JPS6217932B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a submarine cable cutting grapone capable of easily cutting a submarine cable when the submarine cable is salvaged and repaired.

Conventionally, when a failure occurs in the transmission line of a submarine cable such as a submarine optical fiber cable, it is lifted using a grapnel for probing lines such as gift grapnel, original grapnel, or Maruhiroku grapnel. Lift up the defective part of the installed cable in a catenary shape and pull it up, or cut the part near the defective part by the tension during lifting.
A method is adopted in which both cut ends are then pulled up.

In the above construction method, the load applied to the installed cable (submarine optical fiber cable) will be explained using FIG. 1. In this construction method, the laying cable 1 is attached to a probe anchor 4 for grasping the cable attached to the tip of a grapnel rope 3 attached to a laying ship 2.
It is lifted using. At this time, a very large tension is applied to the lifted portion and its vicinity due to the weight of the installed cable 1, so that a large elongation occurs in the lifted portion and its vicinity. However, as is well known, the breaking strain of optical fibers is small, and the maximum allowable short-term elongation is about 0.5%, even if the strength of the optical fiber is increased. This is because in order to guarantee short-term growth of 0.5%, it is necessary to perform a quality inspection (screening) in which the cable is given an elongation of about 1% and the criterion is whether or not the cable will break. This is because it is difficult to screen long optical fibers by as much as 1% with current technology, and it is not possible to guarantee quality for short-term growth of 0.5% or more.

By the way, Figure 2 shows the elongation strain (%) of the laid cable when it is lifted from a maximum water depth of 5000 m. Note that the coefficient of friction on the seabed surface at this time is 0.5. In this figure, slack (ratio of spare length to minimum required length) is 2.
% and 5%, respectively, are shown. As is clear from this figure, by increasing the slack, elongation strain during lifting can be suppressed. However, increasing the slack increases the possibility that the installed cable will form a loop and cause a kink, and also increases the overall length of the cable, which has the disadvantage of increasing the cost of installation materials.

On the other hand, even if the installed cable is introduced with the largest possible slack (5%), the maximum cable elongation strain during lifting will be around 0.8%.
Furthermore, the length of the cable where the elongation strain exceeds the permissible elongation strain of optical fiber (0.5%) is as long as 10 km. In addition, even if the installed cable is subjected to elongation strain that exceeds the allowable elongation strain, even if the optical fiber does not break during lifting, cracks on the surface of the optical fiber will grow due to the elongation of the installed cable during lifting. If tension is applied again, there is a high possibility that it will break even with a very small tension. Therefore, it becomes necessary to replace the cable portion to which an elongation strain exceeding the allowable elongation strain as described above has been applied.

Therefore, as shown in Figure 2, the slack is 5%
In this case, a section of approximately 10 km on one side will experience an increase of 0.5% or more, so the total length will be approximately 20 km.
cables will need to be replaced. Furthermore, if the slack is set at 20%, approximately 70 km of cables will need to be replaced.

Using this method of hoisting optical fiber cables laid on the ocean floor from the deep sea floor using conventional grapnels, it is difficult to extend the laid cables over long distances due to the reliability of the optical fiber's elongation strength. The disadvantage was that the installed cables had to be replaced and repairs were costly.

The present invention has been made in view of the above circumstances, and its purpose is to provide a submarine cable cutting grapnel that can significantly reduce the tension applied to the submarine cable when the submarine cable is salvaged. A cutting blade is provided on the cable gripping part of the probe tool, so that the cable can be forcibly cut when probing or salvaging submarine cables.

Hereinafter, the present invention will be explained with reference to the drawings. FIGS. 3 and 4 show an embodiment of the present invention. In the figure, reference numeral 10 indicates a cut grapnel according to the present invention, and 11 indicates a support body.As shown in FIG. A lower end portion 1 that is integrally formed with the main body 11a and is curved into a hook shape.
1b. A shaft hole 12 is bored near the center of the lower end 11b of the support body 11, and a shear pin hole 13 is bored in the lower part of the lower end 11b. A locking recess 15 is formed between them.

A hollow rectangular column-shaped connecting member 16 is fixed to the upper part of the support body 11 formed as described above. This connecting member 16 has a central rod 1 having a connecting hook 17 connected to the grapnel rope 3 at the upper end.
8 is loosely fitted and passed through, and the center rod 18 can slide in parallel to the support 11. Further, on the side surface of the upper part of the support body 11 that is perpendicular to the side surface to which the connection member 16 is fixed,
A stabilizing blade 19 formed into a substantially triangular plate shape is fixed. Further, on the side of the lower end of the support body 11 to which the connecting member 16 is fixed, a rotating member 20 formed in a substantially L-shape is attached to the lower end 11b.
It is rotatably supported by a pivot shaft 21 fitted into a shaft hole 12 of.

As shown in FIGS. 6a and 6b, the rotating member 20 is in close contact with the lower end 11b of the support 11, and has a sliding plate portion 22 that rotates and slides with respect to the lower end 11b.
A triangular plate-shaped connecting plate part 23 is formed integrally with this sliding plate part 22, and a triangular plate-shaped connecting plate part 23 is integrally formed with this sliding plate part 22 on the opposite side of the sliding plate part 22 from the connecting part 23. It is composed of a cable introduction body 24 that is The sliding plate portion 22 is completely formed into a disk shape, and the sliding plate portion 22 includes the lower end portion 1.
It is formed to have the same shape and dimensions as the locking recess 15, shaft hole 12, and shear pin hole 13 of 1a, and when the rotating member 20 is attached to the support 11, the locking recess 15, shaft hole 12, and shear pin hole 1a are formed. A locking recess 25 and a shaft hole 26 that correspond to the hole 13, respectively.
and a sear pin hole 27. The connecting plate portion 23 is formed thinner than the sliding plate portion 25, and has a shaft hole 28 bored at its end. The cable introduction body 24 is formed higher and wider than the sliding plate portion 22, and is formed in a tapered shape that narrows upward when viewed from the side (Fig. a). Further, as shown in FIG. 6b, the side surface 24a of the lower part of the cable introducing body 24 adjacent to the sliding plate part 22 is such that the rotating member 20 is attached to the supporting body 11 as shown in FIG. It is formed in a circumferential shape so as to be in contact with the outer peripheral surface of the lower end portion 11b of the support body 11 when attached. Therefore, in FIG. 3, the rotating member 20 is prevented from rotating in the direction opposite to arrow A from the illustrated position, and can only rotate in the direction of arrow A from this illustrated position. There is.

The connecting plate portion 28 of the rotating member 20 formed as described above is connected to the center rod 1 by a crank rod 29.
It is rotatably connected to 8.

In the above structure, the locking recesses 15 and 25 form a cable cutting part 30, and this cable cutting part 30 is a place where the laid cable 1 is locked and cut, as will be described later. By the rotation of the rotating member 20, this laid cable 1 is connected to one side surface (hereinafter referred to as a first cutting blade) 30a of the locking recess 15 and one side surface (hereinafter referred to as a second cutting blade) of the locking recess 25. (referred to as the cutting blade) 30b closes, the cutting blade receives a shearing force and is cut.

In order to use the submarine cable cutting grapnel 10 according to the present invention configured as described above, first, as shown in FIGS. 3 and 4, the shear pins (locking members) 31 are inserted into the shear pin holes 13 and 27. do. The shear pin holes 13 and 27 are set so that the shear pin 31 can be inserted into the shear pin holes 13 and 27 when the center rod 18 is pushed down and the cutting blades 30a and 30b forming the cable cutting section 30 are open. 31 is inserted, the cutting blades 30a and 30b provided in the cable cutting section 30 are fixed in an open state. Then, as shown in FIG. 7, this cut grapnel 10 is transported from the laying ship 2
0 until it touches the bottom of the seabed, and the laying ship 2
is run in a direction across the laid cable 1. When this cutting grapnel 10 crosses the laid cable 1, the laid cable 1 is cut by the cable introducing body 20.
is introduced into the cable cutting section 30. Laying ship 2
As the cable progresses, the laid cable 1 is lifted up by the cutting grapnel 10. At this time, the support body 11 is pulled downward by the resistance of the stabilizing blades 19 and the weight of the laid cable 1, while the center rod 18 is pulled upward by the grapnel rope 3, so that the shear pin holes 13, 27 A shearing force acts on the shear pin 31 inserted into. When this shearing force reaches the breaking shearing force of the shear pin 31, the shear pin 31 is sheared. When the grapnel rope 3 is further pulled, a rotational force about the pivot shaft 21 acts on the laid cable 1 which is locked to the cable cutting part 30 through the center rod 18 and the crank rod 29, and the cutting blades 30a and 30b close, and the laid cable 1 is disconnected.

Here, as shown in FIG. 3, if the upward tension acting on the grapnel rope connecting hook 17 is Tg, the force T _p acting on the cable cutting portion 30 is given by the following equation (1).

T _p =l ₁ /l ₂ Tg... (1) On the other hand, in Fig. 7, the tension T _c that acts on the cable when pulling it up is given by the following equation (2), where θ is the angle that the installed cable 1 makes with the horizontal plane H. shown.

T _c Tg/2sinθ ...(2) Therefore, from equations (1) and (2), the tension acting on the cable T _c
can be expressed by the following equation (3).

T _c = T _p /2sinθ×l ₂ /l ₁ ... (3) If the tensile strength of the installed cable 1 is T, the shear strength is approximately T/3, so T _p = T/3. At this time, the installed cable 1 will be cut. Therefore, the expression
From (3), the cable tension T _c at the time of cutting can be expressed by the following equation (4).

T _c =T/6 sin θ×l ₂ /l ₁ (4) Since θ>30 in the general formula, sin θ>0.5. Therefore, from equation (4), as an example, l ₁ shown in FIG. 3,
If l ₂ is l ₂ /l ₁ =1/2, then T _c <1/6T. Therefore, by using the main cutting grapnel 10, the laid cable 1 can be cut with a cable tension of 1/6 or less of the tensile breaking tension of the laid cable 1.

If the laid cable 1 is cut using this cutting grapnel 10 and then the laid cable cut using the conventional probe grapnel 4 is lifted up, the cable will be stretched significantly compared to the conventional lifting method. curve B in Figure 2.
As shown in Figure 2, it is possible to suppress the elongation strain of the cable to be pulled up to less than the allowable elongation strain of 0.5%. Therefore, during salvage repair, it is possible to replace only the minimum cable section length necessary for cable repair.

In addition, as another example, the cable introduction body provided in the above example may be placed one side on the left and right with the stabilizing blade as the center plane.
A structure in which a total of two units are installed is also conceivable.

In addition, in the above embodiment, a shear pin was used as a locking member that locks the support body and rotating member until just before cutting the installed cable, but other structures may be used as long as they have the same effect. A locking member may also be employed.

As explained above, according to the submarine cable cutting grapnel according to the present invention, it is possible to easily cut the submarine cable after locating the submarine cable without applying a load to the cable. The elongation of the cable during salvage can be reduced, the length of the cable to be replaced during repair can be significantly reduced, and economical repair can be realized.

Furthermore, the present cut grapnel has a simple structure, is strong and reliable, and can be manufactured at low cost.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional lifting method, Fig. 2 is a diagram showing elongation strain of a laid cable, Figs. 3 and 4 show an embodiment of the present invention, and Fig. 3 is a side view. , FIG. 4 is a front view, FIG. 5 is a perspective view of a support constituting the submarine cable cutting grapnel according to the present invention, and FIGS. 6 a and b show rotating members constituting the cutting grapnel, FIG. 7 is an explanatory view of the cutting method using the submarine cable cutting grapnel according to the present invention. 11...Support, 11b...Lower end, 17...
Connection hook, 18... Center rod, 20... Rotating member, 21... Pivot, 24... Cable introducing body, 2
9...Crank bar, 30...Cable cutting part, 3
0a...first cutting blade, 30b...second cutting blade, 31...locking member (shear pin)

Claims (1)

[Claims] 1. A support body having a first cutting blade at the lower end, a second cutting blade facing the first cutting blade, and a cable introduction body continuous to the cutting blade, a rotating member rotatably supported at a lower end; a center rod slidably attached to the support along the support; and a grabnell rope connected to the upper end; and a crank rod connected to the rod and the rotating member, and when the support body and the rotating member are locked by a locking member, the first and second cutting blades are connected to the first and second cutting blades. A submarine cable cutting grapnel characterized in that a cable cutting section is formed by this.