JP2007140003A - Optical fiber cable and method for manufacturing optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber cable in which all of the coated fibers can be easily taken out when the cable is torn from a notch to take out coated optical fibers by preventing the coated optical fibers from being embedded in a coating material. <P>SOLUTION: A coating material fed to a crosshead 11 is applied on a coated optical fiber 1, a support wire 2 and a tension body 3 passing through insertion holes of a nipple 12, and then discharged through an exit of a die 13. The exit side of the insertion hole where the coated optical fiber 1 is inserted among the insertion holes of the nipple 12 is provided with a pipe 13 which extends the insertion hole. The pipe 14 is set to locate the top end of the pipe 14 on a parallel land portion L of the die 13, while controlling the distance L1 between the top end r of the pipe 14 and the top end in the exit side of the die 13, and the distance L2 between the exit s of the insertion hole of the nipple 12 and top end q in the nipple side of the parallel land portion L to satisfy L1=1.0 to 2.5 mm and L2=1.0 to 4.5 mm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical fiber cable and a method for manufacturing the optical fiber cable. Related to fiber cable.

  With the rapid spread of the Internet, etc., in addition to increasing the speed of information communication and increasing the amount of information, the construction of an optical network for two-way communication and large-capacity communication has recently progressed. FTTH (Fiber To The Home) service that provides high-speed communication services has been started. For this reason, there is an increasing demand for optical fiber cables such as drop cables used for drawing into the home and indoor cables for home wiring.

FIG. 5 is a diagram showing a configuration example of a drop cable. In the figure, 1 is an optical fiber core wire, 2 is a support wire, 3 is a strength member, 4 is a main body jacket, 5 is a notch, and 6 is a support wire portion. A jacket, 7 is a main body part, 8 is a support line part, and 9 is a neck part. The optical fiber cable of this configuration example is configured by integrally connecting a main body portion 7 and a support wire portion 8 with a neck portion 9 that can be easily separated. The main body 7 has a configuration in which two strength members 3 are arranged in parallel on both sides of a plurality of optical fiber cores 1, and the core wire 1 and the strength members 3 are integrally covered with a main body jacket 4. is doing. A tear notch 5 is provided on both side surfaces of the main body jacket 4 for facilitating removal of an internal optical fiber core wire (hereinafter simply referred to as a core wire) 1.
The support wire portion 8 is configured by covering a support wire 2 made of a high tensile strength wire such as a steel wire with a support wire portion jacket 6. These support wire portion jacket 6 and main body portion jacket 4 are simultaneously formed by the same process.

  When laying the optical fiber cable of FIG. 5, the support wire portion 8 is partially separated from the main body portion 7 in order to apply tension to the structure or to pull the main body portion 7 into a closure or the like. Also, when used for indoor optical wiring, the support wire portion 8 is used by being separated from the main body portion 1. For this reason, the main-body part 7 and the support line part 8 are connected and integrated through the narrow neck part 9 so that it can be easily separated by a worker's hand.

  The jacket that constitutes the optical fiber cable as described above is formed by extrusion coating of plastic resin using a crosshead. The crosshead is a device that constitutes a part of the extruder, and is connected to a cylinder for supplying plastic resin that has been heated into a fluid. A die is attached to one end of the crosshead, and a nipple is positioned at a predetermined interval inside the die. Insertion holes are provided in the nipple, and the plastic resin extruded from the gap between the die and the nipple is coated on the tensile body and the optical fiber that have passed through the insertion holes (see, for example, Patent Document 1). ).

In addition, as another configuration example of the optical fiber cable in which the core wire and the tensile body are coated with a plastic resin, the separated state of the optical fiber is stabilized by arranging the inclusions around the plurality of core wires. There is something. Here, the core wire, the intervening body, and the tensile body arranged on both sides thereof are supplied to the extrusion head and covered with a sheath made of plastic resin. The nipple of the extrusion head is provided with a hole through which the core wire and the interposed body are inserted independently of each other (see, for example, Patent Document 2).
JP 2004-12540 A JP 2004-70248 A

  As described above, an optical fiber cable applied to a drop cable or an indoor cable has a structure in which one or more optical fiber core wires (hereinafter simply referred to as a core wire) are collectively covered with a tensile body and a support wire. Generally, a notch 5 for tearing as shown in FIG. 5 is formed on the jacket of the optical fiber cable so that the core wire can be easily taken out.

However, in a drop cable containing two or more core wires, the core wires are buried in the covering material, and it takes time and effort to take out all the core wires at the time of cutting the notch portion and separating the core wires. There's a problem.
FIG. 6 is a diagram for explaining a problem at the time of cutting such a notch portion. When the drop cable as shown in FIG. 5 described above is torn from the notch 5, the main body jacket 4 is broken and the core wire 1 accommodated therein can be taken out. At this time, if the core wire 1 is filled with the coating material during the covering molding of the main body jacket 4, it becomes impossible to take out the entire core wire 1 even if the main body jacket 4 is cut from the notch 5. .

  For example, as indicated by the arrow A shown in FIG. 6 above, the core wire 1 located away from the tear surface of the main body jacket 4 is in a state of being buried in the surrounding main body jacket 4, and thus has been cut off. It is necessary to stretch or bend the main body jacket 4, and it takes time to take out the core wire 1.

  In order to solve such a problem, a structure in which the covering material around the core wire is formed into a pipe shape so that the core wire is not restrained by the covering material is also considered. However, in this structure, the core wire moves inside the pipe-shaped coating material, and there is a possibility that the core wire is pulled or protruded at the end portion of the optical fiber cable and disconnected.

  Further, as disclosed in Patent Document 2, a structure in which the periphery of an optical fiber core wire is covered with an intermediate body such as a plastic yarn and the outside thereof is covered is also considered. Since the number of members increases, the cost increases, and it is not efficient because it is necessary to supply the inclusions in the manufacturing process.

  The present invention has been made in view of the above-described circumstances. By preventing the optical fiber core wire from being embedded in the coating material, all the cores can be easily removed when the optical fiber cable is cut from the notch and the core wire is taken out. It is an object of the present invention to provide an optical fiber cable and a method for manufacturing the optical fiber cable that can take out a wire.

  The method of manufacturing an optical fiber cable according to the present invention includes a method in which a plurality of optical fiber cores and a tensile body are supplied to an extrusion crosshead, and the optical fiber core wire and the tensile body are collectively coated using a coating material. Is molded. A notch for taking out the optical fiber core wire is formed in the jacket. The extrusion crosshead includes a nipple having a plurality of insertion holes through which the optical fiber core wire and the tensile body are respectively inserted, and a pipe that extends only the insertion hole through which the optical fiber core wire is inserted to the outlet side, and a nipple A crosshead is used that includes an optical fiber core wire that has passed through the insertion hole and a die that defines the shape of the jacket by covering the tensile strength member with a coating material.

  In the optical fiber cable manufacturing method of the present invention, the pipe tip is set so that the tip of the pipe is positioned in the parallel land portion provided in the die, and the distance between the tip of the pipe and the tip of the outlet side of the die is set to L1. When the distance between the outlet of the insertion hole and the end of the parallel land portion on the nipple side is L2, L1 = 1.0 to 2.5 mm and L2 = 1.0 to 4.5 mm. To do.

  In the optical fiber manufacturing method according to the present invention, the optical fiber cable has two strength members arranged in parallel on both sides of the plurality of optical fiber cores, and the notches are opposed to each other at two locations on both sides of the jacket. The line connecting the notch tips and the line connecting the two strength members are orthogonal to each other.

  Moreover, the optical fiber cable of this invention has a some optical fiber core wire and the jacket coat | covered around those optical fiber core wires. The direction perpendicular to the straight line connecting the centers of the adjacent optical fiber cores is the height direction, the radius of the optical fiber core is H1, and the outer sheath that has entered between the adjacent optical fiber cores H2 / H1 is in the range of 0.10 to 0.50, where H2 is the distance between the tip position in the height direction and the apex in the height direction of the optical fiber core wire. .

  In the optical fiber cable of the present invention, two strength members are arranged in parallel on both sides of a plurality of optical fiber cores, and the notches are provided so as to face each other at two locations on both sides of the jacket. The connecting line and the line connecting the two strength members are orthogonal to each other.

  According to the present invention, the degree of adhesion between the core wire and the covering material can be optimized, and the core wire can be prevented from being completely embedded in the covering material. In such a state, when the optical fiber cable is cut at the notch and the core wire is taken out, all the core wires can be easily taken out without stretching or bending the cut covering.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a view showing an extrusion coating facility used in the method of manufacturing an optical fiber according to the present invention, FIG. 1 (A) is a view showing a schematic configuration of a coating portion of the extrusion coating facility, and FIG. It is a figure which shows the principal part of A). In FIG. 1, 1 is a core wire (optical fiber core wire), 2 is a support wire, 3 is a tensile body, 11 is a crosshead, 12 is a nipple, 13 is a die, 14 is a pipe, 15 is a nipple holder, and 16 is a nipple. A holder mounting plate, 17 is a bolt for fixing the nipple holder mounting plate, and 18 is a nut. In addition, the coating equipment of this example is applied to manufacture of a drop cable, and when manufacturing an indoor cable, the support wire 2 becomes unnecessary.

The crosshead 11 is connected to a cylinder of an extruder (not shown). Then, the coating material made of plastic resin melted by the extruder is fed into the crosshead 11 by the action of the screw in the cylinder. A die 13 is attached to the tip of the cross head 11, and a nipple 12 is disposed inside the die 13.
The nipple 12 is provided with an insertion hole (not shown) for inserting the core wire 1, the support wire 2, and the strength member 3. The core wire 1, the support wire 2, and the strength member 3 enter the cross head 11 from the upstream side (the right side in FIG. 1) of the cross head 11 and are positioned by the insertion holes of the nipple 12.

  The coating material fed from the extruder to the crosshead 11 flows through the gap between the nipple 12 and the die 13 and enters the die 13, and the core wire 1 and the support wire 2 that have passed through the insertion hole of the nipple 12. , And the periphery of the strength member 3 is discharged from the outlet of the die 13.

  A pipe 14 extending the insertion hole is provided on the outlet side of the insertion hole through which the optical fiber core wire 1 is inserted among the insertion holes of the nipple 12. By the action of the pipe 14, the coating material is covered with the parallel land portion L of the die 13 with respect to the core wire 1.

  In this configuration, the traveling direction of the linear body such as the core wire 1, the support wire 2, and the strength member 3 is M. For the traveling direction M, the distance between the outlet side tip p of the die 13 and the tip r of the pipe 14 is L1, and the distance between the nipple side end q of the parallel land portion L and the insertion hole outlet s of the nipple 12 is L2. To do. The distance between the tip r of the pipe 14 and the nipple side end q of the parallel land portion L is L3.

  The nipple 12 is held by a nipple holder 15 attached from the upstream side of the cross head 11. The nipple holder 15 is fixed to the cross head 11 by a nipple holder mounting plate 16 provided on the upstream rear side. The nipple holder mounting plate 16 is fixed to the cross head 11 with bolts 17.

A nut 18 is attached to the bolt 17 that fixes the nipple holder mounting plate 16 to the cross head 11 so as to sandwich the nipple holder mounting plate 16. By adjusting the nut 18, the distance L2 of the flow path formed between the nipple 12 and the die 13 can be adjusted.
When the nipple 12 is moved to the outlet side (downstream side) of the die 13, the distance L <b> 1 is reduced, and as a result, the coating material bites into the core wire 1 and the coating material is filled between the core wires 1. Can not make a hollow part.

FIG. 2 is a diagram for explaining a state in which the coating material bites into the core wire. The biting state of the coating material of the body jacket 4 with respect to the core wire 1 can be measured and quantified by observing the cross section of the manufactured optical fiber cable.
Here, in the core wires 1 arranged adjacent to each other, the radius of the optical fiber core wire is H1. Further, when the direction perpendicular to the straight line n connecting the centers of the adjacent optical fiber cores 1 is defined as the height direction, the coating material of the main body jacket 4 that has penetrated most between the optical fiber cores 1 in the height direction. The distance between the tip position t and the apex u in the height direction of the core wire 1 is H2. The biting degree of the coating material can be expressed by the ratio of H1 and H2 (H2 / H1).

  As shown in FIG. 3, when covering three or more core wires 1, the average value of H2 / H1 between the adjacent core wires 1 is calculated, and the average value is used as the biting degree of the covering material. . Such an evaluation based on the average value can be applied to a configuration in which the cores 1 are bundled in a circular shape as shown in FIG. 3, and is also applied to a configuration in which a plurality of cores 1 are arranged in a tape shape. can do.

(Example)
Using the manufacturing equipment shown in FIG. 1, an optical fiber cable is manufactured by changing the distance L1 between the tip r of the pipe 14 provided in the nipple 12 and the outlet side tip p of the die 13. The degree of biting was evaluated.
The manufactured optical fiber cable was a drop cable as shown in FIG. The notch 5 of the drop cable is provided so as to be opposed at two places on both sides of the main body jacket 4 so that the line connecting the tips of the notch 5 and the line connecting the two strength members 3 are orthogonal to each other. Has been.

The drop cable was made of the following specifications.
Core 1: 0.5 mmφ optical fiber × 8 Support wire 2: 2.3 mm φ steel wire Tensile body 3: 0.4 mmφ steel wire × 2 Cable height: 7.5 mm
Cable thickness: 3.3 mm
Coating material: L-LDPE (NUCG-9121, manufactured by Nihon Unica)

FIG. 4 is a diagram showing a list of evaluation results of prototype samples.
The distance L1 was changed from 0 to 3 mm, and nine types of samples having a value of H2 / H1 of 0 to 0.70 were produced. For each sample, the maximum protruding length of the core wire and how many core wires were buried in the coating material were evaluated, and the optimum value of H2 / H1 was obtained.
For the evaluation of the maximum protruding length of the core wire, after winding the manufactured optical fiber cable 100m on a metal reel having a body diameter of 280 mm and performing a heat cycle test at -40 ° C to + 70 ° C in a thermostatic chamber, the end portion of the cable The maximum protrusion length of the eight core wires was measured.
In addition, for the evaluation of the filling of the core wire with respect to the covering material, five 3 m cables are prepared for each condition, the notch is cut off at the end of each cable, and how many of the eight core wires are inside the covering material. Observed whether it was buried.

As a result, as shown in FIG. 4, when the biting degree H2 / H1 of the coating material becomes smaller than 0.10, the restraining force of the core wire by the coating material becomes small, and the core wire can move freely inside the cable. Thus, the maximum overhang length is outside the allowable range.
On the other hand, if the encroachment degree H2 / H1 of the coating material becomes larger than 0.50, the constraint of the core wire by the coating material becomes too large, and the core wire into the coating material is taken when the core wire is taken out by cutting at the notch portion. Occurs.
Therefore, the biting degree H2 / H1 of the coating is preferably in the range of 0.10 to 0.50. In order to realize this, the tip r of the pipe 14 provided on the nipple 12 and the outlet side of the die 13 are provided. It has been found that the distance L1 with the tip p needs to be 1.0 to 2.5 mm.

  If the distance L2 between the nipple side tip q of the parallel land portion L and the insertion hole outlet s of the nipple 12 is smaller than 1.0 mm, the flow path of the coating material becomes narrow and the pressure rises, resulting in mechanical deterioration of the crosshead component. Is promoted. If the distance L2 is greater than 4.5 mm, the flow stabilizing effect by the nipple 12 is reduced, and the cable shape becomes unstable. Therefore, in this sample production, the distance L2 was set within a range of 1.0 mm to 4.5 mm.

  Moreover, the resin pressure at the time of said sample manufacture was 11.0-21.0 Mpa, and the resin temperature was the range of 170-190 degreeC. If the resin pressure is too low, the molten coating material does not spread over the entire flow path at the die outlet, and a uniform shaped cable cannot be obtained. On the other hand, if the resin pressure is too high, mechanical deterioration of the components of the crosshead is promoted. On the other hand, if the resin temperature is too high, the flowability of the resin after passing through the die is so high that a cable with a uniform shape cannot be obtained by dripping vertically downward. On the other hand, if the resin temperature is too low, the fluidity of the resin is lowered, and the coating surface becomes rough.

With the above conditions, the degree of adhesion between the core of the optical fiber cable and the coating material can be optimized, and the core can be prevented from being completely embedded in the coating material.
Note that the drop cable and the indoor cable to which the present invention is applied usually have a main body portion that does not include the support wire 2 having a size of 5 mm or less. In such a small-sized cable, the dimensions are different from those in the above embodiments. Even so, the optimum manufacturing conditions described above can be applied.

It is a figure which shows an example of the extrusion coating equipment used for the manufacturing method of the optical fiber by this invention. It is a figure for demonstrating the biting state of the coating material with respect to a core wire. It is a figure for demonstrating the biting state of the coating | covering material with respect to a core wire when covering 3 or more core wires. It is a figure which lists and shows the evaluation result of the sample prototyped by the Example in connection with this invention. It is a figure which shows the structural example of the conventional drop cable which can apply this invention. It is a figure for demonstrating the problem at the time of the tearing of the notch part in the conventional drop cable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical fiber core wire, 2 ... Support line, 3 ... Strength body, 4 ... Main part outer cover, 5 ... Notch, 6 ... Support line part outer cover, 7 ... Main body part, 8 ... Support line part, 9 ... Neck part , 11 ... cross head, 12 ... nipple, 13 ... die, 14 ... pipe, 15 ... nipple holder, 16 ... nipple holder mounting plate, 17 ... bolt, 18 ... nut.

Claims (4)

A plurality of optical fiber cores and strength members are extruded and supplied to the crosshead, and the optical fiber core wires and the strength members are collectively coated using a coating material to form a jacket, and light is applied during the batch coating. In the method of manufacturing an optical fiber cable in which a notch for taking out a fiber core wire is formed in the jacket,
As the extrusion crosshead,
A nipple provided with a plurality of insertion holes through which the optical fiber core wire and the tensile body are respectively inserted, and provided with a pipe that extends only the insertion hole through which the optical fiber core wire is inserted to the outlet side;
Using a cross head comprising the optical fiber core wire that has passed through the insertion hole of the nipple and a die that preliminarily coats the coating material on the tensile body to define the shape of the jacket,
Set so that the tip of the pipe is located in the parallel land portion provided in the die,
The distance between the tip of the pipe and the tip on the outlet side of the die is L1,
When the distance between the outlet of the insertion hole of the nipple and the end of the parallel land portion on the nipple side is L2,
L1 = 1.0-2.5mm
L2 = 1.0-4.5mm
A method for manufacturing an optical fiber cable, characterized in that: In the optical fiber cable, two tensile bodies are arranged in parallel on both sides of the plurality of optical fiber core wires,
The notches are provided so as to be opposed to each other at two locations on both sides of the jacket, and are configured such that a line connecting the notch tips and a line connecting the two tensile bodies are orthogonal to each other. The method of manufacturing an optical fiber cable according to claim 1. In an optical fiber cable having a plurality of optical fiber cores and a jacket coated around the optical fiber core wires,
The direction perpendicular to the straight line connecting the centers of the adjacent optical fiber cores is the height direction,
The radius of the optical fiber core wire is H1,
When the distance between the tip position in the height direction of the jacket that bites between the adjacent optical fiber cores and the apex in the height direction of the optical fiber core wire is H2,
H2 / H1 is in the range of 0.10 to 0.50. In the optical fiber cable, two strength members are arranged in parallel on both sides of the plurality of optical fiber core wires,
The notches are provided so as to be opposed to each other at two locations on both sides of the jacket, and are configured such that a line connecting the notch tips and a line connecting the two tensile bodies are orthogonal to each other. The optical fiber cable according to claim 3.

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