JP2006130553A - Mold for continuous casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold for continuous casting in which an air gap generated between its inner surface and the surface of an ingot is relaxed. <P>SOLUTION: The mold for continuous casting is provided with a casting hollow part 2 formed of a pair of long side faces 4 and a pair of short side faces 3, and in which the inlet side 13 of molten metal and the outlet side 16 of an ingot are released, and the cross-section on the inlet side is larger than the cross-section on the outlet side, and in the casting hollow part 2, the taper angle θ<SB>1</SB>of each central part 5 in the pair of long side faces 4 is wider than the taper angle θ<SB>2</SB>in each corner part 6 thereof. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a continuous casting mold of an ingot having a short cross section, and more particularly, copper or copper capable of relaxing an air gap generated between the central surface of the long side in the mold and the ingot surface. The present invention relates to a continuous casting mold suitable for continuous casting of alloys and the like.

  In continuous casting of copper or copper alloy, in order to cast a continuous copper or copper alloy ingot, a molten copper or copper alloy is poured into the hollow portion of the mold and cooled.

FIG. 8 is an explanatory diagram showing an outline of continuous casting by a conventional vertical continuous casting machine.
In FIG. 8, continuous casting of a long ingot is performed by pouring a molten metal 30 of copper or copper alloy from a molten metal nozzle 20 into a mold 21 made of a material such as copper, copper alloy, or carbon, and from the mold wall. A solidified shell having a sufficient thickness is formed by heat removal. Thereafter, the solidified shell is continuously drawn out from the lower side of the mold 21 as an ingot 33 in the casting direction 34, and then water is discharged in the form of a shower or spray. The ingot 33 such as copper or copper alloy is continuously cast by cooling with the next cooler 25 and then directly cooling with water through the water tank 26. At this time, an air gap 37 is generated between the mold 21 and the surface of the ingot 33.

FIG. 9 is an explanatory view showing the concept of the shrinkage shape of the ingot and the air gap in the transverse section (CC longitudinal section in FIG. 8) in the casting direction by the conventional continuous casting mold.
According to the CC cross section of FIG. 8 shown in FIG. 9, the ingot 33 is solidified between the surface of the long side surface 24 of the continuous casting mold 21 and the surface of the ingot 33 of the casting hollow portion 22. Due to the shrinkage of time, a gap atmosphere layer is generated, and an air gap 37 is formed. When the air gear 37 is generated, heat transfer from the unsolidified portion 31 to the mold 21 on the surface of the long side surface 24 becomes radiant heat transfer, which is compared with heat transfer at the direct contact portion between the ingot 33 and the mold 21. The heat flux is greatly reduced.

On the other hand, in continuous casting of molten metal, it is known that when the molten metal is poured into a continuous casting mold and cooled, an air gap is generated between the mold and the ingot. (For example, Patent Document 1)
In order to deal with the problems associated with the occurrence of such air gaps, conventionally, a taper of an angle that allows for the amount of shrinkage of the ingot relative to the casting direction is uniformly formed in the casting hollow portion of the mold. Measures have been taken, such as a method for coping, a method for installing a cooling body and a heating element for cooling the mold, or a method for controlling the flow rate of cooling water to the ingot to optimize the cooling. (For example, Patent Document 1 and Patent Document 2)

The continuous casting mold of the prior art described in Patent Document 1 has a taper having an angle that allows for the amount of shrinkage of the ingot relative to the casting direction in the casting hollow portion of the mold.
In the continuous casting mold of the invention described in Patent Document 1, the central part of the long side of the mold is projected inward.

  The casting mold described in Patent Document 2 absorbs heat when a current is applied to the mold in order to uniformize the growth of the solidified shell formed immediately below the meniscus in the mold width direction during continuous casting of medium carbon steel. Cooling is controlled by installing a cooling element and a heating element composed of elements.

The casting mold described in Patent Document 3 is a mold for molten steel or molten aluminum, in which a plurality of cooling water grooves are formed at equal intervals between a copper plate and a back plate having a rectangular casting space having a rectangular cross section. Control is performed.
JP-A-2004-74172 [0008]. [0009]. (FIG. 2) Japanese Patent No. 3414219 (FIG. 2) Japanese Patent No. 3493966 (FIG. 3)

However, in rectangular ingots cast from a molten metal of copper or copper alloy, the long side of the rectangular cross section in which the solidified portion remains until the end of the ingot shrinkage amount, rather than near the corner of the rectangular cross section Since the central portion near the center is large, there remains a problem that air gaps are likely to occur remarkably in the ingot near the center of the long side of the rectangular cross section.
Further, when the drawing speed of the ingot is increased, the difference in ingot shrinkage tends to increase between the center of the long side of the rectangular cross section and the vicinity of the corner portion. Further, there is a problem that the amount of contraction at the center of the long side becomes very large depending on the type of copper alloy.

  On the other hand, when casting an ingot with a rectangular cross-section from a molten copper or copper alloy to the mold with a uniform taper in the casting direction as in the prior art, it matches the shrinkage near the center of the long side of the rectangular cross-section. If the taper is formed, the taper near the corner of the rectangular cross section becomes excessively large, so that the ingot and the mold are worn during casting, and there is a problem that the mold is damaged and the ingot surface is cracked. .

  Furthermore, when the taper is adjusted to the contraction amount near the corner portion of the rectangular cross section, the air gap near the center of the long side of the rectangular cross section becomes prominent, and solidification failure occurs due to non-uniform heat removal from the mold. Although the amount of shrinkage of the ingot can be controlled to some extent by adjusting the flow rate of the cooling water, there is a problem that the air gap generated between the mold and the ingot cannot be sufficiently mitigated.

  In particular, when an air gap occurs between the surface of the long side of the mold and the surface of the ingot of the casting hollow portion, the heat transfer of that portion becomes radiant heat transfer, and the direct transfer between the mold and the ingot is direct. Compared with the heat transfer in the contact area, the heat flux is greatly reduced, so the ingot during solidification has cracks on the surface, coarse and uneven texture, and intergranular cracking due to these. There is a problem of significantly degrading the quality. In noticeable cases, the solidified shell may re-dissolve and cause leaks.

  Accordingly, an object of the present invention is to alleviate air gaps that tend to occur between the center of the long side surface of the mold and the ingot surface in continuous casting of an ingot such as copper or copper alloy having a rectangular cross section. An object of the present invention is to provide a casting mold for continuous casting.

  Another object of the present invention is to provide a continuous casting mold capable of preventing cracks on the surface of an ingot such as copper or copper alloy having a rectangular cross section, coarsening or non-uniformity of the structure, and intergranular cracking. It is to provide.

In order to achieve the above object, the present invention is formed by a pair of long side surfaces and a pair of short side surfaces, the molten metal inlet side and the ingot outlet side are opened, and the sectional area of the inlet side is In a continuous casting mold with a casting hollow part larger than the cross-sectional area on the outlet side,
The casting hollow part is provided by a continuous casting mold characterized in that a center part of the pair of long side surfaces is formed by the cross-sectional area on the entrance side having a taper angle larger than the corner part.

  In the present invention, the cross-sectional area on the inlet side of the casting hollow portion of the mold is preferably such that the long side surface extending from the central portion along the corner portion is formed by a single straight line.

  In the present invention, the cross-sectional area on the inlet side of the casting hollow portion of the mold is preferably such that the long side surface extending from the central portion along the corner portion is formed by a plurality of straight lines.

  In the present invention, the cross-sectional area on the inlet side of the casting hollow portion of the mold is preferably such that the long side surface extending from the central portion along the corner portion is curved.

  According to the continuous casting mold of the present invention, in continuous casting of an ingot having a rectangular cross section, it is possible to alleviate the air gap generated in the central portion of the long side surface of the casting hollow portion of the mold, and to achieve good casting. The effect that casting of copper, copper alloy, etc. which have lump quality is possible is acquired.

  In addition, according to the continuous casting mold of the present invention, it is possible to prevent cracking of the surface of the ingot such as copper or copper alloy, coarsening or non-uniformity caused by air gaps, The effect that a crack at the boundary can be prevented is obtained.

(First embodiment)
FIG. 1 is a front view showing a molten metal inlet side of a continuous casting mold according to a first embodiment of the present invention.
The continuous casting mold 1A shown in FIG. 1 is formed by a pair of long side surfaces 4 and a pair of short side surfaces 3, and the inlet side 13 of the molten metal and the outlet side of the ingot are opened, and the sectional area of the inlet side 13 Is provided with a cast hollow portion 2 larger than the cross-sectional area on the outlet side.
The casting hollow portion 2 has a taper 7A from the inlet side 13 of the molten metal along the outlet side of the ingot in order to make the sectional area of the inlet side 13 larger than the sectional area of the outlet side.

In the mold 1 </ b> A of FIG. 1, the taper 7 </ b> A of the cast hollow portion 2 is formed by a single straight line from the central portion 5 of the long side surface 4 of the cast hollow portion 2 along the corner portion 6.
Further, the taper 7 </ b> A is formed such that the taper angle at the central portion 5 of the pair of long side surfaces 4 is larger than the taper angle at the corner portion 6 of the long side surface 4.

FIG. 2 is a longitudinal sectional view showing a central portion (A-A in FIG. 1) of the long side surface of the continuous casting mold according to the first embodiment of the present invention.
In the mold 1A of FIG. 2, the taper 7A of the casting hollow portion 2 extends from the molten metal inlet side 13 to the ingot outlet side 16 so that the sectional area of the inlet side 13 is larger than the sectional area of the outlet side 16. In addition, the taper 7A of the cast hollow portion 2 has a taper angle θ ₁ of the central portion 5 of the pair of long side surfaces 4 at the corner portion 6 of the long side surface 4 on the inlet side 13 of the molten metal. The taper angle θ ₁ is larger than the taper angle (θ ₂ ).

FIG. 3 is a longitudinal sectional view showing a corner portion (BB longitudinal section of FIG. 1) of the long side surface of the continuous casting mold according to the first embodiment of the present invention.
In the mold 1A of FIG. 3, the taper 7A of the casting hollow portion 2 extends from the molten metal inlet side 13 to the ingot outlet side 16 so that the sectional area of the inlet side 13 is larger than the sectional area of the outlet side 16. However, the taper angle θ _{2 at} the corner of the long side surface on the inlet side 13 of the molten metal is smaller than the taper angle (θ ₁ ) at the center of the long side surface. .

According to the continuous casting mold 1A shown in FIGS. 1, 2 and 3, the taper 7A is formed so that the cross-sectional area of the inlet side 13 is larger than the cross-sectional area of the outlet side 16, and the casting hollow portion 2 is formed. Since the taper angle θ _{1 at} the center of the long side surface is formed by a single straight line so as to be larger than the taper angle θ _{2 at} the corner portion of the long side surface, the molten metal is continuous with the mold 1A. When casting, the solidification shrinkage of the molten metal on the long side surface of the casting hollow portion 2 and the taper 7A on the inner surface of the casting hollow portion 2 are aligned well, and an air gap is generated between the mold 1A and the ingot. Can be prevented. Moreover, the relaxation of the air gap that has occurred near the center of the long side surface can solve problems such as cracking of the ingot surface, coarsening and non-uniformity of the structure, and intergranular cracking that are likely to occur in the ingot.

(Second Embodiment)
FIG. 4 is a front view showing the molten metal inlet side of the continuous casting mold according to the second embodiment of the present invention.
The continuous casting mold 1B shown in FIG. 4 has a cross-sectional area of the inlet side 13 of the molten metal in the casting hollow portion 2 formed by the pair of long side surfaces 4 and the pair of short side surfaces 3, and is on the outlet side of the ingot. In order to form larger than the cross-sectional area, a taper 7B is provided from the molten metal inlet side 13 to the ingot outlet side.
The taper 7 </ b> B of the cast hollow portion 2 in FIG. 4 is formed by a plurality of straight lines from the central portion 5 of the long side surface 4 of the cast hollow portion 2 along the corner portion 6.
Further, the taper 7B is formed such that the taper angle at the central portion 5 of the pair of long side surfaces 4 is larger than the taper angle at the corner portion 6 of the long side surface 4.

  According to the continuous casting mold 1B shown in FIG. 4, since the taper 7B is formed by a plurality of straight lines, an air gap is generated between the mold 1B and the ingot as in the case of the mold 1A. Can be prevented.

(Third embodiment)
FIG. 5 is a front view showing the inlet side of the molten metal of the continuous casting mold according to the third embodiment of the present invention.
The continuous casting mold 1C shown in FIG. 5 has a cross-sectional area of the inlet side 13 of the molten metal formed in the casting hollow portion 2 formed by the pair of long side surfaces 4 and the pair of short side surfaces 3, and is on the outlet side of the ingot. In order to form a larger cross-sectional area, a taper 7C is provided from the inlet side 13 to the outlet side.
The taper 7 </ b> C of the cast hollow portion 2 in FIG. 5 is formed in a curve along the corner portion 6 from the central portion 5 of the long side surface 4 of the cast hollow portion 2.
The taper 7 </ b> C is formed such that the taper angle at the central portion 5 of the pair of long side surfaces 4 is larger than the taper angle at the corner portion 6 of the long side surface 4.

  According to the continuous casting mold 1C shown in FIG. 5, since it has a taper 7C formed in a curve, an air gap is prevented from being generated between the mold 1C and the ingot as in the case of the mold 1A. it can.

FIG. 6 is a front view showing the outlet side of the ingot of the continuous casting mold according to the embodiment of the present invention.
The continuous casting mold 1D of FIG. 6 has a casting hollow portion 2 having a rectangular cross section formed by a pair of long side surfaces 4 and a pair of short side surfaces 3 on the outlet side 16 of the ingot. The ingot cast in the casting hollow portion 2 flows out from the outlet side 16 as an ingot having a rectangular cross section.

FIG. 7 is a front view showing a deformation on the outlet side of the ingot of the continuous casting mold according to the embodiment of the present invention.
The continuous casting mold 1E shown in FIG. 7 has a pair of long side surfaces 4 and a pair of short side surfaces formed on the outlet side 16 of the ingot with the central portion 5 of the long side surface 4 protruding inwardly in a curved shape. 3 has a hollow casting section 2 having a rectangular cross section. The ingot cast by the casting hollow portion 2 flows out from the outlet side 16 as an ingot having a rectangular cross section with a curved constriction on the long side surface.

  The continuous casting mold of the present invention has been described for a mold used in a vertical continuous casting apparatus, but the continuous casting mold of the present invention can also be applied to a horizontal continuous casting machine.

  In the present invention, copper and a copper alloy are generally used as a material for a continuous casting mold. However, the material is not particularly limited to copper and a copper alloy, and may be composed of other refractory materials as long as the material has fire resistance. May be.

  In the continuous casting mold of the present invention, the continuous casting mold has a casting hollow portion whose sectional area on the inlet side is larger than the sectional area on the outlet side, and the center portion of the pair of long side surfaces has a taper angle larger than its corner portion. Therefore, the mold configuration may be an integral mold finished by hot forging and machining, or a combined mold in which a mold portion is coupled to a back plate. Alternatively, a mold in which a graphite sleeve is fitted into a copper water-cooled jacket may be used.

  The continuous casting mold of the present invention can be used by applying metal plating such as chromium on the surface of the casting hollow portion.

(Example)
As an example of the present invention, a case where a mold made of a copper alloy material is used in a vertical continuous casting machine will be described. The mold had a cross-sectional size of 210 mm × 540 mm and a length of 450 mm, and a continuous casting was performed by supplying a molten copper alloy containing 2.3% Fe to Cu to the casting hollow portion of the mold.
The taper angle formed in the hollow casting part is 5 ′ at the corner of the long side, 15 ′ at the center of the long side, and the short side in consideration of the shrinkage when the molten metal becomes an ingot. 10 'on the surface.
The molten metal surface of the casting hollow part was 50 mm from the upper end of the mold, and the molten metal surface was coated with a reducing gas to prevent molten metal oxidation. The ingot drawing speed was 100 mm / min.

After completion of the casting according to the example, an appearance inspection of the copper alloy ingot was performed.
As a result, no cracks or deep dents were found on the surface of the ingot having a rectangular cross section, and the appearance was good. In addition, no cracks were found inside the ingot, and the cross-sectional structure was a fine equiaxed crystal.

(Comparative example)
In the comparative example, a continuous casting mold according to a conventional technique was used. The condition was that continuous casting was performed by supplying a molten copper alloy containing 2.3% Fe in Cu to a mold made of copper alloy. The mold has a cross-sectional size of 210 mm × 540 mm and a length of 450 mm. The taper angle of the inner surface of the mold was uniformly 10 'on the long side surface. The ingot drawing speed was 100 mm / min.

After completion of casting according to the comparative example, an appearance inspection of the copper alloy ingot was performed.
As a result, on the surface of the ingot having a rectangular cross section, periodically deep depressions were observed at the center of the long side surface, and cracks were partially confirmed. The partial crack reached 20 mm from the surface at a deep location. The cross-sectional structure was a fine equiaxed crystal.

It is a front view of the inlet side of the molten metal which shows the casting mold for continuous casting by the 1st Embodiment of this invention. It is a longitudinal cross-sectional view which shows the center part of the long side surface of the casting mold for continuous casting by the 1st Embodiment of this invention. It is a longitudinal cross-sectional view which shows the corner part of the long side surface of the casting mold for continuous casting by the 1st Embodiment of this invention. It is a front view of the inlet side of the molten metal which shows the casting mold for continuous casting by the 2nd Embodiment of this invention. It is a front view of the inlet side of the molten metal which shows the casting mold for continuous casting by the 3rd Embodiment of this invention. It is a front view which shows the exit side of the ingot of the casting mold for continuous casting by embodiment of this invention. It is a front view which shows the deformation | transformation of the exit side of the ingot of the casting mold for continuous casting by embodiment of this invention. It is explanatory drawing which shows the outline of the continuous casting by the conventional vertical continuous casting machine. It is explanatory drawing which shows the concept of the shrinkage | contraction shape of an ingot in the cross section of the casting direction by the conventional continuous casting mold, and an air gap.

Explanation of symbols

1A mold 1B mold 1C mold 1D mold 1E mold 2 casting hollow part 3 short side face 4 long side face 5 center part 6 corner part 7A taper (single straight line)
7B Taper (multiple straight lines)
7C Taper (curve)
θ1 Taper angle θ2 Taper angle 13 Entrance side (metal melt)
14 Casting direction 16 Outlet side (ingot)
DESCRIPTION OF SYMBOLS 20 Molten nozzle 21 Mold 22 Cast hollow part 23 Short side surface 24 Long side surface 25 Secondary cooler 26 Water tank 30 Molten metal 31 Unsolidified part 32 Solidification complete part 33 Ingot 34 Casting direction 35 Inlet side (metal melt)
36 Outlet side (ingot)
37 Air Gearup

Claims (4)

A casting hollow portion is formed with a pair of long side surfaces and a pair of short side surfaces, the inlet side of the molten metal and the outlet side of the ingot are opened, and the sectional area of the inlet side is larger than the sectional area of the outlet side. In continuous casting molds,
The casting hollow part is formed by the cross-sectional area of the inlet side having a taper angle in which a central part of the pair of long side surfaces is larger than a corner part thereof.   2. The continuous casting mold according to claim 1, wherein the cross-sectional area of the entrance side is formed such that the long side surface extending from a central portion along a corner portion thereof is a single straight line.   2. The continuous casting mold according to claim 1, wherein a cross-sectional area of the entrance side is formed by a plurality of straight lines on the long side surface extending from a central portion along a corner portion thereof. 2. The continuous casting mold according to claim 1, wherein the cross-sectional area on the entrance side is formed such that the long side surface extending from the central portion along the corner portion is curved.

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