JPH0687615B2 - Direct buried cable protection method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of laying a cable in a straight line, that is, a method for laying a so-called direct-embedded cable, and more particularly to a method for protecting the directly-embedded cable.

[Prior art and its problems]

Conventionally, a communication cable or the like is directly buried by inserting a cable a into a cable trough T or a fume tube shown in FIG. In this burying method, the cable trough T and the fume tube are heavy in terms of work.

Further, Japanese Utility Model Publication No. 52-9599 discloses a technique in which a protective tube through which a cable a is passed is divided into two parts in a plane in the length direction. In this technique, since the split cylinder (half-split cylinder) is made into two pieces, there is a possibility that the fitting may come off. If it comes off, if dirt or the like enters or if an external force is applied, the edge of the split cylinder may hit the cable a and be damaged, so that it does not serve the role of protection.

In view of the above points, an object of the present invention is to prevent disconnection of the divided pipe as much as possible when protecting the cable with the divided pipe.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, in the present invention, when the cable is embedded in a straight line, the plastics pipe is divided into two in a plane in the longitudinal direction as a circular cross section, and the cross section of one of the divided cylinders. The center angle of the arc is more than 180 degrees and 240 degrees or less, and dovetail grooves or mortises are formed on one side of the inner surface of both split edges of the split tube, and the entire outer surface of both split edges of the other split tube is formed. After forming the dovetail or dovetail that fits into the dovetail groove or dovetail of one of the above-mentioned divided cylinders, connect one of the divided cylinders in the required length direction and put the cable in it. The other end is covered so that its one end does not overlap the one end, and is integrally connected through the dovetail groove and the dovetail joint to embed it.

The reason why the sectional arc center angle of the above-mentioned split cylinder is more than 180 degrees and 240 degrees or less is that if the split cylinders have a bending difference of 180 degrees, and if they exceed 240 degrees, the center angle of the other is This is because the binding force becomes too small and the angle becomes
Select appropriately considering the pipe diameter and its thickness.

[Action]

In the protection method according to the present invention having such a configuration, the cable is inserted into one of the split tubes and the other is fitted. This fit is
Since the dovetail groove and dovetail are formed on the inner surface of the dividing edge and on the outer surface of the dividing edge on the one side, one dividing edge covers the other dividing edge.

Therefore, when an inward external force is applied to the pipe, the center angle of the arc of the cross section exceeds 180 degrees, and it tends to bend compared to the other split cylinder, so it tries to bend largely inward, but the other split cylinder is not so much. It does not tend to flex, which makes the dovetail and dovetail fit more firmly.

By the way, if the dovetail groove and dovetail are formed with one split tube with a large central angle on the outer surface of the split edge and the other split tube on the inner surface of the split edge, the mating will be weakened when an inward external force is applied. The divided cylinder bends so that it does.

Further, since the connected divided cylinders are fitted so that their ends do not overlap with each other, they are surely integrated and become like a single pipe. On the other hand, if a split tube is damaged, replace it only.

〔Example〕

First, the plastics pipe A will be described. As shown in FIGS. 2 and 3, the pipe A has a sectional cylinder 1a having a central angle θ _{1 of} 210 degrees and a thickness t of 4 mm and a sectional circular arc 1 a. It is composed of a split cylinder 1b having a central angle θ ₂ : 150 degrees and a thickness t: 4 mm, and a dovetail groove 2a is formed over the entire length on the inner surface of the split edge of the former split cylinder 1a, and the latter split cylinder 1b is formed. Dovetails 2b are formed on the outer surface of the dividing edge over the entire length thereof, and these are extruded to a required length by hard vinyl chloride. This length is appropriately determined in consideration of ease of transportation and the like.

The dovetail groove 2a and the dovetail 2b may be formed such that the former 2a is formed in the divided cylinder 1b and the latter 2b is formed in the divided cylinder 1a.
You may make it form one by one in 1b.

Next, the work of covering the directly buried cable and its rising portion with this plastics pipe A will be described.

First, as shown in FIG. 1 (a), a cable a is guided along a telephone pole H, and an embedded portion (short in the drawing, but over the entire embedded portion) of the cable a and its rising portion 2 are introduced.
After connecting the required number of one split cylinder 1a or 1b to the length of ~ 3m and inserting the cable a therein, fit the split cylinders 1a and 1b in a staggered manner so that their ends do not overlap. Turn into. Tube A
Both ends 1a ', 1b' of the divided pipes 1a, 1b are appropriately cut into, for example, a half module for use.

At this time, it is preferable to cover the rising bent portion of the cable a with the elbow B. It is preferable that the elbow B can also be divided into two. For example, as shown in FIGS. 4 (a) and 4 (b), a mortise 4a and a mortise hole 4b are provided at required positions on the outer circumference of the half-split cylinders 3a and 3b, and both halves 4a and 4b are fitted to each other, thereby The elbow B can be formed by connecting the tubes 3a and 3b. Further, as shown in FIG. 6 (a), the concave portions 5a and I having a U-shaped cross section are formed.
Strip 5 made of hard vinyl chloride with a series of character-shaped inserts 5b
While spirally winding, as shown in FIG. 5, it is assumed that the insertion portion 5b is fitted in the recessed portion 5a, or the strip 5 is not spirally wound, but has an annular shape as shown in FIG. 6 (b), If the ring is made to fit continuously in the axial direction so as to have flexibility, any degree of bending can be dealt with.

The cable a covered with the plastics pipe A and the elbow B as described above is tightened with the steel band C via the bolt d as shown in FIGS. A sealing e such as a rubber bushing is attached to both ends to be embedded. At the time of tightening, a steel band C is provided at the joint (joint portion) of the split cylinders 1a and 1b and the elbow B (however, it is omitted in the drawings). [Advantages of the Invention] The present invention is as described above. Both split cylinders are fitted with a dovetail groove and a dovetail, one split cylinder is formed on the inner surface of the split edge, and the other split cylinder is formed on the outer surface of the split edge. The other division edge is covered. For this reason, when an inward external force is applied to the pipe, one of the split cylinders has a cross-sectional arc center angle of more than 180 degrees, and is easily bent compared to the other split cylinder, so that it is largely bent inward. However, the other split cylinder does not tend to bend so much, and the dovetail groove and the dovetail dovetail joint become more solid, and the cable is reliably protected.

Further, since the end portions of the connected divided cylinders do not overlap with each other, they are like a single pipe and are unlikely to come off, which also ensures the above protection. Further, even if the split cylinder is damaged, it is only necessary to replace it.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) is a schematic view of an embodiment of a method for protecting an embedded cable according to the present invention, and FIG. 1 (b) is a cutaway plan view of FIG. 2 (a) and 2 (b) are a front view and a plan view of the plastics tube of the same embodiment, and FIGS. 3 (a) and 3 (b) are a side view and a side view of each divided cylinder of the plastics tube. (A),
(B) is a front view and a sectional view of the elbow of the same embodiment, FIG. 5 is a partial perspective view of another example of the elbow, and FIGS. 6 (a) and 6 (b) are manufacturing explanatory views of the other example. FIG. 7 is a perspective view of a conventional example. A ... Plastic tube, B ... Elbow, C ... Steel band, H ... Pole, a ... Cable, θ ₁ , θ ₂ …… Cross section center angle, 1a, 1b …… Split tube, 2a… … Dovetail, 2b… Dovetail mortise, 3a, 3b… Cylinder, 4a… Mortise, 4b… Mortise, 5… Article, 5a… Recess, 5b… Insert.

Claims (1)

[Claims] 1. When burying a cable a in a straight line, the plastics pipe A is divided into two parts in a lengthwise direction as a circular cross section, and a sectional arc central angle θ _{1 of} one of the divided cylinders 1a.
Over 180 degrees and 240 degrees or less, and while forming the dovetail groove 2a or dovetail over the entire length of both split edges of one of the split cylinders 1a, the entire length of both split edge outer surfaces of the other split cylinder 1b. It is assumed that the dovetail groove 2a or the dovetail groove 2b or the dovetail groove that fits into the dovetail groove is formed on one of the divided pipes 1a, and one of the divided pipes 1a and 1b is connected in the required length direction and After inserting the electric wire a, cover the other end so that its end does not overlap with one end, and integrally couple the dovetail groove 2a and the dovetail mortise 2b with each other by embedding it. A method for protecting a direct-embedded cable characterized by.