JPH0326010B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an inner hard tube that can be penetrated by various types of wiring, and is configured by spirally winding a hard belt-like body made of hard resin; The present invention relates to a buried wire protection including a cladding tube formed by spirally winding a soft belt-like body made of a soft resin around the outer periphery of the inner hard tube.

[Conventional technology]

As a general buried wire protection pipe, for example,
As shown in Japanese Patent No. 53-65598, a structure in which the outside of a corrugated pipe made of hard resin is covered with a pipe made of soft resin is known.

In such buried cable protection pipes, the outside of the hard corrugated pipe is protected by a soft pipe, which is effective in terms of impact resistance and prevention of water intrusion from the outside into the protection pipe. However, since the corrugated pipe made of hard resin was simply configured with a corrugated cross section, if we tried to increase the wall thickness of the corrugated pipe to increase its flat compression strength, The disadvantage was that the flexibility and stretchability of the pipe itself was greatly impaired.

Therefore, in the past, as shown in Japanese Patent Publication No. 44-13065, for example, hard strips were wound spirally without being bonded to each other, and the side surfaces of adjacent hard strips were further wound. A layer of a soft band-like body is provided on the surface of the hard band-like body by welding or gluing, and a layer of a soft band-like body is integrally superimposed on the surface of the hard band-like body.

With this configuration, the hard strips are not bonded to each other and there are gaps between adjacent ones, so the thickness of the hard strips themselves can be increased to make them flat. Even if the strength is increased, stretchability and flexibility can be ensured to a certain extent, but the following problems arise depending on the size of the gap between the opposing sides of the adjacent hard strips. In other words, if the gap is small, the flexibility and elasticity of the buried wire protection tube are likely to be impaired, and only the soft band-like body covering the outside of the gap can expand and contract within the small gap. As a result, premature fatigue damage is likely to occur. On the other hand, if the gap is made sufficiently large to widen the range in which the elastic stretch action of the soft band-like body acts, the flexibility and stretchability of the buried wire protection tube will be considerably improved, but on the other hand,
The soft band-shaped body is easily deformed in the direction of diameter reduction due to the pressure of groundwater or earth and sand, and there is a risk of breakage at that point, and the inner hard tube may be bent or contracted while being deformed in the direction of diameter reduction. There was also a risk that the soft band-shaped body would be caught in the gap between the hard band-shaped bodies and be deformed and damaged.

[Problem to be solved by the invention]

The present invention is directed to spirally winding an inner hard tube with a hard strip in a non-adhesive state so that even if the inner hard tube has a high flat strength, it has sufficient flexibility and stretchability as a buried wire protection tube. The purpose of this is to avoid a reduction in durability due to early deterioration or damage to the cladding tube located outside the cladding tube.

[Means to solve the problem]

The technical means of the present invention taken to achieve the above object includes an inner hard tube configured by spirally winding a hard band made of hard resin, and a soft band made of soft resin around the outer periphery of the inner hard tube. In a buried wire protection tube comprising a cladding tube formed by spirally winding a cladding tube, [a] the hard band-shaped body is partially polymerized in a non-adhesive state between adjacent edges in the tube axis direction; At the same time, the overlapping surface is inclined with respect to the tube axis.

[B] The soft strip is positioned to cover the joint of the overlapping portion of the hard strip, and adjacent edges in the direction of the tube axis are integrally joined.

[C] The hard strip and the soft strip are brought into contact with each other in a non-adhesive state, or are partially fixed by adhesive or welding only in a part of the width of the soft strip in the tube axis direction. There is.

[d] The outer circumferential surface of the hard strip is provided with a protruding curved portion that bulges radially outward in a cross-sectional view along the tube axis direction, at a portion that contacts the inner circumferential surface of the soft strip.

It has the configurations described in [a] to [d] above.

[Effect]

The effects of the above technical measures are as follows.

The structure of [A] above enables relative movement of adjacent hard band parts in the axial direction, and therefore increases the wall thickness of the hard band to increase the flattening compression strength of the inner hard tube body. Even if you make it bigger,
Compared to simply bending or expanding and contracting a pipe-like tube with a corrugated cross section, it has far superior flexibility and elasticity. In other words, rather than bending the outer surface shape of each hard strip by greatly changing its shape in the radial or axial direction, the bending is done by changing the arrangement pitch of each hard strip. The internal stress is relatively small, and it is easy to bend and expand/contract.

From the configurations [A] and [B] above, the joints of the polymerized parts of the hard strips are covered with a soft resin cladding tube in a watertight manner, making it easy to prevent water from entering the inside of the buried wire protection tube, and In addition to being advantageous in terms of impact resistance, the edges of the hard strip overlap each other, and the overlapping surface is inclined,
Since the amount of displacement in the radial direction of the hard strip when the buried cable protection pipe is bent or expanded/contracted is small, it is easy to avoid partial deformation of the outer cladding pipe even if external pressure is applied. There is little risk of the outer soft band being pinched and damaged by the hard band.

With the configuration [C] above, it is possible to ensure as large an expansion and contraction range as possible in the axial direction of the soft resin cladding tube. In other words, if the soft strip forming the cladding tube is entirely adhered or welded to the outer circumferential surface of the hard strip, the range in which the elasticity of the soft strip acts against expansion and contraction in the axial direction is However, in the present invention, the soft strip is only in contact with the hard strip in a non-adhesive state.
Alternatively, since the flexible strip is bonded or welded only over a portion of its axial width, the range in which the elasticity of the flexible strip itself acts can be set as wide as possible.

Due to the configurations [C] and [D] above, the protruding curved portion of the outer circumferential surface of the hard strip acts as a resistance against movement in the axial direction of the soft strip that is in contact with it. As a result, the means for preventing the soft strip from slipping in the tube axis direction relative to the hard strip is completely unnecessary, or only requires fixing such as adhesion or welding in a small area. This allows the soft band-like body to freely expand and contract, thereby making it possible to set the elastic range of the soft band-like body as wide as possible.

〔Effect of the invention〕

The effects of the above action are as follows.

From the effect of ~ above, the flattening strength is large,
Although the buried cable protection pipe can prevent the intrusion of muddy water, etc., it can ensure sufficient stretchability and flexibility.

From the above effects, it is possible to avoid as much as possible damage to the soft strip due to deformation due to external pressure or being pinched by a hard strip, or deterioration due to repeated large deformations due to a small range of elastic expansion and contraction. can improve its durability.

From the above-mentioned effects, it is possible to prevent the positional shift of the soft strip in the axial direction with respect to the hard strip while making good use of the elastic expansion and contraction action of the soft strip, thereby achieving the intended function of the buried wire protection pipe. can be maintained.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

The hard strip 1 (made of hard synthetic resin, preferably hard vinyl chloride) is placed in a state where the hard strip parts 1a, 1a adjacent to each other in the axial direction partially overlap each other, and the hard strip Body part 1a, 1
The overlapping portions of the rigid strips 1 are in contact with each other in a non-adhesive state with their overlapping surfaces inclined with respect to the tube axis, and further, the edges of the rigid strips 1 are partially in contact with each other in a non-adhesive state. By polymerizing these, a cylindrical inner hard tube 2 is formed which is spirally turned in a state where it can be expanded, contracted and bent.

On the outside of this inner hard tube 2, there is provided a soft strip 3 (made of soft synthetic resin, especially soft chlorinated [preferably made of vinyl] are attached to the soft band-shaped body portions 3 adjacent to each other in the axial direction.
A cladding tube 4 which is wound spirally with the end edges of a and 3a integrally joined to each other and welded or bonded to the hard strip portion 1a only in a part of the width in the tube axis direction. has been established. Incidentally, both the strips 1 and 3 may simply be brought into contact with each other.

Further, the outer circumferential surface of the hard strip 1 is provided with a protruding curved portion that bulges radially outward in a cross-sectional view along the tube axis direction at a portion that contacts the inner circumferential surface of the soft strip 3.

The soft strip 3 is spirally wound so that one pitch of the strip portion 3a corresponds to one pitch of the strip portion 1a of the hard strip 1 by one pitch as shown in FIG. Alternatively, it may be spirally wound to accommodate multiple pitches as shown in FIG. In either case, it is preferable to wind the soft band parts 3a, 3a so that the joint edges of the soft band parts 3a, 3a are located at different positions in the axial direction with respect to the joints of the hard band parts 1a, 1a. 1
b is a wavy uneven strip formed on the inner surface of the hard strip 1 in order to prevent the inserted electric wire from slipping by abutment.

[Brief explanation of drawings]

The drawings show an embodiment of the buried wire protection tube according to the present invention, with FIG. 1 being a longitudinal sectional front view and FIG. 2 being a partial longitudinal sectional front view of another embodiment. 1... Hard band-shaped body, 1a... Band-shaped body part, 2...
...Inner hard tube, 3...Hard strip body, 3a...Soft strip body portion, 4...Coating tube.

Claims (1)

[Scope of Claims] 1. An inner hard tube 2 formed by spirally winding a hard band-like body 1 made of hard resin, and a soft band-like body 3 made of soft resin spirally wound around the outer periphery of the inner hard tube 2. A buried wire protection tube comprising a cladding tube 4 configured as follows: [a] The hard strip 1 has edges that are adjacent to each other in the tube axis direction partially overlapped with each other in a non-adhesive state. At the same time, the overlapping surface is inclined with respect to the tube axis. [B] The soft strip 3 is positioned to cover the joint of the overlapping portion of the hard strip 1, and
Adjacent edges in the direction of the tube axis are integrally joined. [C] The hard strip 1 and the soft strip 3 may be brought into contact with each other in a non-adhesive state, or may be partially bonded or welded only in a portion of the width of the soft strip 3 in the tube axis direction. It's stuck. [D] The outer circumferential surface of the hard strip 1 is provided with a protruding curved portion that bulges radially outward in a cross-sectional view along the tube axis direction, at a portion that contacts the inner circumferential surface of the soft strip 3. be. A buried wire protection pipe characterized by having the configuration described in [A] to [D] above.