JPH0833508B2 - Method for manufacturing optical fiber tube - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing an optical fiber-containing tube (that is, an optical fiber core wire, an optical fiber cord or an optical fiber cable) in which an optical fiber is fixed in the tube.

The optical fiber in the present invention is a fiber strand comprising a core and a cladding layer, a synthetic resin for this fiber strand,
It refers to those coated with metal, ceramics, etc., as well as those of single core, multiple cores, and strands. The term "tube" refers to steel, aluminum, and other metal tubes, and plastic tubes and other non-metal tubes.

(Prior Art) An optical fiber extended to an aerial, sea floor, underground, or the like may be used after being covered with a metal tube or the like in order to prevent excessive tension or to provide environmental resistance. For example, optical communication cables that have been widely used in recent years have been required to have a fiber cord coated with a metal tube because the optical fiber is weak in strength.

By the way, if there is a large difference between the mechanical properties and thermal properties of the cladding and those of the optical fiber, various problems may occur. For example, when an optical fiber cord in which the optical fiber is covered with a metal tube is heated, an excessive tension may be applied to the optical fiber due to the difference in thermal expansion coefficient between the metal tube and the optical fiber. Therefore, there is a problem that the transmission characteristics of the optical fiber are deteriorated, or if the optical fiber has minute cracks, the optical fiber is broken from the cracks. Further, when tension is applied to extend the optical fiber cord, excessive tension may be applied to the optical fiber, which causes problems such as the above-described deterioration of transmission characteristics.

Therefore, conventionally, the optical fiber is made to be somewhat longer than the tube with the optical fiber-containing tube being at a uniform temperature over the entire length. Hereinafter, the extra length is referred to as extra length. Generally, the temperature at the time of manufacturing a tube with an optical fiber (at the time of manufacturing,
The length of the extra length is determined based on the fact that the tube with the optical fiber is at a substantially uniform temperature. For example, the surplus length is increased when the temperature of the optical fiber-containing tube during use is higher than that during manufacturing, and conversely, when the temperature is low, it is decreased. During manufacture, the optical fiber is meandered or undulated in the tube to form an extra length.

Regarding the extra length of such an optical fiber-containing tube, for example, "temperature compensation method for optical fiber cable" disclosed in Japanese Patent Laid-Open No. 57-130002 or "Extra length" disclosed in Japanese Patent Laid-Open No. 59-191517. A method for producing a metal tube containing a long linear body "is known. The former method feeds the optical fiber a little faster than the extrusion speed into the sheath during manufacturing. In the latter method, the optical fiber is fed at a speed higher than the moving speed of the metal hoop and with a constant pushing force.

In addition, it is necessary to prevent the optical fiber from slipping out of the pipe or having an excessive length when the optical cable is processed, transported, or overhead wire. In order to prevent the optical fiber from being pulled out, a method of fixing the optical fiber to the inner surface of the tube at a plurality of points has been proposed. For example, JP-A-57-124313
In the publication, as shown in FIG. 2, a spiral optical fiber is supported by a sponge-like spacer. JP-A-57-130
In the 002 publication, as shown in FIG. 8, it is fixed at a fixed point. Further, in Japanese Patent Laid-Open No. 60-247608, as shown in FIG. 1, it is fixed with a cushioning material composed of a foam material or the like.

(Problems to be Solved by the Invention) However, the present inventors have found that the conventional optical fiber-containing tube has the following problems.

Even if the optical fiber is inserted into the tube with extra length, if the optical fiber is not fixed to the tube as described above, transportation, processing,
There is a risk that the optical fiber may come out of the tube or the excess length may be biased during the work such as overhead line work. And, this fixing means must be easily achieved at the time of manufacturing the optical fiber-containing tube.

However, in the above-mentioned conventional optical cable to which the optical fiber is fixed, the spacer or the cushioning material substantially closes the inner cross-section of the pipe, and it is difficult to insert the spacer and the like into the pipe together with the optical fiber. In particular, when the inner diameter of the pipe is reduced to a few mm or less, the length of the candy becomes longer than several tens of meters.
Its insertion is almost impossible.

In order to avoid these difficulties, there is a method of inserting an optical fiber, a spacer and the like into a material obtained by processing a thin plate into a U-shape through the opening of the material and then closing the opening and welding the joint. However, with this method, the optical fiber may be overheated and deteriorated during welding.

The above publications do not disclose how to insert the spacer or the cushioning material.

Therefore, the present invention is to manufacture an optical fiber-containing tube in which the optical fiber can be easily fixed to the tube by inserting the optical fiber into a small-diameter or long tube without degrading the optical fiber and without damaging the optical fiber. It is intended to provide a method.

(Means for Solving the Problems) In the method for manufacturing an optical fiber-containing tube according to the present invention, before inserting the optical fiber into the tube, the tube is preliminarily coiled to form a coil of the tube, and An adhesive is applied to at least one of the inner surface and the surface of the optical fiber. Then, while supplying the optical fiber from one end of the tube, the coil of the tube is vibrated so that an arbitrary point of the tube reciprocates along a spiral path, and the optical fiber is inserted into the tube. Once the optical fiber is inserted into the tube, the adhesive is treated to bond the optical fiber to the inside surface of the tube.

To form a coil of tubing, the tubing is wrapped around a cylinder such as a bobbin or spool. Also. In order to vibrate the coil of the tube so that any point of the tube reciprocates along a spiral path, the above-mentioned cylindrical body may be driven by a known means such as a vibration motor.

As the adhesive used in the present invention, a special adhesive such as a hot melt adhesive, a rubber adhesive, a CO ₂ curing type, or an adhesive type is used. For hot melt adhesives,
There are thermoplastic and thermosetting resin adhesives that have thermal adhesion. As the thermoplastic adhesive, water-soluble ones such as polyvinyl alcohol and polyethylene oxide, and water-insoluble ones such as polyester and polyethylene are used. Polyurethane or the like is used as the thermosetting adhesive. Examples of rubber adhesives include nitrile rubber and butyl rubber, CO ₂ curable adhesives such as water glass, and adhesive adhesives such as rubber based on plasticized with diphenyl phthalate. An adhesive is used which has a heat softening temperature or a heat curing temperature that is not higher than a temperature at which an optical fiber, a fiber coat or the like is not deteriorated by heat, for example, 180 ° C. or lower.

The treatment of the adhesive for fixing the optical fiber is performed by heating or aeration of CO ₂ gas depending on the characteristics of the adhesive. In the case of heat treatment, the tube may be heated over its entire length, or may be locally heated at intervals along the longitudinal direction of the tube.

In the optical fiber-containing tube manufactured as described above, the optical fiber is inserted into the tube with a waviness, and the portion where the optical fiber is in contact with the inner surface of the tube is generally the peak or valley of the waviness. One or both of the ridges or valleys of the undulations are adhered to the inner surface of the tube, and in some cases every other peaks or valleys are adhered. When the optical fiber is inserted in a twisted manner, the undulation becomes slightly helical, and the ridges or valleys of the undulation come into contact with the inner surface of the tube while changing their positions around the tube axis.

The optical fiber does not necessarily have to be fixed to the inner surface of the tube, and may be in a state of being adhered to the inner surface of the tube via a highly viscous substance as in the case of using an adhesive adhesive.

(Operation) In the method for manufacturing an optical fiber-containing tube of the present invention, since the coil of the tube is vibrated so that any point of the tube reciprocates along a spiral path, the optical fiber in the tube is inclined from the inner wall surface of the tube. Receives a force that moves upward and forward. Due to this force, the optical fiber jumps obliquely upward and forward in the tube or slides on the inner wall surface of the tube. In this way, the optical fiber inside the tube is intermittently provided with a carrier force in the circumferential direction of the coil from the inner wall of the tube to advance inside the tube, and the optical fiber outside the tube is drawn into the tube.

In the above optical fiber insertion method, the pushing force is not applied to the optical fiber from one end, but the entire tube is vibrated so that the optical fiber in the tube is given a forward force by the inner wall surface of the tube. Therefore, a uniform advancing force acts on each part of the optical fiber in the tube, and the excess length of the optical fiber is uniformly distributed in the longitudinal direction of the tube.

The optical fiber inserted as described above is inserted with undulations, and at least one of the peaks and valleys of the undulations is in contact with the inner surface of the tube. Therefore, when a treatment such as heating is applied to the adhesive, the optical fiber is locally fixed to the inner surface of the tube at the contact portion.

As described above, in the method for manufacturing an optical fiber-containing tube of the present invention, the optical fiber is adhered and fixed to the inner surface of the tube, and a member such as a spacer is not used for fixing. Therefore, since fixing members such as spacers do not block the inner cross section of the pipe,
The optical fiber can be easily inserted into the tube.

(Example) An optical fiber cord having an optical fiber inserted in a metal tube will be described below as an example, and a manufacturing apparatus, a manufacturing method, and a product example thereof will be sequentially described.

FIG. 1 is an overall view of the optical fiber cord manufacturing apparatus,
And FIG. 2 is a plan view of the vibration table.

The pedestal 11 is firmly fixed to the floor surface 9 so as not to vibrate. At the four corners on the upper surface of the gantry 11, coil springs 18 for supporting the vibration table are attached.

A square board-shaped vibration table 14 is placed on the frame 11 via a support spring 18. A support frame 15 extends downward from the lower surface of the vibration table 14.

A pair of vibration motors 21 and 22 are attached to a support frame 15 of the vibration table 14. The vibration motor 22 is in a position and posture obtained by rotating the vibration motor 21 by 180 degrees around the central axis C of the vibration table 14. Also, the vibration motors 21,2
Reference numeral 2 indicates a posture in which these rotation axes are parallel to the vertical planes including the central axis C and are inclined by 60 degrees in mutually opposite directions with respect to the vibration table surface. Vibration motor
Unbalanced weights 24 are fixed to both ends of the rotation shafts 21 and 22, and apply a vibrating force to the vibration table 14 in a diagonal direction to the vibration table 14 by centrifugal force generated by the rotation of the unbalanced weight 24. The pair of vibration motors 21 and 22 are driven so that the frequencies and the amplitudes thereof match each other and the directions of the exciting forces are shifted from each other by 180 degrees. Therefore, when the vibrations generated by the pair of vibration motors 21 and 22 are combined, the vibration table 14 vibrates so that the central axis of the vibration motors 21 and 22 coincides with the spiral that coincides with the central axis C of the vibration table 14. Since the vibration table 14 is attached to the mount 11 via the support spring 18 as described above, the vibration table 14
The vibration of 14 is not transmitted to the gantry 11.

The bobbin 27 is fixed on the vibrating table 14 such that the bobbin axis is aligned with the central axis C of the vibrating table 14. The tube 1 through which the optical fiber 7 is inserted is wound around the bobbin 27 in a coil shape, and the optical fiber 7 is supplied into the tube from the lower end of the coil 5 of this tube. The diameter of the coil 5 of the tube is preferably 15 mm or more so as not to give an excessive bending stress to the optical fiber. In this embodiment, the optical fiber 7 is an optical fiber bare wire coated with silicone resin and urethane resin, and the tube 1 is a steel tube. In order to ensure that the bobbin 27 receives the vibrations of the vibration motors 21 and 22, the outer peripheral edge of the lower flange 29 of the bobbin 27 is fixed to the vibration table 14 by a fixing jig 31.
It is fixed at. As shown in FIG. 3, the bobbin 27 is provided with a groove 30 by shaper processing so that irregularities are continuous in the circumferential direction of the body portion 28 in the axial direction of the bobbin, and the pipe 1 is brought into close contact with the groove 30. Has become. Tube 1 this way bobbin 27
The close contact with the groove 30 of the body allows the vibration of the bobbin 27 to be accurately transmitted to the tube 1, and the vibration insertion of the optical fiber 7 can be smoothly and efficiently performed.

A supply spool 34 of an optical fiber supply device 33 is arranged on the side of the bobbin 27. The supply spool 34 is rotatably supported by the bearing base 35. The supply spool 34 draws out the optical fiber 7 wound therearound, and feeds the coiled tube 1.
Supply to. The position at which the supply spool 34 feeds the optical fiber 7 is at substantially the same height as the position at which the optical fiber 7 is supplied to the tube 1.

A drive motor 38 is disposed adjacent to the supply spool 34, and the supply spool 34 and the drive motor 38 are operatively connected via a belt transmission 40. The supply spool 34 is driven to rotate by a drive motor 38, draws out the optical fiber 7, and supplies the optical fiber 7 to the tube 1 wound around the bobbin 27.

An adhesive application device 45 is arranged following the optical fiber supply device 33. The adhesive application device 45 is provided with a spray 49 inside a housing 47, and the adhesive is supplied under pressure to the spray 49.

An adhesive drying device 51 is arranged adjacent to the output side of the adhesive applying device 45. A heated air supply pipe 55 and an exhaust pipe 56 are connected to the housing 53 of the adhesive drying device 51. Then, heated air of 30 to 40 ° C. is blown into the housing 53 from a heated air supply device (not shown).

A lubricant supply device is provided between the adhesive drying device 51 and the pipe inlet end 2.
59 is installed. A solid lubricant made of powder of carbon, talc, tetrafluoroethylene or molybdenum disulfide is used as the lubricant. The lubricant falls from the lubricant supplier 59 into its cylindrical passage 60, and as it passes there, the lubricant adheres to the surface of the optical fiber. The adhesive is a 7 wt% aqueous solution of polyethylene oxide.

A scratch-proof guide 61, which is manufactured separately, is fixed to the inlet end of the pipe 1. The anti-scratch guide 61 is made of a material having a small coefficient of friction such as plastic, and has a tapered guide portion 62 which is opened outward with a curved surface. Since the scratch-proof guide 61 has the above-described structure, the optical fiber 7 can be easily inserted into the tube 1 and, at the same time, the optical fiber 7 can be reliably and smoothly inserted without being damaged. 1 is transferred.

An adhesive heat treatment device 65 is arranged on the side of the vibration table 14. The adhesive heat treatment device 65 includes a stand 67 that supports a reel 71 on which the tube 1 having the optical fiber 7 inserted therein is wound. Also, the housing 66
The inside is heated to about 80 ° C. by the electric heater 68.

Next, a method of inserting the optical fiber 7 into the tube 1 and fixing the optical fiber 7 to the tube by the device configured as described above will be described. FIG. 4 is a flowchart showing the manufacturing process of this optical fiber-containing tube.

In advance, the tube 1 is wound around the bobbin 27 in a coil shape to form the coil 5, and the optical fiber 7 precoated with the optical fiber is also wound around the supply spool 34. Then, the bobbin 27 around which the tube 1 is wound is placed on the vibration table so that the coil axis coincides with the center axis C of the vibration table 14.
14 Fix on top. Then, the optical fiber 7 is pulled out from the supply spool 34, and the adhesive applying device 45 and the adhesive drying device 51 are drawn.
Then, the tip end of the optical fiber 7 is inserted from the scratch-proof guide 61 into the pipe inlet via the lubricant feeder 59. The tube inlet end 2 is located at the lowermost end of the tube coil 5, and the optical fiber 7 is inserted into the tube 1 substantially along the tangential direction of the tube coil 5.

The optical fiber 7 is put in a coiled tube by hand 1-10
Press m. Thereby, the optical fiber is given a sufficient conveying force by the inner surface of the tube due to the vibration of the tube, and the optical fiber surely enters the tube. The pushing length (initial insertion length) is determined by the inner diameter of the tube, the outer diameter of the optical fiber, and the coefficient of friction between the optical fiber and the inner wall surface of the tube. In the initial insertion, if the optical fiber is inserted while applying vibration to the tube, the insertion becomes easy. Also, in order for the optical fiber to enter the tube smoothly, a certain amount of clearance is required between the optical fiber and the tube.
m or more. Furthermore, for the same reason, it is desirable that the diameter of the coil of the tube is 150 mm or more, preferably 300 mm or more.

Next, when the vibration motors 21 and 22 are driven, the vibration motor 2
1 and 22 are attached to the vibration table 14 in the above-described positions and postures, so that the vibration table 14
And a force about the central axis. As a result, the arbitrary point on the vibration table is the helix H shown in FIG.
Vibrates along the line. This vibration is applied to the vibration table 14.
Is further transmitted to the optical fiber 7 through the fixture 31, the bobbin 27, and the coil 5 of the tube. Due to the vibration, the optical fiber 7 receives an acceleration in the vibration direction from the bottom surface of the inner wall of the tube, flies against gravity, and lands. Such a swelling motion is repeated for each vibration or for every several vibrations, and the optical fiber advances in the tube. Further, depending on the frictional state between the bottom surface of the inner wall of the tube and the optical fiber 7, the optical fiber 7 does not fly but slides in the tube to proceed. Since the coil axis coincides with the central axis C of the vibration table 14, the optical fiber 7 in the tube makes a circular motion about the central axis C (a circular motion in the counterclockwise direction P in the example of FIG. 2).

In this way, the optical fiber 7 is paid out from the supply spool 34 by the vibrating article conveying force, and the adhesive applying device 45, the adhesive drying device 51, the lubricant supplying device 59, the damage guide 61, the pipe inlet end 2, the coil shape. The pipe 1 and the pipe outlet end 3 are moved in this order, and after a predetermined time, they are inserted into the entire coil 5.

At this time, the optical fiber fed from the supply spool 34 is immediately coated with the adhesive in the adhesive coating device 45, and then the adhesive is dried.

The optical fiber cord obtained by the above-mentioned optical fiber insertion method has an undulating optical fiber in the tube, and has an extra length to some extent. However, to get a larger margin, do the following:

FIG. 5 (a) shows the front end of the tube 1 in which the optical fiber 7 is inserted as described above. In this state,
The tip of the optical fiber 7 is cut or pushed into the tube to align the tip of the tube with the tip of the optical fiber as shown in FIG. Then, as shown in FIG. 5 (c), the cap 10 is put on the tip of the pipe 1, and the whole pipe is further vibrated. The vibration imparts a carrying force to the optical fiber, but the advancement of the optical fiber is blocked by the cap.
As a result, the pitch of the waviness of the optical fiber 7 becomes smaller and the surplus length becomes larger. The time to vibrate depends on the required extra length. FIG. 5D shows a state in which the above work has been completed and the extra length has increased.

When the optical fiber has been inserted through the entire length of the tube as described above, the tube 1 with the optical fiber 7 inserted is wound on another lighter reel 71 as shown in FIG. Then, the tube 1 in which the optical fiber 7 is inserted is attached to the stand 67.
After being heated and held at about 80 ° C for 1 hour,
Allow to cool. As a result, the adhesive applied to the surface of the optical fiber is softened and then hardened, and the optical fiber 1 is locally fixed to the inner surface of the tube at the portion where the ridges or valleys of the undulation are in contact with the inner surface of the tube.

(Example of product) I Insertion of optical fiber An optical fiber was inserted into a steel pipe under the following conditions by the apparatus shown in FIG.

(1) Specimen Steel pipe coil: Outer diameter (inner diameter) 1.0mm (0.8mm), length 10
Steel pipe coil made by aligning and winding 00m steel pipe (SUS304) on a steel bobbin with a winding diameter of 1200mm.

Optical fiber: A silica glass optical fiber (diameter 125 μm) with a primary coating of silicon resin and a secondary coating of urethane resin, an optical fiber with a diameter of 0.4 mm.

(2) Vibration condition: Vibration angle of coil 30 ° to horizontal plane Vibration frequency 20Hz Vertical component of full amplitude 1.25mm (3) Insertion result: Initial insertion length 3m Transfer speed 2m / min Insertion time 500min Extra length 2m II Optical fiber Fixing (1) Adhesive and its application Adhesive: A 7 wt% aqueous solution of polyethylene oxide Application method: Spray application, application time 2 min (2) Drying adhesive Heating temperature: 40 ° C Heating time: 2 min (3) Heating adhesive Treatment Heating temperature: 80 ℃ Heating time: 1hr Cooling: Cooling As a result of inserting and adhering the above optical fiber, the optical fiber was fixed to the inner surface of the pipe at a pitch of about 25 mm at the ridges or valleys of the undulation.

The present invention is not limited to the above embodiment. For example, the supply of the optical fiber into the tube is not limited to one, but a plurality of optical fibers can be provided in association with the tube inner diameter and the optical fiber diameter. In the above description, the optical fiber is precoated on the element wire, and the tube through which the optical fiber is inserted has been described as a steel tube, but of course not limited to this combination, the optical fiber or its cable is inserted into an aluminum tube, a synthetic resin tube, and so on. Specific examples are possible. When adding the extra length, instead of stopping the end of the optical fiber with the cap, other fixing means such as tying the end to the end of the tube or adhering with an adhesive may be used. Further, the adhesive may be applied to the inner surface of the tube instead of being applied to the surface of the optical fiber.
Further, the optical fiber may be coated with a solid adhesive having a heat-adhesive property such as urethane, and this may be heat-treated for adhesion. That is, urethane has two functions, that is, coneting and adhesion.

(Effects of the Invention) In the method for manufacturing an optical fiber-containing tube of the present invention, since the optical fiber is inserted into the tube by vibration, the optical fiber is inserted into a small-diameter or long tube without degrading and without damaging it. can do. Furthermore, since the optical fiber is adhered to the inner surface of the tube with an adhesive, the optical fiber can be easily fixed to the tube.

[Brief description of drawings]

FIG. 1 is a side view showing an example of an apparatus for inserting an optical fiber into a tube, FIG. 2 is a plan view of a vibration table of the apparatus, and FIG. 3 is a front view showing an example of a bobbin attached to the vibration table. 4 and 5 are flow charts showing a manufacturing process of an optical fiber-containing tube, and FIG. 5 is a drawing for explaining a method of giving an extra length. 1 ... Tube, 5 ... Tube coil, 7 ... Optical fiber, 10 ...
… Caps, 11… Stands, 14… Vibration tables, 21, 22
…… Vibration motor, 27 …… Bobbin, 33 …… Optical fiber supply device, 38 …… Drive motor, 45 …… Adhesive coating device, 51 ・ ・ ・
… Adhesive dryer, 59 …… Lubricant feeder, 65 …… Adhesive heat treatment device

Claims (1)

[Claims] 1. A coil of a tube formed by winding the tube in a coil shape so that an arbitrary point of the tube reciprocates along a spiral path while supplying an optical fiber from one end of the tube. In a method for producing an optical fiber-containing tube by vibrating the optical fiber through the optical fiber into the tube, an adhesive is previously attached to at least one of the inner surface of the tube and the surface of the optical fiber, and the optical fiber is attached to the optical fiber. A method for manufacturing an optical fiber-containing tube, comprising: inserting the optical fiber into the tube, inserting the optical fiber, and then treating the adhesive to bond the optical fiber to the inner surface of the tube.