JP3056658B2 - Continuous casting method of molten metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a method for continuously casting molten metal using a square fixed mold for casting steel, stainless steel, alloy, aluminum or the like, and disposing an electromagnetic coil outside the mold. The present invention relates to a continuous casting method of molten metal in which a molten metal in a mold is pinched by electromagnetic force to promote feeding of a lubricant.

[0002]

2. Description of the Related Art Conventionally, for example, in a continuous casting process of steel, a lubricant added to a molten steel surface and melted is
The interaction between the mold vibrating under the predetermined conditions and the solidified shell drawn at a constant speed is caused by the interaction or natural fall of the mold, and is consumed.The lubricity of this lubricant is determined by the operability of continuous casting, It is known that it greatly affects the quality of cast slabs, particularly the surface properties.

[0003] The consumption of the lubricant is considered to be an important factor governing the lubrication between the mold and the solidified shell, and various measures have been proposed to increase this. For example, JP-A-52-32824 discloses, for example,
As shown in FIG. 3, an electromagnetic coil 3 is arranged outside a stationary mold 1 formed of a copper plate 1a via a back plate 2 so as to surround the fixed mold 1, and an immersion nozzle 4 is arranged in the mold. While the molten metal s is being injected into the mold from the immersion nozzle, power is supplied to the electromagnetic coil 3 from the power supply 5 to apply an electromagnetic force to the meniscus portion of the molten metal s in the mold, and the meniscus portion sf is molded. 1 to form a recessed portion 6, thereby facilitating the feeding of the lubricant (powder) p to enhance the lubricity, and thereby solidifying the slab sc
It is disclosed to improve the surface properties of the steel.

In the continuous casting method disclosed herein, when a rectangular fixed mold is used, an electromagnetic coil disposed outside the mold is energized to apply an electromagnetic force to the molten metal in the mold. The eddy current flowing through the molten metal is concentrated at the corner of the mold. In this case, the electromagnetic force acting on the molten metal in the mold is proportional to the magnetic flux density x eddy current, so the electromagnetic force is excessively concentrated at the corner of the mold, and a uniform electromagnetic force is generated in the circumferential direction of the mold. However, there is a problem that the meniscus portion sf is disturbed (abnormal flow), and a slab having sufficiently uniform surface properties cannot be obtained.

[0005]

SUMMARY OF THE INVENTION In the present invention, an electromagnetic coil is arranged outside a rectangular fixed mold for injecting and solidifying molten metal, and casting is performed while pinching the molten metal in the mold by electromagnetic force. A method for continuously casting molten metal, which suppresses the concentration of electromagnetic force at the corners of a mold and makes the electromagnetic force uniform, thereby providing a method for continuously casting molten metal capable of casting a slab having a sufficiently uniform surface property. It is.

[0006]

Means for Solving the Problems The first invention of the present invention is:
In a continuous casting method of molten metal, in which an electromagnetic coil is arranged outside a rectangular fixed mold for injecting and solidifying the molten metal, and the molten metal in the mold is pinched by electromagnetic force, an electromagnetic coil arranged outside the mold is used. The vertical width of the coil
The molten metal is characterized in that it is made larger in the casting direction at the corners of the mold and in the vicinity thereof than in the other parts, thereby reducing the concentration of electromagnetic force at the corners of the mold and generating uniform electromagnetic force. Continuous casting method.

A second invention is a continuous casting of molten metal in which an electromagnetic coil is arranged outside a rectangular fixed mold for injecting and solidifying molten metal, and casting is performed while pinching the molten metal in the mold by electromagnetic force. In the method, the upper end position and the lower end position of the mold corner portion and the vicinity thereof of the electromagnetic coil disposed outside the mold are lowered in the casting direction from the upper end position and the lower end position of the other portions, so that the electromagnetic force at the mold corner portion is reduced. A continuous casting method for molten metal, characterized in that concentration of force is reduced and uniform electromagnetic force is generated.

[0008]

According to the present invention, there is provided a continuous casting method for molten metal in which an electromagnetic coil is arranged outside a rectangular fixed mold for injecting and solidifying the molten metal, and the molten metal in the mold is pinched by electromagnetic force. In this case, it is possible to generate a uniform electromagnetic force by suppressing the concentration of electromagnetic force at the corner of the mold and in the vicinity thereof, to make the electromagnetic force uniform in the circumferential direction of the mold, and to make the molten metal surface in the mold (meniscus portion). The slab having uniform surface properties can be cast by suppressing disturbance (abnormal flow) of the slab.

The present inventors dispose an electromagnetic coil outside a rectangular fixed mold for injecting and solidifying a molten metal, and perform continuous casting of the molten metal by pinching the molten metal in the mold by electromagnetic force. If the coil shape is made uniform in the casting direction through various experiments in the method, there is a phenomenon of concentration of electromagnetic force at the corner of the mold, and it is possible to generate electromagnetic force uniformly in the circumferential direction of the mold. It was found that disturbances (abnormal flow) occurred on the molten metal surface (meniscus portion) in the mold, and good cast slabs with uniform surface properties could not be obtained. Accordingly, the present invention has been completed with the idea of reducing the concentration of electromagnetic force at the corners of the mold.

In the present invention, as means for reducing the concentration of the electromagnetic force at the corner of the mold, the width of the electromagnetic coil disposed outside the mold in the vertical direction of the corner of the mold is increased. The upper end position and the lower end position of the corner portion of the mold in the electromagnetic coil disposed outside the mold are lower than the upper end position and the lower end position of the other portions. Such a method is effective.

When the method of (1) is used, the density of the eddy current at the corner of the mold is reduced by utilizing the property that the eddy current of the molten metal flows relative to the coil current. ) By increasing the width in the direction, the eddy currents at the corners are diffused and distributed in the vertical direction,
The electromagnetic force acting on the molten metal at the corner is diffused and distributed in the vertical direction to reduce the concentration of the electromagnetic force on the corner.

In the case of using the method described above, the upper end position of the electromagnetic coil at the corner of the mold is made lower than the surface of the molten metal, so that the electromagnetic force acting on the molten metal at the corner is diffused and distributed to the corner. Alleviate the electromagnetic force concentration.

The present invention can be applied as a continuous casting method using a fixed mold for casting not only steel but also stainless steel and alloys.

[0014]

【Example】

(Embodiment 1) An embodiment in which the present invention is applied to a continuous casting method of molten steel will be described below together with an example of an apparatus. In this embodiment, as shown in FIG. 1, in a continuous casting apparatus using a square fixed mold as shown in FIG. 3, a corner portion of an electromagnetic coil corresponding to a corner portion 1c of a copper plate 1a forming a mold 1 is formed. the upper end side to form a wide portion 7b wide portion 7a, the lower end of the, and is formed larger than the width H ₁ of the electromagnetic coil 3b to the corresponding width of H ₂ vertically other portions 1b.

Here, by forming the vertical width H ₂ of the corner portion of the electromagnetic coil large, the eddy current density of the corner portion is diffused by utilizing the property that the eddy current of the molten steel flows relative to the coil. This reduces the concentration of electromagnetic force at the corners and suppresses disturbance on the molten steel surface (meniscus).

In this embodiment, the wide portions 7a and 7b formed at the corners of the electromagnetic coil 3 are formed to have substantially the same size, but need not be the same. Even if only the wide portion 7a is formed, a corresponding effect can be obtained.

(Embodiment 1-1) In the embodiment shown in FIG. 1, a width H ₂ in the vertical direction (height) of the corner of the mold is outwardly provided.
The 280 mm (width H ₁ of the other part 200 mm) was continuously cast using the mold of arranging the electromagnetic coils to.

As a result, the molten steel surface in the mold is suppressed from flowing from the corner portion to the peripheral portion, and shows a stable swelling. The obtained cast slab is oscillated at both the corner portion and the long side portion. The effect that the mark becomes shallow was obtained. While the depth of the oscillation mark when no electromagnetic force was applied was 250 μm, in this example, the depth of the oscillation mark was 80 μm on average, indicating a considerable improvement effect.

(Comparative Example) Continuous casting was carried out using a mold having a rectangular solenoid coil as shown in FIG. As a result, in the obtained slab, the oscillation mark disappeared at the corner portion and the vicinity thereof, and although the surface properties at this portion were satisfactory, the oscillation was disturbed at other portions, especially at the long side portion. Marks and hot water wrinkles,
Entrainment of the lubricant was observed, and the effect of improving the surface properties was not uniform in the circumferential direction. This is because the electromagnetic force is concentrated on the corner portion and the flow is generated from the corner toward the periphery.

(Embodiment 2) In this embodiment, as shown in FIG. 2, in a continuous casting apparatus as shown in FIG. 3, an electromagnetic coil 3 corresponding to a corner 1c of a copper plate 1a forming a mold 1 is formed. The upper end position and the lower end position of the corner portion are lower than the upper end position and the lower end position of the electromagnetic coil 3b corresponding to the other portion 1b by a distance d to form a position lowering portion 8a at the upper end and a position lowering portion 8b at the lower end. It is. Here, the upper end position and the lower end position of the corner portion of the electromagnetic coil 3 are reduced by a distance d from the upper end portion and the lower end portion of the other portion 3, and are moved downward from the molten steel surface in the mold so as to act on the molten steel in the mold. We try to reduce the concentration of power on the corners.

In this embodiment, the lowering portion 8a at the upper end of the corner of the electromagnetic coil 3 and the lowering portion 8b at the lower end are separated by the same distance d from the upper and lower positions of the other portions 3b. Although the distance d is not necessarily the same at the upper end and the lower end, a corresponding effect can be obtained by forming the position lowering portion 8a only at the upper end.

(Embodiment 2-1) In the embodiment shown in FIG. 2, the upper end position and the lower end position of the mold corner are outwardly positioned at a distance d: 50 from the upper end position and the lower end position of the other portion 3b.
Continuous casting was performed using the mold 1 in which the electromagnetic coil 3 in which the position lowered portion 8 was formed by lowering by mm was arranged.

As a result, the same effect as in the case of Example 1 is obtained. The molten steel surface in the mold shows a stable swelling, and the obtained slab has oscillation marks at both corners and long sides. It was shallow and had an average depth of 90 μm. A considerable improvement effect was observed with respect to the comparative example.

Casting conditions (common to Examples 1-1 and 2-2 and Comparative Examples) Cast slab Steel type: carbon steel Size: width 1500 mm, cavity thickness 250 mm Mold height: 800 mm Mold plate center part thickness: 25 mm Back plate (SUS304) ) Thickness: 40mm Electromagnetic coil Size: Internal dimensions 1700mm × 450mm Magnetic flux density: 1200 gauss Casting speed: 2m / min Applied oscillation to mold: frequency 120cpm, stroke ± 5mm

[0025]

In the present invention, an electromagnetic coil is arranged outside a rectangular fixed mold for injecting and solidifying molten metal, and the molten metal is cast while pinching the molten metal in the mold by electromagnetic force. In the casting method, it is possible to suppress the concentration of electromagnetic force in the corner of the mold and in the vicinity thereof, to generate a uniform electromagnetic force in the circumferential direction of the mold, and to make the electromagnetic force in the circumferential direction of the mold uniform, A slab having various surface properties can be cast.

[Brief description of the drawings]

FIG. 1 is a three-dimensional schematic explanatory view showing a first embodiment of a mold structure of a continuous casting apparatus for implementing the present invention.

FIG. 2 is a three-dimensional schematic explanatory view showing a second embodiment of the mold structure of the continuous casting apparatus for implementing the present invention.

FIG. 3 (a) is a schematic longitudinal sectional view showing an example of a continuous casting apparatus for molten steel to which the present invention is applied, and FIG. 3 (b) is a schematic plan sectional view of FIG. 3 (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold 1a Copper plate 1b Copper plate other than a corner part 1c Copper plate of a corner part of a mold 2 Back plate 3 Electromagnetic coil 3b Electromagnetic coil other than a corner part 4 Immersion nozzle 5 Power supply 6 Depressed part 7a, 7b Wide part 8a, 8b Position lowering Part s molten steel sf molten steel surface (meniscus part) sc slab p lubricant (powder)

Continuation of the front page (72) Inventor Takehiko Fuji 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Technology Development Division (56) References JP-A-63-180352 (JP, A) JP-A-4 JP-A-333351 (JP, A) JP-A-4-13441 (JP, A) JP-A-8-33959 (JP, A) JP-A-62-187547 (JP, A) JP-A-58-41661 (JP, A) JP-A-52-32824 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 11/115 B22D 11/04 311 B22D 11/07

Claims (2)

(57) [Claims] 1. A method for continuously casting molten metal in which an electromagnetic coil is arranged outside a rectangular fixed mold into which molten metal is injected and solidified, and the molten metal in the mold is pinched by electromagnetic force. The vertical width of the electromagnetic coil placed on the outside is made larger in the casting direction at the corners of the mold and in the vicinity thereof than in other parts, so that the concentration of electromagnetic force at the corners of the mold is relaxed and uniform. A continuous casting method for molten metal, comprising generating an electromagnetic force. 2. A continuous casting method for a molten metal in which an electromagnetic coil is arranged outside a rectangular fixed mold for injecting and solidifying the molten metal and the molten metal in the mold is pinched by electromagnetic force. The upper and lower end positions of the outer corners of the electromagnetic coil mold and the vicinity thereof are lowered in the casting direction from the upper and lower end positions of the other portions to reduce the concentration of electromagnetic force at the mold corners. A continuous casting method for molten metal, characterized by generating a uniform electromagnetic force by relaxing.