JPH03118949A - Continuous casting method and equipment - Google Patents

Abstract

PURPOSE:To control flow of molten steel in a mold, to improve cleaning effect of the molten steel at meniscus part and to produce a continuously cast slab having sound material by setting two pairs of magnets having the same polarity and two pairs of magnets having the different polarities on both faces at long wall sides of a mold at the time of continuously casting the molten steel. CONSTITUTION:The molten steel is poured into the water cooling type continuously casting mold 3 having rectangular cross sectional shape from a submerged nozzle 1, and solidified shell 4 in the molten steel is formed on inner wall of the mold and pulled out from the mold 3 as the continuously cast slab. In this case, two pairs of the magnets 21 having the same polarity are set as facing at upper side faces of the long walls 3a, 3b in the rectangular mold 3 and two pairs of the magnets 22 having the different polarities are set as facing at the lower part thereof. By controlling fluidity of the molten steel in the mold by magnetic field with the electro-magnets 21, impurity is floated up and separated and breakout in the continuously cast slab caused by remelting of the solidified shell 4 is prevented, and by accelerating flow of the molten steel near the meniscus part by shifting magnet field with the electro- magnets 22, the cleaning effect of molten steel is improved and the continuously cast slab having excellent quality is stably produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a continuous casting method and apparatus for controlling the flow of molten steel in a mold using a static magnetic field.

[Conventional technology]

Applying a braking force to the flow of molten steel in the mold of a continuous casting machine to slow its movement promotes the floating of impurities in the molten steel and is extremely effective in maintaining good quality of slabs.

As a method of applying a braking force to the molten steel flow in this manner, a method disclosed in Japanese Patent Application Laid-open No. 17856/1983 is known. FIG. 5 is a schematic vertical sectional view of the apparatus used in the method, and FIG. 6 is a schematic plan view thereof. As shown in these figures, electromagnetic coils 2, 2. 2
．． 2 will be placed. Then, a static magnetic field is applied to the molten steel flow discharged from the immersion nozzle 1 by the electromagnetic coils 2, 2.2.2, and the molten steel flow is influenced by the interaction force between the current induced in the molten steel flow and the static magnetic field. Apply braking force.

The braking force suppresses the flow velocity of the molten steel, and the short side 3 of the mold 3
b. To promote floating separation of impurities in the molten steel by reducing the downward flow velocity in 3b, and to prevent breakout due to remelting of the solidified shell by reducing the impact force of the molten steel ingot on the solidified shell. I can do it.

However, in the method described above, there is a problem in that the flow velocity near the meniscus portion is low, so that no cleaning effect can be expected in the molten steel scene.

A method for solving the above problem is disclosed in Japanese Patent Application Laid-Open No. 61-140.
There is a method disclosed in Japanese Patent No. 355. FIG. 7 is a schematic vertical sectional view of the apparatus used in the method, and FIG. 8 is a schematic plan view thereof. In this method, as shown in these figures, electromagnetic coils 2, 2,
2.2, and moving magnetic field type electromagnetic coils 5, 5 are arranged directly above the mold 3. And electromagnetic coil 2.2
, 2.2 suppress the molten steel flow velocity, and the moving magnetic field type electromagnetic coils 5, 5 promote the molten steel flow near the meniscus portion, thereby ensuring the cleaning effect.

[Problems to be Solved by the Invention] However, the method of promoting the flow of molten steel near the meniscus using a moving magnetic field electromagnetic coil as described above is difficult because the moving magnetic field electromagnetic coil is disposed directly above the mold. ,
There were problems in that workability was poor, and a device to prevent radiant heat from molten steel had to be added, making it impractical.

The present invention has been made in view of the above circumstances, and includes magnets with magnetic poles of the same polarity facing each other and magnets with magnetic poles of different polarity facing each other on both sides of the long side of the mold, and these magnets It is an object of the present invention to provide a continuous casting method and apparatus that ensure the cleaning effect of molten steel in the meniscus portion, promote floating separation of impurities present in the molten steel, and prevent breakout.

[Means to solve the problem]

The continuous casting method according to the present invention is a continuous casting method in which the flow of molten steel is controlled by a static magnetic field formed by magnets arranged oppositely on both long sides of the mold. It is characterized by arranging magnets with the same polarity and magnets with opposing polarities of different polarities, and controlling the flow of molten steel by the static magnetic fields formed by these magnets.

Further, the continuous casting apparatus according to the present invention is a continuous casting apparatus that controls the flow of molten steel by a static magnetic field formed by magnets arranged opposite to each other on both long sides of the mold. It is characterized by comprising magnets with the same polarity and opposing magnets with different polarities.

[Effect]

The magnetic field distributions of magnets with different polarities facing each other and magnets with the same polarity facing each other are shown in Figure 9. In the case of magnets with different polarities facing each other as shown in (a) in the figure, the distribution of magnetic fields extends to the center between the magnetic poles. A strong magnetic field penetrates, whereas in the case of magnets with the same polarity facing each other as shown in Cb in the figure, a strong magnetic field exists only near the magnetic poles, and the strength of the magnetic field rapidly attenuates as it moves toward the center between the magnetic poles. .

On the other hand, when a conductive fluid is passed through a region where a magnetic field exists, a current flows in the direction shown in FIG. 10, and an interaction force F with the magnetic field is generated. Conventional methods attempt to brake the flow of molten steel by utilizing this interaction force.

However, in the conventional method, the braking force is applied only to the discharge flow from the nozzle. Therefore, by applying a homopolar opposing magnetic field distribution to a place where no braking force is applied, the different polar opposing magnetic fields can be canceled out, making it possible to suppress the braking force.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof.

Fig. 1 is a schematic vertical sectional view of an apparatus for carrying out the continuous casting method according to the present invention, Fig. 2 is a schematic plan view showing the arrangement of the first electromagnet, and Fig. 3 is a schematic plan view of the arrangement of the first electromagnet. FIG. 3 is a schematic plan view showing the arrangement state.

In the figure, numeral 3 denotes a water-cooled mold having a rectangular cross section and an opening at the top, and an immersion nozzle having discharge ports 1a and lb opened on both sides is disposed at the top of the mold 3.

Further, as shown in FIG. 2, first electromagnets 21, 2121, 2121, 2121, 2121, 2121, 2121.
21 are arranged as a pair to face each other with the mold 3 interposed therebetween. and said first electromagnet 21.21.21.21
As shown in FIG.
are arranged in pairs facing each other.

The first electromagnets 2L 2L 21.21 are connected to the second electromagnets 22゜22, 2 so as not to reduce the flow rate of the molten steel flowing through the static magnetic field formed by them.
Change the magnetic field distribution so as to cancel the static magnetic field formed by 2.22.

Note that if the first electromagnets 21, 21, 21, 21 are arranged so that their opposing polarities are different, the magnetic field will penetrate to the center between the magnetic poles and a strong braking force will act on the flowing molten steel, which will cause the solidification shell to be described later. Impurities are trapped at the tip of the molten steel, making it ineffective for cleaning molten steel, making it impossible to obtain the desired effect. Further, the second electromagnets 22, 22, 22, 22 apply a magnetic force to the molten steel flowing in the static magnetic field formed by these so as to reduce the flow velocity.

When continuous casting is performed using an apparatus configured as described above,
Molten steel is supplied to the immersion nozzle 1, and its discharge port 1a,
lb is discharged into the mold 3. The discharged molten steel first passes through a static magnetic field formed by the second electromagnets 22, 22, 22, 22. During this flow, the molten steel flow is braked by the magnetic force of the magnetic field, reaches the short sides 3b, 3b of the peripheral wall of the mold 3 while its flow velocity is suppressed, and is divided into a downward flow A and an upward flow B.

The downward flow A flows below the mold 3 while being further braked by the second electromagnet 22.22.22.22.

On the other hand, the upward flow B flows along the mold 3 along the molten steel scene.
The current flows from the short sides 3b, 3b toward the immersion nozzle l, but at the time of this flow, the upward flow B is caused by the first electromagnet 21.2.
1.21.21, which allows the flow to flow without being slowed down. The molten steel is cooled in a water-cooled mold 3 to form a solidified shell 4, and the solidified shell 4 is pulled out from below the mold 3 by a roll (not shown).

Next, Table 2 shows the results of actual continuous casting using the method and apparatus described above under the conditions shown in Table 1. However, Condition 1 in Table 1 is when molten steel flow control is not performed, Condition 2 is when conventional methods and equipment are used,
Condition 3 is when the method and apparatus of the present invention is used, and Condition 4 is when the first electromagnets 21, 21, 2L 21 of this embodiment are arranged so that their opposing polarities are different. Moreover, FIG. 4 is a dimension diagram showing the dimensions of the parameter (lI-16) in Table 1, and 1. -16 and 11 to 1 in FIG. 4 correspond to each other.

In addition, A ji' of the slab surface layer in Table 2 is 0. The cluster index is the number of alumina clusters within 4 m from the surface of the long side of the slab, using the value of the above condition l as the standard value, and the A fi tOs cluster index inside the slab is The number of alumina clusters inside 40 Tsuru is expressed as an index using the value of the condition 1 as a standard value.

(Margin below) As is clear from Table 2, in the present invention, A j! A product with a small zOs cluster index and good surface quality and internal quality in slabs can be obtained.

〔Effect of the invention〕

As detailed above, in the continuous casting method and apparatus according to the present invention, a magnet with magnetic poles of the same polarity facing each other and a magnet with magnetic poles of different polarity facing each other are provided on the long sides of the mold, and these magnets In order to suppress the molten steel flow velocity and promote the molten steel flow near the meniscus by the acting force of
The present invention has excellent effects such as ensuring the cleaning effect of molten steel, promoting floating separation of impurities present in molten steel, and preventing breakout.

[Brief explanation of drawings]

FIG. 1 is a schematic longitudinal sectional view of a continuous casting apparatus according to the present invention,
Fig. 2 is a schematic plan view showing the arrangement of the first electromagnetic coil, Fig. 3 is a schematic plan view showing the arrangement of the second electromagnetic coil, and Fig. 4 is the dimensions of the parameters in Table 1. 5 is a schematic longitudinal sectional view of the device used in the conventional continuous casting method, FIG. 6 is its schematic plan view, and FIG. 7 is the device used in other conventional continuous casting methods. 8 is a schematic plan view thereof, FIG. 9 is a schematic diagram illustrating magnetic field distribution and magnetic field strength, and FIG. 10 is a diagram showing the principle of braking force action. l... Immersion nozzle 21... First electromagnet magnet 3.
...Mold 22...Second electric

Claims (1)

[Claims] 1. In a continuous casting method in which the flow of molten steel is controlled by a static magnetic field formed by magnets arranged oppositely on both long sides of the mold, opposing polarities are provided on both long sides of the mold. A continuous casting method in which magnets with the same polarity and magnets with opposing polarities of different polarities are arranged, and the flow of molten steel is controlled by the static magnetic fields formed by these magnets. 2. In a continuous casting device that controls the flow of molten steel by a static magnetic field formed by magnets arranged opposite to each other on both sides of the long sides of the mold, the polarities facing both sides of the long sides of the mold are made to be the same. A continuous casting device comprising a magnet and magnets facing each other with different polarities.