JPS60234757A - Electromagnetic stirrer in mold - Google Patents

Abstract

PURPOSE:To prevent the thermal stress cracking of a billet and intrusion of powder therein while maintaining a substantially high speed of a molten metal by placing an electromagnetic coil which acts a moving magnetic field to the molten metal in a mold for continuous casting so as to face the mold and inclining the coil relative with the center line of the mold. CONSTITUTION:The moving magnetic field type electromagnetic coil 1 is disposed to face the mold 2 and is inclined by an angle theta of inclination relative with the center line of the mold 2. The molten metal 6 poured from a tundish 3 via an immersion nozzle 5 into the mold 2 is fluidized by the coil 1. Rotating flow is generated in the molten metal by reversing the moving direction of the magnetic field of the coil 1 facing the mold. Thrust acts on the molten metal 6 in the mold 1 on the side in proximity to the coil 1 and the flow direction changes in the corner part. Meniscus 4 builds-up in the corner part and the flow is consequently disturbed, but if the above-described angle theta of inclination is provided, the collision of the molten metal 6 perpendicularly against the mold wall is averted. The build-up of the meniscus 4 is thus prevented and the purpose is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electromagnetic stirring device in a continuous casting mold.

[Background technology]

When a moving magnetic field is applied to bath water in a continuous casting mold, the bath water flows in the same direction as the moving direction of the magnetic field. This flow of bath water is effective in improving the surface properties of the slab or the internal structure of the slab. That is, it has been experimentally found that a molten metal flow rate of 20 to 25 WV/rn1n is required to improve the surface properties of the slab and the internal structure of the slab.

However, since the molten metal inside the rectangular mold flows,
At some corners where the flows collide, the meniscus swells up, causing problems such as thermal stress cracking due to uneven solidification and entrainment of powder as a lubricant. On the other hand, the above disadvantages can be prevented by lowering the flow rate of the molten metal in the mold, but at a flow rate as low as 20 to 25 m/min or less, there is no effect on improving the surface properties of the slab and the internal structure of the slab. This means that it will no longer occur.

[Object of the present invention]

Therefore, the present invention aims to maintain a sufficiently high flow rate of the molten metal while
The object of the present invention is to provide an electromagnetic device in a continuous casting mold that suppresses the rise of meniscus in some corners of the mold to obtain a flow pattern that prevents thermal stress cracking of slabs and powder entrainment. do.

[Configuration of the present invention]

The present invention, as a means for achieving all of the above objects, resides in that the electromagnetic coil is arranged at an angle with respect to the center line of the mold. That is, the present invention is an electromagnetic stirring device in a continuous casting mold, which is characterized in that all electromagnetic coils are arranged facing the continuous casting mold and tilted with respect to the center line of the mold.

The present invention has been developed by arranging a moving magnetic field type electromagnetic coil facing the sides of the mold and tilting the direction of the thrust acting on the bath water with respect to the center line of the entire mold. #) It is designed to prevent the meniscus from becoming disordered.

In the present invention, it is preferable to attach the electromagnetic coil to the mold so that the inclination angle of the electromagnetic coil with respect to the mold center line can be fully adjusted. Therefore, this inclination angle is preferably adjusted within the range of 10 or less for the bloom size -f=-k, and within the range of 1 or less for the slab size.

Hereinafter, the present invention will be explained in detail with reference to FIGS. 1 to 3.

FIG. 1 is a perspective view of an electromagnetic stirring device in a continuous casting mold according to an embodiment of the present invention, FIG. 2 is a plan view of the same device, and FIG. 5 is a side view of the same device. As shown in FIGS. 1 to 5, the electromagnetic coil 1 is placed facing the mold 2,
Moreover, it is inclined by an inclination angle θ with respect to the mold center line. 5 is a tundish, 4 is a meniscus, 5 is an immersion nozzle, and 6 is a molten metal.

To explain the entire operation of this device, a moving magnetic field type electromagnetic coil 1 causes the bath water 6 in the mold 2 to flow, and by reversing the moving direction of the magnetic field of the opposing electromagnetic coils 1, a rainbow rotational flow is generated.

In this case, a thrust acts on the bath water 6 in the mold 1 on the side close to the electromagnetic coil 1, and the flow direction changes at a part of the corner. At this time, the meniscus builds up in a part of the corner, disrupting the upward flow.

In the present invention, by arranging the electromagnetic coil 1 at an angle with respect to the mold center line and preventing the bath water 6 from colliding with the mold wall perpendicularly, a meniscus can be prevented from rising in a part of the p corner. ing.

Specifically, the opposing electromagnetic coils 1 are arranged at an angle of 10 degrees or less for plume size molds and 1 degree or less for slab size molds with respect to the mold center line. As a result, the molten metal in the mold will not collide vertically with the mold wall, and the meniscus will be prevented from rising and becoming turbulent at some corners. Therefore, thermal stress cracking due to uneven cooling of the molten metal within the mold or entrainment of powder as a lubricant can be prevented.

[Effects of the present invention]

As described in detail above, in the present invention, the electromagnetic coil is arranged to face the mold and be inclined with respect to the center line of the mold. This has the effect of suppressing the build-up of the meniscus in a part of the inner corner, thereby preventing thermal stress cracking of the slab and powder entrainment. Furthermore, in the present invention, since the molten metal in the mold is stirred at a high flow rate, the surface properties of the slab and the internal structure of the slab can be improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an electromagnetic stirring device in a continuous casting mold according to an embodiment of the present invention, FIG. 2 is a plan view of the device, and FIG. 3 is a side view of the device. 1 fist・Electromagnetic coil 2 eyes Mold 3・Tandishu 41 Meniscus 5・Immersion nozzle 6・・Molten metal θ・・Inclination angle agent 1) Meifu agent Ryo Hagiwara - Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. An electromagnetic stirring device in a continuous casting mold, comprising an electromagnetic coil disposed facing the continuous casting mold and tilted with respect to the center line of the mold.