JPS5919715Y2 - porous plug - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in porous plugs for blowing gas into molten metal, such as molten steel.

For example, it is a widely known technique to adjust the temperature and composition of molten steel by blowing oxygen, argon, or other gas into the molten steel so that nonmetallic inclusions in the molten steel float.

Generally, it is known that gas is supplied from a porous plug provided at the bottom or side of a ladle or tundish as the gas blowing means.

However, when the porous plug used for the above gas supply is used repeatedly many times, due to the thermal history,
Often approximately 30 mm from the surface in contact with the molten steel, i.e. from the working surface.
It has the disadvantage that cracks occur approximately parallel to the surface between mm, resulting in peeling damage.

In order to solve the above drawbacks, for example,
As described in No. 454, a hole is provided in a relatively dense brick body made mainly for mechanical strength, and a porous refractory made mainly for breathability is fitted into this hole. and an embodiment in which it is integrally formed, and JP-A-49-97705.
As described in the above issue, the porous refractory is made of high-temperature fired basic bricks that have high hot strength and good corrosion resistance, and this is used as an inner cylinder, and a defective material with good spalling resistance is attached to the outer periphery of this inner cylinder. A method in which the bottom is formed integrally with baked bricks, or a method in which the outer periphery and bottom of the porous refractory body are surrounded by a layer of refractory material with low air permeability, as described in Utility Model Application No. 52-127010. , an embodiment has been proposed in which a connection hole for inserting and connecting a gas introduction pipe is provided in approximately the center of the bottom of the surrounding refractory material layer.

However, even in each of the above embodiments, since the porous plug has a porous structure, as mentioned above, it is insufficient to significantly resolve the peeling damage caused by spalling, and its lifespan is short, usually after every 5 to 6 uses. It was a consumable item that was intended to be replaced.

The inventors of the present invention investigated the details of the peeling damage caused by the above-mentioned spalling of the porous plug, and found that by selecting the gas discharge area of the porous plug, as shown in Figs. 1 and 2, the above problem could be solved. We found that this can be reduced and suppressed.

In other words, as the gas discharge area of the porous plug is reduced, the temperature distribution behind the operating surface becomes steeper, the steady temperature position moves toward the operating surface, and the maximum value of the tensile stress decreases. , and its position moves toward the operating surface.

Therefore, based on the above knowledge, the present inventors adopted a porous refractory with a small cross section as the structure of a porous plug, and combined a plurality of the small cross section porous refractories based on specific structural conditions. By making it into a hollow body, we have developed a porous plug that secures a sufficient gas flow rate to achieve the gas blowing effect and has sufficient strength to withstand multiple uses.

Hereinafter, the present invention will be specifically explained based on the drawings.

FIG. 3 is a vertical sectional view showing one embodiment of the porous plug according to the present invention, and this porous plug has an externally inserted structure (for example, a method in which it is attached from the outside of a ladle).

In the figure, 1 is a porous refractory rod made primarily for breathability.

The rod 1 is made of a porous refractory material having pores through it in the axial direction, or a porous refractory material having air permeability as a whole due to voids formed between refractory particles.

The cross-sectional shape of the rod 1 is not limited to a circular or square shape, but as is clear from FIGS. If it is a melting point metal, the diameter is preferably 50 mm or less.

The gas flow rate that can be supplied from the single small cross-section porous refractory rod 1 is naturally limited.

Therefore, in order to secure the necessary absolute amount, a plurality of the above-mentioned rods 1 are used at once.

The plurality of porous refractory rods 1 have a plurality of metal wire cores 2.
They are arranged in parallel in one direction and surrounded by a monolithic refractory 3 having low air permeability to form a refractory molded body 4.

As shown in FIG. 4, the rod 1 is surrounded by the monolithic refractory 3, in which the rod 1 and the metal wire core 2 are arranged side by side at a predetermined interval, and the rod 1 and the metal wire core The sides of the two groups are surrounded by monolithic refractories 3, or as shown in FIG.
A metal wire core 2 is placed between the groups of the rods 1 or around the group of rods.
There is a mode in which the refractories are arranged side by side and their sides are surrounded by monolithic refractories 3.

The refractory molded body 4 obtained as described above is fitted into the metal cylinder 5.

A ring-shaped spacer 6 is interposed between the lower end of the refractory molded body 4 and the bottom upper surface of the metal cylindrical body 5, and a space 7 surrounded by the molded body 4 and the cylindrical body 5, that is, a supply gas Forms a pool.

Another method for forming this space 7 is to form a step (not shown) by molding a part of the metal cylinder 5 at the lower part of the inner circumferential surface of the metal cylinder 5. It can be a spacer 6.

A conduit 8 connected to a gas supply source (not shown) is connected to the center of the bottom of the metal cylinder 5 and communicates with the space 7 .

A cylindrical metal mesh 9 is arranged on the side of the refractory molded body 4 configured as described above, and the side of the refractory molded body 4 and the bottom of the metal cylinder 5 are arranged to have low air permeability. Monolithic refractory 10
Surround it using

As the monolithic refractories 3 and 10 with low air permeability, alumina or magnesia refractories whose particle size has been adjusted can be used.

Metal wire core 2 interposed in the monolithic refractories 3 and 10
The metal mesh 9 prevents the monolithic refractory from peeling off due to spalling, and the metal mesh 9 acts to bind the porous plug, which is a composite structure.

The porous plug shown in FIG. 6 is made of a monolithic refractory 10 and has an appearance shaped like an inverted truncated cone, and is inserted and removed by insertion.

The internal composite structure of this porous plug is the same as that shown in FIG. 3, so the explanation will be omitted.

The porous plug shown in FIG. 7 is another modification of the present invention, in which the refractory molded body 4 shown in FIG. These two refractory molded bodies 4 are arranged side by side, and a cylindrical metal mesh 9 is placed on the outer side of the refractory molded bodies 4. It is a porous plug with a rectangular appearance in which the bottom of the body 5 is surrounded by a monolithic refractory 10 with low air permeability and formed into a trapezoid or inverted trapezoid.

In this porous plug having a rectangular appearance, the refractory molded body 4 may have a circular shape.

Further, as another modification of the porous plug according to the present invention, as shown in FIG.
When surrounding with the monolithic refractory 10, a porous plug that surrounds only the sides of the molded body 4 and the cylinder 5, and as shown in FIG. A porous plug using a double cylindrical body in which the cylindrical body 11 is joined, and furthermore, a 10th
As shown in the figure, as a double cylinder structure, there is a porous plug in which a layer of monolithic refractory material 10 is formed between the bottoms of an inner cylinder 4 and an outer cylinder 11.

As described above in various aspects, the porous plug of the present invention has a plurality of small cross-section porous refractory rods 1 and metal wire cores 2 arranged in parallel in one direction and surrounded by a monolithic refractory 3. The refractory molded body 4 is fitted onto the metal cylindrical body 5 via the spacer 6, and the refractory molded body 4 and the metal cylindrical body 5 are assembled together.
The working surface of the porous plug is
That is, spalling of the plurality of porous refractory rods 1 is eliminated in the gas injection part, and the monolithic refractories 3 and 10 reinforcing the rods 1 have a double structure, and the monolithic refractories 3 The metal wire core 2 is interposed within the refractory, and the metal mesh 9 is interposed within the monolithic refractory 10 to create an integrated composite structure.
Hot strength, corrosion resistance, and spalling resistance are mutually improved, and while conventional products had to be replaced every 5 to 6 uses, the product of this invention can be used to replace the siding bricks to which porous plugs are attached. It is now possible to extend the service life to a point where it can be handled.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between temperature and distance from the operating surface of porous refractory rods with different diameters. Figure 2 is a graph showing the relationship between the distance from the operating surface and the tensile stress of porous refractory rods with different diameters. 3 to 10 show aspects of the porous plug according to the present invention, and FIG. 3, FIG. 8, FIG. 9, and FIG. 5 and 5 are explanatory horizontal cross-sectional views of the refractory molded body 4, FIG. 6 is an explanatory vertical cross-sectional view of an internal porous plug, and FIG. 7 is an explanatory horizontal cross-sectional view of a rectangular porous plug. 1...Small cross-section porous refractory rod, 2...
・Metal wire core, 3, 10... Monolithic refractory, 4.
... Refractory molded body, 5, 11 ... Metal cylinder, 6 ... Spacer, 7 ... Space, 8 ... Gas Conduit, 9...metal mesh.

Claims (1)

[Scope of utility model registration request] A refractory molded body 4 in which a plurality of small cross-section porous refractory rods 1 and a plurality of metal wire cores 2 are arranged in parallel in one direction and surrounded by a monolithic refractory 3 is made of metal via a spacer 6. A porous plug that is fitted into the cylinder 5 and has a bottom shape made of an amorphous refractory 10 with a cylindrical metal mesh 9 interposed between the outer surfaces of the refractory molded body 4 and the metal cylinder 5. .