Apparatus for making a catheter
The present invention concerns a catheter for medical purposes, such as for insertion into a body opening for draining fluids, wherein the catheter comprises a flexible tube having a distal end region wherein the tube is provided with at least one draining opening, characterized in that the peripheral edge on the outside of the tube is provided with a curvature for creating a smooth transition between the exterior surface of the tube and the substantially radially oriented cut constituting the opening side and wherein said curvature is a rounded edge with a curvature radius between 0.2-0.6 mm. The invention further concerns a method of making such catheter and an apparatus for performing this method.
1. An apparatus for manipulating openings punched in a polymer tube with a punching or cutting tool, the opening, having generally radially oriented side walls, said apparatus comprising:
a forming member having a distal end adapted to engage with an opening punched in the polymer tube, the forming member is provided with a rounded shoulder transition portion at a foot of the distal end of the forming member and has a protrusion extending from said shoulder transition portion, said protrusion having a form sized and shaped to fit into the punched opening in the polymer tube, said rounded shoulder transition portion being provided with a three-dimensional edge contour shaped to define a corresponding rounded three-dimensional contour of an outer surface peripheral edge of the punched opening in the polymer tube when the protrusion fits into the punched opening in the polymer tube and the rounded shoulder transition portion contacts the polymer tube; and
heating means to heat said forming member to a temperature above the softening point of the polymer of the tube to form the corresponding three-dimensional contour of the outer surface peripheral edge of the opening in the polymer tube corresponding to the rounded shoulder transition portion of the forming member,
wherein the forming member is mounted in a forming station in a floating arrangement such that the protrusion remains fitted into the punched opening in the polymer tube when the three-dimensional contour of the outer surface peripheral edge of the opening in the polymer tube is formed.
2. An apparatus according to claim 1 , wherein said apparatus comprises a movable frame comprising one or more forming stations, each forming station being adapted for receiving a flexible polymer tube with at least one opening therein through the station.
3. An apparatus according to claim 1 , wherein the forming member is self-aligning when the protrusion is engaging the opening of the polymer tube.
4. An apparatus according to claim 2 , wherein the movable frame comprises an upper section and a lower section where between the at least one forming station is arranged.
5. An apparatus according to claim 1 , wherein the forming member is made of metal.
6. An apparatus according to claim 1 , wherein the rounded shoulder portion is provided with a curvature radius between about 0.2-0.6 mm.
7. An apparatus according to claim 1 , wherein the protrusion is elongated with a longitudinal length substantially corresponding to the axial extension of the opening on the tube.
8. The apparatus according to claim 5 , wherein the metal comprises brass.
9. The apparatus according to claim 1 , wherein the heating means is configured to heat the forming member to the temperature below the melting point of the polymer material of the tube.
10. The apparatus according to claim 4 , wherein the upper section is configured to be heated to about 170-210° C.
11. The apparatus according to claim 4 , wherein the lower section is configured to be heated to about 160-200° C.