KR100643840B1 - Immersion nozzle for continuous casting - Google Patents

Abstract

The present invention relates to an immersion nozzle during continuous casting, and more particularly, to an immersion nozzle for continuous casting in which a floral cross-sectional shape is formed in a portion of a nozzle to prevent drift of molten steel passing through the immersion nozzle and attachment of inclusions.

The present invention provides a continuous casting immersion nozzle having an inner diameter section of the floral pattern cross section consisting of radial circular grooves in a certain section to prevent drift and inclusion of molten steel passing through the nozzle during the continuous casting process,

The floral pattern inner diameter section (B) is formed a predetermined distance (A) away from the top of the nozzle, at the end of the floral pattern inner diameter section (B) is 1.1 times to 1.5 times larger than the inner diameter formed by the innermost portion of the floral pattern An enlarged inner diameter section C having an inner diameter formed is provided.

As a result, the molten steel can be prevented from drift and the inclusions can be prevented from adhering to the nozzle inner wall, thereby increasing the continuous casting productivity and stabilizing the mold bath surface, thereby improving the steel quality.

Continuous casting, immersion nozzle, flower pattern, drift prevention, inclusion

Description

Submerged entry nozzle for continuous casting

1 is a schematic diagram showing continuous casting from a typical tundish to a mold.

2 is a longitudinal sectional view of a continuous immersion nozzle having a predetermined stepped portion in an inner diameter as an example of a conventional continuous casting immersion nozzle.

Figure 3a and 3b is a longitudinal sectional view and a cross-sectional view of a continuous casting immersion nozzle having a floral pattern forming section and stepped portion as another example of the conventional continuous casting immersion nozzle.

Figure 4 is a longitudinal sectional view of the immersion nozzle for continuous casting according to the present invention.

Figure 5 is a cross-sectional view showing a floral inner diameter section of the immersion nozzle for continuous casting according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100 ... immersion nozzle 101 ... taper section

103.Circular groove 120 ... Discharge outlet

B ... Floral inner diameter section C ... Enlarged inner diameter section

D ... Reduced inner diameter section

The present invention relates to an immersion nozzle during continuous casting, and more particularly, to an immersion nozzle for continuous casting in which a floral cross-sectional shape is formed in a portion of a nozzle to prevent drift of molten steel passing through the immersion nozzle and attachment of inclusions.

In general, the continuous casting process is a process for manufacturing cast steel by continuously injecting molten steel manufactured in a steel making factory through a tundish from the ladle to the mold side, and then solidifying the molten steel.

1 is a schematic view showing continuous casting from a conventional tundish 2 to a mold, in which the molten steel in the ladle 1 is controlled by the sliding plate 3 and supplied to the tundish 2, and the turn The molten steel supplied to the dish 2 is injected into the mold 7 through the immersion nozzle 6 through the sliding plate 3 mounted on the lower portion of the tundish 2 in order to perform continuous casting.

The sliding plate 3 mounted below the tundish 2 includes an upper plate 3a, an intermediate plate 3b, and a lower plate 3c. An upper nozzle 4 is positioned above the upper plate 3a, and an immersion nozzle 6 is installed below the lower plate 3c, and the upper plate 3b is reciprocated left and right. The amount of molten steel supplied from the tundish 2 to the immersion nozzle 6 side is controlled by changing the opening degree connecting 4) and the immersion nozzle 6.

Therefore, the molten steel supplied to the immersion nozzle 6 side through the sliding plate is imparted with the rotational force while hitting the inner diameter surfaces of the sliding plate 3 and the immersion nozzle 6 in turn. A splash phenomenon is generated in the immersion nozzle 6.

This splash phenomenon causes uneven flow of the molten steel in the nozzle, causing a large amount of inclusions to adhere to the inner diameter surface of the immersion nozzle 6. These inclusions close the inner diameter of the immersion nozzle 6, causing uneven flow rate and flow rate, unstable cast or hot water, and reducing casting speed, and in severe cases, causing serious problems such as stopping the casting. It is a major cause of lowering productivity and quality.

As shown in FIG. 2, there is an immersion nozzle 10 in which a predetermined stepped portion 11 is formed inside the nozzle as a method for preventing the above-mentioned drift of molten steel or preventing attachment of inclusions in the nozzle.

The immersion nozzle 10 forms the stepped portion 11 inside the nozzle to prevent the drift of molten steel and the inclusion of inclusions by increasing the flow velocity while the molten steel passes through the nozzle inner diameter relatively narrowed by the stepped portion 11. However, the immersion nozzle 10 can be expected to have only a uniform effect of the molten steel flow in the left and right discharge port (12, 12) side due to the increase in the flow rate of the molten steel, it can completely prevent the molten steel drift in the nozzle. Rather, the stagnation section of the molten steel is formed in the stepped portion 11 and the inclusions are accumulated therein and spread to the adjacent areas, thereby causing the problem of recurring molten steel drift and inclusion inclusions.

On the other hand, as shown in Figure 3, as a conventional method for preventing the drift of molten steel or the adhesion of inclusions in the nozzle is proposed by the present applicant and disclosed in the domestic utility model registration application 2002-15674 "for continuous casting Collector nozzles or immersion nozzles are known.

As shown in Figure 3a, the immersion nozzle 20 has a floral pattern forming section (P) having a floral cross-sectional shape on the top of the nozzle so that the drift phenomenon of the molten steel is suppressed by the centripetal force acting as a central portion of the floral pattern As a result, molten steel is evenly distributed to the discharge port 22 in the lower part of the immersion nozzle 10, and at the same time, the inner diameter of the molten steel is smaller than the inner diameter of the floral pattern forming section P under the floral pattern forming section P. By forming the jaw portion 21 to increase the flow rate of the molten steel passing through the flower pattern forming section (P) to suppress the inclusion of the inclusions in the nozzle.

However, as shown in FIG. 3B, the immersion nozzle 20 has a drift direction in which the molten steel drift generated from the sliding plate 3 enters the flower formation section P except for some circular grooves 23. There was a limit to completely prevent the drift of the molten steel because it can only flow through the floral pattern grooves on the side, as in the case of the former immersion nozzle (10) the inclusions are accumulated in the stepped portion 21 adjacent area Could not solve the problem of spreading.

The present invention has been made in consideration of the above-described conventional problems, the present invention is to prevent the occurrence of vortex and drift in the molten steel passing through the interior of the immersion nozzle during continuous casting and at the same time the cross-sectional shape of the pattern is not attached to the inner wall The purpose is to provide a continuous casting immersion nozzle having a.

In order to achieve the above object, the continuous casting immersion nozzle of the present invention is the inner diameter section of the floral pattern cross-section consisting of radial circular grooves in a certain section to prevent the drift of the molten steel passing through the nozzle during the continuous casting process and attachment of inclusions In the continuous casting immersion nozzle having a, the floral inner diameter section is formed a predetermined distance away from the nozzle top, the end of the floral inner diameter section is 1.1 times to 1.5 times than the inner diameter formed by the innermost portion of the floral pattern An enlarged inner diameter section having a larger inner diameter is formed.

In addition, the floral inner diameter section is preferably formed at a point 50mm to 300mm away from the top of the nozzle.

In addition, the length of the floral inner diameter section is preferably formed to satisfy 50mm to 400mm.

In addition, both ends of the floral inner diameter section may be formed to be tapered so that the inner diameter becomes wider toward the end.

In addition, a reduced inner diameter section may be further formed at a lower portion of the nozzle where the enlarged inner diameter section is finished so that an inner diameter thereof is widened toward both ends and a smaller inner diameter than the enlarged inner diameter section.

In addition, the circular grooves forming the floral pattern are formed to face each other and the number is preferably formed even.

The features and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments based on the accompanying drawings. Prior to this, the terms or words used in the present specification and claims are defined in the technical spirit of the present invention on the basis of the principle that the inventor can appropriately define the concept of the term in order to explain his invention in the best way. It must be interpreted to mean meanings and concepts.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.

4 and 5, the continuous casting immersion nozzle 100 of the present invention is installed in close contact with the bottom of the lower plate (3c) of the sliding plate (3) installed under the tundish (2), continuous In the casting process, the inner diameter section B of the flower pattern cross-section consisting of the circular circular groove portions 103 in a certain section to prevent the drift of the molten steel passing through the immersion nozzle 100 and attachment of inclusions.

Here, the floral pattern cross section has the same shape as the floral pattern cross section described in the prior art, and thus the detailed description thereof will be omitted.

According to the present invention, the floral inner diameter section (B) is formed at a predetermined distance (A) from the top of the nozzle to effectively prevent the drift of the molten steel supplied to the immersion nozzle (100). When the floral inner diameter section (B) is formed at a position away from the nozzle at a predetermined distance (A), the molten steel is deflected to one side in the course of passing through the sliding plate (3), and initially flows only through one region of the floral formation region. By doing so, it is possible to prevent the phenomenon that the molten steel drift is not completely removed in the floral inner diameter section (B).

That is, the molten steel flows into the upper end of the immersion nozzle 100 and is collected inside the nozzle while passing through a predetermined distance (A). At the time passing through the floral inner diameter section (B), the molten steel is evenly introduced throughout the entire region of the floral formation part. The molten steel drift in the floral inner diameter section (B) can be more effectively suppressed.

division Distance from top of nozzle 50mm or less 50 ~ 300mm More than 300mm Vortex Formation plenty Less usually Mold surface state usually Good unrest Left / Right Discharge Drift (Unit: kg / sec) 1.27 0.24 1.42

Table 1 checks the vortex state of the nozzle top and the state of the mold bath surface while varying the distance formed by the floral inner diameter section B from the top of the immersion nozzle 6. As an experiment measuring the difference in the discharge mass, as shown in Table 1, when the floral inner diameter section (B) is formed to be 50mm or less from the upper end of the immersion nozzle 100 or 300mm or more, excessive molten steel vortex is generated. As a result, the molten steel drift deepened.

Therefore, it can be seen that the floral inner diameter section (B) is most preferable when formed 50mm to 300mm away from the top of the immersion nozzle (6).

In addition, as a result of repeated experiments varying the length of the floral pattern forming section, the floral pattern inner diameter section (B) was able to obtain the best results when formed over 50mm to 400mm.

When the floral inner diameter section B is formed to be shorter than 50 mm, the floral inner diameter section B is short so that the drift generated in the molten steel is not completely removed while passing through the floral inner diameter section B. On the other hand, if the floral inner diameter section (B) is formed longer than 400mm, the distance between the lower end of the floral inner diameter section (B) and the discharge port 120 of the immersion nozzle 100 is too short, the floral inner diameter section (B) This is because the molten steel that is faster than the proper flow rate through the exhaust gas is not decelerated, and the discharge holes 120 and 120 are discharged quickly, thereby making the water surface unstable.

Meanwhile, the continuous casting immersion nozzle 6 according to the present invention has an enlarged inner diameter section having an inner diameter d2 larger than the inner diameter d1 formed by the innermost part of the floral pattern at the end of the floral pattern inner diameter section B. Has (C).

If the inner diameter d2 of the enlarged inner diameter section C is smaller than or equal to the floral inner diameter d1, the molten steel flow rate through the section becomes faster and the mold bath surface becomes unstable, such a sudden increase in the molten steel speed. Due to this, a molten steel stagnation zone is formed on the inner diameter of the nozzle, and the inclusions are easily attached.

In addition, when the inner diameter of the enlarged inner diameter section (C) is larger than the flower pattern inner diameter is larger than the proper range, the molten steel speed decreases rapidly and the inclusions are easily attached to the nozzle inner diameter surface.

Therefore, the flow rate of the molten steel should be manufactured within an appropriate range so as not to increase suddenly, and the inner diameter d2 of the enlarged inner diameter section C is 1.1 than the inner diameter d1 formed by the innermost part of the floral pattern through a plurality of repeated experiments. In the case of fold to 1.5 times, the most stable molten steel flow and inclusions were minimized.

On the other hand, both ends of the floral pattern inner diameter section (B) is preferably tapered so that the inner diameter is wider toward the end. If the predetermined tapered section 101 is formed at both ends of the floral pattern inner diameter section B as described above, the molten steel is naturally collected at the center of the floral pattern while passing through the tapered section 101, so that the vortex and drift of the molten steel are further increased. It can be effectively prevented, it is possible to prevent the speed of the molten steel discharged from the floral inner diameter section (B) to be rapidly increased or reduced to maintain the flow of the molten steel stably.

According to the present invention, a reduced inner diameter section D having an inner diameter d3 smaller than the enlarged inner diameter section C may be further formed at a lower portion of the nozzle where the enlarged inner diameter section C is finished.

The reduced inner diameter section (D) collects the molten steel that has passed through the floral inner diameter section (B) and the enlarged inner diameter section (C) to the center of the nozzle and increases the flow rate appropriately, thereby increasing the floral inner diameter section (B). ) And secondly remove the molten steel drift firstly removed while passing through the inner diameter section (C) and completely remove the micro drift in the molten steel.

In this case, the reduced inner diameter section (D) is preferably formed to be round so that the inner diameter is wider toward both ends. In this case, since the molten steel exiting the enlarged inner diameter section C may naturally enter the reduced inner diameter section D, no stagnation of the molten steel occurs, and thus no inclusion is attached to the entrance of the reduced inner diameter section D.

In addition, such a reduced inner diameter section D may be formed in plural as necessary.

On the other hand, the circular groove portion 103 constituting the floral cross section in the floral inner diameter section (B) of the present invention is formed to face each other and the number is preferably made even.

When the circular groove 103 is made to be an odd number, the discharge holes 120 below the immersion nozzle 6 are symmetrically formed on both sides, so that the circular grooves 103 are arranged to be aligned vertically above the discharge holes 120. Since the molten steel exiting the lower end of the circular groove 103 may not be naturally discharged to the discharge hole 120, the molten steel may collide with the inner diameter surface of the nozzle or collide with the molten steel moving from the adjacent circular groove 103. Vortex at the inlet. When the vortex occurs, the discharge property of the molten steel is poor, the amount of drift is increased, and a settling section is generated, and the inclusions are easily attached.

Therefore, if the circular groove portion 103 of the floral pattern to face each other and the number is made even number can be effectively prevented such a phenomenon.

division Number of measurements Casting time (minutes) Inclusion thickness (mm) Measuring part a Measuring part b Measuring part c The present invention Primary 270 2 3 5 Secondary 285 2 3 5 Comparative Example 1 Primary 205 5 8 15 Secondary 235 3 10 13 Comparative Example 2 Primary 200 2 8 10 Secondary 235 3 9 12

Table 2 shows the degree of attachment of the inclusions to the immersion nozzle 100 and the immersion nozzles 10 and 20 having the stepped portions 11 and 21 or the floral pattern forming section P at one side of the nozzle inner diameter part according to the present invention. As a result of the comparison, the thickness of the inclusions was measured while varying the measurement site.

Comparative Example 1 of the present experiment is a conventional immersion nozzle 10 in which the stepped portion 11 is formed to narrow the inner diameter (see FIG. 2), and Comparative Example 2 has an inner diameter section P having a floral cross-sectional shape on one side of the nozzle. A conventional immersion nozzle 20 in which the stepped portion 21 is formed. (See FIG. 3).

As can be seen in Table 2, although the inclusions attached to the inside of the immersion nozzle 100 of the present invention is measured by a longer casting time than Comparative Examples 1 and 2, the immersion nozzle 100 of the present invention is considered to be the least. ) Is very effective in preventing molten steel drift and inclusions.

While the invention has been shown and described with respect to specific embodiments thereof, it will be understood that the invention can be variously modified and varied without departing from the spirit or scope of the invention as set forth in the claims below. It should be included in the scope of the invention.

According to the continuous casting immersion nozzle according to the present invention configured as described above, the floral inner diameter section is formed on the inner wall of the nozzle at a predetermined distance from the top of the nozzle to pass through the floral inner diameter section over the entire region of the floral formation section By flowing evenly to the molten steel drift more completely suppressed in the floral inner diameter section, by forming an enlarged inner diameter section having an inner diameter 1.1 to 1.5 times larger than the inner diameter of the floral pattern at the end of the floral inner diameter section, Effectively prevents drift prevention and inclusion inclusions due to the increase of the proper flow rate of molten steel, which not only improves continuous casting workability, but also stabilizes the mold surface, thereby improving steel quality.

Claims (6)

In the continuous casting immersion nozzle having an inner diameter section of the flower pattern cross-section consisting of radial circular grooves in a certain section to prevent drift of the molten steel through the nozzle during the continuous casting process and to prevent inclusions, The floral pattern inner diameter section is formed a predetermined distance away from the top of the nozzle, the enlarged inner diameter section having an inner diameter is formed 1.1 times to 1.5 times larger than the inner diameter formed by the innermost portion of the floral pattern at the end of the floral pattern inner diameter section is formed Continuous casting immersion nozzle, characterized in that configured to include. The method of claim 1, The floral inner diameter section is Immersion nozzle for continuous casting, characterized in that formed at a point 50mm to 300mm away from the top of the nozzle. The method according to claim 1 or 2, The length of the floral inner diameter section is continuous casting immersion nozzle, characterized in that 50mm to 400mm. The method of claim 1, Both ends of the floral pattern inner diameter section immersion nozzle for continuous casting, characterized in that the tapered so that the inner diameter becomes wider toward the end. The method of claim 1, The submerged nozzle for continuous casting, characterized in that the lower end of the expanded inner diameter section of the nozzle is rounded so that the inner diameter is wider toward both ends and a reduced inner diameter section having an inner diameter smaller than the enlarged inner diameter section. The method of claim 1, Circular grooves forming the floral pattern are formed so as to face each other and the continuous casting immersion nozzle, characterized in that the number is formed in an even number.

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