JPS63180922A - Method for inserting optical fiber into pipe - Google Patents

Abstract

PURPOSE:To facilitate the insertion of an optical fiber by vibrating the coil of a pipe so that the optical fiber reciprocates from an optional point of a pipe along a spiral path. CONSTITUTION:The optical fiber 7 is pressed in the coiled pipe by a hand firstly by 5-150m and given a sufficient conveyance force by the internal surface of the pipe through the vibration of the pipe to securely enter the pipe. Then when vibration motors 21 and 22 are driven, a vibration table 14 receives torque around a center axis C and a force in the center axis direction because the vibration motors 21 and 22 are fitted to the vibration table 14, so that the optional point of the vibration table vibrates along the spiral H. The spiral vibration is conducted to the coil 5 of the pipe through the vibration table 14 and then the optical fiber 7 supplied from a pipe entrance end 2 below the coil 5 moves into the pipe 1 continuously with the body conveyance force of the vibration. Consequently, the optical fiber 7 is given the conveyance force for the fiber insertion.

Description

Detailed Description of the Invention (Industrial Application Field) This invention relates to a method for inserting an optical fiber into a pipe, and more particularly, to a method for inserting an optical fiber into a tube or a sheath. Relating to a method for manufacturing a cable.

In this invention, the optical fiber includes a fiber wire consisting of a core and a crat layer, a fiber coated with synthetic resin, metal, ceramic, etc., and single-core fibers, multi-core fibers, and more. It refers to a line. In addition, pipe refers to steel, aluminum and other metal pipes, and plastic pipes and other non-metallic pipes.

(Prior Art) Optical communication cables that have become widely used in recent years are required to have a metal-coated structure because optical fibers are weak in strength.

Conventionally, as a method for manufacturing an optical fiber line in which an optical fiber is inserted into a tube such as a metal tube, a tape forming-welding method (for example, Japanese Patent Laid-Open No. 60-46869) is known. In this method, a metal tape is formed into a tubular shape, and both edges of the tape are welded to manufacture the tube, while an optical fiber is inserted.

In addition, another method is the tube insertion method (for example, JP-A-58-
25606) is known. In this method, an aluminum tube with a steel wire inserted inside the tube is manufactured, the tube is reduced in diameter, and the steel wire inside the tube is then replaced with an optical fiber.

(Problems to be Solved by the Invention) In the tape forming-welding method described above, when the optical fiber passes through the welding point, it is easily affected by the welding heat and changes in quality, and when the pipe diameter is small, 2H or less. It has disadvantages such as being technically difficult to insert.

In addition, with the tube insertion method described above, the manufacturing process becomes complicated;
Another disadvantage is that it is difficult to use a replacement blade that is stronger than the fiber because of the risk of breakage, and it is difficult to use a replacement blade that is longer than 200 m.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for inserting an optical fiber into a long tube without deteriorating the quality of the optical fiber or damaging the optical fiber.

(Means for Solving the Problems) In the method of inserting an optical fiber into a tube according to the present invention, the tube is wound into a coil to form a coil of the tube. To form a coil of tubing, the tubing is wound around a cylindrical body such as a bobbin or spool. Next, the optical fiber is inserted into the tube manually or automatically using pinch rolls or the like from one end of the tube to a length that provides a sufficient conveying force to draw the optical fiber into the tube. Then, while supplying the optical fiber from one end of the tube, the coil of the tube is vibrated so as to reciprocate along a spiral path from an arbitrary point on the tube. To vibrate the tube coil, the cylindrical body may be driven by a known means such as a vibration motor.

The insertion length (initial insertion length) is about 5 to 150 m, and 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. Initial insertion of the optical fiber is facilitated by applying vibration to the tube.

(Operation) When the coil of the tube is vibrated so that any point on the tube reciprocates along a spiral path, the optical fiber within the tube receives a force directed diagonally upward and forward from the inner wall surface of the tube. Due to this force, the optical fiber jumps diagonally upward and forward within the tube or slides on the inner wall surface of the tube. In this way, the optical fiber inside the tube is intermittently given a conveying force in the coil circumferential direction by the inner wall of the tube to advance inside the tube, and the optical fiber outside the tube is drawn into the tube.

By inserting the optical fiber into the tube in advance as described above, sufficient conveying force for insertion of the optical fiber is applied to the optical fiber.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1 is an overall view of the apparatus of the present invention, and FIG. 2 is a plan view of the vibrating table.

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

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

A pair of photographing motors 21 and 22 are attached to the support frame 15 of the vibration table 14. Vibration motor 2
2, the vibration motor 21 is aligned with the center axis 0 of the vibration table 14.
It is in a position and attitude rotated 180 degrees around. Also,
The vibration motors 21 and 22 are arranged such that their rotation axes are parallel to a vertical plane including the central axis C, and are inclined at 75 degrees in opposite directions with respect to the vibration table surface. The vibration motors 21 and 22 have unbalanced weights 24 fixed to both ends of the rotating shaft, and apply an excitation force in an oblique direction to the surface of the vibration table 14 by centrifugal force caused by the rotation of the unbalanced weights 24. . This pair of vibration motors 21,
22 are driven such that their frequencies and amplitudes match each other, and their excitation directions are shifted by 180 degrees from each other. Therefore, when the vibrations caused by the pair of vibration motors 21 and 22 are combined, the vibration table 14 vibrates along a spiral whose central axis coincides with the central axis C of the vibration table 14.

Since the vibration table 14 is attached to the pedestal 11 via the support spring 18 as described above, the imaging table 14
The vibrations of the vibration motors 21 and 22 are not transmitted to the pedestal 11.Instead of the above-mentioned photographing motors 21 and 22, for example, a vibration device using a crank, a cam, or an electromagnet may be used as the vibration device. The method of attachment to the table 14 is not limited to that shown.

The bobbin 27 is fixed on the vibrating table 14 so that the bobbin axis coincides with the center axis C of the vibrating table 4. The tube 1 through which the optical fiber 7 is inserted into the bobbin 27
is wound into a coil, and an optical fiber 7 is supplied into the tube from the lower end of the coil 5 of this tube. In order not to apply excessive bending stress to the optical fiber, the diameter of the tube coil 5 is 1.
It is desirable that it is 50 mm or more. In this example,
The optical fiber 7 is an optical fiber wire precoated with resin, and the tube 1 is a steel tube. The outer periphery of the lower flange 29 of the bobbin 27 is fixed to the vibration table 14 with a fixing jig 31 so as to reliably receive the vibrations of the vibration motors 21 and 22. As shown in FIG. 3, the bobbin 27 has a groove 30 formed by shaving in the circumferential direction of the body 28 so that the unevenness is continuous in the bobbin axial direction, and the tube 1 is placed in close contact with the groove 30. It has become.

The optical fiber 7 is gradually inserted while applying vibration to the bobbin 27, but if the bobbin 27 to be directly vibrated and the tube 1 wound around it are not in close contact, the vibration will not be accurately transmitted to the tube 1. , smooth insertion of the optical fiber 7 becomes impossible. The tube 1 wound around the bobbin body 28 is connected to the bobbin 2
Although it is easy to make a close contact with the body part 28 in the 7 radial direction, it is difficult to make a close contact with the bobbin 27 in the axial direction. This means that the tube 1 cannot vibrate uniformly in the vertical direction over its entire length. However, if the tube 1 is placed closely within the groove 30 of the body of the bobbin 27 in this way, the vibrations of the bobbin 27 can be transmitted to the tube 1 with high precision.
Vibration insertion of the optical fiber 7 can be carried out smoothly and efficiently.

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 on a bearing stand 35. The supply spool 34 lets out the optical fiber 7 wound thereon and supplies it to the coiled tube 1. The position at which the supply spool 34 unwinds the optical fiber 7 is approximately at the same height as the position at which the optical fiber 7 is supplied to the tube 1.

A drive motor 38 is arranged 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 rotationally driven by a drive motor 38 to feed out the optical fiber 7 and supply the optical fiber 7 to the tube 1 wound around the bobbin 27 .

A holding guide 43 is provided close to the optical fiber feeding position of the supply spool 34 . The holding guide 43 consists of a short tubular main body 44 and a stand 45 that horizontally supports the stiffener, and holds the optical fiber 7 fed out from the supply spool 34.

Following the holding guide 43, the optical fiber feeding state detection device 4
7 is placed. Optical fiber feeding state detection device 47
consists of a support column 48 and an optical fiber height position detector 49 attached to the support column 48. The optical fiber height position detector 49 is composed of an image sensor and a light source placed opposite to the image sensor, and is located at a position where the optical fiber 7 passes, and detects the degree of slack in the optical fiber 7. A CCD line sensor is used as the image sensor.

A rotation speed control device 52 is connected to the optical fiber feeding state detection device 47, and the rotation speed control device 52 controls the voltage of the power source of the drive motor 38 based on a signal from the detection device 47. That is, the rotation speed of the drive motor 38, that is, the feeding speed of the optical fiber 7 is controlled according to the height position at which the optical fiber 7 blocks the optical fiber height position detector 49 from the light source.

During the insertion of the optical fiber 7 into the tube 1, the insertion speed of the optical fiber 7 is not necessarily constant and may vary depending on the co-photography phenomenon and the conditions of the inner surface of the tube and the surface of the optical fiber. Therefore, if the speed of the optical fiber 7 inside the tube 1 fluctuates, it will affect the feeding state of the optical fiber 7 outside, and if this feeding speed cannot follow the insertion speed of the optical fiber 7, the feeding speed of the optical fiber 7 will be affected. Unnecessary slack or disconnection due to excessive tension may occur, which may impede the smooth supply of the optical fiber 7. However, by driving and rotating the supply spool 34 as described above, the optical fiber 7 in the tube 1 is
By changing the rotational speed of the supply spool 34 or stopping it depending on the transport state of the optical fiber 7, it is possible to always supply the optical fiber 7 within a required supply speed range. In other words, the optical fiber 7 can be maintained in the best condition (slightly slack as shown in FIG. 1) without becoming too stretched or too slack. As a result, the optical fiber 7 can be inserted into the tube 1 without any hindrance without putting a burden on the optical fiber 7 itself, that is, without giving any resistance to the insertion of the optical fiber 7. By the way, the diameter is 0
．． When inserting a 4 mm optical fiber into a steel pipe with an inner diameter of 0.5 mm, if the force applied to the optical fiber toward the optical fiber supply side is 20 gf or more, the optical fiber will not enter the pipe.

A vibration-proofing guide 54 is installed between the optical fiber feeding state detection device 47 and the pipe entrance 142, and the vibration-proofing guide 54 consists of a cylindrical main body 55 and a stand 58 that horizontally supports the main body 55. . As shown in FIG. 4, both ends of the main body 55 of the anti-vibration guide 54 have tapered portions that open outward.
Funnel part) 57. It is preferable that the boundary between the tapered portion 57 and the cylindrical portion 56 be processed into a curved surface without corners. The length of the anti-vibration guide 54 may be appropriately determined depending on the distance between the pipe inlet end 2 and the supply spool 34, and naturally, the longer this distance, the longer the anti-vibration guide 54 should be. Furthermore, the vibration-proofing guide 54 may be made of a material having a small friction coefficient, such as glass or plastic, so as not to inhibit the transport of the optical fiber 7 due to vibration.

A lubricant supply device 59 filled with lubricant is attached to the cylindrical portion 56 of the anti-vibration guide 54 . A solid lubricant made of powder such as carbon, talc, or molybdenum disulfide is used as the lubricant. The lubricant drops from the lubricant supply device 59 into the cylindrical portion 56, and as it passes through this, the lubricant adheres to the surface of the optical fiber.

When the coil 5 of the tube through which the optical fiber 7 is inserted is vibrated,
A large deflection occurs in the optical fiber 7 in front of the end face of the tube l, which impedes smooth vibration insertion and also comes into contact with the edge of the tube inlet i42 and damages the optical fiber surface. Furthermore, if the deflection is large, cracks may also occur inside the optical fiber. However, this anti-vibration guide 5
4 suppresses vibrations outside the end of the tube 1, and a good transfer state can be maintained without damaging the optical fiber 7 or providing any resistance to the vibration transfer of the optical fiber 7.

As shown in FIG. 5, a separately manufactured damage prevention guide 6I is fixed to the artificial end of the tube 1. The scratch-proof guide 61 is made of a material with a small friction coefficient such as plastic.
It is provided with a tapered guide portion 62 that expands outward with a curved surface.

When the optical fiber 7 is inserted into the coiled tube 1, the vibration of the tube 1 causes the optical fiber 7 inserted from the tube inlet end 2 to move forward while colliding with the tube inlet end 2 due to the vibration of the optical fiber 7. At this time, the optical fiber 7 is connected to the edge of the pipe entrance end 2.
Scratches occur in the longitudinal direction, and these scratches cause cracks in the optical fiber 7, degrading product quality. However, 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 causing any scratches. It is transferred inside the tube 1.

Next, a method for inserting the optical fiber 7 into the tube 1 using the apparatus configured as described above will be explained.

In advance, the tube 1 is wound in a coil around the bobbin 27 to form the coil 5, and the optical fiber 7, which is a pre-coated fiber strand, is also wound around the supply spool 34. Note that the tube 1 is not limited to being wound in one layer around the bobbin 27, but is often wound in multiple layers. In this case, the first layer is bobbin body 2.
8, but the second and subsequent layers will fit between the tubes 1 of the previous layer. Next, the bobbin z7 around which the tube 1 is wound is fixed on the vibration table 14 so that the coil axis and the center axis C of the vibration table 14 coincide. Then, the optical fiber 7 is pulled out from the supply spool 34,
The distal end of the optical fiber 7 is inserted into the tube entrance from the anti-damage guide 61 via the holding guide 43, the optical fiber feeding state detection device 47, and the anti-vibration guide 54.

The tube entrance end 2 is located at the lowest end of the tube coil 5, and the optical fiber 7 is inserted into the tube 1 along a substantially tangential direction of the tube coil 5.
It is designed to be inserted inside.

The optical fiber 7 is initially placed in a coiled tube with 5 to 15 fibers.
0 m pushed. As a result, sufficient transport force is applied to the optical fiber by the inner surface of the tube due to the vibration of the tube, and the optical fiber reliably enters the inside of the tube. In addition, 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, and 0.1
It is desirable that the thickness is not less than mm. Further, for the same reason, it is desirable that the diameter of the tube coil is 150 mm or more, preferably 300 mm or more.

Next, when the vibration motors 21 and 22 are driven, since the vibration motors 21 and 22 are attached to the vibration table 14 in the positions and postures described above, the vibration motors 21 and 22 are driven.
is subjected to a torque about the central axis C and a force in the direction of the central axis. As a result, any point on the vibration table vibrates along the spiral H shown in FIG. This vibration is transmitted from the vibration table 14 to the optical fiber 7 through the fixing fitting 31, the pobbin 27, and the tube coil 5 in this order.

Although the movement of the optical fiber changes depending on the type of vibration, the physical properties of the optical fiber, the inner diameter of the tube, etc., it is thought that the optical fiber travels inside the tube in the following manner.

As shown in FIG. 6, the bottom surface of the inner wall of the tube is vibrating at a vibration V centering on O. The vibration angle is θ, and the maximum acceleration is n times the acceleration of gravity 9 (nsin θ>1). Since it is difficult to imagine that the optical fiber is in contact with the bottom surface of the tube inner wall over the entire length, it is assumed that the optical fiber is in contact with the bottom surface of the inner wall of the tube over the entire length. Let the contact point be a. Contact point a is reached when the vertical acceleration of the bottom of the inner wall of the pipe becomes downward equal to 9, that is, the separation line 1
, and is released at the upper separation point P1. The released optical fiber starts flying at the current speed Vl and radiation angle θ. On the other hand, since the optical fiber is not a rigid body at the non-contact point,
It moves differently from contact point a. In other words, the vibration V does not generate as much upward force as the contact point a, and after it is released on the separation line 21, it receives a downward force generated as the contact point a moves. As a result, the vehicle lands on the landing line 22 at a new contact point A that is different from the first contact point a. If the vibration V of the bottom of the pipe inner wall at this time is in the rising direction, continue rising as it is at the separation line 1. released above. If it lands when the vibration V is in the downward direction, it will once descend to the lowest position, then start rising and be released above the departure line 1 in the same way. Such waviness motion is repeated for each vibration or every few vibrations, and the optical fiber advances within the tube. The most efficient condition is the landing line 1 during the rise of each vibration. coincides with the departure line JZ2, and the optical fiber starts flying at the same time as it lands.

Strictly speaking, friction phenomena, repulsion phenomena, etc. between the bottom surface of the tube inner wall and the optical fiber should be taken into consideration. Needless to say, when the flying optical fiber comes into contact with the upper surface of the inner wall of the tube, the traveling state is different.

Further, when n sin θ≦1, the optical fiber does not fly, but slides and advances depending on the friction condition between the bottom surface of the inner wall of the tube and the optical fiber.

The optical fiber 7 is propelled into the tube by the coil circumferential component of the force received from the inner wall of the tube 1 as described above. Since the coil axis and the central axis C of the vibration table 14 coincide, the optical fiber 7 in the tube performs a circular motion (in the example of FIG. 2, a circular motion in the counterclockwise direction P) about the central axis C.

The explanation will be given by returning to FIG. 1 again.

When the above spiral vibration is applied to the tube coil 5 through the vibration table 14, the optical fiber 7 supplied from the tube entrance end 2 below the coil 5 continuously enters the tube 1 due to the article conveying force of the vibration. Go. That is, the optical fiber 7 is paid out from the supply spool 34, and the holding guide 43, the optical fiber feeding state detection device 47, the anti-vibration guide 54, the anti-scratch guide 6
1. The tube inlet end 2, the coiled tube 1, and the tube outlet end 3 are moved in this order by the vibration of the coil 5, and are inserted through the entire coil 5 after a predetermined time.

During the insertion of the optical fiber 7, if the speed of insertion into the pipe changes due to some factor, this will affect the feeding state of the optical fiber 7 at the position of the optical fiber height position detector 49, and this will affect the detection. It is immediately detected by the device 49. That is, if the optical fiber height position detector 49 detects that the optical fiber 7 is too tensioned, a signal thereof is sent to the drive motor 38 to increase the spool rotational speed and thereby increase the supply speed of the optical fiber 7. Furthermore, if excessive slack in the optical fiber 7 is detected, the drive motor 38 is similarly controlled to slow down the supply speed of the optical fiber 7.

In this way, abnormal transport conditions of the optical fiber 7 are immediately detected, corrected, and normal transport conditions restored.

(Specific Example) In order to confirm the effects of the present invention, an optical fiber was inserted into a steel pipe using the apparatus shown in FIG. 1 under the following conditions (Table 1). The insertion results are shown in Table 1.

(1) Test material steel pipe coil: The outer diameter (inner diameter) shown in Table 1 is 0.8 to 2.
Off1mφ (0.5~1.6mn+) Length IO・
7 types of steel pipe coils made by winding 7 types of steel pipes of Km in order on a steel bobbin with a winding trunk diameter of 1200 mm (10 to 20 layer windings).

A secondary optical fiber was used.

An optical fiber with a diameter of 0.4 m + n, which is a quartz glass optical fiber (diameter 125 μm) coated with silicone resin.

(2) Vibration conditions 2 The steel pipe coil used in this example has 10 winding layers (No. 1 to 6 in Table 1) and 20 winding layers (No. 7).
Therefore, all parts of the tube are subject to almost the same vibration conditions.

Vibration angle of the coil with respect to the horizontal plane: 15 degrees Frequency: 20 Hz Vertical component of total amplitude: 1.25 to 1.55 mm The insertion results are shown in Table 1.

Further, FIG. 7(a) and FIG. 7(b) each show the vibration of the bobbin in the fourth embodiment shown in Table 1. Fig. 7(a) shows a state in which the optical fiber has not yet been inserted into the pipe, and Fig. 7(b) shows a state in which only one optical fiber has been inserted into the pipe.
000m is inserted. In these figures, AV indicates the vertical component of the amplitude, and A indicates the horizontal component of the amplitude. As is clear from FIG. 7(b), when the optical fiber is inserted into the tube, a high frequency component appears in the vibration of the coil. These amplitudes were measured by an accelerometer attached to the bobbin flange.

Through this experiment, it was confirmed that the optical fiber could be inserted into the steel pipe extremely smoothly without any trouble, and that it could be inserted through the entire length of the steel pipe within a predetermined time. Also, as is clear from Table 1,
Even when inserting an optical fiber into a small diameter tube of 2 mm or less,
It is quite possible to insert a long tube of about m in length into the IO, and of course the optical fiber inserted therein will not be deteriorated in quality.

This invention is not limited to the above embodiments.

The supply of optical fibers into the pipe is not limited to just one, but may also include a plurality of optical fibers depending on the pipe inner diameter and the optical fiber diameter. In the above explanation, we have explained that the optical fiber is a pre-coated wire and the pipe through which the optical fiber is inserted is a steel pipe, but of course the combination is not limited to this, and there are many other ways such as inserting the optical fiber or its cable into an aluminum pipe, a synthetic resin pipe, etc. Some concrete examples can be considered. Further, post-processes such as surface reduction processing may be added after the optical fiber is inserted into the metal tube, and may be performed as appropriate depending on the operator or the situation. The light beam and eye μ may be supplied from the top of the tube coil. Furthermore, the central axis of the tube coil does not necessarily have to coincide with the central axis of the spiral, but it is preferable that both axes coincide, and the central axis of the tube coil does not necessarily have to be perpendicular, but it is perpendicular. It is desirable that there be.

(Effect of the invention) According to the invention, the tube has a small diameter (for example, the outer diameter of the tube is +2
The optical fiber can be inserted into a long tube (for example, tube length of 1 km or more) without deterioration or damage. Furthermore, since the insertion method is simple, it is possible to reduce the cost of the optical fiber covered with the tube.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an example of a device for inserting an optical fiber according to the present invention, FIG. 2 is a plan view of a vibration table of the device, and FIG. 3 is a front view showing an example of a bobbin attached to the vibration table. 4 is a cross-sectional view showing an example of a vibration-proof guide provided in the above device, FIG. 5 is a cross-sectional view showing an example of a scratch-proof guide provided in the above device, and FIG. 6 is a cross-sectional view showing an example of an anti-scratch guide provided in the above device. 7(a) and 7(b) are diagrams each showing the vibration state of the coil. DESCRIPTION OF SYMBOLS 1... Tube, 5... Tube coil, 7... Optical fiber, 11... Frame, 14... Vibration table, 21.2
2... Vibration motor, 27-... Bobbin, 33-... Optical fiber supply device, 38... Drive motor, 43...
Holding guide, 47--speed difference detection device, 52--control device. Applicant's agent Patent attorney Tomoyuki Yabuki (and 1 other person) Figure 7, Ichiyoshi's letter regarding the Maharuma procedure (self-motivated) April 18, 1988

Claims (1)

[Claims] coiling the tube to form a coil of tube; pre-inserting the optical fiber into the tube from one end to a length that provides a sufficient conveying force to draw the optical fiber into the tube; and 1. A method for inserting an optical fiber into a tube, the method comprising vibrating a coil of the tube so as to reciprocate along a spiral path from any point in the tube while supplying the optical fiber.