JPH03121393A - Bellows pipe - Google Patents

Abstract

PURPOSE:To increase rigidity in the vicinity of fixed section so as to prevent breakage by molding and waving the peripheral face of metallic cylinder in which wall thickness of at least one end in longitudinal direction is larger than that of other sections. CONSTITUTION:The peripheral face of a metallic cylinder in which wall thickness of at least one end in longitudinal direction is larger than that of other sections is waved and molded in a bellows pipe 6a. Consequently, the bellows pipe is not deformed easily because rigidity in the vicinity of one end is larger than that in other sections. Even if bending displacement is applied, stress which is generated in the vicinity of one end is reduced. Stress over the whole length of the bellows pipe 6 is distributed equally to prevent breakage of the pipe.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a bellows tube.

(Prior art) Multilayer bellows pipes are highly flexible and absorb external shocks, and also have the function of absorbing vibrations, so they are used in piping for automobile exhaust systems, piping around ship engines, and air conditioning. Widely used for related pumps and compressor piping.

As shown in Fig. 5, the bellows tube 1 from υC is formed by forming corrugations using a cylindrical body whose tube wall thickness is constant in the axial direction, and crests 2 of the same shape are formed at equal intervals. It was something that had been done.

(Imposition to be Solved by the Invention) When a bending displacement is applied to the conventional bellows pipe described above, the bending moment l~ applied to the bellows portion 3 near the fixed portion 4 of the multilayer bellows pipe 1 shown in FIG. 5 becomes large. As a result, stress is concentrated in this portion, and breakage accidents of the bellows tube 1 at the bellows portion 3 occur relatively frequently.

In addition, in conventional bellows tubes, the overall wall thickness is constant and the bellows are formed at equal intervals, so the bellows tube has the same resonant frequency over its entire length. Due to resonance, damage could easily occur.

The present invention was made in view of the current state of bellows pipes as described above, and its purpose is to increase the rigidity near the fixed part even when bending displacement is applied, thereby preventing breakage accidents, and also improving vibration resistance. The purpose of the present invention is to provide a bellows tube with a high quality.

(Means for Solving the Problems) In order to achieve the above object, the bellows pipe of the present invention has a metal cylindrical body whose wall thickness at least at one end in the longitudinal axis direction is thicker than the pond part, and the corrugation is formed on the circumference of the metal cylinder. It has a molded configuration.

(For 1 piece) The bellows pipe of the present invention is formed by forming a corrugation on the circumferential surface of a metal cylindrical body that is thicker than the wall portion at least at one end in the longitudinal axis direction. The rigidity of the surrounding area is greater than that of the pond part, making it difficult to deform, and even if bending displacement is applied, the stress generated near one end becomes small. Therefore, the stress distribution over the entire length of the bellows tube is uniformly distributed by changing the wall thickness, and breakage accidents are prevented from occurring.

In addition, by forming different sections of the tube wall in the axial direction of the bellows tube and making the resonance frequency of the bellows tube different in each section in the axial direction, the vibration resistance strength is improved to prevent the whole body from resonant vibration and damage. I can do it.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a cross-sectional view of the metal cylindrical body of the first embodiment, and the second figure is a cross-sectional view of the metal cylinder of the first embodiment.
It is a sectional view of the bellows tube of the example.

As shown in FIG. 1, the metal cylindrical body 5a of the first embodiment has different plate thicknesses in the axial direction, and is thicker at both ends. The metal cylindrical body 5a having such a shape is subjected to corrugation forming using a known corrugation forming machine, thereby forming a bellows tube 6a as shown in FIG. In the bellows tube 6a according to the first embodiment, the tube walls at both ends connected to the fixed portions 4a and 4b are thicker and more rigid than the pond portions.

Therefore, even if bending displacement is applied to the bellows tube 6a, the rigidity near the fixing parts 4a and 4b increases, making it difficult to deform and generating less stress.The stress distribution becomes equal as a whole, and the bellows tube 6a becomes Will not break.

Furthermore, in the first embodiment, since the tube wall on the side of the fixed parts 4a and 4b is thicker than the pond part, the resonant frequency of the bellows tube 6a is different between the center part and both ends, so that the bellows tube 6a as a whole This prevents damage due to resonance.

In the above embodiment, both ends were formed with a thick wall. However, if the ambient temperature at both ends is greatly different, it is natural that stress will occur, so the thick wall is formed only on one end on the high temperature side. You can also do that.

FIG. 3 is a sectional view of a metal cylindrical body of the second embodiment, and FIG. 4 is a sectional view of a bellows tube of the second embodiment.

As shown in FIG. 3, the metal cylindrical body 51) of the second embodiment has thick parts formed at both ends and at the center in the axial direction.

The metal circle body 5b having such a shape is subjected to known corrugation using a forming machine, and a bellows tube 6b as shown in FIG. 4 is formed.

The bellows tube 6b according to the second embodiment has fixed parts 4a, 4
The tube walls at both ends connected to b and at the center are thicker and more rigid than the pond portion.

Therefore, bending displacement is applied to the bellows tube 6b, and the rigidity near the fixing portions 4a, 4b increases, making it less likely to deform than the thin-walled portions and generating less stress. Therefore, the stress distribution is equal over the entire length, preventing breakage of the bellows tube 6a, and in the bellows tube 6b of this embodiment, the tube walls at the center and both ends are thicker than the pond portions, so the center The resonance frequency of the bellows tube 6b differs between the end portion and both ends, and the bellows tube 6b is prevented from being in a resonant state as a whole and being damaged.

In addition, in the first embodiment and the second embodiment, two or three thick portions are formed in the axial direction, respectively.
Since acoustic passbands having different resonance frequencies are formed, the noise attenuation effect can also be enhanced.

In addition, in the second embodiment, thick portions are formed in the tube wall at three locations in the axial direction, and both ends of the bellows tube are connected to the fixed portion. For example, the pipe wall may have thick parts at five locations including at least one end in the axial direction, and the thick part at the center of the bellows pipe may be connected to the fixed part. You can also do that.

(Effects of the Invention) As described above in detail, according to the present invention, the rigidity near the fixed part is increased, breakage accidents do not occur near the fixed part even when bending displacement is applied, and high temperature This has the effect of reducing stress on the sides, and also improves vibration resistance and noise damping.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are diagrams explaining the first embodiment.
The figure is a cross-sectional view of a metal cylindrical body, Figure 2 is a cross-sectional view of a bellows tube, and Figures 3 and 4 show the second embodiment. ...Fixed part, 5a, 5b...Metal circle 6b...
Bellows tube.

Claims (1)

[Claims] A bellows tube formed by corrugating the circumferential surface of a metal cylindrical body whose wall thickness at least at one end in the longitudinal axis direction is thicker than the pond part.