JP7207232B2 - Optical cable manufacturing method - Google Patents

Description

The present disclosure relates to a method of manufacturing an optical cable.

2. Description of the Related Art In an optical cable used for communication or the like, the outer periphery of a cable core containing an optical fiber is usually covered with a cable jacket (also referred to as a sheath) formed by, for example, extrusion molding.
When taking out the optical fiber, it is necessary to remove the cable jacket to expose the cable core. To facilitate removal of the cable jacket, a tearing member for tearing the cable jacket may be placed near the surface of the cable core.

For example, Patent Literature 1 discloses a structure in which a tearing member (tearing string) is brought into close contact with the surface of a cable core to prevent outer covering resin from wrapping inside the tearing member. Further, Patent Document 2 discloses a structure in which a gap is provided between the tearing member and the cable jacket so that the tearing member can be removed without being damaged when scraping off the cable jacket with a peeler or a cutter.

JP 2017-37214 A Japanese Unexamined Patent Application Publication No. 2014-32302

By the way, in order to lay the optical cable in various environments such as indoors and outdoors, there are cases where the cable jacket is composed of multiple layers such as an inner sheath and an outer sheath. In this case, the tearing member for tearing the outer sheath should preferably be placed near the surface of the inner sheath, since the tearing force is less if it is as close to the outer sheath as possible. Also, if the position where the tear string is embedded is known, it can be easily pulled out, so it is desirable that the position in the circumferential direction is fixed in the longitudinal direction. In addition, rather than completely embedding, it is preferable to embed the tear string about halfway so that the visibility of the tear string is improved and it is easy to find.
However, when the tearing member is arranged near the surface of the inner sheath, if the tearing string is covered between the inner sheath and the outer sheath, the tearing member may be completely embedded in the inner sheath, and the entire length of the tearing member may be covered. It is difficult to place it near the surface of the inner sheath by force, and it is also difficult to fix its circumferential position.

The present disclosure has been made in view of the actual situation as described above. The object is to provide a manufacturing method.

A method for manufacturing an optical cable according to an aspect of the present disclosure includes a cable core containing an optical fiber, a cable jacket covering the outer periphery of the cable core, and a cable provided along the longitudinal direction of the cable, a part of which is the above. a wire embedded in the cable jacket and arranged on the outer periphery of the cable jacket, the method for manufacturing an optical cable comprising: a step of extruding a resin for the cable jacket onto the outer circumference of the cable core; a step of arranging the wire on the outer periphery of the extruded resin; and a step of cooling the resin in which the wire is arranged, wherein the arranging step is performed between the extruding step and the cooling step. do in
A method for manufacturing an optical cable according to an aspect of the present disclosure includes a cable core containing an optical fiber, and a plurality of layers covering the outer periphery of the cable core and including at least an inner first sheath and an outer second sheath. and a cable sheath provided along the longitudinal direction of the cable and arranged on the outer peripheral portion of the first sheath with a part thereof embedded in the first sheath for tearing the second sheath 2. A method of manufacturing an optical cable comprising: a step of extruding resin for a first sheath onto the outer circumference of the cable core; and a step of arranging the second tearing member on the outer circumference of the extruded resin. and cooling the resin on which the second tear member is placed, wherein the placing step is performed between the extruding step and the cooling step.

According to the above, the wire is arranged on the outer circumference of the cable jacket with only a part of it embedded in the cable jacket, so that the wire is not buried too much in the cable jacket.

FIG. 5 is a diagram illustrating an example of a sheath covering process for an optical cable in the present disclosure; It is a figure for demonstrating the structure of a crosshead and a plate. (A) is a front view of the plate of FIG. 2, and (B) is a cross-sectional view taken along line BB of (A). 1 is a diagram illustrating an example of an optical cable according to Example 1; FIG. FIG. 10 is a diagram illustrating an optical cable according to Example 2; FIG. 10 is a diagram for explaining an optical cable according to Example 3;

[Description of Embodiments of the Present Disclosure]
First, the contents of the embodiments of the present disclosure will be listed and described.
The method for manufacturing an optical cable according to the present disclosure includes: (1) a cable core containing an optical fiber; a cable jacket covering the outer circumference of the cable core; a wire embedded in the cable jacket and arranged on the outer periphery of the cable jacket, the method for manufacturing an optical cable comprising: a step of extruding a resin for the cable jacket onto the outer circumference of the cable core; a step of arranging the wire on the outer periphery of the extruded resin; and a step of cooling the resin in which the wire is arranged, wherein the arranging step is performed between the extruding step and the cooling step. do in Since the process of arranging the wires is performed between the process of extruding the resin for the cable sheath and the process of cooling this resin, the resin wraps around the wires more than when the wires are arranged in the process of extruding the resin. becomes difficult. Therefore, the wire is arranged on the outer peripheral portion of the cable jacket with only a part of the wire embedded in the cable jacket, and the wire is not buried too much in the cable jacket.

(2) In one aspect of the method for manufacturing an optical cable according to the present disclosure, in the step of arranging the wire, a through hole through which the cable core extruded from the resin for the cable sheath is inserted in the center, and the wire is placed on the side. An adjusting component having an insertion hole to be inserted is arranged to adjust the filling amount of the wire with respect to the extruded resin. By using the adjusting component, the amount of the wire embedded in the cable jacket can be easily adjusted.
(3) In one aspect of the optical cable manufacturing method of the present disclosure, the adjustment component is installed at a position where radial pressure is not applied to the cable jacket resin. Since the wire can be placed in the resin at a location where there is no radial pressure applied to the resin during the extrusion process, the wire can be placed at a fixed location on the cable jacket.
(4) In one aspect of the optical cable manufacturing method of the present disclosure, the wire is a tearing member for tearing the cable jacket, or a band-shaped colored band colored in a color different from the color of the cable jacket, Or it is a rod-shaped steel material for reinforcing the optical cable. If the tearing member is used, the cable jacket can be easily torn at an appropriate position, and if the band-shaped colored band is used, the optical cable can be easily identified because the entire circumference is not buried in the cable jacket. Moreover, if it is a bar-shaped steel material, an optical cable can be reliably reinforced.

(5) In one aspect of the method for manufacturing an optical cable of the present disclosure, a cable core containing an optical fiber and a plurality of layers covering the outer periphery of the cable core and including at least an inner first sheath and an outer second sheath A configured cable jacket and a second sheath provided along the longitudinal direction of the cable and positioned around the outer periphery of the first sheath with a portion thereof embedded in the first sheath for tearing the second sheath. A method for manufacturing an optical cable comprising: a step of extruding resin for a first sheath on the outer circumference of the cable core; and arranging the second tearing member on the outer circumference of the extruded resin. and cooling the resin on which the second tear member is placed, wherein the placing step is performed between the extruding step and the cooling step. Since the step of arranging the second tearing member is performed between the step of extruding the resin for the first sheath and the step of cooling this resin, when the second tearing member is arranged in the step of extruding the resin for the first sheath Compared to , the resin for the first sheath is less likely to wrap around the second tearing member. Therefore, the second tearing member is arranged on the outer peripheral portion of the first sheath with only a part thereof embedded in the first sheath, and the second tearing member is not buried too much in the first sheath. As a result, the position of the second tearing member can be stabilized, and the second sheath can be easily torn.

[Details of the embodiment of the present disclosure]
Preferred embodiments of the method for manufacturing an optical cable according to the present disclosure will be described below with reference to the accompanying drawings.
FIG. 1 is a diagram illustrating an example of a sheath covering process for an optical cable according to the present disclosure. This sheath coating line is equipped with a supply reel 30 , an extrusion device 31 , a cooling device 38 , a take-up capstan 39 and a winding device 40 .

The cable core 2 contains an optical fiber in, for example, a slot rod (also called a spacer), and its outer circumference is wrapped with a pressure winding tape. A slotless cable core may be used. Moreover, the outer periphery of the cable core 2 may be attached with a first tearing member 21 described in FIG. The first tearing member 21 is used for tearing the first sheath 11 of the cable jacket 10 .

The cable core 2 is let out from the supply reel 30 toward the extrusion device 31 . The cable core 2 that has been paid out is introduced into a crosshead 32 provided in an extrusion device 31 .
The extrusion device 31 heats and melts the resin for the cable jacket, and the crosshead 32 supplies the heat-melted resin for the cable jacket to the outer circumference of the cable core 2 .
The moving speed of the cable core 2 is controlled by the take-up capstan 39 . By adjusting the moving speed of the cable core 2 and the extrusion amount of the resin of the extrusion device 31 , the first sheath 11 is formed around the cable core 2 .

(Example 1)
In this embodiment, after the resin for the first sheath is extruded onto the cable core 2, the second tearing member 22 described in FIG. A second tearing member 22 is used to tear the second sheath 12 of the cable jacket 10 . The first sheath 11 corresponds to the cable jacket of the present disclosure, and the second tearing member 22 corresponds to the wire rod of the present disclosure.

The second tearing member 22 is arranged in the longitudinal direction of the cable while being exposed from the first sheath 11 . The cable core 20 coated with the first sheath 11 is sent to the cooling device 38 together with the second tearing member 22 to be cooled, and then passed through the take-up capstan 39 and wound up by the winding device 40 .

FIG. 2 is a diagram for explaining the structure of the crosshead 32 and the plate 35, and is a cross-sectional view of the crosshead 32 and the plate 35 cut in a horizontal direction perpendicular to the longitudinal direction of the cable. 3 is a diagram for explaining the plate 35. FIG. It should be noted that the plate 35 corresponds to the adjusting component of the present disclosure.
As shown in FIG. 2, the crosshead 32 is provided with a cylindrical nipple 33 extending in the longitudinal direction of the cable. A cylindrical die 34 is provided in front of the nipple 33 .

The inlet of the die 34 is arranged to face the outlet of the nipple 33 , and the outlet of the die 34 formed at the front end of the die 34 is exposed through the opening of the crosshead 32 . The front end of the die 34 is a point where the pressure of the resin R for the first sheath extruded in the crosshead 32 becomes zero (or a point where the pressure is low enough that the resin R has no resistance). A plate 35 is installed at the front end of the die 34 . As shown in FIG. 3A, the plate 35 has, for example, a substantially elliptical plate body 35a when viewed from the front, and is fixed to the front end of the die 34 with a plurality of bolts (not shown).

A through-hole 36 is formed in the center of the plate body 35a so as to pass through the plate body 35a along the longitudinal direction of the cable. The through-hole 36 is concentric with and opposed to the exit of the die 34 , and the inner diameter of the through-hole 36 is adjusted to adjust the filling amount of the second tearing member 22 with respect to the first sheath 11 . It is formed to have the same size as the outlet or a slightly larger size than the outlet of the die 34 .

Further, as shown in FIG. 3A, insertion holes 37 and 37a extending toward the through hole 36 are provided on the side surface of the plate body 35a. The insertion hole 37 is arranged on the left side of the plate 35 when viewed from the front, and the insertion hole 37a is arranged on the right side of the plate 35 when viewed from the front.
The entrances of the insertion holes 37 and 37 a are formed, for example, below the through hole 36 , and the string-like second tearing member 22 is fed from below the plate 35 toward the entrance of the insertion hole 37 . Further, the string-like second tearing member 22a shown in FIG. 4A is fed from below the plate 35 toward the entrance of the insertion hole 37a.

The through holes 37 , 37 a are, for example, inclined to approach the through hole 36 and then extend horizontally. In addition, in FIG. 3B, the exit of the insertion hole 37 can be seen.
A second tearing member 22 is arranged in the insertion hole 37 , and the second tearing member 22 is supplied from the entrance of the insertion hole 37 by the driving force of a driving device (not shown), and is supplied from the exit of the insertion hole 37 . It is sent into the through hole 36 . 4(A) is arranged in the insertion hole 37a, the second tearing member 22a is also supplied from the entrance of the insertion hole 37a, and penetrates from the exit of the insertion hole 37a. It is fed into bore 36 .

The cable core 2 that is drawn out from the supply reel 30 and reaches the crosshead 32 is passed through the nipple 33 and directed forward. The resin R for the first sheath is supplied to the outer periphery of the nipple 33 from the side of the nipple 33, and is extruded onto the outer periphery of the cable core 2 in the die 34 to cover the cable core 20 with the first sheath 11 covered. becomes. The cable core 20 that has reached the exit of the die 34 is directed toward the through hole 36 of the plate 35 .

The cable core 20 covered with the first sheath 11 passed through the through-hole 36 of the plate 35 is supplied with the second tearing members 22, 22a from the side, and moves further forward. The inner peripheral surface of the through-hole 36 contacts the second tearing members 22 , 22 a and can press the second tearing members 22 , 22 a toward the first sheath 11 . Thereby, the filling amount of the second tearing members 22 and 22a with respect to the first sheath 11 is adjusted. Then, the cable core 20 with the second tearing members 22 , 22 a exits the through hole 36 toward the cooling device 38 .

When the resin for the second sheath is extruded to the outer circumference of the cable core 20 coated with the first sheath 11, after the coating process for the first sheath, the next process ( second sheath coating step), and the second sheath 12 is over-molded around the first sheath 11 .

As described above, the process of arranging the second tearing members 22, 22a is performed between the process of extruding the resin R for the first sheath and the process of cooling the resin R, so that the pressure of the resin applied by the die is applied. The second tearing members 22 and 22a are arranged in a state in which there is no resin R for the first sheath compared to the case where the second tearing members 22 and 22a are arranged in the step of extruding the resin R for the first sheath. is less likely to wrap around the second tearing members 22, 22a. Therefore, the second tearing members 22, 22a are partly embedded in the first sheath 11 (the other parts of the second tearing members 22, 22a are exposed from the outer periphery of the first sheath 11). It is arranged on the outer peripheral portion of the first sheath 11 so that the second tearing members 22, 22a are not buried in the first sheath 11 too much. As a result, the positions of the second tearing members 22, 22a can be stabilized, and when the second sheath 12 is covered thereon, the second sheath 12 can be easily torn.

In the above embodiment, an example in which the plate 35 is installed directly on the front end of the die 34 has been described. In this case, since the plate 35 is heated by the resin R in the die 34, the second tearing members 22, 22a can be more easily embedded in the first sheath 11. However, the invention is not limited to this example. For example, a plate may be placed just before the cooling device 38 . In order to heat the plate in this case, for example, a heater may be used. Also, if the resin temperature is too high, the plate 35 may be separated from the die 34 .

Further, in the above-described embodiment, an example has been described in which the second outer sheath 12 is pushed out in a separate process after the first inner sheath 11 is pushed out. However, it is also possible to push out the first inner sheath and place the second tear member, followed by simultaneously pushing out the second outer sheath.

FIG. 4 is a diagram explaining an example of an optical cable according to the first embodiment.
In the optical cable 1 manufactured as described above, the cable core 2 is covered with a two-layer cable jacket 10 as shown in FIG. 4(A). The cable jacket 10 is composed of a first sheath 11 made of first sheath resin and a second sheath 12 made of second sheath resin.

A first sheath 11 covers the outside of the cable core 2 and also covers a first tearing member 21 for tearing the first sheath 11 . In addition, the second sheath 12 covers the outside of the first sheath 11, and the two second tearing members 22 and 22a are partially embedded in the outer peripheral portion of the first sheath 11. It is stuck.
Alternatively, as shown in FIG. 4B, the cable jacket 10 may be composed of three layers such that the outside of the second sheath 12 is further covered with a third sheath 13 . In this case, a third tearing member 23 for tearing the third sheath 13 is embedded in the outer peripheral portion of the second sheath 12 .

Alternatively, as shown in FIG. 4C, a shield 14 made of steel or hard plastic tape may be vertically attached between the first sheath 11 and the second sheath 12 . In this case, markings may be provided on the surface of the second sheath 12 to clarify the position of the second tearing member 22 for tearing the second sheath 12 .

By the way, in the above embodiments, the tearing member was described as an example of a wire rod. However, it is also possible to use the plate described above to place colored strips or steel on the cable jacket between the extrusion of the resin for the cable jacket and the cooling of this resin. In other words, these colored bands and steel materials also correspond to the wire of the present disclosure.

Specifically, in the optical cable 1a shown in FIG. 5, the first sheath 11 (corresponding to the cable jacket of the present disclosure) covers the cable core 2, and the outer circumference of the first sheath 11 is exposed from the outside of the optical cable 1a. It has a recognizable color band 24 . The colored band 24 is formed, for example, in a strip shape, is colored in a color (eg, pink) different from the color (eg, black) of the first sheath 11, and extends along the longitudinal direction of the cable. Since such colored bands are exposed on the surface without being embedded in the cable jacket, the cable can be easily identified.

In the optical cable 1b shown in FIG. 6, the first sheath 11 covers the cable core 2, and a plurality of steel members 25, for example, in the shape of a round bar, are arranged around the outer periphery of the first sheath 11 as reinforcing materials. . Also in this case, the side surface of each steel material 25 is exposed from the outer circumference of the first sheath 11 .

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present disclosure is indicated by the scope of the claims rather than the above-described meaning, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

1, 1a, 1b... optical cable, 2, 20... cable core, 10... cable jacket, 11... first sheath, 12... second sheath, 13... third sheath, 14... shield, 21... first tearing member, 22, 22a... Second tearing member, 23... Third tearing member, 24... Color band, 25... Steel material, 30... Supply reel, 31... Extruding device, 32... Cross head, 33... Nipple, 34... Die, 35... Plate 35a... Plate main body 36... Through hole 37, 37a... Insertion hole 38... Cooling device 39... Take-up capstan 40... Winding device R... Resin for first sheath.

Claims (5)

A cable core housing an optical fiber, a cable jacket covering the outer periphery of the cable core, and the cable jacket provided along the longitudinal direction of the cable with a portion thereof embedded in the cable jacket. A method for manufacturing an optical cable comprising a wire rod arranged on the outer periphery of the
a step of extruding a cable jacket resin onto the outer periphery of the cable core;
placing the wire on the outer periphery of the extruded resin;
a step of cooling the resin in which the wire is arranged;
including
A method of manufacturing an optical cable, wherein the disposing step is performed between the extruding step and the cooling step. In the step of arranging the wire rod, an adjusting part having a through hole for inserting the cable core extruded from the resin for the cable jacket in the center and an insertion hole for inserting the wire rod in the side part is arranged, and the extrusion is performed. 2. The method of manufacturing an optical cable according to claim 1, wherein the filling amount of the wire with respect to the resin is adjusted. 3. The method of manufacturing an optical cable according to claim 2, wherein said adjustment component is installed at a position where radial pressure is not applied to said cable jacket resin. The wire material is a tearing member for tearing the cable jacket, a band-shaped colored band colored in a color different from the color of the cable jacket, or a rod-shaped steel material for reinforcing the optical cable. The method for manufacturing an optical cable according to any one of claims 1 to 3. a cable core containing an optical fiber; a cable sheath covering the outer circumference of the cable core and composed of a plurality of layers including at least an inner first sheath and an outer second sheath; a second tearing member for tearing the second sheath, the tearing member being partially embedded in the first sheath and disposed on the outer peripheral portion of the first sheath; There is
extruding resin for the first sheath onto the outer circumference of the cable core;
placing the second tearing member on the outer periphery of the extruded resin;
cooling the resin in which the second tearing member is arranged;
including
A method of manufacturing an optical cable, wherein the disposing step is performed between the extruding step and the cooling step.

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