JP4011249B2 - Immersion tube for vacuum degassing furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dip tube for a vacuum degassing furnace.
[0002]
[Prior art]
The dip tube of the vacuum degassing furnace has a cylindrical cored bar, an inner cylindrical part that is formed by building a refractory inside the cored bar and forms a molten metal passage, and is integrated with the outer and lower ends of the cored bar. And an outer cylinder part formed by solidification of an irregular refractory material covering.
[0003]
An example of a vacuum degassing furnace will be described with reference to FIG. That is, the vacuum degassing furnace includes a chamber 102 having a decompression chamber 101 having an exhaust passage 100 formed therein, and a pair of two dip tubes 200 arranged in parallel at the lower end of the chamber 102. Yes. The lower part of the dip tube 200 is immersed in the molten metal 300 of the ladle 350. One of the two dip tubes 200 forms a rising passage 201 for raising the molten metal, and the other of the two dip tubes 200 forms a lower passage 251 for lowering the molten metal.
[0004]
In the degassing process, the inside of the decompression chamber 101 is decompressed by the exhaust passage 100, and the molten metal 300 in the ladle 200 is transferred in the order of the ascending passage 201 → the decompression chamber 101 → the descending passage 251. By repeating this transfer, the molten metal 300 in the ladle 350 is degassed to improve the quality.
[0005]
By the way, when using the dip tube, the cored bar, which is a constituent element of the dip tube, is thermally expanded, so that the outer cylinder portion often cracks when the service period is extended. In order to prevent cracking, it is preferable to form a gap between the outer surface of the cored bar and the inner surface of the outer cylinder part. This is because the thermal expansion of the cored bar is absorbed by the gap. In order to form a gap, it is conceivable that paper or corrugated cardboard, which is a burned-out substance, is attached to a core metal and burned off by heat.
[0006]
When the gap is formed as described above, the thermal expansion absorbability of the cored bar can be secured. However, on the other hand, since the bondability between the outer cylinder part and the core metal is lowered, there is a high possibility that the outer cylinder part falls off the core metal when the service period is extended.
[0007]
Furthermore, it is not easy to attach paper or cardboard that is two-dimensional and has a large exposed area to the core metal with high accuracy. A V-shaped stud that mechanically engages the outer tube made of irregular refractory may be fixed to the cored bar. In this case, the stud interferes with the paper or cardboard. There was a case.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a dip tube for a vacuum degassing furnace that can easily prevent the outer cylinder from falling off and can easily form a gap.
[0009]
[Means for Solving the Problems]
The dip tube of the vacuum degassing furnace according to the present invention includes a cylindrical cored bar, an inner cylindrical part made of a regular refractory that is built inside the cored bar and forms a molten metal passage, and the outer and lower ends of the cored bar. In the dip tube of the vacuum degassing furnace having an outer cylindrical portion formed by solidifying an amorphous refractory that integrally covers the inner surface, and forming a gap between the outer surface of the core metal and the inner surface of the outer cylindrical portion,
When the irregular refractory has fluidity, it is characterized in that a long rope or long rope having the property of impregnating the irregular refractory is wound around a core metal and a gap is formed by burning the rope or rope. is there.
[0010]
According to the dip tube according to the present invention, a rope or a rope is wound around a metal core to form a gap. The rope or rope can function as an elongated body that is flexible and burnable. Since ropes and ropes can be regarded as substantially one-dimensional compared to two-dimensional paper or cardboard, the work of winding around a core metal becomes easy. Further, as described above, the rope and the rope can be regarded as substantially one-dimensional and have flexibility. Therefore, the V-shaped stud that mechanically engages the outer cylindrical portion made of an irregular refractory is a cored bar. Even if it is fixed to the cable, it is easy to wind the rope or rope while avoiding the stud.
[0011]
When the amorphous refractory is fluid, the rope or rope has the property of being able to impregnate the fine powder portion of the fluid refractory. That is, the fine powder portion of the irregular refractory can soak into the gap of the rope or rope. For this reason, if the rope or rope wound around the core metal burns out, the impregnated and solidified portion of the amorphous refractory impregnated and solidified in the rope or rope remains in the gap. When the impregnated and solidified portion remains in this manner, the engagement between the irregular refractory and the cored bar is improved and the outer cylinder portion is prevented from falling off compared to the case where the gap is a simple space. The
[0012]
DETAILED DESCRIPTION OF THE INVENTION
According to the dip tube according to the present invention, the cored bar has a cylindrical shape. The cored bar may be formed by bending one or a plurality of plate bodies into a cylindrical shape, or may be formed by cutting a large diameter steel pipe into a cylindrical shape.
[0013]
The inner cylinder part is formed by constructing a regular refractory inside the cored bar, and a molten metal passage is formed by the inner surface of the regular refractory. The outer cylinder part is formed by solidification of the amorphous refractory which integrally covers the outer side and the lower end of the metal core.
[0014]
When the irregular refractory has fluidity, use a long rope or long rope (long body with flexibility) that has the property of impregnating the irregular refractory with fluidity. It is wound around. If the rope or rope wound around the core metal burns away, a gap is formed in the burned trace, and the impregnated and solidified refractory portion remains in the gap. The remaining portion (residual portion) is easier to contact and engage with the core than in the case of a mere gap, and thus contributes to suppression of the outer cylinder portion from falling off.
[0015]
The material of the rope or rope can be formed using organic fiber, chemical fiber, or the like. As the rope, a rice rope, a hemp rope, a nylon rope or the like can be used. The diameter of the rope or rope is not particularly limited, and can be 5 to 20 mm, for example. When the lengths of ropes and ropes are insufficient, a plurality of ropes and ropes can be joined using an adhesive, a connector, or the like.
[0016]
【Example】
An embodiment of a dip tube of a vacuum degassing furnace according to the present invention will be described with reference to the drawings.
[0017]
As shown in FIG. 2, the dip tube has a ring-shaped flange portion 1 and a cylindrical cored bar 2 extending downward from the flange portion 1 (thickness: about 9 to 16 mm, diameter: about 600 to 1100 mm). Solidification of the inner cylinder part 3 formed by constructing the substantially refractory 30 in a substantially cylindrical shape inside the cored bar 2 and the amorphous refractory 50 integrally covering the outer side and the lower end surface of the cored bar 2 And an outer cylinder portion 5 having a cylindrical shape formed by the above.
[0018]
The core metal 2 is formed in a cylindrical shape by a metal plate made of carbon steel. A mounting plate 20 is welded to the lower end portion of the core metal 2 to receive the fixed refractory 30. A plurality of V-shaped studs 23 are fixed to the outer peripheral surface of the core metal 2 by welding.
[0019]
A molten metal passage 32 extending in the vertical direction through which a high-temperature molten metal passes is formed by the inner peripheral surface 31 of the inner cylinder portion 3. The fixed refractory 30 that forms the inner cylinder portion 3 is made of a brick of MgO—Cr ₂ O ₃ quality.
[0020]
An irregular refractory 50 constituting the outer cylinder portion 5 is mechanically engaged with the stud 23. For this reason, even if the use period of the dip tube is prolonged and a crack occurs in the outer cylinder part 5, the stud 23 suppresses the outer cylinder part 5 formed by solidifying the amorphous refractory 50.
[0021]
The amorphous refractory 50 is made of high alumina and is formed by kneading a refractory granular material, a hydraulic cement, and water, and thus has fluidity before solidification. Since the solid amorphous refractory 50 is mechanically engaged with the stud 23 as described above, even if the outer cylinder part 5 is cracked, the outer cylinder part 5 is prevented from falling off.
[0022]
In this embodiment, when manufacturing the above-described dip tube, a long rope 7 (see FIG. 3) formed by twisting continuous organic fibers is used as a continuous long body. The rope 7 is wound around the outer peripheral surface of the core metal 2 to form a wound body 70. The rope 7 is wound substantially coaxially with respect to the central axis of the core metal 2 so that the wound body 70 forms a gap outside the core metal 2. The rope 7 can be packed tightly on the outer peripheral surface of the cored bar 2. As the rope 7, a rice rope is used. The diameter of one rope 7 is about 5 to 20 mm, but is not limited to this. In general, since the diameter size of the rope 7 is larger than the thickness of the paper, it is advantageous to increase the gap width of the gap formed by the burnout marks of the rope 7, and therefore absorbs the thermal expansion of the cored bar 2. It is advantageous to ensure the property. Further, the inner peripheral side of the cored bar 2 is covered with a burnable covering 8 that forms a gap inside the cored bar 2. The covering 8 is made of corrugated paper.
[0023]
When manufacturing the dip tube, as described above, the winding body 70 is packed around the outer peripheral surface of the core metal 2 and wound, and the inner peripheral surface of the core metal 2 is covered with the covering 8 and the fluidity is maintained. An indeterminate refractory 50 having a fluidity, that is, a castable material having fluidity, is poured, and the outer periphery of the wound body 70 and the inner periphery of the covering 8 are covered by the indeterminate refractory 50 having fluidity. Before the amorphous refractory 50 is solidified, the amorphous refractory 50 has fluidity. For this reason, the irregular refractory 50 having fluidity can be partially impregnated inside the rope 7 of the wound body 70. That is, when the castable layer 50a, which is the amorphous refractory 50, has fluidity, the fine powder portion constituting the castable layer 50a is easily impregnated inside the rope 7.
[0024]
The rope 7 and the covering 8 constituting the wound body 70 are burned out by a heating operation for heating the dip tube or heat when the dip tube is used. That is, burnt residue of the rope 7 is formed between the outer peripheral surface of the cored bar 2 and the inner peripheral surface of the outer cylinder part 5 due to burnt traces of the rope 7 and having pores with a gap. Similarly, due to burnout of the covering 8, a gap or a burnt residue with a gap is formed between the portion 50 c of the irregular refractory inside the core 2 and the inner peripheral surface of the core 2. . Since these gaps or burned residue with gaps have a buffer function, they can function to absorb thermal expansion and contraction of the core metal 2 and suppress cracks in the outer cylinder portion 5.
[0025]
If the rope 7 wound around the core metal 2 is burned out, the irregular refractory portion impregnated and solidified in the rope 7 remains in the gap. That is, as shown in FIG. 6, the mixed layer 53 of the burned residue of the rope 7 and the solidified portion of the castable fine powder soaked in the rope 7 is between the metal core 2 and the amorphous refractory 50 (castable layer 50a). Will remain. The mixed layer 53 is easier to engage with the outer peripheral surface of the cored bar 2 and the stud 23 than with a simple space. Therefore, the mixed layer 53 can suppress dropping of the outer cylinder portion 5 (the irregular refractory 50) while ensuring the absorbability against the thermal expansion of the cored bar 2.
[0026]
In the case of conventionally used paper, corrugated cardboard, and the like, impregnation of the irregular refractory portion cannot be substantially obtained, so that sufficient engagement cannot be obtained.
[0027]
In the present embodiment, the rope 7 is wound around the outer peripheral surface of the cored bar 2. The rope 7 is not only flexible, but can be regarded as substantially one-dimensional compared to two-dimensional paper and cardboard. Therefore, the operation of winding the rope 7 around the outer peripheral surface of the cored bar 2 is not necessary. It becomes easy. Even when a plurality of V-shaped studs 23 that are mechanically engaged with the outer cylindrical portion 5 formed of the irregular refractory 50 are fixed to the core metal 2, the positions of the studs 23 can be changed. The operation | work which winds the rope 7 around the outer peripheral surface of the cored bar 2 avoiding becomes easy.
[0028]
Incidentally, when winding the rope 7 around the outer peripheral surface of the cored bar 2, as shown in FIG.
[0029]
The dip tube according to the present embodiment can be used in vacuum degassing as shown in FIG.
[0030]
In addition, the present invention is not limited only to the embodiment described above and shown in the drawings. For example, instead of a rope, a rope formed of a chemical fiber may be wound around a core metal and necessary. It can be implemented with appropriate changes depending on the situation.
[0031]
(Supplementary note) The following technical idea can be grasped from the above description.
[0032]
・ By solidification of a cylindrical cored bar, an inner cylindrical part made of a fixed refractory that is built inside the cored bar and forms a molten metal passage, and an amorphous refractory that covers the outer and lower end surfaces of the cored bar integrally. In the method of manufacturing a dip tube of a vacuum degassing furnace having a formed outer tube portion and forming a gap between the outer surface of the core metal and the inner surface of the outer tube portion,
When the amorphous refractory has fluidity, a long rope or a long rope that can be impregnated with the irregular refractory is wound around the core metal,
Thereafter, a flowable amorphous refractory is poured into at least the outside of the core bar to solidify the amorphous refractory, and a method for producing a dip tube for a vacuum degassing furnace.
[0033]
According to this manufacturing method, the flowable amorphous refractory can be impregnated into the rope or rope, so that the outer cylinder portion formed of the amorphous refractory is prevented from falling off, and the work for forming a gap is performed. Becomes easy.
[0034]
・ By solidification of a cylindrical cored bar, an inner cylindrical part made of a fixed refractory that is built inside the cored bar and forms a molten metal passage, and an amorphous refractory that covers the outer and lower ends of the cored bar integrally. In the dip tube of the vacuum degassing furnace having the formed outer cylinder part and forming a gap between the outer surface of the core metal and the inner surface of the outer cylinder part,
A long flexible and burnable long body that has the property of impregnating an irregular refractory when the amorphous refractory has fluidity is wound around a cored bar, and a gap is formed by burning the long body. A dip tube for a vacuum degassing furnace.
[0035]
・ By solidification of a cylindrical cored bar, an inner cylindrical part made of a fixed refractory that is built inside the cored bar and forms a molten metal passage, and an amorphous refractory that covers the outer and lower ends of the cored bar integrally. In the dip tube of the vacuum degassing furnace having the formed outer cylinder part and forming a gap between the outer surface of the core metal and the inner surface of the outer cylinder part,
It is characterized in that a mixed layer of burnt residue formed with burnt pieces of rope or rope with gaps and the irregular refractory impregnated therein remains between the cored bar and the outer cylinder part. Vacuum degassing furnace.
[0036]
【The invention's effect】
According to the dip tube of the vacuum degassing furnace according to the present invention, it is possible to suppress dropping of the outer cylindrical portion formed by solidifying the amorphous refractory. Furthermore, since the rope or rope can be regarded as one-dimensional as well as flexible, the winding work is facilitated, thereby facilitating the work for forming a thick gap. Since a thick gap can be formed in this way, the occurrence of cracks in the amorphous refractory is reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a vacuum degassing furnace equipped with a dip tube.
FIG. 2 is a cross-sectional view of a dip tube.
FIG. 3 is a side view schematically showing a rope.
FIG. 4 is an enlarged cross-sectional view of the main part of the dip tube.
FIG. 5 is a configuration diagram showing a form in which a rope is wound.
FIG. 6 is a configuration diagram showing a cross section of the main part in the vicinity of the cored bar and the irregular refractory.
[Explanation of symbols]
In the figure, 2 is a metal core, 3 is an inner cylinder part, 30 is a regular refractory, 5 is an outer cylinder part, 50 is an irregular refractory, 7 is a rope, and 70 is a wound body.

Claims (1)

Solidification of a cylindrical cored bar, an inner cylindrical part made of a fixed refractory built inside the cored bar and forming a molten metal passage, and an amorphous refractory integrally covering the outer and lower ends of the cored bar In the dip tube of the vacuum degassing furnace having the outer cylinder part formed by, and forming a gap between the outer surface of the cored bar and the inner surface of the outer cylinder part,
When the amorphous refractory has fluidity, a long rope or long rope having a property capable of impregnating the amorphous refractory is wound around the core metal, and the gap is formed by burning the rope or rope. A dip tube for a vacuum degassing furnace.

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