Optical fiber cable manufacturing method

Abstract

To provide a method for manufacturing an optical fiber cable that has a tensile strength fiber with a lower rigidity than an optical fiber inserted into a closed pipe, and an optical fiber cable that is manufactured by the manufacturing method to obtain high tensile resistance in a longitudinal direction.SOLUTION: A method for manufacturing an optical fiber cable includes fixing and placing a closed pipe taken up into a coil onto a vibration table, making an optical fiber and a tensile strength fiber into a bundle and binding them at their tips in advance, matching a vibration center axis of the vibration table with a tube coil axis with the bound tips inserted into one end of the closed pipe and vibrating the vibration table in a spiral manner, and inserting the optical fiber and the tensile strength fiber into the closed pipe.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical fiber cable. Lu's Regarding the manufacturing method. [Background technology]

[0002] As a technique for imparting tension resistance to optical fiber cables, Patent Document 1 proposes a technique in which a linear or band-shaped flexible tensile strength material is provided along the longitudinal direction of the tube on the outer surface of a flexible tube such as a metal tube through which the optical fiber is inserted.

[0003] Furthermore, Patent Document 2 discloses a technique for inserting an optical fiber into a thin, long tube in a short time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-174293 [Patent Document 2] Japanese Patent Application Publication No. 9-281364 Summary of the Invention [Problem to be solved by the invention]

[0005] In optical fiber cables, the metal tube through which the optical fiber is inserted has high radial strength but low longitudinal tensile strength, so a material that provides tensile strength along the longitudinal direction of the outer periphery of the metal tube is sometimes applied. However, applying such a material to the outer periphery of the metal tube inevitably increases the outer diameter of the cable. On the other hand, the fiber material used to provide tensile strength has lower rigidity than glass optical fibers, making it very difficult to insert the fiber into a long metal tube.

[0006] The object of the embodiment of the present application is to provide a method for manufacturing an optical fiber cable in which tensile strength fibers with lower rigidity than optical fibers are inserted into a long metal tube (hereinafter referred to as a "closed tube") in which communication between the internal space and the outside world is impossible except at both ends, and an optical fiber cable manufactured using this manufacturing method that has high longitudinal tensile strength. [Means for solving the problem]

[0007] The manufacturing method of an optical fiber cable according to an embodiment of the present application is characterized in that a closed tube wound in a coil shape is fixed and placed on a vibrating table, the optical fiber and the tensile strength fiber are bundled and tied together at their tips in advance, the tied tip is inserted into one end of the closed tube, and the vibration center axis of the vibrating table is aligned with the tube coil axis to vibrate the vibrating table in a spiral manner, and the optical fiber and the tensile strength fiber are inserted into the closed tube.

[0008] Here, it is desirable that the optical fibers and the tensile strength fibers are bound together with a binding band wound around the ends of each other.Furthermore, it is desirable that a lead wire having flexibility and elasticity, a weight per unit length greater than the weight per unit length of the optical fibers, and a diameter equal to or smaller than the diameter of the bundle of the optical fibers and the tensile strength fibers is attached to the binding band and inserted into the closed tube.

[0009] By the above manufacturing method, an optical fiber cable is manufactured, which is characterized in that an optical fiber and a tensile strength fiber are inserted into a closed tube. [Effects of the Invention]

[0010] Since the embodiment of the present application is configured as described above, it is possible to provide a method for manufacturing an optical fiber cable in which tensile strength fibers with lower rigidity than optical fibers are inserted into a closed tube, and an optical fiber cable manufactured using this manufacturing method that has high longitudinal tensile strength. [Brief explanation of the drawings]

[0011] [Figure 1]1 is a schematic diagram showing the structure of an optical fiber cable according to an embodiment of the present application. [Figure 2] FIG. 1 is a side view schematically showing an example of an apparatus for inserting a fiber bundle into a closed tube. [Figure 3] FIG. 2 is a plan view schematically showing a vibration table. [Figure 4] FIG. 10 is a schematic diagram showing how a vibration motor is attached to a vibration table. [Figure 5] FIG. [Figure 6] An example in which the tip of a fiber bundle is bound with a binding band is shown in a partial cross section. [Figure 7] An example in which a lead wire is attached to the tip of a fiber bundle is shown in a partial cross section. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present application will be described with reference to the drawings. Note that the drawings described below are schematic diagrams, and the positional relationships between components and the size ratios may not be the same as those of the actual products.

[0013] 1 is a schematic diagram showing the structure of an optical fiber cable 20 of this embodiment. The closed tube P is a flexible metal tube (e.g., a steel tube) formed to a long length (e.g., a total length of 10 m or more), and its outer periphery is covered with a synthetic resin coating layer C. The internal space of the closed tube P is not in communication with the outside except at both ends. In other words, there are no holes or gaps on the side of the closed tube P that would allow communication with the outside world.

[0014] A fiber bundle 6 made up of optical fibers 6a and tensile strength fibers 6b is inserted throughout the entire length of the internal space of the closed tube P. The number of optical fibers 6a inserted varies depending on the application of the optical fiber cable 20, and may be multiple as shown in the figure, or may be one.

[0015] The tensile strength fibers 6b are inserted into the closed tube P in order to improve the tensile strength of the optical fiber cable 20. Suitable examples of the tensile strength fibers 6b include synthetic resin fibers with excellent tensile strength, such as aromatic polyamide fibers, and especially aramid fibers. While such tensile strength fibers 6b have excellent tensile strength, they are less rigid than the glass optical fibers 6a and have a lower weight per unit length, making it extremely difficult to insert them alone into the long closed tube P. For this reason, the tensile strength fibers 6b can be inserted into the long closed tube P together with the optical fibers 6a by bundling them together into a fiber bundle 6.

[0016] Next, a manufacturing method of the optical fiber cable 20 of this embodiment will be described with reference to the drawings. Fig. 2 is an overall side view showing an example of an apparatus for inserting a fiber bundle 6 into the internal space of a closed pipe P formed as a steel pipe, Fig. 3 is a plan view of the vibration table 2, and Fig. 4 is an explanatory diagram of a method for attaching vibration motors 3a and 3b to the vibration table 2.

[0017] The coil R of the closed tube P is placed and fixed on the vibration table 2 by fixing the outer periphery of the lower flange of its bobbin 1 and the axial hole portion with a fixing jig 9 of the vibration table 2 so that it can reliably receive the vibrations of the vibration motors 3a and 3b. A pair of vibration motors 3a and 3b are integrally attached to the vibration table 2, tilted, for example, by 12.5° from the vertical, and the pair of vibration motors 3a and 3b apply vibrations centered on the tube coil axis X. The vibration table 2 is attached to a base 5 via a spring 4, so that the vibrations of the vibration table 2 are not transmitted to the base 5.

[0018] In this embodiment, vibration motors 3a and 3b are rotary vibrators that generate vibrations by utilizing centrifugal force generated by the rotation of unbalanced weights attached to both ends of the rotating shaft. Two of these motors are attached symmetrically to the vibration table 2 with respect to the tube coil axis X. The vibration planes of the pair of vibration motors 3a and 3b form the same angle α with the horizontally placed vibration table 2 surface. Furthermore, other vibration conditions of the vibration motors (frequency, amplitude, etc.) and the rotation direction of the vibrators are also the same, so that the vibrations from the pair of vibrators are combined and applied to the vibration table 2. When such vibrations are applied to the vibration table 2, the coil R of the closed tube P on the table performs circular motion at a constant angular velocity (counterclockwise in the illustrated example) around the intermediate axis of the vibration motors 3a and 3b. By placing the coil R on the vibration table so that this intermediate axis coincides with the tube coil axis X, the axis of the coil R can be aligned with the vibration center axis of the vibration table 2.

[0019] The vibration state of the vibration table is explained using Figure 5. In Figure 5, E is a circle drawn on the vibration table with its center at the tube coil axis X (the central vibration axis), and E' is the circle after circle E has moved due to vibration. As shown, the circle vibrates spirally between the solid circle E and the dashed circle E' due to the vibration of the vibration table. The center of the circle vibrates vertically between P and P', and as you move away from this center, that is, as the diameter of the circle increases, the vibration angle β of each point P1, P2, P3, and P4 on the circumference relative to the horizontal plane decreases, while the amplitudes P1P'1, P2P'2, P3P'3, and P4P'4 gradually increase from PP'. However, the vertical component of the amplitude remains constant. The closed tube coil is placed on a vibration table so that the tube coil axis X and the vibration center axis coincide. Since the closed tube is wound in a coil shape, the above circle corresponds to one turn of the closed tube. Therefore, closed tubes of the same diameter in the coil exhibit the same vibration (same amplitude and vibration angle), while the smaller the diameter of the inner layer closed tube, the smaller the amplitude and the larger the vibration angle β.

[0020] As shown in FIG. 6, multiple optical fibers 6a inserted into the closed tube P are bundled together with tensile strength fibers 6b to form a fiber bundle 6, and their ends are bound together by wrapping a binding band 6c around them. The binding band 6c can be, for example, an adhesive tape. First, the ends of the fiber bundle 6 bound with the binding band 6c are inserted into the tube start end 7 of the closed tube P. In this state, when the spiral vibration described above is applied to the coil R of the closed tube P via the vibration table 2, the fiber bundle 6 is supplied from the tube start end 7, which is one end of the coil below, by the conveying force of the vibration, and continuously enters the closed tube P. That is, the fiber bundle 6 is unwound from the spool 10 journaled on the support 12 and moves in the following order: spool 10 → guide 11 → tube start end 7 → closed tube P of the coil R → tube end 8 due to the vibration of the coil R. After a predetermined time, the fiber bundle 6 is inserted into the entire coil R.

[0021] 7, a lead wire 13 may be attached to a tie band 6c that ties the tip of the fiber bundle 6. The lead wire 13 is made of a flexible and elastic material, for example, a strand of thin metal wires such as stainless steel, or a plastic wire containing metal powder such as iron, and is formed with a diameter equal to or smaller than that of the fiber bundle 6. With this lead wire 13 inserted into the tube start end 7 of the closed tube P in advance, spiral vibrations can be applied to the coil R of the closed tube P via the vibration table 2 as described above, so that the fiber bundle 6 can be inserted into the closed tube P of the coil R following the lead wire 13.

[0022] The closed tube P used in the present application does not have to be a simple cylindrical long tube as shown in the above embodiment, but may be, for example, a long tube formed as a stacked spiral tube to increase flexibility. [Explanation of symbols]

[0023] 1 bobbin 2 vibration table 3a, 3b vibration motor 4 Spring 5 Stand 6 Fiber bundle 6a Optical fiber 6b Tensile strength fiber 6c Cable tie 7 Pipe start end 8 Pipe end 9 Fixture 10 Spool 11 Guide 12 Support 13 Lead wire 20 Fiber Optic Cable C Coating layer P Closed tube R Coil X-tube coil shaft

Claims

1. The closed tube wound into a coil is fixed and placed on a vibration table, The optical fiber and the tensile strength fiber are bundled and bound together at only the tips of the fibers. A method for manufacturing an optical fiber cable, characterized in that the bundled tip is inserted into one end of the closed tube, the vibration center axis of the vibration table is aligned with the tube coil axis, which is the center axis of the coiled portion of the closed tube, and the vibration table is vibrated spirally, and the optical fiber and the tensile strength fiber are inserted into the closed tube.

2. 2. The method for manufacturing an optical fiber cable according to claim 1, wherein the optical fiber and the tensile strength fiber are bound together by a binding band wound around the ends of the optical fiber and the tensile strength fiber.

3. 3. The method for manufacturing an optical fiber cable according to claim 2, characterized in that a lead wire having flexibility and elasticity, a weight per unit length greater than the weight per unit length of the optical fiber, and a diameter equal to or smaller than the diameter of the optical fiber and the bundle of tensile strength fibers is attached to the bundle tie and inserted into the closed tube.

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