JPH0258543B2 - - Google Patents

Description

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

[Conventional technology]

As a conventionally known flexible duct, there is one disclosed, for example, in 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. 7 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. 8, the above-mentioned seam part 1 is
One side edge 3 is bent at a right angle to form a rising part 4, and the other side edge 5 is placed over this rising part 4 and then folded in the direction of the arrow, and the whole is parallel to the axis of the duct. make a face 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. 9, there is a structure in which the seam 8 is folded over the inclined surface of one of the adjacent corrugated ribs 7 (Japanese Patent Laid-Open No. 50-154157). Public bulletin).

In order to make the above-mentioned flexible duct compact during transportation, it is compressed in the axial direction after manufacturing to the extent that the ribs contact 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.

[Problem that the invention seeks to solve]

As mentioned above, although this type of flexible duct is inevitably subjected to compression, elongation, and bending, the material is quite thin, so the seams are crushed during compression deformation, and the material is also subject to elongation and bending. Occasionally, the seams may become loose and may even partially separate, resulting in so-called disintegration.

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

Therefore, the present invention provides an extremely strong flexible duct that increases the strength of the seam portion and does not collapse or loosen when compressed, stretched, or bent.

[Means for solving problems]

This invention provides a flexible duct having a seam part, in which the seam part is formed into a substantially S-shaped cross section with one peak and one valley, and both ends of the flexible duct are located in the middle of the sloped surfaces of the end ribs on both sides. It is a smooth continuation of the .

〔Example〕

The flexible duct of the embodiment shown in FIGS. 1 to 3 is similar to the conventional one, in which a plurality of corrugated ribs 13 parallel to the side edges 12a, 12b of a thin metal plate 11 of a predetermined width are formed on a forming roller. This is formed into a pipe shape by winding it spirally on a core metal and joining adjacent side edges 12a and 12b with a seam joint.

The seam portion 14 between the side edges 12a and 12b is
As shown in FIGS. 2 and 3, in the state after manufacture, it is bent into a substantially S-shape with a pitch that is almost the same as the pitch of the ribs 13. The seam portion 14 herein refers to the area where four thin metal plates 11 overlap.

The above-mentioned seam portion 14 is formed into a substantially S-shaped cross section having one peak 15 and one valley 16, and the end on the valley 16 side is connected to the terminal rib 13a on one side edge 12a ( The slope (the slope seen from the seam portion 14 is an upward slope) continues smoothly in the middle of the slope surface 17a. Furthermore, the end of the seam 14 on the mountain 15 side is a downward slope of the terminal rib 13b on the other side edge 12b (as seen from the seam 14).
It continues smoothly in the middle of the inclined surface 17b.

The above-mentioned seam part 14 is formed on the core metal up to the middle through a molding process that is almost the same as the conventional molding method shown in FIGS. It is press-formed into an approximately S-shape using special forming rollers inside and outside.

In the flexible duct manufactured as described above, each rib 13 is formed with a constant pitch, so if it is transported and stored as is, the space occupation rate is high. Therefore, as shown in FIG. 4, the distance between the ribs 13 is usually reduced by compressing it in the axial direction, thereby shortening the entire length of the flexible duct. The shortening rate is about 1/4, and for example, a pipe length of 4 m can be shortened to 1 m. In addition, at the piping site where this is used, the pipe is stretched to the required length and bent along the bend.

Furthermore, the metal thin plates used in this invention refer to ordinary steel plates, stainless steel plates, aluminum foil, etc., with a thickness of about 0.08 mm to 0.20 mm, and the maximum elongation rate is the length of time during pipe manufacturing. This is an increase of about 20%.

The ridges 15 and troughs 16 of the seam 14 configured as described above are strongly pressed during molding, resulting in a strong integration similar to that achieved by crimping. Therefore, not only is there no deviation (sliding) due to twisting of the duct, but also when a force is applied in the compression direction as shown in Figure 5, or when a force in the extension direction is applied as shown in Figure 6. Even in this case, the seams 14 do not collapse or loosen, maintaining a high degree of connection.

Note that when the pipe is bent, the force in the compression direction and the force in the extension direction act.

〔Effect of the invention〕

Since the flexible duct of the present invention is as described above, there is no crushing, loosening, unraveling, separation, etc. of the seam joints due to compression, stretching, or bending, and therefore, there is no defective rate at the seam joints and leakage accidents. can be significantly reduced. Furthermore, the compression rate for reducing the space occupation rate can be increased compared to the conventional method.

Furthermore, since the section modulus of the seam section is significantly larger than that of conventional ones, it exhibits extremely high rigidity against external forces from the outer circumferential direction, making the duct as a whole extremely durable.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the manufacturing process of the duct of the present invention, Figure 2 is a schematic sectional view of the same wall surface, and Figure 3 is a schematic sectional view of the same wall surface.
4 is a schematic sectional view of the wall surface in a compressed state, FIG. 5 is a sectional view of the seam in a compressed state, and FIG. 6 is a sectional view of the seam in an expanded state. 7 is a sectional view of a conventional seam, FIG. 8 is a sectional view of the forming process of the seam in FIG. 7, and FIG. 9 is a seam of another conventional example. FIG. 11...Thin metal plate, 12a, 12b...Side edge,
13a, 13b...End rib, 14...Seam portion, 15...Mountain, 16...Valley, 17a, 17b...
...Slope.

Claims (1)

[Claims] 1 A thin metal plate of a predetermined width is formed with a plurality of corrugated ribs parallel to its side edges, the metal thin plate is wound spirally, and adjacent side edges are joined by a seam. In the flexible duct, the above-mentioned seam portion is formed into a substantially S-shaped cross section with one peak and one valley, and both ends thereof are smoothly connected to the middle of the sloped surfaces of the end ribs on both sides. Flexible duct.