Immersion nozzle

Abstract

In an immersion nozzle, the restriction on the size of the corner radius at the connection point between the flange and the nozzle is relaxed to avoid stress concentration at the connection point. [Solution] The refractory material 2 comprises a flange portion 5 having a rectangular upper surface 51 and lower surface 52 in a plan view, and a side surface 53 connecting the upper surface 51 and the lower surface 52, and a substantially cylindrical nozzle portion 6 extending from the lower surface 52 of the flange portion 5, and a covering material 3 that covers the refractory material 2 in a portion including at least the side surface 53, wherein the connection portion 7 between the flange portion 5 and the nozzle portion 6 is not covered by the covering material 3 at least partially.

Description

[[Technical Field]]

[0001] The present invention relates to an immersion nozzle. [[Background Art]]

[0002] Immersion nozzles are commonly used in continuous steel casting and other processes. An immersion nozzle is a nozzle-shaped refractory that is used with the discharge port at its tip immersed in molten steel.

[0003] In one aspect, an immersion nozzle is used by being attached to a quick nozzle changing device. The quick nozzle changing device is installed on a slide valve of a tundish or the like, and is configured to enable quick replacement of the immersion nozzle communicating with the slide valve. The immersion nozzle Nz (Fig. 6) attached to the quick nozzle changing device has a structure in which the nozzle portion N extends from the flange portion 5, and generally the side surface and lower surface 52 of the flange portion 5 and the root portion of the nozzle portion N are covered with a metal covering material C. The covering material C serves to prevent damage to the immersion nozzle Nz caused by contact with the quick nozzle changing device. The immersion nozzle of this aspect is found, for example, in Japanese Patent Laid-Open No. 2008-178899 (Patent Document 1) and Japanese Patent Laid-Open No. 2015-157316 (Patent Document 2). [[Prior Art Documents]] [[Patent Documents]]

[0004] [[Patent Document 1]] Japanese Patent Laid-Open No. 2008-178899 [[Patent Document 2]] Japanese Patent Laid-Open No. 2015-157316 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0005] Immersion nozzles often suffer from damage (such as crack formation) at the connection point between the flange and the nozzle. Making the corner radius of the connection point as large as possible is advantageous in avoiding damage because it helps to avoid stress concentration at the connection point. However, the immersion nozzles disclosed in Patent Documents 1 and 2 have limitations on the size of the corner radius because the shape of the refractory material is restricted by the shape of the metal covering material.

[0006] Therefore, it is desirable to realize an immersion nozzle that can relax the restrictions on the size of the corner radius at the connection point between the flange and the nozzle, thereby avoiding stress concentration at the connection point. [Means for solving the problem]

[0007] The immersion nozzle according to the present invention comprises a shaped refractory material having a flange portion having a rectangular upper and lower surface, and a side surface connecting the upper and lower surfaces in a plan view, and a substantially cylindrical nozzle portion extending from the lower surface of the flange portion, and a covering material that covers the shaped refractory material in a portion including at least the side surface, wherein the connection portion between the flange portion and the nozzle portion is not at least partially covered by the covering material.

[0008] With this configuration, since the connection point is not covered by the covering material at least partially, interference between the refractory material and the covering material at the connection point is less likely. Therefore, the radius of the corner of the refractory material at the connection point can be made larger than that of conventional immersion nozzles, thus avoiding stress concentration.

[0009] Preferred embodiments of the present invention will be described below. However, the scope of the present invention is not limited by the examples of preferred embodiments described below.

[0010] In one embodiment of the immersion nozzle according to the present invention, it is preferable that the covering material covers the shaped refractory material in a portion including the side surface and the bottom surface.

[0011] With this configuration, the lower surface of the flange is covered with a protective material, resulting in relatively high strength for the flange. Furthermore, when the immersion nozzle is attached to a nozzle rapid replacement device, the refractory material of the part supported by the nozzle rapid replacement device is protected.

[0012] In one embodiment, the immersion nozzle according to the present invention further includes an amorphous refractory material disposed between the shaped refractory material and the covering material, wherein the thickness of the amorphous refractory material is preferably 0.7 mm or more.

[0013] This configuration further helps to avoid stress concentration at the connection points.

[0014] In one embodiment of the immersion nozzle according to the present invention, it is preferable that the difference between the outer diameter of the connecting portion and the outer diameter of the nozzle portion is 20 mm or more.

[0015] This configuration makes it easier to secure corner radii of a particularly effective size to avoid stress concentration.

[0016] In one embodiment, the immersion nozzle according to the present invention is preferably mounted on a nozzle rapid replacement device.

[0017] This configuration makes it easier to avoid production interruptions associated with replacing immersion nozzles in continuous steel production to which the present invention is applied.

[0018] In one embodiment, the immersion nozzle according to the present invention preferably has the lower surface of the flange portion covered with the covering material at a position supported by the nozzle rapid replacement device when the nozzle is mounted on the nozzle rapid replacement device.

[0019] This configuration makes it easier to avoid damage to the refractory material caused by contact with the nozzle rapid replacement device.

[0020] Further features and advantages of the present invention will become clearer through the following description of exemplary and non-limiting embodiments, with reference to the drawings. [Brief explanation of the drawing]

[0021] [Figure 1] It is a front cross-sectional view of the immersion nozzle according to the embodiment. [Figure 2] It is a bottom view of the immersion nozzle according to the embodiment. [Figure 3] It is a side cross-sectional view showing the usage state of the immersion nozzle according to the embodiment. [Figure 4] It is a front cross-sectional view showing the usage state of the immersion nozzle according to the embodiment. [Figure 5] It is a front cross-sectional view of the immersion nozzle according to a modified example. [Figure 6] It is a front cross-sectional view of the immersion nozzle according to a conventional example. MODE FOR CARRYING OUT THE INVENTION

[0022] An embodiment of the immersion nozzle according to the present invention will be described with reference to the drawings. Hereinafter, an example in which the immersion nozzle according to the present invention is applied to the immersion nozzle 1 attached to the rapid nozzle changing device 10 will be described.

[0023] [Configuration of Immersion Nozzle] The immersion nozzle 1 according to the present embodiment includes a shaped refractory 2, a covering material 3, and an unshaped refractory 4 (Fig. 1, Fig. 2). The shaped refractory 2 has a flange portion 5 and a nozzle portion 6, and has a flow path 21 inside through which a fluid such as molten steel circulates. The shaped refractory 2 is partially covered with the covering material 3, and the unshaped refractory 4 is disposed between the shaped refractory 2 and the covering material 3.

[0024] The immersion nozzle 1 has the flange portion 5 attached to the lower part of a container such as a ladle or a tundish, and is used for discharging the fluid (such as molten steel) flowing out from the container by gravity from the tip end (not shown) of the nozzle portion 6. In view of this usage mode, when referring to the vertical direction of the immersion nozzle 1, unless otherwise specified, the flange portion 5 side is referred to as "upper" and the nozzle portion 6 side is referred to as "lower".

[0025] (Shaped Refractory) The refractory material 2 may be a known refractory material used in immersion nozzles. That is, the refractory material 2 may include oxide raw materials such as alumina, silica, spinel, magnesia, zirconia, zircon, and calcium zirconate; carbon raw materials such as graphite, carbon black, and pitch; and non-oxide raw materials such as silicon carbide, boron carbide, zirconium boride, aluminum, and silicon nitride. Therefore, as non-limiting examples, the refractory material 2 may be alumina refractories, silica refractories, spinel refractories, magnesia refractories, zirconia refractories, alumina-carbon refractories, magnesia-carbon refractories, zirconia-carbon refractories, and so on.

[0026] The refractory material 2 is constructed as a single, integrated refractory material having a rectangular flange portion 5 in the plan view and a substantially cylindrical nozzle portion 6 extending from the flange portion 5. Here, "rectangle" includes not only a rectangle in the mathematical sense but also shapes that have been modified (such as rounding) to a rectangle in the mathematical sense, which is typically applied industrially. In this embodiment, the flange portion 5 has rounded corners (Figure 2). The flange portion 5 has a rectangular upper surface 51 and lower surface 52 in the plan view, as well as a side surface 53 connecting the upper surface 51 and the lower surface 52. The nozzle portion 6 extends from the lower surface 52 of the flange portion 5. A corner radius 71 is provided at the connection portion 7 between the flange portion 5 (lower surface 52) and the nozzle portion 6, and the shape is configured to change continuously between the planar lower surface 52 and the substantially cylindrical nozzle portion 6. The tip of the nozzle portion 6 (not shown) is provided with a discharge port (not shown) for discharging fluid into a mold or the like.

[0027] The boundary between the flange portion 5 (lower surface 52) and the connection portion 7 is defined as the starting point where deformation of the refractory material occurs in a direction away from the lower surface 52. The boundary between the nozzle portion 6 and the connection portion 7 is defined as the starting point where the outer diameter expands from bottom to top. In this embodiment, both the boundary between the flange portion 5 and the connection portion 7 and the boundary between the nozzle portion 6 and the connection portion 7 are circular in the plan view, and the diameter of the former is defined as the outer diameter D1 of the connection portion 7.

[0028] Preferably, the difference D1-D2 between the outer diameter D1 of the connecting portion 7 and the outer diameter D2 of the nozzle portion 6 is 20 mm or more. The larger the difference D1-D2, the less likely cracks are to occur in the connecting portion 7, and the crack-preventing effect is particularly pronounced when the difference D1-D2 is 20 mm or more. There is no particular lower limit to the difference D1-D2, but it may be, for example, 10 mm or more.

[0029] As described above, the larger the difference D1-D2 between the outer diameter D1 of the connection portion 7 and the outer diameter D2 of the nozzle portion 6, the more advantageous it is for crack prevention. However, if the outer diameter D2 of the nozzle portion 6 is reduced in order to increase the difference D1-D2, the flow path 21 becomes narrower and the amount of fluid that can pass through the nozzle portion 6 decreases. Therefore, in order to enhance the crack prevention effect without impairing the performance of the immersion nozzle 1, it is preferable to make the outer diameter D1 of the connection portion 7 as large as possible.

[0030] Shaped refractories 2 can be manufactured by known methods. For example, shaped refractories 2 are manufactured by a method comprising a mixing step, a molding step, and a firing step. In the mixing step, various raw materials such as oxide raw materials, carbon raw materials, oxideable raw materials, and other additives are weighed, and these raw materials are mixed with a binder. The binder is an aid to facilitate the shaping of the mixture of raw materials, and examples include organic binders such as phenolic resins, furan resins, pitch, and tar, as well as inorganic binders such as phosphates and silicates.

[0031] The molding process involves molding the mixture obtained in the mixing process to form the shape of the refractory material 2. For example, the mixture is molded using a molding method such as cold isostatic pressing (CIP molding) to obtain a pre-molded body. The pre-molded body may be dried as appropriate.

[0032] In the firing process, the pre-molded body obtained in the molding process is fired. The firing conditions are not particularly limited. For example, the firing atmosphere is not particularly limited and can be appropriately selected from an air atmosphere, a reducing atmosphere, and an inert atmosphere. The firing temperature is also not particularly limited and can be, for example, between 700°C and 1200°C. The firing conditions can be appropriately set considering the materials constituting the refractory material 2 and the shape of the refractory material 2.

[0033] (covering material) The covering material 3 is a metallic covering material that partially covers the shaped refractory material 2. The covering material 3 can generally be made of general steel or stainless steel. As will be described later, the immersion nozzle 1 is supported by the nozzle rapid replacement device 10 in the covering material 3, so the shape of the covering material 3 must be such that it can be supported by the nozzle rapid replacement device 10.

[0034] In this embodiment, the covering material 3 covers the refractory material 2 on the side surface 53 and a portion of the bottom surface 52 of the flange portion 5. Therefore, the covering material 3 has a side portion 31 that covers the side surface 53 and a bottom portion 32 that covers the bottom surface 52. The bottom portion 32 has an opening 33, and the nozzle portion 6 extends through the opening 33. The inner diameter D3 of the opening 33 is larger than the outer diameter D2 of the nozzle portion, and part or all of the connecting portion 7 is exposed from the opening 33. That is, the connecting portion 7 is not covered by the covering material 3 at least partially.

[0035] The immersion nozzle 1 according to this embodiment differs primarily from the conventional immersion nozzle Nz (Figure 6) in the shape of the coating material. For illustrative purposes, in Figure 6, the shaped refractory material 2 and the unshaped refractory material 4 are the same as those in the immersion nozzle 1 and are given the same reference numerals. In the conventional immersion nozzle Nz as well, the shape of the coating material C must be such that it can be supported by the nozzle rapid replacement device 10, and specifically, it must be such that it does not interfere with the clamper 11 (described later) of the nozzle rapid replacement device 10.

[0036] In conventional immersion nozzles Nz, the covering material C typically covers not only the flange portion 5 but also the base portion of the nozzle portion 6. In this structure, the nozzle portion C2, which covers the nozzle portion 6, extends from the lower surface portion C1, which covers the lower surface 52 of the flange portion 5. A corner radius R is provided at the connection between the lower surface portion C1 and the nozzle portion C2, and the connection portion 7 of the refractory material 2 is located in a position where it is covered by the corner radius R. Due to this positional relationship, the shape of the connection portion 7 is constrained by the shape of the corner radius R. That is, the shape of the connection portion 7 must be within the range where it does not interfere with the corner radius R inside the corner radius R.

[0037] In other words, the shape of the coating material C is constrained by the nozzle rapid replacement device 10, and the shape of the connecting portion 7 is constrained by the shape of the coating material C. Due to these dual constraints, the size of the corner radius 71 of the connecting portion 7 (in other words, the size of the difference D1-D2) is limited. As mentioned above, the larger the difference D1-D2 between the outer diameter D1 of the connecting portion 7 and the outer diameter D2 of the nozzle portion 6, the more advantageous it is for crack prevention, and it is particularly preferable to make the outer diameter D1 of the connecting portion 7 as large as possible. However, since the outer diameter D1 of the connecting portion 7 and the outer diameter D2 of the nozzle portion 6 are constrained by the shape of the coating material C, the degree of freedom in designing the refractory material 2 (especially the connecting portion 7) is limited.

[0038] In contrast, in the immersion nozzle 1 according to this embodiment, the connection portion 7 is not covered by the covering material 3 at least partially, so interference between the connection portion 7 and the covering material 3 is less likely to occur. Therefore, compared to the conventional immersion nozzle Nz, there is greater design freedom for the refractory material 2 (especially the connection portion 7), and it is easier to make the corner radius 71 larger. In other words, it is easier to make the outer diameter D1 of the connection portion 7 larger. This makes it possible to design the nozzle in a way that makes it easier to avoid cracks in the connection portion 7.

[0039] In the immersion nozzle 1 according to this embodiment, increasing the outer diameter D1 of the connection portion 7 may cause interference between the connection portion 7 and the covering material 3 (lower surface portion 32). However, this interference can be easily avoided by making the inner diameter D3 of the opening portion 33 sufficiently larger than the outer diameter D2 of the nozzle portion 6. Specifically, it is preferable that the difference D3-D2 between the inner diameter D3 of the opening portion 33 and the outer diameter D2 of the nozzle portion is 20 mm or more. Note that the inner diameter D3 of the opening portion 33 may be larger than the outer diameter D1 of the connection portion 7. In this case, the entire connection portion 7 will not be covered by the covering material 3.

[0040] The coating material 3 can be manufactured by known metalworking methods. For example, the coating material 3 can be manufactured by sheet metal processing using sheet metal made from the metal material that constitutes the coating material 3 as the raw material.

[0041] (Unshaped refractories) The unshaped refractory material 4 is placed between the shaped refractory material 2 and the covering material 3. The unshaped refractory material 4 may be a known unshaped refractory material used in immersion nozzles, and non-limiting examples include refractory mortar. It is preferable that the thickness T of the unshaped refractory material 4 is 0.7 mm or more, as this makes it easier to avoid stress concentration at the connection point and particularly easy to prevent cracks in the connection point 7.

[0042] The method of applying the unshaped refractory material 4 is not particularly limited. For example, one method is to insert the shaped refractory material 2 into the covering material 3 and then pour the unshaped refractory material between the shaped refractory material 2 and the covering material 3, or to apply the unshaped refractory material 4 to the part of the shaped refractory material 2 that will be covered by the covering material 3 (part of the bottom surface 52 and the side surface 53) and then insert the shaped refractory material 2 into the covering material 3.

[0043] [How to use the immersion nozzle] The immersion nozzle 1 according to this embodiment is used when mounted on a nozzle rapid replacement device 10 (Figures 3 and 4). The nozzle rapid replacement device 10 includes a clamper 11 that supports the immersion nozzle 1 and a hydraulic cylinder 12 that moves the immersion nozzle 1 along the clamper 11. The clamper 11 is a pair of metal members arranged opposite each other, and its cross-section perpendicular to the longitudinal direction (left-right direction in Figure 3) is formed in a hook shape (Figure 4). The nozzle rapid replacement device 10 is equipped with two immersion nozzles 1 (1A and 1B), of which immersion nozzle 1A is positioned in a working position where fluid flows, and immersion nozzle 1B is positioned in a standby position where fluid does not flow.

[0044] When it becomes necessary to replace the immersion nozzle 1A through which molten steel or other fluids flow, the hydraulic cylinder 12 is operated to push the immersion nozzle 1B. The immersion nozzle 1B, pushed by the hydraulic cylinder, then pushes the immersion nozzle 1A. As a result, the immersion nozzles 1A and 1B move along the longitudinal direction of the clamper 11, and the immersion nozzle 1B is positioned in place of the immersion nozzle 1A. This minimizes the interruption of operations required for the replacement of the immersion nozzles 1.

[0045] The immersion nozzle 1 is supported by the clamper 11 at the lower surface portion 32 of the covering material 3 (Figure 4). That is, when the immersion nozzle 1 is mounted on the nozzle rapid replacement device 10, the lower surface 52 is covered by the covering material 3 at the position where it is supported by the nozzle rapid replacement device 10 (clamper 11). Since the clamper 11 is made of metal, it is preferable that the portion of the immersion nozzle 1 that contacts the clamper 11 is also made of metal, and the above configuration is preferable in this respect. In this embodiment, the separation distance L of the clamper 11 is greater than the inner diameter D3 of the opening portion 33 and less than the width W of the flange portion 5 (lower surface 52).

[0046] [Other Embodiments] Finally, other embodiments of the immersion nozzle according to the present invention will be described. Note that the configurations disclosed in each of the following embodiments can be applied in combination with configurations disclosed in other embodiments, as long as this does not create a contradiction.

[0047] In the above embodiment, a configuration was described in which the refractory material 2 is covered by the covering material 3 on the side surface 53 and a portion of the lower surface 52 of the flange portion 5. However, in the present invention, the lower surface of the flange portion does not need to be covered by the covering material. In the modified immersion nozzle 8 shown in Figure 5, the covering material 9 covers only the side surface 53 of the flange portion 5. In this case as well, the connection portion 7 is not covered by the covering material 9, and interference between the connection portion 7 and the covering material 9 is unlikely to occur. In this modified example, the refractory material 2 is exposed at the position supported by the nozzle rapid replacement device, and the refractory material 2 and the clamper come into direct contact. Therefore, it is preferable to take measures to prevent damage to the refractory material 2 due to contact with the clamper.

[0048] In the above embodiment, a configuration in which an amorphous refractory material 4 is placed between the fixed refractory material 2 and the covering material 3 was described as an example. However, in the present invention, the presence or absence of the amorphous refractory material is optional. Therefore, the amorphous refractory material 4 in the above embodiment may be omitted in whole or in part.

[0049] In the above embodiment, a configuration in which the entire connection portion 7 is not covered by the covering material 3 was described as an example. However, in the present invention, the connection portion may be partially covered by the covering material.

[0050] With regard to other configurations, the embodiments disclosed herein are illustrative in all respects, and it should be understood that the scope of the present invention is not limited thereto. Those skilled in the art will readily understand that modifications can be made as appropriate without departing from the spirit of the invention. Therefore, other embodiments modified without departing from the spirit of the invention are naturally included within the scope of the present invention. [Examples]

[0051] The present invention will be further described below with reference to examples. However, the following examples are not limiting to the present invention.

[0052] (1) Configuration of the immersion nozzle in the examples and comparative examples (Common matters) In the immersion nozzles of each example and comparative example, the material of the shaped refractory was alumina carbon, the material of the coating material was general steel, and the material of the unshaped refractory was refractory mortar. Each immersion nozzle in each example was manufactured by producing a shaped refractory that met the specified dimensional conditions for each example using a known method, and then covering the shaped refractory with a coating material of a predetermined shape. In all examples, the width W of the flange surface was 204 mm. The shape of the coating material was as shown in Figure 1 for Examples 1 to 5, as shown in Figure 5 for Example 6, and as shown in Figure 6 for Comparative Examples 1 to 3.

[0053] (Example 1) An immersion nozzle with a configuration similar to immersion nozzle 1, which has the cross-sectional shape shown in Figure 1, was created and designated as Example 1. In the immersion nozzle of Example 1, the outer diameter D1 of the connection part was 172 mm, and the outer diameter D2 of the nozzle part was 150 mm, with a difference of D1-D2 of 22 mm. The inner diameter D3 of the opening part was 172 mm. The thickness T of the monolithic refractory material was 0.8 mm.

[0054] (Example 2) An immersion nozzle was created that was the same as in Example 1, except that the outer diameter D1 of the connection part and the inner diameter D3 of the opening part were set to 175 mm, and this was designated as Example 2. In the immersion nozzle of Example 2, the difference D1-D2 was 25 mm.

[0055] (Example 3) An immersion nozzle was created in the same manner as in Example 1, except that the thickness T of the amorphous refractory material was set to 0.6 mm, and this was designated as Example 3.

[0056] (Example 4) An immersion nozzle was created in the same manner as in Example 1, except that the thickness T of the amorphous refractory material was set to 2.8 mm, and this was designated as Example 4.

[0057] (Example 5) An immersion nozzle with a configuration similar to that of immersion nozzle 1A, which has the cross-sectional shape shown in Figure 5, was created and designated as Example 5. In the immersion nozzle of Example 5, the outer diameter D1 of the connection part was 175 mm, and the outer diameter D2 of the nozzle part was 150 mm, with a difference of D1-D2 of 25 mm.

[0058] (Comparative Example 1) An immersion nozzle with a configuration similar to the immersion nozzle Nz with the cross-sectional shape shown in Figure 6 was created and designated as Comparative Example 1. In the immersion nozzle of Comparative Example 1, the outer diameter D1 of the connection part was 160 mm, and the outer diameter D2 of the nozzle part was 150 mm, with a difference of D1-D2 of 10 mm. The inner diameter D3 of the opening part was 160 mm. The thickness T of the monolithic refractory material was 0.8 mm. Comparative Example 1 is a conventional immersion nozzle.

[0059] (Comparative Example 2) A immersion nozzle was created that was the same as in Comparative Example 1, except that the outer diameter D1 of the connection part was set to 168 mm, and this was designated as Comparative Example 2. In the immersion nozzle of Comparative Example 2, the difference D1-D2 was 18 mm.

[0060] (Comparative Example 3) An attempt was made to create an immersion nozzle similar to Comparative Example 1, except that the outer diameter D1 of the connection part was set to 172 mm, and designated as Comparative Example 3. In the immersion nozzle of Comparative Example 3, the planned difference D1-D2 was 22 mm. However, the refractory material produced under these dimensional conditions interfered with the covering material at the connection part, and it was not possible to cover it using a covering material of the same shape as in Comparative Examples 1 and 2. Therefore, it was impossible to create the immersion nozzle planned for Comparative Example 3.

[0061] (2) Evaluation (Usability) The immersion nozzles of each example and comparative example were mounted on a nozzle rapid replacement device, and the difficulty of mounting was evaluated in comparison to Comparative Example 1, which was a conventional immersion nozzle. However, Comparative Example 3 was excluded from this evaluation because an immersion nozzle could not be created. For the immersion nozzles of Examples 1-5 and Comparative Example 2, no significant difference was observed in the difficulty of mounting them on the nozzle rapid replacement device compared to Comparative Example 1, so they were given an evaluation of "A". The immersion nozzle of Example 6 was given an evaluation of "B" because the shaped refractory material was in a positional relationship where it could directly contact the clamper, requiring measures such as using an intervening material such as a metal plate or performing the mounting operation more carefully than in Comparative Example 1. However, all immersion nozzles of Examples 1-6 and Comparative Examples 1 and 2 were deemed to be immersion nozzles that can be mounted on the nozzle rapid replacement device and are actually usable.

[0062] (Stress relaxation effect) Finite element method (FEM) analysis was performed on the stress distribution generated in the immersion nozzles of each example and comparative example. However, Comparative Example 3 was excluded from this evaluation because an immersion nozzle could not be created. The analysis was performed using the nonlinear finite element analysis software Marc (manufactured by MSC Software). As analysis conditions, the temperature and heat transfer coefficient were set for the target edge on the simulation model based on the actual preheating temperature and steel receiving temperature reached by the immersion nozzle in a rapid nozzle replacement device used for continuous casting of steel. In addition, the physical properties of the simulation model were set based on known values ​​for the physical properties of each part of the immersion nozzle (shape-formed refractory: alumina carbon, coating material: general steel, shape-less refractory: refractory mortar).

[0063] Under the above conditions, the generated stress was calculated for each of Examples 1-6 and Comparative Examples 1 and 2. The generated stress calculated for each example was expressed as an index with the value of Comparative Example 1 set to 100, and based on this index, it was classified into the following four levels. The generated stress in Examples 1-5 was 70% or less (level C or higher) compared to Comparative Example 1, which is an example of a conventional immersion nozzle, indicating that the stress was relieved in all examples. A: Index is 50 or less B: Index greater than 50 and less than or equal to 60 C: Index greater than 60 and less than or equal to 70 D: Index greater than 70

[0064] Table 1: Evaluation of stress relaxation effect [Table 1] [Industrial applicability]

[0065] This invention can be used for immersion nozzles that are attached to tundishes or the like via a rapid nozzle replacement device. [Explanation of symbols]

[0066] 1: Immersion nozzle 2: Standard refractory materials 3: Covering material 4: Monolithic refractories 5: Flange section 51:Top surface 52: Bottom surface 53: Side view 6: Nozzle section 7: Connection part 10: Nozzle rapid replacement device D1: Outer diameter of the connection part D2: Outer diameter of the nozzle

Claims

1. A flange portion having a rectangular upper and lower surface in the plan view, and a side surface connecting the upper and lower surfaces, A refractory material having a substantially cylindrical nozzle portion extending from the lower surface of the flange portion, A covering material that covers the shaped refractory material in at least the portion including the side surface, An immersion nozzle in which the connection portion between the flange portion and the nozzle portion is not at least partially covered by the covering material.

2. The immersion nozzle according to claim 1, wherein the covering material covers the shaped refractory material in portions including the side surface and the bottom surface.

3. The present invention further includes an unshaped refractory material disposed between the aforementioned shaped refractory material and the aforementioned covering material, The immersion nozzle according to claim 1, wherein the thickness of the amorphous refractory material is 0.7 mm or more.

4. The immersion nozzle according to claim 1, wherein the difference between the outer diameter of the connecting portion and the outer diameter of the nozzle portion is 20 mm or more.

5. An immersion nozzle according to any one of claims 1 to 4, which is attached to a nozzle rapid replacement device.

6. The immersion nozzle according to claim 5, wherein, when mounted on the nozzle rapid replacement device, the lower surface of the flange portion is covered with the covering material at a position supported by the nozzle rapid replacement device.

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