RU2797460C1 - Method for exposing core of fibre optic cable and fibre optic cable - Google Patents

Abstract

FIELD: fibre optic cables.

SUBSTANCE: invention relates to a method for exposing the core of a fibre optic cable and to a fibre optic cable. The claimed method of exposing the core of a fibre optic cable contains: a core containing an optical fibre; a winding tube surrounding the core; a sheath containing the core and the winding tube; and an anti-stretch member made of fibre-reinforced plastic embedded in the shell. The method includes the steps of: making a cut in the sheath in the circumferential direction at a location located in the longitudinal direction closer to the first end section of the fibre optic cable than to the second end section of the fibre optic cable; bending the fibre optic cable at the section having a cut to destroy the element that prevents stretching; and remove the removed section of the shell, located between the cut and the first end section.

EFFECT: improvement in the convenience of exposing the core.

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Description

Technical field

The invention relates to a method for exposing the core of an optical fiber cable and to an optical fiber cable.

The present application claims priority based on Japanese Patent Application No. 2019-214076 filed in Japan on November 27, 2019, the contents of which are incorporated herein by reference.

Prior Art

An optical fiber cable typically includes a core containing an optical fiber and a jacket containing the core. In the method for exposing the core of an optical fiber cable disclosed in Japanese Patent Application First Publication No. 2017-3762 (hereinafter referred to as Patent Document 1), a sheath is cut in the circumferential direction, and a sheath portion located between the cut and the end portion of the optical fiber is removed.

Disclosure of invention

Problems solved by the invention

In such fiber optic cables, there is a need to improve the usability of exposing the core. For example, if an anti-stretching member is embedded in the shell, the shell is not easily removed by simply cutting in the circumferential direction of the shell, as in the method proposed in Patent Document 1.

The invention has been made in view of these circumstances, and its object is to provide an optical fiber cable or core exposure method that can improve the convenience of core exposure.

Problem solving tools

In order to solve the above problems, in the method for exposing the core of an optical fiber cable according to the first aspect of the invention, the optical fiber cable includes a core made of an optical fiber, a winding tube enclosing the core, a jacket enclosing the core and the winding tube, and an anti-stretch member, made of fiber-reinforced plastic, embedded in a sheath, and the method includes the steps of: making a cut in the sheath in the circumferential direction at a location located in the longitudinal direction closer to the first end section of the fiber optic cable than to the second end section of the optical fiber cable; bending the fiber optic cable at the section having a cut to destroy the element that prevents stretching; and remove the removed section of the shell, located between the cut and the first end section.

In addition, in the method for exposing the core of an optical fiber cable according to the second aspect of the invention, the optical fiber cable includes a core made of an optical fiber, a winding tube enclosing the core, a jacket including the core and the winding tube, and an anti-stretch member made of fiber reinforced a plastic embedded in a shell, the method including the steps of: making a cut in the shell in the circumferential direction at a first location and at a second location different from the first location in the longitudinal direction; bending the fiber optic cable at a first location and at a second location to destroy the stretch-resistant member; a second incision is made in the longitudinal direction in the shell between the first location and the second location, and the section of the shell located between the first location and the second location is removed.

In addition, the optical fiber cable according to the third aspect of the invention includes a core made of an optical fiber, a winding tube enclosing the core, a sheath enclosing the core and the winding tube, an anti-stretch member made of fiber-reinforced plastic embedded in the sheath, and a wire member that is flexible, includes fibers, and is sheathed. In the cross-sectional view, the wire element is located within an imaginary circle passing through the center of the anti-stretch element and having a center located on the central axis of the core.

Useful effect of the invention

According to the above-described aspects of the invention, it is possible to provide an optical fiber cable or a core-exposing method that can facilitate the work of exposing the core.

Brief description of the drawings

In FIG. 1 is a cross-sectional view of a fiber optic cable according to a first embodiment of the invention;

in fig. 2 is a diagram of a cutting process in a method for exposing the core of an optical fiber cable according to the first embodiment of the invention;

in fig. 3A is a vertical sectional view corresponding to FIG. 2;

in fig. 3B is a process diagram following the process shown in FIG. 3A;

in fig. 3C is a diagram of a process following the process shown in FIG. 3B;

in fig. 3D is a diagram of a process following the process shown in FIG. 3C;

in fig. 4 is a cross-sectional view of an optical fiber cable according to a second embodiment of the invention;

in fig. 5A is a diagram of a cutting process in a method for exposing the core of an optical fiber cable according to the second embodiment of the invention;

in fig. 5B is a process diagram following the process shown in FIG. 5A;

in fig. 5C is a process diagram following the process shown in FIG. 5B;

in fig. 6 is a cross-sectional view of an optical fiber cable according to a third embodiment of the invention;

in fig. 7 is a sectional view of the cable along line VII-VII in FIG. 6;

in fig. 8A is a diagram of a cutting process in a method for manufacturing an optical fiber cable according to a third embodiment of the invention;

in fig. 8B is a diagram of a process following the process shown in FIG. 8A;

in fig. 9A is a diagram of a cutting process in a method for manufacturing an optical fiber cable according to a modified example of the third embodiment;

in fig. 9B is a process diagram following the process shown in FIG. 9A.

The best way to carry out the invention

First Embodiment

Next, with reference to the drawings, an optical fiber cable and a method for exposing the core of an optical fiber cable according to the first embodiment will be described.

As shown in FIG. 1, an optical fiber cable 1A of this embodiment includes a core 2, a winding tube 6, a sheath 101, and an anti-stretch member 8. The 1A fiber optic cable is a so-called slotless fiber optic cable that does not have a slotted core for accommodating optical fibers.

(Determining the direction)

In the exemplary embodiment of the invention, the longitudinal direction of the fiber optic cable 1A is simply referred to as the longitudinal direction. A cut perpendicular to the longitudinal direction is called a transverse cut, and a cut in the longitudinal direction is called a longitudinal cut. In the cross-sectional view, the direction intersecting the center axis O of the fiber optic cable is called the radial direction, and the circumferential direction around the center axis O is called the circumferential direction.

In the longitudinal direction, the E1 side of the first end section (see FIG. 3A) of the optical fiber cable 1A is called the +X side, and the E2 side of the second end section is called the -X side.

The core 2 includes a plurality of optical fiber ribbons 5. The optical fiber ribbons 5 comprise a plurality of optical fibers 3 and a bonding material 4 that binds these optical fibers 3. The optical fibers 3 can be such as fiber optic core wire and fiber optic core wire. element. The optical fiber tape 5 can be a so-called intermittent fixation tape. When the fiber optic ribbon 5 is an intermittently fixed fiber optic ribbon, a plurality of optical fibers 3 are bonded to each other so that they diverge into a web when they are pulled in a direction orthogonal to the longitudinal direction. Specifically, one optical fiber 3 is bonded to two adjacent optical fibers 3 at different locations in the longitudinal direction, and adjacent optical fibers 3 are bonded to each other in the longitudinal direction at a certain interval.

A plurality of fiber optic ribbons 5 are twisted together in an SZ shape or in a spiral shape and enclosed in a winding tube 6. The aspect of the fiber optic ribbons 5 is not limited to the intermittently fixed fiber optic ribbon, and can be changed as necessary. In addition, the number of fiber optic tapes 5 may vary depending on the need, and may include one fiber optic tape. In addition, a plurality of optical fibers 3 can be enclosed in a winding tube 6 without being bound by a binding material 4.

The wrapping tube 6 surrounds the core 2. The wrapping tube 6 can be a non-woven fabric or a polyester tape. The wrapping tube 6 may also have water-absorbing properties.

The sheath 101 accommodates the core 2 and the winding tube 6. The material of the sheath 101 can be polyolefin (PO) resins such as polyethylene (PE), polypropylene (PP), ethylene-ethyl acrylate copolymer (EEA), ethylene-vinyl acetate copolymer (EVA ), ethylene-propylene copolymer (EP) and polyvinyl chloride (PVC). On the outer peripheral surface of the shell 101 formed mark M, indicating the position of the element 8, preventing stretching. In the exemplary embodiment of the invention, the mark M is a protrusion projecting outward in the radial direction and extending along the entire length of the fiber optic cable 1A. It should be noted that the mark M may not be a protrusion but, for example, a concave portion or a colored portion. Even if the mark M is not present, the user can locate the anti-stretch element 8, for example, by the direction of bending of the fiber optic cable 1A due to the pair of anti-stretch elements 8.

The anti-tensile element 8 is embedded in the shell 101. In the present embodiment, the two anti-tensile elements 8 are located in the radial direction so that the core 2 is between them. The anti-stretch element 8 is made of fiber-reinforced plastic. Glass fiber, carbon fiber, aramid fiber, etc. can be used as fibers in fiber reinforced plastics. The number of elements 8, preventing stretching, embedded in the shell 101, may include one, three or more elements. When three or more anti-stretch elements 8 are used, the anti-stretch elements 8 may be spaced at equal intervals in the circumferential direction. In such a case, the directionality of the bend in the fiber optic cable 1A can be suppressed, which facilitates the handling of the fiber optic cable 1A.

Next, a method for exposing the core of the fiber optic cable 1A will be described.

As shown in FIG. 2, first, a tool K such as a knife is brought to the mark M, and advanced into the sheath 101 to cut it. Since the sheath 101 is formed of soft resin, the tool K can be easily advanced into the sheath 101. On the other hand, since the stretching resistance member 8 is formed of fiber reinforced plastic, the cutting resistance of the stretching resistance member 8 is greater than that of the sheath 101. Therefore, when the end of the tool K abuts against the anti-stretch member 8, the advancement of the tool K is stopped. In the present embodiment, the tool K does not completely cut the anti-stretch member 8. However, a portion of the outer periphery of the anti-tensile member 8 may be scratched by the tool K. from its inner side in the radial direction, may remain uncut.

Next, the tool K is moved in the circumferential direction. As a result, the sheath 101 is cut in the circumferential direction as shown by a dotted line in FIG. 2 (cutting process). The cut L is made along at least the entire circumference of the outer surface of the shell 101. In FIG. 2, the position of the cut L in the radial direction is constant over the entire circumference in the circumferential direction; however, the position of the slit L in the radial direction may change in the circumferential direction. In particular, since the resistance to the tool K is less in the circumferential direction where the anti-tensile member 8 is absent, the incision L can extend radially deeper than the location of the anti-tensile member 8.

As shown in FIG. 3A, in the present embodiment, the portion of the sheath 101 located on the +X side (the side of the first end portion E1) with respect to the cut L is referred to as the removable portion 101a, and the portion located on the -X side (the side of the second end portion E2) with respect to the cut L , is called the remaining section 101b.

After the cutting process, the fiber optic cable 1A is bent so that the cutting position L is convex (upper side in FIG. 3B) and concave (lower side in FIG. 3B) in the longitudinal direction as shown in FIG. 3b. In particular, this is done by grasping the portion 101a to be removed and the remaining portion 101b with both hands, and applying a bending force to the fiber optic cable 1A starting from the cut point L. Then, a strong tensile force is applied to the anti-stretch member 8 in the longitudinal direction at the point where section L is made and where the cable is bent convexly. The tensile force leads to the destruction of one of the two elements 8, preventing stretching (destruction process). In particular, if the anti-tensile member 8 is scratched or partially cut during cutting, the anti-tensile member 8 breaks smoothly.

Further, as shown in FIG. 3C, the fiber optic cable 1A is again bent so that the section shown in FIG. 3B was bent to become concave, became convex. This leads to the destruction of the second of the two elements 8, preventing stretching. Thus, in the exemplary embodiment of the invention, the fiber optic cable 1A is bent several times by changing the bending direction, and each anti-stretch member 8 is destroyed as a result of such an operation. It is believed that fiber reinforced plastic, which is the material of which the anti-stretch member 8 is made, can be fractured in such a way that it is not a material that fractures ductilely like metal but easily fractures brittlely. In the breaking process, the sheath 101 located in the radial direction on the inner side of the anti-tensile member 8 may also be destroyed together with the anti-tensile member 8.

Then, a force is applied to tighten the removal portion 101a of the sheath 101 in the direction of the +X side. As a result, tensile stress is concentrated at the portion where the removed portion 101a is connected to the remaining portion 101b (the portion which is radially inward with respect to the slit L), and the portion is destroyed. As a result, the portion 101a to be removed is separated from the remaining portion 101b, as shown in FIG. 3D, and the wrapping tube 6 covered by the removal portion 101a is exposed (removal process). More specifically, the wrapping tube 6 and the core 2 extend from the end surface 101c of the sheath 101 towards the +X side. The end surface 101c is a surface formed by making a cut L in the sheath 101. Since the wrapping tube 6 can be easily separated from the core 2, the user can easily expose the core 2 after the wrapping tube 6 is exposed.

As described above, the optical fiber cable 1A of the present embodiment includes a core 2 containing an optical fiber 3, a winding tube 6 enclosing the core 2, a jacket 101 enclosing the core 2 and the winding tube 6, and an anti-stretch member 8 made fiber-reinforced plastic and embedded in the sheath 101. The method for exposing the core of the fiber optic cable of this embodiment is to make a cut L in the circumferential direction in the sheath 101 at a location located in the longitudinal direction closer to the first end section E1 than to the second end portion E2 of the fiber optic cable 1A (cutting process), and bending the fiber optic cable 1A at the portion where the cut L is made to break the stretch-preventing member 8 (breaking process), and remove the removal portion 101a located between the cut L and the first end portion E1 shell 101 (deletion process). This method of exposing the core makes it possible to easily expose the core 2 even if the sheath 101 has an anti-stretch member 8 embedded in it.

As shown in FIG. 3D, in the process of being removed, the wrapping tube 6 which has been covered by the removal portion 101a extends from the remaining portion 101b located between the cut L and the second end portion E2 in the sheath 101. In this method, by maintaining the state in which the wrapping tube 6 covers core 2, even after the removal process, the optical fiber 3 constituting the core 2 can be protected from accidental damage.

In addition, since the anti-tensile member 8 is also notched during the cutting process, the anti-tensile member 8 can be more easily broken during the breaking process.

Second Embodiment

Next, the second embodiment of the invention will be described. The basic configuration is the same as in the first embodiment. For this reason, the same configurations in different embodiments are designated by the same reference numerals, and their description is omitted, and only the differences are described.

As shown in FIG. 4, the fiber optic cable 1B of the present embodiment further includes an opening cord 7. The opening cord 7 is positioned to be in contact with or adjacent to the wrapping tube 6 and extends in the longitudinal direction. In the example shown in FIG. 4, the opening cord 7 is embedded in the casing 101 in such a way that a portion thereof protrudes from the casing 101 from the inner side in the radial direction. However, the opening cords 7 cannot be embedded in the casing 101 unless the opening cords 7 are designed so as not to move in the circumferential and longitudinal directions. The number of cords 7 for opening the shell can be changed and may include two or more cords.

As a cord 7 for opening the shell, a cylindrical rod made of polypropylene or nylon can be used. The opening cord 7 may also be formed of twisted polypropylene or polyester fibers to provide the water absorption properties of the opening cord 7 .

Except for the opening cord 7, the configuration of the 1B fiber optic cable is the same as that of the 1A fiber optic cable.

Next, a method for exposing the core of the fiber optic cable 1B of the present embodiment will be described.

First, as shown in FIG. 5A, cuts L are made in the casing 101 in the circumferential direction at first and second locations P1 and P2 that are spaced apart in the longitudinal direction (cutting process). Depth, etc. of each cut, L is the same as in the first embodiment of the invention. In the exemplary embodiment of the invention, the section of the sheath 101 located between the first and second places P1 and P2 in the longitudinal direction is called the removable section 101a, and the other section is called the remaining section 101b.

Next, each anti-stretch member 8 is destroyed by bending the optical fiber cable 1B at the first and second locations P1 and P2 (destruction process). The breaking mechanism of the anti-stretch member 8 is the same as in the first embodiment.

Further, as shown in FIG. 5B, in the casing 101 in the longitudinal direction between the first location P1 and the second location P2, a second cut L2 (second cut process) is performed. The second incision L2 is made along the entire length of the section 101a to be removed in the longitudinal direction. The position of the second cut L2 in the circumferential direction is preferably on the opposite side of the opening cord 7 as viewed from the side of the core 2.

Further, by contracting the removal portion 101a in the radial direction, the connection between the removal portion 101a and the remaining portion 101b is broken. As a result, as shown in FIG. 5C, the removal portion 101a is removed and the wrapping tube 6 is exposed (removal process). More specifically, the winding tube 6 and the core 2 are exposed between the two end surfaces 101c of the sheath 101. In this embodiment, the two end surfaces 101c are formed by two cuts L. When the removal portion 101a is removed, the removal portion 101a is elastically deformed so that the second cut L2 opens to form an opening, and the winding tube 6 and the core 2 pass through this opening. In FIG. 5C shows that after the winding tube 6 and the core 2 pass through the opening of the removal portion 101a, the opening is closed under elastic force.

As described above, the method of exposing the fiber optic cable in this embodiment is to cut L in the circumferential direction in the sheath 101 at the first location P1 and the second location P2 spaced apart in the longitudinal direction (cutting process), bending the fiber optic cable 1B at the first location P1 and a second location P2 for destroying the anti-tensile member 8 (breaking process), making a second cut L2 in the shell 101 in the longitudinal direction between the first location P1 and the second location P2 (second cutting process), and removing the removal portion 101a located between the first location P1 and the second place P2 in shell 101 (deletion process). According to such a core exposure method, it is possible to easily expose the core 2 even if the anti-tensile member 8 is embedded in the sheath 101. In addition, the core 2 can be exposed even in the middle portion in the longitudinal direction of the fiber optic cable 1B.

In addition, both by cutting with the tool K and by tearing with the cord 7 to open the casing, longitudinally extending cuts can be made in the removal portion 101a at two different places in the circumferential direction. This facilitates the removal of the removal portion 101a because the removal portion 101a is divided into two parts in the circumferential direction. As previously described, if the removal portion 101a is elastically deformed to form a hole, and the opening is used to separate the removal portion 101a from the wrapping tube 6 and the core 2, the removal portion 101a can be removed without breaking the removal portion 101a with the opening cord 7. Therefore, cord 7 for opening the shell is not a mandatory element.

Third Embodiment

Next, the third embodiment of the invention will be described. The basic configuration is the same as in the first option. For this reason, the same configurations are designated by the same reference numerals, and their explanation is omitted, and only the different points are described.

As shown in FIG. 6, the fiber optic cable 1C of the present embodiment has four anti-stretch elements 8 and four wire elements 9. The anti-stretch elements 8 and wire elements 9 are arranged alternately in the circumferential direction and extend in the longitudinal direction. However, the number and arrangement of elements 8 and 9 can be changed if necessary.

The wire member 9 has an elliptical shape in cross section, and its dimensions in the radial direction are smaller than in the circumferential direction. In the cross section shown in Fig. 6, an imaginary circle C passes through the center of the anti-stretch element 8 and has a center located on the central axis O. Said wire element 9 is located inside the imaginary circle C.

The wire member 9 includes fibers and is flexible. For example, glass fibers and aramid fibers can be used as the fibers of the wire member 9. The fibers of the wire element 9 may or may not be twisted together. The wire element 9 may have a coating (eg resin) covering the surface of the fibers. However, the wire member 9 preferably has sufficient flexibility so as not to break when the fiber optic cable 1C is bent in the breaking process.

As shown in FIG. 7, the fiber optic cable 1C further includes an optional component 10 attached to the first end portion E1. In the example shown in FIG. 7, the additional component 10 is a waterproof connector. However, the additional component 10 may be a type of optical connector other than a waterproof connector, such as a closure or towing device, or a device other than an optical connector. The closing means is a component that protects the exposed optical fiber at the branch point where the optical fiber 3 branches off from the fiber optic cable 1C. The towing device is a component for towing the 1C fiber optic cable when it is laid in a building duct or the like. The wire member 9 is used to increase the fastening strength between these additional components 10 and the fiber optic cable 1C.

The optional component (watertight connector) 10 shown in FIG. 7 has a clamping element 11, a connector block 12, an articulation block 13, a tip 14, a shoe 16, and an outer connector portion 17. The clamping element 11, the connector block 12, the articulation block 13, the tip 14 and the shoe 16 are distributed inside the cylindrical outer section 17 of the connector. The inside of the clamping element 11 is filled with glue (not shown). The waterproof connector 10 with these components is generally cylindrical in shape and surrounds the vicinity of the end surface 101c of the sheath 101. As described in the first embodiment of the invention, the end surface 101c is formed by making a cut L in the sheath 101 at a location near the first end portion E1 of the fiber optic cable 1C. The core 2 and the wire member 9 extend from the end surface 101c in the longitudinal direction in the +X side. The wire member 9 extends farther from the end surface 101c than the anti-stretch member 8. The anti-stretch member 8 may or may not extend from the end surface 101c. The case where the anti-tensile member 8 does not extend further from the end surface 101c is also covered by the phrase "the wire member 9 extends farther from the end surface 101c than the anti-tensile member 8".

Although the detailed representation is omitted, the ferrule 14 has fiber holes for inserting the optical fiber 3 constituting the core 2. The optical fiber 3 constituting the core 2 passes through the waterproof connector 10 and reaches the end (end on the +X side) of the ferrule 14 When the waterproof connector 10 is connected to another optical connector or the like, the optical fiber 3 is optically connected to the optical circuit (optical fiber, optical waveguide, etc.) included in the other connector. Together with the core 2 (optical fiber 3), a winding tube 6 may also extend from the end surface 101c. Alternatively, the winding tube 6 may not extend beyond the end surface 101c.

The sheath 101 and the wire member 9 are attached to the waterproof connector 10 with the adhesive contained in the clamp member 11. In addition, the adhesive prevents water or other substances from entering the waterproof connector 10.

As shown in FIG. 7, the wire elements 9 are folded in half inside the clamp element 11. The section of the folded wire element 9 is located between the sheath 101 and the clamp element 11. The sections of the clamp element 11 and the outer surface 17 of the connector that surround the sheath 101 and the wire element 9 are plastically deformed in the radial direction. inwards, forming a recess 11a. Due to the recess 11a, the wire member 9 is pressed against the sheath 101. With this configuration, the additional component 10 can be more firmly attached to the fiber optic cable 1C.

Next, a method of attaching the accessory 10 to the fiber optic cable 1C (in other words, the method of manufacturing the fiber optic cable 1C to which the accessory 10 is attached) will be described.

First, a fiber optic cable 1C is prepared without additional components 10.

Then, the core 2 and the wire member 9 are released from the sheath 101 at the first end portion E1 of the fiber optic cable 1C in the same procedure as the method for exposing the core of the fiber optic cable 1A described in the first embodiment.

In particular, as shown in FIG. 8A, the tool K is advanced into the sheath 101 while cutting the sheath 101. In addition, when the tool K is moved in the circumferential direction, the sheath 101 and the anti-stretch member 8 are partially cut (cutting process). In the example shown in FIG. 8, the tool K cuts the portion of the anti-tensile member 8 located on the outer side in the radial direction. In other words, in the sheath 101 and the anti-stretch member 8, a cut L is formed along the aforementioned imaginary circle C. The tool K is preferably configured to be movable in the circumferential direction of the fiber optic cable 1C, while the distance from the central axis O (i.e., the position in the radial direction) adjust. The degree of advancement of the tool K into the shell in the radial direction can be changed according to need. However, it is preferable that the cut L is made from the outside of the imaginary circle C (see Fig. 6) in the radial direction so that the wire element 9 is not cut by the tool K.

In the present embodiment, the portion of the sheath 101 located on the +X side (the side of the first end portion E1) relative to the cut L is called the removable portion 101a, and the portion located on the -X side (the side of the second end portion E2) relative to the cut L, is called the remaining section 101b.

After the cutting process, the fiber optic cable 1C is bent so that the cut location L becomes convex and concave in the longitudinal direction (similarly to FIGS. 3B and 3C). As a result, the anti-tensile member 8 breaks at the portion that was scratched or partially cut in the cutting process (breaking process). As shown in FIG. 6, when the four anti-stretch members 8 are arranged in the circumferential direction at equal intervals, the fiber optic cable 1C can be bent several times with a change in the bending direction so that each anti-stretch member 8 is destroyed. Since, in the present embodiment, the anti-tensile member 8 is also fiber reinforced plastic, such failure is likely to occur as a result of brittle failure. On the other hand, since the wire member 9 is mainly composed of fibers and is flexible, the wire member 9 does not collapse even when the fiber optic cable 1C is bent. In other words, in the breaking process in the present embodiment, the tensile resisting member 8 is broken so that the wire member 9 remains intact.

Further, as shown in FIG. 8B, the removal portion 101a of the casing 101 is drawn to the +X side and separated from the remaining portion 101b (removal process). In the exemplary embodiment, when the removal portion 101a is removed, the wireframe 9 is exposed along with the wrapping tube 6. More specifically, the wrapping tube 6, the core 2, and the wireframe 9 extend from the end surface 101c of the sheath 101 toward +X. In this case, the wire member 9, the core 2, and the wrapping tube 6 can extend the same length from the end surface 101c. If necessary, unnecessary sections of the wire element 9 and the wrapping tube 6 can be cut off. Since the anti-tensile member 8 is broken near the end surface 101c, the anti-tensile member 8 may or may not extend slightly further from the end surface 101c.

Next, an additional component 10 is attached to the fiber optic cable 1C. For example, the optical fiber 3 reaches the end of the ferrule 14, and the clamping member 11 is placed over the sheath 101, the wire member 9, and the like. Then, by filling the clamping member 11 with adhesive, the wire member 9 and the like are attached to the additional component 10.

In the case of the optional component (watertight connector) 10 shown in FIG. 7, the plastic deformation process of the clamping member 11 and the outer portion 17 of the connector can be performed.

As described above, the optical fiber cable 1C in this embodiment includes a core 2 containing an optical fiber 3, a winding tube 6 enclosing the core 2, a sheath 101 enclosing the core 2 and the winding tube 6, an anti-stretch member 8 made fiber-reinforced plastic embedded in the sheath 101; and a wire member 9 including fiber embedded in the sheath 101 and flexible. In the cross-sectional view, the wireframe 9 is positioned within an imaginary circle C that passes through the center of the anti-stretch member 8 and has a center located on the central axis O of the core 2. This configuration prevents the wireframe 9 from being cut unintentionally when the tool K makes a cut. L in the shell 101. Accordingly, the work of exposing the core 2 is facilitated.

The fiber optic cable 1C further includes an additional component 10, and the wire member 9 is fixed inside the additional component 10 by extending longer in the longitudinal direction from the end surface 101c of the sheath 101 than the anti-stretch member 8. According to the above configuration, the fastening strength can be stabilized compared to the case where the accessory 10 and the fiber optic cable 1C are bonded by fixing the anti-stretch member 8 mainly inside the accessory 10.

In a cross-sectional view, the wire element 9 has a flat shape. In particular, the dimension of the wire member 9 in the circumferential direction is larger than the dimension of the wire member 9 in the radial direction. This makes it difficult to destroy the wireframe 9 when making a cut L with the tool K. On the other hand, it is possible to increase the cross-sectional area of the wireframe 9 to increase the fastening strength between the additional component 10 and the fiber optic cable 1C.

Example

The above described embodiments of the invention are described below with specific examples, although the invention is not limited to the following examples.

In this example, the fiber optic cable 1A described in the first embodiment was prepared. The relationship between the thickness t of the portion of the sheath 101 located in the radial direction on the inner side of the anti-stretch member 8 and the ease of removal of the removable portion 101a was confirmed. The results are shown in table 1.

Table 1 Thickness t (mm) Removability 0.6 Good 0.8 Good 1.0 Good 1.2 Good 1.4 bad

As shown in Table 1, a plurality of 1A fiber optic cables with different thicknesses t ranging from 0.6 to 1.4 mm were prepared. Then, the cutting process, the breaking process and the removal process described in the first embodiment were carried out. As a result, when the thickness t was 1.2 mm or less, the removed portion 101a of the optical fiber cable 1A could be removed without any difficulty. On the other hand, when the thickness t was 1.4 mm, the removal portion 101a was difficult to remove. This is because when the thickness t is too large, it is difficult to break the connection between the removal portion 101a and the remaining portion 101b even when the removal portion 101a is contracted in the longitudinal direction. Considering the foregoing, it is preferable that the thickness t of the portion of the sheath 101 located in the radial direction on the inner side of the anti-stretch member 8 is 1.2 mm or less.

Further, in the fiber optic cable 1A, the force for pulling the removal portion 101a in the longitudinal direction (hereinafter, pulling force F) and the ease of removal of the removal portion 101a were confirmed. The results are shown in table 2.

table 2 Traction force
F (H) Removability 300 Good 400 Good 500 Good 600 Good 700 bad

The pull force F varies depending on the surface properties of the winding tube 6 (smoothness and the like), the surface properties of the sheath 101, and the shape of the core 2. By varying these parameters, a plurality of fiber optic cables 1A were prepared with different pull force F ranging from 300 to 700 N , as shown in Table 2. Then, the cutting process, the breaking process, and the removal process described in the first embodiment were carried out. As a result, when the pulling force F was 600 N or less, the removal portion 101a could be removed without any difficulty. On the other hand, when the pulling force F exceeded 700 N, it was not easy to remove the removal portion 101a. Considering the foregoing, it is preferable that the pulling force F be 600 N or less when the removal portion 101a is pulled together in the longitudinal direction.

The technical scope of the invention is not limited to the above-described embodiments, and various modifications can be made without departing from the object of the invention.

It is also possible to replace the components in the above described embodiments with well known components without departing from the object of the invention, and the above described embodiments and modifications may be combined as necessary.

For example, the fiber optic cable 1A of the first embodiment of the invention may include the opening cord 7 described in the second embodiment of the invention. In this case, an application is contemplated in which the core 2 is exposed near the first end portion E1 of the fiber optic cable 1A, and then the cladding cord 7 is used to cut the remaining portion 101b.

In the optical fiber cable 1B of the second embodiment, the thickness t of the sheath portion 101 located in the radial direction on the inner side of the anti-stretch member 8 may be 1.2 mm or less.

In the fiber optic cables 1A and 1B of the above embodiment, two anti-stretch members 8 are embedded in the sheath 101 so as to be located on both sides of the core 2, but the sheath 101 may be embedded with three or more anti-stretch members 8 spaced apart from each other. from each other in the circumferential direction. In such a case, the fiber optic cables 1A and 1B can be stripped in the same manner as in the above embodiment by bending them so as to break each of the anti-stretch members 8.

The core exposure method described in the second embodiment can also be applied to the optical fiber cable 1C of the third embodiment. In this case, as shown in FIG. 9A, at a third location P3 between the first location P1 and the second location P2 in the sheath 101, a third cut L3 in the circumferential direction can be made to cut the wire member 9. Next, when the removal portion 101a is removed as shown in FIG. 9B, the wire member 9 extends from the two end surfaces 101c. The wire member 9 can be used to attach the accessory 10 to the fiber optic cable 1C. Such a modification example is suitable, for example, when a closure means is used as an additional component 10. In such a modification example, the fiber optic cable 1C may further include a sheath opening cord 7 as described in the second embodiment. In an alternative embodiment, a wire element 9 can be used as a cord 7 for opening the shell.

List of reference designations

1A, 1B, 1C: Fiber optic cable

2: Core

3: Optical fiber

6: Winding tube

7: Opening cord

8: Anti-stretch element

9: Wire element

101: Shell

101a: Area to be deleted

101b: Remaining section

101c: End face

E1: First end section

E2: Second end section

L: cut

L2: Second cut

P1: First place

P2: Runner-up

Claims (24)

1. A method for exposing the core of an optical fiber cable, comprising: core containing optical fiber, winding tube enclosing the core, a sheath containing the core and the winding tube, and anti-stretch element made of fiber reinforced plastic, embedded in the shell, wherein the method includes the steps of: making a cut in the sheath in the circumferential direction at a location longitudinally closer to the first end portion of the fiber optic cable than to the second end portion of the fiber optic cable; bending the fiber optic cable at the section having a cut to destroy the element that prevents stretching; And remove the removed section of the shell, located between the cut and the first end section. 2. The method of exposing the core of a fiber optic cable according to claim 1, wherein upon removal of the removed portion, the wrapping tube covered with the removed portion is in a state where the wrapping tube extends from the remaining portion of the sheath located between the cut and the second end portion. 3. The method of exposing the core of an optical fiber cable according to claim 1 or 2, wherein, when the removal portion is removed, the pulling force when pulling the removal portion in the longitudinal direction is 600 N or less. 4. A method for exposing the core of an optical fiber cable, comprising: a core containing an optical fiber; a winding tube surrounding the core; a sheath containing the core and the winding tube; And anti-stretch element made of fiber reinforced plastic, embedded in the shell, wherein the method includes the steps of: making a cut in the shell in the circumferential direction at the first location and a second location different from the first location in the longitudinal direction; bending the fiber optic cable at a first location and a second location to destroy the stretch-preventing member; And making a second incision in the shell in the longitudinal direction between the first location and the second location; remove the removed section of the shell, located between the first place and the second place. 5. The method of exposing the core of a fiber optic cable according to any one of paragraphs. 1-4, in which the thickness of the section of the shell located in the radial direction on the inner side of the anti-stretching element is 1.2 mm or less. 6. The method of exposing the core of the fiber optic cable according to any one of paragraphs. 1-5, in which when making a cut in the shell, the cut is also made in the element that prevents stretching. 7. The method of exposing the core of a fiber optic cable according to any one of paragraphs. 1-6, wherein the fiber optic cable further comprises a sheath opening cord extending in the longitudinal direction and positioned to be in contact with or near the wrapping tube.

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