JPH06346211A - High-speed hot dip coating equipment - Google Patents

Abstract

(57) [Summary] [Purpose] A gas injection slit nozzle was installed in the width direction of the steel strip between the gas wiping nozzle that blows gas in the width direction of the steel strip pulled from the molten metal plating bath and the plating bath surface. To obtain a high-speed hot-dip galvanizing machine. [Constitution] In a hot dip coating apparatus having gas wiping for controlling a basis weight of a continuous metal plate pulled up from a hot dip bath by gas wiping to a predetermined amount,
A slit nozzle having a slit-shaped gas injection hole was provided over the entire width of the continuous metal plate pulled up between the gas wiping nozzle and the plating bath surface. Spray gas is blocked from being blown from the gas wiping nozzle onto the bath surface, and even if a large amount of wiping gas is blown onto a continuous metal plate under high-speed striping conditions, splashing due to tapping of the wiping gas on the bath surface also occurs. Therefore, stable continuous high-speed hot-dip galvanizing becomes possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high speed hot dip galvanizing apparatus applied to hot dip galvanizing of strip steel sheets, for example.

[0002]

2. Description of the Related Art A conventional hot-dip galvanizing machine was used in
As stated on pages 10 and 11 of "Advances in Surface Treatment Technology and Future Trends" issued by The Iron and Steel Institute of Japan
Gas is sprayed from the gas wiping to the steel strip pulled up from the metal hot dip plating bath to control the basis weight to a predetermined amount.

However, as the steel strip passing speed increases, the amount of molten metal pulled up from the plating bath increases, and even when controlling the basis weight to a predetermined basis weight, the amount of wiping gas sprayed from the gas wiping nozzle is inevitable. You also need to do a lot.

However, when the amount of gas of the wiping nozzle 1 sprayed on the plating surface is increased by increasing the line speed, as shown in FIG. 3, the wiping gas 4 sprayed on the steel strip strikes the bath surface and splashes from the bath surface. 5, the generated splash adheres to the surface of the steel strip after plating and deteriorates the plating appearance quality, or adheres to the gas wiping nozzle 1 to cause nozzle clogging, which makes continuous operation impossible. The problem arises.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of splash adhesion due to gas wiping, nozzle clogging, etc., which accompanies an increase in the adhered plating layer due to an increase in the pulling speed of a continuous metal plate pulled from a hot dip bath. It is to provide an effective means for solving the problem.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to a hot dip coating apparatus having a gas wiping for controlling a basis weight of a continuous metal plate pulled up from a hot dip bath by gas wiping to a predetermined amount. It is a high-speed hot dip plating apparatus provided with a slit nozzle having slit-shaped gas injection holes over the entire width of a continuous metal plate pulled up between bath surfaces.

[0007]

[Function] By providing the gas jet slit nozzle between the gas wiping nozzle and the plating bath surface over the entire width of the continuous metal plate to be pulled up, the spraying of the jetted gas from the gas wiping nozzle to the gas bath surface is blocked. ,
Even if a large amount of wiping gas is sprayed on a continuous metal plate under high-speed stripping conditions, splashing due to tapping of the wiping gas on the bath surface does not occur, and stable continuous high-speed hot-dip galvanizing is possible.

[0008]

EXAMPLE An example in which the present invention is applied to hot-dip galvanizing of steel strip will be described.

Each of the attached drawings shows an embodiment of the present invention.
1 is a view seen from the thickness direction of the steel strip.
Shows a view looking towards the surface of the steel strip.

In these drawings, reference numeral 1 denotes a gas wiping nozzle for wiping the basis weight of the molten metal plated on the steel strip S pulled up from the zinc hot dipping bath M so that the basis weight becomes a predetermined basis weight. As shown in FIG. 2, it has a structure of slit nozzles arranged over the entire width of the pulled steel strip S. Reference numeral 2 denotes a gas injection slit nozzle arranged below the gas wiping nozzle 1, which is a slit-shaped opening 3 arranged over the entire width of the pulled steel strip S and substantially horizontally with respect to the plating bath M. On the surface of the steel strip S.

From this gas injection slit nozzle 2, 20
By blowing the N ₂ gas a heated to about 0 ° C. and pressurized to about 0.005 to 0.01 MPa onto the surface of the steel strip S, the N ₂ gas a is blown downward into the jet gas flow b from the gas wiping nozzle 1. The directed gas is prevented from generating splash due to directly hitting the zinc hot-dip galvanizing bath M.

A plate width of 1200 mm and a basis weight of molten zinc of 55
The limit line speed of splash generation due to tapping on the bath surface for controlling g / m ^{2 on} one side was changed from 120 m / min to 150 m / min by the hot dipping apparatus of the present invention, and the line speed could be increased.

[0013]

The present invention has the following effects.

(1) Splash is not generated by hitting the bath surface by gas wiping, the continuous metal pulling rate from the hot dip plating bath can be increased, and the line speed can be increased.

(2) Since the generation of splash due to tapping on the bath surface is eliminated, there is no splash attached to the surface of the steel strip after plating, and the production yield of plated steel sheet is improved.

(3) Nozzle clogging due to splash adhesion is eliminated, maintenance of nozzles during operation is eliminated, and workability is improved.

[Brief description of drawings]

FIG. 1 is a view seen from a thickness direction of a plate material in an example of the present invention.

FIG. 2 is a view of FIG. 1 viewed from a surface direction of a plate material.

FIG. 3 shows a plate material in a conventional hot dipping apparatus.

[Explanation of symbols]

 1 Gas Wiping Nozzle 2 Gas Injection Slit Nozzle 3 Slit-shaped Opening 4 Wiping Gas 5 Splash M Zinc Galvanizing Bath S Steel Strip

Claims (1)

[Claims] 1. A hot dipping apparatus having gas wiping for controlling a basis weight of a continuous metal plate pulled up from a hot dipping bath by gas wiping, to be continuously pulled up between a gas wiping nozzle and a bath surface. A high-speed hot dip plating apparatus provided with a slit nozzle having slit-shaped gas injection holes over the entire width of a metal plate.