Invention Grant
- Patent Title: Method and device for avoiding surface defects caused by zinc dust in a continuous strip galvanising process
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Application No.: US14412929Application Date: 2013-07-05
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Publication No.: US09695496B2Publication Date: 2017-07-04
- Inventor: Norbert Schaffrath , Sabine Zeizinger , Michael Peters , Gernot Nothacker , Klaus Josef Peters
- Applicant: THYSSENKRUPP STEEL EUROPE AG
- Applicant Address: DE Duisburg
- Assignee: THYSSENKRUPP STEEL EUROPE AG
- Current Assignee: THYSSENKRUPP STEEL EUROPE AG
- Current Assignee Address: DE Duisburg
- Agency: thyssenkrupp North America, Inc.
- Priority: DE102012106106 20120706
- International Application: PCT/EP2013/064249 WO 20130705
- International Announcement: WO2014/006183 WO 20140109
- Main IPC: B05D3/02
- IPC: B05D3/02 ; C23C2/02 ; C21D9/56 ; C23C2/00 ; C23C2/06 ; C23C2/40 ; C21D1/26 ; C21D9/52 ; B05D3/00

Abstract:
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.
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