JPH0753044Y2 - Spacer for supporting optical fiber having spiral grooves that are alternately inverted - Google Patents

Description

[Detailed Description of the Invention] << Industrial Application Field >> The present invention has a tensile strength wire in the center, a plurality of grooves for accommodating optical fibers provided on the outer periphery by a thermoplastic resin, and the grooves are alternately inverted. And a spacer for supporting an optical fiber formed in a spiral shape.

<< Prior Art and its Problems >> In order to prevent crushing and the like, an optical fiber is accommodated in a spacer having a plurality of grooves on its outer periphery and is made into a cable.

Conventionally, as this type of spacer, one having a spiral groove in one direction on the outer periphery is often used.

However, when manufacturing an optical fiber cable using a unidirectional spiral spacer, a large-scale rotating device is required to insert the optical fiber into the spacer groove, and the production speed cannot be increased too much. was there.

As a spacer that can solve these problems, a spacer having an alternating inversion groove in which the direction of the groove is alternately inverted within one rotation or less has been proposed.

If this spacer is used, the device for inserting the optical fiber as described above is not required, and the insertion speed can be improved, so that it is possible to reduce the equipment cost and the production cost, and use this spacer. The above optical fiber cable has an advantage that the optical fiber can be branched and taken out from the middle of the cable during or after installation.

FIG. 3 shows a typical spacer of this type. The spacer comprises a tensile strength line 1 arranged in the center and a main body coating layer 2 provided on the outer periphery thereof, and the outer periphery of the main body coating layer 2 is shown. Is provided with alternating U-shaped spiral grooves 3 and ribs 4, the spiral grooves 3 extending along the longitudinal direction, and
It is formed so as to be alternately inverted at a predetermined rotation angle.

As a method of manufacturing this type of spacer, when the outer periphery of the tensile strength wire 1 is extruded from a die corresponding to the cross-sectional shape of the spacer to obtain a molten thermoplastic resin, and coated,
It is known to rotate the die itself or alternately rotate the tensile strength line 1 or the product.

However, when the spacers are manufactured by these conventionally known methods, the ribs 4 that define the spiral grooves 3 are formed by viscoelasticity of the molten resin, strain at the time of cooling and solidification, or the like at the portion where the spiral direction of the spacers is reversed. For example, it is difficult to surely accommodate the optical fiber core wire or the tape in the groove 3 because the portion is inclined and has a shape as shown in FIG. 4, for example.

In order to compensate for the deformation and reduction of the groove space due to such an inclination, if the width of the rib is reduced and the groove has an inverted trapezoidal cross section as shown in FIG. 5, the bobbin is wound on the bobbin as shown in FIG. At the time of winding, the ribs enter the groove portions of the adjacent spacers to make the winding layer non-uniform, which makes it difficult to wind in an aligned manner and makes it difficult to take out during use.

Therefore, the inventors of the present invention have earnestly studied an optical fiber carrying spacer having an alternating inversion groove capable of solving the above-mentioned problems, and have completed the present invention. An object of the present invention is to provide a spacer that can solve the above-mentioned problems.

<< Means for Solving the Problems >> A tensile strength wire and a primary coating layer made of a thermoplastic resin surrounding the outer periphery thereof, and a thermoplastic resin main body coating layer provided on the outer periphery of the primary coating layer, and In an optical fiber-carrying spacer having a spiral groove extending in the longitudinal direction on the outer periphery of the main body coating layer and alternately inverting, a bottom portion of the spiral groove has a cross-section that is substantially concentric with the primary coating layer. Arcuate,
Alternatively, the ribs are formed in a substantially linear shape, the width of the upper end of the rib defining the spiral groove is made wider than the width of the groove opening, and the side wall of the spiral groove is formed in a concave shape. Is characterized by.

The tensile strength wire that can be used in the present invention is a steel wire, a copper wire or other metal wire, a single wire or a stranded wire of a reinforced plastic wire containing long fiber reinforcing fibers, and the outer circumference of these wires is made of a thermoplastic resin. A thermoplastic resin having a primary coating layer, capable of adhering to the outer periphery of the tensile strength wire, and having compatibility with the thermoplastic resin coated on the outer periphery of the primary resin layer is selected and used.

Note that the adhesion here is not limited to chemical adhesion and may be anchor-effective adhesion.

Therefore, when the twisted wire is used, it is not always necessary to use the adhesive resin.

While making the outer diameter of the primary coating layer and the outer diameter of the bottom of the spiral groove as close as possible, the groove bottom portion is formed in a substantially arc shape whose cross section is concentric with the primary coating layer, or in a substantially straight line shape,
It is preferable that the ribs rise from the bottom of the groove to rise as rapidly as possible so that the arc surface or the flat surface is made as long as possible.

Further, the width of the upper end of the rib defining the spiral groove is made wider than the width of the groove opening, and the side wall of the spiral groove is formed in a concave shape to widen the groove space as much as possible. It is preferable in terms of storage capacity.

<Operation> In the spacer of the present invention, the groove bottom has a substantially arcuate shape or a substantially linear cross section concentric with the primary coating layer, and has a thin wall thickness between the primary coating layer and the groove bottom of the spacer body coating layer. Since the part is made as long as possible, the primary coating tensile strength wire is inserted into the crosshead die, and the resin for the molten spacer body is extruded through this to coat the outer periphery of the primary coating layer, and then the groove bottom First, it solidifies by cooling, and both bases for standing the ribs are cooled and fixed, and then the ribs solidify by cooling.Therefore, the main body resin on the groove bottom side does not pull in the unsolidified portion of the ribs. The degree to which the rib portion is inclined is improved.

Further, since the width of the upper end of the rib defining the spiral groove is wider than the width of the groove opening, the rib is prevented from entering the groove when wound on the bobbin.

Furthermore, since the side wall of the spiral groove is formed so as to be raised in a concave shape, the degree of inclination of the rib portion is improved, which makes it easier to store the optical fiber. It is possible to achieve both the effect and the effect of preventing it from falling into the groove.

<< Examples >> The present invention will be described below with reference to Examples.

Example 1. A steel stranded wire 10 in which seven single steel wires having an outer diameter of 1.0 are twisted together is passed through an acetone bath to be degreased, preheated to 80 ° C., and inserted into a crosshead die for primary coating. An outer diameter of 6.15 mm was covered with high-density polyethylene (MI = 0.1), which was subsequently passed through a heated shaping die to shape the outer diameter to 6.0 ± 2/100 mm.

Thereafter, the shaped primary coating tensile strength wire 12 is passed through a spacer body coating die to rotate a die having a shape corresponding to the shape of the product and has a cross-sectional shape as shown in FIG. The groove 13 has a groove 13 of
6.25 mm, the outer diameter of the rib 15 is 11.5 mm, the width of the upper end 16 of the rib 15 is 3.0 mm, the width of the groove opening 17 is 2.8 mm, the length of the arc portion of the bottom of the groove 13 is 1.8 mm. The groove side wall 18 is formed in a concave shape with about 4R, and the spiral direction is alternately inverted rightward (hereinafter referred to as S) and leftward (Z) at a rotation angle of 360 °, and the inversion pitch is 250.
mm, the spacer with a repeat pitch of 500 mm was obtained.

The obtained spacer had a good shape with a very small inclination of the rib 15 as compared with the conventional spacer, and had no trouble at the time of winding the drum.

In this example, the ratio D0 / D1 = 6.0 / 6.25 = 0.96 between the outer diameter D0 of the primary coating and the outer diameter D1 of the groove bottom is the same, but this ratio is the same in the range 0.90 <D0 / D1 <1. It was confirmed that the effect of was obtained.

Example 2 The same shaped primary coating tensile strength wire 12 as in Example 1 was coated with a spacer body, and the groove bottom portion 14 had a flat surface as compared with Example 1, and a spacer having an assumed outer diameter of 6.25 mm. Got Also in this spacer, ribs at the SZ inversion portion
The inclination of 15 was smaller than the conventional product and was a satisfactory shape.

Comparative Example 1. Using the same shaped primary coated tensile strength wire as in the above example, the bottom diameter of the U-shaped groove 3 as shown in FIG. 3 is 6.25 mm, the width of the U-shaped groove 3 is 2.4 mm, and the rib 4 is When a spacer was manufactured in the same manner as in the example, aiming at a U-shaped groove spacer having an outer diameter of 11.5 mm, the reversal portion had a cross-sectional shape as shown in FIG. 4 and could not be put to practical use.

<Effect> Since the spacer for supporting an optical fiber having the spiral groove which is alternately inverted of the present invention has a very small inclination of the rib at the inversion portion, which has been a problem in the past, the optical fiber core wire or the like can be provided over the entire length of the spacer. It is a very useful spacer that can surely be protected and supported over the entire length, and that troubles in winding the spacer in the manufacturing process of the spacer can be avoided.

[Brief description of drawings]

1 and 2 are views showing a cross-sectional shape of a spacer according to an embodiment of the present invention, FIG. 3 is a cross-sectional view of a conventional U-shaped spacer, and FIG. 4 is a description of a defect of the conventional spacer. FIG. 5 is a sectional view showing another example of a conventional spacer, and FIG. 6 is an explanatory diagram showing a defect of the spacer. 10 …… tensile strength wire, 12 …… primary coating tensile strength wire 14 …… groove bottom, 15 …… rib upper end 16 …… groove opening, 17 …… groove side wall

Claims (1)

[Scope of utility model registration request] 1. A primary coating layer made of a thermoplastic resin surrounding a tensile strength wire and an outer periphery thereof, and a main body coating layer made of a thermoplastic resin provided on the outer periphery of the primary coating layer. In an optical fiber-carrying spacer provided with spiral grooves that extend in the longitudinal direction on the outer periphery and that are alternately inverted, the bottom of the spiral groove has a cross section of a substantially arc shape concentric with the primary coating layer, or a substantially circular shape. In addition to being formed in a straight line, the width of the upper end of the rib defining the spiral groove is wider than the width of the groove opening, and the side wall of the spiral groove is formed in a concave shape. An optical fiber carrying spacer having spiral grooves that are alternately inverted.