JP3166300B2 - Strip vibration prevention device in hot dip galvanizing line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for preventing a strip from vibrating from a plating pot provided in a hot-dip galvanizing line.

[0002]

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

[0003] Among them, in the galvannealing line,
As shown in FIG. 4, after controlling the amount of deposition 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. Is adopted so as to make the temperature uniform.

[0004]

However, since the insides of the touch rolls 5a and 5b are water-cooled, they cause whitish surface unevenness when applied to the production of a galvanized sheet.
It cannot be used in a plating line for producing the galvanized sheet. Therefore, in such a line, the strip X that is pulled up flaps, and the amount of plating applied becomes uneven.

[0005] On the other hand, even when used in an alloyed hot-dip galvanizing line, if there is a Zn pick-up or the like on the surface of the touch roll, it is transferred to the surface of the galvanized coating, causing a flaw. In addition, when used in the same line, Zn powder is generated, and this Zn powder may cause a flaw to be formed on the plating surface after the plating pot, or may cause equipment troubles such as electric leakage or deteriorate the working environment. Also.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a strip vibration preventing apparatus which can suppress the flapping of a strip in a non-contact manner and make the amount of plating applied uniform. is there.

[0007]

SUMMARY OF THE INVENTION For this reason, the present invention has been described.
Of Strip Vibration in Hot Dip Galvanizing Line
On each side of the strip rising from the plating pot
A static pressure nozzle that can blow out gas
Provided facing each other with the lip in between, and
Control the gas ejection and set the static pressure between the two sides to 50-200mm
It is characterized in that a differential pressure of H ₂ O is generated.

Here, the differential pressure of the static pressure between the two surfaces is 50 to 200 mm.
H ₂ O is defined as the range of the strip within this range.
Flicking can be effectively prevented and plating adhesion is good.
What is good is found from the experimental results described below
Based on

[0009] Further , they are arranged to face each other across the strip.
Static nozzles are connected vertically in the vertical direction,
By controlling the gas ejection of each nozzle to be arranged, the strip
Static pressure between the front and back surfaces, which creates a pressure difference between the two surfaces
May be reversed in the vertical direction.
If the static pressure nozzle is further divided into a plurality of sections in the strip width direction and the pressure of the gas ejected therefrom is controlled in the strip width direction, the shape of the strip can be corrected.

The structure of the present invention as described above was created as a result of studying a structure capable of suppressing flapping of a strip in a non-contact manner in place of the above-mentioned touch roll. The above described 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 or the like as shown in FIG. On the other hand, gas is ejected from both sides to generate a static pressure in a portion surrounded by the wall surface of the nozzle.

In the above configuration, both sides of the strip X are kept at the same pressure so that a cushion effect and a suction effect can be obtained against the flapping of the strip X. However, in reality, these nozzles 10a , 10b, the pressure changes in the blower that sends the gas, the vibrations are eventually generated 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 surfaces of the strip X are stopped from being kept at the same pressure, and a differential pressure is provided between them from the beginning. That is, the strip X is always pressed to the low pressure side, and even if the blower pressure fluctuates to some extent, the flapping becomes very small, and the stable running of the strip X is realized.

[0014]

EXAMPLES The present inventors conducted the following experiments on a galvannealed galvanizing line as shown in FIG.

In the same line, the amount of plating of the strip X pulled up from the plating pot 1 via the sink roll 2 is controlled by the gas jets of the gas wiping nozzles 3a and 3b. You will enter. In contrast to such a series of configurations, a configuration in which a touch roll (not shown) is provided between the wiping nozzles 3a and 3b and the alloying furnace 4 and a configuration similar to that shown in FIG. There may be a configuration in which two sets of upper and lower static pressure nozzles P ₁ , P ₂ , P ₃ , and P ₄ are provided while facing each other on both sides of the strip X.

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

While making the above adjustments, the present inventors simultaneously examined the vibration / fluttering amount 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 criterion for determining the amount of strip vibration and flapping is double circle (excellent) when the flapping width of the strip X at the static pressure nozzle portion is less than 3 mm, and when the width is less than 5 mm. The case was judged as a single circle (good), the case with the width less than 7 mm as a triangle (acceptable), and the case with the same width of 7 mm or more as a cross (impossible). The criterion for the amount of Zn powder generated was evaluated based on the amount of Zn powder deposited on a 10 × 10 cm ² tray installed in the vicinity of the gas wiping nozzles 3a and 3b (3 m from the touch roll part) in one hour. If there is no double circle (excellent), if the same amount is less than 10 mg, single circle (good), if the same amount is less than 30 mg, triangle (poor), if the same amount is 30 mg or more, cross (poor) ).

From the table, in the case of No. 3 to No. 10, which are examples of the present invention, the evaluation of the single circle to double circle was made for the strip vibration / fluttering amount and the amount of Zn powder generated, whereas the case of No. 1 And N
In the comparative example of o.2, the strip vibration and the amount of flapping were inferior in the cross or the triangle, and in the conventional examples of No. 11 to No. 15, Z
n The amount of generated powder was inferior to triangle or cross.

Next, the present inventors consider the case where the touch roll used in the previous embodiment is installed in a hot-dip galvanizing line for producing a galvanized sheet, and instead, the static pressure nozzles P ₁ , P ₂ , P _3. performs experiments to examine the plating deposition amount of the strip X width direction in the case where P ₄ is installed, with the results shown in FIG. The plating conditions at this time were as follows: strip size 0.8 ^t × 1500 ^w (unit: mm), line speed 80 m /
min, and the target plating weight was 120 g / m ² .

From the figure, it can be seen that the gas distribution is best (ie, uniform) in the case of the present invention in which gas is ejected on both sides of the strip X and a differential pressure is generated on both sides at that time.

[0023]

According to the apparatus of the present invention described in detail above, the flapping of the strip rising from the plating pot is suppressed by the non-contact type configuration, so that the plating adhesion amount can be made uniform. Also, since it is a non-contact type, Z
The generation of n-powder is suppressed, and the occurrence of dents and the like is also eliminated.
Therefore, the plating surface becomes beautiful, the occurrence of equipment troubles such as electric leakage is reduced, and the working environment is improved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of the configuration of the present invention implemented in a galvanizing portion of an alloyed galvanizing line.

FIG. 2 is a graph showing a plating adhesion amount distribution in a strip width direction obtained in a 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 view showing a conventional configuration of a plating portion of an alloyed hot-dip galvanizing 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 nozzle X Strip

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C23C 2/00-2/40

Claims (3)

(57) [Claims] [Claim 1] coming risen from the plating pot strip
Static pressure nozzle that can blow out gas to each side of the pump
The nozzles are provided to face each other with the strip interposed therebetween, and the gas ejection from each of the opposed nozzles is controlled so that the static pressure between both surfaces thereof is reduced .
An apparatus for preventing strip vibration in a hot dip galvanizing line, wherein a differential pressure of 50 to ₂₀₀ mmH2O is generated. 2. It is arranged to oppose each other across a strip.
Static pressure nozzles are connected vertically and arranged vertically
Control the gas ejection from each nozzle to
Strong static pressure generated between the front and back surfaces, causing a pressure difference between the surfaces
Claims characterized by reversing the weak relationship in the vertical direction
Item 1 Prevention of strip vibration in hot-dip galvanizing line
apparatus. 3. Leave installed the static pressure nozzle in a state that the plurality of divided strip width direction, claim 1 or the pressure of the gas ejected therefrom, characterized in that each control in the strip width direction An apparatus for preventing strip vibration in a hot dip galvanizing line according to claim 2 .