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Method of making liquid-tight cup

  • US 3,908,523 A
  • Filed: 11/05/1973
  • Issued: 09/30/1975
  • Est. Priority Date: 11/15/1972
  • Status: Expired due to Term
First Claim
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1. A method of forming a liquid-tight heat-insulated cup comprising the steps of providing a smooth surface inner cup member having a circular bottom and a circular cross-section side wall in liquid-tight relation with said bottom and extending upwardly therefrom;

  • cutting, from a smooth planar sheet, a smooth planar blank, as a starting material, having a width in excess of the peripheral length of said circular bottom and a length substantially equal to the height of said side wall;

    then uniting the laterally opposite ends of said smooth planar blank in overlapped relation to form a circular cross-section, initially smooth surface, sleeve constituting an outer cup member;

    after such uniting, thereafter forming parallel, longitudinally extending concavo-convex flutes in said outer cup member to form a structure whose peripheral surface is corrugated longitudinally of said sleeve; and

    then telescoping said inner cup member into said outer cup member to form a composite liquid-tight cup with heat insulating air passages extending upwardly along the outer surface of the smooth side wall of said inner cup member.

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