KR20010058173A - Electromagnetic casting machine without mold oscillation - Google Patents

Abstract

PURPOSE: An electromagnetic continuous casting device not oscillating a mold is provided to simplify the structure and reduce the power consumption of the casting device by omitting any additional elements for oscillating a mold and improve the quality of the surface of cast slabs. CONSTITUTION: An electromagnetic continuous casting device in which an ingot is supplied via an immersion nozzle(9) and a slab is cast by using a mold(20) wound with a coil(15) on an outer surface by several times, includes a plurality of slits formed in a casting direction for increasing a curvature of a meniscus(19) by transmitting the electromagnetic force and Joule heat of the coil generated by the power supply with respect to the outer surface of the mold wound with the coil to the ingot contacting the mold, thereby casting the slab under no oscillation, wherein the coil is applied with a frequency 10-200kHz and a coil current 500-5000A.

Description

Mold-free vibration-free electromagnetic continuous casting device {ELECTROMAGNETIC CASTING MACHINE WITHOUT MOLD OSCILLATION}

The present invention relates to an electromagnetic continuous casting apparatus capable of continuous casting without shaking the mold, and more particularly, to secure a wide flow path through which the mold powder flows into the electromagnetic pressure generated when the power is applied, thereby enabling the inflow of the mold powder without the need for mold vibration. The present invention relates to a moldless vibration-free electromagnetic continuous casting device that can manufacture high quality cast steel and improve energy.

In general, as shown in Figure 1, the continuous casting device is to produce a cast while supplying molten steel in the tundish into the mold (2) through the nozzle (9), in the case of continuous casting of steel in such a continuous casting process In order to smoothly supply the mold powder (4), which is a lubricant, between the (2) and the cast steel, and to prevent the sticking of the cast and the mold (2) a separate vibration generating device (not shown) (2) We arrange in the neighborhood and perform mold vibration.

On the surface of the cast steel cast in such a process, a hook 8 is formed due to overcooling of the hot water surface part, and as the hook 8 grows, an oscillation mark due to vibration of the mold 2 is generated. (3), a number of defects including the horizontal, vertical cracks (crack), etc. occurs, and because the passage between the mold (2) and the slab is narrow, it is difficult to flow into the mold powder (4).

The surface defect of the cast steel has a great influence on the productivity and workability of the continuous casting process, such as causing breakout during the casting and stopping the casting operation.

In addition, casts that have surface defects may need to be removed by means of scarping, grinding, etc. before delivering them to the post-process. It involves material loss.

On the other hand, many techniques have been proposed to improve cast quality after the technology for continuously casting molten steel while vibrating the mold.

First, heating mold powders have been developed to improve the lubricity between mold and cast steel and to increase mold powder consumption. However, this did not completely eliminate surface defects and slightly reduced the depth of oscillation marks. 5 (1992) p207)

Second, the casting vibration method was changed from sine wave to ladder type and saw tooth type to improve casting surface quality, but this method also could not completely solve the surface joining of cast steel. (1985) p247)

Thirdly, an electronic stirring device was installed in the mold to control the molten steel flow in the mold to solve the surface defect. However, this method does not eliminate the oscillation mark but merely reduces the depth to reduce the surface defect of the cast steel. A more aggressive method is needed to realize direct rolling.

It is the electromagnetic continuous casting technology that has been studied by such a demand. Electromagnetic casting (EMC) technology is developed in the form of a moldless casting, which replaces the mold with electromagnetic force for materials with low specific gravity and good electrical conductivity, and has a semi-contact type that uses a mold for continuous casting of molten steel. Research has been attempted to apply EMC in the form of soft contact casting.

In the case of such continuous electromagnetic casting, mold vibration is also performed, and instability of the molten surface occurs due to the vibration of the mold, so that the molten metal overflows and the oscillation mark is not completely solved.

Therefore, the present invention has been made in order to solve the above problems, the object is to install a coil that can apply an electromagnetic field to the outside of the electromagnetic mold during molten steel induction heating the hot water surface and the mold powder by electromagnetic pressure It secures the inflow channel widely so that the mold powder flows well and casts steel without mold vibration to solve various surface defects caused by mold vibration, and improves product quality and energy by realizing continuous casting-rolling direct connection process. In addition, to provide a mold-free vibration-free electromagnetic continuous casting device that can secure a continuous casting facility of a simple structure without a mold vibration device.

1 is a schematic view showing a typical continuous casting device,

Figure 2 is a longitudinal sectional view showing a mold vibration-free electromagnetic continuous casting device according to the present invention,

Figure 3 is a perspective view showing a mold vibration-free electromagnetic continuous casting device according to the present invention,

Figure 4 (a) is also the surface state of the cast slab while the mold vibration without electromagnetic field,

Figure 4 (b) is a surface state of the cast slab while performing the mold vibration during electromagnetic field application,

Figure 4 (c) is a surface state of the cast slab without performing the mold vibration during electromagnetic field application,

5 is a graph showing the consumption of the mold powder according to the casting conditions

* Explanation of symbols for the main parts of the drawings *

3 ..... Oscillation Mark 4 ..... Mold Powder

8 ..... Hook 9 ..... Immersion nozzle

10 .... solidified shell 14 .... slit

15 .... Coil 19 .... Manikus Curvature

The present invention as a technical configuration for achieving the above object,

In the electromagnetic continuous casting device is supplied to the molten steel through the immersion nozzle, casting the cast using a mold wound the coil multiple times on the outer surface,

Vibration-free by forming a plurality of slits in the casting direction so that the electromagnetic force and Joule heat generated when the power is applied to the outer surface of the mold wound around the coil to the molten steel side in contact with the mold to form a large meniscus curvature. It is to provide a mold-free vibration-free electromagnetic continuous casting device, characterized in that casting the cast in the state.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

Figure 2 is a longitudinal cross-sectional view showing a mold vibration free electromagnetic continuous casting apparatus according to the present invention, Figure 3 is a perspective view showing a mold vibration free electromagnetic continuous casting device according to the present invention, as shown, the apparatus (1) ) Coils the coil 15 to the outer surface of the mold 20 to which the molten steel is supplied through the immersion nozzle 9, and casts the cast while generating an electromagnetic field and joule heat to the molten steel side when the power is applied.

On the outer surface of the mold 20 in which the coil 15 is wound, the electromagnetic force and joule heat of the coil 15 generated when the power is applied are transferred to the molten steel side in contact with the inner surface of the mold 20. A plurality of slits 14 are formed in a casting direction to form a large curvature 19, and the slits 14 are special sealing materials through which electromagnetic fields and joules heat can be generated while preventing external flow of supplied molten steel. It is sealed with.

At this time, a frequency of 10 ~ 200kHz, coil current 500 ~ 5000A is applied to the coil 15.

And, the slit 14 formed in the mold 20 is formed in the casting direction to a range of four times the width (W) of the coil 15 at a portion 10mm away from the upper end of the mold 20, the length Extends above the coil 15 to the width W x 1 of the coil 15, below the coil 15 to the width W x 2 of the coil 15, and the slit 15. The width of is preferably 0.3 mm ± 0.2 mm.

When an external power source is applied to the coil 15 of the mold 20 in which the slit 14 is formed on the outer surface in the casting direction, an electromagnetic field is generated in the mold 20 divided into the slit 14. A current is induced by this magnetic field, which generates an induction magnetic field and a current through the slit 14 in the molten steel that is the molten metal inside the mold 20.

The induced current not only heats the molten metal molten metal with Joule heat, but also acts as a magnetic field to generate an electromagnetic force 18 in the molten metal.

The present invention supplies the power of a certain intensity to the coil 15 wound on the outer surface of the mold 20 to be supplied of molten steel, the slit formed on the outer surface of the mold 20 Joule heat and electromagnetic force generated when the power is applied By casting to the molten steel side through (14), casting the cast having excellent surface quality in the vibration-free state.

That is, the electromagnetic force generated in the coil 15 increases the curvature of the meniscus 19 of the molten steel which is formed while contacting the mold 20, thereby supplying a mold powder 4 supplied to the upper portion of the molten steel. It improves the inflow and at the same time reduces the contact pressure between the solidification shell 10 and the mold 20.

In addition, the surface of the molten steel is intensively heated by Joule heat, so that a thin initial solidification shell 10 is formed at the lower portion of the meniscus 19 to suppress the occurrence of the hook which is the source of the oscillation mark.

In addition, since the joule heat serves to delay the solidification of the mold powder existing between the cast and the mold 20, this not only promotes heat transfer between the solidification shell 10 and the mold 20. The widthwise deviation of heat transfer is also reduced.

As described above, the electromagnetic force and joule heat transmitted to the molten steel side through the slit 14 when the power of the coil 15 is applied acts as the molten steel side which is in contact with the mold 20, and thus, between the slab 20 and the molten steel. The inflow passage 11 of the mold powder 4 formed in the widen, the dissolution of the mold powder 4 is promoted, the fluidity is improved, the inflow of the mold powder 4 is increased significantly than in the general casting.

Therefore, even if the mold 20 is not vibrated using a separate vibrator, the mold powder 4 flows well between the cast steel 20 and the molten steel to perform continuous casting in a mold-free vibration state.

And, if the vibration does not occur in the mold 20, there is no need for a separate vibration device (hydraulic equipment or electric motor) to vibrate the mold 20, it is possible to configure the casting equipment more simply, It is possible to eliminate the oscillation mark (oscillation mark) of the surface portion of the cast due to the mold vibration can significantly contribute to surface quality improvement.

If mold vibration is applied while applying electromagnetic field, instability of melt surface occurs due to mold vibration, but if mold vibration is not performed, melt surface is stabilized and the surface shape of cast steel is greatly improved, and less electromagnetic field is applied during mold vibration. Even better effect can be obtained.

<Example>

In order to confirm the effect of the present invention, the following three types of casting experiments were conducted.

That is, Fig. 4 (a) shows the surface state of the cast steel while casting the mold without applying an electromagnetic field, and Fig. 4 (b) shows the surface state of the cast steel while applying the electromagnetic field and performing mold vibration. 4 (c) shows the surface state of the cast slab without applying an electromagnetic field and performing mold vibration.

At this time, as a result of measuring the roughness of each of the surface of the cast as a shape measuring device, the oscillation mark depth is 0.6 mm in FIG. 4 (a), 0.2 mm in FIG. 4 (b), and FIG. 4 (c). In the case of), it can be confirmed that the measurement is 0.1 mm or less, and thus, in the case of the present invention, the surface shape of the cast steel is very good.

In addition, the consumption of the mold powder 4 was examined in the present invention, in which the mold powder 4 can be introduced without the mold vibration.

That is, as shown in Fig. 5, in the case of the present invention (c) in which the mold vibration is not applied while applying the electromagnetic field, the consumption of the mold powder is the case in which the mold vibration is performed without applying the electromagnetic field (a), that is, during normal casting. About 400g was consumed, which is about 30% more than (about 300g consumption).

This amount of mold powder consumption is less than the case (b) when the mold vibration is applied while applying an electromagnetic field, but it is more than the consumption required for stable operation.

In conclusion, it was confirmed that even without applying the vibration of the mold while applying the electromagnetic field, it was possible to obtain a significantly improved good surface shape of the cast steel and to introduce sufficient mold powder 4 for stable casting.

In addition, when casting the cast while applying a current of 1000 A to the coil 15 while applying vibration to the mold 20 side, the depth of the oscillation mark appearing on the surface of the cast was reduced by about 67%, as in the present invention ( In the case where the cast was cast while applying a current of 800 A to the coil 15 without applying vibration to 20), the depth of the oscillation mark appearing on the surface of the cast was reduced by about 83%.

From these results, it can be seen that casting the cast while applying the electromagnetic field without the mold vibration can achieve a better effect at about 80% lower power than casting the cast while applying the electromagnetic field during the mold vibration. .

According to the present invention as described above, there is no need for a separate facility for the vibration of the mold to simplify the configuration of the casting equipment to simplify the structure of the equipment, to reduce the maintenance cost for maintaining it, the quality of the cast surface In addition to the conventional method, it is possible not only to significantly improve the conventional art, but also to reduce the amount of power used significantly compared with the electroforming process while vibrating the mold.

Claims (3)

In the electromagnetic continuous casting device, the molten steel is supplied through the immersion nozzle (9), and the cast steel is cast using a mold (20) wound on the outer surface of the coil (15), The electromagnetic force and joule heat of the coil generated when the power is applied to the outer surface of the mold 20 in which the coil 15 is wound may be transferred to the molten steel side in contact with the mold 20 to form a large meniscus curvature 19. Moldless vibration-free electromagnetic continuous casting device, characterized in that for casting a slab in a vibration-free state by forming a plurality of slits 14 in the casting direction so that. The method of claim 1, Moldless vibration-free electromagnetic continuous casting device, characterized in that the coil 15 is applied with a frequency 10 ~ 200kHz, coil current 500 ~ 5000A. The method of claim 1, The slit 14 is formed in the casting direction up to four times the width (W) of the coil 15 at a portion 10mm away from the upper end of the mold 20, the length of the coil above the coil 15 (15) to the width (W) x 1, the bottom of the coil 15 extends to the width (W) x 2 of the coil 15, the width of the slit 15 is 0.3mm ± 0.2mm Moldless vibration-free electromagnetic continuous casting device characterized in that the configuration.