KR100786484B1 - Tundish for continuous casting - Google Patents

Abstract

A tundish used in continuous casting is provided to disperse powder into molten metal uniformly and efficiently with a feeder for adjusting composition of constituents in the molten metal. A tundish used in continuous casting has a region(A) where molten metal is transferred, a region(C) where hot metal stored in the tundish is drained, a region(B) which is located between the regions as a main body(210) of a holding bath, a feeder(230) which supplies wire(400) wrapped powder around a hoop to hot metal for adjusting composition of elements, and a submerged nozzle(234) at the region of draining hot metal. The feeder supplying powder has a wire feeder(235), a tube(231) to providing a passageway to introduce the wire to the molten metal in the holding bath, and an impeller(233) mounted on outer surface at an end of the wire tube.

Description

Tundish for Continuous Casting

1 is a conceptual diagram of a continuous casting facility of steel according to the prior art.

Figure 2 is a cross-sectional view of the tundish used in the continuous casting equipment for steel according to one embodiment of the present invention.

Figure 3 is a cross-sectional view of the wire used in the tundish according to one embodiment of the present invention.

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

100: ladle 200: tundish

210: container body 220: immersion nozzle

230: fine particle feeder 231: wire tube

233 impeller 234 nozzle

235 wire feeder 237 drive motor

239: power transmission means 300: mold

400: wire 410: fine particles

420: hoop

The present invention relates to a tundish used in the continuous casting process of the present invention, and more particularly, to a tundish having a feeder for supplying fine particles for ingredient adjustment.

The continuous casting process is generally a method of manufacturing slabs, blooms, billets, etc. by continuously injecting molten steel into a mold and cooling and solidifying the mold by eliminating casting, mold, crack, and rolling of ingot cases.

Korean Patent Publication No. 10-2006-0126288 describes this general continuous casting process. 1 shows a typical continuous casting installation described in the document.

According to this, in the continuous casting facility, the tundish 2 is positioned at the lower part of the ladle 1 for transporting molten steel, and the tundish nozzle 3 is installed at the bottom of the tundish 2 to discharge the molten steel. On the other hand, a mold 4 for producing molten steel as a billet having a predetermined thickness and width is installed at the lower part of the nozzle 3, and a plurality of pinch rolls 5 for guiding the billet is provided at the lower end of the mold 4. It is installed.

This continuous casting facility is made in such a way that the molten steel injected from above solidifies into the cross-sectional shape of the mold 4 as it flows down through the mold 4.

The molten steel with which the temperature is precisely adjusted is transported by the ladle 1 and injected into the inside of the tundish 2 through the tap hole formed under the ladle 1. In the tundish 2, the inclusions of the molten steel are separated and floated, and when the injection of the molten steel is completed, the tundish 2 is placed on the bottom of the tundish 2.

The molten steel flows out by opening the tundish nozzle 3 which has been set. The molten steel flowing out at this time is injected into the mold 4 to produce a bilet having a predetermined thickness and width inside the mold 4, and then guides the plurality of pinch rolls 5 installed at the bottom of the mold 4. To receive and move.

On the other hand, it is required to develop low-cost products that do not contain nickel (Ni), which is excellent in mechanical properties, such as stainless steel. Need development

To this end, the technology of securing 70% or more of equiaxed crystals in ferritic stainless steel by uniformly dispersing the component adjustment fine particles in molten steel has become an important technical problem.

In order to evenly insert the fine particles, it is preferable to insert the fine particles in the tundish process of the continuous casting process, but when the fine particles are added in the ladle process, the standby time is required in most continuous casting processes, which acts as a nucleus during solidification. There is a disadvantage in that it does not dissolve, and when the fine particles are injected in the molding process, the input device is complicated and there is a disadvantage that it is not evenly distributed as a whole.

Therefore, the tundish, which is a part that receives hot molten steel from the ladle and supplies molten steel with reduced inclusions, is evaluated as an optimal position that can be used to uniformly distribute fine particles.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a continuous casting tundish having a feed mechanism for adjusting the fine particles.

Continuous casting tundish according to an embodiment of the present invention is a container body partitioned into an internal space A region into which molten steel flows in, C region in which molten steel flows out, and B region located between the A region and the C region ; A fine particle feeder for supplying a wire composed of a constituent fine particle and a hoop surrounding the fine particle into the B region; And an immersion nozzle provided in the C region, wherein the fine particle feeder comprises: a wire feeder; And a wire tube providing a path for introducing the wire supplied from the wire feeder into the molten steel of the container body. And it characterized in that it comprises an impeller provided on the outer surface of the end of the wire tube.

(k는 후프재료에 따라 용강에서 정해지는 용해 속도상수(1/s), a(mm)는 임펠러의 하부와 턴디쉬의 바닥의 거리를 , b는 턴디쉬의 용강의 수위와 임펠러의 하부사이의 거리, V(m/s)는 와이어의 전송속도이다.)을 만족하는 것이 바람직하다. At this time, the thickness of the hoop of the wire

(k is the melt rate constant (1 / s) determined in molten steel depending on the hoop material, a (mm) is the distance between the bottom of the impeller and the bottom of the tundish, b is between the level of molten steel in the tundish and the bottom of the impeller) It is desirable to satisfy the distance, V (m / s), which is the transmission speed of the wire.

In addition, it is preferable that the boundary between the area A and the area B consists of a dam and a dam, and the boundary between the area B and the area C consists of a second dam protruding from the bottom of the container.

In addition, the wire tube is preferably rotated by a power transmission means for transmitting power from the rotary motor.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 2 is a cross-sectional view of the tundish used in the continuous casting process according to an embodiment of the present invention. Portions indicated by the dotted lines are ladle 100 and mold 300.

According to this, the tundish largely includes the container body 210, the fine particle supply 230, and the immersion nozzle 220.

The container body 210 retains the molten steel until the molten steel flowing from the ladle 100 through the tap hole 110 flows into the mold through the immersion nozzle 220. At this time, the outlet 110 through which the molten steel flows is provided in the region A in the container body 210 and the immersion nozzle 220 flowing out in the region C, so that the molten steel extends the retention path in the container body 210. .

At this time, the B region is provided between the A region and the C region, the B region is a region in which the impeller 233 of the fine particle supplier 230 rotates. Areas A and B are bounded by the dam 250 and the first dam 260, and areas B and C are bounded by a second dam 270 protruding therein.

The fine particle feeder 230 provided in the region B includes a wire feeder 235, a wire pipe 231, an impeller 233, a drive motor 237, and a power transmission means 239.

The wire feeder 235 may be configured as a roller or the like as a device for supplying the wire 400.

On the other hand, the wire 400 is a material for supplying a material for adjusting the composition, a cross-sectional view of the wire is shown in FIG. According to this, the wire 400 has a structure in which the constituent fine particles 410 are included inside and the hoop 420 is wrapped around the outside thereof. The material of the fine particles 410 or the hoop 420 may vary depending on the steel to be manufactured, and embodiments of the present invention are not limited thereto. For example, the hoop 420 may be stainless.

The wire feeder 235 is passed through the wire 400 is a device for introducing into the area B in the container body (210). A nozzle 234 for injecting the wire 400 into the molten steel is formed at an end of the wire feeder 235, and an impeller 233 is provided at an end outer surface of the wire feeder 235.

The impeller 233 rotates by the rotational force generated by the drive motor 237. That is, when the driving motor 237 is driven, the driving force rotates the wire tube 231 by the power transmission means 239, and as the wire tube 231 is rotated, the outer end of the wire tube 231 is provided. Impeller 233 is also rotated.

At this time, the impeller 233 is preferably spaced apart from the bottom surface of the container body at a predetermined interval. The material of the impeller 233 may be alumina.

On the other hand, in order to more efficiently disperse the fine particles 410 included in the hoop 420 of the wire 400 by the rotation of the impeller 233, it is preferable to set the height of the hoop to satisfy the following equation. .

Where k is the dissolution rate constant (1 / s) determined in molten steel according to the hoop material, a (mm) is the distance between the bottom of the impeller and the bottom of the tundish, b is the level of the molten steel of the tundish and the bottom of the impeller The distance between them, V (m / s), is the transmission speed of the wire.

The immersion nozzle 220 in the region C is located at the bottom of the container body 210 to allow molten steel to flow out, and the opening is determined by the operation of the upper stopper 240.

Looking at the flow of the molten steel in the tundish 200, first, the molten steel is introduced into the A region of the container body 210 through the outlet 110 of the ladle 100, the weir 250 and the dam 260 It moves to area B through it.

In region B, the wire 400 is injected into the molten steel. Area B is a point where the turbulent flow of the molten steel is minimized in the container body 210. The injected wire 400 has a hoop 420 dissolved therein so that the fine particles 410 therein are dispersed into the molten steel through the nozzle 234 at the end of the wire. At this time, the fine particles are efficiently dispersed in the molten steel by the rotation of the impeller 233 adjacent to the nozzle 234 of the wire tube 231.

Molten steel in which fine particles are efficiently dispersed is moved to the C region and flows out into the mold through the immersion nozzle 220.

Experimental Example

In continuous casting of 436L ferritic stainless steel, the cast steel having a casting thickness of 200 mm was installed at a tundish as shown in FIG. 2 and cast at a casting speed of 1.0 mpm.

In this continuous casting operation, after performing a casting experiment as shown in Table 1 to confirm the effect of the present invention, the section of the cast steel was cut to confirm the equiaxed crystal and surface quality.

Fine particle input area Rotation Equiaxed Surface quality Comparative Example 1 Not input Unturned 28% Good Comparative Example 2 A Unturned 39% Inferior Comparative Example 3 A rotation 54% Inferior Comparative Example 4 B Unturned 45% Good Example B rotation 70% Good

According to Table 1, it was confirmed that the surface quality and the equiaxed crystallization rate of the steel were changed by affecting the uniformity of the microparticles according to the input area of the microparticles and the rotation of the impeller. That is, it was confirmed that the case of the example in which the fine particles were put in the B region and the impeller was rotated was the most excellent in isometric constant and surface quality.

Meanwhile, FIG. 4 is a graph illustrating embodiments in which the thickness of the hoop of the wire is measured according to the distance between the impeller and the bottom surface of the container body (the tundish bottom).

Although the present invention has been described primarily with reference to the above embodiments, many other possible modifications and variations can be made without departing from the spirit and scope of the invention. For example, a change in the shape of the impeller, a change in the position and shape of an internal dam or weir of the tundish.

The continuous casting tundish of steel according to the present invention has a fine particle feeder capable of injecting fine particles for adjusting ingredients into the tundish, so that the fine particles can be efficiently dispersed, and thus the amount of equiaxed crystals generated in the center of the cast steel. There is an effect that can increase.

The scope of the above-described invention is defined in the following claims, not bound by the description in the specification body, all modifications and variations that fall within the equivalent scope of the claims will fall within the scope of the invention.

Claims (4)

A container body partitioned into an internal space A region into which molten steel flows in, a C region into which molten steel flows out, and a B region located between the A region and the C region; A fine particle feeder for supplying a wire composed of a constituent fine particle and a hoop surrounding the fine particle into the B region; And It includes an immersion nozzle provided in the C region, The fine particle feeder, Wire feeder; And A wire tube providing a path for introducing the wire supplied from the wire feeder into the molten steel of the container body; And A tundish for continuous casting process, characterized in that it comprises an impeller provided on the outer surface of the end of the wire tube. The method of claim 1, The thickness of the hoop of the wire is represented by Equation 1 (Equation 1)

(k is the melt rate constant (1 / s) determined in molten steel depending on the hoop material, a (mm) is the distance between the bottom of the impeller and the bottom of the tundish, b is the level of molten steel in the tundish and the bottom of the impeller) The distance between them, V (m / s), is the transmission speed of the wire.) Tundish for continuous casting process, characterized in that to satisfy. The method of claim 1, The boundary between the regions A and B is composed of a dam and a first dam, and the boundaries of the regions B and C are composed of a second dam protruding from the bottom of the container.  The method of claim 1, The wire tube, Tundish for continuous casting process, characterized in that the rotation by the power transmission means for transmitting power from the rotating motor.

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