JP7134108B2 - Manufacturing method for stoppers, etc. - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting nozzle, such as a stopper for controlling the flow rate of molten steel discharged from a tundish into a mold, or an immersion nozzle or upper nozzle in continuous casting of molten steel. In this specification, a stopper or nozzle for continuous casting is simply referred to as "stopper or the like".

Some of such stoppers have a gas blowing function for the purpose of floating inclusions in the molten steel or preventing inclusions from adhering to the inner wall of the nozzle.
For example, in Patent Document 1, a porous graphite-containing carbon bond refractory having an air permeability at the tip of the stopper of 500 to 5000 (cm ³ ) (cm)/(min) (cm ² ) (kg/cm ² ) A stopper for a gas blowing tundish is disclosed comprising:
Further, Patent Document 2 discloses that a plurality of through holes of 0.1 to 0.5 mm are arranged radially from the inner surface of the tundish stopper toward the outer surface in the horizontal direction with respect to the axial center of the tundish stopper. A featured tundish stopper is disclosed.

However, when the gas is discharged from a porous refractory material as in Patent Document 1, the bubble diameter of the gas tends to increase, and the gas discharge rate becomes excessive, resulting in an insufficient cleaning function. be. Therefore, it is preferable to discharge the gas from a small-diameter through-hole as disclosed in Patent Document 2.

However, Patent Document 3 also states, ``If the position of the fixed combustible body is displaced when the raw material is put into the mold, or if the combustible body is a thin fiber, it will bend and entangle and form a fixed position as a through hole. It is technically difficult to set the diameter to "," it is difficult to stably form a small-diameter through-hole as shown in Patent Document 2 as designed, If they are not formed as designed and stably, the intended gas bubble diameter and gas discharge rate may not be obtained stably, and the anti-adhesion and cleaning functions may become insufficient.

In order to solve the problem of Patent Document 2, Patent Document 3 describes, "In a rubber press device, the warp made of combustible yarn open (blind-like) fabric has through holes formed in the axial direction, and the weft threads have through holes. Cylindrical through-hole forming bodies arranged in the circumferential direction to maintain the spacing are fixed to the tip of the core metal for molding, then the mold is filled with refractory clay and molded, and then fired to make the combustible yarn. A method for manufacturing a gas-blowing type stopper head, characterized by burning off a cylindrical through-hole forming body of open (blind-like) fabric to form fine gas-blowing through-holes.

JP-A-61-095756 JP-A-03-110048 JP-A-01-205857

However, even with the method of Patent Document 3, it is difficult to completely prevent deformation and misalignment of "warp made of combustible yarn open (blind-like) fabric" especially during molding. It remains difficult to manufacture through-holes with high precision.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing gas discharge through holes with high accuracy.

The present invention is a method for manufacturing a stopper or the like described in 1 to 8 below.
1.
A method for manufacturing a stopper or the like having a through-hole for gas discharge, comprising:
A step of placing a material that disappears by heat treatment on the side surface of a columnar refractory molded body (hereinafter referred to as "primary molded body") to produce a core;
The core is placed in a mold for molding the stopper, etc., and the mold for molding the stopper, etc. is filled around the core to perform secondary molding, or a separate mold is prepared around the core. a step of bonding refractory molded bodies via a refractory bonding material to produce an integrally molded body containing the core;
A method of manufacturing a stopper or the like, comprising a step of heat-treating the integrally molded product.
2.
The method of secondary molding is a method of pressurizing clay, which is an aggregate of powder,
Alternatively, the method of manufacturing a stopper or the like according to 1 above, which is a method of pouring, blowing or thrusting muddy clay.
3.
In the step of producing the core, the material that disappears due to the heat treatment is installed so as to protrude outside the side surface of the primary compact, or is installed in a groove formed in the side surface of the primary compact. 2. A method for manufacturing the stopper or the like according to 2.
4.
The gas discharge through-holes are a plurality of pores, and in the step of manufacturing the core, a plurality of filaments are used as the substance that disappears by the heat treatment, and the filaments are arranged in a plurality of circumferential directions on the side surface of the primary compact. 3. The method for manufacturing a stopper or the like according to any one of 1 to 3 above, wherein the stopper is installed in a distributed manner.
5.
The method of dispersing and installing the filamentous materials in a plurality of locations in the circumferential direction of the side surface of the primary molded body includes a method of adding materials in the form of threads in advance, or a method of applying a liquid material in the form of threads and solidifying it. 4. A method for manufacturing a stopper or the like according to 4 above, which is a method.
6.
The through-holes for gas discharge are slit-shaped, and in the step of manufacturing the core, the material that disappears by the heat treatment is used as a film-like material, and the film-like material is formed on the side surface of the primary compact at a plurality of locations in the circumferential direction. 1. The method of manufacturing the stopper or the like according to 1 above, wherein the stoppers are installed in a dispersed manner or installed over substantially the entire side surface of the primary molded body.
7.
7. The method for manufacturing a stopper or the like according to any one of 1 to 6 above, wherein the primary compact has a cylindrical shape or a truncated cone shape.
8.
8. The stopper according to any one of 1 to 7 above, wherein in the step of producing the core, the substance that disappears by the heat treatment is installed so that one end thereof communicates with the gas introduction path inside the stopper or the like. etc. manufacturing method.

By using a primary molded body and placing a substance that disappears due to heat treatment on its side surface, when filling the clay during secondary molding, the shape and shape of the substance that disappears due to heat treatment (becomes a through hole for gas discharge) position can be maintained.
As a result, it is possible to prevent the gas ejection through-hole from being crushed or deformed in the manufacturing stage, and the gas ejection through-hole can be obtained as designed.

FIG. 1 is an image diagram of an embodiment of a stopper, etc. (a stopper and a nozzle for continuous casting) manufactured by the manufacturing method of the present invention, viewed in longitudinal section. The image figure (plan view) which looked at the stopper shown in FIG. 1 from the downward direction. FIG. 2 is an image diagram (plan view) of the nozzle shown in FIG. 1 as viewed from above; FIG. 4 is an image diagram of the structure of the stopper manufactured by the manufacturing method of the present invention, viewed in longitudinal section. In the method of manufacturing the stopper according to the present invention, an image diagram of the arrangement of the primary molded body and the thread when forming a plurality of pores by placing the thread as a substance that disappears by heat treatment on the side surface of the primary molded body (the stopper is placed in the direction of the tip) view from the top). In the stopper manufacturing method according to the present invention, the primary molded body and the grooves when forming a plurality of pores by placing a liquid material as a substance that disappears by heat treatment in the grooves formed on the side surface of the primary molded body (Liquid) arrangement image diagram (top view of the stopper viewed from the tip direction). In the same way as in Fig. 5, an image of the placement of the primary molded body and the film-like material when forming slits by placing the film-like material on the side surface of the primary molded body as a substance that disappears due to heat treatment (stopper from the tip direction) example showing a top view).

A mode for carrying out the present invention will be described.

1 to 3 show a stopper 10 and a nozzle 20, which are one embodiment of a stopper manufactured by the manufacturing method of the present invention.
The stopper 10 is an integral molding of a columnar (truncated cone-shaped) primary molded body 11 (a portion that becomes a core when the stopper 10 is manufactured) and a secondary molded body 12. A plurality of holes 13 are provided as through-holes for gas ejection at predetermined intervals in the direction. One end (base end) of each pore 13 communicates with an inner hole 12a, which is a gas introduction path inside the stopper 10 (secondary compact 12). It is discharged from the other end (tip) of the pore 13 .
The nozzle 20 is also an integral molding of a columnar primary molded body 21 (a portion that becomes a core when the nozzle 20 is manufactured) and a secondary molded body 22, and a predetermined interval is provided in the circumferential direction of the side surface of the primary molded body 21. , a plurality of pores 23 are provided as through-holes for gas discharge. One end (base end) of each pore 23 communicates with a gas pool 22a, which is a gas introduction path inside the nozzle 20 (secondary compact 22). It is discharged from the other end (tip) of the pore 23 . The nozzle 20 has a nozzle hole 24 that can be fitted with the stopper 10 as shown in FIG.

As described above, the stopper, etc. of this embodiment is an integrally molded product of the primary molded body and the secondary molded body. has no restrictions.
That is, any composition can be adjusted according to individual operating conditions, etc., from the viewpoints of adhesion of inclusions during continuous casting, corrosion resistance, wear resistance, and the like. However, it must have physical properties that do not cause breakage, deformation, etc., during secondary molding, especially in pressure molding such as CIP, which is exposed to high pressure.
As for the molding method, it is a so-called monolithic refractory that is hardened after molding by a method of pressurizing the clay, which is an aggregate of powder, or by pouring, blowing, or plunging the muddy clay. The molding method and the like can be arbitrarily selected.
In the present embodiment, the secondary molding is performed by placing a core prepared by placing a substance that disappears by heat treatment on the side surface of the primary molded body in a mold for molding a stopper or the like, and placing the stopper around the core. This is done by filling the clay for uniform molding, but here, "filling the clay" means pressurizing the clay, which is an aggregate of powder, as described above, and pouring or blowing in the clay that is muddy. , is a general term for thrusting.

There are no restrictions on the composition of the substance that disappears by heat treatment, as long as it disappears at a temperature below the heat treatment temperature. For example, threads or the like that are already solid at room temperature can be used, as shown in FIGS. 4 and 5 described below. On the other hand, as shown in FIG. 6, for example, when a groove 11a is formed on the side surface of the primary molded body 11 and placed in the groove 11a, liquid substances are used. Liquids with hardness can be used.

When installing the thread on the side surface of the primary molded body, as shown in FIG. A substance 16 that disappears by heat treatment may be placed so as to bury the thread 14 over an arbitrary length and the entire circumference. The portion where the substance 16 that disappears by the heat treatment is installed becomes a space after the heat treatment, and becomes a gas flow path (gas pool for homogenizing the gas).
On the other hand, the part where the thread 14 is installed (see FIG. 5) becomes the pores 13 as shown in FIG. It communicates with a gas flow path (gas pool for gas homogenization) formed in the part. That is, in FIG. 4, the thread 14 is installed so that one end (base end) thereof communicates with the gas flow path (gas pool for gas homogenization) formed in the portion where the substance 16 that disappears by heat treatment is installed. ing.
A core rod is attached to the inner hole 12a in FIG. 4 at the time of molding.

The nozzle 20 (pore 23, gas pool 22a) shown in FIGS. 1 and 3 can also be manufactured by the same method as in FIG.

Here, the horizontal cross-sectional shape (outer shape) of the columnar primary compact is not particularly limited, and can be arbitrarily selected from circular, elliptical, polygonal, and the like. However, in order to equalize the applied pressure in the secondary molding, it is most preferable to use a circular shape, and in the case of a polygonal shape, it is preferable to make the edge portions curved (with R).

Although the through holes for gas ejection are a plurality of fine holes in the above embodiments, the through holes for gas ejection may be slits. In this case, for example, as shown in FIG. 7, the substance that disappears due to heat treatment is used as a film-like material 17, and this film-like material 17 is dispersed and installed at a plurality of locations in the circumferential direction of the side surface of the primary molded body 11, or the primary molding is performed. It is installed on substantially the entire side surface of the body 11 . It should be noted that the reason why it is set "substantially all over" is that there is a need for a partial joint between the side surface of the primary molded body 11 and the secondary molded body 12 surrounding it.

The size of these gas discharge through-holes (pore diameter, slit thickness) can be arbitrarily set according to individual operating conditions, but preferably the pore diameter is 2 mm or less or the slit By setting the thickness to 1 mm or less, the flow rate can be controlled with higher accuracy, and the ratio of small-diameter bubbles (approximately less than 3 mm) that easily floats inclusions in the molten steel and does not easily cause defects in the steel is increased. be able to.

In the above embodiment, an integrated molding including the core is produced by secondary molding. It is also possible to make an integral molding that includes the core by joining via.

REFERENCE SIGNS LIST 10 stopper 11 primary compact 11a groove 12 secondary compact 12a inner hole (gas introduction path)
13 pore (through hole for gas ejection)
14 thread (substance that disappears due to heat treatment)
15 core 16 substance that disappears due to heat treatment (portion that becomes gas flow path (gas pool))
17 film-like substance (substance that disappears due to heat treatment)
20 nozzle 21 primary compact 22 secondary compact 22a gas pool 23 pore (through hole for gas discharge)
24 nozzle holes

Claims (8)

A method for manufacturing a continuous casting stopper or nozzle (hereinafter simply referred to as "stopper, etc.") having a gas discharge through hole, comprising:
A step of placing a material that disappears by heat treatment on the side surface of a columnar refractory molded body (hereinafter referred to as "primary molded body") to produce a core;
The core is placed in a mold for molding the stopper, etc., and the mold for molding the stopper, etc. is filled around the core to perform secondary molding, or a separate mold is prepared around the core. a step of bonding refractory molded bodies via a refractory bonding material to produce an integrally molded body containing the core;
A method of manufacturing a stopper or the like, comprising a step of heat-treating the integrally molded product. 2. Manufacture of a stopper or the like according to claim 1, wherein the method of secondary molding is a method of pressurizing clay that is an aggregate of powder, or a method of pouring, spraying or plunging clay that is muddy. Method. 2. In the step of producing the core, the material that disappears due to the heat treatment is installed so as to protrude outside the side surface of the primary compact, or is installed in a groove formed in the side surface of the primary compact. A method for manufacturing a stopper or the like according to claim 2. The gas discharge through-holes are a plurality of pores, and in the step of manufacturing the core, a plurality of filaments are used as the substance that disappears due to the heat treatment, and the filaments are arranged in a plurality of circumferential directions on the side surface of the primary compact. 4. The method for manufacturing a stopper or the like according to any one of claims 1 to 3, wherein the stoppers are installed in a distributed manner. The method of dispersing and installing the filamentous materials in a plurality of locations in the circumferential direction of the side surface of the primary molded body includes a method of adding materials in the form of threads in advance, or a method of applying a liquid material in the form of threads and solidifying it. A method for manufacturing a stopper or the like according to claim 4, which is a method. The through-hole for gas discharge is slit-shaped, and in the step of manufacturing the core, the material that disappears by the heat treatment is used as a film-like material, and the film-like material is formed on the side surface of the primary compact at a plurality of locations in the circumferential direction. 2. The method of manufacturing a stopper or the like according to claim 1, wherein the stoppers are installed in a dispersed manner or are installed over substantially the entire side surface of the primary molded body. 7. The method for manufacturing a stopper or the like according to any one of claims 1 to 6, wherein said primary molded body has a cylindrical shape or a truncated cone shape. 8. The method according to any one of claims 1 to 7, wherein in the step of producing the core, the substance that disappears by the heat treatment is installed so that one end thereof communicates with a gas introduction path inside the stopper or the like. A method for manufacturing a stopper, etc.

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