Method for Cleaning Hot Dip Galvanized Steel Sheet and Cleaning Apparatus Therefor

• US 20090283110A1
• Filed: 01/22/2007
• Published: 11/19/2009
• Est. Priority Date: 01/26/2006
• Status: Active Grant

• Current Assignee: JFE Steel Corporation (JFE Holdings Incorporated)
• Original Assignee: JFE Steel Corporation (JFE Holdings Incorporated)
• Inventors: Yoneda, Satoshi, Sugano, Takahiro
• Granted Patent: US 8,940,100 B2
• Time in Patent Office: Days
• US Class Current: 134/2
• CPC Class Codes: B08B 3/022 Cleaning travelling work B08B3/042 takes precedence
• CPC Class Codes: C23G 1/02 with acid solutions
• CPC Class Codes: C23G 3/023 by spraying

Abstract

Cleaning of a hot dip galvanized steel sheet is conducted by bringing a strip-shaped steel sheet which was treated by surface oxidation in advance into contact with a cleaning liquid for 1 second or more, and then bringing the hot dip galvanized steel sheet into contact with pure water, while continuously transferring the hot dip galvanized steel sheet. The method allows efficiently and fully washing off the acidic solution adhered to the surfaces of the hot dip galvanized steel sheet treated by surface oxidation. The invention also provides an apparatus for cleaning the hot dip galvanized steel sheet to carry out the above cleaning method.

Claims

1. A method for cleaning hot dip galvanized steel sheet comprising steps of contacting a strip-shaped hot dip galvanized steel sheet, treated by surface oxidation in advance, with a cleaning liquid for 1 second or more, and then contacting the hot dip galvanized steel sheet with pure water, while continuously transferring the hot dip galvanized steel sheet.

2. The method for cleaning hot dip galvanized steel sheet according to claim 1, wherein the contact with the cleaning liquid and the contact with the pure water are conducted in a single cleaning tank.

3. The method for cleaning hot dip galvanized steel sheet according to claim 2, wherein a diluted cleaning liquid prepared by mixing the cleaning liquid with the pure water in the single cleaning tank is stored in a circulation tank, and the hot dip galvanized steel sheet contacts further with the diluted cleaning liquid in the circulation tank, while utilizing the diluted cleaning liquid by recirculating thereof.

4. The method for cleaning hot dip galvanized steel sheet according to claim 3, wherein the contact of the diluted cleaning liquid is given at a position after a position of beginning the contact with the cleaning liquid and at a position before a position of beginning the contact with the pure water.

5. The method for cleaning hot dip galvanized steel sheet according to claim 1, wherein the cleaning liquid contains P.

6. The method for cleaning hot dip galvanized steel sheet according to claim 5, wherein the P concentration in the cleaning liquid is in a range from 4 to 70 ppm by mass.

13. The method for cleaning hot dip galvanized steel sheet according to claim 2, wherein the cleaning liquid contains P.

14. The method for cleaning hot dip galvanized steel sheet according to claim 3, wherein the cleaning liquid contains P.

15. The method for cleaning hot dip galvanized steel sheet according to claim 4, wherein the cleaning liquid contains P.

16. The method for cleaning hot dip galvanized steel sheet according to claim 13, wherein the P concentration in the cleaning liquid is in a range from 4 to 70 ppm by mass.

17. The method for cleaning hot dip galvanized steel sheet according to claim 14, wherein the P concentration in the cleaning liquid is in a range from 4 to 70 ppm by mass.

18. The method for cleaning hot dip galvanized steel sheet according to claim 15, wherein the P concentration in the cleaning liquid is in a range from 4 to 70 ppm by mass.

7. An apparatus for cleaning hot dip galvanized steel sheet comprising:

a cleaning liquid spray nozzle which sprays a cleaning liquid to both surfaces of a strip-shaped hot dip galvanized steel sheet which was treated by surface oxidation and which is continuously traveling; and

a pure water spray nozzle which sprays pure water to both surfaces of the hot dip galvanized steel sheet at a position where the hot dip galvanized steel sheet travels 1 second or more after being sprayed with the cleaning liquid.

8. The apparatus for cleaning hot dip galvanized steel sheet according to claim 7, further comprising an inverting roller to invert a traveling direction of the hot dip galvanized steel sheet, at a position between the spraying position of the cleaning liquid spray nozzle and the spraying position of the pure water spray nozzle.

9. The apparatus for cleaning hot dip galvanized steel sheet according to claim 7, wherein both the cleaning liquid spray nozzle and the pure water spray nozzle are arranged in a single cleaning tank.

10. The apparatus for cleaning hot dip galvanized steel sheet according to claim 9, further comprising:

a circulation tank which stores a diluted cleaning liquid prepared by mixing the cleaning liquid with the pure water in the single cleaning tank; and

a diluted cleaning liquid spray nozzle which sprays the diluted cleaning liquid in the circulation tank to both surfaces of the hot dip galvanized steel sheet.

11. The apparatus for cleaning hot dip galvanized steel sheet according to claim 10, wherein the diluted cleaning liquid spray nozzle is located between a spraying position of the cleaning liquid spray nozzle and a spraying position of the pure water spray nozzle.

12. A method for cleaning strip-shaped hot dip galvanized steel sheet while continuously transferring a strip-shaped hot dip galvanized steel sheet which was treated by surface oxidation, comprising steps of:

contacting the hot dip galvanized steel sheet with a cleaning liquid for 1 second or more; and

then contacting the hot dip galvanized steel sheet with pure water.