Cable with traction end and method for manufacturing cable with traction end

Abstract

This cable with a traction end comprises: a cable part having an optical fiber, a tensile strength body, and a sheath; a branch part having a resin part fixed to an end part of the cable part; and a traction part having a traction hose covering the branch part. In the resin part, a hose fixing member, a waterproof member holding part, and an end part of the tensile strength body are embedded.

Description

Cable with a traction end and method for manufacturing a cable with a traction end

[0001] The present invention relates to a cable with a traction end and a method for manufacturing a cable with a traction end. This application claims priority from Japanese Patent Application No. 2024-088964 filed in Japan on May 31, 2024, the content of which is incorporated herein by reference.

[0002] Patent Document 1 discloses a structure in which a sleeve for protecting a branch portion of an optical fiber core wire is provided at an end portion of an optical cable. The optical cable and the sleeve are fixed by engaging means provided on the sleeve.

[0003] Japanese Patent Application Laid-Open No. 2004-294680

[0004] In Patent Document 1, a sleeve having an outer diameter larger than the outer diameter of the optical cable is provided at the end portion of the optical cable. Therefore, when pulling the optical cable into a duct, the traction end of the cable having the sleeve may get caught in the duct, making it difficult to lay the cable. On the other hand, when adopting a structure with a thinner traction end, damage may be caused to the traction portion due to the tension during traction, and the water-stopping function and the connection and fixing function between various components may not be maintained.

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a cable with a traction end having a branch portion capable of suppressing an increase in outer diameter while having a fixing function and a waterproof function of the traction end, and a method for manufacturing a cable with a traction end.

[0006] In order to solve the above problems, the cable with a traction end according to Aspect 1 of the present invention includes a cable portion having an optical fiber, a tensile strength member, and a sheath, a branch portion having a resin portion fixed to an end portion of the cable portion, and a traction portion having a traction hose covering the resin portion. In the branch portion, a hose fixing member, a waterproof member holding portion, and the tensile strength member are embedded.

[0007] Further, in the cable with a traction end according to Aspect 2 of the present invention, the hose fixing member may have an insert nut holding portion and an insert nut held by the insert nut holding portion.

[0008] In addition, in a third aspect of the present invention, in the cable with towing ends of the first aspect, the hose fixing member may be a male thread portion formed on an outer peripheral surface of the resin portion.

[0009] In addition, in a fourth aspect of the present invention, in the cable with towing ends of the first aspect, the hose fixing member may be a convex portion having a protrusion protruding from an outer peripheral surface of the resin portion.

[0010] In addition, in a fifth aspect of the present invention, in the cable with a pulling end according to any one of the first to fourth aspects, the waterproofing member holding portion may be an O-ring holding portion.

[0011] In addition, a method for manufacturing a cable with a towing end according to aspect 6 of the present invention includes attaching a mold to the end of a cable portion having an optical fiber, a tensile strength member, and a sheath, the mold having a hose fixing member, a waterproofing member holding portion, and the tensile strength member extending from the sheath disposed therein, filling the mold with resin, and hardening the resin to form a branch portion, removing the mold, and attaching a towing hose that covers the branch portion.

[0012] According to the above aspects of the present invention, it is possible to provide a cable with a towing end having a branch portion that can prevent the outer diameter from increasing while providing a function of fixing the towing end and a waterproof function, and a method for manufacturing a cable with a towing end.

[0013] 6A is a partial longitudinal sectional view illustrating the structure of a towing-end cable according to the first embodiment. FIG. 1B is a cross sectional view taken along line IB-IB in FIG. 1A. FIG. 1C is a cross sectional view taken along line IC-IC in FIG. 1B. FIG. 1D is a cross sectional view of a hose fixing member according to the first embodiment. FIG. 1E is a partial longitudinal sectional view illustrating a method for manufacturing a towing-end cable according to the first embodiment. FIG. 2 is a view illustrating a process following FIG. 3. FIG. 4A is a cross sectional view taken along line IVB-IVB in FIG. 4A. FIG. 4E is a view illustrating a process following FIG. 4A. FIG. 4F is a view illustrating a cable section having a connector provided at the end of an optical fiber. FIG. 6A is a partial perspective view illustrating the structure of a towing-end cable having a towing end provided at the end of the cable section shown in FIG. 6A. FIG. 6G is a view illustrating a state in which a towing-end cable is laid in a duct between data centers. FIG. 7A is a view taken along line VII-VII in FIG. 7A (cross section of the duct). FIG. 7H is a partial longitudinal sectional view illustrating the structure of a towing-end cable according to the second embodiment. FIG. 7I is a partial longitudinal sectional view illustrating a method for manufacturing a branching section of a towing-end cable according to the second embodiment. 11A , a cross-sectional view taken along line IXB-IXB in FIG. 9A , illustrating the removal of a mold from a branching portion in the method for manufacturing a towing end cable according to the second embodiment. 12A is a partial longitudinal cross-sectional view illustrating the structure of a towing end cable according to the third embodiment. 13A is a partial longitudinal cross-sectional view illustrating the manufacturing method of a branching portion of a towing end cable according to the third embodiment. 14A is a cross-sectional view taken along line XIB-XIB in FIG. 11A, illustrating the removal of a mold from a branching portion in the method for manufacturing a towing end cable according to the third embodiment. 15A is a cross-sectional view taken along line XIB-XIB in FIG. 11A , illustrating the removal of a mold from a branching portion in the method for manufacturing a towing end cable according to the third embodiment. 16A is a cross-sectional view illustrating the manufacturing method of a conventional towing end cable. 17A is a cross-sectional view illustrating the manufacturing method of another conventional towing end cable. 18A is a view illustrating a process subsequent to FIG. 13A . 19A is a view illustrating the structure of another conventional towing end cable.

[0014] 1A to 1C, the towing-end cable 100 includes a cable portion 10, a branching portion 20, and a towing portion 30.

[0015] (Directional Definition) In this embodiment, the longitudinal direction of the towing-end cable 100 is simply referred to as the longitudinal direction, and is represented by the X-axis in the drawings. One side (tip end side) in the longitudinal direction is referred to as the +X side, and the opposite side (base end side) is referred to as the -X side. Furthermore, when viewed from the longitudinal direction, the direction winding around the central axis O of the cable 1 (see FIG. 1B, etc.) is referred to as the circumferential direction, and the direction intersecting the central axis O is referred to as the radial direction. FIGS. 1A and 1C are cross-sectional views of the towing-end cable 100 taken along the central axis O. FIG. 1B is a cross-sectional view of the towing-end cable 100 intersecting the central axis O.

[0016] (Cable portion 10) The cable portion 10 includes a sheath 11, a plurality of optical fibers 12 housed within the sheath 11, and a tensile strength member 13 embedded in the sheath. The cable portion 10 of this embodiment is an optical fiber cable including the optical fibers 12, but the cable portion 10 may house other linear members (e.g., power lines) instead of the optical fibers 12. That is, the cable portion 10 may be a power cable or the like.

[0017] The optical fiber 12 in this embodiment is a plurality of single-core optical fiber core wires. However, the optical fiber 12 may also be a ribbon core wire in which a plurality of parallel-arranged optical fiber core wires are bonded together with a resin or the like. The ribbon core wire may also be a so-called intermittently bonded ribbon core wire in which adjacent optical fibers 12 are bonded to each other with adhesive parts at a fixed interval in the longitudinal direction.

[0018] The strength members 13 are embedded in the sheath 11. In this embodiment, two strength members 13 are provided facing each other across the central axis O (see FIGS. 1B and 1C). By embedding the strength members 13 in the sheath 11, it is possible to suppress elongation and contraction of the sheath 11 in the longitudinal direction. Note that the number and arrangement of the strength members 13 are not limited to the above example and can be changed as appropriate.

[0019] Examples of materials that can be used for the strength members 13 include metal wires (such as steel wires), high-tensile fibers (such as aramid fibers), and fiber-reinforced plastics (FRP). Specific examples of FRP include KFRP, which uses Keppra fibers, and PBO-FRP, which uses polyparaphenylenebenzobisoxazole (PBO). The strength members 13 may have a coating layer to bundle the high-tensile fibers and to enhance adhesion to the sheath 11. In this embodiment, the strength members 13 include high-tensile fibers and resin layers disposed between the high-tensile fibers and around the periphery of the tensile fiber bundle. As will be described in detail later, in the portion extending from the cable portion 10, the resin layer covering the periphery of the tensile fiber bundle is removed, and the tensile fiber bundle is branched into two, resulting in the strength members 13 being embedded in the resin portion 21 of the branching portion 20, as shown in FIGS. 1A to 1C.

[0020] The sheath 11 is formed in a cylindrical shape with its center approximately on the central axis O. The sheath 11 can be made of a polyolefin (PO) resin such as polyethylene (PE), polypropylene (PP), ethylene-ethyl acrylate copolymer (EEA), ethylene-vinyl acetate copolymer (EVA), or ethylene-propylene copolymer (EP), or polyvinyl chloride (PVC), either alone or in combination with other resins. Furthermore, additives such as flame retardants, fillers, or anti-degradants may be added to the material of the sheath 11 depending on the purpose.

[0021] As shown in FIG. 1A, an optical fiber 12 and a tension member 13 extend from an end 10a of a cable portion 10, which is an end of a sheath 11, toward the +X side.

[0022] (Branch 20) The branch 20 includes a resin portion 21, a hose fixing member 22, and a waterproofing member holding member 23. The branch 20 covers the strength members 13 and a portion of the optical fiber 12 extending from the cable 10. The optical fiber 12 extends from a first end 20a on the +X side of the branch 20, and a second end 20b on the −X side of the branch 20 contacts the end 10a of the cable 10. The strength members 13 extend to the first end 20a but are not exposed at the first end face 20s of the branch 20. The strength members 13 may be exposed at the end face 20s of the branch 20 or may extend from the end face 20s. The outer diameter of the branch 20 is equal to or smaller than the outer diameter of the cable 10. That is, the outer diameters of the resin portion 21, the hose fixing member 22, and the waterproofing member holding member 23 are set to be equal to or smaller than the outer diameter of the cable.

[0023] A hose fixing member 22 and a waterproofing member holding portion 23 are embedded in the resin portion 21, and are arranged in this order from the second end 20b toward the +X direction. Note that a plurality of hose fixing members 22 and a plurality of waterproofing member holding portions 23 may be provided, and the arrangement order is not limited to the above example. The resin portion 21 is formed, for example, from a two-component curing epoxy resin or acrylic resin.

[0024] Because the strength members 13 are embedded in the resin portion 21, it can be said that the branch portion 20 grips the tip of the strength member 13 extending through the cable portion 10. Therefore, when the branch portion 20 is pulled in the +X direction, the cable portion 10 can be pulled by the pulling force. In the example shown in FIGS. 1A to 1C, the covering layer has been removed and the strength members 13 that are branched into two in the radial direction are embedded inside the resin portion 21. This allows the strength members 13 and the resin portion 21 of the branch portion 20 to be bonded with an appropriate adhesive force so that they do not separate due to the tension when pulled.

[0025] The hose fixing member 22 has a function of fixing the traction section 30 to the branch section 20. In this embodiment, the hose fixing member 22 has a plurality of insert nuts 22n and an insert nut holding portion 22a that holds the plurality of insert nuts 22n. In this embodiment, the number of insert nuts 22n is four, but is not limited to four. As shown in FIGS. 1B and 1D , the insert nut holding portion 22a is a cylindrical member centered on the central axis O, and the optical fiber 12 that passes through the inner hole 22i and a portion of the resin portion 21 are disposed in the inner hole 22i. The insert nut holding portion 22a is formed of resin. For example, the hose fixing member 22 may be manufactured by insert molding the plurality of insert nuts 22n into the insert nut holding portion 22a.

[0026] The insert nut holding portion 22a is provided with strength member through holes 22t that penetrate in the longitudinal direction X. The strength member through holes 22t are provided in accordance with the number and arrangement of the strength members 13. In this embodiment, the number of strength member through holes 22t is two, the same as the number of strength members 13, and the strength member through holes 22t are provided opposite each other across the central axis O. The strength member through holes 22t open to the +X side and the -X side of the insert nut holding portion 22a. The strength members 13 and the resin portion 21 are arranged inside the strength member through holes 22t.

[0027] Multiple insert nuts 22n are provided at equal circumferential intervals on the outer peripheral surface 22o of the insert nut holding portion 22a. Two of the intermediate portions of two circumferentially adjacent insert nuts 22n are provided with strength member through-holes 22t. The hose fixing member 22 has the strength member through-holes 22t and insert nuts 22n arranged in this manner. Therefore, the longitudinal cross section (cross section IA-IA in FIG. 1B) in the longitudinal direction X passing through two insert nuts 22n facing each other across the central axis O shown in FIG. 1A does not include the strength members 13. For the sake of explanation, only one strength member 13 embedded in the resin portion 21 is shown by a dotted line in FIG. 1A. Two strength members 13 are shown in the longitudinal cross section (cross section IC-IC in FIG. 1B) in the longitudinal direction X passing through two strength member through-holes 22t facing each other across the central axis O shown in FIG. 1C.

[0028] A fixing member B passing through the through-hole 31h of the towing hose 31 is fixed to the insert nut 22n, thereby fixing the branching portion 20 and the towing portion 30. The fixing member B is, for example, a female thread. Here, because the insert nut 22n is provided on the inside of the outer circumferential surface 22o, it is possible to prevent a gap from being formed between the towing hose 31 and the branching portion 20 when the towing hose 31 is disposed radially outside the branching portion 20.

[0029] The hose fixing member 22 is not limited to a configuration including an insert nut 22n. Details will be described in the embodiment below, but for example, a male thread formed on the outer circumferential surface 21a of the resin part 21 may serve as the hose fixing member 22. In this case, to fix the branching part 20 and the traction part 30, a female thread may be provided on the inner wall of the traction hose 31, or the traction hose 31 may be fixed by a member having a female thread. Furthermore, a recess formed on the outer periphery of the resin part 21 may serve as the hose fixing member 22, and a protrusion formed on the inner wall of the traction hose 31 may be fitted into the hose fixing member 22 to fix the traction part 30 to the branching part 20.

[0030] The waterproofing member holding portion 23 is a member for preventing water from entering the inside of the towing-end cable 100 from the connection portion between the branching portion 20 and the pulling portion 30. In this embodiment, the waterproofing member holding portion 23 is an O-ring holding portion 23a that holds an O-ring 24. The O-ring 24 can prevent water from entering the inside of the towing-end cable 100 from a gap between the towing portion 30 and the sheath 11.

[0031] The O-ring holder 23a is cylindrical and centered on the central axis O, and has a recess 23r recessed radially inward from the outer circumferential surface 23o. The recess 23r extends circumferentially along the outer circumferential surface 23o and is formed around the entire circumference of the O-ring holder 23a. An O-ring 24 is disposed inside the recess 23r. The optical fiber 12, the strength member 13, and a portion of the resin portion 21 are disposed in an inner hole 23i of the O-ring holder 23a.

[0032] The waterproofing member holding portion 23 is not limited to the O-ring holding portion 23a, and may have any configuration that can prevent water from entering the inside of the towing-end cable 100 from between the towing portion 30 and the sheath 11. For example, the waterproofing function may be imparted by wrapping a waterproof tape around the resin portion 21 or by providing a valve in the resin portion 21 that prevents water from entering. Also, instead of placing the O-ring 24 in the recess 23r of the O-ring holding portion 23a, a water-absorbing material that absorbs water and expands may be placed therein.

[0033] The insert nut holder 22a and the O-ring holder 23a may each be composed of a single ring-shaped member, or may be composed of two arc-shaped members formed by dividing a ring in half in the circumferential direction. For example, the insert nut holder 22a may be formed by combining arc-shaped members divided in half at the joint surface 221 (see FIG. 1D ) that passes through the two strength member through holes 22t. This is preferable because it eliminates the need to pass the optical fiber 12 through the inner holes 22i and 23i and the strength members 13 through the inner holes 22i and 23i. Note that the insert nut holder 22a and the O-ring holder 23a are not limited to being ring-shaped members that can be disassembled into two members, but may also be ring-shaped members that can be disassembled into three or more members.

[0034] (Towing Section 30) The towing section 30 has a towing hose 31 and a tip section 32 provided at a first end section 31a on the +X side of the towing hose 31.

[0035] The pulling hose 31 is a hose extending in the longitudinal direction X, and accommodates a portion of the sheath 11 at the end 10a, the branching portion 20, and the optical fiber 12 extending from the branching portion 20 in an internal space 31S. In the pulling hose 31, a first end 31a on the +X side is sealed by a tip portion 32, and a second end 31b on the −X side is in contact with and sealed to the end 10a of the cable portion 10. The pulling hose 31 can protect the optical fiber 12 extending from the branching portion 20 while preventing water, dust, and the like from entering the cable with pulling end 100.

[0036] The traction hose 31 is a hose made of, for example, metal or a resin such as polyvinyl chloride, polyolefin resin, fluoropolymer, or thermoplastic elastomer. The traction hose 31 is flexible and strong enough to withstand traction force. The traction hose 31 may be a spiral tube or a tube made of woven fibers (typically resin fibers). Furthermore, the traction hose 31 is not limited to a hose made of only one layer. The traction hose 31 may have multiple layers made of different materials or configurations. For example, the traction hose 31 may have two layers: a metal layer that is a metal tube and a resin layer made of resin and provided radially outside the metal layer.

[0037] The second end 31b of the traction hose 31 covers the sheath 11 of the end 10a and the radially outer side of the branching portion 20. A through hole 31h is formed in the second end 31b at a position corresponding to the insert nut 22n, and the second end 31b is fixed to the branching portion 20 by a fixing member B passing through the through hole 31h. As shown in FIG. 1B , the fixing member B is positioned inside the outer circumferential surface 31o of the traction hose 31. In other words, the head of the fixing member B does not protrude from the outer circumferential surface 31o of the traction hose 31. For example, a counterbore 31h1 corresponding to the diameter and height of the head of the fixing member B may be formed in the radially outer portion of the through hole 31h, or the fixing member B may be tightened into the insert nut 22n until the entire fixing member B is located inside the traction hose 31. This makes the outer diameter of the second end 31b equal to the outer diameter of the traction hose 31.

[0038] The tip portion 32 is provided at the first end 31a of the towing hose 31. The tip portion 32 is a cone-shaped metal member whose outer diameter tapers toward the +X side. The tip portion 32 is joined to the towing hose 31 by, for example, adhesive or welding. The outer diameter of the tip portion 32 is preferably smaller than the outer diameter of the towing hose 31, and more preferably equal to or smaller than the outer diameter of the cable portion 10.

[0039] The tip portion 32 has a pulling eye 33 at its tip. By tying a rope or the like to the pulling eye 33 and pulling the cable 100 with the pulling end, the cable portion 10 can be inserted into a duct or the like. Note that it is also possible to insert the cable 100 with the pulling end into a duct without providing the pulling eye 33, for example, by air pressure feeding.

[0040] Because the pulling section 30 and the cable section 10 are connected via the branch section 20 in this manner, when the tip section 32 is pulled, the pulling force is transmitted to the pulling hose 31, the branch section 20, and the tensile strength member 13 fixed to the branch section 20, thereby pulling the cable section 10. Furthermore, the pulling force can be prevented from being applied to low-strength members such as the optical fiber 12. Furthermore, in the pulling-end cable 100, the branch section 20 has an outer diameter equal to or smaller than that of the cable section 10, and there is no portion with an outer diameter greater than that of the pulling hose 31. This makes it easier to route the pulling-end cable 100 through a duct than conventional pulling-end cables. A conventional pulling-end cable will now be described with reference to FIGS. 12 to 13C.

[0041] FIG. 12 and FIGS. 13A to 13C show conventional pulling-end cables 200 and 300. In the conventional pulling-end cable 200 shown in FIG. 12, a cased branch portion 220 is formed by filling a resin 200R through a through-hole 240h in a case 240 located outside the outer circumferential surface of a cable portion 210. Therefore, the outer diameter of the cased branch portion 220 is larger than the outer diameter of the cable. The cased branch portion 220 is further provided with a hose fixing member (not shown) and a waterproof member holding portion (not shown). The addition of these members may complicate the shape of the case 240 and further increase the outer diameter of the case 240. Additionally, a pulling hose (not shown) is connected radially outward from the cased branch portion 220. In this case, the outer diameter of the pulling-end cable 201 becomes larger than the outer diameter of the cable portion 210.

[0042] In other conventional cables with towing ends 300, resin 300R is first filled through a through-hole 340h in a mold 340 provided outside the outer periphery of the cable portion 310 as shown in FIG. 13A , and after the resin 300R is cured, the mold 340 is removed as shown in FIGS. 13B and 13C to form the branch portion 320. Therefore, although the outer diameter of the branch portion 320 containing the cured resin 300R′ is the same as the outer diameter of the cable, the branch portion 320 is made only of adhesive, which may result in an unstable outer diameter shape. Furthermore, because the branch portion 320 does not have a hose fixing member or a waterproofing member holding member, it may not have sufficient functionality for fixing the towing hose or waterproofing the cable end.

[0043] In contrast, the cable with towing end 100 of this embodiment has the function of fixing the towing hose and the waterproofing function by the hose fixing member 22 and the waterproofing member holding portion 23, but can be configured so that the resin portion 21 and the tensile member 13 are appropriately joined and the outer diameter is not excessively large compared to the cable portion 10.

[0044] (Method of laying a pulling-end fiber cable) A method of laying the pulling-end cable 100 shown in Fig. 6A between data centers will be described with reference to Figs. 6B to 7B. In the cable section 10 shown in Fig. 6A, a plurality of connectors 14 are provided at the ends of the optical fibers 12 extending from the end section 10a. The connectors 14 are, for example, MPO connectors. The connectors 14 may be single-fiber connectors or multi-fiber connectors. In other words, the cable section 10 of this embodiment may be an optical fiber cable including optical fibers 12 with connectors 14.

[0045] As shown in FIG. 6B , multiple connectors 14 terminated to multiple optical fibers 12 are arranged with a staggered arrangement in the longitudinal direction X. To stagger the arrangement of the connectors 14 in the longitudinal direction X, excess lengths of the optical fibers 12 may be bundled within the towing hose 31, or the lengths of the multiple optical fibers 12 extending from the end 10a of the cable portion 10 may be varied. This allows the diameter of the towing hose 31 accommodating multiple connectors 14 to be kept small. Therefore, even when multiple connectors 14 are included within the towing hose 31, the cable with towing end 100 can be inserted through a narrow duct. Note that in the example of FIG. 6A , the optical fibers 12 are bundled with a bundle material and arranged within the towing hose 31 for each unit including multiple optical fibers 12 terminated to each connector 14.

[0046] As shown in Figures 7A and 7B, the duct D is a pipe that is installed underground or the like in advance. The duct D is a pipe that connects underground spaces or connects an underground space with a station building, an apartment building, or other location where the optical fiber is to be installed. In the example of Figure 7A, the duct D that connects the first data center C1 to the second data center C2 is buried underground. Below, a method of laying the cable 100 with a pulling end from a manhole M provided in the middle of the duct D will be described.

[0047] 7A , the towing end-equipped cable 100 is first introduced from a manhole M through a duct D to the first data center C1. At this time, a wire W is first passed through the duct D between the first data center C1 side and the manhole M, the tip of the wire W coming out of the manhole M is connected to the pulling eye 33 of the towing end-equipped cable 100, and the wire W is laid by being pulled from the first data center C1 side. After the tip of the towing end-equipped cable 100 has been routed to the first data center C1, the towing hose 31 of the towing section 30 is removed, and the connector 14 is connected to equipment E in the first data center C1.

[0048] 6A and 6B is attached to the end 100b of the pulling-end cable 100 on the C2 side, which is opposite the end 100a on the C1 side laid toward the first data center C1. The method of laying the cable from the manhole M to the second data center C2 using the pulling section 30 of the end 100b is the same as the method of laying the end 100a, so a detailed description will be omitted. In this way, the pulling section 30 can be used to lay the pulling-end cable 100 between the data centers C1 and C2.

[0049] 7B , two existing cables W1 and W2 are laid in the duct D, and the cross-sectional area of ​​the duct D that can be used when laying a new cable may be small. Therefore, it is desirable that the outer diameter of the cable with towing end 100 is small so that it can pass through the manhole M and the duct D.

[0050] According to the pulling-end cable 100 of this embodiment, compared to conventional pulling-end cables 200, 300, the outer diameter of the branching portion 20 is equal to or smaller than the outer diameter of the cable portion 10, and the outer diameter of the pulling portion 30 can be made thinner, making it possible to lay the cable in a duct D where conventional cables could not be laid because the outer diameter of the pulling end is large. Furthermore, the pulling-end cable 100 of this embodiment can achieve a pulling-end cable 100 in which the hose fixing member 22, waterproofing member holding portion 23, and resin portion 21 provide the functions of fixing the pulling hose 31, waterproofing the cable end, and connecting the tensile member 13, while preventing the outer diameter of the pulling end from becoming larger.

[0051] (Method of Manufacturing the Cable with Towing End 100) Next, a method of manufacturing the cable with towing end 100 will be described with reference to Figures 2 to 5. Note that the following manufacturing method is merely an example, and other manufacturing methods may also be adopted.

[0052] First, the sheath 11 is removed from the end of the cable portion 10, and the required length of the optical fiber 12 and the tension member 13 is extended. A connector 14 may be attached to the tip of the optical fiber 12 depending on the intended use.

[0053] Next, as shown in FIG. 2 , a mold 40 for forming the resin portion 21 of the branching portion 20 is attached to the end portion 10a of the cable portion 10. The mold 40 (see FIG. 4B ) is formed by combining two members each having a semicircular arc-shaped recess 42 extending in the longitudinal direction. In other words, the mold 40 can also be considered a member divided into halves, with a joining surface 41 extending in the longitudinal direction when the halves are combined. The optical fiber 12, the strength member 13, the hose fixing member 22, and the waterproofing member holding portion 23 are arranged in a cylindrical space 40S extending along the longitudinal direction inside the mold 40. The hose fixing member 22 and the waterproofing member holding portion 23 are fixed to an inner wall 40i of the mold 40. In this case, for example, if the insert nut holding portion 22a and the O-ring holding portion 23a are split in half, the insert nut holding portion 22a and the O-ring holding portion 23a may be provided inside the mold 40 so that the joint surface 221 of the insert nut holding portion 22a and the joint surface (not shown) of the O-ring holding portion 23a overlap with a plane including the joint surface 41. A through hole 40n penetrating the wall surface of the mold 40 is provided in the wall surface.

[0054] Next, as shown in FIG. 3 , resin R1 is filled into the mold 40 through the through-hole 40n. The resin R1 is liquid, and the viscosity of the resin R1 may be set to a certain level when filling the mold 40 so that the resin R1 is sufficiently filled into the gaps between the components arranged in the space 40S. When filling the mold 40 with resin R1, the cable portion 10 may be positioned so that the +X direction faces vertically upward. This allows the uncured resin R1 to fill the mold 40 more tightly with gaps. The branch portion 20 is formed by curing the resin R1.

[0055] Next, as shown in FIGS. 4A and 4B , the mold 40 is removed from the branching portion 20. Because the half mold 40 can be separated into two parts at the joint surface 41, the mold 40 can be removed without applying excessive stress to the branching portion 20. Because the hose fixing member 22 and the waterproofing member holding portion 23 are adhered to the resin portion 21, when the mold 40 is removed, the hose fixing member 22 and the waterproofing member holding portion 23 are embedded in the branching portion 20. This makes it easy to manufacture a branching portion 20 in which the outer diameters of the hose fixing member 22 and the waterproofing member holding portion 23 are equal to the inner diameter of the mold 40 (i.e., the outer diameter of the branching portion 20). Furthermore, a waterproofing member (O-ring 24) is appropriately placed in the recess 23r of the waterproofing member holding portion 23.

[0056] Next, the traction hose 31 is attached so as to cover the branching portion 20 and the end 10a of the cable portion 10. A through hole 31h is provided in the second end 31b of the traction hose 31 at a position corresponding to the hose fixing member 22. The traction hose 31 is fixed to the branching portion 20 by tightening a fixing member B, which passes through the through hole 31h of the traction hose 31, to the insert nut 22n of the hose fixing member 22. Furthermore, the tip portion 32 is attached to the first end 31a of the traction hose 31. Through the above steps, the cable 100 with a traction end is manufactured.

[0057] 5, when manufacturing the cable with towing end 100, a protective layer 21p may be formed on the outer peripheral surface of the branching portion 20 before attaching the towing hose 31 to the branching portion 20. The protective layer 21p may be a heat-shrinkable tube, a painted resin, a spray film formed by spraying a resin, or the like.

[0058] In the manufacturing method of this embodiment, functional parts such as the tensile strength member 13, the hose fixing member 22, and the waterproofing member holding portion 23 are arranged inside a mold 40, and resin R1 that will become the resin portion 21 is poured into the mold 40 and then hardened to form the branch portion 20. Even after the mold 40 is removed, the functional parts such as the tensile strength member 13, the hose fixing member 22, and the waterproofing member holding portion 23 remain in the branch portion 20, making it possible to easily manufacture a branch portion 20 that has the functions required for the towing end and has a small outer diameter.

[0059] As described above, the cable with towing end 100 of this embodiment comprises the cable portion 10 having the optical fiber 12, the tensile strength member 13, and the sheath 11, the branching portion 20 having the resin portion 21 fixed to the end 10a of the cable portion 10, and the towing portion 30 having the towing hose 31 covering the branching portion 20, and the hose fixing member 22, the waterproofing member holding portion 23, and the tensile strength member 13 are embedded in the resin portion 21.

[0060] The cable with towing end 100 of this embodiment has a fixing function for the towing portion 30 by the hose fixing member 22 of the branch portion 20, and a waterproofing function by the waterproofing member holding portion 23. Furthermore, because the tensile member 13 is fixed within the branch portion 20, the cable with towing end 100 can be reliably pulled by the tension when towing. Furthermore, because the outer diameter of the branch portion 20 can be made equal to or smaller than the outer diameter of the cable portion 10, the outer diameter of the towing portion of the cable with towing end 100 can be made thinner than that of conventional cables.

[0061] The hose fixing member 22 also has an insert nut holding portion 22 a and an insert nut 22 n held by the insert nut holding portion 22 a. This allows the towing hose 31 to be fixed to the branch portion 20 using a fixing member B such as a female screw.

[0062] Furthermore, the waterproofing member holding portion 23 is an O-ring holding portion 23a, which prevents water from entering the inside of the cable with towing end 100 by the O-ring.

[0063] Furthermore, the method for manufacturing the cable with towing end 100 of this embodiment involves attaching a mold 40, inside which the hose fixing member 22, the waterproofing member holding portion 23, and the tensile member 13 extending from the sheath 11 are disposed, to the end 10a of the cable portion 10 having the optical fiber 12, the tensile member 13, and the sheath 11; filling the inside of the mold 40 with resin R1; forming the branch portion 20 by hardening the resin R1; removing the mold 40; and attaching a towing hose 31 that covers the branch portion 20.

[0064] As a result, functional parts such as the hose fixing member 22 and the waterproofing member holding portion 23 remain in the branch portion even after the mold 40 is removed, making it possible to easily manufacture the branch portion 20 having a small outer diameter while still having the functions required for the pulling end. Thus, it is possible to manufacture the cable with pulling end 100 that can prevent the outer diameter from increasing while still having the fixing function and waterproofing function for the pulling end.

[0065] Second Embodiment Next, a second embodiment of the cable with towing ends according to the present invention will be described, which has the same basic configuration as the first embodiment. Therefore, the same components are denoted by the same reference numerals, and their description will be omitted, and only the differences will be described.

[0066] FIG. 8 is a partial longitudinal cross-sectional view of a cable with a towing end 100 according to a second embodiment. As shown in FIG. 8 , in this embodiment, the hose fixing member 22 is a male thread portion 22m formed on the outer circumferential surface 21a of the resin portion 21. In this case, to fix the branching portion 20 and the pulling portion 30, a female thread portion 30f into which the male thread portion 22m can be fitted is provided on the inner wall of the pulling hose 31. The branching portion 20 and the pulling portion 30 are fixed by fitting the male thread portion 22m into the female thread portion 30f. Note that in this embodiment, part of the thread of the male thread portion 22m may be provided radially outward from the outer circumferential surface of the cable portion 10. Even in this case, the outer diameter of the branching portion 20 can be made equal to or smaller than the outer diameter of the cable portion 10, excluding part of the thread, and therefore the outer diameter of the pulling portion of the cable with a towing end 100 can be made smaller than that of conventional cables.

[0067] Next, with reference to FIGS. 9A and 9B , a method for manufacturing a cable with a pulling end 100 according to the second embodiment will be described, focusing only on differences from the first embodiment. Note that the following manufacturing method is merely an example, and other manufacturing methods may be employed. To form the male thread portion 22m, a spiral groove 43 (see FIG. 9B ) is formed on the inner surface of a mold 40. By pouring uncured resin R1 into the mold 40 having the groove 43 and then curing the resin R1, the branch portion 20 having the male thread portion 22m shown in FIG. 9A can be easily manufactured. Furthermore, the branch portion 20 and the pulling portion 30 can be fixed together by threading the female thread portion 30f of the pulling portion 30 into the male thread portion 22m of the branch portion 20.

[0068] As described above, in the cable with towing end 100 of this embodiment, the hose fixing member 22 is the male thread portion 22m formed on the outer circumferential surface 21a of the resin portion 21. According to this configuration, the towing hose 31 can be fixed to the branch portion 20 by fitting the male thread portion 22m with the female thread portion 30f on the inner circumferential surface of the towing hose 31.

[0069] (Third Embodiment) Next, a third embodiment of the cable with a pulling end according to the present invention will be described. The basic configuration is the same as that of the first embodiment. Therefore, the same components are denoted by the same reference numerals and their description will be omitted, and only the differences will be described. The third embodiment differs from the first embodiment in that a protrusion 22p is provided instead of an insert nut 22n.

[0070] Fig. 10 is a partial vertical cross-sectional view of a cable with a pulling end 100 according to a third embodiment. As shown in Fig. 10, in this embodiment, the hose fixing member 22 is a plurality of protrusions 22p. Each protrusion 22p has a protrusion 22p1 that protrudes radially outward from the outer circumferential surface 21a of the resin portion 21, and an embedded portion 22p2 that is embedded in the resin portion 21. The protrusion 22p1 and the embedded portion 22p2 have a cylindrical shape extending radially. In this embodiment, the diameter of the embedded portion 22p2 is larger than the diameter of the protrusion 22p1, and the number of protrusions 22p is four, but the shape and number of the protrusions 22p are not limited.

[0071] To secure the branching portion 20 and the towing portion 30, a recess 30r is provided on the inner wall of the traction hose 31, into which the protruding portion 22p1 of the convex portion 22p engages. A plurality of recesses 30r are provided, the number of which corresponds to the number of convex portions 22p. The branching portion 20 and the towing portion 30 are secured by fitting the protruding portion 22p1 into the recess 30r. Note that the recess 30r on the inner wall of the traction hose 31 may be provided only at positions corresponding to the convex portions 22p. Furthermore, the recess 30r may be formed so as to extend spirally from the end face of the second end 31b of the traction hose 31 along the inner wall of the traction hose 31 in the +X direction, and the engagement between the protruding portion 22p and the recess 30r may be a so-called bayonet fit.

[0072] Next, with reference to Figures 11A and 11B, a method for manufacturing a cable with a pulling end 100 according to the third embodiment will be described, focusing only on the differences from the first embodiment. Note that the following manufacturing method is merely an example, and other manufacturing methods may be adopted. As shown in Figure 11B, the mold 40 has a plurality of split molds 40a, the same number as the number of protrusions 22p. In the example shown in Figures 11A and 11B, there are four split molds 40a, and each split mold 40a has an arc-shaped recess 42 that is 1 / 4 the shape of a cylinder extending in the longitudinal direction, and an accommodating recess 44 that accommodates the protrusion 22p1.

[0073] The mold 40 is assembled by joining the joint surfaces 41 of multiple split molds 40a together with the protrusions 22p1 inserted into the accommodation recesses 44 of the split molds 40a. When assembling the mold 40, the optical fiber 12, the tensile strength members 13, etc. may be placed in the cylindrical internal space of the mold 40. After the mold 40 is assembled with the end 10a of the cable portion 10, uncured resin R1 is poured into the internal space. After the resin R1 is cured, the split molds 40a are each removed radially outward (see FIG. 11B), thereby producing a branching portion 20 in which the protrusions 22p1 of the protrusions 22p protrude from the outer peripheral surface of the branching portion 20 (see FIG. 11A). Because the mold 40 is formed from a number of split molds 40a corresponding to the number of protrusions 22p, both the direction in which the protrusions 22p1 extend and the direction in which the split molds 40a move when removed are radially outward. In this way, since the two directions can be aligned, the mold 40 can be easily removed from the branching portion 20 .

[0074] After the branch portion 20 is formed, the convex portion 22p is fitted into the concave portion 30r to fix the branch portion 20 and the towing portion 30. If the concave portion 30r is provided spirally on the inner surface of the traction hose 31, the convex portion 22p is fitted into the concave portion 30r on the end surface of the second end 31b of the traction hose 31, and the traction hose 31 is rotated relative to the branch portion 20 along the spiral shape of the concave portion 30r, thereby moving the convex portion 22p to the +X side of the spirally extending concave portion 30r. This allows the branch portion 20 and the towing portion 30 to be fixed together.

[0075] As described above, in the towing cable 100 of this embodiment, the hose fixing member 22 is the convex portion 22p having the protruding portion 22p1 protruding from the outer peripheral surface of the resin portion 21. This allows the towing hose 31 to be fixed to the branch portion 20 using the protruding portion 22p1 of the convex portion 22p.

[0076] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0077] For example, although an example has been described in which the optical fiber 12 extends from the first end 20a of the branching portion 20, the optical fiber 12 does not have to extend from the branching portion 20, and the optical fiber does not have to be provided within the branching portion 20.

[0078] In addition, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, and the above-described embodiments and variations may be combined as appropriate, without departing from the spirit of the present invention.

[0079] According to the above-described embodiment of the present invention, it is possible to provide a cable with a towing end having a branch portion that can prevent the outer diameter from increasing while having a function of fixing the towing end and a waterproof function, and a method for manufacturing a cable with a towing end.

[0080] 10...cable portion, 11...sheath, 12...optical fiber, 13...tensile member, 20...branch portion, 21...resin portion, 21a...outer surface of resin portion, 22...hose fixing member, 22a...insert nut holding portion, 22n...insert nut, 22m...male thread portion, 22p...convex portion, 22p1...protruding portion, 23...waterproof member holding portion, 23a...O-ring holding portion, 30...pulling portion, 31...pulling hose, 40...type, 100...cable with pulling end

Claims

1. A cable with a towing end, comprising: a cable portion having an optical fiber, a strength member, and a sheath; a branch portion having a resin portion fixed to the end of the cable portion; and a towing portion having a towing hose covering the branch portion, wherein a hose fixing member, a waterproof member holding portion, and the strength member are embedded in the resin portion.

2. A cable with a towing end according to claim 1, wherein the hose fixing member has an insert nut holding portion and an insert nut held in the insert nut holding portion.

3. A cable with a towing end according to claim 1, wherein the hose fixing member is a male thread portion formed on the outer circumferential surface of the resin portion.

4. A cable with a towing end according to claim 1, wherein the hose fixing member is a convex portion having a protrusion protruding from the outer peripheral surface of the resin portion.

5. A cable with a towing end according to any one of claims 1 to 4, wherein the waterproof member holding portion is an O-ring holding portion.

6. A method for manufacturing a cable with a towing end, comprising: attaching a mold to the end of a cable portion having an optical fiber, a strength member, and a sheath, the mold having a hose fixing member, a waterproof member holding portion, and the strength member extending from the sheath disposed therein; filling the mold with resin; forming a branch portion by hardening the resin; removing the mold; and attaching a towing hose that covers the branch portion.

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