Tubing
First Claim
1. An elongated tube having an annular wall with an outer surface and an inner surface which inner surface defines a central passageway of a uniform size, said tube comprising a first section comprised of a first material, a second section comprised of a second material, the first and second materials being of different stiffness, and an intermediate section joining the first section and the second section, the intermediate section being a transition section in which the wall of the tube gradually changes from the first material of the first section to the second material of the second section to form a continuous unbroken tube of differential stiffness without abrupt joints, the materials of the first section and the second section naturally adhering to each other and being gradually combined in the transition section to form a wedge structure in which the first material extends into the second material within the transition section so that the second material surrounds the wedge structure of the first material and is between the wedge structure and both the inner surface and the outer surface of the wall.
0 Assignments
0 Petitions
Accused Products
Abstract
Differential stiffness tubing for medical products, such as catheters, and a method and apparatus for making the tubing. The tubing has a stiff section and a flexible section joined by a relatively short transition section in which the materials of the stiff and flexible sections are wedged into each other in a smooth gradual manner to produce an inseparable bond between the materials without abrupt joints. The tubing is made using a resin modulating system and a unique co-extrusion head that minimize the length of the transition section by minimizing the volumes in all flow channels of the head.
383 Citations
26 Claims
- 1. An elongated tube having an annular wall with an outer surface and an inner surface which inner surface defines a central passageway of a uniform size, said tube comprising a first section comprised of a first material, a second section comprised of a second material, the first and second materials being of different stiffness, and an intermediate section joining the first section and the second section, the intermediate section being a transition section in which the wall of the tube gradually changes from the first material of the first section to the second material of the second section to form a continuous unbroken tube of differential stiffness without abrupt joints, the materials of the first section and the second section naturally adhering to each other and being gradually combined in the transition section to form a wedge structure in which the first material extends into the second material within the transition section so that the second material surrounds the wedge structure of the first material and is between the wedge structure and both the inner surface and the outer surface of the wall.
- 25. An elongated tube having an annular wall with an outer surface and an inner surface which inner surface defines a central passageway of a uniform size, said tube comprising a first section comprised primarily of a first material that forms the inner surface of the wall, a second section comprised primarily of a second material that forms the outer surface of the wall, the first and second materials being of different stiffness, and an intermediate section joining the first section and the second section, the intermediate section being a transition section in which the wall of the tube gradually changes from the primary material of the first section to the primary material of the second section to form a continuous unbroken tube of differential stiffness without abrupt joints, the materials of the first section and the second section naturally adhering to each other and being gradually combined in the transition section to form a structure in which the first material continues to form the inner surface of the wall of the tube within the transition section and the second material continues to form the outer surface of the wall of the tube within the transition section.
Specification