JP2001189111A - Corrugated sheath cable and removal method of corrugated sheath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a cable core at a cable-connection position from extruding or drawing back from the terminal of a corrugated sheath due to vibrations and temperature changes, by increasing friction between the cable core of a corrugated sheath cable and the corrugated sheath, and to facilitate the work to remove a corrugated sheath at the cable terminal. SOLUTION: This corrugated sheath cable has a corrugated sheath 2 on the outside of a cable core 1. An intermediary plastic string 4, which has in the longitudinal direction with a certain interval, parts 4a with low tensile strength, for example, parts with smaller external diameter, and in which the external-diameter size of its ordinary parts 4b is larger than the gap size between the cable core 1 and the corrugated sheath 2, is attached longitudinally, or wound spirally on the cable core. The corrugated sheath 2 is arranged around the cable core with the plastic string, and part of wave ridges inside the corrugated sheath is thrusted into the ordinary parts 4b of the intermediary plastic string 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrugated sheath cable having a corrugated sheath outside a cable core and a method for removing the corrugated sheath.

[0002]

2. Description of the Related Art A corrugated sheath cable is made of aluminum, copper, or the like around a cable core containing an optical fiber core in a groove of a strength member having a spiral groove on the surface or a cable core in which insulated conductors are gathered. A metal tape made of steel or the like is longitudinally attached, rounded in the width direction, and both side edges are joined to form a pipe, and the pipe is subjected to spiral corrugation to form a corrugated sheath. It is used as a cable that can withstand large lateral pressure. Corrugated sheaths are sometimes referred to as corrugated sheaths or corrugated sheaths. In addition, an outer coating made of plastic such as polyethylene is often provided on the corrugated sheath in order to prevent corrosion of the metal tape for the corrugated sheath.

[0003] In addition to the corrugated sheath, the above-mentioned metal tape is longitudinally attached to a cable core and rolled in the width direction to form a pipe, and both side edges are joined to each other, and a metal pipe is extruded onto the cable core. They can also be manufactured by corrugating them. In addition, the corrugation may be a ring-shaped corrugation other than the spiral corrugation.

Further, since the surface of the cable core is pressed and wound with a plastic tape or the like, the outer diameter is not always uniform in the longitudinal direction and has a variation of about 0.5 mm to 1 mm. Also, its cross section is not perfectly circular,
May have a slightly collapsed oval shape. On the other hand, the corrugated sheath is made by rolling the vertically attached metal tape in the width direction and joining the two side edges to form a pipe, and corrugating the pipe with a corrugating device. Relatively uniform and circular in cross section. Normal,
The corrugated sheath cable is manufactured so that the inner diameter of the corrugated sheath is equal to or larger than the maximum outer diameter of the cable core so as not to damage the cable core at the time of corrugating.

Therefore, in the corrugated sheath cable,
A slight gap is likely to be formed in the longitudinal direction or a part of the circumferential direction between the outer surface of the cable core and the inner surface of the corrugated sheath. When this gap is large, the friction between the cable core and the corrugated sheath is reduced, and the cable core is easily slipped in the corrugated sheath. The frictional force between the cable core and the corrugated sheath in the corrugated sheath cable is smaller than the frictional force between the cable core and the outer coating in a cable in which a plastic outer coating is directly provided on the cable core.

Therefore, when the cable end is gripped from above the outer sheath or the corrugated sheath and the end is pulled and laid, if the caulking by the grip does not sufficiently reach the cable core, the pulling force is reduced by the outer sheath and the corrugated sheath. In some cases, the outer coating and the corrugated sheath extend in the longitudinal direction, and the cable core retracts from the end of the corrugated sheath.

Further, when the cable core is subjected to vibration or expansion and contraction due to a temperature change after the cable is laid, the cable core slides in the corrugated sheath in the longitudinal direction and moves, and the cable core is retracted from the end of the corrugated sheath at the cable connection point. It may protrude from the end. In order to prevent sliding movement between the corrugated sheath and the cable core, a polyethylene string having an outer diameter slightly larger than the gap between the cable core and the corrugated sheath is laid along the cable core, and a corrugated wire is provided outside the corrugated sheath. By providing a sheath, a corrugated sheath is brought into close contact with a polyethylene string so that a part of the corrugated sheath bites into the corrugated sheath, thereby increasing a frictional force between the cable core and the corrugated sheath.

[0008]

On the other hand, when cables are laid and the cables are connected to each other, it is necessary to peel off the outer coating and the corrugated sheath at the cable ends. In this case, first, the outer coating and the corrugated sheath are cut into sections at locations corresponding to the stripped length from the cable ends. Then, the external coating and the corrugated sheath on the terminal side are pulled out from the location by pulling in the terminal direction. In the case of a cable without a polyethylene string under the corrugated sheath, the corrugated sheath can be pulled out relatively easily by hand even if the stripping length is about 1 m. In this case, when the stripping length is as long as about 1 m, the friction between the corrugated sheath and the cable core is increased by the polyethylene string, so that the corrugated sheath cannot be easily pulled out by hand.

Therefore, in order to peel off the outer coating and the corrugated sheath on the terminal side from the round section, it is necessary to make a cut in the longitudinal direction and tear it vertically to peel off. 1m
The operation of making longitudinal cuts over the length of the object is tedious and can also damage the internal cable core. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and to provide a corrugated sheath cable and a corrugated sheath removing method in which the friction between the cable core and the corrugated sheath is increased and the corrugated sheath is easily pulled out. is there.

[0010]

A corrugated sheath cable according to the present invention is a corrugated sheath cable having a corrugated sheath outside a cable core, wherein an interposed plastic string is vertically attached or spirally wound on the cable core. A corrugated sheath is provided around,
The intervening plastic cord has relatively weak tensile strength portions at regular intervals in the longitudinal direction, and an outer diameter of a normal portion (a portion other than the relatively weak tensile strength portion) of the interposed plastic cord is the cable core. It is larger than the gap size between the wire and the corrugated sheath.

In the case of this corrugated sheath cable, at least a part of the corrugated portion inside the corrugated sheath penetrates into the interposed plastic cord, so that the frictional force between the corrugated sheath and the interposed plastic cord is larger than that of the cable core. Is greater than the frictional force between the wire and the intervening plastic string. Therefore, when the cable core attempts to move in the corrugated sheath, the intervening plastic string moves together with the corrugated sheath side. Utilizing this property, at the end of the corrugated sheath cable of the present invention, the case where the corrugated sheath is removed is as follows.

First, the corrugated sheath is cut into sections at a length where the corrugated sheath is to be removed from the terminal.
Then, the corrugated sheath on the terminal side is rotated around the axis of the cable from the round section. Then, the interposed plastic string inside the corrugated sheath on the terminal side is closely attached to the corrugated sheath and goes around the cable core together with the corrugated sheath, so that the interposed plastic string is pulled in the longitudinal direction near the round section. At this time, since a portion having relatively low tensile strength is formed in the intervening plastic string, the portion having low tensile strength near the round section is stretched and broken. When the intervening plastic cord is broken near the cross section and separated, when the corrugated sheath on the terminal side is pulled in the terminal direction, the interposed plastic cord inside the corrugated sheath also moves together with the corrugated sheath, so that the corrugated sheath on the terminal side is easily pulled out. I can do it.

[0013]

1A and 1B show a corrugated sheath cable according to an embodiment of the present invention.
FIG. 1A is a transverse sectional view, and FIG. 1B is a longitudinal sectional view.
FIG. 1C is a perspective view showing an example of an interposed plastic string used for the corrugated sheath cable of the present invention. In FIG. 1, 1 is a cable core, 2 is a corrugated sheath, 3 is an outer coating, 4 is an interposed plastic string,
a is a portion where the tensile strength is relatively weak, and 4b is a normal portion (a portion other than the portion where the tensile strength is relatively weak).

The cable core 1 may be a combination of optical fiber cores or an assembly of insulated conductors. For example, there are a cable core for an optical fiber cable in which an optical fiber core wire is accommodated in a groove of a strength member having a spiral groove on the surface, a cable core for a communication cable in which a large number of insulated conductors are assembled, and the like. These cable cores have an outer diameter of 15
It is about 35 mm to 35 mm, and its surface is usually held down with a plastic tape or the like.

Further, the corrugated sheath 2 is rounded in the width direction by vertically attaching a metal tape made of aluminum, copper, steel, or the like, and joining both side edges to form a pipe, and the pipe is formed with an eccentric ring or the like. Spiral corrugation is performed by a corrugation device having the following. The corrugated sheath is obtained by rolling a vertically attached metal tape in the width direction to form a pipe and joining both side edges, and extruding a metal pipe on a cable core with a metal extruder or the like and corrugating it. It can also be manufactured by processing. The corrugation may be a ring-shaped corrugation in addition to the spiral shape. The thickness of the metal tape is 0.3m
m to 1.5 mm are used, and the corrugation pitch is about 5 mm to 15 mm, and the corrugation depth is 1 mm to 4 m.
m.

The outer coating 3 is formed by extruding a plastic such as polyethylene on the corrugated sheath 2, but is not always necessary when the corrugated sheath 2 itself has excellent corrosion protection. Further, in the case of a cable which is directly buried under the ground, a further exterior may be provided outside the outer sheath 3.

In the corrugated sheath cable of the present invention,
An intervening plastic string 4 is vertically wound or helically wound around the cable core 1 to extend along the same. In the case of spiral winding, the spiral pitch is desirably about 300 mm or more in order to easily pull out the corrugated sheath. The intervening plastic cord 4 has a portion 4a having relatively low tensile strength at regular intervals in the longitudinal direction, that is, a portion that is easily broken when pulled in the longitudinal direction, and the other portion is outside the normal portion 4b. The diameter is uniform. The portion 4a of the intervening plastic string 4 shown in FIG. 1 where the tensile strength is weak has an outer diameter smaller than that of the normal portion 4b to reduce its cross-sectional area. It is desirable that the cross-sectional area of the portion 4a is about 1/2 to 1/4 of the cross-sectional area of the normal portion 4b.

The interval between the portions 4a having a low tensile strength is preferably not more than the corrugated spiral pitch of the corrugated sheath, so that the pitch is preferably about 10 mm to 20 mm. The intervening plastic cord 4 is made of a plastic such as polyethylene or nylon, and its normal portion 4b (the portion other than the portion 4a having a relatively low tensile strength).
Is slightly larger than the gap between the corrugated sheath and the cable core.

According to an experiment, in the case of a corrugated sheath cable having a length of 1 m, when the cable core and the corrugated sheath are pulled out from the corrugated sheath by pulling the cable core and the corrugated sheath in opposite directions, if the pulling force is larger than 980 N / m, the cable can be pulled out by hand. Have difficulty. On the other hand, if the pulling force is smaller than 653 N / m, the cable core moves in the corrugated sheath in cable laying or the like, and a phenomenon such as withdrawal or protrusion of the cable core occurs. Therefore, the pull-out force of the cable core of the 1 m long corrugated sheath cable is 653 N /
It is preferable to select the outer diameter of the normal portion 4b of the interposed plastic string so as to be not less than m and not more than 980 N / m.

The specific outer diameter of the intervening plastic string 4 is about 0.9 mm to 1.8 mm at the normal portion 4b. However, when a polyethylene interposed plastic string having a circular cross section is used, The outer diameter of the normal part can be determined. If placed along one intervening plastic cord 4 in the cable core 1, the inner diameter D ₂ of the outer diameter d and the corrugated sheath normal part of the intervening plastic straps 4, the relationship between the outer diameter D ₁ of the cable core, d = (D ₂ -D ₁ ) +0.
It is about 4 mm. In addition, in the circumferential direction 18 of the cable core,
When two intervening plastic cords, one each, are placed along a position separated by 0 degrees, d = (D ₂ −D ₁ ) /2+0.4 mm
Degree.

At the end of the corrugated sheath cable shown in FIGS. 1A and 1B, for example, when a corrugated sheath having a length of 1 m is removed, the following is performed. First, at a position 1 m from the terminal, the outer coating 3 and the corrugated sheath 2 are sliced. The round cutting operation is performed by moving the rotary blade so as to cut the outer coating 3 and the corrugated sheath 2 in the circumferential direction of the outer coating 3 while using a tool having the rotary blade so as not to damage the inner cable core.

Subsequently, the outer coating 3 on the terminal side is gripped by hand from the round section and rotated around the cable axis together with the corrugated sheath 2. Then, the intervening plastic cord 4 inside the corrugated sheath on the terminal side is closely attached to the corrugated sheath and goes around the cable core together with the corrugated sheath, so that the interposed plastic cord 4 is pulled in the longitudinal direction near the round section. At that time, the portion 4a having a low tensile strength near the cross section of the intervening plastic string 4 is
It is stretched and broken.

Next, the outer coating 3 on the terminal side is grasped and pulled in the terminal direction together with the corrugated sheath 2. Then,
Since the intervening plastic cord 4 on the terminal side also moves from the break point together with the outer coating 3 and the corrugated sheath 2, the outer coating and the corrugated sheath on the terminal side can be easily pulled out from the cable core 1.

FIGS. 2 and 3 show other examples of the interposed plastic cord used for the corrugated sheath cable of the present invention. FIG. 2 (A) is a perspective view, and FIG.
2B is a cross-sectional view in the X direction of FIG. 2A, and FIG.
FIG. 3A is a sectional view in the Y direction, FIG.
FIG. 3B is a cross-sectional view in the X direction of FIG. FIG. 2, FIG.
5, 5 and 6 are interposed plastic strings, 5a is a concave portion constituting a portion having relatively low tensile strength, 5b is a normal portion,
6a is a through-hole constituting a portion having a relatively low tensile strength,
6b is a normal part.

The intervening plastic string 5 shown in FIG.
A groove-shaped concave portion 5a is formed on both sides at intervals of about 20 mm to about 20 mm so that the outer diameter of the interposed plastic cord in one direction of the cross section becomes relatively weak in tensile strength. The material of the string, the sectional area of the portion 5a having a relatively low tensile strength, and the outer diameter of the normal portion 5b are shown in FIG.
It is not different from that shown in (C). In addition, the intervening plastic cord 6 shown in FIG. 3 has a plurality of through holes 6a perforated in one direction in the cross section of the intervening plastic cord at intervals of about 10 mm to 20 mm to be a portion having relatively low tensile strength. The material of the interposed plastic string, the cross-sectional area of the portion 6a having a relatively low tensile strength, and the outer diameter of the normal portion 6b are the same as those shown in FIG.

In the intervening plastic cord shown in FIGS. 1, 2 and 3, the normal portion has a circular cross section, but the cross section is not limited to a circle. Intermediate plastic strings such as polygons such as a quadrangular cross section and ellipses can also be used. In the case of a regular polygon, the maximum outer diameter is set to be larger than the gap between the corrugated sheath and the cable core. In the case of an elliptical shape, since the long side is along the cable core, it is necessary to determine the size of the intervening plastic string so that the short side dimension is larger than the gap dimension between the corrugated sheath and the cable core. is there.

[0027]

The corrugated sheath cable of the present invention
The cable core has a relatively weak portion of tensile strength at regular intervals in the longitudinal direction, and the outer diameter of the normal portion is vertically wrapped or spirally wound with an interposed plastic string larger than the gap between the cable core and the corrugated sheath. Since the corrugated sheath is provided around the corrugated sheath, the force of pulling out the corrugated sheath and the cable core is increased, and the cable core may be pulled in or protruded from the end of the corrugated sheath during or after installation. Never do.

Further, by cutting the corrugated sheath cable in the vicinity of the end of the corrugated cable and rotating the corrugated sheath on the terminal side about the axis of the cable from the cut portion, a relatively weak portion of the internal plastic string having a relatively low tensile strength is broken. Therefore, the corrugated sheath on the terminal side can be easily pulled out by hand.

[Brief description of the drawings]

1 (A) and 1 (B) are views showing an embodiment of a corrugated sheath cable of the present invention, wherein FIG. 1 (A) is a transverse sectional view and FIG. 1 (B) is a longitudinal sectional view. FIG. 1 (C)
FIG. 1 is a perspective view showing an example of an interposed plastic string used for a corrugated sheath cable of the present invention.

FIG. 2 shows another example of an interposed plastic string used for the corrugated sheath cable of the present invention,
(A) is a perspective view, (B) is a sectional view in the X direction, and (C) is a sectional view in the Y direction.

FIG. 3 shows another example of an interposed plastic string used for the corrugated sheath cable of the present invention,
(A) is a perspective view, (B) is an X-direction sectional view.

[Explanation of symbols]

1: Cable core 2: Corrugated sheath 3: Outer coating 4: Interposed plastic string 4a: Part having relatively low tensile strength 4b, 5b, 6b: Normal part (part other than part having relatively low tensile strength) 5, 6: Interposed plastic string 5a: recess (part with relatively low tensile strength) 6a: through hole (part with relatively low tensile strength)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigenori Takagi 1 Tayacho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Sumitomo Electric Industries Co., Ltd. Ki Kogyo Co., Ltd. Yokohama Works F-term (reference) 2H001 DD25 KK17 KK24 MM04 5G313 AB04 AC04 AC07 AD07 AE01 AE08

Claims (2)

[Claims] 1. A corrugated sheath cable having a corrugated sheath outside a cable core, wherein an interposed plastic string is vertically attached or spirally wound on the cable core, and a corrugated sheath is provided around the periphery thereof.
The intervening plastic cord has portions with relatively low tensile strength at regular intervals in the longitudinal direction, and the outer diameter of a normal portion (the portion other than the portion having relatively low tensile strength) of the interposed plastic cord is the same as that of the cable. A corrugated sheath cable which is larger than a gap between a core and the corrugated sheath. 2. A corrugated sheath cable in which an intervening plastic cord having a portion with relatively low tensile strength is longitudinally attached or spirally wound on a cable core at regular intervals in a longitudinal direction, and a corrugated sheath is provided outside thereof. In the vicinity of the terminal, the corrugated sheath is cut into round pieces, and the corrugated sheath on the terminal side is rotated around the axis of the cable from the cut section to extend and break the relatively weak portion of the interposed plastic string near the cut section. And removing the corrugated sheath on the terminal side by pulling the corrugated sheath toward the terminal side to expose the cable core.