Claims
- 1. A finishing process for conventional continuous hot-dip, two-side coating of a ferrous base metal strip with a molten coating metal of the type wherein said ferrous base metal strip is caused to enter a bath of said molten coating metal contained in a coating pot, said ferrous base metal strip having been treated to bring it to a coating temperature sufficiently high to prevent casting of said coating metal thereon and low enough to prevent excess coating metal-base metal alloying and to render the surfaces of said strip clean and free of oxide as it passes through said molten coating metal bath, said finishing process comprising the steps of providing an enclosure in sealed relationship with said bath for said two-side coated ferrous base metal strip as it exits said bath and an exit in said enclosure for said coated strip, maintaining a non-oxidizing atmosphere within said enclosure, locating a jet finishing nozzle to either side of said coated strip within said enclosure, jet finishing said coated strip with a non-oxidizing gas and maintaining said jet finishing gas and said atmosphere within said enclosure at an oxygen level of less than about 1000 ppm, whereby to render said two-side coated strip uniform in appearance and coating thickness.
- 2. The process claimed in claim 1 wherein said molten coating metal is chosen from the class consisting of zinc, zinc alloys, aluminum, aluminum alloys, terne and lead.
- 3. The process claimed in claim 1 including the step of maintaining said jet finishing gas and said atmosphere within said enclosure at an oxygen level of less than about 200 ppm.
- 4. The process claimed in claim 1 including the step of maintaining said jet finishing gas and said atmosphere within said enclosure at an oxygen level of less than about 100 ppm.
- 5. The process claimed in claim 1 wherein said non-oxidizing jet finishing gas and said atmosphere within said enclosure comprise nitrogen.
- 6. The process claimed in claim 1 wherein said non-oxidizing jet finishing gas and said atmosphere within said enclosure comprise an inert gas.
- 7. The process claimed in claim 1 including the step of vertically staggering said jet finishing nozzle with respect to each other.
- 8. The process claimed in claim 1 wherein each of said jet finishing nozzles has a rectangular nozzle opening of uniform width throughout its length and equidistant from said coated strip throughout its length.
- 9. The process claimed in claim 1 including the step of recirculating a portion of said non-oxidizing gas from said enclosure through said jet finishing nozzles.
- 10. The process claimed in claim 1 wherein said molten coating metal is chosen from the class consisting of zinc and zinc alloys and including the step subjecting said two-side coated strip to a spangle minimizing treatment after said strip exits said enclosure.
- 11. The process claimed in claim 5 including the step of recirculating a portion of said nitrogen from said enclosure through said jet finishing nozzles.
- 12. The process claimed in claim 5 including the step of vertically staggering said jet finishing nozzles with respect to each other.
- 13. The process claimed in claim 12 wherein each of said jet finishing nozzles has a rectangular nozzle opening of uniform width throughout its length and equidistant from said coated strip throughout its length.
- 14. The process claimed in claim 13 including the step of maintaining said nitrogen at an oxygen level of less than about 100 ppm.
- 15. The process claimed in claim 14 including the step of subjecting said two-side coated strip to a spangle minimizing treatment after said strip exits said enclosure.
CROSS REFERENCE TO RELATED APPLICATION
This is a continuation-in-part of application Ser. No. 30,660, filed Apr. 16, 1979, now abandoned, in the name of the same inventors and titled FINISHING METHOD AND APPARATUS FOR CONVENTIONAL HOT DIP COATING OF A FERROUS BASE METAL STRIP WITH A MOLTEN COATING METAL.
US Referenced Citations (23)
Foreign Referenced Citations (2)
Number |
Date |
Country |
55-62154 |
May 1980 |
JPX |
588281 |
May 1947 |
GBX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
30660 |
Apr 1979 |
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