JPS5916215A - Method of producing communication cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing highly reliable communication cables that can be applied to areas with large temperature changes and sloped areas.

Traditionally, polyethylene sheaths or aluminum-laminated polyethylene sheaths have been used to protect overhead cables from damage to the jacket caused by birds, insects, animals, gunshots, etc.
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=-= A so-called CS cable is used in which a polyethylene sheath is used, a corrugated steel tube (hereinafter referred to as C8) is provided on top of the sheath, and a moisture-proof mixture is applied and then coated with polyethylene.

By the way, the manufacturing of CS cable involves the process of assembling the cable cores, applying an internal polyethylene sheath, placing a steel tape vertically on the outer sheath of the internal sheath, butt-welding both ends, and then adding a spiral waveform. Manufacturing is carried out in two steps: forming a corrugated steel tube, coating the surface with a moisture-proofing compound, and covering the outer polyethylene sheath. Therefore, due to variations in the outer diameter of the inner polyethylene sheath and manufacturing errors in C8, a gap is created between the inner polyethylene sheath and C8, and the frictional resistance value between the gaps is extremely small.

Therefore, when a CS cable is installed in an area where temperature changes are large, such as an overhead section or a slope, a relative deviation between the internal polyethylene sheath and C8 tends to occur at the connection point, and in a metal cable, this deviation tends to occur. There are cases where line failures have occurred due to this. In addition, in optical cables, the internal polyethylene sheath and many of the structural members in the cable core are made of plastic materials, so the uniform linear expansion coefficient is much larger than that of C8. There was a drawback that relative deviations were likely to occur.

In order to eliminate the conventional drawbacks, the present invention provides a method for manufacturing a communication cable consisting of a cable core, an inner polyethylene sheath, a corrugated steel tube, a moisture-proof compound and an outer polyethylene sheath, after extruding the polyethylene of the inner sheath into the cable core. , the troughs of the corrugated steel tube are bitten into the polyethylene until the polyethylene cools, a moisture-proof mixture is applied to the surface of the corrugated steel tube, and the outer polyethylene sheath is further coated, the purpose of which is to Even if there is a variation in the outer diameter of the inner polyethylene sheath or a manufacturing error in C8, no gap is created between the inner polyethylene sheath and C8, and the frictional resistance value increases, so that it can be applied to areas with large temperature changes or sloped areas. In addition, the cable core can be manufactured without applying lateral pressure.

The present invention will be explained based on the drawings.

FIG. 1 is a partially cutaway perspective view of a corrugated steel tube stripped in steps from a communication cable manufactured by the manufacturing method of the present invention, and FIG. 2 is a partial vertical cross-section of FIG. 1.

In the figure, (1) shows the cable core, and (21) shows the C8 groove of the inner polypropylene sheath.

Manufacturing of the communication cable according to the present invention is carried out in the following order. First, after assembling the cable cores (1) and applying the inner sheath (2), while the polyethylene of the inner sheath (2) is not cooled, the valley of C8+31 bites into the inner sheath (2) and the inner sheath Select the root diameter of CS (31) and apply C3 (31) so that the C8 groove (22) of (2) is provided.

Thereafter, the moisture-proof mixture (5) is applied to the outer periphery of C3 (31) and covered with an external polyethylene sheath (4).

In the communication cable of the present invention manufactured in this way, the inner sheath 21 and the CS (31) are mechanically joined together, so that even if a relative movement force is applied in the longitudinal direction, the cable will not move. Completely preventable.

For example, in the case of a 0.65 mm 150 pair PEF-LAP-CS cable whose standard outer diameter of the inner sheath (2) is 35 mmφ, the outer diameter variation is 0.5 mm, and the accuracy of the valley diameter of CS (31) is 0.5 mm. Assuming 1 mm, C of the inner sheath
In order to design the groove 8 (22) to always have a depth of 0.1 mm or more, the diameter of the valley of C8 [31 may be set to 34.2 mm.

As explained above, in the manufacturing method of the present invention, after the polyethylene of the 111 inner sheath is extruded and coated, C8 is applied so that the valleys of C8 bite into the polyethylene of the inner sheath while the polyethylene is not cooled. It becomes possible to manufacture cables without receiving lateral pressure and without affecting the cable core.

(2) Since the inner sheath and C8 are mechanically joined together, there is no problem in removing C83 at the connection part, and by simply selecting the root diameter of C8 appropriately, the outer sheath can be Despite the diameter variation, the C8 groove of the inner sheath can be reliably provided in the longitudinal direction of the cable. (3) In the manufactured communication cable, the inner sheath and C8 are mechanically fitted, so there is no temperature change. It produces effects such as no relative deviation even in large areas or sloped areas.

[Brief explanation of drawings]

FIG. 2 shows a partial vertical sectional view of the communication cable of FIG. 1. Two cable cores 2: Internal polyethylene sheath 22: C8 groove of internal sheath 3: C84: External polyethylene sheath Patent applicant: Nippon Telegraph and Telephone Public Corporation representative, patent attorney Isao Abe

Claims (1)

[Claims] In a method of manufacturing a communication cable comprising a cable core, an inner polyethylene sheath, a corrugated steel tube, a moisture-proof compound, and an outer polyethylene sheath, after extruding the polyethylene of the inner sheath onto the cable core, the polyethylene is corrugated before cooling. A method for manufacturing a communication cable, characterized in that the troughs of the attached steel tube are bitten into the polyethylene.