JPH06158253A - Continuous hot dip galvanizing apparatus - Google Patents

Abstract

PURPOSE:To restrain stickness of bottom dross to a steel sheet by arranging a porous plate restraining the flow in a bath between a sink roll and the bottom part of a pot. CONSTITUTION:By arranging the porous plate 6 between the sink roll 2 and the bottom part of the pot in a zinc bath vessel, the flow in the bath generated by rotating the sink roll 2 and shifting the galvanized steel sheet 4 in the bath is shut off with the porous plate 6 to restrain the raise-up of the bottom dross 7. At the same time, as a part of the vigorous stream between the sink roll 2 and the porous plate 6 is flowed out from the holes 5 in the porous plate 6 and shifted to the lower part of the porous plate 6, the bottom dross 7 is not so much deposited at the lower part of the porous plate 6 that the raise-up of the bottom dross 7 generates. Then, the hole 5 arranged in the porous plate 6 is made to be about 10-50mm the hole diameter and the total area of the holes 5 is made to be in the range of 5-40% of the porous plate area. By this method, the galvanization having a little adhesion of the bottom dross is executed for a long term.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous hot dip galvanizing apparatus for suppressing adhesion of bottom dross to a steel plate.

[0002]

2. Description of the Related Art It is known that, in a continuous hot-dip galvanizing process, bottom dross, which is an impurity, adheres to a plated steel sheet in a zinc bath and impairs the appearance of the plated steel sheet. Conventionally, for this bottom dross, for example, Japanese Patent Laid-Open No. 3-479.
As disclosed in Japanese Patent Laid-Open No. 56 and Japanese Patent Application Laid-Open No. 3-277754, it is reported that a flow straightening plate is installed between the sink roll and the bottom of the pot for winding up the bottom dross in the continuous hot dip galvanizing process. ing.

[0003]

When a straightening vane is installed between the sink roll and the bottom of the pot to block the flow, at the beginning of the straightening vane installation, the bottom dross is prevented from rolling up.
There is a problem that bottom dross gradually accumulates in the lower part of the straightening vane where the bath flow is shielded, the bottom dross begins to roll up due to the accompanying flow near the straightening vane, and eventually the bottom dross adheres to the plated steel sheet and impairs the appearance.

[0004]

The present invention has been made in view of the above problems and is characterized in that a perforated plate for controlling the flow in the bath is installed between the sink roll in the zinc bath and the bottom of the pot. The subject is a continuous hot-dip galvanizing device. The pore area of the perforated plate is 5% to 4% of the perforated plate area.
It is desirable to set it within the range of 0%.

[0005]

[Function] By installing the perforated plate between the sink roll and the bottom of the pot, the flow in the bath caused by the rotation of the sink roll and the movement of the plated steel sheet in the bath is shielded by the perforated plate, and the winding of bottom dross is suppressed. To be done. At the same time, a part of the violent flow between the sink roll and the perforated plate flows out from the holes of the perforated plate and moves to the lower part of the perforated plate, so that the bottom dross does not accumulate to the bottom of the perforated plate to the extent that the bottom dross winds up. . The hole provided in the perforated plate has a hole diameter of 1
0 to 50 mm, the total area of the holes is 5 to 40 of the perforated plate area.
By configuring in the range of%, as shown in FIG. 2, it is possible to reduce the dross flaw by suppressing the bottom dross roll-up and the deposition amount of the lower portion of the perforated plate. Total area of holes is 5
If it is less than 40%, the effect of suppressing the amount of dross deposited on the lower portion of the porous plate is insufficient, and if it exceeds 40%, the effect of suppressing the dross winding is insufficient.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. In the lab test, as shown in Figure 1, Syncroll 2
A perforated plate 6 having a hole diameter of 20 mm and a total hole area of 10% of the surface area of the perforated plate was placed in the middle of the bath bottom, and the steel plate 4 was passed through. At this time, the flow in the bath is shielded by the perforated plate 6, curling up of the bottom dross 7 is suppressed, and the holes 5 of the perforated plate are prevented.
From this, a part of the violent flow between the sink roll 2 and the perforated plate 6 flowed out, and a slight flow was generated in the lower part of the perforated plate 6. Therefore, the bottom dross 7 deposited on the entire bath bottom had a deposition depth of about 30 mm, and the bottom dross deposited on the lower portion of the porous plate 5 was not deposited more than 40 mm.

[0007]

As described above, according to the present invention, rolling up of bottom dross and the amount of bottom dross accumulated at the bottom of the bath can be suppressed, and therefore hot dip galvanization with little adhesion of bottom dross can be performed for a long period of time.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention,

FIG. 2 is a diagram illustrating an implementation result of the present invention.

[Explanation of symbols]

 1 molten zinc bath 2 sink roll 3 snout 4 plated steel plate 5 holes in perforated plate 6 perforated plate 7 bottom dross

Claims (2)

[Claims] 1. A continuous hot dip galvanizing apparatus comprising a perforated plate for suppressing flow in the bath between a sink roll in the zinc bath and the bottom of the pot. 2. The continuous hot dip galvanizing apparatus according to claim 1, wherein the total area of the holes of the perforated plate is within the range of 5% to 40% with respect to the area of the perforated plate.