JPH0617214A - Top dross removing device for continuous hot-dipping bath - Google Patents

Abstract

PURPOSE:To prevent the quality defect due to adhesion of dross by removing the top dross near a strip. CONSTITUTION:The rising part of the strip 8 is enclosed with an immersion trough 10 formed into a trough shape on the inside surface side of the bottom end and is immersed under the bath surface. A hot-dipping metal is then discharged via a suction pipe 4 from the bottom of this immersion trough 10, by that, the top dross 7 floating near the strip 8 is expelled without stagnation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for removing top dross generated in a continuous molten metal plating bath.

[0002]

2. Description of the Related Art As shown in FIG. 4, a strip 8 exiting an annealing furnace 15 passes through a snout 11 and is then immersed in a hot-dip metal 13 stored in a plating tank 12 to form a sink roll.
It is turned by 14 and stands upright. The vertically rising strip 8 is wiped by a gas blown from a pair of wiping nozzles 9 arranged on the bath surface of the hot-dip metal 13 so that a predetermined coating weight is obtained.

In the case of a hot dip galvanizing bath, for example, in the case of a hot dip galvanizing bath, hot dip zinc (Zn) is leached from ZnO produced by oxidation of the hot dip galvanizing bath and strip 8 dipped in the bath. There is a top dross 7 consisting of Fe ₂ Al ₅ formed by the reaction of iron (Fe) with Al present in the bath. If the top dross 7 is not removed, it adheres to the strip 8 and deteriorates the plating quality of the strip, so conventionally, the top dross was manually scraped up and removed using a tadpole.

Manual top dross scraping is a work in a high-heat atmosphere, which puts a heavy load on the operator and poses a safety problem. That is, the bath surface of the plating tank is about 4 to 5
Because it is as wide as m square and the bath equipment is arranged in a complicated way,
It is difficult to completely scrape off the top dross because the top dross is scratched with a long tadpole passing through the gap, and the top dross often deteriorates the plating quality.

[0005] Achieved a realization to mechanize the removal of top dross.
Japanese Patent Laid-Open No. 55-155864 discloses that a weir is formed in the plating metal carry-out portion on the surface of the molten metal bath, and the bath cleaning device is linked to the metal plating bath in the weir. However, there is a problem that a sufficient bath cleaning effect cannot be obtained by simply drawing out and circulating the molten metal by surrounding the metal carry-out portion with a weir.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus for removing top dross generated in a continuous hot dip metal plating bath, which can solve the problems of the prior art. .

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention investigated the flow state of the plating metal in the portion where the strip rises from the bath surface of the molten metal plating bath and the behavior of top dross floating on the bath surface. The present invention has been achieved as a result of repeated studies on means for effectively collecting the above, and the gist of the present invention is as follows.

According to the present invention, a bottom wall and an inner wall are formed by folding back a lower end of an outer wall which surrounds a vertically rising strip through a sink roll immersed in a molten metal plating bath in the vicinity of the bath surface. The immersed trough is arranged such that the outer wall of the immersed trough extends from above the bath surface to below the bath surface, and the bottom wall and the inner wall are immersed below the bath surface, and the top dross is placed at the bottom of the immersion trough. A top dross removing device for a coupled molten metal plating bath, characterized in that a discharge port for sucking the hot-dip metal and discharging it to the outside of the immersion trough is provided, and a discharge pipe having a pumping means is connected to the discharge port. Is.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure and operation of the apparatus of the present invention will be described in detail below with reference to an embodiment. In the apparatus of the present invention, the strip 8 exiting the annealing furnace 15 in FIG. 1 passes through the snout 11 and is then immersed in the hot-dip galvanized metal (here, zinc) 13 stored in the plating tank 12, and the sink roll 14 It turns around and stands upright. Strip with zinc 8
As in the prior art, the gas is wiped by a gas blown from a pair of wiping nozzles 9 arranged on the bath surface so that a predetermined coating weight is obtained.

In the apparatus of the present invention, as shown in FIGS. 1 and 2, a sink roll 14 immersed in a hot dip galvanizing bath 13 is used.
A bottom wall 3 and an inner side wall 2 are formed by folding back a lower end of an outer wall 1 that surrounds a strip 8 that rises vertically through a bath surface in the vicinity of the bath surface. The bottom wall 3 and the inner wall 2 are arranged so as to extend under the bath surface and be immersed under the bath surface.

The bottom wall 3 of the immersion trough 10 is provided with a discharge port 16 for discharging the hot-dip zinc along with the top dross to the outside of the immersion trough 10, and the discharge port 16 is connected to a suction pipe 4 equipped with a pump 5. The discharge end of the discharge pipe 6 connected to the outlet side of the pump 5 is immersed in the galvanized zinc 13 inside the plating tank 12 outside the immersion trough 10. Next, the operation of the present invention will be described. When removing the top dross 7 floating near the strip 8 on the hot-dip galvanized zinc 13 stored in the plating tank 12, when the pump 5 is started, the inside of the dip trough 10 is removed. The hot-dip galvanized metal 13 is sucked into the suction pipe 4 from the discharge port 16 provided in the bottom wall 3, and is discharged from the discharge pipe 6 through the pump 5 into the plating tank 12 outside the immersion trough 10.

That is, when the pump 5 is started, the bath surface of the hot-dip galvanized zinc 13 surrounded by the immersion trough 10 composed of the outer wall 1, the inner wall 2 and the bottom wall 3 as shown in FIG. Since the top dross 7 is guided toward the immersion trough 10 along with the hot-dip galvanized zinc 13 over the upper end of the inner wall 2, it is discharged through the above-mentioned path.

In particular, since the surface of the strip 8 has a downward gas flow injected from the wiping nozzle 9 and a downward flow of excess wiped molten zinc, it is directed to the immersion trough 10 by the activation of the pump 5 described above. Since the moving force of the bath surface is increased, the effect of removing the top dross 7 is further enhanced. The outer wall 1 of the immersion trough 10 prevents dross on the outer bath surface from flowing into the bath surface surrounded by the immersion trough 10, and the inner wall 2 has its upper edge below the bath surface level. Since the hot dip zinc 13 is discharged by the pump 5, a gradient is formed on the bath surface surrounded by the outer wall 1, so that the top dross existing in the vicinity of the bath surface is formed. It is effective in eliminating 7.

In FIG. 2, the immersion trough 10 is an embodiment arranged so as to surround the steel of the strip 8,
In some cases, the effect of removing the top dross is recognized even when the immersion trough is arranged only in the portion facing the front and back surfaces of the strip 8 and not in the portion facing the edge of the strip 8. Next, specific examples of the present invention will be described.

Using the apparatus of FIG. 1, 0.7 mm thick × 1400 mm
The width steel strip was subjected to hot dip galvanizing and the amount of dross deposited was examined. Plating conditions are line speed 120 mpm and basis weight 90 g / m
^{2. The} Al concentration in the bath was 0.15% by weight, and the plating bath temperature was 470 ° C. As a result, the amount of deposited dross was 20 to 50 pieces / m ² in the conventional apparatus, but was 0 piece / m ² in the apparatus of the present invention.

[0016]

As described above, according to the apparatus of the present invention, the top dross floating on the hot-dip metal in the immersion trough surrounding the strip bath surface can be completely removed, so that the strip Poor plating quality due to dross adhesion can be prevented.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a schematic vertical section of an apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view showing an arrow AA of FIG.

FIG. 3 is an explanatory view showing the operation of the device of the present invention.

FIG. 4 is an explanatory diagram showing a schematic cross-section of an apparatus according to a conventional example.

[Explanation of symbols]

 1 Outer Wall 2 Inner Wall 3 Bottom Wall 4 Suction Pipe 5 Pump 6 Discharge Pipe 7 Top Dross 8 Strip 9 Wiping Nozzle 10 Immersion Trough 11 Snout 12 Plating Tank 13 Hot-dip Metal (Zinc) 14 Sink Roll 15 Annealing Furnace 16 Discharge Port

Claims (1)

[Claims] 1. A dip in which a bottom wall and an inner wall are formed by folding back a lower end of an outer wall, which surrounds a vertically rising strip through a sink roll immersed in a molten metal plating bath in the vicinity of the bath surface, inwardly. The trough is arranged such that the outer wall of the immersion trough extends from above the bath surface to below the bath surface, and the bottom wall and the inner wall are immersed from above the bath surface to below the bath surface, and at the bottom of this immersion trough. A top dross of a continuous molten metal plating bath, characterized in that a discharge port for sucking the molten plated metal together with the top dross and discharging it out of the immersion trough is provided, and a suction pipe equipped with a pumping means is connected to the discharge port. Removal device.