Method of manufacturing a fiber optic drop cable

Patent metadata

Field	Value
Publication number	US-9669592-B2
Application number	US-201414206327-A
Country	US
Kind code	B2
Filing date	Mar 12, 2014
Priority date	Jul 27, 2012
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

A method of manufacturing a fiber optic cable includes manufacturing a subunit and manufacturing an outer portion. Manufacturing the subunit includes extruding a subunit jacket over a first reinforcement material constraining an optical fiber. Manufacturing the outer portion of the fiber optic cable includes extruding an outer jacket over a second reinforcement material between the outer jacket and the subunit jacket. Hoop stress is applied to the second reinforcement material by the outer jacket, which constrains the second reinforcement material such that it is positioned and oriented to provide anti-buckling support to the fiber optic cable and mitigate effects on the optical fiber of jacket shrinkage due to low temperatures.

First claim

What is claimed is:

1. A method of manufacturing a fiber optic cable, comprising steps of:
manufacturing a subunit by:
extruding a subunit jacket over a first reinforcement material; wherein the subunit jacket defines a passageway interior thereto; wherein the subunit jacket is an indoor jacket comprising a flame-retardant jacketing material; wherein the first reinforcement material constrains, within the subunit jacket, an optical fiber extending through the passageway such that the optical fiber and the subunit jacket are coupled to one another by way of the first reinforcement material; and wherein the first reinforcement material is at least one of so positioned and non-rigid in bending such that the subunit has essentially no bend preference; and
manufacturing an outer portion of the fiber optic cable by:
pressure-extruding an outer jacket over a second reinforcement material to tightly constrain components of the fiber optic cable interior to the outer jacket; wherein the outer jacket is an outdoor jacket comprising medium- or high-density polyethylene; wherein the second reinforcement material is between the outer jacket and the subunit jacket, whereby removal of the outdoor jacket and the second reinforcement material converts the fiber optic cable to an indoor cable; wherein the second reinforcement material is at least one of so positioned and non-rigid in bending such that, in combination with the subunit, the fiber optic cable has essentially no bend preference; and wherein hoop stress applied to the second reinforcement material by the outer jacket constrains the second reinforcement material between the subunit and outer jackets such that the second reinforcement material is held in position and oriented to provide anti-buckling support to the fiber optic cable and thereby mitigate effects on the optical fiber of jacket shrinkage due to low temperatures experienced by the fiber optic cable.

2. The method of claim 1 , wherein pressure extruding of the outer jacket occurs at least at 100 bar, whereby, upon cooling, the outer jacket contracts and constrains the second reinforcement material.

3. The method of claim 1 , wherein the step of manufacturing the subunit further includes tensioning the optical fiber while extruding the indoor jacket about first reinforcement material and the optical fiber so that the optical fiber is without excess fiber length following cooling and shrinkage of the indoor jacket after extruding the indoor jacket.

4. The method of claim 1 , wherein the fiber optic cable has essentially no preferential bend such that magnitudes of forces, for loading the fiber optic cable on a free end thereof in a direction orthogonal to the length of the fiber optic cable and holding a fixed portion of the fiber optic cable that is 250 mm from the free end of the fiber optic cable to bend the fiber optic cable between the free end and fixed portion thereof so that the lengthwise center of the free end of the fiber optic cable is directed 30-degrees from the lengthwise center of the fixed portion of the fiber optic cable in any two different bend directions, differ by less than 25% of the magnitude of the greater of the forces for bending the fiber optic cable.

5. The method of claim 1 , wherein the subunit has essentially no preferential bend such that magnitudes of forces, for loading the subunit on a free end thereof in a direction orthogonal to the length of the subunit and holding fixed a portion of the subunit that is 100 mm from the free end of the subunit to bend the subunit between the free end and fixed portion thereof so that the lengthwise center of the free end of the subunit is directed 30-degrees from the lengthwise center of the fixed portion of the subunit in any two different bend directions, differ by less than 25% of the magnitude of the greater of the forces for bending the subunit.

6. The method of claim 1 , wherein the second reinforcement material comprises fiberglass yarn, wherein the fiberglass yarn includes a non-rigid binding material that includes at least one of cohesive polymers and a coating to clump fibers of the fiberglass yarn together in flattened strips, and wherein individual fibers of the fiberglass yarn are able to move relative to one another as the cable bends, thereby facilitating flexibility of the fiber optic cable.

7. The method of claim 1 , wherein the second reinforcement material comprises fiberglass yarn in the form of flattened strips positioned around and adjoining the indoor jacket.

8. A method of manufacturing a fiber optic cable, comprising steps of:
manufacturing a subunit by:
extruding a subunit jacket over a first reinforcement material; wherein the subunit jacket defines a passageway interior thereto; wherein the subunit jacket is an indoor jacket comprising a flame-retardant jacketing material; wherein the first reinforcement material constrains, within the subunit jacket, an optical fiber extending through the passageway such that the optical fiber and the subunit jacket are coupled to one another by way of the first reinforcement material; and wherein the first reinforcement material is at least one of so positioned and non-rigid in bending such that the subunit has essentially no bend preference; and
tensioning the optical fiber while extruding the indoor jacket about first reinforcement material and the optical fiber so that the optical fiber is without excess fiber length following cooling and shrinkage of the indoor jacket after extruding the indoor jacket; and
manufacturing an outer portion of the fiber optic cable by:
extruding an outer jacket over a second reinforcement material; wherein the outer jacket defines an outer periphery of the cable; wherein the outer jacket is an outdoor jacket comprising medium- or high-density polyethylene; wherein the second reinforcement material is between the outer jacket and the subunit jacket, whereby removal of the outdoor jacket and the second reinforcement material converts the fiber optic cable to an indoor cable; wherein the second reinforcement material is at least one of so positioned and non-rigid in bending such that, in combination with the subunit, the fiber optic cable has essentially no bend preference; and wherein hoop stress applied to the second reinforcement material by the outdoor jacket constrains the second reinforcement material between the subunit and outer jackets such that the second reinforcement material is held in position and oriented to provide anti-buckling support to the fiber optic cable and thereby mitigate effects on the optical fiber of jacket shrinkage due to low temperatures experienced by the fiber optic cable.

9. The method of claim 8 , wherein the step of extruding the an outer jacket includes pressure-extruding the outer jacket over the second reinforcement material to tightly constrain components of the fiber optic cable interior to the outer jacket.

10. The method of claim 8 , wherein the second reinforcement material comprises fiberglass yarn stranded about the indoor jacket at a lay length of at least 200 mm, and wherein the first reinforcement material comprises aramid fibers aligned with the optical fiber and not having a lay length.

11. The method of claim 8 , wherein the first reinforcement material comprises aramid fibers and the second reinforcement material comprises aramid fibers and fiberglass yarn, wherein aramid fibers of the first reinforcement material fully surround the optical fiber, separating the optical fiber from the indoor jacket, thereby forming a barrier mitigating sticking of the optical fiber to the indoor jacket during manufacturing of the subunit.

12. The method of claim 8 , wherein the optical f

Assignees

• Corning Optical Communications LLC

Inventors

• Blazer Bradley Jerome
• Dodd Andrew S
• Kundis Dieter Erwin
• Olszewski Sebastian

Classifications

• G02B6/4495

  Physics · mapped topic

• G02B6/4486

  Protective covering · CPC title

• B29D11/00701 Primary

  having an intermediate layer between core and cladding · CPC title

• G02B6/4432

  with fibre reinforcements · CPC title

• G02B6/4431

  with provision in the protective covering, e.g. weak line, for gaining access to one or more fibres, e.g. for branching or tapping (break-out terminations G02B6/4471) · CPC title