid part 1080 is the length in the height direction of the second cuboid part 1050 minus twice the length in the height direction of the first cuboid parts 1010 to 1040. It is the same as the length. The upper end surface of the fourth rectangular parallelepiped section 1080 is connected to the lower end surface of the third rectangular parallelepiped section 1060, and the lower end surface of the fourth rectangular parallelepiped section 1080 is connected to the upper end surface of the third rectangular parallelepiped section 1070.
There is no boundary line in the interconnected regions of the first rectangular parallelepiped sections 1010 to 1040, the second rectangular parallelepiped section 1050, the third rectangular parallelepiped sections 1060 and 1070, and the fourth rectangular parallelepiped section 1080.

Among the first rectangular parallelepiped parts 1010 to 1040 and the second rectangular parallelepiped part 1050 as described above, the coil 951 is arranged in a region between two rectangular parallelepiped parts 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 sections 1010 to 1040, the second rectangular parallelepiped section 1050, the third rectangular parallelepiped sections 1060 and 1070, and the fourth rectangular parallelepiped section 1080.

Here, a region between two rectangular parallelepiped parts adjacent to each other along the casting width direction (X-axis direction) in the first rectangular parallelepiped part 1010, and a region between two rectangular parallelepiped parts adjacent to each other along the casting width direction (X-axis direction) in the first rectangular parallelepiped part 1030. The regions between two rectangular parallelepiped parts that are adjacent to each other along the casting direction (Z-axis 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 their positions in the casting direction (Z-axis direction).

In addition, a region between two rectangular parallelepiped parts adjacent to each other along the casting width direction (X-axis direction) in the first rectangular parallelepiped part 1020 and a region between two rectangular parallelepiped parts adjacent to each other along the casting width direction (X-axis direction) in the first rectangular parallelepiped part 1040 ) are arranged in the casting direction (Z-axis direction). The two regions that are lined up in the casting direction (Z-axis direction) differ only in their positions in the casting direction (Z-axis direction).

A region between two first rectangular parallelepiped sections 1010 and 1020 that are adjacent to each other along the casting width direction (X-axis direction), and a first rectangular parallelepiped section that is lined up with the region in the casting direction (Z-axis direction). The coil is wound so as to pass through the area between 1030 and 1040. Therefore, when winding the coil so as to pass through this area, and when winding the coil so as to pass through the area between the two second rectangular parallelepiped parts 1050 that are adjacent to each other along the casting width direction (X-axis direction). The range of the area where the coil is placed is the same in both cases. Therefore, in the casting width direction (X-axis direction), the lengths of the coils arranged in the area between two rectangular parallelepiped parts that are adjacent to each other along the casting width direction (X-axis direction) are made equal (same). be able to.

In FIG. 10, similarly to the first embodiment, this embodiment will be described using an example in which the electromagnetic stirring device has five magnetic poles P1 to P5. In this embodiment, the cross-sectional area of the iron core 941 (perpendicular to the casting width direction (X-axis direction)) and the cross-sectional area surrounded by the parts (coils) forming the same magnetic poles P1 to P5 are made to be the same. do. This is preferable because it is possible to suppress the occurrence of three-phase unbalance. In addition, in FIG. 10, a second rectangular parallelepiped part 1050 between the U phase of the magnetic pole P1 and the -V phase of the magnetic pole P2, and a second rectangular parallelepiped part 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 made the same as the length in the height direction of the first rectangular parallelepiped parts 1010 to 1040, thereby forming the first rectangular parallelepiped part. Alternatively, the length of the fourth rectangular parallelepiped part 1080 in the casting width direction may be shortened by the length of the second rectangular parallelepiped part in the casting width direction (X-axis direction) whose length in the height direction has been changed. good.

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

Further, the position Z5 of the upper end surface of the first rectangular parallelepiped portions 1030, 1040 in the casting direction (Z-axis direction) is the position Z5 of the top end surface of the immersion nozzle 230 (downstream end surface in the casting direction) in the casting direction (Z-axis direction). It is below position Z3 and above position Z4.
The length ZL [mm] in the casting direction (Z-axis direction) from position Z1 to position Z5 preferably satisfies the following formula (1).
ZL≧ZD+ZH+{(WD)÷2}×tanθ...(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, 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 interval between the inner wall surfaces of the short sides 213 and 214 of the mold in the casting width direction (X-axis direction) (see FIG. 2B). D [mm] is the outer diameter at 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 of the immersion nozzle 230 (at the discharge ports 230a, 230b).

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

In addition, in the above description, the long side part 211, the back plate 221, the iron core 941, and the coil 951 are replaced with the long side part 212, the back plate 222, the iron core 942, and the coil 952, respectively. Therefore, 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 stirring device of this 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 this 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 in the shape of an E-shape. The iron cores 941 and 942 are arranged so that the position of the axis of the immersion nozzle 230 in the casting width direction (X-axis direction) is the same as the position of the center of the casting width direction of the iron cores 941 and 942 in the casting width direction. Here, the area of the upper horizontal line of the letter E shape is defined as the second area, the area of the vertical line is defined as the first area, and the area of the lower horizontal line is defined as the third area. The regions of the iron cores 941, 942 above the upper ends of the discharge ports 230a, 230b of the submerged nozzles 230 are defined as second regions, and the regions of the iron cores 941, 942 below the upper ends of the discharge ports 230a, 230b of the submerged nozzles 230 are defined as second regions. The area is defined as a first area, and the area below the first area is defined as a third area.

Therefore, as shown in FIG. 11, in the region above the upper ends of the discharge ports 230a, 230b of the submerged nozzle 230, a fast stirring flow can be generated, similar to 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 central region in the casting width direction (X-axis direction), and the discharge in this region The discharge flow can be dispersed by interfering with the interference flow. Since the generation of stirring flow is suppressed in the end region 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. Furthermore, in the third region, similar to the second region, a fast stirring flow can be generated. Therefore, in addition to being able to further reduce the flow rate of the downward flow and the flow rate of the collision flow to the solidified shell S, the fast stirring flow in the third region allows bubbles and inclusions carried in the downward flow to enter downward. It is possible to suppress this and promote levitation. Therefore, the surface quality, internal quality, and productivity of the slab can be further improved.

In addition, the surfaces of the iron cores 941, 942 (the first region, the second region, and the third region) facing the long sides 211, 212 of the molds are replaced with the iron cores 941, 942 of the molds 211, 212, respectively. 942 (the first region, the second region, and the third region) is preferably parallel to the surface facing the surface. In this way, the distance between the first region and the long sides 211, 212 of the mold, the distance between the second region and the long sides 211, 212 of the mold, and the distance between the third region and the long sides of the mold. 211 and 212 can be made constant. Therefore, the electromagnetic steel sheets forming the first region, the electromagnetic steel sheets forming the second region, and the electromagnetic steel sheets forming the third region can be made of the same material, and a stable stirring flow can be generated. I can do it.

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

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

FIG. 12(a) shows the stirring force Fx near the molten metal surface (meniscus) (a region whose position in the casting direction (Z-axis direction) is within the range of the second region). FIG. 12(b) shows the stirring force Fx near the center of the cores 941 and 942 in the casting direction (Z-axis direction) (a region whose position in the casting direction (Z-axis direction) is within the range of the first region). FIG. 12(c) shows the stirring force Fx in a region where the position in the casting direction is the same as the vicinity of the lower ends of the iron cores 941 and 942 (a region whose 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. Incidentally, graphs 702 and 704 shown in FIG. 7 also show the stirring force Fx when using the general electromagnetic stirring device explained with reference to FIG. The operating conditions at the time are different. Therefore, graphs 702 and 1204 at the same position do not match. However, as described above, the operating conditions when graphs 1202, 1204, and 1206 were obtained are the same.

As shown in graphs 1201 and 1202 in FIG. 12(a), near the hot water surface (meniscus), the electromagnetic stirring device of this embodiment can also generate a large stirring force Fx similar to a general electromagnetic stirring device. can. Thereby, the quality of the slab surface can be improved.

Furthermore, as shown in graphs 1203 and 1204 in FIG. 12(b), even in the area where the center of the cores 941 and 942 in the casting direction (Z-axis direction) and the position in the casting direction are the same, the center side in the casting width direction In this region, the electromagnetic stirring device of this embodiment can also generate a large stirring force Fx similar to a general electromagnetic stirring device. This allows the discharge flow to be dispersed.

On the other hand, as shown in graphs 1203 and 1204 in FIG. 12(b), in the region where the center of the cores 941 and 942 in the casting direction (Z-axis direction) and the same position in the casting direction, the region on the end side in the casting width direction By using the electromagnetic stirring device of this embodiment, the stirring force Fx can be reduced compared to the case where a general electromagnetic stirring device is used. Therefore, the flow speeds of the upward flow, the downward flow, and the impinging flow against the solidified shell S can be reduced, and it is possible to prevent the slab from being continuously cast while the powder P, bubbles, and inclusions are caught in the molten steel M. In addition, re-dissolution of the solidified shell S can be suppressed.

Furthermore, as shown in graphs 1205 and 1206 in FIG. 12(c), in the area where the position in the casting direction is the same as near the lower ends of the iron cores 941 and 942, a large stirring force Fx is generated like a general electromagnetic stirring device. can be done. Therefore, the floating of powder P, bubbles, and inclusions can be promoted. Therefore, the quality inside the slab can be further improved.

<Modified example>
The present embodiment has been described using an example in which the length ZL in the casting direction (Z-axis direction) from position Z1 to position Z5 satisfies formula (1). This is preferable because many areas where the discharge flow is generated can be used as the first area. However, the first region can be determined depending on the direction of the discharge flow and the degree of the effect of suppressing 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 set to position Z5. Furthermore, within a range that satisfies equation (1), a position below the position of the lower end of the immersion nozzle 230 in the casting direction (Z-axis direction) may be set as position Z5. Further, the right side of equation (1) may be changed to [ZD+ZH+{(WD)÷2}×tanθ]÷2. Further, when the molten steel M is discharged horizontally from the discharge port of the immersion nozzle, the position of the lower ends of the discharge ports 230a, 230b of the immersion nozzle 230 in the casting direction (Z-axis direction) may be set to position Z5. In this case, for example, the position in the casting direction (Z-axis direction) of the upper end (one end) of the discharge ports 230a, 230b of the immersion nozzle 230 is set as position Z2, and the lower end (the other end) of the discharge ports 230a, 230b of the immersion nozzle 230 is The position in the casting direction (Z-axis direction) of the end (end portion) may be set as position Z5.

Moreover, in this embodiment, the case where the lower end surfaces of the iron cores 941 and 942 of the mold are located above the long sides 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 positions 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 positions of the lower end surfaces of the long sides 211 and 212 of the molds in the casting direction (Z-axis direction). In this way, the casting direction (Z-axis direction ) can be made larger. Therefore, the flow velocity of the downward flow can be further reduced, bubbles and inclusions carried in the downward flow can be further suppressed from entering downward, and floating can be further promoted. Therefore, both the surface quality and internal quality of the slab can be further improved.

In addition, in this embodiment, the distance between the second region of the iron cores 941, 942 and the long sides 211, 212 of the mold, and the distance between the third region of the iron cores 941, 942 and the long sides 211, 212 of the mold are determined. The explanation has been given using an example where the intervals are the same. However, it is not necessary to do this. There is less powder P (or no powder P) in the lower part of the mold than in the upper part. Therefore, even if the stirring force applied to the molten steel M is increased, the possibility that the powder P will be drawn into the molten steel M is lower than in the upper part of the mold. Therefore, for example, the distance between the third region of the core and the long sides 211, 212 of the mold may be shorter than the distance between the first region of the core and the long sides 211, 212 of the mold. Further, the distance between the iron core and the long sides 211 and 212 of the mold may be made shorter as the position is lower. In this way, by increasing the stirring force F, inappropriate solidification of the molten steel M can be alleviated.

Moreover, in this embodiment, the case where the lengths of the second rectangular parallelepiped part 1050 and the fourth rectangular parallelepiped part 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 in the casting direction (Z-axis direction) of the second rectangular parallelepiped part and the fourth rectangular parallelepiped part (the area of the vertical line in the shape of an "E") may be made different. In this case, as shown in FIG. 13, the second rectangular parallelepiped part and the fourth rectangular parallelepiped part 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 the cross-sectional area surrounded by the parts (coils) that constitute the same magnetic pole is As described above, it is preferable that they be the same (as described above, it is not necessarily necessary to do so).
Furthermore, various modifications described in the first embodiment can be adopted in this embodiment as well.

The embodiments of the present invention described above are merely examples of implementation of the present invention, and the technical scope of the present invention should not be construed as limited by these embodiments. It is something. That is, the present invention can be implemented in various forms without departing from its technical idea or its main features.

211-212: Long side, 213-214: Short side, 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 across the long sides of the mold;
a first coil wound around the first iron core in the casting width direction of the mold;
a second coil wound around the second core in the casting width direction of the mold;
has
By generating a traveling magnetic field in the casting width direction based on the alternating current flowing through the first coil and the second coil, the hollow part of the mold is moved from the discharge port of the immersion nozzle toward the short side of the mold. An electromagnetic stirring device that electromagnetically stirs molten metal injected into the
The first iron core and the second iron core each have a first region and a second region whose position in the casting direction is different from the first region,
The first region is a region whose range in the casting direction is a part between both ends of the first iron core and the second iron core in the casting direction,
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 smaller than that of the first region. Including the casting width direction,
A range in which the range in the casting direction of the second region overlaps with the range in the casting direction in which a discharge flow, which is a flow of molten metal from the discharge port of the immersion nozzle toward the short side of the mold, flows is better. . An electromagnetic stirring device, wherein a range in the casting direction of the first region and a range in the casting direction through which the discharge flow flows are shorter than an overlapping range. The first iron core and the second iron core are symmetrical in the casting width direction with an axis of symmetry passing through the center of the first iron core and the second iron core in the casting width direction and extending in the casting direction. The electromagnetic stirring device according to claim 1, having a shape as follows. the axis of the immersion nozzle and the axis of symmetry are parallel;
3. The position of the shaft of the immersion nozzle in the casting width direction is the same as the position of the center of the first iron core and the second iron core in the casting width direction. electromagnetic stirring device. A surface of the first region and the second region that faces the long side of the mold is parallel to a surface of the long side of the mold that faces the first region and the second region. 4. The electromagnetic stirring device according to claim 1, wherein the electromagnetic stirring device has a flat surface. The electromagnetic stirring device according to any one of claims 1 to 4, wherein the cross-sectional area in the direction perpendicular to the casting width direction of the region surrounded by the coils constituting the same magnetic pole is the same. The discharge port of the immersion nozzle is inclined toward the first side with respect to the casting width direction ,
The first side is a side in which molten metal is discharged from the immersion nozzle,
The first region includes a region on the first side of the first end of the discharge port of the immersion nozzle in the casting direction,
The first end in the casting direction of the outlet of the immersion nozzle is the second end of the outlet of the immersion nozzle in the casting direction,
The electromagnetic stirring device according to any one of claims 1 to 5, wherein the second side is an opposite side to the first side. 7. The electromagnetic stirring device according to claim 6, wherein the second region includes a region on the second side of the first end in the casting direction of the discharge port of the immersion nozzle. Molten metal is discharged diagonally downward from the discharge port of the immersion nozzle,
the first side is a lower side;
the second side is an upper side;
The electromagnetic stirring device according to claim 6 or 7, wherein the first end in the casting direction of the outlet of the immersed nozzle is an upper end of the outlet of the immersed 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. 9. The electromagnetic stirring device according to claim 8, wherein the electromagnetic stirring device is located at any position within the range of . The first iron core and the second iron core are regions having different positions in the casting direction from the first region, the second region, the first region and the second region, respectively. a third area;
The third region is located on a first side of the first region, and the second region is located on a second side of the first region.
The first side is a side in which molten metal is discharged from the immersion nozzle,
The electromagnetic stirring device according to any one of claims 1 to 9 , wherein the second side is an opposite side to the first side . 10. The surface of the third region that faces the long side of the mold is a surface that is parallel to the surface of the long side of the mold that faces the third region. The electromagnetic stirring device described in . The electromagnetic stirring device according to claim 10 or 11, wherein the length of the second region in the casting width direction is the same as the length of the third region in the casting width direction. The electromagnetic stirring device according to any one of claims 10 to 12, wherein the discharge port of the immersion nozzle is inclined toward the first side with respect to the casting width direction . 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 stirring device according to any one of claims 10 to 13, characterized in that: Let ZL [mm] be 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 of the third region in the casting direction,
ZD [mm] is the length in the casting direction from the molten metal level in the hollow part of the mold to the first end in the casting direction of the discharge port of the immersion nozzle,
ZH [mm] is the length of the discharge port of the immersion nozzle in the casting direction,
W [mm] is the interval in the casting width direction of the inner wall surface of the short side of the mold,
D [mm] is the outer diameter of the immersion nozzle at the center of gravity of the discharge port of the immersion nozzle,
θ [°] is the discharge angle of the immersion nozzle,
The electromagnetic stirring device according to any one of claims 10 to 14, characterized in that the following formula (A) is satisfied.
ZL≧ZD+ZH+{(WD)÷2}×tanθ...(A) 16. The electromagnetic stirring device according to claim 1, wherein the number of magnetic poles formed by the current flowing through the first coil and the second coil is an odd number.

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