JPH0318078B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a flexible duct used for air conditioning piping and the like.

[Prior Art] As a conventionally known flexible duct, there is one disclosed in, for example, Japanese Utility Model Application Publication No. 166386/1986.

This product is made into a pipe shape by forming a plurality of corrugated ribs parallel to the side edges of a strip-shaped thin metal plate of a predetermined width, winding it spirally, and joining the adjacent side edges with a seam. It is something that is formed.

FIG. 9 shows a flexible duct manufactured in this manner.

In the figure, 1 is a seam portion, and 2 is a corrugated rib. A plurality of ribs 2 are formed between the seam portions 1 at appropriate pitches.

As shown in FIG. 10, the above-mentioned seam part 1 is formed by bending one side edge 3 at right angles to form a rising part 4, and bending the other side edge 5 into this rising part 4.
It is folded in the direction of the arrow after being covered with
The surface as a whole is parallel to the duct axis.

Note that caulking 6 consisting of fine irregularities may be applied to the seam portion 1 if necessary.

In addition, as another example of the prior art, as shown in FIG. Public bulletin).

In order to make the above-mentioned flexible duct more compact during transportation, it is compressed in the axial direction after manufacturing to the extent that the ribs touch each other, and then stretched to the required length at the construction site, or stretched to the required length at the construction site, or Can be bent along.

[Problems to be Solved by the Invention] As mentioned above, although this type of flexible duct is inevitably subjected to compression, stretching, and bending, the material is quite thin, so the seams do not form during compression deformation. In addition, during stretching or bending, the seams may become loose, and in some cases, they may partially separate, resulting in so-called disintegration.

This problem arises because the joining structure of the seams is a relatively simple structure in which only the other side edges are held together.

SUMMARY OF THE INVENTION Therefore, the present invention provides an extremely durable flexible duct that increases the strength of the seams and does not collapse or loosen when compressed, stretched, or bent.

[Means for Solving the Problems] In order to achieve the above object, the flexible duct of the present invention is formed into a valley shape or a mountain shape by pressing the seam joints. That's what I did.

[Function] The flexible duct is transported in a contracted state, is expanded to the required length at the piping site, and is piped to bend along a bend.

At this time, not only is there no displacement of the seam due to the torsion of the duct, but also the occurrence of collapse, loosening, unraveling, separation, etc. of the seam due to external forces of compression, stretching, and bending applied to the duct is significant. Decrease.

Moreover, since the manufactured flexible duct has a large compression ratio, the space occupation ratio becomes smaller accordingly.

Furthermore, the section modulus of the seam portion becomes significantly large, and thereby exhibits great rigidity against external forces from the outer circumferential direction.

[Embodiment] The flexible duct of the embodiment shown in FIGS. 1 to 3 has a plurality of corrugated ribs 13 parallel to the side edges 12a and 12b of a thin metal plate 11 of a predetermined width, similar to the conventional flexible duct. is formed by a forming roller, and is wound spirally on a core metal, similar to the conventional forming process shown in FIGS. 9 to 11, and adjacent side edges 12a and 12b are separated. A seam portion 14 joined by a seam and joined by a seam
is pressed into a valley shape (concave shape) using special inner and outer forming rollers placed at the end of the core metal to complete the pipe.

The seam 14 formed as described above has 4
It has a heavy structure, as shown in Figures 2 and 3.
In the state after manufacture, it is curved into a valley shape with a pitch that is not much different from the pitch of the ribs 13, and one end of the valley shape 15 has an upward slope as seen from the seam portion 14 of the terminal rib 13a. ) inclined surface 16
It continues smoothly in the middle of a, and the other end has a terminal rib 1.
3a and is continuous with the rib 13a.

Although the valley shape 15 is asymmetrical, it may be symmetrical.

The flexible duct manufactured as described above is formed with a constant pitch between each rib 13 for convenience of molding, so the space occupation rate is high as it is, so it is usually shown in Fig. 4. By compressing the ribs 13 in the axial direction, the distance between the ribs 13 is reduced, and the length of the entire flexible duct is shortened. The shortening rate is 1/4, and for example, a pipe length of 4 m can be shortened to 1 m.

The metal thin plates used in the present invention are ordinary steel plates, stainless steel plates, aluminum plates, etc., and have a thickness of about 0.08 mm to 0.20 mm, and the maximum elongation rate is determined by the length of pipe making. This is an increase of about 20%.

7 to 8 show a flexible duct showing another embodiment of the present invention, in which the seam portion 14 is press-formed into a chevron (convex shape) 17.

One end of this chevron 17 smoothly continues in the middle of the slope 16b of the end rib 13b (the slope seen from the spliced part 14 is a downward slope), and the other end extends to the end rib 13b. It has the same effect as the valley shape 15 mentioned above.

As described above, since the seam portion 14 is formed into the valley shape 15 or the mountain shape 17 by pressing, it is possible to achieve a strong integration in the same way as the pressure welding by caulking, and the direction thereof is approximately parallel to the axis of the duct. It will be oriented at right angles.

The flexible duct manufactured and shrunk as described above is transported to the place where it will be used, and at the piping site, it is stretched to the required length and piped, and bent along the bend. .

At this time, not only is there no displacement (sliding) of the seam part 14 due to twisting of the duct, but also the fifth
In either case, when a force in the compressive direction as shown in the figure is applied, or when a force in the elongation direction and bending force as shown in Fig. 6 is applied during piping, the seam 14 may be crushed or loosened. It never occurs.

Furthermore, since the seam portion 14 has a concave or convex cross section, its section modulus increases greatly, and therefore exhibits great rigidity against external forces from the outer circumferential direction.

[Effects of the Invention] Since the present invention is configured as described above, it produces effects as described below.

Since the seam part is pressed and formed into a valley or mountain shape, the shape of the valley or mountain shape not only prevents the seam part from shifting due to twisting of the flexible duct, but also prevents the compression applied to the duct. The occurrence of crushing, loosening, unraveling, separation, etc. of the seam joints due to external forces due to stretching and bending is significantly reduced, and as a result, the failure rate of the seam joints during piping as well as leak accidents due to stretching and bending of piping are reduced. Can be lowered to a wide swath.

In addition, since the manufactured flexible duct has a high compression rate, the space occupation rate is reduced accordingly, making it easier to handle, reducing shipping costs and requiring less storage space.

Furthermore, since the cross section of the seam is a valley or mountain shape with a quadruple structure, the section modulus is significantly larger than that of conventional ones, which makes it highly resistant to external forces from the outer circumferential direction. The duct as a whole is extremely durable.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the duct of the present invention in the manufacturing process, Fig. 2 is a schematic cross-sectional view of the same wall, Fig. 3 is a cross-sectional view of the seam, and Fig. 4 is a schematic cross-section of the wall in a compressed state. 5 is a sectional view of the seam in a compressed state, FIG. 6 is a sectional view of the seam in an expanded state, and FIG. 7 is a sectional view of the seam in a stretched state. 8 is a schematic sectional view showing the compressed state of the wall surface in the embodiment shown in FIG. 7; FIG. 9 is a sectional view of a conventional seam; FIG.
The figure is a cross-sectional view of the forming process of the seam shown in FIG. 9, and FIG. 11 is a cross-sectional view of another conventional example of the seam. 11...Thin metal plate, 12a, 12b...Side edge,
13a, 13b... end rib, 14... seam part, 15... valley shape, 16a, 16b... sloped surface,
17...Yamagata.

Claims (1)

[Claims] 1 A plurality of corrugated ribs parallel to the side edges of a thin metal plate of a predetermined width are formed, the thin metal plate is wound spirally, and adjacent side edges are connected by seams. What is claimed is: 1. A flexible duct characterized in that said seam-jointed seam portions are pressed and formed into a valley shape or a mountain shape.