JP3253012B2 - Electromagnetic brake device for continuous casting mold and continuous casting method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic brake device for a continuous casting mold and a continuous casting method using the same, and more particularly to controlling a molten steel flow by generating a static magnetic field in molten steel in a mold used for continuous casting. TECHNICAL FIELD The present invention relates to an electromagnetic brake device for a continuous casting mold and a continuous casting method using the same, which are preferably applied at that time.

[0002]

2. Description of the Related Art Generally, in continuous casting of billets, although not shown, molten steel contained in a tundish is guided into a continuous casting mold via an immersion nozzle connected to its bottom. Have been done. In that case, the flow velocity of the molten steel spouted from the discharge port of the immersion nozzle is significantly higher than the casting speed, so if inclusions or bubbles in the molten steel penetrate deeply and become trapped in the solidified shell, It is inevitable that a product defect is caused by the above.

In addition, when the upward flow of the molten steel jet is particularly large, the mold meniscus rises and promotes fluctuations in the molten metal level. This causes a significant adverse effect on the quality of the slab and the casting operation. Was exerted.

[0004] In order to avoid such a problem, for example, Japanese Patent Application Laid-Open No. 3-14049 discloses that a static magnetic field is applied to molten steel in a mold by a magnetic pole arranged on the back surface of the opposite side wall of the mold.
A continuous casting technique has been disclosed which applies braking to a molten steel flow in a mold to prevent the above problem from occurring.

FIG. 7A is a cross-sectional view showing a main part of the casting apparatus disclosed in the above publication, and FIG. 7B is a longitudinal cross-sectional view showing a part of the casting apparatus in an enlarged manner.

In the figure, reference numeral 101 denotes a continuous casting mold comprising a pair of opposing short side walls 101A and long side walls (opposing side walls) 101B, the inside of which is water-cooled. Immersion nozzles 103A and 103B for supplying the molten steel from a tundish (not shown) are core bodies forming magnetic paths, 104A, 104B, 105A and 105.
B is connected to each core body 103A, 103B,
Upper and lower magnetic poles (iron core) extending along the width direction of 01
It is.

Reference numeral 106 denotes magnetic field adjusting means for adjusting the intensity of the static magnetic field generated between the magnetic poles. The adjusting means 106 includes a bracket 107 fixed to a support or the like.
And a bracket 108 fixed to the iron core body 103B.
, A pivot pin 109 connecting these two brackets 107 and 108, and a hydraulic cylinder 110 fixed to the support and having a rod tip engaged with the iron core body. Reference numeral 102B in the figure denotes a discharge port of the immersion nozzle 102.

In the continuous casting mold 101, for example, when the upper magnetic pole 104A on the A side on the left side in FIG. 7 (A) is an N pole and the upper magnetic pole 104B on the B side is an S pole, A → A magnetic field of B is generated, while a magnetic field of A ← B is generated at the lower magnetic pole. When molten steel is supplied in such a magnetic field, the upward flow is decelerated by the upper magnetic field, and the downward flow is decelerated by the lower magnetic field.

In the mold 101, when the strength of the static magnetic field is changed between the upper magnetic pole and the lower magnetic pole, the hydraulic cylinder 110 is operated by the magnetic field adjusting means 106, and the iron core body is connected to the pivot pin 109. The strength of the magnetic field is changed by changing the distance between the upper magnetic poles by rotating about the center.

[0010]

However, the technique disclosed in the above publication requires a hydraulic cylinder 110 and a pivot pin 109, and also requires a position detection sensor for more accurately adjusting the distance. Because of the necessity, there is a problem that in order to install equipment for adjusting the strength of the static magnetic field, a large space is required and the number of equipment is large.

The above-mentioned publication also discloses a method of adding a non-magnetic material to a part of the iron core in order to adjust a magnetic field. In addition, the strength of the magnetic field cannot be changed arbitrarily during casting, and it takes time to replace the non-magnetic material, so that the work efficiency is extremely low.

The present invention has been made to solve the above-mentioned conventional problems, and provides a technique capable of easily and inexpensively changing the strength of the magnetic field of the upper and lower magnetic poles and arbitrarily during casting. This is the first problem.

A second object of the present invention is to make it possible to manufacture a high-quality cast product by solving the first object.

[0014]

SUMMARY OF THE INVENTION The present invention is directed to a continuous casting mold having a pair of upper electromagnets disposed adjacent to and opposed to the backside of an opposing side wall of the casting mold, and opposed to a lower portion thereof. A pair of lower electromagnets, a static magnetic field is generated between each pair of the electromagnets, and the static magnetic field applies an electromagnetic force to the continuous casting mold to brake the molten steel flow supplied into the mold. In the brake device, the first problem is solved by providing control means for independently controlling the direction and the current value of the current supplied to the electromagnetic coils constituting each electromagnet.

According to the present invention, in the electromagnetic brake device, an upper core and a lower core constituting an upper electromagnet and a lower electromagnet, respectively, which are arranged close to the same side and back of the opposite side wall of the mold, are magnetically connected. It is as if it were.

According to the present invention, the relationship between the magnetic poles of the upper electromagnet and the lower electromagnet can be determined by using the electromagnetic brake device.
Control to make the opposite pole sandwiched and the upper and lower poles on the same side different polarities, upper pair
Control to make only the pole the same pole, or make only the lower counter electrode the same pole
By controlling the molten steel jet supplied from the discharge port of the immersion nozzle into the mold and casting it continuously,
This is a solution to the second problem.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic sectional view schematically showing a main part of an electromagnetic brake device for a continuous casting mold according to an embodiment of the present invention.

The electromagnetic brake device of the present embodiment is applied to a continuous casting mold 10 indicated by reference numeral 10 in the figure.

This mold 10 is substantially the same as that shown in FIG. 7 described above, and cooling water is circulated inside the side wall of the mold 10. Molten steel Sm is supplied from a discharge port (not shown) of the immersion nozzle 12.

The electromagnetic brake device according to the present embodiment includes an upper iron core 14A installed close to the back surface of the side wall of the mold 10 on the free side (left side in the figure) located slightly above the discharge port of the immersion nozzle 12. , The upper electromagnetic coil 16 wound therearound
A first upper electromagnet 17A made of A, an upper core 14B and an upper coil 16B on the fixed side (right side in the figure) at the same height position
And a pair of the first and second upper electromagnets are arranged to face each other with the mold 10 interposed therebetween.

Similarly, below the upper electromagnet, there is a first lower electromagnet 21A including a lower-side lower core 18A and a lower electromagnetic coil 20A, and a lower-side lower core 18B and a lower electromagnetic coil 20B on a fixed side. 2nd lower electromagnet 21B
, And the pair of electromagnets are similarly arranged to face each other. Also, the upper cores 14A, 14B and the lower cores 18A, 1A,
8B are integrally formed and magnetically connected to each other via the connecting portion cores 22A and 22B, respectively. The four electromagnetic coils 16A, 16B, 20A and 20B are connected to the current control devices 24A to 24D. Current is supplied individually, and each current value can be controlled independently.

Next, the operation of the present embodiment will be described.

In this embodiment, when a normal static magnetic field is generated in the upper part and the lower part, the four control devices 2 are used.
By controlling the current to each electromagnet independently by each of 4A to 24D, as shown schematically in FIG. 2, the relationship between the magnetic poles of the upper and lower electromagnets, the counter electrode sandwiching the molten steel and the upper and lower poles on the same side are different. Pole. In this case, it is most efficient to make the current values of the counter electrode electromagnetic coils the same.

Further, in order to prevent the mold powder from being caught in the meniscus portion of the molten steel, the upper magnetic field is increased in order to calm the fluctuation of the molten metal level, and the penetration of nonmetallic inclusions into the deep portion of the molten steel. For the purpose of preventing
The lower magnetic field can be increased to dampen the downward flow of molten steel in the mold.

Conventionally, eliminating the strength of either the upper or lower magnetic field is achieved by connecting the upper and lower iron cores by connecting iron cores even when the current value to the coil of the electromagnet is zero. However, in the present embodiment, the control devices 24A to 24A
With 4D, the direction of the current of one of the opposing electromagnetic coils can be reversed, and the opposing magnetic poles can be made the same, as shown in FIGS. 3 and 4, thereby eliminating the strength of the magnetic field.

Therefore, for example, in order to ensure the quality under the surface of the skin rather than the powder entrainment due to the fluctuation of the molten metal level, to prevent the non-metallic inclusions from being mixed into the inner surface of the solidified shell in the meniscus portion, or to prevent the discharge of the immersion nozzle. In order to prevent the argon gas bubbles blown into the steel from being trapped so that the outlet is not blocked, it is effective to reduce the magnetic field between the upper electromagnets to zero when the molten steel flow in the meniscus is required. However, according to the present embodiment, such control can be easily performed.

Next, an example which is a specific example of the present embodiment will be described.

[0029]

EXAMPLE Using a mold provided with the electromagnetic brake device of the first embodiment shown in FIG. 1, continuous casting was performed under the following conditions to produce a cast slab of low carbon A1 killed steel. ,
The surface quality and internal quality were investigated. FIG. 5 shows the result when the intensity of the lower magnetic field was fixed at 2500 Gauss and the intensity of the upper magnetic field was changed.
FIG. 6 shows the result in the case of fixing to 0 Gauss.

[Casting conditions] Casting speed 2.5 m / min Slab width 1400 mm Slab thickness 220 mm Upper magnetic field strength 2000 to 3000 Gauss Lower magnetic field strength 2000 to 3000 Gauss

From the results shown in FIGS. 5 and 6, it is clear that adjusting the strength of the magnetic field according to the operating conditions is extremely effective.

As described in detail above, according to the present embodiment,
Since the molten steel flow in the mold can be arbitrarily damped, non-metallic inclusions are prevented from being deeply caught in the molten steel pool by the injected molten steel jet and mold powder being caught in the molten steel due to fluctuations in the meniscus level. This makes it possible to produce high quality cast slabs with high efficiency.

Although the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist thereof.

[0034]

As described above, according to the present invention,
The strength of the magnetic field between the magnetic poles of the upper and lower electromagnets can be easily and inexpensively changed arbitrarily during casting.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing a schematic configuration of an embodiment according to the present invention.

FIG. 2 is an explanatory diagram showing combinations of poles of a magnetic field.

FIG. 3 is another explanatory diagram showing combinations of poles of a magnetic field.

FIG. 4 is yet another explanatory diagram showing combinations of poles of a magnetic field.

FIG. 5 is a diagram showing the quality of a slab obtained in an example.

FIG. 6 is a diagram showing the quality of a slab obtained in an example.

FIG. 7 is a sectional view schematically showing a conventional mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Continuous casting mold 12 ... Immersion nozzle 14A ... Free side upper iron core 14B ... Fixed side upper iron core 16A ... Free side upper coil 16B ... Fixed side upper coil 17A ... 1st upper electromagnet 17B ... 2nd upper electromagnet 18A ... Free Lower lower core 18B Fixed lower core 20A Free lower coil 20B Fixed lower coil 21A First lower electromagnet 21B Second lower electromagnet 22 Current control device Sm Molten steel

Continuation of the front page (56) References JP-A-6-190520 (JP, A) JP-A-2-117756 (JP, A) JP-A-6-71403 (JP, A) JP-A-6-71401 (JP) JP-A-5-154621 (JP, A) JP-A-4-344858 (JP, A) JP-A-4-319052 (JP, A) JP-A-7-136747 (JP, A) 9-174216 (JP, A) JP-A-8-10917 (JP, A) JP-A-3-142049 (JP, A) JP-A-4-327343 (JP, A) Table 11-502466 (JP, A) A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B22D 11/115 B22D 11/04 311 B22D 11/11

Claims (3)

(57) [Claims] 1. A pair of upper electromagnets disposed adjacent to a back surface of an opposing side wall of a continuous casting mold and having the mold opposed therebetween;
And a pair of lower electromagnets disposed below the pair of electromagnets. A static magnetic field is generated between the pair of electromagnets, and the static magnetic field dampens the molten steel flow supplied into the mold. an electromagnetic brake device for a continuous casting mold is added, the orientation及of the current supplied to the electromagnetic coil constituting each electromagnet
An electromagnetic brake device for a continuous casting mold, comprising control means for independently controlling the current value and the current value . 2. The method according to claim 1, wherein an upper core and a lower core constituting an upper electromagnet and a lower electromagnet, respectively, disposed close to the same back surface of the opposite side wall of the mold are magnetically connected. Electromagnetic brake device for continuous casting mold. 3. A relationship between magnetic poles of an upper electromagnet and a lower electromagnet using the electromagnetic brake device according to claim 1.
The opposite pole across the molten steel and the upper and lower poles on the same side
Control, control only the upper counter electrode to the same polarity, or only the lower counter electrode
A continuous casting method comprising controlling the molten steel jet supplied from the discharge port of the immersion nozzle into the mold to perform continuous casting.