JPS6082653A - Device for controlling amount of plated metal in hot dipping apparatus - Google Patents

Abstract

PURPOSE:To form a beautiful hot-dipped layer of extremely thin thickness on the surface of a strip by providing a supporting roll for the plated strip to a specified position above a gas wiper. CONSTITUTION:A strip 1 is passed through a hot-dipping bath and pulled up after passing through a sink roll 5 and supporting rolls 4, 4' in the bath. Excess molten metal is wiped off by blowing with ejected high pressure gas from gas wipers 3, 3' to form a hot dipped layer of extremely thin thickness. The supporting roll 2, 2' for preventing the vibration of the strip 1 are positioned in this case at a position apart by a distance Y from the top end of the wiper 3, 3' within a range surrounded by A-F in Fig. 2 and in a range where the hot- dipped metal is still unsolidified (h) depending on the rising speed of the strip. Even if the supporting roll 2, 2' are in the unsolidified range of the hot-dipped metal, a plated layer having smooth surface with beautiful extremely thin plated layer is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a device for controlling the amount of plating deposited by a gas squeezing method in hot-dip metal plating equipment. We propose a technology that directly prevents plate wobbling and warping near the gas wiper by arranging the gas wiper, thereby making it possible to obtain a hot-dip metal-plated plate with a clean surface and an ultra-thin coating.

Conventional technology and its problems In continuous hot-dip metal plating that uses the gas throttling method to control plating deposition, the conventional technology to achieve ultra-thin coating weight is to increase the gas pressure when spraying with a gas wiper (injection nozzle). Another method is to adjust the distance between the plated plate (strip) and the nozzle tip to a smaller value.

In these conventional techniques, for example, when spraying uses a method that increases gas pressure, flying metal powder called splash adheres to the surface of the strip and causes defects, as well as loss and significant noise due to splash. There was a problem. In addition, in the latter method of adjusting the distance, the string is often curved and has some wobbling, so there is a limit to how far the distance can be shortened, and it has been difficult to achieve a thin weight.

In order to overcome the above-mentioned problems of the prior art, a method of increasing the tension to prevent plate deflection and a method of providing an air bat to suppress plate deflection have recently been proposed. However, a woman said that although these improved techniques are somewhat effective in suppressing vibration, the equipment is expensive and it is not possible to completely prevent scratches near the injection nozzle, so it is difficult to avoid contact with the plated surface. Because the distance cannot be closer than 10 cities,
For example, in the case of zinc plating, it was not possible to achieve an ultra-thin basis weight of less than 980g7m2 per side.

OBJECT OF THE INVENTION An object of the present invention is to overcome the above-mentioned drawbacks of the prior art by disposing a support roll near the injection nozzle to suppress vibrations and ensure flatness of the threading strip. It is in.

Structure and scope of embodiments of the invention Generally, in hot-dip metal plating equipment, support rolls 2 and 2' are disposed above the bath surface to hold the IJ tube to be plated while suppressing vibrations. ing.

As shown in FIG. 1, the position is such that the plated metal adhesion layer is completely solidified. When the support roll 2.2' is disposed at a stage when the plated metal is not solidified, for example, Zn, kl, Zn-Ajt, Pb-8
Metal plating, such as n, had the disadvantage that the plating surface became rough and a clean surface quality could not be obtained.

Therefore, the present inventors determined that the line speed ('!)min
), various studies were conducted on the relationship between the amount of plating deposited, etc., and the position of the support roll, and it was found that in hot-dip metal plating, even if the plating metal comes into contact with the support roll in an unsolidified stage, the surface of the plating metal may be damaged. It was found that there is a suitable range in which induction can be achieved without any problems.

Table 1 shows the results of evaluating the plating surface when the line speed, zinc coating weight, and support roll height from the bath surface were varied. The range was as shown in Figure 8 (○, △, and × are evaluations of narrow plating in Table 1).

Table 1 Note 2: Splash occurs on the surface The critical significance of the line separating the area surrounded by A-F in the figure, which is the preferred range above, is: ■MA~B(Y=]OOrnm): Below this level However, due to equipment limitations, it is virtually impossible to provide support rolls.

・In order to obtain the same weight, as the line speed increases, the die pressure tends to need to be increased, and if it is outside this range, the gas flow will be squeezed out when obtaining a thinner grain angle, making it more likely that sedge rush will occur.

0m0-D (x (260m//I[]in)...
Upper limit of j, tj, the line speed of currently commonly used hot-dip metal plating equipment is up to 260 m/ncin.
It is.

This is because it becomes difficult to control the basis weight when the line speed is around 240 to 260 m/min, and this upper limit was determined.

■Wire ~ E (Y = 80001 il)... If it is higher than this, even if it does not protrude from the surface, the effect of preventing C 9 and runout of the board will be very weak.

...This is because the Zn solidification position becomes lower as the line speed becomes slower.

■Line F-A (X) D m/min)...There is no lower limit for line speed. However, in the example of a hot-dip galvanizing line, if the line speed is slower than 20 mpm, there will be less Zn to pull up and the amount of gas to be squeezed out from the injection nozzle will be smaller, making it difficult to obtain a beautiful surface.

FIG. 2 shows an embodiment of the apparatus of the present invention, in which 1 is a threaded strip, 2 and 2' are support rolls, 3 and 3' are injection nozzles, 4 and 4' are bath support rolls, and 5 is a This is a zinc roll, Y is the height from the tip of the injection nozzle 8, 3' of the support roll of the present invention, and h is the position at which solidification of the plated metal is completed. In a normal hot-dip plating line, the tips of the injection nozzles 3 and 3' are located at a distance of 100 mm to 250 mm from the bath surface. The materials used for the support rolls 2 and 2' are water-cooled stainless steel heat-resistant rolls;
Alternatively, use a ceramic spray roll or the like.

In addition, in the present invention, the roll may be driven or not driven (≦2
00 mm), the use of a backup roll,
This does not exclude application to single-sided plating equipment that uses a plating inhibitor, and furthermore, application to hot-dip plating equipment that has a remelting device for alloying processing.

However, the present invention is particularly effective when employed in plating equipment that does not have a remelting treatment (alloying treatment) device that requires strict requirements for surface properties.

EXAMPLE The support roll was installed at a position within the preferred range according to the present invention. That is, when operating at a line speed of 80 mpm, when the support roll was placed at a position 500 mm above the bath surface, the plated metal surface was smooth and beautiful, and the deflection of the strip was reduced, so that the injection When the nozzle was able to approach the strip up to about 5 mm, and the amount of plating deposited was reduced with a gas injection pressure of 1"/cry?',
One side! It was possible to reduce the weight to 1122jl', p·, and an ultra-thin basis weight was achieved.

For comparison, we installed a support roll at a position 5 mm above the bath surface where the zinc solidifies, as in the past, in an attempt to obtain a smaller amount of zinc, but the distance between the copper strip and the injection nozzle was S) For IJgu's Fureyawan song, ], Q mm
In the case of zinc plating, the minimum coating weight was 30 g/m2 (on one side).

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, as described in detail, the support roll can be installed at a position close to the injection nozzle.
This prevents plate wobbling and deformation in the plating coating control area caused by the injection gas, and allows the injection nozzle to be brought close to the IJ surface, resulting in ultra-thin coating weight and beautiful plating on the surface. A surface is obtained.

[Brief explanation of the drawing]

FIG. 1 is a route map showing an example of a conventional device, FIG. 2 is a route map showing an example of the plating coating amount control device of the present invention, and FIG. 3 is a route diagram showing an example of the support roll arrangement position according to the present invention. This is a graph showing. l...Strip 2, 2'/Support roll 3.3
'...Injection nozzle. Patent applicant Kawasaki Steel Co., Ltd., applicant Kawasaki Steel Sheet Co., Ltd. TLJ, 1. Written by patent attorney Ko Sugimura. Figure 1 Figure 3 Line suit (Mh side)

Claims (1)

[Claims] L In a plating deposition amount control device in a hot-dip metal plating facility, which has a gas wiper on the bath surface along the passing path of the strip to be plated, the gas wiper on the bath surface and the attached plating metal complete solidification. Along the passage path of the strip between the positions A and B of the melt water in Figure 3
, C, D, E, and F. 1. A plating example landscape control device in molten metal plating, characterized in that a support roll is disposed within an area surrounded by C, D, E, and F.