WO2017187665A1

WO2017187665A1 - Continuous casting device for steel

Info

Publication number: WO2017187665A1
Application number: PCT/JP2017/000014
Authority: WO
Inventors: 守彦久保田
Original assignee: Ｍｋテクノコンサルティング株式会社
Priority date: 2016-04-28
Filing date: 2017-01-04
Publication date: 2017-11-02
Also published as: AT526023A1; JPWO2017187665A1; JP6570738B2; AT526023B1

Abstract

Provided is a continuous casting device for steel, said device being capable of: effectively using existing molds; preventing the rise of cooling water by means of a spray guard; effectively preventing high-temperature vapor from entering an air gap and thereby preventing corrosion and abrasion from occurring on the lower-end inner peripheral surface of the mold via the addition of a high-pressure gas discharge unit; and accommodating mold width-changing operations. The continuous casting device for steel also has excellent versatility, a long operating life, and excellent resource-saving characteristics, maintainability, and easy of assembly and disassembly. The continuous casting device is provided with: a mold having a pair of short edges and a pair of long edges; and a plurality of spray nozzles which are provided to the lower outer area of the mold and from which water is shot towards semi-finished casting products that are continuously pulled out from the mold while being supported by support rollers. The present invention is provided with a high-pressure gas discharge unit which injects high-pressure gas toward the short and long edges on the inner periphery side of the mold from a discharge port provided on the lower-end periphery of the mold.

Description

Steel continuous casting equipment

The present invention relates to a continuous casting apparatus for steel that can prevent corrosion and wear from occurring on the inner peripheral surface of the lower end side of a mold by cooling water and water mist (spray water) used for cooling a cast piece continuously cast. .

In continuous casting of steel, the biggest factor that determines the mold life (chs / campaign) is the corrosion that occurs on the inner surface of the lower part of the mold (in reality, it is also referred to as corrosion / wear because it also affects wear) It is.
2. Description of the Related Art Conventionally, in a continuous casting apparatus that performs continuous casting of steel, molten steel is poured from above a mold, and a cast piece coming out of the mold is continuously drawn while being supported by a support roller or the like. At this time, a solidified layer called a solidified shell is formed in the mold, but the inside is in an unsolidified state. Therefore, the slab is cooled by spraying cooling water or water mist (water or water mixed with air, spray water) from a plurality of spray nozzles disposed on the lower outer side of the mold.
Because the inner surface of the mold is exposed to high temperatures and damaged by friction with molten steel, a surface treatment layer is formed on the inner surface of the mold by a thermal spray coating such as Co-Ni plating or cermet, etc. to extend the service life. In addition, when the inner surface of the mold is damaged, it is repaired by cutting, grinding, and surface treatment, and is generally used repeatedly 3 to 10 times (3 to 10 campaign).
However, the spray water contains a component that corrodes metals such as sulfuric acid and hydrochloric acid, and fluorine in the mold powder used for casting reacts with cooling water or high-temperature steam to react with hydrogen fluoride or the like. Since a strong corrosive liquid and a high-temperature gas are generated, it causes a reduction in the life of the surface treatment layer on the inner surface of the mold. That is, the cooling water and its high-temperature steam enter the air gap generated between the solidified shell of the slab and the inner surface of the mold, causing corrosion and wear of the surface treatment layer of the mold.

In order to solve this problem, in recent years, the following methods have been performed as countermeasures against mold corrosion and wear in a continuous casting apparatus for steel.
First, if the generation of an air gap at the lower part of the mold can be prevented, the corrosion can be prevented. In order to suppress the generation of the air gap, it is necessary to support the shrinkage of the shell accompanying solidification with an appropriate taper of the mold.
A typical example that suppresses the occurrence of this air gap is high-speed casting. Among them, thin slab casting using a funnel mold (drawing speed Vc: 4 to 6.5 m / min, fluorine content in mold powder: 20%) can be seen from the viewpoint of suppressing the occurrence of an air gap. This is a very good slab casting method.
This casting method can prevent fine cracks on the surface of the slab generated in the mold and prevent internal corrosion at the bottom of the mold in a steel type sensitive to cracking. This has been proven in practice.
However, in the majority of parallel plate mold operations, even with high-speed casting, it is not possible to sufficiently suppress the occurrence of air gaps at the corners of the short and long sides of the mold. Compared with, there are few air gaps and very little corrosion in high speed casting.)
Secondly, even if there are some air gaps, if there is no hot water (or high-temperature steam accompanying spraying of spray water), the corrosion phenomenon does not occur or is greatly suppressed. This is the principle of the corrosion phenomenon.
The corrosion generated on the inner surface of the lower part of the mold is a phenomenon that occurs when this hot water (or high-temperature steam) enters the air gap generated at the lower part of the mold. (This hot water or high-temperature steam reacts with fluorine contained in the mold powder to form highly corrosive hydrofluoric acid, and also creates a very strong corrosive environment together with sulfuric acid and hydrochloric acid accumulated in spray water.)
In order to solve these problems, for example, (Patent Document 1) discloses a continuous casting mold in which a cooling water shield is provided on at least a lower end surface on the long side of a mold base.
In addition, (Patent Document 2) discloses a continuous casting mold in which a gas ejection portion is provided in the corner portion of the inner lower portion of the mold main body forming the mold space or in the vicinity thereof.

JP 2005-103619 A JP 2003-326338 A

However, the above conventional technique has the following problems.
(1) The continuous casting mold of (Patent Document 1) is premised on slab casting, and is provided with a spray guard between the lower end surface of the mold base and the uppermost support roller. Since cooling water is applied mainly to the long side of the lower end surface, a spray guard must be provided on the lower end surface of the long side of the base, and the cooling water is scattered on the short side. A spray guard is preliminarily provided on the end face. That is, the spray guard of (patent document 1) guides the cooling water sprayed from the nozzle and prevents the cooling water from directly entering the inner surface of the mold base.
However, in actuality, in the high speed casting area where the drawing speed of the slab is 2 m / min or more, the air gap generated between the surface of the slab and the inner surface of the mold is particularly that of the long side slab. The solidified shell is pressed against the inner surface of the mold by the static pressure of the molten steel and hardly occurs.
As an example of high-speed slab casting, there are data on operations in Japan and the United States of 2 to 2.3 m / min and 3.5 m / min. In both cases, the life of the surface treatment film on the long side of the mold per surface treatment exceeds 2000 charges of (Patent Document 1) and achieves 2000 to 3000 charges without any special measures against corrosion and wear. This partly has the effect of reducing wear due to the decrease in hardness of the solidified shell in high-speed casting, but the decrease in strength of the solidified shell on the long side increases the bulging effect due to the static pressure of the molten steel, so that almost no air gap is generated. This is considered to indicate that corrosion and wear are greatly reduced. The above (Patent Document 1) is exactly carried out under such casting conditions.
However, it has been found that even under this casting condition, an air gap is generated on the short side and the corner. The majority of continuous casting machines are medium and low speed casting operations, and an air gap is likely to occur between the surface of the slab and the inner surface of the mold.
Therefore, it is important to take measures against corrosion and wear on the short side and corner of the high speed casting area where air gaps are likely to occur, and on the long side and short side of the medium and low speed casting areas. Therefore, it is impossible to prevent the high-temperature steam from entering the air gap only by providing a protruding spray guard on the lower end surface of the mold, and there is a problem that a sufficient effect cannot be obtained. Was.
(2) (Patent Document 2) is based on the premise of bloom casting, and gas is formed at or near the inner corner portion of the mold body through which the corner portion of the slab passes at the lower portion inside the mold body forming the mold space. By providing a jet part and filling gas between the mold space and the slab, intrusion of steam and water into the mold space is prevented, and at the inner lower part of the mold main body, at the inner corner and in the vicinity thereof. It is intended to prevent the corrosion and wear of the mold body and extend the service life.
However, since there is a gas ejection part inside the mold, there is a problem that high-temperature mold powder is deposited on the gas ejection part, and clogging is likely to occur, and it has not been put into practical use.
(3) Further, in the conventional continuous casting apparatus, in order to quickly cool the slab drawn continuously from the lower end side of the mold, the spray nozzle of the uppermost stage has the cooling water injection direction slightly upward from the horizontal. Is set. However, due to this, the cooling water sprayed from the spray nozzle and its high temperature steam easily enter the air gap formed between the surface of the slab and the inner surface of the mold, which is a major cause of corrosion and wear. It has become.
(4) This application was invented on the basis of various on-site experiments as a countermeasure against mold corrosion and wear in a continuous casting apparatus for steel.

The present invention solves the above-mentioned problems, and by using an existing mold effectively, the spray guard prevents the high-pressure steam from rising, and a high-pressure gas injection part is added to prevent the high-temperature steam from entering the air gap. It can effectively prevent corrosion and wear that occurs on the inner peripheral surface of the lower end side of the mold, and can cope with mold width changing operation, and is excellent in versatility, long life, and resource saving. An object of the present invention is to provide a continuous casting apparatus for steel that is excellent in workability, maintainability, disassembly and assembly workability.

In order to solve the above conventional problems, the steel continuous casting apparatus of the present invention has the following configuration.
According to a first aspect of the present invention, there is provided a continuous casting apparatus for steel, comprising a mold having a pair of short sides and long sides, and continuous while being supported on a lower outer side of the mold by a support roller. And a plurality of spray nozzles for injecting water onto the slab to be drawn, and a short side on the inner peripheral side of the mold from a jet port disposed at a lower end side peripheral edge of the mold And a high pressure gas jetting part for jetting high pressure gas toward the long side part.
With this configuration, the following effects can be obtained.
(1) A solidified shell of a slab since it includes a high-pressure gas jetting part that jets high-pressure gas from a jet nozzle disposed on the lower edge of the mold toward the short side and long side on the inner circumference of the mold. Cooling water / water injected from the spray nozzle to cool the slab by injecting high-pressure gas from the outlet of the high-pressure gas injection section against the air gap generated between the mold and the inner surface of the mold It is possible to effectively prevent mist and its high temperature steam from entering the air gap. As a result, high-temperature steam containing sulfuric acid, hydrochloric acid, etc. contained in the water enters the air gap on the inner peripheral side of the mold, and fluorine in the mold powder reacts with the cooling water in the mold, such as hydrogen fluoride. The generation of strong corrosive liquid and high temperature gas can be prevented, and the surface treatment layer of the mold can be prevented from being corroded and worn, and the mold has a long life.
(2) Since the high-pressure gas jetting portion having a plurality of jetting ports is simply configured to be disposed on the lower edge of the lower end of the mold, the existing mold can be used effectively, saving resources, disassembling and assembling. Excellent workability.
(3) Since the high-pressure gas ejection portion having a plurality of ejection ports can be formed as a separate member and disposed on the lower end side periphery of the mold, the high-pressure gas ejection portion is corroded by sulfuric acid, hydrofluoric acid, or the like. If this occurs, only the high-pressure gas ejection part can be easily removed from the mold for repair or replacement, and the mold can be used for a long period of time, saving resources, maintenance, and handling. Excellent in properties.

Here, the steel continuous casting apparatus manufactures slabs such as slabs, blooms, billets, and beam blanks depending on the type of mold.
The present invention is employed for slab, bloom and beam blank casting except high speed casting and billet casting which does not use mold powder.
The high-pressure gas ejection part ejects high-pressure gas from a plurality of ejection ports toward the short side and long side on the inner peripheral side of the mold, but the corners of the short side and long side where corrosion and wear are likely to occur. It is sufficient that the high-pressure gas can be ejected in a range of at least 250 mm from the portion. For example, a plate-like or block-like member having a flow path formed therein and a jet outlet communicating with the flow path are desirable, but as a simplified type, a jet outlet may be formed in a pipe-shaped flow path. .
Moreover, although the high-pressure gas ejection part is disposed on the lower end side periphery of the mold, the arrangement of the flow path, the number of divisions, and the like can be appropriately selected. Even when the flow path is divided into a plurality of parts, by supplying high pressure gas from a common high pressure gas supply source to the plurality of flow paths, it is possible to reliably supply the required amount of high pressure gas at a predetermined pressure simultaneously from each jet outlet. It can be ejected and has excellent stability and reliability.
The number and arrangement of the nozzles can be selected as appropriate according to the shape and size of the mold, but by arranging the nozzles at least at the corners of the mold, the surface of the slab and the mold High pressure gas is jetted around the corner where a particularly large air gap is likely to occur between the surface and high temperature steam can be prevented from entering the air gap, effectively preventing corrosion and wear. . The shape of the jet port may be circular or a horizontally long slit.
As the gas ejected from the high-pressure gas ejection section, air is advantageous in terms of cost, but nitrogen or other inert gas may be used.
The injection pressure and injection amount of the high-pressure gas need only be able to prevent high temperature steam from entering the air gap. However, the injection pressure of about 3 to 5 atmospheres used for air-water cooling (spray nozzle) is sufficient. it is conceivable that.
Further, the high-pressure gas ejection part can also have a spray guard function for preventing cooling water ejected from the spray nozzle from entering the air gap between the surface of the slab and the inner surface of the mold. In that case, the material of the high-pressure gas ejection part is preferably a stainless steel, and SUS316 is particularly desirable from the viewpoint of corrosion resistance against hydrofluoric acid.

Invention of Claim 2 is the continuous casting apparatus of steel of Claim 1, Comprising: The said casting_mold | template has a copper plate part and the backplate arrange | positioned on the outer side of each said copper plate part. The high-pressure gas ejection part is fixed to the lower end surface of the back plate of the mold.
With this configuration, in addition to the operation obtained in the first aspect, the following operation can be obtained.
(1) The mold has a copper plate portion and a back plate disposed outside each copper plate portion, and the high-pressure gas ejection portion is fixed to the lower end surface of the back plate of the mold, thereby The high-pressure gas jet part can be installed at this part where the pressure is limited, the attachment / detachment work is easy, and the workability and maintenance of assembly and disassembly are excellent.

Here, the fixing method of the high-pressure gas ejection part can be selected as appropriate, but by fixing with bolts, it is excellent in fixing reliability and can be easily attached and detached as necessary. Excellent handleability.
As a special example, when the molded copper plate is very thick, the high-pressure gas ejection portion may be fixed to the lower end surface on the non-consumable side of the copper plate.

Invention of Claim 3 is the continuous casting apparatus of steel of Claim 2, Comprising: The said high pressure gas ejection part is the said back plate of the said short side part of each said mold, and the said long side part. It has the structure divided | segmented and arrange | positioned at the lower end surface.
With this configuration, in addition to the operation obtained in the second aspect, the following operation can be obtained.
(1) The high-pressure gas ejection portion is divided and disposed on each of the short side portion of the mold and the lower end surface of the back plate of the long side portion. High-pressure gas can be ejected from the slab, and it is possible to handle slab width changing operations, and it is possible to reliably protect the required part of the inner surface on the lower end side of the mold from cooling water and its high-temperature steam. It is excellent in preventing corrosion and abrasion of the surface treatment layer.

Here, the high-pressure gas ejection portion can be reliably ejected to each side of the mold by being disposed on the lower end surface of each back plate disposed outside the copper plate portion of the mold. it can. The number and arrangement (interval) of the ejection ports formed in each of the divided high-pressure gas ejection portions can be appropriately selected according to the length of each side of the mold.

Invention of Claim 4 is the continuous casting apparatus of steel of Claim 2, Comprising: The said high-pressure-gas ejection part is divided | segmented into the lower end surface of the said backplate of a pair of said short side part of the said casting_mold | template. It has the structure arranged.
With this configuration, in addition to the operation obtained in the second aspect, the following operation can be obtained.
(1) The high-pressure gas ejection part is divided and disposed on the lower end surface of the back plate of the pair of short sides of the mold, thereby making the short side of the mold movable and producing slabs having different widths. Even when the high-pressure gas ejection part is moved together with the back plate of the short side part, the high-pressure gas can be reliably ejected from the corner part on the inner peripheral side of the mold toward the short side part and the long side part. Excellent reliability and corrosion / wear prevention.

Here, in the case of high-speed casting slab casting, the high-pressure gas ejection part has a substantially U-shaped flow path, and a jet port is formed at each corner part of the flow path and directly above the uppermost spray nozzle. Those are preferably used. Even when the short side of the mold is moved by slab casting, the corner of the flow path becomes the position of the corner on the inner peripheral side of the mold, and corrosion and wear occur on the inner surface of the mold with a simple structure. Can be effectively prevented.

A fifth aspect of the present invention is the continuous casting apparatus for steel according to any one of the first to fourth aspects, wherein the jet port of the high-pressure gas jet part is added to a corner part of the mold. And a structure arranged immediately above each of the spray nozzles arranged on the lower outer side of the mold.
With this configuration, in addition to the action obtained in any one of claims 1 to 4, the following action is obtained.
(1) Cooling sprayed from each spray nozzle by disposing the jet outlet of the high-pressure gas ejection section directly above each spray nozzle disposed on the lower outer side of the mold in addition to the corner portion of the mold. Effectively prevent water / water mist and its high temperature steam from entering the air gap between the surface of the slab and the inner surface of the mold, and protect the inner surface of the mold from corrosion and wear. And has a long mold life.

Here, the air gap tends to occur between the inner peripheral surface of the lower end side of the mold and the surface of the slab, particularly at the corner portion, and there is a tendency for corrosion and wear to increase. It is easily affected by the cooling water sprayed from the nozzle and its high-temperature steam, and corrosion and wear are observed. Therefore, in addition to the corners of the mold, the high-pressure gas is ejected by disposing a high-pressure gas ejection part directly above each spray nozzle, so that the cooling water and its high-temperature steam ejected from the spray nozzle are injected into the mold. Intrusion into the interior can be reliably prevented, the occurrence of corrosion and wear can be prevented over the entire circumference of the inner peripheral surface of the lower end side of the mold, and the long life of the mold can be improved.

Invention of Claim 6 is a continuous casting apparatus of steel of any one of Claim 1 thru | or 5, Comprising: The said high pressure gas ejection part is formed with a plate-shaped member, The said plate-shaped member A flow path formed in parallel to the longitudinal direction, the spout formed in the end surface of the plate-shaped member and communicating with the flow path, and the uppermost spray formed on the lower surface of the plate-shaped member And a spray guard having an inclined surface for guiding cooling water sprayed from the nozzle downward from the horizontal direction.
With this configuration, in addition to the action obtained in any one of claims 1 to 3, the following action is obtained.
(1) The high-pressure gas ejection portion is formed of a plate-like member, and has a channel formed in the plate-like member in parallel with the longitudinal direction, and a jet port that is drilled in the end surface of the plate-like member and communicates with the channel. And a spray guard formed on the lower surface of the plate-like member and having an inclined surface that guides cooling water and water mist ejected from the uppermost spray nozzle downward from the horizontal direction, and is ejected from the spray nozzle. The spray guard can effectively prevent cooling water from entering the air gap between the surface of the slab and the inner surface of the mold, greatly reducing the corrosion and wear generated on the inner surface of the mold. it can.
(2) Since the spray guard is formed on the lower surface of the plate-like member constituting the high-pressure gas ejection portion, the limited space between the lower end of the mold and the uppermost support roller is effectively utilized, and spraying is performed. A high-pressure gas ejection part with a guard function can be easily installed, and it excels in space saving and reliability of corrosion and wear reduction.
(3) Since the spray guard is formed integrally with the high-pressure gas ejection part, the number of parts can be reduced, and the workability of disassembly and assembly can be improved.

Here, the spray guard only needs to be able to guide the cooling water sprayed from the spray nozzle downward from the horizontal direction. However, the spray guard has an inclined surface inclined downward from the outer peripheral side to the inner peripheral side of the copper plate portion of the mold. What has is used suitably.
The inclination angle of the inclined surface of the spray guard is preferably 10 degrees or more with respect to the horizontal plane. As the inclination angle of the inclined surface of the spray guard becomes smaller, it becomes difficult for the cooling water sprayed from the spray nozzle to be guided downward from the horizontal direction, and a part of the cooling water sprayed from the spray nozzle and diffused becomes the surface of the slab. It tends to enter the air gap between the mold and the inner surface of the mold, and the effect of reducing corrosion and wear tends to decrease, which is not preferable. However, the height of the high-pressure gas ejection part is limited by the space of the installation position. If the inclination angle of the inclined surface of the spray guard is too large, the cooling water tends to be hindered by the spray guard, and it is pulled out from the outlet of the mold. There is a tendency that sufficient cooling water injection is hindered against the cast slab, and the cooling effect by the spray nozzle tends to be lowered. Therefore, the position and angle (cooling water injection direction) of the uppermost spray nozzle is selected according to the installation space of the high-pressure gas injection section, and the upper limit of the inclination angle of the inclined surface is within a range that does not impede the cooling water injection. Need to be set.

In particular, the center line (injection direction) of the cooling water sprayed from the uppermost spray nozzle passes through the central part of the gap between the inclined surface of the spray guard of the high-pressure gas ejection part and the upper surface of the uppermost support roller. It is preferable that the uppermost spray nozzle is inclined. As a result, the slab can be reliably cooled by the cooling water sprayed from the spray nozzle without being obstructed by the spray guard and the support roller, and the cooling water / water mist and its high-temperature steam can be cooled on the surface of the slab and the mold. It is possible to reliably prevent the air gap between the inner surface and the inner surface of the steel from entering and to significantly reduce the occurrence of corrosion and wear.
By disposing a plate-like member having a jet port formed in the end surface from the back plate side to the inner peripheral surface side of the mold, the high-pressure gas can be jetted from the jet port toward the inner peripheral surface of the mold. Moreover, the compactness and productivity of a high-pressure gas ejection part are excellent by forming the flow path connected to each ejection port inside the plate-like member.

According to the continuous casting apparatus for steel of the present invention, the following advantageous effects can be obtained.
The air gap generated between the solidified shell of the slab and the inner surface of the mold is injected from the spray nozzle to cool the slab by injecting high-pressure gas from the outlet of the high-pressure gas injection part. This effectively prevents the cooling water / water mist and its high-temperature steam from entering the air gap, and high-temperature steam containing sulfuric acid, hydrochloric acid, etc. contained in the cooling water enters the mold and fluorine in the mold powder. The length of the mold that prevents corrosion and wear of the surface treatment layer of the mold by preventing the generation of strong corrosive liquids and gases such as hydrogen fluoride by reacting with cooling water, water mist and high-temperature steam It is possible to provide a continuous casting apparatus for steel having excellent life.
In addition, by adopting a structure that moves the hot gas ejection part together with the back plate of the short side part, even if the short side part of the mold is movable and slabs with different widths are manufactured, the corner on the inner peripheral side of the mold It is possible to provide a versatile steel continuous casting apparatus capable of reliably preventing corrosion and wear of the surface treatment layer by ejecting high-pressure gas from the portion toward the short side portion and the long side portion. .

Sectional schematic side view of the main part of the continuous casting apparatus for steel according to Embodiment 1 Schematic bottom view taken along line AA in FIG. Sectional enlarged schematic side view of the main part of the high-pressure gas ejection part in the continuous casting apparatus for steel according to Embodiment 1 Main part schematic top view which shows the high pressure gas ejection part of the continuous casting apparatus of steel of Embodiment 2 The principal part schematic plan view which shows the high pressure gas ejection part of the continuous casting apparatus of steel of Embodiment 3

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. The technical scope of the present invention is not limited to these embodiments.
(Embodiment 1)
1 is a schematic cross-sectional side view of a main part of the continuous casting apparatus for steel according to Embodiment 1, and FIG. 2 is a schematic bottom view taken along the line AA in FIG.
In FIG. 1, 1 is a continuous casting apparatus for steel according to the first embodiment, 2 is a mold of the continuous casting apparatus 1 for steel, 2a is an outlet on the lower end side of the

mold

2, and 5 is disposed on the lower outer side of the mold 2. A plurality of spray nozzles 6 for injecting cooling water or water mist onto the slab continuously drawn out from the outlet 2a of 2 and 6 are disposed below the mold 2 at a predetermined interval and support the slab discharged from the mold 2 It is a support roller.
1 and 2, reference numeral 3a denotes a copper plate portion disposed on the long side portion of the mold 2 in which the outlet 2a is formed in a rectangular shape, and 4a denotes a mold 2 disposed on and fixed to the outside of each copper plate portion 3a. The back plate 7a is a high-pressure gas jetting part disposed on the lower end surface of each back plate 4a at the long side of the

mold

2, and 8 is formed on the lower surface of the high-pressure gas jetting part 7a. It is a spray guard which guides the cooling water injected below from the horizontal direction.

In FIG. 2, 3 b is a copper plate portion disposed on the short side of the

mold

2, 4 b is a back plate of the mold 2 disposed and fixed outside each

copper plate portion

3 b, and 7 b is a short side portion of the mold 2. Of the continuous casting apparatus 1 disposed on the lower end surface of each

back plate

4b, 9a is a plurality of jets formed in each of the high-

pressure gas jets

7a and 7b, and 9d is each high-pressure gas. High-pressure gas supply pipes 10 disposed in the

ejection portions

7a and 7b are fixing bolts that detachably fix the main points of the high-pressure

gas ejection portions

7a and 7b to the

back plates

4a and 4b.

Next, the details of the high-pressure gas ejection portion in the steel continuous casting apparatus of Embodiment 1 will be described.
FIG. 3 is an enlarged schematic sectional side view of a main part of a high-pressure gas ejection part in the continuous casting apparatus for steel according to the first embodiment.
In FIG. 3, 5a is cooling water sprayed from the

spray nozzle

5, 8a is an inclined surface of the spray guard 8 inclined downward from the outer peripheral side to the inner peripheral side of the copper plate portion 3a of the

mold

2, and 9 is a high-pressure gas jet A plate-like member that constitutes the portion 7a (7b), 9b is a high-pressure gas ejection portion that is formed in a groove shape along the longitudinal direction inside the plate-like member 9 and communicates with the plurality of ejection ports 9a through the air passage 9b ′ 7a (7b), 9c is a cover part of the

channel

9b, and 9e is an air gap.
In the present embodiment, the uppermost spray nozzle 5 is installed to be inclined downward by 3 to 8 degrees, preferably about 5 degrees from the horizontal, and the center line (injection direction) of the injected cooling water 5a is the high-pressure gas ejection. It passes through the central part of the gap between the inclined surface 8a of the spray guard 8 of the part 7a (7b) and the upper surface of the uppermost support roller 6. Accordingly, the slab 20 can be reliably cooled by the cooling water 5a sprayed from the spray nozzle 5 without being obstructed by the spray guard 8 and the support roller 6, and the cooling water 5a and its high-temperature steam can be cooled. Intrusion into the air gap 9e between the surface of the mold 2 and the inner surface of the mold 2 can be reliably prevented.
In the present embodiment, the spout 9a is formed in a circular shape having a diameter of about 5 mm, but may be formed in a slit shape having a height of about 3 mm and a width of about 6 mm. The injection pressure and the injection amount of the high-pressure gas injected from the injection port 9a are within a range in which they can be prevented from entering the air gap 9e according to the injection amount of the cooling water 5a, the injection pressure, the generation amount of high-temperature steam, etc. Can be appropriately selected.

In FIG. 3, the inclination angle α of the inclined surface 8a of the spray guard 8 is 10 degrees with respect to the horizontal plane. As the inclination angle α of the inclined surface 8a of the spray guard 8 becomes smaller than 10 degrees, the cooling water 5a ejected from the spray nozzle 5 becomes difficult to be guided by the spray guard 8, and a part of the cooling water 5a is cast into the slab 20. This is because it has been found that the effect of reducing corrosion and wear tends to be reduced due to easy entry into the gap between the surface of the mold 2 and the inner surface of the mold 2. When the inclination angle α is too large, the cooling water 5a is easily blocked by the spray guard 8, and it becomes difficult to supply sufficient cooling water 5a to the slab 20 drawn from the outlet 2a of the mold 2. There exists a tendency for the cooling effect by the spray nozzle 5 to fall. Therefore, according to the installation space between the lower end surface of the mold 2 and the support roller 6, the position and angle of the uppermost spray nozzle 5 (injection direction of the cooling water 5a) are selected, and cooling with the cooling water 5a is performed. Although it is necessary to set the inclination angle α within a range not hindering, the upper limit of the inclination angle α is preferably about 30 to 40 degrees.
By forming the spray guard 8, the jet outlet 9 a and the flow passage 9 b integrally on the plate-like member 9, the coolant 5 a jetted from the spray nozzle 5 with the high pressure gas jetted from the spray guard 8 and the jet outlet 9 a. In addition, the high temperature steam can be effectively prevented from entering the air gap 9e between the surface of the slab 20 and the inner surface of the mold 2.

In the present embodiment, the high pressure gas ejection part 7a is divided into two parts with respect to the long side part of the mold 2, but the longitudinal dimension and the number of divisions of the high pressure gas ejection part 7a should be selected as appropriate. In accordance with the length of the long side portion of the mold 2, a necessary number of high-pressure gas ejection portions 7a can be installed.
Further, the number and arrangement interval of the ejection ports 9a of the high pressure gas ejection part 7a can be appropriately selected according to the lengths of the long side part and the short side part of the mold 2. In particular, for the long side portion of the mold 2, as shown in FIG. 2, the cooling water sprayed from each spray nozzle 5 is provided by arranging the jet outlet 9 a in accordance with the position of each spray nozzle 5. In addition, it is possible to reliably prevent the high temperature steam from entering the air gap between the surface of the slab 20 and the inner surface of the mold 2, and protect the inner surface of the mold 2 from corrosion and wear over the entire circumference.
In FIG. 2, a supply pipe 9d communicating with an internal flow path 9b (see FIG. 3) is formed in each of the high pressure

gas ejection portions

7a and 7b, and is connected to a high pressure gas supply source (not shown). High-pressure air or nitrogen or other inert gas supplied from the high-pressure gas supply source is distributed and ejected from the supply pipe 9d to the plurality of jet outlets 9a through the flow path 9b. The number and arrangement of the supply pipes 9d can be selected as appropriate. By supplying high pressure gas from a common high pressure gas supply source to the plurality of divided high pressure

gas ejection portions

7a and 7b, it is necessary at a predetermined pressure simultaneously from the respective outlets 9a of the high pressure

gas ejection portions

7a and 7b. An amount of high-pressure gas can be reliably ejected, and operation stability and reliability are excellent.

As described above, since the steel continuous casting apparatus according to Embodiment 1 of the present invention is configured, the following operation is obtained.
(1) A solidified shell of a slab since it includes a high-pressure gas jetting part that jets high-pressure gas from a jet nozzle disposed on the lower edge of the mold toward the short side and long side on the inner circumference of the mold. Cooling water / water injected from the spray nozzle to cool the slab by injecting high-pressure gas from the outlet of the high-pressure gas injection section against the air gap generated between the mold and the inner surface of the mold It is possible to effectively prevent mist and its high temperature steam from entering the air gap. As a result, high-temperature steam containing sulfuric acid, hydrochloric acid, etc. contained in the water enters the air gap on the inner peripheral side of the mold, and fluorine in the mold powder reacts with the cooling water in the mold, such as hydrogen fluoride. The generation of strong corrosive liquid and high temperature gas can be prevented, and the surface treatment layer of the mold can be prevented from being corroded and worn, and the mold has a long life.
(2) Since the high-pressure gas jetting portion having a plurality of jetting ports is simply configured to be disposed on the lower edge of the lower end of the mold, the existing mold can be used effectively, saving resources, disassembling and assembling. Excellent workability.
(3) Since the high pressure gas jetting portion having a plurality of jetting ports can be formed as a separate member and disposed on the lower end side periphery of the mold, if the high pressure gas jetting portion is damaged or malfunctioned, The high-pressure gas ejection part can be easily removed from the mold for repair or replacement, and the mold can be used for a long period of time, resulting in excellent resource saving, maintenance and handling.
(4) The mold has a copper plate portion and a back plate disposed outside each copper plate portion, and the high-pressure gas ejection portion is fixed to the lower end surface of the back plate of the mold, thereby providing a space. The high-pressure gas jet part can be installed at this part where the pressure is limited, the attachment / detachment work is easy, and the workability and maintenance of assembly and disassembly are excellent.
(5) The high-pressure gas ejection part is divided into the short side part of each mold and the lower end surface of the back plate of the long side part, so that each high-pressure gas ejection part with respect to each side of the mold. High-pressure gas can be ejected from the slab, and it is possible to handle slab width changing operations, and it is possible to reliably protect the required part of the inner surface on the lower end side of the mold from cooling water and its high-temperature steam. It is excellent in preventing corrosion and abrasion of the surface treatment layer.
(6) Cooling sprayed from each spray nozzle by disposing the jet outlet of the high-pressure gas ejection section directly above each spray nozzle disposed on the lower outer side of the mold in addition to the corner portion of the mold. Effectively prevent water / water mist and its high temperature steam from entering the air gap between the surface of the slab and the inner surface of the mold, and protect the inner surface of the mold from corrosion and wear. And has a long mold life.
(7) The high-pressure gas ejection portion is formed of a plate-like member and is formed in parallel with the longitudinal direction of the plate-like member, and a jet port that is formed in an end surface of the plate-like member and communicates with the flow passage. A cooling guard that is formed on the lower surface of the plate-like member and sprayed from the uppermost spray nozzle and a spray guard having an inclined surface that guides the water mist downward from the horizontal direction. However, the spray guard can effectively prevent the air gap between the surface of the slab and the inner surface of the mold from entering, and the corrosion and wear generated on the inner surface of the mold can be greatly reduced.
(8) By forming a spray guard on the lower surface of the plate-like member constituting the high-pressure gas ejection part, the limited space between the lower end of the mold and the uppermost support roller can be effectively used to spray A high-pressure gas ejection part with a guard function can be easily installed, and it excels in space saving and reliability of corrosion and wear reduction.
(9) Since the spray guard is formed integrally with the high-pressure gas ejection part, the number of parts can be reduced, and the workability of disassembly and assembly can be improved.

(Embodiment 2)
A steel continuous casting apparatus according to Embodiment 2 of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the thing similar to Embodiment 1, and description is abbreviate | omitted.
FIG. 4 is a schematic plan view of an essential part showing a high-pressure gas ejection portion of the continuous casting apparatus for steel according to the second embodiment.
In FIG. 4, the continuous casting apparatus 1A for steel in the second embodiment is for bloom casting. The difference from the first embodiment is that the high-pressure gas ejection portion 7c is divided into a long side portion and a short side portion of the mold 2. It is a point arranged. In FIG. 4, the fixing bolt 10 is omitted.
In FIG. 4, each supply pipe 9 d is connected to a high-pressure gas supply source (not shown), and air or nitrogen or other inert gas supplied from the high-pressure gas supply source passes through the flow path inside the plate-like member 9 from the supply pipe 9 d. It is distributed and ejected to a plurality of jet outlets 9a. It should be noted that the number and arrangement of the ejection ports 9a formed at portions other than the corners of the mold 2 can be appropriately selected according to the dimensions of the mold 2. Further, the number and arrangement of the supply pipes 9d can be appropriately selected. As described above, the high-pressure gas jetting portion 7c that is divided and arranged on each side of the mold 2 can also be applied to beam blank casting.
As described above, since the steel continuous casting apparatus according to the second embodiment of the present invention is configured, the same operations as (1) to (9) of the first embodiment can be obtained.

(Embodiment 3)
A steel continuous casting apparatus according to Embodiment 3 of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the thing similar to

Embodiment

1 or 2, and description is abbreviate | omitted.
FIG. 5 is a schematic plan view of an essential part showing a high-pressure gas ejection part of the continuous casting apparatus for steel according to the third embodiment.
In FIG. 5, the high-pressure gas ejection part 7d of the steel continuous casting apparatus 1B in the third embodiment is employed in the case of high-speed slab casting, and the difference from the second embodiment is the plate shape of the high-pressure gas ejection part 7d. The member 9 is formed in a substantially U-shape and is divided and disposed on the lower end surfaces of the pair of back plates 4b on the short side portion of the mold 2. In FIG. 5, the fixing bolt 10 is omitted.
The ejection ports 9a are formed at five locations on each plate-like member 9 in accordance with the position corresponding to the corner portion of the mold 2 and the position corresponding to the position immediately above the spray nozzle at the center of the short side portion. Thereby, the high pressure gas can be ejected from the short side portion and the long side corner portion on the inner peripheral side of the mold 2 to a range of at least 250 mm and a position directly above the spray nozzle of the short side portion.

As described above, since the steel continuous casting apparatus according to the third embodiment of the present invention is configured, the same operations as in the first embodiment (1) to (4) and (6) to (8) are performed. In addition, the following effects can be obtained.
(1) The high-pressure gas ejection part is divided and disposed on the lower end surface of the back plate of the pair of short sides of the mold, thereby making the short side of the mold movable and producing slabs having different widths. Even when the high-pressure gas ejection part is moved together with the back plate of the short side part, the high-pressure gas can be reliably ejected from the corner part on the inner peripheral side of the mold toward the short side part and the long side part. Excellent reliability and corrosion / wear prevention.

Hereinafter, the present invention will be specifically described by way of examples. The present invention is not limited to these examples.
(Comparative Example 1)
In a conventional continuous casting apparatus for steel (without a high-pressure gas ejection section and a spray guard), the cooling water spraying direction of the uppermost spray nozzle is set to the horizontal direction and normal operation is performed. (Initially, the spraying direction of the cooling water of the uppermost spray nozzle was 5-7 degrees upward, with an emphasis on cooling directly under the mold, aiming directly under the mold. (Because it sometimes blows up and it is not necessary to be particular about cooling right under the mold because of low speed casting, it was changed to the horizontal direction.)
As operating conditions at this time, the drawing speed is 0.9 to 1.2 m / min in the low speed casting region, the water pressure of the spray nozzle is 5 to 8 kg / cm ² , and the amount of water is 5 to 20 L / min / nozzle. During the operation, the mold was used while visually checking the condition of the mold.
The surface coating used Co—Ni plating, but was subsequently replaced with a thermal spray coating. In either case, the service life was limited to 800 to 900 charges (chs) due to corrosion and wear, and the mold life was reached.

Example 1
An experiment was conducted in the same manner as in Comparative Example 1 except that a spray guard without a high-pressure gas injection part was attached between the lower end of the mold of the conventional continuous casting apparatus for steel and the first-stage support roller (reference: FIG. 1). FIG. 2 and FIG. 3).
During the use, the experiment was continued while observing the details on-line and visually at the time of mold change.
The mold life was 1,000 to 1,300 charges in three tests. The conditions for determining the mold life were all the use limits due to corrosion and wear. In particular, what differs from the corrosion and wear of (Comparative Example 1) is the generation position and form. In (Comparative Example 1), the corrosion and wear that occurred on the short and long sides near the four corners determined the limits of use, but in this (Example 1), all were centered around the corner. Semi-circular corrosion and wear were remarkably observed just above the upper spray nozzle.

From the above, it was possible to prevent the spray water from directly entering the air gap of the mold by attaching the spray guard (correctly, it is understood that the influence of a large amount of water vapor generated by the spray water was alleviated. ). As a result, the level of corrosion and wear at the lower end of the mold was reduced, and the mold life was improved by about 50%.
However, the semicircular corrosion and wear phenomenon that occurs just above the top spray nozzle clearly shows that even if the spray guard alone can mitigate the intrusion of water vapor, it cannot be completely prevented. ing.
However, it is clear that by spraying high-pressure gas directly above the uppermost spray nozzle, water vapor is (?) Dispersed and diluted, and the spray nozzle outlet shape and injection amount should be optimized. Therefore, it is considered that the semicircular corrosion / wear is greatly reduced.
As a result, the expected life of the mold is expected to be 1,500 to 1,800 chs / campaign in the currently used film.
In addition, by reducing this corrosion, it becomes possible not only to extend the life of the conventional coating, but also to use many thermal spray coatings that are not applicable due to inferior corrosion resistance in particular, and that are resistant to mechanical impact and mechanical shock, It is expected to contribute to further life extension and cost reduction.

The present invention effectively utilizes the existing mold, prevents the high-pressure steam from rising by the spray guard, and prevents the high-temperature steam from entering the air gap by adding a high-pressure gas jetting portion, thereby lowering the lower end side of the mold. Corrosion and wear generated on the inner peripheral surface can be effectively prevented, and productivity can be improved. In addition, it can easily cope with changes in the width of the mold, has excellent versatility and long life, and if damage or malfunction occurs, repair or replace only the high-pressure gas ejection section and use the mold. It is possible to provide a continuous casting apparatus of steel that is excellent in resource saving, maintenance, handling, disassembly and assembly workability, and can extend the life of the mold.

1,1A, 1B Steel continuous casting device 2

Mold 2a Outlet

3a, 3b

Copper plate part

4a, 4b Back plate 5 Spray nozzle 6

Support roller

7a, 7b, 7c, 7d High pressure gas ejection part 8 Spray guard 8a Inclined surface 9 Plate shape Member 9a Spout 9b Flow path 9b 'Ventilation path 9c Cover part 9d Supply pipe 9e Air gap 10 Fixing bolt 20 Slab

Claims

A mold having a pair of short sides and a long side, and a plurality of spray nozzles that are disposed on the lower outside of the mold and spray water on the slab continuously drawn from the mold while being supported by a support roller. A continuous casting apparatus for steel,
A steel having a high-pressure gas jetting portion for jetting high-pressure gas from a jet port disposed at a lower end side periphery of the mold toward a short side portion and a long side portion on an inner circumference side of the mold. Continuous casting equipment.
The mold includes a copper plate portion and a back plate disposed outside each copper plate portion, and the high-pressure gas ejection portion is fixed to a lower end surface of the back plate of the mold. The continuous casting apparatus for steel according to claim 1.
3. The continuous steel according to claim 2, wherein the high-pressure gas ejection portion is divided and disposed on the lower side surface of the back plate of each of the short side portion and the long side portion of the mold. Casting equipment.
3. The continuous casting apparatus for steel according to claim 2, wherein the high-pressure gas jetting part is divided into a lower end surface of the back plate of the pair of short sides of the mold.
5. The jet port of the high-pressure gas jet section is disposed directly above each spray nozzle disposed on the lower outer side of the mold in addition to the corner portion of the mold. The continuous casting apparatus for steel according to any one of the above.
The high-pressure gas ejection part is formed of a plate-like member, and a flow path formed in the plate-like member in parallel with the longitudinal direction, and the end face of the plate-like member is formed in communication with the flow path. And a spray guard having an inclined surface that is formed on a lower surface of the plate-like member and guides cooling water sprayed from the uppermost spray nozzle downward from a horizontal direction. Item 6. The continuous casting apparatus for steel according to any one of Items 1 to 5.