JPH0375384A - Electroplating method for hot galvanized steel sheet and continuous galvanizing producing line - Google Patents

Abstract

PURPOSE:To make the above line continuous and to efficiently produce a plated steel sheet having an electroplated composite layer excellent in coating property by arranging a hot galvanizing post-treating device in the interval until an electroplating device after performing hot galvanizing in the continuous plating producing line. CONSTITUTION:A steel sheet wherein washing and annealing have been performed is regulated at the temp. proper for plating in a cooling furnace 6. Thereafter both sides or single side of the steel sheet is galvanized in a hot galvanizing bath tank 7. Furthermore at least one or more hot galvanizing post-treating devices 9 are arranged and the surface of the hot galvanized steel sheet is treated by strong alkali. Successively it is washed with water dewatered and thereafter refining and rolling are performed to smoothen the surface of the galvanized steel sheet. This steel sheet treated by various hot galvanizing post-treatment is successively led to an electroplating device 14 and electroplating is performed on the upper layer thereof. Successively in accordance with necessity, surface treatment due to chromate treatment, zinc phosphate treatment or resin coating by a roll coater, etc., is performed to obtain a final product.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an electroplating method for hot-dip galvanized steel sheets and a series of zinc-based continuous plating manufacturing equipment used therefor, and in particular to a method for electroplating hot-dip galvanized steel sheets, and a series of zinc-based continuous plating manufacturing equipment used therefor. This invention relates to an electroplating method for plated steel sheets and a series of zinc-based continuous plating manufacturing equipment used therein.

(Prior Art) Materials used in fields such as automobiles and building materials are required to have higher corrosion resistance and longer lifespan each year.

In particular, in recent years, demands for improving the corrosion resistance of rust-proof steel sheets for automobile bodies have become more severe, and in response to this, for example, Zn-N1
5Zn-Fe, Zn-Mn based alloy electroplating, or Zn Fe, Zn AQ St, Zn-
AQ-Mg alloy hot-dip plated steel sheet, and Fe in the upper layer to improve cationic electrodeposition coating properties and water-resistant adhesion.
Multi-layer plated steel sheets with rich (260%) Fe-Zn alloy plating have been developed and put into practical use (Patent No. 1).
No. 299498).

Among these, multilayer plated steel sheets are advantageous in that they can be provided with various functionalities such as not only paintability but also press workability (slidability) and weldability. N
i/re-Zn plating (Japanese Patent Publication No. 60-57518), 2i1Zn-Ni plating (Japanese Patent Publication No. 60-1978)
93), two-layer Zn-Mn plating (JP-A-58-
42787), Zn, Zn alloy/fine particle dispersion plating (Japanese Unexamined Patent Publication No. 62-230999), etc., multilayer plating by electroplating has been proposed. Recently, it has been proposed that electroplating is applied on top of alloyed hot-dip galvanizing as a base material (Japanese Unexamined Patent Publication No. 56-1
See Publication No. 33488 and Japanese Unexamined Patent Publication No. 61-253397.

By the way, in the case of an electroplating line, for example, equipment for continuously manufacturing such multilayer plating on one line, it is possible to produce different types of plating by simply arranging each plating tank (cell) in succession. Generally, no special equipment was installed between each plating tank, except for spray or dip (immersion) water cleaning between the transferred cells, hot water rinsing as needed, and simple brush cleaning.

When performing electroplating after molten metal plating on a steel plate, it is conceivable to arrange two plating processes in succession, similar to an electroplating line. It is also disclosed in Japanese Patent No. 224791.

(Problems to be Solved by the Invention) However, as a result of subsequent research, it has been found that when two different processes, such as molten metal plating and electroplating, are arranged in series, the following problems arise when simply arranging them in series. It was found that this occurs.

(1) If electroplating is performed continuously after hot-dip galvanizing, for example, Fe (Fe-Zn), Cr (Cr-ox etc.)
The adhesion of electroplated films such as IDE, Ni, and Zn-Ni platings is poor, and they easily peel off when in the form of a flat plate or after processing (bending, drawing).

(2) After hot-dip galvanizing, heating and alloying treatment and applying the same electroplating as above will result in an alloyed hot-dip Zn-plated steel sheet,
In other words, there are microscopic irregularities in the plating that are specific to G^ steel sheets (this depends on the crystal form of the Zn-Fe alloy and microscopic depressions formed during alloying, and the size is 3 to 2.
0tI11), the upper layer electroplating does not sufficiently cover the recesses (depressions), and the upper layer plating is a plating layer such as Fe plating that is responsible for improving the cationic electrodeposition coating properties, and the function is sufficient. It is not demonstrated. Hereinafter, this plating coverage will be referred to as plating micro coverage.

Although great benefits can be expected from continuous plating lines, basic and important performance such as adhesion and coverage of coatings cannot be obtained sufficiently, and therefore, it is difficult to achieve these qualities. There is a strong demand for manufacturing equipment that can continuously manufacture multi-layer plated steel sheets.

Thus, an object of the present invention is to provide an excellent continuous manufacturing method and equipment for a multilayer meso-metallic steel sheet that advantageously satisfies these requirements.

(Means for Solving the Problems) The gist of the present invention is to provide a pretreatment device, a hot-dip galvanizing bath, an alloying device and a temper rolling machine that may be provided as necessary, and an electroplating device. In a row of continuous plating production equipment that is arranged in sequence, at least one or more This is a line of zinc-based continuous plating manufacturing equipment equipped with molten chicken post-processing equipment.

From another aspect, the present invention provides a method for electroplating a hot-dip galvanized steel sheet, preferably an alloyed hot-dip galvanized steel sheet, in which a hot-dip galvanizing post-treatment, that is, surface oxide removal, is performed before electroplating. and post-treatment for activation at least once.

According to a preferred embodiment of the present invention, the hot-dip plating post-treatment device is a strong alkaline immersion or spray device with pi≧12, an alkaline electrolysis device, a cathode electrolysis device, or an aluminum oxide soluble acid immersion or spray device. You can.

According to another aspect, the hot-dip plating post-treatment may be alkaline water cooling with pi≧10 before the steel rolling process provided before electroplating; In the 11 quality rolling process provided previously, p
Temper rolling may be performed using a strong alkali or aluminum oxide soluble acid with H≧12 as the temper rolling fluid.

The manufacturing equipment array according to the present invention will be explained in more detail with reference to the attached drawings. In this example, an equipment array equipped with an alloying furnace is explained, but the present invention is not limited to this. has already been mentioned.

FIG. 1 is a schematic explanatory diagram of a series of continuous manufacturing equipment according to the present invention. In FIG.
The surface of the steel strip is cleaned in a pretreatment furnace consisting of a reduction furnace 5 and a cooling furnace 6, and further annealed if necessary, then led to a galvanizing bath 7, hot-dip galvanized, and then optionally annealed. Zn and Fe are alloyed in an alloying furnace 8.

This galvanized bathtub is made of Galfan (5% M, 0.1%
(Lance), remaining Zn), galvalume (55%A
Q.

(3), 5% S+, remaining Zn), etc., and in the present invention, these are collectively referred to as hot-dip galvanized bathtubs.

Next, it is immersed in, for example, a strong alkaline solution (pH≧12>) in a hot-dip plating post-processing device 9, and cleaned with a water scrubber 10. Thereafter, it is passed through a priddle roll 19 and then passed through a temper rolling mill 11 and a leveler 12 to make the surface flat. After the electroplating and distortion removal, electroplating is performed through a pretreatment tank 13, an electroplating tank 14, and a washing scrubber 15, and then the dryer 1
The steel strip 2 is dried in step 6, and then subjected to final finishing such as chromate treatment in a surface treatment device 17 if necessary, and then wound on a tensigon roll 18.

The hot-dip plating post-treatment device 9 may be an alkaline liquid spray device, an alkaline electrolysis device, a cathode electrolysis device, or an aluminum oxide soluble acid dipping device or a spray device instead of the above-mentioned strong alkaline solution immersion cleaning device. Good too. In addition, the post-treatment device may be located either before or after the skin pass rolling mill 11.In short, such a post-treatment device cleans and activates the surface of the hot-dip Zn plating layer and improves the adhesion with the subsequent electroplating layer. There are no particular restrictions.

The manufacturing equipment line according to the present invention is equipped with a hot-dip plating post-treatment device 9, such as a strong alkali immersion treatment or spray treatment device, as described below.

(2) the hot-dip plating post-treatment device 9 after the alloying furnace 8;
For example, an alkaline electrolytic treatment or a neutral cathode electrolytic treatment device is installed.

(3) After the temper rolling mill 11 and the leveler 12, an alkaline electrolyzer is installed again. The alkaline electrolyzer in this case performs neutral cathode electrolysis.

(4) The hot-dip plating post-processing device 9 after the leveler 12
For example, an alkaline electrolyzer (neutral cathode electrolyzer) is installed.

(5) The hot-dip plating post-processing device 9, for example, an alkaline electrolysis device, is installed immediately before the electroplating equipment row.

As described above, by using the zinc-based continuous plating production equipment array according to the present invention, it is possible to continuously produce multi-layer plated steel sheets with excellent performance on the same line with high efficiency, that is, with high efficiency. .

(Function) Next, an example of operation using the continuous plating production equipment array according to the present invention will be described in detail along with its function.

First, the pretreatment equipment cleans the surface of the belt and anneales it if necessary. Such equipment includes, for example, the rapid heating furnace 4, the reduction furnace 5, and the cooling furnace (temperature adjustment) shown in Fig. 1.
Consists of 6. Note that the copper strip cleaning may be performed as a pre-cleaning with an alkali or the like before entering the rapid heating furnace 4.

After the steel strip that has been cleaned and annealed in this way is adjusted to a temperature suitable for plating in a cooling furnace 6, it is placed in a hot-dip Zn plating bath 7.
(or Zn-based alloy plating bath) to plate both sides or one side. The amount of plating deposited is adjusted to the specified amount using a gas wiping device directly above the plating bath. After that, Z
When alloying n-plating, the alloying process is performed in an alloying furnace 8.

As the alloying furnace 8, for example, a gas combustion heating furnace, an electric M1 induction heating furnace, a laser irradiation heating furnace, etc. can be used, and the alloying process is performed using these. It can be changed as appropriate.

For example, as a rust-proof steel sheet for automobiles, Zn coating amount: 30 to 8
0g/-1 alloying degree: Zn-Fe alloy plating with Fe7 to 12% is possible. Moreover, when alloying treatment is not performed, the sheet is threaded without using this device.

The alloyed hot-dip Zn-plated or hot-dip Zn-plated steel strip produced in this manner is then surface-treated with a strong alkali as a post-hot-dip plating treatment.

As alkaline treatment liquid, sodium hydroxide, sodium silicate (
(ortho, meta), sodium phosphate, sodium bicarbonate, etc. However, in the case of immersion or spray treatment, that is, in the case of non-electrolysis, strong alkalis with pi≧12 (for example, 1 mol/ 1 or more Na0H) and the temperature is preferably 60°C or higher.

In addition, hot-dip plating post-treatment may be carried out by cathodic electrolysis using strong or weak alkali (sodium phosphate, sodium bicarbonate), or cathodic electrolysis using a neutral solution (e.g. sodium sulfate)! As a solution device, either direct energization, in which voltage is applied directly to the electrodes and strips, or indirect energization (alternating current), in which voltage is applied indirectly, is possible.

Alternatively, a dip or spray treatment with alfructium oxide soluble acid can be used. Examples of aluminum oxide soluble acids include hydronic acid, phosphoric acid, and Shellac acid, but sulfuric acid, hydrochloric acid, and nitric acid are not suitable because they have a low ability to dissolve aluminum oxide and have a high melting rate for base plated steel sheets. , the aluminum oxide soluble acid has a pH of 1 to 4 or less,
A liquid temperature of 40° C. or higher is desirable; a pH>4 requires a long time for treatment, and a pH<l is undesirable because it promotes dissolution of the base plated steel sheet.

Following the hot-dip plating post-treatment such as the alkali treatment mentioned above, cleaning with a water (hot water) scrubber or dip tank,
After removing water using a ringer roll, air blow, etc., the material is then usually subjected to temper rolling.

This tIi award rolling may be performed before the hot-dip plating post-treatment described above.

Temper rolling is performed at a reduction rate of, for example, 0.1 to 2.0% for the purpose of preventing buckling of a plated steel sheet caused by alloying treatment, removing strain, and flattening the plated surface. This temper rolling is not essential and can be omitted, for example, in Ti-added steel sheets. Further, even with ordinary steel sheets, it is perfectly acceptable to perform temper rolling in a post-process after plating.

Furthermore, when a temper rolling facility is provided in the zinc-based continuous plating manufacturing equipment line of the present invention, the hot-dip plating post-treatment can also be performed in water cooling before temper rolling.

A steel plate after hot-dip galvanizing or alloying is at a high temperature. Therefore, when applying 11 award rolling to this steel sheet, it is desirable from the viewpoint of mechanical properties that this skin pass rolling be performed at around room temperature. The surface cleaning activation can be performed by using alkaline water cooling in the pre-cooling.

Specifically, two or more water-cooled cells are installed for cooling, and the final cell is water-cooled, but at least one of the other cells is water-cooled.
For example, in the apparatus shown in Fig. 5, surface cleaning is activated in an alkaline water cooling bath 9'', and then the water cooling bath is The alkali fraction is removed and cooled at 10°C. In this case, the alkaline liquid type is hydric soda, but other alkaline types such as sodium orthosilicate can be used without any problem.
In addition, the alkaline solution may contain a surfactant, etc. It is effective as long as the pH is 10 or higher, and there is no particular upper limit. The temperature of the steel plate is preferably 80°C or higher at the alkaline solution inlet, and 80°C. If the plate temperature is below, it is necessary to lengthen the treatment time or increase the alkali concentration to pH 12 or higher, which is not practical. The effect can be obtained in a short period of time, and as shown in Figure 3, the micro coverage is greatly affected by the temperature of the plate being treated. Therefore, after the water cooling bath, it is necessary to raise the temperature of the board from room temperature again, and
From the viewpoint of ensuring the mechanical property values of the steel sheet, it is not desirable to increase the sheet temperature after temper rolling.

In this process, the final cooling tank is water-cooled, but this is to prevent the alkali fraction from being picked up by the subsequent rolls, etc., and even if it is not water-cooled, it does not affect the improvement of microscopic coverage itself.

Furthermore, the hot-dip plating post-treatment of the present invention can also be performed in a temper rolling process. Specifically, ai'it rolling is performed using a strong alkali or aluminum oxide soluble acid with a pH ≧12 as the skin pass rolling fluid. After passing through a water cooling tank (not shown), the rolling can be carried out in a temper rolling mill 11.

As the strong alkali to be used, for example, 1.
ol/ffi solutions are mentioned, but there are no restrictions as long as they are alkaline substances that do not pose a problem even if they are brought into the subsequent electroplating solution as a contaminant component. Considering this, a pn of 12.5 or higher is desirable.

Examples of acids that can dissolve aluminum oxide include hydrofluoric acid, phosphoric acid, and oxalic acid, but sulfuric acid, hydrochloric acid, and nitric acid are not suitable because they have a low ability to dissolve aluminum oxide and have a high rate of dissolving zinc in base plated steel sheets. No, the acid concentration is preferably p) II to 4.

If the pH is >4, the treatment time will take a long time, and if the pH is less than 1, it will promote dissolution of the base plated steel sheet, which is undesirable.

The effects of the above treatment method are not affected much by manufacturing conditions such as the steel sheet passing speed and the roughness of the pressure regulating roll.

In addition, it is known that the rolling fluid used in rolling mills for zinc-based continuous plating equipment usually adds inhibitors to the water, but these are all used to remove oils and fats from steel sheets and According to the 0-line treatment, which is aimed at preventing corrosion of the metal and is completely different from the present treatment, the plating adhesion and coverage of the electroplating applied as an upper layer can be significantly improved.

The strip treated with the various hot-dip plating post-treatments detailed above is then led to an electroplating apparatus, and the upper layer is electroplated.

The electroplating equipment has a pre-treatment tank, an electroplating tank, and a post-cleaning tank (washing scrubber).The pre-treatment tank is cleaned with water or a solution that improves the plating surface properties, and the plating tank is used to perform various types of electroplating. After that, the steel plate is washed with water in a post-washing tank, and if necessary, the steel plate is dried with hot air or electrical heating.

For electroplating, pure Fe and Fe-X systems (where X is Zn, P, or Ni) improve cationic electrodeposition coating properties.

B, Sn, Ti, etc.), Cr (Cr-oxide), Ni, Ni-Zn that improves the sliding properties of the plating film
In addition to N1-5iC, ZZn-3in, MI
There are various functionally dispersed platings such as Zn 5i (h, Zn AQgOs type).The number of electroplating tanks may be plural depending on the amount of plating deposited.

Subsequently, this is also subjected to surface treatment such as chromate treatment, zinc phosphate treatment, or resin coating using a roll coater equipment, etc., as necessary, to obtain a final product.

The hot-dip plating post-treatment device, which is a feature of the present invention, is a device that greatly improves the plating adhesion and plating coverage of the electroplating applied as an upper layer, but its function is not yet fully clear, and current considerations Where it is
AQ oxide (or Z
In addition to dissolving and removing (n-containing AQ oxide), it is thought that removing impurity elements that are estimated to affect electrodeposition, such as AQ that is also segregated on the surface, is involved. Such impurities can be removed by the post-hot-dip plating treatment of the present invention, specifically treatment with a strong alkali or acid solution capable of dissolving aluminum oxide, or the electrolytic treatment described above. Therefore, the post-treatment of the present invention can be referred to as "surface oxide removal activation."

When post-treatment is performed by alkaline water cooling before or after temper rolling, the temperature of the steel plate is thought to affect the AQtOs dissolution reaction on the plate surface, and when the plate temperature is 80°C or higher, it is especially difficult to apply micro-coated parts of electroplating. sex is improved.

Also, il! As a temper rolling fluid in the temper rolling process, pH 12
When using the above strong alkali or aluminum oxide soluble acid, M oxide (or Zn-containing M oxide), which has poor conductivity, is formed on the surface of the plating that has undergone thermal history such as hot-dip plating or alloying treatment. matter>, A further segregated on the surface
Impurity elements that are estimated to affect electrodeposition, such as □, are removed mechanically by rolls during pressure adjustment, and at the same time, they are chemically removed using strong alkali or aluminum oxide soluble acid used in the adjustment rolling oil. It is something.

Note that electroplating equipment is usually equipped with alkaline degreasing equipment as a pre-plating treatment, but this is simply to remove dirt and oil adhering to the steel strip, and in terms of function and effect, it is not a genuine product. Unlike the alkali treatment equipment of the invention,
This should be distinguished from the above-mentioned "surface oxide removal activation."

Furthermore, even if the hot-dip galvanizing contains elements such as AQ, Mg, and Mn, the above activation acts only on the surface;
Since it does not reach the inside of the plating, there is no problem.

FIGS. 2(a) and 2(ET) are schematic illustrations of multilayer plating film structures obtained by the present invention and conventional examples, respectively. The hot-dip galvanized layer 22 has fine irregularities 24.26
However, an electroplating layer 28 is uniformly provided over the entire surface. This is because the electrodeposition inhibiting components were removed in advance. On the other hand, in the conventional example (b), the convex portions are covered with the electroplating layer 28, but the lower alloyed hot-dip galvanized layer 22 is exposed in the concave portions, so the electroplating layer 28 is coated with the electroplated layer. This means that the effects of improvement in properties, processability, etc., will not be sufficiently achieved.

[Example 1 The present invention will be specifically explained by examples.

Example 1 In this example, the manufacturing equipment array shown in FIG. 1 is used (however, the post-processing is done so that it can be processed either after the alloying process or after the leveler). A zinc-based plated steel strip was produced under the treatment conditions shown and other conventional conditions.

In Table 1, (^) to (F) indicate the following processing conditions.

(^) Alkaline solution immersion conditions: Treatment time: 2 seconds (B) Alkaline electrolysis conditions: Cathode electrolysis: 20 A/d+*” Treatment time: 2 seconds (C) Neutral cathode electrolysis conditions: Treatment solution 20.5 mol / l NazSOa, temperature: 7
0°C cathodic electrolysis: 60 A/dm” Treatment time: 5 seconds (D) Alkaline liquid spray conditions: Alkaline liquid: 1 mol/l NaOH, Temperature = 70°C
(Treatment liquid) Spray header pressure: 0.5 kg/cm'' Treatment time = 2 seconds (E) Immersion conditions for aluminum oxide soluble acid: Acid liquid
: 0.5 mol/l Phosphoric acid temperature: 70°C Treatment time: 3 seconds (F) Spray conditions of flyl-argonium soluble acid:
Acid liquid: 0.5 mol/1 Shellacic acid temperature: 6
0° C. Treatment time: 3 seconds After the electroplating was completed, a chromate treatment was performed in the surface treatment device 17 as necessary to give a final finish.

The electroplating adhesion and coverage of the plated steel sheets thus obtained are summarized in Table 1.

(Continued on next page) As is clear from Table 1, the multilayer steel sheet obtained by the present invention has excellent plating adhesion and coverage, and in particular, the plating coverage has reached an unprecedented level. Improvements have been made.

Example 2 Oil-free and untreated GA manufactured on an actual line (45g
After performing oxide removal treatment using various temper rolling oils shown in Table 2 in the wR quality rolling process before electroplating, electroplating was performed under the following conditions, and from cross-sectional microscopic observation. The rolling properties of electroplating were investigated.The results are shown in Table 2.

Electroplating conditions Total Fe 80g/j! Current density
60A/d+s"Fe" 11000pp Plating adhesion 1 5g/m "Zn" 2g/I Na" 25g/1 pH 1,6 Temperature 50℃ Sulfuric acid bath Table 2 Treatment method and micro-adhesiveness Cleanly along the unevenness of 64 layers O the things that follow you
, those in which the plating layer was intermittent were evaluated as ×.

N11L4.5 has a pi of less than 12 when treated with a weak alkali, and N11L4.10 is not an acid that can dissolve aluminum oxide. Therefore, the microscopic adhesion properties are poor.0 Problems 1 to 3 and 6 to 8 of the examples of the present invention are treatments that dissolve the aluminum oxide on the surface, and the dissolution of the GA layer of the base material is suppressed. Excellent micro-turning properties.

Example 3 In the hot-dip galvanizing equipment shown in FIG. 3, 1 mol/l of NaOH (pH 1
When continuous plating was performed on GA using electroplating equipment under the electroplating conditions described in Example 2 using 3°5), the micro coverage was good.

On the other hand, 50'crtio (and HzO + inhibitor) and NaOH with a pH of 11.0 were used as rolling oil.
When electroplating was applied on the GA, the microscopic coverage was poor.

Example 4 Electroplating was carried out under the following conditions using GA (0.8 Kaku 45/45) treated with pH 10, 0 strength soda for 1.0 seconds and then washed with water. FIG. 4 shows the effects of the treatment liquid temperature and steel plate temperature on the electroplating runnability in that case.

Electroplating conditions Total Fe 70g/j! Current density
50A/da"Fe"2g#! Plating deposition amount 5g/lZn" 1.5g/l pH 1.8 Temperature 50°C Micro-adhesiveness is more affected by the steel plate temperature than the treatment liquid temperature. The higher the steel plate temperature, the better.
A more significant effect was observed.

Example 5 GA (0.8 mtm
45/45) under the same conditions as in Example 4.

The results are shown in Table 3.

Table 3 Micro-stripping properties The multilayer steel plate obtained by the present invention has excellent micro-pulling properties.

Example 6 (1) In the actual machine shown in Fig. 5, a strong soda solution with a pH of 10.0 was used in the alkaline water cooling tank 9°, and water was used in the water cooling tank 10'' for treatment, and then electroplating (implementation) was carried out. The same as in Example 4) was applied, but the micro coverage was good.

The processing conditions at that time are Penetration plate temperature 90℃ Alkaline water temperature 85°C Processing time Q, 5sec Met.

(2) In the case of (1) without alkaline water cooling, the microscopic coverage was poor.

(Effects of the Invention) The present invention is a continuous plating process that has not been previously known, and the effects obtained by it have not yet been achieved. The significance of the invention is great.

That is, according to the present invention, multi-layer plated steel sheets can be manufactured efficiently by making the plating line continuous, and multi-layer plating with excellent electroplating coverage and adhesion, which could not be obtained by simply making the plating line continuous, can be achieved. You can get steel plates.

[Brief explanation of drawings]

Fig. 1 is a schematic explanatory diagram of a zinc-based continuous plating manufacturing equipment line according to the present invention; Fig. 2 (A) and (El) show coating structures on the surface of steel sheets obtained by the apparatus of the present invention and the conventional example, respectively. A schematic explanatory diagram of; FIG. 3 is a schematic explanatory diagram of another zinc-based continuous plating manufacturing equipment line of the present invention; FIG. 4 is an explanatory diagram showing the flowability depending on the temperature of the steel plate and the temperature of the processing liquid; and FIG. 5 is a schematic explanatory diagram of another zinc-based continuous plating manufacturing equipment line according to the present invention. 1: Payoff reel 2: Steel strip 3: Pre-cleaning device 4: Rapid heating furnace 5: Reduction furnace 6: Cooling furnace 7: Galvanizing bath 8: Alloying furnace 9: Hot-dip plating post-treatment device 9°: Alkaline water cooling tank: 10: Water scrubber 10゛: Water cooling tank: 11: III prize rolling mill 12: Leveler 13: Pre-treatment tank 14: Electroplating tank 15: Water scrubber 1
6 = Dryer 17: Surface treatment device 18: Tensilan roll bird 2 Figure

Claims (8)

[Claims] (1) In a continuous plating production equipment line consisting of a pre-treatment device, a hot-dip galvanizing bath, and an electroplating device, after hot-dip galvanizing and up to the electroplating device,
A series of zinc-based continuous plating manufacturing equipment equipped with at least one post-treatment device for hot-dip plating. (2) The hot-dip plating post-treatment device is a strong alkaline immersion or spray device with a pH≧12, an alkaline electrolysis device,
2. The zinc-based continuous plating manufacturing equipment line according to claim 1, which is a cathode electrolysis device or an aluminum oxide soluble acid dipping or spraying device. (3) A temper rolling mill is installed in front of the electroplating device,
2. The zinc-based continuous plating production equipment array according to claim 1, wherein the hot-dip plating post-treatment device is an alkaline water cooling tank with a pH≧10 provided in front of the temper rolling mill. (4) A temper rolling mill is installed in front of the electroplating device,
The zinc-based continuous plating according to claim 1, wherein the temper rolling mill uses a strong alkaline solution with a pH≧12 or an aluminum oxide soluble acid solution as the temper rolling fluid, and also serves as the hot-dip plating post-treatment device. Manufacturing equipment row. (5) In the method of electroplating hot-dip galvanized steel sheets, before electroplating, immersion or spray treatment in a strong alkali with pH≧12, alkaline electrolysis treatment, cathodic electrolysis treatment, or immersion or spray treatment with aluminum oxide soluble acid. A method for electroplating hot-dip galvanized steel sheets, which comprises performing a post-hot-dip galvanizing treatment for surface oxide removal and activation. (6) In a method of electroplating a hot-dip galvanized steel sheet after temper rolling, a hot-dip plating post-treatment for activation of removal of surface oxides is performed by alkaline water cooling with pH≧10 before the steel rolling process. An electroplating method for hot-dip galvanized steel sheets. (7) The electroplating method according to claim 6, wherein the temperature of the steel plate on the alkaline water cooling entry side is 80°C or higher. (8) In a method of electroplating hot-dip galvanized steel sheets after temper rolling, surface oxides are A method for electroplating hot-dip galvanized steel sheets, which comprises performing a post-hot-dip plating treatment for activation of removal.