JP5159648B2 - Slot core, manufacturing method thereof, and optical fiber cable using the slot core - Google Patents

Description

  The present invention relates to a slot core, a method of manufacturing the same, and an optical fiber cable using the slot core, and in particular, a slot core having one groove for accommodating an optical fiber and having at least two strength members, and the slot The present invention relates to a slot core used in a one-groove slot core type optical fiber cable in which the periphery of the core is covered with a sheath, a manufacturing method thereof, and an optical fiber cable using the slot core.

  Conventionally, in an optical fiber cable composed of a slot core having one groove for accommodating an optical fiber therein and a sheath covering the periphery of the slot core, as disclosed in Patent Document 1, the sheath However, there is disclosed a cable having an eccentric sheath structure in which the sheath thickness on the opening side of the groove is relatively thicker than the sheath thickness on the side opposite to the opening.

JP 2008-76897 A

  By the way, in the conventional patent document 1, as shown in FIG. 7 in particular, the optical fiber cable 101 includes one groove 105 for accommodating the optical fiber 103 therein, and at least two strength members. When the slot core 109 having 107A and 107B inside is used, the center of the opening 113 of the groove 105 passes through the center C of the sheath 111 (cable) in a cross section perpendicular to the length direction of the sheath 111 (cable). Is the Y axis, and the X axis is the direction passing through the center C of the sheath 111 (cable) and perpendicular to the Y axis, the two strength members 107A and 107B are on the opening 113 side of the groove 105. Is disposed on the Y-axis inside the slot core 109 at a position opposite to the center.

The above two strength members 107A, when the center of 107B as point O, to the sheath 111 (cable) is not symmetrical with respect to the vertical _{X 1} axis as Y-axis and the point O, and _{X 1} axis Since the amount of contraction of the sheath 111 is different between the side with more sheath 111 and the side with less sheath 111 as a reference, a deformed bend occurs in the optical fiber cable 101 as shown in FIG.

  This bending causes deterioration of the lineability of the optical fiber cable 101 into the duct, and in the overhead wiring, the cable swells in the hanger. In addition, the workability of bundling and laying out 8 when laying cables is also a factor.

  Furthermore, when the optical fiber cable 101 is bent, it is desirable that the bending center axis coincides with the Y axis and further coincides with the lamination center of the optical fiber 103 to be mounted. As shown in FIG. 8, since the bending center axis BL is displaced from the Y axis connecting the centers of the two strength members 107A and 107B, the difference (layer) between the center of the optical fiber 103 and the bending center axis BL of the cable. There is a problem in that the transmission loss characteristic of the optical fiber 103 may be deteriorated.

  An object of this invention is to make an optical fiber cable into a linear form by devising so that the shrinkage | contraction amount of a different sheath may be canceled.

In order to solve the above problems, a slot core according to the present invention has one groove for accommodating an optical fiber therein, and the center of the opening of the groove in a cross section perpendicular to the length direction of the groove. When the Y-axis is a substantially symmetrical direction, a slot core in which at least two strength members are arranged in the Y-axis and / or the vicinity thereof, and a sheath covering the periphery of the slot core are provided. And an optical fiber having an eccentric sheath structure in which the sheath has a thick portion in which the sheath thickness on the opening portion side of the groove is relatively thicker than the sheath thickness of the thin portion on the opposite side to the opening portion side of the groove The slot core used in a cable,
In order to cancel the contraction of the sheath on the opening side of the groove so that the cable after manufacture is linear, the tensile body on the thin-walled side of the sheath is contracted out of the at least two strength members. The present invention is characterized in that a line length difference with other strength members is provided.

  Further, in the slot core of the present invention, in the slot core, the line length difference is expressed as a ratio of the strength member on the thin-walled portion side of the sheath and other strength members in a ratio to the length of the reference slot core. The line length difference is preferably 0.05% or more and 0.28% or less.

The method for manufacturing a slot core according to the present invention has a single groove for accommodating an optical fiber therein, and is substantially symmetrical with respect to the center of the opening of the groove in a cross section perpendicular to the length direction of the groove. When the direction is the Y-axis, the Y-axis and / or the vicinity thereof includes a slot core in which at least two or more strength members are disposed, and a sheath that covers the periphery of the slot core. The slot used in an optical fiber cable having an eccentric sheath structure having a thick portion in which the sheath thickness on the opening side of the groove is relatively thicker than the sheath thickness of the thin portion on the opposite side to the opening side of the groove When manufacturing the core,
In order to cancel the contraction of the sheath on the opening side of the groove so that the cable after manufacture is linear, the tensile body on the thin-walled side of the sheath is contracted out of the at least two strength members. The extrusion molding is performed in a state in which the feeding tension of the at least two strength members is changed and adjusted so as to obtain a line length difference from other strength members .
In the method for manufacturing a slot core according to the present invention, when the difference between the wire lengths of the thin-wall portion side of the sheath and other strength members is expressed as a ratio to the length of the reference slot core, Is 0.05% or more and 0.28% or less.

The optical fiber cable according to the present invention has a groove that accommodates the optical fiber therein, and has a cross-section perpendicular to the longitudinal direction of the groove and passing through the center of the opening of the groove so as to be substantially bilaterally symmetric. When a Y-axis is provided, the Y-axis includes a slot core having at least two strength members disposed therein and / or the vicinity thereof, and a sheath covering the periphery of the slot core, and the sheath includes the groove. In the optical fiber cable which is an eccentric sheath structure having a thick portion in which the sheath thickness on the opening side of the groove is relatively thicker than the sheath thickness of the thin portion on the opposite side to the opening side of the groove,
In order to cancel the contraction of the sheath on the opening side of the groove so that the cable after manufacture is linear, the tensile body on the thin-walled side of the sheath is contracted out of the at least two strength members. The present invention is characterized in that a line length difference with other strength members is provided.

  Also, in the optical fiber cable of the present invention, in the optical fiber cable, the difference in wire length represents a difference between the strength member on the thin-walled portion side of the sheath and other strength members as a ratio to the length of the reference slot core. In this case, the difference in line length is preferably 0.05% or more and 0.28% or less.

  As can be understood from the means for solving the above problems, according to the slot core of the present invention, at least two strength members built in the slot core are optical fiber cables in which the slot core is used. Since the tensile body on the thin-walled portion side of the sheath is made shorter than the tensile body on the thick-walled portion side of the sheath to provide a difference in wire length, the optical fiber cable manufactured using the slot core The tension of the side tension member acts to cancel the contraction force of the sheath and keep the stress balance inside the cable, so that the entire cable can be kept straight and the transmission characteristics and distortion characteristics of the cable can be kept good. It becomes.

  In addition, according to the method for manufacturing a slot core of the present invention, since a prescribed line length difference can be provided in at least two strength members built in the slot core, an optical fiber cable manufactured using the slot core. Keeps the entire cable straight and maintains the cable's transmission and distortion characteristics by maintaining the stress balance inside the cable by the tension of the tensile body on the thin wall side of the sheath canceling out the contraction force of the sheath. It becomes possible to keep it good.

  In addition, according to the optical fiber cable of the present invention, an optical fiber having excellent cable linearity and excellent transmission loss can be obtained by using a slot core having a prescribed line length difference between at least two strength members. Cable can be provided.

It is a perspective view explaining the outline of the manufacturing method of the slot core of embodiment of this invention. It is a schematic sectional drawing of the extrusion molding apparatus of FIG. It is sectional drawing of the arrow III-III line | wire of FIG. It is sectional drawing of the slot core of embodiment of this invention. It is sectional drawing of the optical fiber cable manufactured by embodiment of this invention. It is a perspective view which shows a state when the optical fiber cable of FIG. 5 is bent. It is sectional drawing of the conventional optical fiber cable. It is a perspective view which shows a state when the optical fiber cable of FIG. 7 is bent.

  Embodiments of the present invention will be described below with reference to the drawings.

  Referring to FIG. 5, first, as an example of the optical fiber cable 1 in which the slot core according to this embodiment is used, an optical fiber cable similar to that described in the related art can be cited. That is, basically, a slot core 7 provided with one groove 5 for accommodating the optical fiber 3 therein and a sheath 9 covering the periphery of the slot core 7 are provided. 9 is made of a resin such as polyethylene resin, and has a thick portion 13 in which the sheath thickness on the opening 11 side of the groove 5 is relatively thicker than the sheath thickness on the opposite side to the opening 11 side of the groove 5. It has an eccentric sheath structure. In other words, the sheath 9 opposite to the opening 11 side of the groove 5 is a thin portion 15.

  More specifically, in the cross section perpendicular to the length direction of the optical fiber cable 1, the sheath thickness on the opening 11 side of the groove 5 becomes the maximum sheath thickness (thick portion 13) and the opening 11 of the groove 5. The sheath thickness on the opposite side to the side becomes the minimum sheath thickness (thin wall portion 15).

  In the one-groove slot type optical fiber cable 1 having the above-described configuration, a direction connecting the center of the opening 11 of the groove 5 through the sheath (cable) center C in a cross section perpendicular to the length direction of the sheath (cable). Is the Y axis, and the direction perpendicular to the Y axis through the sheath (cable) center C is the X axis, so that the Y axis is a cable bending neutral line as at least two linear bodies. For example, the strength member 17 is disposed on the Y axis and / or in the vicinity thereof in the slot core 7 at a position opposite to the opening 11 side of the groove 5. In addition, the vicinity of the Y axis mentioned above means that the Y axis becomes a cable bending neutral line by arranging, for example, a pair of linear bodies so as to face the vicinity of the Y axis.

  In this embodiment, two strength members 17A and 17B are arranged. Further, the tensile body 17 is not limited to the above-described linear body, and may be a belt-like body, and a steel wire or FRP can be used as the material. The above-mentioned band-shaped body refers to a long band-shaped member having a rectangular shape such as a flat shape, an elliptical shape, or a rectangular cross section.

  In this embodiment, the groove 5 of the slot core 7 has a circular cross section, but the cross sectional shape of the groove 5 is not limited to a circular cross section. One or more optical fibers 3 are accommodated in the groove 5. In FIG. 1, a total of 10 optical fiber ribbons are accommodated as the optical fibers 3. When the optical fiber 3 is accommodated in the groove 5, the periphery of the optical fiber 3 may be a gap or a buffer material may be interposed. In either case, it is desirable that the position of the optical fiber 3 accommodated in the groove 5 is arranged so as to substantially coincide with the Y axis.

  In addition, as the optical fiber 3, an optical fiber strand, an optical fiber core wire, an optical fiber tape core wire, or the like is used.

  Further, a longitudinal tape 19 having a width that covers the opening 11 of the groove 5 of the slot core 7 and does not cover the entire circumference of the slot core 7 is vertically attached. Note that the sheath tape 9 is directly applied to the longitudinal tape 19 without being pressed by rough winding or the like. In addition, as a material of the vertical attachment tape 19, a non-woven fabric, plastic tapes, such as PET tape, etc. are mentioned.

  In this embodiment, in order to prevent deformation of the optical fiber cable 1 due to contraction of the sheath 9, in consideration of the influence of cable bending due to contraction of the sheath 9, the two strength members 17 </ b> A and 17 </ b> B are in advance. Among them, the tensile strength body 17B on the thin-walled portion 15 side of the sheath 9 is embedded in the slot core 7 while being pulled so as to contract, thereby suppressing the entire bending of the optical fiber cable 1.

  A method for manufacturing the slot core according to this embodiment will be described with reference to the drawings.

  Referring to FIG. 1, the manufacturing method of the slot core according to this embodiment has one groove 5 for accommodating the optical fiber 3 therein, and the cross section perpendicular to the length direction of the groove 5 The slot core 7 in which at least two strength members 17A and 17B are disposed on the Y axis is extruded when the Y axis is a direction that passes through the center of the opening 11 of the groove 5 and is substantially symmetrical.

  That is, as shown in FIGS. 2 and 3, in this embodiment, the two strength members 17 </ b> A and 17 </ b> B are fed out and slot-molded by the extrusion molding device 21.

  In the extrusion molding device 21, a protrusion 25 having substantially the same shape as the groove 5 (the cross section is substantially circular) is provided at the tip of the nipple 23, and the upper surface of the protrusion 25 is formed on the upper surface of the die hole 29 of the extrusion die 27. The openings 11 of the slot grooves 5 are formed so as to be in contact with each other.

  Further, the two strength members 17A and 17B delivered from each strength member bobbin 31 are inserted into two nipple hole portions 33 for strength members provided at positions corresponding to the Y axis of the nipple 23. At this time, in order to apply the contraction force to the strength member 17 so as to cancel the contraction force of the sheath 9 after the cable is manufactured, the above-mentioned 2 is obtained so as to obtain a prescribed line length difference between the two strength members 17A and 17B. Adjustment is made by changing the feeding tension of the tensile strength members 17A and 17B.

  That is, in consideration of the influence of the bending of the cable due to the contraction of the sheath 9 in advance, the contraction of the sheath 9 on the opening 11 side of the groove 5 should be offset so that the optical fiber cable 1 after the cable manufacture is linear. Of the two tensile strength members 17A and 17B, the tensile strength member 17B on the thin-walled portion 15 side of the sheath 9 is sent out while being pulled with a relatively high tension, thereby providing a line length difference. In other words, during slot extrusion molding, the strength member 17B on the thin wall portion 15 side of the sheath 9 in FIG. 5 is mounted relatively short compared to the strength body 17A on the thick wall portion 13 side of the sheath 9. Increase the feed tension.

  The amount of contraction of the strength member 17 is the difference between the lengths of the two strength members 17A and 17B, that is, the line length, when only two strength members 17A and 17B are taken out from the slot core 7 having a certain length. This can be confirmed by measuring the difference.

  Here, the line length difference can be expressed by Equation (1).

Line length difference (%) = [(TM1−TM2) / L] × 100 (1)
However, TM1 is the length of the strength member 17 on the opening 11 side (the thick portion 13 side).
TM2 is the length of the strength member 17 opposite to the opening 11 side (thin wall portion 15 side)
L is the length of the reference slot core 7.

  As described above, the core resin 35 is extruded from the die hole 29 through the resin flow path 37 of the extrusion die 27 in a state where a line length difference is formed between the two strength members 17A and 17B, as shown in FIG. The slot core 7 is extruded. The slot core 7 is cooled in the water tank 39 after being extruded and then taken up by the take-up caterpillar 41 and taken up by the take-up drum 43.

  Therefore, by using the slot core 7 in the optical fiber cable 1, the slot core 7 is opened after the two strength members 17A and 17B are integrated with the core resin 35 by extrusion molding. Since the contraction force acts on the stretched strength member 17B, the contraction of the sheath 9 on the opening 11 side of the groove 5 can be suppressed after manufacturing the cable. By relaxing the stress generated by the sheath 9 due to the temperature contraction, the entire bending of the optical fiber cable 1 can be suppressed by maintaining the stress balance inside the cable.

  Next, eight types of tape core wires shown in Table 1 were produced as prototype cables A to H, and the cable bending state and loss temperature characteristic evaluation of each prototype cable A to H were performed. As shown in FIG.

The cable transmission characteristics are measured at a wavelength of 1.55 μm, and 0.25 dB / km or less is accepted. The temperature cycle of the transmission loss temperature characteristic is −30 degrees to +70 degrees × 3 cycles, and the value indicates the maximum value measured at a wavelength of 1.55 μm. Further, the cable linearity was linear when extended, and a level where there was no problem was marked with ◯, undulation was observed, but an acceptable level was marked with Δ, and a large level of undulation was marked with x.

  Thereby, the above-described line length difference can be optimized from Table 1. According to the result of the trial production, if the difference in wire length is less than 0.05%, the cable swells and the transmission characteristics cannot be satisfied. Further, when the line length difference is 0.30% or more, the loss temperature characteristic is confirmed to be deteriorated.

  Therefore, the strength member 17B on the thin portion 15 side is made shorter than the strength member 17A on the thick portion 13 side so that the line length difference is 0.05% or more and 0.28% or less. It is desirable to manufacture by adjusting the tension of the strength member 17B. In this way, after the cable is manufactured, the tension of the strength member 17B acts so as to offset the contraction force of the sheath 9, keeping the entire cable straight and maintaining good transmission characteristics and distortion characteristics of the cable. Is possible.

  As described above, when the slot core 7 provided with a prescribed line length difference between at least two strength members 17A and 17B is used for the optical fiber cable 1, the cable linearity is excellent and the transmission loss is excellent. An optical fiber cable 1 is obtained.

  Table 1 evaluates the influence of the difference in wire length between the two strength members 17A and 17B on the optical fiber cable 1. However, the influence of the wire length difference on the mere slot core 7 is almost the same as in Table 1. A similar evaluation is obtained.

DESCRIPTION OF SYMBOLS 1 Optical fiber cable 3 Optical fiber 5 Groove 7 Slot core 9 Sheath 11 Opening part 13 Thick part 15 Thin part 17, 17A, 17B Strength member 19 Vertical tape 21 Extruder 23 Nipple 25 Protrusion part 27 Extrusion die 29 Die hole 31 Tensile Bobbin 33 Nipple Hole 35 Core Resin 37 Resin Channel 39 Water Tank 41 Take-up Caterpillar 43 Winding Drum

Claims (6)

When a Y-axis is defined as a direction having a single groove for accommodating an optical fiber therein and being substantially bilaterally symmetric through the center of the opening of the groove in a cross section perpendicular to the length direction of the groove, the Y axis A slot core having at least two or more strength members disposed in the shaft and / or its vicinity, and a sheath covering the periphery of the slot core, and the sheath has a sheath thickness on the opening side of the groove The slot core used in an optical fiber cable having an eccentric sheath structure having a thick portion relatively thicker than a sheath thickness of a thin portion on the opposite side to the opening side of the groove,
In order to cancel the contraction of the sheath on the opening side of the groove so that the cable after manufacture is linear, the tensile body on the thin-walled side of the sheath is contracted out of the at least two strength members. A slot core characterized by providing a line length difference with other strength members.   The line length difference is expressed as a ratio between the strength member on the thin-walled portion side of the sheath and the other strength member as a ratio to the length of the reference slot core, and the line length difference is 0.05% or more, and The slot core according to claim 1, wherein the slot core is 0.28% or less. When a Y-axis is defined as a direction having a single groove for accommodating an optical fiber therein and being substantially bilaterally symmetric through the center of the opening of the groove in a cross section perpendicular to the length direction of the groove, the Y axis A slot core having at least two or more strength members disposed in the shaft and / or its vicinity, and a sheath covering the periphery of the slot core, and the sheath has a sheath thickness on the opening side of the groove When manufacturing the slot core used for the optical fiber cable that is an eccentric sheath structure having a thick portion relatively thicker than the sheath thickness of the thin portion on the opposite side to the opening side of the groove,
In order to cancel the contraction of the sheath on the opening side of the groove so that the cable after manufacture is linear, the tensile body on the thin-walled side of the sheath is contracted out of the at least two strength members. A method of manufacturing a slot core, wherein extrusion is performed in a state in which a feeding tension of the at least two strength members is changed and adjusted so as to obtain a line length difference from other strength members . The line length difference is 0.05% or more when the difference between the strength member on the thin-walled portion side of the sheath and the other strength members is expressed as a ratio with respect to the length of the reference slot core. 4. The method of manufacturing a slot core according to claim 3, wherein the slot core content is 28% or less. When a Y-axis is defined as a direction having a single groove for accommodating an optical fiber therein and being substantially bilaterally symmetric through the center of the opening of the groove in a cross section perpendicular to the length direction of the groove, the Y axis A slot core having at least two or more strength members disposed in the shaft and / or its vicinity, and a sheath covering the periphery of the slot core, and the sheath has a sheath thickness on the opening side of the groove In the optical fiber cable that is an eccentric sheath structure having a thick portion relatively thicker than the sheath thickness of the thin portion on the opposite side to the opening side of the groove,
In order to cancel the contraction of the sheath on the opening side of the groove so that the cable after manufacture is linear, the tensile body on the thin-walled side of the sheath is contracted out of the at least two strength members. An optical fiber cable characterized by providing a line length difference with other strength members. The line length difference is 0.05% or more when the difference between the strength member on the thin-walled portion side of the sheath and the other strength members is expressed as a ratio with respect to the length of the reference slot core. 6. The optical fiber cable according to claim 5 , wherein the optical fiber cable is 28% or less.

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