METHOD AND DEVICE FOR AVOIDING SURFACE DEFECTS CAUSED BY ZINC DUST IN A CONTINUOUS STRIP GALVANISING PROCESS

The invention relates to a method and to an apparatus for avoiding surface defects, which are caused by zinc dust, on galvanized metal strip in continuous strip galvanization, in which metal strip which is to be galvanized and is heated in a continuous annealing furnace is moved through a furnace pi...

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Bibliographische Detailangaben
Hauptverfasser:	PETERS, Michael, SCHAFFRATH, Norbert, ZEIZINGER, Sabine, PETERS, Klaus, Josef, NOTHACKER, Gernot
Format:	Patent
Sprache:	eng ; fre ; ger
Schlagworte:	CHEMICAL SURFACE TREATMENT CHEMISTRY COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL COATING MATERIAL WITH METALLIC MATERIAL COATING METALLIC MATERIAL DIFFUSION TREATMENT OF METALLIC MATERIAL GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS METALLURGY METALLURGY OF IRON MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION
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Beschreibung
Zusammenfassung:	The invention relates to a method and to an apparatus for avoiding surface defects, which are caused by zinc dust, on galvanized metal strip in continuous strip galvanization, in which metal strip which is to be galvanized and is heated in a continuous annealing furnace is moved through a furnace pipe in protective furnace gas and is immersed into a zinc bath, wherein the furnace pipe is provided with injection openings via which the front side and the rear side of the metal strip can be acted upon with protective furnace gas, and wherein extraction openings for extracting protective furnace gas loaded with zinc vapor are arranged adjacent to the injection openings. The apparatus according to the invention is characterized in that a multiplicity of the injection openings are configured and arranged in the furnace pipe in such a manner that the protective furnace gas streaming out of said injection openings is directed onto that surface of the metal strip which faces the respective injection opening with an angle of impact within the range of 70° to 110°, wherein the distance between the respective injection opening and at least one extraction opening assigned thereto is selected in such a manner that, at a predetermined or predeterminable flow velocity of the protective furnace gas emerging from the respective injection opening, an entraining of protective furnace gas, which occurs during movement of the metal strip, in the direction of the zinc bath is opposed.