JPH02104649A - Method for supplying component into plating bath - Google Patents

Abstract

PURPOSE:To rapidly inhibit fluctuations in the concentration of components in a plating bath and to stably obtain superior plating quality by supplying components from plural premelting pots via a mixing tank and a spray nozzle provided in a plating bath. CONSTITUTION:Premelting pots 8, 9 are disposed in the side part of a plating bath 1, in which molten Zn 9, molten Al 11, etc., as supplementary components are stored, respectively. A pump 16 is worked, and a molten metal 2 in the plating bath 1 is formed into s state of circulation via a mixing tank 17 and a spray nozzle 19. Pumps 12, 14 are worked to discharge the molten metal components 9, 11 into conduits 13, 15, respectively. These supplementary components 9, 11 are introduced into the mixing tank 17 and mixed with the molten metal 2 in the tank 17. The resulting mixture is sprayed into the plating bath 1 via a connecting pipe 18 through the spray nozzle 19. Respective amounts of the components 9, 11 discharged from the premelting pots 8, 10 are regulated according to the required supplementary concentrations of the components 9, 11 and the amount of decrease in the quantity of the plating bath 1.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for replenishing components to a plating bath in continuous hot-dip metal plating.

<Prior art> In continuous hot-dip plating, a continuously running copper strip is immersed in a bath of molten plating metal for a predetermined period of time, and then gas wiping is applied to the surface of the copper strip taken out of the plating bath to form a predetermined coating. It is a plating method that applies desired plating to the surface of a steel strip by adjusting the coating weight, and hot-dip galvanizing is a typical example.

Originally, galvanized steel sheets were used as building materials due to their excellent corrosion resistance.
Widely used as steel sheets for home appliances and automobiles, hot-dip galvanizing currently has inferior surface quality compared to electrogalvanizing, but it consumes less energy, the cost of molten metal for plating is lower, and it is easier to use. It is attracting attention in the mass production of galvanized steel sheets because it can be made thicker.

By the way, in continuous hot-dip galvanizing, in addition to using a pure zinc bath, hard and brittle Fe-
AJ2 may be added to the zinc bath in order to suppress the growth of the Zn alloy layer (r phase: Fe5Zn2+) and improve plating adhesion. That is, by forming an Al-enriched layer (Fe2An6, etc.) at the interface between the plating layer and the base steel, the Fe-Zn alloy layer at the interface between the zinc and the base steel is moderately suppressed, and the peeling of the plating layer is prevented. (powdering).

In addition to the above addition of An, a small amount of PB may be added to form spangles (flower pattern 2M) on the plating surface, and the addition rate of AJl and PB may vary depending on the purpose of the galvanized steel sheet. It's different.

In such continuous hot-dip galvanizing, the components (Zn, All, Pb) in the plating bath are i) carried out by the plating layer adhering to the surface of the steel strip, and ii) the formation of floating dross and its exit from the plating bath. It is necessary to replenish the reduced components to the plating bath.

A conventional method of replenishing components to a plating bath will be explained below.

First, the composition of the hot-dip galvanizing bath and the supplementary components (ingot) are shown in Table 1 below. Note that hot-dip galvanized steel sheets generally include not only pure zinc plating baths but also steel sheets having bath compositions as shown in Table 1.

Table 1 To give a representative explanation of the varieties Gl and GA in Table 1 above, when the liquid level in the rinsing bath decreases, about 1 ton of 0.
As a result of putting an ingot of 3~0.5wt% A41-Zn alloy into a plating tank and analyzing the bath components over several hours, it was found that as the A2 concentration decreased, one
Ingredients were replenished by putting an appropriate number of ingots of 10 wt % AIL-Zn alloy into a plating tank (for example, see Japanese Patent Laid-Open No. 62-238358).

The reason for introducing the A11-Zn alloy ingot with a higher AJZ concentration than the target AJ2 concentration of the bath components is to reduce Zn in the plating bath due to the formation of the AJ2-enriched layer (Fe2Aj2a, etc.) and floating dross as described above. A than rate
This is because the rate of decrease of 1 is greater.

<Problem to be solved by the invention> However, in the above replenishment method by feeding ingots,
It takes time for the ingot put into the plating bath to melt and spread in the bath to form a uniform plating bath (the larger the weight of the ingot, the longer it takes), and it also takes time for the ingot to melt and spread in the bath. Since the AIL concentration in the bath continues to decrease from until the next time of charging, the AIL concentration in the plating bath varies greatly depending on the pitch at which ingots are charged (several hour intervals).

If the AJ2 concentration in the plating bath fluctuates in this way, the uniformity of the AfL-enriched layer mentioned above will be impaired, making it impossible to obtain stable plating quality, and in continuous hot-dip galvanizing, the AJZ concentration in the plating bath will change. The number of plated areas that deviate from the target value increases, leading to a decrease in plating quality.

In addition, in the conventional component replenishment method described above, the relationship with the cleaning conditions is not taken into account, and moreover, the Al2 content is constant.
1-For charging Zn alloy ingot, any AIl
It is not possible to replenish the components at high concentrations, and AJ2 in the plating bath
It is not possible to finely adjust the density.

In recent years, hot-dip galvanized steel sheets have become popular due to their low manufacturing costs.
It is expected that it will be applied to mass-produced automobile exterior panels, but for this purpose, it is necessary to have excellent plating adhesion even during deep drawing by press forming, and therefore, the above-mentioned appropriate A1 Formation of an enriched layer is essential. Therefore, it is necessary to more strictly control the A1 concentration during plating.

Taking these points into consideration, the conventional component replenishment method by adding ingots requires 1. There is a limit to reducing fluctuations in Au concentration, and it has not been possible to stably obtain satisfactory plating quality.

In contrast, the present inventors have discovered that by first replenishing components from multiple pre-melt pots, fluctuations in the concentration of components in the plating bath can be suppressed and good plating quality can be stably obtained. Patent application for method of replenishing ingredients to plating bath in 1982-32
No. 4717.

However, even if such a component replenishment method is used, when replenishing Zn and A1 in a molten state from each Brimeltbot 8.10 to the plating bath 1 as shown in FIGS. 8 and 9, for example, each conduit 13. Input port 131 at the tip of 15.
151 at different positions, the problem of the concentration distribution of Zn and Afl in the plating bath 1 becoming non-uniform as shown in the graph of FIG. 10 is avoided.

That is, at the 5 points near the AIL input port 151, the A1 concentration exceeds the upper control limit every time the An supplement is indicated by the arrow, and at the point near the Zn input port 131, the AJ concentration exceeds the upper control limit every time the Zn supplement is indicated by the arrow.
Since the concentration of AI2 decreases, the steel strip 6 to be plated in such a footbath 1 will have an AI concentration in its width direction and longitudinal direction.
Since it passes through plating baths 1 with different concentrations, variations occur in the plating quality.

An object of the present invention is to provide a method for replenishing components to a plating bath that can solve the above-mentioned problems, suppress concentration fluctuations of components in the plating bath, and stably obtain good plating quality. .

<Means for Solving the Problems> In order to achieve the above object, according to the present invention, in a method for replenishing components to a plating bath when hot-dip plating is performed in a plating bath containing a plurality of components, replenishing components are added in advance. Using multiple molten pre-melt pots, the molten replenishment components from the pre-melt pots are replenished and mixed into a mixing tank installed in the plating bath in order to correspond to the required replenishment concentration and the amount of reduction in the plating bath. There is provided a method for replenishing components into a plating bath, characterized in that the mixture is injected into the plating bath from inside using a spray nozzle to replenish the components.

Further, according to the present invention, in a method for replenishing components to a plating bath when performing hot-dip plating in a plating bath containing a plurality of components, at least one pre-melt pot in which replenishment components are melted in advance and a metal of the replenishment component are provided. Using at least one hopper containing lumps or metal powder particles, replenish and mix the molten replenishment components from the pre-melt pot into a mixing tank located within the plating bath to match the required replenishment concentration and plating bath reduction. There is also provided a method for replenishing ingredients into a plating bath, which comprises injecting the mixture from inside the mixing tank into the plating bath using an injection nozzle and supplying the ingredients into the plating bath from a hopper. Ru.

In these inventions, it is preferable that the necessary replenishment concentration and the amount of reduction in the plating bath be determined by the plating conditions.

EMBODIMENT OF THE INVENTION Hereinafter, the method of replenishing components to a plating bath according to the present invention will be described in detail with reference to preferred embodiments shown in the accompanying drawings.

FIG. 1a and FIG. 1b are side views schematically showing an example of the configuration of equipment for carrying out the method of replenishing components to a plating bath according to the present invention.

In the plating bath 1, the annealed steel strip 6 coming out of the snout 7 is immersed in the molten metal for plating (for example, molten zinc) 2 by the zinc roll 3, and then straightened by the collecting roll 4 and stabilized. After being stabilized by stopping the rocking by the rising roll 5 and being pulled up from the molten metal for plating 2, it is adjusted to a predetermined plating area weight by gas wiping (not shown).

In this way, the steel strip 6 is continuously coated with hot-dip metal.

When performing hot-dip galvanizing, as mentioned above, it is possible to add A1 to the plating bath to improve plating adhesion, or to add a small amount of PB to form spangles on the plating surface. be exposed. Therefore, the composition of the molten metal 2 for plating is Al1-Zn-based or Al1-
It is a Pb-Zn type, etc., and the addition rate of AIL and PB is appropriately determined depending on the use, type, etc. of the galvanized steel sheet to be manufactured.

Fallen tree, l) Composition of molten metal 2 for sewing is 0, 0
1 ~ 0. 2wt% Pb-0,1~0. 2
Galvanized steel sheet or alloyed galvanized steel sheet (G1.GA) which is wt%Aj2-Zn alloy, il) Zinc-aluminum alloy coated steel sheet whose composition of molten metal 2 for plating is 5wt%AfL-Zn alloy. (GALFAN),
Or fit) The composition of molten metal 2 for plating is 1.4wt%SL
-55wt%An-43.6wt%Zn zinc-aluminum alloy plated steel sheet (GALVALUME), etc.

The uses of i) are mainly for building materials, home appliances, and automobile interior panels, and the uses of if) and 1ff) are mainly for building materials.

In such continuous hot-dip galvanizing, take-out due to the galvanizing layer adhering to the surface of the steel strip 6 and floating dross are generated, and by removing this from the plating bath, the liquid level of the molten metal 2 for plating is lowered. descend. Therefore, it is necessary to replenish so as to keep the liquid level constant and to keep the composition of the molten metal 2 for plating constant at the target value.

In addition, the floating dross is molten gold for Fe potting, which is eluted from steel F6! Combines with A1 in Z to form Fe, Al2. This is what has floated to the surface of the plating bath (having a specific gravity smaller than the molten metal 2 for plating), or what has been oxidized by zinc on the bath surface.

In addition, the decrease in the molten metal 2 for plating does not mean that each component (Zn, AIt, Pb) of the molten metal 2 for plating decreases in proportion to its content (concentration), that is, the decrease in A1. Regarding this, since an AJ2-enriched layer (Fe2AIL, etc.) is formed at the interface between the base steel and the plating layer, the AJ2 concentration in the takeout is higher than the An concentration in the molten metal 2 for plating, and the wiping bath is The composition of the floating dross removed to the outside is Al1-Fe = 2 to 4 wt% and the balance Zn in the molten metal 2 for plating with an A1 concentration of 0.1 to 0.2 wt%. The decrease in A1 concentration is remarkable compared to other components.

Therefore, replenishment of components to the plating bath is necessary for molten metal for plating.
As a result of replenishing the amount so that the liquid level reaches the target value, rather than at a concentration equal to the composition of molten metal 2 for plating,
It is also necessary to adjust the composition to the target value.

In the present invention, components are replenished into the plating bath as follows. As shown in Fig. 1a, pre-melt pots 8 and 10 are installed on the sides of the rice-melting temperature 1, and the pre-melt pot 8 contains molten Zn9 obtained by melting an ingot, pre-melt Bot 10 contains molten Aj obtained by melting an ingot! 11 are stored.

A mixing tank 17 is provided in the plating bath 1 and has a structure that allows the molten metal 2 in the bath to be sucked in. A pump 16 is provided above the plating bath 1, and a connecting pipe 18 is provided from the pump 16 A spray nozzle 19 is provided through the pipe.

Between each pre-melt bot 8.10 and the plating bath 1, a conduit 13.15 is provided with its tip facing into the mixing tank 17 via each pump 12.14.

When replenishing the components, first operate the pump 16 to circulate the molten metal 2 in the plating bath 1 through the mixing P117 and the injection nozzle 19, then operate the pumps 12 and 14 to circulate the molten Zn9 and molten AfLit. Discharge into conduits 13 and 15, respectively. , .

At this time, molten Zn or molten AfL in the conduit 13 or 15 is introduced into the mixing tank 17, mixed with the molten metal 2 in the tank, passes through the connecting pipe 18, and is injected from the injection nozzle 19 into the metal bath i. It is necessary to operate pump 16 more strongly than pumps 13 or 15 so that the

Further, the pump 16 may be operated not only when replenishing the components but also at all times.

The injection nozzle 19 is not particularly limited, and may be made of a material that can withstand the molten metal 2 in the plating bath 1.
As clearly shown in FIG. 1a, the shape of the copper strip is preferably substantially parallel to the steel strip 6 and extends a required length in the width direction of the copper strip.

Replenishment of such components is carried out by adjusting the amount discharged from each pre-melt bot 8.10 to correspond to the above-mentioned required replenishment concentration and reduction amount of the plating bath. In addition, when the molten metal 2 for plating is a binary alloy, at least two pre-melt bots are required in order to replenish the components to correspond to the required replenishment concentration and the amount of decrease in the plating bath. Molten Zn from each Primeltbot 8.10
9 and the amount of molten A111 to be fed is adjusted using pump 12.
This can be done by using a pump capable of controlling the flow rate in 14, or by providing a flow control valve (not shown) in the middle of the conduit 13.15.

In addition, the form of replenishment may be either continuous replenishment, in which replenishment is performed at any time during plating, or intermittent replenishment, in which replenishment is performed at predetermined intervals. The forms may be different. In addition, when performing intermittent replenishment, it is preferable that the replenishment pitch be as short as possible, since concentration fluctuations in the molten metal 2 for plating will be reduced.

When the liquid level of the pre-melt bot 8.10 decreases, a Zn ingot and an Al1-Zn alloy ingot are respectively introduced into the pre-melt bot 8.10 to compensate for the decrease.

The conduits 13.15 are preferably heated and maintained at a temperature above the melting point of the metal passing through them so that molten metal does not solidify within them and cause blockages.

In this way, when replenishing the components to the plating bath 1 by charging molten metal, there is an advantage that fluctuations in the bath temperature of the plating bath can be suppressed compared to the conventional method of charging ingots.

Melt Zn9 and Melt A from Brimeltbot 8.10
The means for replenishing the plating bath 1 with 111 is not limited to the method using the pumps 12 and 14 described above.

That is, as shown in FIG.
Molten metal 9,! It is also possible to introduce the molten metal 9.11 into the plating bath 1 by inserting a spacer 20 into the plating bath 1 to raise the liquid level and cause it to overflow.
In this case, the amount of molten metal 9.11 introduced is adjusted by the amount of spacer 20 inserted.

In addition, as shown in Figure 3, the pre-melt pot 8.10
It is also possible to make the container a closed type, send high-pressure gas into the pre-melt pot 8.10 using the compressor 21, and use the pressure to push out the molten metal 9.11 in the pre-melt pot and throw it into the plating bath 1.

Note that the A1 component of the plating bath 1 is generally replenished with a molten Aft-Zn alloy instead of molten AIL, and the reason is as follows.

The bath temperature of the plating bath 1 is such that the composition of the molten metal 2 for plating is 0.
For 1-5 wt% AJZ-Zn alloy, about 450-48
0° C., but since the melting point of AJ2 alone is 660° C., when molten A1 is poured into the plating bath 1, it solidifies. On the other hand, if AIL-Zn alloy is used, its melting point will be lower (the melting point of 10 wt% AJZ-Zn alloy is 4
30°C), and there is no inconvenience of coagulation occurring when it is put into a plating bath. Therefore, in the present invention, when replenishing a metal component having a melting point higher than the bath temperature,
The metal is alloyed with another metal, especially the main component metal (zinc in this example), and the melting point is lowered, preferably below the bath temperature, and the alloy is added to the plating bath. is preferred.

As shown in FIG. 5, pre-melt pot A contains molten Zn, pre-melt pot B1 contains molten AfL, and pre-melt pots C and D%E% each contain molten AfL-Zn alloys with different Ai concentrations. F is provided,
1 or 2 of pre-melt pot A%C%D, E%F
It is also possible to arbitrarily select any of the above and charge an appropriate amount of molten metal from each of them into the plating bath 1.

When the liquid level of any of Brimeltbots C, D%E, and F decreases, predetermined amounts of molten Zn and molten AIL from Brimeltbots A and B are respectively charged into the premelt pot. For example, when replenishing Brimelt Bot C, the respective input amounts from Premelt Pots A and B are adjusted to be equal to the Aj2 concentration of Premelt Pot C.

When the composition of the molten metal in each pre-melt pot is as shown in Table 2 below, Table 3 below shows an example of replenishment from each pre-melt pot to the plating bath with respect to the composition of the plating bath.

Table 2 Table 3 FIG. 4 is a side view schematically showing another example of the configuration of equipment for carrying out the method of replenishing components to a plating bath according to the present invention. In the equipment shown in the figure, pre-melt pots 8 and 10 similar to those described above and a hopper 22 containing metal powder grains 24 as a supplementary component are installed, and a pre-melt pot 8 is placed in the same manner as described above.
and 10 to melt Zn9 and melt A11, respectively.
1 is thrown into the plating bath 1, and at the same time, a predetermined amount of metal powder particles 24 are thrown into the plating bath from the hopper 22. A blade (rotary feeder) 23 is installed at the opening at the lower end of the hopper 18, and as the blade 23 rotates, a fixed amount of metal powder particles in the hopper are cut out and thrown into the plating bath 1.

Note that, unlike the illustration, the hopper 22 is installed at a position a considerable distance am from the plating bath, and the metal powder particles 24 cut out from the hopper 22 are conveyed by a conveyor, and the plating bath 1
It is also possible to input it into

In hot-dip galvanizing, a small amount of PB may be added to the molten metal 2 for plating in order to form spangles on the plating surface, as described above. That is, the composition of the molten metal 2 for plating is a Pb-A11-Zn alloy, and the pb acid component can be replenished by introducing metal powder particles 24 using pb grains. Note that the melting point of pb is 327 ° C. Since the bath temperature is lower than the bath temperature (450 to 480°C) of plating bath 1, the PB particles introduced into plating bath 1 quickly melt and diffuse.

The particle size of the metal powder particles 24 is not particularly limited, but is preferably about 1 to 10 liters. If it is less than 1 am, minute particles will float in the air and easily adhere to the copper strip.
This is because if it exceeds 0 m1, the accuracy of density adjustment becomes rough. Note that the metal powder particles 24 are not limited to PB particles, but may also be Pb-Zn.
It may be alloy grains or powder grains of other metals or alloys.

In such equipment, when the molten metal 2 for plating is a binary alloy, at least one pre-melt pot and one hopper are used to replenish the necessary replenishment concentration and components corresponding to the decrease in the plating bath. It's good to have one each.

In the present invention, the amount of component replenishment may be determined by, for example, a method in which bath components are analyzed in a timely manner and based on the analyzed values, or a method is determined based on estimated values determined empirically. Although it is possible, it is preferable to determine the necessary replenishment concentration and the amount of decrease in the plating bath based on the plating conditions, and replenish the components based on this, as described below.

The present inventors have determined that the plating bath composition is 0.05 to 0.20 wt%
As a result of conducting experiments and discussions to investigate the relationship between the amount of decrease in the A1 component and the plating conditions regarding hot-dip galvanizing using Afl-Zn, the following findings were obtained.

■ Ai-enriched layer (Fe2
Aj! , etc.), the Aft concentration in the plating layer is higher than the A1 concentration in the plating layer. Furthermore, the An concentration in the plating layer is not always constant with respect to the amount of deposited plating, but is a function of the amount of deposited plating as shown in FIG. Therefore, the amount of reduction in AJZ due to carry-out can be known from the amount of plating deposited.

■ The main component of floating dross is Fe, which is formed by the combination of Fe eluted from the copper strip and AJ2 in the plating bath.

A1. As a result of analyzing the components of this dross, it was found that Aλ = Fe = 2 to 4 wt%, and the balance was Zn.

The amount of decrease in the A1 component due to floating dross generation is equal to the amount of Fe eluted from the copper strip, and by understanding this, it is possible to know the amount of decrease in Ai due to floating dross.

From the above (1) and (2), the total decrease in Zn and AIL in the plating bath is expressed by the following formula.

Aj2 total decrease amount - f (V, B, C, θ, W) Zn total decrease ffi”g (V, B, C, θ, W) ■Niline speed B: Plate Width C: Rakuchu AIl concentration θ: Intrusion plate Warm W: Decreased amount of Zn, A, and Q in the cleaning bath and Z from the coating amount or more
The reduction rate of n and AIL is determined by the plating conditions (plating amount,
It was found that it can be determined by the plate width, line speed, plate temperature, etc.).

Conventionally, the AIL concentration (
In this method, an A11-Zn alloy ingot with a certain content (content ratio) was simply put into the plating bath, and the replenishment concentration of A1 was not changed depending on the plating conditions. In contrast, with the present invention, which determines the necessary replenishment concentration of bath components and the amount of reduction in the plating bath based on the plating conditions, it is possible to replenish the components more appropriately, and the concentration of each component in the plating bath can be controlled within a narrower range. It can also be limited to plating conditions (
Even if the coating weight, plate width, line speed, plate temperature, etc. change, it can be accommodated.

Generally, there are n (n≧2) Brimelt pots, and C
n is the concentration of the specific component in the nth Brimelt pot, Q
If n is the supply amount from the nth Brimelt pot, then
The required replenishment amount Q'' and the required concentration C'' are expressed by the following equations.

Q''” Q I+ Q 2+ ” ” Q nThis Q”
, C' are determined from the plating conditions, and their Q", C"
Replenishment may be performed by adjusting Q1 to Q so that the value becomes .

Above, the method of replenishing components to a plating bath according to the present invention has been typically explained for hot-dip galvanizing containing an Al acid component, but the present invention is not limited to hot-dip galvanizing, for example, hot-dip tin plating,
It can be applied to all types of molten metal plating such as tin-lead alloy plating and molten aluminum plating.

<Example> (Example 1 of the present invention) Hot-dip galvanizing was performed under the following conditions using equipment having the configuration shown in FIGS. 1a and 1b.

Plating bath composition: 0.15±0. Otwt%AfL (objective straight) -Zn
First pre-melt pot composition: Pure Zn Second pre-melt pot composition + 2wt% AJ2-Zn alloy plating conditions Plate width: 1200 mm Line speed: 120 m/+l1in Plating coverage (one side): 90 g/rn' Calculated from these plating conditions: The amount of reduction in plating bath is 30 kg/win.

Therefore, 21 k of pure Zn from the first Brimelt pot
g/min, 0.2wt%A from the second Brimelt pot
J2-Zn was supplied at a rate of 9 kg/min. In addition, the form of replenishment is such that Zn is supplied to the above-mentioned amount on average.
: 630g and 2wt% An-Zn:210g were applied intermittently at a pitch of 30 minutes. In addition, the conduit between each Brimelt pot and the plating bath is heated by a heater to prevent the molten metal from solidifying in the tube.
It was heated to 80 tons.

Regarding the above-mentioned Invention Example 1, G during the rice paddy temperature shown in Fig. 1a
, the time course of AIL concentration was investigated at point H. G
, the variation in AJ2 concentration at point H is σ 0.002
It was ~0.003. The results are shown in the graph of FIG.

(Comparative Example) The plating bath composition and plating conditions were the same as those of Inventive Example 1, and molten Zn and molten AiL were intermittently introduced into the plating bath using the equipment shown in FIGS. 8 and 9. The ingredients were replenished. Note that everything except the component replenishment equipment was the same as in Example 1 of the present invention.

Regarding the above comparative example, the change over time in the AJ2 concentration was investigated at the 3% point in the plating shown in FIG. This 3%
The points were located at the same positions as points G and H in Inventive Example 1, respectively.

The variation of A111 degrees at point J is 0.00 in σ
It was 5 to 0.006. The results are shown in the graph of FIG.

Figures 7 and 10 As is clear from these graphs,
It was found that in Inventive Example 1, there was almost no variation in the A1 concentration in the plating bath from the target value compared to the comparative example, and therefore, the desired plating quality could be stably obtained.

<Effects of the Invention> According to the method for replenishing components to a plating bath of the present invention, the components to be replenished are The concentration and amount of replenishment can be arbitrarily selected. Therefore, fluctuations in concentration of components in the plating bath can be quickly suppressed, and good plating quality can be stably obtained.

In particular, when determining the necessary replenishment concentration of components and the reduction amount of the plating bath from the plating conditions, it becomes possible to replenish the components more appropriately, and even if the plating conditions change, it is possible to quickly respond to changes. This makes it possible to strictly control the concentration of components in the plating bath.

[Brief explanation of drawings]

FIGS. 1a and 1b are a diagrammatic plan view and a side view, respectively, schematically showing a configuration example of equipment for carrying out the method of replenishing components to a plating bath according to the present invention. FIG. 2, FIG. 3, FIG. 4, and FIG. 5 are diagrammatic side views schematically showing other configuration examples of equipment for carrying out the method of replenishing components to a plating bath according to the present invention, respectively. It is. FIG. 6 is a graph showing the relationship between the amount of plating deposited and the Aj2 concentration in the plating layer. FIG. 7 is a graph showing the change over time in the A2 concentration in the plating in the example of the present invention. FIGS. 8 and 9 are a schematic plan view and a side view, respectively, of equipment for replenishing components directly from a pre-melt pot to a plating bath. FIG. 10 is a graph showing changes over time in the An concentration in the plating bath in the equipment shown in FIG. Explanation of symbols 1... Plating bath, 2... Molten metal for plating, 3... Zinc roll, 4... Correcting roll, 5... Stabilizing roll, 6... Copper strip, 7... - Snout, 8.10... Pre-melt pot, 9... Molten Zn. 11-...Melting Aj! -Zn alloy, 12.14... Pump, 13.15... Conduit, 131.151... Inlet, 16... Pump, 17... Mixing tank, 18... Connecting pipe, 19 ... Injection nozzle, 20 ... Spacer, 21 ... Compressor, 22 ... Hopper, 23 ... Blade, 24 ... Metal powder, A, B, C, D, E, F.・・Primelt pot FI
G, 1a FIG, 1b FIG, 2 FIG, 3 FIG, 6. FIG・7 纂IPito J day 1 FIG, 8 FIG, 9

Claims (4)

[Claims] (1) In a method for replenishing components into a plating bath when performing hot-dip plating in a plating bath containing multiple components, multiple pre-melt pots in which replenishment components are melted in advance are used to determine the necessary replenishment concentration and In order to cope with the reduced amount, the melted replenishment components from the pre-melt pot are replenished and mixed into a mixing tank installed in the plating bath, and the mixture is injected from inside the mixing tank into the plating bath using an injection nozzle to replenish the components. A method for replenishing ingredients into a plating bath, characterized by replenishing. (2) The method for replenishing components to a plating bath according to claim 1, wherein the necessary replenishment concentration and the amount of reduction in the plating bath are determined by plating conditions. (3) In a method for replenishing components into a plating bath when performing hot-dip plating in a plating bath containing multiple components, at least one pre-melt pot in which replenishment components are melted in advance and metal lumps or metal powder particles of replenishment components are used. Using at least one hopper containing molten replenishment components, replenish and mix the molten replenishment components from the pre-melt pot into the mixing tank provided in the plating bath to correspond to the required replenishment concentration and the reduction amount of the plating bath. A method for replenishing components into a plating bath, characterized in that the mixture is injected into the plating bath using an injection nozzle, and the components are replenished by charging the mixture into the plating bath from a hopper. (4) The method for replenishing components to a plating bath according to claim 3, wherein the necessary replenishment concentration and the amount of reduction in the plating bath are determined by plating conditions.