WO1995015509A1

WO1995015509A1 - Connecting device and branching device for optical fibre cables

Info

Publication number: WO1995015509A1
Application number: PCT/DE1994/001429
Authority: WO
Inventors: Thomas Kuchenbecker; Hans-Dieter Weigel
Original assignee: Siemens Aktiengesellschaft
Priority date: 1993-12-02
Filing date: 1994-11-25
Publication date: 1995-06-08

Abstract

A contracted heat shrinkable sleeve (22, 122) contains a curable sealing compound (47, 160). The ends of strain relief means (10; 32, 33) of individual optical fibre cables (1) with stripped ends are embedded in the sealing compound (47, 160).

Description

description

Connection device and branching device for optical fiber cables

The invention is in the field of fiber optic cables and relates to a connecting device for fiber optic cables and a method for connecting fiber optic cables as well as a branching device and a method for producing a branching of a multi-core fiber optic cable.

DT-Bl-25 34 756 describes an aligned connection of two individual light waveguides, the ends of which are inserted into a central bore of a thermoplastic which is hard at room temperature. The thermoplastic surrounded by a shrink tube becomes viscous when the shrink temperature is reached and is pressed radially onto the optical waveguide by the shrinking forces to form a rigid connection after cooling.

A strain relief for a cable sheath is known from DE-Cl-41 04 530, a cylindrical holding part being glued to the cable sheath and surrounded by a shrink tube. Separate strain relief elements are mechanically clamped. From EP-Al-0 475 494 it is known to define strain relief means (KEVLAR fibers) in relation to a cable sheath with shrinkable elements.

DE-Al-42 14 377 discloses a shrinkable branch sleeve for bridging differences in diameter, which comprises a support body, a receptacle for a splice of a branching optical waveguide, front end bodies and a shrinkable covering. US Pat. No. 4,404,010 describes a connection of individual optical waveguides, in which a replacement sheath piece is pushed over a splice point, surrounded by a shrink tube and subsequently melted. The collapsed heat shrink tubing serves as a casting mold for the sheathing and is then removed again.

With a branching device known from the "FIBER OPTIC PRODUCTS FOR PREMISES COMMUNICATIONS" brochure from SIECOR CORP., 1990, in particular sections 1-26, 4-17 and 5-14, the individual cores of a multi-core optical waveguide cable can be divided into two (p . 5-14) or more (p. 4-17) Split individual cables or combine individual cables to form an overall cable. For this purpose, the multi-core optical waveguide cable is stripped at the ends, so that the individual wires and all wires are exposed to common and / or individual wire strain relief means (eg ARAMID fibers). If necessary, the strain relief means can be shortened and / or folded over. The cores are then threaded into individual sheaths (fan-out tubing) which have their own strain relief means. The branching area is surrounded by a shrink tube into which the multi-core optical fiber cable enters and from which the individual sheaths emerge.

A branching body and crimping sleeves are provided in order to ensure reliable transmission of train loads over the branching area. The crimp sleeves are pushed onto the branching body with the respective ends of the strain relief means in between and crimped there with a special tool. The fixing of the strain relief means thus requires not only several fastening parts to be manufactured and handled separately and the special tool, but also a considerable amount of assembly work by personnel trained in crimp connections. There is also the risk of an inhomogeneous distribution of the tensile stress on the strain relief means, because an absolute during crimping uniform definition of the strain relief means cannot be guaranteed.

The object of the invention is therefore to create a connecting device for optical waveguide cables, in particular for connecting optical waveguide cables of different geometry and mechanical properties, or a branching device which ensures reliable mechanical coupling and homogeneous loading of the cable-specific strain relief means or the strain relief means of a multi-core optical waveguide cable with the strain relief means of individual sheaths.

With regard to the connecting device, this object is achieved according to the invention by a contracted shrink tube into which a first and a second optical waveguide cable enter, the ends of the optical waveguide cables each being stripped with release of the ends of cable-specific strain relief means, in the shrink tube a curing or curable

Potting compound is included and the ends of the cable-specific strain relief means are embedded in the potting compound.

With regard to the branching device, this task is accomplished with a contracted shrink tube into which an optical waveguide cable enters, which is released at the end to release the ends of its strain relief means from a cable sheath common to the wires, and in which the wires in at least two with individual ones Branch strain relief means provided individual sheaths that emerge from the shrink tube, solved according to the invention in that a hardening or hardenable sealing compound is contained in the shrink tube and that the ends of the strain relief means of the optical fiber cable and the ends of the strain relief means of the single sheaths in the potting compound are embedded. The invention is thus based on the overarching principle of embedding the exposed ends of the strain relief means of the optical fiber cables coming in and going out in a hardening or hardenable casting compound which is contained in a contraction shrink tube.

An essential advantage of the invention is that the shrinking process (contraction or collapse of the shrinking tube) results in a considerably reduced internal shrinking tube volume, which can be filled with a comparatively small amount of sealing compound in such a way that the ends of the strain relief means are almost completely removed from it Potting agents are surrounded. As a potting compound z. B. a thermosetting compound or a multi-component system (resin / hardener system) is suitable. Embedding the

The ends of the strain relief means ensure a homogeneous load on the strain relief means, because all strain relief means (eg ARAMID FIBERS) are evenly involved in the transmission of tensile forces. Additional individual parts for mechanically fixing the strain relief means can therefore be dispensed with. The shrink tube also serves as protection of the connection area against external influences and as a kind of casting mold. Another advantage of the invention is that the potting compound can be introduced into the shrink tube relatively easily and also on site (field assembly). The shrink tube advantageously forms a safe transition between optical fiber cables of different thicknesses and / or mechanical properties.

In particular, the connection device according to the invention enables a connection of a thin, flexible optical fiber cable (for example for connection to data transmission and processing devices) with a robust and inflexible optical fiber cable that is particularly resistant to mechanical stress. At least one optical fiber cable can contain several individual sheaths for receiving optical fibers in its jacket.

A further development of the invention which is particularly advantageous for the targeted initialization of the curing process consists in that the shrink tube is transparent and that the sealing compound is a light-curing or curable adhesive. The transparent shrink tubing can advantageously also be used to control the distribution of the casting compound and the strain relief device and to precisely control the metering of casting compound.

Advantageous pre-fixation of the device during handling can be achieved according to a preferred development of the invention in that the shrink tube is coated on the inside with adhesive.

A mechanically and geometrically particularly favorable embodiment of the invention provides that at least one optical waveguide cable contains several protective sleeves for optical waveguides in its cable sheath and that the protective sleeves end offset in the shrink tube in the axial direction.

For additional protection of the connection area it is provided according to an advantageous embodiment of the invention that the (inner) shrink tube is surrounded by a further (outer) contracted shrink tube.

The total cross section of the individual sheaths entering one end of the shrink tube can be larger than the cross section of the common cable sheath or cable sheaths entering the other end. The outer shrink tube therefore has a particularly strong shrinkage at this end and thus an increased material hardening. Around the common cable sheath and the To protect the veins during bending processes from mechanical damage due to the comparatively hard edge of the outer shrink tube, the inner shrink tube advantageously protrudes at least with one end under the outer shrink tube.

In order to protect the connection or branching area from external mechanical damage and from forces occurring when the outer shrink tube shrinks, a support sleeve, preferably made of aluminum, is arranged between the inner and the outer shrink tube.

In order to ensure a symmetrical concentric position of the outer shrink tube and the support sleeve, a further advantageous embodiment of the invention provides that spacing means are provided between the support sleeve and the inner shrink tube.

The spacing means are preferably formed by a cable sheath piece. Material residues arising during stripping can advantageously be used. A cable jacket piece is also characterized by its compressibility.

The method according to the invention for connecting optical waveguide cables provides that the optical waveguide cables are stripped at the ends to release the ends of their cable-specific strain relief means, that the ends of the optical waveguide cables are inserted into a contractible shrink tube and that after the shrink tube has contracted, a hardening process takes place or curable potting compound is introduced into the shrink tube so that the ends of the cable-specific strain relief means are embedded in the potting compound.

A method known from the SIECOR CORP. Brochure mentioned at the beginning for producing a branching of a multi-core Optical waveguide cable in which the end of the optical waveguide cable is released from its cable sheath to release the ends of its strain relief means, in which the wires of the optical waveguide cable are threaded into at least two individual sheaths provided with individual strain relief means and in which the branching area is surrounded by a shrink tube. is designed according to the invention in such a way that after the shrink tube has contracted, a hardening or hardenable casting agent is introduced into the shrink tube and that the ends of the

Strain relief means of the optical waveguide cable and the ends of the strain relief means of the individual sheaths are embedded in the sealing compound.

The invention is explained in more detail below by way of example with reference to a drawing; show it:

1A to 1F process steps for producing a branching device according to the invention, FIG. 2 the branching device in longitudinal section, FIG. 3 optical waveguide cables with connecting devices, FIGS. 4A, 4B, 4C a connecting device and FIG. 5 further connecting devices.

FIG. 1A shows a multi-core optical waveguide cable 1 with eight individual optical waveguide wires, of which only two wires 3, 4 are shown in FIG. 1A for reasons of clarity. Each wire 3, 4 is surrounded by a thermoplastic protective layer (buffer) 5, 6. A support strand 8 runs in the center of the multi-core optical waveguide cable 1. The cores can be surrounded individually and / or collectively by strain relief means. In the exemplary embodiment shown, common tension relief means 10 in the form of ARAMiD fibers 11 are provided. The wires 3, 4, the support strand 8 and the strain relief means 10 run in a common cable sheath 12. Such an optical fiber cable is, for example, made of Section 4-17 (Figure 5) of the prospectus of SIECOR CORP. known.

An outer shrink tube 20 of a = 85 mm length (known for example under the trade name ATUM 16/4 from RAYCHEM) and another (inner) transparent shrink tube 22 are successively attached to the optical waveguide cable 1 which has been cut to the desired length of b = 75 mm in length (known for example under the trade name DWTC 12/3-x from RAYCHEM, FRG). Both shrink tubes 20, 22 have an adhesive coating on the inside. The fiber optic cable 1 is then freed from its cable jacket 12 at the end; the stripped length 23 is dimensioned to the desired free length of the wires 3, 4 to be branched (e.g. c = 2100 mm). The ARAMiD fibers 11 are trimmed to a suitable protrusion (e.g. d = 16 mm) at their ends 24 over the cable jacket end 25.

FIG. 1B already shows prepared individual sheaths 30, 31 of e = 2000 mm in length threaded over the wires 3, 4, each with individual strain relief means 32, 33 in the form of ARAMID fibers 34, the ends 35, 36 of which are approximately 10 mm protrude. Suitable individual coats are known per se under the name "fan-out tubing" (section 1-6 of the prospectus of SIECOR CORP.). In order for the strain relief means 10; 32, 33 in the interweaving area (f = 11 mm), the ends 37, 38 of the individual sleeves 30, 31 are arranged offset in the axial direction 39.

In a further process step (FIG. IC), the transparent shrink tube 22 is pushed approx. G = 28 mm beyond the cable jacket end 25 beyond the branching area 40 and then air is flowed at at a temperature of approximately 100 ° C. As a result of the shrinking process, the shrink tube 20 contracts and clings closely to the Cable sheath 12 and the individual sheaths 30, 31 which connect with an adhesive layer 43 applied to the inside 42 of the shrink tube 22, so that the branching device is pre-fixed and easy to handle.

As FIG. 1D shows, a gap 44 formed between the individual shells 30, 31 offers sufficient access for a cannula 45 of a metering device 46 (known for example under the name DE OMAT 944 from DELO, Munich, FRG). About 1 ml of a hardenable casting compound 47 in the form of a light-curing adhesive, for example, is inserted through the cannula 45 into the remaining internal volume of the contracted shrink tube 22. B. from DELO with the name DELo-Katiobond 050. At the same time, the branching area 40 is exposed through the transparent shrink tube 22 for about 60 s using a triple-ar fiber exposure device 48 from SCHOTT (trade name KL 1500) at level 5. The ends 24, 35, 36 of the strain relief means 10, 32, 33 are embedded on all sides in the potting means 47.

Subsequently (FIGS. 1E and 1F), a support sleeve 50 made of aluminum with an inner diameter of 12 mm and an outer diameter of 14 mm and a length of 50 mm is pushed over the branching area 40. Then the outer one

Shrink tube 20 pushed symmetrically over the support sleeve 50 and the inner shrink tube 22 in such a way that the inner shrink tube 22 protrudes approx. H = 10 mm on the side 52 facing the multi-core optical fiber cable 1 under the outer shrink tube 20. The outer shrink tube 20 is then exposed to an air stream with a temperature of more than 125 ° C. and shrinks (contracts) closely onto the support sleeve 50, the inner shrink tube 22 and the individual sleeves 30, 31 (FIG. 1F). The shrink tube 20 is additionally fixed by an adhesive layer 55 applied to its inside 54. FIG. 2 shows, in an enlarged representation, a branching device according to the invention, the reference numbers mentioned in connection with FIGS. 1A to 1F being used for the corresponding parts. FIG. 2 shows particularly clearly that the inner volume 58 remaining in the contracted inner shrink tube 22 is almost completely filled by the potting compound 47, the potting compound 47 both the ends 24, 35, 36 of the strain relief means 10 and 32, 33 and the Cable sheath 12 and the individual sheaths 30, 31 embedded and fixed. The support sleeve 50 protects against external mechanical loads and keeps the branch area 40 free of radially inward shrinkage stresses of the outer heat shrink tubing 20. The protrusion of the inner shrink tube 22 towards the optical fiber cable 1 prevents the end edge 56 of the outer shrink tube 20, which has hardened due to the comparatively high degree of shrinkage, from damaging the common cable sheath 12 and / or the individual wires 3, 4 when the optical fiber cable 1 bends.

The branching device according to the invention can also be easily assembled on site without crimp fastening parts and crimping tool. The strain relief means embedded in the sealing compound ensure a very even and safe transmission of tensile loads. The cable sheaths are particularly well protected against being pulled out of the branching device by the potting compound and additionally by the shrink sleeves coated on the inside with adhesive.

FIG. 3 shows an optical waveguide cable arrangement 100 which contains a first thin, flexible optical waveguide cable 102. The first end 102a of the optical fiber cable 102 is terminated by a connector 104 for connection to a data processing device, while the second End 102b enters a connection device 106. The arrangement 100 comprises a robust, less flexible second optical waveguide cable 108, which is resistant to mechanical loads, the first end 108a of which enters the connecting device 106 and the second end 108b of which enters a similar connecting device 110. A third optical waveguide cable 112 is provided with a connecting plug 115 at one end 112a analogous to the first cable 104 and enters the connecting device 110 with its second end 112b. The arrangement shown in FIG. 1 allows the robust cable 108 to be used to lay optical fibers in a manner that is protected and resistant to external damage and loads, and the thinner cables 102, 112 allow flexible and convenient connection of the optical fibers to corresponding optical devices.

FIGS. 4A, 4B, 4C show one of the connecting devices 106 or 110, for example for the optical waveguide cable 102, 108, each of which enters the open end 118, 119 of a first inner shrink tube 122. The ends 102b, 108a of the cables 102, 108 are each stripped with the release of the ends 126, 128 of cable-specific strain relief means (KEVLAR fibers) 130, 132 (FIG. 4B). In FIG. 4A, the strain relief means are not shown in the connection area 133 only for reasons of clarity and for the clear illustration of individual optical fibers 136, 137 running in a protective sheath 134 in the optical fiber cable 102. The optical waveguides 136, 137 enter separate protective sleeves 138, 140, which are surrounded by the sheath 142 of the optical waveguide cable 108. The protective sleeves 134, 138, 140 preferably protrude beyond the end of the sheaths 142, 144 of the optical waveguide cables 102, 108. The optical waveguides 136, 137 can have a length corresponding to the length of the cable 102, so that they pass from the cable 108 into the cable 102 without splicing. For this, the light Waveguides 136, 137 are threaded into protective sheath 134 beforehand. The protective sleeves 138, 140 and any strain relief means running in them preferably end offset in the axial direction in the shrink tube 122. The inner shrink tube 122 is surrounded by a further outer contracted shrink tube 150, the ends 122a, 122b of the inner shrink tube 122 on both sides protrude under the outer heat shrink tubing 150. A support sleeve 152 made of aluminum is arranged between the inner and the outer heat shrink tubing 122, 150, the distance from the inner sleeve

Shrink tube 122 is fixed by a cable sheath piece 154 serving as a spacer. The cable sheath piece 154 effects a concentric and symmetrical alignment of the support sleeve 152 during the shrinking of the shrink tube 150.

To produce the connecting device, the outer shrink tube 150 (for example "ATUM 16/4" from RAYCHEM, FRG) and the inner transparent shrink tube 122 (for example DTWC 12/3-X from Fa. RAYCHEM, FRG) threaded. Both shrink tubes 122, 150 have an adhesive coating on the inside. The strain relief means (ARAMiD fibers) are cut to a suitable overhang (eg 10 mm) of their ends 126, 128 (FIG. 4B). The transparent shrink tube 122 is pushed over the connection area 133 and then flowed with air at a temperature of approximately 100 ° C. The shrinking tube 122, which collapses during the shrinking process, clings closely to the sheaths 142, 144 of the cables 102, 108, which connect to the adhesive layer 156 applied to the inside of the shrinking tube 122. The connection device is thus pre-fixed and easy to handle.

Through the shrink tubing 122, a cannula of, for example, DELOMAT 944 from DELO,

Munich, FRG distributed dosing device are introduced the. About 1 ml of a light-curing adhesive (for example with the designation DELO-KATIOBOND 050) is introduced into the inner volume of the contracted shrink tube 122 as a casting compound 160 (FIG. 2C). At the same time, the connection area 133 is exposed through the transparent shrink tube 122 for several seconds with a fiber exposure device. The ends 126, 128 are wetted on all sides by the potting compound 160 and embedded in it. Subsequently, the support sleeve 152 is pushed over the connection area 133 and above the outer one

Shrink tube 150 arranged symmetrically such that the inner shrink tube 122 protrudes at both ends by several millimeters below the outer shrink tube 150. The outer shrink tube 150, which is also coated on the inside with an adhesive layer, collapses by treatment with an air stream at a temperature of approximately 125 ° C. and nestles closely onto the support sleeve 152 and the inner shrink tube 122 a symmetrical coaxial alignment of the support sleeve 152 is ensured despite the possibly asymmetrically acting shrinking forces of the shrink tube 152. The support sleeve 152 protects against external mechanical loads. The inner shrink tube 122, which is outstanding under the shrink tube 150, prevents the end edges of the shrink tube 152, which are hardened by the comparatively high degree of shrinkage, from damaging the cable sheath 144 and / or the optical waveguide when the cable 102 is bent.

FIG. 5 shows an alternative embodiment of a connecting device, in which a plurality of shrink tubes 200 to 203, staggered in a cascade manner, each receive optical fiber cables 210, 211; 212, 213, 214, 215, 216, 217 in the manner described above and are surrounded by a common shrink tube 220. The individual connection areas 222, 223, 224, 225 are, as described above, in a corresponding manner with a potting compound (not shown). tel filled with determination of the cable-specific strain relief.

Claims

claims

1. Connection device

with a contracted shrink tube (122) into which a first and a second optical fiber cable (102, 108) enter,

the ends (102b, 108a) of the optical waveguide cables (102, 108) are each stripped with the release of the ends (126, 128) of cable-specific strain relief means (130, 132),

- Wherein in the shrink tube (122) a hardening or hardenable casting compound (160) is contained and

- The ends (126, 128) of the cable-specific strain relief means (130, 132) are embedded in the potting means (160).

2. branching device for a multi-core optical fiber cable (1)

- With a contracted shrink tube (22), - into which the optical fiber cable (1) enters, which is freed at the end to release the ends (24) of its strain relief means (10) from a cable sheath (12) common to the wires (3, 4) and - in which the wires (3, 4) branch into at least two individual sheaths (30, 31) provided with individual strain relief means (32, 33), which emerge from the shrink tube (22), characterized in that in the shrink hose (22) contains a hardening or hardenable casting compound (47) and that the ends (24) of the strain relief means (10) of the optical waveguide cable (1) and the ends (35,36) of the strain relief means (32,33) of the individual sheaths (30,31) are embedded in the potting compound (47).

3. Device according to one of the preceding claims, characterized in that ß the shrink tube (22, 122) is transparent and that the potting compound (47, 160) is a light-curing or curable adhesive.

4. Device according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t, d a ß the shrink tube (22,122) is coated on the inside adhesive.

5. Device according to one of the preceding claims, characterized in that at least one optical waveguide cable (108) in its cable sheath (142) contains a plurality of protective sleeves (138, 140) for optical waveguide (136, 137) and that the protective sleeves (138, 140) in end offset in the axial direction in the shrink tube (22, 122).

6. Device according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t, that the (inner) shrink tube (22, 122) is surrounded by a further (outer) contracted shrink tube (20, 150).

7. Device according to claim 6, d a d u r c h g e k e n n z e i c h n e t d a ß the inner shrink tube (22,122) protrudes at least with one end (122a) under the outer shrink tube (20,150).

8. Device according to claim 6 or 7, that a support sleeve (152), preferably made of aluminum, is arranged between the inner (122) and the outer shrink tube (150).

9. Device according to claim 8, characterized in that ß spacing means (154) are provided between the support sleeve (152) and the inner shrink tube (150).

10. The device of claim 9, d a d u r c h g e k e n n z e i c h n e t, that the spacing means (154) are formed by a cable jacket piece.

11. Method for connecting optical fiber cables, in which the optical fiber cables (102, 108) are stripped at the ends to release the ends (126, 128) of their cable-specific strain relief means (130, 132),

- In which the ends (102b, 108a) of the optical waveguide cables (102, 108) are inserted into a contractible shrink tube (122) and

- In which, after contracting the shrink tube (122), a hardening or hardenable potting agent (160) is introduced into the shrink tube (122), so that the ends (126, 128) of the cable-specific strain relief means (130, 132) are embedded in the potting agent (160).

12. A method for producing a branching of a multi-core optical waveguide cable (1),

- In which the optical waveguide cable (1) is released from the end of its cable sheath (12) to release the ends (24) of its strain relief means (10),

- In which the wires (3, 4) of the optical fiber cable (1) in at least two with individual strain relief means

(32, 33) individual coats (30, 31) are threaded and - in which the branching area (40) is surrounded by a shrink tube (22), characterized in that after the shrink tube (22) has contracted, a hardening or hardenable one Potting compound (47) is introduced into the shrink tube (22) and that the ends (24) of the strain relief means (10) of the optical fiber cable (1) and the ends (35,36) of the strain relief means (32,33) Individual jackets (30, 31) are embedded in the casting compound (47).