KR101254110B1

KR101254110B1 - Continuous Casting Apparatus for Manufacturing Double-layered Metal Slab

Info

Publication number: KR101254110B1
Application number: KR1020100133037A
Authority: KR
Inventors: 박준표; 김종호
Original assignee: 재단법인 포항산업과학연구원
Priority date: 2010-12-23
Filing date: 2010-12-23
Publication date: 2013-04-12
Also published as: KR20120071475A

Abstract

The present invention relates to a multi-layer slab continuous casting device, and more specifically, two molten metals having different components are cast through a nozzle to an inner mold and an outer mold, and the outer mold is provided with a cooling device and an electromagnetic stirring device. And an electromagnetic coil is installed inside the inner mold, and a cooling water circulation path is formed to enable control of the outer cast and the inner cast, to suppress the formation of oxides at the cast interface, and to provide a large temperature variation. Even if the present invention relates to a multi-layer slab continuous casting device with improved performance so that it can be cast into a high-quality multilayer cast.
In the present invention, the multilayer cast slab continuous casting device is a multilayer cast slab continuous casting device having an inner mold and an outer mold to be cast by receiving a molten metal having a different component through a nozzle, wherein the outer mold outside the cooling device and the electromagnetic The stirring device is installed, the inner mold is characterized in that the electromagnetic field coil is installed in the mold and the cooling water circulation path is formed.
According to the present invention, it is possible to control the interface of the two metals with different melting temperatures and compositions, to control the structure of the cast steel, and to control the casting speed and quality through controlling the cooling water and the applied electromagnetic force of the mold. In addition, the present invention is composed of an inner mold and an outer mold that can control the solidification rate and structure of the cast steel by applying an electromagnetic field, a good contact interface between the inner and outer metal of the multilayer cast, the internal quality is uniform, the multilayer cast There is an effect that can be prepared.

Description

Continuous Casting Apparatus for Manufacturing Double-layered Metal Slab}

The present invention relates to a multi-layer slab continuous casting device, and more specifically, two molten metals having different components are cast through a nozzle to an inner mold and an outer mold, and the outer mold is provided with a cooling device and an electromagnetic stirring device. And an electromagnetic coil is installed inside the inner mold, and a cooling water circulation path is formed to enable control of the outer cast and the inner cast, to suppress the formation of oxides at the cast interface, and to provide a large temperature variation. Even if the present invention relates to a multi-layer slab continuous casting device with improved performance so that it can be cast into a high-quality multilayer cast.

In general, when ingots are made of molten metal, molten metal is injected into a mold to solidify and formed into a plate or rod, and the length is 2 to 3 m. Is made in a way. However, the more advanced continuous casting method produces a long ingot up to several tens of meters by continuously pouring from the top of the water-cooled mold, pulling out the bottom of the mold, and drawing the hardened ingot down. Can be.

In the individual casting method, molten metal injected into the mold is solidified after being filled in the mold, but in continuous casting, in the bottomless and shallow mold, the upper part is molten metal and hardens from the surroundings as it descends. Therefore, the funnel-shaped molten metal part is in the center, and long ingots emerge from the bottom in turn.

The continuous casting as described above is also used to produce a single-layered cast of one metal, but can also be used to manufacture a multilayer cast composed of a metal having a surface layer portion and a core portion of the cast steel. The prior art of manufacturing such a multilayer cast is disclosed in US Patent Publication No. 2007/0215312.

Figure 1 is a front view of the multilayer cast iron manufacturing apparatus according to the prior art is shown by cutting a portion. In FIG. 1, one side of the water jacket 12 storing the wall 11 and the coolant 13 to flow the wall 11 forming the rectangular casting mold 10 also serves as a wall of the rectangular casting mold 10. Indicates.

The injection-molded portion of the casting mold 10 is divided into two injection chambers by the partition wall 14. The first molten metal supplied from the injection nozzle 15 and the first storage container 30 provided with the adjusting rod 32 is supplied to the first chamber at the bottom thereof to form the molten metal 18 of the core part. The second molten metal supplied from the injection nozzle 16, the side channel, and the second storage container 24 provided with the adjusting rod 31 is transferred to the second chamber at the bottom thereof to form the molten metal 18 in the surface layer portion. Supplied.

The vertically movable pedestal 17 blocks the inlet of the mold before the start of casting so as to support the multilayer ingot that begins to be initially formed, and then gradually descends downwardly in accordance with the solidification speed since the ingot is formed.

FIG. 2 is an enlarged partial cutaway view of a cast steel fabrication apparatus for explaining a process of forming a surface layer portion and a core portion of a multilayer cast according to the prior art. Referring to FIG. 2, in the first chamber, the molten metal 18 of the core is gradually cooled to form a self-supporting surface 27 adjacent to the lower end of the partition 14. Thus forming a semi-solidified region 19 between the liquid and the solid, sometimes referred to as the puff layer. The lower portion of this semi-solidified region 19 is the solid region 20 region. Molten metal flowing into the second chamber also forms the surface layer portion 21 of the multilayer cast piece, and the solidification region 22 and the solid region 23 are formed.

The temperature of the partition 14 is maintained at a predetermined temperature by means of cooling means passing through the reservoir 33. The reservoir 36 is provided with an inlet 36 and an outlet 37 so that heat can be taken out of the partition 14 to inject or remove the cooling water to control the temperature. The chilled interface thus formed acts to control the temperature of the self supporting surface 27 below the lower end 35 of the partition 14.

The upper surface 34 of the second chamber molten metal 21 is located below the lower end 35 of the partition 14. The temperature of the self supporting surface 27 is also the self supporting surface when the upper surface 34 of the molten metal 21 is at the temperature of the self supporting surface 27 between the solidification temperature and the liquefaction temperature of the molten metal 18. (27) is kept in contact.

However, according to the prior art, the multilayer cast steel continuous casting apparatus having a chamber divided into an inner mold (first chamber) and an outer mold (second chamber) has no heating means in the inner mold, so that the molten metal of the core part When it starts to form the self-supporting surface 27 while solidifying, there is a problem that the tissue control of the core slab is impossible at all.

In addition, there is only a cooling device in the outer mold, there is no molten metal stirring device or heating means, and once the surface layer cast is transitioned to the solidification process, it is no longer possible to control the structure of the surface cast slab. There is a problem that it is impossible to manufacture a multilayer cast.

Also, in the prior art, the upper surface 34 of the molten metal 21 of the second chamber is located below the lower end 35 of the partition 14, so that a part of the self supporting surface 27 forming the core part is in the atmosphere. It is a structure that can only be exposed. This produces an oxide and an intermetallic compound at the slab interface of the core portion and the surface layer portion, which leads to a problem of deterioration of the quality of the multilayer cast.

In addition, in the prior art, when casting a multilayer cast, there is no facility for heating or stirring the molten metal from the outside of the mold, and thus a large temperature variation occurs inside the molten metal. Therefore, it is not possible to reduce the thickness of the cast steel and only cast a double-layer cast, such as sandwich, there is a problem that the slab casting that the outer material wraps the inner material as in the present invention is impossible.

The present invention was devised to solve the problems of the prior art as described above, and the present invention provides a device capable of manufacturing a high quality multilayer cast by solving the temperature non-uniformity of the molten metal in the mold generated during continuous casting of the multilayer cast. It aims to do it.

In order to achieve the above object, the multilayer cast slab continuous casting apparatus of the present invention is a multilayer cast slab continuous casting apparatus having an inner mold and an outer mold to be supplied by casting a molten metal having a different component through a nozzle, A cooling device and an electromagnetic stirring device are installed outside the outer mold, and the inner mold is characterized in that an electromagnetic coil is installed inside the mold and a cooling water circulation path is formed.

In the present invention, the outer surface of the outer mold is characterized in that the slit for applying an electromagnetic field is processed, and further characterized in that the high frequency electromagnetic field coil is installed on the electromagnetic stirring apparatus of the outer mold, and the outer The slits processed on the outer surface of the mold are processed in the range of 10 mm from the upper part of the mold to the bottom of the mold in a range of 0.3 ± 0.2 mm and a gap of 100 to 400 mm, and the electromagnetic stirring device is located at a lower part of the electromagnetic coil from 300 mm to the bottom. It is characterized by being installed.

According to the present invention, it is possible to control the interface of the two metals with different melting temperatures and compositions, to control the structure of the cast steel, and to control the casting speed and quality through controlling the cooling water and the applied electromagnetic force of the mold.

In addition, the present invention is composed of an inner mold and an outer mold that can control the solidification rate and structure of the cast steel by applying an electromagnetic field, a good contact interface between the inner and outer metal of the multilayer cast, the internal quality is uniform, the multilayer cast There is an effect that can be prepared.

1 is a front view of a multilayer cast iron manufacturing apparatus according to the prior art is a view showing a portion cut.
FIG. 2 is a view for explaining, in particular, the interface part in the multilayer cast steel manufacturing apparatus of FIG. 1.
3 is a front sectional conceptual view of a multilayer cast steel manufacturing apparatus of the present invention.
Figure 4 is a conceptual diagram for explaining the temperature distribution of the cast steel and the cast according to the prior art manufactured in a multilayer cast steel manufacturing apparatus with an electromagnetic stirring device of the present invention.

The main technical idea of the present invention is to install an electromagnetic stirring device on the outside of the multilayer mold casting outer mold to apply a lateral stirring technique in which the molten metal is perpendicular to the casting direction. According to the present invention, the molten metal in the mold may be stirred in the transverse direction to uniform the temperature of the molten metal. When the molten metal temperature is uniform, the surface solidification of the cast steel may be uniform, thereby increasing the casting stability and improving the surface quality of the multilayer cast. Can be.

In addition, the dendritic structure is cut by the stirring of the melt to change to the equiaxed crystal structure, and the grain size becomes finer, thereby improving the quality of the multilayer cast core part.

The present invention is a multilayer cast continuous casting device composed of an inner mold and an outer mold that can control the solidification speed and structure of the cast by applying an electromagnetic field, a sound interface formation, core and surface layer that cannot be solved by the conventional technology Temperature control, casting of other metals with different melting temperatures, and the like. Hereinafter, the detailed configuration and operation of the present invention will be described in detail with reference to the accompanying drawings.

3 is a front sectional conceptual view of a multilayer cast steel manufacturing apparatus of the present invention. Figure 4 is a conceptual diagram for explaining the temperature distribution of the cast steel and the cast according to the prior art manufactured in a multilayer cast steel manufacturing apparatus with an electromagnetic stirring device of the present invention.

Referring to FIG. 3, in the present invention, the multilayer cast slab continuous casting device supplies molten metal having different components from the nozzle 3 to the outer mold 1 and the inner mold 2. Nozzles provided for supplying the molten metal to the outer mold 1 are provided one by one on both sides of the long side or both sides of the short side.

A cooling device 4 is installed outside the outer mold 1 to control the amount of cooling water to solidify the surface of the outer (surface layer) slab. At this time, by installing an external coil 5 that can apply a high frequency electromagnetic field outside the upper part of the outer mold 1 to apply the electromagnetic field to the molten metal to generate Joule heat to control the solidification rate of the cast. In addition, the low frequency electromagnetic stirring device 7 is installed below the electromagnetic external coil 5 of the outer mold 1 to agitate the molten metal to improve the internal quality of the cast on the surface layer.

In the electromagnetic coil application external coil 5 provided above the external mold 1, the number of coil turns is 1 to 10 times, the coil current frequency range is 100 to 100,000 Hz, and the coil current is 20 to 1000 A.

The number of turns of the coil is correlated with the current value applied to the molten metal. If the number of windings is lowered, a large amount of current is supplied. If the number of windings is large, the applied current may be lowered. Due to the configuration of the device, there was a limit to the space where the coil could be installed, so it was 1 ~ 10 times and the upper limit of the applied current was about 2000A.

The coil current is induced inside the mold and acts on the surface of the melt to generate electromagnetic pressure and heat. The electromagnetic pressure acts on the center of the mold to reduce the contact pressure between the molten metal and the mold, thereby reducing the friction between the cast and the mold. In this case, if the frequency of the power supply is low, stirring force is generated on the surface of the melt, and thus the surface of the melt cannot be maintained stably.

In addition, heat is generated in the molten metal due to an applied current, and heat must be concentrated on the molten surface to prevent irregular solidification from occurring on the surface of the molten metal. Therefore, the lower limit of the frequency of the power supply was 100 Hz. If the frequency of the power supply is high, electromagnetic pressure and heat can be effectively used, but the upper limit was 100,000 Hz due to the limitation of the power supply.

In the electromagnetic stirring device 7 installed at the lower end of the outer mold 1, the power frequency range is 2 to 100 Hz, the coil current is 20 to 1000 A, and the position of the electromagnetic stirring device 7 is the electromagnetic external coil 5. ) It is from the bottom to 300mm bottom.

The coil in the present invention is an apparatus that effectively generates a stirring force in the molten metal. Therefore, the lower the frequency, the longer the penetration depth of the electromagnetic field and the greater the stirring force. Since this coil is installed below the molten surface, the surface of the cast steel is in a solidified position. Therefore, if the frequency is less than 2Hz, the stirring force is weak, and if it exceeds 100Hz, the electromagnetic field is applied to the outside of the cast steel, the electromagnetic field applied to the interior of the molten metal is reduced, the stirring force does not occur. Therefore, the upper limit of the frequency was 100 Hz. The installation position of the outer coil 5 is related to the depth of the molten metal forming the cast steel. Since the depth of the molten metal does not normally exceed 300 mm, it is not preferable to install the coil under the slab.

The material of the outer mold 1 is copper or aluminum with good electrical conductivity, and slits are processed in the longitudinal direction of the outer mold 1 so that an electromagnetic field can be efficiently induced into the molten metal. In the outer mold 1 which processed the slit which can apply an electromagnetic field as mentioned above, the slit processing range processes a slit in the casting direction from the part 10 mm apart from the upper part of the outer mold 1 to the lower end of a mold, The width should be 0.3mm ± 0.2mm and be properly processed between the slits 100 ~ 400mm.

The slit is processed so that the electromagnetic field is guided to the molten metal well, and if the width is wide, the molten metal may leak out of the mold. Therefore, the slit may be narrowly processed. If the slit width is widened, coagulation unevenness occurs in the slit. Therefore, the width of the slit is preferably limited to the above range.

The spacing of the slits is also important to ensure that the electromagnetic field is uniformly applied to the cast steel. If the slit spacing is wide, the nonuniformity of the electromagnetic field is increased and the intensity of the applied electromagnetic field is weakened. Therefore, it is efficient to limit the range to the above range.

The inner mold 2 is made of copper, and a coolant circulation path is formed in the inner mold 2 so that the coolant can be circulated. The cooling water circulation path of the inner mold 2 is obtained along a mold inner surface and discharged along the mold outer surface. In addition, the inner mold (2) is provided with a height adjustment means to be able to move.

In addition, the inner coil 6 is installed inside the inner mold 2 to apply an electromagnetic field. An electromagnetic field is applied to the inner coil 6 to control the solidification rate of the outer part of the core (inner) melt and the inner part of the surface layer (outer) melt, and the molten metal is stirred to control the structure of the cast steel.

In the internal coil 6 capable of applying the electromagnetic field and the internal mold 2 provided with the cooling function as described above, the electromagnetic field applied frequency range of the internal mold 2 is 1 to 1000 Hz, and the internal coil current is 10 to 300 A. to be.

The purpose of the power applied to the inner mold is to stir the molten metal. The lower the frequency applied to the electromagnetic field, the more effective. Therefore, it is set to 1 ~ 1000Hz. In addition, since the structure of the mold is difficult to supply a large amount of current, the upper limit of the current was set to 300A because the structure was designed to increase the number of windings of the coil and reduce the current.

Hereinafter, the operation of the multilayer cast continuous casting device of the present invention will be described.

First, in order to operate the apparatus of the present invention, in the mold consisting of the inner mold (2) and the outer mold (1) by raising the dummy bar (corresponding to the "movable pedestal" of the prior art) to the lower surface of the inner mold (2) Then, the molten metal is supplied to the sealed inner mold 2 and the outer mold 1 through the nozzle 3 with different melt components.

First, the internal molten metal starts to cool from the outer skin part by the cooling water flowing into the cooling water circulation path formed in the inner mold 2. Here, the cooling water circulation path of the inner mold 2 is obtained along the inner surface of the mold and discharged along the outer surface of the mold, thereby exhibiting a strong cooling effect.

Since the inner mold 2 is provided with a height adjusting means so as to be movable up and down, the inner mold 2 is raised or lowered when necessary for temperature control and the like. When the outer surface of the inner molten metal starts to solidify based on the cooling, the outer molten metal is supplied through the nozzle at this time, and the outer molten metal is cooled by a cooling device installed on the outer side of the outer mold 1. When the core and the surface layer are hardened to some extent, the shape of the multilayer cast steel is formed, and when the solidified state does not collapse even when moved, continuous casting starts while lowering the dummy bar.

At this time, the electromagnetic stirring device 7 provided on the outside of the outer mold 1 is operated to perform the process of stirring the inner molten metal over the entire inner and outer molten metal on the transverse side which is the direction orthogonal to the casting direction. . In this case, when necessary, the electromagnetic field may be applied to the high frequency electromagnetic field outer coil 5 installed on the outer mold 1 or the inner coil 6 embedded in the inner mold 2 to increase the temperature of the molten metal. .

Therefore, the internal and external molten metal is heated violently by the operation of the electromagnetic stirring device 7 while appropriately combining cooling by the cooling device or heating through the electromagnetic coil as necessary throughout the internal and external molten metal. By stirring properly, the temperature distribution of the inner and outer molten metals can be adjusted appropriately and uniformly, thereby making it possible to homogeneously control the structure of the multilayer cast steel to produce a high quality multilayer cast steel.

Figure 4 is a conceptual diagram for explaining the temperature distribution of the cast steel and the cast according to the prior art manufactured in a multilayer cast steel manufacturing apparatus with an electromagnetic stirring device of the present invention. As shown in FIG. 4, the temperature distribution in the mold in the absence of the electromagnetic stirring device is lower in the longitudinal center portion or the left and right side portions of the surface layer in the drawing, but the electromagnetic stirring device as in the present invention is installed and operated. It can be seen that the temperature distribution appears uniformly throughout the core and surface layer portions.

As for the parts that are not described in detail in the present invention, the above description of the related art may be used. In addition, this invention demonstrated one Example, The scope of this invention has the effect also to the deformation | transformation and improvement technique which can be easily conceived from this invention.

1: outer mold 2: inner mold 3: nozzle
4 cooling device 5 outer coil 6 inner coil
7: electromagnetic stirring device

Claims

In the multi-stage slab continuous casting apparatus having an inner mold and an outer mold to be supplied by casting a molten metal having a different component through a nozzle,
A cooling device installed outside the outer mold;
An outer coil of the high frequency electromagnetic field, which is installed outside the upper part of the outer mold and controls the solidification rate of the cast steel by applying the electromagnetic field to the molten metal to generate joule heat;
A low frequency electromagnetic stirring device installed at a lower portion of the outer coil to a lower portion of 300 mm;
A cooling water circulation path inside the inner mold, the cooling water circulation path being formed along a mold inner surface and discharged along the mold outer surface;
An inner coil installed inside the inner mold to control the solidification rate of the outer portion of the inner melt and the inner portion of the outer melt by applying an electromagnetic field, and to control the structure of the cast steel by stirring the melt;
Multi-layer slab continuous casting apparatus characterized in that it comprises a height adjustment means for enabling the inner mold to move up and down

The method of claim 1,
Multi-layer cast slab continuous casting apparatus characterized in that the outer surface of the outer mold is processed with a slit to apply an electromagnetic field

delete

The method of claim 2,
The slit processed on the outer mold outer surface is a multi-layer slab continuous casting device, characterized in that the width of the mold from 10mm to the bottom of the mold: 0.3 ± 0.2mm, interval: 100 ~ 400mm