Long nozzle support holder and continuous casting method using same

Abstract

To provide a long nozzle support holder which can be safely mounted to a long nozzle, and a continuous casting method using the same.SOLUTION: When performing a continuous casting while pouring a molten metal from a ladle into a tundish using a long nozzle, the long nozzle is mounted to a long nozzle support holder. The long nozzle support holder comprises a support holder main body which is positioned at an outer peripheral side and placed on a long nozzle attaching / detaching device, and a long nozzle mounting member which is positioned at an inner peripheral side and to which the long nozzle is directly mounted. The long nozzle mounting member is divided into two or more pieces in a circumferential direction. The present invention also relates to a method by which, via the long nozzle support holder including the long nozzle mounting member, the long nozzle is installed between the ladle and the tundish, and the molten metal is poured from the ladle into the tundish.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a long nozzle support holder to which a long nozzle is attached when continuous casting is performed while pouring molten metal from a ladle into a tundish using the long nozzle, and to a continuous casting method using the same. [Background technology]

[0002] In continuous casting, as shown in an example in Figure 2, molten metal (molten steel) 10 is poured from a ladle 11 into a tundish 14. At this time, the upper end of a refractory nozzle called a long nozzle (also known as an air seal pipe) 13 is attached to a molten metal spout (sliding nozzle 12) at the bottom of the ladle 11. Then, the molten metal is poured while the lower end of the long nozzle 13 is immersed in the molten metal (molten steel) 10 in the tundish 14.

[0003] When the molten metal (molten steel) 10 in the ladle 11 is used up, the long nozzle 13 is removed from the sliding nozzle 12 at the bottom of the ladle 11, and the ladle 11 is replaced with a ladle filled with molten metal 10 using a swing tower (not shown) or the like, and the long nozzle 13 is reattached to the sliding nozzle 12 at the bottom of the ladle 11. Then, the molten metal 10 is poured into the tundish 14. This allows continuous casting, improving quality and productivity.

[0004] In this way, a long nozzle attachment / detachment device 15 is used when attaching or detaching the long nozzle 13 to or from the sliding nozzle 12 at the bottom of the ladle 11. In this case, as shown in Figures 2 and 3, the upper end (fitting portion) of the long nozzle 13 is usually attached to a long nozzle support holder 20, and the long nozzle support holder 20 is set on the tip end (receiving portion) 15b of an arm 15a of the long nozzle attachment / detachment device 15. In Figure 3, (a) is a schematic side cross-sectional view, (b) is a schematic front view, (c) is a schematic top view, and (d) is a partially enlarged cross-sectional view.

[0005] When molten metal is poured from the ladle 11 into the tundish 14 using the long nozzle 13, any gap between the fitting of the long nozzle 13 and the sliding nozzle 12 at the bottom of the ladle 11 could result in leakage of the molten metal. Additionally, air could be trapped in the molten metal through the gap, deteriorating the quality of the molten metal. As the molten metal 10 flows down through the long nozzle 13, the flow of molten metal exerts a downward force on the long nozzle 13. Therefore, the long nozzle 13 is pressed against the sliding nozzle 12 at the bottom of the ladle 11 to prevent gaps from forming. Furthermore, if there is a gap between the long nozzle 13 and the long nozzle support holder 20, the long nozzle 13 cannot be securely fixed even when pressed against the sliding nozzle 12. Therefore, a long nozzle mounting member 22, to which the long nozzle 13 is directly attached, is installed as a filler in the long nozzle support holder 20.

[0006] After casting is complete, the long nozzle mounting member 22 and support holder body 21 are removed from the long nozzle 13. The support holder body 21 and long nozzle mounting member 22 are attached to a new long nozzle 13 and reused. During casting, the long nozzle 13 is pressed against the sliding nozzle 12 at the bottom of the ladle 11 by lifting the long nozzle support holder 20 with the long nozzle support device 15. The upper periphery of the long nozzle 13 has a trumpet shape that widens toward the top. Therefore, when the long nozzle 13 is pressed against the sliding nozzle 12, the gap between the long nozzle 13 and the support holder body 21 narrows. This causes the long nozzle mounting member 22 located between them to be compressed. Furthermore, the support holder body 21 and the long nozzle 13 expand due to the high-temperature molten metal 10, causing the long nozzle mounting member 22 to become stuck. Therefore, after casting is complete, it is difficult to remove the long nozzle mounting member 22 and support holder body 21 from the long nozzle 13 without applying an external force.

[0007] Patent Document 1 discloses a long nozzle support holder for continuous casting that smoothly follows the movement of the long nozzle and has a long life. The long nozzle support holder has a spherical bearing inside that combines a convex spherical seat and a steel ball, and is equipped with air blowing means for blowing air to the spherical bearing. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-083775 Summary of the Invention [Problem to be solved by the invention]

[0009] When removing the long nozzle mounting member 22 or the support holder body 21, an external force is applied to the long nozzle mounting member 22 from above the long nozzle 13. If a large hammer 23 is used during this process, as shown in Figure 4, the upper parts of the long nozzle mounting member 22 and the support holder body 21 are deformed. If the deformed long nozzle mounting member 22 or the support holder body 21 are reused, a gap will form between the long nozzle 13 fitting and the sliding nozzle 12 at the bottom of the ladle 11. Air is drawn into this gap and becomes entrained in the molten metal 10 flowing from the ladle 11 to the tundish 14. This phenomenon of air being entrained in the molten metal actually occurs several times per three months. Oxygen and nitrogen, which are components of air, are impurities and standard amounts are established for each steel grade. When air is entrained, the composition of the molten metal is measured. If the molten metal contains more than the standard amount of air, the resulting cast piece is deemed defective.

[0010] Furthermore, the assembly work of the support holder main body 21 and the long nozzle mounting member 22 to the long nozzle 13 involves irregular work, such as manually lifting the heavy long nozzle mounting member 22, posing safety concerns such as pinching of fingers. Furthermore, when removing the long nozzle mounting member 22 from a used long nozzle 13, if the long nozzle mounting member 22 is strongly attached to the long nozzle 13, a large impact force is required. In such cases, a large hammer weighing approximately 6 kg is used, which reduces the safety of the work. However, Patent Document 1 does not disclose the structure of the long nozzle mounting member 22.

[0011] SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a long nozzle support holder that can be safely attached to a long nozzle by hand, and a continuous casting method using the same. [Means for solving the problem]

[0012] The long-nozzle support holder of the present invention, which advantageously solves the above-mentioned problems, is a long-nozzle support holder to which a long nozzle is attached when continuous casting is performed while pouring molten metal from a ladle into a tundish using the long nozzle, and is characterized in that it comprises a support holder main body located on the outer periphery and placed on a long-nozzle attachment / detachment device, and a long-nozzle attachment member located on the inner periphery and to which the long nozzle is directly attached, and the long-nozzle attachment member is divided into two or more parts in the circumferential direction.

[0013] The continuous casting method of the present invention, which advantageously solves the above-mentioned problems, is characterized in that a long nozzle is installed between a ladle and a tundish via a long nozzle support holder having the long nozzle mounting member, and molten metal is poured from the ladle into the tundish. [Effects of the Invention]

[0014] According to the long-nozzle support holder of the present invention, the long-nozzle mounting member is divided, making each divided piece lightweight and reducing the need to handle heavy objects during installation and disassembly. Additionally, the adhesive force between the long nozzle and the long-nozzle mounting member is reduced, reducing the need for hammer striking, thereby suppressing deformation of the support holder body and the long-nozzle mounting member. This increases the recycling rate of the long-nozzle mounting member, and improves adhesion between the long nozzle and the ladle's sliding nozzle, thereby improving the quality of the cast slab. This is extremely useful industrially, contributing to improved safety, productivity, and quality in continuous casting. [Brief explanation of the drawings]

[0015] [Figure 1] 1A and 1B are conceptual diagrams illustrating a long nozzle mounting member according to one embodiment of the present invention, in which (a) is a perspective view showing a two-piece type, (b) is a perspective view showing a three-piece type, (c) is a perspective view showing a four-piece type, and (d) is a cross-sectional conceptual diagram showing the divided pieces. [Figure 2] FIG. 2 is a diagram showing a state in which molten metal is poured from a ladle into a tundish. [Figure 3] 1A and 1B are diagrams showing the state in which a long nozzle is attached to a long nozzle support holder, in which (a) is a schematic side cross-sectional view, (b) is a schematic front view, (c) is a schematic top view, and (d) is a partially enlarged cross-sectional view. [Figure 4] This shows the work of dismantling the support holder body and the long nozzle mounting member by hammering after use. [Figure 5] 10 is a graph showing the effect of the long nozzle mounting member according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] The following describes in detail embodiments of the present invention. Note that the drawings are schematic and may differ from the actual embodiments. Furthermore, the following embodiments exemplify devices and methods for embodying the technical concept of the present invention, and are not intended to limit the configuration to those described below. In other words, the technical concept of the present invention can be modified in various ways within the technical scope described in the claims.

[0017] FIG. 1 is a conceptual diagram illustrating a long nozzle mounting member according to one embodiment of the present invention. FIG. 1(a) is a perspective view of a long nozzle mounting member 22 divided into two equal parts in the circumferential direction. FIG. 1(b) is a perspective view of a long nozzle mounting member 22 divided into three equal parts in the circumferential direction. FIG. 1(c) is a perspective view of a long nozzle mounting member 22 divided into four equal parts in the circumferential direction. FIG. 1(d) is a schematic cross-sectional view of one divided piece 22A of the long nozzle mounting member 22. The individual divided pieces 22A are combined with pieces of the same shape to form a roughly circular ring shape. The inner periphery is attached to the top of the long nozzle 13, and the outer periphery is surrounded and supported by a support holder 21.

[0018] The long-nozzle mounting member 22 is divided into two or more segments. It is preferable that the segments 22A be equally divided and have the same shape. By dividing the long-nozzle mounting member 22, the weight of each segment 22A is reduced by half or more. This reduces the workload required to manually handle the long-nozzle mounting member 22. Furthermore, the area of ​​each segment 22A that adheres to the long nozzle is reduced by half or more, and the adhesive strength per segment is reduced by half or more. This reduces the effort required to remove the long-nozzle mounting member 22 when disassembling the long nozzle 13 from the support holder 20. For example, the long-nozzle mounting member 22 can be removed by striking it with a lightweight hammer weighing 3 kg or less, rather than a large hammer weighing approximately 6 kg. The number of segments is preferably three or more, and more preferably four or more. While there is no upper limit to the number of segments, having too many segments increases the workload required to attach the long nozzle 13. Therefore, it is preferable to set the number of segments to 10 or less, more preferably six or less, and even more preferably four or less.

[0019] The long nozzle mounting member 22 of this embodiment can be released with little or no impact force, allowing it to be disassembled and recovered without deforming the support holder body 21 or the long nozzle mounting member 22. Therefore, even if the recovered support holder body 21 or the long nozzle mounting member 22 is reused to attach it to the long nozzle 13, it can be pressed against the fitting portion of the long nozzle 13 without creating a gap between the fitting portion of the long nozzle 13 and the sliding nozzle 12 of the ladle 11. This makes it possible to prevent air from being mixed into the molten metal, allowing for the casting of a high-quality cast slab.

[0020] In this embodiment, the molten metal is molten steel, and it is preferable to apply this embodiment to continuous casting of steel. Molten steel is at a high temperature, and the adhesive strength between the long nozzle 13 and the long nozzle mounting member 22 increases due to thermal expansion of the long nozzle 13, the support holder body 21, and the long nozzle mounting member 22. Therefore, this embodiment is useful.

[0021] In addition, a spherical seat or a steel ball may be disposed between the support holder body and the long nozzle mounting member in this embodiment to form a spherical bearing. Also, a means for blowing air onto the spherical bearing may be provided.

[0022] The effect of the segmented long nozzle mounting member according to this embodiment is shown in Figure 5. The frequency with which a 6 kg large hammer was required to dismantle the long nozzle and long nozzle support holder after continuous steel casting was expressed as a percentage, representing the rate of occurrence of irregular work. The number of boiling occurrences was evaluated by counting the number of times per period (3 months) that air sucked into the long nozzle appeared as bubbles on the surface of the molten metal in the tundish. By replacing the conventional one-piece long nozzle mounting member with a two-segment long nozzle mounting member, the irregular work of dismantling using a large hammer was reduced from 100% to half. The rate of irregular work decreased with each increase in the number of segments, and the use of a four-segment long nozzle mounting member did not require the use of a large hammer.

[0023] The reason for this is presumably that, by dividing the long nozzle mounting member into multiple pieces, the contact area between the long nozzle and the long nozzle mounting member per segment is reduced, reducing the external force required to separate the long nozzle mounting member from its adhered state. By applying this embodiment, the long nozzle mounting member and support holder are no longer deformed, and the occurrence of a gap between the long nozzle and the sliding nozzle is suppressed. As a result, the intrusion of air into the molten metal is suppressed, improving the yield of the cast slab.

[0024] The long nozzle mounting member is made of, for example, stainless steel cast steel SCH13. The impact force of a 6 kg large hammer is considered to be a stress of approximately 650 N. The yield strength of SCH13 is 235 N / mm 2 If the impact of the large hammer is concentrated in a small area of ​​the long nozzle mounting member, the strength of the long nozzle mounting member may be exceeded. In this case, the long nozzle mounting member will be deformed. In this embodiment, by dividing the long nozzle mounting member into three or four parts in the circumferential direction, the adhesive strength of each part can be reduced to one-third or one-quarter. For example, a striking force of 220 N from a 3 kg hammer is sufficient to disengage the adhesive of the long nozzle mounting member. Therefore, dismantling work can be carried out without deforming the long nozzle mounting member. [Explanation of symbols]

[0025] 10 Molten metal (molten steel) 11 Ladle 12 Sliding Nozzle 13 Long nozzle 14 Tundish 15 Long nozzle attachment / detachment device (long nozzle support device) 15a Long nozzle attachment / detachment device arm 15b Receptacle for long nozzle attachment / detachment device 20 Long nozzle support holder 21 Support holder body 22 Long nozzle mounting member 22A (Long nozzle mounting part) division piece 23 Hammer

Claims

1. A long nozzle support holder to which a long nozzle is attached when continuous casting is performed while pouring molten metal from a ladle into a tundish using the long nozzle, A long nozzle support holder comprising a support holder body located on the outer periphery and placed on a long nozzle attachment / detachment device, and a long nozzle attachment member located on the inner periphery and to which the long nozzle is directly attached, the long nozzle attachment member being made of stainless cast steel and divided into two or more parts in the circumferential direction.

2. A continuous casting method, comprising: installing a long nozzle between a ladle and a tundish via a long nozzle support holder having the long nozzle mounting member according to claim 1; and pouring molten metal from the ladle into the tundish.

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