JPS59118869A - Adjusting method of spangle in galvanization - Google Patents

Abstract

PURPOSE:To change and adjust instantaneously the level of the spangle in galvanization by melting a Pb metal into the plating layer covering a strip right after pulling from a low Pb zinc alloy bath. CONSTITUTION:A spangle adjuster 8 is installed on both sides of a strip 1 to be pulled up, at the position right above at low Pb molten zinc bath 4 in a continuous galvanizing line. The Pb metal 10 unwound from the coled strip 9 of the Pb metal is supplied through a supply adjuster 11 and a support 12 in the adjuster 8, and is brought into contact continuously with the melting plating layer covering the strip 1, so that it is melted into the plating layer covering the strip. The transfer speed of the metal 10 is changed by adjusting the device 11 whereby the fluctuation in the size of the spangle is prevented.

Description

[Detailed Description of the Invention] The present invention relates to a spangle adjustment method for hot-dip galvanizing.
In particular, it relates to a spangle adjustment method for hot-dip galvanizing that can easily and arbitrarily change the size of spangles (crystalline patterns of zinc) that appear on the surface of hot-dip galvanized strips (steel plates, etc.) on a continuous galvanizing line. .

A needle-shaped zinc crystal pattern called a spangle appears on the surface of the hot-dip galvanized coating on a strip material such as a steel plate. It is known that the size of this spangle changes depending on the components in the zinc plating bath. In particular, lead (Pb) has a large effect on the size of spangles7, and as shown in Figure 1, the spangles become smaller as the Pb content decreases.Therefore, the minimum spangle plating surface (Z As one method to obtain a product in which the crystals of ?L are so fine that the spangles are so small that the crystal pattern is hardly noticeable, it has been carried out to lower the PB content in the molten zinc bath. There is.

However, in this conventional method, in order to manufacture plated surfaces with different spangle sizes, such as regular spangles (products with large spangles) and minimum spangles, on the same line, the Pb content in the zinc bath must be readjusted each time [
7, whose implementation is extremely IAIfi I,
stomach. In other words, in an industrial-scale continuous galvanizing line, each part of the zinc bath weighs several tens of tons, so the amount of Pb-containing deposits is either high (for regular spangles) or low (for regular spangles).
In order to change to (for minimum spangle) or vice versa, it is necessary to change the noisy zinc ingot used in the zinc bath to one with a different Pb content, which is extremely difficult to implement. be. Another method is to adjust the Pb content meter by adding Pb metal into the zinc bath, but even with this method, if the Pb content meter is to be decreased, it is necessary to replace the entire zinc bath. When increasing the content, it is possible to add Pb ingot and omit replacing the ready lead bath, but it still takes a long time and is difficult to implement.

In this way, the method of changing the Pb content meter in the zinc bath requires a long time to change, and if line operation continues during this time, a plated product with different spangle sizes will result, resulting in a large amount of damage. There is a problem that loss occurs. Although it is possible to stop the line while replacing the zinc bath, it is extremely uneconomical and extremely difficult to implement as a practical matter because the replacement process requires a large amount of time as described above.

The object of the present invention is to eliminate the drawbacks of such conventional spangle changing methods and to provide a method for galvanizing that can instantly change and adjust the level of Pb-containing spangles in hot-dip galvanizing in an industrial-scale galvanizing line. An object of the present invention is to provide a spangle adjustment method.

The feature of the present invention is that the Pb base metal is dissolved in the IJ tube coating plating immediately after being pulled out of the zinc bath, which is suitable for obtaining minimum spangles, and is still in a molten state. It is about achieving a goal.

That is, according to the present invention, a continuous galvanizing line with low Pb
A method for adjusting spangles in hot-dip galvanizing is provided, which comprises adjusting the size of spangles by dissolving a Pb ingot in a molten strip coating layer pulled up from a zinc bath.

The present invention will be described in detail below with reference to FIGS. 2 to 4.

First, a specific example of a hot-dip galvanizing process in a continuous galvanizing line will be described with reference to FIG.

In Fig. 2, the IJ tube 1 is surface-cleaned by pretreatment such as degreasing or washing, and then guided to the town down roll 2 to form a snout (tube-like conduit).
3 and is continuously fed into the molten zinc melt 4. A zinc roll (bot roll) 5 is installed in the molten zinc bath 4, and the strip 1 is fed upward around the zinc roll 5 to a differential V-ctor roll installed above the molten zinc bath 4. The IJ tube is continuously fed to the subsequent process by 6 and is coated with lead while passing through the molten zinc bath 4. A gas throttle device R (gas wiping device) 7 installed at a lower position controls the adhesion of zinc on the surface of the sheet, and then the zinc is sent to the deflector roll 6. Further, the aforementioned self-molten zinc bath 4 is a low-Pb zinc bath suitable for removing minimal Pb particles.

Therefore, at a position below the gas throttle device 7 and directly above the melting capacity lead bath 4, a continuous galvanizing line with a low P
(b) A spangle adjustment device 8 is installed for dissolving the Pb base metal into the strip coating plating layer which has been pulled out of the zinc bath and is still in a molten state.

FIGS. 3 and 4 are diagrams illustrating the structure of the snow knuckle adjustment device.

In FIGS. 3 and 4, a strip-shaped Pb ingot 1 is unwound from a coil-shaped Pb ingot strip 9.
0 is fed through the supply adjustment device 11 and the support 12, and is arranged so as to continuously contact the coating layer of the strip L in the dissolved state and dissolve into the coating layer. In the illustrated example, the spangles are installed on both sides of the above-mentioned snow knuckle adjustment equipment strip 1, so that the spangles of the galvanized layers on both sides can be adjusted.

The supply adjustment device 11 has a feed roll structure consisting of a pair of rotating rolls, and adjusts the rotation speed of the rolls.
It is possible to use a type in which the supply mechanism and transfer speed of the strip-shaped Pb ingot can be adjusted by adjusting λ.

Different spangles can be formed on both sides of the strip 1 by differentiating the PB metal supply experience of each spangle adjustment device placed on both sides of the strip 1, and it is also possible to form different spangles on both sides of the strip 1. By installing it, it is also possible to make one side a L/Gulars bangle and the other side a minimum spangle with molten nfj lead from the molten zinc bath 4 attached.

As explained above, the melting capacity lead bath 4 is always adjusted to the minimum spangle component with a small Pb content, and the spangle adjustment device 8 dissolves the Pb base metal into the plating layer of the strip to be considered in the molten state. By adjusting the melting point, it is possible to form various types of plated coating layers ranging from minimum spangles to regular spangles of any size. As shown in FIG. 4, the IJ tube-shaped Pb metal is pressed against the entire width of the plating surface so that it can be continuously fed.

Also, if the threading speed of strip l changes,
By adjusting the supply speed of the strip-shaped Pb ingot 10, fluctuations in the size of the spangles can be prevented and spangles of a stable size can be obtained.

In this case, since Pb has a lower melting point than zinc, the dissolution rate of the Pb ingot is fast; therefore, (i) the spangle test can be quickly adjusted by controlling the feeding test of the IJ tube-shaped Pb ingot; This makes it possible to form a plating coating layer having the desired spangle quality in a continuous and stable state.

When changing from minimum spangle to regular spangle, strip-shaped P6 base metal 1O is brought into contact with the hot-dip galvanized layer, and when changing from regular spangle to minimum spangle, strip-shaped Pb
It is only necessary to separate the base metal 10, and in any case, the Pb-containing liver in the galvanized coating can be precisely #A adjusted at 1 o'clock.

In other words, it is possible to perform the process independently on both sides of the strip l, and it is also possible to easily make one side a minimum spangle and the other side m1 a regular spangle of a predetermined size, and furthermore, Regular spangles with a width of m are shaped (or shaped freely) on each side.

Next, test examples in which the spangle adjustment method of the present invention and the conventional method (without any spangle adjustment) will be explained based on data.

In a continuous 1L lead plating line, a plate of 11.3 M and a plate width of 1,200 km was used.IJ Tsububayashi's Pb metal was incorporated into the equipment shown in Figures 3 and 4, and the plate width was 0.5η with a plate thickness of 0.5η. 914D /d81 strip at line speed 110
Hot-dip galvanized with Illi+in. Differences in spangle size and Pb content in the plating film when the spangle adjustment method according to the present invention was implemented and when it was not used were as shown in Table 1.

In the test examples shown in Table 1, the Pb content in the molten zinc bath was 0.01% or less, and the strip-shaped Pb ingot was electrolytic lead with 100% Pb.

Furthermore, when the snogle adjustment device used in the above test example was used, switching to regular snogle could be instantaneously performed, and the resulting product also had uniform spangles.

In addition, in the above test example, the feed stage of the IJ tube-shaped Pb metal was 0.15 g/mtn, and the molten zinc bath 4
The bath temperature was 460°C. Furthermore, the melting temperature of zinc is 420°C and the melting temperature of lead is 328°C, but the temperature of the unsolidified plating layer of molten zinc at the position where the strip-shaped Pb ingot 10 is brought into contact is 440°C. there were.

When Pb metal is brought into contact with the 11machi lead plating layer, which is still in a molten state above its melting temperature, the melting temperature of lead is 3.
Since the temperature is quite low at 28° C. and lead forms a solid solution with zinc, the melting rate and diffusion rate of lead are fast, and lead can be instantly melted into zinc. Thereafter, during the cooling process of the zinc, the spangles grow to form spangles of a desired size.

Note that when the spangle adjusting device 8 is directly installed very close to the level of the molten zinc bath 4, since the galvanized layer 13 is still in a molten state, the molten Pb ingot passes through the plating layer and spreads out the zinc. It is conceivable that the Pb content in the zinc bath may change by flowing back into the molten bath 4, but according to the test results of the present inventors, it takes a very long time before the Pb content in the zinc bath increases. Although it took some time, it turned out that there was no practical problem at all. For example, in the above test example, the Pb content in the molten zinc bath at the beginning of the test was 0.01% or less, but after the above spangle adjustment was performed continuously for 12 hours, the Pb content in the zinc bath was The increase was about 0.03 inches.

As is clear from the above description, according to the present invention, there is provided a spangle adjustment method for hot-dip galvanizing that can quickly and accurately adjust the spangle size in a strip coating plating layer.

[Brief explanation of the drawing]

Figure 1 shows Pb in the molten zinc bath when the present invention is not implemented.
A graph illustrating the characteristics of the spangle size of the plating surface with respect to the content meter, Fig. 2 is an explanatory diagram illustrating the continuous hot-dip galvanizing process to which the present invention is applied, and Fig. 3 is a graph showing the spangle adjustment method according to the present invention. FIG. 4 is a schematic side view illustrating the apparatus of the invention, and FIG. 4 is a schematic front view taken along line IV-IV in FIG. 3. 1... Strip, 4... Molten zinc bath, 5
... Zinc roll, 7... Gas squeezing device (gas wihing device), 8... Suno (nangle adjustment device, 9... Coiled Pb bullion store soap,
10... Pb metal in the shape of a stop, 11...
- PbJt gold supply alignment device, 12... Support, 13... Galvanized layer in molten Mffl state. Agent Tatsuyuki Unuma (and 2 others)

Claims (3)

[Claims] (1) Pb in the strip coating plating layer in the molten state pulled up from the low pb zinc bath of a continuous galvanizing line.
A method for adjusting spangles in hot-dip galvanizing, characterized by adjusting the size of spangles by melting base metal. (2) Spangle of hot-dip galvanizing according to claim 1, characterized in that the strip-shaped Pb base metal is continuously supplied and melted while being in contact with the strip coating plating layer in a molten state. Adjustment method. (3) By melting the Pb metal only on one side of the strip, one side becomes a regular spangle and the other side becomes a minimum spangle. How to adjust the spangle of hot-dip galvanizing.