Upper-nozzle / upper-plate integrated object

Abstract

Provided is an upper-nozzle / upper-plate integrated object capable of suppressing adhesion of alumina in a lower part of an upper nozzle having the largest adhesion of the alumina in molten steel. An upper-nozzle / upper-plate integrated object (1) used for a sliding gate comprises gas blowing parts (21, 22) at two locations. One gas blowing part (21) can blow gas to at least an upper part of an upper nozzle (1-1), and the other gas blowing part (22) can simultaneously blow the gas to a lower part of the upper nozzle (1-1) and a sliding surface of an upper plate (1-2).

Description

Upper nozzle and upper plate integrated

[0001] The present invention relates to an upper nozzle and upper plate unit used in a sliding gate.

[0002] A sliding gate (also called a sliding nozzle) is located at the bottom of the tundish to regulate the flow of molten steel. The sliding gate comprises an upper nozzle, an upper plate, a lower plate, and an SEN. When performing continuous casting for long periods of time, the SEN must be replaced frequently during continuous casting. In this case, the upper nozzle and upper plate are integrated into one unit, and the lower plate and SEN are integrated into one unit. The lower plate and SEN slide relative to the upper nozzle and upper plate to control the flow of molten steel and enable quick replacement of the SEN. Even when continuous casting is not performed for long periods of time, the upper nozzle and upper plate are still integrated into one unit.

[0003] In a conventional upper nozzle-and-plate assembly, a gas such as an inert gas is blown into the upper nozzle to prevent alumina from adhering to the inner surface of the hole in the upper nozzle. Furthermore, a gas such as an inert gas is blown into the sliding surface of the upper plate to prevent the molten steel from entraining air (see Patent Document 1). To blow gas into the upper nozzle and onto the sliding surface of the upper plate, the upper nozzle-and-plate assembly is provided with two gas blowing sections, one of which blows gas into the upper nozzle and the other gas blowing section blows gas onto the sliding surface of the upper plate.

[0004] U.S. Pat. No. 5,431,374

[0005] However, in the upper nozzle-upper plate integrated structure, since there is only one gas injection port for injecting gas into the upper nozzle, there is a problem that alumina in molten steel is particularly likely to adhere to the lower part of the upper nozzle. If alumina clogging occurs in the lower part of the upper nozzle, problems such as the need to suspend operations, shortening the casting cycle and requiring replacement of the tundish, and further increasing the frequency of replacement of refractories such as the submerged entry nozzle occur.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an upper nozzle upper plate unit that can suppress alumina deposition in the lower part of the upper nozzle, where alumina deposition in molten steel is greatest.

[0007] In order to solve the above problems, one aspect of the present invention is an upper nozzle and upper plate integrated unit used in a sliding gate, which has two gas blowing sections, one of which is capable of blowing gas into at least the upper part of the upper nozzle, and the other of which is capable of blowing gas into the lower part of the upper nozzle and the sliding surface of the upper plate simultaneously.

[0008] According to the present invention, the other of the two gas injection sections can simultaneously inject gas into the lower part of the upper nozzle and the sliding surface of the upper plate. Therefore, when the grooves on the sliding surface of the upper plate are filled with gas, the gas is supplied preferentially to the lower part of the upper nozzle. A gas film can be stably formed on the lower part of the upper nozzle, preventing alumina from adhering to the lower part of the upper nozzle. This results in a longer casting cycle, less frequent replacement of the tundish, and less replacement of refractories such as the submerged entry nozzle, resulting in improved economic benefits.

[0009] Fig. 1 is a vertical cross-sectional view of a sliding gate using an upper nozzle-upper plate integrated unit according to one embodiment of the present invention; Fig. 2 is a vertical cross-sectional view of one gas blowing portion of the upper nozzle-upper plate integrated unit according to this embodiment; Fig. 3 is a vertical cross-sectional view of the other gas blowing portion of the upper nozzle-upper plate integrated unit according to this embodiment; Fig. 4 is a plan view of the upper nozzle-upper plate integrated unit according to this embodiment.

[0010] Hereinafter, an upper nozzle-top plate integrated unit according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the upper nozzle-top plate integrated unit according to the present invention can be embodied in various forms and is not limited to the embodiments described herein. The present embodiment is provided with the intention that those skilled in the art will be able to fully understand the invention by fully disclosing the specification.

[0011] As shown in FIG. 1 , the upper nozzle-upper plate integral body 1 of this embodiment constitutes a part of the sliding gate 3. The tundish 4 holds molten steel. The sliding gate 3 controls the outflow of molten steel from the tundish 4. The sliding gate 3 comprises the upper nozzle-upper plate integral body 1 and the lower plate-submerged entry nozzle integral body 2. The lower plate-submerged entry nozzle integral body 2 slides horizontally relative to the upper nozzle-upper plate integral body 1 by a machine (not shown). The flow rate of the molten steel depends on the degree of overlap between the hole 1 a of the upper nozzle-upper plate integral body 1 and the hole 2 a of the lower plate-submerged entry nozzle integral body 2.

[0012] The upper nozzle-top plate unit 1 is inserted into the openings in the mounting plate 5 and the bottom wall 6 of the tundish 4. The upper nozzle-top plate unit 1 is surrounded by a refractory material 7 such as a ramming material.

[0013] The lower plate and submerged entry nozzle assembly 2 comprises a lower plate 2-1 and a submerged entry nozzle 2-2. The lower plate 2-1 and the submerged entry nozzle 2-2 are integrally molded by CIP molding or the like to enable quick replacement. Alternatively, the lower plate 2-1 and the submerged entry nozzle 2-2 may be molded separately and then integrated with mortar, a steel shell, or the like. A lower nozzle (not shown) may also be interposed between the lower plate 2-1 and the submerged entry nozzle 2-2.

[0014] As shown in FIG. 2 , the upper nozzle-upper plate assembly 1 includes an upper plate 1-2 and an upper nozzle 1-1 fixed to a recess 28b of the upper plate 1-2. The upper nozzle 1-1 includes an upper porous refractory 11, a middle refractory 12, and a lower porous refractory 13. The upper porous refractory 11 and the lower porous refractory 13 are configured to be permeable to gases such as argon gas. The porosity of the upper porous refractory 11 and the lower porous refractory 13 is, for example, 20 to 25%, which is greater than the porosity of the middle refractory 12. The materials for these refractories 11, 12, and 13 are not particularly limited, and may be alumina-based refractory materials, zirconia-based refractory materials, magnesia-based refractory materials, or the like.

[0015] The hole 1a of the upper nozzle 1-1 has a receiving end 1a1 disposed on the floor of the tundish 4 and a discharge end 1a2 disposed concentrically with the upper plate 1-2. A cylindrical shoulder 14 protruding downward is formed around the periphery of the discharge end 1a2.

[0016] A ring-shaped groove 15 (hereinafter referred to as a gas pool portion 15) extending in the circumferential direction is formed on the outer surface of the upper porous refractory 11. Vertical grooves 16 connected to the gas pool portion 15 are formed on the outer surfaces of the upper porous refractory 11, the middle refractory 12, and the lower porous refractory 13. The vertical grooves 16 are coated with a sealing material so that gas can be guided to the gas pool portion 15.

[0017] The upper porous refractory 11, the middle refractory 12, and the lower porous refractory 13 are covered with a cylindrical wall 17 (hereinafter referred to as the shell 17) made of steel or the like. The upper part of the shell 17 surrounds the upper part of the upper porous refractory 11 and is sealably fixed to the upper part of the upper porous refractory 11 with a heat-resistant sealing material such as mortar. The lower part of the shell 17 surrounds the lower part of the lower porous refractory 13 and is sealably fixed to the lower part of the lower porous refractory 13 with a heat-resistant sealing material such as mortar. This allows the gas that passes through the vertical grooves 16 and fills the gas pool portion 15 to be trapped.

[0018] 4, the upper nozzle-upper plate assembly 1 is provided with two gas blowing sections 21 and 22. The gas blowing sections 21 and 22 are connected to a gas supply source such as an argon gas cylinder (not shown) via a valve (not shown).

[0019] 2, one gas blowing section 21 includes a gas blowing pipe 23 fixed to the iron shell 17 and the vertical groove 16. The gas blowing pipe 23 is connected to the vertical groove 16.

[0020] As shown in Figure 3, the other gas blowing section 22 includes a gas blowing pipe 24 penetrating the steel shell 17, a slit 25 formed in the lower porous refractory 13, and a vertical hole 26 formed in the upper plate 1-2. The gas blowing pipe 24 has a T-shaped branch portion 24a inside the lower porous refractory 13. The branch portion 24a is housed in a recess 13a in the lower porous refractory 13. The recess 13a is sealed with mortar or the like. A main pipe 24a1 of the branch portion 24a is connected to the slit 25. A branch pipe 24a2 of the branch portion 24a is connected to the vertical hole 26. The vertical hole 26 is connected to a ring-shaped groove 27 in the sliding surface of the upper plate 1-2.

[0021] As shown in FIG. 4, the upper plate 1-2 has a rectangular shape in a plan view. As shown in FIG. 3, the upper plate 1-2 includes a dense refractory material 28 that does not have pores. The refractory material 28 has a hole 28a in its center that connects to the hole 1a of the upper nozzle 1-1. A recess 28b is formed in the upper surface of the refractory material 28. The recess 28b has a shape complementary to the cylindrical shoulder 14 of the upper nozzle 1-1. The cylindrical shoulder 14 of the upper nozzle 1-1 is fixed to the recess 28b with mortar or the like. The above-mentioned ring-shaped groove 27 is formed in the lower surface of the refractory material 28. The material of the refractory material 28 is not particularly limited, and an alumina-based refractory material, a zirconia-based refractory material, a magnesia-based refractory material, or the like can be used.

[0022] The top and side surfaces of the refractory material 28 are covered with a cylindrical wall 29 (hereinafter referred to as the shell 29) made of steel or the like. The shell 29 is fixed to the refractory material 28 with mortar or the like. An opening for receiving the upper nozzle 1-1 is formed in the shell 29. The periphery 29a of the opening is bent so that the shell 17 of the upper nozzle 1-1 can fit into it, and is welded to the shell 17 of the upper nozzle 1-1.

[0023] 2 , when gas with adjusted pressure and flow rate is supplied to the gas injection section 21, the gas passes through the gas injection pipe 23 and the vertical grooves 16 to fill the gas pool section 15, and then the gas penetrates the wall of the upper porous refractory 11. As a result, a gas film is formed on the inner surface of the holes 1 a of the upper porous refractory 11. This gas film prevents the molten steel from coming into direct contact with the inner surface of the holes 1 a of the upper porous refractory 11, thereby preventing alumina from adhering to the upper porous refractory 11.

[0024] 3 , when gas whose pressure and flow rate are adjusted by a valve is supplied to the gas blowing section 22, the gas passes through the main pipe 24a1 of the branched section 24a of the gas blowing pipe 24, fills the slits 25, and then penetrates the wall of the lower porous refractory 13. As a result, a gas film is formed on the inner surface of the holes 1a of the lower porous refractory 13. This gas film prevents the molten steel from coming into direct contact with the inner surface of the holes 1a of the lower porous refractory 13, thereby preventing alumina from adhering to the lower porous refractory 13.

[0025] 3, gas passes through the branch pipe 24a2 of the branch portion 24a and the vertical hole 26 to fill the groove 27 on the sliding surface of the upper plate 1-2. Filling the groove 27 with gas prevents the molten steel from drawing in air from the outside through the gap between the sliding surface of the upper plate 1-2 and the sliding surface of the lower plate 2-1.

[0026] When the grooves 27 on the sliding surface of the upper plate 1-2 are filled with gas, the gas is supplied preferentially to the lower porous refractory 13 of the upper nozzle 1-1. As a result, a gas film can be stably formed on the inner surface of the hole 1a of the lower porous refractory 13.

[0027] The effects of the upper nozzle and upper plate integral assembly of this embodiment will be described below.

[0028] Since the gas blowing section 22 has a branch section 24a inside the lower porous refractory 13, the upper nozzle-upper plate integrated unit 1 can be made compact, and the upper nozzle-upper plate integrated unit 1 can be easily installed in a sliding gate machine.

[0029] Because the upper nozzle 1-1 includes an upper porous refractory 11, a middle refractory 12, and a lower porous refractory 13, gas can be efficiently supplied to the upper porous refractory 11 and the lower porous refractory 13. When starting casting, a stopper head may be pressed against the top of the upper nozzle 1-1 to prevent molten steel from flowing. In this case, alumina is likely to adhere to the top of the upper nozzle 1-1. Also, during casting, the hole in the upper plate of the upper nozzle and the hole in the submerged entry nozzle of the lower plate may be misaligned to perform throttle injection. In this case, stagnation occurs, and alumina is likely to adhere to the bottom of the upper nozzle 1-1. By efficiently supplying gas to the upper porous refractory 11 and the lower porous refractory 13, alumina adhesion can be suppressed even in such cases.

[0030] Since the gas blowing section 22 is connected to the ring-shaped slit 25 formed in the lower porous refractory 13, a gas film can be stably formed on the inner surface of the hole 1a of the lower porous refractory 13.

[0031] The upper nozzle and upper plate integral assembly of the present invention is not limited to being embodied in the above-described embodiment, but can be embodied in other embodiments without departing from the spirit of the present invention.

[0032] In the above embodiment, the upper nozzle is made of three layers of porous refractory material, but it may be made of a single layer of porous refractory material. Furthermore, in the above embodiment, one gas blowing section blows gas into the upper part of the upper nozzle, but one gas blowing section may blow gas into the upper and middle parts of the upper nozzle. Furthermore, in the above embodiment, a slit is formed inside the lower porous refractory material, but a gas pool section may be formed on the outer surface of the lower porous refractory material.

[0033] In the above embodiment, the upper nozzle and the upper plate are joined by mortar and steel shell, but they may be integrally formed by CIP molding or the like.

[0034] The upper plate may incorporate zirconia inserts to prevent refractory wear.

[0035] This specification is based on Japanese Patent Application No. 2023-106612, filed on June 29, 2023, the entire contents of which are incorporated herein by reference.

[0036] DESCRIPTION OF SYMBOLS 1...Upper nozzle and upper plate integrated body 1-1...Upper nozzle 1-2...Upper plate 3...Sliding gate 11...Upper porous refractory (upper part of upper nozzle) 12...Middle refractory 13...Lower porous refractory (lower part of upper nozzle) 21...One gas blowing section 22...Other gas blowing section 24a...Branch section 25...Slit

Claims

1. An upper nozzle and upper plate integral assembly used in a sliding gate, having two gas blowing sections, one of which is capable of blowing gas into at least the upper part of the upper nozzle, and the other of which is capable of blowing gas into the lower part of the upper nozzle and the sliding surface of the upper plate simultaneously.

2. The upper nozzle and upper plate integral assembly according to claim 1, characterized in that the other gas blowing section has a branching section inside the upper nozzle.

3. The upper nozzle upper plate integral assembly described in claim 1 or 2, characterized in that the upper nozzle comprises an upper porous refractory, a middle refractory and a lower porous refractory, one of the gas blowing sections is capable of blowing gas into the upper porous refractory, and the other gas blowing section is capable of blowing gas into the lower porous refractory.

4. An upper nozzle and upper plate integral assembly as described in claim 3, characterized in that the other gas blowing portion is connected to a ring-shaped slit formed in the lower porous refractory material.

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