JPH10249491A - Electromagnetic stirrer and continuous casting equipment for multi-section slabs in continuous casting - Google Patents

Abstract

(57) Abstract: The present invention provides an electromagnetic stirrer for simultaneously stirring unsolidified molten steel of a slab in continuous casting of a multi-slab slab. SOLUTION: In an electromagnetic stirrer M, an iron core 1 is formed in the shape of a rectangular tube having a rectangular cross section and a hollow inside, and electric wires 3 to 4 are formed so as to be orthogonal to each of the four sides constituting the iron core.
14, and two or more slab passages were provided in the hollow portion of the iron core. [Effect] By not disposing the iron core and the magnetic pole between the slab passages of the electromagnetic stirring device, the interval between the slabs can be minimized, and the machine width of the continuous casting facility can be greatly reduced. Can be greatly reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for continuously stirring molten steel in a slab mold or unsolidified molten steel in a shell of a slab drawn from the slab mold in a continuous casting facility for multi-slab cast slabs. The present invention relates to an electromagnetic stirring device used and a continuous casting facility using the device.

[0002]

2. Description of the Related Art In a continuous casting facility, applying a stirring force by electromagnetic induction to molten steel in a mold or unsolidified molten steel in a shell of a slab drawn from the mold improves electromagnetic properties of the slab surface, improves slab internal quality. Has a great effect on the improvement of
For this purpose, an electromagnetic stirrer is often installed.

Conventionally, an electromagnetic stirrer applied to a multi-cast slab continuous casting apparatus is configured in an eyeglass shape so as to surround each of the unsolidified molten steels of two or more cast slabs simultaneously. Japanese Patent Application Laid-Open No. Hei 5 (1993) -5 discloses that an electromagnetic stirrer is generally used in which a protruding magnetic pole is provided on the inner side of a formed iron core, a winding is arranged on the magnetic pole, and a two-phase or three-phase power source is connected to generate a rotating magnetic field. No. 146854.

FIG. 12 shows a conventional electromagnetic stirring device for a multi-section cast slab. This is an example of an electromagnetic stirrer for a two-section slab driven by a two-phase AC power supply to stir the molten steel 15b, 15b 'in the mold. This electromagnetic stirrer is used for the slab mold 2
Magnetic poles 18, 18 ′ are provided inside the iron core 1 formed in eyeglasses so as to surround b, 2 b ′, and the winding 3 is wound around the magnetic poles 18, 18 ′. In this case, the slab mold 2b,
2b ', the magnetic poles 18, on which the iron core 1 and the windings 3 are arranged,
Since 18 ′ is required, the distance Lb between the slab molds becomes large.

FIG. 13 shows a magnetic flux density distribution along the line AA in FIG. In the case of such a conventional multi-section slab electromagnetic stirrer, the width of the magnetic pole 18, which is generally called a pole arc, which is the entrance / exit portion of the line of magnetic force, can only take a limited length equal to or less than the length of each side. Even if magnetic lines of force are generated between opposing magnetic poles, the distribution of the magnetic lines of force spreads in the width direction of the magnetic poles 18 at the centers 17 and 17 ′ between the magnetic poles, so that the magnetic flux density at the center between the magnetic poles is larger than that near the magnetic poles 18. Become smaller.
At this time, the stirring center of the electromagnetic stirrer is located at the center 17,17 'between the magnetic poles where the magnetic flux density distribution is minimized. In order to stir the molten steel 15b, 15b' in the slab mold uniformly, the magnetic pole is required. Center 17, 17 'and slab mold center 16
b and 16b 'must be arranged so as to match.

[0006] In such a continuous casting apparatus for multi-section slabs, the size of the slab mold is often changed to cast several types of slabs of different sizes.

[0007]

In the case of the conventional type, the distance Lb between the slab molds becomes large. For this reason, the machine width of the continuous casting equipment has increased, and the equipment cost has increased. Further, in order to uniformly stir the molten steel 15b, 15b 'in the slab mold, it is necessary to match the centers 17, 17' between the magnetic poles of the electromagnetic stirrer with the slab mold centers 16b, 16b '. As shown at 14, the slab molds 2b, 2b '
In the case where the size is changed and used, it is often impossible to match the centers. FIG. 15 shows a magnetic flux density distribution along the line AA in FIG. As shown in this figure, the slab mold center 16b, 1
When 6b 'cannot be arranged so as to coincide with the centers 17 and 17' between the magnetic poles, the stirring center of the electromagnetic stirrer becomes the centers 17 and 17 'between the magnetic poles where the magnetic flux density distribution is minimized, and the centers 16b and 16b of the slab molds. 16b '. For this reason, the stirring center is eccentric from the center of the molten steel 15b, 15b 'in the slab mold, causing a problem that uniform stirring cannot be performed in each slab mold. Slab mold center 16b, 16b '
And the center 17,17 'between the magnetic poles have been a great constraint in planning the continuous casting equipment.

[0008]

Means for Solving the Problems As means for solving the above-mentioned problems, an iron core of an electromagnetic stirrer is formed in the shape of a rectangular tube having a rectangular cross section and a hollow inside, and each of the four sides constituting the iron core is provided with: An electric wire was wound so as to be orthogonal to each side, and two or more slab passages were formed in the hollow portion of the iron core.

Then, the above-mentioned electromagnetic stirring device was disposed on the outer periphery of the slab mold. Further, the above-mentioned electromagnetic stirring device was provided below the cast slab mold and in the unsolidified portion of the cast slab. Furthermore, the above-mentioned electromagnetic stirrer is arranged on the outer periphery of the slab mold to form a primary electromagnetic stirrer, and further, the electromagnetic stirrer is arranged below the electromagnetic stirrer and on the slab unsolidified part. As a result, a secondary electromagnetic stirring section was formed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The electromagnetic stirring device of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing a main part of the electromagnetic stirring device M. FIG. 2 is a cross-sectional view of the electromagnetic stirring device M. FIG. 3 is a graph showing the magnetic flux density distribution along the line AA in FIG. These are cases where the present invention is applied to continuous casting of a two-piece slab. As a power supply, each phase 12
This is a case where three-phase AC power supplies of U-phase, V-phase, and W-phase having a phase difference of 0 ° are used.

The iron core 1 is formed by laminating a rectangular tube-shaped magnetic body having a rectangular cross section and a hollow inside so as to surround the two slab passages 2a and 2a '. In addition, windings 3 to 14 are formed by winding wires so as to be orthogonal to each side, and twelve windings 3 to 14 are arranged on each side of the iron core 1. For example, windings 3, 4, 9, 10
Are connected to a U-phase AC power supply, and the windings 7, 8, 13, 14
Is connected to a V-phase AC power supply, and windings 5, 6, 11,
12 is connected to a W-phase AC power supply.

The number of windings 3 to 14 required when used by connecting to a three-phase power supply as in this embodiment is constituted by a minimum of six windings.
It is also possible to appropriately divide one winding into a plurality.
Such a winding system is called a distributed winding. The positions of the windings 3 to 14 on each of the four sides of the iron core 1 are such that the U-phase windings are generated such that a rotating magnetic field is generated by a combined magnetic field of U-phase, V-phase and W-phase as shown in FIG. 3,4,9,10 and V
Phase windings 7, 8, 13, 14 and W-phase windings 5, 6, 11,
The magnetic fields φU, φV, φW generated in each of
It is arranged so as to have an angle of 0 °.

Since the iron core 1, the windings 3 to 14, and the slab passages 2a and 2a 'are configured as described above, the entire surface of the hollow portion of the iron core 1 can be poled without limiting the pole arc which is the entrance and exit of the magnetic field lines. The arc could be formed. As a result, FIG.
, The magnetic flux density distribution in the hollow part of the iron core 1 becomes uniform,
Irrespective of the position of the slab passages 2a, 2a 'in the hollow portion of the iron core 1, uniform agitation is enabled such that the slab passage centers 16a, 16a' are the stirring centers. As a result, the electromagnetic stirring device M that does not require an iron core between the slab passages has been realized, and the distance La between the slab passages has been significantly reduced.

In the above description, the case where the power supply is connected to a three-phase AC power supply has been described. However, the present invention can also be applied to a two-phase power supply. The number is constituted by a minimum of four, and one winding can be appropriately divided into a plurality at the same time as the three-phase alternating current. In addition, windings 3 to 14
The conductor has a shape corresponding to the cooling method. In the case of indirect cooling by immersion cooling, a solid and water-resistant insulation is applied to the outside, and in the case of direct cooling by internal water flow, a hollow conductor is used, and the cooling capacity is improved by using both direct cooling and indirect cooling In the case of cooling, use a hollow, water-resistant insulation on the outside.

A case where the electromagnetic stirring device of the present invention is applied to a continuous casting facility will be described with reference to FIGS. FIG.
FIG. 8 is a longitudinal sectional view when the electromagnetic stirring device M is arranged in the slab mold part of the continuous casting, and FIG. 8 is a transverse sectional view of FIG. 7 taken along the line BB. The continuous caster for two-piece slab is composed of slab molds 2b, 2b 'and a continuous caster main body 20 at the upper part thereof.
a, 2a 'are formed. The electromagnetic stirring device M is a slab mold 2
b, 2b 'are disposed in the electromagnetic stirring section 19 on the outer periphery.
Disposing the electromagnetic stirrer 19 on the outer periphery of the continuous casting slab molds 2b, 2b 'and applying it to the stirring of the molten steel 15b, 15b' in the slab mold can be achieved by solidifying the molten steel 15b, 15b 'in the slab mold. There is a great metallurgical effect such that the cast crystals at the interface are constantly washed with a new molten steel flow by stirring to promote the floating of gas and inclusions. It is well known that stirring has a metallurgical effect such that the molten steel temperature is made uniform and pseudo-low-temperature casting increases the number of equiaxed crystals. The electromagnetic stirrer M of the present invention is installed in order to obtain the metallurgical effect, and no matter where the cast slab 2b is arranged in the hollow portion of the iron core, the cast slab mold center 16b becomes the stirring center. This enabled uniform stirring. Thus, by realizing an electromagnetic stirring device that does not require an iron core between the cast slabs, the distance Lb between the cast slabs could be significantly reduced.

Next, another embodiment in which the electromagnetic stirring device of the present invention is applied to a continuous casting facility will be described with reference to FIGS. FIG. 9 is a longitudinal sectional view in the case where the electromagnetic stirring device M is arranged below the continuous casting slab mold, and FIG.
Is a cross-sectional view taken along the line CC. The continuous caster for two-piece slabs is composed of slab molds 2b, 2b 'and a continuous caster main body 20 at the upper part thereof, and slab passages 2a, 2a' are formed in the continuous caster main body 20. It is formed. The electromagnetic stirring device M is disposed below the slab molds 2b, 2b 'and in the electromagnetic stirring section 19 of the slab unsolidified portions 15a, 15a'. The electromagnetic stirrer 19 is connected to the continuous casting slab mold 2b, 2
b ′ and surrounding the slab passages 2a, 2a ′, and applying the agitation of the unsolidified portion 15a in the shell of the slab drawn from the slab mold 2b to the slab It is generally well known that the cast solid crystal being crystallized in the unsolidified portion 15a has a large metallurgical effect such that it is washed by the agitated flow of molten steel, melted into fine crystals, and the number of equiaxed crystals increases. The electromagnetic stirrer M of the present invention is installed to obtain its metallurgical effect, and no matter where the slab passages 2a and 2a 'are arranged in the hollow portion of the iron core, the slab passage center 16
This enables uniform stirring such that a, 16a 'is the center of stirring. As a result, by realizing an electromagnetic stirrer that does not require an iron core between the slab molds, the distance La between the slab passages could be significantly reduced.

Next, another embodiment in which the electromagnetic stirring device of the present invention is applied to a continuous casting facility will be described with reference to FIG. FIG. 11 is a longitudinal sectional view in the case where electromagnetic stirring devices M and M 'are arranged below the slab mold part and the slab mold for continuous casting, respectively. The continuous caster for two-piece slabs is composed of slab molds 2b and 2b 'and a continuous caster main body 20 at the upper part thereof, and slab passages 2a and 2 are provided in the continuous caster main body 20.
a 'is formed. The electromagnetic stirring device M is a slab mold 2b, 2
b 'is disposed on the electromagnetic stirring section 19 on the outer periphery to form a primary electromagnetic stirring section.
9 and on the electromagnetic stirring section 19 around the unsolidified sections 15a and 15a 'of the cast slab to form a secondary electromagnetic stirring section. In this embodiment, the casting slabs 2b, 2b 'and the casting slab passage 2 are installed at any position in the hollow portion of the iron core so as to simultaneously obtain the metallurgical effects described in the above embodiments.
a, 2a ', the slab mold center 16b, 16
This enables uniform stirring such that b 'and the slab passage centers 16a, 16a' are the stirring centers. Thus, by realizing an electromagnetic stirrer that does not require an iron core between the respective slab molds and between the slab passages, the distance La between the slab molds and the distance La between the slab passages can be significantly reduced.

The above embodiment is an example in which the present invention is applied to two-section slabs, but it is apparent that the invention can also be applied to continuous casting of three or more slabs. FIG. 5 shows an embodiment in which the present invention is applied to continuous casting of three-row slabs. In this method, the iron core 1 is formed by laminating a rectangular tube-shaped magnetic body having a rectangular cross section and a hollow inside so as to surround three slab passages 2a, 2a ', 2a''. An electric wire is wound around each of the four sides so as to be orthogonal to each side, and windings 3 to 14 are formed. Twelve windings 3 to 14 are arranged on each side of the iron core 1 by three, and electromagnetic stirring is performed. An apparatus M is formed. Also in this case, similarly to the case of the two-piece slab, the magnetic flux density distribution in the AA line in the hollow portion of the iron core 1 becomes uniform, and the slab passages 2a, 2a ', 2a' ′, Uniform agitation is enabled such that the slab passage centers 16a, 16a ′, 16a ″ become the agitation centers. As a result, the distances La, La between the slab passages could be significantly reduced.

It is apparent that the present invention can be applied to continuous casting of a single cast slab. FIG. 6 shows the embodiment.
That is, the iron core 1 is formed by laminating a rectangular tube-shaped magnetic body having a rectangular cross section and a hollow inside so as to surround one slab passage 2a. Winding an electric wire so as to be orthogonal to each side to form windings 3 to 14, 12
Three windings 3 to 14 are arranged on each side of the iron core 1 to form an electromagnetic stirring device M. Thus, the present invention
Although it can be applied to continuous casting of a single large-section slab, the effect of the present invention is particularly exhibited in the case of simultaneous casting of a multi-section slab.

[0020]

According to the present invention, the following effects can be expected. 1. By eliminating the iron core and magnetic poles between the slab passages of the electromagnetic stirrer, the gap between slabs can be minimized, and the machine width of the continuous casting facility can be greatly reduced. Can be reduced. 2. By homogenizing the magnetic flux density distribution in the hollow portion of the iron core of the electromagnetic stirrer, the degree of freedom in slab arrangement is increased. For this reason, it is possible to eliminate a large constraint when planning the continuous casting equipment. 3. By homogenizing the magnetic flux density distribution in the hollow portion of the iron core of the electromagnetic stirrer, the degree of freedom in slab arrangement is increased. For this reason, it is possible to perform casting of a large-section single-section slab and a small-section multi-section slab with one electromagnetic stirring device.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of an electromagnetic stirring device of the present invention.

FIG. 2 is a cross-sectional view of the electromagnetic stirring device of the present invention.

FIG. 3 shows a magnetic flux density distribution along the line AA in FIG. 2;

FIG. 4 is a diagram showing a magnetic field generated in a hollow portion of an iron core in the electromagnetic stirring device of the present invention.

FIG. 5 is a cross-sectional view when the electromagnetic stirring device of the present invention is applied to three strips.

FIG. 6 is a cross-sectional view when the electromagnetic stirring device of the present invention is applied to a single-section large slab.

FIG. 7 is a longitudinal sectional view of a casting facility using the electromagnetic stirring device of the present invention.

FIG. 8 is a sectional view taken along line BB of FIG. 7;

FIG. 9 is a longitudinal sectional view of another embodiment of a casting facility using the electromagnetic stirring device of the present invention.

FIG. 10 is a sectional view taken along line CC of FIG. 9;

FIG. 11 is a longitudinal sectional view of another embodiment of a casting facility using the electromagnetic stirring device of the present invention.

FIG. 12 is a cross-sectional view showing a conventional electromagnetic stirring device.

FIG. 13 shows a magnetic flux density distribution along the line AA in FIG.

FIG. 14 is a cross-sectional view showing a case where the size of a slab mold is changed by a conventional electromagnetic stirring device.

FIG. 15 shows a magnetic flux density distribution along line AA in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Iron core 2a ... Slab passage 2b ... Slab mold 3-14 ... Winding 15a ... Slab unsolidified part 15b ... Molten steel in a slab mold 16a ... Slab passage center 16b ... Slab mold center 17 ... Center between magnetic poles 18 magnetic pole 19 electromagnetic stirrer 20 continuous casting machine body

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naru Honda 59-46 Nakahara, Tobata-ku, Kitakyushu-shi, Fukuoka Nippon Steel Plant Design Co., Ltd.

Claims (4)

[Claims] 1. An electromagnetic stirrer for continuously casting a multi-section slab which simultaneously stirs the multi-section slab, wherein an iron core is formed in a rectangular tube shape having a rectangular cross section and a hollow inside. In each of the four sides constituting, a wire is wound so as to be orthogonal to each piece, and in the hollow part of the iron core, two or more cast slabs are formed, wherein the multi-strip slab in continuous casting is characterized in that Electromagnetic stirrer. 2. A continuous casting facility wherein the electromagnetic stirring device according to claim 1 is provided on the outer periphery of a slab mold. 3. A continuous casting facility wherein the electromagnetic stirring device according to claim 1 is provided below a slab mold and in an unsolidified portion of the slab. 4. An electromagnetic stirrer according to claim 1 is provided on an outer periphery of a slab mold to form a primary electromagnetic stirrer, and a first electromagnetic stirrer is provided below said electromagnetic stirrer and in an unsolidified portion of the slab. A continuous casting facility wherein the electromagnetic stirring device according to 1 is arranged to form a secondary electromagnetic stirring section.