JPH0715143U - Tundish slag outflow prevention device - Google Patents

Abstract

(57) [Summary] [Objective] To prevent slag from flowing out from the bottom nozzle of a tundish by using an inexpensive stopper device made of steel. [Structure] A stopper device 1 is configured by a cylindrical shell 1A made of steel and a suspension member 1B, and the cylindrical shell 1A is made into a cylindrical shell portion 8
And the truncated inverted conical shell portion 9 in advance. An inflow opening 11 is provided in the upper portion of the cylindrical shell portion 8 for allowing the molten steel 10 poured into the tundish 2 to flow into the mold, and the truncated inverted conical shell portion 9 integrated at the lower end of the cylindrical shell portion 8 is provided. An outflow opening 12 is formed which is seated on the inner peripheral edge 6a of the bottom nozzle 6 and through which the molten steel 10 flows. The cylindrical shell portion 8 and the suspension member 1B are selected to have a thickness that does not melt until a pool of water is formed in the tundish 2, and the truncated inverted conical shell portion 9 has residual heat in the bottom portion of the tundish 2 that causes the bottom nozzle 5 The thickness is selected so that the inner peripheral edge 5b can be closely contacted with the inner peripheral edge 5b to prevent the residual slag 14A from flowing out, and the molten steel 10
It can be melted in.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a tundish slag outflow prevention device, and in detail, before pouring different steel types into the tundish, the bottom nozzle of the empty tundish is closed and the remaining slag is discharged from the continuous casting equipment. The present invention relates to a slag outflow prevention device that prevents the slag from flowing into a continuous slab molding mold.

[0002]

[Prior art]

 When forming molten steel melted in an electric furnace into a continuous slab by continuous casting equipment, the molten steel is secondly refined in a ladle or vacuum degassed, and then poured into a tundish. It is injected from the bottom nozzle into a mold for forming a slab of the desired cross-sectional size. As shown in FIG. 3, a bottom nozzle 5 is formed in the lower part of the tundish 2 having a fireproof wall 3 formed inside the iron skin 2a, and molten steel 10 is molded from the bottom nozzle 5 (not shown). ), And slabs of various steel types such as ordinary carbon steel and alloy steel are continuously formed. By the way, if the same tundish is used even when the steel type of the continuous slab formed by the continuous casting equipment is changed, all the remaining conventional molten steel is poured into the mold to empty the tundish 2. To be done. On the other hand, it is inevitable that the slag 14 produced by refining is poured into the tundish during pouring. Therefore, as the surface of the molten metal lowers, the slag 14 floating on the surface of the molten steel also descends and remains at the bottom of the tundish 2. In that state, if the slag remaining until the molten steel of a different steel type is poured into the mold flows into the mold, the vitreous slag solidifies in the cooled mold and adheres to the mold wall, or when the new steel type is initially used. In some cases, slag may be mixed in the cast slab. In the former case, continuous casting is hindered, and in the latter case, the quality of the slab is partially deteriorated, and slabs that must be discarded are generated, resulting in poor yield. To prevent this, the bottom nozzle of the tundish that has no molten steel is closed when the molten steel of the previous steel type has been injected into the mold to prevent the remaining slag from flowing into the mold. I am trying. That is, when changing the grade of the molten steel 10 poured into the tundish 2, all the molten steel of the preceding steel type is allowed to flow into the mold so that the molten steel of the preceding steel type does not mix with the molten steel of the subsequent steel type. Empty dish 2 Then, the stopper drive mechanism 20 is operated to reduce the lifting cylinder 21, and the stopper rod 23 is lowered via the arm 22 as shown by the chain double-dashed line to close the bottom nozzle 5. The stopper rod 23 is suspended from the tip of the arm 22 and has a columnar shape formed of refractory material and extending vertically. The lower end of the stopper rod 23 is seated in the opening of the bottom nozzle 5. It is said to be a state. When continuously casting the same steel type, the stopper rod 23 is pulled up from the position indicated by the chain double-dashed line to the position indicated by the solid line, and the opening of the bottom nozzle 5 is maintained.

[0003]

[Problems to be solved by the device]

 Molten steel melted in an electric furnace is poured into a tundish in 12 to 13 times through a ladle. During this period, the same steel type is molded into a slab by a mold, but the stopper rod 23 contacts the molten steel 10 and is gradually damaged while the molten steel is being poured into the tundish. Before the molten steel of the next steel type is poured, the stopper rod 23 closes the bottom nozzle 5, but the tip of the stopper rod 23 melts and the seating at the bottom nozzle 5 deteriorates each time. There is a drawback that the function is not maintained for a long time. Therefore, the stopper rod 23 must be discarded and replaced after being used twice or three times, and maintenance work becomes frequent. On the other hand, since a stopper rod made of refractory material is expensive, it is desirable that it should be durable for a long period of time or inexpensive. In addition, since the stopper bar 23 has a weight of about 15 kg, it is not easy for the operator to operate, and the above-described lifting device is required. Further, since the stopper rod 23 is immersed in the molten steel, it is necessary to constantly hold the stopper rod 23 against the buoyancy acting on the stopper rod 23. Therefore, an elevating cylinder is required not only for raising and lowering the stopper rod 23, but also for preventing the stopper rod 23 from floating, and in the end, the stopper device installed in a high temperature atmosphere is complicated and large. It has the drawback of being modeled. Incidentally, although the stopper rod 23 is joined via the metal fitting 24, mortar is used because heat resistance is also required at the joining portion. At the time of the joining, the stop bar 23 is pre-centered so as to come into close contact with the bottom nozzle 5, but the joining work becomes troublesome. After the joining operation, the stopper rods 23 and The metal fitting 24 may be thermally deformed. If the deformation deteriorates the adhesion of the stopper rod to the bottom nozzle, it is necessary to perform centering work again on the reddish tundish, which is a work at a high place, and the work is harsh. There is.

The present invention has been made in view of the above problems, and an object thereof is to provide an inexpensive stopper that does not require maintenance work such as replacement and that has good seatability at the bottom nozzle and prevents slag outflow. It is possible to completely prevent the continuous casting with a high yield, reduce the generation of buoyancy acting on the stopper and eliminate the need for the stopper floating prevention device, and perform centering in harsh environments. It is an object of the present invention to provide a slag outflow prevention device for a tundish that eliminates the need for work.

[0005]

[Means for Solving the Problems]

In the present invention, when molten steel melted in an electric furnace is poured into a tundish from a ladle to form a continuous slab with a mold, the molten steel of the preceding steel type is injected into the mold and becomes empty. Applies to a stopper device that closes the bottom nozzle of a tundish. As for the feature, referring to FIG. 1, the stopper device 1 is made of a steel cylindrical shell 1A extending in the vertical direction and a steel shell 1A for lowering the cylindrical shell 1A from above the tundish 2. And a hanging member 1B. The cylindrical shell 1A is provided with an inflow opening 11 for allowing molten steel 10 poured into a tundish 2 to flow out to a mold (not shown), and a cylindrical shell 8 extending in the up-down direction, and this cylindrical shell 8. The truncated conical shell portion 9 is integrated with the lower end of the shell portion 8, is seated on the inner peripheral edge 5b of the bottom nozzle 5, and has an outflow opening 12 through which the molten steel 10 flows. The cylindrical shell portion 8 and the suspension member 1B are selected to have a thickness t ₁ (see FIG. 2) that does not melt due to the retained heat of the molten steel 10 until a pool of molten metal is formed in the tundish 2, while the truncated head is reversed. The conical shell portion 9 is selected to have a thickness t ₂ (see FIG. 2) that is deformed to such an extent that it can be brought into close contact with the inner peripheral edge 5 b of the bottom nozzle 5 by the residual heat at the bottom of the tundish 2.

[0006]

[Action]

Molten steel 10 melted in an electric furnace is poured into a tundish 2 through a ladle, and a continuous casting facility molds continuous slabs of various steel types such as ordinary carbon steel and alloy steel. When the type of molten steel is changed, the slag floating on the molten steel surface at the time when all of the molten steel previously flowed into the mold remains at the bottom of the tundish. Then, the cylindrical shell 1A is lowered toward the bottom nozzle 5 by the suspension member 1B, and the truncated conical shell 9 is seated on the inner peripheral edge 5b of the bottom nozzle 5. Due to the residual heat at the bottom of the tundish 2, the truncated inverted conical shell 9 having a thickness of t ₂ is red-heated and deformed, and the truncated inverted conical shell 9 comes into close contact with the inner peripheral edge 5b of the bottom nozzle 5. This forms a weir that prevents the outflow of slag and prevents the outflow of residual slag into the mold. In this state, molten steel 10 of different steel type is poured into the tundish 2. When the molten metal 10 rises up to the inflow opening 11 provided at the upper portion of the cylindrical shell portion 8, the molten steel 10 passes from the inflow opening 11 through the inside of the cylindrical shell 1A to the outflow opening 12 and then the mold. And the continuous casting is started. When the pool of tundish 2 becomes large, the cylindrical shell portion 8 made of steel having a thickness t ₁ and the truncated conical shell portion 9 having a truncated conical shape having a thickness t ₂ are also melted by the heat of the molten steel 10. As a result, the cylindrical shell 1A as a stopper disappears, so that it is not necessary to pull it up afterwards. The steel suspension member 1B immersed in the molten steel 10 is also melted, mixed in the molten steel 10 and poured out into the mold. Even if the cylindrical shell 1A and the suspension member 1B are slightly different from the molten steel 10 in steel type, the amount thereof is small and does not affect the quality of the cast slab. As long as the same steel type is poured, it remains as it is, and when the steel type is changed, the cylindrical shell 1A is lowered by the suspension member 1B and consumed each time.

[0007]

[Effect of device]

 According to the present invention, the outflow of slag can be prevented by seating the truncated truncated conical shell on the bottom nozzle. As a result, the inclusion of slag in new steel types is minimized, and high quality and high quality slabs can be formed. The cylindrical shell made of steel will be melted and consumed every time the type of steel is changed, but it can be manufactured much cheaper than a stopper rod made of refractory that can be used several times. . Moreover, the truncated conical shell that sits on the bottom nozzle has a good outflow prevention function because it exhibits good adhesion by utilizing the deformation caused by residual heat. There is no need to raise or center the work. Since the cylindrical shell and the suspension members are melted by the heat of the molten steel, the time required to hold the cylindrical shell in the tundish is short and there is no need to hold it thereafter. It's very easy.

[0008]

【Example】

 Hereinafter, a tundish slag outflow prevention device of the present invention will be described in detail with reference to the drawings showing an embodiment thereof. FIG. 1 shows a state in which the stopper device 1 is arranged at the bottom of the tundish 2. The tundish 2 is used to form a continuous slab by pouring molten steel melted in an electric furnace (not shown) from a ladle and letting the molten steel flow into a mold (not shown) having a desired cross-sectional size. It is something. In this tundish 2, a fireproof wall 3 is formed on an inner surface of an iron skin 2a having a semi-circular lower portion with a cross section having a downward constriction, and an opening 4a is provided at an upper edge of the iron skin 2a. The dish cover 4 is put on. At the bottom, there is a bottom nozzle 5 formed of a refractory material 6 having a passage 5a through which the molten steel poured into the mold flows out, and a sliding nozzle 7 is arranged below the bottom nozzle 5. The stopper device 1 according to the present invention uses the bottom nozzle 5 of the tundish 2 which is emptied by injecting the molten steel of the previous steel type into the mold when the same tundish is continuously used even if the molten steel type is changed. It functions to close.

More specifically, the stopper device 1 includes a long cylindrical shell 1A made of steel that extends in the vertical direction, and a steel suspension member 1B that lowers the cylindrical shell 1A from above the tundish 2. Composed of. The cylindrical shell body 1A includes a cylindrical shell portion 8 and a truncated conical shell portion 9. The cylindrical shell portion 8 extends in the vertical direction, and an inflow opening 11 for letting out the molten steel 10 indicated by a virtual line poured into the tundish 2 to the mold is provided in the upper portion thereof. The truncated conical shell 9 is integrated with the lower end of the cylindrical shell 8 by welding, and is formed at the lower end with an outflow opening 12 that is seated on the inner peripheral edge 5b of the bottom nozzle 5 and is continuous with the internal space to allow the molten steel 10 to flow. To be done.

As a specific example, the outer diameter of the cylindrical shell 1A is about 80 mm, and the length is about 250 mm. The truncated conical shell 9 is a pressed conical steel tube having a length of about 100 mm. In addition, as shown in FIG. 2, about 100 mm of the lower portion of the steel pipe cut to a length of about 350 mm may be formed by drawing into a truncated conical shape. In short, in the cylindrical shell 1A, the inflow opening 11 and It is sufficient that the outflow opening 12 is formed. As the inflow opening 11, the upper opening of the cylindrical shell portion 8 is used as it is in the example of FIG. 1, but in the example of FIG. 2, some holes 11a and 11a are provided on the side surface of the cylindrical shell portion 8 as necessary. Has been. The hole 11a is positioned near the upper end because it functions as the inflow opening described above, but its arrangement and the like are determined in consideration of the length of the cylindrical shell 1A and the required depth of the pool. For the suspension member 1B, a lightweight small-diameter steel pipe or wire having a length of, for example, about 1 m is used. This can stabilize the posture by fixing the center of the hanging wire 13 attached to the upper part of the cylindrical shell 1A, and can lower the cylindrical shell 1A toward the bottom nozzle 5.

The above-mentioned cylindrical shell portion 8 is provided with a thickness t _{1 of,} for example, about 3 mm to 4 mm, which is not melted by the heat retained by the molten steel 10 until a pool of molten metal having a desired depth is formed in the tundish 2. The member 1B is also a wire or bar material having heat resistance equivalent to that of the member 1B. On the other hand, the truncated conical shell 9 is red-heated by the residual heat at the bottom of the tundish 2, for example, 1,560 ° C., and is deformed to the extent that it can be brought into close contact with the inner peripheral edge 5b of the bottom nozzle 5, for example, a thickness t of about 2 mm to 3 mm. Selected as ₂ . By the way, the stopper device 1 has a weight of about 3 kg, and does not impose a burden on the transportation thereof and the operation of preventing the slag from flowing out.

According to the slag outflow preventing device having such a configuration, the bottom nozzle 5 of the emptied tundish 2 is closed so that the remaining slag does not flow into the mold. However, even when the type of steel is changed, continuous cast pieces can be formed without degrading the quality. Molten steel melted in an electric furnace or the like is transferred to a ladle, secondly refined outside the furnace or subjected to vacuum degassing treatment, and then poured into a tundish 2. When the molten steel 10 is successively put into the tundish 2 from the ladle, the slag 14 also floats on the surface of the molten metal as shown by the broken line. Only the heavy molten steel 10 passes through the bottom nozzle 5 and the sliding nozzle 7 and is molded into a cast piece having a desired cross-sectional size. When the steel type is changed and the same tundish 2 is used, most of the remaining molten steel is discharged into the mold. However, as the molten steel surface descends, the slag 14A accumulates on the bottom surface of the tundish 2 where a very small amount of molten steel remains, as shown by the solid line. When new molten steel 10 is poured into the tundish 2 in this state, the slag 14A immediately flows out into the mold, so that the stopper device 1 is lowered.

The slag 14A remaining around the bottom nozzle 5 has a temperature of 1,560 ° C., at which point an operator extends the suspension member 1B while observing the position of the bottom nozzle 5 to lower the cylindrical shell 1A. The truncated truncated conical shell portion 9 is seated on the inner peripheral edge 5b of the bottom nozzle 5, but even if the truncated truncated inverted conical shell portion 9 is not manufactured precisely, the residual heat in the tundish 2 causes a thin thickness t. The steel shell of No. ₂ is softened by red heat and deformed, and adheres to the inner peripheral edge 5b. Therefore, the weir is formed by the cylindrical shell 1A, and the slag is prevented from flowing out from the bottom nozzle 5. By the way, the inverted truncated conical shell portion 9 pushes the slug 14A away when seated, but the slag in the portion in contact with the truncated inverted conical shell portion 9 is rapidly cooled and solidified, so that the residual slag is pushed in the mold direction. There is almost no problem, and even if there is, it is an extremely small amount and does not pose a problem. Molten steels of different steel types are poured into the tundish 2, and the molten steel surface of the pool rises, but the cylindrical shell 1A maintains its seated state by its own weight. It does not melt immediately even if it comes into contact with high temperature molten steel, and when the molten steel surface reaches the inflow opening 11, the molten steel 1 flows out into the mold through the inside of the cylindrical shell 1A as shown by the phantom line in FIG. . At this time, the cylindrical shell 1A is heated from inside and outside by molten steel at 1,650 ° C. When the pouring amount increases, the residual slag floats again on the molten steel surface and mixes with the slag that has been injected together with the new molten steel. After, for example, about 10 minutes have passed after pouring, the cylindrical shell 1A exposed to the molten steel at 1,650 ° C. melts. The suspension member 1 B immersed in the molten steel also melts, and the stopper device 1 disappears at that time. When the desired amount of molten steel is poured, the tundish cover 4 is covered to suppress heat dissipation. As described above, the cylindrical shell 1A and the suspension member 1B are melted and mixed in the molten steel, but they are mixed in a large amount of the molten steel in the tundish 2, so that it affects the steel type. Not the one. While molten steel of the same steel type is being poured one after another, a cast product is continuously formed from the mold, cut after passing through a number of pinch rollers, and a slab of a desired length is manufactured. The slag of the new steel grade will not be entrapped by the residual slag after discharging the old steel grade, and it will be a slab of high quality with the prescribed quality.

As can be seen from the above description, by using this stopper device, it is possible to prevent the slag remaining in the tundish from flowing out and form a high quality cast piece. Most of the stopper device disappears every time the type of molten steel is changed, but this stopper device is extremely inexpensive compared to the stopper made of refractory (see Fig. 3), and its manufacturing accuracy is also high. No need to leave. Moreover, since the molten steel circulates in the cylindrical shell, the cylindrical shell itself does not float, and it is not necessary to press the truncated inverted conical shell portion against the bottom nozzle. Therefore, the structure of the stopper device can be simple. Therefore, maintenance work is almost unnecessary, and further, centering work in the harsh environment required in the case shown in FIG. 3 can be avoided. The present invention can be applied not only when the steel type is intentionally changed, but also immediately when a different steel type occurs due to a component deviation or the like in the steelmaking stage, and casting by that steel type can be made possible. Furthermore, the stopper device can also be used in the following cases. When pouring molten steel into a tundish, bricks on the refractory wall may fall off. In that case, it is possible to prevent the fragments of the brick from getting caught in the molten steel and flowing out to the mold. Also, if there is some kind of accident and there is a delay in tapping from the electric furnace and casting must be interrupted, if it seems to recover in about 10 minutes, use a stopper device to block the outflow of residual molten steel. After that, the casting can be restarted using the same tundish.

[Brief description of drawings]

FIG. 1 is a sectional view when a stopper device is arranged on a tundish.

FIG. 2 is a partially cutaway view of a stopper device having a different shape.

FIG. 3 is a sectional view of a tundish in which a conventional stopper device is arranged.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Stopper device, 1A ... Cylindrical shell, 1B ... Suspension member,
2 ... tundish, 5 ... bottom nozzle, 5b ... inner peripheral edge,
8 ... Cylindrical shell, 9 ... Reversed conical shell, 10 ... Molten steel, 11
... inlet opening, 11a ... hole (inlet opening), 12 ... outlet opening, 14, 14A ... slag, t _1, t ₂ ... thickness.

Claims (1)

[Scope of utility model registration request] 1. When molten steel melted in an electric furnace or the like is poured into a tundish from a ladle to form a continuous slab by a mold, the molten steel of the preceding steel type is injected into the mold and is emptied. In the stopper device for closing the bottom nozzle of the tundish, the stopper device comprises a steel cylindrical shell extending vertically and a steel suspension member for lowering the cylindrical shell from above the tundish. The cylindrical shell body comprises a cylindrical shell portion which is provided at an upper portion with an inflow opening for letting out molten steel poured into the tundish into the mold, and a lower end of the cylindrical shell portion. And a truncated inverted conical shell portion which is seated on the inner peripheral edge of the bottom nozzle and has an outflow opening for flowing molten steel, wherein the cylindrical shell portion and the suspension member are in the tundish. The thickness is selected so that it will not be melted by the heat of the molten steel until the pool of molten metal is formed, and the truncated conical shell is deformed to the extent that it can be adhered to the inner peripheral edge of the bottom nozzle by the residual heat at the bottom of the tundish. The tundish slag outflow prevention device is characterized by being selected for different thicknesses.