JPS6012260A - Continuous casting device for thin plate - Google Patents

Abstract

PURPOSE:To provide a titled device which prevents the deterioration in the characteristic of the edge parts and surface of a thin slab by the constitution in which an inert gas is supplied through gas permeable refractories embedded in a side dam to seal the space between the side dam and a continuous rotary casting mold. CONSTITUTION:A continuous casting device for a thin plate casts a thin slab 2 by supplying a molten metal from a tundish 4 via a side dam 3 installed above a continuous rotary casting mold of which the surface in the transverse direction of the plate is formed of a pair of casting rolls 1a, 1b rotating in the directions opposite from each other into said casting mold. Gas permeable refractories 10 are embedded in said side dam 3 and with said refractories as a a gas passage, an inert gas is passed therethrough from an inert gas source 11 to seal the space delta between the dam 3 and the rolls 1a, 1b with the inert gas. The penetration of the molten metal into the space delta is prevented and the slab 2 having uniform edge parts and a good surface characteristic is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention casts a thin plate directly from molten metal using a continuously rotating mold in which the mold surface in the width direction of the plate is formed by the surfaces of a pair of casting rolls or casting belts that rotate in opposite directions. This invention relates to improvement of continuous thin plate casting equipment.

In continuous casting of molten steel, proposals have been made to directly cast thin plates instead of conventional thick slabs.

For example, JP-A-55-75862 discloses a method of directly rolling a thin plate from molten steel using large diameter rolls.

There are two problems inherent in this case, and as mentioned in this publication, one of the problems is the control of the edges of the thin sheet to be cast, and the other is the surface of the thin sheet to be cast. Another major problem is that it is difficult to maintain good properties. This is because, in order to rotate the mold without frictional resistance, it is absolutely necessary to provide a gap between the three-rotation mold and the sump (non-rotating part) that supplies molten metal to the mold. Not only does hot water intrusion occur in this area, making both edges of the cast thin plate (slab) uneven, but this intrusion also occurs on the surface of the rotary mold that is about to face the casting surface. This is because there is a risk that the surface of the mold may be roughened, and the quality of the surface of the slab may deteriorate due to the solidified matter.

In order to deal with this, Japanese Patent Laid-Open No. 58-32548 proposes supplying powder additives on the surface of the rotary mold, such as those used in conventional continuous casting slabs of molten steel. ing. The supply of this powder additive will provide good lubrication between the sheet slab and the mold surface, but will not compensate for the uniform distribution of this solid powder by gravity over the entire area of the gap. It seems that there is no complete protection against hot water being inserted.

The present invention was made with the aim of solving such problems, and includes a continuous rotating mold in which a mold surface in the sheet width direction is formed by the surfaces of a pair of casting rolls or casting belts that rotate in opposite directions, and In a thin plate continuous casting machine consisting of a No. id dam installed above the mold and a tande sosh for supplying molten metal to this side dam, a gas-permeable refractory is embedded inside the side dam.

The object of the present invention is to provide a thin plate continuous casting apparatus characterized in that this gas-permeable refractory is used as a gas supply means for sealing the gap between the continuous rotary mold and the side dam with an inert gas. The details of the thin plate continuous casting apparatus of the present invention will be explained below with reference to the drawings.

FIG. 1 shows a thin plate continuous casting apparatus using a continuous rotating mold in which the mold surface in the sheet width direction is formed by the surfaces of a pair of casting rolls la and lb that rotate in opposite directions. A pair of rolls la and lb form the mold surface,
They are placed horizontally with their rotation axes parallel to each other with a gap between them.
Although not shown in the drawings, each of the rolls la and lb is provided with cooling equipment therein for continuously cooling the roll surface. The gap between the rolls la and lb serves as a mold, and the thin plate slab 2 is continuously manufactured by continuously supplying molten metal to the gap between the rolls la and Ib, which rotate synchronously in opposite directions.

A No. 1 id dam 3 is installed on top of this rotating roll mold, and a kundesh 4 for supplying molten metal to the side dam 3 is installed further above this side dam 3.

The continuous thin plate casting apparatus of the present invention is characterized by the structure of this side dam 3. This side dam 3 is made of refractory material,
As shown in Figure 2, the &N type roll l
side walls 5a, 5b along the direction of the rotation axis of a, lb;
It has side walls 6a, 6b along a direction perpendicular to the rotation axis of the mold rolls la, lb.

The lower side walls 5a, 5'b are connected to a bottom surface having curved surfaces 7a, 7b shaped along the circumferential surfaces of the mold rolls la, lb. That is, the curved surfaces 7a and 7b having a gap δ (FIG. 1) with the surface of the mold form the bottom surface of the side dam 3 facing the mold surface.

On the other hand, the side walls 6a, 6b gradually taper on both sides along the curved surfaces 7a, 7b.
5b, and these side walls 5a, 5
The inner distance between the protruding portions 8a and 8b extending below b corresponds to the width of the plate to be cast.

In the present invention, a gas permeable refractory 10 is embedded inside this side dam, and this gas permeable refractory 10
is a gas supply means for supplying inert gas to the gap between the continuous rotating mold and the side dam.

More specifically, on the bottom surface (curved surfaces 7a, 7b) of the side dam 3 facing the mold surface, the gas permeable refractory material 10 is formed so that the gas passage end 9 of the gas permeable refractory material 10 is exposed in the form of a slit. A material 10 is embedded in the wall of the side dam and used as a gas passage. The gas passage 10 of the gas-permeable refractory in this wall is then connected to an inert gas supply source 11.

As shown in FIG. 2, this slit-shaped gas passage end 9 has a gas passage end 9A in the direction along the side walls 5a, 5b and a -9-id wall 6a, 61J on the curved bottom surfaces 7a, 7b.
and a gas passage end 9B in the direction along the direction. Both gas passage ends 98 and 9B may be configured to be continuous as shown in the figure, but they may also be provided independently. Although it is not visible in Figure 3, a gas passage end is provided in the form of a slit in the direction along the side walls 6a, 6b on the bottom surfaces of the lowest ends of the side walls 6a, 6b (the bottoms of the protruding parts 8a and 8b). good. side dam 3
The gas passages 10 of the gas-permeable refractory provided inside are arranged so that gas can be uniformly blown out from each slit-shaped gas passage end 9, and the gas passages 10 are arranged so that gas can be uniformly blown out from each slit-shaped gas passage end 9. As shown in Figure 2, a gas header 12 is placed around the side dam 3, and branch pipes are taken from the gas header 12 as appropriate and connected to the gas passages 10 of the gas-permeable refractory inside the side dam 3. good. Thereby, when inert gas is supplied to the gas header 12, the inert gas is blown out in a slit shape from the gas passage end 9 on the bottom surface of the side dam 3 facing the mold.

When the inert gas is blown out evenly from the gas passage end 9 in this way, the inert gas blown out from the direction of the gas passage end 9A is directed to the surfaces of the rotating rolls Ia and lb that are about to head toward the casting surface. The inert gas is blown out from the gas passage end 9B and the gas passage ends (not shown) provided at the bottoms of the protruding parts 8a and 8b. prevents hot water from entering in the width direction of the slab. That is, the gap formed between the pair of rotary mold rolls la, lb and the side dam 3 is surrounded by an inert gas seal, effectively preventing molten metal from entering this gap. Become. To give an example of specifications for obtaining this effect, when the gap δ formed between the mold rolls la, lb and the side dam 3 is 0.3 to 0.5 mm, the gas pressure is set to 2 to 7 mm. kg/ca Q, gas amount 0.5-5 Nrl/min, T + gas temperature 20
It is preferable to set it in the range of 0 to 40°C.

The example in Fig. 3 is a two-rotation mold, with rolls la in Fig. 1,
This figure shows an apparatus similar to the thin plate continuous casting apparatus of FIG. 1, except that a pair of casting bells (15a, 15b) rotating in opposite directions are used in place of the casting bell. In this case as well, by installing an inert gas supply equipment similar to that explained in Figs. 1 and 2 to the side dam 3 installed on the two-rotation mold, it is possible to prevent hot water from pouring in as described above. .

Note that the supply of this inert gas accelerates cooling around the side dam, and in the case of casting conditions where solidified shells are generated on areas other than the mold surface, making smooth casting difficult, this defect may be avoided. It is preferable to preheat the active gas before supplying it. Although this inert gas can be heated by exchanging heat with an external heat source, it is actually more convenient to use the waste heat that is removed from the molten steel by cooling rolls la and lb. .

As described above, the present invention solves the problems of deterioration of the properties of the thin plate edges and surface quality, especially when directly manufacturing molten steel into thin plates using a continuous casting apparatus using a synchronous rotating mold. This contributes to the successful implementation of direct continuous casting of thin sheets.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an example of the thin plate continuous casting apparatus of the present invention, FIG. 2 is a general perspective view of the side dam of the present invention, and FIG. 3 is a schematic sectional view showing another example of the thin plate continuous casting apparatus of the present invention. FIG. ■...Rotary mold roll, 2...Thin slab. 3. Sidedam, 4. Tandesos. 5. The side wall of the side dam, 6. The side wall of the same dam. 7. Curved surface (bottom of side dam). 9... Gas passage end 10... Gas passage of gas permeable refractory material, 11... Inert gas source. 12...Gas header. Applicant Nisshin Steel Co., Ltd.

Claims (1)

[Claims] A continuous rotating mold that forms a mold surface in the plate width direction by the surfaces of a pair of casting rolls or casting belts that rotate in opposite directions, a side dam installed on top of this continuous rotating mold, and molten metal being supplied to the side dam. In a thin plate continuous casting device consisting of a tumble pusher for molding, a gas-permeable refractory is embedded inside the side dam, and the gas-permeable refractory is used to inert the gap between the continuous rotary mold and the side dam. A thin plate continuous casting apparatus characterized by using a gas supply means for gas sealing.