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TUBING WITH INNER BAFFLE FINS AND METHOD OF PRODUCING IT

  • US 3,776,018 A
  • Filed: 02/29/1972
  • Issued: 12/04/1973
  • Est. Priority Date: 02/29/1972
  • Status: Expired due to Term
First Claim
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1. Method of forming tubing, which comprises providing a round metal tube blank having an axis, an annular peripheral wall about said axis, and inner metal fins on said wall extending helically thereon in one direction and being spaced from said axis;

  • partially compressing the blank from two opposite sides for interpress of opposed fins at their crossings; and

    expanding the partially compressed blank to separate the fins from their interpress.

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