Gas blowing nozzle and method for manufacturing the same

Abstract

Provided is a gas blowing nozzle capable of preventing a filler, such as mortar, from flowing into a gas pool, thereby ensuring a stable gas quantity. A gas blowing nozzle (1) comprises: a refractory (2) that has a nozzle hole (2a) and has a recess (2b) for forming a gas pool (6) on the outer surface thereof; an inner circumferential metal case (3) that is mounted on the refractory (2) by shrink fitting and that covers the recess (2b) of the refractory (2); an outer circumferential metal case (4) that surrounds the refractory (2) and the inner circumferential metal case (3); and a filler that is used to fill at least the area between the refractory (2) and the outer circumferential metal case (4).

Description

Gas blowing nozzle and its manufacturing method

[0001] The present invention relates to a gas blowing nozzle having a nozzle hole that serves as a flow path for molten metal and capable of blowing an inert gas into the nozzle hole, and a method for manufacturing the same.

[0002] A sliding gate that adjusts the flow rate of molten steel is attached to a ladle or a tundish (see Patent Document 1). Nozzles such as the upper nozzle of the sliding gate have nozzle holes that serve as a flow path for the molten steel. If impurities in the molten steel adhere to and accumulate on the inner wall of the nozzle hole, causing the nozzle hole to become smaller, the flow rate of molten steel decreases, hindering operation. To prevent this, gas-blowing nozzles that can blow inert gas into the nozzle holes are used for the nozzles (see Patent Document 1).

[0003] The gas blowing nozzle comprises a refractory having a nozzle hole and a metal case (also called a shell) surrounding the refractory. A recess is formed on the outer surface of the refractory to form a gas pool. When inert gas is introduced into the gas pool, the inert gas is blown into the nozzle hole through the porous portion of the refractory.

[0004] In conventional gas blowing nozzles, a metal case is provided to prevent gas leakage from the outer periphery of the refractory and to reinforce the strength of the refractory. Mortar is filled between the metal case and the refractory to fill the gap between the metal case and the refractory and prevent gas leakage.

[0005] JP 2011-256079 A

[0006] However, in conventional gas blowing nozzles, mortar may flow into the gas pool, which causes variations in the gas flow rate discharged from the gas pool to the nozzle hole. Furthermore, if the amount of mortar is reduced to prevent the mortar from flowing into the gas pool, the gas leakage prevention capability is reduced, leading to operational problems such as an insufficient amount of inert gas being blown into the molten steel, which is the original purpose, and a decrease in back pressure.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a gas blowing nozzle that can prevent filler material such as mortar from flowing into the gas pool and ensure a stable amount of gas, and a method for manufacturing the same.

[0008] In order to solve the above problems, one aspect of the present invention is a gas blowing nozzle comprising: a refractory having a nozzle hole and a recess for forming a gas pool on its outer surface; an inner metal case attached to the refractory by shrink fitting and covering the recess; an outer metal case surrounding the refractory and the inner metal case; and a filler material filled at least between the refractory and the outer metal case.

[0009] Another aspect of the present invention is a method for manufacturing a gas blowing nozzle, comprising the steps of: attaching an inner metal case to a refractory material having a nozzle hole and a recess for forming a gas pool on its outer surface by shrink fitting; and setting an outer metal case surrounding the refractory material and the inner metal case, and filling a filler material at least between the refractory material and the outer metal case.

[0010] According to the present invention, it is possible to prevent filler materials such as mortar from flowing into the gas pool, thereby ensuring a stable gas flow rate. Furthermore, the inner peripheral metal case attached to the refractory by shrink fitting firmly fixes the refractory and reinforces its strength, thereby preventing mechanical cracking of the refractory or cracking due to thermal shock, and preventing gas leaks caused by cracks in the refractory.

[0011] Fig. 1 is a longitudinal sectional view of a gas blowing nozzle according to an embodiment of the present invention. Fig. 2 is an enlarged view of part A in Fig. 1. Fig. 3 is an enlarged view of part B in Fig. 1. Fig. 4 is a sectional view of a gas pool and a gas introduction path of the gas blowing nozzle according to the embodiment. Fig. 5 is a sectional view of a gas pool and a gas introduction path of a gas blowing nozzle of a comparative example. Fig. 6 is a process chart of a method for manufacturing the gas blowing nozzle according to the embodiment.

[0012] Hereinafter, a gas blowing nozzle and a method for manufacturing the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the gas blowing nozzle and the method for manufacturing the same according to the present invention can be embodied in various forms and are not limited to the embodiments described in this specification. The present embodiment is provided with the intention of enabling those skilled in the art to fully understand the invention by providing sufficient disclosure in the specification.

[0013] Figure 1 shows a longitudinal cross-sectional view of a gas blowing nozzle 1 according to an embodiment of the present invention. The gas blowing nozzle 1 of this embodiment is an upper nozzle of a sliding gate. The gas blowing nozzle 1 of this embodiment comprises a refractory 2 having a nozzle hole 2a, an inner metal case 3, an outer metal case 4, and a filler material 5 such as mortar filled between the outer metal case 4 and the refractory 2 and between the outer metal case 4 and the inner metal case 3 (see Figures 2 and 3). An upper plate of a sliding gate (not shown) is attached to the bottom of the gas blowing nozzle 1.

[0014] The refractory 2 in this embodiment is formed into a cylindrical shape that is long in the vertical direction. The outer surface of the refractory 2 and the nozzle holes 2a are formed so that their upper portions are tapered, widening toward the top. A gas-permeable porous refractory is used as the material for the refractory 2. The shape and material of the refractory are not particularly limited. For example, the material of the refractory may be different for the upper, middle, and lower portions, with a gas-permeable porous refractory being used for the upper and lower portions and a gas-impermeable dense refractory being used for the middle portion.

[0015] The outer surface of the refractory 2 having the nozzle hole 2a is formed with a recess 2b for forming a gas pool 6 and a gas inlet groove 2c connected to the recess 2b. The nozzle hole 2a extends in the axial direction of the refractory 2 and serves as a flow path for molten metal such as molten steel. The recess 2b is provided in the upper part of the outer surface of the refractory 2 and circumferentially surrounds the outer surface of the refractory 2. The gas inlet groove 2c extends vertically from a gas inlet pipe 7 provided at the bottom of the outer metal case 4 to the recess 2b, and introduces an inert gas supplied to the gas inlet pipe 7 into the gas pool 6. The recess 2b and the gas inlet groove 2c may be formed simultaneously with the formation of the refractory 2, or may be machined by grinding or the like after the refractory 2 is fired. A coating agent 8 is applied to the outer surface, the upper surface of the refractory 2, and the gas inlet groove 2c, excluding the recess 2b. In FIG. 1 , the areas to which the coating agent 8 is applied are indicated by dashed and diagonal lines.

[0016] The inner metal case 3 has a substantially cylindrical shape that matches the shape of the refractory 2. The inner metal case 3 is attached to the refractory 2 by shrink fitting. Shrink fitting refers to heating the inner metal case 3, which has a diameter slightly smaller than the refractory 2, to expand it, fitting it to the refractory 2, and then cooling the inner metal case 3 to shrink it and secure it to the refractory 2. By attaching the inner metal case 3 to the refractory 2 by shrink fitting, the inner metal case 3 can be attached to the refractory 2 directly without using a filler material 5 such as mortar. The thickness of the inner metal case 3 is thinner than the thickness of the outer metal case 4. The inner metal case 3 is provided mainly to prevent the filler material 5 such as mortar from flowing into the gas pool 6 and the gas inlet groove 2c, and to facilitate shrink fitting.

[0017] The recess 2b and the gas inlet groove 2c of the refractory 2 are covered by an inner metal case 3. A gas pool 6 is formed by covering the recess 2b with the inner metal case 3. A gas inlet path 9 is formed by covering the gas inlet groove 2c with the inner metal case 3.

[0018] The refractory 2 and the inner metal case 3 are surrounded by a substantially cylindrical outer metal case 4. The outer metal case 4 is provided for the same purpose as a conventional metal case. That is, the outer metal case 4 is provided to prevent gas leakage from the outer periphery of the refractory 2 and to reinforce the strength of the refractory 2. A filler material 5 such as mortar (see FIGS. 2 and 3 ) is filled between the outer metal case 4 and the refractory 2 and between the outer metal case 4 and the inner metal case 3 to fill the gaps therebetween and prevent gas leakage.

[0019] As shown in Fig. 2, the outer peripheral metal case 4 extends upward beyond the upper end of the inner peripheral metal case 3. The filler material 5 is filled between the outer peripheral metal case 4 and the refractory material 2 and between the outer peripheral metal case 4 and the inner peripheral metal case 3. As shown in Fig. 3, the outer peripheral metal case 4 extends downward beyond the lower end of the inner peripheral metal case 3. The filler material 5 is filled between the outer peripheral metal case 4 and the refractory material 2 and between the outer peripheral metal case 4 and the inner peripheral metal case 3. Note that if the gap between the outer peripheral metal case 4 and the inner peripheral metal case 3 is narrow, it is not necessary to fill the filler material 5 therebetween.

[0020] 4 shows a cross-sectional view of the gas pool 6 and gas inlet passage 9 of the gas blowing nozzle 1 of this embodiment. As described above, the inner metal case 3 is attached to the refractory 2 by shrink fitting, and the recess 2b and gas inlet groove 2c of the refractory 3 are covered by the inner metal case 3. This prevents the filler material 5, such as mortar, from flowing into the gas pool 6 and gas inlet passage 9, ensuring a stable gas flow rate. Furthermore, the inner metal case 3 attached to the refractory 2 by shrink fitting firmly secures the refractory 2 and reinforces its strength, preventing mechanical cracking and cracking due to thermal shock in the refractory 2 and preventing gas leaks caused by cracking in the refractory 2. In particular, in the case of a refractory 2 that is vertically long, as in this embodiment, the strength of the refractory 2 is easily weakened, so reinforcing the strength of the refractory 2 with the inner metal case 3 is effective.

[0021] Furthermore, by attaching the inner metal case 3 to the refractory 2 by shrink fitting, the degree of adhesion between the inner metal case 3 and the refractory 2 is increased, making it possible to reduce gas leakage. However, when viewed minutely, the outer surface of the refractory 2 is uneven, and there is a risk that inert gas may leak to the outside through small gaps between the inner metal case 3 and the refractory 2. By filling the gaps between the outer metal case 4 and the refractory 2 and the inner metal case 3 with a filler 5 such as mortar, it is possible to prevent inert gas from leaking from above and below the refractory 2.

[0022] 5 shows a cross-sectional view of the gas pool 16 and gas inlet passage 19 of a gas blowing nozzle 11 of a comparative example. In the comparative example, the inner metal case 3 is not provided, and the refractory 12 is surrounded by the outer metal case 14 as in the conventional art, and a filler material 15 such as mortar is filled between the outer metal case 14 and the refractory 2. In the comparative example, some 15a, 15b of the filler material 15 such as mortar may flow into the gas pool 16 or the gas inlet passage 19, causing variations in the flow rate of gas discharged from the gas pool 16 to the nozzle hole.

[0023] 6 shows a process flow chart of the manufacturing method of the gas blowing nozzle 1 of this embodiment. First, an inner metal case 3 is attached to a refractory 2 having a nozzle hole 2a and a recess 2b on its outer surface for forming a gas pool 6 by shrink fitting (S1). Next, a filler material 5 such as mortar is applied to the refractory 2 with the inner metal case 3 attached and the outer surface of the inner metal case 3 and / or the inner surface of the outer metal case 4 (S2). Next, the outer metal case 4 surrounding the refractory 2 and the inner metal case 3 is set concentrically with the refractory 2 and the inner metal case 3, and the filler material 5 is filled between the refractory 2 and the inner metal case 3 and the outer metal case 4 (S3). The filler material 5 such as mortar is then allowed to dry naturally, thereby producing the gas blowing nozzle 1 of this embodiment. As described above, the outer metal case 4 may be set after step S2 of applying the filler material 5, or step S2 may be omitted, and the filler material 5 may be filled between the refractory material 2 and the inner metal case 3 and the outer metal case 4 after the outer metal case 4 is set.

[0024] The present invention is not limited to the above-described embodiment, and can be embodied in other embodiments without departing from the spirit of the present invention.

[0025] For example, in the above embodiment, the inert gas supplied from the gas inlet pipe is introduced into the gas pool via the gas inlet passage, but the gas inlet passage may be omitted and the inert gas supplied from the gas inlet pipe may be introduced directly into the gas pool.

[0026] In addition, in the above embodiment, the gas pool is provided at one location on the outer surface of the refractory material, but the gas pool may be provided at two or more locations on the outer surface of the refractory material, or may be provided at a location other than the upper part of the outer surface of the refractory material.

[0027] This specification is based on Japanese Patent Application No. 2024-033568, filed March 6, 2024, the entire contents of which are incorporated herein by reference.

[0028] REFRACTORY SYMBOLS 1... Gas blowing nozzle 2... Refractory material 2a... Nozzle hole 2b... Recess 2c... Gas introduction groove 3... Inner peripheral metal case 4... Outer peripheral metal case 5... Filler material 6... Gas pool

Claims

1. A gas blowing nozzle comprising: a refractory having a nozzle hole and a recess for forming a gas pool on its outer surface; an inner metal case attached to the refractory by shrink fitting and covering the recess; an outer metal case surrounding the refractory and the inner metal case; and a filler material filled at least between the refractory and the outer metal case.

2. The gas blowing nozzle according to claim 1, characterized in that the refractory has a gas inlet groove connected to the recess on its outer surface, and the inner metal case covers the recess and the gas inlet groove of the refractory.

3. A gas blowing nozzle according to claim 1 or 2, characterized in that the thickness of the inner metal case is thinner than the thickness of the outer metal case.

4. A method for manufacturing a gas blowing nozzle, comprising the steps of: attaching an inner metal case to a refractory material having a nozzle hole and a recess on its outer surface for forming a gas pool by shrink fitting, the inner metal case covering the recess; and setting an outer metal case surrounding the refractory material and the inner metal case, and filling a filler material at least between the refractory material and the outer metal case.

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