Dipping nozzle

Abstract

The purpose of the present invention is to suppress both the occurrence of cracks in the neck and the occurrence of sinks in an immersion nozzle applied to an immersion nozzle replacement device. Specifically, the immersion nozzle (10) is provided with a bridging member (15) in such a manner that the inner peripheral surface of a metal shell (13A) surrounding a flange portion (12) and the outer peripheral surface of a nozzle body portion (11) are bridged. One end of the bridge member (15) is fixed to the metal case (13A), and the other end of the bridge member (15) engages with a recess (11c) provided on the outer peripheral surface of the nozzle body (11). Furthermore, the outer peripheral surface of the nozzle body (11) is formed in a shape that extends in the vertical direction with respect to the center axis of the inner hole (11a) and is not subjected to dimensional change, excluding the recess (11c), above the point of force of the upward support force of the support of the immersion nozzle replacement device.

Description

Technical Field

[0001] The present invention relates to an immersion nozzle used when pouring molten steel from a tundish into a casting mold in continuous casting of steel. Background Art

[0002] In order to replace the immersion nozzle, the continuous casting operation of steel must be interrupted or terminated due to wear caused by molten steel, endurance limit caused by adhesion and accumulation of inclusions such as non-metallic aluminum oxide particles in the molten steel, closure of the inner hole, cracks and breakage. However, in order to improve the working efficiency, as a method for achieving long-term injection, a device that can replace the immersion nozzle with a new immersion nozzle without interrupting the continuous casting operation of steel has been introduced (for example, Patent Documents 1 and 2).

[0003] The basic structure of the immersion nozzle used in such an immersion nozzle replacement device can be roughly divided into two parts, namely: a cylindrical nozzle body part having an inner hole, a path for the molten steel to pass through, in the vertical direction; and a flange part, which is supported from below by a support member of the immersion nozzle replacement device in order to support the nozzle body part relative to gravity and push it upward to contact the upper part (upper nozzle part), and the cross-sectional area is expanded in the horizontal direction. Moreover, the boundary part where the cross-sectional area is enlarged is called a neck.

[0004] The neck is known to be a stress concentration part in the structure, and cracks may occur due to the thermal stress and mechanical stress. The cracks in the neck will become a problem for the service life of the immersion nozzle and the quality of the steel. Since the molten steel flows in the inner hole of the immersion nozzle, the pressure level of the inner hole space tends to be negative pressure, and as a result, air is sucked in from the cracks in the neck, causing the carbon component constituting the refractory to oxidize, resulting in the possibility of steel leakage, and there is also the possibility that the steel is contaminated by oxygen.

[0005] Therefore, the present inventors disclosed in Patent Document 3 an immersion nozzle having a shape which is called a neck portion in a nozzle body portion and in which the cross-sectional area does not change.

[0006] Patent Literature Patent Document 1: Japanese Patent No. 2793039 Patent Document 2: Japanese Patent Publication No. 4-50100 Patent Document 3: Japanese Patent No. 6122393 Summary of the invention

[0007] In the patent document 3 Figure 1When the immersion nozzle shown was put to actual operation and tested, the inventors found that although the problem of cracks in the neck could be eliminated, a new problem occurred, namely the sinking of the nozzle body. When the nozzle body sinks, a gap is generated at the joint with the upper part (upper nozzle part), which is the main cause of the reduction in steel quality or the melting loss of refractory materials due to air entrainment. In addition, it is the main cause of major failures that affect the operation due to leakage.

[0008] Therefore, the technical problem to be solved by the present invention is to take into account both the suppression of the occurrence of cracks in the neck and the suppression of the occurrence of sinking of the submerged nozzle in the submerged nozzle used in the submerged nozzle replacement device.

[0009] According to one aspect of the present invention, the following immersion nozzle is provided. An immersion nozzle comprises: a nozzle body portion, which is made of a refractory material and has an inner hole in the vertical direction; and a flange portion, which is made of a flat refractory material, and the flat refractory material is directly joined to the outer periphery of the upper end portion of the nozzle body portion in a manner of surrounding the outer periphery of the upper end portion of the nozzle body portion and protruding in the horizontal direction, or is joined to the outer periphery of the upper end portion by an adhesive, the outer periphery of the flange portion and a part of the nozzle body portion below it is surrounded by a metal shell, the upper end surfaces of the nozzle body portion and the flange portion are located in the same horizontal plane, the lower side of the flange portion is supported by a support member so as to slide in the horizontal direction, and the upper end surfaces of the nozzle body portion and the flange portion are arranged to be joined together with the lower end surface of an upper nozzle component located above the immersion nozzle, It is characterized in that A bridging member is provided to bridge the inner peripheral surface of the metal shell surrounding the flange portion and the outer peripheral surface of the nozzle body portion, one end of the bridging member is fixed to the metal shell, and the other end is engaged with a recessed portion provided on the outer peripheral surface of the nozzle body portion. Above the point of force of the upward supporting force of the support member, the outer peripheral surface of the nozzle body, excluding the recessed portion, extends in a vertical direction with respect to the central axis of the inner hole without any dimensional change.

[0010] According to the present invention, in a submerged nozzle used in a submerged nozzle replacement device, it is possible to suppress both the occurrence of cracks in the neck and the occurrence of sinking of the submerged nozzle. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a longitudinal sectional view of the immersion nozzle which is one embodiment of the present invention. Figure 2 Yes means Figure 1 A longitudinal sectional view of the main part of the immersion nozzle in use ( Figure 1 AA direction section). Figure 3 yes Figure 1 Top view of the immersion nozzle. Figure 4 This is a longitudinal sectional view of a conventional immersion nozzle. Explanation of symbols 10, 10'-immersion nozzle; 11-nozzle body; 11a-inner hole; 11b-discharging hole; 11c-recess; 12-flange; 13-metal shell; 13A-metal shell surrounding the flange; 13a-support part (pin); 14-joining material; 15-bridging member (pin); 20-support member; 30-upper nozzle member DETAILED DESCRIPTION

[0012] Figure 1 is a longitudinal sectional view of an immersion nozzle according to one embodiment of the present invention, Figure 2 Yes means Figure 1 A longitudinal sectional view of the main parts of the immersion nozzle in use, Figure 3 yes Figure 1 Top view of the immersion nozzle. The immersion nozzle 10 has a nozzle body 11 and a flange 12. The nozzle body 11 is made of a refractory (shaped refractory) and has an inner hole 11a in the vertical direction as a passage for molten steel. At the same time, at the lower end, a discharge hole 11b is provided at a symmetrical position in order to discharge the molten steel into the mold. The flange 12 is made of a refractory different from the nozzle body 11 (a cast-molded refractory in this embodiment). The flange 12 is flat-plate-shaped, and specifically, is directly joined to the upper end of the nozzle body 11 or joined to the outer periphery of the upper end of the nozzle body 11 by an adhesive in a manner that surrounds the outer periphery of the upper end of the nozzle body 11 and protrudes in the horizontal direction. The upper end surfaces of the nozzle body 11 and the flange 12 are located in the same horizontal plane. Moreover, the outer periphery of the flange 12 and a portion of the nozzle body 11 below it is surrounded by a metal shell 13. Furthermore, a joint material 14 (for example, an amorphous refractory material such as mortar, a fiber sheet, etc.) is interposed between the metal shell 13 and the nozzle body 11 .

[0013] like Figure 2 As shown, the immersion nozzle 10 is provided and used in the following manner, that is, by supporting the lower side of the flange portion 12 of the immersion nozzle 10 with the support member 20 of the immersion nozzle replacement device and sliding it in the horizontal direction, the upper end surface of the nozzle body 11 and the flange portion 12 are simultaneously engaged with the lower end surface of the upper nozzle member 30 located above the immersion nozzle 10. In addition, the sinking of the immersion nozzle (nozzle body) mentioned above refers to the phenomenon that the nozzle body 11 is displaced and dropped downward due to the reaction force of the upward supporting force of the support member 20.

[0014] In the above basic structure, Figure 1 and Figure 3 As shown in FIG. 1 , the immersion nozzle 10 of the present invention includes a bridge member 15 extending in the horizontal direction so as to bridge the inner peripheral surface of the metal shell 13A surrounding the flange portion 12 and the outer peripheral surface of the nozzle body portion 11. One end of the bridge member 15 is fixed to the metal shell 13A, and the other end is engaged with a recessed portion 11c provided on the outer peripheral surface of the nozzle body portion 11. By providing the bridge member 15 in this manner, the sinking of the nozzle body portion 11 can be suppressed.

[0015] Furthermore, in the present invention, in order to suppress the occurrence of cracks in the neck, the support member 20 is provided at a position higher than the force point P of the upward supporting force (higher than the support member 20). Figure 2 The outer peripheral surface of the nozzle body 11, except for the recessed portion 11c, extends in the vertical direction relative to the central axis C of the inner hole 11a without any dimensional change.

[0016] In this embodiment, if Figure 3 As shown in FIG. 1 , the bridge member 15 is not disposed in the vertical region where the force point P of the support member 20 has an upward support force. In this way, by not disposing the bridge member 15 in the vertical region where the force point P has an upward support force, it is possible to prevent the upward support force from directly acting on the bridge member 15 and the concave portion 11c on the outer peripheral surface of the nozzle body 11. Thus, the occurrence of cracks in the neck can be further suppressed. In addition, in the present embodiment, the bridge members 15 are arranged at two locations so as to be rotationally symmetrical with the central axis C of the inner hole 11a as the rotation axis. In this way, by arranging the plurality of bridge members 15 so as to be rotationally symmetrical with the central axis C of the inner hole 11a as the rotation axis, the sinking of the nozzle body 11 can be effectively suppressed.

[0017] In this embodiment, the bridge member 15 is a cylindrical pin, and correspondingly, the recessed portion 11c provided on the outer peripheral surface of the nozzle body 11 is circular. Thus, by making the bridge member 15 cylindrical and the recessed portion 11c circular, stress is not easily concentrated on the bridge member 15 and the recessed portion 11c, and the generation of cracks in the neck can be further suppressed. However, the shapes of the bridge member 15 and the recessed portion 11c are not limited to cylindrical or circular shapes, and may be, for example, shapes extending in the circumferential direction of the nozzle body 11. On the other hand, since the recessed portion 11c provided on the outer circumferential surface of the nozzle body 11 may become a stress concentration portion on the nozzle body 11, it is preferred that the ratio of the circumference of the recessed portion 11c (the total circumference in the case of a plurality of recessed portions 11c) to the circumference of the nozzle body 11 be 20% or less, and more preferably 10% or less.

[0018] In addition, if Figure 3As shown, in this embodiment, the top view shape of the flange portion 12 is octagonal, but it can also be rectangular, polygonal, elliptical or circular. In addition, the top view shape of the nozzle body portion 11 is not limited to circular, for example, it can also be rectangular or elliptical.

[0019] The submerged nozzle 10 of the present invention can be produced, for example, by the following method. First, as a preparation for manufacturing, one end of the bridge member 15 is fixed to the metal shell 13. Specifically, a through hole for mounting one end of the bridge member 15 is provided in the metal shell 13, and one end of the bridge member 15 is mounted in the through hole and fixed by welding, etc. In addition, a recess 11c for engaging the other end of the bridge member 15 is provided on the outer peripheral surface of the nozzle body 11. After the preparation for manufacturing is completed, the other end of the bridge member 15 is engaged with the recess 11c provided on the outer peripheral surface of the nozzle body 11, and the metal shell 13 is installed around the nozzle body 11. Thereafter, a cast refractory is filled between the nozzle body 11 and the metal shell 13 to form the flange 12. At this time, the upper end surfaces of the nozzle body 11 and the flange 12, which are the joint surfaces with the lower end surface of the upper nozzle member 30, are located at a position protruding upwards more than the upper end of the metal shell 13, and the upper end surfaces of the nozzle body 11 and the flange 12 are machined in such a way as to form the same horizontal plane.

[0020] Thus, by forming the flange 12 with a cast-molded refractory, the bridge member 15 can be set in the flange 12 without a gap. In addition, since the cast-molded refractory is also filled in the recess 11c that engages the other end of the bridge member 15 during manufacturing, the other end of the bridge member 15 can be engaged with the recess 11c without a gap. Thus, the occurrence of cracks in the neck and the sinking of the immersion nozzle can be effectively suppressed.

[0021] Although the embodiment of the present invention has been described above, the present invention is not limited thereto. For example, in the present embodiment, the flange portion 12 is formed of a cast refractory, but may be formed of a shaped refractory. In addition, the nozzle body 11 is simplified for convenience and the same and integrated structure is illustrated, but the present invention is not limited to such an identical and integrated structure. For example, a refractory different from the refractory applied to the nozzle body 11 other than these may be used near the peripheral portion of the powder portion of the mold, a part or all of the inner hole surface, or a part or all of the discharge hole, or in order to blow gas into the inner hole, a structure with a gas pool or a gas introduction path on a part of the nozzle body 11 may also be used.

[0022] As an embodiment of the present invention, Figure 1 The submerged nozzle 10 shown in the figure was tested to confirm the effect of suppressing the occurrence of sinking. Figure 4 The same test was conducted on the submerged nozzle 10' shown in the figure. Figure 1 The basic structure of the immersion nozzle disclosed in the invention is the same as that of the immersion nozzle 10 of the present invention. Figure 4 The immersion nozzle 10' shown in FIG. Figure 1 The same components of the submerged nozzle 10 are denoted by the same reference numerals. In the submerged nozzle 10 and the submerged nozzle 10', the outer diameter of the nozzle body 11 is 150 mm, and the outer diameter of the flange 12 is 215 mm. In addition, Figure 1 In the immersion nozzle 10 shown, the bridge member 15 is a cylindrical pin with an outer diameter of 12 mm, and its configuration is as follows Figure 3 In addition, Figure 4 In the illustrated immersion nozzle 10 ′, the support portion 13 a is a cylindrical pin having an outer diameter of 12 mm, and three of the support portions 13 a are provided at equal intervals in the circumferential direction of the nozzle body 11 .

[0023] The test was conducted according to the following procedure. The inner hole 11a was heated by a gas burner until the temperature of the nozzle body 11 reached 1000°C, and then only the nozzle body 11 was pressurized from above at a predetermined pressure for 60 minutes. After the pressurization test, the difference in height between the upper end surface of the nozzle body 11 and the upper end surface of the flange 12 was checked. In the evaluation of whether sinking occurred, the case where the difference was 0.05 mm or more was judged as sinking, and the case where the difference was less than 0.05 mm was judged as no sinking.

[0024] Table 1 shows the evaluation results. As shown in the table, in the comparative example (submerged nozzle 10'), sinking occurred at a pressure of 20 kg (total pressure). In contrast, in the embodiment (submerged nozzle 10), sinking did not occur even at a pressure of 700 kg (total pressure). Thus, according to the embodiment (submerged nozzle 10), it can be seen that the sinking of the nozzle body 11 can be effectively suppressed. This is consistent with the results of the actual operation test conducted by the inventors. Specifically, according to the results of the actual operation test, the nozzle body 11 sank in the comparative example (submerged nozzle 10 ′), but did not sank in the example (submerged nozzle 10 ).

[0025] (Table 1)

[0026] Thus, the following reasons are considered to be the reason why there is a difference in the effect of suppressing the sinking of the nozzle body 11 between the comparative example (submerged nozzle 10 ′) and the example (submerged nozzle 10 ). In the comparative example (immersion nozzle 10'), the sinking is suppressed by the support portion 13a. However, since the support portion 13a is arranged below the flange portion 12, the distance from the heat source, that is, the mold, is short, and the heat from the mold is directly received. As a result, the metal shell 13 expands, etc., and a gap is generated around the support portion 13a. This gap makes the nozzle body 11 easy to sink. In contrast, in the embodiment (immersion nozzle 10), since the bridge member 15 is disposed in the flange portion 12, the distance from the heat source, that is, the mold, becomes longer. Figure 2 As shown, since the flange 12 is supported on the lower side by the support 20 of the submerged nozzle replacement device, it is located inside the submerged nozzle replacement device during operation. Therefore, it is not easy to be directly exposed to heat from the mold. Therefore, in the embodiment (submerged nozzle 10), it is not easy to form a gap around the bridge member 15, and as a result, it is not easy to sink the nozzle body 11. In addition, in the embodiment (submerged nozzle 10), since the flange 12 is formed by a cast refractory, as described above, the bridge member 15 can be set in the flange 12 without a gap, and the other end of the bridge member 15 can be engaged with the recess 11c without a gap. Therefore, it is more difficult for the nozzle body 11 to sink.

[0027] On the other hand, regarding the effect of suppressing the generation of cracks in the neck, in the embodiment (submerged nozzle 10), since the recessed portion 11c may become a stress concentration portion, there is a possibility that it is slightly reduced compared with the comparative example (submerged nozzle 10'). However, the inventors have confirmed through actual operation tests that the problem of the generation of cracks in the neck can also be eliminated according to the embodiment (submerged nozzle 10).

Claims

1. An immersion nozzle, comprising: a nozzle body portion, which is made of a refractory material and has an inner hole in the vertical direction; and a flange portion, which is made of a flat refractory material, and the flat refractory material is directly joined to the outer periphery of the upper end portion of the nozzle body portion in a manner of surrounding the outer periphery of the upper end portion of the nozzle body portion and protruding in the horizontal direction, or joined to the outer periphery of the upper end portion by an adhesive, the outer periphery of the flange portion and a part of the nozzle body portion below it is surrounded by a metal shell, the upper end surfaces of the nozzle body portion and the flange portion are located in the same horizontal plane, the lower side of the flange portion is supported by a support member so as to slide in the horizontal direction, and the upper end surfaces of the nozzle body portion and the flange portion are arranged to be joined together with the lower end surface of an upper nozzle member located above the immersion nozzle, It is characterized in that A bridging member is provided to bridge the inner peripheral surface of the metal shell surrounding the flange portion and the outer peripheral surface of the nozzle body portion, one end of the bridging member is fixed to the metal shell, and the other end is engaged with a recessed portion provided on the outer peripheral surface of the nozzle body portion. Above the point of force of the upward supporting force of the support member, the outer peripheral surface of the nozzle body, excluding the recessed portion, extends in a vertical direction with respect to the central axis of the inner hole without any dimensional change.

2. The immersion nozzle according to claim 1, characterized in that The flange portion is formed of a cast refractory.

3. The immersion nozzle according to claim 1 or 2, characterized in that The bridge member is not disposed in a region in the vertical direction of a force point portion where an upward supporting force of the support member exists.

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