JPS6349058Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention mainly relates to a synthetic resin flexible tube for protecting electric wires buried underground or in the ceiling, floor, or wall of a building.

By the way, iron pipes have traditionally been used as electrical conduits for wiring, but although they have the advantages of being strong and rigid, they are also heavy and difficult to connect and bend, so in recent years hard chlorinated pipes have been used. Synthetic resin pipes such as vinyl pipes are used. However, although this synthetic resin pipe is lightweight and has excellent corrosion resistance, it is weak in impact resistance and requires a lot of effort to bend. Further improvements have been made and corrugated pipes, which have bellows-like irregularities on the inner and outer surfaces of synthetic resin pipes, have come into use for the purpose of making them more flexible. Because they are extremely large, they have low tensile strength, which causes them to expand or contract unexpectedly during burying work, or to bend during concrete pouring, making the installation work time-consuming.

Therefore, this corrugated tube with unevenness on the inner and outer surfaces is used as the inner tube, and the outer tube is made of a soft synthetic resin with a smooth outer surface and a corrugated inner surface corresponding to the external waveform of the inner tube. A synthetic resin flexible tube has been proposed that is made of a double tube that has cushioning properties by fitting the inner surface peaks of the outer tube into the valleys of the inner tube without completely filling the space between them. (Refer to Utility Model Publication No. 55-43704).

However, even if a space is provided between the outer surface valley of the inner tube and the inner surface peak of the outer tube in the fitted state, the flexible tube does not have the peak of the outer tube within the valley. are fitted like a screw connection,
No matter how flexible it is, it imposes restrictions on bending, making it difficult to bend small curvatures, and since the space is small, not only does it increase weight, If the fitting between the peaks and valleys of the inner and outer tubes is loose, the inner and outer tubes will rotate independently, resulting in poor workability.

The present invention was developed in view of the above circumstances, and includes an outer tube that is fitted onto the outer surface of the convex portion of the synthetic resin inner tube, which has bellows-like irregularities on the inner and outer surfaces. On the outer periphery of the inner tube, an outer tube made of a synthetic resin softer than the inner tube and having a smooth outer circumferential surface is formed. The inner peripheral surface of the tube is engaged with the raised part of the inner tube, and a large space is left between the inner circumferential surface of the inner tube and the recessed part of the inner tube, so that the inner circumferential surface of the tube is fitted and integrated. The amount of fitting of the outer pipe crest into the trough is reduced, making it lightweight, allowing bending with a small curvature, and eliminating individual rotation of the inner and outer pipes.

The present invention will be explained below with reference to the embodiments shown in the figures.
Reference numeral 1 denotes an inner tube made of synthetic resin such as polyethylene, which is formed into a wavy shape by providing bellows-like uneven parts 2 and 3 on the inner and outer surfaces, and on the outer surface of the protruding part 3,
A resistor, for example, a protrusion 4 as shown in the figure, is provided to prevent the outer tube 5 fitted onto the outer circumference of the inner tube 1 from moving in the circumferential direction and the axial direction. Reference numeral 5 denotes an outer tube made of synthetic resin such as polyvinyl chloride, which is made of polyvinyl chloride or the like and has a smooth outer surface, and has a raised portion 4 formed on the convex portion 3 of the inner tube engaged with the inner surface. In this way, the inner tube 1 is prevented from rotating, and the inner and outer tubes 1 and 5 are fitted with a wide space 6 formed between the inner surface of the outer tube 5 and the recess 2 of the inner tube 1. It is integrated. Note that although the concavo-convex portions 2 and 3 of the inner tube 1 are formed in the shape of a ring and axially symmetrical in the figure, they may also be formed in a spiral shape. It may be in the shape of a rod, as shown in Fig. 2.

In the flexible tube of the present invention, an inner tube 1 is formed into a wavy shape by adding uneven parts 2 and 3 on the inner and outer surfaces, and an outer tube 5 that is softer than the inner tube 1 on the outer periphery is fitted. The inner and outer tubes 1 and 5 form a raised portion 4 on the outer surface of the convex portion 2 of the outer tube 1, and the tensile strength is increased by forming a raised portion 4 on the outer surface of the convex portion 2 of the outer tube 1. Soft outer tube 5
The fact that the inner surface of the tube is anchored provides a significant improvement over conventional corrugated tubes as a single layer. Furthermore, the raised portion 4 is located on the outer tube 5 with respect to the inner tube 1.
By acting as a resistor to prevent the inner and outer tubes from moving in the circumferential and axial directions, the inner and outer tubes 1 and 5 are prevented from rotating individually.

In particular, according to the present invention, in the outer surface recess 2 of the inner tube 1 whose inner and outer surfaces are corrugated as in the above-mentioned known example,
The inner surface of the outer tube 5 corresponding to the recess 2 of the inner tube 1 is
Since it hardly fits into the recess 2 and a large space is formed between the inner surface of the outer tube and the valley 2 of the inner tube, the amount of material used can be reduced accordingly, making it lightweight. Not only can the cushioning properties be increased, but also the bending of small curvatures can be performed well, making the bending work during installation work easier.
Furthermore, during this bending, the flesh of the outer tube 5 slightly enters the recess 2 of the inner tube at the inner bending portion, thereby preventing extreme bending and preventing local creases.

In this way, the flexible tube of the present invention not only has high compressive strength and tensile strength, but also has improved impact resistance while being lightweight, and can be bent well at small curvatures. It has the effect of effectively preventing the occurrence of creases during bending, etc., and can exhibit excellent functions when used as a wiring protection tube for buried electric wires.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway side view of the flexible tube of the present invention;
The figure is a partially cutaway side view showing another embodiment. 1 is an inner tube, 2 and 3 are uneven parts, 4 is a raised part, 5 is an outer tube, and 6 is a wide space.

Claims (1)

[Scope of utility model registration request] The outer surface of the protrusion on the outer periphery of the synthetic resin inner tube, which has bellows-like unevenness formed on the inner and outer surfaces in a spiral or axially symmetrical manner, An outer tube, which is made of a synthetic resin softer than the inner tube and has a smooth outer circumferential surface, is provided on the outer circumference of the inner tube with a protruding protuberance that provides resistance to axial movement. A flexible tube made of synthetic resin, characterized in that the surface is engaged with the raised portion of the inner tube, and the recessed portion of the inner tube is left in a wide space so as to be integrally fitted together.