Methods of making and accessing cables having access features
Cables jacket are formed by extruding discontinuities in a main cable jacket portion. The discontinuities allow the jacket to be torn to provide access to the cable core. The discontinuities can be longitudinally extending strips of material in the cable jacket, and can be introduced into the extrudate material flow used to form the main portion through ports in the extrusion head. The discontinuities allow a section of the cable jacket to be pulled away from a remainder of the jacket using a relatively low peel force.
1. A fiber optic cable, comprising:
a core comprising an optical fiber; and
a jacket surrounding the core, wherein the jacket has an interior surface that faces the core and an exterior surface, wherein the jacket is formed primarily from a polymer material, wherein the jacket comprises:
a discontinuity extending lengthwise along the cable and wholly embedded in the jacket, wherein the discontinuity comprises a portion of the jacket of a different material composition than a main portion of the jacket, the main portion of the jacket being an annular hoop surrounding the core, whereby the discontinuity provides a line of weakness that allows the jacket to be separated to provide access to the core, wherein the discontinuity is bonded to the main portion of the jacket such that the jacket comprises a cohesive composite polymer structure; and
a tactile indicator extending lengthwise along the exterior of the jacket denoting the location of the wholly-embedded discontinuity of the jacket,
wherein a peel force is required to pull the section of the jacket away from the remainder of the cable at an angle of 90-degrees to the remainder of the cable, and wherein the peel force is less than about 90 Newtons (N).
2. The fiber optic cable of claim 1 , wherein the jacket comprises a visual indicator extending lengthwise along the exterior of the jacket denoting the location of the wholly-embedded discontinuity of the jacket.
3. The fiber optic cable of claim 1 , wherein the tactile indicator comprises a tactile locator feature comprising at least one of a raised surface and a depressed surface on the exterior of the jacket to provide tactile indication of the location of the discontinuity, wherein the core further comprises a bundle of a plurality of optical fibers bundled by a binder, wherein the discontinuity is located between the core and the tactile locator feature in the radial direction.
4. The fiber optic cable of claim 3 , wherein the tactile locator feature comprises a raised surface in the form of a bump to provide tactile indication of the location of the discontinuity, wherein the plurality of bundled optical fibers are adjacent to each other in a circumferential direction when viewed in cross-section.
5. The fiber optic cable of claim 4 , wherein the bump extends along the entire length of the cable.
6. The fiber optic cable of claim 1 , wherein the discontinuity has a maximum width and height, and wherein the ratio of the maximum width to the height of the discontinuity is in the range of 1:4 to 1:100, thereby facilitating stress concentration at a root of the discontinuity.
7. The fiber optic cable of claim 6 , wherein the ratio of the height of the discontinuity to the overall thickness of the jacket is at least 1:4.
8. The fiber optic cable of claim 1 , wherein the main portion of the jacket is formed from a first material comprising at least 80% by weight of a first polymer, and wherein the discontinuity is formed from a second material comprising at least 70% by weight of a second polymer and at least 0.5% by weight of the first polymer, thereby increasing bonding between the discontinuity and the main portion of the jacket.
9. The fiber optic cable of claim 8 , wherein the first polymer is polyethylene and the second polymer is polypropylene.
10. The fiber optic cable of claim 9 , wherein the second material comprises at least 1% by weight polyethylene.
11. The fiber optic cable of claim 9 , wherein the second material comprises at least 2% by weight polyethylene.
12. The fiber optic cable of claim 1 , wherein the discontinuity is a first discontinuity and further comprising a second discontinuity wholly embedded in the jacket and spaced apart from the first discontinuity such that a section of the jacket is between the first and second discontinuities.
13. The fiber optic cable of claim 1 , wherein the peel force is in a range from about 20N to about 65N.
14. The fiber optic cable of claim 1 , wherein the discontinuity is wholly embedded in the jacket such that a section of the main portion of the jacket is located outside of the discontinuity in the radial direction.
15. The fiber optic cable of claim 1 , wherein the discontinuity is wholly embedded in the jacket such that the entire discontinuity is located between the interior surface of the jacket and the exterior surface of the jacket in the radial direction.
16. A fiber optic cable, comprising:
a core comprising an optical fiber; and
a jacket surrounding the core, wherein the jacket has an interior surface that faces the core and an exterior surface, wherein the jacket is formed primarily from a polymer material, wherein the jacket comprises:
a discontinuity extending lengthwise along the cable and wholly embedded in the jacket, wherein the discontinuity comprises a portion of the jacket of a different material composition than a main portion of the jacket, the main portion of the jacket being a hoop surrounding the core, whereby the discontinuity provides a line of weakness that allows the jacket to be separated to provide access to the core, wherein the discontinuity is bonded to the main portion of the jacket such that the jacket comprises a cohesive composite polymer structure; and
a tactile indicator extending lengthwise along the exterior of the jacket denoting the location of the wholly-embedded discontinuity of the jacket;
wherein the discontinuity is wholly embedded in the jacket such that a section of the main portion of the jacket is located outside of the discontinuity in the radial direction.