Casting nozzle

Abstract

To provide a casting nozzle that is less prone to drawing in outside air even when exposed to external wind. [Solution] The upper end 111 of the nozzle body, which is the upper end of the nozzle body, is surrounded by a metal case 12. The upper end 111 of the nozzle body, surrounded by the metal case 12, is joined to a lower nozzle 2 attached to the bottom of a molten steel ladle or tundish. The casting nozzle 1 has a gas pool 13 provided between the outer surface of the upper end 111 of the nozzle body and the inner surface of the metal case 12, a gas passage 14 that communicates with the gas pool 13 and is provided between the upper end surface of the upper end 111 of the nozzle body and the inner surface of the metal case 12, and a gas outlet 141 which is the tip opening of the gas passage 14 and discharges gas toward the lower nozzle 2. The metal case 12 is provided with a hanging part 121 that hangs down to guide the gas discharged from the gas outlet 141 downwards.

Description

[Technical Field]

[0001] The present invention relates to a casting nozzle used in continuous casting of molten steel. [Background Art]

[0002] In continuous casting of molten steel, when discharging molten steel from a molten steel pan (ladle) to a tundish, a long nozzle as a casting nozzle is generally joined below a lower nozzle attached to the bottom of the molten steel pan, in order to suppress oxidation of the molten steel and entrainment of slag present on the upper surface in the tundish into the molten steel. Further, when pouring molten steel from the tundish into a mold, an immersion nozzle as a casting nozzle is generally joined below the lower nozzle attached to the bottom of the tundish.

[0003] Hereinafter, among these casting nozzles, a long nozzle will be mainly taken as an example for description. The long nozzle is joined to the lower nozzle attached to the bottom of the molten steel pan via a packing material or the like. High adhesion (sealing performance) is required between the long nozzle and the lower nozzle in order to suppress (a) mixing of air (oxygen etc.) into molten steel, (b) leakage of molten steel from the joint, and (c) wear caused by oxidation or the like near the joint of the long nozzle and the lower nozzle made of carbon-containing materials. In addition, the long nozzle is attached to and detached from the lower nozzle every time the molten steel pan is replaced, so this attachment and detachment is repeated for the number of times the molten steel pan is replaced. At the joint between such a long nozzle and the lower nozzle, adhesion may be degraded to form a gap due to attachment and detachment work, adhesion of molten steel, slag, etc., damage to the nozzle, or the like. When such a gap is formed, the sealing performance is degraded, and outside air is drawn into the nozzle, which increases the risk of causing oxidation of molten steel and damage due to oxidation of the nozzle made of carbon-containing refractory.

[0004] One countermeasure employs a method of discharging inert gas from near the upper end of the long nozzle. For example, Patent Documents 1 to 3 disclose a long nozzle having a structure in which the upper end of the nozzle body, made of refractory material, is surrounded by a metal case, and gas is discharged toward the lower nozzle from a sludge discharge port, which is the tip opening of a gas passage provided between the upper end surface of the nozzle body and the inner surface of the metal case. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2011-212721 [Patent Document 2] Japanese Patent Publication No. 2014-133241 [Patent Document 3] Japanese Patent Publication No. 2020-32430 [Overview of the initiative] [Problems that the invention aims to solve]

[0006] The inventors conducted detailed on-site observations, including usage conditions, of a conventional casting nozzle having a structure in which gas is discharged from a sludge discharge port, which is the tip opening of a gas passage provided between the upper end surface of the upper end of the nozzle body and the inner surface of the metal case, toward the lower nozzle, as described above. They also conducted various simulations based on these usage conditions. As a result, it was found that in the casting site, the casting nozzle is constantly exposed to external winds generated by cooling air from a spot cooler when an operator approaches, and cooling air to the sliding nozzle device to which the lower nozzle is attached. The effect of the gas seal caused by the discharge of gas from the gas discharge port is weakened by the influence of this external wind, making it easier for outside air to be drawn into the nozzle.

[0007] Therefore, the problem that the present invention aims to solve is to provide a casting nozzle that is less prone to drawing in outside air even when exposed to external wind. [Means for solving the problem]

[0008] According to one aspect of the present invention, the following casting nozzle is provided. A casting nozzle in which the upper end of the nozzle body, which is the upper end of the nozzle body, is surrounded by a metal case, and the upper end of the nozzle body surrounded by the metal case is joined to a lower nozzle attached to the bottom of a molten steel ladle or tundish, The nozzle has a gas pool provided between the outer surface of the upper end of the nozzle body and the inner surface of the metal case, a gas passage that communicates with the gas pool and is provided between the upper end surface of the upper end of the nozzle body and the inner surface of the metal case, and a gas outlet which is the tip-side opening of the gas passage and discharges gas toward the lower nozzle. A casting nozzle having a hanging portion on the metal case that guides the gas discharged from the gas outlet downward. [Effects of the Invention]

[0009] According to the present invention, by providing a hanging portion on the metal case, outside air is less likely to be drawn into the nozzle even when exposed to wind from the outside. [Brief explanation of the drawing]

[0010] [Figure 1] A cross-sectional view in the vertical direction of the main part of a casting nozzle, which is one embodiment of the present invention. [Figure 2] Figure 1 shows a cross-sectional view in the vertical direction illustrating the state when the metal case slides up in the casting nozzle. [Figure 3] A diagram conceptually illustrating the simulation methods and conditions used to verify the effect of the hanging portion. [Figure 4] This diagram conceptually illustrates the various models used in the simulations shown in Figure 3. [Figure 5] Figure 3 shows the simulation results for the flow of outside air and argon gas (when the crosswind is 1 m / min in models (a) and (b)). [Figure 6] Figure 3 shows the simulation results for the flow of outside air and argon gas (when the crosswind is -1 m / min in models (a) and (b)). [Figure 7] Figure 3 shows the simulation results for the flow of outside air and argon gas (when the crosswind is 1 m / min in models (c) and (d)). [Figure 8] Figure 3 shows the simulation results for the flow of outside air and argon gas (when the crosswind is -1 m / min in models (c) and (d)). [Figure 9] Figure 3 shows a graph illustrating the calculated amount of argon gas drawn in at the joint with the lower nozzle, based on the simulation. [Modes for carrying out the invention]

[0011] Figure 1 shows a cross-sectional view in the vertical direction of the main part of a casting nozzle, which is one embodiment of the present invention. The casting nozzle shown in the figure is a long nozzle 1, in which the upper end 111 of the nozzle body, which is the upper end of the nozzle body 11 made of refractory material, is surrounded by a metal case 12, and this upper end 111 of the nozzle body surrounded by the metal case 12 is joined to a lower nozzle 2 attached to the bottom of a molten steel ladle (not shown).

[0012] The long nozzle 1 comprises: a gas pool 13 provided between the outer side surface of the upper end 111 of the nozzle body and the inner side surface of the metal case 12; a gas passage 14 communicating with the gas pool 13 and provided between the upper end surface of the upper end 111 of the nozzle body and the inner surface of the metal case 12; and a gas discharge port 141 which is a distal opening of the gas passage 14 and discharges gas toward the lower nozzle 2. The metal case 12 is provided with a hanging portion 121 that hangs down to guide the gas discharged from the gas discharge port 141 downward. In Fig. 1, reference numeral 15 denotes a filler (adhesive) filled between the outer side surface of the upper end 111 of the nozzle body and the inner side surface of the metal case 12, in a region other than the portion forming the gas pool 13.

[0013] Here, in the present embodiment, a plurality of grooves 111a are radially provided on the upper end surface of the upper end 111 of the nozzle body. The gas passages 14 are formed by the plurality of grooves 111a and the inner surface of the metal case 12, and a plurality of gas passages 14 are radially provided corresponding to the plurality of grooves 111a. The configuration of such a gas passage 14 is a well-known configuration as disclosed, for example, in the above Patent Documents 2 and 3. However, the configuration of the gas passage in the present invention is not limited to this configuration. For example, a configuration in which a plurality of spacers are interposed instead of the plurality of grooves 111a may be adopted. In short, the gas passage only needs to be provided between the upper end surface of the upper end portion of the nozzle body and the inner surface of the metal case.

[0014] Next, a specific configuration of the hanging portion 121 will be described. In the present embodiment, the hanging portion 121 is provided so as to hang vertically downward in the form of a hanging curtain from the entire circumference of the inner peripheral edge of the metal case 12. However, the configuration of the hanging portion 121 is not limited to this configuration, and may be provided intermittently corresponding to the plurality of gas discharge ports 141 that are distal openings of the plurality of radially arranged gas passages 14. Further, the direction in which the hanging portion 121 hangs is not limited to vertically downward. For example, the hanging portion 121 may be tapered to hang downward in accordance with the shape of the joint portion with the lower nozzle 2 or the like. In short, the hanging portion only needs to hang so as to guide the gas discharged from the gas discharge port downward.

[0015] The length L of the hanging portion 121 in the vertical direction is not particularly limited, but in consideration of the upward creeping phenomenon of the metal case 12 described later, it is preferable that the length L of the hanging portion 121 in the vertical direction is 5 mm or more and 20 mm or less. Here, the length L of the hanging portion 121 in the vertical direction refers to the length from the inner surface of the metal case 12 to the lower end surface of the hanging portion 121, as shown in FIG. 1. The upward creeping phenomenon of the metal case 12 refers to a phenomenon in which the metal case 12 creeps upward relative to the upper end portion 111 of the nozzle body, as illustrated in FIG. 2. This upward creeping phenomenon occurs not only due to the difference in thermal expansion between the metal case (metal) and the upper end portion of the nozzle body (refractory), but also occurs when a force for pushing upward the upper end portion of the nozzle body surrounded by the metal case is applied to join the casting nozzle to the lower nozzle. The present inventors investigated data on the upward creeping phenomenon of the metal case (the upward creeping amount of the metal case) for various casting nozzles, and found that the amount is generally about 2 to 4 mm. Then, in consideration of this upward creeping phenomenon (upward creeping amount) of the metal case 12, it was found that it is preferable that the length of the hanging portion in the vertical direction is 5 mm or more and 20 mm or less. It should be noted that the present invention does not exclude those in which the length of the hanging portion in the vertical direction is less than 5 mm. This is because even if the length of the hanging portion in the vertical direction is less than 5 mm, the effect of the present invention (outside air is less likely to be drawn into the nozzle even when exposed to external wind) can be obtained to a considerable extent compared to the case where there is no hanging portion.

[0016] Next, a simulation performed to verify the effect of the hanging portion will be described. FIG. 3 conceptually shows the method and conditions of the simulation. Further, FIG. 4 conceptually shows various models subjected to the simulation. In the simulation, as conceptually shown in FIG. 3, the supply amount of gas (argon) to the casting nozzle was set to 250 L / min, the suction amount at the joint with the lower nozzle was set to 30 L / min, and the flow of outside air and argon gas was simulated respectively using the models shown in FIGS. 4(a) to (d) for the case where the external wind (cross wind) is 1 m / min and the case where it is -1 m / min. Here, the model in Figure 4(a) (hereinafter referred to as "Model (a)") is a conventional casting nozzle without a hanging section, where the metal case does not slide up as described above. The model in Figure 4(b) (hereinafter referred to as "Model (b)") is the case where the metal case slides up (amount of slide = 4 mm) in Model (a). Furthermore, the model in Figure 4(c) (hereinafter referred to as "Model (c)") is the casting nozzle of the present invention with a hanging section (length L = 8 mm), where the metal case does not slide up. The model in Figure 4(d) (hereinafter referred to as "Model (d)") is the case where the metal case slides up (amount of slide = 4 mm) in Model (c).

[0017] Figures 5 to 8 show the simulation results for the flow of outside air and argon gas. Specifically, Figure 5 shows the simulation results for models (a) and (b) when the crosswind is 1 m / min, Figure 6 shows the simulation results for models (a) and (b) when the crosswind is -1 m / min, Figure 7 shows the simulation results for models (c) and (d) when the crosswind is 1 m / min, and Figure 8 shows the simulation results for models (c) and (d) when the crosswind is -1 m / min. Furthermore, Figure 9 shows the argon gas intake rate at the connection point with the lower nozzle, calculated from these simulation results. As mentioned above, the simulation assumed an argon gas intake rate of 30 L / min at the connection point with the lower nozzle. This means that there is no outside air drawn into the nozzle, and as shown in Figure 9, this value (30 L / min) is the ideal value for argon gas intake.

[0018] From Figures 5 to 8 and Figure 9, it can be seen that, according to models (c) and (d), which are models of the casting nozzle of the present invention with a hanging section, compared to models (a) and (b), which are models of conventional casting nozzles without a hanging section, outside air is less likely to be drawn into the nozzle even when exposed to wind from the outside (crosswind) or when the metal case slides up.

[0019] In the embodiments described above, long nozzles were used as an example among casting nozzles, but the present invention can naturally be applied to immersion nozzles as well. Furthermore, the shape of the lower nozzles joined to these casting nozzles is not limited to the example in Figure 1, nor is the joining method between the casting nozzles and the lower nozzles limited to the example in Figure 1. In other words, known shapes and joining methods can be appropriately adopted. [Explanation of symbols]

[0020] 1. Long nozzle (casting nozzle) 11 Nozzle body 111 Upper end of nozzle body 111a Groove 12 Metal Case 121 Drooping part 13 Gas Pool 14 Gas flow path 141 Gas outlet 15 Filler (Adhesive) 2 Lower nozzle

Claims

1. A casting nozzle in which the upper end of the nozzle body, which is the upper end of the nozzle body, is surrounded by a metal case, and the upper end of the nozzle body surrounded by the metal case is joined to a lower nozzle attached to the bottom of a molten steel ladle or tundish, The nozzle has a gas pool provided between the outer surface of the upper end of the nozzle body and the inner surface of the metal case, a gas passage that communicates with the gas pool and is provided between the upper end surface of the upper end of the nozzle body and the inner surface of the metal case, and a gas outlet which is the tip-side opening of the gas passage and discharges gas toward the lower nozzle. A casting nozzle having a hanging portion on the metal case that guides the gas discharged from the gas outlet downward.

2. The casting nozzle according to claim 1, wherein the vertical length of the hanging portion is 5 mm or more and 20 mm or less.

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