04876051 is referenced by 26 patents and cites 18 patents.

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.

Title
Apparatus and method for extruding and expanding polytetrafluoroethylene tubing and the products produced thereby
Application Number
930411
Publication Number
4876051
Application Date
December 17, 1987
Publication Date
October 24, 1989
Inventor
Charles E Biggerstaff
Flagstaff
AZ, US
Rob G Riffle
Flagstaff
AZ, US
Benjamin G Williams
Flagstaff
AZ, US
Michael L Campbell
Flagstaff
AZ, US
Agent
Mortenson & Uebler
Assignee
W L Gore & Associates
DE, US
IPC
B29C 47/20
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