JPH10286651A - Mold for continuous casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the development of fine shrinkage hole and crack in the center part of a cast billet by shaving grooves extended in the axial direction on the fitting surface of a mold constituted by fitting an inner and an outer cylinders and forming gaps at a part of the fitting surface to reduce the heat conductive area between the inner and the surface cylinders and molten metal extracting heat in a primary cooling. SOLUTION: The mold 11 used to continuously casting copper, etc., is formed by fitting the copper-made outer cylinder 11b by shrinkage-fitting, pressing-in, etc., to the graphite-made inner cylinder 11a of a refractory having bad wettability with the molten metal. Many grooves 12 extended in the axial direction and having a fixed width are arranged on the outer peripheral surface of the inner cylinder 11 of this mold at the same interval to form the gaps at a part of the fitting surface of the inner and the outer cylinders 11a, 11b. Further, the lower end side of the grooves 12 are closed to prevent the invasion of secondary cooling water or steam from the lower part of the mold 11 into the grooves 12. The grooves can be arranged on the inner peripheral surface of the outer cylinder 11b and in some case, the grooves are arranged on both of the inner and the outer cylinders 11a, 11b. Further, it is desirable to form such wedge shape that the width is gradually narrowed from the upper end of the mold 11 toward the lower end side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting mold used for continuously casting a metal lump such as copper, which does not generate voids and cracks.

[0002]

2. Description of the Related Art Recently, when casting a metal lump such as copper, a continuous casting method has been adopted from the viewpoint of good yield of the metal lump. This continuous casting method is a method of casting a long metal lump by using a mold having both ends opened and continuously drawing solidified metal from the lower end while pouring a molten metal from the upper end of the mold. As an apparatus for performing such a continuous casting method, for example, there is an apparatus as shown in FIG.

That is, this apparatus comprises a continuous casting mold 1 comprising an inner cylinder 1a made of a refractory having poor wettability with a molten metal and an outer cylinder 1b made of metal fitted around the outer periphery of the inner cylinder 1a. A jacket 3 for surrounding the mold 1 to form a cooling water passage 2 between itself and the mold 1 is provided on the outside of the mold 1, and a nozzle 4 is formed by the jacket 3 and the lower end of the mold 1. It is. Then, the molten metal M injected into the mold 1 from the pouring nozzle 5 is cooled (primary cooling) by the cooling water flowing in the passage 2 in the mold 1, and its outer peripheral portion is solidified. The whole is solidified by cooling (secondary cooling) by the jetted cooling water, thereby forming a metal lump.

However, according to such a continuous casting method,
If the metal to be cast is copper or
Is a metal that is prone to segregation or eutectic, such as its alloys.
If the diameter of the metal lump to be cast or cast is large,
Fine holes and cracks may occur in the center of the metal block.
there were. That is, the metal to be cast has segregation or eutectic
If the metal is easily formed, as shown in FIG.
Fusion part M₁, And solidification part M _TwoWide semi-solid at the lower end between and
Part M_ThreeWill exist. This semi-solid part M _ThreeRange
Is large, the molten metal M melts according to the shrinkage amount when it solidifies.
Part M₁To semi-solid part M_ThreeInsufficient amount of molten metal to be supplied to
I do. For this reason, with the solidification of the molten metal M, the semi-solidified portion M
_ThreeTensile stress is generated in the
Solid part M_ThreeFine pores and cracks are formed in the steel.

Therefore, conventionally, as a method for preventing the occurrence of such voids and cracks, a method has been employed in which the amount of heat extracted from the molten metal M by the primary cooling is smaller than the amount of heat extracted by the secondary cooling. According to this method, since the amount of heat extracted by the primary cooling is small, only a portion of the molten metal M in the vicinity of the inner cylinder 1a in the mold 1 is solidified, and most of the center side remains in a molten state. And since it is quenched by secondary cooling, the part which kept the molten state on the center side will be solidified almost without passing through the semi-solid state, so that the semi-solid part will be greatly reduced, thereby the semi-solid part Insufficient supply of the molten metal from the molten portion to the air can be prevented, and the occurrence of holes and cracks can be prevented.

Conventionally, as a means for performing such a method, the cooling water systems for the primary cooling and the secondary cooling are individually provided and the amount of water is changed, and the thickness of the inner cylinder 1a and / or the outer cylinder 1b is changed. the thickening of the inner surface of the inner tube 1a and the tapered surface, varying the contact pressure between the solidified portion M ₃ and the inner tube 1a, there are means like.

[0007]

However, each of these means has the following problems. That is, in the case of the means, a new cooling water system must be provided, and not only the equipment cost is increased, but also separate cooling water systems must be adjusted, and workability is poor. Is usually made of graphite and metal with good thermal conductivity as the material of the inner cylinder 1a and the outer cylinder 1b, respectively.
Even if the thickness is increased, the amount of heat extraction cannot be significantly changed, and if the thickness of the inner cylinder 1a and the outer cylinder 1b is increased, the size of the apparatus is increased. In addition to the fact that it is not possible to expect a large change in the heat extraction amount due to the change in the temperature, there is a problem that the surface defect of the metal block or the mold 1 may be damaged.

[0008]

SUMMARY OF THE INVENTION The present inventor has made it possible to greatly reduce the amount of heat extracted from the molten metal by primary cooling, thereby preventing the occurrence of minute holes and cracks in the center of a metal lump. In addition, as a result of conducting research to obtain a continuous casting mold that can solve the problems of the above-described conventional pore generation preventing means at a stroke, the continuous casting mold has an inner cylinder and an outer cylinder. Paying attention, by forming a gap in a part between the inner cylinder and the outer cylinder, to reduce the heat transfer area between the inner cylinder and the outer cylinder, to solve the above problems at once The research results showed that a continuous casting mold capable of producing the same could be obtained.

The present invention has been made based on the above research results. (1) In a continuous casting mold comprising an inner cylinder and an outer cylinder fitted around the outer periphery of the inner cylinder, It has a feature in a continuous casting mold in which a gap is formed in a part between a cylinder and the outer cylinder.

The inner cylinder may be made of any refractory material such as alumina, magnesia, zirconia, calcium oxide, graphite, and the outer cylinder fitted around the inner cylinder may be made of copper, iron, aluminum, and aluminum. It is preferable to use a metal such as an alloy thereof. Therefore, the present invention
(2) In a continuous casting mold including an inner cylinder made of a refractory material and a metal outer cylinder fitted to the outer periphery of the inner cylinder, a gap is formed in a part between the inner cylinder and the outer cylinder. The continuous casting mold has characteristics.

However, the refractory constituting the inner cylinder is most preferably graphite among refractories such as alumina, magnesia, zirconia, calcium oxide, and graphite, and copper, iron, aluminum and the like constituting the outer cylinder. Copper or a copper alloy is most preferable among metals such as an alloy of the above. Therefore, the present invention provides (3) a continuous casting mold comprising an inner cylinder made of graphite and an outer cylinder made of copper or a copper alloy fitted to the outer periphery of the inner cylinder. It has a feature in a continuous casting mold in which a gap is formed in a part between them.

It is preferable that a gap formed in a part between the inner cylinder and the outer cylinder is formed by a groove provided on at least one of an outer periphery of the inner cylinder and an inner periphery of the outer cylinder. Therefore, according to the present invention, (4) the gap formed in a part between the inner cylinder and the outer cylinder in the above (1), (2) or (3) is limited to the outer circumference of the inner cylinder and the inner circumference of the outer cylinder. A continuous casting mold formed by a groove provided in at least one of
It is characterized by the following.

The grooves provided on at least one of the outer circumference of the inner cylinder and the inner circumference of the outer cylinder to form a gap in a part between the inner cylinder and the outer cylinder are provided on the outer circumference of the inner cylinder and the outer cylinder. It is preferable that the grooves are constant width grooves provided at equal intervals in at least one circumferential direction of the inner circumference of the inner cylinder. Further, a gap formed in a part between the inner cylinder and the outer cylinder is Further, it is more preferable to be formed by wedge-shaped grooves provided at equal intervals in at least one of the inner circumferences of the outer cylinder and gradually narrowing in width from the upper end to the lower end. Therefore, according to the present invention, (5) the gap formed in a part between the inner cylinder and the outer cylinder of the above (1), (2) or (3) is limited to the outer circumference of the inner cylinder and the inner circumference of the outer cylinder. And (6) the inner cylinder of (1), (2) or (3), wherein the casting mold is formed by a constant width groove provided at equal intervals in at least one circumferential direction. The gap formed in a part between the inner cylinder and the outer cylinder is gradually increased from the upper end provided at equal intervals in at least one of the outer circumference of the inner cylinder and the inner circumference of the outer cylinder toward the lower end. It is characterized by a continuous casting mold formed by a wedge-shaped groove having a reduced width. The constant width groove and the wedge-shaped groove may have an arbitrary cross-sectional shape such as a triangle, a quadrangle or a semicircle.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the continuous casting mold of the present invention, and FIG. 2 is a side view of the inner cylinder 11a of the continuous casting mold 11 of the present invention shown in FIG. The continuous casting mold 11 of the present invention is made of a graphite inner cylinder 11a, which is a refractory having poor wettability with a molten metal, and a copper-made inner fitting and fixed to the outer periphery of the inner cylinder 11a by shrink fitting or press fitting. And an outer cylinder 11b. On the outer periphery of the inner cylinder 11a, a number of grooves 12 having a constant width extending in the
Are formed at equal intervals in the circumferential direction. That is, by forming the constant width groove 12, a gap is formed in a part between the inner cylinder 1a and the outer cylinder 1b. The lower end of the fixed width groove 12 is closed, thereby preventing secondary cooling water or its vapor from entering the fixed width groove 12 from the lower end of the mold 11.

Thus, such a continuous casting mold 11
When continuous casting is performed by installing the inner cylinder 11a in the ordinary casting apparatus shown in FIG. 10, since the constant width grooves 12 are formed at equal intervals in the circumferential direction on the outer periphery of the inner cylinder 11a, Cylinder 1
1b, the amount of heat extracted from the molten metal by the primary cooling through the mold 11 can be reduced, thereby preventing holes and cracks from being generated in the center of the metal lump. Can be. Moreover, since the mold 11 has no difference in appearance from a conventional mold, it can be used as it is in a conventional casting apparatus. Therefore, it is not necessary to provide new equipment in the casting apparatus, and the apparatus does not become large. Also, since only one cooling water system is required,
Workability can be improved. Further, the inner cylinder 11a
Since the surface pressure between the metal and the solidified portion of the molten metal is not forcibly changed, it is possible to prevent surface defects of the metal lump or damage of the mold 11.

FIG. 3 is a cross-sectional view of another continuous casting mold 11 according to the present invention. The continuous casting mold 11 is fixed to an ordinary graphite inner cylinder 11a and fixed to the inner periphery shown in FIG. The copper outer cylinder 11b formed with the width groove 12 is fitted and fixed by shrink fitting or press fitting.

FIG. 5 is a sectional view of another continuous casting mold 11 according to the present invention. The continuous casting mold 11 includes a graphite inner cylinder 11a of FIG. 2 and a copper outer cylinder 11b of FIG.
Are fixed by shrink fitting or press fitting so that the fixed width groove 12 formed on the outer circumference of the inner cylinder 11a and the fixed width groove 12 formed on the inner circumference of the outer cylinder 11b coincide with each other.

FIG. 6 is a cross-sectional view of another continuous casting mold 11 of the present invention. The continuous casting mold 11 includes a graphite inner cylinder 11a of FIG. 2 and a copper outer cylinder 11b of FIG.
The constant width groove 12 formed on the outer periphery of the inner cylinder 11a and the outer cylinder 11
The fixed-width grooves 12 formed on the inner periphery of b are fitted and fixed by shrink fitting or press-fitting so that they do not coincide.

FIG. 7 shows a continuous casting mold 1 according to the present invention.
The cross-sectional shape of the constant width groove 12 formed on the inner circumference of the outer cylinder 11b is triangular, and FIG. 8 shows the constant width groove 12 formed on the inner circumference of the outer cylinder 11b of the continuous casting mold 11 of the present invention. Has a semicircular cross section.

FIG. 9 is a partially cutaway sectional view of an outer cylinder 11b for producing another continuous casting mold 11 of the present invention. The mold 11 produced using the outer cylinder 11b of FIG. , A wedge-shaped groove 12 whose width gradually decreases from the upper end to the lower end is formed on the inner periphery of the outer cylinder 11b. In this case, not only the effect of the above embodiment is obtained, but also the width of the wedge-shaped groove 12 is changed between the upper end side and the lower end side, so that the heat extraction amount between the upper end side and the lower end side in the primary cooling is also changed. be able to.

In each of the above embodiments, the fixed width groove or the wedge-shaped groove 12 is extended in the axial direction of the inner cylinder 11a, but may be extended in the circumferential direction of the inner cylinder 11a to form an annular shape. Alternatively, the shape may be a spiral shape. Further, in each of the above-described embodiments, the air enters as a mere space in the fixed width groove 12 or the wedge-shaped groove 12, but the inside of the groove 12 is evacuated or a defective conductor of heat is inserted therein. By changing the degree of vacuum or changing the heat transfer rate of the defective conductor, the ratio of heat extraction between primary cooling and secondary cooling can be easily changed.

[0022]

As described above, according to the continuous casting mold of the present invention, since a gap is formed in a part between the inner cylinder and the outer cylinder, the central portion of the metal block is formed. Can prevent the occurrence of fine holes and cracks, and can replace the conventional mold without providing new equipment to the conventional casting apparatus or increasing the size of the casting apparatus. Therefore, the cost can be kept low, and the effects of improving the workability, preventing the surface defect of the metal block and the damage of the mold can be obtained. Also, if the shape and size of the gap are appropriately changed or various defective conductors are appropriately selected and inserted into the gap, not only the ratio of the extracted heat between the primary cooling and the secondary cooling but also the primary cooling can be reduced. , The heat extraction ratio between the upper end side and the lower end side can be easily changed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a continuous casting mold of the present invention.

FIG. 2 is a side view of an inner cylinder constituting the continuous casting mold of FIG.

FIG. 3 is a schematic sectional view of another continuous casting mold of the present invention.

FIG. 4 is a partially cutaway side view of an outer cylinder constituting the continuous casting mold of FIG. 3;

5 is a schematic cross-sectional view of the continuous casting mold of the present invention constituted by the inner cylinder shown in FIG. 2 and the outer cylinder shown in FIG.

FIG. 6 is a schematic cross-sectional view of another continuous casting mold of the present invention constituted by the inner cylinder shown in FIG. 2 and the outer cylinder shown in FIG.

FIG. 7 is a schematic sectional view of a continuous casting mold of the present invention having a triangular groove.

FIG. 8 is a schematic cross-sectional view of the continuous casting mold of the present invention having a semicircular groove.

FIG. 9 is a partially cut-away side view of an outer cylinder having a wedge-shaped groove on the inner periphery which constitutes another continuous casting mold of the present invention.

FIG. 10 is a longitudinal sectional view schematically showing a conventional continuous casting apparatus using a mold.

[Explanation of symbols]

 Reference Signs List 1 mold 1a inner cylinder 1b outer cylinder 3 jacket 3 4 nozzle portion 5 pouring nozzle 11 mold 11a inner cylinder 11b outer cylinder 12 groove

Claims (6)

[Claims] 1. A continuous casting mold comprising an inner cylinder and an outer cylinder fitted on the outer periphery of the inner cylinder, wherein a gap is formed in a part between the inner cylinder and the outer cylinder. And a continuous casting mold. 2. A continuous casting mold comprising an inner cylinder made of a refractory material and a metal outer cylinder fitted on the outer periphery of the inner cylinder, wherein a gap is formed in a part between the inner cylinder and the outer cylinder. A mold for continuous casting, characterized by forming: 3. A continuous casting mold comprising an inner cylinder made of graphite and an outer cylinder made of copper or a copper alloy fitted to the outer periphery of the inner cylinder, wherein a part between the inner cylinder and the outer cylinder is provided. A continuous casting mold characterized by having a gap formed therein. 4. A gap formed in a part between the inner cylinder and the outer cylinder is formed by a groove provided on at least one of an outer periphery of the inner cylinder and an inner periphery of the outer cylinder. The continuous casting mold according to claim 1, 2 or 3, wherein: 5. A gap formed in a part between the inner cylinder and the outer cylinder is provided at equal intervals in at least one circumferential direction of an outer periphery of the inner cylinder and an inner periphery of the outer cylinder. 4. The continuous casting mold according to claim 1, wherein the casting mold is formed by a groove having a constant width. 6. A gap formed in a part between the inner cylinder and the outer cylinder is provided at regular intervals in a circumferential direction of at least one of an outer periphery of the inner cylinder and an inner periphery of the outer cylinder. 4. A continuous casting mold according to claim 1, wherein the casting mold is formed by a wedge-shaped groove whose width gradually decreases from the upper end to the lower end.