JPH0610151A - Method for obtaining nonchromated plated steel sheet - Google Patents

Abstract

PURPOSE:To manufacture a nonchromated plated steel sheet free from unevenness in chemical convertion within a short time by spraying water on both faces of the plated steel sheet or on the face not in contact with a roll. CONSTITUTION:A plated steel sheet 8 is passed through vertical chromating equipment 10 to manufacture a chromated steel sheet and a nonchromated steel sheet. At this time, in the case the nonchromated material is obtd. in the process of passing the sheet, a spray 7 is set on the inlet of a chromating tank 9 at least before the plated steel sheet 8 is brought into contact with the roll 6 in the treating tank, and water is sprayed on both faces of the plated steel sheet 8 or on the face at which the plated steel sheet non in contact with the roll 6. Thus, the state of the plated steel sheet 8 is formed into an undried one. In this way, the chemical convertibility of the plated steel can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for obtaining a chromate-free material for a plated steel sheet, and an object thereof is to improve the chemical conversion treatability of the plated steel sheet.

[0002]

2. Description of the Related Art Conventionally, a coil of plated steel sheet is passed through a vertical chromate treatment facility to produce a chromate treated steel sheet or a non-chromate treated steel sheet from a single coil. Therefore, when performing chromate treatment, supply chromate to a vertical chromate treatment facility and pass it through,
When the chromate treatment is not performed, the chromate solution in the chromate treatment facility is stopped and the coated steel sheet is passed through while washing the roll with water.

Referring to FIG. 1, reference numeral 9 is a vertical chromate treatment tank, and the plated steel plate 8 is a direction changing roll 6
Is guided vertically upward by the roll 3 that straightens the warp of the plated steel sheet 8, and in the case of chromate treatment, a chromate solution is sprayed from the spray 2 onto the plated steel sheet 8 and subjected to chromate treatment.

When the plated steel plate 8 is not subjected to chromate treatment, the chromate treatment liquid spray 2 is stopped and the cleaning water spray 1 cleans the rolls 3 and 6 with water. However, the liquid splashed from the bottom of the chromate tank 4 is sprayed. However, there was a problem that the plated steel sheet produced by No. 5 was contaminated and a chemical conversion treatment failure occurred depending on the chemical conversion treatment method.

[0005]

SUMMARY OF THE INVENTION According to the present invention, the rolls 3 and 6 in the plated steel sheet passing through the chromate treatment tank are used.
The purpose of the present invention is to prevent the contamination of the plated steel sheet with the chromate residue liquid generated by the washing.

[0006]

Means for Solving the Problems The present invention passes a plated steel sheet through a vertical chromate treatment facility, and when producing a chromate-treated and chromate-untreated steel sheet, when a chromate-untreated material is obtained during the passage, A spray is installed at the entrance of the chromate treatment tank of the vertical chromate treatment equipment, at least before contact with the roll in the treatment tank for the plated steel sheet, and water is sprayed on both sides of the plated steel sheet or on the surface where the plated steel sheet does not come into contact with the roll. A method for obtaining a chromate-untreated plated steel sheet, characterized in that the steel sheet is kept in a non-dried state.

[0007]

The present invention will be described below with reference to the drawings. Figure 1
FIG. 3 is a diagram showing an example of the present invention. 1 is a cleaning spray used when no chromate treatment is performed, and 2 is a spray of a chromate treatment liquid. 3 is plated steel plate 8
Is a roll that corrects the warp of the paper, and its surface is contaminated with impurities such as a chromate treatment liquid. Reference numeral 4 denotes accumulated water that is the liquid sprayed from the cleaning spray 1 and the chromate treatment liquid spray 2, and contains impurities such as the chromate treatment liquid. A liquid 5 from the cleaning spray 1 flows down into the stripped water 4 and splashes. 6 is a plated steel plate 8
Is a roll that changes the traveling direction of the, and its surface is contaminated with impurities such as a chromate treatment liquid. Reference numeral 7 is a spray used when the chromate treatment is not performed. The spray 7 is disposed near the inlet of the chromate treatment tank 9 and before the plated steel plate 8 entering in a dry state comes into contact with the splashing liquid 5 and the roll 6 is the plated steel plate. The surface of the plated steel sheet 8 is brought into a non-dried state before it comes into contact with the roll 8. When the plated steel sheet 8 comes in contact with the roll 5 and the roll 6, the plated steel sheet 8 comes up in the dry state with the liquid 5 and Impurities adhering to the plated steel plate 8 are significantly reduced as compared with the case where the roll 6 is contacted. In the figure, 10 is a chromate treatment facility.

FIG. 2 shows the time for passing the chromate untreated material,
It is the figure which showed the relationship of the chemical conversion processability score. In the present invention,
Board thickness 0.4 to 1.6 mm, board width 610 to 1219 mm,
A GI zero spangle material having a zinc adhesion amount of 60 to 120 g / m ^{2 on} both sides is passed without chromate treatment. The difference between the conventional method and the conventional method is that the plated steel plate 8 is exposed to the liquid 5 and the rolls 6 for 15 to 60 min /
Liquid 5 sprayed with 1 l of purified water and splashed on the plated steel plate 5
And the non-dry state before coming into contact with the roll 6.

The untreated material passing time means the elapsed time of the untreated material passing after the chromate treatment is completed when the untreated material is continuously passed after the chromate treated material is passed. .

The chemical conversion treatment rating is a grade of local color unevenness that occurs when a specific chemical conversion treatment is performed, based on the number and shade of the color unevenness. The larger the color is and the closer it is to black, the worse the score.

A score of 0 indicates that no chemical conversion treatment unevenness occurs at all, a score of 1 indicates that several thin chemical conversion irregularities occur within 300 mm × 300 mm, and a score of 2 indicates 300 mm × 300 m.
A few uneven chemical formations occurred in m, and a score of 3 was 30.
0 mm x 300 mm The formation unevenness was several tens or more.

The curve in FIG. 2 will be described. When the present invention is compared with the conventional one, the chemical conversion treatability score is improved in the present invention. The cause of deteriorating the chemical conversion treatment score is that the splashing liquid 5 adheres to the plated steel sheet 8 to form an impurity film such as chromic acid on the surface of the plated steel sheet 8, and the chemical conversion treatment film having different properties at that portion during the chemical conversion treatment. Is formed. Once a film of impurities such as chromic acid is formed on the surface of the plated steel plate 8, the film cannot be removed even by washing. Therefore, in order to improve the chemical conversion treatment rating, the liquid 5 and the roll 6 and the plated steel plate are splashed. It is necessary not to form an impurity film such as chromic acid on the surface of No. 8.

As a result of various experiments, the reaction between the splashing liquid 5 and the roll 6 and the plated steel sheet 8, that is, the formation of an impurity film such as chromic acid on the surface of the plated steel sheet 8, is more than that when the plated steel sheet 8 is in a dry state. It turned out that the non-dry state is less likely to occur. Therefore, the chemical conversion treatment property score of the present invention becomes better than that of the conventional one. Further, as the untreated material passing time increases, the improvement in the chemical conversion treatment score is observed. As the untreated material passing time increases, the concentration of impurities and the like on the surface of the liquid 5 and the roll 6 that splashes up. Is decreased, and the reaction with the plated steel sheet 8 is less likely to occur.

[0014]

According to the present invention, it is possible to produce a chromate-free plated steel sheet in which chemical conversion treatment unevenness does not occur in a shorter time than ever before.

[Brief description of drawings]

FIG. 1 Vertical chromate equipment for carrying out the method of the present invention

FIG. 2 shows the relationship between the unprocessed material passing time and the chemical processability rating.

[Explanation of symbols]

 1 Spray for cleaning 2 Spray of chromate treatment liquid 3 Roll to correct warpage of plated steel plate 4 Stagnant water 5 Splashing liquid 6 Roll to change traveling direction of plated steel plate 7 Water spray used when not performing chromate 8 Plated steel plate 9 Vertical chromate treatment tank 10 Vertical chromate treatment equipment

Claims (1)

[Claims] 1. When a plated steel sheet is passed through a vertical chromate treatment facility to produce a chromate-treated and chromate-untreated steel sheet, a chromate treatment of a vertical chromate treatment facility is used when a chromate-free material is obtained in the strip. A spray is installed at the entrance of the tank, at least before contact with the roll in the treatment tank of the plated steel sheet, and water is sprayed on both sides of the plated steel sheet or the surface where the plated steel sheet does not come into contact with the roll to make the plated steel sheet non-dry. A method for obtaining a chromate-free untreated plated steel sheet.