JPH01162545A - Short side plate for strip continuous casting machine - Google Patents

Abstract

PURPOSE:To restrain wear of heat resistant refractory and to enable stable casting by inserting the wear resistant refractory having high hardness at high temp. more than that of a cast strip between frame edge parts formed at both side edges contacting with a circular body and heat insulating refractory supported interval of both frame edge parts. CONSTITUTION:The surface of the frame edge part 9 is sufficiently cooled with cooling water flowing in coolant passage 11 and molten steel is cooled in there, to develop the solidified shell. The heat resistant refractory 10 held in the frame edge part 9 is brought the surface into contact with the molten steel, but as it has low thermal conductivity, the solidification of the molten steel is not developed on the heat insulating refractory 10. The solidified shell developed at the frame edge part 9 grows and a part thereof expects to extend to the face of heat resistant refractory 10, but growth of the solidified shell is stopped on the surface of the wear resistant refractory 12 having high hardless at high temp. arranged at the boundary of the frame edge part 9 and heat resistant refractory 10. As the solidified shell is not directly brought into contact with the heat resistant refractory 10, the heat resistant refractory 10 is scarcely worn with the solidified shell.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a short side plate that forms a casting space together with a pair of circulating bodies in a continuous thin slab casting machine that directly produces thin slabs from molten metal.

(Prior art) A continuous casting machine (which continuously manufactures thin slabs such as sheet bars directly from molten metal (explained below using the example of "molten steel"))
Recently, various types of belt casters have been proposed. Figure 3 shows a typical example. The illustrated synchronous belt caster is of the narrowing type and is cast through a plurality of guide rolls 3a, 3b, 3c, respectively, while maintaining a gap for holding the cast material such as molten steel or solidified shell over a predetermined distance. metal belts 1 and 2 that support a pair of long side surfaces that are arranged opposite to each other and move axially; The upper and lower sides are concave-shaped short side plates 4.5 to confine the casting space on four sides.

When molten steel is supplied into the casting space from the immersion nozzle 6, the metal belt 1 is cooled by the cooling pads 7a and 7b.
The molten steel that has come into contact with 2 is drawn downward while forming a solidified shell.

In order to delay solidification on the short sides, it is advantageous to form the inner surfaces of the short side plates in contact with the molten steel with a refractory material. This disclosure discloses a short side plate in which a refractory is supported by a frame part on a metal plate having a frame part.

In addition to supporting the refractory, the provision of the frame is effective in promoting solidification in the corners of the casting space and preventing molten steel from entering between the short side plate and the metal belt.

(Problem to be Solved by the Invention) It is advantageous for the refractory material in the center of the short side plate to have high heat insulation and thermal shock resistance. A mixture of these and boron nitride is suitable.

However, if the entire refractory is made of a new material, the molten metal will solidify on the surface of the short side plate due to the high thermal conductivity of the material, and the frame part that holds the refractory due to its high coefficient of linear expansion. It has the disadvantages of deformation and high cost, making its application difficult.

On the other hand, when fused silica is used as a refractory, the ends of the slab begin to solidify at the frame that holds the refractory, but a solidified layer also develops on the refractory surface, and this solidified layer is It cannot withstand long casting times because it easily scrapes things off and eventually damages the refractory.

The purpose of this invention is to propose a short side plate that can avoid wear of refractories.

(Means for Solving the Problems) The present invention provides a pair of circulating bodies disposed opposite each other that circulate while maintaining a gap for holding molten metal over a certain distance, and both sides of the circulating bodies. A picture frame formed on both side edges in contact with the circulating body in a short side plate of a continuous thin slab casting machine that constitutes a casting space with a pair of short side plates positioned at the edge and having a concave shape with an upper width and lower width. and a heat insulating refractory supported between the picture frame parts, and a wear-resistant refractory having higher high temperature hardness than the slab is interposed between the picture frame part and the heat insulating refractory. This is the short side plate of a continuous thin slab casting machine.

(Function) The molten metal supplied to the casting space of the continuous thin slab caster is
The long side is cooled by the circulating body and the short side is cooled by the frame of the short side plate to form a solidified shell. As the solidified shell on the short side grows, it extends from the picture frame to the heat insulating refractory, but in the short side plate according to the present invention, there is a layer between the picture frame and the heat insulating refractory that has wear resistance that is higher in high temperature hardness than that of the slab. Since the refractory is interposed, it is less likely to be damaged by the movement of the solidified shell when the slab is drawn, and the melting loss of the heat insulating refractory remains within a very small range.

(Example) FIG. 1 shows a short side plate according to the present invention.

In the figure, reference numeral 8 denotes a side plate main body having frame parts 9 on both side edges, 10 a heat insulating refractory supported by the frame part 9, 11 a refrigerant passage through which water etc. circulate, and 12 a frame part 9 and a heat insulating refractory. It is a wear-resistant refractory provided intermittently between 10 and 10. The wear-resistant refractory 12 is made of a refractory that has higher high-temperature hardness than the slab.

FIG. 2 shows another preferred embodiment of the present invention, in which a wear-resistant refractory 12 is provided over the entire length between the frame portion 9 and the heat-insulating refractory 10.

The surface of the frame portion 9 is sufficiently cooled by the cooling water flowing in the refrigerant passage 11, and is always given the necessary properties, namely high strength and high thermal conductivity, where the molten steel is cooled and a solidified shell is generated. . Further, the surface of the heat insulating refractory 10 held in the frame portion 9 is in contact with the molten steel, but since the heat conductivity is low, the molten steel does not solidify in the heat insulating refractory 10.

The solidified shell generated in the frame part 9 grows and a part of it tries to extend to the surface of the heat insulating refractory 10. The growth of the solidified shell stops on the surface of the highly wear-resistant refractory 12, and the solidified shell and the heat-insulating refractory 10 do not come into direct contact, so the heat-insulating refractory IO is rarely scraped by the solidified shell.

When there is no wear-resistant refractory, that is, when the conventional short-side side plate shown in FIG. When the shell is pulled downward, the heat insulating refractory IO is scraped off as shown in FIG. 4(b). As a result, the interface between the frame portion 9 and the heat-insulating refractory 10 is severely damaged, and eventually the refractory 10 at the boundary falls off, resulting in a breakout or damage to the frame portion 9.
Becomes inoperable.

Further, the width of the wear-resistant refractory 12 is preferably 3 to 20 mm; that is, if it is less than 3 widths, the above-mentioned effects cannot be obtained, and if it exceeds 20 mm, there is a risk of damaging the frame portion 9 due to thermal expansion. Further, since the shore hardness of the slab immediately after casting is 10 or less, the wear-resistant refractory 12 only needs to have a shore hardness of 1200 or less, and preferably has a shore hardness of 1200 or less.
Materials having a Shore hardness of 15 or more at .degree. C., such as silicon nitride, sialon, zirconium polide alone, or a mixture of at least one of these and boron nitride, are advantageously suitable.

Next, continuous casting using short side plates according to the present invention will be specifically explained.

The belt caster shown in Fig. 3 was used with the short side plate having the structure shown in Fig. 1, and low carbon alkylated steel was cast.゛Speed: 15m
/win was cast into a slab with a thickness of 35 mm and a width of 1000 mm. In addition, Cu material was used for the frame of the short side plate, fused silica was used for the heat insulating refractory, and ZrB and -BN materials were used for the wear-resistant refractory in the form of a rectangular block with a width of 5 mm and a length of 20 mm. . The characteristics of each refractory are shown in the table below.

For comparison, similar castings were also made using similar short side plates without wear-resistant refractories.

In the comparative example, the boundary between the frame and the refractory was damaged.
Whereas breakout occurred at 50 m, in the example it was possible to cast up to 3000 m without any problems.

Although the above embodiment uses a twin-belt continuous casting machine,
In addition, it can be applied to any twin-roll ring type ring short-side side plate made of refractory material.

In addition, although an example is shown in which the heat-insulating refractory in the center is made of fused silica, the same effect can be obtained by applying this invention to the case where a heat-insulating refractory such as alumina graphite or zirconia graphite is used. .

(Effects of the Invention) According to the present invention, wear of the heat insulating refractory in the central portion can be suppressed, thereby increasing the continuous casting length and achieving stable casting.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams showing short side plates according to the present invention; Figure 3 is an explanatory diagram of a belt caster; Figure 4 (a) is an explanatory diagram showing growth of a solidified shell; Figure 4, etc.) is an explanatory diagram showing melting loss of a heat insulating refractory. 1.2...Metal belt

Claims (1)

[Claims] 1. A pair of circulating bodies arranged opposite each other, which circulate while maintaining a gap for holding molten metal over a certain distance, and located on both side edges between the circulating bodies. In the short side plate of a continuous thin slab casting machine, which constitutes a casting space with a pair of short side side plates each having an upper and lower concave shape, a frame portion formed on both side edges in contact with the circulation body, and the frame portion A thin slab continuous casting machine comprising: a heat insulating refractory supported between the frame portion and the heat insulating refractory, and a wear-resistant refractory having higher high temperature hardness than the cast slab interposed between the frame portion and the heat insulating refractory. short side plate.