JPH01284464A - Mold for cast strip continuous casting - Google Patents

Abstract

PURPOSE:To stabilize the production of a cast strip and to improve the quality of the cast strip by arranging a cavity adjoining to a refractory of a short side mold in the mold for continuous casting providing one pair of long side molds and the short side molds having the refractory. CONSTITUTION:The mold for cast strip continuous casting is constituted of one pair of the long side molds 5 and the short side molds 1. The short side mold 1 is formed with a mold main body 2 having copper-made sliding plates 2a, 2b and the high m.p. refractory 3, and the cavity 4 is arranged between the refractory 1 and the main body 2. At the time of shaping the cast strip 13 while cooling molten metal 12 by shifting of the mold 5, the cavity part 4 having heat insulating action reduces heat conduction from the refractory 3 to outside, to prevent temp. drop of the refractory 3. By this constitution, the development of solidified shell at surface part of the short side mold 1 is surely prevented. Therefore, the production of the cast strip is stabilized and as the shaping of the cast strip 13 is stabilized, the quality of the cast strip 13 is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mold for continuous casting of thin plate slabs by sequentially squeezing the molten metal while cooling it, and particularly relates to a mold for continuous casting of thin plate slabs with excellent quality. The present invention relates to a mold for continuous casting of thin plate slabs suitable for stably obtaining.

[Conventional technology]

Continuous casting machines are devices that continuously form thin plates, and continuous casting machines include twin roll (drum) type and squeeze type twin belt type continuous casting machines, which are more economically superior than conventional slab continuous casting machines. It has been known.

In such a continuous casting machine, the surface area of the molten metal in the pouring section is wide, and becomes narrower as it goes downward, and the plate thickness is determined by the gap at the narrowest part. The molten metal is cooled and shaped as the mutually opposing cooling bodies move or rotate. Depending on the configuration of this cooling body, it is classified as either a twin roll (drum) type or a narrowing type double belt type.

Since the cooling body faces the long side of the slab to be shaped, it is called a long-side mold.A side dam is provided between the ends of this long-side mold to prevent molten metal from spilling.

Since this side dam faces the short side of the slab to be shaped, the short side mold is called a short side mold, and is usually fixedly provided and does not move like a long side mold.

The problem with such molds for continuous casting of thin plate slabs is whether or not the slabs can be successfully pulled out downward. That is, when the molten metal in contact with the short-side mold is cooled by cooling from the short-side mold to a temperature lower than the melting temperature of the molten metal, a solidified shell is formed. In this case, since the short side mold in the molten metal holding area is narrowed downward, the solidified shell formed above the molten metal holding area passes through the narrower short side mold part below. As a result, the already formed slab is restrained in the molten metal holding area,
The problem is that this molten metal holding area is expanded, causing a phenomenon where the molten metal spills, that is, a breakout, or the slab is restrained in the molten metal holding area, making it impossible to stably obtain high quality slabs. There is.

In this way, when the molten metal in contact with the short-side mold is cooled, the slab cannot be pulled out downward, so the short-side mold is constructed of a mold with a small cooling effect. Refractories are considered to be the most suitable material.

In addition, when the short side mold is made of refractory material, since the refractory is relatively soft, it wears out due to sliding between the short side mold and the long side mold.
Scratches are likely to occur. This not only leads to accidents such as molten steel leakage, but also shortens the life of the short-side mold. Therefore, in order to prevent this, as described in Japanese Patent Publication No. 61-9903, sliding pads made of copper, ceramics, etc. are installed on both sides of the short-side mold where the short-side mold and long-side mold contact each other. Providing a plate is used as a preferred method.

In this configuration, for example, when copper is used on both edges of the short side mold, a solidified shell is formed in the copper part, so the solidified shells on both sides meet at the narrowest part at the bottom of the molten metal holding area. In order to prevent the molten metal holding area from expanding, the total width of the sliding plates on both sides should be equal to or greater than the gap at the narrowest part of the molten metal holding area (desired final plate thickness width). It is important to keep it small.

In addition, in order to actively prevent the cooling of the molten metal that comes into contact with the short-side mold, a heating element is attached to the refractory surface of the short-side mold that comes in contact with the molten metal, as described in JP-A No. 62-64458.
It has been proposed to inject molten metal while heating it with the heating element.

[Problem to be solved by the invention]

In a mold for continuous casting of thin plate slabs that uses a refractory material with high heat resistance and low thermal conductivity as the short-side mold material, the refractory is in contact with the long-side mold, which is a cooling body. Further, in this case, the long-side mold and the short-side mold are configured to be brought into close contact with each other as much as possible for the purpose of preventing leakage of molten metal. For this reason,
The refractory absorbs heat from the long-side mold, which is a cooling body, and the temperature of the refractory becomes lower than the molten metal. A solidified shell is also formed in the refractory part above the narrowest part of the mold, and the solidified shell is connected to the long-side mold. Either it merges with the solidified shell forming on the synchronously moving long-sided mold, resulting in breakout, or the slab is restrained in the molten metal holding area, resulting in poor casting quality. The problem of not being able to stably obtain pieces still occurred.

In addition, in a configuration in which sliding plates made of copper, ceramics, etc. are provided on both edges of the short side mold where the short side mold and long side mold contact, a large amount of heat is taken away from the sliding plate. A solidified shell is also formed on the short side mold portion inside the sliding plate, and this solidified shell is integrated with the solidified shell formed on the long side mold via the solidified shell formed on the sliding plate. Therefore, there still arises the problem that a breakout occurs or the slab is restrained in the molten metal holding area, making it impossible to stably obtain a slab of excellent quality.

In this way, in the above-mentioned conventional technologies, no consideration is given to preventing the formation of a solidified shell in the short side mold portion, and a solidified shell is formed above the narrowest part of the short side mold, and the long side The molten metal holding area formed by the mold and the short-side mold is pushed out and the molten metal spills out, causing a breakout, or the slab is restrained by the molten metal holding area, resulting in high quality slabs. There was a problem that it became impossible to stably obtain .

On the other hand, in JP-A-62-64, a heating element is provided on the surface of the mold on the short side.
In the proposal of No. 458, not only is the structure complicated, but it is almost impossible to heat the short side mold surface to an extent that can prevent the formation of a solidified shell using existing heating elements, and the temperature of the molten metal is low. Since the temperature reaches as high as 1500° C., the heating element would be damaged at this high temperature, making it extremely difficult to implement this proposal.

An object of the present invention is to provide a mold for continuous casting of thin plate slabs that can prevent the formation of solidified shells in the short side mold portions with a simple short side mold structure and stably obtain slabs of excellent quality. It is.

[Means to solve the problem]

The above purpose is to provide a pair of long-side molds that move or rotate in synchronization with the slab to be formed and that are disposed opposite to each other, and a mold that is disposed between both ends of the pair of long-side molds, and that is placed between the ends of the pair of long-side molds that move or rotate in synchronization with the slab to be shaped. In a mold for continuous casting of thin plate slabs, which includes a short-side mold having at least a refractory in contacting portions, this is achieved by providing a cavity adjacent to the refractory in the short-side mold.

[Effect]

The cavity provided in the short-side mold has a heat insulating effect, reduces the flow of heat from the refractory to the outside, and prevents the temperature of the refractory from decreasing. As a result, the formation of a solidified shell on the short side mold surface is prevented.

By providing a cavity in the short-side mold in this way, it is possible to prevent the formation of a solidified shell on the surface of the short-side mold, thereby making it possible to stably obtain slabs of excellent quality.

〔Example〕

Next, one embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows, in cross section, a short side mold 1 constituting the main part of a mold for continuous casting of thin plate slabs according to an embodiment of the present invention.

The short-side mold 1 has a copper mold body 2 which has copper sliding plates 2a and 2b with a water-cooled jacket structure and a thickness of 7 cm, which are provided on both side edges of the mold in the part that comes into contact with the long-side mold. It is made up of a high melting point refractory 3. In this embodiment, a new material is used for the refractory 3. Note that even if a commercially available product such as a fused cylinder is used for boat fishing, the effects of the present invention will not be affected. A cavity 4 is provided in the short side mold 1 between the high melting point refractory 3 and the saw-shaped main body 2. This cavity 4 is the most essential part of the present invention.

FIG. 3 shows the overall configuration of a twin-belt continuous casting machine in which the short-side mold 1 is used to construct a mold for continuous casting of thin plate slabs. Twin-belt continuous casting machine has two belts (long side mold)
A pair of belts 5 and 5 are provided facing each other, and the short-side mold (side dam) 1 is placed between both ends thereof, and the belt S and the short-side mold 1 constitute a mold for continuous casting of thin plate slabs. Ru.

The belt 5 is guided by rollers 6,7,8.

It is floated and supported by a pad 9 of a hydrostatic pressure bearing type, and rotated in the casting direction (downward). Tension is applied to the belt 5 by pulling the roller 7 from the cylinder 10 via the bracket 11. In this way, by the movement of the belt 5, the molten metal 12 in the mold is cooled and continuously shaped into a slab 13. In the figure, 14 is the molten metal holding area of the mold, and 15 is the narrowest part at the bottom of the area 14.

When shaping such a slab 13, in the continuous casting mold of this embodiment, a cavity 4 is provided in the short side mold 1 adjacent to the high melting point refractory 3, and this cavity 4 has a heat insulating effect. This reduces the outflow of heat from the high melting point refractory 3 to the outside and prevents the temperature of the refractory 3 from decreasing. As a result, it is possible to reliably prevent the formation of a solidified shell on the surface of the short-side mold 8. As described above, according to this embodiment, by providing the cavity 4 in the short-side mold 1, the surface of the short-side mold 1 is It is possible to prevent the formation of a solidified shell on top, and as a result, it is possible to stably obtain a slab 13 of excellent quality.

As an example, in FIG. 2, the upper width of the molten metal holding area 14 is 200 m, and the narrowest part 15 of the lower molten metal holding area is 301 m.
When a 111,800 steel sheet was drawn continuously at a speed of 12 m/win, it was possible to continuously produce a beautiful steel sheet with smooth short and long side surfaces for a long period of time. In this experiment.

The composition of the steel material is C10.04%, Mn10.30
%.

Plo, 023%, S10.016%, A Q 10.
042% was used.

Here, the shape of the molten metal holding areas 14 on both side edges of the short side mold 1 shown in FIG. 1 is an arc shape.

It does not necessarily have to be an arcuate shape, and the effects of the present invention are not affected even if the shape is a straight line or a quadratic curve.

Further, in the above embodiment, a belt-type continuous casting machine is described in which the long-side mold 5 is a belt, but the long-side mold is not limited to a belt type; for example, the effects of the present invention can be obtained even if the long-side mold is of a type such as a caterpillar. It is demonstrated in Further, although the molten metal holding area 14 of the present invention has a rectangular shape when viewed from above, the essential effects of the present invention will not be affected by any shape other than the rectangle.

Furthermore, the mold of the present invention is not only applicable to the downward drawing continuous casting machine described in this embodiment, but also to horizontal continuous casting machines and various angle continuous casting machines located between the downward drawing method and the horizontal continuous casting machine. It is also applicable to casting machines.

Furthermore, in this embodiment, the high melting point refractory 3 was used for the short side mold 1, but a high melting point refractory for heat retention is overlaid or bonded by thermal spraying etc. on the relevant part, and the protruding parts are made of the same material or a different material. A large heat-retaining material with a high melting point formed by overlaying or bonding by thermal spraying or the like may also be used.

Further, although one embodiment of the present invention has been described based on a twin-belt continuous casting machine, the same method can be applied to a twin-roll (drum) large continuous casting machine.

It has been confirmed that similar effects occur.

〔Effect of the invention〕

As is clear from the above, according to the present invention, the formation of a solidified shell on the short side mold can be prevented with a simple structure of just providing a cavity, and a slab of excellent quality can be stably obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a short-side mold constituting the main part of a mold for continuous casting of thin plate slabs according to an embodiment of the present invention, and FIG. FIG. 2 is a conceptual diagram of a twin-belt continuous casting machine with a mold configuration. 1...Short side mold, 2a, 2b...Sliding plate, 3...
Refractory, 4...Cavity, 5...Long side mold. 1. Figure 1 Ka2. figure

Claims (1)

[Scope of Claims] 1. A pair of long-side molds that are provided opposite each other and move or rotate in synchronization with the slab to be formed, and a pair of long-side molds disposed between both ends of the pair of long-side molds. and a mold for continuous casting of thin plate slabs, which is equipped with a short-side mold in which at least a refractory is provided in the portion that contacts the molten metal, wherein a cavity is provided in the short-side mold adjacent to the refractory. Features a mold for continuous casting of thin plate slabs. 2. A sliding plate made of copper, ceramics, etc. is provided on both side edges of the short side mold where the short side mold and the long side mold contact each other, and the cavity is placed between the sliding plate and the refractory. A mold for continuous casting of thin plate slabs according to claim 1, characterized in that: