JPH0261048A - Seal box for molten metal plating or coating - Google Patents

Abstract

PURPOSE:To block the intrusion of air, etc., and to prevent the oxidation of a plated surface by providing an injection nozzle for sending a gaseous sealant from the inside to the outside in a seal box enclosing a wiping nozzle and a plated band metal. CONSTITUTION:A wiping nozzle 3 for injecting a gas onto a surface of a band metal passing through a molten metal tank or a coating soln. tank and then traveling upward and a seal box 4 enclosing the plated band metal 1, with the lower part dipping in the tank, and having an opening 5 at the upper part are provided. Nozzles 6 for injecting the gaseous sealant are provided in the seal box 4, and the gaseous sealant is injected onto both ends of the opening 5 in the cross direction through which the band metal 1 passes toward the downstream side of the traveling band metal 1. At this time, the distance L between the nozzles 6 is controlled so that the flow of the gas, which is injected from the wiping nozzle 3, allowed to collide with the band metal 1, and then flows along the band metal, is not blocked. By this method, the intrusion of oxygen into the seal box 4 is prevented, and a high-quality and beautiful plated surface or coated surface is obtained.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention uses gas wiping to remove excess plating solution and paint used in hot-dip metal plating of metal strips or coating with various paints to reduce the amount of adhesion, that is, the thickness of the coating film. The present invention relates to a seal box surrounding a gas wiping device that adjusts the gas wiping device.

<Prior Art> Conventionally, rope strips, for example f! J Xl! A so-called gas wiping method is known in which the surface weight of the steel strip is controlled by blowing high-pressure gas onto the surface of the steel strip after passing through a zinc bath.

At this time, in order to prevent oxidation of the molten zinc, the wiping nozzle and the plated metal strip are surrounded, the lower end of which is immersed in the hot-dip metal bath, and the upper part is provided with an opening through which the plated metal strip passes. Providing a seal box with
It is publicly known from JP-A-62154 and the like.

However, atmospheric gas (oxygen) from outside the seal box enters through the upper opening through which the metal band passes, making it impossible to fill the seal box with a sufficient concentration of inert gas, which is the purpose of preventing plating metal. Oxidation prevention is not sufficient.

<Problems to be Solved by the Invention> An object of the present invention is to prevent external air from entering the seal box when adjusting the amount of molten metal plating or paint deposited using a gas wiping nozzle inside the seal box. Our goal is to provide a sealed box.

Means for Solving the Problem> In order to understand the inflow route of oxygen entering the seal box, the present inventors conducted various experiments and observations, and as a result, as shown in Fig. 4, It was found that the metal band was flowing from near both ends in the width direction of the seal box opening through which the metal strip passed.

As a result, the present invention has been achieved, that is, the present invention has a gas wiping nozzle that injects gas onto a metal band surface that passes through a molten metal bath or a paint liquid bath, and which includes a gas wiping nozzle and a coated The coated metal is placed in a seal box surrounding the metal strip, the lower end of which is immersed in the molten metal tank or the BGI paint liquid tank, and the upper end of which has an opening through which the coated metal strip passes. A method for molten metal plating or painting, characterized in that a seal gas jetting nozzle is provided so that the seal gas flows from the inside of the seal box to the outside near both ends in the width direction of the opening through which the metal strip passes through. It is a sealed box.

<For production> The seal box of the present invention will be explained using the drawings.

FIG. 1 shows an example of application of the present invention in a case where the width of the metal strip, which is the material to be treated, is approximately constant. Nozzles 6 are provided at both ends in the plate width direction of the opening through which the metal strip 1 passes after plating to eject seal gas toward the downstream side in the traveling direction of the metal strip, and the inert gas filling the seal box is removed. It was made to erupt. At the center of the plate width, the wiping gas ejected toward the front and back surfaces to wipe away the excess plating solution on the front and back surfaces collides with the gold i-band and flows along the metal strip in large quantities and at high speed, resulting in a large amount of atmospheric gas. No break-in occurs. However, the seal box opening 5 through which the metal strip 1 after plating passes is slightly wider than the width of the metal strip, and the flow of wiping gas after colliding with the metal strip is small and weak at the edges of the strip width. However, by ejecting seal gas from the nozzle 6 of the present invention, it is possible to maintain a positive pressure and prevent atmospheric gas from entering. .Here, the broken line arrow C indicates the flow of the sealing gas ejected from the nozzle 6.

Figures 2 and 3 show an example of application of the present invention when the width of the metal strip l to be treated varies considerably. Figure 2 is a sectional view showing the front side, and Figure 3 is a side view thereof. FIG.

3 is a nozzle for wiping the plating solution on the front and back sides of gold WA strip 1, and 4 is a seal box.

6 is a length that is opposite to the metal band l at both ends in the plate width direction of the opening through which the metal band passes after plating, and is longer than the length of the plate width variation of the material to be treated plus the amount of meandering that occurs when the metal band runs. The nozzle 6 has a sealing gas ejection port having a large diameter, and the sealing gas is ejected toward the downstream side in the metal band traveling direction.

Note that the flow of the seal gas is shown by the broken line C in FIGS. 2 and 3.

It is desirable to arrange the nozzles 6 at intervals so as not to obstruct the gas flow (A in Fig. 3) that is ejected from the wiping nozzle 3 and follows it after colliding with the metal band. The outlet may be a rectangular slit gap or may be provided with spouting ports intermittently.

Next, using a seal box equipped with the nozzle of the present invention, the sealing effect was tested under the following conditions, and the oxygen concentration was measured.

Note that H1 gas was used as the wiping gas and sealing gas.

As a result, Figure 3 is a side sectional view of the acid in the seal box, and Figure 4 is a schematic diagram of the path of atmospheric gas intrusion into the conventional seal box.

Therefore, it is clear that the sealing effect of the sealing gas injection is effective in suppressing oxidation of plated metal and generation of dross, and is also effective in painting processing.

<Effects of the invention> It is possible to effectively prevent oxygen from entering the seal box, and it is possible to fill the seal box with a high concentration of inert gas, thereby reducing the deterioration of the plating surface properties due to oxidation immediately after wiping. It is possible to prevent this, and to obtain a high-quality and beautiful plated or painted surface. Also, the generation of dross is reduced, the yield of zinc, etc. can be improved, and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the seal box of the present invention, FIG. 2 is a front sectional view of the seal box of the present invention, 1st...metal band, 3... wiping nozzle, 5... opening,

Claims (1)

[Claims] It has a gas wiping nozzle that injects gas onto the surface of the metal strip that passes through the molten metal tank or the paint liquid tank, surrounds the gas wiping nozzle and the coated metal strip, and has its lower end connected to the molten metal tank. Alternatively, in a seal box that is immersed in the paint liquid tank and has an opening at the upper end through which the coated metal strip passes, both ends in the width direction of the opening through which the coated metal strip passes. A seal box for molten metal plating or painting, characterized in that a seal gas jetting nozzle is provided in the vicinity so that seal gas flows from the inside of the seal box to the outside.