JP4907909B2 - Outer sheath removal method for optical fiber cable - Google Patents

Description

The present invention relates to envelope elimination method of an optical fiber cable which strength members are embedded in the cable outside the object.

  In recent years, with the development of optical communication networks, various types of low-loss and broadband optical fiber cables have been proposed according to the installation environment. For example, one or more optical fiber tape cores in which a plurality of optical fiber strands are arranged in parallel and collectively coated on the outer periphery are laminated, and a buffer layer is provided around the optical fiber tape core. There are some which have been coated by extrusion of plastics such as polyethylene. In this cable, a tensile body made of steel wire or the like is embedded in the jacket at a position facing the optical fiber tape core, thereby preventing an increase in transmission loss of the optical fiber due to temperature changes. At the same time, no stress is applied to the optical fiber during cable installation (see, for example, Patent Document 1).

  However, the optical fiber cable described in Patent Document 1 increases the transmission loss of the optical fiber due to excessive or insufficient adhesion strength between the strength member and the jacket, or covers the jacket during connection work at a terminal or the like. There was a problem that it could not be easily removed.

On the other hand, an optical fiber cable is known that optimizes the adhesion strength between the strength member embedded in the jacket and the jacket, prevents an increase in transmission loss due to temperature changes, and has excellent jacket removal properties. (For example, refer to Patent Document 2). In the optical fiber cable described in Patent Document 2, two strength members 15 are embedded in the cable jacket 14 vertically, for example, at positions symmetrical to each other with respect to the center of the cable. The drawing force is 150 to 600 N / 20 mm.
Japanese Patent No. 3064284 JP 2004-287221 A

  However, even if the pulling force of the strength member is set to 150 to 600 N / 20 mm as described in Patent Document 2, there may be a problem in the jacket removability. For example, even if the pulling force specified here is satisfied, a special tool is required if the pulling force is several hundred N, and it is extremely difficult to manually remove the jacket in a limited work space. is there. On the other hand, when the outer cover is twisted instead of being pulled out in the longitudinal direction, the outer cover is twisted even with a relatively small force. In this case, the tensile strength member may be twisted and folded together with the outer cover. .

The present invention has been made in view of the circumstances as described above, and does not use a special tool, and even in a limited work space, it is easy to remove the outer cover manually without folding the tensile body. and to provide a jacket removal method of the optical fiber cable capable of performing.

An optical fiber cable jacket removal method according to the present invention is a jacket removal method for removing a jacket around a tensile strength body of an optical fiber cable in which a tensile strength body is vertically embedded in the jacket. Then, the outer cover is cut at a position of 20 mm in length from the cable terminal, and the cut outer cover is twisted around the strength member to peel off the adhesion with the strength member, and then pulled out. Further, this optical fiber cable has a tensile body bonded to the outer sheath, and the pulling force is 100 N / 20 mm or more. The outer sheath is cut at a position of 20 mm in length from the cable end and twisted around the tensile body. then, in which the adhesion between the strength member at an angle twisting within 720 degrees were as completely peeled. Here, the optical fiber cable is cut in the outer cover at a position of 20 mm in length from the end, twisted around the tensile body, and the longitudinal direction of the outer cover after the adhesion with the tensile body is completely peeled off. The pulling force is preferably 40 N / 20 mm or less.

  According to the present invention, when removing the jacket of the optical fiber cable, it is possible to easily perform it manually without using a special tool without folding the tensile body even in a limited work space. Become.

Figure 1 is a sectional view showing an example of an optical fiber cable you remove the jacket by envelope removal method according to the present invention, FIG. 1 (A) is an example of a round optical fiber cable, FIG. 1 (B ) Shows an example of a self-supporting optical fiber cable. In the figure, 1 and 2 are optical fiber cables, 11 and 21 are optical fiber strands, 12 is an optical fiber ribbon, 13 and 23 are buffer layers, 14 and 24 are strength members, 15 and 25 are tear strings, 16 , 26 are cable jackets, 17 and 27 are protrusions, 22 is an optical fiber core wire, 30 is an optical cable neck, 31 is an optical cable support wire, and 32 is an optical cable support wire covering portion.

As shown in FIG. 1 (A), the optical fiber cable 1 that to remove the jacket by envelope removal method according to the present invention, the optical fiber ribbon 12 laminating a plurality, such as polypropylene fibers around A buffer layer 13 is provided, and a cable jacket 16 is formed on the outer side by extrusion molding of a plastic such as polyethylene or polyvinyl chloride.

  The optical fiber ribbon 12 is formed by arranging a plurality of optical fiber strands 11 in a tape shape and collectively coating the outer periphery thereof. In the example of FIG. 1A, an example is shown in which six optical fiber ribbons 12 in which four optical fiber strands 11 are arranged and whose outer periphery is collectively covered are laminated. The number of cores and the number of stacked layers are not limited to this. Further, the optical fiber 11 may be coated. Moreover, although the example which provided the buffer layer 13 around the optical fiber tape core wire 12 is shown, it is good also as a structure which replaces with the buffer layer 13 and accommodates the optical fiber tape core wire 12 in a tube, for example.

  Further, as shown in FIG. 1A, for example, two tear strings 15 are embedded in the cable jacket 16 on the diagonal line at the center of the optical fiber cable 1. In addition, it is good to form the small protrusion 17 in the outer surface of the cable jacket 16 as a position display of the part in which the two tear strings 15 were embedded. Moreover, you may form this protrusion by marking.

  In the optical fiber cable 1, a tensile body 14 is vertically embedded in the cable jacket 16. In FIG. 1 (A), the strength members 14 are embedded vertically so as to be symmetrical with respect to the center of the cable, and each of the strength members 14 is rotated by about 90 ° in the circumferential direction as described above. A total of two tear strings 15 are vertically attached and embedded at each position. As shown in FIG. 1A, in general, there are many structures in which two strength members are embedded on the diagonal of the center of the optical fiber cable 1, but in the present invention, the number of strength members and the arrangement thereof are used. There are no restrictions. However, as will be described later, in the present invention, the cable jacket 16 is cut and removed by twisting around the strength member 14, so that the cable jacket 16 is divided vertically between the adjacent strength members. Necessary.

  In the cable terminal and the intermediate branch portion, the jacket is removed by a predetermined length. By removing the outer sheath, the strength member 14 can be directly gripped to obtain a strong gripping force, and at the same time, when the strength member 14 is made of metal, it is possible to ground. Further, the tensile body 14 can be replaced by FRP (glass fiber reinforced plastic) in addition to the steel wire.

  Next, a method for bonding the strength member 14 and the cable jacket 16 will be described. The strength member 14 is bonded to the cable jacket 16 and has a pulling force of 100 N / 20 mm or more. As a specific adhesion method, the adhesiveness of the jacket is used for direct adhesion, or an adhesive thermoplastic resin is coated on the surface of the tensile body, and then the outer periphery of the cable jacket is coated. The pulling force of the strength member 14 includes the types of materials used for the strength member 14 and the cable jacket 16, the surface shape and properties of the strength member 14 (including surface treatment such as application of adhesive), the cable jacket 16. It can be adjusted according to the extrusion conditions.

  2A and 2B are diagrams for explaining a method of removing the jacket of the optical fiber cable of FIG. 1A, FIG. 2A is a schematic perspective view of the optical fiber cable, and FIG. The BB sectional drawing of the optical fiber cable of 2 (A) is shown. In the figure, C is a position for cutting the cable jacket around the strength member, L is a partial peeling range of the cut portion, and the other parts that are the same as in FIG. To do. Further, the jacket removal with the optical fiber cable of FIG. 1B described later is basically the same, and the description thereof is omitted.

As shown in FIG. 2 (A), the jacket removal method of the present invention, with respect to the optical fiber cable 1, after the silo in a semicircular angle shaped notched along the jacket axially from the terminal When the cable jacket 16 is cut at a position C having a length of 20 mm and twisted around the strength member 14, the bonded portion is completely peeled off within a twist angle of 720 degrees. Moreover, it is more preferable if the adhesion part peels off at a twist angle of 360 degrees or less. That is, the optical fiber cable 1 that removes the jacket by the jacket removing method of the present invention has a twist angle within 720 degrees when the cable jacket 16 is cut and twisted at a position 20 mm in length from the terminal. It is fabricated so that the bonded portion with the strength member 14 is completely peeled off.

  As shown in FIG. 2 (B), when the cable jacket 16 is being twisted, the bond is partially peeled off at the jacket cutting point (position C), and the strength member 14 is twisted in this range L. ing. If the adhesive strength is high and difficult to peel, the above-described partial peeling range becomes narrow (that is, the twisting strength of the strength member 14 is increased), and the adhesive strength is stronger than the twisting torque of the strength member 14, The strength member 14 is twisted and broken until it exceeds the twisting limit. From the results of the experiment, it has been confirmed that if the twist angle of the cable jacket 16 is within 720 degrees and the adhesive strength is such that the bonded portion completely peels off, the tensile strength body 14 can be removed without breaking. .

  As described above, in the present invention, in order to suppress an increase in transmission loss due to a temperature change, an initial pulling force of the strength member is specified, and in order to facilitate the outer cover removal work at the terminal, the outer cover is twisted. It defines the twist angle in the operation of turning and peeling the bonded portion with the tensile body.

According to the present invention, when carrying out the outer sheath removal work of the optical fiber cable, it is possible to carry out the work manually without using a special tool and without breaking the tensile body even in a limited work space. . On the other hand, in the cable described in Patent Document 2, the pull-out force of the tensile strength body is set to 150 to 600 N / 20 mm for the purpose of achieving both suppression of increase in transmission loss due to temperature change and coat removal properties. It is difficult to remove the outer cover manually if there is a pulling force. Furthermore, if there is a pulling force of 600 N, it is difficult to pull it out manually using a tool such as pliers. However, if the peel adhesion portion twisted about the cable jacket to as described above earlier, also easily be removed envelope with a force of sufficiently possible manually, engaging Ru optical fiber of the present invention If the cable is used, the peelability of the adhesive part is poor, and the adhesive part can be peeled off without twisting and breaking the tensile body together. After that, the outer cover is easily removed with a relatively small pulling force. it can.

Further, after the bonded portion is peeled off, the pulling force of the outer jacket is determined by the frictional force. By setting this pulling force (the pulling force after peeling) to 40 N / 20 mm or less, the outer cover removing operation becomes easier. . That is, in the optical fiber cable 1 for removing the jacket by the jacket removing method of the present invention, the cable jacket 16 is cut and twisted at a position 20 mm in length from the end, and the bonded portion to the strength member 14 is peeled off. After that, it is preferable that the cable jacket 16 is produced so that the force for pulling it out in the longitudinal direction is 40 N / 20 mm or less.

  Actually, whether the outer cover is removable is influenced not only by the adhesive force between the cable jacket 16 and the strength member 14 but also by the pulling force after the adhesion is peeled off. Since the technique of Patent Document 2 defines only the pulling force as the adhesive strength between the outer cover and the tensile body, the adhesive material remains on the surface of the tensile body after peeling even if this condition is satisfied. However, in the present invention, it was possible to obtain a good coat removability by defining the pulling force after the bonded portion peeled off.

  Furthermore, in order to have the above-mentioned adhesive strength and removability, it is preferable to use a blend of an adhesive material and a non-adhesive material for the adhesive layer, and the blending ratio depends on the type of adhesive used. It can determine suitably so that it may become said adhesive state.

  In fact, Patent Document 2 describes that the adhesive force is adjusted by changing the thickness of the adhesive layer using a commercially available adhesive, but from the viewpoint of the stability of the production considering mass production, Rather than controlling the thickness to be thin, it is easier to coat a material that provides a predetermined adhesive strength with a certain thickness. In the present invention, as a specific means for obtaining an appropriate adhesive strength as described above, a material having an appropriate adhesive strength can be obtained by blending and diluting with an easily available commercial adhesive and a non-adhesive material. An adhesive layer made of the material is provided.

  The outer diameter of the strength member 14 embedded in the cable jacket 16 is preferably φ1.2 mm or less. The smaller the strength member 14 is, the more clearly the effect of the present invention appears. Therefore, it is preferable to define the maximum outer diameter of the strength member 14 in this way.

  The cable type may be round or self-supporting, but the self-supporting optical fiber cable 2 having a support wire as shown in FIG. Since it is a diameter, the easiness of removing the outer cover of the present invention becomes clear. The optical fiber cable 2 shown in FIG. 1 (B) is an optical fiber cable in place of the optical fiber tape core wire 12 other than the optical fiber cable 1 shown in FIG. An optical fiber core wire 22 formed by bundling a plurality of wires 21 is accommodated, and the other buffer layer 23, strength member 24, tear string 25, cable jacket 26, and protrusion 27 are shown in FIG. This is basically the same as those in A), and the description thereof is omitted. In addition, the optical fiber core wire 22 accommodated in the optical fiber cable 2 may be in any form, and for example, a tape core wire type or a single core type shown in FIG.

  The self-supporting optical fiber cable 2 has a structure in which an optical cable support line 31 is attached to a cable jacket 26 in the round optical fiber cable 1. The outer periphery of the optical cable support wire 31 is covered with the same material as the cable jacket 16 to form an optical cable support wire covering portion 32. Then, in order to attach the optical cable support wire 31 to the cable jacket 26, a part of the cable jacket 26 and a part of the optical cable support wire covering portion 32 are connected by the optical cable neck 30 made of the same material as the optical cable jacket 16. Are connected.

In the case of the self-supporting type cable 2 having the support wire shown in FIG. 1B, the strength member 24 embedded in the main body jacket (cable jacket 26) is generally a small diameter, and the strength member according to the present invention. The effect that 24 is not broken appears clearly. On the other hand, in the adhesive strength in the technique of Patent Document 2, the thin tensile member is more easily broken when the outer cover is twisted.

  In addition, as shown in both FIGS. 1A and 1B, in the case of a structure in which a plurality of strength members are embedded, the outer cover is divided in the vertical direction, and one strength member is formed in one part. If it is made to contain, it will become easy to do the operation | work of a jacket removal. For this reason, a structure in which the tear string is embedded at a position shifted by 90 degrees from the tensile strength member for the outer casing is advantageous.

  FIG. 3 is a cross-sectional view showing an example of markings indicating the embedding positions of strength members in the optical fiber cable of FIG. In the figure, 5 is a nipper, 18a is a protrusion, 18b is a protrusion having a shape different from that of the protrusion 18a, and 18c is a cutting position when the protrusion 18b is provided. In addition, although the example of marking is demonstrated based on FIG. 1 (A), even if it is the cable of FIG. 1 (B), for example, one uses the optical fiber neck part 30 for marking, and the marking example which demonstrates the other below Should be applied.

  As shown in FIGS. 3 (A) and 3 (B), if there is a marking by a projection 18a or a line (not shown) on the cable jacket 16 so that the position where the strength member 14 is embedded is known, for example, a nipper When the outer cover is cut with a tool such as 5, the possibility that the tensile strength body 14 is accidentally damaged can be reduced. If the projection 18b having a predetermined width is provided as shown in FIG. 3B, the blade of the nipper 5 is inserted in accordance with the side surface (position 18c) of the projection 18b as shown in FIG. It can be devised so that the blade does not hit the strength member 14.

As described above, the structure of the optical fiber cable to be removed by the jacket removing method according to the present invention has been described while touching the jacket removing work. Next, an example of the jacket removing work is divided vertically. The work will be described in detail.

  FIG. 4 is a diagram for explaining in detail the work method for removing the jacket of the optical fiber cable of FIG. In the figure, the same portions as those in FIGS. 1A and 2 are denoted by the same reference numerals, and the description thereof is omitted.

  First, as shown in FIG. 4A, when the outer jacket is removed, if there is a tear string, the cable jacket 16 is divided vertically by using this. Here, when there is no tear string, it may be cut with a tearing tool such as a cutter. Next, as shown in FIG. 4 (B), the cable jacket 16 is cut at a position C 20 mm long from the terminal, and this portion is twisted around the strength member 14 to be bonded to the strength member 14. To peel off. Then, after the bonded portion is completely peeled off, the cable jacket 16 is pulled out as shown in FIG. The above operation is repeated several times to remove the cable jacket 16 having a predetermined length. For example, when it is desired to remove the cable jacket 16 having a length of 40 mm from the terminal, the above-described operation may be repeated twice. If there are a plurality of strength members 14 in the optical fiber cable 1, the same operation is performed for each.

  As described above, by first twisting the cable jacket to peel off the bonded portion with the strength member, the cable jacket can be easily removed manually without using a special tool. Even if the cable jacket pulling force is 100 to 500 N / 20 mm and the jacket twist angle for peeling off the bonded portion of the tensile strength body is 720 degrees or less, the conventional jacket stripping method that pulls the jacket first does not work. Have difficulty. However, in the present invention, the outer cover is first twisted in order to peel off the bonded portion with the strength member, and then the outer cover is pulled out, so that the outer cover can be easily removed manually.

  A self-supporting cable as shown in FIG. 1 (B) was prototyped, and its optical characteristics and jacket removal were evaluated. In this self-supporting cable, 24 SM fiber cores are mounted as optical fiber cores, L-LDPE (linear low density polyethylene) is used as the cable jacket material, and the cable jacket dimension is set to an outer diameter of 10 A steel wire having a diameter of 0.72 mm was used as the tensile strength embedded in the main body, and a 7 / 1.4 steel stranded wire was used as the cable support wire.

  The materials A to D having the material types and blending settings shown in Table 1 below were used as materials used (adhesive, polyethylene for dilution). Here, NUC-ACE GA004 is an adhesive resin manufactured by Nihon Unicar, Admer LB030 is an adhesive resin manufactured by Mitsui Chemicals, and Sumikasen G201F is a low density polyethylene manufactured by Sumitomo Chemical.

  Furthermore, conditions 1 to 5 shown in Table 2 below were used as trial conditions. In these conditions 1 to 5, the type of adhesive and the thickness of the adhesive layer were used as parameters.

(1) Evaluation of transmission characteristics and pulling force Under each condition as described above, initial transmission loss (measured with 1.55 μm wavelength OTDR), temperature characteristics (transmission loss fluctuation at −30 to 70 ° C.), and tensile body Table 3 below shows the results of testing the initial pulling force.

  Only in condition 5, the temperature characteristics were poor, and after the test, the tensile body protruded at the cable end. From this, it can be seen that if the pulling force of the strength member is insufficient, the transmission characteristics are affected.

(2) Evaluation of jacket removability Next, with respect to the cable jacket that is vertically divided so that one strength member is included, the jacket material is cut at a position 20 mm in length from the terminal as shown in FIG. The work of twisting it and then pulling it out was performed. At this time, the twist angle (peeling twist angle) until the bonded portion of the tensile strength member and the outer shell peeled, and the outer sheath pulling force (peeling force after peeling) after the adhesion was peeled off were measured. The measurement results are shown in Table 4 below.

  As shown in Table 4, under the conditions 3, 4 and 5 in which the twisting angle at which the adhesion peeled off was less than 720 degrees, the tensile strength member did not break at all, and the jacket removal property was good. In condition 1, the tensile strength body broke with a probability of 90%, and the twist angle when it did not break barely exceeded 720 degrees. Condition 2 also exceeded 720 degrees, and the tensile strength body broke with a probability of 20% although it was lower than condition 1.

  In conditions 1 to 5, the torque for twisting the outer jacket having a length of 20 mm is ≦ 200 N · mm, which is a level that can be easily twisted manually without using a tool. With respect to the pulling force after the adhesive was peeled off, conditions 3, 4 and 5 below 40 N / 20 mm were able to pull out the cover without difficulty and the workability was good.

  Comparing this result with the results in Table 3, the lower the initial pulling force, the less the tensile strength body will not be broken, and the optimum twisting angle and pulling force after debonding of the adhesive part are selected by appropriate material selection. It can be seen that good coat removability can be secured.

In cross-sectional view showing an example of an optical fiber cable by envelope removal how to remove the jacket of the present invention, an example of FIG. 1 (A) round the optical fiber cable, FIG. 1 (B) self-supporting 1 shows an example of a type of optical fiber cable. It is a figure for demonstrating the work method of the jacket removal of the optical fiber cable of FIG. 1 (A). It is sectional drawing which shows the example of the marking which shows the embedding position of the strength body in the optical fiber cable of FIG. It is a figure for demonstrating in detail the working method of the jacket removal of the optical fiber cable of FIG. 1 (A).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,2 ... Optical fiber cable, 5 ... Nipper, 11, 21 ... Optical fiber strand, 12 ... Optical fiber tape core wire, 13, 23 ... Buffer layer, 14, 24 ... Strength body, 15, 25 ... Tear string, DESCRIPTION OF SYMBOLS 16, 26 ... Cable jacket, 17, 27 ... Projection, 18a, 18b ... Projection, 18c ... Cutting position, 22 ... Optical fiber core wire, 30 ... Optical cable neck, 31 ... Optical cable support line, 32 ... Optical cable support line coating Department.

Claims (2)

For an optical fiber cable in which a tensile body is vertically embedded in the outer jacket, a jacket removing method for removing the jacket around the tensile body,
In the optical fiber cable, the tensile body is bonded to the outer casing, and the pulling force is 100 N / 20 mm or more. The outer tension is obtained by cutting the outer casing at a position of 20 mm in length from the end of the optical fiber cable. An optical fiber cable that, when twisted around the body, completely peels off the bond with the tensile body at a twist angle of 720 degrees or less,
Cutting the envelope at the position of 20mm long from the terminal of the optical fiber cable, the pulling out the envelope and the cutting, from twisted about around the strength member is peeled off the adhesive between the strength members A method for removing the outer casing as a feature. The method of removing a jacket according to claim 1 , wherein a force withdrawing in a longitudinal direction of the jacket after the adhesion with the tensile body is completely peeled is 40 N / 20 mm or less.

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