JPH05320847A - Strip vibration prevention device for hot dip galvanizing line - Google Patents

Abstract

PURPOSE:To uniformlaize a plating metal deposition by suppressing the fluttering of a strip rising from a plating pot. CONSTITUTION:Static pressure nozzles P1, P2 and P3, P4 are respectively divided to lower and upper two stages on both surface sides of the strip X rising from the plating pot 1 and the gas ejection pressures from these nozzles are respectively controlled to generate a differential pressure in the static pressure generated on both surfaces. As a result, the vibration of the strip resing from the plating pot is prevented and the plating is uniformly executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip vibration preventing device for preventing vibration of a strip rising from a plating pot provided on a molten zinc plating line.

[0002]

2. Description of the Related Art In a hot-dip galvanizing line for producing galvanized iron sheets and alloyed hot-dip galvanized steel sheets, a gas jet from a gas wiping nozzle is applied to a strip that is pulled up after being immersed in the bath of a plating pot. Done,
The plating amount control is performed.

Among them, in the alloyed molten zinc plating line,
As shown in FIG. 4, after the deposition amount is controlled by the gas wiping nozzles 3a and 3b, the strip X comes into contact with the touch rolls 5a and 5b before entering the alloying furnace 4, and the flapping thereof is suppressed, and the plating deposition amount is reduced. The structure is adopted so as to be uniform.

[0004]

However, since the inside of the touch rolls 5a and 5b is water-cooled, when applied to the manufacture of a zinc iron plate, a whitish surface unevenness occurs,
It cannot be used in a plating line for producing the zinc-iron plate. Therefore, in such a line, the strips X that are pulled up rattle, and the amount of plating adhered becomes uneven.

On the other hand, even in the case of being used for an alloyed molten zinc plating line, if there is a Zn pickup or the like on the surface of the touch roll, it will be transferred to the plating surface and cause defects. When used on the same line, Zn powder is generated, and this Zn powder causes defects on the plating surface after the plating pot, causes equipment troubles such as earth leakage, and deteriorates the working environment. Will also be.

The present invention was devised in view of the above problems of the prior art, and it is an object of the present invention to provide a strip vibration preventive device capable of suppressing the flapping of the strip in a non-contact manner and making the plating amount uniform. is there.

[0007]

Therefore, the strip vibration preventing apparatus of the present invention is provided with static pressure nozzles for ejecting gas to both sides of the strip rising from the plating pot, and controls the ejection of gas from the nozzles. The basic feature is that a differential pressure is generated between the static pressures on both sides.

It is desirable that the pressure difference be 50 to ₂₀₀ mmH ₂ O between the both surfaces of the strip based on the experimental results described later.

Further, if the static pressure nozzle is further installed in a state of being divided into a plurality in the strip width direction, and the pressure of the gas ejected therefrom is controlled in the strip width direction, respectively.
The shape of the strip can be corrected.

The above-described structure of the present invention was created as a result of a study of a structure capable of suppressing the flapping of the strip by a non-contact method in place of the above-mentioned touch roll, and it was studied before the creation of the structure. The above-mentioned non-contact type configuration will be described first, and then the configuration of the present invention will be described in detail.

The structure considered as a non-contact type strip flapping prevention means uses static pressure nozzles 10a and 10b called so-called static pressure pads as shown in FIG. On the other hand, a gas is ejected from both sides to generate a static pressure in a place surrounded by the wall surface of the nozzle.

In the above structure, both sides of the strip X are held at the same pressure so that the cushion effect and the suction effect can be obtained against the flapping of the strip X. However, in reality, these nozzles 10a are used. , 10b, if a pressure change occurs in the blower that sends gas to the blower 10b, it will end up vibrating under the influence of the change.

In the structure of the present invention, in order to eliminate the influence of the pressure fluctuation of the blower, the both sides of the strip X are not kept at the same pressure, and a differential pressure is provided between the both sides. That is, the strip X is always pressed against the low pressure side, and even if the pressure of the blower fluctuates to some extent, the fluttering becomes very small, and the stable running of the strip X is realized.

[0014]

EXAMPLES The present inventors conducted the following experiments in an alloyed molten zinc plating line as shown in FIG.

In the same line, the strip X pulled up from the plating pot 1 via the sink roll 2 has its plating amount controlled by the gas jets of the gas wiping nozzles 3a and 3b, and further to the alloying furnace 4 thereabove. I will enter. In contrast to such a series of configurations, a configuration in which a touch roll (not shown) is installed between the wiping nozzles 3a and 3b and the alloying furnace 4 and a configuration similar to that shown in FIG. In some cases, the static pressure nozzles P ₁ , P ₂ , P ₃ , and P _{4 that} are provided have a structure in which two sets are installed vertically while facing each other on both sides of the strip X.

Then, the strip X having a size of 0.8 ^t × 1500 ^w (unit: mm) was plated at a line speed of 60 to 120 m / min. At the same time, the pressing amount of the touch roll is controlled within a range of 5 to 10 mm, while the gas ejection pressures of the static pressure nozzles P ₁ , P ₂ , P ₃ , and P ₄ are individually controlled, and stripping is performed by these gas ejections. The static pressure generated between X and X was adjusted in the range of 0 to 250 mmH ₂ O.

While making the above adjustments, the present inventors simultaneously examined the amount of vibration / flapping of the strip X and the amount of Zn powder generated, and obtained the results shown in Table 1 below.

[0018]

[Table 1]

In Table 1, the strip vibration / flapping amount judgment criteria are double circles (excellent) when the width of the flapping of the strip X at the static pressure nozzle is less than 3 mm, and the width is less than 5 mm. The case was judged as a single circle (good), the case where the width was less than 7 mm was a triangle (OK), and the case where the width was 7 mm or more was a X (no). Also, the criterion for determining the amount of Zn powder generated is evaluated by the amount of Zn powder deposited in a 10 × 10 cm ² tray installed in the vicinity of the gas wiping nozzles 3a, 3b (3 m from the touch roll part) in 1 hour. If there is no, the double circle (excellent), if the same amount is less than 10 mg is single circle (good), if the same amount is less than 30 mg is triangular (bad), and if the same amount is 30 mg or more, it is poor (poor). ).

From the table, in the case of No. 3 to No. 10 which are the examples of the present invention, the strip vibration / flapping amount and the Zn powder generation amount are both evaluated as single circle or double circle. And N
In the comparative example of o.2, the strip vibration and the amount of flapping are inferior due to the unevenness or triangle, and in the conventional examples of No. 11 to No. 15, Z is inferior.
n The amount of powder generated was inferior to triangle or cross.

Next, the inventors of the present invention installed the touch roll used in the previous embodiment in a molten zinc plating line for producing a zinc iron plate, and, instead, installed the static pressure nozzles P ₁ , P ₂ , P ₃ , P ₄ were installed, an experiment was conducted to examine the amount of plating applied in the strip X width direction, and the results shown in FIG. 2 were obtained. The plating conditions at this time are: strip size 0.8 ^t × 1500 ^w (unit mm), line speed 80 m /
min, the target amount of plating applied was 120 g / m ² .

It can be seen from the figure that the distribution of the amount of adhering is best (that is, uniformized) in the case where gas is ejected on both sides of the strip X and a pressure difference is produced on both sides at that time.

[0023]

According to the apparatus of the present invention described in detail above, the vibration fluttering of the strip rising from the plating pot is suppressed by the non-contact type structure, so that the amount of plating adhesion can be made uniform. Since it is a non-contact type, Z
n Generation of powder is suppressed, and defects such as blemishes are eliminated.
Therefore, the plated surface becomes beautiful, the occurrence of equipment troubles such as electric leakage is small, and the working environment is improved.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of the constitution of the present invention carried out in a plating treatment portion of an alloyed molten zinc plating line.

FIG. 2 is a graph showing a plating adhesion amount distribution in the strip width direction obtained in the second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a basic configuration of a static pressure nozzle.

FIG. 4 is a schematic diagram showing a conventional configuration of a plating treatment portion of an alloyed molten zinc plating line.

[Explanation of symbols]

1 Plating pot 2 Sink roll 3a, 3b Gas wiping nozzle 4 Alloying furnace 5a, 5b Touch roll 10a, 10b, P ₁ , P ₂ , P ₃ , P ₄ Static pressure nozzle X Strip

Claims (3)

[Claims] 1. A static pressure nozzle for ejecting gas is provided on both sides of a strip rising from a plating pot, respectively.
A strip vibration preventing device in a molten zinc plating line, characterized in that a gas injection from the nozzle is controlled to generate a differential pressure between static pressures on both surfaces thereof. 2. The melt vibration preventing device in the molten zinc plating line according to claim 1, wherein the differential pressure between the two surfaces of the strip is 50 to 200 mmH ₂ O. Strip vibration prevention device for zinc plating line. 3. A strip vibration preventing device in a molten zinc plating line according to claim 1, wherein:
3. The static pressure nozzle is installed in a state of being divided into a plurality in the strip width direction, and the pressure of the gas ejected from the static pressure nozzle is controlled in the strip width direction, respectively. An apparatus for preventing strip vibration in a molten zinc plating line according to the item.