JPS6379916A - Plug for blowing gas to molten metal and its production - Google Patents

Abstract

PURPOSE:To provide the titled plug which is tougher than a porous plug, withstands long-period of use and has less tendency to clogging of holes by embedding filaments consisting of heat resistant fibers into a plug so as to be penetrated in the plug from the outside surface which should face the outside of a vessel up to the inside surface which should contact a molten metal in the penetrated state. CONSTITUTION:The filaments 5 consisting of the heat resistant fibers are inserted into the fine holes 4 penetrated from the inside surface 3 up to the outside surface 2 into the blowing plug 1 to be attached and provided to the bottom or wall of the vessel contg. the molten metal. The fibers made of, for example, high fire resisting alumina, zirconia, carbon, etc., are used as the above-mentioned heat resistant fibers and the filaments 5 are formed by bundling plural pieces of such fibers. Each filament 5 is preferably sized about 1mm in diameter. The material to constitute the plug 1 except the filaments 5 is dense structure made of refractories, for which, for example, alumina, zirconia, etc., are used.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a plug for blowing gas into molten metal and a method for manufacturing the same.

(Prior Art) During refining of molten metal, gas is blown into the molten metal. Gas blowing is carried out for various purposes, such as stirring metals to promote reactions, degassing, desulfurization, floating inclusions, or equalizing molten steel temperature and added components. In either case, it is necessary that bubbles of appropriate size be created in the molten metal.

For this purpose, a refractory gas injection plug is attached to the wall or bottom of the container containing the molten metal. In the past, porous plugs were used as gas injection plugs, but in recent years, straight-hole plugs, in which a dense refractory material is penetrated with many linear pores, have come to be used.

The porous plug is made by partially fusing refractory particles on its surface to form a millet-like structure. Therefore, porous plugs have poor strength and therefore cannot withstand long-term use. In addition, it is difficult to uniformly generate bubbles of the same size because they fill all the irregular gaps, and during use. There is a drawback that when the gas blowing is stopped, molten metal tends to enter the holes, which tends to cause the holes to become clogged. Therefore, there was a drawback that the gas pressure could not be varied over a wide range.

On the other hand, a straight hole plug has a structure in which a dense refractory is penetrated by many linear pores. A straight hole plug has pores of uniform cross section and can be distributed to a desired density. Therefore, straight hole plugs are strong and can withstand long-term use, and can uniformly generate bubbles of the same size, and by reducing the cross-sectional area of the hole, gas can be blown during use. Even if it is completely stopped, the hole will not be clogged by molten metal. Therefore, it became possible to change the gas pressure over a wide range. In this way, the straight-hole plug seemed to have improved all the shortcomings of the porous plug (the problem that the invention aims to solve).However, even with such a straight-hole plug, the conventional plugs have never been satisfactory. It wasn't something. This is because the amount of gas blown is small and therefore the gas cannot be completely blown efficiently. In other words, in order to increase the total amount of gas injected, the cross-sectional area of the pores must be increased, but when the cross-sectional area is increased, molten metal enters the pores and causes pore clogging. . Therefore, it was considered to increase the amount of gas injected by increasing the number of pores while leaving the cross-sectional area of the pores as large as possible. Increasing the plug's strength reduces the plug's useful life. Therefore, it has been desired to maintain the current advantages of the straight-hole type plug, increase the amount of gas blown, and facilitate the blowing of gas. This invention is
This is an attempt to meet such requests.

(Means for solving the problem) This inventor (well, the conventional straight-hole type plug had completely empty pores was completely improved, and the pores were filled with threads of refractory fiber. We considered using the gaps around and within the threads as gas passages.In other words, in conventional straight-hole plugs, instead of making the pores hollow, we created a structure in which the pores were filled with refractory fibers. By doing so, we attempted to prevent weakening of the plug due to the formation of pores and to make the gaps finer due to the presence of the refractory fibers.

The inventor formed a plug by extending a large number of threads made of refractory fibers in a straight line and arranging them close to each other, filling the space between them with a refractory material 11, and penetrating the threads into the plug. It has been found that the strength of the plug does not decrease significantly even if a large number of threads are embedded. In addition, the plug in which the yarn is embedded in this way contains minute gaps inside and around the yarn, and these gaps allow gas to pass through, but do not allow molten metal to enter. I discovered that. Therefore, it was confirmed that a straight-hole plug with easy gas injection could be obtained in this manner. This invention was made based on such knowledge and confirmation.

(Summary of the Invention) This invention is a densely structured refractory plug to be attached to the bottom or wall of a container containing molten metal. This invention relates to a plug for blowing gas into molten metal, which is embedded in a state in which a plurality of threads made of heat-resistant fibers penetrate all the way to the inner surface.

In addition, the invention of a manufacturing method related to this is such that a plurality of threads made of heat-resistant fibers are placed in a plug mold in a straight line from the outer surface that should face the outside of the container to the inner surface that should be in contact with the molten metal. This invention relates to a method for manufacturing a plug for gas injection, which is characterized by stretching the yarn into a shape, then densely filling a refractory around the yarn to form a plug, and then firing the molded body taken out of the mold. .

(Example) Regarding an example of all the gas blowing plugs according to the present invention,
The explanation is as follows based on the drawings. Figure 1 shows
This figure shows a gas blowing plug according to the present invention, (a
) is a plan view thereof, and (b) is a sectional view taken along the line BB in (a). FIG. 2 is a partially cutaway enlarged perspective view of a thread that can be used in the present invention. FIG. 8 is a partially cutaway enlarged perspective view of another thread that can be used in the present invention.

FIG. 4 is a plan view of another plug according to the invention.

In FIG. 1, ■ is a plug made of refractory material.

2 is the outer surface of the plug 1, which is the surface that should face the outside of the container. 8 is the inner surface of the plug 1, which is the surface that should come into contact with the molten metal. 4 is a pore in which a thread 5 is inserted.
is inserted. The thread 5 extends linearly inside the plug 1 from the outer surface 2 to the inner surface 8 with a substantially -shaped cross section, and penetrates the inside of the plug. The plug of this invention differs from conventional plugs in that the pores include threads 5 made of heat-resistant fibers.

The yarn 5 is made of heat-resistant fiber as described above. By heat-resistant fibers we mean fibers made of materials that do not melt when they come into contact with molten metal. For example, it refers to fibers made of highly refractory alumina, zirconia, carbon, silicon nitride, etc. The yarn 5 means a bundle of a plurality of single fibers.

The state in which the fibers are bundled to form the yarn 5 may be twisted or untwisted.

That is, as shown in FIG. 2, the yarn 5 may be made by twisting and converging a large number of fibers without using a binder, or as shown in FIG. To,
A large number of fibers may be arranged in parallel and bundled with a binder.

Furthermore, the fibers may be twisted and then a binder added thereto, or the fibers may be simply arranged in parallel without using a binder.

As the binder, phenol resin, urea resin, sodium silicate, vinyl acetate copolymer resin, etc. can be used.

The binder may penetrate between the fibers constituting the yarn, or may cover only the surface of the yarn.

The diameter of the thread 5 is preferably about one thread, but it may be larger than that. Although it is desirable that the yarns 5 do not contact adjacent yarns, they may contact each other. In an extreme case, the threads 5 may be gathered at the center of the plug 1, as shown in FIG.

The plug of the present invention is no different from the conventional straight hole plug except for the thread 5. The material constituting the plug is a dense structure made of refractory material. The materials that have already been used as constituent materials for direct hole plugs can be used as they are. The material is, for example, alumina, zircon, magnesia, or spinel thereof.

The plug of the present invention is produced by first molding the refractory into a fully dense structure containing the threads 5, and then firing this molded body. During molding, the yarn 5 is fully stretched in advance in the mold,
Fill the area with refractory material. The threads 5 are arranged so as to penetrate from the outer surface of the plug to the inner surface of the plug within the mold, and to avoid contact with each other as much as possible and to be close to each other, but depending on the case, the threads 5 may be brought into contact with each other. . The state of the yarn arranged in this way remains in the plug as it is. If a binder is used, the binder is burned away during the firing process, and voids having a shape corresponding to the shape of the binder are subsequently formed.

When using the plug of the present invention, a gas reservoir 6 is provided in contact with the outer surface 2, as shown in FIG.
A pipe 7 is attached to the pipe 7, and gas is pressurized through the pipe 7.

According to this invention, the plug is constructed with a dense structure made of refractory material, and threads made of heat-resistant fibers penetrate from the outer surface that should face the outside of the container to the inner surface that should be in contact with the molten metal. Because it is embedded in the fibers, there are small gaps between the fibers, so it has all the characteristics of a straight hole plug,
Therefore, compared to porous plugs, it is tougher and can withstand long-term use, and it also has all the advantages of being able to uniformly generate microscopic bubbles of uniform size, making it less likely to cause clogging noise. . On top of that, the threads are made of heat-resistant fibers, so the threads do not burn out even when the plug is in use, and are always present in the plug to fully reinforce the plug, so the pores are hollow. The plug is stronger than the case. Therefore, the plug does not reduce its strength even if the yarns are placed close to each other. Therefore, a large amount of yarns can be brought close to each other in the plug, and gas permeability can be further increased. Moreover, in this plug, the actual gas passage is made up of small gaps between the fibers and between the fibers and the dense structure refractory, so molten metal is not allowed to enter, so it is better than the conventional straight hole plug. This also makes it even more difficult for holes to become clogged. Furthermore, gas passages are formed only in the positions where the threads are present, and the gap between the fibers can be fully adjusted by adjusting the twist of the fibers and the amount of binder, so the air bubbles can be dispersed as desired depending on the arrangement of the threads. can be generated into a state. Thus, according to the present invention, it is possible to obtain a straight-hole plug that is easy to blow into as desired. As a result, it is possible to provide a straight-hole plug that can be used in special alloy steel and high-temperature refining.

In these respects, the effects of this invention are significant.

Next, details regarding this invention will be explained by giving specific examples.

Specific Example Highly refractory alumina fibers with a fiber thickness of about 0.01 m are immersed in a solution of an initial condensate of phenolic resin (binder), and 100 fibers are twisted together to form a fiber with a thickness of 1.0 m. It was made into a Fl m thread. 100 of these threads were arranged at equal intervals, and an alumina refractory material was densely filled around the threads to form a plug. Thereafter, this was fired at 650° C. to obtain the entire plug as shown in FIG.

This plug has a gap of 0.01m even at the largest gap.
It was about. Therefore, even if this is used for blowing gas into molten metal, no clogging will occur, and the amount of gas permeation is 3 Kf.
! /- at 4001 Jtorr/min, reaching 15 times that of the conventional straight-hole plug, and the gas produced was evenly dispersed and uniform in size. Therefore, it is easier to blow gas than before, and it can be carried out with high efficiency.

[Brief explanation of the drawing]

Fig. 1 shows the entire gas blowing plug according to the present invention, (a) is a plan view thereof, and (b) is a B--B in Fig. 1 (a).
It is a sectional view taken along the B line. FIGS. 2 and 8 are partially cutaway enlarged perspective views of yarns that can be used in the present invention. FIG. 4 is a plan view of another plug according to the invention. In the figure, l is a plug, 2 is an outer surface, 8 is an inner surface, 4 is a pore, 5 is a thread, 6 is a gas reservoir, and 7 is a pipe. Patent applicant Fuoseco Japan Limited (Figure 5, Figure 4)

Claims (1)

[Claims] 1. A dense structure plug made of refractory material to be attached to the bottom or wall of a container containing molten metal, from the outer surface that should face the outside of the container to the inner surface that should come into contact with the molten metal. , a plug for blowing gas into molten metal, which is embedded through a thread made of heat-resistant fibers. 2. In the mold for forming a plug, string multiple threads made of heat-resistant fibers in a straight line from the outer surface that should face the outside of the container to the inner surface that should contact the molten metal when used as a plug, and then string around the threads. 1. A method for producing a gas injection plug, comprising: forming a plug by densely filling a refractory with a refractory, and then firing the formed body taken out from the mold.