JPS63187208A - Tube containing wire body - Google Patents

Abstract

PURPOSE:To prevent a wire body from being cut owing to the local heating of a tube and tensile force by inserting the wire body which is longer than the tube in a uniform temperature state and has extra length distributed uniformly in the longitudinal direction of the tube into the tube while leaving a gap. CONSTITUTION:A bobbin 27 is wound with the tube 1 in a coil shape to form a coil 5 and the bobbin 27 is fixed on a vibration table 14. Then an optical fiber 7 is drawn out of a supplying spool 34 and the tip part of the optical fiber 7 is inserted into a tube entrance part from a flaw-preventive guide 61 through a holding guide 43, an optical fiber feed state detector 47, and a vibration-proof guide 54. The optical fiber 7 is intruded into the tube by a hand first. Then the vibration table 14 is vibrated by vibration motors 21 and 22. The vibrations are transmitted to the optical fiber 7 through the coil 5, the optical fiber 7 enters the tube 1 continuously, and its extra length is distribution uniformly in the tube longitudinal direction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a linear body tube in which a linear body is inserted with a gap.

The linear body in this invention refers to a flexible linear body such as an optical fiber or an electric wire. Optical fibers include fiber wire consisting of a core and cladding layer, fiber wire coated with synthetic resin, metal, ceramic, etc., and these f! lLj+', 6"+φ, Me,
$A', n4 n7) to 7) n 1131 or now t2
Electric wires include bare wires such as copper wires, aluminum wires, and galvanized iron wires, as well as insulated wires such as enamelled wires and vinyl insulated wires. In addition, pipe refers to steel, aluminum and other metal pipes, and plastic pipes and other non-metallic pipes.

(Prior art) Linear bodies such as optical fibers and electric wires that are extended over the air, under the sea, underground, etc. are coated with metal tubes to prevent excessive tension or to provide environmental resistance. Sometimes used. For example, optical communication cables, which have become widely used in recent years, have weak optical fibers, so
There is an increasing demand for fiber cords coated with metal tubes.

By the way, if there is a large difference between the mechanical properties and thermal properties of the cladding tube and those of the linear body, various problems may occur. For example, when an optical fiber cord in which an optical fiber is coated with a metal tube is heated, excessive tension may be applied to the optical fiber due to the difference in coefficient of thermal expansion between the metal tube and the optical fiber. For this reason, there is a problem that the transmission characteristics of the optical fiber deteriorate or, if the optical fiber has minute racks, the optical fiber breaks from there. Additionally, when extending an optical fiber cord under tension, excessive tension may be applied to the optical fiber.
Problems such as the deterioration of transmission characteristics as described above arise.

Therefore, conventionally, the optical fiber is made longer than the tube to some extent while the tube containing the linear body is kept at a uniform temperature over its entire length. Hereinafter, this extra length will be referred to as extra length. in general,
The size of the total length is determined based on the temperature at which the linear body tube is manufactured (at the time of manufacture, the linear body tube is at a substantially uniform temperature). For example, if the temperature during use of the linear tube is higher than that during manufacture, increase the extra length.
On the other hand, when it is low, make it smaller. During manufacturing, the linear body is meandered or undulated within the tube to form extra length.

Regarding the extra length of such a linear tube, for example, ``Temperature Compensation Method for Optical Fiber Cable'' disclosed in JP-A-57-130002, or JP-A-59-19151,
“Method for manufacturing a metal tube containing a linear body with extra length” disclosed in 7.
It has been known. The former method feeds the optical fiber a little faster than the speed at which it is extruded into the sheath during manufacturing. Furthermore, in the latter method, the optical fiber is fed at a speed faster than the moving speed of the metal hoop and with a constant pushing force.

(Problems to be Solved by the Invention) However, the present inventors have found that the conventional linear tube having an extra length has the following problems.

In other words, although the absolute value of the total length is a necessary quality factor for pipes containing linear bodies, it is rather the variation in the extra length in unit length that is a more necessary and sufficient quality factor. In other words, if there is a locally small portion of excess length, the effect of that small excess length is only for temperature compensation or tension protection. When used in actual use, it is necessary to take into account that parts with locally small extra length may be exposed to harsh environments in terms of temperature and tension, resulting in stable and high quality reliability. It cannot be said that it is a tube that contains a high linear body.

In addition, long linear tubes may be manufactured, and depending on demand, the long linear tubes may be cut into short lengths and then supplied. In such a case, if the extra length varies, products with small extra length or no extra length will be provided.

The above-mentioned JP-A-57-130002 and JP-A-59-. 191
In the manufacturing method shown in No. 517, although it is possible to obtain the overall extra length, it is difficult to obtain uniformity.

The reason is that the movement of the tube and optical fiber must always be balanced.
1. This is because it is difficult to implement a constant ratio with a slight difference of H or less due to the material and mechanical structure of the tube and optical fiber.

Therefore, the actual method would be to detect changes in the hoop speed, tune the optical fiber's moving speed at a constant ratio, always set it faster than the hoop speed, and then intermittently change the tuning ratio. You don't get it. As a result, it is difficult to provide uniformity to the extra length per unit length in order to absorb detection errors.6 Therefore, the present invention provides a linear tube with a uniform overall length distribution in the longitudinal direction of the tube. This is what I am trying to do.

(Means for Solving the Problems) The linear body-entering tube of the present invention has a linear body that is longer than the length of the tube when the linear body-entering tube is at a uniform temperature over its entire length, and the extra length of the linear body is longer than the length of the tube. The length, ie the total length, is substantially uniformly distributed along the length of the tube.

The uniformity of the extra length distribution in the longitudinal direction of the tube is determined by the coefficient of variation of the ratio between the tube weight and the linear weight for consecutive lO divided samples of any length at any position in the tube entering the linear body. It can be displayed by

(Function) Since the extra length of the linear tube is uniformly distributed, even if the linear tube is heated locally or tension is applied locally, there will be no meandering or undulations in that part. The stored extra length extends to absorb the tension applied to the linear body. Furthermore, no matter which part of the long linear body tube is cut, the cut part has the required overall length.

(Example) Hereinafter, an optical fiber cord in which an optical fiber is inserted into a metal tube will be used as an example, and its manufacturing apparatus, manufacturing method, product example, and characteristics 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 a vibration 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 vibration 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. Also,
The vibration motors 21 and 22 are oriented such that their rotational 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 dimple plane. 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 I4 is attached to the pedestal 11 via the support spring 18 as described above, the vibration table 14
The vibrations are not transmitted to the pedestal 11.

The bobbin 27 is fixed on the vibration table 14 such that the bobbin axis coincides with the center axis C of the vibration table 14. 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. The diameter of the tube coil 5 is set to avoid applying excessive bending stress to the optical fiber.
It is desirable that the length is 150 mm or more. In this embodiment, the optical fiber 7 is an optical fiber 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 Figure 3,
The bobbin 27 has a groove 30 formed by shaper processing in the circumferential direction of the body 28 so that the unevenness continues in the bobbin axial direction, and the tube 1 is brought into close contact with the groove 30. tube 1
In this way, when closely fitting into the groove 30 of the body of the bobbin 27,
The vibration of the bobbin 27 can be accurately transmitted to the tube 1, and the vibration insertion of the optical fiber 7 can be performed 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 payout position of the supply spool 34. The holding guide 43 holds the optical fiber 7 paid 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
It 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 power source 3 of the drive motor 38 based on the signal from the detection device 47.
9 voltage is controlled. That is, the rotational speed of the drive motor 38, that is, the rotational speed of the optical fiber 7, depends on the height position at which the optical fiber 7 blocks the optical fiber height position detector 49 from the light source.
control the feeding speed. In this way, the supply spool 34
By driving and rotating the supply spool 34 and changing or stopping the rotation speed of the supply spool 34 depending on the transfer state of the optical fiber 7 inside the tube 1, the optical fiber 7 can always be supplied within the required supply speed range. Can be done. In other words,
The optical fiber 7 is not too stretched or too slack,
It can be maintained in the best condition (slightly sagging condition as shown in FIG. 1). 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, when inserting an optical fiber with a diameter of 0.4 mm into a steel pipe with an inner diameter of 0.5 mm, the force applied to the optical fiber toward the optical fiber supply side is 20 gf.
If this is the case, the optical fiber will not enter the pipe.

A vibration isolation guide 54 is installed between the optical fiber feeding state detection device 47 and the pipe entrance end 2. This anti-vibration guide 54
As a result, vibrations outside the end of the tube 1 are suppressed, 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.

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 falls 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.

A separately manufactured damage-proofing guide 61 is fixed to the artificial end of the tube 1. The scratch-proof guide 61 is made of a material with a small coefficient of friction, such as plastic, and includes a tapered guide portion 62 that expands outward with a curved surface. Since this scratch-proof guide 61 has the structure described above,
The optical fiber 7 is easily inserted into the tube 1, and at the same time, after insertion, the optical fiber 7 is reliably and smoothly transferred within the tube 1 without causing any damage.

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 shape around the bobbin 27 to form the coil 5, and the optical fiber 7, which is a pre-coated fiber wire, is also wound around the supply spool 34. Next, the bobbin 27 around which the tube 1 is wound is fixed on the vibration table 14 so that the coil axis and the central axis C of the vibration table 14 coincide. Then, the optical fiber 7 is pulled out from the supply spool 34, and the tip of the optical fiber 7 is inserted into the pipe entrance from the anti-scratch guide 61 via the holding guide 43, the optical fiber feeding state detection device 47, and the anti-vibration guide 54. do. The tube inlet @2 is located at the lowest end of the tube coil 5, such that the optical fiber 7 is inserted into the tube 1 along a substantially tangential direction of the tube coil 5.

The optical fiber 7 is initially placed in a coiled tube with 5 to 15 fibers.
Pushed 0m. 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, 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.

Insertion becomes easier if the optical fiber is inserted while applying vibration to the tube during initial insertion. 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, and the clearance is 0.1
It is desirable that the thickness is not less than mm. Furthermore, for the same reason, it is desirable that the diameter of the tube coil is at least 150 mm, preferably at least 300 mm.

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 bobbin 27, and the tube coil 5 in sequence.

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. 4, the bottom surface of the inner wall of the tube is vibrating at vibration (2) with O as the center. The vibration angle is θ, and the maximum acceleration is n times the acceleration of gravity g (n sin 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 tube becomes downward equal to g, that is, the separation line u
It leaves and is released at the departure point P, above 1. 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. That is, a lifting force as high as that at the contact point a cannot be obtained by the vibration V, and the separation line 2. After being released at the top, it receives a downward force generated as the contact point a moves. As a result, the vehicle lands on the landing line It2 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 separation line 2. 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 state is that the landing line 21 during the rise of each vibration coincides with the departure line 1□,
This is a state in which the optical fiber starts flying as soon 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. Pipe inlet end 2. Coiled pipe! , the tube outlet end 3 in this order due to the vibration of the coil 5, and is inserted through the entire coil 5 after a predetermined time.

During the insertion of the optical fiber 7, if a fluctuation occurs in the insertion speed into the tube due to factors such as burrs, 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 feeding state of the optical fiber 7 at the position of the optical fiber height position detector 49. It is immediately detected by the detector 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. In addition, the optical fiber 7
If excessive slack 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.

In the optical fiber insertion method described above, instead of applying a pushing force to the optical fiber from the lower end, the entire tube is vibrated to apply a forward force to the optical fiber inside the tube by the inner wall surface of the tube. Therefore, a uniform advancing force acts on each part of the optical fiber within the tube, and the remaining length of the optical fiber is uniformly distributed in the longitudinal direction of the tube.

Further, in the optical fiber cord obtained by the above-mentioned optical fiber insertion method, the optical fiber is undulated within the tube, and a certain amount of extra length is formed. However, to obtain an even larger extra length, do the following:

FIG. 5(a) shows the front end of the tube 1 through 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, and the tip of the tube and the tip of the optical fiber are aligned as shown in FIG. 5(b).

Then, as shown in FIG. 5(C), a cap 10 is placed on the tip of the tube 1, and the entire tube is further vibrated. The vibration imparts a transport force to the optical fiber, but the advancement of the optical fiber is blocked by the cap. As a result, the pitch of the undulations of the optical fiber 7 becomes smaller and the extra length becomes larger. The vibration time depends on the amount of extra length required. FIG. 5(d) shows the state in which the above work has been completed and the remaining length has increased.

Here, a method for evaluating the uniformity of the extra length will be explained.

Now, weight of 1 cm optical fiber a (gr) arbitrary cut tube length u, (cm) arbitrary cut tube weight W, (g) arbitrary cut optical fiber length 12 (cm) arbitrary cut optical fiber weight'
J Wr(g) Density of tube
ρam (gr/cm3) Outer diameter of tube
D, (mm) Tube wall thickness t
(mm), W, = π1. ρ, (Dmt-t2)XIO-2(g)
W,=,Q2 a'
(g). Also, when we say , we get .

Therefore, the coefficient of variation (standard deviation/average value
100Q;) and that of k match. In other words, evaluating the uniformity of the entire length is directly connected to investigating the coefficient of variation of k. ρ,,D,,t,a can be treated as a constant if one or an average representative of the divided samples is considered sufficient, but if there is a large variation, it should be determined for each divided sample. It is.

For example, in the case of an optical fiber cord in which the optical fiber is inserted into a metal tube, the coefficient of variation is 0.13 in 10 divided samples! J
The following is desirable.

(Product example) Insertion of optical fiber An optical fiber was inserted into a steel pipe under the following conditions using the apparatus shown in Fig. 1. In addition, in order to compare the uniformity of the extra length, the insertion conditions were changed slightly and the uniformity of the extra length was measured.

(1) Test material steel pipe coil: outer diameter (inner diameter) is 1.0 mmφ (0.8+
n+nφ), a steel pipe with a length of 1000m and a winding barrel diameter of 1200m.
Steel tube coil wound in line on a mm steel bobbin.

Optical Fiber An optical fiber with a diameter of 0.4 mm that is made of a double silica glass optical fiber (diameter 125 um) coated with silicone resin.

(2) Vibration conditions: Vibration angle of coil relative to horizontal plane 30
Vertical component of total amplitude 1.25 mm (3) Insertion result: Initial insertion length 50 tn Transfer speed
2 m/min Insertion time 500 min Extra length 4 m II Measurement of uniformity of extra length The measurement results are shown in Table 1.

In addition, in Table 1, the weight a of 1 cm of optical fiber is 1
．． 573x 10-3gr, density ρ1 of metal tube is 7.9
10gr/crn3, outer diameter D1 of metal tube is 0.9981
mm, and the wall thickness t of the metal tube is 0.1010 mm.

Measurement sample work and ■ are conventional methods
1519) through which an optical fiber is inserted.

The measurement sample (■) was obtained using the above-mentioned test material and vibration conditions. Divide the 1,000 m optical fiber cord into sample sections A to E every 200 m, and measure the length at any position in each sample section A to H. A 10 m sample was cut approximately every 1 m.

Measurement sample (2) was made of the same material as measurement sample (2), with a vibration angle of 15°, and an optical fiber was inserted under the same vibration conditions as measurement sample (2).

Measurement sample V is the same sample as measurement sample ■, and with the forward movement of the tip of the optical fiber inserted into the tube being suppressed by the method shown in FIG.
The extra length is added by excitation for 0 win.

The measurement sample (■) was the same as the measurement sample, and was further heated for 30 minutes under the same vibration conditions as the measurement sample (■), with the tip of the optical fiber inserted into the tube restrained from advancing in the manner shown in Figure 5.
The extra length is added by vibrating for min.

The following is clear from Table 1 above.

Comparing the measurement sample work and ■ (conventional example) with the measurement sample ■, the average value of k has increased compared to the conventional example, which indicates that the absolute surplus length has increased, ■ The fact that the standard deviation has decreased compared to the conventional example means that
Exactly the same ρIa + D@+ t, a means that the variation in extra length is small, but ρffi + D m
*If even one of t and a fluctuates, it is meaningless.■ Compared to the conventional example, the coefficient of variation is small, which means that different ρ, ,D,
, t, and a can also be compared for the extra length magnification, which clearly shows that the extra length variation is small and the uniformity is excellent.

From the measurement sample ■, ■ Increasing the vibration angle from 30° to 15° will increase the fiber conveying force in the loading direction, giving extra length with stronger pushing stress. ■ Measurement sample Compared to ■, the average value and coefficient of variation coefficient are reduced. In other words, it is clear that as the absolute surplus length becomes larger, the uniformity of the surplus length also becomes better. Note that various other means can be used to increase the fiber conveyance force in the insertion direction by changing the vibration conditions.

Furthermore, from the measurement sample V, it is clear that when the optical fiber is fixed at the tip of the tube and further subjected to vibration, the absolute total length increases and the variation becomes extremely small.

Furthermore, from the measurement sample ■, the absolute total length of the conventional product increased due to the final vibration application, and the loose arrows became deaf small male 7
J-A (110 Y'n-75 FUS) Measurement of Transmission Loss Transmission loss was measured for the above measurement sample (conventional example) and measurement sample (C) at different temperatures.

The results are shown in FIG.

As is clear from Figure 6, even though the average value of K of the conventional example is equal to that of C of measurement sample ■, that is, despite the fact that the absolute surplus length is the same, the transmission loss changes with respect to temperature changes. has changed significantly. If 20℃ is used as a reference point, the loss will decrease once at the low temperature side of 0℃, but at -20℃
It increases at ~-40°C. Microscopically, it is thought that compressive stress occurs in some parts and tensile stress occurs in others, but as a whole, compressive stress caused by the difference between the contraction of the metal tube and the contraction of the optical fiber acts on the optical fiber. It shows that On the high temperature side, on the contrary, tensile stress occurs,
Losses are increasing. On the other hand, the optical fiber cord according to the present invention (measurement sample (C)) had almost no transmission loss.

This invention is not limited to the above embodiments.

The supply of optical fibers into the pipe is not limited to just one, but can also include a plurality of optical fibers depending on the inner diameter of the pipe and the diameter of the optical fibers. In the above explanation, we have explained that the optical fiber is pre-coated as a bare wire and the pipe through which the optical fiber is inserted is a steel pipe, but of course, this 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.

When adding extra length, instead of capping the tip of the optical fiber, other fixing means such as tying the tip to the tip of the tube or bonding it with adhesive may be used.

In addition, if the optical fibers are elastically fixed to the tube with a foam material or the like at intervals in the longitudinal direction of the tube, the insertion state of the optical fibers in the tube will not be disturbed due to irregular vibrations during transportation, and the remaining length will be reduced. A uniformly distributed state can be maintained at all times.

(Effects of the Invention) According to the present invention, since the extra length of the tube entering the linear body is uniformly distributed, even if the tube entering the linear body is locally heated or tension is applied locally. , the extra length force stored in that part as a meander or undulation extends to absorb the tension applied to the linear body. Further, no matter which part of the long linear body tube is cut, the cut part has a required extra length. Therefore, the linear body will not be cut due to excessive tension. Moreover, when the linear body is an optical fiber, almost no transmission loss occurs even if the temperature changes.

[Brief explanation of the drawing]

Fig. 1 is a side view showing an example of a device for inserting an optical fiber into a tube, 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. Figures 4 and 4 are drawings explaining the principle of transporting optical fibers within the pipe, and Figures 5 (a) to 5 (d).
6 is a diagram illustrating the provision of extra length, and FIG. 6 is a graph showing the results of a transmission characteristic test of an optical fiber. DESCRIPTION OF SYMBOLS 1... Tube, 5... Tube coil, 7... Optical fiber, lO... Cap, 11... Frame, 14-... Vibration table, 21° 22... Vibration motor, 27 ...
Bobbin, 33 - Optical fiber supply device, 38 - Drive motor, 43 - Holding guide, 47 - Speed difference detection device, 52 - Control device.

Claims (1)

[Claims] In a pipe with a linear body inserted into the pipe with a gap, the linear body is longer than the length of the pipe when the temperature of the pipe with the linear body is uniform over the entire length, and the extra length A tube with a linear body characterized in that the distribution is substantially uniform in the longitudinal direction of the tube.