Extrusion process for manufacturing PTFE products
AssigneeMeadox Medicals, Inc.
InventorsRichard J. Zdrahala, Nicholas Popadiuk, Gerald Kalin, David J. Lentz
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Abstract
An improved extrusion method is employed in a process which is used to form tubing for medical applications. The method includes providing an extrusion apparatus having a die which includes a die cavity and a mandrel within the die cavity. The die is rotated in a first rotational direction while the mandrel is rotated in a second rotational direction opposite the first direction. While the die and the mandrel are rotating, a PTFE paste is passed through the annular passage defined between the die and the mandrel. The die cavity is cooled to maintain the PTFE paste passing therethrough at a substantially non-elevated temperature.
Claims24
A method of forming a tubing material, comprising the steps of:
- providing an extrusion apparatus having an elongate die defining a die cavity and an elongate mandrel substantially concentrically located within said die cavity;
- rotating a portion of said die in a first rotation direction;
- rotating said mandrel in a second rotation direction opposite said first direction;
- passing a PTFE paste through an elongate passage defined between said rotating die and said rotating mandrel;
- cooling said die cavity to maintain said PTFE paste passing through said passage at a substantially non-elevated temperature;
- and
- extruding said PTFE paste through an extrusion die located at one end of said elongate passage whereby helical fibrous formation of said tubing material is enhanced.
A method of forming an elongate extruded tube comprising the steps of:
- forming a PTFE preform product;
- providing an extrusion apparatus including an elongate die having an internal die cavity and an elongate mandrel within said die cavity to thereby define a generally tubular die chamber therebetween;
- placing said preform product in said extrusion apparatus;
- rotating at least a portion of said die in a first direction;
- rotating at least a portion of said mandrel in a second direction opposite said first direction;
- extruding said preform product through said die chamber between said oppositely rotating die and mandrel portions to form said tube;
- and
- cooling said preform product during said extruding step whereby said formed extruded tube exhibits substantial fibrous formation in a direction non-longitudinally aligned with said tube.
A method of forming a PTFE tube comprising the steps of:
- providing an extrusion apparatus having an elongate die defining a die cavity and an elongate mandrel substantially concentrically located within said die cavity,
- rotating one of said die or said mandrel;
- passing a PTFE paste through an elongate annular passage defined between said die and said mandrel;
- controlling the temperature of said die cavity to maintain said PTFE paste passing through said annular cavity at a substantially non-elevated temperature;
- and
- extruding said PTFE paste through an extrusion die located at one end of said elongate passage whereby fibrous state formation of said formed tube is enhanced in a direction which is non-aligned with said elongate annular passage.
A die apparatus for extruding PTFE tubes comprising:
- a die body having a passage for receipt of a PTFE preform;
- a die element having an elongate central bore therethrough in communication with said passage of said die body;
- a tubular extrusion die supported at one end of said central bore of said die element and forming therewith an elongate die cavity for extrusion therethrough of said preform;
- an elongate mandrel positioned within said die cavity, said mandrel being rotatably supported within said die cavity for rotation in a first rotational direction;
- means for rotating said mandrel in said first rotational direction;
- and
- temperature control means coupled to said die body for maintaining said die cavity adjacent said rotating mandrel at a substantially non-elevated temperature.
Dependencies are inferred from the claim text.