JP7010158B2 - Thin-walled slab manufacturing equipment and thin-walled slab manufacturing method - Google Patents

Description

The present invention relates to a thin-walled slab manufacturing apparatus for supplying molten metal to a molten metal pool portion formed by a pair of cooling drums and a pair of side dams to manufacture thin-walled slabs, and a method for manufacturing thin-walled slabs. It is a thing.

As a device for producing thin-walled metal slabs, a pair of cooling drums having a water-cooled structure inside and rotating in opposite directions are provided, and melted in a molten metal pool portion formed by a pair of cooling drums and a pair of side dams. Metal is supplied, a solidified shell is formed and grown on the peripheral surface of the cooling drum, and the solidified shells formed on the outer peripheral surfaces of the pair of cooling drums are pressure-bonded at the drum kiss point to form a thin-walled slab of a predetermined thickness. A twin-drum type continuous casting device (a device for manufacturing thin-walled slabs) is provided. Such a thin-walled slab manufacturing apparatus is applied to various metals.

In the above-mentioned thin-walled slab manufacturing apparatus, for example, as shown in Patent Document 1, molten metal is continuously supplied from a tundish arranged above the cooling drum to the molten metal pool portion via a dipping nozzle. The molten metal solidifies and grows on the peripheral surface of the rotating cooling drum to form a solidified shell. Then, the solidified shell formed on the peripheral surface of each cooling drum is crimped at the drum kiss point to produce a thin-walled slab.

In such a thin-walled slab manufacturing apparatus, the molten metal is brought into direct contact with the cooling drum without using mold powder or the like. Therefore, the surface of the molten metal pool portion is exposed to the atmospheric gas.
Therefore, in the above-mentioned thin-walled slab manufacturing apparatus, a chamber is arranged so as to surround the molten metal pool portion, and the inside of this chamber is made into an inert gas atmosphere to suppress oxidation of the molten metal and the like. ..

In the above-mentioned thin-walled slab manufacturing apparatus, since the cooling drum used as a mold is rotated, it slides at the contact point between the chamber and the cooling drum, so that a slight gap is generated. Further, since the inside of the chamber becomes a high temperature environment, the chamber itself is thermally deformed and the shape of the gap changes with time. Therefore, it was difficult to increase the degree of sealing of the chamber and completely prevent the invasion of external atmospheric gas.
Therefore, when the thin-walled slab is manufactured using the above-mentioned thin-walled slab manufacturing apparatus, the amount of the inert gas introduced into the chamber is increased so that the pressure in the chamber is higher than that of the outside air. , The invasion of outside air is suppressed.

However, if the amount of the inert gas introduced into the chamber is increased, the molten metal may undulate due to the blowing of the inert gas and the temperature of the molten metal may drop, resulting in unstable solidification. there were. In addition, if the pressure inside the chamber is increased, there is a difference in the speed and pressure at which the gas is ejected between the place where the gap is large and the place where the gap is small, and the outside air may be sucked in from the place where the pressure is low, and the sealing property may be deteriorated. rice field.

Therefore, for example, Patent Document 2 proposes dropping a liquefied gas obtained by liquefying an inert gas in the vicinity of the molten metal pool portion in the chamber.
In Patent Document 2, the contact between the molten metal and the outside air is prevented by vaporizing the liquefied gas obtained by liquefying the inert gas near the surface of the molten metal. Further, by blocking the molten metal surface from the outside air with a small amount of gas, the pressure inside the chamber does not rise more than necessary.

Japanese Unexamined Patent Publication No. 2004-283869 Japanese Unexamined Patent Publication No. 61-180653

By the way, as shown in Patent Document 2, when the liquefied gas is dropped in the vicinity of the molten metal surface, the liquefied gas is immediately vaporized at the dropped portion and the entire molten metal surface is inactive. It was very difficult to cover with gas. Further, the heat of vaporization when the liquefied gas is vaporized may locally cool the molten metal, generate solidified foreign matter, and disturb the formation of the solidified shell.
Further, in the vicinity of the side weir, since the cooling drum and the side weir are in contact with each other, it is a place where outside air easily enters and a place where molten metal easily stays. Therefore, when the liquefied gas is dropped in the vicinity of the side weir, the temperature of the molten metal is particularly lowered and solidified foreign matter is likely to be generated, which may cause the casting to become unstable.

The present invention has been made in view of the above-mentioned situation, and the liquefied gas obtained by liquefying the inert gas can be uniformly vaporized on the molten metal surface, and the molten metal surface can be uniformly vaporized. It is an object of the present invention to provide a thin-walled slab manufacturing apparatus capable of stably casting by blocking from the outside air by covering with a thin-walled slab, and a method for manufacturing thin-walled slabs.

In order to solve the above problems, the thin-walled slab manufacturing apparatus according to the present invention supplies molten metal to a molten metal pool portion formed by a pair of rotating cooling drums and a pair of side dams, and supplies the molten metal to the cooling drum. It is a thin-walled slab manufacturing device that forms and grows a solidified shell on the peripheral surface to manufacture thin-walled slabs. A chamber is arranged above the molten metal pool portion and the cooling drum, and this chamber is provided. A liquefied gas introduction section for introducing a liquefied gas obtained by liquefying an inert gas is provided therein, and the liquefied gas introduced by the liquefied gas introducing section is impregnated above the molten metal pool section in the chamber. It is characterized in that a vaporizer for vaporizing is arranged.

According to the thin-walled slab manufacturing apparatus having this configuration, a vaporizer that impregnates and vaporizes the liquefied gas obtained by liquefying the inert gas is arranged above the molten metal pool portion in the chamber. Since the liquefied gas introduced therein is vaporized in a state of being impregnated in the vaporizer, the liquefied gas can be uniformly vaporized on the molten metal pool portion and the molten metal pool portion. By covering with an inert gas, it is possible to shield from the outside air and perform stable casting.
That is, since the liquefied gas is vaporized not only at the place where the liquefied gas is introduced but also in the entire vaporizer, the entire surface of the molten metal can be covered with the inert gas, and the surface of the molten metal pool is covered with outside air. Can be blocked from.

Here, in the thin-walled slab manufacturing apparatus of the present invention, it is preferable that a height adjusting means for adjusting the height position of the vaporizer is provided in the chamber.
In this case, even if the height of the molten metal pool portion fluctuates, the height position of the molten metal of the vaporizer from the molten metal can be kept constant, and the liquefied gas is stably vaporized. It is possible to cover the surface of the molten metal with an inert gas.
Further, by retracting the vaporizer at the start of casting, it is possible to prevent the splash and the like generated at the time of injecting the molten metal from adhering to the vaporizer.

Further, in the thin-walled slab manufacturing apparatus of the present invention, it is preferable that the height adjusting means adjusts the height position of the vaporizer along the peripheral surface of the cooling drum.
In this case, even if the height of the molten metal pool portion fluctuates, the vaporizer can be arranged near the cooling drum of the molten metal pool portion, and the liquefied gas is stably vaporized to form the molten metal. It is possible to cover the surface of the hot water with an inert gas.

Further, in the thin-walled slab manufacturing apparatus of the present invention, the liquefied gas introduction unit is provided with a liquefied gas holder and a liquefied gas introduction pipe for introducing liquefied gas into the chamber from the liquefied gas holder. preferable.
In this case, since the liquefied gas holder is provided, the liquefied gas can be stably introduced into the chamber. Further, even when the liquefied gas is vaporized in the liquefied gas introduction pipe, the backflowing gas can be received by the liquefied gas holder, and damage to the equipment on the upstream side of the liquefied gas holder can be suppressed.

In the method for producing a thin-walled slab according to the present invention, molten metal is supplied to a molten metal pool portion formed by a pair of rotating cooling drums and a pair of side dams, and a solidified shell is formed on the peripheral surface of the cooling drum. A method for producing a thin-walled slab by growing it to produce a thin-walled slab, wherein a chamber is disposed above the molten metal pool portion and the cooling drum, and the molten metal pool portion in the chamber is provided. A vaporizer that impregnates and vaporizes the liquefied gas obtained by liquefying the inert gas is disposed above, and the liquefied gas is introduced into the vaporizer, and the molten metal surface of the molten metal pool portion is exposed to the inert gas. It is characterized by covering with.

According to the method for producing a thin-walled slab having this configuration, a liquefied gas obtained by liquefying an inert gas is introduced into a vaporizer arranged above the molten metal pool portion in the chamber, and the inside of the chamber is inactivated. Since the gas atmosphere is used, the liquefied gas can be uniformly vaporized on the molten metal surface of the molten metal pool portion by vaporizing the liquefied gas in a state of being impregnated in the vaporizer. Therefore, by covering the molten metal surface of the molten metal with an inert gas, it is possible to shield from the outside air, and stable casting can be performed.

Here, in the method for producing a thin-walled slab of the present invention, the height position of the vaporizer is adjusted according to the height of the molten metal pool portion, and the height of the vaporizer from the molten metal surface is adjusted. It may be configured to maintain the position within a certain range.
In this case, even if the height of the molten metal pool portion fluctuates, the height position of the vaporizer from the molten metal surface is maintained within a certain range, so that the liquefied gas is stably vaporized. This makes it possible to cover the surface of the molten metal with an inert gas.

Further, in the method for producing a thin-walled slab of the present invention, the liquefied gas is placed in the chamber so that the difference P1-P0 between the pressure P1 and the atmospheric pressure P0 in the chamber is within the range of 10 Pa or more and 500 Pa or less. It may be a configuration to be introduced in.
In this case, by setting the difference P1-P0 between the pressure P1 and the atmospheric pressure P0 in the chamber to 10 Pa or more, it is possible to accurately suppress the intrusion of outside air into the chamber and perform more stable casting. Will be. Further, by setting the difference P1-P0 between the pressure P1 and the atmospheric pressure P0 in the chamber to 500 Pa or less, the seal gas is unevenly ejected from a part of the seal portion to suck the outside air into the chamber. Can be suppressed.

As described above, according to the present invention, the liquefied gas obtained by liquefying the inert gas can be uniformly vaporized on the molten metal surface, and the molten metal surface is covered with the inert gas from the outside air. It is possible to provide an apparatus for producing a thin-walled slab that can be cut off and stably cast, and a method for producing a thin-walled slab.

It is a schematic explanatory drawing of the manufacturing apparatus of the thin-walled slab used when carrying out the manufacturing method of the thin-walled slab which is an embodiment of this invention. It is sectional drawing in the vicinity of the molten steel pool part of the thin-walled slab manufacturing apparatus shown in FIG. It is a perspective explanatory view of the vicinity of the molten steel pool part of the thin-walled slab manufacturing apparatus shown in FIG.

Hereinafter, the apparatus for producing thin-walled slabs and the method for producing thin-walled slabs according to the embodiment of the present invention will be described with reference to the attached drawings. In the following embodiments, the metal to be cast will be described as steel. The present invention is not limited to the following embodiments.

Here, as the steel type constituting the thin-walled slab 1 manufactured in the present embodiment, for example, 0.001 to 0.01% C ultra-low carbon steel, 0.02 to 0.05% C low carbon steel, and the like. 3. 0.06 to 0.4% C medium coal steel, 0.5 to 1.2% C high coal steel, austenite stainless steel represented by SUS304 steel, ferrite stainless steel represented by SUS430 steel, 3. Examples thereof include 0 to 3.5% Si directional electromagnetic steel, 0.1 to 6.5% Si non-directional electromagnetic steel, and the like (% is mass%).
Further, in the present embodiment, the size of the thin-walled slab 1 to be manufactured is, for example, within the range of 500 mm or more and 2000 mm or less in width and 1 mm or more and 5 mm or less in thickness.

As shown in FIG. 1, the thin-walled slab manufacturing apparatus 10 according to the present embodiment includes a pair of cooling drums 11, 11 and pinch rolls 12, 12, and 13, 13 that support the thin-walled slab 1. The molten steel 3 introduced into the side weir 15 arranged at the widthwise end of the pair of cooling drums 11 and 11 and the molten steel pool portion 16 defined by the pair of cooling drums 11 and 11 and the side weir 15. It is provided with a tundish 18 for holding the tundish 18 and a dipping nozzle 19 for introducing the molten steel 3 from the tundish 18 into the molten steel pool portion 16.

In the thin-walled slab manufacturing apparatus 10, the solidified shells 5 and 5 grow on the peripheral surfaces of the cooling drums 11 and 11 by contacting and cooling the molten steel 3 in contact with the rotating cooling drums 11 and 11. The solidified shells 5 and 5 formed on the pair of cooling drums 11 and 11 are pressure-bonded to each other at the roll kiss point, whereby the thin-walled slab 1 having a predetermined thickness is cast.

FIG. 2 shows an enlarged explanatory view around the molten steel pool portion 16 in FIG. In the thin-walled slab manufacturing apparatus 10 of the present embodiment, as shown in FIG. 2, a chamber 20 is arranged above the molten steel pool portion 16 and the cooling drums 11 and 11.
Since the end portion of the chamber 20 is slidably contacted with the peripheral surface of the rotating cooling drums 11 and 11, there is a slight amount between the end portion of the chamber 20 and the peripheral surface of the cooling drums 11 and 11. There is a gap.

Further, in the thin-walled slab manufacturing apparatus 10 according to the present embodiment, as shown in FIG. 2, a liquefied gas introduction unit 40 for introducing the liquefied gas obtained by liquefying the inert gas is provided in the chamber 20. As the liquefied gas obtained by liquefying the inert gas, it is preferable to use argon gas, nitrogen gas or the like.
Further, above the molten steel pool portion 16 in the chamber 20, a vaporizer 30 that impregnates and vaporizes the liquefied gas introduced by the liquefied gas introducing portion 40 described above is arranged.

The vaporizer 30 has a structure impregnated with liquefied gas as described above, and is composed of, for example, a ceramic filter, a ceramic fiber sheet, a ceramic wool, or the like having heat resistance.
In the present embodiment, the vaporizer 30 has a structure in which the above-mentioned porous sheet material is attached to a frame body.

Here, it is preferable that the thickness of the sheet material of the porous body constituting the vaporizer 30 is within the range of 2 mm or more and 40 mm or less.
By setting the thickness of the sheet material of the porous body constituting the vaporizer 30 to 2 mm or more, the vaporizer (sheet material of the porous body) can be sufficiently impregnated with the liquefied gas. On the other hand, by setting the thickness of the sheet material of the porous body constituting the vaporizer to 40 mm or less, radiant heat is efficiently transmitted, and the impregnated liquefied gas can be accurately vaporized.
The lower limit of the thickness of the sheet material of the porous body constituting the vaporizer 30 is preferably 5 mm or more, and more preferably 10 mm or more. Further, the upper limit of the thickness of the sheet material of the porous body constituting the vaporizer 30 is preferably 30 mm or less, more preferably 25 mm or less.

In the present embodiment, it is preferable that the vaporizer 30 extends along the axis of the cooling drum 11 as shown in FIG.
The vaporizer 30 is preferably not arranged within a range of 50 mm from the axial end of the cooling drum 11. This is because the side weir 15 is arranged at the axial end of the cooling drum 11 and is a region where the temperature of the molten steel 3 tends to decrease, so that the temperature of the molten steel 3 is further suppressed due to the heat of vaporization. Is.

Further, in the present embodiment, as shown in FIGS. 2 and 3, it is preferable that the height adjusting means 35 for adjusting the height position of the vaporizer 30 is provided in the chamber 20.
Further, it is preferable that the height adjusting means 35 has a mechanism for adjusting the height position by moving the vaporizer 30 along the peripheral surface of the cooling drum 11.

Further, in the present embodiment, as shown in FIG. 2, the liquefied gas introduction unit 40 includes a liquefied gas holder 42, a liquefied gas supply means 43 for supplying the liquefied gas of the inert gas to the liquefied gas holder 42, and the liquefaction gas holder 42. It is preferable to include a liquefied gas introduction pipe 41 for introducing the liquefied gas into the chamber 20 from the gas holder 42, and a pressure adjusting means 44 for adjusting the internal pressure in the liquefied gas holder 42.
Then, in the present embodiment, as shown in FIGS. 2 and 3, the tip of the liquefied gas introduction pipe 41 is connected to the vaporizer 30, and the liquefied gas introduction pipe 41 allows the vaporizer 30 to be placed in the chamber 20. It is supported.

Further, in the present embodiment, as shown in FIG. 2, an in-chamber pressure measuring device 25 for measuring the pressure in the chamber 20 is arranged.
In the present embodiment, the pressure adjusting means 44 adjusts the internal pressure of the liquefied gas holder 42 so that the liquefied gas is introduced into the chamber 20 via the liquefied gas introduction pipe 41.

Next, a method for manufacturing a thin-walled slab using the thin-walled slab manufacturing apparatus 10 according to the present embodiment will be described.

First, a dummy sheet (not shown) is inserted between the pair of cooling drums 11 and 11. At this time, the vaporizer 30 is retracted to a position separated from the molten steel pool portion 16 by the height adjusting means 35. In this state, the molten steel 3 is injected from the tundish 18 toward the molten steel pool portion 16 via the immersion nozzle 19.
When the molten metal surface of the molten steel 3 in the molten steel pool portion 16 reaches a predetermined position, the cooling drums 11 and 11 are rotated. Further, the height adjusting means 35 arranges the vaporizer 30 above the molten steel pool portion 16.
Then, the liquefied gas is introduced into the chamber 20 by the liquefied gas introducing unit 40, and the vaporizer 30 is impregnated with the liquefied gas to be vaporized. Although it depends on the volume of the chamber 20 and the casting conditions, the amount of the liquefied gas introduced is preferably in the range of about 100 cc / min or more and 1000 cc / min or less.

In the present embodiment, it is preferable to introduce the liquefied gas into the chamber 20 so that the difference P1-P0 between the pressure P1 and the atmospheric pressure P0 in the chamber 20 is within the range of 10 Pa or more and 500 Pa or less.
By setting the difference P1-P0 between the pressure P1 and the atmospheric pressure P0 in the chamber 20 to 10 Pa or more, it is possible to accurately suppress the invasion of outside air into the chamber 20. On the other hand, by setting the difference P1-P0 between the pressure P1 and the atmospheric pressure P0 in the chamber 20 to 500 Pa or less, the seal gas is unevenly ejected from a part of the seal portion to suck the outside air into the chamber. It becomes possible to suppress it.
The lower limit of the difference P1-P0 between the pressure P1 and the atmospheric pressure P0 in the chamber 20 is preferably 30 Pa or more, and more preferably 50 Pa or more. Further, the upper limit of the difference P1-P0 between the pressure P1 and the atmospheric pressure P0 in the chamber 20 is preferably 300 Pa or less, and more preferably 250 Pa or less.

Here, since the height of the molten metal in the molten steel pool portion 16 fluctuates during casting, in the present embodiment, the height adjusting means 35 is used according to the height of the molten metal in the molten steel pool portion 16. It is preferable to adjust the height position of the vaporizer 30 to maintain the height position of the molten steel pool portion 16 of the vaporizer 30 from the molten metal surface within a certain range.

Specifically, it is preferable to arrange the vaporizer 30 so that the height of the molten steel pool portion 16 from the molten metal surface is within the range of 5 mm or more and 60 mm or less.
By setting the height of the molten steel pool portion 16 of the vaporizer 30 from the molten metal surface to 5 mm or more, it is possible to accurately suppress the molten steel 3 from being cooled by the heat of vaporization to generate solidified foreign matter. On the other hand, by setting the height of the molten steel pool portion 16 of the vaporizer 30 from the molten metal surface to 60 mm or less, the molten steel surface of the molten steel 3 can be accurately covered with the inert gas by the vaporized inert gas.
The lower limit of the height of the molten steel pool portion 16 of the vaporizer 30 from the molten metal surface is preferably 10 mm or more, and more preferably 15 mm or more. Further, the upper limit of the height of the molten steel pool portion 16 of the vaporizer 30 from the molten metal surface is preferably 50 mm or less, and more preferably 40 mm or less.

According to the thin-walled slab manufacturing apparatus 10 of the present embodiment having the above configuration, the liquefied gas introduced by the liquefied gas introducing portion 40 is impregnated above the molten steel pool portion 16 in the chamber 20. Since the vaporizer 30 for vaporizing is disposed, the liquefied gas introduced into the chamber 20 is vaporized in a state of being impregnated in the vaporizer 30, so that the liquefied gas can be uniformly vaporized. Therefore, by covering the molten metal surface of the molten steel 3 with an inert gas, the molten steel 3 can be shielded from the outside air, and stable casting can be performed. Further, by suppressing the local vaporization of the liquefied gas, it is possible to suppress the generation of solidified foreign matter due to the temperature drop of the molten steel 3 due to the heat of vaporization, and it is possible to cast a high-quality thin-walled slab 1.

Further, in a preferred embodiment of the present embodiment, since the height adjusting means 35 for adjusting the height position of the vaporizer 30 is provided in the chamber 20, when the height of the molten metal pool portion 16 fluctuates. Even if there is, the height position of the molten steel pool portion 16 of the vaporizer 30 from the molten metal surface can be kept constant, the liquefied gas is stably vaporized, and the molten metal surface of the molten steel 3 is covered with the inert gas. Is possible.
Further, at the start of casting, the vaporizer 30 can be retracted, and it is possible to prevent splashes and the like when pouring the molten steel 3 from adhering to the vaporizer 30.

Further, in a preferred embodiment of the present embodiment, the height adjusting means 35 is configured to adjust the height position of the vaporizer 30 by moving the vaporizer 30 along the peripheral surface of the cooling drum 11. Therefore, even if the height of the molten metal surface of the molten steel pool portion 16 fluctuates, the vaporizer 30 can be arranged in the vicinity of the cooling drum 11 of the molten steel pool portion 16 to stably vaporize the liquefied gas. It becomes possible to cover the molten metal surface of the molten steel 3 with an inert gas.

Further, in a preferred embodiment of the present embodiment, the liquefied gas introduction unit 40 includes a liquefied gas holder 42 and a liquefied gas introduction pipe 41 for introducing the liquefied gas into the chamber 20 from the liquefied gas holder 42. Liquefied gas can be stably introduced into 20. Further, even when the liquefied gas is vaporized in the liquefied gas introduction pipe 41, the backflowing gas can be received by the liquefied gas holder 42, and damage to the equipment on the upstream side of the liquefied gas holder 42 can be suppressed.

Further, in the preferred embodiment of the present embodiment, since the vaporizer 30 extends along the axis of the cooling drum 11, the molten steel formed by the pair of cooling drums 11 and 11 and the pair of side dams 15 and 15 The liquefied gas can be vaporized on the pool portion 16, and the entire surface of the molten steel pool portion 16 can be covered with the inert gas. As a result, the entire surface of the molten steel 3 can be accurately shielded from the outside air, and casting can be performed more stably.

Further, according to the method for producing a thin-walled slab according to the present embodiment, the liquefied gas obtained by liquefying the inert gas is introduced into the vaporizer 30 arranged above the molten steel pool portion 16 in the chamber 20, and the chamber 20 is used. Since the inside is an inert gas atmosphere, the liquefied gas can be uniformly vaporized by vaporizing the liquefied gas in a state of being impregnated in the vaporizer 30, and the molten metal surface of the molten steel 3 is covered with the inert gas. It is possible to perform stable casting by shutting off from the outside air.

Further, in a preferred embodiment of the present embodiment, the height position of the vaporizer 30 is adjusted according to the height of the molten steel pool portion 16 and the height position of the molten steel pool portion 16 of the vaporizer 30 from the molten metal surface. Since it is configured to be maintained within a certain range, even if the height of the molten steel pool portion 16 fluctuates, the liquefied gas is stably vaporized and the molten metal surface of the molten steel 3 is covered with the inert gas. Can be done.

In a more preferable embodiment of the present embodiment, the molten steel pool portion 16 is arranged so that the height from the molten metal surface is within the range of 5 mm or more and 60 mm or less, so that the molten steel 3 is cooled by the heat of vaporization and solidified foreign matter is generated. The formation can be accurately suppressed, and the molten metal surface of the molten steel 3 can be accurately covered with the inert gas by the vaporized inert gas.

Further, in a preferred embodiment of the present embodiment, the liquefied gas is introduced into the chamber 20 so that the difference P1-P0 between the pressure P1 and the atmospheric pressure P0 in the chamber 20 is within the range of 10 Pa or more and 500 Pa or less. Therefore, it is possible to accurately suppress the intrusion of outside air through the gap of the chamber 20, and it is possible to perform casting more stably.

Although the apparatus for producing thin-walled slabs and the method for producing thin-walled slabs according to the embodiment of the present invention have been specifically described above, the present invention is not limited thereto, and the technical idea of the invention is not limited thereto. It can be changed as appropriate within the range that does not deviate from.
For example, in the present embodiment, as shown in FIG. 1, a thin-walled slab manufacturing apparatus in which pinch rolls are arranged has been described as an example, but the arrangement of these rolls and the like is not limited, and the design is appropriately changed. You may.

Further, in the present embodiment, the liquefied gas introduction unit has been described as having a liquefied gas holder, but the present invention is not limited to this, and the liquefied gas holder may not be provided.
Further, in the present embodiment, a height adjusting means for adjusting the height of the vaporizer is provided, and the height adjusting means is described as a configuration for adjusting the height position of the vaporizer along the peripheral surface of the cooling drum. However, the present invention is not limited to this, the configuration of the height adjusting means is not limited, and the height adjusting means may not be provided.

Further, in the present embodiment, the vaporizer is supported by the liquefied gas introduction pipe in the chamber, but the present invention is not limited to this, and the vaporizer may be supported by another support structure.
Further, in the present embodiment, the vaporizer has been described as having a structure in which a porous sheet material is attached to a frame body, but the present invention is not limited to this, as long as it is impregnated with liquefied gas and vaporized. good.

The results of experiments carried out in order to confirm the effects of the present invention will be described below. Using the thin-walled slab manufacturing apparatus described in the embodiment, a thin-walled slab made of SUS304 steel was cast under the following conditions.
The casting conditions common to the examples of the present invention, Comparative Example 1 and Comparative Example 2 are shown below.

(Casting conditions)
Cooling drum width: 1000mm
Cooling drum diameter: 600 mm
Casting speed: 50 m / min on average
Casting thickness: 3.0 mm
Molten steel temperature in the molten steel pool: 1510 ° C
Casting amount: 45 tons Casting time: 30 minutes

<Example of the present invention>
In the example of the present invention, an alumina ceramic wool filter (20 mm × 900 mm × 15 mm thickness) was used as the sheet material of the porous body constituting the vaporizer. Further, the height of the molten steel pool portion of the vaporizer from the molten metal surface was set to 20 mm.
Argon gas was used as the liquefied gas. A liquefied gas was introduced into the chamber so that the pressure P1 in the chamber was +100 Pa with respect to the atmospheric pressure P0. The introduction amount was 365 cm ³ / min.

In the example of the present invention, no deckle (solidified metal) was generated on the molten metal surface of the molten steel pool portion over the entire casting time, no cracking on the surface of the slab due to its entrainment occurred, and stable casting was possible.
In addition, scum made of Mn-Si oxide was generated on the molten steel surface of the molten steel pool so as to cling to the circumference of the immersion nozzle within a few centimeters, but it was not caught in the slab and was thin-walled with a sound surface texture. I got a piece.

<Comparative Example 1>
In Comparative Example 1, the liquefied gas was directly dropped near the molten metal surface of the molten steel pool portion in the chamber without using a vaporizer.
Argon gas was used as the liquefied gas. A liquefied gas was introduced into the chamber so that the pressure P1 in the chamber was +100 Pa with respect to the atmospheric pressure P0. The introduction amount was 365 cm ³ / min.

In Comparative Example 1, immediately after the start of casting, a deckle (solidified metal) having a size of 2 to 3 cm was generated in the dropping portion of the liquefied gas, and this deckle was caught from the contact portion between the molten steel pool portion and the cooling drum. Surface cracks occurred on the thin-walled slab. In addition, 15 minutes after the start of casting, the deckle stagnated and grew near the meeting point between the side weir, the end face of the cooling drum, and the molten steel pool portion, and was caught in the deckle to stop the casting.

<Comparative Example 2>
In Comparative Example 2, the inert gas was introduced into the chamber in a gaseous state without using a vaporizer.
Argon gas was used as the inert gas. An inert gas in a gaseous state was introduced into the chamber so that the pressure P1 in the chamber was +980 Pa with respect to the atmospheric pressure P0. The introduction amount was 1000 Nl / min.

In Comparative Example 2, after the start of casting, scum made of Mn—Si oxide was generated in a film shape on the molten steel surface of the molten steel pool portion and stayed on the molten metal surface of the molten steel pool portion for 2 to 3 min. Every time, it was intermittently caught in the thin-walled slab, and the surface of the slab in which the scum was caught had streaky gloss unevenness of several mm in width, and cracks occurred at the boundary between the glossy uneven portion and the normal portion.

From the above, according to the example of the present invention, the liquefied gas obtained by liquefying the inert gas can be uniformly vaporized on the molten metal surface, and the outside air is covered by covering the molten metal surface with the inert gas. It was confirmed that it is possible to provide a thin-walled slab manufacturing apparatus capable of stably casting and a thin-walled slab manufacturing method.

1 Thin-walled slab 3 Molten steel (molten metal)
5 Solidification shell 11 Cooling drum 15 Side weir 16 Molten steel pool part (molten metal pool part)
20 Chamber 30 Vaporizer 35 Height adjusting means 40 Liquefied gas introduction unit 41 Liquefied gas introduction pipe 42 Liquefied gas holder

Claims (7)

A thin-walled cast that supplies molten metal to a molten metal pool formed by a pair of rotating cooling drums and a pair of side dams, and forms and grows a solidified shell on the peripheral surface of the cooling drum to produce thin-walled slabs. It ’s a piece of manufacturing equipment,
A chamber is arranged above the molten metal pool portion and the cooling drum.
A liquefied gas introduction section for introducing a liquefied gas obtained by liquefying an inert gas is provided in this chamber.
A thin-walled slab manufacturing apparatus characterized in that a vaporizer that impregnates and vaporizes the liquefied gas introduced by the liquefied gas introducing portion is disposed above the molten metal pool portion in the chamber. .. The thin-walled slab manufacturing apparatus according to claim 1, wherein a height adjusting means for adjusting the height position of the vaporizer is provided in the chamber. The thin-walled slab manufacturing apparatus according to claim 2, wherein the height adjusting means adjusts the height position of the vaporizer along the peripheral surface of the cooling drum. One of claims 1 to 3, wherein the liquefied gas introduction unit includes a liquefied gas holder and a liquefied gas introduction pipe for introducing liquefied gas into the chamber from the liquefied gas holder. The equipment for manufacturing thin-walled slabs according to the section. A thin-walled cast that supplies molten metal to a molten metal pool formed by a pair of rotating cooling drums and a pair of side dams, and forms and grows a solidified shell on the peripheral surface of the cooling drum to produce thin-walled slabs. It ’s a piece manufacturing method.
A chamber is arranged above the molten metal pool portion and the cooling drum, and a vaporizer that impregnates and vaporizes a liquefied gas obtained by liquefying an inert gas above the molten metal pool portion in the chamber. Is arranged,
A method for producing a thin-walled slab, which comprises introducing the liquefied gas into the vaporizer and covering the molten metal surface of the molten metal pool portion with the inert gas. The claim is characterized in that the height position of the vaporizer is adjusted according to the height of the molten metal pool portion, and the height position of the vaporizer from the molten metal surface is maintained within a certain range. 5. The method for producing a thin-walled slab according to 5. 5. The liquefied gas is introduced into the chamber so that the difference P1-P0 between the pressure P1 and the atmospheric pressure P0 in the chamber is within the range of 10 Pa or more and 500 Pa or less. 6. The method for producing a thin-walled slab according to 6.

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