JP2006193818A - Method and device for producing electrogalvanized steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for producing an electrogalvanized steel sheet having excellent uniformity in surface appearance without differentiating the visual sensitivity in a plating layer in the width direction. <P>SOLUTION: Regarding the device 20 for producing an electrogalvanized steel sheet, the space between a second water-washing apparatus 25 of washing the steel sheet stock 21 to be electrogalvanized with water, and an electrogalvanizing apparatus 27 of applying electrogalvanizing to the steel sheet stock 21 with a plating liquid is provided with a lubrication treatment apparatus 26 of subjecting the steel sheet stock 21 to lubrication treatment with an acid solution in the range from the pH of the plating liquid to the pH of water. As the acid solution, washing water after the washing of an electrogalvanized steel sheet 21a subjected to plating treatment by a post water washing apparatus 28 is used. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and an apparatus for producing an electrogalvanized steel sheet.

  Zinc (Zn) -based plated steel sheets (hereinafter referred to as galvanized steel sheets) are excellent in corrosion resistance and workability, and are inexpensive, so they are used in various applications such as building materials, automobile members, household appliance members, and guardrails. Yes. Since the galvanized steel sheet is used for such a wide range of applications, various galvanized coating amounts are required depending on the application. In general, galvanized steel sheets are hot dip galvanized when increasing the amount of adhesion with an emphasis on corrosion resistance, and electrogalvanized when reducing the amount of adhesion with an emphasis on workability. ing.

  FIG. 3 is a diagram illustrating a configuration of a conventional electrogalvanized steel sheet manufacturing apparatus 1 used for manufacturing an electrogalvanized steel sheet. The electrogalvanized steel sheet manufacturing apparatus 1 is roughly composed of an alkaline degreasing apparatus 3, a first water washing apparatus 4, from the upstream side to the downstream side in the sheet passing direction indicated by the arrow 9 of the base steel sheet 2 to be electrogalvanized. The pickling device 5, the second water washing device 6, the electrogalvanizing device 7, and the post-water washing device 8 are provided in this order.

  Hereinafter, the production of a conventional electrogalvanized steel sheet will be described with reference to FIG. In the base steel plate 2 rewound from a rewinding device (not shown), the oil and fat content on the steel plate surface is first washed and removed in the alkaline degreasing device 3. Next, the surface of the base steel plate 2 is washed with water in the first washing device 4, and the alkaline degreasing liquid remaining on the surface is washed away.

  The washed steel sheet 2 is pickled by the pickling solution in the pickling device 5 and the surface is activated. The activated steel sheet 2 is washed with water in the second washing apparatus 6, and the pickling solution remaining on the surface is removed by washing. The base steel plate 2 washed with the second water washing device 6 is drained of the washing water by a pair of ringer rolls 10 a and 10 b provided on the outlet side of the second water washing device 6. Thereafter, the base steel plate 2 is inserted into the electrogalvanizing apparatus 7, immersed in a plating solution stored in a plating tank provided in the electrogalvanizing apparatus 7, and energized through an electrode (not shown). Electrogalvanizing is applied.

  The base steel plate 2 to which the electrogalvanization has been applied becomes an electrogalvanized steel plate 2a, and the surface of the post-washing device 8 is cleaned with water, and the remaining plating solution and the like are cleaned and removed. Here, the term “steel plate” is used to include a steel strip.

  As described above, the base steel plate 2 washed with the second water washing device 6 is secondly brought into the electrogalvanizing device 7 with the water used for the water washing adhered to the surface so as not to dilute the plating solution. Water is drained by the ringer rolls 10a and 10b on the outlet side of the water washing device 6. However, draining is not always performed sufficiently, and there is a tendency that draining is insufficient in the vicinity of the end in the width direction of the base steel plate 2 than in the center in the width direction.

  FIG. 4 is a perspective view of the electrogalvanized steel sheet 2a plated with insufficient draining. In FIG. 4, an electrogalvanized steel sheet 2 a that is plated by the electrogalvanizing apparatus 7 in a state where the drainage in the vicinity of the widthwise end portion 11 of the base steel plate 2 is insufficient as compared with the central portion 12 in the widthwise direction. Indicates. The electrogalvanized steel sheet 2a plated with insufficient draining is formed with a non-uniform pattern in which the galvanized layer has different visual sensations in the vicinity 11 in the width direction and the central part 12 in the width direction. The The electrogalvanized steel sheet 2a on which such a pattern is formed cannot be commercialized as a defective appearance, and there is a problem that the yield is lowered.

  Prior art for improving the surface appearance of an electrogalvanized steel sheet involves pickling the surface of the steel sheet with an acidic solution having substantially the same composition as that of the acidic plating bath prior to the electrogalvanizing step using an acidic plating bath. (See Patent Document 1).

  However, the technique disclosed in Patent Document 1 prevents the removal of the impurity-concentrated layer or oxide layer on the surface of the steel sheet due to the pickling performed before the plating process, and the occurrence of rough skin or acid burn (dirt). By doing so, the surface appearance of the electrogalvanized steel sheet is improved. That is, it improves the surface appearance defect due to the mechanical surface shape or acid burn (dirt) on the surface of the base steel plate before plating.

  Therefore, as described above, the unevenness of the galvanized layer due to insufficient draining of the water washing despite the lack of mechanical surface shape or dirt on the base steel plate In Patent Document 1, nothing is mentioned, and no improvement technique is disclosed.

  Another conventional technique for improving the surface appearance of an electrogalvanized steel sheet is that an acidic plating solution remains on the surface of the steel sheet after electrogalvanization, resulting in poor appearance due to re-dissolution of the electrogalvanized layer. In order to improve, wash water with pH adjusted so that the pH value of the liquid during the final wash section will increase stepwise will be used, and in the final wash section, it will be washed with neutral wash water. (See Patent Document 2).

  However, the technique disclosed in Patent Document 2 also does not mention any non-uniform pattern in which the galvanized layer has a different visual appearance due to insufficient draining of water before plating treatment. There is no disclosure of the improved technology.

Japanese Patent Laid-Open No. 10-110290 Japanese Patent Laid-Open No. 11-92991

  The objective of this invention is providing the manufacturing method and manufacturing apparatus of an electrogalvanized steel plate which were excellent in the uniformity of the surface external appearance, without the visual appearance of a plating layer differing in the width direction.

  According to the results of intensive studies by the present inventors, such uneven patterns with different visual sensations have a pH in the steel plate width direction of the plating solution present in the vicinity of the steel plate surface charged in the plating solution. This is due to the difference between the vicinity of the end and the center. That is, when the draining after the water washing performed before the plating is not always sufficient, a larger amount of water tends to remain in the vicinity of the end portion in the width direction of the steel plate than in the central portion. In such a state, when a steel plate is inserted into the electrogalvanizing solution, the plating solution generally adjusted to pH: 1 to 2 is greatly diluted near the end in the width direction of the steel plate so that the pH is reduced. It becomes high and pH is lowered because it is hardly diluted in the central part in the width direction of the steel sheet. Therefore, the plating solution is plated with a high pH in the vicinity of the end in the width direction of the steel plate and at a low pH of the plating solution in the center in the width direction of the steel plate.

  The present inventors have found that the crystal growth orientation of the galvanized layer formed on the steel sheet surface by electrogalvanization has a dependency on the pH of the plating solution, and the end portion is different due to the different pH in the steel sheet width direction. The inventors have obtained the knowledge that the crystal growth orientation is different between the vicinity and the central portion, and that a non-uniform pattern is produced with different visual sensations after plating, and the present invention has been achieved.

The present invention provides a method for producing an electrogalvanized steel sheet in which an electrogalvanized steel sheet is produced by electrogalvanizing a base steel sheet.
A water washing step for washing the steel sheet to be electrogalvanized with water,
A wet treatment step of wet-treating the surface of the steel sheet with an acidic solution having a pH that is higher than the pH of the plating solution and lower than the pH of the water after washing with water and before electrogalvanizing,
And a plating treatment step of electrogalvanizing a base steel plate wet-treated with an acidic solution with a plating solution.

The present invention also includes a post-water washing step of washing the electrogalvanized steel sheet with water after the plating step,
The acidic solution is characterized by being the washing water used in the post-water washing step.
In the present invention, the acidic solution has a pH of 3 or more and 5 or less.

The present invention provides an electrogalvanized steel sheet manufacturing apparatus for manufacturing an electrogalvanized steel sheet by subjecting a base steel sheet to electrogalvanization.
Water washing means for washing the steel sheet to be electrogalvanized with water,
Electrogalvanizing means for electrogalvanizing the steel sheet with a plating solution;
A wet treatment means provided between the water washing means and the electrogalvanizing means and wet-treating the washed steel sheet with an acidic solution having a pH which is not less than the pH of the plating solution and not more than the pH of the water. An apparatus for producing an electrogalvanized steel sheet.

The present invention further includes post-water washing means for washing the electrogalvanized steel sheet that has been electrogalvanized with water,
The acidic solution is characterized in that it is washing water used for washing by a post-water washing means.

  In the present invention, the acidic solution used in the wet treatment means has a pH of 3 or more and 5 or less.

  According to the present invention, the steel sheet to be electrogalvanized is an acidic solution having a pH that is higher than the pH of the plating solution and lower than the pH of the water after washing and before electrogalvanizing. It is processed. As a result, the plating solution existing in the vicinity of the surface of the steel sheet charged in the plating solution is remarkably relieved in the pH difference in the width direction of the steel sheet, so that the galvanized layer formed on the surface of the steel sheet The crystal growth orientation is aligned, and the generation of non-uniform patterns is prevented.

  Moreover, according to this invention, the wash water used at the water-washing step after washing the electrogalvanized steel plate in which the electrogalvanization was given is used as an acidic solution. This eliminates the need for a separate material and apparatus for adjusting the acidic solution, thereby making the apparatus compact and reducing the cost.

  Further, according to the present invention, since the pH of the acidic solution is 3 or more and 5 or less, the pH in the steel plate width direction of the plating solution existing in the vicinity of the surface of the steel plate charged in the plating solution is more reliably uniform. Can be

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing apparatus of the electrogalvanized steel plate which can prevent generation | occurrence | production of the nonuniform pattern from which the visual appearance in a plating layer differs is implement | achieved.

  FIG. 1 is a diagram showing a configuration of an electrogalvanized steel sheet manufacturing apparatus 20 according to an embodiment of the present invention. The electrogalvanized steel sheet manufacturing apparatus 20 (hereinafter abbreviated as the manufacturing apparatus 20) is used to manufacture the electrogalvanized steel sheet 21a by subjecting the base steel sheet 21 to electrogalvanizing treatment.

  The manufacturing apparatus 20 is configured to acidify the alkaline degreasing device 22, the first water-washing device 23, which is a washing means for washing the steel plate 21 to be electrogalvanized with water, and the steel plate 21 washed with the first water-washing device 23. A pickling device 24 for washing, a second water washing device 25 which is a water washing means for washing the steel plate 21 after pickling with water, and an electric which is an electrogalvanizing means for electrogalvanizing the steel plate 21 with a plating solution. The steel plate 21 provided between the galvanizing device 27, the second water rinsing device 25, and the electrogalvanizing device 27 is washed with an acidic solution having a pH that is not less than the pH of the plating solution and not more than the pH of water. A wet treatment means 26 for performing a wet treatment and a post-water washing device 28 which is a post-water washing means for washing the electrogalvanized steel sheet 21a subjected to electrogalvanization with water.

  The raw steel sheet 21 is unwound from a rewinding device (not shown) and is subjected to various treatments in the process of passing in the direction indicated by the arrow 29, and each treatment is performed to obtain an electrogalvanized steel sheet 21a. After that, it is wound up by a winding device (not shown).

  The alkaline degreasing device 22 includes a degreasing tank 22a in which an alkaline degreasing solution is stored, an electrode grid (not shown) provided in the degreasing tank 22a, and a power supply (not shown) that applies a voltage between the electrode grids. . As the alkaline degreasing solution, known sodium hydroxide (NaOH) or the like is used. The base steel plate 21 is electrolytically degreased and cleaned by removing oil and fat from its surface when passing between the electrode grids provided in the degreasing tank 22a to which a voltage is applied.

  The 1st water washing apparatus 23 is provided with the water washing tank 23a which stores the water used for water washing. The bare steel plate 21 subjected to the alkali degreasing treatment is washed with water by being transferred through the water stored in the washing tank 23a. The first rinsing device 23 is not limited to the above configuration, and is provided across a water supply source for supplying water, a pipe to the water supply source and the rinsing tank, and a raw steel plate transfer path in the rinsing tank. The water jet nozzle is provided, and water supplied from a water supply source is sprayed from the nozzle onto the steel plate to wash the surface of the steel plate, and the water after washing is recovered from a drain outlet formed in advance in the water washing tank. It may be configured as follows.

  The pickling apparatus 24 includes a pickling tank 24a for storing a pickling solution such as an aqueous sulfuric acid solution. The base steel plate 21 washed with the first water washing device 23 is pickled by being transferred through the pickling solution stored in the pickling tank 24a, and the oxide scale and the like on the surface of the base steel plate are removed and activated. It becomes.

  The second water washing device 25 is a device for washing and removing the pickling solution remaining on the surface of the steel plate after pickling with water, a washing tank 25a, a water supply source for supplying water, and a water supply source. And a pipe to the water washing tank 25a and a water injection nozzle provided across the raw steel plate transfer path in the water washing tank 25a, and water supplied from a water supply source is sprayed onto the steel sheet 21 from the nozzle. The steel plate surface is washed with water, and the washed water is collected from a drain outlet formed in advance in the washing tank 25a.

  In the present embodiment, the main part of the wet treatment means 26 is provided on the outlet side of the second water washing device 25. The wet treatment means 26 faces the ringer rolls 31a and 31b and the ringer rolls 31a and 31b provided on the exit side of the second water washing apparatus 25 with the transfer path of the base steel sheet 21 therebetween, and transfers the base steel sheet 21. First and second spray nozzles 32a, 32b, 33a, 33b (two pairs in the present embodiment) provided across the path, a post-water washing device 28 that is an acidic solution supply means, a post-water washing device 28, and a first And the second injection nozzles 32 a, 32 b, 33 a, 33 b are connected to form an acidic solution flow path 34, and a pump 35 is provided in the middle of the acidic solution pipe 34 to feed the acidic solution. It is comprised including.

  The ringer rolls 31a and 31b are drained of the base steel plate 21 washed by the second water washing device 25, and an acidic solution jetted from the first and second jet nozzles 32a, 32b, 33a and 33b to the roll surface. The water-washed steel sheet 21 is applied and wetted.

  As the acidic solution that is sprayed onto the ringer rolls 31a and 31b and applied to the raw steel plate 21, one having a pH that is higher than the pH of the plating solution used for electrogalvanizing and lower than the pH of water is used. Preferably, the pH of the acidic solution is 3 or more and 5 or less.

  If the pH of the acidic solution is less than 3, there is no particular inconvenience, but it becomes difficult to use the wash water used for the post-washing described in detail later as the acidic solution, and an acidic solution with a separately adjusted pH must be prepared. This will incur a disadvantage in terms of cost. When the pH of the acidic solution exceeds 5, it is not possible to sufficiently obtain the effect of uniforming the pH in the steel plate width direction of the plating solution existing in the vicinity of the surface of the raw steel plate 21 during the plating process. Therefore, the pH of the acidic solution is preferably 3-5.

  In addition, it is preferable to use the aqueous solution containing the acid component contained in a plating solution for an acidic solution. For example, when the plating solution contains a sulfuric acid component, it is preferable to use an aqueous solution containing a sulfuric acid component as the acidic solution. Since the acidic solution adheres to the surface of the base steel plate 21 and is brought into the plating solution, by changing the components of the plating solution and the acidic solution in common, the change in the plating solution composition due to the mixing of the acidic solution is suppressed, This is because deterioration of the plating quality can be prevented.

  As described above, in the present embodiment, the post-water washing apparatus 28 constitutes a part of the wet treatment means 26. The post-water washing device 28 is a device that cleans and removes the plating solution remaining on the surface of the electrogalvanized steel sheet 21a after being plated. The post-water washing device 28 has the same configuration as the second water washing device 25, and includes a water washing tank 28a, a water supply source for supplying water, a pipe to the water supply source and the water washing tank 28a, and the water washing tank 28a. A water injection nozzle provided across the electrogalvanized steel sheet transfer path is provided, and water supplied from a water supply source is sprayed from the nozzle onto the electrogalvanized steel sheet 21a to wash the surface, and the water after washing is washed with water. It is comprised so that it may collect | recover from the drain port previously formed in the tank 28a.

  In the present embodiment, as the acidic solution, the washing water used for the post-water washing recovered from the drain port of the water washing tank 28a is used. Wash water recovered from the drain outlet is supplied to the first and second injection nozzles 32a, 32b, 33a, 33b by the pump 35, and sprayed to the ringer rolls 31a, 31b. A flow rate adjusting valve may be provided in the acidic solution pipe 34 between the pump 35 and the first and second injection nozzles 32a, 32b, 33a, 33b so that the injection flow rate of the acidic solution can be adjusted. .

  An electrogalvanizing apparatus 27 serving as an electrogalvanizing means includes a plating tank 27a for storing a plating solution, a plating electrode (not shown) provided in the plating tank 27a, and a plating power supply (not shown) for applying a voltage to the plating electrode. Is provided. In the present embodiment, a solution containing zinc sulfate and sulfuric acid is used as the plating solution, and its pH is adjusted to 1-2.

  When the draining with the ringer rolls 31a and 31b is not sufficient, the acidic solution remains on the surface of the raw steel plate 21 wet-treated with the acidic solution by the wet treatment means 26. However, since the acidic solution is adjusted to pH: 3 to 5 and has a pH close to the pH of the plating solution, the acidic solution is diluted in the vicinity of the end in the width direction and the central portion of the raw steel plate 21 charged in the plating solution. There is almost no difference in the pH of the plating solution. Therefore, since the growth direction of the zinc crystal of the plating layer formed on the surface of the raw steel plate 21 is the same in the vicinity of the end portion and the central portion, it is possible to prevent the occurrence of uneven patterns with different visual sensations.

  Since the above-described post-water washing apparatus 28 removes the plating solution remaining on the surface of the electrogalvanized steel sheet 21a after the plating treatment with water, the washing water after being used for washing is contained in the plating solution. It contains a sulfuric acid component and has a pH suitable for use as an acidic solution.

  In this way, in the post-water washing apparatus 28, the washing water used for washing the electrogalvanized steel sheet 21a can be used as the acidic solution, so that it is not necessary to provide a separate apparatus for supplying the acidic solution. The apparatus can be made compact, and the initial cost of the manufacturing apparatus and the running cost of production can be reduced.

Hereinafter, the manufacturing method of the electrogalvanized steel sheet in the manufacturing apparatus 20 is demonstrated.
The base steel plate 21 unwound from a rewinding device (not shown) is inserted into an alkaline degreasing device 22 and subjected to alkaline electrolytic cleaning to remove oil and fat from the surface. The alkali degreased steel sheet 21 is inserted into the first water washing device 23, and the alkaline degreasing liquid remaining on the surface is washed with water. After rinsing with the first rinsing apparatus 23, the base steel plate 21 is inserted into the pickling apparatus 24 and activated.

  After pickling, the base steel plate 21 is charged into the second water washing device 25, and the pickling solution remaining on the surface is washed with water. The washed steel sheet 21 is wet-treated by applying an acidic solution having a pH not lower than the plating solution and not higher than the pH of the plating solution by ringer rolls 31 a and 31 b provided on the outlet side of the second water-washing device 25. . This acidic solution is used after washing the electrogalvanized steel sheet 21 in the post-water washing apparatus 28. Thereafter, the wash water has a pH in the range of 3 to 5, and is fed by the pump 35 to flow through the acidic solution pipe 34, and the first and second injection nozzles 32a, 32b, 33a, 33b are linked to the ringer. It is sprayed on the rolls 31 a and 31 b and applied to the base steel plate 21.

  The wet-treated base steel sheet 21 is inserted into a plating tank 27a provided in the electrogalvanizing apparatus 27, and is subjected to electrogalvanizing in a state where the pH of the plating solution in the width direction is substantially uniform. The base steel plate 21 is plated to become an electrogalvanized steel plate 21 a and is inserted into the post-water washing apparatus 28. The electrogalvanized steel sheet 21 a is washed with water in the plating solution remaining on the surface in the post-water washing device 28. Thereafter, the washing water is used as the acidic solution as described above.

  The electrogalvanized steel sheet 21a cleaned by the post-water washing apparatus 28 is dried by a drying apparatus (not shown) and wound by a winding apparatus, and the production of the electrogalvanized steel sheet is completed.

Examples of the present invention will be described below.
Using the production apparatus 20 shown in FIG. 1, the pH of the acidic solution was changed to produce an electrogalvanized steel sheet, and the appearance was tested. As the base steel sheet, SPCC as defined in Japanese Industrial Standard (JIS) G3141 having a thickness of 1.6 mm and a width of 1219 mm is used, and the production apparatus 20 is passed through at a speed of 70 m / min, and an electrogalvanized steel sheet is obtained. Manufactured.

  The compositions of the alkaline degreasing solution, pickling solution and plating solution used in the alkaline degreasing device 22, the pickling device 24 and the electrogalvanizing device 27 are shown in Table 1.

  The pH of the washing water in the post-water washing which is an acidic solution was changed as follows. When the steel sheet is passed through at the above speed, the pH of the post-cleaning water obtained by the post-water cleaning device 28 is 4. Post-wash water other than pH 4 was adjusted by adding water or sulfuric acid. The relationship between the amount of water or sulfuric acid added and mixed per unit time with the post-wash water and the pH of the resulting post-wash water is tested in advance, and the pH of the post-wash water is lower than 4. In this case, sulfuric acid was added, and when higher than 4, water was added to intentionally change the pH from 3 to 8.

An electrogalvanized steel sheet was manufactured by applying galvanization to a steel sheet wet-treated with post-cleaning water (acid solution) having each pH so that the adhesion amount was 20 g / m ² . The surface of the manufactured electrogalvanized steel sheet was visually observed while being wound with a rewinding device, and whether or not a non-uniform pattern was formed on the surface was examined by visual observation. The evaluation standard of the surface appearance was set as follows.

Evaluation 3: Very good with no pattern Evaluation 2: There is an extremely slight pattern, but there is no problem in quality Evaluation 1: There is a pattern, there is a problem in quality Evaluation 0: There is a clear pattern, and it cannot be used

  The evaluation results are shown in FIG. FIG. 2 is a diagram showing the relationship between the pH of the acidic solution and the evaluation result of the surface appearance. As shown in FIG. 2, when the pH of the acidic solution was 5 or less, a good quality electrogalvanized steel sheet having a rating of 2 or more was obtained.

  As described above, in the present embodiment, the wet treatment means is configured to inject the acidic solution onto the ringer roll and apply it to the steel sheet with the ringer roll. It may be configured to inject directly.

  Moreover, although post-wash water is used for the acidic solution, the present invention is not limited to this, and an aqueous solution in which pH is adjusted by mixing sulfuric acid or the like with water may be used. In the case of using such separately adjusted acidic solution, the wet treatment means may be configured to prepare an acidic solution tank for storing the acidic solution and immerse the raw steel sheet in the tank. The acidic solution is an aqueous solution containing a sulfuric acid component, but is not limited thereto, and may be an aqueous solution containing another acid component such as hydrochloric acid.

It is a figure which shows the structure of the manufacturing apparatus 20 of the electrogalvanized steel plate which is one Embodiment of this invention. It is a figure which shows the relationship between pH of an acidic solution, and the evaluation result of a surface external appearance. It is a figure which illustrates the structure of the conventional electrogalvanized steel plate manufacturing apparatus 1 used for manufacture of an electrogalvanized steel plate. It is a perspective view of the electrogalvanized steel plate 2a plated with insufficient draining.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Electrogalvanized steel plate manufacturing equipment 21 Raw steel plate 22 Alkaline degreasing device 23 First water washing device 24 Pickling device 25 Second water washing device 26 Wet treatment means 27 Electrogalvanizing device 28 Post water washing device 31 Ringer roll 32, 33 Injection nozzle 34 Acid solution line 35 Pump

Claims (6)

In the method for producing an electrogalvanized steel sheet in which an electrogalvanized steel sheet is produced by electrogalvanizing the base steel sheet,
A water washing step for washing the steel sheet to be electrogalvanized with water,
A wet treatment step of wet-treating the surface of the steel sheet with an acidic solution having a pH that is higher than the pH of the plating solution and lower than the pH of the water after washing with water and before electrogalvanizing,
And a plating treatment step of electrogalvanizing a base steel plate wet-treated with an acidic solution with a plating solution. Including a post-water washing step of washing the electrogalvanized steel sheet with water after the plating step;
The method for producing an electrogalvanized steel sheet according to claim 1, wherein the acidic solution is washing water used in a post-water washing step.   The method for producing an electrogalvanized steel sheet according to claim 1 or 2, wherein the pH of the acidic solution is 3 or more and 5 or less. In an electrogalvanized steel sheet manufacturing apparatus for manufacturing an electrogalvanized steel sheet by electrogalvanizing a base steel sheet,
Water washing means for washing the steel sheet to be electrogalvanized with water,
Electrogalvanizing means for electrogalvanizing the steel sheet with a plating solution;
A wet treatment means provided between the water washing means and the electrogalvanizing means for wet-treating the washed steel sheet with an acidic solution having a pH that is not less than the pH of the plating solution and not more than the pH of the water. A device for producing electrogalvanized steel sheets. Further comprising a post-washing means for washing the electrogalvanized steel sheet subjected to electrogalvanization with water,
The apparatus for producing an electrogalvanized steel sheet according to claim 4, wherein the acidic solution is washing water used for washing by a post-water washing means.   6. The apparatus for producing an electrogalvanized steel sheet according to claim 4, wherein the pH of the acidic solution is 3 or more and 5 or less.

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