JPH11248053A - Expansion bellows type duct - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an expansion bellows type duct which has excellent tight attachment of a reinforcing coil to a band-shaped member, can hold the form at the time of contraction, generates less dangling at elongation, is light in weight, allows easy cutting, and may be thrown without any significant problem. SOLUTION: A duct 1 is composed of a reinforcing resin coil 2 in spiral shape and a duct wall 5 formed by overlapping a band-shaped member of resin and winding along the spiral of the coil. One end 26 on the side alongside the longitudinal direction of the band-shaped member enwraps the reinforcing coil 2 and sealed in tight attachment to the band-shaped member and the other end of the band-shaped member enwraps the adjacent reinforcing coil 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a form in which a resin spiral reinforcing coil is wrapped in a duct wall so that even when bending is repeated, the adhesion between the reinforcing coil and the duct wall is excellent and the duct is contracted. The present invention relates to a lightweight telescopic bellows duct which has excellent holding properties and has little sagging during elongation, and which is particularly useful as an air conditioning duct.

[0002]

2. Description of the Related Art Conventionally, typical types of ducts of this kind are classified into three types (a), (b) and (c). (A): A telescopic bellows duct in which a metal coil is attached to a duct wall made of resin, and grooves are provided in a valley portion and a mountain shoulder portion of the duct wall in a vertical section of the duct. (B): Only duct wall made of resin (no coil used)
And a telescopic bellows duct in which the adjacent hypotenuses have a relationship between a thick side and a thin side or a long side and a short side. Even with this type of duct, it can be compactly contracted when not in use, can be freely adjusted in length when in use, and can retain its shape even when bent. (C): An elastic bellows duct in which a resin coil such as highly crystallized polypropylene is melt-bonded or adhered to a duct wall made of resin, and grooves are provided in a valley portion and a shoulder portion of the duct wall in a vertical section of the duct. This type of duct can be compactly contracted when not in use, can be freely adjusted in length when in use, and can maintain its shape even when bent.

[0003]

However, the above (a),
The (b) and (c) types have the following problems. The type (a) is heavy because the coil serving as a reinforcing material is made of metal. If the coil is long, the coil hangs down due to its own weight, and the shape cannot be maintained. Also, it is not easy to cut during duct molding and piping work because it is made of metal. When incinerated, the metal coil remains without burning. Further, in the field where hygiene is required, metal rust is generated. The (b) type does not have a coil that plays the role of a reinforcing material, so the crushing of the duct in the radial direction is weak, and the shape cannot be maintained if a negative pressure is applied to the duct even when used for air conditioning. Not actually used. Type (c) solves the problems of (a) and (b). However, the resin used is limited because the duct wall made of resin and the coil material are resins that can be melt bonded or adhered.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a resin spiral reinforcing coil is wrapped in a resin strip constituting a duct wall so that the duct wall can be connected to the duct wall even when bending is repeated. It is an object of the present invention to provide a telescopic bellows duct having excellent adhesion without peeling from a coil material. Furthermore, by replacing the helical coil that plays the role of a reinforcing material with metal instead of resin, weight is reduced. Even if the duct is elongated (long), it does not sag due to its own weight, and it retains its shape even when it contracts. It is an object of the present invention to provide a telescopic bellows duct which is excellent in cutability and disposal property.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to provide a telescopic bellows duct comprising a resin spiral reinforcing coil and a duct wall formed by overlapping and winding a resin band along the spiral of the coil. A telescopic bellows duct is provided in which one end on the side along the longitudinal direction of the band wraps the reinforcing coil, is tightly sealed to the band, and the other end of the band covers the adjacent reinforcing coil. Achieved by:

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A duct according to the present invention has a groove in a valley and a shoulder of a duct wall in a longitudinal section thereof.
Furthermore, in the aspect in which the left and right duct walls in the vertical cross section of the duct are thin and thick,
An embodiment satisfying the following (A) to (F) is preferable, and an embodiment combining these embodiments is more preferable.

(A) In the vertical section of the duct, the ratio of the right and left hypotenuses formed by the duct wall with the groove at the valley of the duct wall being 3:
7-7: 3 (B) Spiral pitch / wave height is 1.8-3.2 (C) Wave height / duct outer diameter is 0.02-0.1 (D) Flexural modulus of duct wall material is 2,500 -10,
000 (kgf / cm ² ) (E) The bending elastic modulus of the coil material is 10,000 to 40,
000 (kgf / cm ² ) (F) Wave height / coil core diameter is 1.5 to 5

In the present invention, one end on the side along the longitudinal direction of the band encloses the reinforcing coil and is tightly sealed to the band means, for example, as shown in FIG. The duct wall) 5 is wrapped by one end 26, and the one end 26 is adhered and sealed at the sealing member 25 with the strip 5 or, as shown in FIG. Similarly, it refers to a state where it is adhered and sealed. One end of the band does not envelop the reinforcing coil, but simply sandwiches the reinforcing coil between one end of the band and the other end of the adjacent band, and in a sealed structure, it is not possible to firmly fix the reinforcing coil. It is difficult. The seal portion 25 is formed by heat fusion, an adhesive, or the like, but heat fusion is preferable. The other end (mountain) 3 of the strip covers the reinforcing coil 2 adjacent thereto, and this cover is preferably bonded to the lower strip by heat fusion, an adhesive or the like. . In the present invention, the belt-like body is a tape-like long object, and its width and thickness are appropriately determined according to the size, use, and purpose of the duct. The duct of FIG. 3 bends at the grooves 6 and 7 when a force in the compression direction is applied, contracts as shown in FIG. 4, and is held in that form.

The material of the strip constituting the wall of the telescopic bellows duct of the present invention includes high-density polyethylene, polypropylene, polystyrene, methacrylic resin, acrylonitrile-butadiene-styrene copolymer resin, acrylonitrile-styrene copolymer resin, polycarbonate, A thermoplastic resin such as a polyester resin and a polyamide may be used. The duct wall is preferably made of a thermoplastic resin having a relatively small specific gravity as a main component, for example, a polypropylene-based resin. Although it differs somewhat depending on the type of the thermoplastic resin, it is preferable to use an elastomer component as a copolymer or a mixture with the above main component. The flexural modulus is 2,500 to 10,000 (kgf / cm ² )
Is preferred. 2,500 flexural modulus of duct wall material
If it is less than (kgf / cm ² ), the bent portion tends to have a large rubber-like elasticity during the contraction process, so that it tries to return to the expanded state. Therefore, it cannot be easily held in a contracted state. On the other hand, the flexural modulus of the duct wall material (JIS K7
When (203) exceeds 10,000 (kgf / cm ² ), whitening occurs in the bent portion, resulting in poor bending fatigue resistance.

[0010] As a material constituting the coil, a material having a high flexural modulus is required, and is 10,000 to 40,000.
0 (kgf / cm ² ) is preferable. Depending on the coil core diameter, the bending elastic modulus of the coil material is 10,000
If it is less than 0 (kgf / cm ² ), the rigidity of the core material is weak, and in the shrinking process, the core may bend and may not be able to maintain a stable duct length in a shrunk state. On the other hand, the bending elastic modulus of the coil material is 40,000 (kgf / c
When the resin exceeds m ² ), the rigidity of the core is increased, but the impact strength is reduced, so that the core is easily broken. Examples of the coil material include high-density polyethylene, polypropylene, polystyrene, methacrylic resin, acrylonitrile-butadiene-styrene copolymer resin, acrylonitrile-styrene copolymer resin, polycarbonate, polyester resin, and thermoplastic resin such as polyamide. Preferably, when both the duct wall and the coil are made of polypropylene, the bending fatigue resistance is also improved, which is effective in reducing the weight.

The density of the reinforcing coil and the band is 1.3 g / cm ^3.
Hereinafter, it is particularly preferable that the content be 1.2 g / cm ³ or less. Further, when the material of the reinforcing coil and that of the band are made of the same material, a bellows duct that is stable during expansion and contraction can be obtained. Further, when a transparent resin is used as the material of the reinforcing coil and the belt-like body, it is possible to obtain a duct in which the inside of the duct can be easily observed, and various applications can be expected.
Further, it is preferable that the reinforcing coil and the strip are heat-fused. However, according to the present invention, even if the reinforcing coil and the strip are not heat-fused to each other, a sufficiently intended telescopic bellows duct can be obtained. be able to.

Next, the present invention will be further described with reference to the drawings. FIG. 3 is a partially cutaway front view showing an extended state of the duct of the present invention. The extended state refers to a state in which the duct maintains a stable length and shape without receiving any external force. FIG. 4 is a partial cross-sectional view of the contracted state, wherein 1 is a duct main body, 2 is a reinforcing coil, 3 is a bellows crest (the other end of the band), 4 is a bellows trough, and 5 is a band. A body (duct wall), 6 is a groove at a valley, 7 is a groove at a shoulder, 8 is a thick portion (double layer portion), and 9 is a step-down portion. In FIG. 3, reference numeral 10 denotes a helical pitch (p), 11 denotes a wave height (distance between peaks and valleys: h)), 12 denotes an outer diameter of the duct (d), and 13 denotes a groove at a shoulder of the duct wall. The hypotenuse portion on the side having no groove, and the hypotenuse portion 14 on the side having a groove at the mountain shoulder of the duct wall. The duct of FIG. 3 is bent at the grooves 6 and 7 when a force in the compression direction is applied, contracts as shown in FIG. 2, and is held in that form.

In the present invention, by providing grooves in the valleys and shoulders of the duct in the vertical section of the duct, and by making the left and right duct walls in the vertical section of the duct thin and thick, respectively, more stable operation is achieved. A structure that retains the form can be provided.

In the present invention, in a vertical section of a duct wall forming a duct trough, a ratio of a hypotenuse having a groove at a mountain shoulder to another hypotenuse is 3: 7 to 7: 3. And preferably from 4: 6 to 6: 4,
The pitch in the contracted state can be reduced, and the duct length when not in use can be reduced. As shown in FIG. 3, when the pitch 10 from the peak 3 to the adjacent peak 3 is divided by the valley 4, as shown in FIG. It refers to the ratio of the length in the axial direction of the hypotenuse 14 provided with a groove in the shoulder portion.

Further, by forming the pitch / wave height in the range of 1.8 to 3.2, it is possible to reduce the sag in the extended state and to easily fix the contracted state. Further, by setting the wave height / duct outer diameter to 0.02 to 0.1, the duct form in the contracted state can be easily maintained, and drooping is small.

Further, by setting the wave height / coil core diameter to 1.5 to 5, the expansion ratio can be increased, and the holding property at the time of contraction is also good. The coil core diameter depends on the size of the duct, but 1-6 mm, and even 1-4 mm
It is preferable to choose from. Such a duct has a spiral shape, and can be continuously formed, and can be formed into a long object.

In the duct of the present invention, as shown in FIG. 3, when the shoulder portion adjacent to the groove 7 of the shoulder portion is formed as a thick portion 8 and a stepped portion 9 is formed on the outer surface of the duct, the shrinking process is performed. In addition, stress concentration is likely to occur only in the portion where the groove and the step have fallen during the elongation process, and only the valley portion and that portion can be bent points.
Therefore, since the stress is not dispersed except the groove and the stepped portion, a stable length and shape can be maintained when the duct is extended and contracted. Further, the thickness of the shoulder portion adjacent to the core material is increased, so that the coil can play a reinforcing role. Furthermore, even if the groove is formed shallow for the reasons described above, the bending point is easy to be determined, so that it is resistant to bending fatigue.

Next, with reference to the drawings, a description will be given of the relationship between each component and the action in the process of contracting the duct. First, paying attention to the cross-sectional shape of a conventional highly rigid duct having a metal coil at the time of expansion and contraction, as shown in FIG. 3
When a point link mechanism is configured to apply a compressive force P in the duct axis direction, the link mechanism changes the point 16 from the point 16 to the point 161 to the point 1 by the crank motion of the hypotenuse 18 around the point 17.
62, and the point 161 is associated with the hypotenuse 18
Is deformed to the oblique side 181, causing tension strain inside the resin (oblique side 181) constituting the duct wall, and generating a maximum compressive stress as seen in the compressive stress diagram of FIG. 7 as a repulsive force. In the process from point 161 to point 162,
Contrary to the previous process, the tension strain inside the resin acts in the direction to be eliminated, so a negative compressive stress acts and the duct will necessarily have a contracted state length and a stress relationship that maintains the shape .

Therefore, when the sag is to be reduced by a coil having high rigidity such as a metal, it can be maintained if the maximum value of the compressive stress shown in FIG. To increase the maximum value, the hypotenuse 1
It has been found that it is preferable to increase the tensile strain of 81, that is, to make the hypotenuse 18 and the hypotenuse 19 in the longitudinal section of the duct wall forming the valley of the duct as close as possible to the distribution, and to lower the wave height with respect to the pitch. .

However, in the case of a coil having a lower rigidity than a metal such as a resin, if the tensile strain of the hypotenuse 181 increases, the maximum value of the compressive stress in FIG. When the compressive force P is further increased, the coil becomes bent and cannot be contracted.

Therefore, the present invention slightly lowers the maximum value of the compressive stress in FIG. 7 for a low rigidity material such as a resin core material. That is, the tension distortion of the hypotenuse 231 in FIG. 6 is reduced, that is, the wave height is increased with respect to the pitch between the hypotenuse 23 and the hypotenuse 24 in the vertical section of the duct wall forming the valley of the duct, and the coil loses the maximum compressive stress. It is preferable not to do so. The problem of sag can be solved by reducing the weight. In addition, with the above structure, a duct that is strongly crushed in the radial direction of the duct can be obtained.
In addition, 20 and 21 in FIG. 6 are respectively 15 and 21 in FIG.
16, 201, 202, and 202 in FIG.
211, 212 and 231 are respectively 151, FIG.
152, 161, 162, and 181.

[0022]

Examples Examples of the present invention and comparative examples will be described. Examples 1 and 2 and Comparative Example 1 As a duct wall material (band-shaped body), a flexural modulus of elasticity of 6,500 was used.
(Kgf / cm ²⁾ Polypropylene (PP) (Density 0.91 g / cm ³⁾ made strip of, as constraining the coil material, bend highly crystalline PP of the modulus 21,000 (kgf / cm ²⁾ (Density 0. 90 g / cm ³⁾ (Example 1) and a coil (coil core diameter) using high-density polyethylene (density 0.95 g / cm ³⁾ having a flexural modulus of 16,000 (kgf / cm ² ) (density 0.95 g / cm ³⁾ 1.8 mm) is wrapped by one end on the side along the longitudinal direction of the band, and the bands are sealed by heat sealing, and co-extrusion is turned, and the coil is adjacent to the other end of the band. A duct as shown in FIG. 1 was obtained by covering the upper part and fusing the overlapped portion. The duct has a groove at a valley and a mountain shoulder, and further has a stepped portion on the outer surface of the duct where the thickness of the mountain shoulder adjacent to the groove at the mountain shoulder is increased.

For the comparative example (Comparative Example 1), a coil in which a carbon steel wire having a carbon composition of 0.4% by weight was coated with PP was used, and the coil was melted without being completely wrapped by one end of the strip. The duct was obtained by bonding. With respect to the obtained elastic bellows duct, the adhesion between the coil and the band-shaped body, the sagging during elongation, and the shape retention during shrinkage (whether or not the shape can be maintained in a contracted state) were measured. Table 1 shows the results.

In the hanging test, as shown in FIG. 8, the hanging distance at the tip of the duct was measured with a test length of 50 cm in an extended state. In addition, the temperature condition was measured without blowing air into the duct at room temperature of 25 ° C. The evaluation of adhesion is
In a stretched state, using a 60 cm test duct, a bending repetition test (180 ° bending, 25 ° C., 20 times / min) was repeated 5,000 times to form a duct wall material (band) and a wrapped reinforcing coil. Was visually evaluated for adhesion.

[0025]

[Table 1]

[0026]

The telescopic bellows duct of the present invention has excellent adhesion between the reinforcing coil and the band, has good shape retention during shrinkage, has little droop during elongation, is light in weight, and has good cutability. Also, the disposability is excellent.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a reinforcing coil and a strip of a duct according to the present invention.

FIG. 2 is a partial cross-sectional view of a reinforcing coil and a strip showing another embodiment of the duct of the present invention.

FIG. 3 is a partially cutaway front view showing a duct extension state of the present invention.

FIG. 4 is a partial cross-sectional view illustrating a contracted state of the duct according to the present invention.

FIG. 5 is a partial simplified cross-sectional view of a comparative example illustrating an operation.

FIG. 6 is a partial simplified cross-sectional view of the embodiment explaining the operation.

FIG. 7 is a compressive stress diagram in a shrinking process.

FIG. 8 is a diagram illustrating a sag test method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Duct 2 Reinforcement coil 3 Crest (the other end on the side along the longitudinal direction of the strip) 4 Trough 5 Duct wall (strip) 6 Trench groove 7 Groove at shoulder 8 Thick section 9 steps Falling part 10 Pitch (p) 11 Wave height (h) 12 Outer diameter (d) 13 Slope with no groove on mountain shoulder 14 Slope with groove on mountain shoulder 15, 16, 17 Bending point 18 Groove on mountain shoulder A hypotenuse with a groove 19 A hypotenuse without a groove in the mountain shoulder 20, 21, 22 Bending point 23 A hypotenuse with a groove in the mountain shoulder 24 A hypotenuse without a groove in the mountain shoulder 25 Seal part 26 Along the longitudinal direction of the belt-shaped body One end of the side

Claims (4)

[Claims] 1. A telescopic bellows duct composed of a resin-made spiral reinforcing coil and a duct wall formed by overlapping and winding a resin-made band along the spiral of the coil, along a longitudinal direction of the band-shaped body. A telescopic bellows duct, one end of which surrounds the reinforcing coil, is tightly sealed to the band, and the other end of the band covers an adjacent reinforcing coil. 2. The telescopic bellows duct according to claim 1, wherein a groove is provided at a valley portion and a shoulder portion of the duct wall in the duct longitudinal section. 3. The telescopic bellows duct according to claim 1, wherein the left and right duct walls in the vertical section of the duct are made thin and thick, respectively. 4. The telescopic bellows duct according to claim 1, which satisfies the following (A) to (F) when the duct is extended. (A) In the vertical section of the duct, the ratio of the right and left hypotenuses formed by the groove at the trough of the duct wall or the duct wall bordering the trough is 3:
7-7: 3 (B) Spiral pitch / wave height is 1.8-3.2 (C) Wave height / duct outer diameter is 0.02-0.1 (D) Flexural modulus of duct wall material is 2,500 -10,
000 (kgf / cm ² ) (E) The bending elastic modulus of the coil material is 10,000 to 40,
000 (kgf / cm ² ) (F) Wave height / coil core diameter is 1.5 to 5