JPH021580Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention can be used as various ducts, hoses, tubes, boots, seals, or covers that have excellent strength against abrasion and impact, and especially excellent stability during compression. This invention relates to the bellows hollow body used.

[Prior Art] Conventionally, this type of bellows hollow body has been manufactured by blow molding a thermoplastic plastic parison, and these are as shown in FIGS. 4 and 5, or 6 and 7. The configuration is as shown in .

Further, a material with good elasticity by forming valleys on the peaks is described in Japanese Utility Model Application Publication No. 55-92984.

[Problem to be solved by the invention] By the way, in the conventional bellows hollow body shown in FIGS. 4 and 5, the peak portions 14, which have a high expansion ratio in blow molding, are larger than the valley portions 15. However, in the case shown in FIGS. 6 and 7, the crest 24 has a flat portion 24', so that the ridge 24 has a flat portion 24'. Although thinning of the portion 24 can be prevented, during compression, as shown in FIG.
Since the flat part 24' of is curved and deformed in the outer circumferential direction,
When compressed, the outer diameter becomes large, which poses a problem when disposed in a narrow space, and it also has disadvantages, such as poor crush resistance during compression, and particularly poor stability during compression.

Furthermore, as described in Japanese Utility Model Application Publication No. 55-92984, in the case where small valleys are formed in the peaks, even if the elasticity is improved by making the wall thickness uniform, when compressed In this case, the peak portion bulges in the outer circumferential direction and the outer diameter increases, and the inner surfaces of the walls that make up the bellows hollow body do not come into contact with each other.
Similar to those shown in FIGS. 7 to 7, the stability during compression is poor.

The present invention is an attempt to eliminate the drawbacks of the conventional products, and is to improve the pitch of the peaks in the uncompressed state of the bellows, and By forming a concave part that has a specific relationship with the depth from to the valley and the wall thickness at the center of the valley, the peak part does not bulge in the outer circumferential direction during compression, and the outer diameter remains constant. The inner walls of the bellows hollow body are in contact with each other and supported, and have excellent strength against abrasion and impact.
It is an object of the present invention to provide a bellows hollow body that has excellent stability particularly when compressed.

[Means for Solving the Problems] The present invention is configured as follows as a technical means for achieving the above object.

That is, the configuration is such that in a bellows hollow body 1 in which peaks 4 and valleys 5 are provided alternately, a depression 6 is formed in the peak 4, and the depression 6 is formed when the bellows hollow body 1 is in an uncompressed state. With respect to the pitch of the peak portion 4, the depth from the peak portion 4 to the valley portion 5, and the wall thickness at the center of the valley portion 5, the depression portion 6 does not bulge out in the outer circumferential direction when the bellows hollow body 1 is compressed. The bellows hollow body is characterized in that it maintains a constant outer diameter and is formed so that the inner wall surfaces 7, 7 of the bellows hollow body 1 are in a specific relationship such that they abut against each other.

The above specific relationship is the width P of the depressed portion 6 of the peak portion 4.
1. The pitch of the peak 4 is P, and the depth of the depression 6 is D.
1. Depth from peak 4 to valley 5 is D, depression 6
If T1 is the wall thickness at the center of and T is the wall thickness at the center of the valley 5, P1 is 0.02 to 0.2P, D1 is 0.01 to 0.1D, and T
1 is in the range of 0.2 to 0.95T.

[Function] As described above, the bellows hollow body 1 according to the present invention has the following features:
The depressed portion 6 of the peak portion 4 corresponds to the pitch of the peak portion 4 in the uncompressed state of the bellows hollow body 1, and the pitch of the peak portion 4 to the valley portion 5 of the hollow bellows body 1.
When the hollow bellows body 1 is compressed, the recessed portion 6 maintains a constant outer diameter without expanding in the outer circumferential direction, and the hollow bellows body 1 Since the inner wall surfaces 7, 7 of the bellows are formed in a specific relationship such that they abut against each other, the bellows hollow body 1 is compressed (see FIG. 3), and the recessed portion 6
Even if it bulges in the outer circumferential direction, it does not bulge out from the ridge 4 in the outer periphery direction, and at most it becomes substantially flush with the ridge 4, and the outer diameter of the bellows hollow body 1 does not increase. Moreover, the wall inner surfaces 7, 7 of the bellows hollow body 1 are supported in contact with each other. Therefore, the bellows hollow body 1 maintains a stable state during compression and prevents the peak portion 4 from expanding.

[Embodiment] An embodiment of the present invention will be described based on FIGS. 1 to 3.

1 is a bellows hollow body, and this bellows hollow body 1
is integrally constructed by blow molding thermoplastic plastic. 2 is its main body, and 3 is a connecting portion integrally formed at both ends. The main body 2 has annular peaks 4 and valleys 5 arranged alternately in the axial direction, and is formed in a bellows shape, and an inwardly depressed depression 6 is formed in an annular shape on the outer periphery of the peak 4. There is. When the bellows hollow body 1 is compressed in the axial direction from the normal uncompressed state as shown in FIG. 2, the center 6a of the depressed portion 6 protrudes from both ends 6b as shown in FIG. In other words, the depressed portion 6 approaches a flat shape and maintains a constant outer diameter, and this depressed portion 6 reinforces the outer peripheral surface of the bellows hollow body 1, making it resistant to crushing during compression. It has excellent properties and can maintain a constant length when compressed. Furthermore, the end portions 6b of the adjacent recessed portions 6, 6,
6b, the wall inner surfaces 7, 7 of the adjacent bellows hollow bodies 1 are supported in contact with each other, so that the stability during compression can be further improved, and therefore, the bulges of the peaks 4 are prevented. be able to.

The shape of the depressed portion 6 of the hollow bellows body 1 may be U-shaped or U-shaped, in addition to the V-shape described above.

In order to obtain the above effects in the embodiment of the present invention, it is necessary that the overall structure of the peaks 4 and valleys 5 and the structure of the depressions 6 have a specific relationship as follows. It is.

That is, the above specific relationship is that the width of the depression 6 of the peak 4 is P1, the pitch of the peak 4 is P, the depth of the depression 6 is D1, the depth from the peak 4 to the valley 5 is D, If the wall thickness at the center of the depressed portion 6 is T1, and the wall thickness at the center of the valley portion 5 is T, then P1 is 0.02 to 0.2P, and D1 is 0.01 to
0.1D, T1 ranges from 0.2 to 0.95T.

In the above specific relationship, the width P1 of the depressed portion 6
is less than 0.02P, the depressed portion 6 exhibits the above effect.
In addition, the center 6a of the depressed portion 6 protrudes outward from both ends 6b and is deformed in a curved manner during compression, resulting in poor stability during compression. On the other hand, depression 6
When the width P1 exceeds 0.2P, the expansion/contraction width is extremely limited. Moreover, if the depth D1 of the depressed portion 6 exceeds 0.1D, the center 6a of the depressed portion 6 will be bent so as to protrude inward, and the bellows hollow body 1 will be inferior in stability when compressed. Furthermore, the wall thickness T at the center of the depressed portion 6
1 is less than 0.2 or exceeds 0.95T, the peak 4
There is an extreme difference in the wall thickness between the troughs 5 and the troughs 5, and the peaks 4 are wrinkled during expansion and contraction, resulting in poor shape retention and poor elasticity.

In addition, in the entire wall of the bellows hollow body 1, the inner layer 1
The B outer layer 1C is made of a thermoplastic elastomer such as polyester elastomer, polyurethane elastomer, or polyamide elastomer, which has excellent strength such as bending resistance and abrasion resistance, and furthermore, the outer layer 1C is made of a thermoplastic elastomer such as polyester elastomer, polyurethane elastomer, polyamide elastomer, etc., which has excellent strength such as bending resistance and abrasion resistance. By constructing the thick main layer 1A in a multi-layered manner using plastic with excellent flexibility, such as soft polyvinyl chloride or ethylene-vinyl acetate copolymer, it is possible to reduce wear and tear.
A bellows hollow body with excellent impact strength and flexibility can be obtained.

Note that the multilayered bellows hollow body as described above can be integrally constructed by coextrusion multilayer blow molding.

[Effects of the invention] As described above, in the bellows hollow body 1 in which the peaks 4 and valleys 5 are alternately provided, the depressions 6 are formed in the peaks 4, and the depressions 6 are formed in the bellows. When the bellows hollow body 1 is compressed, the depressed portion 6 is compared to the pitch of the peak 4 in the uncompressed state of the hollow body 1, the depth from the peak 4 to the valley 5, and the wall thickness at the center of the valley 5. Since the bellows hollow body 1 maintains a constant outer diameter without bulging in the outer circumferential direction and has a specific relationship in which the inner walls 7, 7 of the hollow bellows body 1 abut against each other, the bellows do not bulge during compression. The part 4 maintains a constant outer diameter without bulging in the outer circumferential direction, and the inner walls 7, 7 of the bellows hollow body are in contact with each other and supported, and have excellent strength against wear, impact, etc. A bellows hollow body 1 having excellent stability during compression can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a front view showing the bellows hollow body according to the present invention in an uncompressed state, Fig. 2 is an enlarged sectional view of a part of the same, Fig. 3 is an enlarged sectional view of a part of the same when compressed, and Fig. 4 The figure is an enlarged sectional view of a part of a conventional bellows hollow body showing the state when it is not compressed, FIG. 5 is a sectional view showing the state when the same as above is compressed, and FIG. Partial enlarged sectional view showing the state when not compressed, No. 7
The figure is a cross-sectional view showing the state when the same as above is compressed. DESCRIPTION OF SYMBOLS 1... Bellows hollow body, 2... Main body, 3... Connection part, 4... Mountain part, 5... Valley part, 6... Depression part,
7,7...Inner surface of the wall.

Claims (1)

[Scope of utility model registration request] In the bellows hollow body 1 having alternating peaks 4 and valleys 5, a depression 6 is formed in the peak 4, and the depression 6 is similar to the peak 4 of the bellows hollow body 1 in an uncompressed state.
, the depth from the ridge 4 to the trough 5, and the wall thickness at the center of the trough 5, the depression 6 does not bulge in the outer circumferential direction when the bellows hollow body 1 is compressed, and has a constant outer diameter. A bellows hollow body is characterized in that the hollow bellows body 1 is formed such that its diameter is maintained and the inner wall surfaces 7, 7 of the hollow bellows body 1 abut each other in a specific relationship.