JPS582811B2 - Manufacturing method of spirally wound synthetic resin pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a spirally wound pipe made of thermoplastic synthetic resin, particularly a pipe of small diameter.

Conventionally, when molding a spirally wound pipe made of thermoplastic synthetic resin, a metal core material having a radial expansion and contraction mechanism has been used.

That is, a molten thermoplastic synthetic resin band extruded from an extruder while being heated (120 to 150°C) is spirally wound around the core material with its sides overlapped, and then cooled and solidified.

Thereafter, the diameter of the core material is reduced and the core material is removed from the pipe.

The metal core material having the above-mentioned radial expansion/contraction mechanism is expensive to manufacture, and is extremely difficult to manufacture if it has a small diameter and long length.

The present invention solves the above-mentioned problems and solves the problems described above.
The purpose of the present invention is to easily and inexpensively manufacture a spirally wound pipe (0 to φ300 mm).

That is, the present invention has achieved the above object by using a core material 1 as shown in FIG.

This core material 1 is made by spirally wrapping a metal band 2 as shown in FIG. 2 around the outer surface of a paper tube 3 while abutting its sides.

The core material 1 is mounted on a rotating table and supported at both ends, as shown in FIG.

The surface of the core material 1 is heated (100 to 130°C), and the extruder 4
A thermoplastic synthetic resin band 5 in a molten state extruded from the core material 1 is spirally wound around the core material 1 with their sides overlapped.

At the time of winding, a roll 6 is pressed against the overlapped side portions of the synthetic resin band 5, and the overlapped portions are welded to form a pipe.

After cooling and solidifying, the pipe is removed from the rotary table together with the core material 1.

The paper tube 3 is removed after being soaked with water to swell and soften.

After that, the metal band 2 attached to the inner wall of the pipe is
By pulling the end, it is easily peeled off, and the removal of the core material 1 is completed.

FIG. 4 shows a pipe 7 manufactured according to the present invention.

Using a paper tube with a thickness of 10 mm, an outer diameter of 100 mm, and a length of 2000 mm, the present invention was carried out to mold a high-density polyethylene resin pipe with a wall thickness of 25 mm, and the results were very good.

That is, (1) it is easy to remove the paper tube and metal band;
There were no remaining paper pieces on the inner surface of the pipe.

(2) There is no unevenness on the inner surface of the pipe due to gasification of moisture absorbed by the paper pipe, which occurs when a molten synthetic resin band is directly wrapped around the paper pipe.

(3) The inner surface of the pipe had good gloss, similar to when a metal core material was used.

As described above, in the present invention, a metal band is spirally wound around a paper tube to serve as a core material, so that even in the case of a small-diameter pipe, it is very easy to remove it by simply swelling the paper tube.

Furthermore, since the core material does not have a radial expansion/contraction mechanism like the conventional one, it is very inexpensive and can reduce manufacturing costs, so the industrial value of the present invention is extremely high.

[Brief explanation of drawings]

Figure 1 is a partially cutaway sectional view of the core material used in the present invention;
Figure 3 is a perspective view of the metal band constituting the core material, Figure 3 is a plan view showing the state in which the synthetic resin band is spirally wound around the core material, and Figure 4 is a partially cutaway cross section of a pipe manufactured according to the present invention. It is a diagram. 1 is a core material, 2 is a metal band, 3 is a paper tube, 4 is an extruder, 5 is a synthetic resin band, 6 is a roller, and 7 is a pipe.

Claims (1)

[Claims] 1 A core material is formed by spirally winding a metal band around the outer circumferential surface of a paper tube while abutting its sides, and a molten synthetic resin band extruded from an extruder is wrapped around the core material while abutting its sides. 1. A method for manufacturing a spirally wound synthetic resin pipe, which comprises forming a pipe by spirally winding the pipes, cooling and solidifying the pipe, and then moistening the paper pipe and removing the paper pipe and metal band.