JPH08155610A - Method for continuously casting molten metal - Google Patents

Abstract

PURPOSE: To uniformize an electromagnetic force and to cast a cast slab having sufficiently uniform surface characteristic by impressing DC magnetic field to the corner parts of a mold and restraining the disturbance of molten metal surface. CONSTITUTION: In a continuous casting apparatus using a rectangular type fixed mold, permanent magnets 7 are arranged at four corner parts so that the magnetic fields S and N are faced by interposing the corner parts while approaching the outsides of the corner parts of the copper plate 1 forming the mold 1 near the molten steel surface in the mold 1. While the DC magnetic field of the permanent magnets 7 is impressed with the integration of the magnetic field impressed with an electromagnetic coil 3, the continuous casting is executed and the molten steel in the mold 1 is pinched with the electromagnetic force and also, the electromagnetic brake effect is acted only the corner parts to restrain the disturbance of the molten steel surface by the concentration of the electromagnetic force to the corner parts. As a result, the effect of stable rise-up of the whole meniscus on the molten steel surface in the mold is obtd., and oscillation mark of the obtd. cast slab is shallowed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly applied to a continuous casting method of molten metal using a square fixed mold for casting steel, stainless steel, alloys, aluminum, etc., in which an electromagnetic coil is arranged outside the mold. The present invention relates to a continuous casting method for molten metal in which a pinch force is applied to the molten metal in the mold to accelerate the feeding of the lubricant and to suppress the disturbance of the molten metal surface in the mold.

[0002]

2. Description of the Related Art Conventionally, for example, in a continuous casting process of steel, a lubricant added to the molten steel surface and melted is
It flows in and is consumed by these interactions or a natural drop between the mold that vibrates under a predetermined condition and the solidified shell that is pulled out at a constant speed, and it is consumed. It is known that the quality of the slab, especially the surface quality, is greatly affected.

The consumption of this lubricant is considered to be an important factor controlling the lubrication between the mold and the solidified shell, and various measures have been proposed to increase the consumption. For example, in Japanese Patent Laid-Open No. 52-32824, for example,
As shown in FIG. 4, the electromagnetic coil 3 is arranged outside the fixed mold 1 formed of the copper plate 1a so as to surround it through the back plate 2, and the immersion nozzle 4 is arranged in the mold. The molten metal s is injected from the dipping nozzle into the mold, and the electromagnetic coil 3 is energized from the power source 5 to pinch the meniscus portion of the molten metal s in the mold by an electromagnetic force to form the meniscus portion sf in the mold. A lubricant (powder) is formed by forming a curved depression 6 in the vicinity of 1.
It is disclosed that the feeding of p- is promoted to improve the lubricity and the surface quality of the cast slab sc after solidification is improved.

In the continuous casting method as disclosed herein, when a rectangular fixed mold is used, when an electromagnetic coil arranged outside the mold is energized to apply an electromagnetic force to the molten metal in the mold, Eddy currents flowing through the molten metal concentrate at the corners of the mold.

In this case, since the electromagnetic force acting on the molten metal in the mold is proportional to the magnetic flux density × eddy current, the electromagnetic force is excessively concentrated at the corners of the mold, and the molten steel surface sf
Is disturbed (abnormal flow) as shown by a dotted line, and there is a problem that a slab having a sufficiently uniform surface quality cannot be obtained.

[0006]

DISCLOSURE OF THE INVENTION In the present invention, an electromagnetic coil is arranged outside a square fixed mold for injecting and solidifying molten metal, and casting is performed while applying electromagnetic force to the molten metal in the mold. In the continuous metal casting method, the electromagnetic force concentration at the corners of the mold is suppressed to make the electromagnetic force uniform and to pinch the molten metal in the mold, while suppressing the disturbance (abnormal flow) of the molten metal surface, It is intended to provide a continuous casting method for molten metal capable of casting a slab having a uniform surface property.

[0007]

The first invention of the present invention is as follows:
An electromagnetic coil is placed outside a square fixed mold that injects and solidifies molten metal, and casting is performed while pinching the molten metal in the mold with electromagnetic force. A continuous casting method for molten metal, which comprises applying a magnetic field to suppress disturbance of the molten metal surface. A second invention is characterized in that, in the first invention, the means for applying a DC magnetic field to the mold corner is a permanent magnet arranged near the mold corner, and the third invention is a mold corner. The means for applying a DC magnetic field to the is an electromagnet driven by a DC current. A fourth invention is the second invention, in the third invention, a permanent magnet so that different magnetic poles face each other across the mold corner portion,
The fifth invention is characterized in that an electromagnet is arranged, and in the fifth invention, in the second invention and the third invention, of the four sides forming the cross section of the rectangular mold, the relatively long sides face each other. The continuous casting method for molten metal is characterized in that a permanent magnet and an electromagnet are arranged so that different magnetic poles face each other with the two sides sandwiched therebetween.

[0008]

According to the present invention, a continuous casting method for molten metal in which an electromagnetic coil is arranged outside a square fixed mold for injecting and solidifying molten metal, and casting is performed while pinching the molten metal in the mold by electromagnetic force. In, it is possible to suppress the electromagnetic force concentration at the corners of the mold and its vicinity to generate a uniform electromagnetic force, pinch the molten metal in the mold, and to disturb the molten metal surface in the mold (abnormal flow). By suppressing, it is possible to cast a slab having a uniform surface texture.

The inventors of the present invention have arranged an electromagnetic coil outside a square fixed mold for injecting and solidifying the molten metal, and perform continuous casting of molten metal while pinching the molten metal in the mold by electromagnetic force. Through various experiments on the method, if all the mold plates are made of the same material with the same thickness, there is a phenomenon of electromagnetic force concentration at the corners of the mold, and it is possible to generate electromagnetic force uniformly in the mold circumferential direction. It is not possible to stably pinch the molten metal in the mold, and a disturbance phenomenon (abnormal flow) occurs on the molten metal surface in the mold, and it is impossible to obtain a good slab with uniform surface properties. I found out. Therefore, the present invention is completed and completed with the idea of reducing the electromagnetic force concentration at the corners of the mold.

In the present invention, in order to reduce the concentration of the electromagnetic force at the corners of the mold, a DC magnetic field is superimposed and applied to the corners of the mold, and the electromagnetic braking effect is applied only to the corners of the mold. As a means for applying the DC magnetic field, it is effective to dispose a permanent magnet and an electromagnet driven by a DC current at the corner of the mold near the molten metal surface of the molten metal in the mold.

When arranging the permanent magnets and electromagnets, by arranging the magnetic poles so that different magnetic poles face each other with the mold corners sandwiched therebetween, it is possible to concentrate the static magnetic field on the mold corners, and in particular the corners. It is suitable for suppressing the disturbance of the molten metal surface of the part. Alternatively, it is also effective to dispose the opposite long sides of the mold so that different magnetic poles face each other on the outside. In this case, it is possible to suppress the disturbance of the molten metal surface near the short side including the corner portion.

The present invention can be applied as a continuous casting method using a fixed mold for casting stainless steel, alloys, aluminum, etc. in addition to steel.

[0013]

【Example】

(Embodiment 1) Hereinafter, an embodiment in which the present invention is applied to a continuous casting method for molten steel will be described together with an embodiment apparatus example. In this embodiment, as shown in FIG. 1, in a continuous casting apparatus using a square fixed mold as shown in FIG. 4, the corner of the copper plate 1a forming the mold 1 near the molten steel s molten metal surface in the mold 1 Permanent magnets 7 are arranged at the four corner portions so that the magnetic poles S and N face each other with the corner portion 1c sandwiched therebetween in the vicinity of the outside of the portion 1c.

Here, continuous casting is carried out while superimposing and applying a DC magnetic field from the permanent magnet 7 on the magnetic field applied by the electromagnetic coil 3, and the molten steel s in the mold 1 is pinched by electromagnetic force, and only the corner portion is applied. The electromagnetic braking effect is exerted on the surface of the molten steel to suppress the disturbance of the molten steel surface sf due to the electromagnetic force concentration on the corners. By replacing the permanent magnet 7 with an electromagnet driven by a direct current, the same effect as in the case of using the permanent magnet can be obtained.

Further, as shown in FIG. 2, the permanent magnets 7a (or electromagnets) may be arranged so that different magnetic poles S and N face each other with the opposite long sides of the mold 1 sandwiched therebetween. In addition, the effect of suppressing the disturbance of the molten metal surface near the short side including the corner is remarkable.

(Embodiment 1-1) As in the embodiment shown in FIG. 3, the electromagnetic coil 3 is arranged on the outer side, and C is integrally formed on the outer sides of the four corners so that different magnetic poles face each other. Continuous casting was carried out using a mold in which the V-shaped permanent magnet 7 was arranged, while superposing and applying a magnetic field by the electromagnetic force 3 and a magnetic field by the permanent magnet 7 to the molten steel in the mold.

The magnitude of the DC magnetic field applied by the permanent magnet is preferably set to 0.5 to 2 times the AC magnetic field. If it is less than 0.5 times, there is no effect, and if it is more than twice, the effect of suppressing the electromagnetic force at the corner becomes excessive. Therefore, here, the magnitude of the magnetic field is set within this range.

As a result, the flow generated from the corners toward the periphery is suppressed, and the effect that the entire meniscus of the molten steel surface sf in the mold is stably raised,
The obtained slab had the effect of making the oscillation marks shallow at both the corners and the long sides.

Also, as shown in FIG. 2, the same effect can be obtained when the opposite long sides of the mold 1 are sandwiched and the different magnetic poles S and N are arranged on the outside of the long sides. The flow suppressing effect was remarkable in the portions along the sides, and the obtained slab had the effect of making the oscillation marks shallow at the corners, long sides, and short sides.

(Comparative Example) Continuous casting was carried out while applying a magnetic field by electromagnetic force to the mold using a mold in which an electromagnetic coil as shown in FIG. 4 was arranged outside and no permanent magnets were arranged at the corners. . As a result, the obtained slab, the oscillation mark disappears in the corner portion and its vicinity,
Although the surface quality of this part was satisfactory, disturbed oscillation marks, wrinkles, and lubricant entrapment were observed in other parts, especially the long side part, and the effect of improving the surface property was not uniform in the circumferential direction. . This is because the electromagnetic force concentrates on the corners and goes from the corners to the periphery.
This is because flow has occurred.

Casting Conditions (Common to Examples and Comparative Examples) Cast Steel Type: Carbon Steel Size: Width 1500 mm, Cavity Thickness 250 mm Mold Height: 800 mm Center Mold Plate Thickness: 25 mm Back Plate (SUS304) Thickness: 40 mm Electromagnetic Coil Size : Inner size 1700mm x 450mm Magnetic flux density: 1200 gauss Permanent magnet Size: Typical size 100mm x 100mm x 50mm Magnetic flux density: 1200 gauss Casting speed: 2m / min Oscillation applied to mold: Frequency 120cpm, Stroke ± 5mm

[0022]

INDUSTRIAL APPLICABILITY In the present invention, an electromagnetic coil is arranged outside a square fixed mold for injecting and solidifying molten metal, and continuous casting of molten metal is performed while applying electromagnetic force to the molten metal in the mold. In the casting method, magnets are placed across the mold corners near the molten metal surface of the molten metal in the mold or across the opposite long sides of the mold, and a DC magnetic field generated by the magnet is superimposed on the magnetic field generated by the electromagnetic coil and applied. With this, it is possible to suppress the concentration of electromagnetic force at the corners of the mold, generate uniform electromagnetic force, pinch the molten metal in the mold, and effectively suppress the disturbance of the molten metal surface in the mold. It is possible to cast a slab having various surface textures.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a mold structure example of a continuous casting apparatus for carrying out the present invention.

FIG. 2 is a schematic plan view showing another example of the mold structure of the continuous casting apparatus for carrying out the present invention.

FIG. 3 (a) is a three-dimensional schematic explanatory view showing a mold structure of a continuous casting apparatus used in an embodiment of the present invention, and FIG. 3 (b) is (a).
The plane outline explanatory drawing of a figure, (c) figure is a three-dimensional outline explanatory drawing which shows the permanent magnet used here, (d) figure is a plane outline explanatory drawing of (c) figure.

FIG. 4 (a) is a vertical cross-sectional schematic explanatory view showing an example of a molten steel continuous casting apparatus to which the present invention is applied, and FIG. 4 (b) is a schematic plan explanatory view of FIG. 4 (a).

[Explanation of symbols]

 1 mold 1a copper plate 1b copper plate other than corner 2 back plate 3 electromagnetic coil 3b electromagnetic coil other than corner 4 immersion nozzle 5 power supply 6 molten metal depression 7,7a permanent magnet s molten steel (molten metal) sf molten steel molten metal sc casting One-sided lubricant (powder)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takehiko Fuji, 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corp. Technology Development Division

Claims (5)

[Claims] 1. A continuous casting method for a molten metal, wherein an electromagnetic coil is arranged outside a square fixed mold for injecting and solidifying the molten metal, and casting is performed while pinching the molten metal in the mold by an electromagnetic force. A continuous casting method for molten metal, characterized in that a DC magnetic field is applied to the corners of the molten metal to suppress disturbance of the molten metal surface. 2. The continuous casting method for molten metal according to claim 1, wherein the means for applying a DC magnetic field to the corner of the mold is a permanent magnet arranged near the corner of the mold. 3. The continuous casting method for molten metal according to claim 1, wherein the means for applying a DC magnetic field to the corner portion of the mold is an electromagnet driven by a DC current. 4. The continuous casting method for molten metal according to claim 2, wherein the permanent magnet and the electromagnet are arranged so that different magnetic poles face each other with the mold corner portion interposed therebetween. 5. A permanent magnet and an electromagnet are arranged so that different magnetic poles face each other with two opposite sides, which are relatively long sides, of the four sides forming the cross section of the rectangular mold being sandwiched therebetween. The continuous casting method for molten metal according to claim 2 or 3, characterized in that