JP2002240128A - Slot for optical cable and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slot for an optical cable which improves the molding precision and production properties of the slot, and to provide a method for producing the slot. SOLUTION: A cylindrical separator 11 is provided in a mold for molding the slot, a resin to be an inner layer 2 and a resin to be an outer layer 3 are supplied from two different extruders to the inside and outside of the separator 11. In the tip of the separator 11, in a cross section perpendicular to the longitudinal direction of the mold for molding the slot for the optical cable, the ratio d2/d1 between the diameter d1 of a circle inscribing a part molding the bottoms 5a of a plurality of channels 5 and the diameter d2 of the separator 11 is made 0.65-0.95, and the ratio 1/d2 of the distance from the tip 16 of the discharge opening of the mold to the separator 11 to the diameter d2 of the separator 11 is made 0.3-1.0. The channels 5 are formed spirally in the SZ direction or in one direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical cable slot in which a plurality of grooves are spirally cut, and a method of manufacturing the same. .

[0002]

2. Description of the Related Art Conventionally, an SZ slot type optical cable as shown in FIG. 5 has been used as an example for forming an optical cable by assembling a plurality of optical fiber ribbons (hereinafter, also simply referred to as a tape ribbon). Are known. In the SZ slot type optical cable of this example, a tension member 21 is provided at the center, and a preliminary coating layer 22 made of a thermoplastic resin is provided on the outer periphery of the tension member.
A slot body made of a thermoplastic resin is formed on the outer periphery of the slot 2, and an SZ slot 20 in which a plurality of grooves 23 are spirally cut is used on the peripheral surface of the slot body. An optical fiber tape core laminate (hereinafter, sometimes simply referred to as a tape core laminate) 32 in which a plurality of tape cores 31 are stacked is housed in the groove 23, and the SZ slot 2 is provided.
0, a presser winding layer 25 is provided.
The sheath 26 is provided on the circumference of the fifth.

In order to form the SZ slot 20 used in the SZ slot type optical cable having such a configuration, a pre-coating layer 22 made of a thermoplastic resin such as high-density polyethylene is coated on the outer periphery of the tension member 21 by extrusion molding. Thereafter, the slot body portion forming the rib 24 on the outer periphery of the preliminary coating layer 22 is extruded. As described above, in the conventional method for forming the slot 20, there is a problem that the forming cost of the pre-coating layer 21 and the forming of the rib 24 must be increased twice or more, which increases the processing cost.

[0004] For this reason, a method of forming a slot by a single extrusion was examined, but it was found that there were the following problems. FIG. 6 shows the SZ slot 20
It is sectional drawing which shows the other example of a. In this figure, the outer diameter of the tension member 21 is d ₃ . Further, the diameter of the circle inscribed in all the groove bottom 23a and d _4. When the difference d ₄ −d ₃ between d ₃ and d ₄ increases, in the extrusion of the SZ slot 20, after the SZ slot 20 is extruded from the mold,
The resin forming the groove bottom 23a rises, and the depth of the groove 23 becomes shallow. In addition, the fluidity of the resin to the tip portion of the rib 24 deteriorates, and the rib 24 becomes thinner and shorter. As described above, when d ₄ −d ₃ is increased, the shape of the SZ slot 20 after being extruded from the mold is significantly different from the shape of the discharge port of the mold, and thus the problem that the mold design is extremely difficult is caused. is there.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical cable slot in which a plurality of grooves are spirally cut and a method of manufacturing the same, and an optical cable slot which improves the molding accuracy and manufacturability of the slot. And a method for manufacturing the same.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to provide a method for manufacturing an optical cable slot having a tension member at the center and a plurality of grooves spirally engraved on a peripheral surface of a slot body composed of an inner layer and an outer layer. In a slot molding die for an optical cable, a cylindrical separator is provided, and the resin serving as the inner layer and the resin serving as the outer layer are supplied to the inside and outside of the separator from two different extruders. The problem can be solved by a method of manufacturing an optical cable slot characterized by the above-mentioned feature. Further, at a tip end portion of the separator, in a cross section perpendicular to a longitudinal direction of the optical cable slot of the optical cable slot molding die, a groove bottom of a plurality of grooves of the optical cable slot molding die is formed. the diameter d ₁ of the circle inscribed in the portions of molding, the ratio d ₂ / d ₁ of the outer diameter d ₂ of the separator is preferably set to 0.65-0.95. Then, the ratio l / d ₂ of the distance l from the tip of the discharge port of the optical cable slot forming die to the separator and the outer diameter d _{2 of the} separator is 0.3 to 1.0.
It is preferable that

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to FIGS. 1, 2 and 3. FIG. FIG. 1 is a schematic sectional view showing an example of a discharge port of a slot molding die used in the present invention, which is parallel to a longitudinal direction of a slot. FIG.
1 is a schematic cross-sectional view taken along aa ′ in FIG. 1, showing an example of a cross section of a tip portion of a separator of an optical cable slot forming mold used in the present invention, perpendicular to the longitudinal direction of the slot. is there. FIG. 3 is a schematic cross-sectional view showing a right-angled crosshead die as an example of a slot molding die used in the present invention.

According to the method for manufacturing an optical cable slot of the present invention, a tension member 1 is provided at the center, and an inner layer 2 and an outer layer 3 are provided.
A method for manufacturing an optical cable slot in which a plurality of grooves 5 are spirally engraved on a peripheral surface of a slot main body 4 comprising: a slot molding die for an optical cable (hereinafter referred to as a “slot molding die”). ), A cylindrical separator 11 is provided inside, and a resin to be the inner layer 2 and a resin to be the outer layer 3 are separated from the two different extruders by the inside and outside of the slot forming die separated by the separator 11. And to supply.

At the tip end of the separator 11, a groove bottom forming portion 12a for forming the groove bottom 5a of the plurality of grooves 5 in a section perpendicular to the longitudinal direction of the optical cable slot of the slot forming die. The diameter of the circle inscribed in all is d
_1, and the outer diameter of the separator 11 and d _2, the ratios d ₂ / d ₁ is 0.65-0.95, preferably 0.70
０．９0.90. If d ₂ / d ₁ is less than 0.65, it is difficult to control the depth of the groove 5 by adjusting the supply amounts of the resin to be the inner layer 2 and the resin to be the outer layer 3 at the time of forming the optical cable slot. Become. d ₂ / d ₁ is 0.95
When the value exceeds, a large gap is formed between the inner layer 2 and the outer layer 3 during molding of the optical cable slot, or a desired cross-sectional shape of the optical cable slot cannot be obtained.

When the distance from the tip 16 of the discharge port of the slot forming die to the separator 11 is 1 and the outer diameter of the separator 11 is d ₂ , the ratio l / d ₂ is 0.1.
It is 3 to 1.0, preferably 0.5 to 0.9. l / d
_{If 2} is less than 0.3, when molding an optical cable slot,
A large void is formed between the inner layer 2 and the outer layer 3, or
The desired cross-sectional shape of the optical cable slot cannot be obtained.
If 1 / d ₂ exceeds 1.0, it is difficult to control the depth of the groove 5 by adjusting the supply amounts of the resin to be the inner layer 2 and the resin to be the outer layer 3 at the time of molding the optical cable slot. Become.

FIG. 3 shows a slot molding die.
The crosshead die 17 shown in FIG. 1 is used, but the present invention is not limited to the right-angled die shown in this example, and an inclined type is also used. The right-angled crosshead die 17 of this example is connected on one side thereof to a first extruder 18 perpendicular to the extrusion direction of the optical cable slot, and on the other side, to the extrusion of the optical cable slot. Second perpendicular to the direction
Extruder 19 is connected. The inside of the crosshead die 17 is separated by the separator 11. The resin that forms the inner layer 2 is supplied from the first extruder 18 to the inside of the separator 11, and the resin that forms the outer layer 3 is supplied to the outside of the separator 11 from the second extruder 19. Then, the resin to be the inner layer 2 and the resin to be the outer layer 3 are laminated near the discharge port of the crosshead die 17 and are integrally formed with the tension member 1 to form an optical cable slot.

As described above, by using two different extruders, a slot for an optical cable can be manufactured by one extrusion molding, so that the process is simplified.
Manufacturing costs can be reduced. Further, since the resin to be the inner layer 2 and the resin to be the outer layer 3 are supplied to the slot molding die from two different extruders, the extrusion conditions such as the extrusion pressure and the extrusion temperature of each extruder are adjusted. Since the resin pressure near the tension member 1 can be reduced and the resin pressure near the tip of the rib 6 can be increased, the optical cable slot can be formed in a desired shape.

In the method of manufacturing an optical cable slot according to this embodiment, first, an adhesive made of styrene, ethylenebutylene-styrene block copolymer or the like is applied to the outer periphery of the tension member 1 to provide an adhesive layer. Next, the tension member 1 provided with the adhesive layer is introduced into the nipple 15 in the slot molding die, and the resin which becomes the inner layer 2 on the outer periphery of the adhesive layer near the discharge port of the slot molding die. Then, the resin to be the outer layer 3 is extrusion-coated to form the slot main body 4. Further, the slot body 4 is connected to the tension member 1.
And at the same time, the slot body 4 and the tension member 1 are tightly integrated. At the same time, the outer layer forming portion 14 including the groove forming portion 12 and the rib forming portion of the slot forming die rotates at a constant speed in the SZ direction or in one direction, and a plurality of spiral spirals of the slot main body 4 are formed. Groove 5 is SZ
Formed in one direction or one direction. Next, after the slot body 4 is formed, the optical cable slot is air-cooled,
It is inspected by an inspection device and wound up by a winding machine via a take-up machine. In the manufacturing method of the optical cable slot of this example, since the adhesive layer is provided between the tension member 1 and the slot main body 4, an optical cable slot having excellent adhesion between the tension member 1 and the slot main body 4 can be manufactured. .

FIG. 4 shows an example of the optical cable slot of the present invention. In this example, the optical cable slot
Abbreviated as "slot". 10) is manufactured by the above-described method for manufacturing an optical cable slot, and has a plurality of spiral grooves 5 engraved in the SZ direction or one direction. The SZ direction means that the direction in which the groove is twisted alternately repeats the S direction and the Z direction. Slot 10 in this example
Then, the SZ inversion pitch is preferably 125 to 300 mm. In this way, by forming a plurality of spiral grooves of the optical cable slot in the SZ direction or in one direction, the slot type optical cable using this is excellent in rear branching.

In designing the slot 10, according to the total number of optical fibers accommodated in the entire slot 10 and the number of tape cores to be used, the number of tape cores accommodated in one groove 5 and The number of grooves 5 is determined.
In order to achieve high density, the number of grooves 5 is preferably large, preferably 5 to 10, and particularly preferably 3 to 6.

The cross-sectional shape of the groove 5 is a tapered shape whose side wall is gradually widened toward the outer periphery of the slot 10, and is substantially U-shaped with a substantially arc-shaped groove bottom 5a. Further, in the tape core laminated body accommodated in the groove 5, since only the tape cores are stacked and the tape cores are not integrated with each other, the opening width B of the groove 5 and the width of the laminated product are different. If the difference and the difference between the depth C from the opening of the groove 5 to the deepest point of the groove bottom 5a and the thickness of the tape core laminate are too small, the arrangement of the tape cores housed in the groove 5 may be reduced. There is a risk of being disturbed or applying excessive stress to the tape core. Therefore, the dimension of the groove 5 is such that the opening width B of the groove 5 is 0.2 to 0.2 times larger than the width of the tape core laminated body accommodated in the groove 5.
It is determined so as to be larger by 1.0 mm, and so that the depth C of the groove 5 is larger by 0.2 to 1.0 mm than the thickness of the tape core laminate.

As the tension member 1, a tensile strength material such as a single steel wire, a steel stranded wire, FRP (fiber reinforced plastic) or the like is suitably used, and an appropriate one is selected according to a use environment, a laying method, and the like. In particular, when a single steel wire is used, it is preferable to use a wire that has been subjected to rust prevention treatment.
Further, when it is preferable that the optical cable is made of only a non-metallic material, such as when a non-guided optical cable is required, FRP such as aramid fiber reinforced plastic or glass fiber reinforced plastic is preferably used. Further, since the tension member 1 plays a role of releasing the heat of the resin coated on the outer periphery thereof and cooling the resin after the extrusion molding, it is preferable that the tension member 1 has a larger heat capacity. It is considered that the same cooling effect can be obtained with a single steel wire or a stranded steel wire if the cross-sectional areas are equal. Further, since the heat capacity of FRP or the like is larger than that of a single steel wire, the cooling effect is greater. The thickness of the tension member 1 is designed according to the material of the tension member 1 in consideration of the allowable tension of the tension member 1 and the weight of the optical cable.

As the resin used for the resin forming the inner layer 2 and the resin forming the outer layer 3, a thermoplastic resin such as high-density polyethylene is preferably used.

Hereinafter, specific examples will be described. First, the slot 10 having the configuration shown in FIG. 4 was manufactured. The structural parameters of the slot 10 were as follows. Using the single steel wire having an outer diameter of 2.3mm as tension member 1, the distance l from the tip of the discharge opening of the slot forming mold shown in FIG. 2 to the separator, the outer diameter d ₂ of the separator 11 The slot 10 was manufactured by changing the outer diameter d ₂ to 0.8 times. Number of grooves 10 Groove width (A) 3.3 mm Groove depth (B) 2.3 mm Slot outer diameter 8.0 mm Inversion pitch 125 mm

Next, the controllability of the cross-sectional shape of these slots 10 and the evaluation of the cross-sectional shape were evaluated. Evaluation of the controllability of the cross-sectional shape If the depth C of the groove 5 can be easily controlled by adjusting the supply amounts of the resin to be the inner layer 2 and the resin to be the outer layer 3, ○, the resin to be the inner layer 2, the outer layer It is possible to control the depth C of the groove 5 by adjusting the supply amount of the resin which becomes No. 3;
If it is difficult to easily control the depth C of the groove 5 by adjusting the supply amount of the resin, the result is evaluated as x.・ Evaluation of cross-sectional shape There is no gap between the resin to be the inner layer 2 and the resin to be the outer layer 3. If the desired cross-sectional shape is obtained, ○, between the resin to be the inner layer 2 and the resin to be the outer layer 3. Although a small gap is formed, if a desired cross-sectional shape is obtained, a large gap is formed between the resin to be the inner layer 2 and the resin to be the outer layer 3, and the desired cross-sectional shape is obtained. If not, it was evaluated as ×. Table 1 shows the above results.

[0021]

[Table 1]

From the results shown in Table 1, the value of d ₂ / d ₁ is 0.65
If the mold for slot molding is designed to have a thickness of from 0.95 to 0.95, preferably from 0.70 to 0.90, good controllability of the cross-sectional shape can be obtained, and the slot 10 having a desired cross-sectional shape can be obtained.

Similarly, the value of d ₂ / d ₁ was set to 0.8, and the distance 10 from the tip 16 of the discharge port of the slot forming die to the separator was changed to form the slot 10. Next, the controllability of the cross-sectional shape and the evaluation of the cross-sectional shape of these slots 10 were also performed. Table 2 shows the above results.

[0024]

[Table 2]

From the results shown in Table 2, the value of l / d ₂ is 0.3 to
If the slot molding die is designed to be 1.0, preferably 0.5 to 0.9, good controllability of the cross-sectional shape can be obtained, and the slot 10 having a desired cross-sectional shape can be obtained.

[0026]

As described above, according to the method for manufacturing an optical cable slot of the present invention, a tension member is provided at the center, and a plurality of grooves are spirally formed on the peripheral surface of a slot body composed of an inner layer and an outer layer. A method for manufacturing an optical cable slot, comprising: providing a cylindrical separator in an optical cable slot molding die, and separating the resin to be the inner layer and the resin to be the outer layer from two different extruders from different extruders. By adjusting the respective extruders, the resin pressure near the tension member can be reduced and the resin pressure near the tip of the rib can be increased. Can be formed in a desired shape.

Further, in the method for manufacturing an optical cable slot according to the present invention, the optical cable slot molding die may have a cross section perpendicular to a longitudinal direction of the optical cable slot at a tip portion of the separator. The diameter d _{1 of} a circle inscribing a portion for forming the groove bottom of the plurality of grooves of the slot forming die, and the outer diameter d _{2 of the} separator
Since the 0.65-0.95 ratio d ₂ / d ₁ of the moldability of the optical cable slot is improved.

The optical cable slot according to the present invention is an optical cable slot manufactured by the optical cable slot manufacturing method according to the present invention, wherein a plurality of spiral grooves are formed in the SZ direction or one direction. Since it is provided, it has excellent post-branching properties.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a shape of a discharge port of a slot molding die used in the present invention, which is parallel to a longitudinal direction of a slot.

FIG. 2 is a schematic cross-sectional view showing an example of a cross-sectional shape of a distal end portion of a separator of an optical cable slot-forming mold used in the present invention, which is cut perpendicular to a longitudinal direction of the slot.

FIG. 3 is a schematic sectional view showing a right-angled crosshead die as an example of a slot molding die used in the present invention.

FIG. 4 is a sectional view showing an example of the optical cable slot of the present invention.

FIG. 5 is a sectional view showing a conventional SZ slot type optical cable.

FIG. 6 is a schematic cross-sectional view showing a shape of a discharge port of an SZ slot molding die, which is perpendicular to a longitudinal direction of an optical cable slot.

[Explanation of symbols]

1 ... tension member, 2 ... inner layer, 3 ... outer layer, 4 ...
Slot body, 5 groove, 5a groove bottom, 6 rib, 1
0 ... slot, 11 ... separator, 12 ... groove forming part, 12a ... groove bottom forming part, 13 ... rib forming part, 14 ...
-Outer layer forming part, 15 ... nipple, 16 ... tip of discharge port, 17 ... crosshead die, 18 ... first extruder,
19: second extruder

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B29L 11:00 B29L 11:00 (72) Inventor Suehiro Miyamoto 1440 Mutsuzaki, Sakura City, Chiba Prefecture FUJI CORPORATION F-term in Kura Sakura Office (reference) 2H001 BB09 BB10 MM01 PP01 4F207 AA05 AD03 AD05 AD15 AD34 AG28 AH77 KA01 KA17 KA20 KB18 KB22 KL58 KL65 KL80

Claims (4)

[Claims] 1. A method of manufacturing an optical cable slot, comprising: a tension member at a center; and a plurality of grooves spirally engraved on a peripheral surface of a slot body composed of an inner layer and an outer layer. An optical cable slot, wherein a cylindrical separator is provided in a mold, and the resin serving as the inner layer and the resin serving as the outer layer are supplied to the inside and outside of the separator from two different extruders. Manufacturing method. 2. A cross section perpendicular to a longitudinal direction of the optical cable slot of the optical cable slot molding die at a tip end portion of the separator, wherein a plurality of grooves of the optical cable slot molding die are formed. the diameter d ₁ of the circle inscribed in the portions forming the groove bottom, according to claim 1, characterized in that the ratio d ₂ / d ₁ of 0.65-0.95 between the outer diameter d ₂ of the separator Manufacturing method of an optical cable slot. 3. A ratio 1 / d ₂ of a distance 1 from a tip of a discharge port of the optical cable slot forming die to the separator and an outer diameter d _{2 of the} separator is 0.3 to 1.0. 3. The method for manufacturing an optical cable slot according to claim 1, wherein: 4. An optical cable slot manufactured by the manufacturing method according to claim 1, wherein the plurality of spiral grooves are formed in the SZ direction or in one direction. Slot for optical cable.