JPH055572B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mold for continuous casting of steel or the like.

[Conventional technology]

Conventional continuous casting molds include molds cast in a cylindrical shape and molds assembled from plate materials into a cylindrical shape.
In both cases, the walls are made of copper, and a clad metal of copper and stainless steel is used in the assembly mold, but internal stress is generated due to the temperature difference between the inner surface in contact with the molten metal and the outer surface that is water-cooled. This causes thermal deformation in the mold and causes cracks.

This thermal deformation phenomenon will be explained in detail with reference to FIG. 2, which shows an example of a conventional continuous casting mold. The wall 1 of the continuous casting mold is made of integrally cast metal such as copper, and a water cooling jacket 4 for flowing cooling water in the direction of the arrow is disposed on the outside thereof. In continuous casting, molten metal is supplied from the upper end of the mold, and gradually solidifies (in the area shown by the dots) as it descends through the mold, as schematically shown on the left from the center line in Figure 2a. To go. Therefore, the inner surface of the wall 1 in contact with the molten metal is heated to approximately 200 to 400°C, and the higher the temperature, the higher the temperature. On the other hand, the outer surface of the wall 1, which is cooled by cooling water, is approximately 50°C. Because of this temperature difference, as shown to the right of the center line in Figure 2a,
The wall 1 is thermally deformed as shown by the dotted line, and the amount of deformation is larger toward the upper end. As the number of castings increases, thermal deformation increases and creep accumulates, resulting in uneven cooling due to mold deformation, which causes surface cracks or internal cracks in the mold, and causes quality defects in cast products. was.

Although the above thermal deformation can be prevented to some extent by increasing the wall thickness of the mold, it not only makes the mold expensive but also increases the electromagnetic shielding effect, making electromagnetic stirring impossible.

[Problem that the invention seeks to solve]

The present invention aims to provide a continuous casting mold that can produce cast pieces of excellent quality by minimizing the deformation of the walls of the mold due to temperature differences, and that can also be used for a long period of time. purpose.

[Means for solving problems]

The continuous casting mold of the present invention has a double structure, the outer wall is made of integrally molded metal, the inner wall is made up of a plurality of metal pieces joined to the outer wall, and the gap between each metal piece is 0.1 to 0.4. mm.

The metal constituting the outer wall and inner wall is a metal or alloy such as copper that has traditionally been used in continuous casting molds, and the outer wall and inner wall may be made of the same metal, or as long as they can be joined to each other. Different metals may also be used.

The size of the metal pieces constituting the inner wall is not particularly limited, and it is common to have three or more metal pieces in the casting direction and two or more metal pieces in the transverse direction depending on the size of the mold. If the gap between each metal piece is less than 0.1mm, deformation due to thermal expansion cannot be absorbed.
If it exceeds 0.4 mm, it will have a negative effect on casting.

The ratio of the thickness of the metal piece constituting the outer wall to the thickness of the metal piece constituting the inner wall can be appropriately selected within a range that provides the effects of the present invention, but is preferably in the range of 0.4 to 3.0. If this ratio is less than 0.4, the strength of the mold will be insufficient, and if it exceeds 3.0, the influence of thermal deformation of the outer wall will increase and the intended effect will not be obtained. The thickness of the metal piece is preferably 3 mm to 10 mm; if it is less than 3 mm, thermal expansion cannot be fully absorbed and the intended effect cannot be obtained;
Exceeding this will weaken the electromagnetic force for electromagnetic stirring. In addition, the thickness of the outer wall metal depends on the thickness of the metal pieces that make up the inner wall, but is generally preferably 4 to 10 mm.If it is less than 4 mm, the strength of the mold will be insufficient, and if it exceeds 10 mm, the electromagnetic force for electromagnetic stirring will be reduced. It weakens.

Soldering, silver brazing, heat pressure bonding, etc. can be used to join metal pieces to the exterior wall.
Bonding can also be done with a heat-resistant organic adhesive.
Particularly, it is preferable to bond with an epoxy resin adhesive because it is advantageous in that electromagnetic force easily penetrates through the interposition of an electrically insulating layer, which is advantageous for electromagnetic stirring.

[Effect]

In the double structure mold wall of the present invention, the metal pieces that make up the inner wall are mutually joined to the outer wall with a gap of 0.1 to 0.4 mm, and the metal pieces on the inner wall expand thermally due to the temperature difference between the outer wall and the inner wall. Even if it is, it will be absorbed by the metal gap.

〔Example〕

FIG. 1 shows a specific example of a cylindrical mold for continuous casting according to the present invention. In addition, the water cooling jacket is omitted in FIG.

The mold wall has a double structure consisting of an outer wall 1a and an inner wall 1b, and the outer wall 1a is made of copper with a thickness of 6 mm and is integrally molded. The inner wall 1b is composed of a large number of metal pieces 2 made of copper with a wall thickness of 5 mm, and each metal piece 2 is attached to the outer wall with a heat-resistant epoxy resin adhesive Bond (trademark) while keeping a gap 3 of about 0.2 mm between each metal piece 2. It is adhesively fixed to 1a.

In this specific example, all the metal pieces have the same size except for the curved portions, but the upper part of the mold, which has a large thermal expansion, may be made of a small metal piece, and the lower part may be made of a large metal piece.

〔Effect of the invention〕

According to the present invention, since the inner wall in contact with the high-temperature molten metal is composed of a plurality of metal pieces, thermal expansion is absorbed by the gap between the metal pieces, and thermal deformation of the mold is extremely small. Therefore, since a uniform cooling effect can be obtained, defects such as surface cracks and internal cracks in the cast product can be prevented. Furthermore, since thermal deformation of the mold is extremely small, there is little creep accumulation, and the durability of the mold is improved, such as the cooling characteristics not deteriorating even after repeated use over a long period of time.

Furthermore, when a metal piece is bonded to the outer wall with a heat-resistant organic adhesive, the mold wall becomes electrically thinner due to the presence of the electrically insulating organic adhesive layer, making it easier for electromagnetic force to penetrate inside the mold. The efficiency of electromagnetic stirring of molten metal becomes extremely high.

[Brief explanation of the drawing]

FIG. 1a is a partial vertical cross-sectional view showing an example of the continuous casting mold of the present invention, and FIG. 1b is a partial cross-sectional view of the same example. FIG. 2a is a longitudinal cross-sectional view of a conventional continuous casting mold, in which the solidification state of the molten metal is illustrated on the left side of the center line, and the thermal deformation state of the mold wall is illustrated on the right side of the center line. 2nd b
The figure is a cross-sectional view taken along the line X--X of Figure 2a, showing only the mold wall. 1...Mold wall, 1a...Outer wall, 1b...Inner wall,
2...Metal piece, 3...Gap, 4...Water cooling jacket.

Claims (1)

[Claims] 1. The mold wall has a double structure, the outer wall is made of integrally molded metal, and the inner wall is made of a plurality of metal pieces joined to the outer wall, and the gap between each metal piece is 0.1 to 0.4. Continuous casting mold which is mm. 2. The continuous casting mold according to claim 1, wherein the ratio of the thickness of the outer wall metal to the inner wall metal piece is 0.4 to 3.0. 3. The continuous casting mold according to claim 2, wherein the inner wall metal piece has a wall thickness of 3 to 10 mm. 4. The continuous casting mold according to any one of claims 1, 2, and 3, wherein the inner wall metal piece is bonded to the outer wall with an electrically insulating and heat-resistant epoxy resin adhesive.