Apparatus and method for extrusion of thin-walled tubes

• US 7,425,291 B2
• Filed: 09/22/2004
• Issued: 09/16/2008
• Est. Priority Date: 10/30/2001
• Status: Expired due to Fees

• Current Assignee: Lifeshield Sciences LLC (Acacia Research Corporation)
• Original Assignee: Scimed Life Systems Incorporated (Boston Scientific Corporation)
• Inventors: Wolek, Howard, Hill, Jason P., Girton, Timothy S., Sogard, David J., Brodeur, Christopher B., Venditti, James, Wong, Alice
• Primary Examiner(s): Miggins; Michael C
• Application Number:
  US10/946,875
• Publication Number:
  US 20050042402A1
• Time in Patent Office: 1,455 Days
• Field of Search: 428/35.7, 428/36.9, 428/36.91, 428/36.92, 428/421, 428/422, 264/40.3, 264/40.7, 264/149, 264/150, 264/171.26, 264/167
• US Class Current: 264/150
• CPC Class Codes: B29C 45/531 Drive means therefor
• CPC Class Codes: B29C 48/0012 combined with shaping by internal pressure generated in the material, e.g. foaming
• CPC Class Codes: B29C 48/022 characterised by the choice of material
• CPC Class Codes: B29C 48/09 Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
• CPC Class Codes: B29C 48/12 Articles with an irregular circumference when viewed in cross-section, e.g. window profiles
• CPC Class Codes: B29C 48/475 using pistons, accumulators or press rams
• CPC Class Codes: B29C 48/48 Two or more rams or pistons
• CPC Class Codes: B29K 2027/18 PTFE, i.e. polytetrafluorethene , e.g. ePTFE, i.e. expanded polytetrafluorethene
• CPC Class Codes: B29K 2105/04 cellular or porous
• CPC Class Codes: B29L 2023/007 Medical tubes other than catheters catheters B29L2031/7542
• CPC Class Codes: Y10T 428/1352 Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/139 Open-ended, self-supporting conduit, cylinder, or tube-type article

Abstract

The present invention provides an apparatus and method for manufacturing polymeric thin-walled tubular members, which are well-suited for use as vascular grafts. The apparatus of the present invention enables extrusion of a tubular member having an extremely thin wall thickness so as to facilitate passage through tortuous vascular passageways. The apparatus achieves uniform wall thickness in a tubular member by establishing and maintaining axial alignment of a ram having a concentrically disposed guide rod therein with a die supported in concentric relation to the guide rod.

Claims

1. A process for forming a single tube, said process comprising the steps of:

extruding a fluoropolymer extrudate in the absence of an inner mandrel to form a non self supporting tubular member having a single lumen which is hollow upon extrusion; and

injecting a gaseous stable medium at a pressure of 80-100 p.s.i.g. into said lumen of said tubular member during extruding, said gaseous stable medium solely providing structural support for said tubular member upon extrusion, wherein said fluoropolymer extrudate consists of PTFE and a lubricant.

2. A process as in claim 1, wherein said gaseous stable medium is air.

3. A process as in claim 1, wherein said fluoropolymer extrudate has a cylindrical shape.

4. A process as in claim 1, wherein said fluoropolymer extrudate has a wall thickness of about 250 μ

m or less.

5. A process as in claim 1, wherein said fluoropolymer extrudate has a substantially constant wall thickness.