Tandish

Abstract

This invention provides a novel structure for a dry coat layer that can effectively suppress the occurrence of collapse during the use of a tundish. [Solution] The tundish comprises a side wall portion that demarcates a storage portion where molten metal is stored, a bottom wall portion that intersects the lower end of the side wall portion and constitutes the bottom of the storage portion, and a dry coat layer formed on the inner wall surface of the side wall portion facing the storage portion, wherein the dry coat layer is formed such that its thickness increases from the upper end to the lower end.

Description

[Technical Field]

[0001] This invention relates to a tan dish. [Background technology]

[0002] For example, in casting techniques such as continuous casting of metals, molten metal is generally poured from a ladle into a mold via a tundish, which is a tank-shaped container. By using a tundish, inclusions such as oxides can be separated from the molten metal before it is supplied to the mold. Furthermore, by using a tundish, the amount and rate of molten metal supplied from the ladle to the mold can be adjusted, and it is also easy to branch the molten metal from the ladle into multiple molds. In this way, the tundish functions as a buffer container that adjusts the supply conditions of molten metal to the mold.

[0003] Typically, in tundishes, a refractory lining layer is formed on the inner surface of the iron shell that constitutes the container wall partitioning the storage area for molten metal, in order to enhance its durability against high-temperature molten metal. In addition, when using a tundish, a coating layer is often formed on the surface of this refractory layer.

[0004] By forming a coating layer on the refractory layer, the tundish itself can be protected, and the contamination of the molten metal from the refractory layer can be suppressed. Furthermore, by dismantling and removing the coating layer after casting is complete, residual materials such as metal and slag generated in the tundish during casting can be removed, thus facilitating the removal of residual materials from the tundish after casting.

[0005] The coating layer of a tundish may be formed by spraying a wet coating material. In general, a coating layer formed of a wet coating material is easy to form, has high adhesion to a refractory layer, and is less likely to fall off from the refractory layer. However, since moisture is used to form the coating layer of a wet coating material, it is known that hydrogen atoms remaining inside the coating layer may mix into molten metal, causing so-called hydrogen pickup, which may reduce the quality of cast products. It is also known that the coating layer of a wet coating material may deteriorate in seizure resistance to the refractory layer on the back side thereof and disassembly properties after casting.

[0006] As a coating layer for a refractory layer, in addition to the coating layer of the wet coating material described above, a dry coating layer using a dry coating material is known. The dry coating layer is disclosed, for example, in Patent Document 1 below. A dry coating layer can suppress the occurrence of hydrogen pickup as described above. Further, compared with a coating layer of a wet coating material, it is easier to improve seizure resistance to the refractory layer and disassembly properties after casting. Prior Art Literature Patent Documents

[0007] Patent Document 1 Japanese Patent No. 5302651 Summary of the Invention Problems to be Solved by the Invention

[0008] The dry coating layer of a tundish may expand when subjected to the heat of molten metal. On the other hand, for example, when replacing a ladle, the amount of molten metal in the tundish decreases and the molten metal level drops, the dry coating layer may contract due to a temperature decrease on its surface. The dry coating layer may collapse from the vessel wall of the tundish due to stress generated by thermal expansion and contraction caused by such heat from the molten metal.

[0009] If the dry coat layer collapses, there is a risk that the dry coat material that has detached from the tundish container wall may become mixed into the molten metal as an inclusion. Furthermore, if the dry coat layer collapses, there is a risk that the refractory material will be exposed to the molten metal and damaged in the area where the dry coat layer has collapsed, or that the molten metal reaching the steel shell may melt the steel shell and cause leakage.

[0010] Conventionally, in order to suppress the collapse of the dry coat layer, the strength of the dry coat layer was sometimes adjusted by modifying the binder components contained in the dry coat material. However, it could not be said that adjusting the binder components alone was sufficient to suppress the collapse of the dry coat layer.

[0011] To suppress the collapse of the dry coat layer, one method is to increase the thickness of the dry coat layer to structurally enhance its strength. However, the shape of the tundish is often designed in a complex way to perform the functions described above, making it difficult to simply increase the thickness of the dry coat layer. Furthermore, increasing the thickness of the dry coat layer increases its volume, which may lead to a decrease in the capacity of the tundish. In addition, increasing the thickness of the dry coat layer leads to increased running costs due to the increased amount of dry coat material used, which may also be detrimental to accommodating changes in the design of the tundish for each cast product. Thus, for structural reasons related to the tundish, simply increasing the thickness of the dry coat layer is not easy, and increasing the thickness of the dry coat layer may also reduce the operational efficiency of the tundish.

[0012] The present invention aims to provide a novel structure for a dry coat layer that can effectively suppress the occurrence of collapse during use of a tundish. [Means for solving the problem]

[0013] The present invention can be realized, for example, in the following forms.

[0014] [First Embodiment] The first embodiment of the present invention is provided as a tundish. The tundish of the first embodiment comprises a side wall portion that demarcates a storage portion in which molten metal is stored, a bottom wall portion that intersects the lower end of the side wall portion and constitutes the bottom of the storage portion, and a dry coat layer formed on the inner wall surface of the side wall portion facing the storage portion, wherein the dry coat layer is formed such that its thickness increases from the upper end to the lower end.

[0015] [Second Embodiment] In the tundish of the first embodiment described above, the thickness of the lower end of the dry coat layer may be twice or more the thickness of the upper end of the dry coat layer.

[0016] [Third Embodiment] In the tundish described in the first or second embodiment, the thickness of the dry coat layer at the center of gravity may be 1.5 times or more but less than 2.0 times the thickness of the upper end of the dry coat layer.

[0017] [Fourth Embodiment] In the tundish described in any one of the first, second, and third embodiments, when the angle between the side wall and the bottom wall is θ0, the angle θ between the center line in the thickness direction of the dry coat layer and the bottom wall in the initial state may be θ0 + α (0° < α < 5°).

[0018] [Fifth Embodiment] In the tundish described in any one of the first, second, third, and fourth embodiments, the upper end of the dry coat layer may be formed at a lower position than the upper end of the side wall portion.

[0019] [Sixth Embodiment] In the tundish described in any one of the first, second, third, fourth, and fifth embodiments, an outlet is formed at the upper end of the side wall portion for discharging the molten metal exceeding a specified amount in the storage portion, and the height position of the upper end of the dry coat layer may correspond to the position of the lower end of the outlet.

[0020] [Seventh Embodiment] In the tundish described in any one of the first, second, third, fourth, fifth, and sixth embodiments, a nozzle hole for discharging the molten metal from the storage portion may be formed in the bottom wall portion near the lower end of the dry coat layer.

[0021] [Eighth Form] In the tundish described in any one of the first, second, third, fourth, fifth, and sixth forms, the amount of displacement of the upper end of the dry coat layer when the dry coat layer bends inward from its initial state towards the reservoir is defined as the amount of uplift δ, and the amount of uplift δ when the dry coat layer bends inward from its initial state towards the reservoir such that the angle θ between the center line in the thickness direction and the bottom wall is 90° is defined as the critical amount of uplift δ. θ=90° In this case, the thickness of the dry coat layer at the center of gravity is, in the following formula (1), the amount of lift δ is equal to the critical amount of lift δ θ=90° The value of the thickness tc at that point may be greater than or equal to the reference thickness. [Mathematics 1] Rise δ = (4 × F × L 3 ) / (E×b×tc 3 )...(1) F: Load applied to the center of gravity of the dry coat layer L: Height of the dry coat layer E: Young's modulus of the dry coat layer b: Width of the dry coat layer tc: Thickness of the dry coat layer at the center of gravity. [Effects of the Invention]

[0022] According to the tundish of the present invention, the dry coat layer is configured so that its thickness increases from the top to the bottom, thus increasing the thickness at the center of gravity of the dry coat layer without increasing the overall thickness of the dry coat layer. Increasing the thickness at the center of gravity of the dry coat layer effectively suppresses the occurrence of collapse of the dry coat layer due to thermal deformation. Furthermore, lowering the center of gravity of the dry coat layer can further enhance the effect of suppressing the occurrence of collapse of the dry coat layer. On the other hand, according to the tundish of the present invention, the thickness of the portion of the dry coat layer above the center of gravity can be reduced, thus reducing the volume of the dry coat layer that occupies within the storage portion of the tundish, and thus reducing the structural constraints of the tundish. In addition, by reducing the thickness above the center of gravity of the dry coat layer, the amount of dry coat material used can also be reduced.

[0023] The present invention can be realized in various forms other than tundishes. For example, the present invention can be realized in forms such as a method for designing a dry coat layer, a method for forming a dry coat layer, a method for manufacturing a tundish, or a method for casting using a tundish. [Brief explanation of the drawing]

[0024] [Figure 1] A schematic cross-sectional view showing the structure of a tundish. [Figure 2] A schematic cross-sectional view of the dry coat layer. [Figure 3] A first schematic diagram illustrating the mechanism of thermal deformation in conventional dry coat layers. [Figure 4] A second schematic diagram illustrating the mechanism of thermal deformation in conventional dry-coat layers. [Figure 5] An explanatory diagram showing the relationship between the amount of lifting δ and the thickness tc in the dry coat layer. [Figure 6] An explanatory diagram showing a table summarizing the collapse evaluations of the examples and comparative examples. [Figure 7] An explanatory diagram showing the collapse rate of the examples and comparative examples. [Modes for carrying out the invention]

[0025] Hereinafter, embodiments of the tundish according to the present invention will be described with reference to Figures 1 to 7 as appropriate.

[0026] Figure 1 is a schematic cross-sectional view showing a simplified configuration of the tundish 10 in this embodiment.

[0027] The tundish 10 is used, for example, in metal casting processes such as continuous casting. The tundish 10 is configured as a tank-shaped container and has a storage section 11 that can receive and temporarily store molten metal, which is a fluid molten metal. In continuous casting, molten metal is supplied from a ladle (not shown) through the storage section 11 of the tundish 10 to a mold (not shown).

[0028] The tundish 10 is configured such that when molten metal is supplied from the ladle to the reservoir 11, a flow is created in the molten metal in the reservoir 11 that causes impurities, such as inclusions, to float to the surface and separate. Furthermore, the tundish 10 is configured to allow the molten metal to be supplied to the mold with the inclusions that have floated to the surface removed from the reservoir 11.

[0029] Although not shown in the diagrams and detailed explanations, the storage section 11 of the tundish 10 may be divided into a receiving chamber for receiving molten metal and an outlet chamber into which the molten metal flows from the receiving chamber. The tundish 10 may also have a sleeve that constitutes a flow path for the molten metal, and a pair of trunnions provided on its outer surface.

[0030] The tundish 10 includes a container wall 20 that partitions the storage section 11. The container wall 20 includes a bottom wall portion 21 that forms the bottom surface of the storage section 11, and a side wall portion 22 that extends upward from the outer peripheral end of the bottom wall portion 21.

[0031] The bottom wall portion 21 is positioned along a horizontal direction perpendicular to the direction of gravity when the tundish 10 is in use. The bottom wall portion 21 has a nozzle hole 26 formed as a through hole for allowing the molten metal stored in the storage portion 11 to flow out to a mold or the like located downstream. In the tundish 10 of this embodiment, the nozzle hole 26 is formed at a position close to the lower end of the side wall portion 22. The nozzle hole 26 is formed in the vicinity of the lower end of the side wall portion 22.

[0032] The lower end of the side wall portion 22 intersects with the outer edge of the bottom wall portion 21. In the tundish 10, the side wall portion 22 is inclined outward relative to the storage portion 11. In the tundish 10 of this embodiment, an outlet 27 is formed at the upper end of the side wall portion 22. The outlet 27 is connected to piping such as a trough. When the tundish 10 is in use and more than a specified amount of molten metal is supplied to the storage portion 11, the excess molten metal is discharged to the outside of the tundish 10 through the outlet 27. This prevents the molten metal from overflowing from the upper end of the storage portion 11.

[0033] The container wall 20 has a multilayer structure and comprises a layer of steel shell 23 that constitutes the outer surface of the tundish 10, and a refractory layer 24 in which refractory material is lined to cover the inner wall surface of the steel shell 23. The refractory material constituting the refractory layer 24 is one that can withstand the temperature of the molten metal supplied to the tundish 10. The refractory material mainly consists of alumina (Al2O3), magnesia (MgO), or calcia (CaO). The refractory material has the form of a sheet, brick, or block and is attached in an arrangement that covers the inner wall surface of the steel shell. Insulation material may be placed between the steel shell 23 and the refractory layer 24.

[0034] When the tundish 10 is used, a dry coat layer 25, which is a coating layer, is formed on the surface of the refractory layer 24, that is, on the inner wall surfaces of the bottom wall portion 21 and the side wall portion 22 that face the storage portion 11. The dry coat layer 25 is made of a dry coat material. The dry coat material is made of, for example, about 90-95% by mass of MgO, an organic binder, and an inorganic binder.

[0035] The dry coat layer 25 is formed by filling the gap between a mold (not shown) and the refractory layer 24, which is placed in the storage section 11 of the tundish 10, with dry coat material, and then heating and firing the dry coat material. The dry coat layer 25 is formed before casting is carried out and is removed along with the cast residue after casting is completed.

[0036] In the following, for convenience, the dry coat layer formed on the bottom wall portion 21 of the tundish will be referred to as the "bottom wall dry coat layer," and the dry coat layer 25 formed on the side wall portion 22 will be referred to as the "side wall dry coat layer." The side wall dry coat layer 25s in this embodiment has a structure that can suppress collapse from the side wall portion 22 due to thermal deformation of the tundish 10, which will be described later. The details of the configuration of the side wall dry coat layer 25s in this embodiment will be described below.

[0037] Figure 2 is a schematic cross-sectional view showing an example of a sidewall dry coat layer 25s formed on the sidewall portion 22 of the tundish 10.

[0038] In this embodiment, the sidewall dry coat layer 25s is configured such that its thickness t gradually increases from its upper end to its lower end. In this specification, the thickness t of the sidewall dry coat layer 25s is the dimension in the horizontal direction (the direction along the surface of the bottom wall portion 21).

[0039] In this embodiment, the sidewall dry coat layer 25s is configured such that, when the thickness at the upper end is ta and the thickness at the lower end is tb, the thickness tc at the centroid position CP can be calculated using the following formula (A). tc = 2 × (ta 2+ta×tb +tb 2 ) / 3 × (ta + tb) ... (A)

[0040] The thickness ta at the upper end of the sidewall drycoat layer 25s may be, for example, the thickness in a range of approximately 10% of the height of the sidewall drycoat layer 25s from the upper end of the sidewall drycoat layer 25s. The thickness tb at the lower end of the sidewall drycoat layer 25s may be, for example, the thickness in a range of approximately 10% of the height of the sidewall drycoat layer 25s from the lower end of the sidewall drycoat layer 25s.

[0041] When molten metal is stored in the reservoir 11 of the tundish 10, the sidewall drycoat layer 25s undergoes thermal deformation such as expansion and contraction due to the heat of the molten metal. The inventors of this invention analyzed the mechanism of deformation of the sidewall drycoat layer 25s due to this thermal deformation and found that if the thickness tc at the center of gravity CP of the sidewall drycoat layer 25s is increased, the collapse of the sidewall drycoat layer 25s can be effectively suppressed. The details of this finding will be explained later using equation (1).

[0042] If the sidewall drycoat layer 25s is configured such that its thickness t increases from the top to the bottom, as described above, the thickness tc at the center of gravity CP of the sidewall drycoat layer 25s can be increased without increasing the overall thickness of the sidewall drycoat layer 25s. Increasing the thickness tc at the center of gravity CP makes it possible to effectively suppress the collapse of the sidewall drycoat layer 25s. Furthermore, if the thickness t above the center of gravity CP can be reduced, the volume of the sidewall drycoat layer 25s within the storage section 11 can be reduced accordingly, making it easier to secure the area for forming the sidewall drycoat layer 25s and reducing the structural constraints on the tundish 10. In addition, if the thickness t increases from the top to the bottom, the center of gravity CP of the sidewall drycoat layer 25s can be lowered, thus more effectively suppressing the collapse of the sidewall drycoat layer 25s. Moreover, since the thickness t above the center of gravity CP can be reduced, the amount of drycoat material used to constitute the drycoat layer 25 can also be reduced.

[0043] The thickness tb at the lower end of the sidewall drycoat layer 25s is preferably at least twice the thickness ta at the upper end, as shown in the embodiments described later. With this configuration, the thickness tc at the center of gravity CP of the sidewall drycoat layer 25s can be made larger, and the occurrence of collapse can be suppressed more effectively. In addition, the thickness ta at the upper end can be made smaller, making the structure of the tundish 10 less susceptible to structural constraints. Furthermore, the amount of drycoat material used can be reduced even further.

[0044] Preferably, the thickness tc of the sidewall drycoat layer 25s at the center of gravity CP is 1.5 times or more and less than 2.0 times the thickness ta at the upper end of the sidewall drycoat layer 25s. With this configuration, the thickness tc of the sidewall drycoat layer 25s at the center of gravity CP can be further optimized. Therefore, the effect of suppressing collapse of the sidewall drycoat layer 25s from the sidewall portion 22 can be further enhanced. In addition, the amount of drycoat material used can be further reduced.

[0045] In the following, the angle θ0 between the bottom wall 21 and the side wall 22 in the tundish 10 will also be referred to as the "side wall inclination angle θ0". As described above, since the side wall 22 is inclined toward the outside of the storage section 11, the inclination angle θ0 of the side wall 22 is greater than 90° (θ0 > 90°).

[0046] Furthermore, in the following, the angle θ between the center line CL and the bottom wall portion 21 in the thickness direction of the sidewall dry coat layer 25s in the initial state will also be referred to as the "inclination angle θ of the sidewall dry coat layer". "Initial state" means the state of the tundish 10 before use, and the state before molten metal is stored in the storage portion 11.

[0047] When the inclination angle θ of the sidewall dry coat layer 25s is expressed as θ0 + α (where α is a positive real number), it is preferable that α satisfies the inequality 0° < α < 5°, and more preferably 0° < α < 4°. α may also satisfy the inequality 0° < α < 3°. As shown in the embodiments described later, if the coat layer inclination angle θ is set to such an angle, the thickness t of the sidewall dry coat layer 25s can be increased more appropriately from the top to the bottom, and the collapse of the dry coat layer 25 can be suppressed more effectively.

[0048] Considering the mechanism of deformation of the sidewall drycoat layer 25s due to thermal deformation during use of the tundish 10, as shown in equation (1) below, the lower the height L of the sidewall drycoat layer 25s, the more effectively the collapse can be suppressed. Here, the height L of the sidewall drycoat layer 25s corresponds to the length of the sidewall drycoat layer 25s in the direction along the sidewall portion 22.

[0049] In this embodiment, the upper end of the sidewall dry coat layer 25s is formed at a lower position than the upper end of the sidewall portion 22, thereby reducing the height L of the sidewall dry coat layer 25s. Therefore, according to the configuration of the sidewall dry coat layer 25s in this embodiment, the occurrence of collapse of the sidewall dry coat layer 25s due to thermal deformation of the tundish 10 can be further suppressed. In addition, because the height of the sidewall dry coat layer 25s is lower, the amount of dry coat material used can be further reduced.

[0050] In the tundish 10 of this embodiment, an outlet 27 is formed at the upper end of the side wall portion 22, and the height position of the upper end of the side wall dry coat layer 25s corresponds to the position of the lower end of the outlet 27. With this configuration, the height L of the side wall dry coat layer 25s can be reduced to the position reached by the molten metal surface. Therefore, it is possible to reduce the amount of dry coat material used while ensuring the function of the side wall dry coat layer 25s as a coating layer, and to realize a structure that can further suppress the collapse of the side wall dry coat layer 25s.

[0051] The height position of the upper end of the side wall dry coat layer 25s is not limited to the position described above. In other embodiments, the height position of the upper end of the side wall dry coat layer 25s may be located above the lower end of the discharge port 27, or it may be approximately the same as the upper end of the side wall portion 22.

[0052] As described above, in this embodiment, a nozzle hole 26 is formed in the bottom wall portion 21 of the tundish 10 near the lower end of the side wall portion 22. A through hole communicating with the nozzle hole 26 is formed in the bottom wall dry coat layer 25b.

[0053] In this embodiment, the nozzle hole 26 is formed near the lower end of the sidewall dry coat layer 25s. According to the structure of the sidewall dry coat layer 25s of this embodiment described above, its collapse can be effectively suppressed while preventing its lower end from interfering with the nozzle hole 26.

[0054] Referring to Figures 3 and 4, the mechanism of thermal deformation when using the tundish 10 will be explained for a conventional sidewall dry coat layer 25a as a comparative example, and the reason why collapse can be suppressed by the configuration of the sidewall dry coat layer 25s of this embodiment will be explained.

[0055] Figures 3 and 4 illustrate a comparative example of a tundish 10a in which a sidewall dry coat layer 25a corresponding to the conventional configuration is formed. The comparative example tundish 10a is almost the same as the configuration of the tundish 10 described in Figure 1, except that the comparative example's sidewall dry coat layer 25a is formed instead of the sidewall dry coat layer 25s of this embodiment.

[0056] Figure 3 is a schematic cross-sectional view of the sidewall portion 22 on which the sidewall dry coat layer 25a of the comparative example is formed. Figure 4 is a schematic plan view showing the upper end surfaces of the sidewall portion 22 and the sidewall dry coat layer 25a. For convenience, the same hatching as shown in Figure 3 is applied to the upper end surfaces of the sidewall portion 22 and the sidewall dry coat layer 25a in Figure 4. In addition, in Figures 3 and 4, the position of the sidewall dry coat layer 25a when subjected to the thermal deformation described below is illustrated by a dashed line.

[0057] The configuration of the sidewall dry coat layer 25a of the comparative example is substantially the same as that of the sidewall dry coat layer 25s of this embodiment, except for the following point. In the sidewall dry coat layer 25a of the comparative example, the thickness t is formed to be substantially constant from the upper end to the lower end, and its inclination angle θ matches the inclination angle θ0 of the sidewall portion 22. In addition, the height position of the upper end of the sidewall dry coat layer 25a of the comparative example is substantially the same as the upper end of the sidewall portion 22.

[0058] When molten metal is supplied to the reservoir 11 of the tundish 10a, the sidewall drycoat layer 25a expands due to the heat received from the molten metal. Also, when the amount of molten metal in the tundish 10a decreases and the level of the molten metal drops, the sidewall drycoat layer 25a contracts as the surface temperature decreases.

[0059] As shown in Figure 3, the sidewall drycoat layer 25a is constrained to the sidewall portion 22 with its upper end open. Therefore, in the mechanical model of the sidewall drycoat layer 25a when it undergoes thermal deformation such as expansion and contraction caused by the heat of the molten metal, the dominant deformation is warping, which causes it to bend inward toward the reservoir portion 11, with the lower end connected to the bottom wall portion 21 acting as a fulcrum.

[0060] The inventors of the present invention have found that the mechanical model of the thermal deformation of such a sidewall drycoat layer 25a approximates the warping deformation of a cantilever beam, and therefore, it is possible to apply the mathematical formulas used in the mechanical analysis of the warping deformation of a cantilever beam in material mechanics.

[0061] Mathematical formula (1) below corresponds to a formula used in mechanical analysis of warp deformation of a cantilever beam in material mechanics. Note that mathematical formula (1) is derived by substituting mathematical formula (3) into mathematical formula (2) below. As will be described below, by using this mathematical formula (1), the structure of a dry coat layer that can suppress the occurrence of collapse while avoiding structural constraints of a tundish can be easily determined.

[0062] The "lifting amount δ" in mathematical formula (1) corresponds to the amount of warpage in the warp deformation of a cantilever beam. As shown in FIG. 3, the lifting amount δ represents the horizontal displacement of the position of the upper end of the side wall dry coat layer 25a when it warps inward of the reservoir 11 from the initial state. As shown in FIG. 4, it is preferable to use, as the lifting amount δ, the value at the central portion of the deflection where the deflection amount of the side wall dry coat layer 25a is maximum.

[0063] [Formula 1] Lifting amount δ=(4×F×L 3 ) / (E×b×tc 3 )…(1) F: Load applied to the center of gravity position of the side wall dry coat layer L: Height of the side wall dry coat layer E: Young's modulus of the side wall dry coat layer b: Width of the side wall dry coat layer (illustrated in FIG. 4). tc: Thickness at the center of gravity position of the side wall dry coat layer

[0064] [Formula 2] Lifting amount δ=(F×L 3 ) / (3×E×I)…(2) I: Second moment of area of the cross-section of the side wall dry coat layer.

[0065] [Formula 3] I=b×tc 3 / 12…(3)

[0066] As shown in equation (1) above, in the comparative example, increasing the thickness tc at the centroid position CP in the sidewall dry coat layer 25a reduces the amount of lifting δ. Reducing the amount of lifting δ can suppress the collapse of the sidewall dry coat layer 25a due to thermal deformation.

[0067] The above formula (1) is also applicable to the sidewall dry coat layer 25s of this embodiment. In the sidewall dry coat layer 25s of this embodiment, increasing the thickness tc at the center of gravity CP reduces the amount of uplift δ and suppresses the occurrence of collapse due to thermal deformation. Furthermore, if the sidewall dry coat layer 25s is considered as a single structure, it can be evaluated that a large moment is applied to the center of gravity CP when the amount of warping deformation of the sidewall dry coat layer 25s toward the storage section 11 becomes large. Therefore, it can be said that the effect of suppressing the occurrence of collapse is significantly increased by increasing the thickness tc at the center of gravity CP of the sidewall dry coat layer 25s.

[0068] In the comparative example, the thickness t of the sidewall drycoat layer 25a is almost constant from the top to the bottom. Therefore, increasing the thickness tc at the center of gravity CP will increase the thickness t at other points as well. Consequently, increasing the thickness t of the sidewall drycoat layer 25a in the comparative example may cause interference with the tundish structure or reduce the volume of the tundish. In addition, increasing the thickness t of the sidewall drycoat layer 25a in the comparative example will increase the amount of drycoat material used.

[0069] In contrast, with the sidewall drycoat layer 25s of this embodiment, the thickness t decreases towards the upper end, so even if the thickness tc at the center of gravity CP of the sidewall drycoat layer 25s is increased, the thickness t of the part above the center of gravity CP can be reduced. Therefore, even if the thickness tc at the center of gravity CP is increased to suppress collapse due to thermal deformation, interference between the part above the center of gravity CP and the structure of the tundish 10 can be suppressed. Furthermore, a decrease in the volume of the storage section 11 can be suppressed, and an increase in the amount of drycoat material used can also be suppressed.

[0070] Furthermore, with the sidewall dry coat layer 25s of this embodiment, the thickness t increases from the upper end to the lower end, which allows the position of the center of gravity CP of the sidewall dry coat layer 25s to be lowered. The lower the center of gravity CP, the smaller the load F applied to the center of gravity CP when the sidewall dry coat layer 25s bends toward the storage section 11. Therefore, it is easier to reduce the amount of uplift δ compared to the sidewall dry coat layer 25a of the comparative example, and collapse due to thermal deformation can be suppressed.

[0071] Figure 5 shows a graph illustrating the relationship between the amount of lift δ, obtained from the above formula (1), and the thickness tc of the sidewall drycoat layers 25a and 25s at the centroid position CP. In Figure 5, the sidewall drycoat layer 25s of this embodiment is shown by a solid line graph G1, and the sidewall drycoat layer 25a of the comparative example is shown by a dashed line graph G2. For the sidewall drycoat layers 25s and 25a, if the height L, width b, Young's modulus E, and load F are determined, the relationship shown in graphs G1 and G2 holds, and the thickness tc at the centroid position CP is uniquely determined for the amount of lift δ.

[0072] In both the comparative example's sidewall dry coat layer 25a and the embodiment's sidewall dry coat layer 25s, when the inclination angle θ exceeds 90° due to warping deformation, a downward load is likely to be generated at the upper end of the storage section 11, making collapse highly probable. Therefore, the amount of uplift δ when the inclination angle θ = 90° is defined as the "critical amount of uplift δ". θ=90° In the above equation (1), the amount of buoyancy δ is the critical amount of buoyancy δ θ=90° The thickness tc in this case is called the "reference thickness t rf We request it as ".

[0073] The thickness tc at the center of gravity CP is the reference thickness t rf If the above is done, the amount of lifting δ of the sidewall dry coat layers 25a and 25s will be the critical amount of lifting δ θ=90°This suppresses the occurrence of warping deformation that would reach a certain point, thereby reducing the possibility of collapse. Therefore, in the sidewall dry coat layer 25s of this embodiment, the thickness tc at the center of gravity position CP is equal to the reference thickness t rf It is preferable that the above conditions are met.

[0074] In the case of the sidewall dry coat layer 25s of this embodiment, the reference thickness t rf This can be obtained at a smaller value than the sidewall dry coat layer 25a of the comparative example having the same height L and width b. Therefore, in the sidewall dry coat layer 25s of this embodiment, the thickness tc is set to the reference thickness t rf As a result, it is possible to reduce the amount of drycoat material used while more effectively suppressing the occurrence of landslides.

[0075] As shown in equation (1) above, the amount of lifting δ can be reduced even when the height L of the sidewall dry coat layer 25a in the comparative example is reduced. In other words, by reducing the height L of the sidewall dry coat layer 25a in the comparative example, the collapse of the sidewall dry coat layer 25a due to thermal deformation can be suppressed. The same applies to the sidewall dry coat layer 25a in this embodiment.

[0076] However, in the case of the comparative example's sidewall dry coat layer 25a, even if the height L is reduced in the same way as the sidewall dry coat layer 25s of this embodiment, the above-mentioned reference thickness t rf However, this tends to be larger than the sidewall dry coat layer 25s of this embodiment. With the sidewall dry coat layer 25s of this embodiment, the height L is reduced while the reference thickness t is greater than that of the sidewall dry coat layer 25a of the comparative example. rf This can be made smaller. Therefore, it is possible to effectively suppress the occurrence of collapse while reducing the amount of dry coat material used compared to the side wall dry coat layer 25a of the comparative example.

[0077] As described above, the sidewall dry coat layer 25s of this embodiment has a novel structure in which the thickness t increases from the upper end to the lower end, so that the amount of dry coat material used can be reduced while effectively suppressing the occurrence of collapse. [Examples]

[0078] An embodiment of the tundish according to the present invention will be described with reference to Figures 6 and 7.

[0079] Figure 6 shows schematic diagrams of the sidewall drycoat shape, along with tables summarizing the thickness t(ta,tb,tc), the difference in inclination angle α, and the collapse evaluation value RV for each of Examples E1, E2, and Comparative Examples C1, C2. The tundish configurations of Examples E1, E2, and Comparative Examples C1, C2 are similar except for the difference in the configuration of the sidewall drycoat layer, as will be explained below.

[0080] Sidewall dry coat layer 25 of Example E1 E1 It has a shape similar to the sidewall dry coat layer 25s of the above embodiment, and is configured such that the thickness t increases from the upper end to the lower end. Sidewall dry coat layer 25 of Example E2 E2 Except for the fact that the height of its upper end is approximately the same as the upper end of the side wall portion 22 of the tundish, it has the same shape as the side wall dry coat layer 25s of the above embodiment, and, similar to embodiment E1, the thickness t increases from the upper end to the lower end.

[0081] Sidewall dry coat layer 25 of Comparative Example C1 C1 The sidewall dry coat layer 25a of the comparative example described in the above embodiment has a similar shape, and the thickness t is approximately the same from the upper end to the lower end. Also, the sidewall dry coat layer 25 of comparative example C1 C1 The height of its upper end was set to be approximately the same as the upper end of the side wall of the tundish. Side wall dry coat layer 25 of Comparative Example C2 C2 This is the sidewall dry coat layer 25 of Comparative Example C1. C1 Aside from being shorter in height and having a larger thickness t, the sidewall dry coat layer 25 of Comparative Example C1 is different. C1 It was given a similar shape.

[0082] Sidewall dry coat layer 25 of Examples E1 and E2 E1 ,twenty five E2In both cases, the thickness ta at the upper end was 30 mm, and the thickness tb at the lower end was 70 mm, meaning that the thickness tb at the lower end was more than twice the thickness ta at the upper end. Also, the sidewall dry coat layer 25 of Examples E1 and E2 E1 ,twenty five E2 In this case, the thickness tc at the center of gravity CP was 53 mm, which was within the range of 1.5 to less than 2.0 times the thickness ta at the upper end. In contrast, the side wall dry coat layer 25 of comparative examples C1 and C2 C1 ,twenty five C2 The thicknesses ta, tb, and tc were constant at 50mm and 70mm, respectively.

[0083] The difference in the inclination angle α in Figure 6 is, as explained in the above embodiment, the inclination angle θ of the side wall portion 22 of the tundish and the side wall dry coat layer 25 in the initial state. E1 ,twenty five E2 ,twenty five C1 ,twenty five C2 This is the difference from the inclination angle θ0. Side wall dry coat layer 25 of Examples E1 and E2 E1 ,twenty five E2 Therefore, α was 1.5°, which was greater than 0° and within the range of less than 5° (0° < α < 5°). Sidewall dry coat layer 25 of comparative examples C1 and C2 C1 ,twenty five C2 In both cases, α was 0°.

[0084] The sidewall dry coat layer 25 of Examples E1, E2, and Comparative Examples C1, C2 E1 ,twenty five E2 ,twenty five C1 ,twenty five C2 The width b was the same in all cases. Also, the side wall dry coat layer 25 of Example E1 E1 and the sidewall dry coat layer 25 of comparative example C2 C2 The heights were the same at L1. Side wall dry coat layer 25 of Example E2 E2 and the sidewall dry coat layer 25 of comparative example C1 C1 The heights were the same at L2 (L2 > L1).

[0085] Sidewall dry coat layer 25 of Examples E1 and E2 E1 ,twenty fiveE2 And the sidewall dry coat layer 25 of comparative example C2 C2 These were formed from the same dry coat material and had the same Young's modulus E. On the other hand, the sidewall dry coat layer 25 of Comparative Example C1 C1 Only this one was formed from a dry coat material with a different bulk density, and its Young's modulus E was smaller than that of Examples E1, E2, and Comparative Example C2.

[0086] The collapse evaluation value RV in Figure 6 will be explained. The collapse evaluation value RV is calculated using the thickness tc at the center of gravity CP and the reference thickness t as described in the above embodiment. rf This value is obtained as the difference between (RV=tc-t) rf ). The larger the collapse assessment value RV, the higher the standard thickness t. rf In contrast, the thickness tc at the center of gravity CP becomes larger, which reduces the likelihood of collapse. Furthermore, if the collapse evaluation value RV is positive, the thickness tc at the center of gravity CP is greater than the standard thickness t. rf Because it will be larger, it can be said that it will be able to more effectively suppress the occurrence of landslides.

[0087] In Example E1, the collapse evaluation value RV is +3 mm, and the thickness tc at the center of gravity CP is equal to the critical uplift amount δ, which can be obtained from formula (1) described in the above embodiment. θ=90° The reference thickness t in this case rf The above concludes the findings. The collapse evaluation value RV for Example E1 was the largest among Examples E1, E2, and Comparative Examples C1, C2. Therefore, the configuration of Example E1 is the most effective in suppressing the occurrence of collapse among the configurations of Examples E1, E2, and Comparative Examples C1, C2.

[0088] In Example E2, the collapse evaluation value RV was -6 mm, while in Example E1, the collapse evaluation value RV was higher. This indicates that, in a configuration where the thickness of the sidewall drycoat layer increases from the top to the bottom, a lower height configuration can further suppress the occurrence of collapse.

[0089] In Comparative Example C1, the collapse evaluation value RV was -31 mm, which was significantly lower than that of Examples E1 and E2. This suggests that even when considering the difference in Young's modulus E between Examples E1 and E2, the dry coat layer 25 of Examples E1 and E2 is lower. E1 ,twenty five E2 The dry coat layer 25 of comparative example C1 C1 It is clear that this method can suppress the occurrence of landslides.

[0090] Here, the collapse evaluation value RV for Comparative Example C2 was +1 mm, which was higher than the collapse evaluation value RV for Example E2. However, the side wall dry coat layer 25 of Comparative Example C2 C2 Therefore, the thickness t from the top to the bottom is 70 mm, and its volume is very large, indicating that the volume of the tundish reservoir is significantly reduced, and that a large amount of drycoat material is used.

[0091] In contrast, the sidewall dry coat layer 25 of Example E2 E2 Although the thickness tb at the lower end is 70 mm, the thickness ta at the upper end is less than half that, at 30 mm. Sidewall dry coat layer 25 of Example E2 E2 Therefore, it can be said that the reduction in the volume of the tundish storage area is suppressed, and the amount of drycoat material used is also reduced.

[0092] Thus, considering only the collapse evaluation value RV, it can be said that the occurrence of collapse can be suppressed by increasing the thickness t and decreasing the height L, as in Comparative Example C2. However, from the viewpoint of suppressing the occurrence of collapse while suppressing the reduction of the volume of the tundish storage area and the increase in the amount of dry coat material used, it is clear that a configuration in which the thickness t increases from the top to the bottom, as in Examples E1 and E2, is preferable.

[0093] Figure 7 shows a histogram comparing the collapse rates of Example E1 and Comparative Example C1. When the collapse rate of Comparative Example C1 is set to 1, the collapse rate of Example E1 was reduced to 0.43.

[0094] As described above, a tundish having the sidewall dry coat layer configuration according to the present invention can effectively suppress the occurrence of collapse while suppressing an increase in the amount of dry coat material used.

[0095] The present invention is not limited to the configurations of the embodiments and examples described above, and can be modified without impairing its technical significance. [Explanation of symbols]

[0096] 10...Tundish, 10a...Tundish of the comparative example, 11...Storage section, 20...Container wall, 21...Bottom wall, 22...Side wall, 23...Steel shell, 24...Refractory layer, 25...Dry coat layer, 25a...Side wall dry coat layer of the comparative example, 25b...Bottom wall dry coat layer, 25s...Side wall dry coat layer, 25 C1 ,twenty five C2 ...Comparative example: Sidewall dry coat layer, 25 E1 ,twenty five E2 ...Side wall dry coat layer of comparative example, 26...Nozzle hole, 27...Discharge port, CL...Center line, CP...Center of gravity

Claims

1. A side wall section that partitions the storage area where molten metal is stored, Intersecting the lower end of the side wall portion, the bottom wall portion which constitutes the bottom of the storage portion, A dry coat layer formed on the inner wall surface of the side wall portion facing the storage portion, Equipped with, The dry coat layer is formed such that its thickness increases from the top to the bottom of the tundish.

2. The tundish according to claim 1, wherein the thickness of the lower end of the dry coat layer is at least twice the thickness of the upper end of the dry coat layer.

3. The tundish according to claim 2, wherein the thickness of the dry coat layer at the center of gravity is 1.5 times or more and less than 2.0 times the thickness of the upper end of the dry coat layer.

4. The angle between the side wall portion and the bottom wall portion is θ ０ In this case, the angle θ between the center line in the thickness direction of the dry coat layer and the bottom wall in the initial state is θ ０ The tundish according to claim 1, wherein the angle is +α (0° < α < 5°).

5. The tundish according to claim 1, wherein the upper end of the dry coat layer is formed at a lower position than the upper end of the side wall portion.

6. The tundish according to claim 5, wherein an outlet is formed at the upper end of the side wall portion for discharging the molten metal exceeding a specified amount in the storage portion, and the height position of the upper end of the dry coat layer corresponds to the position of the lower end of the outlet.

7. The tundish according to claim 1, wherein a nozzle hole for discharging the molten metal from the storage portion is formed in the bottom wall portion near the lower end of the dry coat layer.

8. The amount of displacement of the upper end of the dry coat layer when the dry coat layer bends inward from its initial state towards the storage portion is defined as the amount of lift δ. The amount of lift δ when the dry coat layer bends inward from its initial state to the storage portion such that the angle θ between the center line in the thickness direction and the bottom wall portion becomes 90° is defined as the critical amount of lift δ. θ＝９０° In that case, The thickness of the dry coat layer at the center of gravity is given by the following formula (1), where the lift amount δ is equal to the critical lift amount δ θ＝９０° A tundish according to any one of claims 1 to 7, wherein the thickness tc is greater than or equal to the reference thickness, which is the value of the thickness tc at that time. [Mathematics 1] Rise amount δ = (4 × F × L) ３ ) / (E×b×tc ３ ) ... (1) F: Load applied to the center of gravity of the dry coat layer L: Height of the dry coat layer E: Young's modulus of the dry coat layer b: Width of the dry coat layer tc: Thickness of the dry coat layer at the center of gravity.

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