Method of making catheter with irregular inner and/or outer surfaces to reduce travelling friction
First Claim
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1. A continuous method of making a finished reinforced catheter having an irregular inner diameter pattern from a thermoplastic material having an inner diameter and an outer diameter with a single extrusion step and without application of pressure from an external source to said inner diameter comprising the steps of:
- continuously extruding a mandrelized catheter body as an interim structure having an outer diameter about equal to the outer diameter of said finished reinforced catheter;
heating said mandrelized catheter body to a temperature to cause said thermoplastic material to exhibit a predetermined degree of viscosity;
forming a pattern on the inner surface of said catheter by continuously applying a tensioned length of a reinforcing member to an outer surface of said heated interim catheter body by a guide rotating in a plane approximately normal to movement of the catheter body to define a helix angle determined by the ratio of the length through which the tube advances for each complete rotation of the guide;
the step of applying being carried out while said catheter body is sufficiently viscous to permit deformation at a surface contour of said catheter body by an amount at least equal to the volume of said reinforcing member through a wall of said catheter body to locate said reinforming member entirely therein at a location determined by said viscosity and tension on said reinforcing member while the length of reinforcing member is applied thereto; and
said location interrupting said inner diameter to cause said inner diameter to become irregular, thus to define a pattern having at least a land having an I.D. less than the I.D. of said inner diameter.
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Abstract
Method of making a catheter having an irregular outer diameter and/or an irregular inner diameter caused by embedment of a reinforcing member, thereby reducing sliding friction compared to conventional smooth-wall catheters.
198 Citations
22 Claims
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1. A continuous method of making a finished reinforced catheter having an irregular inner diameter pattern from a thermoplastic material having an inner diameter and an outer diameter with a single extrusion step and without application of pressure from an external source to said inner diameter comprising the steps of:
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continuously extruding a mandrelized catheter body as an interim structure having an outer diameter about equal to the outer diameter of said finished reinforced catheter; heating said mandrelized catheter body to a temperature to cause said thermoplastic material to exhibit a predetermined degree of viscosity; forming a pattern on the inner surface of said catheter by continuously applying a tensioned length of a reinforcing member to an outer surface of said heated interim catheter body by a guide rotating in a plane approximately normal to movement of the catheter body to define a helix angle determined by the ratio of the length through which the tube advances for each complete rotation of the guide; the step of applying being carried out while said catheter body is sufficiently viscous to permit deformation at a surface contour of said catheter body by an amount at least equal to the volume of said reinforcing member through a wall of said catheter body to locate said reinforming member entirely therein at a location determined by said viscosity and tension on said reinforcing member while the length of reinforcing member is applied thereto; and said location interrupting said inner diameter to cause said inner diameter to become irregular, thus to define a pattern having at least a land having an I.D. less than the I.D. of said inner diameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of continuously making finished reinforced catheter tubing having an internal bore of accurate dimensions and with a patterned contour surface in a single extrusion step without applying pressure from an external source through said internal bore, comprising the steps of:
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forming the patterned contoured surface by applying a reinforcing material to a mandrelized tube travelling at a relatively fixed linear rate and having an external diameter about equal to a desired external diameter of catheter tubing, said tubing defining an external wall surface and an internal wall surface, to locate said reinforcing material within said tube at a location intermediate said external and said internal wall surfaces and to deform said internal wall surface in a manner which forms the patterned contour surface, the applying step being carried out while said tube is sufficiently heated to exhibit a viscosity at said linear rate sufficient to permit said reinforcement material to travel under tension from a location external to said exterior wall surface to said predetermined location within said tube adjacent said internal wall surface, the temperature of said tube and the tension of said reinforcing material being selected to cooperate to carry out effectively said applying step for the material of said tube when traveling at said linear rate; and causing said tube with said reinforcement embedded therein to cool sufficiently to solidify, thus to embed said reinforcement therein, while retaining said deformed internal wall surface.
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22. A continuous method of making a finished reinforced catheter from a thermoplastic material having patterned inner diameter and an outer diameter with a single extrusion step and without application of pressure from an external source to said inner diameter comprising the steps of:
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continuously extruding a mandrelized catheter body as an interim structure having an outer diameter about equal to the outer diameter of said finished reinforced catheter; heating said reinforcing member to a predetermined temperature; patterning the inner diameter of said catheter by continuously applying a tensioned length of a reinforcing member to an outer surface of said interim catheter body by a guide rotating in a plane approximately normal to movement of the catheter body to define a helix angle determined by the ratio of the length through which the tube advances for each complete rotation of the guide; the step of applying being carried out while said catheter body is sufficiently viscous to permit deformation at a surface contour of said catheter body by an amount at least equal to the volume of said reinforcing member through a wall of said catheter body to locate said reinforcing member entirely therein at a location determined by said viscosity and tension on said reinforcing member while the length of reinforcing member is applied thereto; and said location interrupting said inner diameter to cause said inner diameter to become patterned, thus to define at least a land on said inner diameter having an I.D. less than the I.D. of said inner diameter.
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Specification