JP2000087201A - Production device of hot dip metal plated steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for producing hot dip metal capable of preventing the flowing down of the hot dip metal from a hot dip metallic bath making a steel sheet pass through on a level free from problems in the operation over a long time. SOLUTION: This producing device 6 for a hot dip metal plated steel sheet is provided with a hot dip metal feeding bath 11 fed with hot dip metal and making a steel sheet 1 pass through from downside to upside and when the steel sheet 1 passes through the hot dip metal feeding bath 11, the hot dip metal is adhered to the surface of the steel sheet. The peripheral part of the steel sheet in a steel sheet passing part 11a of the hot dip metal feeding bath 11 is charged with an object 21 freely movable in the hot dip metal and having the size of a degree at which it is not fallen from an opening part 11b of the steel sheet passing part 11a.

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 manufacturing a hot-dip metal-plated steel sheet which is suitable as an aerial pot for producing steel.

[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. 7 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 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 an apparatus for manufacturing a metal-plated steel sheet.

[0013]

In order to solve the above-mentioned problems, the present invention comprises a molten metal supply bath to which a molten metal is supplied and which passes a steel sheet upward from below. A molten metal-plated steel sheet manufacturing apparatus for adhering a molten metal to the surface of a steel sheet when passing through the steel sheet, wherein the molten metal supply bath is capable of freely moving in the molten metal to the periphery of the steel sheet in the steel sheet passing section, and passing the steel sheet. The present invention provides an apparatus for manufacturing a hot-dip metal-plated steel sheet, wherein an object having a size that does not fall from an opening of a part is inserted.

Further, the present invention has a molten metal supply bath through which a molten metal is supplied and passes the steel sheet upward from below, and when the steel sheet passes through the molten metal supply bath, the molten metal adheres to the surface of the steel sheet. An apparatus for manufacturing a hot-dip metal-plated steel sheet, wherein a roll that can move in the thickness direction of the passing steel sheet is provided in a steel sheet passing section of the molten metal supply bath, and the steel sheet is sandwiched by the roll when the steel sheet is passed. Provided is a manufacturing apparatus for a hot-dip metal-plated steel sheet, characterized in that:

In the present invention, firstly, an object having a size that can move freely in the molten metal and does not drop from the steel sheet passage is provided around the steel sheet in the steel sheet passage of the molten metal supply bath. As this object comes in contact with the steel sheet during the passing, it closes the gap between the steel sheet and the supply bath, and closes the gap where the molten metal can flow down in the passing section where there is no steel sheet. The flow can be made extremely small, and when the thickness of the steel sheet is small and the sheet passing speed is high, the flow of the molten metal can be almost completely prevented.

Secondly, a roll is provided in the molten metal supply bath at a portion where the steel sheet passes, and the roll is movable in the thickness direction of the passing steel sheet. When the steel sheet passes through the roll, the steel sheet is sandwiched between the rolls. It is possible to prevent the molten metal from flowing down from the steel sheet passage at the position where the molten metal is in contact with the steel sheet. Also, due to the presence of the rolls, the amount of flow from both sides of the steel sheet passing portion can be extremely reduced, and when the steel sheet thickness is small and the sheet passing speed is fast, the flow of molten metal from both sides is almost completely prevented. be able to.

[0017]

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 for supplying molten metal L from a melting bath 16 for dissolving a plated metal ingot, and a molten metal supply bath 11 provided above the supply bath 11 for removing excess molten metal adhering to the steel sheet 1. The apparatus includes a gas wiping device 14 for wiping with gas, a falling molten metal receiving bath 12 provided below the gas wiping device 14, and a molten metal flow path 19 connecting the receiving bath 12 and the melting bath 16.

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.

As shown in the plan view of FIG. 2, a steel plate passing portion 11a having an opening 11b through which the steel plate 1 passes is formed at the bottom of the molten metal supply bath 11. A number of spherical objects 21 are formed around the steel plate at the opening 1
It is inserted so as not to fall from 1b. The steel plate passing portion 11a has a wall portion 11c, and the spherical member 21 is held by the steel plate passing portion 11a by the wall portion 11c. In addition,
The vicinity of the opening 11b on the bottom wall of the molten metal supply bath 11 is inclined so that the spherical object can easily contact the steel plate.

The falling metal receiving bath 12 is a molten metal supply bath 1.
1 and closely connected to each other, even if the opening 11b
Even if the molten metal flows down, it is received, and the molten metal is prevented from flowing down from the steel plate passage opening 12a provided at the bottom thereof.

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 vertically 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, molten metal is supplied from a melting bath 16 to a molten metal supply bath 11 via a supply flow path 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
b 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 spheres 21 are inserted into the passage 11a of the molten metal supply bath 11 so as not to fall from the openings 11b, the spheres 21 come into contact with the steel plate 1 in the passage. As a result, the gap between the steel sheet 1 and the supply bath 11 is closed, and the gap in which the molten metal can flow down in the steel sheet passing section 11a without the steel sheet 1 is closed, so that the flow of the molten metal from the steel sheet passing section can be extremely reduced, When the steel sheet 1 is thin and the sheet passing speed is high, it is possible to almost completely 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.

In this embodiment, the steel plate passing portion 11a
However, the present invention is not limited to this, and other materials such as a cylinder can be used as long as it can move quickly when the size of the steel sheet changes and can close the gap through which the molten metal flows down. It may be shaped.

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, the configuration inside a molten metal supply bath 11 is different from the previous embodiment.

That is, as shown in the plan view of FIG.
Steel plate passing section 11 formed at the bottom of molten metal supply bath 11
a is provided with a pair of rolls 22 that can move in the thickness direction of the steel sheet 1 passing therethrough instead of the large number of spherical objects 21 in the previous embodiment. The steel plate 1 is sandwiched by 22.

For this reason, it is possible to prevent the molten metal from flowing down from the opening 11b of the steel plate passing portion 11a at the position where the roll 22 is in contact with the steel plate 1. Also, due to the presence of the roll 22, the amount of flow from both sides of the steel sheet passing portion 11a can be extremely reduced, and when the steel sheet thickness is small and the sheet passing speed is fast, the flow of molten metal from both sides can be almost completely reduced. Can be prevented.

Since the roll 22 is not fixed by a bearing or the like so as to be movable in the thickness direction of the steel sheet, it can cope with a change in the steel sheet thickness. The vicinity of the opening 11b of the bottom wall of the molten metal supply bath 11 is inclined so that a force for sandwiching the steel plate 1 is easily generated.

By providing the steel plate passing portion 11a with the spherical body 21 and the roll 22 sandwiching the steel plate as in the above two embodiments, even if the steel plate size changes, the area of the opening 11b of the steel plate passing portion 11a can be reduced. It can be made extremely small, making it possible to reduce the flow of the molten metal and, in some cases, to completely prevent it from flowing down, so that it can be effectively used as an aerial pot.

Note that the spherical object 21 in these embodiments is
Both the roll 22 and the roll 22 may be put in the steel plate passing portion 11a. Also in this case, a cylindrical shape or the like is used instead of the spherical object 21.
Of course, objects of other shapes may be included.
In addition, since the spheres, rolls, and the like are put into the molten metal of the molten metal supply bath 11, it is preferable that the material be higher in density than the molten metal from the viewpoint of effectively closing the opening 11b. Further, it is preferable that the material has corrosion resistance to the molten metal.

Next, still another embodiment of the present invention will be described with reference to FIG. In this embodiment, the gas injection device 15 which supplies a non-oxidizing gas to the lower side of the falling molten metal receiving bath 12 and blows the gas to the steel sheet 1 from the opening through which the steel plate passes passes through the falling metal receiving bath 12. It is provided so as to be close to. This gas injection device 15
The gas is supplied through the pipe 20.

By installing the gas injection device 15 in this manner, 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. .

The flow rate required for this gas injection may be smaller than the gas flow rate necessary for completely preventing 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.

Although the falling molten metal receiving bath 12 is provided in each of the above embodiments, if the molten metal can be completely prevented from flowing down in the molten metal supply bath 11, the falling molten metal receiving bath 12 is provided. The bath 12 need not always be provided.

[0038]

Embodiments of the present invention will be described below. Here, the sealing performance of a low melting point metal (wood metal, melting point: 70 ° C., U-alloy 70 manufactured by Osaka Asahi Metal Factory) was verified using an apparatus as schematically shown in FIG.

A 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.

10 mm × 250 mm on the bath 12
The plating metal supply bath 11 having the steel plate opening 11b 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 was transferred to the supply bath 11 at a rate of 0.35 m3 / min from the melting bath 16 in which the temperature of the molten metal was kept at 100 ° C. by attaching an electric heater around the plating pump 17. In this supply bath 11, the bath surface height was kept constant (50 mm).

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 the wood metal to the press roll 5 side at various steel plate pulling speeds and steel plate thicknesses was grasped. FIG. 6 shows the result. In FIG. 6, the mark “○” indicates a state in which no flow is observed, the mark “△” indicates a state in which the flow is slightly reduced from time to time, and the mark “X” indicates a state in which the flow is slightly reduced but continuously observed.

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 was increased, a flow from the end of the roll 22 where the steel sheet 1 was not in contact with the roll 22 was observed.

Next, as shown in FIG.
5 was used to verify the sealing performance. The gas injection device 15 is provided with a discharge port of 2 mm × 250 mm to discharge nitrogen gas (the distance between the discharge port of the gas injection device 15 and the steel plate 1 is 1 mm). From the connecting tube. In the case of the steel plate thickness 2.5 mm and the steel plate pulling speed of 40 m / min where the flow of the wood metal was the largest in the above embodiment, the nitrogen gas was discharged from the gas injection device 15 on one side to 0.3 Nm3 / min or more. Was prevented from flowing down.

For comparison, without providing the roll 22 in the molten metal supply bath 11, similarly, nitrogen gas was discharged from the gas injection device 15, and the steel plate thickness was 2.5 mm and the steel plate pulling speed was 4 mm.
The amount of nitrogen gas required to prevent flow-down at 0 m / min was determined to be 0.8 Nm3 / min or more. This also confirms the effectiveness of the present invention.

[0045]

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 plan view showing the molten metal supply bath of FIG. 1;

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

FIG. 4 is an enlarged plan view showing the 5-molten metal supply bath of FIG. 3;

FIG. 5 is a schematic sectional view showing a part of an apparatus for manufacturing a hot-dip metal-plated steel sheet according to still another embodiment of the present invention.

FIG. 6 is a diagram for explaining the effect of the embodiment of the present invention.

FIG. 7 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 a 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 channel 19 ... Molten metal flow path 20 ... Piping 21 ... Spherical object 22 ... roll

Claims (2)

[Claims] 1. A molten metal supply bath to which a molten metal is supplied and through which a steel sheet passes from the bottom upwards, and wherein the molten metal adheres to the surface of the steel sheet when the steel sheet passes through the molten metal supply bath. An apparatus for manufacturing a steel sheet, wherein an object having a size that is freely movable in the molten metal and does not drop from an opening of the steel sheet passage is provided around the steel sheet in the steel sheet passage of the molten metal supply bath. An apparatus for producing a hot-dip metal-plated steel sheet. 2. A molten metal supply bath for supplying a molten metal and passing the steel sheet upward from below, wherein the molten metal is deposited on the surface of the steel sheet when the steel sheet passes through the molten metal supply bath. A steel sheet manufacturing device, characterized in that a roll that can move in the thickness direction of the passing steel sheet is provided in a steel sheet passing section of the molten metal supply bath, and the steel sheet is sandwiched by the roll when the steel sheet is passed. Equipment for hot-dip galvanized steel sheet.