JPH04270037A - Nozzle for continuous casting - Google Patents

Abstract

PURPOSE:To uniformly and stably select the optional blowing quantity of inert gas for sealing in extremely easiness in the vicinity just above connect fitting socket face on the face of the upper part of a long nozzle and to enable air sealing effect extremely high in the air sealing at a connect fitting part with the lower end of a ladle collector nozzle in the nozzle. CONSTITUTION:On the upper fitting end face of a nozzle for continuous casting, plural stripes of T type notching grooves opened to air pocket 3 having the inner end at an inner hole 10 face and inert gas introducing hole 7 at an external end, are provided. These have features forming the inert gas introducing passage with external face coating of a protecting iron shell 6. The extremely stable air sealing, which can control the whole casting can be executed and high quality of the casting metal can be stably obtd. Stability of the operation and remarkable reduction in the cost can be attained.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a nozzle for continuous casting, and more particularly to a fire-resistant member for a molten metal flow path used in continuous casting of metals, for example, a nozzle for continuous casting of ladle and tundish. A long nozzle or immersion nozzle is used to prevent oxidation by shielding the molten metal from the air between the tundish and the mold, or to prevent droplets from scattering when the molten metal flows down. The present invention relates to a continuous casting nozzle, etc., related to the air sealing property at the connection fitting part between the upper fitting end surface of the casting nozzle and the collector nozzle at the lower end of the ladle or tundish.

0002

2. Description of the Related Art As mentioned above, a long nozzle used in continuous casting of steel will be described as an example of a nozzle for continuous casting. As a measure to perfect the air sealability of the upper fitting end of the conventional long nozzle with the ladle collector,
Various methods have been adopted, but the most basic methods include placing a sealing material between the connecting mating surfaces to improve sealing performance, and blowing inert gas such as argon gas into the same area. Countermeasures have been taken, such as applying each method alone, such as sealing methods, and using them in combination to increase the effect. In other words, a sheet-shaped sealing material mainly made of alumina aggregate is placed on the top fitting surface of the long nozzle to ensure a tight connection with the ladle collector nozzle, and a fire-resistant material is also placed on the top fitting surface of the long nozzle. Methods such as placing a porous member and blowing out inert gas to prevent air from entering the long nozzle inner hole have been adopted, but these methods do not provide the desired effect. , and later JP-A-57-115952, JP-A-58-209453, and JP-A-59-4566.
No. 2, etc. have been invented and put into practical use as countermeasures for these problems.

FIG. 3 shows an example of air sealing at a long nozzle fitting part using a conventional method. To summarize its action, a fire-resistant porous member 11 is placed on the top of the long nozzle 2a within 70% of the connection fitting part with the collector nozzle 1a, and is fixed with mortar to the long nozzle 2a. The inert gas introduced from the blowing fitting is guided into the air pocket 3a, which is reinforced by the skin 6a, passes through the refractory porous member 11, and is ejected from the gap in the upper iron skin, and is connected to the ladle collector nozzle 1a. This prevents air from entering the joints of the joints and provides a good fit and seal.

0004

[Problems to be Solved by the Invention] The conventional air sealing method at the same location as described above has had the following problems when performing continuous casting operations. In other words, in the continuous casting of metals, the molten steel temperature is generally around 1450℃, although it varies depending on the steel type, and the long nozzle made of alumina graphite material has good thermal conductivity. The top fitting part receives heat from the molten steel and reaches almost the same temperature. The refractory porous material placed in the same area has inferior spalling resistance compared to the material of the long nozzle body, so there may be insufficient preheating at the start of casting, or the next step after pouring one ladle worth of molten steel. It was common for it to cool during the changeover to the pot and crack due to thermal stress when pouring into the next pot. If this fire-resistant porous member cracks, it may become impossible to blow out inert gas uniformly at the fitting part, or the socket surface, which is the joint surface with the ladle collector nozzle, may lose its smoothness. Surface roughness occurs, resulting in incomplete joints, which causes significant problems in air sealing performance in this area, and as a result, has a significant negative impact on the quality of the cast billet. In this method, the top structure of the long nozzle is not integrated, but is assembled with a fire-resistant porous member, which increases the number of processing steps in its manufacture, resulting in a large cost disadvantage.

[0005] To address this problem, the above-mentioned Japanese Unexamined Patent Application Publication No. 57-115952 and Japanese Unexamined Patent Publication No. 5/1988 disclose solutions such as integration.
Publication No. 8-209453 and JP-A-59-45066
However, the following problems have become apparent with these methods as well, as described below. That is, in JP-A-57-115952, the inert gas blowing function is provided on the top end of the long nozzle, but the inert gas is ejected from the gap between the flat surface of the top end of the long nozzle and the reinforcing iron skin. It is a method that blows out
In the high-temperature atmosphere during casting, the iron shell deforms and it is virtually difficult to maintain its original shape for a long time, and the deformation of the iron skin obstructs uniform gas ejection, causing serious defects in sealing performance. This has an adverse effect on the quality of the billets to be cast. Next, JP-A-59-45066
As for the No. 1 publication, it is mainly used as a countermeasure for immersion nozzles for continuous casting, so the amount of inert gas blown into the fitting part is extremely small compared to the long nozzle in this example. , the sealing by this method is for the sealed part where the fitting part blows out to the socket surface, and not to the free space, and furthermore, the sealing is for the socket surface to a maximum of 60 mm.
As a countermeasure for long nozzles where the fitting is relatively rough compared to immersion nozzles which require highly accurate mounting and fitting, for example, the arrangement is limited to within 10%, this invention shows As a result, the deterioration of sealing performance caused by the roughness of the fitting surface cannot be compensated for, and the quality deterioration of the cast billet cannot be prevented. And furthermore, JP-A-58-2094
Regarding Publication No. 53, since a groove is provided on the socket surface, the concept is not suitable for the function that requires the flatness of the socket surface to the maximum possible limit from the viewpoint of attaching importance to the sealing performance for connection with the upper collector nozzle. being at a disadvantage,
The blowout of inert gas is limited to the inner hole below the collector nozzle fitting part (joint part), and since the long nozzle is vertically shaped, the molten steel flow causes physical and uneven stress. Since it constantly acts on the fitting part, the fitting tends to become biased and loosen, and if the degree of this becomes large and conditions are created that invite outside air to enter, it is difficult to prevent this intrusion. Because molten steel is constantly flowing down the long nozzle inner hole, the inner hole is always under a negative pressure condition, and it is necessary to overcome this pressure and prevent outside air from entering by using a large amount of inert gas. Blow-in is necessary, and as a result, the hot water surface in the tundish becomes violent due to the inert gas, and the hot water surface in the tundish is exposed from the coating powder and slag and comes into contact with the air, causing splashes. This is because floating inclusions may be drawn into the molten steel, which may seriously affect the quality of the molten steel, or may cause problems such as making it impossible to ensure work safety.

[0006]

[Means for Solving the Problems] The present invention has been made against the above-mentioned background, and in order to solve these problems, it has the following configuration. That is, the present invention relates to a fire-resistant member for a molten metal flow path used in continuous metal casting, etc. Taking a long nozzle for continuous casting as an example, there is a structure in which the upper end surface of the long nozzle has an inner end facing the inner hole surface. A long nozzle for continuous casting consisting of a plurality of T-shaped grooves each opening into an air pocket with an inert gas inlet at the outer end, and an inert gas inlet passage formed by covering the outer surface of a protective iron shell. It is. In other words, in the air seal of the connection fitting part of the long nozzle with the lower end of the ladle collector nozzle, the inert gas for sealing can be applied very easily and uniformly to the vicinity of the connection fitting socket surface at the upper end surface of the long nozzle. To provide a continuous casting nozzle with high stability and high sealing performance, which allows an arbitrary blowing amount to be selected and which enables an extremely high air sealing effect.

Next, embodiments of the present invention will be described in detail with reference to the drawings. An example of the material of the long nozzle is graphite 26% by weight, alumina 45% by weight, silica 26% by weight.
, 9% by weight in an aggregate formulation consisting of 3% by weight of silicon carbide.
This product is manufactured by kneading a mixture to which a material binder is added, adjusting the particle size, molding the resulting clay using a press, and firing. FIG. 1 shows a vertical cross section of a structure that achieves high seal reliability and stable jointing during connection and fitting at the long nozzle top portion of the present invention. The long nozzle 2 is connected and fitted with the ladle collector nozzle 1 at the socket surface 9. 3 has an inert gas inlet 7 for introducing inert gas, and has an air pocket formed around the circumference, 4 and 5 are T-shaped through slits, 6 is a protective iron shell, and 8 is a long nozzle 2. This refractory mortar is used to bond and fix the protective iron shell 6 and to prevent inert gas from leaking in the same area. Next, T-shaped through slit 4,
As shown in the plan view of FIG. 2, eight T-shaped cut grooves 4' and 5' forming T-shaped grooves 5 are arranged radially at equal intervals on the upper end surface of the long nozzle 2. In addition, 10 is the long nozzle inner hole, 3 is the air pocket, and 9 is the collector nozzle 1.
This is the socket surface that connects with the socket.

[0008] This invention utilizes an inert gas at the fitting part of a refractory part used as a molten metal flow path, such as a long nozzle or an immersed nozzle, to connect a through slit constructed as described above to another member. It enables effective blow-out control and completely prevents air from entering the area, reducing the quality deterioration of molten metal and reducing the variation in product quality level as per the target, and making operations safer. This is what I did.

[0009]

[Operation] Inert gas is introduced into the air pocket 3 from the inert gas inlet 7 through the inlet pipe from the gas supply device (not shown).
guided inward. Then, it is uniformly introduced to the entire top outer circumference of the long nozzle 2. From here, it is blown out into the vicinity of the joint with the bottom of the ladle collector nozzle 1 through the plurality of T-shaped through slits 4 and 5 provided on the upper end surface, respectively.

0010

Effects of the invention: First, the long nozzle top including the T-shaped through-slit is simplified into a single unit structure, which greatly improves the strength and reduces thermal history under conditions of repeated use. Since no cracks occur even after repeated use, the smoothness of the socket surface can be maintained until the long nozzle is disposed of, which is an absolute condition for ensuring the sealing performance of the fitting part with the collector nozzle. In addition, the conditions for supplying and blowing inert gas to the mating surface are evenly distributed over the entire mating surface by the T-shaped cut groove, and the blowing amount can be arbitrarily selected, making the casting plan easier. Under the same conditions, we were able to create an extremely stable air seal that could control casting from start to finish, and achieved a high and stable cast metal quality. Furthermore, the manufacturing cost is reduced by integrally molding the long nozzle, and troubles are prevented by stabilizing the fitting portion during operation, so that it can be used for casting at an extremely low total cost. The overall effect of solving the problem of long nozzle life is to stabilize operations and significantly reduce costs. As a result of actually using the continuous casting nozzle of this invention as a long nozzle between a ladle and a tundish, the stabilization of the strength of the fitting part and the high reliability of gas blowing as described above were achieved as desired. As a result, the sealing properties of the parts were improved, costs were significantly reduced, and the quality of the slab was improved. The durability of the long nozzle was significantly improved, reaching 10 to 11 cycles compared to the conventional 6 to 7 cycles. The above practical example was compared with the conventional method in Table 1.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of a continuous casting nozzle of the present invention.

FIG. 2 is a plan view of an embodiment of the continuous casting nozzle of the present invention.

FIG. 3 is a longitudinal cross-sectional view of a conventional continuous casting nozzle.

[Explanation of symbols]

1, 1a Collector nozzle 2, 2a Long nozzle 3,3a Air pocket 4, 5 T-shaped through slit 4', 5' T-shaped cut groove 6, 6a Protective iron skin 7 Inert gas inlet 8 Fireproof mortar 9 Socket surface 10 Long nozzle inner hole 11 Fire-resistant porous member

Claims (8)

[Claims] [Claim 1] On the upper fitting end surface of the continuous casting nozzle,
A plurality of T-shaped grooves are provided, the inner end of which opens into the inner hole surface, and the outer end of which opens into an air pocket having an inert gas inlet,
A continuous casting nozzle characterized in that an inert gas introduction path is formed by adhering a protective iron shell to the outer surface. 2. The continuous casting nozzle according to claim 1, wherein the T-shaped cut groove has an inclined depth that is shallower on the outer end side and deeper on the inner end side. . 3. The continuous casting nozzle according to claim 1, wherein the T-shaped cut groove has a starting point of the vertical groove within 45 m/m from the outer end. Claim 4: The T-shaped cut groove has a double T shape.
Claim 1 characterized in that a plurality of longitudinal grooves are arranged in relation to a flat groove (including a saw blade shape), such as a triple T or the like.
Nozzle for continuous casting. 5. The continuous casting nozzle according to claim 1, wherein the T-shaped cut groove has a vertical groove that widens from the outside toward the inside end. 6. The continuous casting nozzle according to claim 1, wherein the T-shaped cut groove has a longitudinal groove at a constant angle in the horizontal direction with respect to a flat groove. 7. Claim 1, wherein the T-shaped cut grooves are arranged radially on the fitting end surface, and the arrangement angle is set at an angle depending on the purpose with respect to the tangent to the inner hole circle. Nozzle for continuous casting. 8. The continuous casting nozzle according to claim 1, wherein the T-shaped cut groove is arranged in a curved line such as a circular arc on a horizontal plane.