JP2005185049A - Communication cable and protective tube for communication line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication cable which is unlikely to form bending habit, improved in a bending protection effect such that the cable can easily be bent to a prescribed bending diameter, but a large force is necessary for bending the cable to the smaller diameter, whereby the cable is unlikely to be bent, and to provide a protective tube for communication line. <P>SOLUTION: The communication line of the communication cable is protected with a casing, composed of two or more synthetic resin layers, and a longitudinally continuous spiral slit 15 with a slit width which is substantially zero is formed in the hardest resin layer 13 of the casing. The spiral slit 15 may have a depth that will not penetrate the inside diameter face of the hard resin layer 13. The hard resin layer 13 has a Young's modulus of 1,250 MPa to 20,000 MPa and is preferably formed as the inmost layer of the casing. The communication cable may be constituted, such that a fiber-optic core wire 11 is used as the communication line, and a high-tensile fiber 12 is arranged between the communication line and the casing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a communication cable in which a communication line such as an optical fiber or a twisted electric wire is protected by a synthetic resin sheath, and more particularly to a communication cable used for indoor wiring and a protective tube through which the communication line is inserted.

  Communication cables are used for various types of information transmission and control in vehicles, communication devices, and indoors. As the communication cable, an optical fiber for optical communication or an electric communication wire is used, and the outer periphery of a single-core wire or a multi-core wire is directly or loosely covered with a jacket. Moreover, as a cable form which covers a communication line with a jacket, there is a case where a protective tube serving as a jacket of the communication line is laid in advance, and the communication line is inserted into the protective tube later if necessary.

  For example, an indoor optical cable is usually an optical fiber core wire that is coated with a thermoplastic resin together with a steel wire or FRP (Fiber Reinforced Plastics thin glass fiber hardened with plastic). Bending rigidity is large and difficult to bend. In addition, when the force is released from the bent state, the cable returns to the original state so that it jumps, so that care is required in handling. An optical fiber cord is an optical fiber cord that is covered with a tensile strength fiber and is coated with a thermoplastic resin. The optical fiber cord is easy to bend and has excellent handleability, but is weak in side pressure resistance and impact resistance. For this reason, it has not been suitable for applications in which human hands are touched on a daily basis (for example, optical wiring between an outlet portion and a desk or information equipment).

  Further, these communication lines may be deteriorated in signal transmission characteristics due to bending or lateral pressure, and it is necessary to prevent excessive bending. 2. Description of the Related Art Conventionally, a communication cable using an optical fiber has a configuration in which an annular unevenness is provided on a cable jacket for the purpose of preventing an increase in transmission loss due to bending (for example, see Patent Document 1). ).

  FIG. 7 is a view showing a communication cable having an anti-bending coating disclosed in Patent Document 1, wherein 1 is an optical fiber, 2 is a sheath, and 3 is an anti-bending coating. An optical fiber 1 shown in FIG. 7 is an optical fiber (usually referred to as a plastic fiber) in which a core portion formed of an acrylic resin or a polycarbonate resin is surrounded by a similar resin having a refractive index slightly lower than that of the core portion. Is formed).

The optical fiber 1 shown in FIG. 7 is formed by covering the outer periphery with a sheath 2 made of stretchable polyethylene resin or vinyl chloride resin and covering the outer side with an anti-bending coating 3 formed of a resin equivalent to the sheath 2. ing. And the bending prevention coating | cover 3 becomes the shape which gave the unevenness | corrugation by putting many cyclic | annular groove | channels along the circumference of the surface. The communication cable according to this configuration is said to be capable of preventing the adjacent convex portions and the convex portions of the anti-bending coating 3 from contacting each other when being bent, and bending beyond a certain angle.
Japanese Patent Laid-Open No. 11-223752

  However, since the above-described anti-bending coating 3 has a structure in which irregularities are provided on a coating portion formed of the same resin such as a stretchable polyethylene resin or vinyl chloride resin, it is bent before and after the adjacent convex portions contact each other. The difference in force required for For this reason, when a communication cable is bent, there is a risk that it will be bent below a predetermined bending diameter due to inertia or the like. Further, when adjacent convex portions come into contact with each other, the coating is deformed, and a sufficient bending prevention effect cannot be obtained. Therefore, if the uneven anti-bending coating 3 is formed of a hard resin in order to reduce the deformation of the convex portion, the concave portion will be bent and whitened and cracked when the communication cable is repeatedly bent. Is likely to occur.

  The present invention has been made in view of the above-described circumstances, and can be easily bent with a small force up to a predetermined bending diameter, but requires a large force to bend below that, and is difficult to bend. It is an object of the present invention to provide a communication cable and a communication line protective tube that enhance the bending prevention effect and are difficult to bend.

The communication cable according to the present invention is a communication cable in which a communication line is protected by a jacket made of two or more synthetic resin layers, and is continuous in the longitudinal direction and has a slit width on the hardest resin layer of the jacket. A spiral slit that is substantially zero is formed.
Further, the spiral slit may have a depth that does not penetrate the inner diameter surface of the hard resin layer. The hard resin layer preferably has a Young's modulus of 1250 MPa to 20000 MPa and is formed as the innermost layer of the outer cover. Moreover, it can be set as the structure which used the optical fiber core wire as a communication line and arranged the tensile strength fiber between the communication line and the jacket.

  In addition, the communication line protection tube according to the present invention is a communication line protection tube composed of two or more synthetic resin layers into which the communication line is inserted in a loose state. A spiral slit which is continuous in the longitudinal direction and has a slit width substantially zero is formed.

  According to the present invention, when the communication cable is bent, the slit of the hard resin layer of the jacket can be opened outside the bend and bend with a relatively small force in a range where the bend diameter is relatively large and gentle. However, for bending over a predetermined value, the compressive stress at the edge of the slit of the hard resin layer is increased, making it difficult to bend, and it is possible to effectively prevent bending below a predetermined bending radius.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram for explaining the outline of the present invention, and FIG. 2 is a diagram for explaining the operation of the present invention. In the figure, 10 is a communication cable, 11 is an optical fiber core wire, 12 is a tensile strength fiber, 13 is a hard resin layer, 14 is a soft resin layer, 15 is a spiral slit, and 15a is an edge contact portion.

  In the communication cable 10 of the present invention, when the communication line is an optical fiber, the optical fiber core wire 11 is covered with a jacket without or with the tensile fiber 12 interposed. Moreover, when a communication line is an electric wire, the thing of the form which covered the pair twist conductor or the quad twist conductor with the outer jacket, without or without the shield conductor.

  The outer sheath of the communication line (optical fiber core wire 11) according to the present invention is composed of two or more thermoplastic synthetic resin layers, one of which is formed of a hard resin layer 13 as compared with the other layers. . When the outer cover is formed of two layers, it is preferable that the hard resin layer 13 is on the inner side and the soft resin layer 14 is disposed on the outer side. When the outer cover is formed of three layers, it is preferable that the hard resin layer 13 is disposed in the middle and the soft resin layers 14 and 14 'are disposed on the outer side and the inner side thereof.

  In the present invention, the hard resin layer 13 is provided with a spiral slit 15 continuous in the longitudinal direction. The spiral slit 15 is formed by, for example, applying a sharp blade to a resin tube and cutting it in a spiral shape, and the slit width of the spiral slit 15 is substantially zero. There is a case where a slit width of 0.5 mm or less is generated partially or over the entire length due to some elongation in manufacturing. In the present invention, the substantial slit width is included as zero in such a case as long as it is not functionally impaired.

  The spiral slit 15 is provided so as to penetrate the hard resin layer 13 in the thickness direction. However, it may be in a state where it is not penetrated leaving some thickness. In the latter case, even when the spiral slit 15 does not penetrate in the thickness direction at the beginning of manufacture, the slit is broken in the thickness direction of the resin layer during the laying and handling of the communication cable. In some cases, it may be penetrated. In this case, the spiral slit 15 has a portion that penetrates in the thickness direction of the hard resin layer 13 and a portion that does not penetrate, but the present invention includes such a state. Note that the pitch of the spiral slits 15 is appropriately selected depending on the thickness of each resin layer forming the jacket, the Young's modulus, and the allowable minimum bending diameter of the communication cable.

  As shown in FIG. 1, when the communication cable 10 configured as described above is bent, the edge contact portion 15a of the spiral slit 15 of the hard resin layer 13 serves as a fulcrum on the inner side of the curve, and the spiral slit 15 on the outer side. Is opened and bending is allowed relatively easily. The outer soft resin layer 14 without other slits causes compressive strain on the inner side of the curve and stretches on the outer side. However, since it is a soft resin compared to the hard resin layer 13, it is relatively compressed and compressed. It is easy to respond to stretching and can be easily bent. The hard resin layer 13 is easily bent by the spiral slit 15, but the slit width is substantially zero, is in a close state, has rigidity, and leaves a bending habit by returning to its original state. Will be restored.

  When the bending of the cable progresses and the bending diameter decreases, the hard resin layer 13 causes a large compressive strain in the edge contact portion 15a of the spiral slit 15 due to its rigidity, but the hard resin layer 13 It is hard to produce a deformation | transformation by forming. Further, the stretching stress of the outer soft resin layer 14 also increases, and further, tensile stress is applied to the inner optical fiber core wire 11 and the tensile strength fiber 12. For this reason, even if it tries to bend below a predetermined bending diameter, the stress with respect to bending will increase and it will become difficult to bend.

  FIG. 2 is a diagram for explaining the above-described operation, and shows the relationship between the bending diameter of the communication cable 10 and the force required for bending. In the figure, in the region A where the bending diameter is relatively large and gentle, the edge contact portion 15a of the spiral slit 15 of the hard resin layer 13 on the inner side of the curve does not receive a large compressive strain, and the hard resin on the outer side of the curve. Since the spiral slit 15 of the layer 13 is slightly opened, it can be easily bent with a small bending force. In the region B where the bending diameter is reduced, the edge contact portion 15a of the spiral slit 15 of the hard resin layer 13 is subjected to a large compressive strain, and the force required for bending also increases rapidly.

  Also in the prior art disclosed in Patent Document 1, as shown in FIG. 7, the anti-bending coating has a shape in which a large number of annular slits are inserted along the circumference of the surface to provide unevenness. The region A and the region B exist, and the force required for bending is slightly increased in the region B. However, the recess is formed only up to the middle part of the stretchable anti-bending coating made of a single resin. For this reason, even if contact between convex portions occurs, the difference in force required for bending before and after contact occurs is small, and the state change from region A to region B is not significant. Further, the difference in force required for bending in the region A and the region B is not so large, and the bending is performed until the bending diameter included in the region B is reached.

  On the other hand, in the case of the present invention, the spiral slit 15 having substantially zero slit width is penetrated in the thickness direction of the resin layer with respect to the hard resin layer 13 in the resin layer constituting the jacket. It is formed to do. For this reason, there is no obvious step at the boundary between the region A and the region B, but the difference in force required for bending can be increased. As a result, the force required for bending in the region A where the bending diameter is large and gentle is large in the region B where the bending diameter is small and the force required for bending is clearly different from that in the region A. Can be sensed. As a result, it is possible to reliably prevent bending to a predetermined bending diameter or less.

  1 and 2, an example in which there is no soft resin layer inside the hard resin layer 13 has been described. However, when there is a soft resin layer inside the hard resin layer 13, that is, inside and outside the hard resin layer 13. Even in the case of a three-layer structure having a soft resin layer, it is possible to prevent bending to a predetermined bending diameter or less by the same action. Moreover, when the optical fiber core wire 11 is in a loose state with respect to the jacket, the influence of the tensile force due to bending is small.

  3 and 4 are diagrams for explaining a specific example of the embodiment of the present invention, in which an optical fiber is used as a communication line. FIG. 3A is a diagram showing an example having a soft resin layer outside the hard resin layer, and FIG. 3B is a diagram showing an example having a soft resin layer outside and inside the hard resin layer. FIG. 4 is a diagram for explaining a test example for bending a cable. The reference numerals in the figure are the same as those used in FIG.

  The communication cable 10 in the present invention covers the outer periphery of the optical fiber core wire 11 with a jacket, and is used as a wiring in a vehicle or a communication device, other drop cables or indoor cables, and a connection cord to equipment. The optical fiber core wire 11 used as a communication line is formed by coating a glass fiber composed of a core part and a clad part with an ultraviolet curable resin in one or two layers. In addition, the optical fiber core wire 11 may be referred to as an optical fiber strand when not colored, and in the present invention, the optical fiber core wire 11 is used in the meaning including the optical fiber strand. Shall. For example, as the optical fiber core 11, a glass fiber having a nominal outer diameter of 0.125 mm and a coating of an ultraviolet curable resin having an outer diameter of about 0.24 mm to 0.26 mm is used.

  On the outer periphery of the optical fiber core 11, a resin layer for a jacket is formed by pulling down with or without a tensile strength fiber 12 such as an aramid fiber. For example, the resin layer does not adhere to the optical fiber core 11. It is formed in a tube shape in a loose state. FIG. 3 shows an example in which the tensile strength fiber 12 is vertically attached around the optical fiber core wire 11, but the resin layer for the jacket may be molded in a tight state. The hard resin layer 13 is provided with a spiral slit 15 that performs slit processing in a state where the resin is cured or semi-cured, and has a slit width substantially zero.

  For example, as shown in FIG. 3A, the jacket according to the present invention is formed in a two-layer structure in which at least a hard resin layer 13 and a soft resin layer 14 as a protective layer are disposed on the outer side thereof. In addition, as shown in FIG. 3B, a soft resin layer 14 ′ may be disposed inside the hard resin layer 13 to form a three-layer structure. This inner soft resin layer 14 ′ can also be formed of the same soft resin material as the outer soft resin layer 14. The hard resin layer 13 is preferably made of a thermoplastic resin harder than the soft resin layers 14 and 14 ', and the surface hardness after molding is preferably R100 or more in Rockwell, for example. In addition, the Young's modulus is preferably about 1250 MPa to 20000 MPa for the reason described later.

  As the resin material of the hard resin layer 13, for example, nylon 12, nylon 6, polycarbonate resin, polypropylene resin, polyterephthalate resin, ABS resin and the like are suitable. Also, fillers such as glass fiber, carbon fiber, inorganic powder, metal powder, etc. are added to these resins by about 30% by weight to reduce the linear expansion coefficient of the hard resin layer 13, and the linear expansion coefficient of the optical fiber. It is desirable to reduce the difference. By reducing the difference in coefficient of linear expansion from the optical fiber, it is possible to prevent an increase in transmission loss due to a difference in the line length between the hard resin layer 13 and the optical fiber, particularly when used at low temperatures.

  The soft resin layer 14 is formed of a thermoplastic resin that is softer and stretchable than the hard resin layer 13. Thus, in the bent portion, the outer diameter side of the bend easily expands and the inner diameter side is compressed, so that the bending characteristics are not hindered as described with reference to FIG. As the resin material of the soft resin layer 14, polyethylene, polyvinyl chloride, polyolefin elastomer, polyurethane, and the like are suitable. The outer soft resin layer 14 covers the spiral slit 15 of the hard resin layer 13 to provide a cushioning function for reducing the impact, and prevents foreign matter from entering the spiral slit 15. In addition, the appearance of the cable can be improved, and the unsightly appearance can be reduced even when the wiring is exposed indoors.

FIG. 4 is a diagram showing a test method for a communication (optical fiber) cable formed as described above. According to JIS 6830, which is an optical fiber cord standard, the allowable tensile force of a single-core optical fiber cord having an outer diameter of 4.8 mm is 80 N and the allowable bending diameter is 50 mm. Therefore, it is necessary to prevent bending below the allowable bending diameter below this tensile force. FIG. 4A is a tensile test example for clearing this JIS standard, and a load of 80 N is applied to the communication cable 10 containing the single-core optical fiber according to the present invention by using the corners of a desk or the like. . At this time, in order to set the bending diameter D at the corner to 50 mm or more, the bending rigidity of the cable needs to be 12.5 N · mm ² or more. In this case, it is desirable that the Young's modulus of the hard resin layer 13 is 1250 MPa or more.

Further, according to JIS6830, which is an optical fiber cord standard, the load of a single-core optical fiber cord crush test is 5 N / mm. FIG. 4B is a test example for clearing this JIS standard. The communication cable 10 containing the single-core optical fiber according to the present invention is bent 180 ° and the above-described load is applied. At this time, in order to set the bending diameter D to 50 mm at the bent portion, the bending rigidity of the cable needs to be 3200 N · m ² or less. In this case, it is desirable that the Young's modulus of the hard resin layer 13 is 20000 MPa or less.

  FIGS. 5A and 5B are diagrams showing an example of manufacturing the above-described communication (optical fiber) cable. FIG. 5A is an overall schematic diagram, and FIG. 5B is a diagram showing an example of slit processing. In the figure, 10 is a communication cable after forming a soft resin layer, 10a is a cable immediately after forming a hard resin layer, 10b is a cable after slit processing, 11 is an optical fiber core wire, 12 is a tensile strength fiber, and 18 and 18 'are supplied. Reel, 19 and 19 'are crossheads, 20 and 20' are resin tanks, 21 is a slit processing part, 22 is a capstan, 23 is a take-up reel, 24 is a rotating jig, and 24a is a processing blade.

  In FIG. 5 (A), the optical fiber core wire 11 and the tensile fiber 12 are respectively fed out from the supply reels 18 and 18 'and assembled in front of the first crosshead 19, and then thermosetting from the resin tank 20. The hard resin layer 13 is supplied, and the hard resin layer 13 is formed by the first cross head 19. When a soft resin layer is provided on the inner side of the hard resin layer 13, a crosshead having a configuration capable of covering the first crosshead 19 with two layers is used, or in front of the first crosshead 19. Add another crosshead to form a soft resin layer.

  In the cable 10 a after the hard resin layer 13 is formed by the first crosshead 19, a spiral slit 15 is formed by the slit processing portion 21 with respect to the hard resin layer 13. On the outside of the cable 10b in which the spiral slit 15 is formed, a soft resin layer as an exterior is formed by the second cross head 19 '. A relatively soft thermoplastic resin material is supplied from the resin tank 20 ′ to the second crosshead 19 ′. The communication cable 10 after the soft resin layer is formed is taken up by the capstan 22 and taken up by the take-up reel 23.

For example, as shown in FIG. 5B, the slit processing unit 21 can be configured to include a cylindrical rotating jig 24 having a processing blade 24a on the inside. The rotating jig 24 is rotatably arranged on the cable 10 a immediately after the hard resin layer 13 is formed, and forms a spiral slit 15 in the hard resin layer 13. The spiral slit 15 is formed so as to press the processing blade 24a against the hard resin layer 13 in a cured or semi-cured state from the outer periphery, or formed so that the processing blade 24a cuts the resin layer.
It should be noted that at the stage of forming the hard resin layer 13 or the stage of forming the spiral slit 15, it may be temporarily wound up by the take-up reel 23 to separately form only the outer soft resin layer.

  Further, the example in which the tensile fiber 12 is vertically attached to the outer periphery of the optical fiber core 11 and the outer cover is directly formed on the outer side thereof has been described, but only the outer cover is formed in advance as a tubular communication line protective tube. Alternatively, the optical fiber core wire can be used after being inserted into the protective tube. 6A and 6B are diagrams schematically showing the communication line protective tube, FIG. 6A is a diagram showing an example in which a soft resin layer is not provided inside the hard resin layer, and FIG. 6B is a hard resin. It is a figure which shows the example which has a soft resin layer inside a layer. The reference numerals in the figure are the same as those used in FIG.

  The communication line protection tube 10 ′ shown in FIG. 6A is an example of a two-layer structure in which the soft resin layer 14 is arranged outside the hard resin layer 13, as described with reference to FIGS. A continuous spiral slit 15 is inserted in the longitudinal direction of the hard resin layer 13. The spiral slit 15 is formed by, for example, applying a sharp blade to a resin tube and cutting it into a spiral shape. The slit width of the spiral slit 15 is substantially zero, but it is somewhat difficult to manufacture a cable. In some cases, a slit width of 0.5 mm or less occurs partially or over the entire length. In the present invention, the substantial slit width is included as zero in such a case as long as it is not functionally impaired.

  Further, the spiral slit 15 is provided so as to penetrate in the thickness direction of the hard resin layer 13. However, it may be in a state where it is not penetrated leaving some thickness. In the latter case, the spiral slit 15 may be in the state of not penetrating in the thickness direction at the beginning of manufacture, and then the slit is broken in the thickness direction of the resin layer during laying work and handling of the communication cable, It is because it will be in the state penetrated. On the outer surface of the hard resin layer 13, a softer resin layer 14 than the hard resin layer 13 is formed as in the case of FIG. 3.

  The communication line protection tube 10 ′ shown in FIG. 6B is an example of a three-layer structure in which a soft resin layer 14 ′ is added to the inside of the hard resin layer 13. Except that the soft resin layer 14 'is provided on the inner side, the configurations of the hard resin layer 13 and the outer soft resin layer 14 are the same as in the case of FIG.

  The communication line protective tube 10 ′ shown in FIGS. 6A and 6B has the same configuration and operation as those described in the example of the communication cable in FIGS. Can be easily bent with a relatively small force. However, it becomes difficult to bend with respect to bending with a small diameter, and it is possible to prevent bending to a small diameter of a predetermined value or more. Therefore, it is possible to facilitate the laying operation of the communication line protective tube 10 'itself. Further, since the communication line protective tube 10 'is laid with a bending diameter of a predetermined value or more, when an optical fiber or a signal conducting wire is inserted after laying, the catch at the bent portion is reduced and the insertion is facilitated. be able to. The communication line (for example, the optical fiber core wire 11) can be inserted into the communication line protection tube 10 'by using various well-known wiring methods.

It is a figure explaining the outline of the present invention. It is a figure explaining the effect | action of this invention. It is a figure explaining an example of the communication cable by this invention. It is a figure explaining the test example of the communication cable by this invention. It is a figure explaining an example for manufacturing the communication cable by this invention. It is a figure explaining an example of the protective tube for communication lines by this invention. It is a figure explaining the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Communication cable, 10 '... Communication line protective tube, 11 ... Optical fiber core wire, 12 ... Tensile fiber, 13 ... Hard resin layer, 14, 14' ... Soft resin layer, 15 ... Spiral slit, 15a ... Edge Contact portion 18, 18 '... supply reel, 19, 19' ... cross head, 20, 20 '... resin tank, 21 ... slit processing portion, 22 ... capstan, 23 ... take-up reel, 24 ... rotating jig, 24a ... Processing blade.

Claims (7)

  A communication cable in which a communication line is protected by a jacket made of two or more synthetic resin layers, and is continuous in the longitudinal direction and has a slit width substantially zero in the hardest resin layer of the jacket. A communication cable, wherein a spiral slit is formed.   The communication cable according to claim 1, wherein the spiral slit is formed to a depth that does not penetrate the inner diameter surface of the hard resin layer.   The communication cable according to claim 1, wherein the hard resin layer has a Young's modulus of 1250 MPa to 20000 MPa.   The communication cable according to any one of claims 1 to 3, wherein the innermost layer of the jacket is the hard resin layer.   The communication cable according to claim 1, wherein the communication line is an optical fiber core wire.   The communication cable according to claim 5, further comprising a tensile fiber between the optical fiber core wire and the jacket.   A communication line protective tube comprising two or more synthetic resin layers into which a communication line is inserted in a loose state, wherein the protective tube is the hardest resin layer of the protective tube and is substantially continuous in the longitudinal direction and has a substantially slit width. The communication line protective tube is characterized in that a spiral slit that is zero is formed on the communication line.

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