JPH06330377A - Production of galvanized steel sheet - Google Patents

Abstract

PURPOSE:To form a plated film having uniform gloss in the width direction of the steel sheet and excellent plating adhesive strength by washing away a plating liquid stuck and remaining by dashing a cleaning liquid on a steel surface in a laminar flow at the position where a galvanized steel sheet came out from the plating liquid. CONSTITUTION:At the position whose the steel sheet 9 galvanized with a film of zinc alloy by dipping into the plating liquid came out from the plating liquid, the cleaning liquid 10 is dashed on the surface of the steel sheet 9 in a laminar flow from a laminar flow header 11 provided on the upper side via a straigntening plate. At this time, the installed position of the header 11 is set in the range of about 100-700mm above the liquid surface and an ejection quantity of the cleaning liquid is made >=0.2m<3>/H for header. Thus, the gloss in the width direction of the steel sheet 9 is made uniform and the plated film with excellent adhesive strength is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for electroplating a zinc or zinc-based alloy film having a uniform gloss in the width direction of a steel sheet and having good plating adhesion.

[0002]

2. Description of the Related Art Generally, in a method of electroplating a zinc or zinc-based alloy film on the surface of a steel sheet, the steel sheet is immersed in a plating solution and electroplated, and then the steel sheet is placed at a position out of the plating solution. A method of washing away the plating solution remaining on the surface of the steel sheet is performed. At this time, as a cleaning method, there is known a method in which a specific cleaning liquid is jetted from the spray header onto the steel plate as disclosed in Japanese Patent Application Laid-Open No. 4-301094.

[0003]

However, in the above-mentioned conventional method, a part of the sprayed cleaning liquid adheres to the plated surface after cleaning, or when the sprayed cleaning liquid collides with the steel sheet, it scatters randomly, There is a problem that the part reattaches to the plated surface after cleaning, and uneven gloss occurs in the width direction of the steel sheet due to chemical dissolution of the plating. At present, it is difficult to completely prevent this even if the angle of the spray on the steel plate is changed.

Further, even if the jetting pressure of the cleaning solution is lowered for the purpose of avoiding this problem, it is not very effective, and it is difficult to wash away the remaining plating solution, resulting in poor plating adhesion. Also occurs. There are various possible reasons for poor plating adhesion, but in the case of Zn-Ni alloy plating, it is as follows, for example.

If the cleaning is not sufficient, there will be a portion where the plating solution adheres and remains for a long time as compared with other portions. Where
The reaction of Ni ²⁺ + Zn → Ni ↓ + Zn ²⁺ occurs, the Ni weight ratio of the plating increases and the plating adhesion decreases. The present invention is intended to provide a method for producing a zinc-based plated steel sheet which prevents the occurrence of uneven gloss in the steel sheet width direction of the zinc- or zinc-based alloy electroplated steel sheet and has good plating adhesion. is there.

[0006]

The present invention provides a method for electroplating a zinc or zinc-based alloy film on the surface of a steel sheet, wherein the steel sheet is immersed in a plating solution and electroplated, and then the steel sheet is plated with the plating solution. The method for producing an electrogalvanized steel sheet is characterized in that, when the plating solution adhering and remaining on the surface of the steel sheet is washed away at the position out of, the cleaning solution is applied to the surface of the steel sheet in a laminar flow.

[0007]

According to the present invention, the method of rinsing away the plating solution remaining on the surface of the steel sheet is such that the cleaning solution naturally flows down to the steel sheet in a laminar flow to clean the steel sheet. Part of the cleaning solution that adhered adheres to the plated surface after cleaning, or the sprayed cleaning solution randomly scatters when colliding with the steel sheet, and part of it does not re-adhere to the plated surface after cleaning. The problem of uneven gloss in one direction can be completely prevented.

Next, a case where the plating layer for carrying out the present invention is a radial cell will be described with reference to FIG. 1 as a typical example. However, it goes without saying that the present invention can be applied to vertical and horizontal plating cells. In the figure, reference numeral 1 denotes a plating tank in which container-shaped plating cells 2 and 3 having an open upper side are continuously provided, and a plating solution is contained in each plating cell 2 and 3. Further, each plating cell 2, 3 is provided with a cylindrical conductor roll 4, 5 also serving as a cathode of an electroplating electrode, and half-moon shaped anode electrodes 6, 7 at positions facing the conductor rolls 4, 5. . The conductor rolls 4 and 5 are partly immersed in a plating solution to be arranged in the plating cells 2 and 3, and the anode electrodes 6 and 7 are arranged to face the lower sides of the conductor rolls 4 and 5, respectively. ing.

Further, a cylindrical deflector roll 8 is arranged above the plating tank 1 between the plating cells 2 and 3. The steel plate 9 to be plated is immersed in the plating solution while being wound around the lower outer circumference of the conductor roll 4 between the conductor roll 4 and the anode electrode 6 provided in the plating cell 2 on the inlet side of the plating tank 1. pass. Further, the steel sheet 9 is discharged from the plating solution upward, and while passing around the upper outer circumference of the deflector roll 8, passes between the conductor roll 5 and the anode electrode 7 provided in the next plating cell 3 and passes through the plating cell 2. As in the case of the above, the liquid passes through and drains upward from the plating solution.

Therefore, in order to carry out the method of the present invention,
At the position where the steel plate 9 is projected upward from the plating solution, a header 11 is applied to the steel plate 9 where a cleaning solution 10 for washing off the plating solution is applied in a laminar flow.
It is provided facing the plated surface of. FIG. 2 is an enlarged view of the header 11. The cleaning liquid 10 discharged from the header 11 is laminarized on the straightening vane and naturally flows down to clean the plated surface of the steel plate 9.

At this time, if the discharge amount of the cleaning liquid is less than 0.2 m ³ / H per 1 m of the plate width per plate width, it is difficult to wash off the plating liquid remaining on the plated steel plate. Is preferably 0.2 m ³ / H or more per header. Further, the position where the header 11 is installed will be described in the embodiment as being 100 mm above the liquid level, but it is necessary to wash off the plating solution at a position within 700 mm above the plating level. Because
This is because the reaction between the plating surface and the plating solution proceeds as the plating solution remains attached to the steel sheet after plating for a longer time, and the glossiness and the plating adhesion in the width direction of the steel sheet decrease.

The present invention will be specifically described below based on examples.

[0013]

Example Using the radial cell shown in FIG. 1, operation was performed under the plating solution and plating conditions shown in Table 1. Table 2 shows the results of implementation. As can be seen from the results, the uneven gloss as shown in FIG. 3 was eliminated by using the header in which the cleaning liquid was applied in a laminar flow. The cleaning liquid used was purified water.
Further, FIG. 3 is a diagram showing an example in the case where there is slight uneven gloss.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

As described above, according to the present invention, after the steel sheet is immersed in the plating solution and electroplated, the steel sheet adheres and remains on the surface of the steel sheet at the position where the steel sheet comes out of the plating solution. When the plating solution is washed away, the header is such that the cleaning solution is applied in a laminar flow.Therefore, as when using a spray header, part of the sprayed cleaning solution adheres to the plated surface after cleaning, or the cleaning solution sprayed out. It was possible to completely prevent the problem that the particles randomly scattered when colliding with the steel sheet and reattached to the plated surface after cleaning, and the unevenness of gloss occurred in the steel sheet width direction due to chemical dissolution of the plating.

[Brief description of drawings]

FIG. 1 is a diagram showing a radial cell to which the method of the present invention has been applied.

FIG. 2 is a cross-sectional view showing a header in which the cleaning liquid is applied to the steel sheet in a laminar flow.

FIG. 3 is a diagram showing an example of defective gloss unevenness.

[Explanation of symbols]

 1 Plating tank 2 Plating cell 3 Plating cell 4 Conductor roll 5 Conductor roll 6 Anode electrode 7 Anode electrode 8 Deflector roll 9 Steel plate 10 Cleaning liquid 11 Laminar flow header

Claims (1)

[Claims] 1. A method of electroplating a film of zinc or a zinc-based alloy on a surface of a steel sheet, wherein the steel sheet is immersed in a plating solution and electroplated, and then the steel sheet is removed from the plating solution. A method for producing an electrogalvanized steel sheet, wherein the washing solution is applied to the surface of the steel sheet in a laminar flow when the plating solution remaining on the surface of the steel sheet is washed away.