GB2203856A - Optical cable manufacture - Google Patents

Optical cable manufacture Download PDF

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Publication number
GB2203856A
GB2203856A GB08808857A GB8808857A GB2203856A GB 2203856 A GB2203856 A GB 2203856A GB 08808857 A GB08808857 A GB 08808857A GB 8808857 A GB8808857 A GB 8808857A GB 2203856 A GB2203856 A GB 2203856A
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GB
United Kingdom
Prior art keywords
advancing
elements
tape
water
optical fibre
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08808857A
Other versions
GB2203856B (en
GB8808857D0 (en
Inventor
Stephen Thomas Spedding
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Balfour Beatty PLC
Original Assignee
BICC PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BICC PLC filed Critical BICC PLC
Publication of GB8808857D0 publication Critical patent/GB8808857D0/en
Publication of GB2203856A publication Critical patent/GB2203856A/en
Application granted granted Critical
Publication of GB2203856B publication Critical patent/GB2203856B/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
    • G02B6/4401—Optical cables
    • G02B6/4429—Means specially adapted for strengthening or protecting the cables
    • G02B6/44384—Means specially adapted for strengthening or protecting the cables the means comprising water blocking or hydrophobic materials
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
    • G02B6/4401—Optical cables
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
    • G02B6/4479—Manufacturing methods of optical cables
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
    • G02B6/4479—Manufacturing methods of optical cables
    • G02B6/4483—Injection or filling devices
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
    • G02B6/4479—Manufacturing methods of optical cables
    • G02B6/4484—Manufacturing methods of optical cables with desired surplus length between fibres and protection features

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Light Guides In General And Applications Therefor (AREA)

Abstract

In the manufacture of an optical cable having loosely housed in a bore of the cable a resiliently set undulating optical fibre element, the resiliently set undulating optical fibre element 1 travels in the direction of its length with its major transverse axes horizontal and a tape 4 with its major surfaces horizontal travels adjacent to the element. Water- impermeable medium of a grease-like nature is introduced simultaneously to opposite sides of the advancing undulating optical fibre element through ports 11 of a die/nozzle assembly 10 and is caused to flow transversely into the spaces between the smoothly curved undulations of the element by transversely folding the advancing tape around the element and water-impermeable medium until the neighbouring longitudinal edges of the tape overlap or abut to form a closed tube 2. The rate of feed of water-impermeable medium having regard to the speed of the assembly and the cross-sectional area of the bore of the closed tube 2 are such that the tube is filled with greasy water-impermeable medium. <IMAGE>

Description

OPTICAL CABLE MANUFACTURE This invention relates to optical cables of the kind comprising an elongate body having a bore of substantially circular cross-section in which is housed at least one optical fibre element which has a transverse cross-sectional shape of elongate form and which follows a path of smoothly curved undulations whose axes of curvature lie substantially parallel to one another and to the major transverse axes of the element and substantially normal to the longitudinal axis of the element. An optical cable of this kind will hereinafter, for convenience, be referred to as "of the kind described".
The invention is especially, but not exclusively, concerned with an optical cable of the kind described which is described and claimed in the specification of our British Patent No: 2156094B and which comprises an elongate body having a bore of substantially circular crossrsection in which is loosely housed at least one optical fibre element comprising a flexible tube having a bore in which at least one optical fibre is loosely housed, which flexible tube has a transverse cross-section of elongate form and is resiliently set in such a form that it follows a path of smoothly curved undulations whose axes of curvature lie substantially parallel to one another and to the major transverse axes of the flexible tube and substantially normal to the longitudinal axis of the tube.The arrangement is such that, when the resiliently set tube is subjected to a longitudinally applied tensile force, the tube will tend to straighten in a lengthwise direction against the action of its resilient set thereby to reduce the tensile force applied to the or each optical fibre and, when the tensile force is removed, the tube will return under the action of its resilient set towards its original form.
In optical cables comprising an elongate body of tubular form having a bore in which at least one optical fibre or optical fibre element is loosely housed, it is common practice to fill those parts of the bore not occupied by the optical fibre or fibres or optical fibre element or elements with a water-impermeable filling medium of a grease-like or semi-liquid nature which will permit relative movement between the or each optical fibre or optical fibre element and the elongate body and, where there is more than one optical fibre or optical fibre element present, between the optical fibres and/or optical fibre elements. Many methods of introducing such water-impermeable filling medium into the bore of the elongate body of an optical cable have been proposed and used.
We have found that in the case of an optical cable of the kind described - in which the bore of circular cross-section will normally have a diameter lying in the range 8 to 20mm - it is difficult to fill those parts of the bore not occupied by the resiliently set undulating optical fibre element or elements throughout the length of the cable without damaging an optical fibre of an optical fibre element, or distorting or reducing the undulations of or otherwise effecting damage to an optical fibre element, to an undesirable extent and without restricting to an undesirable extent the ability of the or each resiliently set undulating element to straighten in a lengthwise direction against the action of its resilient set when a tensile force is applied to the optical cable.
It is an object of the present invention to provide an improved method of introducing water-impermeable medium of'a grease-like or semi-liquid nature into the bore of the elongate body of an optical cable of the kind described substantially to fill the bore throughout the length of the cable.
According to the invention, the improved method comprises causing at least one optical fibre element which has a transverse cross-sectional shape of elongate form and which is so resiliently set that the element follows a path of smoothly curved undulations whose axes of curvature lie substantially parallel to one another and to the major transverse axes of the element and substantially normal to the longitudinal axis of the element to travel in the direction of its length with the major transverse axes of the element lying substantially horizontal; causing at least one tape to travel in the direction of its length and with its major surfaces substantially horizontal immediately adjacent the undulating optical fibre element or elements; introducing water-impermeable medium in a grease-like or semi-liquid state simultaneously to opposite sides of the advancing undulating optical fibre element or elements and causing the water-impermeable medium to flow transversely of the advancing undulating optical fibre element or elements into the spaces between the smoothly curved undulations of the advancing element or elements by transversely folding the advancing tape around the advancing undulating optical fibre element or elements and water-impermeable medium until the neighbouring longitudinal edges of the tape overlap or abut to form a closed tube, the rate of feed of water-impermeable medium having regard to the speed of the assembly and the cross-sectional area of the bore of the closed tube to be formed being such that those parts of the closed tube not occupied by the undulating optical fibre element or elements are substantially filled with water-impermeable medium in a grease-like or semi-liquid state throughout the length of the tube.
Preferably, water-impermeable medium in a grease-like or semi-liquid state is introduced simultaneously to opposite sides of the advancing resiliently set undulating optical fibre element or elements by causing the advancing element or elements and the advancing tape to pass through a die and nozzle at which water-impermeable medium is so injected transversely of and towards the advancing element or elements and the tape is so folded transversely around the advancing element or elements and the injected water-impermeable medium that substantially all air is removed from within the tube before the neighbouring longitudinal edges of the advancing tape finally overlap or abut.
Alternatively, the tape may be caused to travel immediately under the advancing resiliently set undulating optical fibre element or elements, continuous or discontinuous streams of water-impermeable medium in a grease-like or semi-liquid state may be fed on to the upper surface of the advancing tape on opposite sides of the advancing element or elements, and the tape may then be transversely folded around the advancing element or elements and water-impermeable medium in such a way that the water-impermeable medium flows transversely of the advancing element or elements into the spaces between the smoothly curved undulations thereof and substantially all air is removed from the tube before the neighbouring longitudinal edges of the advancing tape finally overlap or abut.
Preferably, downstream of the station at which the advancing tape is folded transversely around the advancing resiliently set undulating optical fibre element and water-impermeable medium, an overall covering of plastics material is extruded around the advancing transversely folded tape. In this case, preferably the tape is of laminated form and comprises a metal tape to the outwardly facing surface of which is bonded a coating of plastics material.
Upstream of the extrusion machine by which the coating of plastics material is extruded around the closed tube, the overlapping or abutting longitudinal edges of the advancing transversely folded tape may be heated or otherwise treated to effect a longitudinally continuous seal.
Where two or more resiliently set undulating optical fibre elements are advancing in the directions of their lengths a preferably each of the elements except one element travels above and rests in the adjacent underlying element. Where n resiliently set undulating elements are advancing in the directions of their lengths and n is an even number greater than 3, two stacks of undulating elements, each comprising n T elements nested together, may be arranged to travel side by side.
The water-impermeable filling medium may be any suitable filling medium of a grease-like or semi-liquid nature used or proposed for use in optical cables. One suitable filling medium is described and claimed in our co-pending U.K. Patent Application No: 8529090.
The invention further includes an optical cable manufactured by the improved method as hereinbefore described.
In this optical cable, the or each optical fibre element may take any known form. Three forms of optical fibre element that are preferred are illustrated in Figure 1 of the drawings of our British Patent No: 2141558B and in Figures 2 and 3 of the drawings of our British Patent No: 2156094B.
The improved method of the present invention has the important advantage that all operating steps of the method are of linear form, i.e. involve no stranding or reverse-lay stranding operations, thereby making the method efficient in labour, time and space, and offering scope for tandemization.
The invention will be further illustrated by a description, by way of example, of a preferred optical cable of the kind described and of the preferred method of introducing water-impermeable medium of a grease-like nature into the bore of the elongate body of the preferred optical cable during its manufacture with reference to the accompanying drawing, in which: Figure 1 is a sectional side view of the preferred optical cable, and Figure 2 is a diagrammatic plan view of the apparatus employed in the preferred method of manufacture of the preferred optical cable.
Referring to Figure 1, the preferred optical cable comprises an elongate body 2 of composite form having a bore 3 of circular cross-section in which is housed an optical fibre ribbon 1 as claimed in our British Patent No: 2141558B. The optical fibre ribbon 1 is so resiliently set that the ribbon follows a path of smoothly curved undulations whose axes of curvature lie substantially parallel to one another and to the major transverse axes of the ribbon and normal to the longitudinal axis of the ribbon. The composite elongate body 2 comprises a longitudinally extending, transversely folded laminated tape 4 consisting of a inner metal tape 5 to the outwardly facing surface of which is bonded a coating 6 of plastics material. An extruded sheath 7 of plastics material surrounds the transversely folded laminated tape 4.Throughout its length, those parts of the bore 3 of the composite elongate body 2 not occupied by the undulating optical fibre ribbon 1 are filled with a water-impermeable medium 8 of a grease-like nature which will permit relative movement between the optical fibre ribbon and the composite elongate body when the optical cable is flexed.
When the optical fibre ribbon 1 is subjected to a longitudinally applied tensile force, the ribbon will tend to straighten in a lengthwise direction against the action of its resilient set, relative to the composite elongate body 2 thereby to reduce the tensile force applied to each optical fibre of the ribbon and, when the tensile force is removed, the ribbon will return under the action of its resilient set towards its original form.
As will be seen on referring to Figure 2, the preferred optical cable shown in Figure 1 is manufactured by causing the resiliently set optical fibre ribbon 1 to travel in the direction of its length with the major transverse axes of its smoothly curved undulations lying horizontal and the composite tape 4 is caused to travel in the direction of its length immediately under the advancing optical fibre ribbon 1 with the major surfaces of the composite tape horizontal and with the metal tape 5 uppermost. The advancing optical fibre ribbon 1 and the underlying laminated tape 4 are fed into the upstream end of a die and nozzle assembly 10 at which water-impermeable medium 8 of a grease-like nature is injected through diametrically opposed inlet ports 11 transversely of and above the advancing laminated tape 4 towards the advancing optical fibre ribbon 1.As the undulating optical fibre ribbon 1 and laminated tape 4 advance towards the outlet 12 of the die and nozzle assembly 10, the advancing laminated tape is transversely folded around the advancing undulating optical fibre ribbon 1 so that the injected water-impermeable medium 8 is caused to flow transversely of the optical fibre ribbon into the spaces between the smoothly curved undulations, substantially all air being removed from within the folded laminated tape before the neighbouring longitudinal edges of the advancing tape finally overlap at or near the outlet of the die and nozzle assembly. Downstream of the outlet 12 of the die and nozzle assembly 10, the overlapping longitudinal edges of the transversely folded laminated tape 4 are heated at station 14 to effect a longitudinally continuous seal. After sealing the longitudinal edges of the transversely folded laminated tape 4, the transversely folded tape with the undulating optical fibre ribbon 1 and water-impermeable medium 8 therein passes into an extrusion machine 15 at which a sheath 7 of plastics material is extruded around, and bonds to the plastics coating 6 of, the transversely folded laminated tape.

Claims (11)

Claims:
1. A method of introducing water-impermeable medium of a grease-like or semi-liquid nature into the bore of the elongate body of an optical cable of the kind described, which method comprises causing at least one optical fibre element which has a transverse cross-sectional shape of elongate form and which is so resiliently set that the element follows a path of smoothly curved undulations whose axes of curvature lie substantially parallel to one another and to the major transverse axes of the element and substantially normal to the longitudinal axis of the element to travel in the direction of its length with the major transverse axes of the element lying substantially horizontal; causing at least one tape to travel in the direction of its length and with its major surfaces substantially horizontal immediately adjacent the undulating optical fibre element or elements; introducing water-impermeable medium in a grease-like or semi-liquid state simulultaneously to opposite sides of the advancing undulating optical fibre element or elements; and causing the water-impermeable medium to flow transversely of the advancing undulating optical fibre element or elements into the spaces between the smoothly curved undulations of the advancing element or elements by transversely folding the advancing tape around the advancing undulating optical fibre element or elements and water-impermeable medium until the neighbouring longitudinal edges of the tape overlap or abut to form a closed tube, the rate of feed of water-impermeable medium having regard to the speed of the assembly and the cross-sectional area of the bore of the closed tube to be formed being such that those parts of the closed tube not occupied by the undulating optical fibre element or elements are substantially filled with water-impermeable medium in a grease-like or semi-liquid state throughout the length of the tube.
2. A method as claimed in Claim 1, wherein water-imperameable medium in a grease-like or semi-liquid state is introduced simultaneously to opposite sides of the advancing resilient set undulating optical fibre element or elements by causing the advancing element or elements and the advancing tape to pass through a die and nozzle at which water-impermeable medium is so injected transversely of and towards the advancing element or elements and the tape is so folded transversely around the advancing element or elements and the injected water-impermeable medium that substantially all air is removed from within the tube before the neighbouring longitudinal edges of the advancing tape finally overlap or abut.
3. A method as claimed in Claim 1, wherein the tape is caused to travel immediately under the advancing resilient set undulating optical fibre element or elements, continuous or discontinuous streams of water-impermeable medium in a grease-like or semi-liquid state are fed on to the upper surface of the advancing tape on opposite sides of the advancing element or elements, and the tape is then transversely folded around the advancing element or elements and water-impermeable medium in such a way that the water-impermeable medium flows transversely of the advancing element or elements into the spaces between the smoothly curved undulations thereof and substantially all air is removed from the tube before the neighbouring longitudinal edges of the advancing tape finally overlap or abut.
4. A method as claimed in any one of the preceding Claims, wherein downstream of the station at which the advancing tape is folded transversely around the advancing undulating optical fibre element or elements and water-impermeable medium, an overall covering of plastics material is extruded around the advancing transversely folded tape.
5. A method as claimed in Claim 4, wherein the tape is of laminated form and comprises a metal tape to the outwardly facing surface of which is bonded a coating of plastics material.
6. A method as claimed in Claim 4 or 5, wherein upstream of the extrusion machine by which the coating of plastics material is extruded around the closed tube, the overlapping or abutting longitudinal edges of the advancing transversely folded tape are heated or otherwise treated to effect a longitudinally continuous seal.
7. A method as claimed in any one of the preceding Claims in which two or more undulating resiliently set optical fibre elements are advancing in directions of their lengths, wherein each of the elements except one of the element travels above and rests in the adjacent underlying element.
8. A method as claimed in any one of Claims 1 to 6 in which n resiliently set undulating optical fibre elements are advancing in the directions of their lengths and n is an even number greater than 3, wherein two stacks of undulating elements, each comprising n2 nested together, are arranged to travel side by side.
9. A method as claimed in any one of the preceding Claims, wherein the water-impermeable filling medium is the medium described and claimed in our co-pending U.K.
Patent Application No: 8529090.
10. A method of introducing water-impermeable medium of a grease-like or semi-liquid nature into the bore of the elongate body of an optical cable of the kind described substantially as hereinbefore described with reference to the accompanying drawing.
11. An optical cable manufactured by the method as claimed in any one of the preceding Claims.
GB8808857A 1987-04-15 1988-04-14 Optical cable manufacture Expired - Lifetime GB2203856B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB878709076A GB8709076D0 (en) 1987-04-15 1987-04-15 Optical cable manufacture

Publications (3)

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GB8808857D0 GB8808857D0 (en) 1988-05-18
GB2203856A true GB2203856A (en) 1988-10-26
GB2203856B GB2203856B (en) 1990-08-08

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GB878709076A Pending GB8709076D0 (en) 1987-04-15 1987-04-15 Optical cable manufacture
GB8808857A Expired - Lifetime GB2203856B (en) 1987-04-15 1988-04-14 Optical cable manufacture

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GB878709076A Pending GB8709076D0 (en) 1987-04-15 1987-04-15 Optical cable manufacture

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2205972B (en) * 1987-06-17 1991-04-03 Bicc Plc Filled optical fibre cable manufacture
EP0591867A1 (en) * 1992-10-07 1994-04-13 Siemens Aktiengesellschaft Method for tubing lightwaveguides and apparatus for performing this method
EP1416305A2 (en) * 2002-10-17 2004-05-06 Alcatel Fiber optic tube and method of forming a fiber optic tube from a tape

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2046471A (en) * 1979-03-22 1980-11-12 Telephone Cables Ltd Tube containing optic fibre(s) and thixotropic fluid
GB2088583A (en) * 1980-10-18 1982-06-09 Bicc Ltd Manufacture of a flexible electric/optical fibre cable
GB2091903A (en) * 1981-01-27 1982-08-04 Bicc Ltd Optical fibre cable

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2046471A (en) * 1979-03-22 1980-11-12 Telephone Cables Ltd Tube containing optic fibre(s) and thixotropic fluid
GB2088583A (en) * 1980-10-18 1982-06-09 Bicc Ltd Manufacture of a flexible electric/optical fibre cable
GB2091903A (en) * 1981-01-27 1982-08-04 Bicc Ltd Optical fibre cable

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2205972B (en) * 1987-06-17 1991-04-03 Bicc Plc Filled optical fibre cable manufacture
EP0591867A1 (en) * 1992-10-07 1994-04-13 Siemens Aktiengesellschaft Method for tubing lightwaveguides and apparatus for performing this method
EP1416305A2 (en) * 2002-10-17 2004-05-06 Alcatel Fiber optic tube and method of forming a fiber optic tube from a tape
EP1416305A3 (en) * 2002-10-17 2004-12-15 Alcatel Fiber optic tube and method of forming a fiber optic tube from a tape

Also Published As

Publication number Publication date
GB2203856B (en) 1990-08-08
GB8808857D0 (en) 1988-05-18
GB8709076D0 (en) 1987-05-20

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