JPH11344652A - Sz twisted multi-layered cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it easy to take units out of an intermediate part of a cable wherein the units are twisted in layers. SOLUTION: The multi-layered cable is constituted by arraying and twisting units, having coated optical fibers or electric wires for communication, in layers, and the units of the respective layers are processed by a SZ twisting wherein the twisting direction is inverted along the length and have the same inversion pitches P and P' in each layer and the same inversion positions (X, etc.), along the length in each layer. Further, the inversion is performed at the same inversion positions by layers and further in the same phase to make easier to take units of internal layers out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer cable in which a plurality of units each having an optical fiber core wire or a communication wire are arranged in a plurality of layers and twisted.

[0002]

2. Description of the Related Art A plurality of optical units accommodating optical fiber cores are arranged in grooves of a rectangular spacer having a groove having a U-shaped cross section and a continuous opening in the longitudinal direction around a central body. Arranged and twisted optical cable
No. 108 publication.

This optical cable has a cross section as shown in FIG. In order to manufacture this optical cable, first, as shown in FIG. 2 (A), a plurality of strands 11 each having a glass fiber coated with an ultraviolet-curable resin or the like are arranged in parallel and made of an ultraviolet-curable resin or the like. Batch coating 1
2 is performed to form a tape-shaped optical fiber core wire 33. By using the optical fiber core 13 as shown in FIG. 2B, an optical fiber is inserted into a groove of a spacer 14 made of plastic such as polyethylene or polybutylene terephthalate and having a U-shaped cross section having a linear groove. The optical unit 15 is obtained by stacking and storing a plurality of core wires 13.

Next, as shown in FIG. 2 (C), the optical unit 15 is aligned and twisted around a tension member in which a coating 17 of polyethylene or the like is provided around a steel stranded wire 16 and twisted from a nonwoven fabric or plastic. Tape, thread,
An appropriate holding roll 18 made of yarn or the like is applied. If the number of optical units is large, they may be twisted into two layers as shown in FIG. Then, an outer coating 19 made of polyethylene or the like is applied to the outside thereof to obtain an optical cable.

[0005] In this optical cable, the optical units are arranged in layers and twisted in one direction for each layer. Therefore, even if the outer sheath is removed at the middle part of the optical cable and only the necessary optical fiber core wire is to be taken out at the middle branch or the like, since the optical units are aligned and arranged, only the optical unit is pulled out to the optical unit. Since there is no extra length, it is difficult to take out the necessary optical fiber core wires from the optical unit unless the optical unit is cut. Furthermore, when the optical unit is twisted into two layers, it is more difficult to take out the optical fiber core from the lower layer optical unit.

[0006]

Therefore, in order to make it easy to take out the optical fiber from the optical unit, the optical unit is not twisted in one direction, but is inverted in the longitudinal direction. It is possible to do. However, since the optical unit in which a plurality of tape-shaped optical fiber cores are stacked and housed in the groove of the spacer has considerable rigidity, it cannot be twisted at a small pitch, and the inversion pitch of the SZ twist is 300 mm or more. Also.

If the optical unit has only one layer, the optical unit can be pulled out by removing the outer coating as much as 600 mm in the middle of the optical cable. However, if the optical unit is twisted in multiple layers, Even with SZ twist, it is quite difficult to take out the lower optical unit due to the rigidity of the optical unit. SUMMARY OF THE INVENTION The present invention provides an SZ-twisted multi-layer cable in which a unit having a multi-layered structure is easy to take out an inner layer unit at an intermediate portion of the cable.

[0008]

The SZ stranded multilayer cable of the present invention is a multilayer cable in which a plurality of units having an optical fiber core or a communication wire are arranged in a plurality of layers and twisted. The units are twisted by SZ twist in which the twist direction is reversed in the longitudinal direction, the reversal pitch for each layer is the same, and the reversal position for each layer is the same in the longitudinal direction. Further, by making the inversion phase of each layer the same at the same inversion position in the longitudinal direction, it is possible to further easily take out the unit of the inner layer.

[0009]

FIG. 1 is a diagram showing the situation of SZ twisting of each layer in the case of a two-layer cable which is an embodiment of the SZ twisted multilayer cable of the present invention, and FIG. FIG. 1B shows the SZ twist state of the inner layer. In FIG. 1, the helical line indicates an arbitrary one of each layer.
Shows the trajectory of the unit, X, Y, Z, X ', Y', Z '
Indicates the reversal position of the twist direction. Θ and θ ′ indicate the number of rotations of an arbitrary unit in each layer while the unit rotates in the longitudinal direction of the cable while reversing the twist direction in the longitudinal direction.

The distance between the inversion positions, that is, the distance between X and Y or the distance between Y and Z is called an inversion pitch P. The direction of the spiral from left to right is changed from right-handed to left-handed at the reversal position X, and left-handed to right-handed at the reversal position Y. Are shifted by 180 degrees. In addition, the inversion phases of X and Z are the same. The distance at which the inversion phases are the same, that is, the distance between X and Z, may be called an inversion cycle pitch.

In the multilayer cable of the present invention, the reversal pitch P of the outer layer SZ twist and the reversal pitch P ′ of the inner layer SZ twist are the same, and the reversal position of the outer layer in the longitudinal direction and the reversal position of the inner layer in the longitudinal direction are set. To be the same. In the case of FIG.
And X 'and Y and Y' are at the same position in the longitudinal direction, the reversal position is the same. Also, when X and Y 'and Y and Z' are at the same position in the longitudinal direction, the reversal position is the same. However, X and X 'have the same inverted phase, but X and Y' have the inverted phase shifted by 180 degrees.

In such an SZ twisted multilayer cable in which the reversal position and the reversal pitch are the same for each layer, if the outer coating for one cycle of reversal is removed at the middle part of the cable, the portion where the outer coating has been removed will be in the longitudinal direction. In any case, the twist of the outer layer unit is the same in the outer sheath on both sides, so it is always possible to completely untwist the outer layer unit. Can be pulled out. When the outer layer unit is pulled out, the inner layer unit is also exposed for one reversal period, so that the unit can be untwisted and pulled out of the cable like the outer layer.

[0013] Further, the external coating is formed by forming the external coating so that the twist of the internal unit appears on the surface of the external coating, or by marking the reversal position of the unit on the surface of the external coating. If the position is known, the outer coating is removed with the reversal position at the center. Then, since the reversal position comes at the center of the outer coating removal part, even if the outer coating removal part is shorter than one reversal period, it is possible to untwist and draw out not only the outer layer unit but also the inner layer unit.

In FIG. 1, X and X 'are set in the longitudinal direction.
If Y and Y 'are at the same position, the reversal position is matched between the inner and outer layers, and the reversal phase is also matched between the inner and outer layers, the return direction when untwisting at the removed portion of the outer coating is the outer layer. And the inner layer is the same, so that the twist can be easily returned even if the rigidity of the unit is large, and the inner layer can be more easily pulled out.

As described above, as the embodiment of the SZ twisted multilayer cable of the present invention, the inversion position, the inversion pitch, and the inversion phase of the SZ twist of the unit have been described with reference to FIG.
Specific examples of the unit structure and cable structure of the cable include the following. Even in the optical cable having the same cross section as the optical cable shown in FIG. 2 described in the prior art, the optical unit 15 is a unit of the SZ twisted multilayer cable of the present invention, and the inversion position, the inversion pitch, and the inversion phase are in accordance with the requirements of the invention. If selected, the SZ stranded multilayer cable of the present invention can be realized. Further, in FIG. 2, the optical fiber core is a tape-shaped optical fiber in which a plurality of strands are arranged in parallel and coated collectively.
In the stranded multilayer cable, the optical fiber core wire may be a single wire, and the unit is not limited to an optical unit using a U-shaped spacer.

Further, the SZ twisted multilayer cable of the present invention can be realized also in the communication cable shown in FIG. FIG. 3 is a cross-sectional view showing an example of a communication cable, in which reference numeral 20 denotes a covered wire obtained by coating a conductor, reference numeral 21 denotes a quad in which four covered wires 20 are twisted in a quad shape, and reference numeral 22 denotes five pieces. Is a unit formed by twisting the quads 21, 23 is an upper winding made of a plastic tape or the like, and 24 is an outer covering made of a plastic or the like. Also in this case, the unit 22
Is SZ twist, and the inversion position in the longitudinal direction is the same in the inner layer and the outer layer. Further, preferably, if the inversion phase is also matched between the inner layer and the outer layer, it becomes easier to draw out the inner layer unit.

Although the examples of FIGS. 2 and 3 each show a multilayer cable in which the unit is twisted into two layers, the unit may be twisted into three or more layers.

[0018]

According to the SZ twisted multilayer cable of the present invention, since the twist direction of the unit is SZ twist and the reversal pitch of each layer and the reversal position in the longitudinal direction are matched, the outer coating is removed at the middle part of the cable. It becomes easy to pull out the units of each layer out of the cable. In addition, if the reversal position in the longitudinal direction of each layer is matched and the reversal phase is also matched, it is easier to draw the inner layer unit out of the cable, and even if the rigidity of the unit is slightly high, the unit can be connected to the cable. Can be taken out.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view showing a situation of SZ twist in an embodiment of an SZ twisted multilayer cable of the present invention, wherein (A) shows the situation of SZ twist of an outer layer, and (B) shows the situation of SZ twist of an inner layer. FIG.

FIG. 2A is a cross-sectional view of a tape-shaped optical fiber cable,
(B) is a perspective view of the optical unit, and (C) is a transverse sectional view of the optical cable.

FIG. 3 is a cross-sectional view of a communication cable.

[Explanation of symbols]

 X, Y, Z, X ', Y', Z ': Inversion position P, P': Inversion pitch θ, θ ': Inversion angle 15: Optical unit 22: Unit

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hideyuki Iwata 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (2)

[Claims] 1. A multi-layer cable in which a plurality of units each having an optical fiber core wire or a communication wire are arranged in a plurality of layers and twisted, wherein the units in each layer are twisted by SZ twist in which the twist direction is reversed in the longitudinal direction. SZ twisted multilayer cable characterized in that the inversion pitch of each layer is the same and the inversion position of each layer is the same in the longitudinal direction. 2. The SZ stranded multilayer cable according to claim 1, wherein the inversion phase of each layer is the same at the same inversion position in the longitudinal direction.