Cable traction terminal structure

Abstract

The optical cable traction terminal structure (1A) includes: an inner tube (10) which can accommodate an optical cable (2) therein and is formed by winding a wire material (10A) into a spiral shape and connecting them; and an outer tube (20) which is provided on the outer peripheral surface of the inner tube (10) and has flexibility. A part of the outer tube (20) enters the inside of a groove (11) formed on the outer peripheral surface of the inner tube (10).

Description

Technical Field

[0001] The present invention relates to a cable traction terminal structure.

[0002] This application claims the priority of U.S. Patent Application No. 63 / 021,100, filed in the United States on May 7, 2020, and the content thereof is incorporated herein by reference. Background Art

[0003] In recent years, with the development of optical communication technology using optical fibers, the number of laid optical fibers has increased dramatically. Therefore, in the case of connecting optical cables formed by bundling optical fibers between data centers, etc., in most cases, a cable traction terminal is used to simultaneously wind thousands of optical fibers. Various developments have been made on the structure of this cable traction terminal. For example, the cable traction terminal structure described in Patent Document 1 includes: a flexible tube formed by connecting cross-sectionally substantially groove-shaped forming members in a spiral; a metal mesh covering the outer peripheral surface of the flexible tube; and a heat shrinkable tube covering the outer peripheral surface of the metal mesh. The heat shrinkable tube is used to prevent water from entering the inner tube.

[0004] Patent Document 1: Japanese Patent Laid-Open No. 9-230186

[0005] In the heat shrinkable tube of Patent Document 1, since the elongation (compressibility) is low, for example, when the cable traction terminal is bent, wrinkles are generated on the inner diameter side of the heat shrinkable tube. Then, when the cable traction end is wound, it is possible that friction is locally generated at the wrinkles and the like, and cracks are generated on the outer peripheral surface of the heat shrinkable tube, resulting in water entering the inner tube. Summary of the Invention

[0006] The present invention has been made in view of such circumstances, and an object thereof is to provide a cable traction terminal structure that can prevent water from entering the inner tube.

[0007] The traction terminal structure according to the first aspect of the present invention includes: an inner tube capable of accommodating an optical cable therein, formed by winding a wire material in a spiral and connecting; and an outer tube provided on the outer peripheral surface of the inner tube and having flexibility, a part of the outer tube entering the inside of a groove formed on the outer peripheral surface of the inner tube.

[0008] According to the above aspect, since a part of the outer tube enters the groove, even when a force is applied to bend the inner tube, the outer tube in the groove follows the bending of the inner tube. Thereby, it is possible to alleviate the occurrence of unevenness on the outer peripheral surface of the outer tube. Therefore, cracks are not easily generated on the outer peripheral surface of the inner tube, so that water can be prevented from entering the inner tube.

[0009] It may be that a connecting member is provided on the outer peripheral surface of the rear end of the inner tube.

[0010] Alternatively, protrusions may be formed on the inner wall of the above-mentioned connecting member, and the protrusions are engaged with the grooves of the above-mentioned inner tube.

[0011] Alternatively, the above-mentioned connecting member overlaps with the rear end of the above-mentioned inner tube and also overlaps with the rear end of the above-mentioned outer tube.

[0012] Alternatively, the above-mentioned connecting member is bonded at least at the overlapping portion that overlaps with the rear end of the above-mentioned outer tube.

[0013] Alternatively, in the above-mentioned overlapping portion, the connecting member forms a recess at a position facing the above-mentioned outer tube, and an adhesive is provided in the recess.

[0014] Alternatively, a gap is provided between the above-mentioned outer tube and the above-mentioned connecting member in the longitudinal direction of the above-mentioned inner tube, and a water-stop member is provided in the gap.

[0015] Alternatively, the above-mentioned water-stop member is made of a resin material.

[0016] According to the above aspect of the present invention, water intrusion into the inner tube can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a main part sectional view of the optical cable traction terminal structure according to the first embodiment.

[0018] Figure 2 is Figure 1 a sectional view taken along line II-II.

[0019] Figure 3 is a main part sectional view of the rear end of the optical cable traction terminal structure according to the first embodiment.

[0020] Figure 4 is an exploded view of the rear end of the optical cable traction terminal structure according to the first embodiment.

[0021] Figure 5 is a main part sectional view at the overlapping portion of the connecting member and the inner tube.

[0022] Figure 6 is a main part sectional view of a modified example of the optical cable traction terminal structure according to the first embodiment.

[0023] Figure 7 is a main part sectional view of the optical cable traction terminal structure according to the second embodiment.

[0024] Figure 8 is a view showing the inner tube without the outer tube covered.

[0025] Figure 9 is a view showing the inner tube with the outer tube covered.

[0026] Figure 10 This is a view showing a part of the front end side of the optical cable traction terminal structure of the third embodiment.

[0027] Figure 11 This is a view of the optical cable housed inside the optical cable traction terminal structure. Detailed Embodiment

[0028] (First Embodiment)

[0029] Refer to Figures 1 to 6 The optical cable traction terminal structure according to the first embodiment of the present invention will be described.

[0030] As Figure 1 shown, the optical cable traction terminal structure 1A includes an inner tube 10, an outer tube 20, a conical head 30, and a connecting member 40.

[0031] (Direction Definition)

[0032] Here, in the present embodiment, the length direction of the optical cable traction terminal structure 1A is simply referred to as the length direction. There are cases where the front end side of the optical cable traction terminal structure 1A where the head 30 is provided is called the front end, and the base end side where the connecting member 40 is provided is called the rear end. In addition, the direction intersecting the central axis O (refer to Figure 3 ) of the optical cable traction terminal structure 1A is called the radial direction. In addition, the cross-section orthogonal to the central axis O is called the cross-section.

[0033] As Figure 1 and Figure 2 shown, the optical cable traction terminal structure 1A of the present embodiment further includes an optical cable 2, a pair of tension members 3, and a holding member 4.

[0034] The head 30 is provided on the front end side of the optical cable traction terminal structure 1A, and the connecting member 40 is provided on the base end side of the optical cable traction terminal structure 1A.

[0035] The head 30 is a metal component. As Figure 1 shown, it has a pulling hole 31 at the front end. The head 30 is joined to the inner tube 10 by welding, for example. In addition, the head 30 has an inclined portion 30a. The inclined portion 30a is configured such that the outer diameter gradually decreases from the base end toward the front end. The pulling hole 31 is arranged at the front end of the inclined portion 30a. By tying a rope or the like to the pulling hole 31, it is easy to insert the optical cable traction terminal structure 1A into the inside of an underground pipe and perform traction.

[0036] As Figure 1 shown, the optical cable 2 is housed inside the inner tube 10. In the present embodiment, for example, 3456 optical fibers 5 are bundled, and connectors 6 are terminated at the ends of the respective optical fibers 5.

[0037] As Figure 2 shown, a pair (a total of four) of tension members 3 are arranged so as to radially sandwich the optical cable 2 in a transverse cross-section. The tension members 3 function as members that bear forces such as tensile stress generated when pulling the optical cable traction terminal structure 1A. In addition, in the present embodiment, the number of tension members is set to four, but it is not limited thereto.

[0038] The holding member 4 is made of a tubular metal having a through-hole 4a formed therein for inserting the optical cable 2. The holding member 4 is fixed to the inner tube 10 via a connecting member 40 by bolts 7.

[0039] In addition, the holding member 4 has a tension member fixing portion (not shown) for fixing the tension member 3 on the inner peripheral surface of the through-hole 4a. Thus, by fixing the tension member 3 to the holding member 4, it is possible to reliably bear the force applied to the entire optical cable traction terminal structure 1A, and the firmness can be improved.

[0040] As Figure 3 shown, the inner tube 10 is configured as a tubular member (helical tube) formed by winding a strip-shaped wire material (for example, a stainless steel (SUS) plate) 10A in a spiral shape and connecting it in the length direction. For example, the wire material 10A is fitted about 1 / 3 in the width direction and connected in a spiral shape. According to this structure, the inner tube 10 has flexibility as a whole. In addition, in Figure 3 , the optical cable 2 is not shown in order to easily observe the drawings.

[0041] Figure 4 is an exploded view of the rear end of the optical cable traction terminal structure according to the first embodiment. As Figure 4 shown, a groove 11 is formed along the length direction of the wire material 10A at the central portion in the width direction on the outer peripheral surface of the wire material 10A. The intervals between the grooves 11 adjacent to each other in the length direction are formed by a groove pitch P1.

[0042] In the present embodiment, since the wire material 10A is fitted and connected in a spiral shape, the inner diameter of the inner tube 10 can be maintained even when tension is applied in the length direction.

[0043] As Figure 3 shown, the outer tube 20 is provided on the outer peripheral surface of the inner tube 10 and has flexibility. A part of the outer tube 20 enters the inside of the groove 11 formed on the outer peripheral surface of the inner tube 10. That is, the groove 11 is filled with a part of the outer tube 20. In addition, the outer tube 20 is not provided on the outer peripheral surface of the rear end 12 of the inner tube 10. The material of the outer tube 20 is, for example, an elastomer such as polyvinyl chloride, polyolefin resin, fluorine-based polymer, or thermoplastic elastomer. Thus, even when the inner tube 10 is bent, the resilience to a straight state is improved.

[0044] The method of inserting a part of the outer tube 20 into the groove 11 of the inner tube 10 is not particularly limited. For example, the inner tube 10 is immersed in a liquid polyolefin resin, and the polyolefin resin enters the groove 11 of the inner tube 10. Then, the liquid polyolefin resin is made to closely adhere to the inner surface of the groove 11 and cured to have elasticity.

[0045] As Figure 3 shown, the connecting member 40 of the optical cable traction terminal structure 1A of the present embodiment is provided on the outer peripheral surface of the rear end 12 of the inner tube 10.

[0046] As Figure 4 shown, the connecting member 40 is cylindrical. Inside the connecting member 40, an inner peripheral surface 41, a first recess 42 recessed with respect to the inner peripheral surface 41, and a second recess 43 recessed with respect to the first recess 42 are sequentially formed from the rear end 40A side. The inner diameter of the first recess 42 and the inner diameter of the second recess 43 gradually increase.

[0047] As Figure 4 and Figure 5 shown, on the inner wall of the first recess 42 of the connecting member 40, protrusions 45 are formed in a spiral shape. The protrusion pitch P2 of the protrusions 45 is the same as the groove pitch P1 of the groove 11. The outer tube 20 is not provided on the outer peripheral surface of the rear end 12 of the inner tube 10, and the protrusions 45 of the connecting member 40 are engaged with the grooves 11 of the inner tube 10. That is, the connecting member 40 covers the outer peripheral surface of the rear end 12 of the inner tube 10. Thus, as Figure 3 shown, the rear end 12 of the inner tube 10 is received in the first recess 42. Therefore, the rear end 12 of the inner tube 10 overlaps the connecting member 40 in the radial direction. The first overlapping portion 46 between the connecting member 40 and the inner tube 10 is bonded with an adhesive (not shown).

[0048] As Figure 3 shown, the rear end 21 of the outer tube 20 is received in the second recess 43. That is, the front end 40B of the connecting member 40 covers the outer peripheral surface of the rear end 21 of the outer tube 20. The rear end 21 of the outer tube 20 is in contact with the second recess 43 without a gap and overlaps the connecting member 40 in the radial direction. The second overlapping portion 47 between the connecting member 40 and the outer tube 20 is bonded with an adhesive (not shown).

[0049] As described above, the optical cable traction terminal structure 1A of the present embodiment includes: an inner tube 10 that can accommodate the optical cable 2 therein and is formed by spirally connecting wire materials 10A; and an outer tube 20 that is provided on the outer peripheral surface of the inner tube 10 and has flexibility, and a part of the outer tube 20 enters the inside of a groove 11 formed on the outer peripheral surface of the inner tube 10. With such a structure, a part of the outer tube 20 intrudes (adheres closely) to the inner surface of the groove 11 of the inner tube 10, so the extensibility and compressibility are increased. That is, even when the traction terminal structure 1 is bent, the positional relationship between the outer tube and the inner tube does not shift. Therefore, even when a bending force is applied to the inner tube 10, the local bending stress applied to the outer tube 20 in the groove 11 disappears, and the outer tube 20 follows the bending of the inner tube 10. Thereby, the tensile stress on the outer peripheral surface of the outer tube 20 is alleviated. Then, for example, on the inner side of a bent cable, no wrinkles are generated on the outer skin of the outer tube 20, and the unevenness generated on the outer skin surface can be alleviated. Then, a part of the outer skin is not locally subjected to the friction received when inserting and pulling the optical cable traction terminal structure 1A through a pipe. Therefore, cracks are not easily generated on the outer peripheral surface of the inner tube 10, and thus water intrusion into the inner tube 10 can be prevented.

[0050] In addition, in the optical cable traction terminal structure 1A of the present embodiment, a connecting member 40 is provided on the outer peripheral surface of the rear end 12 of the inner tube 10. According to this structure, compared with the structure in which the connecting member is provided inside the inner tube, contact between the connector 6 and the connecting member 40 can be prevented, so damage to the connector 6 can be suppressed.

[0051] In addition, the connecting member 40 overlaps with the rear end 12 of the inner tube 10 and also overlaps with the rear end 21 of the outer tube 20, so the connecting member 40 is in surface contact with the rear end 12 of the inner tube 10 and the rear end 21 of the outer tube 20. Thereby, the strength of the adhesive can be maintained. And the connecting member 40 can more reliably prevent water from intruding into the inner tube 10 through the first overlapping portion 46 and the second overlapping portion 47.

[0052] In addition, although it is configured that the outer tube 20 is adhesively bonded to the second recess 43 without a gap, there may be a gap between the outer tube 20 and the second recess 43 of the connecting member 40, and the gap is filled with an adhesive.

[0053] [Modification Example]

[0054] As Figure 6 shown, in the optical cable traction terminal structure 1B of the modification example, an adhesive is provided in the second overlapping portion 47. That is, in the above first embodiment, adhesives are provided in both the first overlapping portion 46 between the connecting member 40 and the inner tube 10 and the second overlapping portion 47 between the connecting member 40 and the outer tube 20, but in this modification example, an adhesive is provided only in the second overlapping portion 47.

[0055] The connecting member 40 has a recess 48 formed at a position facing the outer tube 20. That is, the recess 48 is formed on the surface 40a that contacts the outer tube 20. An adhesive 49 is filled in the recess 48. The front end 40B of the connecting member 40 and the rear end 21 of the outer tube 20 are fixed by the adhesive 49.

[0056] In the optical cable pulling terminal structure 1B, the front end 40B of the connecting member 40 and the rear end 21 of the outer tube 20 can be fixed by the adhesive 49, and water can be prevented from infiltrating from the second overlapping portion 47.

[0057] In addition, instead of the adhesive 49, the front end 40B of the connecting member 40 and the rear end 21 of the outer tube 20 can be fixed, for example, by fixing screws in the second overlapping portion 47.

[0058] (Second Embodiment)

[0059] Next, a second embodiment of the present invention will be described. However, the basic structure is the same as that of the first embodiment. Therefore, the same structural components are denoted by the same reference numerals and their descriptions are omitted, and only the differences will be described.

[0060] In the optical cable pulling terminal structure 1C of the present embodiment, as Figure 7 shown, the arrangement of the outer tube 20 and the connecting member 40 is different from that of the first embodiment. In addition, in order to easily observe the drawings, Figure 7 the optical cable pulling terminal structure 1C is a simplified view of the optical cable pulling terminal structure 1A.

[0061] The difference between the present embodiment and the first embodiment is that the outer tube 20 and the connecting member 40 are arranged at intervals. That is, the rear end 21 of the outer tube 20 and the front end 40B of the connecting member 40 are spaced apart in the length direction.

[0062] For the reason of spacing the rear end 21 of the outer tube 20 from the front end 40B of the connecting member 40, for example, when the connecting member 40 and the inner tube 10 are fixed and the front end surface 40b of the connecting member 40 is brazed to the outer peripheral surface of the inner tube 10. That is, in order to prevent the outer tube 20 from melting due to heat, it is necessary to space the rear end 21 of the outer tube 20 from the front end 40B of the connecting member 40.

[0063] A tape 50 having waterproofness and flexibility is wound so as to cover the outer periphery of the rear end 21 of the outer tube 20 and the outer periphery of the front end 40B of the connecting member 40.

[0064] A gap 51 is formed by the rear end face 21a of the outer tube 20, the front end face 40b of the connecting member 40, the outer peripheral surface of the inner tube 10, and the inner peripheral surface of the belt 50. A polyurethane gel (waterstop member: resin material) 52 is provided in the gap 51. The size of the polyurethane gel 52 is larger than the size of the gap 51, and it is disposed in the gap 51 in a compressed state.

[0065] In the optical cable traction terminal structure 1C of the present embodiment, in the longitudinal direction of the inner tube 10, the outer tube 20 and the connecting member 40 are arranged at intervals, and the polyurethane gel 52 is provided in the gap 51. With such a structure, it is possible to prevent the outer tube 20 from melting, and it is possible to prevent water from entering the inner tube 10 by using the polyurethane gel 52.

[0066] In addition, by using a resin material (for example, polyurethane gel) as the waterstop member, even when the optical cable traction terminal structure 1C is stretched in the longitudinal direction due to the traction force, since the resin material follows the elongation, it is also possible to prevent water from entering the inner tube 10.

[0067] (Third Embodiment)

[0068] Next, the third embodiment of the present invention will be described. However, the basic structure is the same as that of the first embodiment. Therefore, the same structural components are denoted by the same reference numerals and their descriptions are omitted, and only the differences will be described.

[0069] In the first embodiment, the relationship between the elastic modulus of the inner tube 10 and the elastic modulus of the outer tube is not particularly limited. However, in the optical cable traction terminal structure of the present embodiment, the outer tube 20 is made of a material having an elastic modulus (Young's modulus) higher than the elastic modulus (Young's modulus) of the inner tube 10.

[0070] According to this structure, the optical cable traction terminal structure may be bent as a whole due to the applied force, but if the force applied to the optical cable traction terminal structure is released, it will return to a straight shape. In addition, the material of the outer tube 20 is the same as that of the first embodiment, which is a polyolefin resin, so it also has stretchability in the longitudinal direction. With such a structure, when an operator handles the optical cable traction terminal structure, if a force is applied to the optical cable traction terminal structure to bend it to the maximum curvature of the inner tube 10 and then the above force is released, the elastic force of the outer tube 20 acts in the direction of restoring the curvature, so that the bending of the outer tube 20 can be restored. As a result, the workability is significantly improved.

[0071] Next, the elastic restoring force of the optical cable traction terminal structure will be specifically shown. Figure 8 It is a view showing the inner tube 10 without the outer tube 20 covered. Figure 9 It is a view showing the inner tube 10 covered with the outer tube 20.

[0072] As Figure 8 shown, it can be seen that the inner tube 10 not covered with the outer tube 20 does not generate a restoring force to return from the bent state to the straight state, and thus maintains the curvature state.

[0073] On the other hand, as Figure 9 shown, it can be seen that for the inner tube 10 covered with the outer tube 20, a force to return the bent outer tube 20 to the straight state acts on the inner tube 10. In Figure 9 , a state in which it bends due to its own weight even when using the outer tube 20 is shown, but in an actual pipeline, when processing the inner tube 10 covered with the outer tube 20, a force to return to a substantially straight state acts. Thus, an optical cable traction terminal structure can be obtained that is easily bent when desired to be bent and can be simply restored to an easily tractionable straight state when pulled after bending.

[0074] Figure 10 is a view showing a part of the front end side of the optical cable traction terminal structure of the present embodiment. As Figure 10 shown, the outer tube 20 has a first part 25 provided with an adhesive 20a and a second part 26 not provided with the adhesive 20a. The first part 25 is provided at the front end 22 of the outer tube 20. Through this first part 25, the inner tube 10 and the outer tube 20 are in close contact over at least one full circumference (entire circumferential direction) in the length direction of the outer tube 20.

[0075] In addition, at the rear end 21 of the outer tube 20 as well as at the front end 22, the outer tube 20 has a first part provided with an adhesive (not shown) and a second part not provided with the adhesive (not shown). At the rear end 21, the inner tube 10 and the outer tube 20 are also in close contact through the first part. Thus, it is possible to prevent water from entering the inner tube 10 of the optical cable traction terminal structure.

[0076] Figure 11 is a view of the optical cable housed inside the optical cable traction terminal structure. As Figure 1 shown, the optical cable 2 is composed of multiple strands. The multiple optical cables 2 are covered with a transparent PVC (polyvinyl chloride) sheet 60. The PVC sheet 60 shrinks corresponding to the shape of the multiple optical cables and has, for example, a tear line (tear strip) 61 in its length direction. The number of tear lines 61 is two parallel to the length direction. That is, it is configured such that after inserting the optical cable traction terminal into the pipeline, when actually connecting to other optical fibers, the sheet 60 can be easily peeled off through the tear line 61. In addition, in the present embodiment, the number of tear lines 61 is two parallel to the length direction, but it can also be one, or three or more.

[0077] In addition, the scope of the technology of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention, and the above-described embodiments and modified examples can be appropriately combined.

[0078] For example, the material of the inner tube 10 is stainless steel, but it is not limited thereto. The material of the inner tube 10 can also be plastic instead of metal.

[0079] In addition, the holding member 4 is fixed to the inner tube 10 via the connecting member 40 by the bolt 7, but it can also be directly fixed to the inner tube 10.

[0080] In addition, in the present embodiment, the inner tube 10 is configured such that a stainless steel plate is fitted about 1 / 3 in the width direction and connected in a spiral shape, but it may not be fitted. In this case, the inner diameter of the inner tube 10 can be changed.

[0081] Description of reference numerals

[0082] 1A, 1B, C... Optical cable traction terminal structure; 2... Optical cable; 10... Inner tube; 11... Groove; 12... Rear end of the inner tube; 20... Outer tube; 40... Connecting member; 45... Projection; 52... Water stop member.

Claims

1. An optical cable traction terminal structure, comprising: An inner tube capable of accommodating an optical cable therein, formed by winding a wire into a spiral shape and connecting them; An outer tube provided on the outer peripheral surface of the inner tube and having flexibility; and A connecting member provided on the outer peripheral surface of the rear end of the inner tube and the outer peripheral surface of the rear end of the outer tube, A part of the outer tube enters the inside of a groove formed on the outer peripheral surface of the inner tube, The connecting member overlaps and is in surface contact with the rear end of the inner tube, and overlaps and is in surface contact with the rear end of the outer tube, Protrusions are formed on the inner wall of the connecting member, The protrusions are engaged with the grooves of the inner tube, The connecting member is bonded at least in the overlapping portion overlapping with the rear end of the outer tube.

2. The optical cable traction terminal structure according to claim 1, wherein In the overlapping portion, the connecting member forms a recess at a position facing the outer tube, An adhesive is provided in the recess.

3. The optical cable traction terminal structure according to claim 1, wherein A gap is provided between the outer tube and the connecting member in the longitudinal direction of the inner tube, A water stop member is provided in the gap.

4. The optical cable traction terminal structure according to claim 3, wherein The water stop member is made of a resin material.

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