JPH01196010A - Manufacture of optical fiber cable - Google Patents

Abstract

PURPOSE:To stabilize back tension applied to a plastic wire body to be put in an excessive length giving device and to obtain accurate excessive length by providing the excessive length giving device on the right downstream side of a gathering die. CONSTITUTION:The plastic wire body 2 which has an optical fiber 1 put in its groove 3 is wound around the excessive length control drum 31 of an excessive-length controller 3 as it is. Consequently, the optical fiber 1 is put on the bottom surface 3a of the groove while extended and thus given excessive length. The distance between a payoff device 11 which applies the back tension of the optical fiber 1 and the excessive length controller 30 which gives the excessive length is short, so the back tension is not affected even if the coefficient between friction between the optical fiber 1 being manufactured and the plastic wire body; 2 varies. Consequently, the excessive length is easily controlled by the diameter of the excessive control drum 31 and the payoff device 11 which applies the back tension to the optical fiber 1.

Description

[Detailed Description of the Invention] <Industrial Utilization> The present invention relates to a method for manufacturing an optical fiber cable that accommodates a coated optical fiber that has been given an extra length. It has been devised so that it can be given well.

<Prior Art> An example of a conventionally manufactured optical fiber cable is shown in FIG. FIG. 4 is a sectional view of the optical fiber cable disclosed in Japanese Patent Application No. 10148/1982. As shown in the figure, an optical fiber 1 (hereinafter referred to as coated optical fiber and/or coated optical fiber unit) consists of a coated optical fiber in which an optical fiber is coated with plastic or a coated optical fiber unit that is a collection of coated optical fibers. The optical fiber (simply referred to as an optical fiber) is housed in a groove 3 formed linearly in the longitudinal direction on the outer periphery of a plastic filament 2 made of polyethylene or the like, and the plastic filament 2 is eccentric from its center. Two tensile strength members 4 having a high Young's modulus made of N4 wire 2 reinforced plastic or the like are provided at the positions. Here, the optical fiber 1 is housed loosely in the groove 3, that is, with an extra length given to the length of the plastic linear body 2, and in order to protect the optical fiber 1, the plastic The outer periphery of the linear body 2 is covered with a pressure tape 5 made of a metal such as aluminum or steel or a material such as paper, rubber, or polyester, and a cable sheath 6 made of polyethylene, polyvinyl chloride, or the like. In this cable, the groove 3 is formed in a straight line without twisting, and there is no need for a twisting process when manufacturing the cable. ! The manufacturing process is simplified,
Manufacturing speed can be improved.

In such a cable, if you want to give extra length to the optical fiber 1, change the positions of Fn3 and tensile strength member 4! Q1′!
The neutral plane of cable bending (the plane where the cable does not expand or contract in the longitudinal direction when bending the cable)
By utilizing the fact that the position of N can be arbitrarily set, the optical fiber 1 is accommodated while giving an appropriate elongation to the bottom surface 3a of the groove 3. That is, by arranging the bottom surface 3a of the groove 3 on the outside of the cable bending and winding the bottom surface 3a on a drum during cable manufacturing so that the bottom surface 3a is located outside the neutral plane N, the bottom surface 3a can be easily removed. The optical fiber 1 is given ζ elongation, and the optical fiber 1 is accommodated in this state. As a result, when extending the cable, the bottom surface 3 of the groove 3
Since a returns to its original state without elongation, the optical fiber 1 has an extra length within the groove 3. Note that this extra length is determined by the cable structure and the diameter of the winding drum, so it can be controlled to the required extra length, and the optical fiber 1 can be pulled in, pushed out, and distorted when the cable is stretched or bent. be able to suppress the occurrence of

In such an optical fiber cable, the bending rigidity of the cable can be minimized in a specific bending direction (for example, in a bending direction with the opening of the groove 3 on the outside) depending on the dimensions and positions in the cross section of the groove 3 and the tensile strength member 4. At the same time, the bending neutral plane N of the optical fiber 1 in that specific bending direction is
Can be set closer to the inside of the cable bend (M
, Kawase et at, , ``Enter New o
optical fiber cable design
+, Firststop electronics c
onference (OEC'86) Technic
al Digest, pp, 102-103.19
86).

Therefore, when the bending direction in which the opening of the WI 3 is placed on the outside is set as the specific bending direction, bending in that bending direction stretches the bottom surface 3a of the groove 3, and the elongation is approximately proportional to the bending curvature.

Next, we will explain the outline of the manufacturing process of optical cables as described above in Section 5.
As shown in the figure (see Japanese Patent Application No. 62-101817). As shown in the figure, an optical fiber 1 is fed out from an optical fiber feeding device 11 while applying pack tension, and a groove 3 of a plastic linear body 2 is fed out from a plastic linear body feeding device 12 while being applied pack tension. The assembled dice 13 are accommodated in the inside. The plastic cotton body 2 containing the optical fiber 1 is wrapped around its outer periphery by a press winding device 14, and a press winding tape feeding device 1
The presser winding tape 5 fed out from the tape 5 is wound to form a cable core 16, and an outer sheath is applied by an extruder 18 having a fourth head 17 to form the optical fiber cable 1.
It is considered to be 9. This optical fiber cable 19 is cooled by a cooling device 20 consisting of a water tank or the like in order to fix the jacket which has softened at high temperatures. Next, the traction device 21 is held and towed by a pair of belt-shaped rotary traveling bodies 22 for traction, and the intermediate winding device 23 is wound around the drum 24.
Thereafter, it is wound up on the winding drum 26 of the winding device 250.

Here, when the optical fiber cable 19 is wound around the drum 24, the bottom surface 3a of the groove 3 is stretched. At this time, if the optical fiber 1 is fed into the groove 3 with pack tension applied by the feeding device 11 to such an extent that no stretching strain occurs, and if the bending diameter is constant, then when the optical fiber cable 19 is stretched, The optical fiber 1 within the groove 3 has an extra length corresponding to the extension of the bottom surface 3a.

The distance from the inner bending m of the optical fiber cable 19 (the side opposite to the opening of the groove 3; see Figure 4) to the bending neutral plane N is d.
c. If the distance from the bending neutral plane N to the position where the optical fiber 1 is placed is 01 and the bending diameter of the weighting drum is 2r, then the surplus length ratio β given to the optical fiber 1 is given by the following equation.

β=C/(r+dc)...
・(1) Note that C and dc are the materials of the plastic linear body 2 (including the tensile strength body 4 and the groove 3) and the cable jacket 6,
It can be determined by the shape and dimensions (H, 5hi
nehara et at,, ``people newsimp
le optical cable + manu
factured in asingle pr
ocess', The transaction
s of the IECE of J person PAN
, Jol, , E69. No.4. April
(see 1986).

Another example of the optical fiber cable is shown in FIG. As shown in the figure, this optical fiber cable is a waterproof optical fiber cable, and soap is added in the groove 3 in order to prevent water from running inside the cable when water enters the cable due to scratches on the cable jacket 6, etc. It is filled with a waterproof material 7 made of a sherry-like mixture such as metal grease, or a fibrous material or powder material that has the effect of absorbing and forming a dam. In the case of manufacturing this optical fiber cable, in FIG. The process is carried out in the same manner except that the waterproof material 7 is filled inside.

Further, FIG. 7 shows an example of a self-supporting optical fiber cable. Generally, when a cable is strung across a utility pole, a method is used in which suspension wires made of galvanized steel strands or aluminum steel strands are installed in advance and the optical cable is fixed as shown in Figure 4 above. The self-supporting optical fiber cable shown in FIG. 7 is a cable in which a suspension wire and a cable are integrated in order to eliminate the step of installing the suspension wire. When manufacturing this cable, for example, as shown in FIG. 5, a collecting die is installed between the presser winding device 14 and the extruder 18, and the hanging wire 8 and the cable core 16 are aligned vertically by the collecting die. Then, an extruder 18 is used to form a cable jacket 6' that bundles the hanging wire 8 and the cable core 16 together.

<Problems to be Solved by the Invention> However, according to the conventional manufacturing method as described above, there is a problem in that it is difficult to control the pack tension to provide the required extra length. That is, in order to provide the required extra length, the pack tension required at the intermediate winding device 23 is fo, the pack tension at the feeding device 11 is f1, and the coefficient of friction between the optical fiber 1 and the plastic linear body 2 is μ, the distance between the collecting die 13 and the intermediate winding device 23 is L1, and the weight per unit length of the optical fiber 1 is W, then f0=f−μWL...(2
) However, since the friction coefficient μ is not constant during manufacturing, the pack tension applied to the optical fiber 1 becomes unstable in the intermediate winding just before the device 23, and there is a problem that the extra length cannot be precisely controlled. In addition, in the case of a waterproof optical fiber cable (see Fig. 6), the friction between the waterproof material 7 filled in the groove 3 and the optical fiber 1 becomes significantly large.
The problem is that the pack tension applied to the optical fiber 1 for the purpose of accurately imparting extra length is almost completely gone by the time the intermediate winding reaches the device 23, and the required extra length is not imparted. Even if an attempt is made to take the influence of the waterproofing material into consideration in the above-mentioned equation (1), it is difficult to control accurately because the degree of influence differs depending on the amount and viscosity of the waterproofing material filled. Note that if the required extra length is not provided, when the optical fiber cable is wound onto the winding drum 26, the optical fiber 1 will be subject to a large elongation strain, resulting in increased optical loss, breakage, or This is undesirable as it causes deterioration of reliability.

In addition, self-supporting fiber optic cable (see Figure 7)
In this case, due to the rigidity of the material of the suspension wire 8, the neutral plane N' is located at the upper side of the optical fiber 1 in the figure (the suspension wire 8) as shown in FIG.
side). Therefore, wrap the wire with the hanging wire 8 side outside.
When the optical fiber 1 is wound around the beam 24, compression occurs on the bottom surface 3a of the groove 3, so when the optical fiber 1 is stretched, the length of the optical fiber 1 becomes shorter than the cable length, and a tensile force is applied to the optical fiber 1, causing it to break or become unreliable. It is undesirable as it causes deterioration of sex.

In addition, in order to create a cable structure with extra length, it is necessary to increase the diameter of the tensile strength member 4 or move its position in the opposite direction to the suspension s8, but in either case, the length of the cable must be increased. The diameter becomes large, which is not desirable.

Further, due to the presence of the hanging wire portion, there is also the problem that it is difficult to always position the hanging wire s8 on the outside when winding the intermediate winding device 23 around the drum 24.

SUMMARY OF THE INVENTION In view of these circumstances, an object of the present invention is to provide a method for manufacturing an optical fiber cable that can accurately provide an extra length to the optical fiber to be accommodated.

Means for Solving the Problems> A method for manufacturing an optical fiber cable according to the present invention that achieves the above-mentioned object is to insert an optical fiber into a groove formed in the longitudinal direction of a plastic linear body having a tensile strength member using a collecting die. Or, when manufacturing an optical fiber cable by accommodating a coated optical fiber unit and forming an outer sheath using an extruder, the neutral plane of the cable bending is set at a position where the coated optical fiber or coated optical fiber unit is housed. The coated optical fiber or coated optical fiber unit is housed with the plastic linear body set inside or at the same position and bent in the bending direction by an extra length imparting device. In a method for manufacturing an optical fiber cable in which the optical fiber cable is accommodated in a state with no stretch or a state with extra length,
The method is characterized in that the extra length providing device is installed between the collecting die and the extruder to provide the extra length, and then the outer cover is formed.

Since the extra length adding device is provided immediately downstream of the collecting die, the pack tensilon applied to the plastic linear body entering the extra length adding device is stabilized, and extra length can be given with high accuracy.

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

FIG. 1 schematically shows a method for manufacturing an optical fiber cable according to a first embodiment of the invention for manufacturing the optical cable shown in FIG. Note that the same members as in FIG. 5 are given the same reference numerals, and redundant explanations will be omitted. In the figure, 30 is a surplus length control device as a surplus length giving device, 31 is a drum for surplus length control, and the fifth
The intermediate winding device 23 and the winding drum 24 in the figure have substantially the same functions.

In this embodiment, the optical fiber 1 and the plastic linear body 2 are fed out from the feeding device 11 and the plastic linear body feeding device 12 while being applied with back tension, respectively. Enter 30. That is, the optical fiber 1 is inserted into the groove 3.
The plastic linear body 2 containing the plastic wire body 2 is wound as it is around the surplus length control drum 31 of the surplus length control device 30. By accommodating the optical fiber 1 with the bottom surface 3a of the groove 3 stretched in this manner, the optical fiber 1 is given an extra length. Then, the optical fiber 1i with the extra length
e The housed plastic linear body 2 is wrapped with a pressure tape 5 and then covered with an outer sheath 6 as in the conventional case, and the winding device 25 winds it around a drum 26.

In this embodiment, since the distance between the unloading device 30 for applying pack tension to the optical fiber 1 and the extra length pushing device 30 for imparting an extra length is close, the pack tension for imparting the required extra length is close. Easy to control. That is, since L is small in the above equation (2), the extra length control device 30
The pack tension f applied to the optical fiber 1 just before it is fO:f...
(3) Therefore, even if the friction coefficient μ between the optical fiber 1 and the plastic linear body 2 changes during manufacturing, it does not affect the pack tension f0. Therefore, the extra length can be controlled by the diameter of the extra length control drum 31 and the feeding device 11 that applies pack tension to the optical fiber 1.

Further, according to this method, the mid-bending plane is determined by the groove 3 of the plastic cotton body 2 and the tensile strength member 4, so that the amount of extra length is not affected by the shape of the cable jacket 6.

In other words, even when the shape of the outer sheath 6 is made triangular or square in cross section, for example, the required extra length can be provided by simply changing the crosshead 17 of the extruder 18, and the position of the neutral plane can be changed. Therefore, there is no need to change the shape of the groove 3 or the tensile strength member 4.

FIG. 2 schematically shows a second embodiment of the present invention for manufacturing a waterproof optical fiber cable (see FIG. 6). In this embodiment, a waterproofing material filling device 32 is installed between an extra length control device 30 and a presser winding device 14 to fill the waterproofing material 7.
This is the same as the example of . In other words, since the extra length is given before filling the waterproofing material 7, the optical fiber 1
Friction between the waterproof material 7 and the waterproof material 7 does not affect extra length control. Therefore, the extra length can be controlled without considering the amount of waterproofing material 7 and the material quality such as viscosity.

In addition, if the extra length can be controlled accurately in this way, it is also possible to prevent the core wire from undulating within the groove 3 and increasing loss when the optical fiber cable is extended.

FIG. 3 schematically shows a third embodiment of the present invention for manufacturing a self-supporting optical fiber cable (see FIG. 7). 1
A hanging wire gathering die 33 is provided between the cable 5 and the cable wrapping tape 5, and the hanging wire 8 fed out from the hanging wire feeding device 34 is attached to the cable wrapped with the presser winding tape 5. The second embodiment is the same as the first embodiment except that .

That is, in this embodiment as well, the bending neutral plane in the extra length control device 30 is between the groove 3 of the plastic linear body 2 and the tensile strength body 4.
Since it is determined by .

<Effects of the Invention> As specifically explained above in conjunction with the embodiments, the method of the present invention allows the remaining length to be determined accurately regardless of the shape of the cable sheath of an optical fiber cable, and even when filled with waterproofing material, etc. Can be given well. This makes it possible to ensure reliability and losses such as breakage life when using the cable, and also suppresses residual strain in the drum-wound state immediately after the cable is manufactured, preventing optical fiber breakage and optical loss. can prevent an increase in

[Brief explanation of the drawing]

1 to 3 are explanatory diagrams showing the outline of the first to third embodiments according to the present invention, FIG. 4 is a sectional view showing an example of an optical fiber cable, and FIG. 5 is a conventional manufacturing method thereof. FIG. 6 is a cross-sectional view showing an example of a waterproof optical fiber cable, and FIG. 7 is a cross-sectional view schematically showing a self-supporting optical fiber cable. In the drawing, 1 is an optical fiber (coated optical fiber or coated optical fiber unit) 1, 2 is a plastic linear body 1, 3 is a groove, 4 is a tensile strength body, 5 is a pressure tape, 6 is a cable jacket, and 13 is a collection. 14 is a press winding device, 18 is an extruder, 20 is a cooling device, 21 is a pulling device, 25 is a winding device, 30 is a surplus length control device, and 31 is a drum for surplus length control. Patent applicant: Agent of Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] When producing an optical fiber cable by accommodating an optical fiber or a coated optical fiber unit in a groove formed in the longitudinal direction of a plastic linear body having a tensile strength body using a gathering die and forming an outer sheath using an extruder. , the neutral plane of the cable bending is set to the inner side of the cable bending or at the same position as the accommodation position of the coated optical fiber or coated optical fiber unit, and the plastic linear body is bent in the bending direction using an extra length adding device. In a method for manufacturing an optical fiber cable in which the coated optical fiber or coated optical fiber unit is housed in a given state and the coated optical fiber or coated optical fiber unit is housed in a state with no elongation or with an extra length, A method for manufacturing an optical fiber cable, characterized in that the above-mentioned outer jacket is formed after the extra length is provided by installing the above-mentioned extra length giving device between the above-mentioned collecting die and the above-mentioned extruder.