JPH0447539B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a plastic pipe composite with a tension member.

This plastic pipe composite is primarily used for split pipes.

Therefore, the case where it is used as a split pipe will be explained below.

[About the split pipe] The split pipe is a 75mm pipe that is already buried underground.
φ, 100mmφ, 130mmφ, etc. A small diameter conduit in which 3 to 7 pipes are laid in advance in order to make effective use of the conduit, so that many small diameter optical cables etc. can be laid. used for.

PE, PVC, etc. are used as the material.

As shown in Figure 2, the structure is, for example, an inner diameter of 20 mm,
In the hollow part 18 of the pipe body 12 with an outer diameter of 24 mm,
A seine net 14 is inserted. This dragnet 14
is for connecting the optical cable later. Note that 10 is the entire divided pipe line.

However, if the material and thickness of the split pipe line 10 are appropriately selected, the seine net 14 can be stretched over a certain distance (150~
Approximately 200m (varies slightly due to route bends, etc.) can be inserted later.

In that case, the dragnet 14 is not necessary.

The present invention relates to a split pipe (plastic pipe complex) without a dragnet 14.

[Prior art and problems] (1) Split pipe 10 and tension member 16: When installing the split pipe 10, more tension than expected is applied, and if it is made of plastic, a large residual stress remains in itself. .

The residual stress will be released over a long period of time, but for example, there is a case where a 200 m long PE pipe was retracted by about 30 cm at the mouth of a manhole after six months.

Therefore, it is natural to consider adding a tension member.

(2) Advantages of including tension members: High tensile strength and bottom elongation.

It has straightness. In other words, the straightness of the divided pipe itself is maintained even if it is unwound from the drum.

The temperature elasticity is reduced by an order of magnitude compared to the case without the tension member.

(3) Problem: Normally, a tension member is required, but since the wall thickness of the divided pipe line 10 is thin, a plurality of tension members are required.

In order to arrange the tension member within the wall of the pipe body 12, the wall thickness of that portion must be made slightly thicker.

At this time, as shown in FIGS. 3 to 5, when the tension members 16 are arranged on one diameter or on two orthogonal diameters, the wall thickness increases over the entire circumference.

In the case of split pipes, the important point is how much the inner diameter can be increased with respect to the limited outer diameter, and from this point of view it is unsatisfactory.

In addition, in the case of FIG. 4, the bending rigidity is even greater, which causes problems when laying the cable around a bend.

[Means for Solving the Problems] As shown in FIG.
(2) The centers of each tension member 16 are on the same plane, (3) and the plane 20 does not pass through the center of the hollow part 18, and (4) the hollow part 18 is The above problem is solved by making the center of the pipe eccentric from the center of the pipe body 12 to the side opposite to the side where the tension member 16 is buried.

[Explanation] (1) The tension member 16 having straightness means that fibrous materials such as Kevlar (trade name) are excluded.

(2) the plane 20 does not pass through the center of the hollow portion 18;
For example, in the case of FIG. 5, the four tension members 16 are on the same plane, but the plane passing through their centers does not include the center 18 of the hollow part. , it means.

[Embodiment] As shown in FIG. 1, within the pipe body 12, the hollow portion 18 is eccentrically made to have a thicker wall on one side, and for example, four tension members 16 are embedded in that portion.

Each tension member 16 is centered on the same plane 2
0, and its plane 20 does not pass through the center of the hollow portion 18 but through the inside of the pipe body 12.

19 is a rib. When winding the split pipe line 10 around a drum, it is easier to wind the drum with the side containing the tension member 16 facing inside. However, the tension member 16 is not visible from the outside. So, for example,
A rib 19 is attached to the opposite side of the tension member 16 to serve as a mark when winding.

For reference, the numbers in this case are as follows: The outer diameter of the pipe body 12 is 36 mm, the inner diameter is 30 mm, and the hollow part 1
The eccentricity (distance between ○○') of 8 is 1 mm, and all four tension members 16 are galvanized steel wires with a diameter of 1.6 mm, and the spacing between them is 4.45 mm.

[Effect of the invention] The centers of the plurality of tension members 16 are on the same plane, and the plane 20 is located on the hollow portion 18.
does not pass through the center, and the center of the hollow portion 18 is eccentric from the center of the pipe body 12 to the side opposite to the side where the tension member 16 is buried. By burying a tension member in the bent part, the wall thickness on the opposite side can be made considerably thinner (the tension member is not buried, and the tension member takes charge of the tension), so the outer diameter is limited. The inner diameter can be greatly increased.

(2) Since the centers of each tension member 16 are on the same plane, when there are three or more tension members, the bending rigidity is lower than in the case shown in Fig. 4, and it is difficult to install the cable around a bend. There is no problem.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, FIG. 2 is a general explanatory diagram of a divided pipe line, and FIGS. 3, 4, and 5 are explanatory diagrams of different conventional techniques. 10...Divided pipe line, 12...Pipe body, 14
...Seine net, 16...Tension member, 18...
...Hollow part, 19...Rib, 20...Flat surface.

Claims (1)

[Claims] 1. In a plastic pipe composite in which tension members 16 having straightness are embedded, there are a plurality of tension members 16, and the center of each tension member 16 is on the same plane, Further, the plane 20 does not pass through the center of the hollow portion 18, and the center of the hollow portion 18 is eccentric from the center of the pipe body 12 to the side opposite to the side where the tension member 16 is buried. A plastic pipe complex.