JPS6012259A - 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 blown from gas blow ports at the base of a side dam to prevent penetration of a molten metal into the space between the side dam and continuous rotary casting mold. CONSTITUTION:A continuous casting device for a thin plate which 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. An inert gas supplied from an inert gas source 11 is blown through slit-shaped gas blow ports provided to the base of the side dam 3 of such device facing the mold through gas passages 10 communicating with said parts. The penetration of the molten metal into the space delta between the base of the side dam 3 and the rolls 1a, 1b is thus prevented and the ununiformity at the edges of the slab 2 and the deterioration in the characteristic of the slab surface are prevented.

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.

In this case, there are nine different problems, but as mentioned in this publication, one of the problems is controlling the edges of the thin plate to be cast, and the surface of the thin plate to be cast is one of the problems. Another major problem is that it is difficult to maintain good properties. This is because there is a gap between the 9-rotating mold and the sump (non-rotating part) that supplies molten metal to the mold.
In order to rotate the mold without frictional resistance, it is absolutely necessary to provide a gap, but hot water will be inserted in this area, and the edges of the cast thin plate (slab) will become uneven. However, this insertion may also occur on the surface of the rotary mold that is about to face the casting surface, which may cause the mold surface to become rough or the solidified material to deteriorate the surface properties of the slab. Because it will be.

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 healds that rotate in opposite directions, and In a thin plate continuous casting apparatus consisting of a side dam installed above a mold and a tandem for supplying molten metal to the side dam, a slit-shaped gas outlet is provided at the bottom of the side dam facing the mold, and the gas The present invention provides a thin plate continuous casting apparatus characterized in that a gas passage leading to an outlet is provided inside a side dam, and this gas passage is connected to an inert gas supply source.

The details of the three continuous thin plate casting apparatuses 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 that form the mold surface are placed horizontally with their rotating axes parallel to each other with a gap between them, and each roll la and lb is equipped with two cooling equipment (not shown) that continuously cools the roll surface. It is installed inside it. The gap between the rolls 1a+ib serves as a mold, and the thin slab 2 is continuously manufactured by continuously supplying molten metal to the gap between the rolls la and lb, which rotate in opposite directions synchronously.

A side dam 3 is installed on the rotating roll mold, and a tandem 4 for supplying molten metal to the side dam 3 is installed above the side dam 3.

The continuous thin plate casting apparatus of the present invention is characterized by the structure of this side dam 3. This issue Ido Dam 3 is made of refractory material,
As shown in the overall diagram in Fig. 2, mold rolls la,
It has side walls 5a, 5b along the direction of the rotation axis of Ib, and side walls 6a, 6b along the direction perpendicular to the rotation axis of the mold rolls la, 11].

The lower side walls 5a, 5b are connected to a bottom surface having curved surfaces 7a, 7b shaped along the circumferential surfaces of the mold rolls la, lb. In other words, the surface of the mold and the gap δ (first
The curved surfaces 7a, 7b with curved surfaces 7a, 7b 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 slit-shaped gas outlet 9 is provided on the bottom surface (curved surface ?a, 7b) of the side dam 3 facing the mold surface, and a gas passage leading to the slit-shaped gas outlet 9 is provided. 10 (FIG. 1) is installed inside this side dam 3, and this gas passage 10 is connected to an inert gas supply source 11.

This slit-shaped gas outlet 9 has a curved bottom surface as shown in FIG. In a, 7b.

It consists of a slit 9A extending along the side walls 5'a and 5b, and a slit 9B extending along the side walls 6a and 6b. The slits 9^ and 9B may be arranged continuously as shown in the figure, but they may also be provided independently. Also.

Although not visible in the figure, it is advisable to provide a slit-shaped gas outlet in the direction along the side walls 6a, 6b at the bottom of the lowest end of the side walls 6a, 6b (bottoms of the protruding parts 8a and 8b). . The gas passages 1o provided in the side dam 3 are arranged so that gas is uniformly blown out from each gas outlet 9, and the gas passages 1o are arranged so that gas is uniformly blown out from each gas outlet 9. As shown in FIG. It is preferable that the header 12 is placed around the side dam 3, and a branch pipe is appropriately taken from the gas header 12 and connected to the gas passage IO in the side dam 3.

Thereby, when inert gas is supplied to the gas header 12, the inert gas is blown out in a slit shape from the gas outlet 9 on the bottom face of the side dam 3 facing the mold.

In this way, when the inert gas is blown out evenly from the gas outlet 9, the inert gas blown out from the direction of the slit 9 is blown onto the surfaces of the rotating rolls la and lb that are about to head toward the casting surface. On the other hand, the inert gas blown out from the slits (not shown) provided at the bottoms of Surin 9B and the protruding parts 8a and 8b spreads over the slab width. Prevent hot water from entering in the direction. That is, the gap formed between the pair of rotary mold rolls la, ib and the side dam 3 is surrounded by an inert gas seal, and the insertion of molten metal into this gap is effectively prevented. 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 5 mm. kg/cJ G, gas amount 0.5-5
It is preferable to set it in the range of N nl /min, T.

The example in Fig. 3 is a two-rotation mold, with rolls la in Fig. 1,
This shows an apparatus similar to the thin plate continuous casting apparatus of FIG. 1, except that a pair of casting bells 58, 15b rotating in opposite directions are used instead of lbO. In this case as well, for the side dam 3 installed on the two-rotation mold,
By installing an inert gas supply facility similar to that explained in FIGS. 1 and 2, it is possible to prevent hot water from being poured in as described above.

If the casting conditions are such that the introduction of this inert gas cools the area around the side dam, making it impossible to perform smooth casting, it is preferable to heat this inert gas in advance before introducing it. As this inert gas heating source, it is preferable to utilize heat removed from the molten steel by cooling rolls la and lb.

As explained above, the present invention solves the problems of deterioration of the properties of the thin plate edges and surface properties especially when directly manufacturing molten steel into thin plates using a continuous casting apparatus using a synchronous rotating mold.
This can be avoided by effectively forming an inert gas seal, and contributes to the successful implementation of direct continuous casting of thin sheets.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a schematic sectional view showing an example of the continuous thin plate casting apparatus of the present invention, Fig. 2 is an overall perspective view of the side dam of the present invention, and Fig. 3 is a continuous thin plate casting apparatus of the present invention. It is a schematic sectional view showing other examples. 1. Rotary mold roll, 2. Thin plate slab. 3. Sidedam, 4. Tandesos. 5. Side wall of the side dam, 6. Side wall of the same. 7. Curved surface (bottom of side dam). 9. Slit-shaped gas outlet. 10. Gas passage inside the side dam. 11... Inert gas source, 12... Gas header. Figure 1

Claims (1)

[Claims] 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, a side dam installed on the continuous rotating mold, and a side dam installed on the continuous rotating mold. In a thin plate continuous casting apparatus comprising a tandem for supplying molten metal to a side dam, a slit-shaped gas outlet is provided on the bottom face of the side dam facing the mold. A thin plate continuous casting apparatus characterized in that a gas passage leading to the gas outlet is installed inside a side dam, and this gas passage is connected to an inert gas supply source.