JP3386181B2 - Method for manufacturing high-density optical fiber cable - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a high-density optical fiber cable, and more particularly to a method for manufacturing a high-density optical fiber cable used on the subscriber side of a public communication line.

[0002]

2. Description of the Related Art Optical fiber cables are currently used as subscriber cables for public communications, and are expected to be further used as cables to be connected to homes in the future. It is said that an ultrahigh-density optical fiber cable, which is much higher in density than the current one, is required for use in such applications.

In such an ultra high density optical fiber cable, it is desirable to use a multifilament tape core wire arranged in a high density. For example, in Japanese Patent Laid-Open No. 143710/1992, a multifilamentary tape core wire is used. There is disclosed a slot provided with a spiral groove for accommodating and carrying a stepped shape.

By the way, when a tape core wire of this kind is used to form a cable, the cross-sectional area A of the concave groove for accommodating the tape core wire is used.
And the sectional area B of the slot body is A / (A + B)> 3
It is desirable to use a slot that gives 0%. At this time, the optimum slot shape is a rectangle (hereinafter referred to as a square groove).

Further, when a spiral twist is applied to the groove for accommodating the optical fiber, the tension applied to the optical fiber becomes uniform when the slot is bent, which is advantageous in that the transmission loss is small. Occurs. Such slots are used by gathering them in a densely twisted state around separately made tension members (tensile strength wires).
However, since the groove has a spiral shape, it can be used alone as an optical cable.

However, when manufacturing an optical fiber cable using such a slot, there were technical problems described below.

[0007]

That is, first, in the method of manufacturing the slot itself, in the slot disclosed in the above publication, extrusion molding of thermoplastic resin is generally adopted, but the slot is formed by simple extrusion molding. However, it was difficult to secure sufficient pitch precision of the spiral as well as insufficient dimensional precision of the square groove.

Further, when an optical fiber cable is manufactured by using the slot having such a structure, the tape core wire is housed in the groove after the slot is manufactured. When wound on a bobbin, the cross-sectional structure of the slot has a concave groove that opens to one end side, so the bending rigidity is very unbalanced, and it deforms in a direction that makes it easier to bend when winding and the spiral pitch There was a problem that fluctuated.

In order to avoid such a problem, for example, if the concave groove is divided into upper and lower parts and the slot is formed in a substantially H-shaped cross section, the imbalance in bending rigidity is considerably eliminated.
However, even in the slot having such a cross-sectional structure, the bending rigidity is slightly different in the vertical direction and the horizontal direction, and when the manufactured slot is wound on the bobbin, the twist tends to return in the most bendable direction, If it is stored for a long time, the spiral pitch will change slightly.

However, even such a slight fluctuation in the spiral pitch leads to a performance problem in the high-density optical fiber cable. That is, in an optical fiber cable that has been recently developed, for example, a 16-core optical fiber is covered with a silicon buffer layer and a photocurable resin, and the silicon buffer layer and the photocurable resin are used to cope with high density. Resin is very thin. Therefore, even a slight change in the spiral pitch causes microbending, which leads to an increase in transmission loss, which is a serious problem in performance.

The present invention has been made in view of the above problems, and an object thereof is to easily insert an optical fiber tape core wire and to change the pitch of the spiral groove even when wound. It is to provide a method for manufacturing a high-density optical fiber cable with less loss.

[0012]

In order to achieve the above object, the present invention provides a two-slot spiral slot having a substantially H-shaped cross section, which is composed of a tensile strength wire and a thermoplastic resin and has spiral grooves open in two directions. within the manufacturing method of the high density optical fiber cables a plurality of optical fiber ribbon core is accommodated carried, after extruding the thermoplastic resin around the tensile force line, cooled at a temperature lower than the melting point A first step of forming a molded product having a substantially H-shaped cross section having a storage groove extending linearly in the longitudinal direction, and forming the molded product around the major axis in a temperature range not lower than the softening point of the thermoplastic resin and lower than the melting point. After applying a twist by rotating, the second step of forming the two-groove spiral slot by spirally forming the storage groove by solidifying by cooling, and inserting the optical fiber tape core wire in the storage groove, After that, the double groove spiral Characterized in that it comprises a third step of subjecting the wound pressing the outer periphery of Tsu and.

[0013] and the second step and the third step, the twist
It said include receiving groove repair step in imparting Ri, can be continuously performed. The tension member (tensile strength wire) in the present invention means high-strength, high-modulus organic fiber (aromatic polyamide, aromatic polyester, polyamide, polyester, vinylon), inorganic fiber (glass fiber, carbon fiber, ceramic fiber, metal). Fibers), and aggregates of these (referred to as fiber bundles, twisted structures, braids, etc.),
Furthermore, it refers to FRP, FRTP filaments, thin metal wires, metal wire aggregates, etc. that use the above-mentioned fibers and fiber aggregates as reinforcing fibers. When the slots are manufactured, the slots are assembled into a cable. When the cable is laid, the cable is laid, or the cable is used, it is a member that receives the tension applied to the slot body.

The arrangement and configuration of the tension members in the slot are set in consideration of the tension applied to the slot body when the slot is manufactured, when the slots are assembled into a cable, when the cable is laid, or when the cable is used. Just do it.

The thermoplastic resin which can be used in the present invention is selected from various crystalline thermoplastic resins according to the performance required as an optical fiber carrying slot. Examples include polypropylene and the like, and the low temperature embrittlement temperature is -40 among them.
℃ or less, the bending elastic modulus at room temperature is 100 kg /
A resin of mm ² or more is preferable, and in addition to high-density polyethylene, nylon 12, PBT (polyethylene butylene terephthalate), etc., polymer alloys of these crystalline thermoplastic resins with non-crystalline thermoplastic resins such as ABS and PC are also available. Recommended.

The softening point of the resin in the present invention means
It refers to the value measured by the JIS K7207 B method.
When a polymer alloy is selected as the thermoplastic resin of the present invention, the amorphous thermoplastic resin generally does not have a clear melting temperature at which it begins to flow (melting point). Since a polymer alloy composed of a plastic resin and an amorphous thermoplastic resin is used, the melting point is virtually that of the crystalline thermoplastic resin.

In the first step of the present invention, the tension member is supplied to the extruder without being twisted, and the thermoplastic resin is extruded around the tension member into a substantially H-shaped cross-sectional shape, and then the temperature of the melting point is lower than the melting point. It is cooled at a temperature to obtain a molded product having a linear storage groove.

At this time, if necessary, a method of sizing while cooling, a method of cooling and solidifying below the softening point, and a method of sizing while cooling and solidifying below the softening point can be selected. In the second step, the molded product having the linear storage groove obtained in the first step, the softening point of the crystalline thermoplastic resin or higher,
While maintaining the temperature condition below the melting point, twisting is performed by rotating around the major axis, and then cooled and solidified to form the storage groove in a spiral shape to form a two-groove spiral slot.

In this second step, the thermoplastic resin is heated before the twist is added, while the twist is added, or after the twist is added, and the twist is fixed by heat shaping to a temperature at least near the softening point. To obtain a two-groove spiral slot having a predetermined spiral pitch. It should be noted that, if necessary, if the groove is sized at an appropriate position in the second step of forming the twist, the dimension and shape of the groove become uniform.

In order to add twist by rotating the molded product having the linear storage groove obtained in the first step around the major axis, it is common to add twist by a rotary take-up machine.
When the first step and the second step described above are not continuously performed, the first step is wound in a non-twisted manner on a bobbin, and the second step is rewound and supplied, or a bobbin, etc. It is also possible to rewind while rotating so as to apply a twist and supply it to an ordinary take-up machine.

The sizing in each of the above-mentioned steps means that a solid corresponding to the shape and outer shape of the groove is brought into contact to make the shape uniform. In the sizing of the linear groove, the sizing key is After the twist forming, a plurality of sizing pins that can follow the spiral groove in rotation are used. In the third step, a plurality of optical fiber tape core wires are inserted into the storage groove of the two-groove spiral slot, and the outer circumference of the slot is wound with a tape or the like.

If a slot cooling device is provided between the second step and the third step, the temperature of the slot heated in the second step can be controlled, and the manufacturing speed can be increased. In the case where the first step and the second step are separated, a non-twisted molded product is supplied by a rotary feeder, and twist is added in the second step, and then in the third step, a two-groove spiral slot is formed. While inserting multiple optical fiber tape core wires into the storage groove while rotating, supply tape while rotating tape etc. to the outer circumference of the slot to press and wind, and then extrude thermoplastic resin to the outer circumference to remove the resin. It is also possible to cool and perform sheathing.

[0023]

According to the method for manufacturing a high-density optical fiber cable of the present invention, the optical fiber tape core wire is inserted into the inside immediately after the linear groove is changed into a spiral shape, so that the optical fiber tape core wire can be easily inserted and housed. it can. Further, the tape core wire inserted and housed is pressed and wound around the outer periphery of the slot, whereby the spiral pitch of the slot is fixed, and the pitch fluctuation is less likely to occur. Furthermore, sheath covering is performed after the press winding,
The close contact between the slot and the press winding further reduces the difference in bending rigidity with respect to the cross-sectional direction of the slot, and significantly reduces the fluctuation of the spiral pitch due to winding.

[0024]

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Example 1 As shown in the sectional shape of FIG. 2, a pair of spiral rectangular storage grooves A and B are provided above and below the center of a substantially H-shaped cross section, and one tension is provided at the center of the rectangular storage grooves A and B. A high-density optical fiber cable in which a slot D in which a member C is arranged and a plurality of optical fiber tape core wires E are respectively housed in a stepwise manner in the housing grooves A and B of the slot D, and a tape F is wound around the outer circumference thereof. It was manufactured by the method shown in FIG.

The cable of FIG. 2 is used by applying a sheath directly on the tape F, or by twisting several cables of FIG. 2 around a central tension member and then applying a sheath. . In this manufacturing method, the target rectangular shape of the storage grooves A and B has a width of 3.6 m.
m, the depth is 2.0 mm, and the outer diameter of the slot D is 6.4.
mm.

In the manufacturing method shown in FIG. 1, as the tension member C, the softening point (127) of the polymer alloy of polybutylene terephthalate and polycarbonate described below is used.
2840 so that the shrinkage rate at
One denier aromatic polyamide fiber (made by DuPont: trade name Kevlar-49) was prepared, set on the clear stand 1, and the tension member C was adjusted to 600 g / by the dancer roller 2. The tension of the book was applied, and the nipple attached to the head section 4 of the melt extruder 3 was inserted into a predetermined position.

Then, on the outer periphery of the tension member C, a die corresponding to the sectional shape of FIG.
Resin (PC: PBT = 50: 50, Teijin Ltd .: H-
7500AN, softening point 127 ° C, melting point 224.7 ° C (shown
Differential scanning calorimeter, measured by Shimadzu DSC-50
(Value) ) is extruded in a molten state for coating, and while being cooled in water in the cooling tank 5, the take-up machine 7 is used while sizing with the sizing key
Then, a molded product having a linear rectangular storage groove was obtained (first step).

The obtained molded product is subsequently passed through a heat treatment furnace 8 having a hot air generator set temperature of 220 ° C. and a surface temperature of the molded product at the outlet of 140 ° C. at a speed of 3 m / min to be softened by heating. , Was supplied to the sizing device 10 via a rotation prevention guide 9 having a protrusion that engages with the groove.

The sizing device 10 fits into the spiral storage grooves A and B formed by the twist applied by the rotation of the rotary winder 14 to be described later and rotates while sizing the grooves A and B, respectively. 5 sets of pins 11 are set, and slot D is provided in this sizing device 10.
While being cooled, the linear rectangular storage grooves A and B are spiraled, fixed, and sized, and by the steps so far,
A two-groove spiral slot D is obtained (second step). The rotation speed of the rotary winder 14 at this time is 6 rotations / minute,
A twist of 500 mm / pitch was applied to the molded product.

Then, a plurality of optical fiber tape core wires E are inserted stepwise into the rectangular storage grooves A and B of the obtained slot D through the assembly die 12, and the tape F is wound around the outer periphery of the slot D. After press-winding with a coiler, the coiler 13 was taken up by the take-up machine 13, and was then taken up by a rotary take-up machine 14 on a bobbin having a body diameter of 600 mmφ (third step).

The high-density optical fiber cable of about 100 m manufactured in this way was unwound from the bobbin and the spiral pitch at 40 points was measured. As a result, the average pitch is 50
It was 1.2 mm and had a standard deviation (σn ⁻¹ ) of 11.0 mm, which was very stable, and could exhibit sufficient performance as an optical fiber cable.

Example 2 A high-density optical fiber cable was produced under the same conditions as in Example 1 except that the rotation speed of the rotary winder 14 was 20 rotations / minute and the take-up speed was 10 m / minute. At this time, the surface temperature of the molded product at the exit of the heat treatment furnace 8 was 135 ° C. The spiral pitch of the cable obtained in this example has an average value of 508 mm and a standard deviation (σn ⁻¹ ) of 13.5 m.
It was stable as m and had sufficient performance as an optical fiber cable.

Comparative Example 1 An optical fiber cable was produced under the same conditions as in Example 1 except that the heat source of the heat treatment furnace 8 was stopped and the temperature was kept at room temperature. The spiral pitch of the obtained optical fiber cable is 52 on average.
3.1 mm, standard deviation (σ n ⁻¹ ) is 48.3 mm,
It was very unstable and its performance as an optical fiber cable was insufficient.

Comparative Example 2 An optical fiber cable was produced under the same conditions as in Example 1 except that the tape F was not pressed. The average pitch of the obtained optical fiber cables is 520.8.
mm, the standard deviation (σ n ^-1 ) was 36.5 mmm, which was very unstable, and the performance as an optical fiber cable was insufficient.

Embodiment 3 As shown in the sectional view of FIG. 2, spiral rectangular storage grooves A and B are provided above and below a circular cross section, and one tension member C is provided at the center of the rectangular storage grooves A and B. FIG. 3 shows a high-density optical fiber cable in which a plurality of optical fiber tape core wires E are housed in a stepwise manner in the slots D in which the slots D are arranged and in the housing grooves A and B of the slots D, and the tape F is wound around the outer circumference thereof. It was produced by the method shown.

In this manufacturing method, the target dimensions of the rectangular storage grooves A and B were set to the same dimensions and shapes as in the first embodiment. In the manufacturing method shown in FIG. 3, the same tension member C as that used in Example 1 is used, a tension of 600 g / piece is loaded by the dancer roller 2, and the tension member C is mounted on the head portion 4 of the melt extruder 3. Insert it in the specified position of the nipple,
The outer periphery of the tension member B is extruded and coated with the same resin as in Example 1 in a molten state, and is cooled by water in the cooling tank 5 while being sized by the sizing key 6. It was wound on a bobbin 21 mounted on 20 to obtain a molded product having a linear rectangular storage groove (first step).

The obtained molded product was loaded with the bobbin 21 in the feeder 2.
2 and then rewinding, and through the fixed die 23, 5
It is supplied to the heat treatment furnace 8 at a speed of m / min, is heated and softened, and is twisted by the rotary take-up machine 13. At this time, the surface temperature of the molded product at the outlet of the heat treatment furnace 8 was 140 ° C. The molded product to which the twist has been imparted in this way is then cooled by the cooling device 24, and the linear rectangular storage grooves A and B are spiralized and fixed (second step).

Next, a plurality of optical fiber tape core wires E are supplied through the assembly die 12 into the rectangular storage grooves A and B of the obtained slot D and are inserted in a stepwise manner, and the tape is provided on the outer periphery of the slot D. Hold F and wind. Then, the press-winding tape F was applied to the bobbin 25 having a body diameter of 600 mmφ by the rotary winder 14 via the rotary take-up machine 13 (third step).

The high-density optical fiber cable of about 100 m manufactured in this way was unwound from the bobbin and the spiral pitch at 40 points was measured. As a result, the average pitch is 49
It was 9.4 mm, and the standard deviation (σn ^-1 ) was 10.5 mm, which was very stable, and could exhibit sufficient performance as an optical fiber cable.

Example 4 As shown in the sectional view of FIG. 2, spiral rectangular storage grooves A and B are provided above and below a circular cross section, and one tension member C is provided at the center of the rectangular storage grooves A and B. FIG. 4 shows a high-density optical fiber cable in which a plurality of optical fiber tape core wires E are housed in a step-like manner in a slot D in which the tape D is arranged, and tapes F are wound around the outer circumference thereof in the storage grooves A and B of the slot D. It was produced by the method shown.

In this manufacturing method, the target dimensions of the rectangular storage grooves A and B were set to the same dimensions and shapes as in the first embodiment. In the manufacturing method shown in FIG. 4, the two-groove spiral slot having the spiral rectangular storage groove was obtained without storing the optical fiber tape core wire and pressing the tape with the tape in Example 1. The two-groove spiral slot wound on the bobbin 21 is mounted on the rotary feeder 30, and while being unwound, is fed to the heat treatment furnace 32 at a speed of 5 m / min through the guide die 31 to be heated and softened, and the pitch. It is introduced into the correction shaping die 34, cooled by the cooling device 35, and the pitch of the spiral rectangular storage grooves A and B is corrected. At this time, the surface temperature of the slot D at the outlet of the heat treatment furnace 32 is 14
It was 0 ° C.

In this case, the pitch correction shaping die 34 is
The dies having a shape that fits into the square-shaped storage grooves A and B, which are twisted in a spiral shape, are set at different angles so as to correspond to at least one spiral pitch, and the dies should be inserted. Thus, the spiral pitch is corrected and fixed by the cooling device 35.

Next, a plurality of optical fiber tape core wires E are supplied through the assembly die 36 into the rectangular storage grooves A and B of the obtained slot D, inserted in a stepwise manner, and the tape is provided on the outer periphery of the slot D. Hold F and wind. Then, the press-winding tape F was applied to the bobbin 35 having a body diameter of 600 mmφ by the rotary winder 34 through the rotary take-up machine 33 (third step).

The high-density optical fiber cable of about 100 m produced in this way was unwound from the bobbin, and the spiral pitch at 40 points was measured. As a result, the average pitch was very stable and sufficient performance as an optical fiber cable was obtained. Was able to exert.

[0045]

As described above in detail, according to the manufacturing method of the present invention, a plurality of optical fiber tape core wires can be easily accommodated in the accommodation groove of the two-groove spiral slot and the bobbin can be accommodated. Even when wound, the fluctuation of the spiral pitch can be reduced, and the productivity and reliability of the cable are greatly improved.

[Brief description of drawings]

FIG. 1 is a process explanatory view sequentially showing a process of a first embodiment of a manufacturing method according to the present invention.

FIG. 2 is a sectional view of a cable obtained according to the first embodiment.

FIG. 3 is a process explanatory view sequentially showing the process of the third embodiment of the manufacturing method according to the present invention.

FIG. 4 is a process explanatory view sequentially showing a process of a fourth embodiment of the manufacturing method according to the present invention.

[Explanation of symbols]

A, B square storage groove C tensile strength line D slot E Optical fiber tape core wire F tape

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-154209 (JP, A) JP-A-1-198712 (JP, A) Fukuihei 1-103813 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) G02B 6/44

Claims (2)

(57) [Claims] 1. A plurality of optical fiber tape core wires are housed and carried in a two-groove spiral slot having a substantially H-shaped cross section, which is composed of a tensile strength wire and a thermoplastic resin and has a spiral groove opened in two directions. the method of manufacturing a density optical fiber cables, after extruding the thermoplastic resin in the ambient of the tensile strength wire, a substantially H-shaped cross-section with a receiving groove extending linearly longitudinally cooled below the melting point A first step of forming a molded product, and after imparting a twist by rotating this molded product around the major axis in a temperature range of the softening point of the thermoplastic resin or higher and lower than the melting point,
A second step of forming the two-groove spiral slot by spirally solidifying by cooling to form the two-groove spiral slot; and inserting the optical fiber tape core wire into the storage groove, and thereafter, 3. A method for manufacturing a high-density optical fiber cable, which comprises a third step of applying a press winding to the outer periphery. 2. The second step and the third step are
The method for manufacturing a high-density optical fiber cable according to claim 1, wherein the method is performed continuously including the step of correcting the storage groove when applying the twist .