JPH0639678B2 - Gas wiping device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention removes excess plating solution or paint by gas wiping when performing hot metal plating or coating with various paints on strips such as steel strips. And a gas wiping device that adjusts the amount of adhesion.

<Prior Art> In molten metal plating, a gas wiping method is used to adjust the amount of molten metal deposited.

In this gas wiping method, as shown in FIG. 6, front and back wiping nozzles 2 and 2 with a steel strip 9 as an object to be plated interposed therebetween.
Are arranged opposite to each other, and this wiping nozzle has a uniform slit gap (gas ejection ports 21, 21) in the width direction, and a uniform ejection gas is blown toward both sides of the steel strip 9 at a substantially right angle. The surplus molten metal 11 above is wiped off. However, in such a gas wiping method, usually, the molten metal on both side edges of the steel strip 9 is more difficult to be wiped than the central portion of the steel strip, so that plating on both side edges of the steel sheet, which is a so-called edge overcoat, is performed. A phenomenon occurs in which the weight per unit area is larger than that in the central portion.

Conventionally, the following methods have been proposed as a method for preventing the edge overcoat.

A method for improving the drawability of the side edges of the steel strip by attaching auxiliary nozzles near both side edges of the steel strip above the gas throttle nozzle and blowing gas toward the steel strip upstream in the traveling direction (JP-A-52- 99933).

Shield plate (baffle plate) for preventing jet gas interference adjacent to the steel strip side edges to prevent turbulence of the gas flow due to mutual interference of the gas jetted from the front and back side wiping nozzles on both side edges of the steel strip. An edge overcoat preventing device provided with (Japanese Patent Application Laid-Open No. 50-91535), the shape of the gas ejection port of the front and back wiping nozzles is a tapered gap in which only the widthwise both side edges of the steel strip are widened,
Method to increase wiping force on the side edge of steel strip Around the wiping nozzle for the front and back sides, an auxiliary nozzle is installed near both side edges of the steel strip to inject gas in a direction almost parallel to the traveling direction of the steel strip and in the opposite direction. Method to prevent nozzle clogging of front and back wiping nozzles due to splash in the vicinity of the side edge (Japanese Utility Model Publication No. 57-150552) However, in the above, delicate gas pressure control of the gas throttle nozzle and the auxiliary nozzle is difficult. However, if the gas pressure is improper, there is a problem in that the uniformity of the coating amount in the steel strip width direction is impaired.

In the above, when the shield plate is installed close to the steel strip end surface,
Since the splash easily adheres to the shield plate and the function of the shield plate deteriorates, there is a problem in that the shield plate must be frequently cleaned or replaced, and a satisfactory effect cannot be continuously obtained.

In the above, it is necessary to replace the front and back surface wiping nozzles according to the change in the width of the steel strip, which leads to a decrease in workability and productivity, and a large number of types of wiping nozzles are required, which increases the manufacturing cost. It has the drawback of inviting.

The above merely prevents the nozzle clogging of the front and back surface wiping nozzles due to the splash occurring near the edge of the steel strip, and is not an effective means for the edge overcoat occurring at the edge of the steel strip.

<Problems to be Solved by the Invention> An object of the present invention is to solve the above-mentioned drawbacks of the prior art, prevent adhesion to a gas wiping device due to splash of liquid such as splash, and make uniform in the width direction of the strip. Another object of the present invention is to provide a gas wiping device capable of continuously obtaining a large amount of adhesion.

<Means for Solving the Problems> The main cause of the non-uniform coating amount in the width direction of the steel strip is that the coating amount increases due to lack of local gas drawing force at the side edge of the steel strip. It is in. In order to make the gas drawing force at the side edge of the steel strip equal to that at the central portion, it is effective to provide a shielding plate as an additional extension of the virtual steel strip in the width direction of both ends of the steel strip. However, it is extremely difficult to install the shield plate in close proximity to the steel strip because the wiping gas for the front and back surfaces causes splashes from the side edges of the steel strip to easily attach to the shield plate only by installing this shield plate. Therefore, the function of the shielding plate cannot be fully exerted, and consequently, it is impossible to continuously obtain a uniform coating amount in the width direction of the steel strip.

The present inventors conducted various experiments and observations in order to investigate the cause of reducing the drawability of the molten metal at the side edge of the steel strip, and obtained the following findings.

The wiping gas ejected from the front and back wiping nozzles on the outer side of the steel strip interferes with each other and deteriorates the gas drawability near the side edge of the steel strip.

At the edge of the steel strip, the flow of wiping gas toward the upstream side (plating bath side) in the direction of travel of the steel strip after it is ejected from the wiping nozzles for the front and back surfaces and collides with the steel strip is smaller than in the central portion of the steel strip. , More excess molten metal is lifted. Therefore, at the wiping point, the side edge portion needs a stronger gas drawing force than the central portion of the steel strip.

At the edge of the steel strip side, the gas flow ejected from the front and back wiping nozzles flows outward in the width direction of the steel strip, and this transverse flow causes the splash to fly outward in the width direction of the steel strip. When the shield plate for preventing mutual interference is attached, the splash easily adheres to the shield plate.

Conventionally, since the shielding plate has been extended a considerable distance (for example, about 50 to 300 mm) below the gas collision point of the front and back wiping gas (hereinafter referred to as the wiping point) (upstream side in the traveling direction of the steel strip), the shielding is performed. Splash was likely to adhere to the plate (splash of splash was more severe on the upstream side in the running direction of the steel strip near the plating bath). However, the shielding plate has a height range (for example, about 5 to 20 mm) including the wiping point.
Even if it is installed in, the mutual interference prevention effect of the front and back wiping gas is sufficiently obtained, and it is not necessary to extend it to the lower side.

Therefore, based on these findings, by using a shield plate that can shield only the vicinity of the wiping point as a shield plate that prevents mutual interference of the front and back side wiping gas outside the steel strip width, it is possible to make splash less likely to adhere. At the same time, in order to prevent the splash from splashing outward in the width direction of the steel strip, it was found that a nozzle for blowing gas toward the upstream side in the steel strip running direction is provided between the shielding plate and the steel strip edge. The present invention has been reached.

That is, the present invention is a gas wiping device for adjusting the amount of adhesion when a liquid is adhered to a continuously running belt, which extends in the width direction of the belt and is directed to both front and back surfaces of the belt. Front and back side wiping nozzles for respectively ejecting gas, and a height including a collision point of the gas ejected from the front and back side wiping nozzles, which is located on the strip width direction extension surface in the vicinity of both edge portions of the strip. And a pair of shielding plates installed on the strip, and installed between the inner end of the shielding plate and both edge portions of the strip, and to the upstream side in the running direction of the strip in the extension direction in the width direction of the strip. The present invention provides a gas wiping device having a pair of edge wiping nozzles for ejecting gas toward it.

Further, it is preferable that the edge wiping nozzle is a gas wiping device integrally attached to the shielding plate.

It is preferable that the gas wiping device is provided with a moving means for moving the shielding plate and / or the edge wiping nozzle in the width direction of the band-shaped material.

Further, it is preferable that the gas wiping device is provided with a control means for controlling the gap distance between the shielding plate and / or the edge wiping nozzle and the edge portion of the band-shaped article to be kept within a certain range.

Hereinafter, the gas wiping device of the present invention will be described in detail with reference to the preferred embodiments shown in the accompanying drawings.

FIG. 1, FIG. 2 and FIG. 3 are a plan view, a side view and a front view, respectively, showing a preferred configuration example of the gas wiping device of the present invention. The gas wiping device 1 of the present invention is
Since the steel strip is symmetrical on both sides in the width direction, one side will be described.

The steel strip 9 pulled up from the molten metal (for example, molten zinc or molten tin) in the hot dip bath continuously travels upward as shown by arrows in FIGS. 2 and 3.

Wiping nozzles 2 for front and back surfaces which spread the pressure in the width direction of the steel strip 9 are installed on both front and back sides of the steel strip 9. The front and back wiping nozzles 2 and 2 are provided with slit-shaped gas ejection ports 21 and 21, respectively. The gas ejection ports 21 and 21 are applied to both front and back surfaces of the steel strip 9 with a uniform pressure in the width direction. Gas is blown out to wipe off excess molten metal adhering to both sides of the steel strip, and the basis weight is adjusted.

The front and back wiping nozzles 2, 2 extend further outward than the width of the steel strip 9 as shown in FIGS. 1 and 3. This is for all widths (usually 500-1550
This is because gas wiping can be performed on the steel strip 9 (mm) without replacing the nozzles 2, 2.

Beams 5 and 5 extending in the width direction of the steel strip 9 are provided above the front and back wiping nozzles 2 and 2, and the wheels 4 axially supported by the carriage 3 are provided above the beams 5 and 5. The trolley 3 can roll and move in the width direction of the steel strip 9. The carriage 3 is moved by driving the wheels 4 in either forward or reverse directions by a driving means 10 such as a motor built in the carriage.

A shield plate 6 is fixed to the lower portion of the carriage 3 for preventing the gases ejected from the front and back surface wiping nozzles 2, 2 on the outer side in the width direction of the steel strip from causing mutual interference.
When the gas wiping is performed, the shielding plate 6 is located on the extension surface in the width direction of the steel strip near the edge portion 91 of the steel strip 9 and is installed at a height including the wiping point A.

If the extension length of the lower end of the shielding plate 6 to the upstream side in the traveling direction of the steel strip is long, splash is likely to adhere, which is not preferable. Therefore, it is preferable that the lower end of the shielding plate 6 is about 5 to 20 mm below the wiping point A. Even in this case, it is possible to sufficiently obtain the mutual interference prevention effect of the wiping gas for the front and back of the steel strip.

An edge wiping nozzle 7 is provided between the inner end portion 61 of the shield plate 6 and the edge portion 91 of the steel strip 9. The edge wiping nozzle is installed substantially parallel to the edge portion 91 of the steel strip, and ejects gas from the gas ejection port 71 at the tip thereof toward the upstream side in the running direction of the steel strip within the extension surface in the width direction of the steel strip. As a result, the wiping force on the front and back surfaces of the steel strip in the vicinity of the edge of the steel strip 9 is prevented from being reduced, the edge overcoat is prevented, and the splash splashing outward in the width direction of the steel strip is jetted from the edge wiping nozzle. Since it is greatly reduced by the gas flow, the attachment of splash to the shield plate 6, the nozzle 7, and other parts of the wiping device 1 is suppressed.

If the gas ejection direction of the edge wiping nozzle 7 is the upstream side in the steel strip running direction within the steel strip width direction extension surface, the gas ejection direction is slightly directed to the steel strip 9 side, or conversely, to the shielding plate 6 side. It is also possible to turn to. In the former case, the wiping force near the edge portion 91 becomes strong, and in the latter case, the wiping force becomes weak. Therefore, the gas ejection amount (ejection pressure) from the edge wiping nozzle 7 may be appropriately increased or decreased to optimize the wiping force.

In the example shown in FIG. 3, the edge wiping nozzle 7
Is fixedly attached to the inner end portion 61 of the shield plate 6 and is configured to move simultaneously with the shield plate 6. However, in the present invention, the edge wiping nozzle 7 and the shield plate 6 are separated from each other. May move independently or in conjunction with each other.

The cross-sectional shape of the gas outlet of the edge wiping nozzle 7 is
It is generally circular, but as shown in FIG. 4 or 5, it has an elliptical shape having a major axis in the width direction of the steel strip 9 or a direction perpendicular to the width direction, or a rectangle or slit shape. Etc. are also possible.

The gas is supplied to the edge wiping nozzle 7 through an air supply pipe 8 connected to the nozzle 7.

Such a shielding plate 6 and edge wiping nozzle 7
Are fixed to the carriage 3, and these are moved in the width direction of the steel strip 9 by moving the carriage 3.

The movement of the shielding plate 6 and the edge wiping nozzle 7 is performed when setting the initial position when changing the width of the steel plate on which the molten metal plating is performed. Further, while the steel strip may meander (oscillate) in the width direction during continuous hot metal plating, the shield plate 6 and the edge wiping nozzle 7 should be moved following the meander. Is preferred. That is, as shown in FIGS. 1 and 3, it is preferable to provide a control means for controlling the gap distance ΔL between the edge wiping nozzle 7 and the edge portion 91 of the steel strip 9 to be kept within a certain range.

Examples of this control means include those having the following configurations. A detection device (for example, a limit switch, an optical sensor, a magnetic sensor, etc.) for detecting the position of the edge portion 91 of the steel strip is provided (not shown), and a detection value by the detection device is input to a computer to perform calculation. If the gap distance ΔL is out of the proper range, a command signal for moving the carriage 3 is output, the drive source 10 is driven based on the command signal, and the carriage 3 moves in a predetermined direction (steel strip). The edge wiping nozzle 7 is controlled in position so as to keep the gap distance ΔL within a proper range by moving the edge wiping nozzle 7 toward or away from the nozzle 9 by a predetermined distance.

Here, although the gap distance ΔL varies depending on the operating conditions such as the basis weight and the line speed, it is usually preferable to set it to about 2 to 10 mm.

Any control means may be used as long as it can maintain the gap distance ΔL within a certain range. In addition to the electric control means described above, the control means can follow the position of the edge portion 91 of the steel strip and can It may be configured to move the trolley 3 as desired.

In the above description, the case where the gas wiping device of the present invention is applied to gas wiping when performing hot metal plating on a steel strip has been described, but the application of the gas wiping device of the present invention is not limited to this, and steel is used. It can also be applied to gas wiping in the case of applying liquids such as various paints and various treatment liquids to a band or other band-shaped materials.

<Example> (Example of the present invention) Gas wiping having a structure shown in Figs. 1 to 3 was manufactured, and gas wiping was performed on a steel strip after hot dip galvanizing under the following conditions.

Steel strip width: 900 mm Steel strip traveling speed: 120 m / min Unit weight (target value): 45 g / m ² Shielding plate dimension: Vertical width 20 x length 600 mm Edge wiping nozzle inner diameter: 3 mm φ Edge wiping nozzle and steel strip edge Gap distance ΔL: 5mm Wiping for front and back sides Gas supply pressure to nozzle: 0.3kg / cm ² Edge wiping Gas supply pressure to nozzle: 3kg / cm ² Cart position control means: Steel strip edge detection value by laser projection / reception method Control by bogie position control based on (Comparative example 1) Gas wiping was performed under the same conditions as in the example of the present invention, except that a gas wiping device without a shielding plate and an edge wiping nozzle was used.

(Comparative Example 2) Gas wiping was performed under the same conditions as in the example of the present invention except that a gas wiping device provided with a shielding plate and no edge wiping nozzle was used.

In addition, the gap distance between the inner end of the shielding plate and the steel strip edge is 5
mm.

(Comparative Example 3) Gas wiping was performed under the same conditions as in the example of the present invention, except that a gas wiping device provided with an edge wiping nozzle and no shielding plate was used.

With respect to the present invention example and Comparative Examples 1, 2 and 3, the gas pressure of the gas flow flowing along the steel strip on the upstream side in the steel strip running direction from the wiping point was measured in the steel strip width direction. The results are shown in the graph of FIG. The horizontal axis of this graph shows the distance from the steel strip edge, and the vertical axis shows the ratio of the gas pressure at each portion when the gas pressure at the central portion in the width direction of the steel strip is 1.0.

As is clear from the graph of FIG. 7, in the gas wiping devices of Comparative Examples 1 to 3, the gas pressure in the plate width direction was not uniform and edge overcoating occurred, but the shielding plate with the edge wiping nozzle of the present invention In the gas wiping device having, there is almost no edge overcoat,
It was confirmed that a uniform coating amount was obtained in the width direction of the steel strip.

Further, in continuous hot dip galvanizing, gas wiping was continuously performed for 8 hours and the adhesion state of splash was examined. As a result, in the gas wiping device of Comparative Example 2, a considerable amount of splash adhered to each part of the device, especially the shielding plate. However, in the gas wiping device of the present invention example, almost no adhesion of splash to the shielding plate, the edge wiping nozzle, and other parts was observed.

<Effects of the Invention> According to the gas wiping device of the present invention, a shielding plate that prevents mutual interference due to collision of wiping gas ejected from the front and back surface wiping nozzles on the outer side in the width direction of the strip.
By providing an edge wiping nozzle for ejecting gas toward the upstream side in the running direction of the strip between the inner end of the shielding plate and the edge of the strip, for example, the present invention is applied to hot-dip metal plating on a steel strip. When applied to gas wiping when applying, the following effects are obtained.

Edge overcoating can be prevented and the amount of plating adhered in the width direction of the steel strip can be made uniform.

It is possible to reduce splashes scattered from the edge portion of the steel strip, and it is not necessary to frequently perform cleaning or replacement of the shielding plate and the wiping nozzle due to the adhesion of the splash to each portion of the wiping device. As a result, the cost can be reduced by reducing the maintenance cost, and the productivity can be improved by shortening the line stop time.

The noise generated due to the collision of the front and back surface wiping gas, which occurred in areas other than the steel strip, is reduced, contributing to the improvement of environmental conditions.

Since it is not necessary to form the taper gap in the gas ejection port of the front and back surface wiping nozzle, and the parallel gap can be formed, it is not necessary to replace the wiping nozzle according to the width of the steel strip, and the labor and time required for replacement can be saved.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration example of a gas wiping device of the present invention, FIG. 2 is a side view thereof, and FIG. 3 is a front view thereof. 4 and 5 are transverse cross-sectional views showing an example of the cross-sectional shape of the edge wiping nozzle according to the present invention. FIG. 6 is a partial cross-sectional side view showing a configuration example of a conventional gas wiping device. FIG. 7 is a graph showing the relationship between the distance from the steel strip edge and the pressure of the gas flow in the example. Explanation of symbols 1 ... Gas wiping device, 2 ... Front and back wiping nozzles, 21 ... Gas ejection port, 3 ... Truck, 4 ... Wheels, 5 ... Beam, 6 ... Shielding plate, 61 ... Inner end part, 7 ... Edge wiping nozzle, 71 ... Gas ejection port, 8 ... Air supply pipe, 9 ... Steel strip, 91 ... Edge part, 10 ... Driving means, 11 ... Molten metal

Claims (4)

[Claims] 1. A gas wiping device for adjusting the amount of liquid adhered when a liquid is adhered to a continuously running belt, the gas wiping device extending in the width direction of the belt and directed toward both front and back surfaces of the belt. A front and back surface wiping nozzle that ejects gas, respectively, and a height that is located on an extension surface in the width direction of the strip near both edges of the strip and that includes a collision point of the gas ejected from the front and back wiping nozzle. A pair of shields installed in the strip, and is installed between the inner end of the shield and both edge portions of the strip, and is directed toward the upstream side in the running direction of the strip in the extension direction of the strip in the width direction. And a pair of edge wiping nozzles for ejecting gas as a gas. 2. The gas wiping device according to claim 1, wherein the edge wiping nozzle is integrally attached to the shielding plate. 3. The gas wiping device according to claim 1, further comprising moving means for moving the shielding plate and / or the edge wiping nozzle in a width direction of the strip. 4. The gas wiping device according to claim 3, further comprising control means for controlling a gap distance between the shielding plate and / or the edge wiping nozzle and an edge portion of the band-shaped article to be kept within a predetermined range. .