JPH05146853A - Method for continuously casting molten metal - Google Patents

Abstract

PURPOSE:To secure flowing of powder for lubrication into gap between a cast slab and the inner surface of a mold even at the time of casting molten metal in high speed and to prevent breakout caused by burning of the molten metal or a solidified shell to the mold. CONSTITUTION:To electromagnetic coils 5 surrounding the mold 1 and the molten metal 2 and divided in the vertical direction, ACs having different phases are conducted. By this method, arched magnetic flux 8 detoured after reaching to near the surface layer of the molten metal 2, is shifted downward and the electromagnetic force to inside downward is applied to the circumferential part of the molten metal. By the component in the center direction of the electromagnetic force, meniscus of the molten metal is curved as the projecting state, and flowing of the powder into between the molten metal and the mold is promoted. By the downward component, the molten metal, solidified shell and semi-solidified metal, are shifted downward without stagnating to one position and the burning caused by the stagnant is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, when a slab is manufactured from a molten metal by a continuous casting method, applies an electromagnetic force to the molten metal to bend the meniscus shape of the molten metal into a convex shape so as to extend along the inner surface of the mold. The present invention relates to a continuous casting method for promoting powder feeding.

[0002]

2. Description of the Related Art In continuous casting, powder is put on a meniscus of molten metal in a mold. This powder improves the lubrication between the slab and the mold inner surface when pulling out the semi-solid slab, reduces wear on the mold inner surface, and mitigates thermal and mechanical impact on the mold inner surface. With.

Japanese Patent Publication No. 57-21408 discloses a method in which an electromagnetic force is applied to bend a meniscus in a convex shape in order to effectively and smoothly introduce powder between a slab and an inner surface of a mold. .. FIG. 3 shows a schematic vertical sectional view of a continuous casting mold incorporating an electromagnetic coil used in the same method. Mold 1
The supplied powder 4 floats above the meniscus 3 of the molten metal 2 injected into the internal space of the. Mold 1
Molten metal 2 by electromagnetic coil 5 embedded inside
When an electromagnetic force is applied to the meniscus 3, the meniscus 3 is curved in the shape shown in FIG. FIG. 4 is a diagram illustrating that the meniscus 3 bends when an alternating current I is passed through the electromagnetic coil 5 in this configuration. A magnetic field H that changes with time is generated around the mold by the alternating current I. Also, an eddy current i is induced in the molten metal 2 in the mold 1 by the temporal change of the magnetic field H. Due to this magnetic field H and eddy current i, a restraining force F directed toward the center of the mold 1 acts. Due to this restraining force F, the molten metal 2 is squeezed toward the center of the mold 1, and the meniscus 3 is curved upward in a convex shape.

[0004]

[Problems to be Solved by the Invention] Japanese Patent Publication No. 57-2140
In the method described in Japanese Patent Publication No. 8, the powder 4 is insufficiently introduced between the molten metal 2 or the solidified shell 6 and the inner surface of the mold 1 at the time of high speed casting, and the molten metal 2 or the solidified shell 6 is seized on the mold 1. There is a problem that breakout is likely to occur.

In view of the problems of the prior art as described above, the present invention is a continuous method for curving the meniscus shape into a convex shape by an electromagnetic coil surrounding the molten metal in the mold to promote the feeding of powder along the inner surface of the mold. It is an object of the present invention to provide a continuous casting method capable of sufficiently feeding powder even during high speed casting.

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is to feed powder along an inner surface of a mold by applying an electromagnetic force to the molten metal by an electromagnetic coil that surrounds the molten metal in the mold to bend the meniscus shape in a convex shape. In the continuous casting method of molten metal for promoting the above, the electromagnetic coils are divided into a plurality of pieces and arranged in the molten metal casting direction, and alternating currents having different phases are passed through the divided electromagnetic coils to reach the molten metal. This is a continuous casting method for molten metal, characterized in that an arch-shaped magnetic flux that detours around is transferred in the molten metal casting direction.

[0007]

FIG. 1 is a vertical cross-sectional schematic view showing a schematic structure of the present invention and an example of a molten metal meniscus shape. The electromagnetic coil 5 that surrounds the molten metal 2 in the mold 1 is divided into a plurality of pieces in the vertical direction, and alternating currents having different phases are passed through the divided coils, so that the molten metal 2 is near the side surface layer or the solidified shell 6 The arch-shaped magnetic flux 8 that reaches and detours is transferred downward. Corresponding to the transfer of the arch-shaped magnetic flux 8, an eddy current is induced in the side surface layer of the molten metal 2 and the solidified shell 6, and the electromagnetic force toward the center of the mold 1 due to the vertical component of the magnetic flux 8 and the induced current, and the magnetic flux. A downward composite force of the electromagnetic force due to the horizontal component of 8 and the induced current, that is, a downward inward electromagnetic force 9 is generated.

FIG. 2 is a diagram showing the distribution of the electromagnetic force generated in the molten metal when the present invention is applied. Electromagnetic coil 5
It is understood that the downward inward electromagnetic force 9 is exerted on almost the entire side surface of the molten metal 2 except near the lower end.

The central component of the electromagnetic force 9 acts to bend the meniscus 3 of the molten metal 2 into a convex shape as in the prior art, and the powder 4 between the molten metal 2 and the inner surface of the mold 1 is made. Promote inflow. The downward component of the electromagnetic force 9 acts so as to transfer the molten metal 2, the solidified shell 6 and the semi-solidified metal in the middle between them downward according to the casting speed without stagnation in one place. The seizure on the inner surface of the mold 1 due to the stagnation of the shell 6 and the semi-solidified metal is prevented.

[0010]

[Examples] With a magnetic flux density of 1000 gauss, a frequency of 100 cycles / min, and a casting speed of 3 m / min, casting was carried out by the method of the present invention and the prior art, and the state of breakout was investigated. As a result, in the prior art, breakouts occurred at a frequency of about once every 10 times, whereas in the method of the present invention, breakouts did not occur at all.

[0011]

INDUSTRIAL APPLICABILITY In the present invention, since a downward inward electromagnetic force can be applied to the molten metal and the solidified shell, the meniscus shape of the molten metal is curved to secure the feeding of the powder along the inner surface of the mold, Further, the molten metal and the solidified shell are transferred in the casting direction without stagnation to prevent seizure on the inner surface of the mold, and high-speed casting can be performed without causing breakout.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing a schematic configuration of the present invention and an example of a molten metal meniscus shape.

FIG. 2 is a diagram showing a distribution of an electromagnetic force generated in a molten metal when the present invention is applied.

FIG. 3 is a schematic vertical sectional view showing a continuous casting mold incorporating a conventional electromagnetic coil.

FIG. 4 is a diagram illustrating that the meniscus is curved when an alternating current is applied to an electromagnetic coil in the conventional technique.

[Explanation of symbols]

 1 Mold 2 Molten Metal 3 Meniscus 4 Powder 5 Electromagnetic Coil 6 Solidification Shell 7 Iron Core 8 Magnetic Flux 9 Electromagnetic Force

Claims (1)

[Claims] 1. A continuous casting method of molten metal for applying an electromagnetic force to the molten metal by an electromagnetic coil surrounding the molten metal in the mold to bend the meniscus shape in a convex shape to facilitate the feeding of powder along the inner surface of the mold. , The electromagnetic coils are divided into a plurality of pieces and arranged in the molten metal casting direction, and alternating currents having different phases are passed through the divided electromagnetic coils, whereby an arc-shaped magnetic flux that reaches and detours the molten metal A continuous casting method for molten metal, characterized in that it is transferred in the casting direction.