JPH01202341A - Mold for horizontal continuous casting machine - Google Patents

Abstract

PURPOSE:To restrain uneven temp. on cross sectional plane of solidified shell at initial stage in a mold and to improve stability of casting by arranging static magnetic field generator, so that magnetic flux is penetrated to the right angle to the drawing direction of a cast billet at both sides of the mold just below a feed nozzle. CONSTITUTION:By using the mold attached to the static magnetic field generator 28, continuous casting of the billet is executed under the prescribed condition. The static magnetic field generator 28 uses an electromagnet having the prescribed iron core cross section and this is arranged so that the magnetic flux is penetrated just below discharging holes of the feed nozzle 6. Intensity of the static magnetic field is set so that the max. magnetic flux density at center part of the mold 8 comes to the prescribed gauss and twin directional drawing type horizontal continuous casting is executed. By this method, the cast billet can be stably produced without any trouble, such as breakout, at the prescribed casting speed. Further, by adding an electromagnetic stirring device to generate rotating flow to the molten steel stream, the cast billet having further good surface characteristic without double skin and cold shut mark, is obtd. By this method, stability of the casting is improved and the productivity of the cast billet is improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a mold for a horizontal continuous casting machine, and particularly to a mold for a horizontal continuous casting machine, which fixes the separation point of a solidified shell to enable stable casting, and which also has excellent surface properties. Concerning a mold that can produce pieces, it is used in the field of horizontal continuous steel casting.

[Conventional technology]

In recent years, in the field of continuous casting, instead of the conventional vertical or curved continuous casting method, molten steel is injected from the bottom of the tundish into a horizontally installed mold, and the slabs produced in the mold are continuously cast in a horizontal direction. In 1983, a horizontal continuous casting method was proposed, and from the original method of drawing out only on one side, it was changed from the original drawing method to JP-A-58-13854.
The bidirectional pultrusion type horizontal continuous casting method disclosed in No. 4, which involves drawing in two contradictory horizontal directions, was proposed and put into practical use.

An outline of a conventional bidirectional drawing type horizontal continuous casting machine will be explained with reference to FIG. That is, the molten W44 stored in the tundish 2 is injected into the mold 8 through the feed nozzle 6.

A break ring 10 is set around the supply port of the feed nozzle 6 connected to the mold 8, and the mold 8 is provided with a water-cooled copper plate 12 inside. The mold 8 is vibrated from side to side in the horizontal direction by an oscillation device 14 while pinch rolls 16 pull out solidified shells, that is, slabs 18, respectively.

However, in this method, since the upper surface of the mold 8 is wide, the molten steel 4 in the mold 8 directly below the feed nozzle 6 tends to form a stagnation area 20 in the upper part, as shown in FIG. The surface becomes non-uniform, and this tendency is noticeable in the upper part. If the solidification becomes uneven, the separation point of the solidified shell will not be constant, making casting unstable and easily becoming the starting point for molten steel bleed during casting. Furthermore, if the solidification becomes uneven, the slab will have double skin and a very rough surface. Furthermore, the temperature of the melt 114 in the retention area 20 decreases, resulting in the problem that so-called cold shut marks remain on the surface of the slab, resulting in significant deterioration of the surface quality.

In the past, in order to solve these problems, attempts were made to install an electromagnetic stirring device inside the mold and actively stir the molten steel 4 to make the temperature distribution uniform, but the electromagnetic stirring device In addition to the fact that an effective flow cannot be obtained unless it is installed near the nozzle 6, there is also the problem that installing it near the feed nozzle 6 is extremely difficult due to the equipment configuration.

[Problem that the invention seeks to solve]

The purpose of the present invention is to solve the above-mentioned problems of the prior art, fix the separation point of the solidified shell, and enable stable casting.
Another object of the present invention is to provide a mold for a horizontal continuous casting machine that can produce slabs with excellent surface properties.

[Means for solving problems]

The gist of the present invention is as follows.

In other words, the mold number for a horizontal continuous casting machine that continuously draws slabs in the horizontal direction while continuously supplying molten steel into the mold from the upper part of the mold through a feed nozzle, and the mold directly below the feed nozzle. This mold for a horizontal continuous casting machine is characterized in that a static magnetic field generating device is installed so that the magnetic flux passes through both sides at right angles to the drawing direction of the slab.

The static magnetic field generator according to the present invention is effective for both electromagnets and permanent magnets. In addition to the above-mentioned static magnetic field generating device, an electromagnetic stirring device is provided for applying a rotating force to the supplied molten steel on the upper and lower sides of the mold in which the feed nozzle is used as the inner nozzle (1). The mold for a horizontal continuous casting machine described in ) is also effective in achieving the object of the present invention.

Further, the electromagnetic stirring device is effective in either a moving magnetic field type or a rotating magnetic field type.

The details of the present invention will be explained with reference to the accompanying drawings.

First, with reference to FIGS. 1 and 2, claim (1) (a case in which a self-mounted static magnetic field generator is provided) will be explained.

Both sides of the mold 8 directly below the feed nozzle 6, coil 22
, a static magnetic field generator 28 consisting of a yoke 24 and a non-magnetic material 26 is provided. In this case, a set of coils 22 is provided so that the magnetic flux coincides with the core of the feed nozzle 6 and passes through the mold 8, and a yoke 24 passing through the coils 22 is provided to prevent as much as possible attenuation of the static magnetic field due to air gaps. water-cooled copper plate 12
The mold 8 is pressed against the wall of the mold 8, and is connected to the left and right sides of the mold axis via the frame of the mold 8. As described above, the static magnetic field generating device 28 is installed on both sides of the mold 8, and the surfaces in contact with the mold 8 have opposite polarities, so that the static magnetic field that penetrates the mold 8 and the supplied molten steel 4 is generated by the feed nozzle. It can be caused to occur immediately after 6.

Although the case where an electromagnet is used as the static magnetic field generator 28 has been described above, a permanent magnet can also be used since it has the same effect. However, from the viewpoint of controllability, @i stone is practically preferable.

FIG. 3 shows an electromagnetic stirring device 30 installed above and below a mold for a bidirectional drawing type horizontal continuous casting machine to actively rotate and stir the discharge flow of the melt 144 injected from the tundish 2 into the mold 8 via the feed nozzle 6. FIG.

It is well known that electromagnetic stirring devices are installed in the secondary cooling zone below the mold and at the solidification end of conventional vertical or curved continuous casting machines, and are effective in improving the quality of slabs. However, in the horizontal series #4 machine, due to its unique equipment configuration, the electromagnetic stirring device 30 alone can only reach a retention area of 20
It is not sufficient to eliminate the above problem, and it is more effective to use it together with the static magnetic field generator 28. As the electromagnetic stirring device, either a moving magnetic field type or a rotating magnetic field type can be applied.

The above-mentioned mold for a bidirectional drawing type horizontal continuous casting machine fixes the separation point of the solidified shell to enable stable casting, and at the same time, the seventh
As shown in the figure, the mold structure that prevents surface defects such as double skin and cold shut marks on the surface of the slab due to the stagnation of the flow of molten steel 4 and the generation of a stagnation area 20 has been described. It was confirmed that it can be applied not only to molds but also to horizontal continuous casting machines with one-side pull-out molds, and that it has the same effect on improving surface quality.

[Effect]

The effect of eliminating the stagnation area 2o according to the present invention will be explained. First, the principle of generation of electromagnetic force F by the static magnetic field generator 28 according to the present invention will be explained with reference to FIG. Due to the magnetic field B generated by the static magnetic field generator 28 with respect to the flow velocity V of the discharge flow of the molten steel 4 flowing into the inside of the mold 8 from the feed nozzle 6.

An induced current i flows, and the induced current i and the magnetic field B generate an electromagnetic force F in the opposite direction to the discharge flow V. As a result, as shown in Fig. 5, in a conventional horizontal continuous casting machine, the discharged molten steel flow 4A collides with the mold 8 directly below the feed nozzle 6, and is then dispersed diagonally upward and horizontally. In order to flow in the direction, a stagnation area 20 was created in the upper part of the mold 8 around the discharge port of the feed nozzle 6, but due to the electromagnetic force F generated in the present invention, the downward flow 4A of molten steel is decelerated. As shown by solid arrows in FIG. 5, the molten steel flow 4A changes direction and is dispersed, so that the stagnation area 20 around the feed nozzle 6 is almost eliminated, and the temperature distribution of the molten steel 4 is made uniform.

Therefore, in the case of a bidirectional drawing type horizontal continuous casting machine mold,
Temperature non-uniformity in the mold cross section of the initially solidified shell is suppressed, the separation point is fixed, casting is stabilized, and the surface properties of the slab are significantly improved.

Furthermore, when the electromagnetic stirring device 30 is used in combination with the static magnetic field generator 28, vertical stirring force is further applied to the molten steel flow 4A indicated by the solid line arrow in FIG. 5, so that the molten steel flow 4A is further improved. The temperature of the molten steel is made uniform, and the effect is further improved.

〔Example〕

Example 1 Static magnetic field generator 28 of the present invention as shown in FIGS. 1 and 2
A billet of 150 m thickness x 150 ai width was continuously cast under the conditions shown in Table 1 using a mold equipped with the following.

Table 1 The static magnetic field generator 28 has an iron core cross section of 150 mm x 150 mm.
An electromagnet having a Horizontal continuous casting was carried out using a two-way drawing type.

As a result, there were no problems such as breakouts.
Stable production was possible at a casting speed of 1.5 m/min. Furthermore, the surface properties of the cast billet were good, with almost no double skin or cold shut marks, and the product was of a level that could be sufficiently supplied to the rolling process without hot scarf.

An electromagnetic stirring device was further added to the apparatus of Example 1, and the molten steel flow 4
As a result of generating a rotating flow in A, double skin is created.

A slab with no cold shut marks and a surface quality slightly better than that of Example 1 could be stably produced without any troubles such as breakouts.

For comparison, a slab was test-manufactured under the same conditions using only the electromagnetic stirring device 3o without operating the static magnetic field generator 28. As a result, the slab surface properties were compared to the slab of Example 1.2.
I found it to be much worse.

〔Effect of the invention〕

As is clear from the above embodiments, the present invention provides a horizontal continuous casting machine mold with a static magnetic field generating device on both sides of the mold directly below the feed nozzle, or in addition to the static magnetic field generating device.
By installing electromagnetic stirring devices above and below the mold centered around the feed nozzle, we were able to achieve the following effects.

(b) It is possible to suppress temperature non-uniformity in the cross section of the mold in the initial solidification shell of the mold, fix the separation point especially in the case of a bidirectional drawing mold, eliminate accidents such as breakouts, and establish casting stability. Ta.

(b) So-called double skin and cold shut marks on slabs were prevented, and the surface quality was significantly improved.

(c) (a) and (b) have made it possible to improve the productivity of slabs through horizontal continuous casting and reduce costs.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the present invention in which a mold for a horizontal continuous casting machine is equipped with a static magnetic field generating device, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, and Fig. 3. 4 is a sectional view showing another embodiment in which the electromagnetic stirring device according to the present invention is provided;
The figure is an explanatory diagram showing the effect of the static magnetic field generator according to the present invention, and Fig. 5 shows the flow of molten steel (solid arrow) produced by the static magnetic field generator according to the present invention when the same conventional device is not disposed (
Fig. 6 is a cross-sectional view showing the configuration of a conventional bi-directional drawing type horizontal continuous casting machine, and Fig. 7 is a schematic cross-sectional view showing the configuration of a conventional bidirectional drawing type horizontal continuous casting machine directly below the feed nozzle. FIG. 2 is a cross-sectional view showing a molten steel retention area generated within a mold. 2... Tandish 4... Molten steel 6... Feed nozzle 8... Mold 18... Solidified shell
20... Retention area 22... Coil 24.
... Yoke 26 ... Non-magnetic material 28 ... Static magnetic field generator 30 ... Electromagnetic stirring device

Claims (6)

[Claims] (1) In a mold for a horizontal continuous casting machine in which molten steel is continuously supplied into the mold from the upper part of the mold through a feed nozzle and slabs are continuously pulled out in the horizontal direction, both sides of the mold directly below the feed nozzle 1. A mold for a horizontal continuous casting machine, characterized in that a static magnetic field generating device is installed in the mold so that the magnetic flux passes through the slab at right angles to the drawing direction of the slab. (2) Claim (1) wherein the static magnetic field generator is an electromagnet.
Mold for the horizontal continuous casting machine described. (3) Claim (1) wherein the static magnetic field generator is a permanent magnet.
) Mold for horizontal continuous casting machine. (4) Horizontal continuous casting according to claim (1), further comprising, in addition to the static magnetic field generator, an electromagnetic stirring device that applies rotational force to the supplied molten steel above and below the mold centering on the feed nozzle. Machine mold. (5) Claim (4) wherein the electromagnetic stirring device is of a moving magnetic field type.
) Mold for horizontal continuous casting machine. (6) Claim (4) wherein the electromagnetic stirring device is of a rotating magnetic field type.
) Mold for horizontal continuous casting machine.