JPH02285911A - Cable anchor - Google Patents

Abstract

PURPOSE: To easily disassemble parts, for reducing the tensile strength of a wire by providing a nipping part for nipping a wire, a means for making the nipping surface have a certain angle to the longitudinal direction of a cable and a trumpet-type wire-guiding surface. CONSTITUTION: An optical fiber submarine cable comprises an electrically conductive metal tube 1 closely surrounded by internal and external tensile strength strand layers 2, 3, formed of steel having high tensile force. The anchoring device comprises a first and a second nipping parts 3A, 2A for nipping a wire between nipping surfaces 4A, 5A and 5C, 6A, a means for holding the nipped parts to each other and making the nipping surfaces 4A, 5A and 5C, 6A have a certain angle to the longitudinal direction of a cable and a trumpet type wire guiding surfaces 4B, 5B for guiding a wire from the direction in parallel to an axis in the longitudinal direction to the direction parallel to the nipping surfaces 4A, 5A and 5C, 6A. The nipping angle is in the range of 45 deg. to 90 deg.. Therefore, parts can be disassembled easily, and the wire tensile strength can be reduced by about 5%.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to cable mooring devices, particularly, but not limited to, cable mooring devices for mooring submarine cables to underwater housings such as splice chambers.

The prior art British Patent No. 322653 is YA
7 shows a cable clamp maintained with a single rope being clamped. This greatly reduces the clamping of the wire as the clamp creates a weak point in the cable at the end of the cable. The clamps are not suitable for fiber optic cables because there is no area for the fibers and there is no protection for them within the clamp.

GB 1 139 841 shows a conventional Taber clamp, the strength of which depends on the self-locking effect of the Taber. The disadvantages of this type of clamp are that it is limited as to the maximum number of strength member wires that it can clamp, and that large radial strengths are required to prevent fragile optical packages from being crushed by the wedging effect at the taber. be. It also introduces weaknesses in cable links.

British Patent No. 1441929 is FI-like, and unless very strong components are used, there is also a risk of the fiber package breaking, which is the biggest weakness of cable links.

Particularly in the prior art, the assembly process results in relative movement between the strand wires of different layers, which causes the strands lI! 7 resulting in uneven load distribution. As mentioned above, due to the strong radial force caused by the Taber effect,
There is always a possibility of breaking the weak light package. Particularly in fiber optic submarine cables that have a conductive voltage tube directly below the tension member wire, this tube becomes pinched, thereby putting pressure on the weak optical package therein.

It has been found that some shears grab the high tensile steel wire at the Taber clamp end, which tends to greatly reduce the wire's designed ultimate tensile strength.

Additionally, Taber clamp terminations are limited to use with single or double layers of stranded wire. Its length makes it impractical to use it in more than two layers of strands.

Finally, it is difficult to disassemble the parts of a conventional Taber clamp after the parts are assembled due to some friction against the relative movement of the parts.

According to the invention, first and second clamping parts clamping the wire between their clamping surfaces, and means for holding the clamped parts together, the clamping surfaces being at an angle with respect to the longitudinal axis of the cable, are provided. A mooring device for a cable wire tensile strength member is provided which comprises a trumpet-shaped wire guide surface extending from a direction parallel to a directional axis to a direction parallel to a clamping surface.

One of the advantages of having a clamping surface at an angle, for example 90', to the longitudinal axis is that a large number of strand wires can be accommodated. In addition, the tether can be designed to accommodate several stranded layers, one after the other for each additional stranded layer with a load-carrying member.

Additionally, damage to the weaker core in fiber optic cables is less likely to occur.

The desired clamping angle with respect to the longitudinal axis of the cable is 90
”, smaller angles like 60° are possible, but
Angles not smaller than 45° are conceivable.

The mooring according to the invention has advantages over conventional Taber clamp terminations with little or no radial forces, the parts are easily disassembled, and reductions in wire tensile strength of as much as 5% can be achieved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, a partially illustrated fiber optic submarine cable comprises conductive gold-layer tubes closely surrounded by inner and outer tensile strength strands WA2 and 3, respectively, made of high-strength steel (HTS). Consists of 1. The rest of the submarine cable is not shown in detail. For example, if there is an optical fiber package within the voltage tube 1 and around the outside of the strand wire there is sufficient power to energize the voltage tube 1 with electricity to drive the regenerator with or without associated strand wire conductivity. It has an insulating exterior. The sheath provides insulation to the seabed.

The mooring device includes a first clamping block 4 having a clamping surface 4A;
and a wire guide defining a trumpet-shaped lead surface 4B which forces the outer strand wire 3 to follow a bending radius designed such that the surface strain of the wire does not exceed 4%. This ensures that the ultimate tensile strength of the high-strength steel strand wires 3 is not less than 95% of their expected strength.
indicated as a limit value. Obviously for larger diameter wires a larger bending radius is required.

The end 3A of the outer strand wire 3 is clamped between the clamping surface 4A of the block 4 and the clamping surface 5A of the block 5 adjacent thereto.

The clamping surfaces make an angle to the longitudinal axis 1Δ of the cable.

In this particular embodiment, the angle is 90° so that the clamping pressure is parallel to the cable axis and the clamping plane is perpendicular to the cable axis. However, it is not essential that the clamping plane be 90°; in fact, it may be 90° plus or minus 30', and at least 45° to the cable wire.
angle is required. Below this angle, the tether begins to acquire the characteristics of a tapered clamp, with superior mechanical advantages.

The block 5 also has a wire guide portion defining a wire lead surface 5B, and its radius is designed so that the surface strain of the wire 2 does not exceed 4%. The end 2A of the wire 2 is clamped between the clamping surface 5C of the block 5 and the cooperating clamping surface 6A of the block 6.

Preferably, at least one of the respective clamping surfaces of the block has its friction increased by means of grit evenly distributed and bonded to the surface in the manner described in the applicant's European Patent Application No. 89311560. Preferably, the bond is as described therein (in the form of a braze and the particles are between 100 and 3
It is within the range of 00μ steel, and the wire penetration depth is Wire A7.
It should not be larger than 5% of the diameter.

The three blocks 4.5 and 6 are clamped together by a thin-walled outer casing 7 having a threaded end 8 into which a threaded member 9 is inserted.

The casing 8 has an inwardly directed annular shoulder 10 that resists the clamping force of the screw member 9. As the screw member 9 is screwed into the casing, the blocks 4, 5 and 6 are squeezed together so that the wire ends 3A and 2A are firmly clamped between the clamping surfaces of the blocks.

The tether has a through passage 11 to accommodate the central optical package of the cable extending from end 8A of casing 8.

The radius of curvature of the trumpet-shaped section is sized according to the diameter of the clamped wire, ie, the radius is a fundamental parameter that can be varied depending on the wire size.

]-1 When the TS wire is bent with a very small radius,
If the bending radius of the wire is not restricted, a significant decrease in tensile strength is seen. In this example, when the radius of trumpet sections 4B and 5B is 16.7x wire radius, there is only a 4% reduction in wire strength, which will be explained in more detail in conjunction with FIG.

The inventor conducted the following test. Approximately 500a*fi4
A sample of strand wire with an inner diameter of 2.64 am or an outer diameter of 1.21 M as representative of wires 2 and 3, respectively, was wound around the former and then placed in an Instron (l ns -t
ron) was clamped in the jaws of a tensile test machine. The diameter of the former was varied between 12 mm and 40 m+. The tensile load was then increased on the sample with the former held in place until failure occurred and the load at failure was recorded.

Referring to Figure 2 of the drawings; S=Rθ (1) S= to S+
(R+Δr)θ 0 The strain ε of the wire due to bending is the ratio of the increase in the wire length ΔS to the initial length S.

That is, the strain in the wire is the ratio of the diameter of the wire to the diameter of the former.

For a 2.64 m diameter wire, the breakage occurs every time at a location just on the wire before wire A7 leaves the former. It is interesting that failure does not occur at other locations on the former, where the contact stresses are of similar magnitude. Therefore, failure is believed to be induced at this location due to the high normal contact stress combined with the shear stress (wire strain) and the rapid change in stress as the wire leaves the former.

For a 1.21 am diameter wire, failure occurs similarly to a 2.64° diameter wire.

The general trend for wire drawings is that the bending radius decreases as the tensile strength decreases.

For a 2.64 m diameter wire, a rapid decrease in strength occurs for bend radii smaller than 15 aw+, while for a 1.21 m diameter, the decrease occurs for bend radii larger than 6#II. It doesn't seem like it's going to happen.

Assuming that a 5% decrease in axial strain strength can be tolerated,
A minimum bending radius of 15.0 mm is provided at guide surface 5B for a 2.64 mm diameter wire, and a minimum bend radius of 6 m is provided at guide surface 4B for a 1.21 mm diameter wire.

[Brief explanation of drawings]

FIG. 1 shows a universal cable mooring device according to an embodiment of the present invention.
FIG. 2, which is a somewhat diagrammatic view taken in longitudinal section, is a diagram illustrating how the wire strength depends on the bending radius. 1... Conductive metal tube, 2.3... Strand layer, 2
A, 3A... Line end, 4, 5.6... Block, 4
A, 5A, 5G, 6A... clamping surface, 48.58...
Guide surface, 1...Casing, 8...Thread end, 8A
. . . End portion, 9 . . . Screw member, 10 . . . Shoulder portion. ~, 2゜procedural amendment

Claims (1)

[Claims] 1. A first and a second sandwiching surface that clamps the wire between the clamping surfaces.
a clamping portion of the cable, a means for holding the clamped portions together, the clamping surface being at an angle to the longitudinal axis of the cable, and a trumpet type for guiding the cable from a direction parallel to the longitudinal axis to a direction parallel to the clamping surface. A mooring device for a cable wire tensile strength member consisting of a wire guide surface. 2. Claim 1, wherein the angle is within the range of 45° to 90°.
Mooring as described. 3. A moor as claimed in claim 1 or 2, wherein at least one of the surfaces is roughened to increase its grip on the wire tensile strength member. 4. The mooring device of claim 3, wherein the roughness comprises grit held firmly on the surface. 5. The mooring device according to claim 4, wherein said grit comprises tungsten carbide coarse particles. 6. A third clamping part, wherein the second and third clamping parts have respective clamping surfaces arranged to clamp another tension member of the cable therebetween. The mooring device described in any one of the items. 7. The tether of claim 6, wherein the clamping surfaces for clamping the separate wire tensioning member are at an angle to the longitudinal axis of the cable. 8. A tether according to any one of claims 1 to 7, further comprising a passageway passing through the tether to accommodate a fiber optic package of the cable.