JP2018112604A - Optical cable and method of manufacturing optical cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical cable that makes it possible to attain enlargement of a housing part of optical fibers and be also easily divided.SOLUTION: An optical cable 100 comprises: an optical fiber unit 10 that is formed by tying a plurality of optical fibers 3 into a bundle; a pair of tension members 20 disposed so as to hold the optical fiber unit therebetween; and a sheath 30 that covers the optical fiber unit and the pair of tension members and in which notches 32 are also formed in an outer peripheral part. Slits 36 which communicate with a housing part housing the optical fiber unit are disposed right below the notches inside the sheath.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical cable and a method for manufacturing the optical cable.

  Patent Document 1 describes an optical fiber cable having a rectangular cross section provided with release paper (separator).

  Patent Document 2 describes an optical fiber cable in which a gap is formed on the outer periphery of a part of a tension member (strength member).

JP 2013-160882 A Japanese Patent Laying-Open No. 2006-6464

IEICE 2014 General Conference B-10-11 2015 IEICE Society Conference B-10-5

  According to the optical fiber cable described in Patent Document 1, since it is necessary to embed the separator in the jacket, the space for accommodating the optical fiber is reduced by the amount of the separator.

  The optical fiber cable described in Patent Document 2 does not include a separator. However, in the optical fiber cable described in Patent Document 2, since it is necessary to dispose a tensile body immediately below the notch, it is necessary to dispose two tensile bodies in accordance with the interval between the notches. As a result, the interval between the two strength members cannot be increased, and the space for accommodating the optical fiber between the two strength members is reduced. (In the first place, in the configuration of Patent Document 2, since a gap is formed around the tensile strength body, there is a possibility that the original function of the tensile strength body (function to resist the shrinkage of the jacket) may not be achieved.) In the optical fiber cable described in Document 2, the blade of the dividing tool hits the strength member, and as a result, there is a possibility that it is difficult to slide the dividing tool with respect to the optical fiber cable.

  It is an object of the present invention to increase the capacity of an optical fiber housing and to allow easy division.

  A main invention for achieving the above object includes an optical fiber unit in which a plurality of optical fibers are bundled, a pair of tensile members arranged so as to sandwich the optical fiber unit, the optical fiber unit, and the pair of tensile strengths. And a jacket having a notch formed on the outer periphery thereof, and a slit connected to the housing portion housing the optical fiber unit is disposed immediately below the notch inside the jacket. It is an optical cable characterized by being made.

  Other characteristics of the present invention will be made clear by the description and drawings described later.

  ADVANTAGE OF THE INVENTION According to this invention, while aiming at the expansion of the accommodating part of an optical fiber, it can divide | segment easily.

1A and 1B are cross-sectional views of the optical cable of the present embodiment. FIG. 1A is a cross-sectional view of an optical cable with a support line, and FIG. 1B is a cross-sectional view of an optical cable without a support line. It is explanatory drawing of the optical fiber tape 1 of an intermittent connection type. 3A to 3D are explanatory diagrams of the interval between the slits 36. 3A is a diagram showing a case where the gap D2 of the slit 36 is wider than the diameter D1 of the optical fiber 3 (D2> D1), and FIG. 3B is a diagram where the gap D2 of the slit 36 is larger than the diameter D1 of the optical fiber 3. It is a figure which shows the case (D2> D1) which is also narrow. 3C is a diagram showing a case where the slit interval D2 is narrowed toward the housing portion 34, and FIG. 3D is a diagram showing a case where the optical fiber 3 is wrapped with the press-wound tape 14. FIG. 4A and 4B are diagrams illustrating a state when the outer jacket 30 of the optical cable 100 is divided using a dividing tool. It is explanatory drawing of the manufacturing system 50 of an optical cable. 3 is a schematic cross-sectional view of an outlet portion of the extruder 53. FIG.

  At least the following matters will be apparent from the description and drawings described below.

An optical fiber unit in which a plurality of optical fibers are bundled, a pair of tensile members disposed so as to sandwich the optical fiber unit, and the optical fiber unit and the pair of tensile members are covered, and a notch is formed on an outer peripheral portion. An optical cable is characterized in that a slit connected to a housing portion that houses the optical fiber unit is disposed immediately below the notch inside the housing. It becomes.
According to such an optical cable, since the separator is not embedded in the jacket, the optical fiber housing portion can be expanded. Moreover, since the slit is arrange | positioned directly under a notch, a jacket can be divided | segmented easily by making a cut according to a notch.

  The gap between the slits is preferably narrower than the diameter of the optical fiber. Thereby, it can suppress that an optical fiber penetrates into a slit, and can suppress degradation of a transmission characteristic.

  The gap between the slits is preferably narrower toward the housing part. Thereby, even if the clearance gap of a slit is not narrower than the diameter of an optical fiber in all the area | regions of a slit, it can suppress that an optical fiber penetrates into a slit.

  The distance between the pair of strength members is preferably wider than the distance between the notches. Thereby, an accommodating part can be enlarged. Further, since the blade of the dividing tool does not hit the tensile strength body, the dividing tool can be smoothly slid.

  The optical fiber unit is preferably configured by a plurality of the optical fibers being wrapped in a press-wound tape. Thereby, when forming a jacket, it can prevent that an optical fiber bites into the inside of a jacket.

  The presser winding tape is preferably a water absorbing tape. Thereby, even if water permeates into the cable, running water in the cable can be prevented.

  The optical fiber unit is preferably configured by being wrapped in the press-wound tape in a state where the plurality of optical fibers constituting the intermittently connected optical fiber tape are twisted. Thereby, it can suppress that an optical fiber penetrates into a slit irrespective of the magnitude | size of the clearance gap between slits.

Supplying an optical fiber unit in which a plurality of optical fibers are bundled to the extruder; supplying a pair of strength members to the extruder while sandwiching the optical fiber unit from a predetermined direction; and By extruding the resin in the machine, the resin is inserted between the optical fiber unit and the tensile body while covering the optical fiber unit and the pair of tensile bodies, thereby forming a notch in the outer peripheral portion. And forming a slit connected to a housing portion housing the optical fiber unit immediately below the notch inside the jacket when forming the jacket. An optical cable manufacturing method characterized by the above is clarified.
According to such an optical cable manufacturing method, the optical fiber housing portion can be enlarged, and can be easily divided when dividing the jacket.

  The extruder is disposed on a downstream side of the die having a die hole, a nipple for guiding the optical fiber unit and the pair of strength members to the die hole, and the nipple and the die hole. It is desirable to provide a slit forming plate for forming the slit. Thereby, a slit can be easily formed in the inside of the jacket.

  It is desirable to release heat from the slit forming plate. Thereby, the temperature drop of the molten resin in contact with the slit forming plate is accelerated, so that the slit shape is not easily broken due to an increase in the viscosity of the molten resin or a transition to a semi-molten state. That is, it is possible to prevent the inner wall surfaces of the slit from being connected (the upper surface and the lower surface of the slit are separated).

  It is desirable that the slit forming plate is in contact with the optical fiber unit. As a result, the slit forming plate is cooled by the optical fiber unit, and the temperature of the molten resin in contact with the slit forming plate is rapidly lowered, so that the slit shape is not easily collapsed due to an increase in the viscosity of the molten resin or a transition to a semi-molten state. That is, it is possible to prevent the inner wall surfaces of the slit from being connected (the upper surface and the lower surface of the slit are separated).

=== Embodiment ===
<Configuration>
1A and 1B are cross-sectional views of the optical cable of the present embodiment. FIG. 1A is a cross-sectional view of an optical cable with a support line, and FIG. 1B is a cross-sectional view of an optical cable without a support line.

  The optical cable shown in FIG. 1A includes a support line 200 and a cable body 100. The support wire 200 is configured by covering a steel wire or the like with a jacket. The support wire 200 and the cable body 100 are connected by a neck portion 200A.

  When the support line 200 and the cable body 100 are branched at the neck portion 200A of the optical cable shown in FIG. 1A, the configuration of the cable body is as shown in FIG. 1B.

  In the following description, both the optical cable supporting line 200 of FIG. 1A (cable body 100) and the optical cable 100 of FIG. 1B from the beginning are simply referred to as “optical cables (optical fiber cables)”. 100 is attached.

  In the following description, a long side direction, a short side direction, and a longitudinal direction are defined as shown in the figure. The long side direction (or the width direction and the left-right direction) is a direction along the long side of the cross section of the optical cable 100, and is a direction in which the pair of strength members 20 are arranged. The short side direction (or thickness direction, vertical direction) is a direction along the short side of the cross section of the optical cable 100 and is a direction orthogonal to the long direction in the cross section. The longitudinal direction is a direction (normal direction of the cross section) along the linear strength member 20 of the optical cable 100.

  The optical cable 100 includes an optical fiber unit 10, a strength member 20, and a jacket 30.

  The optical fiber unit 10 is a unit (aggregate) in which a plurality of optical fibers 3 are bundled. Here, the optical fiber unit 10 is configured as a unit in which a plurality of optical fibers 3 are wrapped with a press-wound tape 14. The optical fiber unit 10 may also be referred to as “optical cable core”, “optical fiber core”, “core unit”, or simply “unit”. The plurality of optical fibers 3 are configured by bundling one or a plurality of intermittently fixed optical fiber tapes.

  FIG. 2 is an explanatory diagram of the intermittently connected optical fiber tape 1. The right view of FIG. 2 is a cross-sectional view taken along the line AA or BB in the perspective view of the left view.

  The intermittently connected optical fiber tape 1 is an optical fiber tape 1 in which a plurality of optical fibers 3 are connected in parallel. Two adjacent optical fibers 3 are connected by a connecting portion 5. A plurality of connecting portions 5 that connect two adjacent optical fibers 3 are intermittently arranged in the longitudinal direction. Moreover, the some connection part 5 of the optical fiber tape 1 is arrange | positioned intermittently two-dimensionally in the longitudinal direction and the width direction. The connecting portion 5 is formed by applying an ultraviolet curable resin serving as a connecting agent and then curing it by irradiating with ultraviolet rays. In addition, it is also possible to comprise the connection part 5 with a thermoplastic resin. A region other than the connecting portion 5 between the two adjacent optical fibers is a non-connecting portion 7 (separating portion). In the unconnected portion 7, the adjacent two optical fibers 3 are not restrained. As a result, the optical fiber tape 1 can be rounded into a cylindrical shape (bundle) or folded, and a large number of optical fibers 3 can be accommodated at high density. When the optical fiber 3 is separated from the optical fiber tape 1, the operator breaks the connecting portion 5 by tearing between the optical fibers 3.

  The intermittently connected optical fiber tape 1 is not limited to that shown in FIG. For example, the number of cores of the optical fiber tape 1 may be changed. Moreover, you may change arrangement | positioning of the connection part 5 arrange | positioned intermittently.

  In this embodiment, the plurality of optical fibers 3 constituting the intermittently connected optical fiber tape 1 are wrapped in a press-wound tape 14 in a twisted state. As a result, the optical fibers 4 can be mounted with high density (can be multi-fibered). Further, when the optical fiber 3 is wound around a drum, it is possible to suppress the deterioration of transmission loss. The plurality of optical fibers 3 are twisted in an SZ shape.

  The presser winding tape 14 is a member that wraps the plurality of optical fibers 3. By wrapping the optical fiber 3 with the press-wrapping tape 14, it is possible to prevent the optical fiber 3 from being embedded (biting into) the outer cover 30 when the outer cover 30 is formed of molten resin. As the presser winding tape 14, a polyimide tape, a polyester tape, a polypropylene tape, a polyethylene tape, or the like is used. In addition, a nonwoven fabric can be used as the presser winding tape 14. In this case, the nonwoven fabric used is a tape formed of polyimide, polyester, polypropylene, polyethylene or the like. The presser winding tape 14 may be a non-woven fabric bonded with a film such as a polyester film. Furthermore, a water-absorbing tape in which water-absorbing powder is adhered to a nonwoven fabric can be used as the presser winding tape 14. In this case, even if water enters the cable, running water in the cable can be prevented.

  The tensile body 20 is a member that resists the contraction of the outer cover 30 and suppresses distortion and bending applied to the optical fiber unit 10 (particularly, the optical fiber 3) due to the contraction of the outer cover 30. The strength member 20 is a linear member and is embedded in the outer cover 30. As the material of the strength member 20, a non-metallic material or a metallic material can be used. As the non-metallic material, for example, glass FRP (GFRP), aramid fiber reinforced plastic (KFRP), and polyethylene fiber reinforced plastic (FRP) can be used. As the metallic material, a metal wire such as a steel wire can be used.

  The optical cable 100 of the present embodiment has two (a pair) strength members 20. The two strength members 20 are arranged at an interval in the long side direction. Further, the two strength members 20 are arranged so as to sandwich the optical fiber unit 10 from both sides in the long side direction. The interval W2 between the two strength members 20 (the interval between the inner edges of the strength members 20) is wider than the interval M between the notches 32 arranged side by side (W2> M). For example, in the present embodiment, the interval M is 2.8 mm, and the interval W2 is 3 mm or more. For this reason, the accommodating part 34 can be formed widely compared with the case where the tensile strength body 20 is arrange | positioned directly under the notch 32. FIG.

  The jacket 30 is a member that covers the optical fiber unit 10 and the strength member 20. The outer shape (cross section) of the jacket 30 is substantially rectangular. In the present embodiment, flame retardant polyolefin (for example, flame retardant polyethylene (PE)) is used as the material of the jacket 30. As the polyethylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, or the like can be used. Further, a non-halogen material (for example, a hydrated metal compound such as magnesium hydroxide or aluminum hydroxide) is contained as an auxiliary material. Since the optical cable 100 of this embodiment does not have the separator embedded in the jacket 30, the flame retardancy can be further improved. In addition, as a material of the jacket 30, polyolefin such as polypropylene (PP), polyvinyl chloride (PVC), polyamide, or fluororesin (ETFE, PTFE, etc.) may be used.

  The jacket 30 is provided with a notch 32, a housing portion 34, and a slit 36.

  The notch 32 is for ensuring the division of the jacket 30. The optical cable 100 is divided by cutting the notch 32 of the jacket 30 with a dividing tool (see FIG. 4). In the present embodiment, four notches 32 are formed on the outer periphery of the jacket 30. More specifically, a pair (two) of notches 32 are provided in the long side direction (left and right) on the upper surface and the lower surface of the jacket 30, respectively. The upper and lower notches 32 are provided at the same position in the long side direction (aligned vertically). However, one notch 32 may be provided on the upper and lower sides alternately.

  The accommodating portion 34 is a space for accommodating the optical fiber unit 10 and is formed inside the outer jacket 30 (inside the pair of notches 32 arranged side by side).

  The slit 36 is a slit connected to the accommodating portion 34. The slits 36 are respectively provided in the four corners (upper right corner, upper left corner, lower right corner, lower left corner) of the accommodating portion 34 along the long side direction. In the following, description will be made mainly using the slit 36 at the upper left corner, but the same applies to the other slits 36.

  The upper surface 36A (outer surface: see FIG. 3D) and the lower surface 36B (inner surface: see FIG. 3D) of the slit 36 are separated. In the present embodiment, a gap is formed between the upper surface 36A and the lower surface 36B of the slit 36. However, as long as the upper surface 36A and the lower surface 36B of the slit 36 are separated, the upper surface 36A and the lower surface 36B may be in contact with each other.

  The slit 36 is disposed immediately below the notch 32. That is, the slit 36 is arranged on the extension of the notch 32 in the short side direction. When the notches 32 are arranged vertically (in the short side direction) as in the present embodiment, the slits 36 are arranged so as to cross the line connecting the notches 32 arranged vertically. Therefore, the longitudinal length (distance between the right end and the left end) W1 of the slit 36 shown in FIG. 1B is wider than the interval M between the notches 32 arranged side by side (W1> M).

  A jacket 30 is formed between the slit 36 and the notch 32. Therefore, the blade of the dividing tool cuts the outer cover 30 between the upper surface 36 </ b> A of the slit 36 and the notch 32.

  A jacket 30 is also formed inside the lower surface 36B of the slit 36. As a result, when the blade of the split tool passes through the slit 36, the blade hits the outer cover 30 on the lower surface of the slit 36. As described above, even if the blade of the dividing tool passes through the slit 36, it hits the outer cover 30, and therefore, in this embodiment, the dividing tool can be slid smoothly compared to the case where it hits the strength member 20.

-About the clearance gap of a slit FIGS. 3A-3D is explanatory drawing about the clearance gap of the slit 36. FIG.

  FIG. 3A is a diagram illustrating a case where the gap D2 of the slit 36 is wider than the diameter D1 of the optical fiber 3 (D2> D1). However, here, it is assumed that the optical fiber 3 is not wrapped with the presser winding tape 14. In this case, as shown in the figure, the optical fiber 3 may enter the slit 36. As a result, there is a possibility that the transmission characteristics are deteriorated.

  FIG. 3B is a diagram showing a case where the gap D2 of the slit 36 is narrower than the diameter D1 of the optical fiber 3 (D2 <D1). In this case, the optical fiber 3 can be prevented from entering the slit 36. Therefore, it is possible to suppress deterioration of transmission characteristics.

  FIG. 3C is a diagram illustrating a case in which the slit interval D2 is narrowed toward the accommodating portion 34 side. In this case, it is desirable that the distance D <b> 2 between the slits 36 is narrower than the diameter D <b> 1 of the optical fiber 3 in a portion connected to the housing portion 34. If this condition is satisfied, the optical fiber 3 does not enter the slit 36, so that D2 <D1 does not have to be satisfied in all regions of the slit 36.

  FIG. 3D is a diagram showing a case where the optical fiber 3 is wrapped with the presser winding tape 14. By wrapping the optical fiber 3 with the press-wound tape 14, it is possible to further suppress the optical fiber 3 from entering the slit 36. Further, by wrapping the optical fiber 3 with the presser winding tape 14, it is possible to prevent the optical fiber 3 from biting into the outer cover 30.

<State at the time of division>
4A and 4B are diagrams illustrating a state when the outer jacket 30 of the optical cable 100 is divided using a dividing tool. The dividing tool (not shown) has four blades, and the four blades respectively correspond to the four notches 32 formed in the outer cover 30. More specifically, the dividing tool includes an upper lever provided with two blades corresponding to the pair of notches 32 on the upper side of the outer cover 30 and two parts corresponding to the pair of notches 32 on the lower side of the outer cover 30. A lower lever provided with a blade is provided.

  As shown in FIG. 4A, the blades of the division tool are aligned with the upper and lower notches 32, and the division tools (upper lever and lower lever) are pressed inward in the vertical direction. As a result, the blade of the dividing tool cuts the outer cover 30 between the notch 32 and the slit 36, and the outer cover 30 is divided as shown in FIG. 4B. Then, the outer jacket 30 of the optical cable 100 is sequentially divided by sliding in the longitudinal direction while pressing the dividing tool.

  In the present embodiment, the jacket 30 is also formed inside the lower surface of the slit 36. In other words, the inner wall surfaces of the jacket 30 forming the slit 36 are directly opposite to each other immediately below the notch 32. Therefore, when the blade of the dividing tool passes through the slit 36, the blade hits the outer cover 30 on the lower surface of the slit 36. For this reason, compared with the case where the blade of the splitting tool hits the strength member 20 (when the strength member 20 is disposed directly below the notch 32), the split tool can be slid smoothly in this embodiment. .

<Manufacturing method>
FIG. 5A is an explanatory diagram of the manufacturing system 50 of the optical cable 100. The manufacturing system 50 includes a fiber guide part 51, a tape forming part 52, an extrusion molding machine 53, a cooling machine 54, and a drum 55.

  The fiber guide 51 is a guide member that bundles and sends out a plurality of optical fibers 3. The fiber guide portion 51 is a pipe-shaped member, and a plurality of optical fibers 3 are inserted through the internal space of the pipe. A plurality of optical fibers 3 (intermittently connected optical fiber tape 1) are supplied from a supply source (not shown) to the fiber guide portion 51, and are bundled by the fiber guide portion 51.

  The tape forming unit 52 is a forming member that forms the press-wound tape 14 in a cylindrical shape (spiral shape) so as to wrap the plurality of optical fibers 3. The downstream end of the fiber guide portion 51 is inserted into the tape forming portion 52, and the tape forming portion 52 shapes the press-wound tape 14 into a cylindrical shape so as to wrap the downstream end of the fiber guide portion 51. The tape forming unit 52 supplies the optical fiber unit 10 in which the plurality of optical fibers 3 are wrapped with the press-wound tape 14 to the extruder 53.

  The extrusion molding machine 53 is an apparatus for extruding the outer jacket 30 of the optical cable 100. The extrusion machine 53 is supplied with the optical fiber unit 10 and a pair of strength members 20. The pair of strength members 20 are supplied so as to sandwich the optical fiber unit 10 from a predetermined direction (long side direction in FIG. 1). Then, the optical cable 100 in which the optical fiber unit 10 and the pair of strength members 20 are collectively covered with the jacket 30 is manufactured by the extruder 53. The details of the extruder 53 will be described later.

  The cooler 54 is a cooling device that cools the jacket 30 of the optical cable 100. When the jacket 30 is cooled, the jacket 30 contracts. However, since the load at the time of contraction of the jacket 30 at the time of cooling is applied to the strength member 20, the distortion of the optical fiber unit 10 (particularly the optical fiber 3) can be suppressed.

  The drum 55 is a member that winds up the optical cable 100. The manufactured optical cable 100 is wound around the drum 55 and shipped.

  FIG. 5B is a schematic cross-sectional view of the exit portion of the extruder 53.

  The extrusion molding machine 53 includes a resin flow path 61, a die 62, a nipple 63, and a slit forming plate 64.

  The resin flow path 61 is filled with a molten resin 30 ′ that forms the outer cover 30.

  The die 62 is a die provided at the outlet of the extrusion molding machine 53 and has a die hole 62 </ b> A having a shape corresponding to the outer shape of the optical cable 100. The molten resin 30 'is extruded from the die hole 62A.

  The nipple 63 guides the optical fiber unit 10 and the pair of strength members 20 to the die 62 (die hole 62A). The tip of the nipple 63 is arranged so as to protrude on the same plane as the opening surface of the die hole 62A or on the downstream side of the opening surface of the die hole 62A. Then, the optical fiber unit 10 and the pair of strength members 20 guided by the nipple 63 are pushed out from the die hole 62 </ b> A together with the molten resin 30 ′ in the resin flow path 61.

  The slit forming plate 64 is a member for forming the slit 36 and is disposed so as to protrude from the downstream side of the nipple 63 by a predetermined distance (for example, about 5 cm). Further, the slit forming plate 64 is disposed so as to protrude downstream from the die hole 62A. The slit forming plate 64 is disposed so as to form the slit 36 immediately below the notch 32. The pair of slit forming plates 64 are arranged so as to sandwich the optical fiber unit 10 sent out from the nipple 63 from above and below.

  The slit forming plate 64 contacts the molten resin 30 ′ extruded from the die hole 62 </ b> A and contacts the optical fiber unit 10 supplied from the nipple 63. By this contact, the slit forming plate 64 is cooled by the optical fiber unit 10. Further, since the temperature of the molten resin 30 ′ in contact with the cooled slit forming plate 64 is rapidly lowered, the slit shape is not easily collapsed due to an increase in viscosity of the molten resin 30 ′ or a transition to a semi-molten state. That is, the inner wall surfaces of the slits can be prevented from being connected to each other, and the upper surface 36A and the lower surface 36B of the slit 36 are separated (the slit 36 is formed). The slit forming plate 64 may not be in contact with the optical fiber unit 10 as long as the heat of the slit forming plate 64 can be released.

  As described above, in this embodiment, when the outer cover 30 is extruded, the slit forming plate 64 forms the slit 36 connected to the housing portion 34 of the optical fiber 3 immediately below the notch 32 of the outer cover 30. Yes. Thereby, the accommodating part 34 of the optical fiber 3 can be expanded, and when the jacket 30 is divided, it can be easily divided.

  Moreover, the slit 36 connected with the accommodating part 34 of the optical fiber 3 can be easily formed by arranging the slit forming plate 64 on the downstream side of the nipple 63 and the die hole 62A.

=== Others ===
The above-described embodiments are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be modified and improved without departing from the gist thereof, and it goes without saying that the present invention includes equivalents thereof.

1 optical fiber tape, 3 optical fiber,
5 connected parts, 7 unconnected parts,
10 optical fiber unit, 14 presser winding tape,
20 Tensile body, 30 outer jacket, 30 ′ molten resin 32 notch, 34 housing portion, 36 slit,
50 manufacturing systems, 51 fiber guides,
52 tape forming section, 53 extrusion molding machine,
54 coolers, 55 drums,
61 resin flow path, 62 dice, 62A dice hole,
63 nipple, 64 slit forming plate,
100 optical cable, 200 support line,
200A neck

Claims (11)

A bundled optical fiber unit of a plurality of optical fibers;
A pair of strength members arranged to sandwich the optical fiber unit; and
Covering the optical fiber unit and the pair of strength members, and a jacket formed with a notch on the outer periphery,
With
An optical cable characterized in that a slit connected to a housing portion that houses the optical fiber unit is disposed immediately below the notch inside the jacket. The optical cable according to claim 1,
The slit gap is narrower than the diameter of the optical fiber,
An optical cable characterized by that. The optical cable according to claim 1 or 2,
The gap between the slits is narrower toward the housing part.
An optical cable characterized by that. The optical cable according to any one of claims 1 to 3,
An interval between the pair of strength members is wider than an interval between the notches,
An optical cable characterized by that. An optical cable according to any one of claims 1 to 4,
The optical fiber unit is configured by wrapping a plurality of the optical fibers in a press-wound tape,
An optical cable characterized by that. The optical cable according to claim 5,
The presser winding tape is a water absorbing tape,
An optical cable characterized by that. The optical cable according to claim 5 or 6,
The optical fiber unit is configured by being wrapped in the press-wound tape in a state where a plurality of the optical fibers constituting the intermittently connected optical fiber tape are twisted,
An optical cable characterized by that. Feeding a bundled optical fiber unit of a plurality of optical fibers to an extruder;
Supplying a pair of strength members to the extruder while sandwiching the optical fiber unit from a predetermined direction;
By extruding resin in the extruder, the resin is inserted between the optical fiber unit and the tensile body while covering the optical fiber unit and the pair of tensile bodies, and a notch is formed in the outer peripheral portion. Forming a jacket formed of
Have
When forming the jacket, a slit connected to the housing portion that houses the optical fiber unit is formed immediately below the notch inside the jacket.
An optical cable manufacturing method characterized by the above. It is a manufacturing method of the optical cable according to claim 8,
The extruder is
A die having a die hole;
A nipple for guiding the optical fiber unit and the pair of strength members to the die hole;
A slit forming plate that is disposed downstream of the nipple and the die hole, and forms the slit in the jacket;
An optical cable manufacturing method comprising: A method for manufacturing an optical cable according to claim 9,
A method of manufacturing an optical cable, wherein heat of the slit forming plate is released. It is a manufacturing method of the optical cable according to claim 10,
The slit forming plate is in contact with the optical fiber unit;
An optical cable manufacturing method characterized by the above.

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