JPS59192552A - Method of coating pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pipe coating method for coating a resin pipe with an adhesive on a pipe to be coated made of a metal pipe such as a steel pipe.

Generally, the inner peripheral surface of an S pipe for water supply or the like is coated with a resin pipe.

Conventionally, in order to coat the inner circumferential surface of a steel pipe with a resin pipe as described above, as shown in FIG. It is closed with a stopper 3 made of material, etc., and the steel pipe 1 is closed in this state.
was heated with gas burner 11. Since the above-mentioned steel pipe 1 is configured to be heated while rotating, the steel pipe 1
is heated almost uniformly, and due to this heating, the resin pipe 2
The air inside expands and the outer circumferential surface of the pipe is pressed against the inner circumferential surface of the steel pipe 1, and the adhesive 7 applied in advance to the outer circumferential surface layer of the resin pipe 2 is melted by the heating and the resin pipe 2 is made of resin. The pipe 2 is pressed and bonded to the inner peripheral surface of the steel pipe 1. still,
Reference numeral 12 is a cock of the gas burner 11.

By the way, generally this kind of steel pipe is often long, 5 m to 6 m, and therefore it is difficult to heat it uniformly over its entire length. This has the disadvantage of causing wrinkles in the resin pipe 2 due to the heating, and also that the internal pressure of the resin pipe 2 becomes uneven due to uneven heating, resulting in insufficient adhesion. Ta. This poor adhesion was noticeable at the tube ends.

The present invention eliminates the above-mentioned conventional drawbacks, and provides a pipe coating method that can sufficiently adhere a resin pipe to the inner circumferential surface of a pipe to be coated, such as a steel pipe, and can coat the resin pipe uniformly. A metal pipe with one end substantially closed is attached to both ends of the coated pipe to create a substantially sealed state, and in this state, the pipe to be coated is heated by induction heating. .

An embodiment of the present invention will be described below with reference to the drawings. Second
In the figure, 1 is a steel pipe, 2 is a resin pipe, and t
An adhesive 7 is applied to the outer peripheral surface layer of the TI-pipe, and the pipe is shown inserted into the steel pipe 1. A metal pipe 4 with one end closed is attached to both ends of the pipe 2 by screwing or press fitting, so that the inside of the pipe 2 is sealed. Reference numeral 5 denotes a well-known induction heating coil, which has a substantially cylindrical shape, into which the steel pipe 1 described above is inserted.

When high-frequency power is supplied to the induction heating coil 5 and the temperature of the steel pipe 1 is raised to 150°C to 200°C, the heat is also transferred to the pipe 2 inside, causing the air inside the pipe to expand. The outer circumferential surface of the pipe is pressed against the inner circumferential surface of the H-tube 1, and the adhesive 7 on the outer circumferential surface layer of the pipe is melted to adhere and coat the pipe 2 onto the inner circumferential surface of the steel pipe 1.

In the above embodiment, the induction heating coil 5 having a length approximately equal to the entire length of the steel pipe 1 was used, but when using the induction heating coil 5 shorter than the steel pipe 1 as shown in FIG. The net pipe 1 and the induction heating coil 5 may be relatively moved by moving either one or both of the mesh pipe 1 and the induction heating coil 5.

Further, the metal pipe 4 may be provided with an air vent plug 3 as shown in FIG. 4, or as shown in FIG.
By providing a pressure control valve 6, the internal air pressure of the pipe 2 may be controlled. As a result, it is expected that the adhesiveness will be stabilized and the quality will be improved accordingly.

In the above embodiment, the steel pipe 1 is used as the pipe to be coated.
Although the explanation has been given as an example, the same effect can be obtained even in the case of metal pipes made of other materials by changing the electrical conditions of the induction heating coil 5.

This invention heats the steel pipe 1 using the above-mentioned induction heating, and by simply adjusting the electrical conditions such as voltage or frequency in response to changes in the outer diameter or wall thickness of the steel pipe, a stable and arbitrary In addition to the conventionally known effects of induction heating, such as not only being able to control the set temperature of the pipe 2 but also being able to heat even long steel pipes without rotating them, By attaching a metal pipe 4 whose one end is substantially closed, the following effects can be obtained.

That is, in general, an unstable temperature phenomenon called the terminal effect occurs at the ends of the steel pipe 1, in which the temperature is overheated or not raised from the center, which may result in poor adhesion of the ends of the steel pipe 1. However, by installing the metal pipe 4, it is possible not only to increase the air pressure inside the pipe 2, but also to concentrate the disturbance of the magnetic flux at the end of the steel pipe 1 on the metal pipe 4. It is possible to eliminate temperature unevenness at the end of the

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the conventional pipe coating method.
FIG. 2 is a configuration diagram for explaining an embodiment of the present invention,
FIG. 3, FIG. 4, and FIG. 5 are configuration diagrams for explaining other different embodiments. 1: Steel pipe, 2: Resin pipe, 4: Metal pipe, 5:
Induction heating coil, 7: Adhesive. Agent Masuo Oiwa

Claims (1)

[Claims] A resin pipe with an adhesive applied to the outer peripheral surface layer is inserted into the pipe to be coated and heated, and the heating expands the air inside the resin pipe to coat the outer peripheral surface of the resin pipe with the pipe to be coated. In addition, when melting the adhesive and bonding the resin pipe to the inner peripheral surface of the pipe to be coated, induction heating is used as the heating means, and both ends of the resin pipe are bonded to the inner peripheral surface of the pipe to be coated. A pipe coating method characterized in that a metal pipe with one end substantially closed is attached to the pipe, and induction heating is performed in a substantially sealed state.