JPH0469227A - Corrugated pipe - Google Patents

Abstract

PURPOSE:To obtain a corrugated pipe exhibiting excellent strength by molding a pipe wall with a bellows-like unevenness by diameter-expanding drawing of an original straight pipe. CONSTITUTION:After a straight pipe 1' is extrusion-molded and is heated at a temp. which is suitable for drawing, the straight pipe 1' is pulled in an outer mold 2 the inner face of which has a bellows-like unevenness. Then, both sides 3 and 4 of the straight pipe 1' are tightly sealed and a fluid pressure is applied to the inside to expand and deform the straight pipe, to bring the outer face into close contact with the inner face of the outer mold 2 without gap and to draw and mold the bellows-like unevenness. It is cooled and solidified as it is and then, the drawn corrugated pipe 1 is taken out by opening the outer mold and the both end parts 1B and 1B are cut off to obtain a required corrugated pipe 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to corrugated tubes, and more particularly to improved corrugated tubes.

[Conventional technology]

Conventionally, tubes having bellows-shaped tube walls have been widely used as flexible tubes.

Generally, in order to improve elasticity and deformability of the bellows-shaped flexible tube, it is preferable that the wall thickness of the tube be thin and the bellows-like unevenness be deep.

[Problems with conventional technology]

However, when a plastic pipe is molded as described above, the pressure resistance of the pipe inside and outside is reduced, and buried pipes have the disadvantage of being resistant to soil erosion and being unsuitable for high-pressure flow.

Further, in order to solve this problem in terms of strength, reinforcing metal cores are embedded along the bellows-like unevenness, but this method has the disadvantage of being labor-intensive and expensive to manufacture.

[Problem to be solved by the invention]

The present invention has been made in view of the above-mentioned problems, with the object of providing a corrugated tube that is easy to mold, has excellent elasticity, has excellent strength, and has excellent internal and external pressure resistance.

[Technology that led to solving the problem]

That is, the corrugated pipe of the present invention is characterized in that the pipe wall having bellows-like irregularities is formed by expanding the diameter of an original straight pipe.

[Effect]

In the corrugated pipe of the present invention, the bellows-like unevenness on the pipe wall is formed by stretching the original straight pipe in the radial direction and expanding the diameter to form the bellows-like unevenness on the pipe wall. The strength is improved in proportion to the amount of stretching, and the thickness of the tube wall is reduced in inverse proportion to the amount of stretching.

Therefore, it is possible to obtain a corrugated tube that has excellent strength, has a thin tube wall thickness, and is highly flexible.

〔Example〕

Next, the present invention will be explained in detail.

FIGS. 1A to 1C are explanatory diagrams showing the manufacturing process of an embodiment of the present invention, and FIG. 2 is a sectional view of a main part of the corrugated tube of the present invention.

As shown in FIG. 1, the corrugated pipe 1 of this invention has a straight pipe 1.
After extrusion molding (not shown) and heating it to a temperature suitable for stretching, a straight tube of 1° is passed through an outer mold 2 having bellows-like irregularities on the inner surface. Seal the sides 3.4 of a 1° straight pipe, apply fluid pressure to the inside to expand and deform the outside, and bring the outside into close contact with the inside of the outer mold 2 without any gaps to form a bellows-like unevenness by stretching. Then, the outer mold 2 is opened, the stretched corrugated tube 1 is taken out, and both end portions IB and IB are cut off to form the corrugated tube 1 as shown in FIG.

In addition, as shown in FIG. 2, there is a socket at one end of the corrugated pipe 1.
A socket or a flange (a socket in the illustrated example) 5 is adhesively fixed as required.

In addition, as an example of the above-mentioned corrugated tube, a case in which uniform unevenness is formed over the entire length is shown, but as shown in FIG. 3A, the corrugated tube 1 is It is also possible to mold it into a shape that is easy to connect to a socket or flange (the illustrated example is a socket) 5, as shown in the opening of FIG.

The stretch-formed corrugated tube formed as described above exhibits a pressure resistance proportional to the stretching ratio, compared to a corrugated tube of the same shape formed without stretch-forming.
Furthermore, if the strength is the same, the tube wall thickness will be inversely proportional to the stretching ratio, so a corrugated tube with better flexibility can be obtained.

〔effect〕

As explained above, in this invention, since the bellows-like unevenness is formed by stretching, it is possible to create a corrugated tube with excellent strength, and with a tube wall of the same thickness, the pressure resistance is proportional to the stretching ratio. Moreover, since the tube wall can be made thinner with the same pressure resistance, it has the effect of making it possible to form a corrugated tube with excellent flexibility.

[Brief explanation of drawings]

Figures 1A to 3C are explanatory diagrams showing the manufacturing process of an embodiment of the present invention, Figure 2 is a sectional view of the main part of the corrugated tube of the invention, and Figure 3A is a diagram showing the manufacturing process of another embodiment. 1: ; IL 1 ゛ U -7 Rod 2 figure ♀ ko

Claims (1)

[Claims] (1) A corrugated pipe characterized in that a pipe wall having bellows-like irregularities is formed by expanding the diameter of an original straight pipe.