JP4658302B2 - Porous plug manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is attached to the bottom of a ladle or the like, and in molten steel for homogenization of molten steel accompanying molten steel stirring, homogenization of molten steel components, improvement of secondary refining effect, floating removal of nonmetallic inclusions, etc. The present invention relates to a method for manufacturing a porous plug for injecting gas.
[0002]
[Prior art]
Since the porous plug is used attached to the bottom of the ladle in this way, gas is discharged only from the surface of the tip that contacts the molten steel, and gas is not emitted from the other surface of the breathable refractory. It has a sealed structure.
[0003]
For example, as shown in FIG. 4, there is a structure that prevents gas discharge from other than the tip surface by applying a sealing material 52 around a breathable refractory 51 and covering the periphery with a metal case 53. . The thickness of the sealing material is usually 1 to 5 mm. The assembly work of the porous plug of this structure is usually performed by applying the sealing material 52 to the surface of the breathable refractory 51, covering the metal case 52, and thereafter attaching the metal bottom plate 55. At this time, when the porous plug is large, it is necessary to apply the sealing material to a considerably large area, and it becomes difficult to uniformly control the coating thickness. And when the thickness of a sealing material is too thin, since the sealing performance of the surface of a breathable refractory is insufficient, a gas leak may occur between the metal case and the sealing material. Further, as a procedure at the time of manufacture, since the sealing material is applied to the surface of the breathable refractory and then inserted into the cylindrical metal case, the viscosity of the sealing material must be lowered to some extent. When the viscosity of the sealing material is high, the resistance during insertion increases, making insertion difficult. Accordingly, the amount of liquid added to reduce the sealing viscosity increases, so that the sealing performance is insufficient, or cracks are generated after drying, which may leak from the cracks.
[0004]
In order to compensate for these drawbacks, recently, as shown in FIG. 5, the use of a castable between a breathable refractory and a metal case is increasing. The outer peripheral surface of the breathable refractory is casted with a castable 54 and the outer periphery of the castable 54 is covered with a metal case 53. These types are widely used because they can be manufactured relatively easily and can be used stably. In this case, the corrosion resistance of the castable is higher than that of the sealing material, so that the thickness can be increased. Further, since the breathable refractory is covered with the castable, it is considered that there is no risk of gas leakage.
[0005]
However, when closely observed, it has been found that gas may leak from between the metal case 53 and the castable 54 at the tip of the porous plug as indicated by an arrow. This type of porous plug is generally manufactured by forming a cylindrical metal case around a breathable refractory and then casting the castable, and then welding a metal bottom plate 55 having a gas pipe 56. is doing. Since the castable shrinks when the castable is hardened after molding, a gap may be generated between the metal case 53 and the castable 54 depending on the shape of the porous plug and the castable material. It is also conceivable that the metal case 53 is deformed by heating after setting the porous plug during drying. For this reason, it is considered that the gas leaks from the gap between the castable and the metal bottom plate 55 through the gap between the metal case on the side plate and the castable, and from the gap between the metal case at the tip of the porous plug and the castable.
[0006]
When gas leaks from this part, the gas discharge amount becomes larger than the original gas-permeable refractory discharge amount. Therefore, many defective products are generated in the final inspection of the product, and the yield decreases.
[0007]
During lifting and use using leaking material, molten steel may enter the gap and solidify. In this case, since a necessary gas discharge amount cannot be secured suddenly, there is a problem that the refining process and the like are interrupted.
[0008]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to prevent leakage from between the metal case at the front end and the castable in the porous plug in which the space between the breathable refractory and the metal case is filled with the castable.
[0009]
[Means for Solving the Problems]
The present invention places a frustoconical breathable refractory together with a metal case surrounding the side surface of the breathable refractory on a board with a small-diameter side facing down, and a gas on the bottom of the breathable refractory. Place a disk to form a pool, pour castable between the breathable refractory and the metal case from the top, cover the bottom of the breathable refractory except the surface in contact with the gas pool and the side of the breathable refractory, and harden the castable After that, set the sealing material in a donut shape on the bottom of the castable, press the metal bottom plate having the gas pipe to extend the sealing material, and continuously arrange the sealing material so as to surround the gas pool, This is a method for manufacturing a porous plug in which a metal case and a metal bottom plate are joined by welding.
[0010]
Unlike the conventional one, the porous plug of the present invention can be provided with a sealing material in a relatively small area, so that it can be applied thickly first, and the applied thickness can be confirmed visually. Therefore, a more reliable seal can be obtained. Further, as a working form, the sealing material can be extended by pressing the metal bottom plate, so that a strong pressing force can be obtained, and a sealing material having higher viscosity than the conventional one can be used, and the sealing performance is further improved.
[0011]
The breathable refractory used in the present invention can be used without any problem as long as it is generally used as a porous plug. Also, castables that are usually used for iron making, steel making kilns, blocks, and the like can be used.
[0012]
The sealing material used in the present invention is obtained by kneading a refractory raw material powder and a binder, and is generally used between a metal case and a refractory with a steelmaking nozzle or the like, or a joint of a brick, etc. The mortar etc. which are used for can be used. Further, a sheet-like sealing material previously formed into a thin donut shape can also be used.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described by way of examples.
[0014]
Example 1
FIG. 1 shows a first embodiment of the porous plug of the present invention. As shown in the figure, between the breathable refractory 2 and the cylindrical metal case 3 and the bottom surface 5 of the breathable refractory communicate with the gas pipe 12 in order to feed gas uniformly into the breathable refractory 2. The castable 4 is covered except for the surface of the gas pool 6 provided. Reference numeral 9 denotes a sealing material filled between the bottom surface 7 of the castable and the metal bottom plate 8.
[0015]
FIG. 2 shows a method for manufacturing the porous plug of the present invention. 2A is a cross-sectional view showing an operation for pouring castable, FIG. 2B is a cross-sectional view showing a state in which a sealing material is set, FIG. 2C is a cross-sectional view in which a metal bottom plate is set, and FIG. ) Is an AA arrow plan view of FIG.
[0016]
In FIG. 2A, a breathable refractory 2 having a truncated cone shape is placed on a board 11 with a small diameter side down, and a cylindrical metal case 3 is also formed so as to surround the side of the breathable refractory 2. Place on the board 11 with the smaller diameter down. And castable 4 is poured from the upper part. A disk 10 is placed on the bottom surface 5 of the breathable refractory so as to form a gas pool so that the surface of the breathable refractory is not covered with the castable 4.
[0017]
FIG. 2B shows a state in which the sealant 9 is set in a donut shape on the bottom surface 7 of the castable after the castable is poured and then cured or dried to harden the castable. The sealing material may be set at any timing as long as the castable is cured to some extent, and may be either before or after drying.
[0018]
FIG. 2C shows a state in which the metal bottom plate 8 having the gas pipe 12 is pressed against the bottom surface 7 of the castable, and the sealing material 9 is extended. As a result, as shown in FIG. 2 (d), the sealing material is continuously arranged so as to surround the gas pool. Thereafter, by joining the metal case 3 and the metal bottom plate 8 by welding, a porous plug capable of preventing leakage from between the metal case at the front end and the castable is obtained.
[0019]
That is, the surface of the bottom surface 7 of the castable is a surface after casting the castable, and unevenness occurs when observed closely. Even if the metal bottom plate is attached in this state, a gap is generated between the metal bottom plate and the bottom surface of the castable, and the gas blown from the gas pipe is likely to leak. The gas that has passed through this gap leaks from the surface through the gap between the side metal case and the castable. Therefore, by sealing in this way, the gas blown from the gas pipe passes through the breathable refractory without leaking. Therefore, a higher effect can be obtained by continuously providing the gas pool on the bottom surface of the castable so as to surround the gas pool.
[0020]
At this time, the thickness of the sealing material is preferably 0.3 mm or more and 10 mm or less, and if it is less than 0.3 mm, there are irregularities on the castable surface, and a gap is likely to be generated between the metal bottom plate. There is a possibility that the gas itself escapes due to contraction due to heat and a gap is easily generated between the metal bottom plate and the sealing material or between the castable and the sealing material.
[0021]
In addition, the sealing material is not necessarily provided continuously around the gas pool, and may be provided over the entire contact surface with the bottom plate, but it is preferable that the width is at least 7 mm. If it is less than 7 mm, gas may escape.
[0022]
Furthermore, it can also be provided continuously without a break so as to surround the gas pool on the bottom surface of the castable in the range of 7 mm to 80 mm in width. For example, it is possible to make a ring in a clay-like soft state, place it on the castable surface around the gas pool, and secure a reliable sealing property by a simple operation such as pressing with a metal bottom plate.
[0023]
Example 2
FIG. 3 shows a second embodiment of the porous plug of the present invention. In this case, the metal case 3 is only halfway along the side surface of the castable 4 formed on the bottom surface of the breathable refractory 2 except for the side of the breathable refractory 2 and the portion of the gas pool 6 leading to the gas pipe 12. However, the sealing material 9 is filled between the bottom surface of the castable 3 and the metal bottom plate 8 to obtain a leak prevention effect.
[0024]
【The invention's effect】
Since the gas leakage of the porous plug could be prevented, the interruption of the steel production process due to the gas leak was reduced, the production was stabilized, and the necessary amount of gas could be blown into the molten steel during refining, thereby improving the quality of the steel. Can be stable.
[0025]
In addition, the number of outflow airflow standards out can be reduced by the airflow inspection at the time of manufacture, and the manufacturing cost can be reduced.
[Brief description of the drawings]
FIG. 1 shows a first embodiment of a porous plug of the present invention.
FIG. 2 shows a method for producing a porous bragg according to the present invention.
FIG. 3 shows a second embodiment of the porous plug of the present invention.
FIG. 4 shows a first conventional example.
FIG. 5 shows a second conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Porous plug 2 Breathable refractory 3 Metal case 4 Castable 5 Bottom of breathable refractory 6 Gas pool 7 Bottom of castable 8 Metal bottom plate 9 Sealing material 10 Disk 11 Panel 12 Gas pipe 51 Breathable refractory 52 Sealing material 53 Metal case 54 Castable 55 Metal bottom plate 56 Gas pipe

Claims (3)

A frustoconical breathable refractory is placed on a panel with a metal case surrounding the side of the breathable refractory, with a small diameter facing down, and a gas pool is formed on the bottom of the breathable refractory In order to put a disk
Cast the castable from the top between the breathable refractory and the metal case , and cover the bottom of the breathable refractory with the castable except the surface that contacts the gas pool,
After the castable is cured, the sealing material is set in a donut shape on the bottom of the castable, the metal bottom plate having the gas pipe is pressed to extend the sealing material, and the sealing material is continuously arranged so as to surround the gas pool,
Thereafter, a method for manufacturing a porous plug in which a metal case and a metal bottom plate are joined by welding . The method for producing a porous plug according to claim 1, wherein the sealing material has a thickness of 0.3 mm to 10 mm. The method for producing a porous plug according to claim 1, wherein the width of the sealing material is at least 7 mm or more.

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