JPH06306557A - Continuous hot dip metal coating apparatus for steel strip and the like - Google Patents

Abstract

PURPOSE:To easily control coating weight in a continuous hot dip metal coating apparatus for a steel strip, etc., even if line speed is changed. CONSTITUTION:A molten metal is supplied onto coating rolls 26,26' which are kept in contact, in planar or linear state, with a steel strip S. After the thicknesses of the molten metal films on the coating rolls 26, 26' are regulated to desired film thicknesses by means of gas wiping nozzles 28, 28', 30, 30', the molten metal films are transferred to the steel strip S to be plated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to hot dip galvanizing,
The present invention relates to a continuous hot-dip metal plating apparatus for steel strips and the like.

[0002]

2. Description of the Related Art A conventional continuous hot-dip galvanizing apparatus for hot-dip zinc or the like is generally of a so-called dashing method as shown in FIG. That is, in FIG. 1, the annealed steel strip S to be plated is guided to the plating bath 10 by a snout 11, and the direction is changed by a sink roll 12 immersed in the plating bath. The molten metal that has been adhered and pulled up is scraped off by a gas wiping nozzle 14 or the like to a predetermined amount of plating adhesion, and then an alloying furnace 16 performs an alloying treatment if necessary.

[0003]

However, the conventional method as described above has the following problems.

First, the hot-dip zinc bath has a large capacity of over 200 tons in recent years because it corresponds to the plating of wide steel strips in recent years. Therefore, for example, it takes a long time and a lot of labor to change the components in the bath such as aluminum accompanying the change of product type.

Second, the sink roll (12 in FIG. 1) immersed in the bath, the support roll in the bath (18 in FIG. 1)
Because of the special environment of bearings such as molten zinc, it is not possible to use precision bearings and they have a play of several mm. For this reason, the steel strip vibrates at the wiping nozzle position, resulting in non-uniform adhesion.

As a method for solving these problems, JP-B-58-10984 is used for plating by contacting a coating roll on both sides or one side of a steel strip having an oblique path and supplying molten metal to the coating roll. A method is disclosed. Among them, as a method for adjusting the amount of molten metal on the coating roll, first, a doctor roll or a doctor blade is attached to the coating roll, secondly, the coating roll and the pickup roll for scraping the molten metal are separated, Two methods of transferring molten metal from a pick-up roll to a coating roll and then transferring it to a steel strip are shown.

Generally, in a method of continuously supplying a molten metal to a steel strip by a coating roll and plating, the coating roll needs to be a metal roll or a ceramic spray roll having excellent corrosion resistance to the molten metal. is there. Therefore, the rotation direction of the coating roll is the same as the traveling direction of the steel strip, and if it is not rotated at a substantially constant speed, the steel strip will be scratched, which will cause an appearance defect and lose its value as a plated steel sheet. Will be. When a doctor roll or a pickup roll is installed side by side and both rolls are pressed against each other, the same relationship occurs, and when a large speed difference is to be provided, it is necessary to provide a gap.

From the above points, in the above-mentioned method for adjusting the amount of molten metal, it is necessary to change the line speed and the peripheral speed of the doctor roll or the pick-up roll at substantially the same speed. It will change. When a gap is provided, the micron-order adjustment is performed in an atmosphere kept at a high temperature to prevent the solidification of molten metal.
It is almost impossible, and if a large gap is used, thick basis weight is possible, but it has recently been required to improve workability.
A thin weight of 0 g / m ² or less (plating thickness 4 μm or less) is impossible. Further, since the doctor blade is heavily worn, the frequency of replacement is very high, and the distribution of the adhered amount in the width direction is not uniform.

The present invention has been made to solve the above-mentioned conventional problems, and provides a continuous hot-dip metal plating apparatus for steel strips or the like, which can easily control the amount of plating adhered even if the line speed changes. The purpose is to do.

[0010]

DISCLOSURE OF THE INVENTION The present invention relates to a continuous hot-dip galvanizing apparatus for steel strips and the like, and a coating roll that rotates in the same direction as the moving direction of the steel strip and is in contact with the steel strip in a planar or linear manner. A means for supplying molten metal to the coating roll, and a gas wiping nozzle for adjusting the film thickness of the molten metal film supplied to the surface of the coating roll,
The molten metal film on the surface of the coating roll, which is adjusted by the gas wiping nozzle, is transferred to the steel strip to be plated, thereby achieving the above object.

The present invention also achieves the above object in a continuous hot-dip galvanizing apparatus for steel strip or the like, in which the means for feeding the molten metal to the coating roll is an apparatus for feeding the molten metal. It was done.

The present invention also provides a continuous molten metal plating apparatus for a steel strip or the like, in which the steel strip is formed as a vertical pie line directed from the upper side to the lower side, and a molten metal bath provided at a position not in direct contact with the steel strip, A coating roll which rotates in the same direction as the moving direction of the steel strip, a part of which is immersed in the molten metal bath, and the other part of which is in planar or linear contact with the steel strip, and melting which adheres to the surface of the coating roll A gas wiping nozzle for adjusting the film thickness of the metal film is provided, the molten metal film is scraped from the molten metal bath by the coating roll, and the molten metal film having the film thickness adjusted by the gas wiping nozzle is applied to the steel strip to be plated. Similarly, the above-mentioned object is achieved by transferring.

[0013]

Basically, as shown in FIG. 2, in the present invention, in a continuous hot-dip galvanizing apparatus for steel strips, etc., the molten metal is supplied onto a coating roll which is in planar or linear contact with the steel strip and then coated. The molten metal film on the roll is adjusted to a desired film thickness by a gas wiping nozzle and then transferred to a steel strip to be plated.

In FIG. 2, the annealed steel strip S is guided to the inside of the seal box 22 in which the plating apparatus according to the present invention is housed, after changing the direction by the deflector roll 20 after adjusting the plate temperature suitable for plating. , Coating rolls 26, 26 'that rotate in the same direction as the moving direction of the steel strip,
Molten metal is deposited.

Here, the coating rolls 26, 26 '
When the steel strip S rises, the molten metal supplied to the pipes is wiped by the wiping nozzles 28, 28 ', and when the steel strip S descends, the molten metal is fed by the wiping nozzles 30, 30'. A desired film thickness is adjusted before being attached to S.

Although not shown, as a method of supplying the molten metal to the coating rolls 26, 26 ', a pouring device is used when the steel strip S is raised, and a molten metal is fed when the steel strip S is lowered. It is carried out by scraping the coating roll 26, 26 'from a molten metal bath provided so that a part of the coating roll 26, 26' is not in direct contact with the steel strip S.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings, taking as an example the case of applying hot-dip galvanizing.

FIG. 3 is a conceptual diagram showing the outline of the first embodiment of the present invention.

In FIG. 3, the steel strip S to be plated annealed in the annealing furnace is at a temperature suitable for plating (around 500 ° C.),
The deflector roll 20 changes the traveling direction and guides it to the plating part. As shown in FIG. 3, the coating roll 26 'for plating on the surface opposite to the coating roll 26 is
The coating rolls 26 and 2 are arranged offset from each other.
6'is in contact with the steel strip S in a planar shape (arc shape). At this time, the pressing amount of the coating rolls 26, 26 'is adjustable, and the winding angle can be changed. The coating roll and the steel strip may be in line (dotted) contact, but if the shape of the steel sheet is poor,
Plating unevenness is liable to occur, and it is desirable to make a planar contact.

The coating rolls 26, 26 'are made of steel strip S.
Is rotating at the same speed in the same direction as the moving direction, and molten zinc is supplied by the molten metal supply devices 32 and 32 '. The supplied excess molten zinc is scraped off by the gas wiping nozzles 28 and 28 ', and is transferred to the steel strip S after having a film thickness on the coating roll suitable for obtaining a predetermined coating amount. . The scraped molten zinc is recovered by the receiving pans 34, 34 ', guided to a melting tank (not shown), and sent again to the supply devices 32, 32'.

The above-mentioned plating apparatus portion is housed in the seal box 22. The inside of the seal box is kept at a high temperature above the melting point (420 ° C.) to prevent the solidification of the molten zinc, and the dross and ash are eliminated. To prevent the occurrence
The atmosphere is maintained in a non-oxidizing or reducing atmosphere.
It is preferable that the gas wiping nozzles 28, 28 'are slit nozzles capable of uniformly injecting gas in the width direction and preheated nitrogen gas is used. Also, coating roll 2
One side of 6 or 26 'can be separated from the steel strip S to perform single-sided plating, and different types of metal can be supplied to the molten metal supply devices 32 and 32' to perform different kinds of front and back surfaces.

The plated steel strip S passes through the sealing device 24, is guided from the seal box 22 to the outside, and is subjected to alloying treatment if necessary.

FIG. 4 is a conceptual diagram showing the outline of the second embodiment according to the present invention. Here again, the case of performing hot dip galvanizing will be described as an example.

In FIG. 4, the steel strip S to be plated annealed in the annealing furnace can be turned downward by the deflector roll 20 at a temperature suitable for plating. The plating section is configured as a vertical path from top to bottom, the coating rolls 26, 26 'are arranged offset
The wrapping angle is adjustable, as in the first embodiment.

The coating rolls 26, 26 'rotate in the same direction as the moving direction of the steel strip S and at the same speed, and scrape molten zinc from the molten metal baths 36, 36'. The amount of the molten zinc scraped up is large, and in order to obtain a predetermined coating amount, a film on the coating roll suitable for scraping off the excess by the gas wiping nozzles 30 and 30 'to obtain a predetermined coating amount. After being thickened, it is transferred to the steel strip S.

The wiping gas and the atmosphere in the seal box are the same as in the first embodiment. The plated steel strip passes through the sealing device 24, is guided to the outside from the seal box 22, and is alloyed as necessary.

In the second embodiment, hot-dip galvanizing was performed on a steel strip having a plate thickness of 0.7 mm and a plate width of 1000 mm with a φ600 coating roll. In order to prevent scratches on the steel strip, the peripheral speed of the coating roll was equal to the line speed, the tension per unit cross-sectional area of the steel strip was 1.5 kg / mm ² , and the winding angle of the steel strip on the coating roll was 10 °.

FIG. 5 shows the relationship between the line speed and the amount of plating deposited when gas wiping is not performed. Thus, if the coating roll peripheral speed is equal to the line speed for preventing scratches, not only does the coating amount change as the line speed changes, but the coating amount is approximately 100 g / m 2.
^Since it is ² or more, plating of about 30 g / m ² required for improving workability for automobiles cannot be performed.

Next, with a wiping nozzle having a slit width of 1.0 mm and a distance between the nozzle and the coating roll of 12 mm,
Nitrogen gas was used to wipe and then plate the molten zinc on the coating roll. Fig. 6 shows the adhesion amount 40g /
The relationship between the wiping nozzle gas pressure and the line speed for setting m ² is shown. In this way, by controlling the wiping nozzle pressure according to the line speed, the adhered amount can be made constant even if the line speed is changed. At this time, the distribution of the adhesion amount in the width direction was uniform on the front and back surfaces, and good plating could not be obtained.

[0030]

As described above, according to the present invention, the amount of plating adhered is controlled by adjusting the molten metal film on the coating roll with the gas wiping nozzle, so that only the nozzle pressure control is simple. With this method, even if the line speed changes, it is possible to control to the desired amount of plating deposition, complicated doctor roll gap setting, frequent replacement of doctor blades can be eliminated, and a large-capacity molten metal bath is unnecessary. It has an excellent effect that the concentration of the bath components such as aluminum can be changed quickly, and unevenness of the adhered amount due to looseness of the sink roll and the support roll in the bath can be eliminated.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing the configuration of a conventional continuous molten metal plating apparatus.

FIG. 2 is a conceptual diagram showing the basic idea of the present invention.

FIG. 3 is a conceptual diagram showing a configuration of a first embodiment of the present invention.

FIG. 4 is a conceptual diagram showing a configuration of a second embodiment of the present invention.

FIG. 5 is a diagram showing the relationship between the line speed and the amount of plating adhered when gas wiping is not used in the second embodiment.

FIG. 6 is a diagram showing the relationship between the wiping nozzle gas pressure and the line speed for the same amount of adhesion of 40 g / m ² .

[Explanation of symbols]

 S ... Steel strip 20 ... Deflector roll 22 ... Seal box 24 ... Sealing device 26, 26 '... Coating roll 28, 28', 30, 30 '... Gas wiping nozzle 32, 32' ... Molten metal supply device 34, 34 '... Receiving pan 36, 36 '... Molten metal bath

Claims (3)

[Claims] 1. A continuous hot metal plating apparatus for steel strips and the like, wherein a coating roll that rotates in the same direction as the moving direction of the steel strip and comes into contact with the steel strip in a planar or linear manner, and a molten metal on the coating roll. A means for supplying and a gas wiping nozzle for adjusting the film thickness of the molten metal film supplied on the surface of the coating roll are provided, and the molten metal film on the surface of the coating roll adjusted by the gas wiping nozzle is plated. A continuous hot-dip metal plating device for steel strips, etc., which is characterized by transferring onto steel strips. 2. The continuous molten metal plating apparatus for steel strips according to claim 1, wherein the means for supplying the molten metal to the coating roll is a device for supplying the molten metal by pouring. 3. A continuous molten metal plating apparatus for a steel strip or the like, in which the steel strip is formed as a vertical pie line that faces downward from above, and a molten metal bath provided at a position where it does not come into direct contact with the steel strip, A coating roll which rotates in the same direction as the moving direction, a part of which is immersed in the molten metal bath, and the other part of which is in planar or linear contact with the steel strip, and a film of the molten metal film adhered to the surface of the coating roll. And a gas wiping nozzle for adjusting the thickness, by the coating roll, from the molten metal bath,
A continuous hot-dip metal plating apparatus for a steel strip or the like, wherein a molten metal film which is scraped up and whose film thickness is adjusted by the gas wiping nozzle is transferred to a steel strip to be plated.