Method of making a water blocked optical fiber cable

• US 5,335,408 A
• Filed: 02/24/1993
• Issued: 08/09/1994
• Est. Priority Date: 11/29/1989
• Status: Expired due to Fees

• Current Assignee: Fitel USA Corporation (Furukawa Electric Company Limited)
• Original Assignee: AT&T, Inc.
• Inventors: Cobb, Gary S.
• Primary Examiner(s): Ball, Michael W.
• Assistant Examiner(s): Lorin, Francis J.
• Application Number:
  US08/021,822
• Time in Patent Office: 531 Days
• Field of Search: 156/49, 156/52, 156/53, 156/56, 156/84, 156/86, 156/85, 156/51, 385/100, 439/523, 439/730, 29/859, 29/516, 29/517, 29/447, 29/458
• US Class Current: 29/447
• CPC Class Codes: G02B 6/443 Protective covering
• CPC Class Codes: G02B 6/44384 the means comprising water blocking or hydrophobic materials G02B6/4439, G02B6/4479 take precedence
• CPC Class Codes: G02B 6/4471 Terminating devices demountable connectors G02B6/3807; Cable clamps
• CPC Class Codes: G02B 6/4476 with heat-shrinkable elements
• CPC Class Codes: G02B 6/44775 Cable seals e.g. feed-through cable seals integrated to the box seals G02B6/4444; pulling eyes G02B6/44465
• CPC Class Codes: G02B 6/4479 Manufacturing methods of optical cables
• CPC Class Codes: Y10T 29/49865 by temperature differential [e.g., shrink fit]
• CPC Class Codes: Y10T 29/49885 with coating before or during assembling
• CPC Class Codes: Y10T 428/1328 Shrinkable or shrunk [e.g., due to heat, solvent, volatile agent, restraint removal, etc.]
• CPC Class Codes: Y10T 428/2933 Coated or with bond, impregnation or core
• CPC Class Codes: Y10T 428/2936 Wound or wrapped core or coating [i.e., spiral or helical]
• CPC Class Codes: Y10T 428/2944 Free metal in coating
• CPC Class Codes: Y10T 428/2947 Synthetic resin or polymer in plural coatings, each of different type
• CPC Class Codes: Y10T 428/2958 Metal or metal compound in coating
• CPC Class Codes: Y10T 428/2964 Artificial fiber or filament

Abstract

An optical cable portion (10), resident within a cable closure (14), is caused to receive a water blocking arrangement which is effective to prevent water, which enters an internal cable portion (24) through an unintended cut (21) in an outer jacket (18) of a cable portion (20), from entering an interior of the cable closure. A plurality of water blocking materials (30 and 32) are coaxially disposed about the outer jacket and a core tube (26) of the cable portion, respectively, and cooperate with a heat shrinkable plastic tube (34) which substantially covers the water blocking materials to prevent the movement of water from the internal cable portion past the water blocking materials.

Claims

1. A method of causing a portion of an optical fiber cable to be water blocked, said method comprising the steps of:

providing an optical fiber cable comprising at least one optical fiber, a longitudinally extending core tube within which the optical fiber is disposed and a longitudinally extending outer jacket disposed about the core tube;

removing the outer jacket from a portion of the cable, the removal of the outer jacket being effective to expose a portion of the core tube;

causing a first water blocking material to be disposed about an outer surface of a portion of the outer jacket adjacent to the exposed portion of the core tube;

causing a second water blocking material to be disposed about an outer surface of a portion of the core tube adjacent to the outer jacket;

causing a heat shrinkable plastic tube to be disposed about the portion of the cable and to extend to cover at least a portion of the first water blocking material disposed about the outer jacket of the cable and at least a portion the second water blocking material disposed about the portion of the core tube; and

applying heat energy to the heat shrinkable plastic tube, said step of applying heat energy being effective to cause the heat shrinkable plastic tube to shrink to cause compressive engagement of a portion of the inner surface of the heat shrinkable plastic tube with the water blocking materials and to provide a seal between a portion of the inner surface of the heat shrinkable plastic tube and a portion of the outer surface of the outer jacket of the cable and between a portion of the inner surface of the heat shrinkable plastic tube and a portion of an outer surface of the core tube.

2. The method of claim 1, wherein the heat shrinkable plastic tube is caused to extend to cover completely and extend past the first water blocking material disposed about the outer jacket of the cable and the second water blocking material disposed about the portion of the core tube.

3. The method of claim 2, wherein the step of applying heat energy to the heat shrinkable plastic tube is effective to cause a portion of the inner surface of the heat shrinkable plastic tube to become disposed in sealing and gripping engagement with a portion of the outer surface of the core tube and a portion of the outer surface of the outer jacket.

4. The method of claim 1, wherein said heat shrinkable plastic tube is a first heat shrinkable plastic tube and wherein said method further includes the steps of causing at least one relatively short length of a second heat shrinkable plastic tube to become disposed about a portion of the core tube which is spaced axially and distally from the second water blocking material, such that the second water blocking material is disposed between the second heat shrinkable plastic tube and the outer jacket and causing the second heat shrinkable plastic tube to be shrunk into sealing and gripping engagement with the core tube by the application of heat energy.

5. The method of claim 4, wherein the first heat shrinkable plastic tube is caused to extend to cover at least a portion of the second heat shrinkable plastic tube and at least a portion of said first water blocking material.

6. The method of claim 5 wherein heat energy is applied to the first heat shrinkable plastic tube and is effective to cause the first heat shrinkable plastic tube to come into compressive engagement with at least a portion of the second heat shrinkable plastic tube, with at least a portion of the first water blocking material, and with the second water blocking material.

7. The method of claim 1, wherein the second water blocking material comprises a disc through which the core tube extends.

8. The method of claim 7, wherein said method further includes the step of causing a water blocking polyurethane material to become disposed in engagement with the disc adjacent to the outer jacket.

9. The method of claim 7, wherein the heat energy applied to the heat shrinkable plastic tube is effective to cause a portion of the inner surface of the heat shrinkable plastic tube to become disposed in compressive engagement with a portion of the outer surface of the disc and to provide a water blocking seal between a portion of the inner surface of the heat shrinkable plastic tube and a portion of the outer surface of the outer jacket and to provide a water blocking seal between a portion of the inner surface of the heat shrinkable plastic tube and the outer surface of the disc.