KR20220055268A - Apparatus of electrogalvanized plating steel plate and method of manufacturing electrogalvanized plating steel plate using the same - Google Patents

Abstract

The present invention provides an electroplating method of a steel plate for preventing a defect by controlling a flow rate of plating solution. According to one embodiment of the present invention, the electroplating method of the steel plate comprises: a step of primarily plating a steel plate; and a step of secondarily plating the primarily plated steel plate. First temperature of the plating solution in primary plating is in a range of 54-57℃, and second temperature of the plating solution in secondary plating is in a range of 50-60℃.

Description

Apparatus of electrogalvanized plating steel plate and method of manufacturing electrogalvanized plating steel plate using the same}

The technical idea of the present invention relates to a method for manufacturing a steel sheet, and more particularly, to an electroplating apparatus for a steel sheet and an electroplating method using the same.

The steel plate for automobile exterior is a part responsible for the exterior of the vehicle, and high strength and beautiful surface are required to improve the permanent preservation ability of the exterior of the vehicle. In order to satisfy this requirement, a method of forming a plating layer on the surface of a steel sheet for automobile exterior plate to prevent corrosion and improve surface paintability is widely used. Electroplating (EG), zinc plating (GA), hot-dip galvanizing plating (GI), etc.

The electroplating is a method of forming a plating layer by an electrochemical method by controlling the strength of an electric current, and has the advantage of forming a uniform plating layer, so the demand for an electroplated steel sheet is increasing.

Korean Patent Application No. 2002-0055208

However, in the electroplating, quality problems have been raised due to the occurrence of various defects such as color difference plating defects, linear stripe defects, and dent defects depending on current density conditions.

The technical problem to be achieved by the technical idea of the present invention is to provide an electroplating apparatus and an electroplating method using the same for preventing defects by controlling the plating solution temperature in order to solve the above problems.

However, these tasks are exemplary, and the technical spirit of the present invention is not limited thereto.

According to one aspect of the present invention, there is provided a method for electroplating a steel sheet.

According to an embodiment of the present invention, the method for electroplating the steel sheet includes the steps of: first plating the steel sheet; and secondary plating of the steel sheet on which the primary plating has been performed, wherein a first temperature of the plating solution in the primary plating is in the range of 54° C. to 57° C., and the second plating solution in the secondary plating includes: 2 The temperature may range from 50°C to 60°C.

According to an embodiment of the present invention, the second temperature of the plating solution in the secondary plating may be in the range of 54 °C to 57 °C.

According to an embodiment of the present invention, the first temperature of the plating liquid in the primary plating and the second temperature of the plating liquid in the secondary plating may be the same temperature.

According to an embodiment of the present invention, the secondary plating may be performed one or more times.

According to an embodiment of the present invention, the primary plating or the secondary plating may be performed by applying a current density in the range of 1 A/dm ² to 200 A/dm ² .

According to an embodiment of the present invention, the flow rate of the plating solution may be in the range of 50 m ³ /hour to 90 m ³ /hour.

According to an embodiment of the present invention, the steel sheet may be fed at a speed of 30 mpm to 100 mpm.

According to an embodiment of the present invention, the steel sheet, by weight, carbon (C): 0.0003% to 0.0034%, silicon (Si): more than 0% to 0.03%, manganese (Mn): 0.05% to 0.7% , aluminum (Al): 0.002% to 0.06%, phosphorus (P): 0.02% to 0.06%, sulfur (S): more than 0% to 0.01%, and the balance may contain iron (Fe) and other unavoidable impurities .

According to one aspect of the present invention, there is provided an electroplating apparatus for a steel sheet.

According to an embodiment of the present invention, the electroplating apparatus for the steel sheet comprises: a first plating cell for primary plating of the steel sheet; and at least one second plating cell for secondary plating the steel sheet on which the primary plating has been performed, wherein a first temperature of the plating solution in the primary plating is in the range of 54°C to 57°C, The second temperature of the plating solution in the plating may be in the range of 50 °C to 60 °C.

According to the technical idea of the present invention, the electroplating method of the steel sheet strictly controls the first temperature of the plating solution in the first plating cell in the range of 54°C to 57°C during initial plating to minimize the surface sensitivity, The formation of plating nuclei having defects can be suppressed. Then, the second temperature of the plating solution of the second plating cell for plating the steel sheet thereafter is controlled on a somewhat relaxed basis in the range of 50°C to 60°C, or is strictly in the range of 54°C to 57°C, similar to the first temperature. can be controlled. Through strict control of the temperature of the plating solution, defects in the plating layer can be prevented, and uniform growth and thickness can be controlled.

The above-described effects of the present invention have been described by way of example, and the scope of the present invention is not limited by these effects.

1 is a schematic diagram showing an electroplating apparatus for a steel sheet according to an embodiment of the present invention.
2 is a schematic diagram showing a plating cell of the electroplating apparatus for the steel sheet of FIG. 1 according to an embodiment of the present invention.
3 is a flowchart illustrating an electroplating method of a steel sheet according to an embodiment of the present invention.
4 is a photograph showing the surface of a steel sheet formed by using the electroplating method of the steel sheet according to an embodiment of the present invention.
5 is a schematic diagram illustrating a plating mechanism in an electroplating method of a steel sheet according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention are provided to more completely explain the technical idea of the present invention to those of ordinary skill in the art, and the following examples may be modified in various other forms, The scope of the technical idea is not limited to the following examples. Rather, these embodiments are provided so as to more fully and complete the present disclosure, and to fully convey the technical spirit of the present invention to those skilled in the art. In the present specification, the same reference numerals refer to the same elements throughout. Furthermore, various elements and regions in the drawings are schematically drawn. Accordingly, the technical spirit of the present invention is not limited by the relative size or spacing drawn in the accompanying drawings.

In the case of the steel sheet for the electroplating outer plate, the thickness and uniformity of the plating layer are changed according to the current density and the production rate applied when the plating layer is formed. When the current density is high, local non-uniform growth of the plated particles occurs, causing a phenomenon of spreading in a spindle shape along the rolling direction around the non-uniformly grown growth nuclei, as a result, over the entire length of the steel sheet coil. Color difference causes plating defects. In general, when the color difference plating defect is more than 10 per square meter, it is evaluated as defective.

1 is a schematic diagram showing an electroplating apparatus 1 for a steel sheet according to an embodiment of the present invention.

Referring to FIG. 1 , the electroplating apparatus 1 includes a first plating cell 10 and at least one second plating cell 20 . Although the number of the second plating cells 20 is shown as 9 in FIG. 1 , this is exemplary and the technical spirit of the present invention is not limited thereto.

The first plating cell 10 may perform primary plating on the steel sheet M at a first plating solution temperature. The second plating cell 20 may perform secondary plating on the steel sheet on which the primary plating has been performed at a second plating solution temperature. This plating method will be described in detail below with reference to FIG. 3 .

After the steel plate M is degreased and washed with water, it enters the electroplating apparatus 1 . The steel sheet M is subjected to primary plating in the first plating cell 10 , and then secondary plating is performed in the second plating cell 20 . The secondary plating may be performed a plurality of times. Then, when the secondary plating is finished, the steel sheet M is washed with water and post-treated as a subsequent process.

2 is a schematic view showing the plating cells 10 and 20 of the electroplating apparatus 1 of the steel sheet of FIG. 1 according to an embodiment of the present invention.

Referring to FIG. 2 , the illustrated plating cells 10 and 20 may show a first plating cell 10 and a second plating cell 20 . That is, the first plating cell 10 and the second plating cell 20 may have the same structure.

The first and second plating cells 10 and 20 include a plating bath 12 , first and second conductive rolls 13 and 14 , an immersion roll 16 , and an electrode 18 . The plating bath 12 may accommodate the plating solution 19 . The first and second conductive rolls 13 and 14 are disposed on the upper side of the plating bath 12, are made of a conductive material such as metal, and a negative voltage can be applied by a power source (not shown). there is. The immersion roll 16 is located inside the plating bath 12 so as to be immersed in the plating solution 19 , and may be composed of a non-conductive material such as rubber. The electrode 18 is composed of at least one or more and is positioned inside the plating bath 12 so as to be immersed in the plating solution 19 . The electrode 18 is made of a conductive material such as a metal, and a positive (+) voltage may be applied by the power source (not shown).

The steel plate M may be moved in the following manner. The steel plate M is wound around the first conductive roll 13 and moves downward by the rotation of the first conductive roll 13 , enters the plating bath 12 , and is immersed in the plating solution 19 . Subsequently, the steel sheet M is wound around the dip roll 16 in the plating solution 19 , and moves upward by the rotation of the dip roll 16 , and is discharged to the outside of the plating bath 12 . Then, the steel sheet M is wound around the second conductive roll 14 and moves downward by the rotation of the second conductive roll 14 to enter the subsequent plating cell.

The steel plate M may be plated in the following manner, and the front and back surfaces of the steel plate M may be plated simultaneously according to the arrangement of the electrodes 18 .

A negative voltage is applied to at least one of the first and second conductive rolls 13 and 14 . Accordingly, the negative voltage is also applied to the steel plate M in contact with the first and second conductive rolls 13 and 14 . Also, a positive voltage is applied to the electrode 18 . A current flows in the plating solution 19 by this voltage application, and cations such as metal ions in the plating solution 19 move to the surface of the steel sheet M to be plated. When the steel plate M moves between the electrodes 18 in the downward and upward directions, the positive ions may be plated on the surface of the steel plate M. The current density of the current in such plating may range, for example, from 1 A/dm ² to 200 A/dm ² .

The plating solution 19 may include a plating material, for example, a metal material, for example, zinc (Zn) or the like. The solvent of the plating solution 19 may include sodium sulfate solution or sulfuric acid.

The plating solution 19 may be introduced into the plating bath 12 through the inlet 15 at an inlet speed V ₀ . The introduced plating solution 19 may pass through the plating bath 12 and be discharged to the outside through the outlet 17 at a discharge speed V _T .

In the first plating cell 10 and the second plating cell 20 , in the region where the steel sheet M descends, the plating solution 19 may flow at a first flow rate V ₁ , and the steel sheet M is In the rising region, the plating solution 19 may flow at a second flow rate V ₂ . Both the first flow rate (V ₁ ) and the second flow rate (V ₂ ) may be in an upward direction from the inlet 15 to the outlet 17 . The first flow rate V ₁ and the second flow rate V ₂ may be, for example, in the range of 50 m ³ /hour to 90 m ³ /hour. The first flow rate V ₁ and the second flow rate V ₂ may be the same or different from each other.

The first temperature of the plating solution of the first plating cell 10 may be, for example, in the range of 54 °C to 57 °C. The second temperature of the plating solution of the second plating cell 20 may be, for example, in the range of 50°C to 60°C, for example, in the range of 54°C to 57°C.

The flow rate of the plating solution of the first plating cell 10 may be, for example, in the range of 50 m ³ /hour to 90 m ³ /hour. The flow rate of the plating solution of the second plating cell 20 may be, for example, in the range of 50 m ³ /hour to 90 m ³ /hour.

An electroplating apparatus 1 for a steel sheet according to the technical idea of the present invention includes: a first plating cell 10 for primary plating of a steel sheet; and at least one second plating cell 20 for secondary plating the steel sheet on which the primary plating has been performed.

3 is a flowchart illustrating an electroplating method of a steel sheet according to an embodiment of the present invention.

Referring to FIG. 3 , the electroplating method of the steel sheet includes the steps of first plating the steel sheet (S10); and secondary plating (S20) of the steel sheet on which the primary plating has been performed.

The primary plating and the secondary plating may be performed in different plating cells. For example, the primary plating may be performed in the first plating cell 10 , and the secondary plating may be performed in the second plating cell 20 . The secondary plating may be performed one or more times according to a plating target.

The first temperature of the plating solution in the primary plating may be, for example, in the range of 54 °C to 57 °C. The second temperature of the plating solution in the secondary plating may be, for example, in the range of 50 °C to 60 °C and the second temperature of the plating liquid in the secondary plating may be in the range of, for example, 54 °C to 57 °C . The first temperature of the plating solution in the primary plating and the second temperature of the plating solution in the secondary plating may be the same temperature.

The steel sheet may be transferred such that the primary plating and the secondary plating are continuously performed, for example, transferred from the first plating cell 10 to the second plating cell 20 . The steel sheet may be fed at a speed of 30 mpm (meter per minute) to 100 mpm.

The primary plating or the secondary plating may be performed by applying a current density in the range of 1 A/dm ² to 200 A/dm ² .

The steel sheet, by weight, carbon (C): 0.0003% to 0.0034%, silicon (Si): more than 0% to 0.03%, manganese (Mn): 0.05% to 0.7%, aluminum (Al): 0.002% to 0.06%, phosphorus (P): 0.02% to 0.06%, sulfur (S): more than 0% to 0.01%. The remainder consists of iron (Fe) and impurities that are unavoidably contained in the steelmaking process. However, this is exemplary, and the technical spirit of the present invention is not limited by the above content.

In the electroplating method of a steel sheet according to the technical idea of the present invention, the first temperature of the plating solution in the first plating cell for plating the steel sheet is strictly controlled in the range of 54° C. to 57° C. to minimize the surface sensitivity, and defects It is possible to suppress the formation of plating nuclei having Then, the second temperature of the plating solution of the second plating cell for plating the steel sheet thereafter is controlled on a somewhat relaxed basis in the range of 50°C to 60°C, or is strictly in the range of 54°C to 57°C, similar to the first temperature. can be controlled. Through strict control of the temperature of the plating solution, defects in the plating layer can be prevented, and uniform growth and thickness can be controlled.

Experimental example

Hereinafter, preferred experimental examples are presented to help the understanding of the present invention. However, the following experimental examples are only for helping understanding of the present invention, and the present invention is not limited by the following experimental examples.

A steel sheet having the composition shown in Table 1 below was prepared. The remainder consists of iron (Fe) and impurities that are unavoidably contained in the steelmaking process. The compositions of Comparative Examples and Examples were the same.

ingredient C Si Mn Al P S content (wt%) 0.0017 0.01 0.35 0.03 0.04 0.005

However, the composition of the steel sheet shown in Table 1 is exemplary, and the technical spirit of the present invention is not limited thereto, and various steel sheets may be applied.

Table 2 shows the plating conditions and the results of the steel sheet.

division 1st plating cell
plating solution temperature
(℃) 2nd to 10th plating cell
plating solution temperature
(℃) spot spot defect
(number per 1 m ² ) grater
quality
evaluation obverse The back Sum Example 1 54 54 4 5 9 Good Example 2 56 56 5 4 9 Good Example 3 55 55 3 2 5 Good Example 4 56 56 4 4 8 Good Example 5 54 54 3 4 7 Good Example 6 55 55 2 4 6 Good Comparative Example 1 50 50 10 16 26 error Comparative Example 2 51 51 5 9 14 error Comparative Example 3 52 52 9 7 16 error Comparative Example 4 53 53 8 5 13 error Comparative Example 5 53 53 6 6 12 error Comparative Example 6 58 58 6 13 19 error Comparative Example 7 59 59 9 11 20 error Comparative Example 8 57 57 5 7 12 error

In Table 2, the first plating cell is a plating cell on which the steel sheet is first plated, and the number is one, and the second plating cell is a plating cell to be plated after being plated in the first plating cell, and the number is nine. Therefore, the total number of plating cells was 10.

In the steel sheet quality evaluation, point spot defects were selected as color difference plating defects, and when the number of spot spot defects is 10 or less per 1 m ² , it is evaluated as “good”, and when it exceeds 10, it is evaluated as “poor” did

Referring to Table 2, in Examples 1 to 6, plating was performed by strictly controlling the temperatures of the first plating cell and the second plating cell in the range of 54°C to 57°C. In the Examples, as the number of spot spot defects was 10 or less, which is the evaluation criterion, all were evaluated as good.

In Comparative Examples 1 to 5, the temperature of the first plating cell and the second plating cell is less than 54°C, and in Comparative Examples 6 to 8, the temperature of the first plating cell and the second plating cell is a temperature greater than 57°C. In Comparative Examples, as the number of spot spot defects was more than 10, which is the evaluation criterion, all of them were evaluated as defective.

4 is a photograph showing the surface of a steel sheet formed by using the electroplating method of the steel sheet according to an embodiment of the present invention.

4, the surface of the steel plate of Example 1 and the surface of the steel plate of Comparative Example 1 are shown. It can be seen that, in Example 1, no prominent spot spot defects were found, but in Comparative Example, spot spot defects were prominently displayed.

5 is a schematic diagram illustrating a plating mechanism in an electroplating method of a steel sheet according to an embodiment of the present invention.

Referring to FIG. 5 , in the case of the embodiment, the plating solution temperature is strictly controlled in a range of 54° C. to 57° C. so that the size of the plating core may be smaller than that of the largest plating core of the comparative example, but it has a uniform size. can Accordingly, in subsequent plating, growth from the plating nucleus is uniformly performed as a whole, and as a result, the plating layer forms a uniform plating surface. Accordingly, the formation of spot spot defects is suppressed and peeling of the plating layer or defects in the final steel sheet can be prevented. In particular, it is preferable to control the temperature of the plating solution of the first plating cell in which the first plating is performed in the range of 54°C to 57°C.

In the case of the comparative example, when the temperature of the plating solution is lower than 54° C., the electrodeposition and crystallization rates of zinc may be slowed, thereby causing non-uniform plating layer formation. This problem may be particularly noticeable when the temperature of the plating solution of the first plating cell in which the first plating is performed is as low as 54° C. or less.

In addition, in the case of the comparative example, when the temperature of the plating solution exceeds 57° C., the growth of the already formed plating crystal grains is non-uniformly promoted, and a coarse plating layer is generated and the plating surface is not beautiful. In particular, this problem may appear conspicuously when the temperature of the plating solution of the first plating cell in which the first plating is performed is higher than 57°C.

The technical spirit of the present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is the technical spirit of the present invention that various substitutions, modifications and changes are possible within the scope without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill in the art to which this belongs.

1: electroplating device, 10, 20: plating cell,
12: plating bath, 13: first conductive roll,
14: second conductive roll, 15: inlet,
16: dip roll, 17: outlet,
18: electrode, 19: plating solution,

Claims (9)

First plating the steel sheet; and
Including; secondary plating of the steel sheet on which the primary plating has been performed;
The first temperature of the plating solution in the primary plating is in the range of 54 ℃ to 57 ℃,
The second temperature of the plating solution in the secondary plating is in the range of 50 ℃ to 60 ℃,
Electroplating method of steel sheet. The method of claim 1,
The second temperature of the plating solution in the secondary plating is in the range of 54 ℃ to 57 ℃,
Electroplating method of steel sheet. The method of claim 1,
The first temperature of the plating solution in the primary plating and the second temperature of the plating solution in the secondary plating are the same temperature,
Electroplating method of steel sheet. The method of claim 1,
The secondary plating is performed one or more times,
Electroplating method of steel sheet. The method of claim 1,
The primary plating or the secondary plating is performed by applying a current density in the range of 1 A/dm ² to 200 A/dm ² ,
Electroplating method of steel sheet. The method of claim 1,
The flow rate of the plating solution is in the range of 50 m ³ / hour to 90 m ³ / hour,
Electroplating method of steel sheet. The method of claim 1,
The steel sheet is transported at a speed of 30 mpm to 100 mpm,
Electroplating method of steel sheet. The method of claim 1,
The steel sheet, by weight, carbon (C): 0.0003% to 0.0034%, silicon (Si): more than 0% to 0.03%, manganese (Mn): 0.05% to 0.7%, aluminum (Al): 0.002% to 0.06%, phosphorus (P): 0.02% to 0.06%, sulfur (S): more than 0% to 0.01%, and the balance contains iron (Fe) and other unavoidable impurities;
Electroplating method of steel sheet. a first plating cell for primary plating of a steel sheet; and
At least one second plating cell for performing secondary plating of the steel sheet on which the primary plating has been performed; includes;
The first temperature of the plating solution in the primary plating is in the range of 54 ℃ to 57 ℃,
The second temperature of the plating solution in the secondary plating is in the range of 50 ℃ to 60 ℃,
Electroplating equipment for steel sheet.

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