Method for cleaning hot dip galvanized steel sheet and cleaning apparatus therefor
AssigneeJfe Steel Corporation
InventorsSatoshi Yoneda, Takahiro Sugano
Life of this patent
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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.
Claims8
A method for cleaning a hot dip galvanized steel sheet comprising the steps of:
- continuously transferring a strip-shaped hot dip galvanized steel sheet, treated by a surface oxidation;
- spraying a cleaning liquid to the hot dip galvanized steel sheet in a first cleaning step;
- contacting the hot dip galvanized steel sheet with the cleaning liquid for 1 second or more;
- spraying a diluted cleaning liquid to the hot dip galvanized steel sheet in a second cleaning step;
- spraying a pure water to the hot dip galvanized steel sheet in a third cleaning step;
- discharging the cleaning liquid and the pure water, sprayed to the hot dip galvanized steel sheet, to form a diluted cleaning liquid of the cleaning liquid diluted by the pure water in a discharging step;
- circulating the diluted cleaning liquid from the discharging step to the second cleaning step;
- and
- providing an inverting roller for inverting a traveling direction of the hot dip galvanized steel sheet 180 ° from a first upside location to a downside location in a vertical direction and then from the downside location to a second upside location in a vertical direction, so that the traveling direction of the hot dip galvanized steel begins at the first cleaning step and terminates at the third cleaning step, thereby allowing the cleaning liquid to drip from the hot dip galvanized steel sheet at a lowermost bottom position of the inverting roller;
- wherein the diluted cleaning liquid is sprayed onto the hot dip galvanized sheet after the inverting of the hot dip galvanized steel sheet, at a position between the first cleaning step and the third cleaning step, and
- wherein the second cleaning step and the third cleaning step are continuously performed at the second upside location.
Dependencies are inferred from the claim text.