JP3148048B2 - Manufacturing method of lining pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a lining pipe used as a piping material for a building, and more particularly, to a method for manufacturing a lining pipe in which a metal pipe such as a steel pipe is covered with a synthetic resin pipe. About the method.

[0002]

2. Description of the Related Art For the purpose of improving the corrosion resistance or chemical resistance of a metal pipe such as a steel pipe, a method of manufacturing a lining pipe whose inner surface is coated with a synthetic resin pipe has been roughly classified into the following two types. It has been known.

One of them is to prepare a metal tube and a synthetic resin tube having an outer diameter much smaller than the inner diameter of the metal tube, and apply an adhesive to each of the inner surface of the metal tube and the outer surface of the synthetic resin tube. After that, insert the synthetic resin tube inside the metal tube, soften the synthetic resin tube by heating from the outside in that state, and pressurize from inside the synthetic resin tube,
This is a method in which a synthetic resin tube is expanded and brought into close contact with the inner diameter surface of a metal tube so that the two tubes are adhered to each other (Japanese Patent Application Laid-Open No. 55-55).
-41246).

The other is to prepare a metal tube and a synthetic resin tube having an outer diameter smaller by a predetermined size than the inner diameter thereof, and apply an adhesive to each of the inner surface of the metal tube and the outer surface of the synthetic resin tube. After that, the synthetic resin tube is inserted into the metal tube, and the metal tube is mechanically reduced in diameter in this state, whereby the inner surface of the metal tube is brought into close contact with the outer surface of the synthetic resin tube so that both tubes are adhered to each other ( JP-B-42-26956).

[0005]

By the way, of the above-mentioned conventional manufacturing methods, in the former method, the air existing between the synthetic resin pipe and the inner surface of the metal pipe at the time of expansion is difficult to escape. Even after the bonding, air remains between the metal tube and the synthetic resin tube, which causes problems such as poor bonding and a phenomenon of "lifting" of the synthetic resin tube.

Further, in the latter conventional method, since the dimensions of the metal pipe after diameter reduction become the nominal (standard) dimensions of the manufactured lining pipe, a metal pipe having the standard dimensions cannot be used, and special dimensions of the metal pipes cannot be used. It is necessary to prepare a metal tube, and there is a disadvantage that the cost is increased. Further, in the case of manufacturing a large-diameter lining pipe, there is a problem that a large-scale apparatus is required for a step of reducing the diameter of the metal pipe, and the equipment cost becomes high.

The present invention has been made in view of such circumstances, and it is difficult to cause poor bonding and "lifting", and it is possible to use a metal tube having a standard size. It is an object of the present invention to provide a method of manufacturing a lining pipe without requiring large-scale equipment.

[0008]

In order to achieve the above object, a method for manufacturing a lining pipe according to the present invention is shown in FIG. After the metal tube 1 is applied, the metal tube 1 is heated to a temperature equal to or higher than the melting point of the hot-melt type adhesive 11, and the inside thereof has an outer diameter equal to or slightly smaller than the inner diameter of the metal tube 1. It is characterized by inserting the resin tube 2 with the hot melt type adhesive 21 applied to its outer surface.

[0009]

When the hot-melt adhesive 11 is softened by applying the hot-melt adhesive 11 to the inner surface of the metal tube 1, the inner diameter of the metal tube 1 is slightly increased due to the thermal expansion of the metal tube 1. Due to the lubricating action of the hot melt adhesive 11 which has become large and softened, it becomes possible to forcibly insert the synthetic resin pipe 2 having an outer diameter approximate to the inner diameter of the metal pipe 1.

The inner diameter of the metal tube 1 and the outer diameter of the synthetic resin tube 2 are close to each other, so that the step of reducing the diameter of the metal tube 1 or the step of expanding the synthetic resin tube 2 is unnecessary. Can be used, and the desired purpose can be attained without adhesion failure or "floating" phenomenon due to the residual air.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic sectional view showing the steps of an embodiment of the present invention. First, a metal pipe 1 such as a steel pipe and a synthetic resin pipe 2 such as a vinyl chloride pipe are prepared. The dimensions of the metal pipe 1 are of a standard having the same outer diameter as the nominal dimension of the lining pipe to be manufactured. Good. The outer diameter of the synthetic resin tube 2 is the same as or equal to the inner diameter of the metal tube 1.
Assuming that the outer diameter of the synthetic resin pipe 2 is D, the outer diameter of the synthetic resin pipe 2 is (D−
1) It is desirable that mm ≧ d ≧ D.

FIG. 1 shows the inner surface of such a metal tube 1.
As shown in (A), the hot-melt adhesive 11 is applied uniformly, and the outer surface of the synthetic resin pipe 2 is also applied to the same figure (B).
As shown in (1), the same type of hot melt adhesive 21 is applied uniformly.

Thereafter, the metal tube 1 is heated to a temperature not lower than the melting point of the hot-melt adhesive 11 by a heating furnace or an induction heating device or the like to soften the hot-melt adhesive 11 on the inner surface thereof.

Then, in this state, the synthetic resin tube 2 shown in FIG. 1B is forcibly pushed into the metal tube 1 and allowed to cool. Thus, a lining pipe having a structure shown in FIG. 1C in which the inner surface of the metal pipe 1 is lined with the synthetic resin pipe 2 via the adhesive 11 or 21 is obtained.

In the above steps, it should be noted that
When the synthetic resin tube 2 is inserted into the heated metal tube 1, the softened hot-melt adhesive 11 functions as a lubricant, and has an outer diameter approximate to the inner diameter of the metal tube 1. Even in the case of the tube 2, the point where the insertion is facilitated and the slight gap between the inner surface of the metal tube 1 and the outer surface of the synthetic resin tube 2 are filled with the softened hot-melt adhesive 11. Therefore, almost no air remains between the two pipes.

As the metal tube 1, a copper tube or an aluminum tube can be used in addition to a steel tube. As the synthetic resin tube 2, an arbitrary thermoplastic resin tube other than a vinyl chloride tube can be used. Obviously, the hot-melt adhesives 11 and 21 may be any known ones.

[0017]

As described above, according to the present invention,
After applying the hot-melt adhesive to the inner surface of the metal tube, the metal tube is heated to a temperature equal to or higher than the melting point of the hot-melt adhesive to soften the hot-melt adhesive. In order to obtain a lining pipe by forcibly inserting a synthetic resin pipe having an outer diameter equal to or slightly smaller than the inner diameter of the metal pipe with the hot melt type adhesive applied to its outer surface, Metal tubes can be of inexpensive standard dimensions,
The possibility of air remaining between the metal tube and the synthetic resin tube was extremely reduced, and a high-quality lining tube free from poor adhesion and "floating" could be obtained at low cost.

In addition, neither the step of reducing the diameter of the metal pipe nor the step of expanding the synthetic resin pipe as in the conventional manufacturing method is required, and simplification of manufacturing equipment and improvement in productivity can be achieved at the same time.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a process of an embodiment of the present invention in a schematic sectional view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal tube 2 Synthetic resin tube 11, 21 Hot melt type adhesive

Claims (1)

(57) [Claims] 1. A method for manufacturing a lining pipe comprising a metal pipe covered with a synthetic resin pipe, wherein a hot-melt adhesive is applied to an inner surface of the metal pipe, and the melting point of the hot-melt adhesive is not less than the melting point of the hot-melt adhesive. In a state where the metal tube is heated, a synthetic resin tube having an outer diameter equal to or slightly smaller than the inner diameter of the metal tube is inserted into the inside thereof in a state where a hot melt type adhesive is applied to the outer surface thereof. A method for producing a lining pipe.