JPH0459948B2 - - Google Patents

Description

A wiping device for applying a coating liquid to a strip-shaped body, characterized in that it is equipped with a wiping gas outlet 16 connected in stages.

2. The wiping device according to claim 1, wherein the lower end of the surrounding body is an open end and is immersed in a coating liquid bath 2 from which the band-shaped body is immersed and pulled up.

3. The wiping device according to claim 1 or 2, further comprising a curved guide plate 20 for wiping gas extending from the tip of the gas wiping nozzle into the lower space.

4. The wiping device according to claim 3, wherein the curved guide plate also serves as the buttful plate.

5. The wiping device according to any one of claims 1 to 4, wherein a receiving tray portion 18 for the excess coating liquid entrained in the wiping gas is provided in the lower space.

[Detailed description of the invention]

(Industrial Application Field) The present invention uses a wiping device for applying a coating liquid to a strip, and in particular, by adjusting the flow of wiping gas when the strip is running at high speed, it is possible to prevent nozzle clogging caused by splash mist and improve quality. The present invention relates to a device for preventing deterioration.

In recent years, Metsuki lines have been required to be faster in order to improve productivity. This also applies to coating type chemical conversion treatment methods, and speeding up is required.

The present invention meets these contemporary demands in the industry.

(Prior art) By the way, roll squeezing has conventionally been a common method for controlling the amount of chemical conversion coating deposited, but the amount of deposition changes depending on the line speed, and if the roll is damaged by a strip edge, the damage may occur. There are problems such as images being transferred to finished products. Alternatively, there were problems such as coloring of the edges due to wraparound to the strip edge portions.

As a solution to this problem, a gas wiping method has been proposed in which the excess coating liquid is wiped away by spraying high-speed gas. However, the biggest drawback of this method is the generation of mist (hereinafter referred to simply as "mist") caused by the splash that occurs during wiping. ``Splatshumist''). When splash mist is generated, problems such as wiping nozzle blockage, adhesion to the strip, and uneven adhesion occur.

Various solutions to such splash mist have been proposed in the past.

For example, Japanese Patent Application Laid-open No. 53-52549 discloses that the surrounding space is divided into two by a wiping nozzle and the upper space is enlarged, with the aim of adjusting the amount of splash mist deposited during gas wiping and ensuring quality. The gas flow from the space is brought to the lower space to generate a strong overall downward gas flow in the space around the wiping nozzle, thereby preventing the harmful effects of splash mist. In such a system, a downward gas flow that wraps around from behind the wiping nozzle is essential.

In the case of JP-A No. 58-55069, a full plate is provided below the gas wiping nozzle, and
A secondary air passage is provided between the nozzle and the full plate, and clean secondary air without mist is taken into the lower end of the nozzle. In this case as well, air flow toward the nozzle tip at the lower end face of the gas wiping nozzle is essential.

However, from the experimental results of the present inventors,
It has been found that the conventional equipment described above cannot always sufficiently prevent the harmful effects of splash mist when processing at high speeds of, for example, 150 m/min or more, which are required today. Ivy.

In other words, the higher the speed, the more significant the harmful effects of splash mist become.

(Problems to be Solved by the Invention) Therefore, it is an object of the present invention to provide a wiping device that prevents the harmful effects of splash mist.

Another object of the present invention is to increase the traveling speed of the strip to, for example, 150 m/min or more,
To provide a wiping device capable of effectively discharging mist to the upstream side in the running direction of a band-shaped body even when the mist divergence speed increases.

(Means for Solving the Problems) Thus, in order to achieve the above object, the present inventors have made extensive studies and found that in the past,
It is good to provide a baffle plate, but even if a space is created between the top surface of the buffle plate and the bottom surface of the wiping nozzle to generate a gas flow toward the nozzle tip, the fine particles that make up the mist will I learned that because it is given kinetic energy, it resists such gas flow and easily scatters.

In this way, there is splash mist that is scattered in the direction of the enclosure side wall between the wiping nozzle and the baffle plate due to the kinetic energy of the splash itself, contrary to the flow on the lower end surface of the wiping nozzle, and this spray mist is scattered near the enclosure side wall. They ride on the inevitable rising air currents and adhere to the product after wiping. Such a splash becomes more severe as the line speed increases because the amount of chemical conversion liquid lifted by the strip increases.

Here, the gist of the present invention is to provide: a gas wiping nozzle that is provided facing at least one surface of a traveling strip to which a coating liquid is attached; an enclosure provided with an outlet portion of the strip; disposed within the enclosure in contact with the lower end surface of the gas wiping nozzle, leaving an opening through which the strip runs; A pair of buttful plates that separate and partition into an upper space and a lower space in which a wiping nozzle is arranged; and a wiping gas discharge port that communicates with the lower space of the surrounding body and is connected to suction and exhaust means. This is a wiping device for wiping a coating liquid onto a strip.

When the gas wiping nozzles are provided oppositely on both sides of the band-shaped body, the buff-full plates are also placed oppositely with the band-shaped body in between.

Further, the lower end of the surrounding body may be an open end, and the band-shaped body may be immersed in a coating liquid bath to be immersed and pulled up, and/or the wiping gas may be extended from the tip of the gas wiping nozzle into the lower space. It may further include a curved guide plate.

Furthermore, even if the curved guide plate also serves as the baffle plate, a receiving tray for the excess coating liquid entrained in the wiping gas may be provided in the lower space.

The treatments of the present invention include hot-dip galvanizing such as hot-dip galvanizing, chemical conversion treatments such as chromate treatment for electroplated steel sheets, etc., and various other surface treatments. It is generally applied to the gas wiping method, which is performed for the purpose of uniformly adhering the particles and preventing wraparound.

Therefore, the "coating liquid" includes molten metal, chemical liquid, and other surface treatment liquids.

The term "strip" therefore includes not only so-called steel strips but also aluminum strips and the like.

(Operation) The present invention will now be described in further detail with reference to the accompanying drawings.

1 to 3 schematically show the concept of the wiping device according to the present invention, and FIG.
The figure is a perspective view of the device according to the present invention specifically assembled. In the illustrated embodiment, the gas wiping nozzle is disposed facing both sides of the strip, but it may be disposed only on one side, and accordingly, the buffle plate may also be provided only on the gas wiping nozzle side. In this regard, the present invention is characterized in that the buffful plate and the gas wiping nozzle are brought into close contact with each other, and suction and exhaust are carried out from the lower space partitioned by the buffful plate. There are no restrictions on

In each drawing, the same parts are designated by the same reference numerals.

In FIG. 1, the strip 4 being lifted from the bath 2 of coating liquid and the gas wiping nozzles 6, generally arranged in pairs, are surrounded by an enclosure 8, which extends the outlet 9 of the strip 4 from the top. The surrounding body 8 provided in the upper space 8 is divided into an upper space 12 and a lower space 14 by a baffle plate 10. A wiping gas discharge port 16 is provided in the lower space 14 . This gas wiping nozzle 6 is a conventional one and is not particularly limited.

In the illustrated example, the lower end of the enclosure 8 is an open end and is immersed in the bath 2. As a modification, the lower end may also be closed and only the inlet portion of the strip 4 may be provided.

According to the present invention, no air passage or space is provided between the lower end of the gas wiping nozzle 6 and the baffle plate 10. That is, the baffle plate 10 is placed in contact with the lower end surface of the gas wiping nozzle 6. Further, the upper space 12 and the lower space 14 are only in communication with each other through an opening 17 that serves as a passage for the band-shaped body 4. The wiping gas from the wiping nozzle 6 is sucked in and discharged exclusively from the discharge port 16, as indicated by the arrow in the figure.
This outlet 16 is connected to an appropriate suction and exhaust device (not shown).

Therefore, a flow of wiping gas is constantly observed in the wiping device in the opposite direction to the sheet passing direction, and the flow rate can be easily changed by changing the suction and discharge speeds from the discharge port 16.

Therefore, with the above-described configuration, even when the strip is running at high speed, although the generation of splash itself cannot be prevented, product contamination due to splash mist is eliminated, and a beautiful treated surface can be obtained.

The structural example shown in FIG. 1 is the simplest one, but in the second part, a receiving tray part 18 for the coating liquid accompanying the wiping gas is provided, and in the case of the illustrated example, a curved guide plate for the wiping gas is provided. Ga Batsuful 1
It is also used as 0. Further, in FIG. 3, a curved guide plate 20 extending from the tip of the buff-full plate 10, that is, the tip of the gas wiping nozzle 6, is provided separately from the buff-full plate 10, and extends from the tip of the gas wiping nozzle 6. As in the case of FIG. 1, it hangs down from the full plate 10.

FIG. 4 is a schematic perspective view of the device having the structure example shown in FIG. The splash mist is also constantly sucked downward and does not adhere to the strip 4 after the wiping process. The splatter mist entrained by the wiping gas through the nozzle opening is decelerated as it is sucked along the curved guide plate 20. At this time, the entrained mist is dropped into the receiving tray 18, and the coating liquid constituting this mist is is returned to bath 2.

In addition, it is desirable to suck in the exhaust gas to the outside of the surrounding body 8 in an amount equal to or more than the amount of wiping gas, and desirably, it is desirable to suck in 1.5 times or more the amount of gas.
If the suction ratio is 1 or more, the upper opening of the enclosure will suck in outside air, and the chemical conversion treatment fume will not come out of the enclosure, making it suitable for coating harmful substances.

Next, an example will be shown to demonstrate that the device according to the present invention having the above-described structure can effectively prevent the harmful effects of splash mist.

EXAMPLE Chromate treatment was carried out on steel strip using the apparatus shown in FIGS. 3 and 4. The chromate treatment solution used at that time was used as a coating solution, and air was used as a wiping gas to perform wiping treatment under the following conditions.

Table 1 Gas pressure: 0.5Kg/cm ² Nozzle slit: 1.0mm Nozzle strip (distance): 15mm Strip size: 0.8 x 1000mm Treatment liquid: 2.5% Cr solution Chromium deposit amount: 30-40mg/m ² Buffful plate for comparison Comparative Example-1 is an example in which the full board and gas wiping nozzle are not provided, Comparative Example-2 is an example in which the full plate and the gas wiping nozzle are installed apart, and Comparative Example-2 is
An example in which the space below the buff-full plate was suctioned and evacuated was treated as Comparative Example 3, and chromate treatment was performed in the same manner.

In addition, an example using the apparatus shown in FIG. 2 is an example of the present invention.
1. Similarly, the case shown in FIG. 3 is referred to as Invention Example-2.

The results are summarized in a graph in FIG. In the figure,
Each symbol is as shown in Table 2.

Table 2 Comparative example -1 ...× 〃 -2 ...▲ 〃 -3 ...△ Present invention example -1...○ 〃 -2...● In the graph of Fig. 5, the appearance of the product was visually evaluated on a five-grade scale, and evaluated based on the degree of splash contamination. The level marked with ◎ is the appearance without any splash mist. In the example of the present invention, there is no splash contamination even at high speed processing of 200 m/min, which is much more effective than the conventional technology.

[Brief explanation of the drawing]

1 to 3 are conceptual diagrams of the device of the present invention; FIG. 4 is a partially exploded perspective view of the device in FIG. 3; and FIG. 5 is a summary of the results of the examples. This is a graph showing. 2... Bath, 4... Band-shaped body, 6... Gas wiping nozzle, 8... Surrounding body, 9... Outlet part, 10...
...Bassful board, 12... Upper space, 14... Lower space, 16... Outlet.

Claims (1)

[Scope of Claims] 1. A gas wiping nozzle 6 provided to face at least one surface of the traveling strip 4 to which the coating liquid is attached; a gas wiping nozzle 6 surrounding the strip and the gas wiping nozzle; An enclosure 8 provided with an outlet portion 9; disposed within the enclosure in contact with the lower end surface of the gas wiping nozzle, leaving an opening 17 through which the band-like body runs; a full plate 10 that separates and partitions into an upper space 12 and a lower space 14 in which a wiping nozzle is arranged;
and A suction and exhaust hand that communicates with the lower space of the surrounding body.