JP4771991B2 - Optical cable fixing tool and optical cable fixing method - Google Patents

Description

  The present invention relates to a fixture for fixing an end portion of an optical cable to the closure side, and more particularly to a fixture and a fixing method for securely fixing the end portion of the optical cable to the closure side.

Closures (connection branch boxes) are used to connect optical cables in an aerial communication line. In the closure, the outer peripheral surface of the end of the optical cable and the tension member are held by members fixed to the closure side. The following Patent Document 1 is known as a technique for fixing an end portion of an optical cable in a closure. The fixing method disclosed in Patent Document 1 is configured to press a resin-based storage grooved spacer of an optical cable from above and below with a clamp member.
Japanese Patent Laid-Open No. 9-61641

  However, in the fixing method of Patent Document 1, since the outer peripheral surface of the optical cable covering is only pressed from above and below by the clamp member, the axial fixing strength of the optical cable becomes insufficient, and the end of the optical cable is pulled by the tensile force acting on the optical cable. There exists a problem that a part tends to remove | deviate from a clamp member within a closure. Further, since the clamp member holds only the outer peripheral surface of the coating of the optical cable, there is a problem that the fixing strength in the direction around the axis of the optical cable is insufficient, and the end of the optical cable is easily twisted in the direction around the axis.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical cable fixing tool and an optical cable fixing method capable of reliably fixing an end portion of an optical cable to a closure side against external forces in a pulling direction and a twisting direction.

In order to achieve the above object, the invention according to claim 1 is characterized in that a first holding means having an elastic holding portion formed in a spacer with a storage groove of an optical cable and inserted into a storage groove in which an optical fiber is stored; A second part having a projection that is fixed to the closure side in which the end of the optical cable is accommodated and that contacts the elastic holding part by combining with the first holding means and presses the elastic holding part against the inner wall surface of the receiving groove. And an optical cable fixing device.
(Function)
The elastic holding portion of the first holding means inserted into the storage groove is pressed against the inner wall surface of the storage groove of the slot by contact with the projection of the second holding means, and the first holding means and the slot And bond strength increases. The first holding means whose strength of coupling with the slot is increased is fixed to the closure side via the second holding means, and the fixing strength in the tension direction and the twist direction at the end of the optical cable is increased.

  According to a second aspect of the present invention, in the optical cable fixture according to the first aspect of the present invention, the portion of the elastic holding portion that contacts the protrusion is formed in a wedge shape.

  According to a third aspect of the present invention, in the optical cable fixture according to the first or second aspect, the elastic holding portion and the protruding portion are formed according to the number of the storage grooves. .

  According to a fourth aspect of the present invention, in the optical cable fixture according to any one of the first to third aspects, the first holding means and the second holding means are fixed to the closure side. An insertion hole into which the tension member of the optical cable is inserted is formed.

  According to a fifth aspect of the present invention, in the optical cable fixture according to any one of the first to fourth aspects, the first holding means and the second holding means are provided in a direction around the axis of the optical cable. It is characterized in that twist preventing means for preventing twist is formed.

  According to a sixth aspect of the present invention, the first holding means having an elastic holding portion that can be inserted into the storage groove of the storage groove spacer in which the optical fiber is stored is attached to the end of the optical cable, The second holding means fixed to the closure side in which the container is stored and the first holding means are combined, and the protrusion of the second holding means is brought into contact with the elastic holding part to store the elastic holding part. An optical cable fixing method characterized by pressing against an inner wall surface of a groove.

  According to the first and sixth aspects of the invention, since the fixing strength in the pulling direction and the twisting direction at the end of the optical cable is increased, even if an external force in the pulling direction or the twisting direction acts on the optical cable, The end portion is prevented from being detached from the optical cable fixture in the closure, and the reliability of the communication function of the optical cable can be improved.

  According to the second aspect of the present invention, the portion with which the protrusion of the elastic holding portion comes into contact is formed in a wedge shape, so that the elastic holding portion is pressed against the inner wall surface of the storage groove with a large force due to the wedge effect. Thus, the coupling strength between the first holding means and the optical cable can be increased.

  According to the invention described in claim 3, since the elastic holding portion and the protrusion are formed according to the number of the storage grooves, the elastic holding portion and the storage groove can be in a plurality of locations, The coupling strength between the first holding means and the optical cable can be increased.

  According to the fourth aspect of the present invention, since the tension member is fixed to the closure side through the insertion holes of the first holding means and the second holding means, the spacer with the storage groove and the tension member are two closures. Thus, the strength of fixing the end portion of the optical cable to the closure side can be further increased.

  According to the fifth aspect of the present invention, the twisting prevention means of the first holding means and the second holding means can prevent the optical cable from being twisted in the direction around the axis, and the optical cable can be fixed in the twisting direction. It can be further increased.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
1 to 7 show Embodiment 1 of the present invention. In FIG. 6, the code | symbol 1 has shown the optical cable, and the edge part of the optical cable 1 is accommodated in the closure (connection branch box) 11 for the connection of an optical fiber. The closure 11 is suspended from a suspension line 10 for an aerial communication line via a support fitting 12. In the closure 11, the optical fibers of the optical cable 1 and the optical cable 1 ′ are connected to each other. As shown in FIG. 1, the optical cable 1 includes a sheath 2, a slot 3, a tension member 4, and an 8-core tape 6. The sheath 2 is the outermost coating in the optical cable 1 and has a function of protecting inner members such as the slot 3.

  The slot 3 is a resin-type storage groove spacer located inside the sheath 2, and a tension member 4 that reinforces the axial strength of the slot 3 is provided at the axial center of the slot 3. In the slot 3 as a spacer with a storage groove, a plurality of storage grooves 5 for storing an 8-core tape 6 having an optical fiber 7 are formed. In this embodiment, the slot 3 is formed with five storage grooves 5 at equal intervals in the circumferential direction, and the cross-sectional shape of each storage groove 5 extends from the outer peripheral surface of the slot 3 toward the axis. . Each storage groove 5 is formed to be twisted in the direction around the axis of the optical cable 1 as it extends in the axial direction of the optical cable 1. As shown in FIG. 4, the eight-core tape 6 is stored in the storage groove 5 in a ten-layer manner from the groove bottom surface 5 b toward the outside. As shown in FIG. 5, the eight-core tape 6 has a rectangular cross-sectional shape and has eight optical fibers 7 arranged at equal intervals in the lateral direction. In this embodiment, 80 optical fibers 7 are stored in one storage groove 5, and the optical cable 1 has 400 optical fibers 7.

  FIG. 1 shows the internal structure of a closure 11 that fixes the end of the optical cable 1. An optical cable fixture 20 is disposed in the closure 11. The optical cable fixture 20 has a first holding means 30 and a second holding means 35. The base metal fixture 21 fixed to the closure 11 side is formed in a substantially L shape, and has a columnar support portion 22 for fixing the optical cable 1. A through hole 23 extending in the horizontal direction is formed in the columnar support portion 22. As shown in FIG. 3, the columnar support portion 22 is formed with a female screw 24 extending in the axial direction from the top surface. The terminal end of the female screw 24 opens to the inner peripheral surface of the through hole 23. A bolt 40 for fixing the tension member 4 is screwed into the female screw 24.

  As shown in FIG. 1, at the end of the optical cable 1 in the closure 11, the outermost sheath 2 is peeled off by a predetermined length, and the tension member 4 projects from the end face of the slot 3. The 8-core tape 6 is all drawn from the storage groove 5 at the end of the optical cable 1. The storage groove 5 at the end of the optical cable 1 in the closure 11 is secured as a storage space for inserting the elastic holding portion 33 of the first holding means 30. The first holding means 30 is made of, for example, synthetic resin and has a first plate-like portion 31 that faces the end face of the slot 3. The first plate-like portion 31 is formed in an arc shape whose upper portion has substantially the same curvature as the outer peripheral surface of the slot 3. The lower surface 31 a of the first plate-like portion 31 is formed on a flat surface facing the upper surface 21 a of the base metal fitting 21. The lower surface 31 a of the first plate-like portion 31 is in contact with the upper surface 21 a of the base metal fitting 21 when an external force in the twisting direction (a direction around the axis of the optical cable 1) acts on the first holding means 30. One holding means 30 has a function of preventing twisting. Thus, the lower surface 31a of the first plate-like portion 31 has a function as a twist preventing means for preventing the optical cable 11 from twisting around the axis.

  On one side surface of the first plate-like portion 31, an elastic holding portion 33 that protrudes toward the end of the optical cable 1 is formed. The elastic holding portions 33 are formed as many as the number of the storage grooves 5 of the slot 3. The elastic holding portion 33 can be inserted into the storage groove 5 from the axial direction of the optical cable 1. As shown in FIG. 2, the elastic holding part 33 is composed of a first elastic piece 33a and a second elastic piece 33b that are arranged to face each other, and the first elastic piece 33a and the second elastic piece 33b. Each piece 33b can be displaced to the inner wall surface 5a side of the storage groove 5 by an external force. The inside of the elastic holding portion 33 is formed in a wedge shape by the inclined surface 33c of the first elastic piece 33a and the inclined surface 33e of the second elastic piece 33b. That is, the gap between the first elastic piece 33a and the second elastic piece 33b is formed in a wedge shape that becomes smaller toward the tip side by the inclined surfaces 33c and 33e.

  On the other side surface of the first plate-like portion 31, a square hole 32 is opened at a position facing each elastic holding portion 33. The square hole 32 has a quadrangular cross-sectional shape and penetrates the first plate-like portion 32 in the axial direction of the optical cable 1. As shown in FIG. 2, the square hole 32 opens between one elastic piece 33 a and the other elastic piece 33 b of the elastic holding portion 33. The square hole 32 is formed in such a size that a projection 38 of a second holding means 35 to be described later can be inserted. A first fixing hole (insertion hole) 34 into which the tension member 4 of the optical cable 1 can be inserted is formed substantially at the center of the first plate-like portion 31. The first fixing hole 34 passes through the first plate-like portion 31 in the axial direction of the optical cable 1.

  A second holding means 35 can be combined with the first holding means 30. The second holding means 35 is made of synthetic resin, for example, and has a second plate-like portion 36 that faces the first plate-like portion 31. The second plate-like portion 36 has substantially the same external shape as the first plate-like portion 31, and the lower surface 36 a is formed on a flat surface that faces the upper surface 21 a of the base metal fitting 21. The lower surface 36 a of the second plate-like portion 36 is twisted by the contact with the upper surface 21 a of the base metal 21 when an external force in the twisting direction acts on the second holding device 35. It has a function to prevent. As described above, the lower surface 36 a of the second plate-like portion 36 has a function as a twist preventing means for preventing twisting in the direction around the axis of the optical cable 11.

  A plurality of protrusions 38 extending in the axial direction of the optical cable 1 are provided on one side surface of the second plate-like portion 36. Each projection 38 is formed in a bar shape having a square cross-sectional shape, and is provided at a position facing each square hole 32 of the first plate-like portion 31. The protrusion 38 is inserted into the square hole 32 and the elastic holding portion 33 when the second holding means 35 is combined with the first holding means 30. When the second holding means 35 is completely pushed into the first holding means 30 in a state where the first holding means 30 is attached to the end of the optical cable 1, the elastic holding portion 33 is in contact with the protrusion 38. By the contact, it is pressed against the inner wall surface 5 a of the storage groove 5.

  A male screw 37 that can be inserted into the through hole 23 of the base metal fitting 21 is formed on the other side surface of the second plate-like portion 36. A second fixing hole (insertion hole) 37 b into which the tension member 4 of the optical cable 1 can be inserted is formed in the approximate center of the second holding means 35. The second fixing hole 37 b penetrates the axis of the second plate-like portion 36 and the male screw 37 in the axial direction of the optical cable 1. A pressing hole 37 a into which the end of the bolt 40 can enter is formed on the side surface of the male thread 37. The pressing hole 37a opens on the inner peripheral surface of the second fixing hole 37b. A circular nut 41 can be attached to the tip of the male screw 37. A female screw 41 a that can be screwed into the male screw 37 is formed on the shaft center of the circular nut 41. As will be described later, the tension member 4 inserted into the second fixing hole 37b is fixed to the inner peripheral surface of the second fixing hole 37b by a bolt 40 that has entered the pressing hole 37a of the male screw 37. It is like that. The bolt 40 has a function as a twist preventing means for preventing twisting in the direction around the axis of the optical cable 11, similarly to the lower surface 36 a of the second plate-like portion 36.

  Next, a procedure for fixing the end of the optical cable 1 to the closure 11 side will be described. As shown in FIG. 7A, first, the first holding means 30 is attached to the end of the optical cable 1. In a state where the first holding means 30 is attached to the end of the optical cable 1, the elastic holding portion 33 of the first holding means 30 is inserted into the storage groove 5 of the slot 3, and the tension member 4 is the first holding means. It protrudes from 30 first fixing holes 34. Thereafter, the second holding means 35 is combined with the first holding means 30 in the first holding means 30, and the first holding means 30 and the second holding means 35 are brought into close contact with each other. When the first holding means 30 and the second holding means 35 are combined, the protrusion 38 of the second holding means 35 comes into contact with the elastic holding portion 33 of the first holding means 30. FIG. 2 shows a state in which the protrusion 38 and the elastic holding portion 33 are in contact with each other. When the protrusion 38 moves in the direction of the arrow F1, the tip of the protrusion 38 comes into contact with the inclined surface 33c of the first elastic piece 33a and the inclined surface 33e of the second elastic piece 33b, and the first elastic piece 33a and the second elastic piece 33a Each elastic piece 33b is displaced in the direction of arrow F2. That is, the elastic holding portion 33 is formed in a wedge shape at the portion that contacts the protrusion 38, so that the outer surface 33 d of the first elastic piece 33 a is brought into contact with one inner wall surface 5 a of the storage groove 5 by contact with the protrusion 38. The outer surface 33 f of the second elastic piece 33 b is pressed against the other inner wall surface 5 a of the storage groove 5. Therefore, as shown in FIG. 7B, in the state where the projection 38 is completely inserted into the elastic holding portion 33, the first elastic piece 33a and the second elastic piece 33b are connected to the inner wall surface 5a of the storage groove 5. It will be in the state contact | adhered enough and the joint strength of the elastic holding | maintenance part 33 and the slot 3 will be raised.

  Next, as shown in FIG. 7 (c), the male screw 37 of the second holding means 35 is inserted into the through hole 23 of the base fitting 21, and a circular nut is attached to the tip of the male screw 37 protruding from the through hole 23. 41 is screwed together. Thereby, the second plate-like portion 36 of the second holding means 35 is in close contact with the columnar support portion 22 of the base metal fitting 21, and the second holding means 35 is fixed to the base metal fitting 21. Since the elastic holding portion 33 of the first holding means 30 is firmly coupled to the protrusion 38 of the second holding means 35 by the wedge effect, the first holding means 30 is interposed via the second holding means 35. It is firmly fixed to the base metal fitting 21. The tension member 4 is fixed to the inner peripheral surface of the second fixing hole 37b of the male screw 37 of the second holding means 35 by a bolt 40 screwed into the base metal fitting 21. Since the second holding means 35 is fixed to the base metal fitting 21, the tension member 4 is also fixed to the base metal fitting 21 via the second holding means 35.

  Thus, since the end of the optical cable 1 is fixed to the base metal fitting 21 on the closure 11 side using the five storage grooves 5 formed in the slot 3, the outer peripheral surface of the slot 3 is simply fixed from the vertical direction. Compared with the structure to make, the coupling | bonding strength with the slot 3 can be raised remarkably. Thereby, even if an external force in the pulling direction and the twisting direction acts on the optical cable 1, the end of the optical cable 1 is prevented from being detached from the optical cable fixture 20 in the closure 11, and the reliability of the communication function of the optical cable 1 is improved. be able to. Furthermore, since the tension member 4 that reinforces the slot 3 is fixed to the base metal fitting 21 via the first holding means 30 and the second holding means 35, the strength in the tension direction and the twist direction at the end of the optical cable 1. Can be further enhanced.

  The elastic holding portion 33 of the first holding means 30 engages with the storage groove 5 of the slot 3 in the direction around the axis of the optical cable 1, and the lower surface 31 a of the first plate-like portion 31 of the first holding means 30 and Since the lower surface 36a of the second plate-like portion 36 of the second holding means 35 can come into contact with the upper surface 21a of the base metal fitting 21, even when an external force in the twisting direction acts on the optical cable 1, the optical cable 1 of this optical force is generated by this external force. Disengagement from the optical cable fixture 20 can be reliably prevented. Further, since the optical cable fixture 20 can be fixed to the base metal fitting 21 of the conventional closure 11, the existing (off-the-shelf) closure 11 can be used as it is.

  Note that if the shape of the through hole 23 of the base metal 21 is a quadrangle, and the shape of the portion that fits the through hole 23 of the male screw 37 of the second holding means 35 is a quadrangle, the twist about the axis of the optical cable 1 is made. It is possible to further increase the strength.

(Embodiment 2)
FIG. 8 shows a second embodiment of the present invention. The difference between the second embodiment and the first embodiment is only the structure for supporting the second holding means on the closure side, and the other parts conform to the first embodiment. By attaching the same reference numerals, the description of the corresponding parts is omitted. The same applies to other embodiments described later.

  In FIG. 8, the second holding means 50 is formed with a cylindrical portion 51 into which the columnar support portion 22 is inserted. The cylindrical portion 51 extends in the vertical direction along the side surface opposite to the side surface on which the projection 38 of the second plate-shaped portion 36 is formed, and is integrally molded with the second plate-shaped portion 36. The through hole 52 into which the male screw 37 of the first holding means 30 is inserted passes through the second plate-like portion 36 and the tubular portion 51.

  In the second embodiment configured as described above, the cylindrical portion 51 of the second holding means 50 is inserted into the columnar support portion 22, so that the second holding means 50 is fixed to the base metal fitting 20 with a large area. Thus, the fixing strength of the second holding means 50 on the closure 11 side can be increased as compared with the structure of the first embodiment. Further, the second holding means 50 has an increased strength against torsion around the axis of the optical cable 1 by inserting the cylindrical portion 51 into the columnar support portion 22, and the optical cable 1 due to external force in the twisting direction. Can be prevented from coming off in the closure.

(Embodiment 3)
9 and 10 show Embodiment 3 of the present invention. As shown in FIG. 9, a male screw 37 and a pair of support plates 55 are provided on the side surface of the second holding means 35 opposite to the side surface on which the projection 38 of the second plate-like portion 36 is formed. Yes. The support plate 55 is disposed on the left and right with the male screw 37 as the center. A second fixing hole 37b into which a tension member (not shown) can be inserted is formed at the axial center of the male screw 37. The tension member protruding from the tip of the male screw 37 is screwed onto the male screw 37, for example. The front end of the male screw 37 is fixed by a lock screw (not shown). The support plate 55 is formed with a bolt hole 55a through which the bolt 15 for fixing the second holding means 35 to the closure side is inserted. As shown in FIG. 10, the support plate 55 is located between the upper fixing plate 13 and the lower fixing plate 14 fixed to the closure side, and is fixed to the upper fixing plate 13 and the lower fixing via bolts 15. It is connected to the plate 14.

  In the third embodiment configured as described above, the support plate 55 of the second holding means 35 is fixed to the closure side via the upper fixing plate 13 and the lower fixing plate 14. The second holding means 35 can be fixed to the closure side without using the base metal fitting 21 as in the first and second embodiments. Therefore, the fixing structure of the end portion of the optical cable can be simplified as compared with the first and second embodiments.

  As described above, the embodiments of the present invention have been described in detail, but the specific configuration is not limited to these embodiments, and even if there is a design change or the like without departing from the gist of the present invention, It is included in this invention. For example, in the first embodiment, the number of storage grooves 5 formed in the slot 3 is five, but the number of storage grooves 5 may be larger or smaller. Further, although the cable is an eight-core tape, any cable other than the eight-core tape may be used as long as the cable has a resin-type storage groove spacer. Moreover, although the cross-sectional shape of the storage groove 5 is rectangular and the 8-core tape 6 is stored in 10 layers, the cross-sectional shape of the storage groove 5 may be trapezoidal or the like according to the shape of the tape core wire. Furthermore, although the tension member 4 that reinforces the slot 3 is a single wire, the present invention can also be applied to the optical cable 1 in which the tension member 4 is composed of a plurality of stranded wires.

  In Embodiment 1, the shape of the contact portion with the storage groove 5 in the elastic holding portion 33 is a flat surface. However, as shown in FIG. 11, the serrated engagement surface 33 g is used as the storage groove in the elastic holding portion 33. 5, or by forming a plurality of conical protrusions 33 h in contact portions with the storage groove 5 in the elastic holding portion 33, as shown in FIG. 12, the elastic holding portion 33 and the storage groove It becomes possible to further increase the bonding strength with the inner wall surface 5a.

It is a disassembled perspective view of the optical cable fixing tool concerning Embodiment 1 of this invention. It is an expanded sectional view of the elastic holding | maintenance part of the 1st holding means in the optical cable fixing tool of FIG. It is principal part sectional drawing of the 2nd holding means in the optical cable fixing tool of FIG. It is an expanded sectional view of the slot of the optical cable of FIG. It is an expanded sectional view of the 8-core tape accommodated in the accommodation groove | channel of the slot of FIG. It is a front view which shows the attachment state of the closure in which the edge part of the optical cable of FIG. 1 is accommodated. FIG. 3 is a work process diagram illustrating a procedure for fixing an end portion of the optical cable of FIG. 1 to the closure side. It is a disassembled perspective view of the optical cable fixing tool concerning Embodiment 2 of this invention. It is a perspective view of the 2nd holding means in the optical cable fixing tool concerning Embodiment 3 of this invention. FIG. 10 is a front view showing a state in which the second holding means of FIG. 9 is fixed to the closure side. It is an expanded sectional view which shows the modification of the elastic holding | maintenance part in FIG. It is an expanded sectional view which shows another modification of the elastic holding | maintenance part in FIG.

Explanation of symbols

1 Optical cable 3 Slot (spacer with storage groove)
4 Tension member 5 Storage groove 5a Inner wall surface 6 8 core tape 7 Optical fiber 11 Closure 20 Optical cable fixture 21 Base bracket 22 Column-shaped support portion 23 Through hole 30 First holding means 33 Elastic holding portion 33a First elastic piece 33b First Second elastic piece 35 Second holding means 37 Male thread 38 Projection 40 Bolt 41 Circular nut

Claims (6)

  A first holding means having an elastic holding portion formed in a spacer with a storage groove of the optical cable and capable of being inserted into a storage groove in which the optical fiber is stored; and the first holding means fixed to the closure side in which the end of the optical cable is stored An optical cable fixture comprising: a second holding means that comes into contact with the elastic holding portion when combined with the holding means, and has a protruding portion that presses the elastic holding portion against the inner wall surface of the housing groove. .   The optical cable fixture according to claim 1, wherein a portion of the elastic holding portion that is in contact with the protruding portion is formed in a wedge shape.   The optical cable fixture according to claim 1, wherein the elastic holding portion and the protrusion are formed according to the number of the storage grooves.   4. An insertion hole through which a tension member of the optical cable fixed to the closure side is inserted is formed in the first holding means and the second holding means. An optical cable fixture according to any one of the above.   5. A twist preventing means for preventing twisting of the optical cable in a direction around an axis of the optical cable is formed in the first holding means and the second holding means. The optical cable fixture described in 1.   A first holding means having an elastic holding portion that can be inserted into a storage groove of a storage groove spacer for storing an optical fiber is attached to an end portion of the optical cable, and the end portion of the optical cable is fixed to the closure side in which the optical cable is stored. The second holding means and the first holding means are combined, and the protrusion of the second holding means is brought into contact with the elastic holding part to press the elastic holding part against the inner wall surface of the storage groove. A characteristic optical cable fixing method.

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