JPH1177258A - Electromagnetic braking device in continuous caster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize a space of the limited back surface of a mold, to enable holding of intense electromagnet capacity and to enable the fitting of the electromagnet device obtaining the necessary braking force at plural steps in a mold for casting at high speed in small size which conventionally is difficult to brake, by improving the constitution, shape, etc., of iron cores from an electromagnetic coil parts to a mold fixed part assembled in the mold, in an electromagnetic braking device applying the brake to molten steel flow in the mold. SOLUTION: In the electromagnetic device composed of the iron cores 13, electromagnetic coils 14 and yokes 15, the iron core 13 is constituted with a tip iron core part 13A, middle iron core part 13B and base end iron core part 13C. Further, the integral type deformed iron core 13 is formed by changing the direction in each part, cross sectional shape and cross sectional area so that the space of the limited back surface can effectively be utilized, and the intense electromagnet device can be obtd. by enlarging the electromagnetic coil 13 and also, the compact and intense electromagnet device can be made to arrange at many steps.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting of steel, in which a molten steel flow from an immersion nozzle for injecting molten steel into a mold is subjected to braking (brake) by a static magnetic field so that inclusions in the molten steel flow down. TECHNICAL FIELD The present invention relates to an electromagnetic brake device that reduces capture in a cast slab, and more particularly to an improvement in an electromagnet device installed on the back side of a long side of a mold.

[0002]

2. Description of the Related Art Generally, in continuous casting, molten steel in a ladle is poured into a tundish, cast into a water-cooled mold from the tundish using an immersion nozzle, and solidified around the molten steel by primary cooling of the water-cooled mold. The slab is continuously formed by growing a solidified shell by secondary cooling by spray cooling or the like while passing between a number of slab support rolls arranged below the mold, and pulling out the completely solidified slab. It is manufactured in a typical manner.

[0003] As a method of reducing the inclusions in such a continuous cast slab, there is a technique of incorporating an electromagnetic brake device in a water-cooled mold. A braking force is applied by the magnetic field to slow down the molten steel injection flow, thereby preventing inclusions contained in the molten steel from penetrating deeply into the molten portion in the solidified shell and being trapped at the solidified shell interface.

The application of such an electromagnetic brake device to continuous casting of steel is disclosed and known in Japanese Patent Publication No. 2-20349. In addition, Japanese Patent Publication 4-5998
No. 8 discloses a structure of an electromagnetic brake device in which an electromagnet device including an electromagnetic coil, a core, and a yoke is opposed to a long side of a mold having a rectangular cross section in a plan view to generate a static magnetic field between a plurality of pairs of magnetic poles. By doing so, a brake is applied to the molten steel in the mold. Normally, in the electromagnetic brake device, it is necessary to minimize the interval between the cores facing each other with the molten steel interposed from the viewpoint of increasing the efficiency of forming the magnetic field. Provide a recess in the cooling box,
A structure in which an electromagnet and a core are inserted into the recess is adopted, and the mold and the electromagnet device are integrated.

Further, recently, Japanese Patent Application Laid-Open No. Hei 5-27764 has been proposed.
No. 5 or Japanese Patent Application No. 8-1615 by the present inventor.
No. 86, etc., an electromagnetic brake device capable of separating a mold and an electromagnet device has also been proposed.

[0006]

[Problems to be solved by the invention]

(1) In an electromagnetic brake device in which a mold and an electromagnet device are integrated as described in Japanese Patent Publication No. 4-59988, the size of the mold (width and height in the long side direction of the mold) depends on the size of the mold. There is a problem that the size and braking capacity of the electromagnet device are physically determined.

(2) In a recent high-speed continuous casting machine (high-production continuous casting machine), there is a problem that a braking force necessary for controlling a molten steel injection flow from an immersion nozzle is not provided. If a sufficient braking force cannot be obtained, the above-described deceleration of the molten steel injection flow becomes insufficient, and inclusions in the molten steel penetrate deeply into the molten portion in the solidified shell. The molten steel injection flow discharged from the immersion nozzle collides with the short side wall of the mold, and this molten steel flow causes re-melting of the solidified shell, which causes a breakout.

(3) As described above, in a high-speed continuous casting machine (a casting machine having a high casting speed and therefore a large amount of molten steel per unit time), the size of the mold and the required electromagnet braking force are unmatched. It has become. Recently, there has been a method in which a plurality of electromagnet devices are provided above and below the back of a mold, and a method of controlling the upper, middle, and lower stages of the mold by braking has been used. In such a case, the required braking function cannot be obtained with the conventional electromagnet device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems at a glance, and has as its object to devise the configuration and shape of the iron core from the electromagnetic coil section to the mold fixing section incorporated in the mold. By doing so, it is possible to effectively utilize the limited space on the back of the mold and to have a strong electromagnet capability, and at the same time, in multiple stages and the necessary braking force in a small and high-speed casting mold, which was difficult in the past. It is an object of the present invention to provide an electromagnetic brake device of a continuous casting machine that can be mounted with an electromagnet device that can obtain the above.

[0010]

SUMMARY OF THE INVENTION The present invention is directed to an electromagnetic brake device provided with an electromagnet device having an iron core and an electromagnetic coil on the back of a mold of a continuous casting machine to apply a brake to a molten steel flow in the mold. Are provided with an integral deformed iron core in which at least one of the direction, the cross-sectional shape, and the cross-sectional area is different from each other in each part in the magnetic path direction.

[0011] Specifically, it is as follows. Fig. 1 (the electromagnetic coil is mounted on the outer base iron core) and Fig. 3 (the electromagnetic coil is mounted on the intermediate iron core). This is an example of the mold provided, and the iron core is fixed to the back surface of the copper plate 4 of the mold and is a fixed iron core 12 which is a part of the mold as a strength member of the mold.
(Set in the molten steel flow section where braking control is desired) and an integrated deformable iron core 13 attached to a mold frame (cooling box) 7.

(1) Appearance Shape of Integrated Modified Iron Core (Direction of Each Part) The integrated deformed iron cores 13-1 provided in the upper and lower stages,
Reference numeral 13-3 denotes a tip iron core 13A inserted into the cooling box 7 and connected to the fixed iron core 12, an intermediate iron core 13B integrally continuous with the tip iron core 13A, and an intermediate iron core 13B. Part 1
3B, the base iron core 13C is formed integrally with the base iron core 13C, and the base iron core 13C is displaced horizontally and vertically outward with respect to the distal iron core 13A. Both sides have an external shape that is bent at a right angle. The length of the intermediate iron core 13B in the horizontal direction is determined by the size of the mold and the passing position of the molten steel flow (the position at which braking control is desired,
That is, it is determined by the position of the fixed iron core 12).

An integrated deformed iron core 13-2 provided in the middle stage
Has a linear external shape that extends straight rearward. However, the present invention is not limited to this, and in the horizontal direction, as in the case of the upper stage and the lower stage, it may be possible to bend outward or to the center. It should be noted that the fixed iron core 12 and the tip iron core 13 which are a part of the strength member when designing the mold are used.
The connection with A may be determined by one positioning pin.

(2) Cross-sectional shape and cross-sectional area of the integrated deformed iron core The integrated deformed iron core 13-1 provided in the upper and lower stages,
In 13-3, the cross-sectional shape of the base iron core 13 </ b> C (in the case of FIG. 1) on which the electromagnetic coil 14 is mounted may be square, but the function of the coil is maximized, and A circular or elliptical shape is used to simplify the work and minimize the area. On the other hand, the cross-sectional shape of the intermediate iron core portion 13B is, for example, a vertically long thin quadrilateral in order to make the most of the limited physical permissible space on the back of the mold (this is an example, Various cross-sectional shapes can be adopted depending on the size of the mold). At this time, the cross-sectional area of the intermediate iron core 13B is equal to the cross-sectional area of the base iron core 13C, which is a coil part, or the cross-sectional area immediately before the magnetic flux density generated by the electromagnetic coil 14 becomes saturated. Area. The tip iron core 13A has a larger cross-sectional area than the fixed iron core 12 whose cross-sectional area is reduced in order to increase the magnetic flux density B.

In the case of FIG. 3, since the electromagnetic coil 14 is mounted on the intermediate iron core 13B, the sectional shape of the intermediate iron core 13B depends on the performance of the electromagnetic coil and the allowable space depending on the size of the mold. In consideration of the above, the shape may be appropriately selected from a circle, an ellipse, a thin quadrilateral, and the like.

An integrated deformed iron core 13-2 disposed in the middle stage
May have a constant cross-sectional area, as shown in FIG.
As shown in FIG. 2, the cross-sectional area of the base iron core 13C, which is the coil part, may be smaller than the cross-sectional area of the distal iron core 13A.

In the above configuration, the direction, cross-sectional shape, and cross-sectional area of one iron core from the electromagnetic coil portion to the mold fixed iron core portion are different from each other at each portion in the magnetic path direction. The magnetomotive force F (the exciting current I or the number of turns N of the electromagnetic coil) of the electromagnetic coil 14 can be increased in the limited space, and the magnetic flux B can be efficiently transmitted to the molten steel flow surface without reducing the magnetic flux density B. A powerful electromagnetic device can be obtained. Specifically, it is possible to make an electromagnet device having the strong electromagnet capability required for molten steel flow braking into a compact configuration, and it is possible to mount multiple stages of electromagnetic brake devices in a small and high-speed casting mold that was difficult in the past. It becomes possible.

As described above, according to the present invention, an electromagnet device capable of exhibiting the maximum magnet function by changing the outer shape, cross-sectional shape, or cross-sectional area of an iron core in a space having a limited volume. In the electromagnetic brake device shown in FIG. 5, the effect of such a change in the length of the iron core and a change in the cross-sectional area of the iron core on the magnetic flux density attenuation will be described below.

(1) Influence of iron core length

[0020]

(Equation 1)

From the above equation (4), the effective magnetic path length l ₁ is
Even now two to three times longer than conventional iron core of, μ _S
Since ≫l ₁ and μ _s ≫μ ₀ , it can be seen that the change in the magnetic flux density B in the molten steel can be almost ignored. Therefore,
Even if the length of the iron core is slightly increased as in the present invention, the effect of the magnetic flux density B can be ignored in practical use.

(2) Cross-sectional area of iron core In the iron core, generated magnetic flux Φ arbitrarily spreads over the entire cross-sectional area. In FIG. 4, the following equation holds.

[0023]

(Equation 2)

Therefore, the range of I is within the range where the iron core does not cause magnetic saturation.
Alternatively, the magnetic flux can be efficiently applied to the molten steel flow by increasing N. Note that the saturation of the magnetic flux is determined by the material of the iron core and the size of the cross-sectional area, and it is not necessary to simply increase I · N in the above equation (I
・ N has a limit). The relationship between the magnetic flux density B and Tetsushindan area S ₁ shown in FIG. The progress is shown below.

[0025]

(Equation 3)

Accordingly, a graph shown in FIG. The minimum cross-sectional area that does not cause magnetic saturation is determined by the configuration of the iron core material and the electromagnet device, and the cross-sectional area of each portion of the integrated deformed iron core of the present invention may be set to be larger than this minimum cross-sectional area.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. This is an example applied to continuous casting of a slab. FIG. 1 is a plan view and a longitudinal sectional view of a mold in which the electromagnetic brake device of the present invention is incorporated on the long side of the mold, and FIG. And a perspective view.
FIG. 3 is a modification of the electromagnetic brake device of the present invention.

In FIG. 1, molten steel A in a tundish (not shown) is cast into a water-cooled mold 1 by an immersion nozzle 2, and a cast piece having a solidified shell formed on the molten steel surface by primary cooling of the water-cooled mold 1 is cast. Solidification is promoted by secondary cooling such as spray cooling while being guided and supported by the one-sided support roll 3,
The slab is continuously manufactured by extracting the completely solidified slab.

The water-cooled mold 1 is an assembly mold having a variable slab width in which a pair of short-side copper plates 5 are movably arranged between a pair of long-side copper plates 4, and a SUS backup plate is provided on the back of the long-side copper plate 4. The long side copper plate 4 is cooled and held by cooling water introduced from the water supply pipe 8 into the cooling box 7 and discharged from the drain pipe (not shown) through the backup plate 6. A SUS backup plate 9 is also attached to the back surface of the short side copper plate 5, and a water supply / drain pipe 10 for cooling water and a width adjusting device 11 for moving the short side copper plate 5 are connected to the backup plate 9. I have.

In this embodiment, an electromagnetic brake device is constructed by installing three stages of upper, middle and lower electromagnet devices on the back of the mold. In the conventional electromagnet device shown in FIG.
The size of the electromagnet device becomes large relative to the size of the mold, making it impossible to mount it on the back of the mold. Therefore, in the present invention, in order to obtain a required magnetic flux by winding a coil around the iron core,
The size, the cross-sectional shape, and the cross-sectional area of each part of the iron core are changed while determining the size of the electromagnetic coil 14 and maintaining the iron core cross-sectional area so as not to saturate the generated magnetic flux. Is determined.

That is, as shown in FIGS. 1 and 2, the integrated deformed iron cores 13-1 and 13-3 disposed on the upper and lower stages so that the entire rear surface of the water-cooled mold 1 can be effectively used.
Are connected to the fixed iron core 12 and inserted into the cooling box 7, an intermediate iron core 13 </ b> B integrated with the distal iron core 13 </ b> A, and an intermediate iron core 13 </ b> B. A base iron core 13C that is integrally continuous with the base iron core 13C. The base iron core 13C is displaced parallel to the outer side in the horizontal direction and the outer side in the vertical direction with respect to the distal iron core 13A. Both have a bent appearance shape. Intermediate iron core 13B
As shown in FIG. 2 (b), the cross section has a step shape in the vertical direction while keeping the cross-sectional area constant.

The sectional shape of the base iron core 13C is a circle or an ellipse so that the function of the electromagnetic coil 14 is maximized, the coil winding operation is simple, and the coil has a minimum area. I have. The intermediate iron core 13B is
It has a vertically long thin quadrilateral shape so that the space behind the mold can be used effectively. The cross-sectional area of the intermediate iron core 13B is equal to the cross-sectional area of the base iron core 13C or a small cross-sectional area that does not cause magnetic saturation. The cross-sectional area of the tip iron core 13A is equal to the cross-sectional area of the mold fixed iron core 12.

An integrated deformed iron core 13-2 provided in the middle stage
Has a straight external shape extending straight rearward, the base iron core 13C has a circular or elliptical shape,
The cross-sectional area is reduced with respect to A. In each stage, the end faces of the left and right proximal iron core portions 13C are connected by a yoke 15.

If necessary, the upper, middle and lower stages may each be formed of an integrated deformed iron core having a different shape and size. However, in this embodiment, the upper and lower stages are arranged vertically. The difference is an integrated iron core. Further, the middle stage was an integrated deformed iron core in which only the cross-sectional area changes immediately after. Also,
The modified example of the present invention shown in FIG. 3 uses an integrated deformed iron core similar to that of FIG.
1 and 13-3, the electromagnetic coil 14 is connected to the intermediate iron core 13B.
It is attached to. In the middle integrated deformed iron core 13-2,
An electromagnetic coil 14 is mounted on the base iron core 3C as in FIG.

As described above, the upper part can effectively utilize the upper part immediately after and above the mold fixed iron core 12 and the range of the slab thickness direction and the slab width direction.
And the range in the mold width direction can be effectively utilized. The lower stage can also effectively utilize the lower range immediately after and below the mold fixed iron core 12 and the range in the slab thickness direction and slab width direction. Thus, the electromagnetic coil 14 can be enlarged in a limited space, and the magnetic flux can be efficiently applied to the molten steel flow by increasing the exciting current I or the number of turns N of the electromagnetic coil within a range where the iron core is not magnetically saturated. And a strong electromagnet device can be obtained.

As described above, a powerful electromagnet device can be mounted in the upper, middle, and lower stages in the limited space behind the mold, which has been difficult in the past. With this three-stage braking control,
By achieving complete levitation of inclusions, it is possible to control the velocity of the molten steel flow (upflow, collision flow to the short side mold, downflow) at any speed, and by lowering the level of molten steel surface fluctuation on the upper surface inside the mold Therefore, it is possible to reduce breakout caused by slag bear entrainment.

Although the three-stage electromagnetic brake device has been described above, the present invention is not limited to the three-stage electromagnetic brake device, but may be applied to a two-stage or four-stage electromagnetic brake device, and further to a one-stage electromagnetic brake device. It goes without saying that a deformed iron core can be applied.

[0038]

As described above, according to the present invention, there is provided an electromagnetic brake device in which an electromagnet device having an iron core and an electromagnetic coil is provided on the back of a mold of a continuous casting machine to apply a brake to molten steel flow in the mold. Is provided in each part in the direction of the magnetic path, at least one of the direction, the cross-sectional shape, and the cross-sectional area is different from each other, so that the following effects are obtained.

(1) By devising the configuration, shape, and the like of the iron core from the electromagnetic coil section to the mold fixing section incorporated in the mold, the limited space on the back of the mold can be used effectively, and a strong electromagnet capability can be obtained. An electromagnetic brake device can be obtained, and a sufficient braking force can be applied to the molten steel flow even in a high-speed continuous casting machine. As a result, even during high-speed casting, complete levitation of inclusions in the molten steel can be achieved, and breakout due to re-melting of the solidified shell of the molten steel flow can be reduced.

(2) Since the electromagnet device can be made compact and powerful, a plurality of stages of electromagnet devices can be mounted on a small and high-speed casting mold, which has been difficult in the past. By enabling a multi-stage electromagnetic brake device, complete levitation of inclusions in molten steel can be achieved, arbitrary speed control of molten steel flow can be performed, and breakout due to slag bear entrainment can be reduced.

[Brief description of the drawings]

1A and 1B are a plan view and a longitudinal sectional view, respectively, showing a mold incorporating an electromagnetic brake device of the present invention.

FIGS. 2A and 2B are details of FIG. 1, wherein FIG. 2A is a longitudinal sectional view of the electromagnet device, and FIG. 2B is a perspective view of an upper and lower integrated deformed iron core.

3A and 3B are a modified example of the electromagnetic brake device of the present invention and a conventional electromagnetic brake device, wherein FIG. 3A is a plan view and FIG. 3B is a longitudinal sectional view.

FIG. 4A is a plan view showing a magnetic path in a conventional electromagnetic brake device, and FIG. 4B is a graph showing a relationship between a magnetic flux density and an iron core cross-sectional area.

FIG. 5 is a plan view showing a magnetic path in the electromagnetic brake device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Water-cooled mold 2 ... Immersion nozzle 3 ... Slab support roll 4 ... Long side copper plate 5 ... Short side copper plate 6 ... Backup plate 7 ... Cooling box 8 ... Water supply pipe 9 ... Backup plate 10 ... Supply / drain pipe 11 ... Width adjustment Device 12: Fixed iron core with frame 13: Integrated deformed iron core 13A: Tip iron core 13B: Intermediate iron core 13C: Base iron core 14: Electromagnetic coil 15: Yoke 16: Power supply cable

Claims (1)

[Claims] 1. An electromagnetic brake device provided with an iron core and an electromagnetic coil on the back of a mold of a continuous casting machine to apply a brake to molten steel flow in the mold. In the direction, cross-sectional shape,
An electromagnetic brake device for a continuous casting machine, comprising an integrated deformed iron core having at least one of different cross-sectional areas different from each other.