WO2009128282A1 - Immersion nozzle for continuous casting - Google Patents

Abstract

Provided is an immersion nozzle for continuous casting, in which the neck part of a cylindrical refractory object can be prevented from being damaged due to a pressing force or a stress by forming a metal case provided for the cylindrical refractory in a double structure configured from an outer part and an inner part. The immersion nozzle for continuous casting comprises an inner metal case (12) provided onto a part or the entire of the outer surface of the cylindrical refractory object (1), a tapered metal part (12a) so formed on the inner metal case (12) as to correspond to the tapered part (11a) of the cylindrical refractory object (1), and an outer metal case (13) provided outside of the inner metal case (12). At least parts of the metal cases (12, 13) are joined to each other.

Description

Immersion nozzle for continuous casting

The present invention relates to an immersion nozzle for continuous casting, and in particular, a metal case provided on a cylindrical refractory is doubled in the outer and inner sides to prevent breakage of the neck of the cylindrical refractory due to pressing force and stress. Related to the improvement.

Conventionally, in the final smelting process of metal, molten metal is injected from a container such as a tundish through a flow control device using a slide gate plate, a stopper, etc. into a casting mold and solidified into a fixed shape. Although not shown, for example, in the case of a slide gate device, it is installed at the bottom of the tundish and used in combination of an upper nozzle, two to three slide plates, a lower nozzle, and an immersion nozzle. The molten metal is poured into the casting mold from inside the tundish through the upper nozzle, the slide plate, the lower nozzle, and the immersion nozzle.

Although there is a joint between these refractories (for example, slide plate and lower nozzle, lower nozzle and immersion nozzle, etc.), the air enters from the joint to oxidize, degrade the quality of the molten metal, or join In some cases, it is possible to cause a bullion from the department, and in severe cases, it may become inoperable.
In order to solve this problem, there is a first method in which a plurality of refractories are combined into one (for example, integrating the lower nozzle and the immersion nozzle), and the refractories by increasing the pressing pressure for fixing the refractories to each other. There is a second method of bringing the two into close contact with each other.

As an example of the first method described above, there is a method of integrating the upper nozzle and the upper plate, and a method of setting and integrating the separately manufactured upper nozzle and the upper plate using a metal case. Similarly, a method of integrating the lower plate, the lower nozzle and the immersion nozzle is also practiced. For example, FIGS. 1 and 5 of Patent Document 1 describe a continuous casting refractory block having a configuration in which the outer peripheral surface of the integrated assembly of plate brick and immersion nozzle is directly accommodated in an integral metal case. There is. Moreover, FIGS. 3 and 4 of Patent Document 1 describe a refractory block for continuous casting, which is manufactured as an integrated refractory from the plate to the immersion nozzle and directly accommodated in a one-piece metal case. It is done. In particular, in the immersion nozzle for a flow control device with a rapid exchange device with an immersion nozzle capable of replacing the immersion nozzle attached to the flow control device during casting, the immersion nozzle integrated from the lower plate to the immersion nozzle from the viewpoint of operability. (Hereafter, integrated immersion nozzle) is widely used.
That is, as shown in FIG. 10, the outer surface including the outer periphery of the elongated cylindrical refractory 1 is covered with the first metal case 2 and the second metal case 3, and each metal case 2, 3 is The joint 4 is integrally formed by welding.

Japanese Utility Model Application Publication 6-553 JP 2001-314949 A

Since the conventional continuous casting immersion nozzle is configured as described above, the following problems exist.
In the above-mentioned integrated immersion nozzle, although the joint of the refractory can be eliminated from the lower plate to the mold, the total length of the refractory must be long. During use, the immersion nozzle may be physically damaged due to vibrations from the molten steel flowing in the casting mold and an impact applied when replacing the immersion nozzle. The stress (hereinafter referred to as dynamic stress) due to the push-up force 5 temporarily generated by such vibration or impact is particularly concentrated on the nozzle neck, and the magnitude of the stress is large in proportion to the lengthening of the immersion nozzle Become. In order to protect the immersion nozzle neck from vibration and impact applied during this use, it is effective to reinforce the portion from the flange portion 1a of the immersion nozzle to the main body with a metal case as shown in FIG. That is, in the integrated immersion nozzle, it is effective to reinforce its neck portion with a metal case, even if it has a jointless structure manufactured from an integrated refractory from the plate to the immersion nozzle.

From the viewpoint of stress relaxation, it is better to use a one-piece metal case to protect the wide area as much as possible from the point of stress relaxation by hanging it from the bowl-like part (hereinafter referred to as flange 1a) corresponding to the lower plate. However, especially in immersion nozzles for flow control devices with immersion nozzle quick change devices, the shape of the metal case often has to be deep, and often a long metal case can not be manufactured. . In such a case, different metal cases are manufactured for the flange portion and the main body portion, and both are connected by welding. For example, in FIG. 2 of Patent Document 1, an immersion nozzle housed in a cylindrical metal case and a plate brick housed in another metal case are joined via mortar, and the metal cases are integrally welded. However, when separate metal cases are welded and integrated in this way, the connection strength is often insufficient, and as shown in Patent Document 2, a method of reinforcing both with reinforcement brackets is also considered. ing. However, such reinforcement with hardware is not only time-consuming and disadvantageous in terms of cost, but also has a problem that the entire circumference can not be equally reinforced.

Although the second method described above is also an effective countermeasure, there is a limit to the pressing pressure that can be applied to the refractory from the viewpoint of the capacity of the apparatus and the strength of the refractory, and the refractory such as plate and immersion nozzle Because the molten steel flow passes through the inside during casting, the temperature rises from the inside and expands. For this reason, the refractories are in a state of being stuck on the inner hole side through which the molten steel flow passes, and a gap is generated in the peripheral portion. In this state, as shown in FIG. 11, the outside of the immersion nozzle is pressed from the bottom to the top by the lifting force 5, and the larger the pressing pressure, the stress generated at the neck of the refractory (hereinafter referred to as static stress and ) Will grow. Since the strength of the immersion nozzle is lower than that of the plate and other nozzles, in the case of a slide gate type flow control device, a pressure device for the immersion nozzle is provided separately from the pressure device for pressing the plate. In general, the pressing pressure (about 8000 to 10000 MPa) is set within the range that the immersion nozzle material can withstand. However, sometimes the neck portion of the immersion nozzle may be cracked and broken without being able to withstand an excessive load. For this reason, for the purpose of protecting the refractory, as disclosed in the above-mentioned FIG. 10 and Patent Documents 1 and 2, the neck portion of the immersion nozzle is reinforced with a metal case to take measures to secure rigidity. However, the present situation is not enough.

The immersion nozzle for continuous casting according to the present invention injects molten metal from a container into a casting mold and is an immersion nozzle for continuous casting comprising a cylindrical refractory, wherein the metal taper corresponds to the tapered portion of the cylindrical refractory. And an outer metal case provided on the outer side of the inner metal case, and an outer metal case provided on the outer surface of the inner case. At least a part of the inner metal case is joined, and the outer metal case has an L-shaped cross section consisting of a vertical plate portion and a horizontal plate portion, and the outer side of the horizontal plate portion is from below. The inclination angle of the metal tapered portion of the inner metal case corresponding to the tapered portion of the cylindrical refractory is a configuration that receives a pressing force, and the inclination angle of the metal tapered portion of the inner metal case is in the vertical direction when the cylindrical refractory is used. 20.about.60. In addition, a refractory material for a metal case is filled between the inner metal case and the outer metal case, and The refractory material of the tubular refractory is made of alumina carbon or alumina silica carbon, and the refractory material of the tubular refractory is formed of two layers of upper and lower layers different in material from each other, and the refractory material of the upper layer The thermal expansion coefficient of the material is larger than the thermal expansion coefficient of the material of the lower layer refractory material, and the difference between the thermal expansion coefficients of the upper layer and the lower layer refractory material is 15% or more. The inner metal case is formed in a round cylinder, the outer metal case is formed in a square tube, and the inner metal case and the outer metal case are formed in a square tube.

Since the immersion nozzle for continuous casting according to the present invention is configured as described above, the following effects can be obtained.
That is, in the immersion nozzle for continuous casting which injects the molten metal from the container into the casting mold and is made of a cylindrical refractory, the metal corresponding to the tapered portion of the cylindrical refractory and formed in the inner metal case An inner metal case provided on a part or the whole of the outer surface of the cylindrical refractory having a tapered portion, and an outer metal case provided on the outer side of the inner metal case; Since at least a part of the inner metal case has a joint structure, it can sufficiently cope with the dynamic stress generated by vibration or impact applied during use, and is generated by the pressing force from the device and the thermal expansion of the refractory. It is possible to sufficiently reinforce the portion from the flange portion of the immersion nozzle to the main body portion with sufficient rigidity to prevent breakage of the neck portion against dynamic stress.
Further, according to the invention of claim 2, the outer metal case has an L-shaped cross section consisting of a vertical plate portion and a horizontal plate portion, and the horizontal plate portion receives a pressing force from the outside lower side. An outer metal case that can withstand dynamic stress can be obtained.
Further, according to the configuration of the third aspect, the inclination angle of the metal tapered portion of the inner metal case corresponding to the tapered portion of the cylindrical refractory corresponds to the vertical direction at the time of using the cylindrical refractory. Since it is set in the range of 20 · to 60 ·, it can have sufficient strength against the above-mentioned stress.
Further, according to the structure of the fourth aspect, since the refractory material for the metal case is filled between the inner metal case and the outer metal case, the rigidity can be further improved.
Further, according to the configuration of claim 5, the refractory material of the cylindrical refractory is made of alumina carbon or alumina silica carbon, and the refractory materials of the cylindrical refractory have upper and lower layers of different materials. An immersion nozzle formed of two layers, wherein the coefficient of thermal expansion of the material of the upper layer refractory material is larger than the coefficient of thermal expansion of the material of the lower layer refractory material can be restrained to the metal case at the position of the upper material .
Moreover, according to the structure of Claim 6, since the difference of the thermal expansion coefficient of the said refractory material of the said upper layer and lower layer is 15% or more, the effect similar to Claim 5 can be acquired.
Further, according to the configuration of claim 7, the inner metal case is formed in a round cylinder, and the outer metal case is formed in a square cylinder, so that a refractory material can be filled therebetween.
Further, according to the configuration of the eighth aspect, since the inner metal case and the outer metal case have a square cylindrical shape, the metal case has a double structure in which the metal cases are mutually polymerized, and the rigidity is improved.

Therefore, since a metal case structure of a two-layer structure is provided ranging from the flange portion of the immersion nozzle to the main body portion, it is composed of an outer metal case for attachment to the flow control device and an inner metal case supporting a refractory. First, even a high strength steel material can be made in one piece by forming the inner metal case in direct contact with the refractory material into a cylindrical (elliptical) shape and a shallow shape of a diaphragm that is not bent at a right angle. (2) can ensure sufficient thickness and sufficient length, so it is highly resistant to dynamic stress generated by vibration and impact. Second, the tapered or funnel-like portion of the inner metal case is generated at the inflection point of the immersion nozzle neck, as the direction of the force pressing the immersion nozzle from below is transmitted obliquely to the refractory and transmitted to the refractory It has the effect of suppressing static stress. Third, the two-layer structure in which the inner and outer metal cases are at least partially in contact with each other significantly improves the rigidity of the entire metal case and deforms both the dynamic stress and the static stress. You can prevent.

It is sectional drawing which shows the 1st form of the immersion nozzle for continuous casting by this invention. It is the plane and sectional view showing the 2nd form of the present invention. It is the plane and sectional view showing the 3rd form of the present invention. It is the plane and sectional view showing the 4th form of the present invention. It is the plane and sectional view showing the 5th form of the present invention. It is the plane and sectional view showing the 6th form of the present invention. It is the plane and sectional view showing the 7th form of the present invention. It is sectional drawing from the arrow C of FIG. It is sectional drawing which shows the 8th form of this invention. It is sectional drawing which shows the conventional immersion nozzle for continuous casting. It is explanatory drawing which shows the deformation | transformation state of the principal part of FIG.

The present invention provides a continuous casting immersion nozzle in which a metal case provided on a cylindrical refractory is doubled in the outer side and an inner side to prevent breakage of the neck portion of the cylindrical refractory due to pressing force or stress. With the goal.

Hereinafter, preferred embodiments of a continuous casting immersion nozzle according to the present invention will be described with reference to the drawings.
The same or equivalent parts as in the conventional example will be described using the same reference numerals.
FIG. 1 shows a first embodiment of the present invention, and the one indicated by reference numeral 1 in FIG. 1 is a long cylindrical refractory for constituting a continuous casting immersion nozzle 10 used in a slide valve. A molten steel injection hole 10 a is formed in the axial center position of the cylindrical refractory 1 so as to penetrate therethrough.

The outer surface 11 of the cylindrical refractory 1 is composed of a tapered portion 11a at the top and a straight portion 11b formed at the lower portion of the tapered portion 11a.
The metal member 12A provided on a part or the whole of the outer surface 11 is composed of an inner metal case 12 and an outer metal case 13.

The inner metal case 12 is formed along the tapered portion 11a and the linear portion 11b, and the tapered portion 11a is formed with a metal tapered portion 12a along the shape.
The outer metal case 13 having an L-shaped cross section and including a vertical plate portion 13a and a horizontal plate portion 13b is provided at an outer peripheral position of the metal tapered portion 12a, and the tapered portion 11a and the outer metal case 13 are provided. The metal case refractory material 15 is filled in the space 14 having a triangular cross section formed between the two.

The outer metal case 13 and the inner metal case 12 are at least partially joined or entirely joined by welding or the like, and the inner metal case 12 and the outer metal case 13 are attached to the cylindrical refractory 1. It may be formed on the entire outer periphery of the tongue, or may be partially formed.

FIG. 2 is a second embodiment showing another plan configuration and a sectional view of the continuous casting immersion nozzle 10 of FIG. 1, wherein the outer metal case 13 has a square shape and the inner metal case 12 has a cylindrical shape. The vertical plate portion 13a and the horizontal plate portion 13b are integrally bent.

FIG. 3 shows a third embodiment of the present invention, in which a vertical portion 12B is formed on the upper portion of the inner metal case 12, and the vertical portion 12B is joined to the inner surface of the vertical plate portion 13a.
FIG. 4 shows a fourth embodiment of the present invention, in which the metal tapered portion 12a is made shorter than that in FIG. 1 on the inner surface of the vertical plate 13a, and they are joined together by welding or the like.

Moreover, FIG. 5 is 5th form of this invention, makes the above-mentioned cylindrical refractory 1 2 layers, and is formed by the upper layer 1A and the lower layer 1B.
6 is a sixth embodiment of the present invention and shows a configuration in which the refractory material 15 for metal case is not filled between the inner metal case 12 and the outer metal case 13 described above.

FIGS. 7 and 8 show a seventh embodiment of the present invention, in which both the inner metal case 12 and the outer metal case 13 described above are square-shaped and polymerized with each other.

FIG. 9 shows an eighth embodiment of the present invention, in which the cylindrical refractory 1 is made into an upper layer 1A and a lower layer 1B, and in FIG. 9, A is the length of the upper layer 1A and B is the metal tapered portion 12a of the inner metal case 12. A length C, a length of the inner metal case 12, a D indicates an inflection point bent from the flange portion 1a, and a t indicates a thickness of the inner metal case 12.

The first embodiment of FIG. 1 of the invention is used in a continuous casting immersion nozzle 10 for injecting molten metal from a container such as tundish into a casting mold, attached to a flow control device located on the tundish side, An inner one-piece cylindrical shape straddling the main body from the flange 1a having the outer metal case 13 fitted to the control device and the press in use and the funnel-like part consisting of the metal taper 12a in whole or in part The continuous casting nozzle is composed of the inner metal case 12 and is accommodated by the two-layer metal case in which at least a part of the two are joined. The thickness of each of the metal cases 12 and 13 is preferably 1.5 mm or more on both the inside and the outside, and more preferably 2.0 mm or more. The length of the inner metal case is preferably 60 mm or more, more preferably 100 mm or more in the vertical direction straddling the upper and lower portions of the bending point D of the neck portion of the immersion nozzle. In addition, sufficient effects can not be obtained unless at least a part of the inner and outer metal cases 12 and 13 are directly joined.

In the second embodiment of FIG. 2 of the invention, the angle of the metal tapered portion 12a of the inner metal case 12 is 20 degrees to 60 degrees with respect to the vertical direction E at the time of use in the above two-layered metal cases 12 and 13. A continuous casting nozzle housed by a metal case in the range of The refractory member of the immersion nozzle is supported in the inner metal case 12 by an angled metal taper 12a. The smaller the angle is, the shallower the diaphragm of the inner metal case 12 is, and the shape is easily elongated. However, if it is less than 20 degrees, the refractory member can not be supported sufficiently. On the other hand, if the temperature exceeds 60 degrees, the inner metal case 12 is deeply drawn, the thickness of the iron shell becomes uneven, and it becomes difficult to manufacture a sufficiently long one-piece inner metal case 12.

In the third and fourth embodiments of FIGS. 3 and 4 of the invention, the reinforcement of the flange portion 1a is made more efficient in the above-mentioned two-layered metal cases 12 and 13, particularly in the immersion nozzle for quick replacement having a wide flange portion. Between the outer metal case 13 and the inner metal case 12 is filled with the refractory material 15 for the metal case such as castable refractor, or the outer metal case 13 and the inner metal case 12 are made of metal. A continuous casting immersion nozzle 10 housed by a two-layer metal case 12, 13 joined by a bridge (not shown). Although direct contact between the outer metal case 13 and the inner metal case 12 can ensure sufficient rigidity against static stress, it is further filled with a refractory material such as castable refractor between the outer iron skin and the inner iron skin. The rigidity can be increased to 3 to 4 times by joining with a metal bridge (not shown). The castable refractor to be used is not in direct contact with the molten steel, so any fixed composition and surface accuracy can be obtained regardless of the chemical composition of the material and the constituent raw material. However, if the coefficient of thermal expansion is too high, cracking may occur due to thermal shock at the start of casting, or the flange portion 1a of the one-piece immersion nozzle may be deformed during casting. Therefore, the coefficient of thermal expansion after drying of the castable refractory is preferably in the range of 0.20 to 0.60% at 1000.degree.

In general, alumina-carbon or alumina-silica-carbon materials are used as the material of the immersion nozzle. Depending on the conditions of use, it may be a single material, but may be used in combination of multiple materials. In the fifth and eighth embodiments of FIGS. 5 and 9 of the invention, the alumina-carbon or alumina-silica-carbon material of the cylindrical refractory 1 in the metal cases 12 and 13 is different between the upper layer 1A and the lower layer 1B. It is a nozzle for continuous casting which is made of a two-layer material and the thermal expansion coefficient of the material of the upper layer 1A is larger than the thermal expansion coefficient of the material of the lower layer 1B. In order to coat the immersion nozzle material with a metal case, a method of setting using mortar is common. In the case of the immersion nozzle material of the uniform material, the immersion nozzle material is uniformly restrained by the inner metal case during use, but the thermal expansion coefficient of the upper material is the thermal expansion coefficient of the lower material with two different layers of material By making the size larger than this, the immersion nozzle is constrained to the metal case at the position of the upper material. By disposing the upper layer in the range of two thirds or less of the funnel-shaped part at the longest from the joint surface, it is possible to further relieve the stress on the neck part from the immersion nozzle flange part to the main body part. As for this stress relaxation, it is desirable that the difference of the coefficient of thermal expansion of two materials is 15% or more.

The chemical composition of a typical immersion nozzle material is often in the range of 35 to 90% by weight of alumina, 0 to 30% by weight of silica, and 10 to 35% by weight of carbon in consideration of corrosion resistance and heat resistance spallability. In order to increase the coefficient of thermal expansion, a method of increasing the ratio of the alumina component in this is generally used, and it can be applied as the material of the upper layer 1A. Further, the thermal expansion coefficient may be increased by adding a metal such as silicon or aluminum, a silicide such as silicon carbide, or a boride such as boron carbide.
The manufacturing method of the immersion nozzle knead | mixes raw materials, such as an alumina, a silica, carbon, etc. with a binder, is filled with a molding frame, preferably shape | molds by CIP, and it dries and bakes. Although several embodiments of the present invention have been described, the present invention is not limited to the above-described embodiments, and is intended to include equivalents that can be easily applied by those skilled in the art.

The above-mentioned Table 1 shows the quality of the refractory used in the present invention, and shows the coefficient of thermal expansion at 1000 ° C. of each of the materials 1 to 4.

The above-mentioned Table 2 is the result of investigating the resistance to an immersion nozzle neck breakage by stress calculation in the present invention using the material of Table 1. The first embodiment is the case where the same material is used from the bonding surface to the main body portion, and the second to fifth embodiments are cases where a material different from the lower layer 1B is used for the upper layer 1A of the tapered portion 11a. In addition, the taper-shaped part 11a said here points out the whole upper part from the inflexion point D from the flange part 1a to a main-body part. When the upper and lower portions are composed of two different layers, when the coefficient of thermal expansion of the material of the upper layer 1A is higher than that of the material of the lower layer 1B, the restraints of the metal cases 12 and 13 concentrate on the material of the upper layer 1A. The stress generated at the inflection point D of the neck in the material was reduced.
As a result of examining various cases other than the above-mentioned Table 2, when the thermal expansion coefficient of the material of the upper layer 1A is 15% or more larger than the thermal expansion coefficient of the material of the lower layer 1B, the neck breakage preventing effect was particularly remarkable.

Claims (8)

In a continuous casting immersion nozzle comprising pouring molten metal from a container into a casting mold and consisting of a cylindrical refractory (1),
Corresponding to the inner metal case (12) provided on a part or the whole of the outer surface (11) of the cylindrical refractory (1) and the tapered portion (11a) of the cylindrical refractory (1) A metal tapered portion (12a) formed on the inner metal case (12); and an outer metal case (13) provided on the outer side of the inner metal case (12);
A continuous casting immersion nozzle characterized in that at least a part of the outer metal case (13) and the inner metal case (12) are joined. The outer metal case (13) has an L-shaped cross section including a vertical plate portion (13a) and a horizontal plate portion (13b), and the horizontal plate portion (13b) receives a pressing force from the outside lower side. The immersion nozzle for continuous casting according to claim 1, characterized in that: The inclination angle of the metal tapered portion (12a) of the inner metal case (12) corresponding to the tapered portion (11a) of the cylindrical refractory (1) is at the time of using the cylindrical refractory (1) The immersion nozzle for continuous casting according to claim 1 or 2, which is set in the range of 2020 to 60 ・ with respect to the vertical direction (E). The continuous according to any one of claims 1 to 3, wherein a refractory material (15) for metal case is filled between the inner metal case (12) and the outer metal case (13). Immersion nozzle for casting. The refractory material of the cylindrical refractory (1) is made of alumina carbon or alumina silica carbon, and the refractory material of the cylindrical refractory (1) is an upper layer (1A) and a lower layer (1B) of different materials. The thermal expansion coefficient of the material of the refractory material of the upper layer (1A) is larger than the thermal expansion coefficient of the material of the refractory material of the lower layer (1B). The immersion nozzle for continuous casting according to any one of 4. The immersion nozzle for continuous casting according to claim 5, wherein the difference in thermal expansion coefficient between the upper layer (1A) and the lower layer (1B) is 15% or more. The immersion nozzle for continuous casting according to any one of claims 1 to 6, wherein the inner metal case (12) has a round cylinder shape and the outer metal case (13) has a square cylinder shape. The immersion nozzle for continuous casting according to any one of claims 1 to 6, wherein the inner metal case (12) and the outer metal case (13) have a square cylindrical shape.

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