JPS5855069A - Gas wiping device for liquid coated on steel strip - Google Patents

Abstract

PURPOSE:To prevent contamination of nozzles by providing enclosures having no relations with the traveling of a steel strip to be wiped of the liquid coated thereon by gases in the positions of the line where said steel strip travels and further providing gas wiping nozzles in the upper parts of the enclosures. CONSTITUTION:Side walls 4 and ceiling walls 5 which are enclosures having no relations with the traveling of a steel strip to be wiped of the liquid coated thereon by gases are provided in the positions of the line where said steel strip travels, and gas wiping nozzles 7, 7' which are sharp in tip angles are provided in the upper parts of said enclosures. Baffles 15, 15' for taking in of secondary air 14, 14' are provided below the nozzles 7, 7'. The tips of the baffles 15, 15' are rounded downward in the positions near the tips of the nozzles 7, 7'. Partition plates 16, 16' are mounted in the lower parts of the baffles 15, 15' and semicircular baffles 17, 17' for separating air and mist-like splashers are mounted in the lower part of the plates 16, 16'.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for continuously treating the surface of a steel strip by gas wiping the excess amount when dusting or coating a treatment liquid or paint (hereinafter referred to as coating liquid). No. 40 relating to the improvement of a device for measuring the amount of sand film adhesion,
For fast-drying coating liquids that have various physical properties such as high viscosity, low density, and low interfacial tension, it is recommended that an air suction mechanism be installed to suck the air ejected from the secondary air intake baffle and gas wiping nozzle. Nozzle contamination caused by scrubbing even on high-speed lines of 200 w/II or higher.
The purpose is to improve the L1 operation rate as well as improve product quality.

Conventionally, the amount of skin deposited when coating or painting the surface of copper strips) a) The reel drawing method was adopted as the west method, but with the establishment of line speed increase technology in nearby cities. Therefore, it is technically difficult to adopt the roll drawing method.
It has become ill. Secondly, when controlling the amount of coating liquid applied on a high-speed line using this roll squeezing method,
I have the following problem.

(G) Width direction e and i@- properties are reduced.

(b) When changing the plate thickness of the copper strip and when downing the copper strip, the amount of adhesion was determined.

(c) Rolls are heavily worn and maintenance is expensive.

2) When the line is stopped, K11-1kpK@fabric liquid sticks and reduces the drawing property.

Therefore, as a method to solve these problems, a so-called gas wiping (gas throttling) method was developed because it can easily control the adhesion amount without contacting the copper strip. This method has been widely used in the field of hot-dip metal plating, and a typical example is shown in Figure 1. (1) in J is a copper strip, which is drawn out from the molten metal bath (2), and the excess molten metal adhering to its surface is passed through the gas wiping nozzle (3) (3')
It was as if the amount of film deposited was controlled by blowing off the film with gas injected from the film. However, if such a method is immediately applied to coating type chemical conversion treatment liquids or OIk cloth liquid coatings such as elms, there may be problems such as nozzle contamination due to splash generation, nozzle slit clogging, and quality deterioration due to product contamination. Problems arose, making it difficult to put it into practical use on high-speed lines.

The reasons for this are as follows.

(a) The above-mentioned 0Ill cloth liquid has a higher viscosity (1
~several hundred ap), low density (about 1F/-), viscosity is about the same to about 100 times, and density is several minutes lower. As a result, when the line speed is constant, the amount of coating liquid lifted by the steel 11 is much larger than that of the molten metal, so the splash caused by the bulging of the liquid film is intense. It is known that the amount of coating liquid required to lift the band is theoretically proportional to the square root of the product of viscosity and line speed, and inversely proportional to the square root of density.

Considering this, it can be seen that in the case of coating liquid, compared to hot-dip metal plating, it is necessary to operate at a considerably lower line speed without generating splash (empirically, 3
0WL/- or less).

■Generally, the surface tension of the coating liquid is small, and as a result, the amount of coating liquid lifted by the steel strip causes splash LJ&<, and its low density helps to entrain secondary air at the nozzle tip. Due to the effects of this turbulence, there are problems of nozzle contamination, nozzle slitting, and product contamination resulting in quality deterioration.This phenomenon is a serious problem in the case of quick-drying OIk fabric liquids. Since it contains heavy metals (such as hexavalent metals) and organic solvents that are harmful to the human body, the coating type chemical conversion treatment tank or coating zone that handles them is a steel-shelled system that is closed for safety reasons. As a result, the generated splash sL#i fills the processing tank or coating zone, and secondarily contaminates the gas wiping nozzle.

As is clear from the above reasons, when using gas wiping to control the amount of coating on copper strips on high-speed lines, splash generation is unavoidable, and nozzle contamination is therefore avoided. Measures against this problem are necessary. Nozzle contamination due to this splash is caused by
There are two main types of contamination: primary contamination, which occurs simultaneously with the generation of splash, and secondary contamination, which occurs when the generated splash fills the treatment tank or coating zone. - The cause of secondary contamination is thought to be due to the entrainment of secondary air at the tip of the nozzle and its turbulence. This is thought to be due to the entrainment of secondary air at the nozzle tip.

By the way, as already explained, this secondary contamination is a common problem in both molten metal fittings and the coating liquid targeted here, and the first method to solve this problem is to modify the nozzle structure. Specially designated by the inventors 1987-10879
It was proposed in No. 1.

However, the reality is that there is still no solution to the problem of secondary contamination.

The present invention is designed to prevent splashes (nozzle contamination or nozzle slit clogging, as well as deterioration of product quality) that occur when continuously controlling the amount of film deposited by gas miping in coating type X-ray coating. It was developed in order to solve the problem ``■'', and its gist is that the coating type chemical conversion treatment liquid or paint etc. 0 @ fabric liquid O surplus applied continuously to the surface of the copper strip. In a device for gas wiping the coating liquid, a 1kl! An O baffle was provided for the secondary air passage WII!IcO at an interval at the bottom of the gas nozzle 9, and an air suction mechanism (air suction mechanism) leading to the outside of the 111110 was provided at the bottom of the test buffer 111110. Special 1m
This is a gas wiping device for coating liquid on steel strips.

Hereinafter, an embodiment of the gas wiping device according to the present invention will be described in detail in comparison with the conventional gas wiping device proposed by the above-mentioned inventors prior to the filing of the present invention. The 2nd m shows an example of the conventional gas wiping device mentioned above, which performs paper cutting and application of a coating type chemical conversion treatment liquid. Figure 3 (1
) (2) and 411 are both gas wiping devices of the present invention, and Fig. 3 shows an example of coating the (→-) Co., Ltd. Co., Ltd. Co., Ltd.'s J1611 liquid, and Fig. 4 also shows an example of its application. Ru. Each [K next week 0 (1) is a steel strip. (2) This is the side wall of the processing tank for storing the catfish and the ceiling wall of the processing tank. (& is housed in the treatment tank - ゐcoating chemical treatment bath) (7 bell room■ gas 9
It is an Ibinda nozzle. However, the conventional equipment shown in 4112ml was used to blow off the excess processing liquid with the (7')K of the acute-angled gas nozzle, and report the amount of film deposited. In this case, the gas wiping device A/(7) (7) flows in the tank according to the flow 11 shown by the air arrow, passes through the air rfIi installed on the ceiling wall ■,
It is led to the duct (10) (10'). In addition, data) (
10) (10 extended end Kfi air cleaning equipment shall be installed. Also, a IIKa thermal storm drying equipment (11)-!11 shall be provided on the chemical marriage tank O, and hot air blown out from there. flows from the gap (12) into the duct (io) (10).In this way, C7 of the gas 9 Ibinda nozzle
In the case of conventional O equipment with a catfish, a stream-like splash is generated in the treatment tank, and secondary air (15) (15') to the tip of the gas nozzle (7') is generated.
1! The entrainment entrains the splash, which secondarily contaminates the nozzle. Therefore, the inventors proposed a conventional chemical treatment method having a C7 gas wiping nozzle.
This study was conducted with the aim of eliminating the above-mentioned drawbacks.
vh'lk accompanied by a splash like a mistake)
%Ih-A baffle for letting in the secondary air and a baffle # for separating the generated mist-like splash and air as necessary, and the above-mentioned gas 9
By installing an air suction mechanism (air suction mechanism) to suck the air ejected from the (A) of the Ibinda nozzle, secondary contamination of the nozzle (7I) caused by Splash JLK can be reduced to just one degree. I'll break the machine.
is a line between the word ``to eliminate''.

, #1311(a) and (b) show examples of the gas wiping device of the present invention, in which the coating liquid is gas-wiped, the copper strip runs on the running line of the self-copper strip, and the my binder nozzle #( 7I) of this O nozzle.
Underneath, there are 15 parallels for introducing clean secondary air (14) (14).
Ru. This O baffle (15) (15 O tip line nozzle (
7') It is rounded downward near the tip of fD, but this is to send the secondary air (14) smoothly downward.Baffle (15) (15) It is appropriate to position it horizontally in the range of 20 to 200 amO below (7I).
The distance between the five tips is determined by the positional relationship between them and (7I) of the nozzle. Yes, there is also a baffle (15) (the curved partition plate (116) is attached to the bottom of 15). A round semicircular baffle (17
) (17 is the installation - Partition plate (16) (141 company The purpose is to adjust the flow of the jet H5L running air from (7') of the nozzle.
7 is used for the purpose of separating the crystalline splash and air by centrifugal force, and at the bottom of these passages the separated splash is returned to the chemical conversion treatment bath (6).
18) (18 are established. (19) (19 Risha S
- It is an air outlet leading to the outside of IIc#i, and although not shown in the drawings, an air suction mechanism is provided. The suction fIkIIi of this air suction mechanism is preferably 1.1 to 5.0 times the amount of air blown out from the seven (usually) Zuru (7), so it is installed on the ceiling a!@ of the chemical conversion tank. Being beaten-
Since outside air is constantly flowing in from the i*iim, the treatment tank itself is a closed system. The air flows smoothly along the streamline (20)k shown by the arrow.
The figure shows an application example of the O gas wi binder device of the present invention.The baffle (21) (21
#), and the air outlet (19) (19') is placed below the chemical conversion tank. Air outlet (
19) (19th 69f) Although not shown in the figure, an air suction mechanism and an air cleaning device are provided.

Next, an example in which the gas twin binder device of the present invention is applied and a comparative example in which a conventional gas twin binder device is used for comparison will be shown.

Implementation @ 1' On a lip-shaped galvanized steel plate with a plate thickness of 27-1 and a width of 1'219-1, a viscosity of 409s, a density of t041-1, a surface tension of 36 dyn/aa, and an organic coating source Kaseijima liquid were applied. Dip coating using a vertical line 1 Figure 3 (1) (b) k
Film adhesion measurement was carried out using the gas evibinder device of the present invention as shown. At this time, the condition was a linear notification・z2. + (7) * (7') and hat y * (15)
e (15') Oflag: 50 ■ s y y # (15) e (15 tip spacing:
100m5 baffles (15), (15') and baffles (17) (17 bottom spacing =
700 ■ (Amount of air suction) ÷ (Amount of air ejected from Nozzle #) 81.2 Gas Wy Binda condition customer Nozzle and strip 0 spacing
15w Nozzle width t5 Air pressure α8gl1 As a result, even at a line speed of 6001v4aI, there was no secondary or secondary damage to the nozzle due to splash generation, and continuous operation could be performed.

Example 2 Plate thickness α27-1 Plate width 121? - strip of molten metal on galvanized steel sheet, viscosity 12001), density 2.19
/j, surface tension 52 dye, AO coating was applied by dip coating using a vertical line, and the amount of film deposited was controlled using the gas riving equipment f of the present invention shown in Fig. 3) (b). Ta. The conditions at ζ0 were as follows.

Nozzles (7), (7 and baffles (15), (15)
ri spacing: 30 Baffle (15), (15') e tip spacing = 60
■Bass# (15), (15') and baffle (17)
, (17 lowest interval:
7ooss (amount of air suction) ÷ (amount of air ejected from the nozzle)! 5.0 Gas living conditions Snow Nozzle and X-nip oflN1M15m Nozzle slit width
1.2- Air pressure 1.01 As a result, there is no primary or secondary contamination of the nozzle due to splash generation even at twin speeds of 200 m/-.
It was a relief to be able to carry out continuous operation.

Comparative Example The chemical conversion treatment solution used in Example 1 was applied by dipping in a second on a vertical line onto a hot-dip galvanized steel sheet with a plate thickness of α27-1 and a plate width of 121 to 5 m0. A film adhesion amount control was conducted using the apparatus. The conditions at this time were as follows: Gas wi binder condition t Between nozzle and strip II
15 ■ Nozzle slit width 1.5 - Air pressure A8 As a result, there was no primary contamination of the nozzle due to splash generation at the 200 II/4110 line speed, but due to secondary contamination, the nozzle slit after about 2 hours of continuous operation) The gas in the copper band coating wave of the present invention caused clogging, making it impossible to operate! Use the Ibinda device-1
Even on a high-speed line of 200 sheets or more, it is possible to use paints from one manufacturer that have high viscosity, low density, and low surface resistance, which may cause secondary contamination of the nozzle due to splash generation. Therefore, it is possible to control the amount of film deposited on the copper strip. It is believed that the gas 9 ibinda device according to the present invention will be applicable to ultra-high-speed metal melting lines that will appear in the future.

[Brief explanation of the drawing]

Both FIG. 1 and FIG. 2 are cross-sectional views of a conventional gas wiping device. FIG. 3(a) is a sectional view of one embodiment of the gas wiping device of the present invention, and FIG. 3(b) is a partially cutaway self-perspective view thereof. FIG. 4 is a sectional view of an embodiment of the gas wiping device of the present invention. FIG. 6 is a cross-sectional view of yet another embodiment. (4) Side wall, (9 ceiling wall, (gradation treatment bath, (7'
) Gas wiping nozzle, (14), (14 secondary air, (15). (15 secondary air intake baffle, (116), (
16/) Partition plate, (17), (17 Baffle for air and splash separation, (1B), (18) Liquid return passage, (
19), (19 air outlets, (21), (21) baffle to separate air and splash, (22) air inlet for gas wiping nozzle. Attorney: Masatoshi Sato

Claims (1)

[Claims] Steel strip O*WEC Coating that is applied continuously - A device for gas wiping the excess of the coating liquid of the chemical conversion treatment box or Korean material IIs. ``&II-'' is installed at the line location, unrelated to the running of the copper strip,
A gas wiper nozzle is provided in the upper part of the pipe, and a secondary air passage is provided at a spaced interval in the lower part of the gas wiper nozzle.
1. A gas wiper device for a copper strip coating liquid, characterized in that a baffle is provided for the IPI, and an air suction mechanism communicating with the outside of the IPI is provided below the baffle.