JP2019124877A - Optical fiber cable adapter and method for sealing closure - Google Patents

Abstract

Provided is an optical fiber cable adapter capable of sealing the periphery of an optical fiber cable at a low cost without requiring a special packing when an optical fiber cable having a non-circular cross-sectional shape is introduced into the closure. To do. An optical fiber cable adapter includes a cylindrical pipe member into which an optical fiber cable having a non-circular cross-sectional shape is inserted, and a heat shrinkable tube extending along a longitudinal direction of the optical fiber cable. 30. A hot melt adhesive is applied to the inner peripheral surface of the heat shrinkable tube 30. The heat shrinkable tube 30 includes a first contact portion 32 that is in close contact with the outer peripheral surface of the pipe member 20 via a hot melt adhesive, and a second contact portion that is in close contact with the outer peripheral surface of the optical fiber cable 90 via the hot melt adhesive. The contact portion 34 includes a contact portion 36 that communicates between the first contact portion 32 and the second contact portion 34. [Selection] Figure 1

Description

  The present invention relates to a method of sealing a fiber optic cable adapter and a closure, and more particularly to a method of sealing a closure into which a fiber optic cable is introduced.

  In order to interconnect optical fibers in cables of overhead communication lines and underground communication lines or branch them to a desired building, it is called a closure (terminal box) that houses the optical fiber connection structure and branch structure inside. Case bodies may be used. As the optical fiber cable introduced into such a closure, a cable having a circular cross section is often used, so a round hole is used as a sealing member (packing) for sealing the introduction portion of the optical fiber cable. It is common to use what was formed (for example, refer patent document 1).

  In recent years, instead of a cable having a circular cross section, a cable having a non-circular cross section such as a rectangular shape has come to be used, but the cross sectional shape of these cables does not conform to the above-mentioned round hole shape of packing. Therefore, sufficient airtightness can not be obtained with the packing used conventionally. Therefore, it is necessary to prepare a special packing adapted to the cross sectional shape of the cable, which causes a problem of cost increase.

JP-A-9-312927

  The present invention has been made in view of such problems of the prior art, and it is possible to introduce an optical fiber without the need for special packing when introducing an optical fiber cable having a non-circular cross-sectional shape into a closure. SUMMARY OF THE INVENTION It is a first object of the present invention to provide a fiber optic cable adapter that enables inexpensive sealing of the cable periphery.

  The present invention also provides a closure that can be inexpensively sealed around the fiber optic cable without the need for special packing when introducing the fiber optic cable having a non-circular cross-sectional shape into the closure. A second object is to provide a sealing method.

  According to the first aspect of the present invention, when a fiber optic cable having a non-circular cross-sectional shape is introduced into a closure, the periphery of the fiber optic cable can be inexpensively sealed without the need for special packing. A fiber optic cable adapter is provided. The optical fiber cable adapter includes a cylindrical pipe member into which an optical fiber cable having a non-circular cross-sectional shape is inserted and a heat-shrinkable tube extending in the longitudinal direction of the optical fiber cable. A hot melt adhesive is applied to the inner circumferential surface of the heat shrinkable tube. The heat-shrinkable tube has a first contact portion in close contact with the outer peripheral surface of the pipe member via the hot melt adhesive, and an outer peripheral surface of the optical fiber cable extending from the pipe member via the hot melt adhesive. And a communicating portion for connecting between the first and second contact portions.

  According to the optical fiber cable adapter having such a configuration, it is possible to seal the periphery of the optical fiber cable having a non-circular cross-sectional shape with a heat-shrinkable tube via a hot melt adhesive and to use a cylindrical pipe A packing having an existing round hole formed around the member can be mounted. That is, when introducing an optical fiber cable having a non-circular cross-sectional shape into the closure, the existing round hole-formed packing is used without the need for a special packing adapted to the non-circular cross-sectional shape. It is possible to seal the circumference of the optical fiber cable inexpensively. In addition, since the existing packing can be used, the degree of freedom in the line design of the optical fiber cable is also increased.

  The heat-shrinkable tube is further connected to the second close-contact portion on the opposite side to the connection portion with the second close-contact portion interposed therebetween, and further includes a separation portion separated from the outer peripheral surface of the optical fiber cable May be In addition, the optical fiber cable may have a jacket in which a notch is formed.

  According to the second aspect of the present invention, when introducing an optical fiber cable having a non-circular cross-sectional shape into a closure, the periphery of the optical fiber cable is inexpensively sealed without requiring any special packing. A method of sealing the closure that can be provided. In this method, a heat-shrinkable tube having a hot melt adhesive coated on the inner peripheral surface is prepared, and a cylindrical pipe member is inserted inside the heat-shrinkable tube, and a noncircular cross-sectional shape is formed inside the pipe member. Through the fiber optic cable. The pipe member is inserted into the heat-shrinkable tube, and the optical fiber cable is inserted into the pipe member, and the heat-shrinkable tube is positioned around the pipe member and around the optical fiber cable extending from the pipe member. Heating at least a partial region of the heat-shrinkable tube to melt the hot melt adhesive, and shrinking the heat-shrinkable tube in the region to form the heat-shrinkable tube as the outer peripheral surface of the pipe member Close contact with the outer peripheral surface of the optical fiber cable. After heating the heat shrinkable tube, the hot melt adhesive is cured. A packing is attached to the outside of the heat shrinkable tube in close contact with the outer peripheral surface of the pipe member, and the optical fiber cable is attached to the closure through the packing.

  With such a method, the heat-shrinkable tube can be used to seal the periphery of the optical fiber cable having a non-circular cross-sectional shape through the hot melt adhesive, and the existing rounds can be provided around the cylindrical pipe member. It is possible to mount a packing in which a hole is formed. That is, it is possible to inexpensively seal the periphery of the optical fiber cable using the existing round hole-formed packing, without requiring a special packing adapted to the non-circular cross-sectional shape. In addition, since the existing packing can be used, the degree of freedom in the line design of the optical fiber cable is also increased.

  In the step of heating the heat-shrinkable tube, at least one end of the heat-shrinkable tube is preferably left unheated, and more preferably the both ends of the heat-shrinkable tube are left unheated. Thus, leaving the end of the heat-shrinkable tube unheated prevents the heat applied to the heat-shrinkable tube from being directly transferred to the sheath of the optical fiber cable. Therefore, it is possible to reduce the damage that the heat-shrinkable tube causes to the optical fiber cable.

  In the step of inserting the pipe member into the heat shrinkable tube, it is preferable to insert the entire length of the pipe member into the heat shrinkable tube. In this way, when the heat-shrinkable tube contracts due to heating, it is possible to prevent the pipe member from being exposed, or even if the pipe member is exposed, the exposed portion can be made smaller, so packing can be attached. It is possible to prevent the number of parts from being reduced.

  As the optical fiber cable, an optical fiber cable having a notched outer jacket can be used. In this case, the hot melt adhesive melted by heating the heat shrinkable tube is also filled in the inside of the notch of the jacket of the optical fiber cable, and the heat shrinks because it is cured in a state of being trapped in the notch. The gap between the tube and the fiber optic cable can be closed with a hot melt adhesive. Therefore, even in the case of the optical fiber cable with the notch formed in the jacket, the airtightness between the heat-shrinkable tube and the optical fiber cable can be maintained high.

  According to the present invention, it is possible to seal the periphery of an optical fiber cable having a non-circular cross-sectional shape with a heat-shrinkable tube via a hot melt adhesive, and round holes are formed around the cylindrical pipe member. The formed existing packing can be attached. That is, when introducing an optical fiber cable having a non-circular cross-sectional shape into the closure, inexpensively sealing the periphery of the optical fiber cable without requiring a special packing adapted to the non-circular cross-sectional shape Is possible.

FIG. 1 is a cross-sectional view showing a cable adapter according to an embodiment of the present invention together with an optical fiber cable. FIG. 2 is a cross-sectional view taken along line AA of FIG. FIG. 3A is a schematic view showing a process of sealing a closure using the cable adapter shown in FIG. FIG. 3B is a schematic view showing a process of sealing the closure using the cable adapter shown in FIG. FIG. 3C is a schematic view showing a process of sealing the closure using the cable adapter shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 3C. Note that, in FIG. 1 to FIG. 3C, the same or corresponding components are given the same reference numerals, and duplicate explanations are omitted. In addition, in FIGS. 1 to 3C, the scale and dimensions of each component may be exaggerated and shown, or some components may be omitted.

  FIG. 1 is a cross-sectional view showing an optical fiber cable adapter 10 according to an embodiment of the present invention together with an optical fiber cable 90, and FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1 and 2, the internal structure of the optical fiber cable 90 is not shown. As shown in FIG. 2, the optical fiber cable 90 in the present embodiment has a substantially rectangular cross section, and the optical fiber cable adapter 10 in the present embodiment has light having such a substantially rectangular cross section. It is used to introduce the fiber cable 90 into a closure (not shown).

  A cable with a non-circular cross section is often formed with a notch extending along the longitudinal direction of the outer sheath of the cable in order to divide and cut the cable to facilitate removal of the internal optical fiber. As shown in FIG. 2, such a notch 92 is formed in the jacket of the optical fiber cable 90 in the present embodiment.

  As shown in FIGS. 1 and 2, the optical fiber cable adapter 10 has a cylindrical pipe member 20 into which the above-described optical fiber cable 90 is inserted, and a heat contraction extending along the longitudinal direction of the optical fiber cable 90. A tube 30 is provided. The pipe member 20 is formed of a rigid material, such as acrylonitrile-butadiene-styrene resin, as compared to the heat-shrinkable tube 30.

  The heat-shrinkable tube 30 is formed of, for example, a polyolefin resin, and has a property of shrinking by heating. On the inner peripheral surface of the heat-shrinkable tube 30, for example, a hot melt adhesive 40 (see FIG. 2; not shown in FIG. 1) made of a thermoplastic resin such as polyamide resin is applied.

  As shown in FIG. 1, the heat-shrinkable tube 30 covers the outer peripheral surface of the pipe member 20 and the outer peripheral surface of the optical fiber cable 90 extending from the pipe member 20. That is, a part of the heat-shrinkable tube 30 is shrunk by heating, and is in close contact with the outer peripheral surface of the pipe member 20 and the outer peripheral surface of the optical fiber cable 90 via the hot melt adhesive 40 described above.

  More specifically, the heat-shrinkable tube 30 has a first contact portion 32 in close contact with the outer peripheral surface of the pipe member 20 via the hot melt adhesive 40 and an outer periphery of the optical fiber cable 90 via the hot melt adhesive 40. A second contact portion 34 in close contact with the surface, a communication portion 36 in communication between the first contact portion 32 and the second contact portion 34, and an opposite of the communication portion 36 with the second contact portion 34 in between. And a separated portion 38 connected to the second contact portion 34 on the side and separated from the outer peripheral surface of the optical fiber cable 90.

  By using the optical fiber cable adapter 10 having such a configuration, when the optical fiber cable 90 is introduced into the closure, a special packing adapted to the substantially rectangular cross-sectional shape of the optical fiber cable 90 is not necessary. It is possible to seal the periphery of the optical fiber cable 90 by using the existing round hole-formed packing. Hereinafter, a method of sealing a closure by the fiber optic cable adapter 10 will be described with reference to FIGS. 3A to 3C.

  First, as shown in FIG. 3A, a heat-shrinkable tube 130 having a hot melt adhesive 40 (see FIG. 2) applied to its inner circumferential surface is prepared, and the above-mentioned pipe member 20 is inserted inside the heat-shrinkable tube 130. Do. Then, the optical fiber cable 90 having the substantially rectangular cross section described above is inserted into the pipe member 20. The step of inserting the optical fiber cable 90 into the pipe member 20 may be performed before or after the pipe member 20 is inserted into the heat-shrinkable tube 130.

  The heat shrinkable tube 130 is longer than the pipe member 20, and in the example shown in FIG. 3A, the pipe member 20 is disposed at a position where the entire length of the pipe member 20 is covered by the heat shrinkable tube 130. At this time, the pipe member is covered so that the heat-shrinkable tube 130 covers the optical fiber cable 90 over a certain distance from one end 20A of the pipe member 20 (the end opposite to the side introduced into the inside of the closure). Arrange 20.

  The other end 20B of the pipe member 20 (the end to be introduced into the inside of the closure) may be exposed from the end 130A of the heat-shrinkable tube 130, but such an arrangement will be described later. When the heat-shrinkable tube 130 contracts in the heating step, the exposed portion of the pipe member 20 expands and the region where the packing 60 (see FIG. 3C) can be mounted becomes narrow. Preferably, the pipe member 20 is arranged to be covered.

Further, as described later, in order to reduce the influence of the heat in the heating process on the optical fiber cable 90, as shown in FIG. 3A, the heat shrinkable tube 130 enters the inside by a fixed distance L ₁ from the end 130A. It is preferable to arrange the pipe member 20 in the above position.

  Next, the heat-shrinkable tube 130 of the heating area H is shrunk by heating the predetermined area (the heating area H (see FIG. 3A)) of the heat-shrinkable tube 130 with a hot gun. At this time, due to the heating by the hot gun, the hot melt adhesive 40 applied to the inner surface of the heat shrinkable tube 130 is melted and spreads between the heat shrinkable tube 130 and the outer peripheral surface of the pipe member 20 and the optical fiber cable 90. The heat-shrinkable tube 130 is shrunk by heating and closely attached to the outer peripheral surface of the pipe member 20 and the outer peripheral surface of the optical fiber cable 90 through the hot melt adhesive 40 to be shaped as shown in FIG. 3B.

  At this time, the melted hot melt adhesive 40 is also filled in the inside of the notch 92 (see FIG. 2) formed in the sheath of the optical fiber cable 90, and the heat-shrinkable tube 130 is shrunk. The hot melt adhesive 40 filled inside can be confined within the notch 92.

  When the heating process is completed and the temperature drops, the above-mentioned hot melt adhesive 40 is cured, and the hot melt bonding between the heat shrinkable tube 130 and the pipe member 20 and between the heat shrinkable tube 130 and the optical fiber cable 90 It is fixed by the material 40. Also, since the hot melt adhesive 40 can be cured while the hot melt adhesive 40 is confined in the notch 92 of the optical fiber cable 90, the gap between the heat shrinkable tube 130 and the optical fiber cable 90 can be hot-melted It can be closed with an adhesive 40. Accordingly, the tightness between the heat shrinkable tube 130 and the optical fiber cable 90 is enhanced.

Here, as shown in FIG. 3A, parts of constant distances L ₁ and L ₂ from the both ends 130 A and 130 B of the heat-shrinkable tube 130 are not included in the heating area H, and these parts are left unheated. Is preferred. In this way, when the heat-shrinkable tube 130 is heated by the hot gun, the non-heated portions of the heat-shrinkable tube 130 are necessarily positioned on both sides of the heating area H. Can be suppressed from being directly transmitted to the sheath of the optical fiber cable 90. Therefore, the damage of the heat of the hot gun to the optical fiber cable 90 can be reduced. In particular, an optical fiber cable with a non-circular cross section tends to be thinner and have a thinner jacket than an optical fiber cable with a circular cross section, so the temperature is likely to rise due to heating and damage as described above By providing the non-heated portions on both sides of the heating region H, damage due to such heating can be effectively reduced.

  Next, the heat-shrinkable tube 130 is cut at a cut surface C (see FIG. 3B) in the vicinity of the end 20B of the pipe member 20. Thereby, the optical fiber cable adapter 10 shown in FIG. 1 is completed. If the end 130A of the heat-shrinkable tube 130 does not interfere with the attachment of the optical fiber cable adapter 10 to the closure, this cutting step is unnecessary.

  Here, the portion of the heat-shrinkable tube 130 located around the pipe member 20 which is contracted by the above-mentioned heating becomes the first contact portion 32 in the optical fiber cable adapter 10 and is located around the optical fiber cable 90 extending from the pipe member 20 The portion where the heat-shrinkable tube 130 contracts due to the heating becomes the second contact portion 34 in the optical fiber cable adapter 10, and the end 130B of the heat-shrinkable tube 130 which is not heated outside the heating area H is the optical fiber cable adapter The separation portion 38 in 10 is formed.

  Next, as shown in FIG. 3C, a gripping aid 50 is attached in the vicinity of the cut portion. The gripping aid 50 is composed of two semi-cylindrical members 52 and 52 in which a groove having a shape corresponding to the outer shape (a cross section is substantially rectangular) of the optical fiber cable 90 is formed. The gripping aid 50 is configured to be gripped by a cable gripping portion (not shown) provided in the closure.

  Then, as shown in FIG. 3C, the packing 60 in which the existing round hole is formed is attached to the optical fiber cable adapter 10. Since the pipe member 20 is cylindrical, the pipe member 20 and the heat-shrinkable tube 30 covering the pipe member can be inserted into the round hole of the packing 60, and the heat-shrinkable tube 30 covering the pipe member 20 is outside The packing 60 can be attached. By inserting the packing 60 into a sleeve (not shown) in the closure and assembling the closure, the optical fiber cable 90 is sealed in the periphery of the optical fiber cable 90 having a substantially rectangular cross section. Can be introduced.

  Thus, by using the optical fiber cable adapter according to the present embodiment, the heat-shrinkable tube 30 seals the periphery of the optical fiber cable 90 having a non-circular cross-sectional shape via the hot melt adhesive 40. While being able to do, it becomes possible to mount the packing in which the existing round hole was formed around the cylindrical pipe member 20. That is, when introducing the optical fiber cable 90 having a non-circular cross-sectional shape into the closure, the existing round hole-formed packing is used without requiring a special packing adapted to the non-circular cross-sectional shape. Thus, the periphery of the optical fiber cable 90 can be sealed inexpensively. In addition, since the existing packing can be used, the degree of freedom in the line design of the optical fiber cable 90 is also increased.

  In addition, when packing is to be attached around an optical fiber cable with a notch formed in the jacket, generally, such a notch is filled with a filler such as an adhesive or a compound and then hardened. According to the present embodiment, the heat-shrinkable tube 130 is simply heated to fill the inside of the notch 92 with the hot-melt adhesive 40 and the optical fiber cable of the heat-shrinkable tube 130 according to this embodiment. 90 can be achieved.

  In the embodiment described above, the optical fiber cable 90 having a substantially rectangular cross section is used, but the present invention can also be applied to an optical fiber cable having a non-circular cross sectional shape other than the substantially rectangular cross sectional shape. It is a thing. Moreover, although the notch 92 is formed in the jacket of the optical fiber cable 90, the present invention is also applicable to an optical fiber cable in which the notch is not formed.

  Moreover, although the example which heated the heat-shrinkable tube 130 with the hot gun was demonstrated in embodiment mentioned above, the heating method of the heat-shrinkable tube 130 is not restricted to this, Arbitrary heating methods can be employ | adopted.

  It goes without saying that the materials of the pipe member 20, the heat-shrinkable tube 30, and the hot melt adhesive 40 are not limited to those described above.

  Although the preferred embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to the above-described embodiments and may be implemented in various different forms within the scope of the technical idea thereof.

DESCRIPTION OF SYMBOLS 10 optical fiber cable adapter 20 pipe member 30 heat-shrinkable tube 32 1st close_contact | adherence part 34 2nd close_contact | adherence part 36 connection part 38 spacing part 40 hot melt adhesive 50 grip assistant 52 semi-cylindrical member 60 packing 90 optical fiber cable 92 Notch 130 Heat Shrinkable Tube H Heating Area

Claims (8)

A cylindrical pipe member into which an optical fiber cable having a non-circular cross-sectional shape is inserted;
A heat-shrinkable tube extending along the longitudinal direction of the optical fiber cable and having a hot melt adhesive applied on its inner circumferential surface;
The heat shrinkable tube is
A first adhesion portion in close contact with the outer peripheral surface of the pipe member via the hot melt adhesive;
A second contact portion closely contacting the outer peripheral surface of the optical fiber cable extending from the pipe member through the hot melt adhesive;
A communication unit for communicating between the first contact unit and the second contact unit;
Fiber optic cable adapter.   The heat-shrinkable tube is further connected to the second contact portion on the side opposite to the connection portion across the second contact portion, and further includes a separation portion separated from the outer peripheral surface of the optical fiber cable. Item 1. The fiber optic cable adapter of claim 1.   The fiber optic cable adapter according to claim 1 or 2, wherein the fiber optic cable has a notched outer jacket. Prepare a heat-shrinkable tube with a hot melt adhesive applied to the inner surface,
Inserting a cylindrical pipe member inside the heat shrinkable tube;
Inserting an optical fiber cable having a non-circular cross-sectional shape inside the pipe member,
The pipe member is inserted into the heat-shrinkable tube, and the fiber optic cable is inserted into the pipe member, and the heat-shrinkable tube is positioned around the pipe member and around the fiber optic cable extending from the pipe member Heating at least a partial region of the heat-shrinkable tube to melt the hot melt adhesive and shrinking the heat-shrinkable tube in the region to form the heat-shrinkable tube as the outer peripheral surface of the pipe member and the heat-shrinkable tube Contact the outer surface of the optical fiber cable,
Curing the hot melt adhesive after heating the heat shrinkable tube;
Packing is attached to the outside of the heat shrinkable tube in close contact with the outer peripheral surface of the pipe member,
A sealing method of a closure for attaching the optical fiber cable to a closure through the packing.   5. The method for sealing a closure according to claim 4, wherein in the step of heating the heat shrinkable tube, one end of the heat shrinkable tube is left unheated.   The method for sealing a closure according to claim 5, wherein in the step of heating the heat shrinkable tube, the other end of the heat shrinkable tube is left unheated.   The closure sealing method according to any one of claims 4 to 6, wherein in the step of inserting the pipe member inside the heat shrinkable tube, the entire length of the pipe member is inserted inside the heat shrinkable tube. .   The closure sealing method according to any one of claims 4 to 7, wherein a fiber optic cable having a notched outer jacket is used as the optical fiber cable.

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