JPH05106005A - Method and apparatus for hot dipping - Google Patents

Abstract

PURPOSE:To provide the method and apparatus for hot dipping for a metal strip capable of controlling the coating weight of hot dipping by a simplified method without using wiping nozzles. CONSTITUTION:At the time of performing hot dipping by applying plating to a metal strip 1 by the use of a hot dipping bath and then wiping the plating metal, the plated metal strip 1 after passed through the hot dipping bath is introduced into a closed space having a slit opening 2a capable of passing the metal strip and then this closed space is evacuated to allow a fluid to flow forcedly into the closed space via the above-mentioned slit opening 2a, by which the plating metal on the metal strip can be wiped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-dip plating method and hot-dip plating apparatus for metal strips.

[0002]

2. Description of the Related Art A number of hot-dip plating methods have been reported so far, in which a hood is provided so as to surround a metal strip continuously drawn from the surface of a hot-dip metal plating bath, as disclosed in, for example, JP-A-57-203764. And a method for controlling the oxygen concentration in the hood to suppress the generation of dross and to reduce the generation of metal vapor, and JP-A-62-37.
No. 359, a method for eliminating the influence of atmospheric gas in an alloying furnace provided above a plating apparatus, and JP-A-61-20.
As in 7559, a method of keeping the inside of the hood at a positive pressure and controlling the amount of plating adhered by a gas wiping nozzle at the top of the box to reduce the occurrence of splash, and JP-A-59-145775. First, there is a method in which molten salt is put in the hood to control the amount of plating adhered.

[0003]

However, in any of the above methods, a device having a function of controlling the amount of adhesion such as a gas wiping nozzle is required inside or outside the hood, and it is difficult to avoid complication of equipment. In particular, when a gas wiping nozzle or the like is provided in the hood, there is a problem that it is difficult to remove the nozzle when it is clogged due to splash or the like.

An object of the present invention is to solve the above-mentioned problems and to provide a hot-dip plating method and hot-dip coating apparatus for a metal strip which can control the amount of hot-dip deposits by a simple method without using a wiping nozzle. There is.

[0005]

According to a first aspect of the present invention to achieve the above object, when performing hot dipping by performing wiping of a plated metal after plating a metal strip in a hot dip bath, The plated metal band after passing through the hot dip plating bath is passed through a closed space having a slit opening so that the metal band can pass through, and the closed space is decompressed to force the fluid to flow from the slit opening into the closed space. A hot dip plating method is provided, which comprises wiping a plated metal on a strip.

Here, the fluid is preferably air and / or an inert gas.

According to the second aspect of the present invention, one open end is immersed in the hot dip plating bath, and the other has a slit opening through which the hot dip metal strip can pass, and a closed space is provided on the hot bath. There is provided a hot dip plating apparatus having a hood for limiting the pressure and a depressurizing means for depressurizing the closed space of the hood.

Here, it is preferable that the opening degree of the slit opening can be adjusted according to the plate width and the basis weight.

Further, it is preferable that a nozzle header for injecting a wiping fluid toward the slit opening is provided on the downstream side of the slit opening in the sheet passing direction.

The present invention will be described in more detail below with reference to the drawings.

FIG. 1 is a sectional view showing an example of a hot dipping apparatus for carrying out the present invention. 1 is a metal strip to be plated,
Reference numeral 9 denotes a plating bath for containing the molten metal 3, and 7 denotes a sink roll provided in the bath 9.

In the present invention, 2 is a hood which is a closed space for passing the plated metal strip 1a after passing through the hot dipping bath.

The metal strip 1 to be plated is introduced into a bath 9 containing a molten metal 3 to be plated, and then the hood 2 is vertically pulled up via a sink roll 7. At this time, the plated metal strip 1a is scraped and wiped so that the plated metal on the metal strip 1a has a desired thickness while passing through the hood 2 and being pulled out of the hood.

That is, in the present invention, the hood 2
Has one open end (lower part) immersed in a plating bath of the molten metal 3 and the other (upper part) has a slit opening through which the molten plated metal strip 1a can pass. Reference numeral 4 is a slit plate, and 2a is a slit opening. An exhaust pipe 8 is provided on the side wall of the hood 2.

In the present invention, while the metal strip 1 is being plated, it is evacuated by the exhaust means (not shown) through the exhaust pipe 8 to reduce the pressure in the hood 2 to a predetermined pressure, and the fluid is discharged from the slit opening 2a. Forced to flow into the hood 2. This enables wiping without using a conventional wiping device.

The fluid is preferably air and / or an inert gas. A non-oxidizing gas such as nitrogen is used as the inert gas.

The adjustment of the wiping is performed by the exhaust means and / or the slit opening, and the fluid flows as shown by an arrow in FIG. 1, and the molten metal 3 adhered to the plated metal strip 1a.
Receives a force corresponding to the flow velocity of the fluid in the direction opposite to the traveling direction of the metal strip 1a.

Here, it is preferable that the opening degree of the slit opening 2a can be adjusted according to the plate width of the metal strip 1 and the basis weight of the plated metal. An example of the hood part is shown in FIGS. In FIG. 2, the slit plate 4 is provided so as to be movable in the width direction of the slit plate (the direction of the arrow), whereby the opening 2a can be adjusted.

In FIG. 3, a pair of movable slit plates 4 are provided in the opening 2a, and a pair of movable plates 5 are provided at the upper ends of both ends of the opening 2a in the longitudinal direction. The flow of fluid can be regulated.

In FIG. 4, both longitudinal end portions of the slit plate 4 are tapered so that the opening degree of the opening 2a is increased at the plate edge portion. Can be increased.

By using the above-mentioned FIGS. 3 and 4 alone or in combination, it is possible to prevent an edge overcoat which causes an excessive amount of plating to adhere to the plate edge portion. Further, by making the slit plate 4 and the movable plate 5 movable as shown in FIGS. 2 to 4, the efficiency of the exhaust device can be improved.

Further, it is preferable that a nozzle header for injecting a wiping fluid toward the slit opening is provided on the downstream side of the slit opening as viewed in the plate passing direction. 5 and 6 show an example thereof, in which the nozzle header 6 is provided above the slit opening 2a provided in the upper portion of the hood 2, and the nozzle hole 6a for ejecting the fluid from the nozzle header 6 toward the opening 2a. Is provided. It is necessary to mount the nozzle header 6 so as not to disturb the movable state of the slit plate 4 and the movable plate 5. By providing such a nozzle header 6 and injecting an inert gas, the composition of the gas flowing into the hood 2 from the opening 2a is adjusted and the atmosphere in the hood 2 is controlled, whereby the dross in the hood 2 is controlled. It is possible to reduce the generated amount of the metal and to keep the plated metal of the plated metal strip 1a in the slit opening 2a in a non-oxidized state, improve the fluidity of the molten metal, and obtain a product of uniform and beautiful plating quality. Becomes

[0023]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, it is possible to control the deposition amount of hot-dip plating by a simple method without using a wiping nozzle, and reduce equipment cost and maintenance cost. At the same time, the clogging of the nozzle due to the adhesion of splash, which has been caused by the method of providing the wiping nozzle inside or outside the conventional hood, can be eliminated, and the production efficiency can be improved. Also, the atmosphere inside the hood can be easily controlled by simply attaching a nozzle header for injecting an inert gas to the outside of the hood.

[Brief description of drawings]

FIG. 1 is a sectional view of a hot dipping apparatus showing an embodiment of the present invention.

FIG. 2 is a plan view of the hood portion of the hot dipping apparatus showing an embodiment of the present invention.

FIG. 3 is a plan view showing another example of the hood portion.

FIG. 4 is a plan view showing another example of the hood portion.

FIG. 5 is a diagram of a hot dipping apparatus showing another embodiment of the present invention.

FIG. 6 is a plan view of a hood portion of a hot dipping apparatus showing another embodiment of the present invention.

[Explanation of symbols]

 1 Metal Band 1a Plated Metal Band 2 Hood 2a Slit Aperture 3 Molten Metal 4 Slit Plate 5 Movable Plate 6 Nozzle Header 6a Nozzle Hole 7 Sink Roll 8 Exhaust Pipe 9 Plating Bath

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Shinji Kawashima 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Chiba Works (72) Inventor Shin Arai 1 Kawasaki-cho, Chiba-shi Kawasaki Steel Co., Ltd. Company Chiba Steel Works

Claims (5)

[Claims] 1. A closed space having a slit opening for allowing the metal strip to pass through the plated metal strip after passing through the molten plating bath when wiping the plated metal in the hot dip plating bath to perform wiping of the plated metal. The hot dip plating method is characterized in that the closed space is decompressed and the fluid is forced to flow into the closed space through the slit openings to wipe the plating metal on the metal strip. 2. The hot dip plating method according to claim 1, wherein the fluid is air and / or an inert gas. 3. One open end is immersed in a hot dip bath,
On the other hand, a hot-dip plating apparatus having a hood that has a slit opening through which a hot-dip metal strip can pass and that defines a closed space on the plating bath, and a decompression unit that decompresses the closed space of the hood. 4. The hot dip plating apparatus according to claim 3, wherein the opening of the slit opening can be adjusted according to the plate width and the basis weight. 5. The hot dip plating apparatus according to claim 3, wherein a nozzle header for injecting a wiping fluid toward the slit opening is provided on the downstream side of the slit opening in the sheet passing direction.