JP3373692B2 - Cable spacer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a cable spacer for accommodating a communication transmission medium such as an optical fiber or an electric cable of copper or the like.

[0002]

2. Description of the Related Art As a cable spacer, for example, "Sumitomo Electric" No. 1 issued by Sumitomo Electric Industries, Ltd. in September 1987
31 No. are described in 1-5 pp, as particularly shown in 1, right column, to 2, left column and FIG. 1 (b), the central strength member (F
It is general that the outer periphery of (RP is shown) is coated with a high elastic modulus thermoplastic material such as polyethylene and a spiral groove is formed around the polyethylene . In addition, JP-A-61-2
Japanese Patent No. 75708 (Japanese Patent Publication No. 2-15845) discloses a material layer having a compression elastic modulus smaller than that of a material (for example, aluminum) of a peripheral portion in order to improve external force and reduce the weight of a flexible cable. (Eg high density polyethylene)
It has been proposed to place the underlayer of the spiral groove.

[0003]

As described above, the conventional cable spacer is formed by extruding ordinary polyethylene around the central strength member and forming the groove for accommodating the transmission medium in the outermost layer thereof. FIG. 3 is a schematic view showing the structure of a conventional cable spacer. In FIG. 3, reference numeral 1 is a central strength member, and 2 is a high elastic modulus thermoplastic material layer having a transmission medium accommodating groove 4.

Depending on the thickness of the spacer, the extrusion coating of the high-strength thermoplastic material on the upper layer of the central tensile strength body may be performed only once, and the thick spacer and the central tensile strength body such as steel wire may be combined with each other. When it is necessary to increase the adhesiveness, a processing method has been taken in which the groove is formed continuously or discontinuously through the extruder in several times. Further, even when the extrusion is carried out several times, a material having exactly the same or substantially the same elastic coefficient is used.

For this reason, when the diameter of the spacer increases, the moment of inertia of area of the spacer increases, the bending rigidity increases, and there is a problem that the flexibility of the spacer; As a method for solving this, the technique described in JP-A-61-275708 can be mentioned. The spacer described in the embodiment is shown in FIG.
As for high-density polyethylene <br/> the aluminum outer peripheral portion 3 having a groove not integrated and low modulus section 2 is centered tension member 1, always both of the outer peripheral portion 3 and the central strength member 1 at the end There was a problem that it was necessary to hold it.

[0006]

As a result of various studies on the above-mentioned problems, the inventor of the present invention, as a covering layer , suppresses the deformation of the outermost layer of the spacer, which is caused by the lateral pressure applied during cable laying, in the groove. High density to protect the transmission medium of
Degree polyethylene high elastic modulus material layer (a) , further,
In order to suppress the bending rigidity of the spacer low, foamed polyethylene low modulus materials layer between the central tension member and the outermost layer (a)
It was found that the flexibility of the spacer can be improved and the workability of the laying work can be improved by arranging (b) and integrating them, and completed the present invention.

That is, the present invention is:
Covered aroundlayerAndOf the coating layerCommunication transmission medium on the outer surface
In a cable spacer with a groove to store the body,
TheCoating layerConstitutes the grooveHigh density polyethyleneOutermost layer
(a) andBetween the outermost layer and the central tensile memberThereOutermost
Has a lower elastic modulus than the layersFoamed polyethyleneLow modulusMaterialFee
layerconsists of (b), Central tensile body and the low elastic modulusMaterialMaterial(b)
And the outermost layer(b)Is a cable spacer that is integrated with
I will provide a. Also, low elastic modulusMaterialMaterial(b)And the outermost layer
(a)Is also characterized in that they are compatibilized by applying heat
Have. Also,   Central tensile body and low elastic modulusMaterialMaterial
(b)Another feature is that an adhesive layer is provided between and.

The present invention will be specifically described below with reference to the drawings. FIG. 1 is one schematic view showing the structure of the cable spacer of the present invention. In FIG. 1, 1 is a central strength member, and 2 is a groove having the outermost layer of the spacer.
It is a high-density polyethylene high-modulus material layer (a) , which suppresses deformation due to lateral pressure applied during cable laying and protects the inside of the transmission medium accommodating groove 4. 3 is the height of the outermost layer
A foamed polyethylene low modulus materials layer arranged between density polyethylene high modulus materials layer 2 and the central strength member 1 (b), which fulfills the function of suppressing the bending stiffness of the spacer.

The central strength member 1 is not particularly limited as long as it is a highly rigid material, and examples thereof include FRP and steel wire having rigidity such as aramid fiber reinforced plastic.
The use of steel wire is common. High modulus materials layer 2 is a need to use high-density polyethylene, high modulus heat-friendly plastic
As the material, low Young's modulus PVC, PVC, nylon, PBT, polycarbonate, etc. can be used .

[0010] Then, high modulus materials which constitute the outermost layer 2 is to protect the transmission medium in the groove 4, high density polyethylene
It is necessary to use an ethylene high elastic modulus material, for example, Young's modulus of about 500 N / mm ² or more, preferably 600 to 1
000 N / mm ² , more preferably 1000 to 2600 N
/ Mm ² of high density polyethylene and high modulus materials can be used. Further, high-density polyethylene high modulus materials layer 2, in order to suppress deformation of the groove 4 by the lateral pressure, the thickness from the groove bottom 0.5mm or more, preferably 0.7~2mm
It is safe in terms of design to make it around. Furthermore, in order to configure a transmission medium accommodating groove 4, the upper layer of the outermost layer 2 made of high density polyethylene and high modulus materials, previously easy other materials of the molding, for example by a rigid rigid member with such as aluminum molded advance, it can be facilitated by integrally bonded high density polyethylene <br/> high modulus materials layer 2 with an adhesive or the like. Further, in order to sufficiently absorb the shock applied to the transmission medium, the groove 4 can be separated into groove forming members so that the groove can move freely to some extent.

Next, in the present invention, the outermost layer is formed.
The outermost layer is formed on the lower layer of the high- density polyethylene high elastic modulus material layer 2.
A foamed polyethylene low elastic modulus material layer 3 having a lower elastic modulus than the layer is arranged. Low modulus material layer 3 is foamed polyethylene, preferably may be mentioned high polyethylene foam 50% degree of foaming. Polyethylene foam When extruding and foaming a low elastic modulus material layer , the foaming agent used is a physical foaming agent with an inert gas such as nitrogen gas, argon gas , carbon dioxide, or a chemical foaming agent with a decomposable agent such as azodicarbonamide. Agents may be mentioned, but the use of nitrogen gas is preferred. Further, as the foamed polyethylene low elastic modulus material layer 3, it is necessary to basically use one having a low elastic modulus in view of easiness of construction work. For example, Young's modulus of about 400 N / mm
² or less, preferably 100~300N / mm ^2, more preferably it is possible to use a material, 10 to 100 N / mm ^2.

Further, the foamed polyethylene low elastic modulus material layer 3
It is important that can be bonded to the central tensile strength body 1 from the viewpoint of material and manufacturing conditions such as processing temperature. FIG. 2 is another schematic view showing the structure of the cable spacer of the present invention. In FIG. 2, an adhesive layer 5 may be interposed between the expanded polyethylene low elastic modulus material layer 3 and the central tensile strength body 1. The central tension member 1 and the foamed polyethylene low modulus material layer 3, or directly as shown in Figure 1. Figure 2
As shown in (4), they are integrated via an appropriate adhesive layer 5 .

As the adhesive layer 5, the central tensile member 1 and foam
There is no particular limitation as long as it exhibits adhesiveness to both the polyethylene low elastic modulus material layer 3, and examples thereof include adhesive polyethylene (polyethylene wax, polyethylene oxide, etc.). Since the contribution of the second moment of area, which is an index of the bending rigidity of the spacer, is proportional to the square of the distance from the center axis of bending and the elastic modulus in material engineering, the low elastic modulus material layer 3 has a low Young's modulus and an outer circumference. It is preferable to be placed at a position close to. That is, the adhesive layer 5 is provided at a position close to the outer layer portion.
Is not desirable because the effect of reducing bending rigidity is reduced.

Further, expanded polyethylene low elastic modulus material layer 3
And of high density polyethylene and high modulus materials layer 2 outermost in direct contact, the both of which are required to be a material which readily compatibilized by the addition of heat from one another. When manufacturing cable spacers, the outermost layer is high density polyethylene.
Both the emission and high modulus materials during extrusion is being integrated. This both, the use of the material of the same series to compatibilization is desirable, a combination of high density polyethylene and foamed polyethylene.

[0015]

The present invention will be described in more detail with reference to FIG.
These do not limit the scope of the invention. A cable spacer as shown in FIG. 2 was manufactured. That is, the spacer diameter is 24.0 mm, and the central tensile strength body 1 is formed by twisting seven 2.0φ steel wires. An adhesive layer 5 of tacky polyethylene having a thickness of 1 mm was applied on the central strength member. This adhesive layer 5 is made of foam poly on the steel stranded wire, which is the central tensile member 1.
And having been subjected to supplemental because it is difficult to apply the ethylene low modulus materials layer 3 directly adhered good, the material of the central strength members 1, for example made of resin such as FRP, originating
Especially if you select good adhesiveness and foam polyethylene low modulus materials layer 3 may not be provided an adhesive layer 5.

A highly expanded polyethylene having a thickness of 3.2 mm and a degree of expansion of 50% is extruded on the central tensile member 1 to obtain a foamed poly
And ethylene low modulus materials layer 3. Since foamed polyethylene generally has a high degree of foaming on the outer periphery, extrusion foaming may be extruded in several times to form a highly foamed polyethylene layer. A foamed polyethylene layer was formed using nitrogen gas as a foaming agent.

[0017] Next, a spacer cable is subjected to high-density polyethylene outermost layer 2 was formed a groove 4 on the rod-like central strength member 1 was sized up to an outer diameter 14.4Mmfai. In this case, since using the high-density polyethylene as the high modulus materials layer 2 having a groove, as the taking into account both the compatibility (adhesion) low elastic modulus materials layer 3, the foam of high density polyethylene and homogeneous Polyethylene was used. If there is no problem in the compatibility (adhesiveness), a foaming material such as low Young's modulus grade PVC or vinyl chloride may be used.

As a comparative example, a cable spacer was manufactured by using the same high- density polyethylene as the outermost layer 2 of high-density polyethylene instead of expanded polyethylene as the intermediate layer. In this way, the two types of samples cut to 1 m length were bent by the workers, and the ones that were easy to bend were pointed out. As a result, 15 out of 17 workers were able to flex the cable spacer according to the present invention. It was pointed out that it has flexibility and is easy to bend. In addition, the two types of samples were cantilevered with a length of 1 mm, and the amount of bending was measured by applying a weight to the free end.
The invention product showed a 12% increase in the amount of deflection.

[0019]

As described above, the cable spacer of the present invention has a high strength as a coating layer around the central strength member.
Outermost layer of density polyethylene (a) and outermost layer and central tensile strength
Foamed polyethylene low modulus material layer between the body (b)
Since it is possible to improve the flexibility,
Moreover, since the entire spacer is integrated, the gripping at the end may be performed only on the central tensile member. In addition, the workability of laying work is improved. Therefore, it is particularly useful for a large-diameter spacer in which the spacer has poor flexibility.

[Brief description of drawings]

FIG. 1 is a schematic view showing the structure of a cable spacer of the present invention.

FIG. 2 is another schematic view showing the structure of the cable spacer of the present invention.

FIG. 3 is a schematic view showing a structure of a conventional cable spacer.

[Explanation of symbols]

High modulus thermoplastic material layer 3 foamed polyethylene low modulus material layer 4 transmission media storage groove 5 adhesive layer having a high density polyethylene high modulus materials outermost layer 2 'groove having a first central strength member 2 grooves

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yo Nishimura 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd. Yokohama Works (72) Nobumasa Nirazawa 1-tani, Saya-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industrial Co., Ltd. Yokohama Works (72) Inventor Takashi Saito 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Hideyuki Iwata 1-6, Uchisai-cho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation Telephone Corporation (56) Reference JP-A 64-78203 (JP, A) JP-A 8-146263 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02B 6 / 44

Claims (3)

(57) [Claims] 1. A subjected to the coating layer around a central strength member, said
In cable spacer having a groove for accommodating the communication transmitting medium to the outer circumferential surface of the coating layer, the coating layer is provided between the high-density polyethylene outermost layer (a) and the outermost layer and the central strength member constituting a groove having a low modulus of elasticity than said outermost there
It consists foamed polyethylene low modulus materials layer (b), the central strength member and the low elastic modulus materials layer (b) a cable spacer, characterized in that it is integrated with the said outermost layer (a) . 2. A low elastic modulus materials layer (b) and the outermost layer (a) a cable spacer of claim 1, wherein the compatibilizing by applying heat. 3. A central strength member and the claim 1 or 2, wherein the spacer cable and providing a bonding layer between the low modulus materials layer (b).