JP3588408B2 - Electromagnetic stirrer and continuous casting equipment for multiple cast slabs in continuous casting - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides an electromagnetic stirrer used to stir molten steel in a slab mold or unsolidified molten steel in a shell of a slab drawn from a slab mold by electromagnetic induction in a continuous casting facility for multi-section cast slabs. The present invention relates to a continuous casting facility using the apparatus.
[0002]
[Prior art]
In continuous casting equipment, applying a stirring force by electromagnetic induction to the molten steel in the mold or the unsolidified molten steel in the shell of the slab drawn from the mold has a great effect on improving the slab surface properties and improving the slab internal quality. It is effective, and for that purpose, it is common to install an electromagnetic stirrer.
[0003]
The electromagnetic stirrer applied to the continuous casting equipment for multi-section cast slabs has been designed to be a glasses-shaped iron core that surrounds each of the two or more cast slabs in order to simultaneously stir the unsolidified molten steel. Japanese Patent Application Laid-Open No. 5-146854 discloses that an electromagnetic stirrer is generally used in which a magnetic pole protruding inward is provided, 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. It is disclosed in the gazette.
[0004]
FIG. 12 shows a conventional electromagnetic stirring device for a multi-section slab. This is an example of an electromagnetic stirrer for a two-section cast slab driven by a two-phase AC power supply to stir the molten steel 15b, 15b 'in the mold. This electromagnetic stirrer is constructed by providing magnetic poles 18, 18 'inside an iron core 1 formed in an eyeglass shape so as to surround a slab mold 2b, 2b' and winding a winding 3 around the magnetic poles 18, 18 '. I do. In this case, since the magnetic poles 18, 18 'in which the iron core 1 and the windings 3 are arranged are required between the slab molds 2b, 2b', the slab mold distance Lb is increased.
[0005]
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 and exit of the magnetic field lines, 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. It is necessary to arrange the center 17, 17 'so that the center 16b, 16b' of the slab mold.
[0006]
Also, in such a continuous casting apparatus for multi-section cast pieces, casting of cast pieces of several different sizes is often performed by changing the size of the cast piece mold.
[0007]
[Problems to be solved by the invention]
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 '. In the case where the size of the slab molds 2b and 2b 'is changed and used as shown by 14, 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, when the slab mold center 16b, 16b 'cannot be arranged so as to coincide with the magnetic pole center 17, 17' due to the limitation of the continuous casting equipment, the stirring center of the electromagnetic stirrer has a magnetic flux density distribution. The center between the magnetic poles 17 and 17 'becomes the minimum, and is shifted from the center 16b and 16b' of the slab mold. 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. Matching the slab mold centers 16b, 16b 'with the magnetic pole centers 17, 17' has been a great constraint in planning a continuous casting facility.
[0008]
[Means for Solving the Problems]
As a 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 three phases are formed on each of four sides constituting the iron core so as to be orthogonal to each piece. Alternatively, an electric wire connected from a two-phase AC power supply was wound, and two or more slab passages were formed in the hollow portion of the iron core.
[0009]
And the said electromagnetic stirring apparatus was arrange | positioned at the outer periphery of the slab mold. Further, the above-described electromagnetic stirring device was provided below the slab mold and in the unsolidified portion of the slab. Furthermore, the above-mentioned electromagnetic stirrer is arranged on the periphery of the slab mold to form a primary electromagnetic stirrer, and further, the electromagnetic stirrer is arranged below the electromagnetic stirrer and in the unsolidified part of the slab. As a result, a secondary electromagnetic stirring section was formed.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
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 two-piece slabs. As a power supply, a three-phase AC power supply of U-phase, V-phase and W-phase having a phase difference of 120 ° is used.
[0011]
An iron core 1 is formed by laminating a rectangular tube-shaped magnetic body having a rectangular cross section and having a hollow inside so as to surround two slab passages 2a and 2a '. The wires are wound so as to be orthogonal to each side to form windings 3 to 14, and twelve windings 3 to 14 are arranged on each side of the iron core 1. For example, windings 3, 4, 9, and 10 are connected to a U-phase AC power supply, windings 7, 8, 13, and 14 are connected to a V-phase AC power supply, and windings 5, 6, 11 , 12 are connected to a W-phase AC power supply.
[0012]
The required number of windings 3 to 14 when used by connecting to a three-phase power supply as in this embodiment is a minimum of six, and one winding can be divided into a plurality as appropriate. . 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 set so that the rotating magnetic field is generated by the combined magnetic field of the U-phase, V-phase, and W-phase as shown in FIG. The magnetic fields φU, φV, φW generated by the 3, 4, 9, 10 and the V-phase windings 7, 8, 13, 14 and the W-phase windings 5, 6, 11, 12 each have an angle of 120 °. To place.
[0013]
By configuring the iron core 1, the windings 3 to 14, and the slab passages 2a and 2a 'as described above, the entire surface of the hollow portion of the iron core 1 is converted into a pole arc without limiting the pole arc which is the entrance and exit of the magnetic field lines. I was able to. As a result, as shown in FIG. 3, the magnetic flux density distribution in the hollow portion of the iron core 1 becomes uniform, and no matter where the slab passages 2a, 2a 'are arranged in the hollow portion of the iron core 1, the slab passage centers 16a, 16a'. , Which became the center of stirring. Thus, by realizing the electromagnetic stirring device M that does not require an iron core between the slab passages, the distance La between the slab passages can be significantly reduced.
[0014]
In the above description, the case where the power supply is connected to the three-phase AC power supply has been described. However, the power supply is also applicable to the two-phase power supply. It is composed of a minimum of four windings, and one winding can be appropriately divided into a plurality of windings simultaneously with the three-phase alternating current.
The conductors of the windings 3 to 14 have a shape corresponding to the cooling system. In the case of indirect cooling by immersion cooling, a solid and water-proof insulation is applied on 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.
[0015]
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. 7 is a longitudinal sectional view in the case where 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 cut along the line BB. 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 stirrer M is disposed in the electromagnetic stirrer 19 on the outer periphery of the slab molds 2b, 2b '. 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 involves 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 generally 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 disposed in the hollow portion of the iron core, the cast slab mold center 16b becomes the stirring center. As a result, uniform stirring was enabled. Thus, by realizing an electromagnetic stirring device that does not require an iron core between the respective cast slabs, the distance Lb between the cast slabs could be significantly reduced.
[0016]
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 a continuous casting slab mold, and FIG. 10 is a transverse sectional view of FIG. 9 taken along 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 and 2b 'and in the electromagnetic stirring section 19 of the unsolidified portions 15a and 15a' of the slabs. An electromagnetic stirrer 19 is disposed below the continuous cast slab molds 2b, 2b 'and so as to surround the slab passages 2a, 2a'. The application to the agitation of the solidified portion 15a is a large metallurgical process in which the crystallized cast crystals of the slab unsolidified portion 15a are washed by the agitated flow of the molten steel, melted into fine crystals, and the number of equiaxed crystals increases. The effect is generally well known. The electromagnetic stirring device M of the present invention is installed in order to obtain its metallurgical effect. Regardless of the position of the slab passage 2a, 2a 'in the hollow portion of the iron core, the slab passage center 16a, This enabled uniform stirring such that 16a 'became 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.
[0017]
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, 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 stirrer M is disposed on the electromagnetic stirrer 19 on the outer periphery of the slab molds 2b and 2b 'to form a primary electromagnetic stirrer. A secondary electromagnetic stirrer was formed on the electromagnetic stirrer 19 around the unsolidified portions 15a and 15a '. In this embodiment, the slab molds 2b and 2b 'and the slab passages 2a and 2a' 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. Even when the slabs are arranged, uniform stirring is enabled such that the slab mold centers 16b and 16b 'and the slab passage centers 16a and 16a' are the stirring centers. Thereby, 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.
[0018]
The above embodiment is an example in which the present invention is applied to a two-section slab, but it is apparent that the invention can also be applied to a 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 on each of the four sides so as to be orthogonal to each side to form windings 3 to 14. 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 such that the slab passage centers 16a, 16a ′, 16a ″ become the agitation center is enabled. As a result, the distances La, La between the slab passages could be significantly reduced.
[0019]
It is also clear 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. An electric wire is wound so as to be orthogonal to each side to form windings 3 to 14. Twelve windings 3 to 14 are arranged on each side of the iron core 1 by three to form an electromagnetic stirring device M. As described above, the present invention can be applied to continuous casting of a single large-section cast slab, but the effects of the present invention are particularly exhibited when multi-cast slabs are simultaneously cast.
[0020]
【The invention's effect】
The following effects can be expected by the present invention.
1. By eliminating the iron core and magnetic poles between the slab passages of the electromagnetic stirrer, the slab spacing can be minimized, and the machine width of the continuous casting facility can be significantly 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 condition when planning a continuous casting facility.
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 single-section slab with a large cross section and a multi-section slab with a small cross section 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 the 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 ... Smelt steel in a slab mold 16a ... Slab passage center 16b ... Slab mold center 17 ... Center between magnetic poles 18 magnetic pole 19 electromagnetic stirring unit 20 continuous casting machine body

Claims (4)

A continuous casting of a multi-section slab, in an electromagnetic stirring device that simultaneously foil-slices the multi-section slab, the core is formed in a rectangular tube having a rectangular cross section and a hollow inside, and each of the cores constituting the core An electric wire connected from a three-phase or two-phase AC power supply is wound on each of the four sides so as to be orthogonal to each piece, and two or more cast slab passages are formed in the hollow portion of the iron core. Stirrer for multi-section slabs in continuous casting. A continuous casting facility, wherein the electromagnetic stirring device according to claim 1 is disposed on an outer periphery of a slab mold. 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. The electromagnetic stirrer according to claim 1, wherein the electromagnetic stirrer according to claim 1 is disposed on an outer periphery of a slab mold to form a primary electromagnetic stirrer, and the electromagnetic stirrer according to claim 1 below the electromagnetic stirrer and in an unsolidified portion of the slab. A continuous casting facility wherein a secondary electromagnetic stirring section is formed by disposing the apparatus.

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