JPH06331867A - Optical cable provided with at least one light-wave conductor band and its manufacture - Google Patents

Abstract

PURPOSE: To provide a means for reducing the mechanical load of optical waveguides included in an optical waveguide band. CONSTITUTION: The optical waveguide band LB1 has many optical waveguides LW1 to LM12 coated with a common coating body UH. The band LB1 is arranged along a twisted route in a cable. Mechanical preliminary stress components PP1 to PP12 are applied at least to a part of the optical waveguides LW1 to LW12 and the direction of the stress components PP1 to PP12 is reversed to the direction of load components SPI to SP12 generated due to guide along the route.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical cable having at least one lightwave conductor band, the lightwave conductor band having a large number of lightwave conductors covered by a common coating, And of the type arranged along a trajectory that causes twisting.

[0002]

2. Description of the Prior Art In the optical cable described in GB 2122767, a bundle of lightwave conductor bands is provided. Each lightwave conductor band has a certain number of
For example, it has four light wave conductors arranged in a line. When such a bundle of lightwave conductor bands is guided along a curved orbit, for example, in a spiraling process for manufacturing an optical cable, the guide type along the orbit and the number of lightwave conductors in the lightwave conductor band are determined. Correspondingly, mechanical loads of different magnitudes occur. In order to at least partly remove these loads, in known optical cables the light guide inside the light guide band is guided through a hollow chamber with a corresponding overlength and tensile forces are applied on both outsides of the light guide band. The parts are extruded together into a common sheath. Since the tensile member must additionally be placed in the light guide band, the light guide band as a whole is wider and the manufacturing process is correspondingly complicated.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the mechanical load on the lightwave conductor inside the lightwave conductor band.
To provide one means.

[0004]

In order to solve this problem, in the arrangement according to the invention, in an optical cable of the type mentioned at the beginning, at least part of the lightwave conductor in a common sheath is subject to mechanical prestress. This mechanical prestress is made to act in the direction opposite to the load generated by the guide along the track.

[0005]

According to the present invention, therefore, a mechanical prestress is applied to the lightwave conductor when the lightwave conductor band is already manufactured. This can be done relatively easily. Because only when installing the cover,
This is because it is sufficient to load each light wave conductor with a desired mechanical prestress. During subsequent processing of the lightwave conductor band, forces are also generated, for example during the helical winding process. According to the invention, this force acts in the opposite direction to the prestressing of the lightwave conductors, at least partially canceling out the mechanical prestressing of the individual lightwave conductors. In the finished optical cable, the light guide has little or no mechanical prestress. Therefore, the increase in transmission loss due to this mechanical prestress need not be feared as much as, for example, when an unpretreated lightwave conductor band is inserted into the cable core or otherwise processed as in the present invention.

Another advantage of using such a prestressed lightwave conductor in a lightwave conductor band is that the lightwave conductor band as a whole in the finished optical cable has a significantly lower mechanical prestress. That is not to have. Because guiding along a curved trajectory at least partially cancels the internal forces. The lightwave conductor band, in which the lightwave conductors are coated without prestressing with a common coating, has a significant elastic load by being guided along a curved trajectory that causes twisting, and thus Repeatedly
While prone to tilting, the lightwave conductor band constructed in accordance with the present invention generally experiences little mechanical force, and therefore has little tendency to tilt or tip. Such tilting or tipping usually results in transmission losses, especially when the lightwave conductor band strikes the sidewalls and other parts. This is because this lightwave conductor band range is particularly susceptible to micro bending deformation. In addition, sustained loading is known to reduce the service life of fibrous members.

Further, the present invention relates to a method for producing a lightwave conductor band by coating a large number of lightwave conductors with a common covering body. According to a feature of the present invention, the lightwave conductor is attached when the common covering body is attached. At least a part of it is mechanically prestressed and the covering is fixedly attached to the lightwave conductor so that the mechanical prestress is at least partially maintained and the direction of the prestress is That is, it is selected so that the direction of the load generated when the lightwave conductor band is subsequently processed is opposite to the direction of the load.

The present invention also relates to a lightwave conductor band having a large number of lightwave conductors contained in a common sheath, which is characterized by the fact that the lightwave conductor is loaded under prestress. The optical waveguides on both outer sides have compressive prestress, and the optical waveguides located inside or at the center have tensile prestress.

Advantageous embodiments of the invention are described in claims 2-4.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be specifically described below based on the embodiments shown in the drawings.

In FIG. 1, a cylindrical support CE1 is provided, which has a spiral radius r. A light wave conductor band LB1 is wound on the support CE1 along a spiral winding orbit, and the light wave conductor band LB1 has twelve light wave conductors LW1 to LW12. These light wave conductors LW1 to LW12 are arranged side by side in a line, and are covered with a common cover UH. The spiral pitch of the lightwave conductor band LB1 attached in this way is indicated by the symbol s.

In FIG. 2, the degree of expansion d of the individual lightwave conductors LW1 to LW12 in the arrangement of FIG. 1 is shown in%.
A solid curve K500 indicates the extension degree d that occurs when the spiral pitch s of the lightwave conductor band LB1 is 500 mm.
The curve K200 shows the degree of elongation of the individual lightwave conductors LW1 to LW12 that occurs when the helical pitch s = 200 mm. In both cases, the coiling radius r = 7.6 mm
Is. The width of the lightwave conductor band LB1 is 3.2 mm.

The relationship between the spiral winding pitch s expressed in mm and the spiral winding angle Φ / m is shown in FIG. As can be seen from this, when the spiral pitch s = 0 mm and s = ∞, the spiral angle Φ / m is 0, while when the spiral pitch s≈50 mm, the spiral angle Φ /
m is the maximum. In the usual spiral pitch s in the range of approximately 100 mm to 500 mm, a considerably large spiral angle Φ / m occurs, and therefore the light wave conductors LW1 to LW
The load on W12 will also be considerable.

As can be seen from the course of the curve K500 in FIG. 2, when the orbit is a spiral line shape as shown in FIG. 1, the light wave conductors LW1, LW2 and LW11, LW1,
LW12 is extended and the inner lightwave conductors LW4 to LW
W9 is compressed. The lightwave conductors LW3 and LW10 are practically unloaded. Pulling loads SP1 and SP12 are shown in the form of arrows on the lightwave conductors LW1 and LW2 on both outer sides of the lightwave conductor band LB1. Compressive loads SP4 and SP9 are shown in the form of arrows on the lightwave conductors LW4 and LW9.

Choosing a helical pitch s = 200 mm results in curve K200. In this case, the degree of extension d becomes extremely large, and therefore the light wave conductors LW1 and LW on both outer sides are formed.
2 and LW11, Lw12 exert a remarkably large tensile force, and accordingly, the degree of compression also remarkably increases, and a remarkably large compression force acts on the inner light wave conductors LW4 to LW9. This is because, as shown in FIG. 3, the spiral winding angle Φ / m when the spiral winding pitch s = 200 mm is equal to the spiral winding angle Φ when the spiral winding pitch s = 500 mm.
This is because it is significantly larger than / m.

The elongation d and the mechanical load increase as the number of lightwave conductors LW arranged inside the lightwave conductor band LB1 increases. This is because the lateral dimension (width) of the lightwave conductor LB1 increases and the mechanical load of the lightwave conductor LW also increases.

The lightwave conductor L inside the lightwave conductor band LB1
In order to cope with such an unfavorable mechanical loading of W, according to the invention, the lightwave conductors LW1 to LW1
Secondly, before the deformation along the trajectory shown in FIG. 1, a prestress PP is applied in the direction opposite to the load generated by guiding along the spiral winding trajectory that causes the twist. To clarify this, in FIG. 1, the tensile loads SP1 and SP12 are shown in the form of arrows on the lightwave conductors LW1 and LW12.
The compression loads SP4 and SP9 are shown in the form of arrows for the lightwave conductors LW4 and LW9.

When the compressive prestress PP1 indicated by the arrow in FIGS. 1 and 2 is applied to the light wave conductor LW1 in advance, the tensile load SP1 generated by the curved orbital shape is reversed in the compressive prestress PP1. Are canceled out completely or at least partly, so that the residual load of the lightwave conductor LW1 is significantly reduced or, in extreme cases, practically zero. The same applies to the light waveguide LW12, in which the compressive prestress PP12 completely or partly cancels the tensile load SP12 caused by the curved track shape.

In the light wave conductors LW4 and LW9, compressive loads SP4 and SP9 are generated by guiding the light wave conductor band LB1 along a curved orbit, and the tensile prestresses PP4 and PP9 are applied in advance. Can be completely or partially offset by.

In short, the basic technical idea for canceling the load exerted on the lightwave conductor LW in the lightwave conductor band LW by the curved orbital shape lies in the following points. That is, the prestress PP in the opposite direction to the load SP is applied to the individual lightwave conductors LW or to some of the lightwave conductors LW, especially to the lightwave conductor LW that receives a large mechanical load SP.
In the final state (in other words, in the state where the lightwave conductor band LB is arranged in the cable core), the residual load of the lightwave conductor LW is reduced or sufficiently removed by the action of.

It is not necessary to apply the prestress PP to all the light wave conductors LW in the light wave conductor band LB. For example, in the case of a lightwave conductor band LB1 having twelve lightwave conductors LW1 to LW12, the third lightwave conductor LW3 and the tenth lightwave conductor LW10 have very little mechanical load or no mechanical load occurs. It will be located in a range that does not exist. In the case of the lightwave conductor band LB having 16 lightwave conductors LW, the lightwave conductors LW of the 3rd, 4th, 5th, and 12th, 13th, and 14th cottons receive only a very slight mechanical load. On the other hand, the light wave conductors LW on the both outer sides (first, second and fifteenth, sixteenth light wave conductors LW) and light wave conductors LW located on the inner side (towards the center) (sixth to eleventh light waves) Conductor L
W) is subject to significantly higher loads. In short, in the case of the lightwave conductor band LB having 16 lightwave conductors LW,
The mechanical prestress PP is applied to the first, second, sixth to eleventh, fifteenth, and sixteenth lightwave conductors LW, and the remaining lightwave conductors LW are not subjected to the mechanical prestress PP. There are still enough things to do. Generally speaking, a mechanical prestress PP is applied to at least both the outer and innermost (center) lightwave conductors LW to offset the loads that occur, for example, in the spiraling process. In this case, the tensile prestress PP is applied to the innermost lightwave conductor LW, and the compressive prestress PP is applied to the outermost lightwave conductors LW.

FIG. 4 shows the lightwave conductor band L shown in FIG.
A device is shown that can make B1. Individual lightwave conductors LW1-L with protective layers (coatings)
W12 is pulled out from the storage bobbins VS1 to VS12 by a pulling device and supplied to the coating device UE. Here, a covering UH is mounted, which tightly surrounds the lightwave conductors LW1 to LW12 in a stationary manner and is hardened before the winding process. The individual lightwave conductors LW1 to LW12 in the braking devices BR1 to BR12 are subjected to the different pulling forces shown in FIG. In FIG. 5, cN is set on the Y axis.
The unit tensile force PT is plotted. The shape of the curve K500 * in FIG. 5 is almost the same as the shape of the curve K500 * in FIG. That is, both outermost lightwave conductors L
W1 and LW12 receive only a slight tensile force PZ1, PZ12 of about 20 cN, whereas the central two optical wave conductors LW6 and LW7 receive a tensile force of 26 c.
N. The light wave conductors LW4 and LW9 have a tensile force PZ.
4 and PZ9. The braking devices BR1 to BR12 are adjusted to exert various tension forces, and the tension force PZ acting on the outer light wave conductor LW is smaller than the tension force PZ acting on the inner light wave conductor LW. It is supposed to be.

The attachment of the covering body UH covering all the light wave conductors LW1 to LW12 is carried out by mounting the individual light wave conductors LW1 to LW1.
It is performed so that the mutual displacement of the LWs 12 and the displacement relative to the covering UH are prevented. Lightwave conductors LW1 to L
W12 is pulled out by the pulling device, and the covering body UH
And the coating UH is cured, the light wave conductors LW1 to LW12 of the light wave conductor band LB1 are subjected to the average tensile force indicated by PR in FIG. The braking force of the braking devices BR1 to BR12 is zero line NU in FIG.
Curve K500 * which is a symmetrical curve of the curve K500 with respect to
It has been chosen such that the curve K500 * of FIG. As a result, the completed lightwave conductor band LB1
In, for example, the lightwave conductors LW1 and LW12 have P
The pulling force having the magnitude of R-PZ1 or PR-PZ12 is acting. This tensile force is the compressive prestress PP1 or PP12 shown in FIGS.

On the other hand, the tensile forces PZ4 and PZ9 acting on the light wave conductors LW4 and LW9 are larger than the average tensile force PR, and PZ4-PR or PZ9-
The prestress PP4 or PP9 corresponding to the magnitude of PR is the tensile prestress.

In the lightwave conductor band LB1 thus manufactured, at least a part of the lightwave conductor LW has a prestress P.
P, and the direction of these prestresses PP is opposite to the direction of the load caused by the twisting of the lightwave conductor band LB1 in the subsequent processing process, in particular the helical process.

Since the dimensions of the lightwave conductor band LB (the coiling pitch s, the coiling radius r, etc.) are generally determined, when the lightwave conductor band LB is already manufactured, it is curved, for example, in the cable core. It is possible to take into account future guidance-based loads of the spiral shape.

However, it is sufficient to exert an "average" prestress PP on the individual lightwave conductors LW.
This is because, in any case, the prestressing PP and the load SP based on the curved trajectory are in opposite directions, so that a canceling action occurs. Even if the prestress PP and the load SP due to the curved trajectory do not exactly cancel each other out, the lightwave conductor band LB is in its final state (ie, for example, in the finished cable core), The load SP of the light guide LW becomes smaller than that when the prestress PP is not applied. The residual load which remains in the light-wave conductor LW in some cases after offsetting is below a very slightly defined limit value. This limit value depends on the loaded lightwave conductor LW1, LW12 or LW6 and LW.
It's only a fraction of the maximum load of seven.

FIG. 6 schematically shows the structure of the optical cable OC. A tensile member (for example, a steel rope) CT6 is arranged at the center of the optical cable OC. Around the plastic layer CE6 (corresponding to the support CE1 in FIG. 1) mounted around this tensile member CT6, two closed layers are provided:
The U-shaped chamber members UC1 and UC2 are wound around.
In this case, only one U-shaped chamber member UC1 or UC2 is shown in each layer for the sake of simplicity.
In each of the U-shaped chamber members UC1 and UC2, for example, a bundle of lightwave conductor bands LB having the structure shown in FIG. 1 is arranged.
In the illustrated example, three light wave conductor bands LB1, LB2 and LB3 are combined into one light wave conductor bundle,
It is contained in a character member, for example UC2. The winding layers BW1 and B are provided on the outer peripheral surfaces of the U-shaped chamber members UC1 and UC2.
W2 is wound, and the outer peripheral surface of the cable is protected by a single-layer or multi-layer outer MA. Of course, the lightwave conductor band LB according to the present invention can be used in an optical cable having any other structure.

[Brief description of drawings]

FIG. 1 is a perspective view of a lightwave conductor band according to the present invention arranged in a spirally extending orbit.

FIG. 2 is a graph showing force distribution of the band shown in FIG.

FIG. 3 is a graph showing a relationship between a rotation angle and a spiral pitch.

FIG. 4 is a view showing an apparatus for manufacturing a lightwave conductor band according to the present invention.

5 is a graph showing force distribution of a lightwave conductor band manufactured by the manufacturing apparatus shown in FIG.

FIG. 6 is a diagram showing an optical cable formed of a lightwave conductor band according to the present invention.

[Explanation of symbols]

BR1 to BR12 braking device, BW1 and BW2 winding layer, CE1 support, CE6 plastic layer,
CT6 tensile member, d elongation, K200, K5
00 and K500 * curve, LB1 to LB3 lightwave conductor band, LW1 to LW12 lightwave conductor, MA outer sheath, NU zero wire, OC optical cable, PP
1, PP4, PP9 and PP12 prestress, PR average tensile force, PT tensile force, PZ1, PZ
4, PZ9 and PZ12 tensile force, r spiral radius, s spiral pitch, SP1, SP4, SP
9 and SP12 load, UC1 and UC2 U-shaped chamber member, UE coating device, UH coating body, VS1
VS12 storage bobbin, Φ / m spiral angle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsang Gao, Republic of Germany Coburg Remenschneiderweg 1 Ar (72) Inventor, Reiner Schneider, Germany Ebersdorf Fluerstrasse 32

Claims (6)

[Claims] 1. At least one lightwave conductor band (LB)
1) an optical cable (OC) having a lightwave conductor band (LB1) having a number of lightwave conductors (LW1 to LW12) covered by a common covering (UH), , Of the type arranged along the orbit causing twisting, a common covering (U
At least a part of the light wave conductors (LW1 to LW12) in H) is subjected to mechanical prestresses (PP1 to PP12), and these mechanical prestresses (PP1 to PP1) are applied.
2) An optical cable with at least one lightwave conductor band, characterized in that it is in the opposite direction to the loads (SP1 to SP12) produced by the guidance along the track. 2. The outer light-wave conductors (LW1, LW12) arranged in a common covering (UH) are loaded with compressive prestresses (PP1, PP12). The optical cable described in 1. 3. A lightwave conductor (LW4) located further inward or towards the center in a common covering (UH).
~ LW9) is loaded with a tensile prestress (PP4, PP9). 4. The stress distribution of the lightwave conductors (LW1 to LW12) in the lightwave conductor band (LB1) is as follows, that is, after the lightwave conductor band (LB1) is spirally wound, the lightwave conductors (LW1 to LW12) are Selected so that it has little tensile and compressive prestress, or that the residual prestress is below a critical value that is only a small fraction of the load that would otherwise result. The optical cable according to any one of claims 1 to 3, characterized in that 5. A large number of light wave conductors (LW1 to LW12) are covered with a common covering (UH) to form a light wave conductor band (L).
In the method of manufacturing B1), a common covering (UH)
At the time of mounting, at least a part of the light wave conductors (LE1 to LW12) is mechanically prestressed (PP1 to PP12).
And load the cover (UH) with the light wave conductor (LW1 to LW1).
2) fixedly attached to mechanical prestress (PP1-P1
P12) is maintained at least partially, and the direction of prestress (PP1 to PP12) is as follows, that is, the load (SP1 to SP12) generated when the lightwave conductor band (LB1) is subsequently processed. A method for manufacturing a lightwave conductor band, which is characterized in that the direction and the direction are opposite. 6. In a lightwave conductor band having a number of lightwave conductors (LW1 to LW12) contained in a common covering (UH), the lightwave conductors (LW1 to LW12) being prestressed, Lightwave conductors on both outside (LW1, LW
12) has a compressive prestress, and the lightwave conductors (LW6, LW7) located inside or at the center further have a tensile prestress, wherein