JPS639952Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Technical Field of the Invention] The present invention relates to an electric cable made of a plurality of insulated wire cores assembled or twisted together, the outer periphery of which is wrapped with plastic tape, and the outer periphery of which is covered with a protective coating. [Technical background of the invention] Conventionally, for example, in communication cables, a method has been used to prevent the insulated wire cores from being fused to the outer periphery of a large number of insulated wire cores assembled or twisted together due to the heat generated when extruding a plastic protective coating. For the purpose of fixing a large number of insulated wire cores, it is often wrapped with plastic tape (hereinafter referred to as embossed tape) whose surface has been given many irregularities by embossing, and a protective coating of plastic is provided around the outer periphery. has been done. Furthermore, in order to prevent water from running along the insulated wire core in the event that the protective coating is damaged outdoors, a waterproof compound in the form of a jelly is filled between the insulated wire cores. [Problems with the Background Art] However, since the above-mentioned conventional embossed tape uses a plastic tape with good airtightness, after the embossed tape is wrapped, for example, water or the like may enter the gaps between the many insulated wire cores. If it remains, there is a risk that it will remain trapped within the protective covering and impair the electrical properties of the cable. In addition, when filling the gap between the insulated wire cores with waterproof compound and wrapping the embossed tape around it, and then applying a protective coating to the outer periphery, there is a possibility that an excessive amount of waterproof compound may be wrapped around the inside of the embossed tape. In such cases, there were problems in that the outer diameter of the cable exceeded a predetermined outer diameter, the outer diameter of the cable was uneven, and the waterproof compound dripped from the overlapped seams of the embossed tape. Furthermore, gaps are formed between the protective coating and the embossed tape due to the unevenness of the embossed tape.
There was also a risk that water might run through this gap. [Purpose of the invention] The present invention was made in order to eliminate such conventional drawbacks, and even after wrapping with embossed tape, there is good air permeability between the insulated wire core and the outside, and the waterproof compound is used in the insulated wire core. The purpose of the present invention is to provide an electrical cable that does not cause dripping of the waterproof compound or run of water between the protective coating and the embossed tape when filled between the embossed tape and the protective coating. [Summary of the invention] In other words, the electric cable of the invention consists of a large number of insulated wire cores assembled or twisted together, wrapped with plastic tape whose surface is embossed with many irregularities, and a protective tape is wrapped around the outer periphery of a large number of insulated wire cores assembled or twisted together. In the coated plastic tape, a through hole is formed at the top of the unevenness of the plastic tape. [Embodiments of the invention] The details of the invention will be described below with reference to the drawings. FIG. 1 is an enlarged sectional view of the embossed tape used in the present invention. As shown in Fig. 1, the embossed tape 1 used in the present invention is a plastic tape whose surface has been given a large number of unevenness by embossing (the figure shows an example of protrusion on only one side). A through hole 2 is bored at the top of the holder. As the plastic tape used for the embossed tape 1, a plastic tape with good heat resistance, such as high density polyethylene, nylon, or polyester, is suitable. Also, the thickness of the tape is 25~75μ, preferably 35~
55μ is suitable, and the maximum thickness (apparent thickness) between the unevenness after embossing is 150 to 500μ, preferably about 200 to 400μ. The shape of the unevenness imparted to the plastic tape by embossing can be, for example, a hexagonal shape, as shown in Fig. 2 a to c,
It may be circular, square, or any other repeating shape. In addition, the size of the through hole 2 formed at the top of the unevenness is preferably 0.314 mm ² (r≒0.3 mm) to allow sufficient gas permeation, and also to allow the waterproof compound to permeate. In order to achieve this, it is desirable that the thickness be 0.78 mm ² (r≈0.5 mm) or more. However, the size of through hole 2 is 3.14mm ² (r≒1mm)
If it is more than that, the mechanical properties such as tear strength and tensile strength of the plastic tape will deteriorate, which is not preferable. By the way, when polyethylene terephthalate tape is embossed (continuous tortoiseshell pattern) and holes are drilled on the top of the tape, the mechanical strength of the embossed tape changes depending on the size of the holes as shown in Table 1. This table also shows that in polyethylene terephthalate tape, the deterioration in properties is small up to a perforation area of 3.14 mm ² .

[Table] Figure 3 shows a communication cable according to an embodiment of the present invention. In the figure, a waterproof compound 5 is applied between the twisted cable cores 4, which are made by twisting a large number of insulated wire cores 3.
The embossed tape 1 shown in FIG. 1 is placed on the outer periphery of the embossed tape 1 with its edges overlapped. Further, a laminate tape 6 in which a plastic film is laminated on one side of an aluminum tape is wound around the outer periphery of the embossed tape 1, and the overlapped portion is heat-fused by the plastic film of the laminate tape 6. Further, a protective coating 7 made of extruded plastic such as polyethylene or soft vinyl chloride is applied to the outer periphery. In addition, in the above example, embossed tape 1
may be wound horizontally onto the cable core 4. In the embodiment of the present invention configured as described above, the through holes 2 are formed at the top of the unevenness of the embossed tape 1, so that when the embossed tape 1 is wound, excess waterproof compound, air, or other The volatile substances ooze out through the holes 2 of the embossed tape 1, resulting in a perfect cylindrical shape as a whole, and the voids inside disappear. Additionally, excess waterproofing compound oozes out through the numerous holes, so it does not drip from the overlapped seams of the embossed tape. Furthermore, if the through-holes are located only on the side that contacts the insulated wire core with the top facing the insulated wire core side, the waterproofing compound that has seeped out from the through-holes will accumulate in this gap, and between the embossed tape and the protective coating. (In this embodiment, the plastic film side of the laminate tape 6 faces the protective coating side and is fused together by the heat during extrusion, so water running between the laminate tape and the embossed tape is prevented.) It disappears. To manufacture such an electric cable, a large number of insulated wire cores 3 are twisted together using a conventional method, and then the cable cores are inserted into a waterproof compound heated to around 90 degrees Celsius. After filling the gap between the twisted insulated wire cores with waterproof compound, the embossed tape 1 is continuously placed vertically on the outer periphery, and then the laminated tape is placed vertically on top of this, and the overlapping part is heated and melted. A protective plastic coating is extruded around their outer peripheries. When the number of insulated wire cores is relatively small, the embossed tape 1 is wrapped around the cable core, and then inserted into a waterproof compound whose viscosity is lowered by heating. The waterproof compound may be filled in the twisting gap of the insulated wire core through the through hole 2 of the insulated wire core. Next, a specific example of the present invention will be explained. Table 2 shows that after filling the gaps between the twisted cable cores, which are made by twisting 400 pairs of foamed polyethylene insulated wire cores (30% foamed) with a conductor outer diameter of 0.5 mm, various embossed tapes 1 are applied vertically. These are the results of a water penetration test and a withstand voltage test of a communication cable manufactured by longitudinally fusion-bonding a laminate tape 6 around its outer periphery, and extruding and covering the outer periphery with a polyethylene protective coating.

[Table] In Table 2, Comparative Example 1 is a communication cable with the same configuration as the Example except that an embossed tape without perforated holes is used, and Comparative Example 2 is a communication cable in which embossed tape 1 of Comparative Example 1 is used instead of embossed tape. Comparative Examples 3 and 4, which use corrugated polyethylene terephthalate tape, are communication cables similarly made of nonwoven fabric and kraft paper, respectively, and are shown for comparison with the present invention. [Effects of the invention] As is clear from the above embodiments, the electric cable of the invention is made of a plastic material whose surface is embossed with many irregularities on the outer periphery of a large number of insulated wire cores assembled or twisted. Since the tape was wrapped, any moisture remaining in the gaps between the insulated wire cores will evaporate through the holes before the protective coating is extruded, and excess water will be removed from the waterproof compound filled in the gaps between the insulated wire cores. The water oozes out through the holes in the embossed tape, and the waterproof compound that oozes out over the entire surface of the embossed tape is present between the sheath and the sheath, resulting in an extremely high waterproofing effect. Finished in a perfectly round shape, there is no risk of appearance defects. In this case, if the holes are drilled only at the top of the embossed tape on the side that is in contact with the insulated wire core, the water permeability will further improve as the waterproof compound oozing from the insulated wire core will fill the gap. .

[Brief explanation of the drawing]

Fig. 1 is an enlarged sectional view showing an example of the embossed tape used in the present invention, Fig. 2 is an explanatory view showing an example of the uneven shape of the embossed tape, and Fig. 3 is a perspective view showing an example of the present invention. It is. DESCRIPTION OF SYMBOLS 1... Embossed tape, 2... Through-hole, 3... Insulated wire core, 4... Cable wire core, 5... Waterproof compound, 6... Laminated tape, 7... Protective coating.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. A plastic tape whose surface has been given many irregularities by embossing is wrapped around the outer periphery of a large number of insulated wire cores assembled or twisted, and a protective coating is applied to the outer periphery. An electric cable characterized in that a through hole is formed at the top of the unevenness of the plastic tape. 2. The electric cable according to claim 1 of the utility model registration claim, characterized in that a waterproof compound is filled in the gaps between the set or twisted insulated wire cores. 3. The electric cable according to claim 1 of the utility model registration, characterized in that a through hole is formed only at the top of the plastic tape on the side that contacts the insulated wire core.