The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 24, 1989
Filed:
Dec. 17, 1987
Michael L Campbell, Flagstaff, AZ (US);
Benjamin G Williams, Flagstaff, AZ (US);
Rob G Riffle, Flagstaff, AZ (US);
Charles E Biggerstaff, Flagstaff, AZ (US);
W. L. Gore & Associates, Inc., Newark, DE (US);
Abstract
Apparatus, a method for extruding and expanding tubular products of polytetrafluoroethylene (PTFE) and the products produced thereby are provided. In the apparatus, at least one helical groove is placed in the wall of the extruder tip or die. Preferably, at least one groove is machined in the tip having a pitch angle of 45 degrees and at least one groove is machined in the die having a pitch opposite that (135 degrees) of the tip groove. In the expanded products produced according to the invention, at least one radial position within the wall of a tube substantially all of the longitudinal axes of the nodes are oriented at an angle between about 85 degrees and about 15 degrees with respect to the longitudinal axis of the tube. In a preferred embodiment, substantially all of the longitudinal axes of the nodes located adjacent the inside wall of the tube are oriented at an angle between about 85 degrees and about 15 degrees with respect to the longitudinal axis of the tube, and substantially all of the longitudinal axes of the nodes which are located adjacent the outside wall of the tube are oriented at an angle between about 15 degrees and about 165 degrees with respect to the longitudinal axis of the tube. For the preferred product, its hoop strength is increased over an otherwise identical tube extruded using smooth surfaces, nongrooved extrusion tip and die.