JP2000008150A - Apparatus for producing hot dip metal coated steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for producing a hot dip metal coated steel sheet by which a hot dip metal is prevented from flowing down from a hot dip metal bath through which a steel sheet passes on a level without causing any problem of operation for a long time. SOLUTION: A coating device 6 is provided with a hot dip metal feeding bath 11 to which a hot dip metal L is fed from a melting bath 16 for melting a coating metal ingot, a gas wiping device 14 provided in the upper direction of the feeding bath 11 and wiping the excessive hot dip metal deposited to the steel sheet by a gas, a flowing-down hot dip metal receiving bath 12 provided in the lower direction thereof, a pair of pressing rolls 5 moving vertically to the moving direction of the steel sheet 1, holding the steel sheet before the charging to the hot dip metal feeding bath 11 and pressing it, and a flowing- down hot dip metal receiving member 20 set in the flowing-down hot dip metal receiving bath 12 and movable cooperatively with the pressing rolls 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for continuously producing a hot-dip galvanized steel sheet, and particularly to a hot-dip galvanized steel sheet (including an alloyed hot-dip galvanized steel sheet; the same applies hereinafter).
The present invention relates to an apparatus for producing a hot-dip metal-plated steel sheet suitable for an aerial pot for producing a steel sheet.

[0002]

2. Description of the Related Art Hot-dip metal-plated steel sheets, such as zinc, aluminum, and alloys thereof, have been generally produced as follows. That is, the thin steel sheet after cold rolling is subjected to surface cleaning in a pretreatment step, a surface oxide film is removed in an annealing furnace maintained in a non-oxidizing or reducing atmosphere, annealing is performed, and then cooling is performed. Then, the molten metal is cooled to approximately the same temperature as the molten metal bath and penetrated into the molten metal bath. Thereafter, the steel sheet is pulled out of the bath, and excess molten metal adhering to the steel sheet surface is wiped off with a gas wiper.

FIG. 4 shows a portion around a molten metal bath of an apparatus used for producing a conventional molten metal plated steel sheet. Steel plate 31
Is drawn into a molten metal bath 32 from a snout 34 kept in a non-oxidizing atmosphere, is pulled vertically through a sink roll 33 and a support roll 35, and excess molten metal is wiped by a gas wiper 36.

However, in such a conventional apparatus, impurities such as dross are generated in the bath, and these impurities adhere to the rolls in the bath to form press flaws on the steel sheet, or adhere to the steel sheet to cause a problem during processing. Causes surface defects. In order to prevent such defects, countermeasures have been taken such as taking out the roll in the bath and performing maintenance, and installing a current plate at the bottom of the bath so that dross does not float in the bath. In addition, in the roll in the bath, poor rotation etc. occur due to melting damage by the molten metal,
This causes plating defects. Correspondingly,
Rolls are exchanged regularly in the bath, and a treatment is performed to spray ceramics or the like on the roll surface.

As described above, when a hot-dip metal-plated steel sheet is manufactured by a conventional manufacturing apparatus, quality and operability are disadvantageously deteriorated.

[0006] The molten metal bath is extremely large for installing equipment in the bath. Therefore, when manufacturing several types of hot-dip metal-plated steel sheets on the same line, changing the bath at the time of changing the type requires a lot of time, cost and labor.

In order to cope with such a problem, a so-called aerial pot has been developed in which a molten metal is held in a bath having an opening at the bottom and plating is performed by passing a steel sheet from below the opening. . For example, JP-A-63-10914
No. 8 discloses an aerial pot by circulation, and describes that a static pressure is applied to a steel plate introduction portion. Also,
JP-A-63-303045 discloses an aerial pot that holds a molten metal by electromagnetic force and injects gas at a position where a steel sheet passes. Further, Japanese Patent Laid-Open No. 1-13
No. 9744 discloses a method of supplying molten metal between a pair of rotating drums. Furthermore, Japanese Patent Laid-Open No.
JP-A-36447 discloses an apparatus in which a seal plate for holding a gap between a steel plate and a steel plate at 0.05 to 1 mm is installed at the bottom of a hot-dip metal plating bath. Each of the devices has a pressure chamber.

The problem with the above aerial pot is how to hold the molten metal so that it does not flow down from the opening at the bottom of the bath, and many of the techniques disclosed so far focus on that point. is there.

[0009]

However, Japanese Patent Application Laid-Open No. 63-109148 and Japanese Patent Application Laid-Open No. 63-303
As disclosed in Japanese Patent Publication No. 045, the technology for preventing the flow of molten metal by gas pressure or electromagnetic force requires controlling the gas pressure or electromagnetic force according to the height of the bath surface or the complicated flowing state of the molten metal flowing down. In addition, these conventional techniques do not provide a sufficient control method, and also have a limited control range. Further, the method of preventing the molten metal from flowing down by injecting a gas also has problems such as scattering of the molten metal and defective plating caused by entrainment of bubbles.

Further, the technique of providing a seal plate as disclosed in Japanese Patent Application Laid-Open Nos. 4-36447 and 9-53164 discloses a technique in which a distance between a steel plate and a seal plate is set to 0.05.
Although it is necessary to keep the thickness to １1 mm, there is a problem that the steel plate actually comes into contact with the seal plate and the surface of the steel plate is damaged.
Furthermore, the method of supplying molten metal between the rotating drums disclosed in Japanese Patent Application Laid-Open No. 1-139744 has a problem in that the molten metal flows down at the end of the roll that is not in contact with the steel plate.

As described above, it is difficult for any of the above-mentioned prior arts to prevent the molten metal from flowing down for a long time at a level that does not cause a problem in operation.

The present invention has been made in view of such circumstances, and it is possible to prevent a molten metal from flowing down from a molten metal bath passing through a steel sheet at a level at which there is no problem in operation for a long time. An object of the present invention is to provide a metal manufacturing apparatus.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a melting method in which a molten metal is supplied from a melting bath in which a metal ingot is charged and melted, and a steel sheet is passed upward from below. A metal supply bath, a device for wiping excess molten metal by gas when pulling up a steel sheet on which the molten metal adheres to the surface by passing through the molten metal supply bath, and a lower side of the molten metal supply bath. A molten metal receiving bath for receiving molten metal flowing down from the molten metal supply bath, and a pair of pressing rolls that move perpendicularly to the moving direction of the steel sheet and sandwich and hold the steel sheet before reaching the molten metal supply bath. And a falling molten metal receiving member installed in the falling molten metal receiving bath and movable vertically with respect to the moving direction of the steel sheet in conjunction with the pair of holding rolls. Providing an apparatus for manufacturing coated steel sheet.

The present invention also provides an apparatus for producing a hot-dip coated steel sheet, characterized in that the above-mentioned apparatus further comprises a hot-dip metal flow path for connecting the falling hot-dip metal receiving bath and the melting bath. .

Further, according to the present invention, there is provided any one of the above apparatuses, further comprising a non-oxidizing, non-oxidizing material that can move vertically below the moving direction of the steel sheet in conjunction with the holding roll under the falling molten metal receiving bath. An apparatus for manufacturing a hot-dip metal-plated steel sheet, comprising: an apparatus for supplying a gas and blowing the gas to the steel sheet from a steel sheet passage opening.

Further, the present invention provides any one of the above apparatuses, further comprising: a pair of rotating rolls provided so as to sandwich the steel sheet inside the falling molten metal receiving bath and at the position of the steel sheet passage opening. An apparatus for manufacturing a hot-dip metal-plated steel sheet, comprising: a blade for scraping molten metal on a rotating roll.

In the present invention, the falling molten metal receiving member, which moves perpendicularly to the moving direction of the steel sheet in conjunction with the pair of holding rolls for sandwiching and holding the steel sheet before reaching the molten metal supply bath, is placed in the falling molten metal receiving bath. Since it is installed, even when the thickness of the steel sheet changes, the molten metal flowing down to the falling molten metal receiving bath can be reliably received by the holding member, so that the molten metal can be more reliably prevented from flowing down. it can.

[0018]

Embodiments of the present invention will be described below. FIG. 1 is a schematic cross-sectional view of a plating facility including an apparatus (aerial pot) for a hot-dip metal-plated steel sheet according to an embodiment of the present invention. The steel sheet 1 is annealed in an annealing furnace 2,
After being cooled, it is transported in the vertical direction by the deflector roll 3, the shape is corrected by the support roll 4, and then the plating apparatus (air pot) is passed through a pair of holding rolls 5.
6. The pair of holding rolls 5 are provided to suppress vibration of the steel plate and determine a pass line. The holding roll 5 has a structure that can move in a direction perpendicular to the moving direction of the steel sheet, and is always in contact with the steel sheet 1 by applying a load so as to sandwich the steel sheet. Therefore, when the thickness of the steel plate 1 changes, the steel plate 1 can move symmetrically from the center of the pass line according to the thickness. The support roll 4 is not essential, but it is desirable to install the support roll 4 from the point of straightening the steel sheet.

The plating apparatus 6 includes a molten metal supply bath 11 in which a molten metal L is supplied from a melting bath 16 for dissolving a plated metal ingot, and an excess molten metal provided on the supply bath 11 and adhering to the steel plate 1. A gas wiping device 14 for wiping with gas, a seal mechanism 13 installed at a steel plate passage opening 11a at the bottom of the supply bath 11, a falling molten metal receiving bath 12 provided therebelow, a receiving bath 12 and a melting bath And a molten metal flow path 19 connecting the molten metal flow path 16 and the molten metal flow path 19.

The molten metal L from the melting bath 16 is supplied to the molten metal supply bath 11 through a supply passage 18 by a molten metal transfer device 17 such as a pump. On the other hand, the molten metal L that has flowed down into the falling molten metal receiving bath 12 through the molten metal flow path 19 is returned to the melting bath 16.

The sealing mechanism 13 is not particularly limited in the sealing method, and may be a conventional sealing plate, and need not be a large-scale mechanism utilizing electromagnetic force. The opening 11a preferably has an opening width of several mm or more so as not to come into contact with the steel plate. Therefore, the molten metal in the molten metal supply bath 11 is
It will flow down from a. That is, since the flow of the molten metal is inevitable in the conventional sealing technology, the present invention presupposes the flow of the molten metal. Is provided below. In addition, the sealing mechanism 1
3 is preferably provided, but is not essential.

The falling metal receiving bath 12 is a molten metal supply bath 1.
1, and a pair of flowing metal receiving members 20 are disposed so as to sandwich the steel plate 1 therebetween. As shown in FIG. 2, this falling metal receiving member 20
The pressing roll 5 is connected to the pressing member 5 by a connecting member 21, and has a structure in which the pressing member 5 can move in a direction perpendicular to the moving direction of the steel plate 1 in conjunction with the pressing roll 5. With such a structure, the opening 1
The molten metal flowing down from 1a is received, and the molten metal is prevented from flowing down from the steel plate passage opening 12a provided at the bottom.

In the plating equipment configured as described above, the steel sheet 1 that has been annealed and cooled in the annealing furnace 2 and conveyed in the vertical direction by the deflector roll 3
Then, it is conveyed to a plating apparatus (air pot) 6 via a holding roll 5.

In the plating apparatus 6, the molten metal is supplied from the melting bath 16 to the molten metal supply bath 11 via the supply channel 18. On the other hand, the steel sheet 1 is supplied into the flowing molten metal receiving bath 12 through an opening 12 a at the bottom of the bath 12, and the opening 11 a
a to the molten metal supply bath 11. While the steel sheet 1 passes through the molten metal supply bath 11 from below to above, the molten metal is attached to the surface thereof. Then, the molten metal supply bath 11
The steel plate 1 pulled up from the gas wiping device 14
Wiping off excess molten metal.

In this case, since the opening portion 11a of the molten metal supply bath 11 through which the steel sheet passes does not come into contact with the steel sheet, the molten metal of the molten metal supply bath 11 is
Flow down from 1a. The molten metal flowing down from the opening 11a is supplied to the molten metal receiving member 20 of the flowing molten metal receiving bath 12, and flows so as to be divided into right and left. The left and right divided molten metal flows along the molten metal receiving member 20 and flows down into the falling metal receiving bath 12.

As described above, since the molten metal separated to the left and right by the falling molten metal receiving member 20 is received by the falling molten metal receiving bath 12, it is possible to prevent the molten metal from flowing down from the falling molten metal receiving bath 12. Can be.

In this case, below the receiving bath 12, a pressing roll 5 movable in a direction perpendicular to the moving direction of the steel plate is provided, and the molten metal receiving member 20 moves the steel plate in conjunction with the pressing roll 5. Therefore, even when the thickness of the steel plate changes, the distance between the receiving member 20 and the steel plate 1 can be kept equal. Therefore, even when the thickness of the steel plate 1 changes, the molten metal flowing down to the falling molten metal receiving bath is held by the holding member 2.
Since it is possible to reliably receive the molten metal at 0, it is possible to more reliably prevent the molten metal from flowing down.

Further, since the molten metal in the falling molten metal receiving bath 12 is connected by a molten metal flow path 19 so as to be able to flow into a melting bath 16 in which an ingot of a plated metal is charged and melted, the molten metal flows down. The molten metal can be supplied to the molten metal supply bath 11 again, which is economical.

Next, another embodiment of the present invention will be described. FIG. 3 is a schematic sectional view showing an apparatus for manufacturing a hot-dip metal-plated steel sheet according to another embodiment of the present invention. In this embodiment, there is provided a gas injection device 15 that supplies a non-oxidizing gas to the lower side of the falling molten metal receiving bath 12 and blows the gas onto the steel plate 1 from an opening through which the steel plate passes. The gas supply to the gas injection device 15 is performed via a pipe 22. The gas injection device 15 is connected to the pressing roll 5 by a connecting member 21 ′, and is provided continuously with the falling molten metal receiving member 20.

By installing the gas injection device 15 in this way, the amount of molten metal received in the falling molten metal receiving bath 12 can be increased. That is, by blowing a non-oxidizing gas onto the molten metal flowing down from the gas injection device 15 disposed below the receiving bath 12, the molten metal flowing down from the receiving bath 12 can be eliminated or reduced. . Further, since the gas injection device 15 moves in conjunction with the pressing roll 5, even when the thickness of the steel plate 1 changes, the distance between the gas injection device 15 and the steel plate 1 can be maintained at the initially set distance. Thus, the flow of the molten metal can be more reliably prevented.

The flow rate required for this gas injection may be smaller than the gas flow rate required to completely prevent the gas from flowing down in the conventional aerial pot.
Since the gas is not sprayed directly on the molten metal, the entrapment of the gas, which has been a problem in the past, does not occur. Further, even if the molten metal is scattered by gas spraying, the receiving bath 12 is supplied by the supply bath 11.
The molten metal does not scatter outside the system because the structure is closely connected to the immersion bath. There is no danger of sticking to the wall surface.

The reason why the non-oxidizing gas is used as the injection gas is to prevent oxidation of the steel sheet and prevent plating failure. Further, from the viewpoint of preventing a temperature drop of the steel sheet, it is desirable to use a high-temperature gas having a temperature substantially equal to the bath temperature. The non-oxidizing gas is not particularly limited, and for example, a dehydrated inert gas or a gas in the annealing furnace 2 can be used.

Next, still another embodiment of the present invention will be described. FIG. 4 is a schematic sectional view showing an apparatus for manufacturing a hot-dip metal-plated steel sheet according to still another embodiment of the present invention. In this embodiment, a pair of rotating rolls 23 provided so as to sandwich the steel plate 1 at the position of the steel plate passage opening inside the falling molten metal receiving bath 12, and a blade 24 for scraping the molten metal on the rotating roll 23. have.

A pair of rotating rolls 23 provided inside the falling metal receiving bath 12 prevent the molten metal supplied thereto from flowing downward from the steel plate passage opening 12a at the bottom of the falling metal receiving bath 12. It has the function to do. The rotating roll 23 may be of a driving type, but is preferably of an idling type because it can suppress vibration of a steel plate. The rotating rolls 23 are configured to rotate upward from the bottom at the steel plate contact portion. It is desirable to heat the rotating roll 23 so that the molten metal does not adhere to the surface of the rotating roll 23 to maintain the roll surface temperature equal to or higher than the melting point of the plating metal.

Since the rotating roll 23 rotates upward from the bottom at the steel plate contact portion with the upward movement of the steel sheet 1, the molten metal supplied to the rotating roll 23 flows so as to be divided into right and left on the upper surface. The left and right molten metal is scraped off by the blade 24 and flows down into the falling metal receiving bath 12.

As described above, since the molten metal is divided into right and left by the rotating roll 23 and the molten metal is scraped off by the blade 24, the molten metal reaching the falling metal receiving member 20 is very small. Flowing down can be prevented more effectively.

The present invention can be variously modified without being limited to the above embodiment. For example, the shape of the falling metal receiving member does not need to be limited to the shape shown in the figure, and may be a roll, for example, as long as the molten metal can be divided into left and right.

[0038]

Embodiments of the present invention will be described below. In this case, a low melting point metal (wood metal, melting point: 70 ° C., Osaka Asahi Metal Factory) is used by using an apparatus as schematically shown in FIG. 1 provided with a roll 23 and a scraping blade 24 shown in FIG. The sealability of U-Alloy 70) was verified.

The steel sheet 1 (width 200 mm) was introduced into a plating apparatus (air pot) 6 from a holding roll 5 (roll diameter 50 mm) via a deflector roll 3 and a support roll 4. The distance between the steel sheet passage opening 12a and the steel sheet 1 in the falling molten metal receiving bath 12 was adjusted to 1 mm. A pair of idling-type steel rolls (diameter: 100 mm) 23 rotating by the movement of the steel plate are arranged in the receiving bath 12 so as to sandwich the steel plate 1. This rotating roll 23
Then, a blade 24 made of Teflon was pressed to scrape the molten metal. A falling metal receiving member 20 that can move below the rotating roll 23 in conjunction with the pressing roll 5.
Was provided.

10 mm × 250 mm on the bath 12
The plating metal supply bath 11 having the steel plate opening was connected so as to be in close contact with the receiving bath 12. The receiving bath 12 and the dissolving bath 16 were connected by a pipe 19 having an inner diameter of 50 mm, and the wood metal accumulated in the receiving bath 12 was guided to the dissolving bath 16. The plating metal is supplied at a rate of 0.35 m ³ / min from a melting bath 16 in which an electric heater is attached to the periphery by a pump 17 to maintain the temperature of the molten metal at 100 ° C.
Transferred to. In this supply bath, the bath surface height is fixed (50 m
m) to provide an overflow weir.

The steel sheet 1 is heated from 40 m / min to 160 m / m.
It was pulled upward at a speed of "in", and the flow of wood metal from the steel plate passage opening 12a of the receiving bath 12 was observed.
As a result, no contact between the steel plate and the aerial pot was observed under any conditions, and there was no problem with the sheet passing property. In addition, the falling state of wood metal at various steel sheet pulling speeds and steel sheet thicknesses was grasped. The result is shown in FIG. In FIG. 5, ○
The mark indicates a state in which no flow was observed, the mark Δ sometimes indicates a state in which the flow was slightly reduced, and the mark X indicates a state in which the amount of flow was small but continuous.

When the thickness of the steel sheet is 1.0 mm or less, no flow of the wood metal from the steel sheet passage opening 12a of the receiving bath 12 is observed at any speed, and the apparatus can prevent the flow of the molten metal. confirmed. When the thickness of the steel sheet is increased, the rotating roll 2 not in contact with the steel sheet 1
Flow from the end of No. 1 was observed.

Next, FIG. 4 shows an apparatus schematically shown in FIG.
The same sealing performance was verified using a roll provided with a roll 23 and a scraping blade 24 shown in FIG. The gas injection device 15 was provided with a discharge port of 2 mm × 250 mm to discharge nitrogen gas, and gas was discharged from the receiving bath 12 through a connection pipe with the dissolving bath 16. In the above embodiment, when the steel sheet thickness was 2.5 mm and the steel sheet pulling speed was 40 m / min, which caused the largest flow of wood metal, the nitrogen gas was discharged from the gas injection device 15 on one side at 0.8 Nm ³ / min or more. Metal flow was prevented. As described above, in the case where the gas injection device 15 was not provided, the flowing down of the wood metal observed from the roll end was not observed in any case. This confirmed the effectiveness of the device.

[0044]

As described above, according to the present invention,
It is possible to prevent the molten metal from flowing down from the molten metal bath passing through the steel sheet at a level that does not cause a problem in operation for a long time. Therefore, it is possible to enjoy the advantages of the so-called aerial pot type plating equipment, such as eliminating defects and dross defects caused by bath equipment, achieving long-term stable operation, and easily switching to different types of products. Becomes

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a plating facility including an apparatus for producing a hot-dip metal-plated steel sheet according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing the falling molten metal receiving bath of FIG. 1;

FIG. 3 is a schematic sectional view showing an apparatus for manufacturing a hot-dip metal-plated steel sheet according to another embodiment of the present invention.

FIG. 4 is a schematic sectional view showing an apparatus for manufacturing a hot-dip metal-plated steel sheet according to still another embodiment of the present invention.

FIG. 5 is a diagram for explaining the effect of the embodiment of the present invention.

FIG. 6 is a schematic sectional view showing a conventional plating apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Steel plate 2 ... Annealing furnace 3 ... Deflector roll 4 ... Support roll 5 ... Holding roll 6 ... Manufacturing apparatus of molten metal plating steel plate 11 ... Molten metal supply bath 12 ... Downflow molten metal receiving bath 13 ... Sealing mechanism 14 Gas wiping device 15 Gas injection device 16 Melting bath 17 Molten metal transfer device 18 Supply flow path 19 Molten metal flow path 20 Downflowing molten metal receiving member 21 , 21 '... connecting member 23 ... rotating roll 24 ... scraping blade

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K027 AA02 AA22 AB28 AB42 AC33 AC52 AC73 AD05 AD08 AD17 AD18 AD22 AE06 AE08 AE15 AE33 AE36

Claims (4)

[Claims] 1. A molten metal supply bath in which a molten metal is supplied from a melting bath in which a metal ingot is charged and melted to pass a steel sheet upward from below, and a molten metal supplied by passing through the molten metal supply bath. A device for wiping excess molten metal by gas when the steel sheet attached to the surface is pulled upward; and a device provided below the molten metal supply bath for receiving molten metal flowing down from the molten metal supply bath. A molten metal receiving bath, a pair of pressing rolls that move perpendicularly to the moving direction of the steel sheet and sandwich and hold the steel sheet before reaching the molten metal supply bath; and An apparatus for producing a hot-dip metal-plated steel sheet, comprising: a falling molten metal receiving member movable in a direction perpendicular to a moving direction of the steel sheet in conjunction with a holding roll. 2. The apparatus according to claim 1, further comprising a molten metal flow path connecting the falling molten metal receiving bath and the melting bath. 3. A non-oxidizing gas, which is movable in a direction perpendicular to the moving direction of the steel sheet in conjunction with the holding roll, is supplied to the lower side of the falling molten metal receiving bath, and the non-oxidizing gas is supplied from the steel sheet passage opening. The apparatus for producing a hot-dip metal-plated steel sheet according to claim 1 or 2, further comprising an apparatus for blowing gas onto the steel sheet. 4. A pair of rotating rolls provided so as to sandwich a steel plate inside the falling molten metal receiving bath and at the position of the steel plate passage opening, and a blade for scraping the molten metal on the rotating roll. The apparatus for manufacturing a hot-dip metal-coated steel sheet according to any one of claims 1 to 3, wherein the apparatus is provided.