JP2023056842A - Slot rod for optical fiber cable, optical fiber cable, and manufacturing method of slot rod for optical fiber cable - Google Patents

Abstract

To provide a slot rod for optical fiber cable configured to suppress collapse of ribs during extrusion molding of a slot rod, an optical fiber cable, and a manufacturing method.SOLUTION: A slot rod for optical fiber cable 10 includes a central layer 20 with a tension member 11 embedded therein, and an outermost layer 13 covering an outer periphery of the central layer 20, the outermost layer 13 having a plurality of slot ribs 15 radially extending from the central layer 20 and slot grooves 16 formed between the slot ribs 15. The slot grooves 16 include at least a first slot groove and a second groove formed in a position different from the first slot groove. When a thicknesses of an outermost layer at a center of a bottom of the slot grooves 16 are a[mm] in the first slot groove and b[mm] in the second slot groove, respectively, a following relationship between (a) and (b) is satisfied: a>b.SELECTED DRAWING: Figure 4B

Description

TECHNICAL FIELD The present disclosure relates to a slotted rod for an optical fiber cable, an optical fiber cable, and a method for manufacturing a slotted rod for an optical fiber cable.

Some optical fiber cables have a slot rod in which a plurality of radially formed slot ribs and slot grooves provided between the slot ribs are formed. Each slot groove accommodates a plurality of optical fibers. The outside of the slot rod is wrapped with, for example, a pressure winding tape and further covered with a cable jacket.

For example, in order to provide high-speed communication services such as FTTH (Fiber To The Home), it is preferable to accommodate optical fibers in slot grooves at a high density. For this purpose, it is preferable to increase the cross-sectional area of the slot groove by making the rib thinner and taller. There is a case of falling (hereinafter also referred to as "rib falling").

Patent Literature 1 discloses a technique for preventing rib collapse by specifying the height of a slot rib and the distance from the center of the groove bottom of the slot groove to the surface of the tension member.

JP 2020-060610

However, in the technique described in Patent Document 1, the height of the slot rib and the distance from the center of the groove bottom of the slot groove to the surface of the tension member are specified. There was a possibility that rib collapse during extrusion molding could not be suppressed.

An object of the present invention is to provide a slotted rod for an optical fiber cable, an optical fiber cable, and a method for manufacturing the slotted rod for the optical fiber cable, which can suppress rib collapse during extrusion molding of the slotted rod.

A slot rod for an optical fiber cable of the present disclosure has a central layer in which a tension member is embedded in the center, and an outermost layer that covers the radially outer side of the central layer, and the outermost layer has a A slotted rod for an optical fiber cable, comprising a plurality of radially extending slot ribs and slot grooves formed between said slot ribs, said slot grooves comprising at least a first slot groove and said first slot groove. and a second slot groove provided at a position different from the first slot groove, wherein the thickness of the outermost layer at the center of the bottom of the slot groove is a [mm] in the first slot groove, and the When b [mm] in the second slot groove, a and b are a>b
satisfy the relationship

Further, an optical fiber cable of the present disclosure includes the optical fiber cable slot rod and an optical fiber unit housed in the slot groove.

Further, in the method for manufacturing a slotted rod for an optical fiber cable of the present disclosure, the extrusion direction is tilted downward with respect to the horizontal plane during the extrusion molding of the slot ribs.

According to the above, it is possible to provide a slotted rod for an optical fiber cable, an optical fiber cable, and a method for manufacturing a slotted rod for an optical fiber cable that suppress rib collapse during extrusion molding of the slotted rod.

1 is a cross-sectional view of a fiber optic cable using slotted rods in accordance with one aspect of the present disclosure; FIG. 1 is a perspective view of a slotted rod for a fiber optic cable according to one aspect of the present disclosure; FIG. FIG. 3 is a schematic diagram of a manufacturing apparatus for the slotted rod for optical fiber cable of FIG. 2; Fig. 3 is a cross-sectional view of the slotted rod for the fiber optic cable of Fig. 2; FIG. 4B is a partially enlarged view of the vicinity of the central portion in FIG. 4A. FIG. 3 is an explanatory diagram of rib collapse of the slot rod for optical fiber cable of FIG. 2 ; 1 is an explanatory diagram of an outermost layer extruder according to an aspect of the present disclosure; FIG.

[Description of Embodiments of the Present Disclosure]
First, the contents of the embodiments of the present disclosure will be listed and explained.
The present disclosure has the following effects due to the configurations (1) to (8).
(1) A center layer having a tension member embedded in the center and an outermost layer covering the radially outer side of the center layer, and the outermost layer has a plurality of slot ribs radially extending from the center layer. and slot grooves are formed between the slot ribs, wherein the slot groove is at least a first slot groove and a position different from the first slot groove and the thickness of the outermost layer at the center of the bottom of the slot groove is a [mm] in the first slot groove, and b [mm] in the second slot groove. mm], a and b are a>b
satisfy the relationship
According to the slotted rod for an optical fiber cable configured in this way, for example, when the slotted rod is extruded, the lowermost slot groove is set as the first slot groove, and the uppermost slot groove is set as the second slot groove. In the case of a slot groove, since the thickness of the groove bottom satisfies the relationship a>b, the material of the upper groove bottom is relatively accelerated when the slot rod is extruded, and the upper slot rib is pulled by gravity. can prevent you from falling down.
In the present disclosure, the positional relationship between the first slot groove and the second slot groove is not limited to the bottom and top positions. For example, when the slot rod is extruded, the first slot groove is positioned downward, If the second slot groove is in an upward relationship, by satisfying the relationship a>b, it is possible to suppress rib collapse during extrusion molding of the slot rod.

(2) In the above slot rod for optical fiber cable, the first slot groove and the second slot groove face each other with the central layer interposed therebetween.
Accordingly, for example, when the slot rod is extruded, the slot groove located at the bottom is defined as the first slot groove, and the slot groove located at the top is defined as the second slot groove. The effect of suppressing rib collapse during molding can be enhanced.

(3) In the above slot rod for optical fiber cable, a and b are (ab)/2≧0.1 mm
satisfy the relationship
As a result, an appropriate range of eccentricity (ab)/2 of the central layer with respect to the outermost layer is defined, and by satisfying this condition, the slot ribs are prevented from collapsing due to gravity when the outermost layer is extruded. can be suppressed.

(4) In the above-described slotted rod for optical fiber cable, the slot groove is SZ-shaped or helical.
As a result, even when the slot grooves are SZ-shaped or spiral, for example, by eccentrically moving the center layer with respect to the outermost layer, the slot ribs are prevented from collapsing due to gravity when the outermost layer is extruded. be able to.

(5) In the above slot rod for an optical fiber cable, the material of the outermost layer and the central layer is resin, and the density of the resin of the outermost layer is higher than that of the central layer.
As the resin for the outermost layer, a resin having a higher density than the resin for the central layer is used, so that the effect of suppressing the collapse of the slot ribs due to gravity can be enhanced when the outermost layer is extruded.

(6) In the slot rod for an optical fiber cable described above, the density of the outermost resin layer is 0.942 g/cm ³ or more, the upper width of the slot rib at the tip of the slot rib is c [mm], and the adjacent c and d are 1.0 mm ≤ c < d ≤ 8.0 mm, where d [mm] is the lower width of the slot rib, which is the length of the straight line connecting the centers of the slot grooves.
satisfy the relationship
This defines an appropriate relationship between the slot rib upper width c and the slot rib lower width d with respect to the resin density of the outermost layer of the slot rod for optical fiber cable. It is possible to further suppress the ribs from collapsing due to gravity.

(7) Further, the optical fiber cable of the present disclosure includes an optical fiber cable slot rod and an optical fiber unit housed in the slot groove.
Accordingly, it is possible to provide an optical fiber cable having the same effect as the optical fiber cable slot.

(8) Further, in the method for manufacturing a slotted rod for an optical fiber cable according to the present disclosure, the extrusion direction is tilted downward with respect to the horizontal plane when the slot ribs are extruded.
As a result, the extrusion direction of the slot ribs during extrusion molding is tilted downward with respect to the horizontal plane, so that the extrusion molding material of the slot ribs, such as a resin material, is supplied to the bottom of the uppermost slot groove. , is relatively smaller than the resin material supplied to the bottom of the lowermost slot groove, and the relationship a>b can be satisfied. Also, even when the slot groove is SZ-shaped or helical, the extrusion direction is always inclined downward with respect to the horizontal plane, so that the relationship a>b can be satisfied.

[Details of the embodiment of the present disclosure]
Hereinafter, specific examples of a slotted rod for an optical fiber cable, a method for manufacturing a slotted rod for an optical fiber cable, and an optical fiber cable according to the present disclosure will be described.
In the following description, configurations denoted by the same reference numerals in different drawings may be the same, and descriptions thereof may be omitted.
In addition, the present disclosure is not limited to these examples, but is indicated by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

[Overview of optical fiber cables]
First, an optical fiber cable using a slot rod according to one aspect of the present disclosure will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a cross-sectional view of a fiber optic cable using a slotted rod according to one aspect of the present disclosure, and FIG. 2 is a perspective view of the slotted rod for the fiber optic cable according to one aspect of the present disclosure.

The optical fiber cable 30 shown in FIG. It is provided with a winding tape 33 wound by winding and a cable jacket 34 applied around the winding tape 33. - 特許庁

The slot rod 10 is a member in which the periphery of the tension member 11 is coated with resin. The slot rod 10 has a tension member 11, an intermediate layer 12 provided outside the tension member 11, and an outermost layer 13 provided radially outside the intermediate layer. The outermost layer 13 is formed with a plurality of slot ribs 15 projecting away from the tension member 11 . An optical fiber cable is arranged in the slot grooves 16 formed between the slot ribs 15 .

The slot groove 16 is formed in a spiral shape along the longitudinal direction of the slot rod 10, or in an SZ shape in which the twist direction is periodically reversed. In FIGS. 1 and 2, for example, eight slot ribs 15 are formed at equal intervals in the circumferential direction. In this case, eight slot grooves 16 are formed in the slot rod 10, but the present disclosure is not limited to this, and for example, 3 to 10 slots can be arbitrarily adopted.

The tension member 11 is a wire rod having resistance to tension and compression, such as a single wire or a stranded wire, and is made of a steel wire or a non-metallic wire (for example, FRP (Fiber Reinforced Plastics, etc.)).

Around the tension member 11, resin layers such as a lower pressing layer and one or more intermediate layers 12 are provided. The number of intermediate layers is not particularly limited, but can be, for example, 1 to 4 layers. Also, the tension member 11 , the lower pressing layer, and the intermediate layer 12 are collectively referred to as a central layer 20 . Although the tension member 11 is embedded in the central portion of the slot rod 10, that is, in the central portion of the central layer 20, its position does not have to be strictly the center of the slot rod 10. It suffices if it is buried inside.

The material of the slot rod 10 is not particularly limited, but resin is usually used. For example, an underlayer of low-density polyethylene (hereinafter referred to as LDPE) is formed around the tension member 11, and an intermediate layer of high-density polyethylene (hereinafter referred to as HDPE) is formed around this underlayer. A layer may be formed on which a surface layer of HDPE may be formed. In this case, the intermediate layer may be formed as multiple layers. Also, part or all of the intermediate layer may be formed of LDPE. HDPE is defined as having a material density of 0.942 (g/cm ³ ) or more, and LDPE is defined as having a material density of less than 0.942 (g/cm ³ ). be.

For example, four bundles of optical fiber units 32 are accommodated in each slot groove 16 in FIG. The optical fiber unit 32 is formed by, for example, twisting a plurality of 12 core optical fiber ribbons 31 together. More specifically, for example, a plurality of 12-core optical fiber ribbons 31 may be laminated, twisted spirally, and bundled with a bundle material (not shown) for identification. In addition, the optical fiber ribbon 31 may have an intermittent structure.

Around each optical fiber core wire constituting the optical fiber tape core wire 31, a tape coating made of ultraviolet curable resin or the like is provided. The optical fiber core wire constituting this optical fiber tape core wire 31 is a so-called optical fiber bare wire, which is a glass fiber with a standard outer diameter of 125 μm coated with a coating with an outer diameter of about 250 μm. Although it was applied
The diameter of the glass fiber may be about 100 μm, and the outer diameter of the coating may be about 200 μm or 180 μm. Moreover, the number of optical fibers forming the optical fiber ribbon 31 is arbitrary.

The slot rod 10 is wound with a pressing winding tape 33 so that the optical fiber unit 32 does not protrude, and is put together in, for example, a round shape.

The outer side of the pressing tape 33 is covered with a cable jacket 34 made of, for example, PE (polyethylene), PVC (polyvinyl chloride), or the like, and is formed, for example, in a round shape.

[Manufacturing slot rod for optical fiber cable]
Next, referring to FIG. 3, a manufacturing process of a slotted rod for an optical fiber cable according to one aspect of the present disclosure will be described. FIG. 3 is a schematic diagram of the apparatus for manufacturing slot rods for optical fiber cables of FIG.

A tension member 11 such as a steel wire is delivered from a delivery device 41 , preheated to a predetermined temperature by a preheating device 42 , and introduced into an intermediate layer extruder 43 . The intermediate layer crosshead 44 of the intermediate layer extruder 43 extrudes, for example, a resin in the horizontal direction to cover the tension member 11 with the resin for forming the intermediate layer 12 . After that, the intermediate layer 12 is cooled and hardened by the intermediate layer cooling device 45 .

Next, the tension member 11 with the intermediate layer 12 formed thereon is introduced into the outermost layer extruder 50 . The outermost layer crosshead 51 of the outermost layer extruder 50 extrudes, for example, a resin in the horizontal direction to cover the intermediate layer 12 with the resin for forming the outermost layer 13 . At this time, SZ-shaped or spiral grooves are formed in the resin by the die of the outermost layer crosshead 51 .

The slot rod 10 coming out of the outermost layer extruder 50 is introduced into the outermost layer cooling device 52 . The outermost layer cooling device 52 is configured to be able to cool the slot rod 10 at a faster cooling rate than natural cooling. Like the outermost layer cooling device 52, the intermediate layer cooling device 45 is also configured to be able to cool the slot rod 10 at a faster cooling rate than natural cooling. The slot rod 10 forcedly cooled by the outermost layer cooling device 52 is taken up by the take-up capstan 53 and then taken up by the take-up machine 54 .

In FIG. 3, the intermediate layer extruder 43 is described as an example in which one intermediate layer is formed by one unit. In order to provide a plurality of layers, the resin may be coated around the tension member 11 a plurality of times (for example, 2 to 4 times). It is also possible to use a push extruder that forms multiple layers at the same time.

[Regarding eccentricity of intermediate layer of slot rod for optical fiber cable]
4A is a cross-sectional view of the slotted rod for the fiber optic cable of FIG. 2; FIG. FIG. 4A shows a cross-sectional view in a direction perpendicular to the longitudinal direction of the slotted rod during extrusion of the slotted rod of the present disclosure. FIG. 4B is a partially enlarged view of the vicinity of the central portion in FIG. 4A. 4A and 4B, the upper side of the drawing is the upper side during extrusion molding (hereinafter referred to as "upper side during extrusion molding"), and the lower side of the drawing is the lower side during extrusion molding (hereinafter referred to as "upper side during extrusion molding"). "downward"). The position in the outermost layer crosshead 51 when defining the upper and lower sides is not particularly limited, but for example, a predetermined position near the center or near the exit in the outermost layer crosshead 51 is the position of
4A and 4B, reference numeral 16U denotes the uppermost slot groove during extrusion molding, and reference numeral 16D denotes the lowermost slot groove during extrusion molding. In FIG. 4B, a [mm] and b "mm" are the slot groove bottom thickness of the outermost layer, and the slot groove bottom thickness of the outermost layer at the central portion of the slot groove, that is, at the intermediate position between the two slot ribs sandwiching the slot groove. is. Then, a [mm] is the outermost slot groove bottom thickness of the lowermost slot groove 16D (corresponding to the first slot groove), and b [mm] is the uppermost slot groove 16U (second slot groove). ) is the slot groove bottom thickness of the outermost layer.

In this embodiment, it is set so that a>b. As shown in FIG. 4B, with respect to the outermost layer 13, the central layer 20 (intermediate layer 12) is eccentric upward in the drawing. By setting in this way, it is possible to suppress rib collapse during extrusion molding of the slot rod 10 . In addition, how to select the first slot groove and the second slot groove in the present disclosure is not limited to the bottom and the top. For example, when the slot rod is extruded, the first slot groove is downward, If the second slot groove is in an upward relationship, it is possible to suppress rib collapse during extrusion molding of the slot rod.

The outermost layer 13 of the slot rod 10 is hardened by cooling the slot rod 10 extruded in the outermost layer crosshead 51 of the outermost layer extruder 50 by the outermost layer cooling device 52 . In this process, if the central layer 20 is positioned at the center of the slot rod 10 or below the center of the slot rod 10, the thickness of the bottom of the uppermost slot groove 16U will increase. When the thickness of the groove bottom increases, it becomes difficult to cool the uppermost groove bottom, and it takes time to harden the resin in the uppermost part. Therefore, there is a risk that the slot ribs 15 positioned above, particularly the slot ribs 15 sandwiching the uppermost slot groove 16U, may collapse due to the weight of the slot ribs 15 themselves.

Therefore, in the present embodiment, by setting a>b and reducing the thickness of the groove bottom in the uppermost slot groove 16U, the time required for curing the resin in the uppermost slot is shortened, and the uppermost slot groove 16U is positioned upward. This is effective in reducing tilting of the slot ribs 15 . In particular, in a slot rod having a relatively large diameter, for example, a slot rod having an outer diameter of 20 mm or more and a rib height of 7 mm or more, the effect of reducing the inclination of the slot rib 15 is high. The diameter of the slot rod in this embodiment is not particularly limited. be.

[Experimental example]
An experiment was conducted to see how much the tilting of the slot rib 15 can be reduced by setting a>b. Table 1 shows the results.

[Experiment target]
In the slot rod 10 with the number of slot grooves = 8, the eccentricity (ab) / 2 of the center layer 20 is (1) - 0.2 mm
(2) -0.1mm
(3) 0 mm
(4) 0.1mm
(5) 0.2mm
5 types of slot rods were tested. The number of samples was N=10 under each condition.

Here, the eccentricity is set to (ab)/2 because the slot groove bottom thickness of the outermost layer in the lowermost slot groove 16D is a [mm], and the outermost slot groove in the uppermost slot groove 16U When the bottom thickness is b [mm], the lowermost slot groove 16D and the uppermost slot groove 16U face each other with the center layer 20 therebetween. This is because the amount of eccentricity upward from the center Or of is half the amount of (ab) (see FIG. 4B).

[Experiment contents]
A sample of the slot rod 10 was sliced to a thickness of about 0.5 mm, and a cross-sectional image was taken with a projector with a magnification of 10 times. The rib tilt angle was measured using a scale on the cross-sectional image taken. The judgment criteria were "good" when the rib inclination angle θ was 10 degrees or less, and "bad" when it was greater than 10 degrees. FIG. 5 is an explanatory view of rib collapse of the optical fiber cable slot rod of FIG. The rib inclination angle θ is defined by the center line 15C of the slot rib 15 in the original posture (the straight line 15C passing through the center O of the slot rod 10 and the center of the tip width of the slot rib 15 in the original posture in the sectional view of FIG. ) and the center line 15M of the slot rib 15 in the collapsed posture (the straight line 15M passing through the center O of the slot rod 10 and the center of the tip width of the slot rib 15 in the collapsed posture in the sectional view of FIG. 5). It is the angle to make.
[Experimental result]

As a result of this experiment, item numbers 1 to 3 are defective, and item numbers 4 to 5 are good.
(ab)/2≧0.1 mm
It can be seen that the effect of suppressing the collapse of the slot ribs 15 of the slot rod 10 of the present embodiment is high when .

[Manufacturing method in which the central layer is decentered upward]
In embodiments of the present disclosure, the center layer 20 is eccentric above the slot rod 10 such that a>b during extrusion. The condition of a>b is maintained even if the slot groove 16 of the slot rod 10 is SZ-shaped or helical. A method of manufacturing while maintaining the condition of a>b in this way will be described below.

FIG. 6 is an illustration of an outermost layer extruder 50 according to one aspect of the present disclosure. The outermost layer crosshead 51 of the outermost layer extruder 50 is inclined downward in FIG. 6 by an angle α in the vertical direction with respect to the horizontal plane Ph. That is, the resin for the outermost layer is extruded in the direction of Pu. As a method of tilting by the angle α, for example, there is a method of tilting the entire outermost layer extruder 50 by the angle α.

When the outermost layer 13 of the slot rod 10 is extruded, the amount of resin supplied to each part, the arrangement of the central layer 20, etc. can be adjusted by inclining the outermost layer crosshead 51 downward by an angle α with respect to the horizontal plane Ph. , the central layer 20 can be eccentrically upward with respect to the slot rod 10 .

In the cross-sectional view of FIG. 5, c [mm] is the slot rib top width at the tip of the slot rib 15, and d [mm] is the length of a straight line connecting the centers of adjacent slot ribs 16. ], c and d are 1.0 mm ≤ c < d ≤ 8.0 mm
If the range satisfies the relation However, the present disclosure is not limited to the conditions.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above.
In addition, each element included in the above-described embodiments can be combined as long as it is technically possible, and combinations of these are also included in the scope of the present disclosure as long as they include the features of the present invention.

Reference Signs List 10 Slot rod 11 Tension member 12 Intermediate layer 13 Outermost layer 15 Slot rib 15C Center line 15M of slot rib 15 in original posture 15M in fallen posture Center line 16 of slot rib 15 Slot groove 16D Lowermost slot groove 16U Lowermost slot groove 20 Central layer 30 Optical fiber cable 31 Optical fiber tape core wire 32... Optical fiber unit 33... Press winding tape hole 34... Cable jacket 40... Manufacturing device 41... Feeding device 42... Heating device 43... Intermediate layer extruder 44 Intermediate layer crosshead 45 Intermediate layer cooling device 50 Outermost layer extruder 51 Outermost layer crosshead 52 Outermost layer cooling device 53 Taking over Capstan 54 Winding machine

a Slot groove bottom thickness of the outermost layer in the lowermost slot groove 16D b... Slot groove bottom thickness of the outermost layer in the uppermost slot groove 16U c...Slot rib upper width d... Slot rib lower width θ Rib tilt angle Pu Pushing direction Ph of slot rod 10 Horizontal plane α Angle of Pu with respect to Ph

Claims (8)

having a center layer with a tension member embedded in the center and an outermost layer covering the radially outer side of the center layer,
A slot rod for an optical fiber cable, wherein the outermost layer is formed with a plurality of slot ribs extending radially from the central layer, and slot grooves are formed between the slot ribs,
The slot grooves include at least a first slot groove and a second slot groove provided at a position different from the first slot groove,
When the thickness of the outermost layer at the center of the bottom of the slot groove is a [mm] in the first slot groove and b [mm] in the second slot groove, a and b satisfy a>b
A slotted rod for optical fiber cables that satisfies the relationship of 2. The slotted rod for an optical fiber cable according to claim 1, wherein said first slot groove and said second slot groove face each other across said central layer. a and b are (ab)/2≧0.1mm
3. The slot rod for an optical fiber cable according to claim 1, which satisfies the relationship: The slotted rod for an optical fiber cable according to any one of claims 1 to 3, wherein the slot groove is SZ-shaped or helical. The material of the outermost layer and the central layer is resin,
The slot rod for an optical fiber cable according to any one of claims 1 to 4, wherein the density of the resin of the outermost layer is higher than the density of the resin of the central layer. The density of the resin of the outermost layer is 0.942 g/cm ³ or more,
The upper width of the slot rib at the tip of the slot rib is c [mm],
When d [mm] is the bottom width of the slot rib, which is the length of the straight line connecting the centers of the groove bottoms of the adjacent slot grooves, c and d are 1.0 mm ≤ c < d ≤ 8.0 mm.
6. The slot rod for an optical fiber cable according to any one of claims 1 to 5, satisfying the relationship of An optical fiber cable comprising: the optical fiber cable slot rod according to any one of claims 1 to 6; and an optical fiber unit housed in the slot groove. 7. The method of manufacturing a slotted rod for an optical fiber cable according to any one of claims 1 to 6, wherein the extrusion direction of the slot rib is inclined downward with respect to a horizontal plane during extrusion molding.

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