KR20010017292A - Device of feeding the molten steel for continuous casting during grade transition - Google Patents

Abstract

PURPOSE: An apparatus for supplying molten steel for sequential casting of dissimilar grades is provided to greatly decrease an amount of steel billet of mixed grades of steel which should be retreated, thereby preventing drop of product prices by greatly preventing recycling and flow stagnation of molten steel in a tundish. CONSTITUTION: A new molten steel in a ladle (10) is supplied into a tundish (100) in which a previous steel remains through an immersion nozzle (20), and injected into a mold through an outlet (30) in an apparatus for sequential casting of dissimilar grades of steel. A dam (3) of an injection area (A) composed of a plurality of refractories is installed stepwise at the injection area (A) near the immersion nozzle (20) in the tundish (100) so that a plurality of pathways through which a downwardly flowing molten steel uniformly passes in a horizontal direction as being collided are uniformly formed. A proceeding area (B) between the immersion nozzle (20) and outlet (30) comprise a plurality of refractories so that a plurality of pathways through which a horizontally proceeding molten steel passes are uniformly formed. A proceeding dam (4) top of which is exposed on surface of molten metal is vertically installed. A discharging dam (5) consisting of a plurality of refractories are vertically installed so that a plurality of pathways through which a molten steel passes are uniformly formed at a discharging area (C) near the outlet (30).

Description

Molten steel supply device for Yonkang type performance casting {DEVICE OF FEEDING THE MOLTEN STEEL FOR CONTINUOUS CASTING DURING GRADE TRANSITION}

The present invention continuously casts only through ladle exchange containing new steel without changing tundish and mold during operation in order to continuously produce steels with different components without stopping the operation The present invention relates to a molten steel supply device that can improve the yield rate of molten steel by minimizing the amount of cast steel produced in an unnecessary production of mixed steels. More specifically, it minimizes recirculation or stagnation of molten steel in a tundish for supplying molten steel to a mold. Therefore, the present invention relates to a molten steel supply device for bi-bar soft casting, which has been improved to reduce the yield of mixed steel by suppressing mixing between newly introduced steel and previous steel.

In order to carry out two-steel soft casting by ladle exchange only for efficient production of various steel grades, the production delay time due to the interruption of operation is reduced and productivity is improved while mixing between steel grades in the tundish and mold occurs. Accordingly, since a large amount of mixed steel cast is produced, the yield of cast steel is lowered.

In this two-bar soft-core operation, the steel mixture is made in the tundish and the mold, respectively, but most steel grades are mixed in the tundish having a larger capacity than the mold. Therefore, researches for minimizing the amount of mixed steel casts generated in the soft steel casting industry have been conducted mainly for mixing in tundish, and through these studies, conventionally replace the tundish in which the old steel remains when exchanging with ladles containing new steel grades. It is known to replace molten metal and to control the molten steel flow in the tundish by installing a refractory structure called a flow control impact pad (FC pad) in the tundish at the bottom of the tundish at the bottom of the ladle nozzle.

However, the conventional method of replacing with a new tundish as described above can solve the mixing of the steel grade in the tundish by completely removing the old steel grade, but there is a problem that the production cost is increased by the increase of the refractory used. In addition, another conventional method of installing a refractory called FC pad in tundish is to vary the shape of the refractory to direct the flow direction of molten steel to the top of tundish to reduce the steel type mixing but still recirculate the flow in tundish. As the section remains, there is a need for further improvement of the steel mixture.

That is, as shown in Fig. 1 (a) (b), when a new steel is introduced into the tundish 100, the old steel species remaining for the two kinds of continuous casting operation, the complex three-dimensional flow in the tundish 100 Due to the flow, various recirculation or stagnation zones are observed. At this time, the old grades existing in the recirculation or stagnation zone are not quickly replaced by the new grades, but are gradually mixed with the new grades over time and then replaced with the new grades to change the outlet 30. Through injection into a mold (not shown) through the production of cast steel of poor mixed steel.

Therefore, the recycling of the molten steel in the tundish 100 or the increase of the stagnant area takes a lot of time until the old steel is replaced with a new steel, resulting in an increase in the amount of mixed steel.

In the conventional case, the molten steel injected from the ladle 10 shows a complicated flow form in the tundish 100, as shown in FIG. 1 (a). In particular, the dam 120 and the weir ( It can be seen that the recirculation and stagnation of the flow is occurring severely around. However, when the dam 120 and the weir 110 are removed, the molten steel injected from the immersion nozzle 20 of the ladle 30 flows to the bottom of the tundish 100 as shown in FIG. It forms a large recirculation area leading to the bottom of the ladle tundish bottom tundish outlet → melt surface.

Therefore, in order to minimize the recirculation zone occurring in the tundish 100 as described above, the molten steel injected from the ladle 10 is uniformly divided in the vertical direction and recycled or vortexed up to the outlet 30 of the tundish 100. It should proceed without occurring.

Accordingly, the present invention has been made to solve the above problems, the object of the molten steel by minimizing the recirculation or stagnation area of the molten steel in the tundish so as to minimize the amount of mixing between the steel grades in the tundish during two-steel continuous casting industry The present invention aims to provide a molten steel supply device for two kinds of cast steel that can flow uniformly within this tundish.

Figure 1 (a) (b) is a state diagram used in the molten steel sheet cast steel according to the prior art,

Figure 2 (a) is a plan view showing a molten steel supply device for two kinds of cast steel according to the present invention,

Figure 2 (b) is a longitudinal cross-sectional view showing a molten steel supply device for two kinds of cast steel according to the present invention,

Figure 3 (a) is a perspective view of the injection portion dam employed in the molten steel supply device for two kinds of cast according to the present invention,

Figure 3 (b) is a perspective view of the traveling part dam, the discharge part dam employed in the molten steel supply device for two kinds of cast according to the present invention,

Figure 4 (a) is a schematic diagram showing the molten steel flow state in the conventional molten steel supply device,

Figure 4 (b) is a schematic diagram showing the molten steel flow state in the molten steel supply apparatus of the present invention.

* Explanation of symbols for the main parts of the drawings *

3 ...... Injection dam 4 ....... Progress dam

5 ...... Exhaust Dam 8a, 8b, 9a, 9b ...... Chamfer

10 ..... Ladle 20 ..... Immersion Nozzle

30 ..... outlet 100 .... tundish

110 .... weir 120 .... dam

The present invention as a technical configuration for achieving the above object,

In a two-bar soft casting system in which a new molten steel in a ladle is supplied through an immersion nozzle into a tundish in which a previous steel remains, and injected into a mold through an outlet.

In the injection region near the immersion nozzle in the tundish, injecting dams formed of a plurality of refractory are formed in a stepwise manner so as to uniformly form a plurality of passages passing evenly in the horizontal direction while colliding with the downward molten steel. In the progress area between the plurality of passages made of refractory to uniformly form a plurality of passages through which the molten steel flowing in the horizontal direction, and vertically installed the progress portion dam exposed on the surface of the hot water, while the discharge near the discharge port The region is provided by providing a molten steel supply device for two kinds of cast steel, characterized in that the discharge portion dam made of a plurality of refractory vertically installed to form a plurality of passages through which the molten steel passes.

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

Figure 2 (a) (b) is a cross-sectional view, longitudinal cross-sectional view showing a molten steel sheet casting molten steel supply apparatus according to the present invention, Figure 3 (a) (b) is employed in the molten steel sheet casting molten steel supply apparatus according to the present invention As a perspective view of the dam member, as shown, the molten steel supply device 1 of the present invention is the injection zone (A), the progress zone (B) and the discharge zone (C) of the tundish 100 is supplied with molten steel from the ladle By installing a plurality of dam members (3) (4) (5) of each of the refractory to the) it is to minimize the recirculation or stagnation area of the molten steel in the tundish (100).

That is, in the tundish 100, the width of the uppermost end is narrower and the width gradually increases toward the lower portion of the injection region A corresponding to the immediate lower portion of the immersion nozzle 20 into which the molten steel of the ladle 10 is injected. An injection section dam 3 in which a plurality of refractory materials 3a, 3b, 3c, and 3d are stepwise constructed is provided vertically.

The injection section dam 3 is composed of a plurality of refractory materials 3a, 3b, 3c, and 3d having different widths as shown in the figure, and refractory structures 3a, 3b, 3c (up and down) are adjacent to each other. A plurality of passages are formed between 3d) to allow molten steel colliding downward in the direction of gravity to pass evenly in the horizontal direction, and the distance between the left end of one side of the top refractory 3a and the left end of the bottom refractory 3d. (L) should be less than twice the diameter of the immersion nozzle 20 supplied with molten steel, and should be directly below the immersion nozzle 20.

In addition, molten steel distributed evenly in the horizontal direction by the injection part dam 3 in the traveling area B between the lower end of the immersion nozzle 20 and the outlet 30 vortex downwards in the tundish 100. It consists of a plurality of refractory (4a) (4b) (4c) (4d) so as to flow through without recirculation, and vertically installs the progression dam (4), the upper part of which is partially exposed on the water surface.

Here, the number of installation of the advanced dam 4 is determined by the ratio of the distance (horizontal) between the immersion nozzle 20 and the discharge port 30 and the height of the molten metal (vertical), When the length of the tundish 100 is longer than the height of 1, the ratio of the width / length exceeds 1, the vortex may be generated in the horizontal uniform flow formed in the injection part dam 3 so that the vortex may be generated. It is necessary to install a plurality in the traveling area (B), and if the length of the tundish 100 is short and the ratio of width / length does not exceed 1, the molten steel fluidity is safe, so that the moving part dam 4 is moved to the traveling area ( There is no need to install multiple in B).

In addition, a plurality of discharge zones (C) near the discharge port (30), as in the progress portion dam (4) to prevent the new vortex and recirculation in the flow due to the discharge port (30) installed in the tundish downstream floor Discharge part dams (5) consisting of two refractory (5a) (5b) (5c) (5d) are installed perpendicular to the front bottom surface of the discharge port (30).

In addition, each passage of the injection part dam 3, the running part dam 4, and the discharge part dam 5 is formed in the middle of the refractory wall stacked in a layer so that the molten steel can flow in the tundish 100 toward the outlet 30. Some of the refractory is removed to form a flow path through which molten steel can escape, and a plurality of vertical and tundish width directions are provided.

Meanwhile, the width of the tundish 10 is enlarged in the injection region A at each upper edge of the tundish 100 having the injection unit dam 3, the advanced unit dam 4, and the discharge unit dam 5. It is maintained in the area (B), and reduced in the discharge area (C) so that the molten steel supplied from the ladle 10 into the tundish 100 can proceed well in a streamline without recirculation, the chamfer having a certain angle of 0 to 80 ° ( 8a) and 8b, respectively, and each of the lower edges of the tundish 100 reduces the injection area A and the discharge area C to reduce the molten steel section mainly occurring at the bottom corner of the tundish 100. The chamfers 9a and 9b each having a predetermined angle of 0 to 80 ° are formed so as to reduce the number.

Referring to the operation and effects of the molten steel supply device for two kinds of cast steel according to the present invention having the configuration as described above are as follows.

As shown in Figure 2 (a) (b), when the molten steel is to be injected into the mold using the molten steel supply device 1 of the present invention, first, the molten steel contained in the ladle 10 is immersion nozzle 20 When the molten steel is supplied into the remaining tundish 100 through the molten steel, the molten steel from the immersion nozzle 20 is supplied to the injection zone A.

That is, a part of the molten steel from the ladle 10 collides with the top refractory 3a of the stepped injection dam 3 and changes the flow direction to 90 ° so that the refractory 3a and the lower refractory 3b are Some of the molten steel flowing horizontally through the passage therebetween and failing to collide with the upper refractory 3a and flowing vertically again collides with the refractory 3b installed below and flows in the horizontal direction. After going through a series of processes that hit the lower refractory (3d) again did not hit and finally to distribute the molten steel from the ladle uniformly and evenly in the vertical direction of the tundish (100).

As a result, the molten steel from the ladle 10 flows to the bottom of the tundish 100 and is gradually converted into the horizontal direction in the flow direction one by one, and evenly to each of the refractories 3a, 3b and 3c. It goes through the passage between (3d) and (3d). At the same time, since the upper and lower edges of the tundish 100 of the injection region A side are reduced by the chamfers 8a and 9a, the recycle section of the molten steel flow is reduced, as well as the stagnation section. This will allow new grades to proceed as they push out older grades quickly.

Continuously, the molten steel evenly distributed in the vertical direction by the injection dam 3 is each refractory 4a, 4b of the traveling dam 4 which is vertically installed while passing through the traveling area B having a constant width. Since it passes through the passage between (4c) and (4d), the molten steel remaining in the tundish 100 is constantly flowed to the discharge port C side to the discharge area C without constant vortex or recirculation, and flows constantly. .

Finally, the molten steel that flows while pushing the previous molten steel to the discharge zone C passes through the passage of the discharge part dam 5 installed perpendicularly to the discharge port 30 and moves the discharge port 30 without vortexing or measuring circulation of the molten steel. It is injected into the mold through. In addition, since the upper and lower edges of the tundish of the discharge area C side have the area reduced by the chamfers 8b and 9b, the recirculation section of the flow is reduced and the stagnant section is reduced. In addition to the rapid supply of new grades, the release of older grades is quicker, reducing the time it takes for these grades to mix.

On the other hand, Figure 4 (a) is a numerical analysis of the flow state of the molten steel when performing two kinds of continuous casting operation using the molten steel supply apparatus according to the prior art, Figure 4 (b) using the molten steel supply apparatus according to the present invention As a result of numerical analysis of the flow state of molten steel during the continuous casting operation of the two kinds of steels, a large recirculation and the entire section were observed in the rear surface of the dam 120 and the weir 110, as shown in FIG. It can be seen. This means that even when a new steel grade is introduced into the tundish 100 from the ladle 10 when the two steel grades are played, the old steel grades in the recycling and stagnation sections are gradually replaced by the new steel grades, so that a lot of time is required until all the mixed steel grades exit the outlet 30. As required, the amount of mixed steel produced increases, leading to cast steel yield.

On the other hand, according to the embodiment of the present invention (the constant angles θ (α) of each chamfer 8a, 8b, 9a, 9b is 0 °, and two running dams 4 are provided). Looking at, a small recycle is observed only in the injection zone (A) in which molten steel is supplied from the ladle 10 to the tundish 100 and the discharge zone (C) discharged from the tundish 100 to the mold, and overall the tundish It can be seen that the flow flows uniformly within. This serves to push the old steel uniformly and quickly to the outlet 30 side when a new steel grade is introduced into the tundish 100 from the ladle 10 for the performance of the two steel grades, and finally the mixed steel grade is tundish ( The time to exit all the 100 is shortened, and as a result, the amount of mixed steel produced is drastically reduced, thereby improving the yield of cast steel.

According to the present invention as described above, since the recirculation and stagnation of molten steel flow in the tundish can be largely prevented, the production of new and mixed steel grades supplied in two-steel soft casting industry significantly reduced, thereby By greatly reducing the amount of cast steel that needs to be reprocessed, it is possible to prevent a drop in product cost, improve the yield rate of cast steel, and to obtain orders for small quantities of various types of products, thereby improving economic benefits.

Claims (4)

In a two-steel type casting system in which a new molten steel in the ladle 10 is supplied through the immersion nozzle 20 into the tundish 100 in which the previous steel remains, and injected into the mold through the discharge port 30, Injecting part dam (3) made of a plurality of refractory materials to uniformly form a plurality of passages uniformly passing in the horizontal direction while colliding downward with the injection region (A) near the immersion nozzle (20) in the tundish (100) (3) ) Is installed stepwise, in the traveling area (B) between the immersion nozzle (20) and the discharge port (30) is made of a plurality of refractory to uniformly form a plurality of passages through which molten steel proceeds in a horizontal direction, While the upper end is installed vertically in the dam portion (4) exposed to the hot water surface, the discharge area (C) near the discharge port 30 is discharged made of a plurality of refractory to form a plurality of passages through which molten steel passes uniformly A molten steel supply device for two kinds of cast steel, characterized in that the installation of the vertical dam (C). The method of claim 1, The distance L between the left end of one side of the top refractory 3a of the injection part dam 3 and the left end of the bottom refractory 3d should be within two times the diameter of the immersion nozzle 20 to which molten steel is supplied. A molten steel supply device for two kinds of cast steel, characterized in that directly below the immersion nozzle (20). The method of claim 1, In each upper edge of the tundish 100, the width of the tundish 10 is enlarged in the injection zone A, maintained in the entry zone B, and reduced in the discharge zone C in the ladle 10. A molten steel supply device for two kinds of cast steel, characterized in that to form a chamfer (8a) (8b) each having a predetermined angle of 0 to 80 ° so that the molten steel supplied into the tundish 100 can proceed well in a streamline without recirculation. The method of claim 1, Each lower edge of the tundish 100 has a predetermined angle of 0 to 80 ° to reduce the injection zone (A) and the discharge area (C) to reduce the molten steel stagnant section that occurs mainly at the bottom corner of the tundish (100). A molten steel supply device for two kinds of cast steel, characterized in that each having a chamfer (9a) (9b) having a.