JPH0251569B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to supports for various purposes such as agricultural and horticultural supports used to support plant vines, or fisheries supports used to support aquaculture nets. Regarding the manufacturing method.

For example, in the case of agricultural and horticultural supports, as illustrated in FIG. By covering the caps 3, 3 made of thermoplastic synthetic resin, the steel pipe is prevented from rusting and its durability is increased.

In the strut as illustrated in FIG. 1, if there is a gap at the joint between the cap 3 and the outer skin layer 2, rainwater will enter through the gap and the rust prevention effect of the steel pipe 1 will not be exhibited. The method by which the cap is attached to the end of the steel pipe 1 is important from the viewpoint of increasing the durability of the support.

Various methods have been proposed for attaching a cap to the end of a steel pipe coated with an outer skin layer, in addition to using adhesives, but a simple and quick method uses ultrasonic vibration. There is a way to do it.

In this method, as illustrated in FIG. 2, for example, a concave portion 1 is attached to a horn 110 attached to a vibration source 100 with an oscillation frequency of about 20 KHz and an output of about 500 W.
11, a cap material 31 made of thermoplastic synthetic resin is accommodated in this recessed portion 111, and the cap material 31 is ultrasonically vibrated by the excitation of the horn 110 accompanying the operation of the vibration source 100. , the steel pipe 1 provided with the outer skin layer 2 is pressed onto the cap material 31 from directly above. According to this method, the round-shaped end surface of the steel pipe 1 rubs violently against the upper surface of the cap material 31, and the upper surface of the cap material 31 softens due to the frictional heat generated during the rubbing, and the end surface of the steel pipe 1 accordingly. It has the advantage that the cap material 31 bites into the upper surface of the cap material 31 and the two are firmly welded together within a short period of 1 to 2 seconds.

However, this method has the following disadvantages.

That is, the steel pipe 1 provided with the outer skin layer 2 is hollow and thin, and the cap material 31 of the steel pipe 1 is
The biting into the cap material 31 occurs as the cap material 31 softens due to the frictional heat generated when the cap material 31 rubs against the steel pipe 1 due to ultrasonic vibration. Depending on the force, the steel pipe 1 may bite into the cap material 31 indefinitely. In such a situation, the manufactured strut will be in a state where the steel pipe 1 digs into the cap 3 more than necessary, as shown in Figure 3.
In severe cases, the end face of the steel pipe 1 may completely penetrate the cap 3, that is, the cap 3 may be completely fitted into the steel pipe 1. In these cases, the lengthwise dimension of the column is not constant,
The rust prevention effect provided by cap 3 may not be sufficiently exerted, leading to a significant decrease in product value.

The present invention was made in view of the above circumstances, and
By proposing a method for manufacturing columns that takes advantage of the advantages of the method using ultrasonic vibration and improves its disadvantages, the rust-preventing effect of the cap on the steel pipe as the core material will be fully demonstrated. The purpose of the present invention is to easily provide a support column that can be used for various purposes and has excellent dimensional accuracy.

That is, the method of the present invention, as shown in FIG.
The steel pipe 1 provided with the engaging portion 4 in this way is pressed against the ultrasonically vibrating cap material 31 in accordance with the method explained in FIG. It is to be applied to. In this case, the engaging portion 4 functions to prevent the cap material 31 from entering into the interior of the steel pipe 1 more than necessary when the steel pipe 1 is pressed against the cap material 31. Therefore, as shown in FIG. 4, if the disc-shaped engagement portion 4 is provided at a location slightly deeper than the round-shaped end face of the steel pipe 1, the steel pipe 1 can be held in a fixed position on the cap material 31 by the above-mentioned pressing. When the cap material 31 is bitten in only the depth
The upper surface of the middle portion of the grip contacts the engaging portion 4, and further biting is prevented. Therefore, the steel pipe 1 does not dig into the cap material 31 more than necessary, and the depth of the penetration is always set constant, so that in the manufactured strut, the steel pipe 1 is inserted into the cap material 31 as shown in Fig. 5. 3, the two are firmly welded together. In such a welded state, the end face of the steel pipe 1 is connected to the cap 3.
Since it is reliably covered with water, rust cannot occur due to the intrusion of rainwater, etc. Moreover, the dimensional accuracy of the support column is also improved.

In addition to the engaging portions shown in FIGS. 4 and 5, the engaging portions that perform the above-mentioned functions include metal pieces provided at one or more locations on the inner surface of the steel pipe 1 by spot welding 6, as shown in FIG. The engaging part 4 may be a fixed engagement part 4, or it may be another part. In short, any material may be used as long as it can prevent the cap material from entering the inside of the steel pipe more than necessary when the steel pipe is pressed against the cap material.

Next, a thermoplastic synthetic resin appropriately selected from polyvinyl chloride, polyethylene, etc. can be suitably used for the outer skin layer applied to the steel pipe, and a similar thermoplastic synthetic resin can also suitably be used for the cap material. . In that case, it is desirable that both be made of the same or a thermoplastic synthetic resin having good compatibility (compatibility). Further, the cap material may be a thermoplastic resin molded into a cap shape in advance, or may be a pellet shape. When a pellet-shaped cap material is used, it is preferable to use an engaging portion that is provided in advance on the steel pipe to close the inside of the steel pipe as shown in FIGS. 4 and 5.

As detailed above, the method of the present invention utilizes ultrasonic vibration to attach the cap material to the steel pipe provided with the outer skin layer, so it has the advantage that both materials can be firmly welded together easily and quickly. Another advantage is that the engaging portion provided in advance on the steel pipe can prevent the cap material from entering the inside of the steel pipe more than necessary. Therefore, it becomes possible to easily and quickly manufacture a highly durable support column in which the steel pipe is reliably rust-proofed and has excellent dimensional accuracy.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway side view showing the support column, Fig. 2 is an explanatory diagram showing the cap material application process using ultrasonic vibration as a comparative example, and Fig. 3 is a cap material manufactured through the same adhesion process. Fig. 4 is an enlarged sectional view showing the main part of the steel pipe used in the method of the present invention, and Fig. 5 is a cross-sectional view showing the main part of the support column manufactured by the method of the present invention. FIG. 6 is an enlarged cross-sectional view showing the main part of a modified example of the steel pipe used in the method of the present invention. 1...Steel pipe, 2...Outer skin layer, 3...Cap,
31... Cap material, 100... Source of ultrasonic vibration.

Claims (1)

[Claims] 1. By pressing the ring-shaped end face of a steel pipe coated with an outer skin layer made of thermoplastic synthetic resin against a cap material made of thermoplastic synthetic resin housed in the concave part of a horn that is excited by the operation of an ultrasonic vibration source. When the cap material is welded to the outer skin layer and attached to the end of the steel pipe, before the round-shaped end face of the steel pipe is pressed against the cap material, this pressing causes the cap material to move into the inside of the steel pipe. A method for manufacturing a support column, characterized in that an engaging portion for preventing the steel pipe from entering is provided inside the steel pipe.