JPS5938561B2 - Sealed optical fiber core movement prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical fiber cable movement prevention device in a sealed termination cable lead-out section of a submarine optical cable that requires water-resistant sealing.

FIG. 1 shows the sealed core lead-out portion of a conventional submarine optical cable.

Figure A is a sectional view, and Figure B is a view of Figure A viewed from the direction of the arrow. As shown in the figure, the optical fiber coated wire 1 is passed through the bottom of a part 2' having a hole 4' with a through hole 3 somewhat larger than the outer diameter of the optical fiber coated wire near the center of the bottom at one end. After passing through the hole 3, a curable resin is filled and cured around the optical fiber core 1 contained in the hole 4' to form a curable resin portion 5'.

Prevention of movement of the optical fiber coated wire 1 mainly depends on the adhesiveness between the nylon resin, which is the optical fiber coated material, and the curable resin. However, in order to improve reliability, it is necessary to lengthen the hole 4', which has been a drawback in that the termination section cannot be made smaller. Additionally, the properties of curable resins vary depending on the formulation and curing conditions, and there are drawbacks such as difficulty in pulling optical fibers straight through, and the properties vary depending on the skill level of the operator. There were flaws.

Currently, optical fiber core structures with a buffer layer are being considered.

When a submarine optical cable is cut, the optical fiber cores come into direct contact with high-pressure seawater. In the structure with a buffer layer currently under consideration, the silicone rubber used for the buffer layer and the nylon secondary coating material do not have adhesive properties, and high-pressure seawater will enter the interface between the two, making it impossible to ensure complete airtightness. In this case, even if movement of the core wire can be prevented, the original role of ensuring airtightness is not fulfilled. In the method of removing the coating of the optical fiber and molding that part with curable resin in order to ensure complete airtightness, the coating must be removed in the middle of the optical fiber, which increases the probability of optical fiber breakage. The disadvantage is that it is very high. In order to eliminate the drawbacks of the conventional art, the present invention provides a connection point in which the strands of the coated optical fibers are fused in the center, and the connection points are connected to the strands of the strands and the optical fibers on the left and right sides of the strands. A movement preventing member made of a curable resin or the like having a symmetrical conical shape with a taper that descends left and right at the center is provided at the connection point, and the optical fiber is inserted through the center symmetrically with respect to a plane passing through the connection point. A back-up member, a tapered metal part, a rubber part, a presser ring, and a cap-nut type metal sleeve are arranged on the outer side, and a hole is provided in the center of the back-up member into which half of the movement prevention member can be inserted closely. The movement prevention member is inserted, the tapered metal part is arranged at the tip of the movement prevention member in the hole, the backup member is provided with a cylindrical recess on the outside of the hole, and the rubber part is provided with a cylindrical recess on the connection point side. an O-ring part on the outside, a nozzle part on the outside, a cylindrical groove part into which the nozzle part is inserted into the center of the connection point side of the cap-nut type metal sleeve, and the retainer ring on the outer periphery of the groove part. An annular groove portion for insertion is provided, and the O-ring portion and the presser ring of the rubber component are inserted into the recess of the backup member, and the nozzle portion and the presser ring of the rubber component are inserted into the cylindrical groove portion and the annular groove portion of the cap nut-shaped metal sleeve. The present invention is characterized in that the cap nut-shaped metal sleeve is fixed to the back-up member, and the purpose thereof is to shorten the member for preventing movement of the optical fiber core and improve airtightness.

The present invention will be explained based on the drawings. FIG. 2 shows a sectional view of an example of the sealed optical fiber movement prevention device of the present invention.

In the figure, 1 is an optical fiber, 6 is an optical fiber obtained by completely removing the coating layer from the optical fiber, 7 is a fusion splice between the optical fibers, and 2 is a tapered hole 4 passing through the optical fiber. The backup member 5 has tapered edges on both sides, contains a fusion splice, an uncoated wire, and a coated core wire, and is molded from curable resin, thermoplastic resin, or rubber. 8 is a tapered metal part; 9 is a nozzle part 11 having a through hole 10 in the center including the main body part, which is somewhat narrower than the outer diameter of the optical fiber, on the outside and on the inside. A rubber part having an O-ring-shaped collar 12 around the periphery, 13 a presser ring for holding down the O-ring portion, and 14 a metal sleeve are shown.

Next, the assembly order of the sealed optical fiber core wire movement prevention device of the present invention will be explained.

A metal sleeve 14 is attached to each of the two optical fiber cores 1,
Pass the presser ring 13 through.

Since the optical fiber through hole 10 of the rubber component 9 is somewhat smaller than the outer diameter of the optical fiber, a hypodermic needle-like wire passing jig T having an inner diameter somewhat larger than the outer diameter of the optical fiber is prepared in advance. The optical fiber core 1 and the rubber component 9 are inserted into the rubber component 9 by passing the optical fiber core 1 through the hole in the rubber component, passing the optical fiber core 1 through the hole in the wire-running jig T, and then removing the wire-running jig T. The nozzle side is directed toward the side opposite to the end of the optical fiber core wire 1. Further, a backup member 2 and a tapered metal part 8 are passed through the optical fiber core wire 1. The coating at the end of the optical fiber core wire 1 is completely removed to expose the strand 6, the end of the strand 6 is cut to expose a clean surface, and the clean surfaces are brought together and heated by discharge. fusion splice. Next, the fusion splicing point 7, the optical fiber bare wire 6 without a coating layer on both sides, and a tapered split mold on both sides including the coating layer are covered, and a curable resin, thermoplastic resin, or Rubber is molded in the mold to form a conical movement prevention member 5 integrally tapered on both sides. Conical metal parts 8 are brought into close contact with both sides of the movement prevention member 5, and the back up members 2 are brought into close contact with the tapered hole 4 of the back up member 2. Since the hole 10 of the rubber component 9 is somewhat smaller than the outer diameter of the optical fiber core 1, the rubber component 9 is difficult to move, but it can be moved by improving the lubricity with grease. Next, the O-ring portion 12 of the rubber component 9 is tightened using the presser ring 13 by fixing the cap nut-shaped metal sleeve 14 to the back-up member 2, thereby completing the sealed optical fiber core movement prevention device of the present invention. Can be assembled. When the sealed optical fiber cable movement prevention device of the present invention is submerged on the seabed and water pressure is applied to either side, the watertightness is determined by the O
- held by the ring part 12 and the nozzle part around the optical fiber core;

Moisture that has entered the interface between the buffer layer and the secondary coating can be removed if the coating is completely removed near the connection point and that area is sealed and integrated with the optical fiber core using a curable resin, thermoplastic resin, or rubber. This part completely prevents intrusion further. In addition, movement of the optical fiber core wire is also possible because the movement prevention member 5 has tapers on both sides, and the back-up member 2 into which the movement prevention member 5 is placed also has a taper with the same slope. When the prevention member 5 moves, the taper acts as a stopper, thereby preventing movement toward the low pressure side. Since the movement prevention member 5 is symmetrical in the axial direction of the optical fiber, it has the effect of preventing movement of the optical fiber even if pressure is applied from either side. It is airtight, and the movement prevention part of the optical fiber core can be concentrated in one place, which has the effect of shortening the length.

Furthermore, if an attempt is made to remove the coating in the middle of the optical fiber, the probability of breakage of the optical fiber becomes very high. In the sealed type optical fiber movement prevention device according to the present invention, the portion from which the coating is removed for fusion splicing the optical fibers is molded into a movement prevention member made of curable resin or the like to obtain airtightness. Since it is useful as is, there is no need to increase the number of steps. Between the metal part 8 and the rubber member 9,
There may be a gap at normal pressure, but when pressure is applied from the nozzle side of the rubber member, the rubber member easily deforms and fills this space, so this space cannot be left at atmospheric pressure. Therefore, even if high-pressure water enters the optical fiber core, there is no possibility of damaging the coating in this space.

If extra length processing parts are provided on both sides of the sealed optical fiber core movement prevention device of the present invention, they can also be used as connecting parts.

In the sealed type optical fiber movement prevention device of the present invention, as described above, the movement prevention member provided at the center has a taper that goes down from the top to both sides, and the back-up member also has a taper with the same slope. , it is possible to prevent the optical fiber from moving due to force from either of them.

Since the rubber members with nozzles are arranged on both sides with the backup culture medium in between, airtightness can be maintained in both directions.
Since the movement prevention member is molded with a curable resin after removing the coating of the optical fiber core, water intrusion between the buffer layer and the secondary coating interface can be prevented.

By providing the migration prevention member at the connecting portion, there is no difficulty in removing the coating in the middle of the optical fiber core wire.

If used together with an extra length processing section, it can be applied to the connection section of an optical cable with an airtight dam.

[Brief explanation of the drawing]

Figure 1 is a conventional sealed core wire movement prevention part, Figure A is a sectional view,
Figure B is a view seen from the direction of the arrow in Figure A, and Figure 2 is a sectional view of the sealed optical fiber movement prevention device according to the present invention. 1: Optical fiber core wire, 2: Backpack material, 3: Core wire through hole, 4: Hole, 5: Movement prevention member, 6: Optical fiber wire, 7: Fusion splicing point, 8: Tapered metal Parts, 9:
Rubber parts, 10: Optical fiber core through hole, 11: Nozzle section, 12: O-ring section, 13: Holding ring, 14: Cap nut type metal sleeve.

Claims (1)

[Claims] 1. A connection point is provided in the center by which strands of coated optical fibers with the coating removed are fused together, and left and right tapers that descend to the left and right around the connection point are provided on the strands and the optical fibers on the left and right sides of the strands. A movement prevention member made of a curable resin or the like having a symmetrical conical shape is provided, and a backup member and a tapered metal part are provided outside the connection point through which the optical fiber is inserted symmetrically with respect to a plane passing through the connection point. , rubber parts,
A presser ring and a cap nut type metal sleeve are provided, a hole is provided in the center of the backup member into which half of the movement prevention member can be inserted closely, the movement prevention member is inserted, and the tip of the movement prevention member is inserted into the hole. The tapered metal part is disposed in the back-up member, a cylindrical recess is provided outside the hole, and the rubber part is provided with an O
The ring part has a nozzle part on the outside, a cylindrical groove part into which the nozzle part is inserted into the center of the connection point side of the cap nut type metal sleeve, and the retaining ring is inserted into the outer periphery of the groove part. An annular groove is provided, and the O-ring part and the presser ring of the rubber component are inserted into the recess of the backup member, and the nozzle part and the presser ring of the rubber component are inserted into the cylindrical groove and the annular groove of the cap nut-shaped metal sleeve. . A sealed optical fiber core movement prevention device comprising the cap nut type metal sleeve being fixed to the backup member.