EP1663627A2

EP1663627A2 - Method for the production of an optical transmission element comprising a filled chamber element and optical transmission element

Info

Publication number: EP1663627A2
Application number: EP04786709A
Authority: EP
Inventors: Dieter Kundis; Horst Knoch
Original assignee: CCS Technology Inc
Current assignee: Corning Research and Development Corp
Priority date: 2003-09-12
Filing date: 2004-09-07
Publication date: 2006-06-07
Also published as: US20070058913A1; WO2005025842A2; DE10342319A1; CN1878654A; CN1878654B; WO2005025842A3

Abstract

The invention relates to the production of an optical transmission element (BA), comprising at least one optical waveguide (LW) and a chamber element (AH), surrounding the optical waveguide, enclosing an internal space. A foamed filler (FM) is intermittently applied to the optical waveguide (LW) and the optical waveguide (LW) then introduced into an extruder (EX), forming a chamber element (AH) around the optical waveguide. The filler (FM) is stabilised within the formed chamber element (AH) and gives, in the final state, several dry compressible filler elements (FE, FE1 to FE4), each enclosing the optical waveguide. A dry and easily manipulated optical transmission element is thus provided. An outflow of filler and an escape of the optical waveguide from the transmission element are prevented.

Description

description

Method for producing an optical transmission element with a filled chamber element and optical transmission element

The present invention relates to a method for producing an optical transmission element with at least one optical waveguide and with a filled chamber element surrounding the optical waveguide. The invention further relates to such an optical transmission element.

Optical transmission elements such as optical cables or optical wires, for example in the form of so-called bundle wires, generally contain one or more optical waveguides, which are surrounded by a chamber element enclosing them. A common method of fixing the optical waveguide in an optical transmission element is to fill the chamber element with a highly viscous, thixotropic or crosslinking filler. The filling compound prevents water, which penetrates into the chamber tube if the transmission element is damaged, from advancing further. Such a filling compound has the disadvantage that it can run out or drip out in the case of vertically hanging ends of the transmission element. In addition, in the event of the transmission element being separated during installation, the filling compound escaping during installation can lead to contamination and handling problems on the part of the installation personnel.

The problem of leakage of the filling compound could be countered with a cross-linking silicone filling compound based on two components. However, this has the disadvantage that the ^{'manufacturing} process with comparatively high costs and a certain production uncertainty due to the used to com- ponents is afflicted. The present invention is based on the object _; to specify a method for producing an optical transmission element with which an easily manageable optical transmission element with a filled chamber element can be produced in an effective manner.

Furthermore, it is an object of the present invention to provide a corresponding optical transmission element.

This object is achieved by a method for producing an optical transmission element according to claim 1 and by an optical transmission element according to claim 11.

According to the method of the invention, a filling compound is applied discontinuously to the optical waveguide fed to an extruder in the foamed state. The optical waveguide with the pre-foamed filling compound applied is then fed to the extruder, which forms a chamber element around the optical waveguide. The applied filler mass stabilizes within the formed comb element through the heat supply of the chamber element, whereby existing gaps in the interior in the cross-sectional plane of the transfer element are filled by the filler mass and in the final state several dry, compressible filler elements are formed, each surrounding the optical waveguide.

This results in the end product being an optical transmission element with an optical waveguide and a chamber element surrounding the optical waveguide, in which several dry and compressible filling elements are arranged in the interior of the comb element, which are formed by material pre-foamed in the interior. The filling elements in the pre-expanded state exert a defined contact pressure against the chamber element and against the optical waveguide for fixing the same in the longitudinal direction of the transmission element, changes in position of the optical waveguide being nevertheless possible. The filling elements each surround the optical waveguide, and any gaps between the optical waveguide and the chamber element in the cross-sectional plane of the transmission element are filled by the subsequently stabilizing and still slightly expanding filling compound. In addition, the optical waveguide and the chamber element are essentially positively contacted by the filling elements. There is thus a dry and easy-to-use optical transmission element. Leakage of filling compound and migration of the optical waveguide out of the transmission element is prevented.

The foamed filling compound preferably has a diameter when it enters the extruder which is approximately equal to an inner diameter of the chamber element. As a result, the cross section of the extruded chamber element is advantageously not impaired during the stabilization process of the filling compound with the method according to the invention.

This is further achieved in that the pre-expanded filling compound is still comparatively compact and resilient on the optical waveguide during the extrusion of the chamber element and only expands slightly after it has entered the extruder within the chamber element formed in order to produce a positive connection to the chamber element. The foamed filler preferably expands by approximately 10 percent of its volume after entry into the extruder. As a result, the chamber element can initially largely cure after the extrusion before the filling compound contacts the inner wall of the chamber element. For example, polyurethanes or silicones can be used as filler.

At least two nozzles are advantageously used, which apply the foamed filling compound approximately concentrically and uniformly to the optical waveguide in the radial direction of the transmission element. This largely ensures that the filler elements each match the light wave completely surround the conductor and existing gaps between the optical waveguide and the chamber element in the cross-sectional plane of the transmission element are filled by the filling compound.

In order to improve this process still further, more than two nozzles are preferably used, which are arranged in a star shape in the radial direction of the transmission element and enclose the optical waveguide between them.

Further advantageous developments and developments of the invention are specified in the subclaims.

The invention is explained in more detail below with reference to the figures shown in the drawing, which illustrate exemplary embodiments of the present invention.

Show it:

FIG. 1 shows a schematically illustrated production line for producing an optical transmission element according to the invention,

FIG. 2 shows a longitudinal section through an optical transmission element according to the invention in the final state,

Figure 3 shows a further embodiment of a device for producing an optical transmission element according to the inventive method in cross section.

FIG. 1 shows a schematically illustrated production line with which an optical transmission element, in particular in the form of a bundle core, is produced by the method according to the invention. A bundle of optical fibers LW is fed to an extruder EX. According to this exemplary embodiment, a plurality of optical waveguides LW run into one Extruder EX for forming a chamber element, here in the form of a wire sheath AH. The optical waveguides LW are in particular designed as optical fibers which are arranged in the end product as an optical waveguide bundle or fiber bundle LWB within a loose tube BA with the buffer tube AH. An alternative embodiment provides as optical waveguide LW, for example, optical cores, each with a plurality of fibers enclosed, the cores being arranged as a strand within a cable jacket with the sheath AH. In the following, the invention is further described with reference to the first embodiment.

According to the invention, an already foamed filler FM is discontinuously applied to the optical fiber bundle LWB by means of nozzles D1, D2. The optical fiber bundle LWB is then fed to the extruder EX, which forms the wire sheath AH around the optical waveguide. The prefoamed filling compound FM stabilizes itself within the wire sheath AH formed by the supply of heat to the wire sheath and, in the final state, forms a hardened, dry but still compressible filling element FE, which in each case surrounds the optical waveguides. Fillers based on foamed polyurethanes or silicones are particularly suitable. Two nozzles D1 and D2 are used, which apply the foamed filling compound FM approximately concentrically and uniformly to the optical waveguide LW in the radial direction of the transmission element.

The nozzles D1, D2 are arranged opposite one another and enclose the optical waveguides LW between them. Piezo-controlled valves are preferably used as nozzles in order to implement the regulation of the application quantities and the short cycle times during application (approximately 1 ms per filling element to be formed) at a comparatively high take-off speed. The order quantity, opening time and the repetition frequency are adjusted depending on the take-off speed in the take-off direction AZ of the loose tube BA. The distance of the filling elements FE and their size can be set individually. The length and size of the FE filler elements are regulated via opening time, valve lift and material pressure. The LW fiber optic cables are precisely guided to prevent axial vibrations.

During the stabilization process of the filling compound FM, the cross section of the wire sheath AH, which is initially still hot, is not changed by the filling compound FM. For this purpose, the foamed filler FM preferably has a diameter when it enters the extruder EX that is approximately equal to an inner diameter of the wire sheath AH. This is particularly regulated via the order quantity. After entering the extruder EX, the foamed filling compound FM expands only slightly in the stabilization process in order to establish a positive connection to the wire sheath AH. The foamed filler FM preferably expands after it has entered the extruder EX by approximately 10 percent of its volume.

In the final state, the foamed, stabilized filling compound FM forms a filling element FE, which exerts a defined contact force against the wire sheath AH and against the optical waveguide LW for fixing the same in the longitudinal direction of the loose tube BA, whereby changes in the position of the optical waveguide LW are nevertheless possible. The filling compound FM also fills and penetrates any gaps between the optical fibers LW in the cross-sectional plane of the loose tube BA, and the optical fibers LW and the ferrule AH are essentially contacted in a form-fitting manner, so that a firm connection is created in each case.

FIG. 2 shows a longitudinal section through a transmission element BA according to the invention in the final state. Due to the intermittent application of the filling compound FM according to FIG. 1 to the optical waveguide LW, several dry and compressible ones are made

Filling elements FEI to FE4 are formed, which surround the optical waveguide LW and existing gaps between the light Fill in and penetrate the waveguides in the cross-sectional plane of the loose tube BA. Between the filling elements FEI to FΞ4 there are intermediate spaces ZW which are not occupied by filling elements. This creates a dry loose tube BA, in the interior of which filler elements FEI to FE4, which act as bulkheads, are arranged, which provide effective longitudinal water tightness of the loose tube. To support this property, the filling elements FEI to FE4 can additionally contain a swellable agent to seal them against water ingress.

FIG. 3 shows a further embodiment of a device for producing an optical transmission element using the method according to the invention in cross section. In this case, more than two, in particular four, nozzles D1 to D4 are used, which are arranged in a star shape in the radial direction of the loose tube and enclose the optical waveguides LW between them. The diameter of the filling elements can thus be set even more precisely.

The application of the filling compound, which forms the later filling elements, to the incoming optical fibers in front of the extruder has the advantage that the precise dosing is considerably simplified. Suitable nozzles can be placed in the immediate vicinity of the optical fibers in front of the extruder. After the extruder, this is only possible within a hollow tube and is difficult to implement technically due to the small dimensions.

The discontinuously provided and foamed filling material only makes a small weight contribution to the finished transmission element. It is such that ^"it can easily and completely be stripped off without the use of additional tools of the optical fibers. They will assist you with the installation and assembly of a cable. The filling material is such that it voids within the fiber bundle and between the fiber and the chamber wall in cross section line of the loose tube is sealed watertight, but the fibers can easily be pulled through them. The fibers are clean and without residues and can be used immediately for further assembly (splicing, storing in cassettes) without additional cleaning steps.

Claims

claims

1. Method for producing an optical transmission element (BA) with at least one optical waveguide (LW) and with a chamber element (AH) surrounding the optical waveguide, which includes an interior,

- in which a filling compound (FM) is applied discontinuously to the optical waveguide (LW) in a foamed state, - the optical waveguide (LW) is subsequently fed to an extruder (EX), which forms a chamber element (AH) around the optical waveguide,

- In which the filling compound (FM) stabilizes within the chamber element (AH) formed and in the final state forms several dry, compressible filling elements (FE, FEI to FE4), each of which surrounds the optical waveguide.

2. The method of claim 1, d a d u r c h g e k e n n z e i c h n e t that foamed polyurethanes or silicones are used as filler (FM).

3. The method according to claim 1 or 2, so that the cross-section of the chamber element (AH) is not changed by the filling compound (FM) during the stabilization process of the filling compound.

4. The method according to any one of claims 1 to 3, characterized in that the foamed filler (FM) has a diameter when entering the extruder (EX) which is approximately equal to an inner diameter of the chamber element (AH).

5. The method according to any one of claims 1 to 4, that the foamed filler (FM) expands after entering the extruder (EX) to produce a positive connection to the chamber element (AH).

6. The method according to claim 5, that the foamed filler (FM) expands by approximately 10 percent of its volume after it has entered the extruder (EX).

7. The method according to any one of claims 1 to 6, d a d u r c h g e k e n n z e i c h n e t that at least two nozzles (Dl, D2) are used, which apply the foamed filler (FM) approximately concentrically and in the radial direction of the transmission element evenly on the optical waveguide (LW).

8. The method according to claim 7, so that the nozzles (Dl, D2) are arranged opposite one another and enclose the optical waveguide (LW) between them.

9. The method according to claim 7 or 8, d a d u r c h g e k e n n z e i c h n e t that more than two nozzles (Dl to D4) are used, which are arranged in a radial shape of the transmission element and enclose the optical waveguide (LW) between them.

10. The method according to any one of claims 7 to 9, characterized in that piezo-controlled valves are used as nozzles (Dl to D4).

11. Optical transmission element (BA)

- with at least one optical waveguide (LW) and with a chamber element (AH) surrounding the optical waveguide, which encloses an interior • with several dry and compressible filling elements (FE, FEI to FE4), which are arranged in the interior and through pre-expanded material ( FM) are formed, with the filling elements exerting a defined contact pressure against the chamber element (AH) and against the optical waveguide (LW) for fixing the same in the longitudinal direction of the transmission element,

- in which the filler elements (FE, FEI to FE4) each surround the optical waveguide (LW), fill any gaps in the cross-sectional plane of the transmission element (BA), and make positive contact with the optical waveguide (LW) and the chamber element (AH).

12. Optical transmission element according to claim 11, so that the material of the filling elements (FE, FEI to FE4) is formed by pre-expanded polyurethanes or by silicones.

13. Optical transmission element according to one of claims 11 or 12, so that a plurality of separate filling elements (FE, FEI to FE4) are arranged in the longitudinal direction of the optical transmission element (BA) with intermediate spaces (ZW) not occupied by filling elements.

14. Optical transmission element according to one of claims 11 to ^" ! 3, ^" characterized in that the filling elements (FE, FEI to FE4) for sealing contain a swellable agent when water enters.

15. Optical transmission element according to one of claims 11 to 14, d a d u r c h g e k e n n z e i c h n e t that the filler elements (FE, FEI to FE4) are such that they can be easily and completely stripped from the optical fibers without the use of additional tools.