JPH04274849A - Continuous casting mold for steel - Google Patents

Abstract

PURPOSE:To secure the service life of a nozzle, to quicken the floating of an inclusion, foam, etc., and to improve the quality of cast billet by forming a static magnetic field zone in the lower part of an injection nozzle inserted into a casting mold, and moving an electromagnet in a height direction. CONSTITUTION:In about a center part in the vertical direction of a continuous casting mold 30, on the long side of the casting mold 30, the magnetic pole 10 of an electromagnet having width being roughly equal to this long side width is provided opposingly, and a static magnetic field zone 17 is generated in the casting mold 30. As for the magnetic pole 10, a clearance 10-1 is provided between the magnetic pole and the casting mold 30 so that it does not receive the vibration of the casting mold 30 at the time of casting. The electromagnet ascends/descends along the peripheral part of the casting mold 30, while maintaining its horizontal state by a mechanism consisting of a worm jack and a synchronizing shaft for supporting a yoke 5 by four points. In such a manner, even in the case a static magnetic field is applied, the service life of an injection nozzle 1 can be secured, and the increase of a refractory cost can be prevented.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention applies a braking force to the injected molten steel flow using a static magnetic field in the mold, promoting the floating of inclusions, bubbles, etc. brought into the mold, and improving the quality of slabs. This invention relates to a steel continuous casting mold that can achieve the following.

0002

[Prior Art] A technique for applying a uniform static magnetic field to molten steel in a mold over the entire width of the mold for the purpose of improving the quality of slabs produced by continuous casting is disclosed in, for example, Japanese Patent Laid-Open No. 2-284755.
Although it has been proposed in Japanese Patent Application No. 2-56608 and Japanese Patent Application No. 2-56608, no technology has been proposed so far for changing the position of the applied magnetic field in accordance with changes in operating conditions.

0003

[Problems to be Solved by the Invention] FIG. 9 shows a schematic diagram of conventional continuous casting of steel.

The molten steel flow 51 injected into the mold 30 from the injection nozzle 1 collides with the copper plate 2 on the side wall of the mold, and branches into an upward reverse flow 52 and a downward reverse flow 53, and the downward reverse flow 53 is When passing through the magnetic field zone 17, it is rectified and becomes a uniform flow 54. The applied static magnetic field band 17 is used to suppress the penetration depth of the downward reversal flow 53 in order to promote the floating of bubbles, inclusions, etc. brought into the molten steel in the mold through the injection nozzle 1, and to suppress the penetration depth of the downward reversal flow 53 to some extent near the meniscus 16 due to the upward reversal flow 52. There is an optimal position for the meniscus 16 and the injection nozzle 1 from the standpoint of ensuring flow and preventing deckle generation.

On the other hand, in actual casting, powder or granular powder is poured onto the surface of the molten metal for reasons such as keeping the molten steel warm and preventing oxidation. A mixed slag layer 55 exists.

[0006] Since this slag layer 55 easily reacts with the material of the injection nozzle 1, the portion where the injection nozzle 1 and the slag layer 55 are in contact with each other is quickly damaged by melting.
As shown in FIG. 10, it is common practice to change the positional relationship between the injection nozzle 1 and the slag layer 55 during casting.

However, in order to always maintain the meniscus 16 at an optimal position with respect to the injection nozzle 1 and to change the positional relationship between the injection nozzle 1 and the slag layer 55 during casting, an electromagnet that generates the applied static magnetic field band 17 is required. It is necessary to move up and down at appropriate times during operation, but this electromagnet is a large device consisting of a yoke 5 that surrounds the mold, an electromagnetic coil 9, a magnetic pole 10, etc. as shown in the figure. No technical idea has been proposed to remotely control this and easily move it up and down.

[0008] The present invention solves the above-mentioned problems and provides a continuous casting mold for steel that can ensure the life of the nozzle, promote the floating of inclusions, bubbles, etc., and improve the quality of the slab.

[0009]

[Means for Solving the Problems] The gist of the present invention is as follows.

[0010] Part 1 is a continuous casting mold with a rectangular cross section, at a position below the molten metal spouting part of the injection nozzle inserted into the continuous casting mold.
A steel characterized by having an electromagnet with magnetic pole faces facing each other so as to form a static magnetic field band with a width approximately equal to the width of the long side of the mold, and having a structure in which the electromagnet is separated from the mold and movable in the height direction. This is a continuous casting mold.

[0011] Part 2 is a continuous casting mold with a rectangular cross section, at a position below the molten metal spouting part of the injection nozzle inserted into the continuous casting mold.
A steel characterized in that an electromagnet is provided with magnetic pole surfaces facing each other so as to form a static magnetic field zone with a width approximately equal to the width of the long side of the mold, and a movable magnetic pole movable in the height direction is provided at the tip of the magnetic pole. This is a continuous casting mold.

Furthermore, in the steel continuous casting mold described above, the movable magnetic pole is made of a material having a higher magnetic permeability than the electromagnet magnetic pole.

[0013]

[Operation] In the present invention, electromagnets are supported by jacks or the like and driven synchronously, and while the electromagnets are maintained horizontally, the peripheral portion of the mold is raised and lowered by controlling the drive from the outside. A movable magnetic pole that is movable in the height direction is inserted between the tip of the magnetic pole and the mold, and this movable magnetic pole is raised and lowered. In this way, the continuous casting mold is capable of easily moving the static magnetic field up and down by remote control even during operation.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal cross-sectional view showing the main parts of a continuous casting mold for steel, and a cross-sectional view taken along line A-A in FIG. 2 below, and FIG. 2 is a perspective view illustrating the overall structure of the continuous casting mold. .

The mold structure is formed by copper plates 2 that are in contact with the molten steel and have a rectangular cross section.
and is firmly fixed by a mold fixing frame 4 to form a mold.

At approximately the center in the vertical direction of the mold 30, magnetic poles 10 of an electromagnet having a width approximately equal to the long side width of the mold are provided facing each other, and a static magnetic field band 17 is provided in the mold.
cause Note that 5 is a yoke surrounding the mold, and 9 is an electromagnetic coil.

A gap 10-1 is provided between the magnetic pole 10 of this electromagnet and the mold 30 so that it is not affected by the vibration of the mold during casting and is movable in the vertical direction. Note that 6 is a mold vibration table.

The static magnetic field zone 17 formed in the molten metal by the electromagnet has a magnetic flux density of 3000 to 500 from the viewpoint of the floating effect of inclusions and bubbles and the separation effect of the molten steel pool.
Approximately 0 Gauss is required, and in order to downsize the electromagnet, it is advantageous for the gap 10-1 to be narrower.

The electromagnet support and elevating mechanism is provided by the yoke 5.
It is composed of a worm jack 7a that supports the worm jack 7a at four points, and a synchronous shaft 7b that connects and drives the worm jack 7a synchronously.One of these shafts is connected to a drive device, and the electromagnet is driven from the outside while maintaining the horizontal position. The peripheral part of the mold 30 is raised and lowered in a controlled manner.

On the other hand, the position of the electromagnet relative to the mold is such that the immersion depth from the meniscus 16 of the injection nozzle is 200 mm,
Considering that the magnetic pole height of the electromagnet is about 400 mm, the distance between the meniscus 16 and the center of the magnetic pole is 400 mm, which is close to the upper limit of the electromagnet. In addition, the practical length of the mold is 1200 to 1300 m.
m and the magnetic pole height of the electromagnet is about 400 mm, the lower limit is 70
It will be about 0mm. Therefore, the movement stroke of the electromagnet is
± based on the center position of 550mm in the above range
150 mm is practical.

In this embodiment, a worm jack is used as the electromagnet support and elevating mechanism, but other mechanisms such as hydraulic drive may also be used.

Next, a second embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a sectional view showing the main parts near the center of the mold, FIG. 4 is a sectional view near both sides of the mold, and FIG. 5 is a plan view of the mold. FIG. 4 is a drawing showing a cross section taken along line B-B. Further, FIG. 6 is a sectional view taken along the line AA in FIG. 4.

The mold structure is formed by copper plates 2 in contact with molten steel with a rectangular cross section, and these copper plates 2 are attached to a mold frame 4.
a and tie rods 4b to form a mold.

At approximately the center in the vertical direction of the mold 30, magnetic poles 10 of an electromagnet having a width approximately equal to the long side width of the mold are provided facing each other, and a static magnetic field band 17 is provided in the mold.
cause Note that 5 is a yoke surrounding the mold, and 9 is an electromagnetic coil.

A movable magnetic pole 10a that is movable in the height direction is inserted between the tip of the magnetic pole 10 and the mold 30. This movable magnetic pole 10a is supported by T-grooves 20a at both ends of the mold, and is guided by these grooves to slide up and down.

A rack 8a is attached to each of the movable magnetic poles 10a at two locations on both ends thereof, and is connected to a drive shaft 8d via a pinion gear 8b and a synchronous shaft 8c, so that the pair of movable magnetic poles 10a are maintained horizontally. While moving up and down between the magnetic pole 10 and the mold 30, the drive is controlled from the outside.

FIG. 7 shows the distribution of magnetic lines of force 21 occurring in molten steel when the movable magnetic pole 10a is located approximately at the center of the magnetic pole 10 when viewed from the horizontal direction. Further, FIG. 8 shows the longitudinal magnetic flux density distribution in each case.

In FIG. 8, the magnetic flux density distribution when the movable magnetic pole 10a is located approximately at the center position 10a-1 is represented by the distribution curve 2.
It reaches its maximum at approximately the center position as shown in 2-1. Next, when the movable magnetic pole 10a is moved upward to 10a-2, the magnetic flux density distribution of the movable magnetic pole 10a is as shown by a distribution curve 22-2.
The magnetic flux density distribution when the movable magnetic pole 10a is moved downward to 10a-3 moves downward as shown by a distribution curve 22-3.

As described above, by moving the movable magnetic pole 10a up and down while keeping the electromagnet body fixed, the maximum value of the magnetic flux density distribution can be moved, that is, the same effect as that of moving the electromagnet body up and down can be produced. be.

In this case, if materials with the same magnetic permeability are used for the movable magnetic pole 10a and the magnetic pole 10, the movable magnetic pole 10a and the magnetic pole 1
Because the area where the magnetic flux density distribution 22-2 and 22-3 overlap decreases, the maximum value of the magnetic flux density distribution curves 22-2 and 22-3 decreases compared to 22-1, and there is a positional deviation from the amount of movement of the movable magnetic pole 10a. accompanied by. Therefore, in the present invention, this drawback is compensated for by using a material for the movable magnetic pole 10a whose magnetic permeability is higher than that of the magnetic pole 10.

For example, as a high magnetic permeability material, Hyperc
o, a combination of Permendur and Armco iron, etc.

In this way, by moving the movable magnetic pole 10a upward, the position of the magnetic flux density distribution can be changed, and by moving the movable magnetic pole 10a downward, the static magnetic field band 17 can be easily moved up and down. can.

On the other hand, the position of the movable magnetic pole 10a with respect to the mold is such that the immersion depth from the meniscus 16 of the injection nozzle is 20
0mm, and considering that the magnetic pole height of the movable magnetic pole 10a is about 400mm, the distance between the meniscus 16 and the magnetic pole center is 400m.
m is close to the upper limit of the movable magnetic pole 10a. Further, since the practical length of the mold is 1200 to 1300 mm and the height of the movable magnetic pole 10a is about 400 mm, the lower limit is about 700 mm. Therefore, the moving stroke h of the movable magnetic pole 10a is ±150 m based on the 550 mm position which is the center of the above range.
m is practical.

As described above, the electromagnet is supported by a jack or the like and driven synchronously, and while the electromagnet is maintained horizontally, the drive is controlled from the outside to raise and lower the peripheral part of the mold, and the mold and the mold at the tip of the magnetic pole are moved up and down. A movable magnetic pole that can be moved in the height direction is inserted between the two, and by raising and lowering this movable magnetic pole, the static magnetic field band can be easily moved up and down, and it is brought into the molten steel in the mold through the injection nozzle. A static magnetic field can be generated at the optimal position to promote the floating of bubbles, inclusions, etc., and while maintaining this optimal position, the positional relationship between the injection nozzle and the slag layer can be changed as appropriate during casting. Melting damage can be suppressed and the service life of the nozzle can be extended. In this way, the continuous casting mold is capable of easily moving the static magnetic field up and down by remote control even during operation.

[0037]

[Effects of the Invention] The present invention constructed as described above has the following effects.

[0038] Even when a static magnetic field is applied, the life of the injection nozzle can be maintained at the same level as before, and an increase in the cost of refractories can be prevented.

The static magnetic field band can always be controlled to the optimum position for the meniscus and the injection nozzle, and the effect of the static magnetic field on floating of bubbles and inclusions can be maximized.

Even with variations in casting speed, ie, variations in the flow velocity of the nozzle discharge flow, it is possible to optimize the static magnetic field band position and magnetic field strength, and stable slab quality can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing essential parts of a continuous casting mold according to a first embodiment of the present invention.

FIG. 2 is a partially cross-sectional perspective view illustrating the overall structure of a steel continuous casting mold.

FIG. 3 is a longitudinal cross-sectional view showing a main part (cross-sectional position taken along line C-C in FIG. 5) near the center of a steel continuous casting mold according to a second embodiment of the present invention.

FIG. 4 is a longitudinal cross-sectional view of the vicinity of both sides of the mold (cross-sectional position taken along line B-B in FIG. 5).

FIG. 5 is an overall plan view of a continuous casting mold.

FIG. 6 is a horizontal sectional view taken along line AA in FIG. 4;

FIG. 7 is a drawing showing the distribution of magnetic lines of force occurring in molten steel when the movable magnetic pole is located approximately at the center of the magnetic pole.

FIG. 8 is a diagram illustrating the state of movement of the vertical magnetic flux density distribution when the movable magnetic pole is moved.

FIG. 9 is a cross-sectional view illustrating the flow of molten steel in a conventional continuous casting mold.

10 is a sectional view illustrating the flow of molten steel in another embodiment in FIG. 9. FIG.

[Explanation of symbols]

1 Injection nozzle 2 Copper plate 3a Mold frame 3b Mold fixed frame 4a Mold frame 4b Tie rod 5 Yoke 6 Mold vibration table 7a Worm jack 7b Synchronous shaft 8a Rack 8b Pinion 8c Synchronous shaft 8d Drive shaft 9 Coil 10 Electromagnetic pole 10a Movable magnetic pole 10-1 Gap 16 Meniscus 17 Static magnetic field zone 20a T-slot 21 Magnetic force line distribution 22-1, 22-2, 22-3 Magnetic force distribution curve 30
Mold 51 Molten steel flow 52 Upward reverse flow 53 Downward reverse flow 54 Uniform flow 55 Slag layer

Claims (3)

[Claims] [Claim 1] At a position below the molten metal spouting part of an injection nozzle inserted into a continuous casting mold with a rectangular cross section, magnetic pole surfaces are arranged to face each other so as to form a static magnetic field band with a width approximately equal to the width of the long side of the mold. Provide an electromagnet, separate the electromagnet from the mold,
A steel continuous casting mold characterized by having a structure that is movable in the height direction. [Claim 2] At a position below the molten metal spouting part of an injection nozzle inserted into a continuous casting mold having a rectangular cross section, magnetic pole surfaces are arranged to face each other so as to form a static magnetic field band with a width approximately equal to the width of the long side of the mold. 1. A steel continuous casting mold, characterized in that an electromagnet is provided, and a movable magnetic pole movable in the height direction is provided at the tip of the magnetic pole. 3. The steel continuous casting mold according to claim 2, wherein the movable magnetic pole is made of a material having a higher magnetic permeability than the electromagnetic pole.