JPH0434014Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention is a round resin-coated material with a flat surface that can be used as a lightweight aggregate for products that require a flat surface, such as curbs and drainboards. In the field of technology for manufacturing metal pipes (hereinafter simply referred to as pipes) or manufacturing the products mentioned above using the same pipes, it is carried out for the purpose of rust prevention of the inner surface of the pipe cut to a desired length and aesthetic treatment of the cut surface. The present invention relates to a structure for attaching a cap to an end surface of a pipe, and more particularly to a structure for welding a thermoplastic synthetic resin cap to an end surface of a pipe by applying the principle of ultrasonic welding.

BACKGROUND ART A pipe 2 whose basic shape in cross section is circular but has a flat portion is known, for example, as described in Japanese Utility Model Application Publication No. 121315/1983. As illustrated in Fig. 6, this is achieved by coating a thermoplastic synthetic resin 22 such as AAS on the outer peripheral surface of a thin-walled steel pipe 23 with a thickness of about 0.7 mm.
It is manufactured to have an outer diameter of φ28 to φ32 by covering it in a uniform layer of about mm. Then, the coating resin layer 22
The thickness of a part of the flat part 2 is increased and flattened.
1 is formed. The inner circumferential surface of the steel pipe 23 is coated with an anticorrosion paint to perform antirust treatment. Therefore, when this pipe 2 is used, the surfaces to be used on edge stands, drainboards, etc. can be formed flat, making them more comfortable to use. Of course, it is suitable for use outdoors or in the bathroom where it is exposed to rainwater.

Since the cut end of the steel pipe 23 is exposed at the cut end surface of the pipe 2, this becomes a weak point in terms of rust prevention. Furthermore, burrs and the like appear in a disordered manner on the cut ends of the steel pipe 23 and the coating resin 22, which is dangerous, and the openings are visible, which is aesthetically undesirable.

Conventionally, a cap 1 as shown in FIGS. 7 and 8 is attached and fixed to the cut end of the pipe 2 as shown in FIG. 9 for sealing. The cap 1 has a skirt-like portion 12 that tightly circumscribes the outer peripheral surface of the circular tube portion and the flat portion 21 of the pipe 2.
It is molded from thermoplastic synthetic resin such as AAS, which is the same material as 2. In many cases, the coating resin 22 of the pipe 2 and the cap 1 circumscribed thereto are
Attachment and fixation (adhesion or fixation, hereinafter the same) is performed by injecting a solvent-based adhesive through the gap in the skirt-like portion 12 of the cap 1 or by applying a glue-like dope-like adhesive. .

Alternatively, resins may be welded together using frictional heat by applying ultrasonic vibrations. When carrying out this ultrasonic welding method, the cap 1 has a width extending along the entire circumference of the inner end surface along the skirt portion 12.
A welding step 11 of approximately 0.7 mm and height of 1.3 mm is formed, and welding is performed using this as a welding margin.

Problems to be Solved by the Present Invention The pipe 2 having the plane portion 21 has a coating resin layer 2
The shrinkage rate of the flat part 21 formed as the thick part of 2 is large, and it is difficult to uniformly and reliably mold the width, thickness, and shape of the flat part 21. However, since the steel pipe 23 serves as the core material in the circular pipe portion, it is easy to obtain molding accuracy.
On the other hand, even with the same synthetic resin molded product, cap 1 has less variation in wall thickness, making it easier to obtain molding accuracy. Therefore, as shown in FIG.
It is often the case that a gap S is created by oversizing.

It is nearly impossible to bond such a gap S with a solvent-based adhesive, and since the gap remains as it is, it is difficult to ensure complete sealing by the cap 1, which is a problem.

Furthermore, even when using the ultrasonic welding method, the cut end surface of the pipe 2 is at the welding step 11 at the location of the gap S.
The cap may come off or shift, resulting in a lack of stability and reliability for welding the cap, and gaps remain, making it difficult to achieve complete sealing (watertightness). Moreover, there was also the problem that the melted resin leaked out from the gap S, spoiling the aesthetic appearance.

On the other hand, in the case of the cap 1 mounting structure using the above-mentioned dope-like adhesive, although the highly viscous dope-like adhesive fills the gap S and works to improve watertightness, the problem is that the workability is poor. There is.

Means for Solving the Problems As a means for solving the problems of the prior art described above, a cap mounting structure for a round pipe having a flat portion according to the present invention is shown in FIGS. 1 to 5 of the drawings. As shown in the embodiment, in a cap mounting structure in which a synthetic resin cap is attached by ultrasonic welding to seal the cut end of a round resin-coated metal pipe having a flat surface, the cap 1 has a flat surface. The round pipe 2 has skirt-like portions 12 and 12' that substantially circumscribe the outer peripheral surface of the circular tube portion and the flat portion 21.

(b) On the rear end surface of the cap 1, there is a welded step portion 1 consisting of a scraped welded portion and a crushed welded portion that come into contact with the resin layer 22 coated on the outer periphery of the steel pipe 23.
1 is formed in a circular shape over the entire circumference.

(c) Moreover, welding step portions 11' are formed at positions on the inner end surface along the skirt-like portion 12' circumscribing the flat portion 21 at each location where the flat portion 21 of the pipe 2 is connected.

D. This cap 1 has a structure in which each welded step part 11, 11' is melted and welded to the pipe 2 by ultrasonic vibration.

Effect When ultrasonic vibration is applied to the fitted cap 1 and pipe 2, the resin layer 22 coated on the outer periphery of the steel pipe 23 will be moved to the circular welded step 11 in contact with the resin layer 22.
Frictional heat is generated between the two, causing them to melt and weld together over the entire circumference, creating a complete sealing effect (watertightness).

On the other hand, in the cap 1, the welded step part 11' located along the skirt-like part 12' circumscribing the flat part 21 of the pipe 2 is connected to the flat part 21 of the pipe 2.
In the limit (range) where cap 1 and pipe 2 come into contact, they are melted by the ultrasonic vibrations, resulting in partial welding (dot bonding), which integrates cap 1 and pipe 2, increasing the installation strength. .

Example Next, the illustrated embodiment of the present invention will be described.

FIG. 1 shows the structure of an improved cap 1, in which a circular pipe portion of a pipe 2 having a flat portion 21 and a shallow skirt-like portion 12 substantially circumscribing the outer peripheral surface of the flat portion 21 have a uniform wall thickness. It is formed of.
The back end surface of the cap 1 has a scraped welded part and a crushed welded part of a shape and size (see FIG. 2) that come into contact with the resin layer 22 coated on the outer peripheral surface of the steel pipe 23 of the pipe 2 with a substantially uniform width. A welded step portion 11 consisting of is formed in an annular shape over the entire circumference. Of this welded step 11, the one formed at the corner between the inner end surface of the cap 1 and the skirt-like portion 12 is the cut-off welded step, and the other part shown in FIG.
As instructed, a strip with a width of 0.7 mm in the radial direction of the cap and a height of about 1.3 mm is formed on the rear end surface of the cap so that it touches the circular part of the pipe away from the skirt-like part and is crushed and welded. It is a stepped section.

In the pipe 2, the resin layer 22 of the circular pipe portion (steel pipe 23) is formed to be relatively thin, about 1 mm, and uniform in thickness. Since the inner steel pipe 23 serves as a core material, the forming precision is high, and the welded step portion 11 reliably and almost exactly abuts over the entire circumference. Therefore, when ultrasonic vibration is applied to the fitted cap 1 and pipe 2, welding of the resin occurs almost uniformly over the entire circumference of the steel pipe 23 (Fig. 4), making it possible to install the cap in a completely sealed manner. It will definitely come true.

On the other hand, in the cap 1, along the skirt-like portion 12' circumscribing the outer circumferential surface of the flat portion 21 of the pipe 2, at the position of the inner end surface thereof, especially from the side edge on the flat portion 21 of the pipe 2 to the outer edge. A welded step portion 11' having an appropriate line length is formed in a substantially L-shape that is bilaterally symmetrical. This welded step 11'
The shape and size of the welded step portion 11 of the circular tube portion are approximately the same (see FIG. 3).

Therefore, when ultrasonic vibration is applied to the cap 1 and the pipe 2 that are fitted together, the cut end of the flat part 21 will be completely welded with a seal as described above at the same time as the circular pipe part will be welded together as described above. Also, the part that comes into contact with the welded step 11' melts the welded step 11' and causes local welding (dot spotting), thereby further increasing the bonding strength between the cap 1 and the pipe 2. It tightens it.

Second Embodiment The cap 1 shown in FIG. 5 is for a pipe 2 having downward hanging walls on both sides of the flat part 21, and the welding with such a flat part can be made more securely and strongly. In order to do this, weld step part 1 for spotting.
1' is located in the cap 1 along the inner end of the skirt-like portion 12' that circumscribes the flat surface of the pipe 2, and at a position along the upper and lower edges of the skirt-like portion 12' and the side edges of the hanging wall portion. They are arranged in a symmetrical arrangement. The rest of the structure is the same as that of the first embodiment, and the cap 1 and pipe 2 can be similarly welded by ultrasonic vibration.

Effects of the present invention As described in detail above in conjunction with the embodiments, the structure for attaching a cap to a pipe having a flat surface according to the present invention is as follows:
The welding step 11 of the cap 1 that comes into contact with the welding step 11 is easily and reliably welded to a completely sealed state over the entire circumference using frictional heat generated by ultrasonic vibration, which prevents rust on the inner surface of the pipe. 100% of the purpose
Installation can be accomplished. Therefore, the pipe 2 having this flat portion can be suitably used as a structural member constituting an edge stand exposed to rainwater or a drainboard in a bathroom.

In addition, the flat part 21 of the pipe 2 and the cap 1 are connected at each position of the locally provided welded step part 11'.
In addition, since the welding step 11' is fused to the limit, there are no bubbles caused by air entrapment, and the attachment strength of the cap 1 to the pipe 2 is extremely large and perfect, so it is not necessary to roughly It withstands use well.

Moreover, it is highly responsive to dimensional errors and shape variations between the flat part 21 and the cap 1 caused by shrinkage distortion of the synthetic resin, and even if there is a gap, there is no inconvenience such as molten resin leaking from there, and the appearance is This allows for clean cap installation, expands the uses of pipes with flat parts, and contributes to improving the aesthetic appearance of the product.

[Brief explanation of the drawing]

Figure 1 is a front view showing the improved cap according to this invention, and Figures 2 and 3 are -
, - A cross-sectional view as seen from the arrow, Fig. 4 is a cross-sectional view of the cap attached to the pipe, Fig. 5 is a front view showing different embodiments of the cap, and Fig. 6 is an example of a round pipe with a flat part. Figures 7 and 8 are perspective and front views of conventional caps, Figure 9 is a perspective view of the cap attached to the pipe, and Figure 10 is a plan view of the cap and pipe. FIG. 3 is a perspective view illustrating a state of mismatch in size and shape with the other parts. 2...Pipe, 21...Plane part, 23...Steel pipe, 22...Coating resin, 1...Cap, 12...
...Skirt-like portion, 11, 11'...Welded stepped portion.

Claims (1)

[Scope of Claim for Utility Model Registration] In a cap mounting structure in which a synthetic resin cap is attached by ultrasonic welding to seal the cut end of a round resin-coated metal pipe having a flat surface, I cap 1 is , has a skirt-like part 12 that circumscribes the circular pipe part 2 having a flat part 21 and the outer peripheral surface of the flat part 21 almost exactly, and (b) the inner end surface of the cap 1 is coated with the outer periphery of a thin-walled steel pipe 23. A welded step part 11 consisting of a scraped welded part and a crushed welded part that comes into contact with the resin layer 22 that has been removed is formed over the entire circumference,
At the position of the rear end surface along <the flat part 21 of the pipe
A welded step 11' is formed at each location to be marked, and (d) this cap 1 is welded to the pipe 2 by melting each welded step 11, 11' by ultrasonic vibration. Each features a round pipe cap mounting structure with a flat surface.