JP2506111B2 - Optical fiber cable manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an optical fiber cable having an extra length and accommodating an optical fiber element wire or a core wire, and in particular, a cable manufacturing process. In, between the feeding device of the strength member and the traction device of the optical fiber cable,
Tension, that is, back tension, is applied to the tensile strength member in the direction of the feeding device, and the elongation strain responsible for the extra length given to the optical fiber or the core wire is given to the cable in advance, and the cable is taken up by the winding device. The present invention relates to a manufacturing method of giving an extra length to an optical fiber element wire or a core wire in a cable by releasing extension strain of the cable when winding the wire.

[Prior Art] An example of the structure of an optical fiber cable applied to the manufacturing method of the present invention is shown in FIGS. Where 1
Is an optical fiber element wire or core wire, and 2 is an optical fiber unit formed by assembling a plurality of optical fiber element wires or core wires 1. 3 is a strength member, and 4 is a cable jacket, and the strength member 3 is embedded in the cable jacket 4. Reference numeral 5 denotes a pipe-shaped space formed inside the cable jacket 4, and the optical fiber unit 2 is arranged in this space 5. A slot rod 6 has a large number of slots 7 formed on its outer peripheral surface, and the optical fiber unit 2 is arranged in these slots 7.

In the example of FIG. 3 (a), the optical fiber element wire, the core wire 1 or the optical fiber unit 2 is accommodated in the space 5 with a degree of freedom, and the cable jacket 4 together with the tensile strength body 3 is accommodated around it. It is coated.

In the example of FIG. 3B, the optical fiber element wire, the core wire 1 or the optical fiber unit 2 is accommodated in each slot 7 of the slot rod 6 with a degree of freedom, and the outer circumference of the slot rod 6 is covered with a cable jacket. 4 is coated.

A feature of these cables is that there is a space 5 in the cable around the optical fiber strand or core 1 or the optical fiber unit 2 in which they can move.
Therefore, even if a lateral pressure is applied to the cable, the optical fiber strand or the core wire 1 or the optical fiber unit 2 in the cable is
It has a structure that pressure is not applied directly to.

Furthermore, by giving an appropriate extra length to the optical fiber elemental wire, the core wire 1 or the optical fiber unit 2 in the cable, the cable may be laid or bridged by tension or temperature change in the cable longitudinal direction applied to the cable. Even if the cable extends, the optical fiber or core wire in the cable 1
Alternatively, the optical fiber unit 2 is only extended by the extra length, and the optical fiber does not have extension strain.

As described above, the optical fiber cable shown in FIG. 3A or 3B has a structure that suppresses the influence of mechanical force from the outside acting on the optical fiber. In the case of such a cable structure, even when the space 5 existing around the optical fiber element wire or the core wire 1 or the optical fiber unit 2 is filled with a jelly-like substance used as a waterproof material, a similar effect is obtained. Have

However, even with an optical fiber cable having such a structure, unless an appropriate extra length is given to the optical fiber accommodated in the cable, the above-mentioned mechanical force from the outside acts on the optical fiber, and This causes elongation strain to occur, which shortens the life, that is, the time from when the cable is formed to when it breaks.

FIG. 4 shows a conventional manufacturing method for manufacturing an optical fiber cable as shown in FIG. 3 (a) or (b).
Here, 8 is a feeding device for the optical fiber strand or the core wire 1 (or an optical fiber unit 2 in which the optical fiber strand or the core wire is assembled), 9 is a tensile strength body feeding device for feeding the tensile strength body 3, and 10 is a feeding means for these. It is an assembling die for assembling the optical fiber elemental wire or the core wire 1 or the optical fiber unit 2 and the strength member 3 fed from the devices 8 and 9. Reference numeral 11 is a plastic extruder, and 12 is a crosshead of the extruder 11, and a cable jacket made of plastic is extruded around the assembly assembled by the assembly die 10. Reference numeral 13 is an optical fiber cable thus obtained from the extruder 11. Reference numeral 14 is a cooling device for the optical fiber cable 13. Reference numeral 15 is a pulling device for the optical fiber cable that has passed through the cooling device 14, and 16 and 16 'are pulling tracks of the pulling device 15. Reference numeral 17 is a device for winding the optical fiber from the pulling device 15, and 18 is a winding drum thereof.

To manufacture the optical fiber cable of FIG. 3 (a) by using the manufacturing apparatus of FIG. 4, the optical fiber element wire or the core wire 1 (or the optical fiber unit 2 in which the optical fiber element wire or the core wire is assembled is used. ) Is fed from the feeding device 8 and the strength member 3 is fed from the strength member feeding device 9, and both are gathered by a gathering die 10. When the optical fiber strand or the core wire 1 (or the optical fiber unit 2 in which the optical fiber strand or the core wire is assembled) assembled together with the strength member 3 passes through the extruder 12, at the crosshead 12 of the extruder 11, An optical fiber cable 13 is formed by extruding and covering a cable jacket 4 including a tensile strength member 3 while forming a space 5 on the outer circumference of the optical fiber element wire, the core wire 1 or the optical fiber unit 2. The optical fiber cable 13 passes through a cooling device 14 such as a water tank, and the extrusion-coated cable jacket 4 is cooled and solidified. The optical fiber cable 13 is pulled while being sandwiched between the pulling caterpillars 16 and 16 ′ of the pulling device 15, is sent to the winding device 17, and is wound around the winding drum 18.

[Problems to be Solved by the Invention] In such a conventional manufacturing method, the optical fiber strand or the core wire 1 (or the optical fiber unit 2 in which the optical fiber strand or the core wire is assembled) is usually manufactured. The back tension T _f (with the feeding device 8 in the direction of the feeding device 8 so as not to cause slack)
Or, since the tension applied to the optical fiber unit 2 is applied, the extra length of the optical fiber element wire, the core wire 1 or the optical fiber unit 2 is not provided in the optical fiber cable 13. On the contrary, due to the back tension T _f , the optical fiber or the optical fiber 1 or the optical fiber unit 2
There is a problem that the elongation strain generated in the cable remains after the cable is made. Therefore, in the conventional manufacturing process, a method of pushing the optical fiber elemental wire, the core wire 1 or the optical fiber unit 2 into the space 5 before the extruder 11 has been considered, but it is difficult in practice, It was impossible to give a proper length.

In manufacturing the optical fiber cable of FIG. 3 (b) with the manufacturing apparatus shown in FIG. 4, the slot rod 6 including the tensile strength member feeding device 9 to the tensile strength member 3 and having the slot 7 spirally provided in the longitudinal direction. Take out. However, also in this case, as in the case of FIG. 3A, it was difficult to give the required extra length to the optical fiber element wire, the core wire 1 or the optical fiber unit 2.

As described above, it is difficult for the conventional manufacturing method to give an extra length to the optical fiber element wire, the core wire, or the optical fiber unit accommodated in the cable. Therefore, the elongation strain of the optical fiber is relaxed to increase the loss. It was not possible to sufficiently suppress the shortening of the breaking life.

Therefore, an object of the present invention is to provide an optical fiber element or core wire in the cable, or an optical fiber cable having a space in which the optical fiber unit can move relatively freely. Alternatively, it is an object of the present invention to provide a manufacturing method for manufacturing an optical fiber cable that can accurately add a required extra length to an optical fiber unit and can suppress elongation strain of the optical fiber when the cable is used.

[Means for Solving the Problems] In order to achieve such an object, the present invention provides a slot rod including an optical fiber element wire or a core wire or an optical fiber unit and a strength member or a strength member, respectively. It is fed from the device and supplied to the extruder, and the optical fiber cable is formed by extruding and covering the cable jacket while forming a space having an inner dimension larger than the outer diameter of the optical fiber element wire, core wire or optical fiber unit on the outer circumference. And then the optical fiber cable is cooled by a cooling device, the cooled optical fiber cable is pulled by a pulling device, and then the optical fiber cable is wound by a winding drum installed in a winding device. In the manufacturing method for manufacturing, in the feeding device of the optical fiber elemental wire, the core wire or the optical fiber unit, Ε _{f is} the elongation strain generated in the optical fiber strand, core wire, or optical fiber unit due to the tension applied to the optical fiber strand, core wire, or optical fiber unit in the direction of the feeding device, and is the optical fiber cable taken out from the extruder. Ε _{s is} the contraction rate of contraction in the cooling device in the longitudinal direction, and the extra length ratio [{(optical fiber is Length of optical fiber strand, core wire or optical fiber unit in cable)-(length of optical fiber cable)} / (length of optical fiber cable)]
Where ε _m is the elongation strain ε _{t such} that ε _t = ε _m + ε _f + ε _s
Is applied to the strength member, tension is applied to the strength member between the strength member feeding device and the traction device in the direction of the strength member feeding device.

[Operation] In the optical fiber cable manufacturing method of the present invention, in the optical fiber cable manufacturing process, tension (back force) is applied to the strength member between the strength member feeding device and the optical fiber cable pulling device in the direction of the strength device. (Tension) is added to the cable in advance to provide a strain equivalent to the excess length applied to the optical fiber strand, core wire or optical fiber unit, and when the cable is wound by the winding device, the strain By opening the cable, a required extra length is accurately provided to the optical fiber strand, the core wire, or the optical fiber unit in the cable. In the conventional method for manufacturing an optical fiber cable, an arbitrary tension is not applied to the strength member between the feeding device for the strength member and the pulling device for the optical fiber cable.

As described above, according to the present invention, it is possible to manufacture the optical fiber cable by accurately providing the required extra length to the optical fiber accommodated in the optical fiber cable.
As a result, the loss variation during actual use of the cable is less than the allowable value, and the reliability such as the breaking life of the optical fiber can be sufficiently ensured.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory view of a first embodiment of a method for manufacturing an optical fiber case according to the present invention.

Here, the optical fiber element wire or the core wire 1 (or the optical fiber element wire or the core wire 1) fed out while being applied with the back tensions T _f and T _t from the feeding device 8 and the tensile strength member feeding device 9, respectively. The optical fiber unit 2) and the strength member 3 passed through the assembly die 10 are arranged with respect to the cable structure.

The assembly formed by passing through the assembly die 10 then passes through an extruder 11 that extrudes a plastic such as polyethylene or polyvinyl chloride. At this time the extruder crosshead
A cable jacket 4 having a space 5 shown in FIG. 3A is extruded and formed by the nipple and the die attached to 12. The optical fiber cable 13 thus formed is passed through the cooling device 14 to be cooled, and the cable jacket 4 softened at a high temperature is solidified. Generally, a water tank is used as the cooling device 14. The optical fiber cable 13 that has passed through the cooling device 14 is a caterpillar for towing of the towing device 15.
It is sandwiched between 16 and 16 ', and is pulled toward the winding device 17 by the rotation of the pulling character pillars 16 and 16', and is wound around the winding drum 18.

Up to this point, the manufacturing method is the same as the conventional manufacturing method, and a conventional manufacturing apparatus can be applied. However, in the present invention, the tensile strength member feeding device 9 and the pulling device 15 for the optical fiber cable 13 are used.
Back tension T _t to the tension member 3 between
An extension strain corresponding to the extra length given to the optical fiber strand, the core wire 1 or the optical fiber unit 2 is given to the optical fiber cable 13 in advance, and after the optical fiber cable 13 has passed through the pulling device 15, the optical fiber cable By releasing the tension of the optical fiber cable 13, the elongation of the optical fiber cable 13 is made zero, so that the required extra length is accurately given to the optical fiber element wire, the core wire 1 or the optical fiber unit 2 in the optical phenyl cable 13. .

The method of designing the back tension applied to the strength member 3 will be described below.

In FIG. 1, in the feeding device 8 of the optical fiber elemental wire, the optical fiber 1 or the optical fiber unit 2, when the back tension applied to the optical fiber elemental wire, the optical fiber 1 or the optical fiber unit 2 is T _f , the optical fiber element Strain ε _f of the optical fiber or core wire 1 or the optical fiber unit 2
Is given by

ε _f = T _f / (ΣA _i E _i ) (1) Here, A and E respectively represent the cross-sectional area and Young's modulus of the constituent material of the optical fiber element wire or the core wire 1 or the optical fiber unit 2, The subscript i represents each constituent material.

The elongation strain ε _t of the optical fiber cable (13) caused by the back tension T _t applied to the strength member 3 is similarly given by the following equation.

ε _t = T _t / (ΣA _j E _j ) (2) Here, the subscript j is the optical fiber strand or core wire 1 or the optical fiber unit 2 and the optical fiber cable 13 excluding the plastic extruded from the extruder 11. Represents each constituent material.

Next, the optical fiber cable 13 coming out of the extruder 11
When the optical fiber cable 13 is cooled by the cooling device 14, the optical fiber cable 13 generally has a contracting force T _{s in the} longitudinal direction of the cable due to the nature of the constituent material thereof, and therefore, the optical fiber cable 13 receives light between the tension member feeding device 9 and the pulling device 15. The tension _Tc acting on the fiber cable 13 can be expressed by the following equation.

Elongation strain epsilon _c in _{T c = T t -T s (} 3) optical fiber cable 13 according to the tension T _c is given by the following equation.

elongation strain epsilon _c of _{ε c = T c / (ΣA} j E j) (4) Equation (4) optical fiber cable 13 given in, after the optical fiber cable 13 passes through the traction device 15, an optical fiber cable Tension applied to 13 T _t
Is released and returns to zero.

Here, since the optical fiber element wire or the core wire 1 or the optical fiber unit 2 is accommodated in the optical fiber cable 13 with a degree of freedom, the extension strain of the optical fiber cable 13 after passing through the pulling device 15 When it returns to zero, that is, when the elongation strain of the cable outer box 4, the tensile strength member 3 or the slot rod 6 including the tensile strength member 3 returns to zero, the optical fiber element wire or the core wire 1 in the optical fiber cable 13 or The optical fiber unit 2 is given an extra length corresponding to the elongation strain ε _c .

In this case, since the elongation strain ε _f given by the equation (1) is already generated in the optical fiber element wire, the core wire 1 or the optical fiber unit 2 by the back tension T _f , the optical fiber cable 13 is connected to the pulling device 15. After passing, the excess length of the optical fiber element wire, the core wire 1 or the optical fiber unit 2 is actually reduced by such an amount of ε _f , and finally the optical fiber element wire, the core wire 1 or the optical fiber unit 2 is finally obtained. 2 has a surplus length ε _m , that is, {(optical fiber strand or core wire 1 or optical fiber unit 2 in the optical fiber cable 13) − (length of the optical fiber cable 13)} / (of the optical fiber cable 13 The length) can be expressed by the following equation.

When shrinkage caused by _{ε m = ε c -ε f (} 5) T s and ε _s, ε _s is given by the following equation.

ε _s = T _s / (ΣA _j E _j ) (6) This elongation strain ε _s depends on the plastic resin temperature in the extruder 11.

Therefore, the elongation strain ε _t generated in the tensile strength body 3 in the tensile strength body feeding device 9 is given by the following equation from the equations (1) to (6).

[epsilon] _t = [epsilon] _m + [epsilon] _f + [epsilon] _s (7) [epsilon] _f is the back tension applied to the optical fiber strand, the core wire 1 or the optical fiber unit 2 in the feeding device 8 of the optical fiber strand or the core wire 1 or the optical fiber unit 2. It depends on the control of T _f .

Therefore, by designing the finally required extra length ratio ε _m , the elongation strain ε _t to be generated in the tensile strength body 3 can be easily determined.

In this case, it is necessary to set ε _t , that is, T _t in consideration of unavoidable fluctuations with respect to set values such as the back tension T _t in the tensile strength member feeding device 9 and the plastic resin temperature in the extruder 11. Considering such variations, it is appropriate to set T _t within a range of ± 10% of the value determined by the equation (7).

When an optical fiber cable is manufactured under the conditions determined in this way, the optical fiber inside the cable is provided with a surplus length that can ensure the reliability required when the cable is actually used. It is possible to realize an optical fiber cable in which the loss fluctuation is equal to or less than the allowable value and the breaking life of the optical fiber is sufficiently long.

FIG. 2 shows a second method of manufacturing an optical fiber cable according to the present invention.
FIG. 3 is an explanatory diagram of an example of FIG. In the apparatus shown in the first figure, the towing device 15 is composed of the towing caterpillar 16, whereas in the present example, the towing device 15 is composed of the towing drum 19. Also in this case, as described with reference to FIG. 1, the back tension T _t is applied to the strength member 3 between the strength member feeding device 9 and the towing drum 19. Here, the back tension T applied to the strength member 3 using the formula (7)
_{If t} is designed, the optical fiber inside the optical fiber cable 13 will be provided with a surplus length that can secure the reliability required during actual use of the cable, and the loss fluctuation during actual use of the cable will not exceed the allowable value. Moreover, it is possible to realize an optical fiber cable having a sufficiently long breaking life of the optical fiber.

[Effects of the Invention] As is clear from the above, according to the present invention, it is possible to manufacture an optical fiber cable by accurately providing a required extra length to the optical fiber accommodated in the optical fiber cable. . As a result, the loss variation during actual use of the cable is less than the allowable value, and the reliability such as the breaking life of the optical fiber can be sufficiently ensured.

[Brief description of drawings]

FIG. 1 is an explanatory view of a first embodiment of a method for manufacturing an optical fiber cable of the present invention, FIG. 2 is an explanatory view of a second embodiment of a method of manufacturing an optical fiber cable of the present invention, and FIG. 3 (a). And (b) are cross-sectional views showing two examples of the structure of an ordinary optical fiber cable, and FIG. 4 is an explanatory view of a conventional optical fiber cable manufacturing method. 1 ... Optical fiber strand or core wire, 2 ... Optical fiber unit, 3 ... Tensile member, 4 ... Cable jacket, 5 ...
Space, 6 ... Slot rod, 7 ... Slot, 8 ...
Optical fiber feeding device, 9 ... Tensile force member feeding device, 10
...... Assembly die, 11 …… Extruder, 12 …… Extruder crosshead, 13 …… Optical fiber cable, 14 …… Cooling device, 15 …… Drawer, 16,16 ′ …… Crawler for pulling, 1
7 ... Winding device, 18 ... Winding drum, 19 ... Towing drum.

Claims (1)

(57) [Claims] 1. An optical fiber strand, a core wire, an optical fiber unit, and a strength member or a slot rod containing a strength member are respectively fed from a feeding device and fed to an extruder, and the optical fiber strand or the core wire or On the outer circumference of the optical fiber unit, while forming a space having an inner dimension larger than its outer diameter, the cable jacket is extruded and coated to form an optical fiber cable, and then the optical fiber cable is cooled by a cooling device. In the manufacturing method for manufacturing an optical fiber cable by pulling a cooled optical fiber cable by a pulling device and then winding the optical fiber cable on a winding drum installed in a winding device, the optical fiber element wire, core wire or optical fiber unit In the feeding device of the above, the optical fiber strand, the core wire or the optical fiber unit is In the longitudinal direction in the optical fiber or cord or elongation distortion of the optical fiber unit epsilon _f, wherein the optical fiber cable has been removed from the extruder and the cooling device by the tension in the direction of the feeding device to be added to The contraction rate for contraction is ε _s , and the extra length ratio [{(in the optical fiber cable) that the optical fiber element wire, the core wire, or the optical fiber unit has when the optical fiber cable is wound on the winding drum. optical fiber or cord or length of the optical fiber unit) - (length of the optical fiber cable)} ÷ (length of said optical fiber cable) when the ε _m, ε _t =
In order to generate elongation strain ε _{t of} ε _m + ε _f + ε _{s in the} strength member, tension is applied to the strength member between the strength member feeding device and the traction device in the direction of the strength member feeding device. A method for manufacturing an optical fiber cable, which is characterized by adding.