Immersion nozzle

Abstract

To provide an immersion nozzle applicable to an immersion nozzle having a small inner pipe diameter and capable of suppressing the occurrence of drift of molten steel in the nozzle and further suppressing the drift in a mold.SOLUTION: An immersion nozzle 1 is provided in a slide valve 3 for controlling the flow rate of the molten steel S by adjusting the opening amount by sliding movement of a sliding plate 30. The immersion nozzle includes a nozzle body 10 having a substantially cylindrical shape. A pair of discharge holes 2 are oppositely arranged on side surfaces near the bottom of the nozzle body 10. The length in the vertical direction of one end side 20 of the discharge hole 2 in the circumferential direction of the side face is longer than the length in the vertical direction of the other end side 21. The shape of the pair of discharge holes 2 includes the axial center of the nozzle body 10 and has mirror symmetry with respect to a plane parallel to the sliding direction D of the sliding plate 30 as a mirror plane.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a submerged nozzle provided in a slide valve that controls the flow rate of molten steel by adjusting the opening amount by the sliding movement of a sliding plate.

Background Art

[0002] In a continuous casting process of steel using a submerged nozzle, when controlling the flow rate by a sliding plate to adjust the supply amount of molten steel from a tundish to a mold, uneven flow always occurs in the submerged nozzle. In particular, when the sliding direction of the sliding plate is in the thickness direction of the mold and the direction of the discharge holes of the submerged nozzle is different by 90 degrees in plan view, the discharge conditions are greatly different between one end side and the other end side in the horizontal direction of one discharge hole, causing an imbalance in the discharge conditions. This imbalance makes the flow state of the meniscus non-uniform in the sliding direction of the sliding plate, and is considered to be a factor in the increase of the molten steel surface fluctuation and the non-uniform solidification of the molten steel.

[0003] As a conventional technique for suppressing the occurrence of uneven flow in the flow rate control by a slide valve, for example, techniques shown in the following Patent Documents 1 to 3 are known.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the immersion nozzle described in Patent Document 1, a plurality of steps are provided on its inner wall surface. Further, in the immersion nozzle described in Patent Document 2, a plurality of convex structures are provided on its inner wall surface.

[0006] However, the above-described configuration of providing steps or convex structures on the inner wall surface of the immersion nozzle may be physically difficult to apply to immersion nozzles for blooms with a small inner pipe diameter. Also, when the clogging of alumina in the inner pipe of the immersion nozzle is remarkable, such a configuration itself may be filled up and the effect may not be exhibited.

[0007] Further, the immersion nozzle described in Patent Document 3 is provided with discharge holes having a discharge hole angle in the opposite direction with respect to the deviation of the nozzle discharge flow caused by the deviation of the molten steel flow in the flow rate adjustment part of the slide valve, but an extreme deviation flow may temporarily occur in the mold thickness direction.

[0008] The present invention has been made in view of the above circumstances, and its object is to provide an immersion nozzle that can be applied to an immersion nozzle with a small inner pipe diameter, suppresses the generation of uneven flow of molten steel in the nozzle, and further suppresses the uneven flow in the mold.

Means for Solving the Problems

[0009] The immersion nozzle according to the present invention is characterized in that, in an immersion nozzle provided in a slide valve that controls the flow rate of molten steel by adjusting the opening amount by the sliding movement of a sliding plate, it includes a substantially cylindrical nozzle body, and a pair of discharge holes are arranged opposite to each other on the side surface near the bottom of the nozzle body. The length in the vertical direction on one end side of the discharge hole in the circumferential direction of the side surface is longer than the length in the vertical direction on the other end side, and the shapes of the pair of discharge holes are mirror-symmetric with respect to a plane including the axis of the nozzle body and parallel to the sliding direction of the sliding plate.

[0010] With such a configuration, by setting the length in the vertical direction on one end side in the horizontal direction of the discharge hole to be longer than the length in the vertical direction on the other end side, and by having a pair of discharge holes having such a shape be mirror-symmetric, it is possible to suppress the generation of uneven flow of molten steel in the nozzle, and furthermore, to suppress the generation of uneven flow of molten steel in the mold, particularly the swirling flow in the meniscus.

[0011] Therefore, according to the present invention, there is no need to provide steps, convex structures, etc. on the inner wall surface of the immersion nozzle, and it can also be applied to an immersion nozzle with a small inner pipe diameter.

[0012] In the immersion nozzle according to the present invention, it is preferable that the ratio of the length in the vertical direction on the one end side to the length in the vertical direction on the other end side in the discharge hole is greater than 0.5 and less than 0.9.

[0013] According to this configuration, it is possible to suppress the concentration of thermal stress on the side with the shorter length in the vertical direction, and thus prevent the generation of cracks from the shorter side.

[0014] In the immersion nozzle according to the present invention, it is preferable that the height of the upper end on the one end side in the discharge hole is the same as the height of the upper end on the other end side.

[0015] According to this configuration, molten steel also easily flows from the upper part in the discharge hole, and it becomes difficult for alumina or the like to adhere to the upper part, so it is possible to make it even more difficult for the generation of uneven flow of molten steel to occur.

[0016] In the immersion nozzle according to the present invention, it is preferable that one end side and the other end side of the discharge hole are provided in this order along the direction in which the opening amount increases in the sliding direction of the sliding plate.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0018] Embodiments of the immersion nozzle according to the present invention will be described with reference to the drawings.

[0019] In a general continuous casting facility, molten steel S in a ladle (not shown) is supplied into a mold 4 via a tundish T. Then, the supply of the molten steel S from the tundish T into the mold 4 is injected into the mold 4 via an immersion nozzle 1 while adjusting the flow rate of the molten steel S by the opening amount of a slide valve 3 provided in the middle as shown in FIG. 1.

[0020] The slide valve 3 in the present embodiment is a three-layer slide valve, and is configured to control the flow rate of the molten steel S by adjusting the opening amount by the lateral sliding movement of an intermediate plate 30 (an example of a sliding plate).

[0021] As shown in FIG. 2, the mold 4 includes short-side steel plates 40 facing each other and long-side steel plates 41 facing each other. The intermediate plate 30 of the slide valve 3 is configured to move in a direction along the short-side steel plate 40, and each of the pair of discharge holes 2 of the immersion nozzle 1 is provided to open toward the side of the short-side steel plate 40.

[0022] The immersion nozzle 1 in the present embodiment includes a nozzle body 10 having a substantially cylindrical shape, and a pair of discharge holes 2 are arranged opposite to each other on the side surface near the bottom of the nozzle body 10. The shapes of the pair of discharge holes 2 have mirror symmetry with each other with a plane including the axis A of the nozzle body 10 and parallel to the sliding direction D of the intermediate plate 30 as a mirror plane M.

[0023] As shown in Fig. 1, the shape of the discharge hole 2 is set such that the vertical length (HL) of one end side 20 of the discharge hole 2 in the circumferential direction of the side surface of the nozzle body 10 is longer than the vertical length (HS) of the other end side 21. In this embodiment, the one end side 20 and the other end side 21 of the discharge hole 2 are provided in this order along the direction in which the opening amount increases in the sliding direction D of the intermediate plate 30 (the one end side 20 is on the left side and the other end side 21 is on the right side of the paper surface of Fig. 1), but the present invention is not limited to this configuration.

[0024] Preferably, the ratio of the vertical length of the one end side 20 to the vertical length of the other end side 21 in the discharge hole 2 is greater than 0.5 and less than 0.9.

[0025] In this embodiment, the height of the upper end of the one end side 20 and the height of the upper end of the other end side 21 in the discharge hole 2 are the same. That is, the shape of the discharge hole 2 in this embodiment is substantially trapezoidal, the upper side of the discharge hole 2 is horizontal, and the lower side of the discharge hole 2 is inclined.

[0026] Note that the shape of the discharge hole 2 is not limited to the above-described embodiment, and may be a shape that is asymmetric when viewed from the front from the outside, and the pair of discharge holes 2 have mirror symmetry with each other.

[0027] Basically, the vertical length on one end side of the discharge hole 2 means the vertical length of the outermost part on that one end side, and the vertical length on the other end side of the discharge hole 2 means the vertical length of the outermost part on that other end side. However, at the corners of the discharge hole 2, in order to suppress the concentration of thermal stress, a processing treatment may be performed to give a roundness that does not affect the flow of molten steel. In this case, the vertical length on one end side of the discharge hole 2 and the vertical length on the other end side mean the lengths in virtual dimensions assuming no such roundness. For example, when the outermost part on one end side is a straight part extending in the vertical direction, the vertical length on one end side of the discharge hole 2 means the vertical length of the rounded part connected to the straight part plus the vertical length of the straight part. Similarly for the other end side. For example, when the outermost part on the other end side is a straight part extending in the vertical direction, the vertical length on the other end side of the discharge hole 2 means the vertical length of the rounded part connected to the straight part plus the vertical length of the straight part.

[0028] 〔Other Embodiments〕 1. In the above-described embodiment, an example of applying the immersion nozzle according to the present invention to a three-layer slide valve was shown, but the present invention is not limited to this configuration, and the immersion nozzle according to the present invention may be applied to a two-layer slide valve.

[0029] Although the present invention has been described with reference to the drawings as described above, the present invention is not limited to the configuration of the drawings and can be implemented in various modes without departing from the gist of the present invention.

Industrial Applicability

[0030] The immersion nozzle according to the present invention can be suitably used, for example, in a continuous casting facility for steel.

Explanation of Signs

[0031] 1: Immersion nozzle 10: Nozzle body 2: Discharge hole 20: One end side 21: Other end side 3: Slide valve 30: Intermediate plate (an example of a sliding plate) 4: Mold 40: Short side steel plate 41: Long side steel plate A: Axis of the nozzle body M: Mirror plane T: Tundish S: Molten steel D: Slide direction

Claims

1. In a submerged nozzle provided in a slide valve that controls the flow rate of molten steel by adjusting the opening amount by sliding movement of a sliding plate, comprising a substantially cylindrical nozzle body, a pair of discharge holes are oppositely arranged on the side surface near the bottom of the nozzle body, the vertical length of one end side of the discharge hole in the circumferential direction of the side surface is longer than the vertical length of the other end side, and the shapes of the pair of discharge holes have mirror symmetry with each other with a plane including the axis of the nozzle body and parallel to the sliding direction of the sliding plate as a mirror surface, a submerged nozzle, characterized in that one end side and the other end side of the discharge hole are provided in this order along the direction in which the opening amount increases in the sliding direction of the sliding plate.

2. The submerged nozzle according to claim 1, characterized in that the ratio of the vertical length of the one end side to the vertical length of the other end side in the discharge hole is greater than 0.5 and less than 0.

9.

3. The submerged nozzle according to claim 1, characterized in that the height of the upper end of the one end side in the discharge hole is the same as the height of the upper end of the other end side.

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