JP6892063B2 - Gas blowing plug - Google Patents

Description

The present invention relates to a gas blowing plug that blows gas into molten metal.

Conventionally, in converters and electric furnaces, gas is blown by a gas blowing plug embedded in the bottom of the furnace in order to promote refining or agitate molten metal (molten steel).
The gas blowing plug is described in Patent Document 1, for example.
Patent Document 1 describes a gas blowing plug in which a plurality of gas blowing through hole pipes (referred to as pipes) of a plurality of metal thin tubes are internally provided in a refractory material containing carbon and graphite.

In a conventional furnace in which a gas blowing plug is embedded (for example, an electric furnace), a furnace bottom brick is placed around the gas blowing plug, and a stamp material made of a powdery fireproof raw material is filled around the bottom brick. .. Then, after melting the metal in this electric furnace, the furnace is tilted (tilted) to take out the molten metal. Then, the gas blowing plug provided at the bottom of the furnace is also tilted according to the tilt of the furnace.

When the gas blowing plug is tilted (tilted) together with the furnace, the bottom bricks arranged around the gas blowing plug push the gas blowing plug, and the pipe is relatively lateral (in the radial direction of the pipe). Power is applied. Then, stress is concentrated on the lower end of the pipe, and the pipe bends at the lower end. When further stress was applied, cracks were generated (cracks propagated) in the welded portion at the lower end of the pipe, and the pipe fell off. Gas leaks occur when pipes crack or fall off. As a result, it has become difficult to blow the desired gas.

Japanese Unexamined Patent Publication No. 10-265829

The present invention has been made in view of the above circumstances, and even if the assembled furnace is tilted, a gas in which gas leakage due to cracks or dropouts in the gas pipe through which the blown gas flows is suppressed is suppressed. The subject is to provide a plug for blowing.

The gas blowing plug of the present invention that solves the above problems is arranged through a plug body of a fireproof material, a metal base that forms a gas chamber provided below the plug body, and a lower end of the plug body. Is a gas blowing plug having a metal gas pipe that communicates with a gas chamber, and the gas pipe is characterized by having a reinforcing portion at a lower end that is joined to a base portion.

The gas blowing plug of the present invention has a structure in which a metal gas pipe is arranged so as to penetrate the plug main body and the lower end thereof communicates with the gas chamber, and has a reinforcing portion at the lower end where the gas pipe is joined to the base portion. According to this configuration, even if the furnace to which the gas blowing plug of the present invention is assembled is tilted (tilted) and a relative lateral stress is applied to the gas pipe, the gas pipe can be bent at the reinforcing portion. It can be suppressed. Therefore, it is possible to prevent the gas pipe from falling off from the base, which is caused by the gas pipe being further bent, and the occurrence of gas leak is suppressed.
In the gas blowing plug of the present invention, the reinforcing portion is preferably a portion in which the gas pipe is thickened. According to this configuration, since the reinforcing portion is composed of a thickened portion, the above effect can be exhibited with a simple configuration.

In the gas blowing plug of the present invention, the gas pipe is formed from a pipe main body made of a thin pipe and a thick metal pipe integrally provided at the base so that the pipe main body is located in the hollow part of the axis thereof. It is preferable that the reinforcing portion is composed of. According to this configuration, since the reinforcing portion is composed of a thick pipe arranged coaxially with the thin pipe, the above effect can be exhibited.

It is sectional drawing of the plug for gas blowing of Embodiment 1. FIG. It is a top view of the plug main body of the gas blowing plug of Embodiment 1. FIG. It is a partially enlarged sectional view of the lower end of the gas pipe of the gas blowing plug of Embodiment 1. FIG. It is a partially enlarged sectional view of the furnace bottom of the electric furnace to which the gas blowing plug of Embodiment 1 is assembled. It is sectional drawing of the plug for gas blowing of Embodiment 2. FIG. It is a partially enlarged sectional view of the lower end of the gas pipe of the gas blowing plug of Embodiment 2. FIG.

Hereinafter, as an embodiment, the gas blowing plug of the present invention will be specifically described using a gas blowing plug provided at the bottom of the electric furnace. In this embodiment, the vertical direction corresponds to the vertical direction when the gas blowing plug is provided on the bottom of the electric furnace, the upper side is the tip side in the gas blowing direction, and the lower side is the base end in the gas blowing direction. Corresponds to the side. Similarly, the upper side is the contact surface side that comes into contact with the molten metal.

[Embodiment 1]
The gas blowing plug 1 (hereinafter referred to as a plug) of the present embodiment has a plug main body 2, a base 3, and a gas pipe 4 as shown in a cross section in FIG.

The plug body 2 has a substantially trapezoidal shape with a small cross section in the vertical direction and a large cross section on the lower side. The substantially trapezoidal shape of the plug body 2 has an upper surface 21 facing the molten metal stored in the electric furnace, a lower surface 22 facing the upper surface 21, and an outer peripheral surface 23 connecting the upper surface 21 and the lower surface 22. The plug body 2 is formed with a convex portion 24 that is convex downward from the lower surface 22. The convex portion 24 has a columnar shape that fits into the base portion 3.

As shown in the top view of FIG. 2, the outer peripheral surface 23 of the plug main body 2 is formed so that the four planes 23a, 23b, 23c, and 23d form a trapezoidal shape. The width of the plane 23a (the length on the outer circumference on the upper surface shown in FIG. 2) is shorter than the width of the plane 23c. In this embodiment, the outer peripheral surface 23 of the plug main body 2 is formed of four flat surfaces 23a to d, but depending on the shape of the bottom of the electric furnace, a part of the surface may be curved. For example, two planes 23a and 23c, which are a trapezoidal upper base and a lower base, may form a curved surface. In this case, it is preferable that each surface is formed along a circular arc centered on the core of the electric furnace.
The specific shape (size) of the plug body 2 is not limited, and the size can be the same as that of the conventional plug.

The plug body 2 is made of a refractory material. The refractory material forming the plug body 2 is not limited, and the material used in the conventional plug can be used. The refractory is preferably, for example, a highly durable magnesia-carbon material.

The base 3 is provided at the lower end of the plug body 2. The base portion 3 includes a cylindrical base cylinder portion 32 into which the convex portion 24 of the plug body 2 fits into the upper end, a disk 33 that closes the lower portion (lower end portion) of the base cylinder portion 32, and a lower surface 24a of the convex portion 24 of the plug body 2. It has a disk 34 that is in contact with the disk 33 and closes the base cylinder 32 at a position separated from the disk 33. The hollow portion of the base tubular portion 32 is closed by two disks 33 and 34, and a gas chamber 31 is formed inside the hollow portion.
In the base portion 3, a mounting port 35 arranged coaxially with the plug main body 2 is fixedly provided at the center of the disk 33. The attachment port 35 has a pipe connected to a gas supply source through which the plug 1 supplies a gas to be blown into the molten metal.

As shown in FIG. 1, the base portion 3 has a convex portion 24 of the plug body 2 fitted and fixed to the upper end of the base tubular portion 32, and a gas chamber 31 is formed (partitioned) below the convex portion 24. The base portion 3 is fixed by inserting a pin (not shown) penetrating the base cylinder portion 32 into the convex portion 24.

The material and specific shape (size) of the members such as the base cylinder portion 32, the disks 33, 34, and the mounting port 35 forming the base portion 3 are not limited, and can be the same as the conventional plug. Examples of the material of the member forming the base 3 include heat-resistant metals such as stainless steel and steel. In this embodiment, the members such as the base cylinder portion 32, the disks 33, 34, and the mounting port 35 forming the base portion 3 are all made of heat-resistant metal.

The gas pipe 4 is made of a metal pipe arranged so as to penetrate the plug main body 2. The lower end of the gas pipe 4 is fixed to the disk 34 by welding while communicating with the gas chamber 31. The gas pipe 4 is fixed by welding on the lower surface of the disk 34 over the entire circumference of the outer circumference with the lower end penetrating the disk 34. The end surface of the lower end of the gas pipe 4 may be located on the same surface as the lower surface of the disk 34 or may be located on the lower side. As shown in FIG. 2, the upper end of the gas pipe 4 is open on the upper surface 21 of the plug main body 2.
The gas pipe 4 of the present embodiment has an alumina coating layer (not shown) having a thickness of 2 mm or more on the outer periphery thereof at a portion penetrating the plug main body 2. This alumina coating layer functions as a heat insulating material, an adhesive material, and a filler.

The thickness and inner diameter of the gas pipe 4 are not limited, but the outer diameter is preferably 3 to 7 mm and the inner diameter is preferably 1 to 3 mm. In this embodiment, a pipe made of stainless steel having an outer diameter of 3.5 mm and an inner diameter of 1.5 mm and a pipe made of stainless steel having an outer diameter of 6 mm and an inner diameter of 2 mm are combined and formed.

The arrangement form of the gas pipe 4 is not limited. In this embodiment, as shown in FIG. 2, the gas pipes 4 are arranged so as to form a hexagon as a whole at a predetermined interval. The form is not limited. The gas pipe 4 may be provided so as to form a polygon or a circle other than a hexagon.

As shown in the enlarged cross-sectional view of FIG. 3, the gas pipe 4 has a thick portion at the lower end that penetrates the disk 34 and a portion that protrudes from the disk 34 by a predetermined length (specifically, 38 mm). It has become. The thickened portion 41 at the lower end of the gas pipe 4 has an outer diameter of 6 mm. That is, the thickened portion 41 has a pipe outer diameter 1.7 times (1.5 times or more) that of the other portions. The thickened portion 41 has a constant outer diameter.
In the gas pipe 4, the inner diameter of the pipe is constant between the thickened portion 41 and the other portions.
The plug 1 of this embodiment may be provided with an additional member (for example, a thermocouple for measuring temperature) used in the conventional plug 1.
The plug 1 of this embodiment is used by being assembled to the electric furnace 5. An example of the state assembled in the electric furnace 5 is shown below.

(Electric furnace)
The electric furnace 5 has an iron skin 51, a permanent brick 52, a furnace bottom brick 53, a stamp material 54, and a seating block 55, as shown in FIG. 4 for a schematic structure of the bottom. As the electric furnace 5, a furnace similar to that of a conventional electric furnace can be used.
The iron skin 51 forms the shell of the electric furnace 5. The iron skin 51 has a through hole 511 through which the attachment port 35 penetrates at the assembly position of the plug 1.
The permanent brick 52 is arranged on the iron skin 51. A heat-resistant bonding material layer (not shown) such as mortar is disposed between the permanent brick 52 and the iron skin 51, and the permanent brick 52 is fixed to the iron skin 51.

The bottom brick 53 is arranged on the permanent brick 52. The upper surface 53a of the bottom brick 53 comes into contact with the molten metal stored in the electric furnace 5. The bottom brick 53 is arranged along the outer circumference of the plug 1 at the bottom of the fire. That is, a plurality of furnace bottom bricks 53 are arranged and arranged so as to form an annular shape as a whole. The plug 1 is arranged at the annular axial center. The fire bottom brick 53 is arranged (formed) so that the inner peripheral surface 53b can come into contact with the outer peripheral surface 23 of the plug main body 2.
The stamp material 54 is arranged on the permanent brick 52. The stamp material 54 is arranged on the outer periphery of the furnace bottom brick 53. The stamp material 54 is formed by stamping a powdered fireproof raw material stamp material.

The seating block 55 is arranged on the iron skin 51. The seating block 55 is arranged so as to be located inside the ring of the hearth brick 53 arranged in an annular shape. The seating block 55 is formed with a recess 551 on the upper surface 55a into which the lower end of the plug 1 is inserted. The seating block 55 has a through hole 552 through which the mounting port 35 penetrates.
The upper surface 55a of the seating block 55 is provided so as to substantially coincide with the upper surface of the permanent brick 52.

As shown in FIG. 4, the lower end of the plug 1 is held in the recess 551 of the seating block 55 in a state of being inserted. At this time, the attachment port 35 of the plug 1 penetrates the through holes 552 and 511 and protrudes to the outside of the iron skin 51.

(Action and effect of this form)
The operation and effect of the plug 1 of this embodiment will be described with reference to a state in which the electric furnace 5 is used.
The electric furnace 5 stores the molten metal in the state shown in FIG. 4, that is, in the state where the gas pipe 4 of the plug 1 extends in the vertical direction. Then, the electric furnace 5 is tilted (tilted) to take out the molten metal.
When the electric furnace 5 is tilted (tilted), the plug 1 provided at the bottom of the furnace is also tilted according to the tilt of the electric furnace 5. Then, as shown in FIG. 4, the hearth brick 53 (and the stamp material 54) and the permanent brick 52 arranged around the plug 1 push the plug 1. The permanent brick 52 presses the base 3 via the seating block 55, and the bottom brick 53 (and the stamp material 54) presses the plug body 2.

The displacement (deformation) of the base 3 is suppressed by the mounting port 35 penetrating the seating block 55 and the iron skin 51. On the other hand, the stress from the bottom brick 53 (and the stamp material 54) is applied to the plug body 2 as it is. As a result, stress is concentrated on the lower end side of the plug body 2, particularly on the lower end of the gas pipe 4.

The plug 1 of the present embodiment has a reinforcing portion including a thickened portion 41 at the lower end portion where the gas pipe 4 is joined to the base portion 3. Due to this reinforcing portion (thickened portion 41), the strength of the lower end portion (thickened portion 41) of the gas pipe 4 is increased. As a result, even if stress is concentrated on the lower end side of the plug body 2, particularly the lower end of the gas pipe 4, the high strength suppresses the deformation (bending) of the gas pipe, the generation of cracks, and the dropout due to the progress of cracks.

In the plug 1 of this embodiment, the lower end of the gas pipe 4 is welded on the lower surface side of the disk 34 over the entire circumference. According to this configuration, the welded portion (welded length) becomes long, and the gas pipe 4 is firmly welded and fixed to the disk 34. Further, by welding the lower end portion of the gas pipe 4 to groove welding, the gas pipe 4 is firmly welded and fixed by the disk 34. That is, the deformation (bending) of the gas pipe 4, the generation of cracks, and the dropout due to the growth of cracks can be further suppressed.

In the plug 1 of this embodiment, the thickened portion 41 of the gas pipe 4 is formed to have a length equal to or larger than the thickness of the disk 34. In other words, the thickened portion 41 of the gas pipe 4 is formed so as to protrude from the disk 34 by a predetermined length. According to this configuration, the boundary between the thickened portion 41 and the other portion is above the upper surface of the disk 34. With this configuration, even if stress is concentrated on the lower end of the gas pipe 4, the high strength suppresses the deformation (bending) of the gas pipe, the generation of cracks, and the dropout due to the progress of cracks.

[Embodiment 2]
The plug 1 of this embodiment has a plug main body 2, a base 3, and a gas pipe 6 as shown in a cross section in FIG. The plug 1 of this embodiment is the same as the first embodiment described above, except that the configuration of the gas pipe 6 is different. The configuration not particularly mentioned in this embodiment is the same as that of the first embodiment described above.
The gas pipe 6 of the plug 1 of the present embodiment has a thin pipe 61 and a thick pipe 62.
The thin tube 61 corresponds to a tube main body and is composed of a metal tube arranged so as to penetrate the plug main body 2. The upper end of the thin tube 61 opens at the upper surface 21 of the plug body 2, and the lower end communicates with the gas chamber 31.

The outer diameter and inner diameter of the thin tube 61 are not limited as long as they have a shape (thickness) that can be inserted into the thick tube 62, but the outer diameter is 3 to 7 mm and the inner diameter is 1 to 3 mm. Is preferable.

The thin tube 61 has an alumina coating layer (not shown) having a thickness of 2 mm or more on the outer peripheral surface thereof. In the portion of the thin tube 61 protruding from the thick tube 62, the alumina coating layer (not shown) functions as a heat insulating material, an adhesive material, and a filler. As shown in FIG. 6, the thin tube 61 is integrally fixed to the thick tube 62 on the lower surface of the disk 34 by welding over the entire outer circumference in a state where the lower end penetrates the disk 34.

The thick tube 62 is made of a metal tube coaxially arranged with the thin tube 61. The thick pipe 62 is fixed by welding (groove welding) on the lower surface of the disk 34 over the entire circumference of the disk 34 with the upper end embedded in the plug body 2 and the lower end communicating with the gas chamber 31.

The inner diameter and outer diameter of the thick pipe 62 are not limited as long as the thin pipe 61 can be inserted into the inside, but the outer diameter is 11 to 18 mm and the inner diameter is 3 to 7 mm. Is preferable. In this embodiment, a pipe as a thick pipe 62 made of stainless steel having an outer diameter of 13 mm and an inner diameter of 3.6 mm and a pipe as a thin pipe 61 made of stainless steel having an outer diameter of 3.5 mm and an inner diameter of 1.5 mm are combined. It is formed.

The length of the thick pipe 62 is not limited as long as the upper end is embedded in the plug body 2. Preferably, even if the upper surface 21 of the plug body 2 comes into contact with the molten metal and wears, the upper end is not exposed. More preferably, the length is 20% or less with respect to the length of the thin tube 61. More preferably, the length from the lower surface of the disk 34 is 25 to 100 mm. If the length from the lower surface of the disk 34 is too short, the effect of providing the thick tube 62 becomes difficult to be exhibited.

(Action and effect of this form)
The plug 1 of this embodiment can be used by being assembled in an electric furnace in the same manner as in the first embodiment.
The plug 1 of this embodiment has a configuration in which a thin tube 61 and a thick tube 62 in which the gas pipe 6 is coaxially arranged are provided. A thick pipe 62, which is thicker than the thin pipe 61, forms a reinforcing portion. Due to this reinforcing portion (thick pipe 62), the strength of the lower end portion of the gas pipe 6 is increased. As a result, even if stress tries to concentrate on the lower end side of the plug body 2, especially the lower end of the gas pipe 6, the gas pipe 6 (particularly the thin pipe 61) is deformed (bent), cracks occur, and cracks grow due to the high strength. The dropout due to is suppressed.

The plug 1 of this embodiment has a configuration in which the thick tube 62 does not penetrate the plug body 2. According to this configuration, the above effect can be more reliably exhibited. When the thick tube 62 penetrates the plug body 2, molten metal enters the gap between the thick tube 62 and the thin tube 61, and the thin tube 61 melts. That is, substantially only the thick pipe 62 is configured.

In the plug 1 of this embodiment, the inner diameter of the thick tube 62 is 0.1 mm or more of the outer diameter of the thin tube 61. By forming a predetermined gap between the inner peripheral surface of the thick pipe 62 and the outer peripheral surface of the thin pipe 61, the stress applied to the lower end of the thin pipe 61 can be suppressed. Specifically, since there is a gap between the thick pipe 62 and the thin pipe 61, even if a lateral (diameter) force is applied to the thick pipe 62 or the thin pipe 61, this force is applied to the welded portion at the lower end. It is not transmitted. When the inner peripheral surface of the thick pipe 62 and the outer peripheral surface of the thin pipe 61 are in close contact with each other (the gap is zero mm), the gas pipe 6 becomes substantially one gas pipe 6 and the above effect is exhibited. It becomes difficult.

1: Gas blowing plug 2: Plug body 3: Base 31: Gas chamber 4, 6: Gas pipe 41: Thickened part 5: Electric furnace 51: Iron skin 52: Permanent brick 53: Furnace bottom brick 54: Stamp material 55: Seating block 61: Thin tube 62: Thick tube

Claims (8)

Refractory plug body and
A metal base forming a gas chamber provided below the plug body and
A metal gas pipe that is arranged through the plug body and has a lower end that communicates with the gas chamber.
It is a gas blowing plug with
The gas pipe is a gas blowing plug having a reinforcing portion at the lower end thereof to be joined to the base portion. The gas blowing plug according to claim 1, wherein the reinforcing portion is a portion in which the gas pipe is thickened. The base has a metal plate that partitions the upper surface of the gas chamber.
The gas blowing plug according to claim 2, wherein the lower end of the gas pipe is welded over the entire circumference on the lower surface side of the metal plate. Any one of claims 2 to 3 in which the thickness of the thickened portion of the gas pipe is formed to be 1.5 times or more the thickness of the thickened portion of the gas pipe. The gas blowing plug described in the section. The gas pipe
The main body of the tube, which consists of thin tubes,
The gas blowing plug according to claim 1, further comprising the reinforcing portion made of a thick metal pipe integrally provided at the base portion so that the pipe main body portion is located in the hollow portion of the axis thereof. The gas blowing plug according to claim 5, wherein the thick tube does not penetrate the plug body. The gas blowing plug according to any one of claims 5 to 6, wherein the inner diameter of the thick pipe is 0.1 mm or more larger than the outer diameter of the thin pipe. The gas blowing plug according to any one of claims 1 to 7, which is used for a furnace used by tilting.

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