JPH0418536B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a composite pipe in which an outer pipe such as a hume pipe, a metal pipe, an asbestos pipe, etc. is lined with a synthetic resin inner pipe, and a method for manufacturing the same.

(Prior art) Composite pipes, in which outer pipes such as hume pipes and metal pipes are lined with synthetic resin inner pipes, have traditionally been used as water and sewage pipes buried underground or as fireproof pipes for sewage in high-rise buildings. ing.

Various methods have been known for manufacturing composite pipes, and the applicant of the present invention previously proposed the most advanced method for manufacturing composite pipes in Japanese Patent Application Laid-Open No. 59-5049.

The method for manufacturing this composite pipe will be explained below based on FIGS. 5 and 6.

The outer tube 1', such as a fume tube or a metal tube, has an enlarged diameter socket 11' at one end, and a stepped opening 12' having a reduced diameter at the other end. A heat-expandable synthetic resin inner tube 2' whose outer circumferential surface has been coated with heat-sensitive adhesive in advance is inserted into the outer tube 1', and a mold 7' and a closing plate 8' are placed at the ends of the inner tube 2'. Then, the inner tube 2' is set inside the outer tube 1'.

Next, a heating medium such as steam is introduced into the inner tube 2' to enlarge its diameter, and the inner tube 2' is brought into close contact with the inner peripheral surface of the outer tube 1'.

After that, remove the mold 7' and the closing plate 8',
After cutting the inner tube 2' at the end of the socket 11', the sixth
As shown in the figure, an inner mold 9' was press-fitted into the socket to bring the inner tube 2' into close contact with the inner peripheral surface of the socket 11'.

(Problems to be Solved by the Invention) However, this conventional manufacturing method has the disadvantage that it requires a heating medium to heat and expand the synthetic resin inner tube, which requires a large amount of equipment. An increase in product costs was inevitable. Further, when a Huum tube is used as the outer tube, there is a drawback that the performance of the Huum tube is degraded due to the thermal influence of the heating medium.

Moreover, the composite tube obtained in this way has an outer tube and an inner tube that have different coefficients of thermal expansion and are joined via adhesive, so when this composite tube is used as piping for transporting high-temperature fluids, In this case, when the inner tube thermally expanded in the radial direction, the outer tube or the inner tube could be damaged.

(Means for Solving the Problems) The present invention solves all of the problems that conventional composite pipes have had, and provides a composite pipe that will not be damaged by the influence of heat. In addition, the present invention provides a method for manufacturing a composite pipe in which the lining process can be performed quickly and reliably without requiring special equipment.

That is, the first invention of the present application is characterized in that an inner tube 2 made of synthetic resin is inserted into an outer tube 1, and a foamable adhesive 3 is interposed between the outer tube 1 and the inner tube 2. Located in a composite pipe.

The second invention has an outer tube 1 which has an enlarged diameter socket 11 at one end and a spigot 12 at the other end, and has an outer diameter slightly smaller than the inner diameter of the outer tube 1; A synthetic resin inner tube 2 having an enlarged diameter portion 21 with an outer diameter slightly smaller than the inner diameter of the socket 11 is inserted, and a foamed adhesive 3 is interposed between the outer tube 1 and the inner tube 2. 12 is a composite tube characterized in that its outer peripheral surface is integrally covered with an inner tube 2 which is inverted from the spout end.

The third invention includes an outer tube 1 having an enlarged diameter socket 11 at one end and a spigot 12 at the other end, and an outer tube 1 having an outer diameter slightly smaller than the inner diameter of the outer tube 1 and having the socket at one end. A synthetic resin inner tube 2 having an enlarged diameter portion 21 with an outer diameter slightly smaller than the opening 11 is prepared, and a foaming adhesive 3 is applied to the inner circumferential surface of the outer tube 1 or the outer circumferential surface of the inner tube 2, and then the outer tube 2 is prepared. The inner tube 2 is inserted into the tube 1, the outer tube 1 and the inner tube 2 are closely joined by foaming the adhesive 3, and then, or at the same time as the foaming and joining, the inner tube 2 is inserted into the tube 1. The method for manufacturing a composite tube is characterized in that the end portion 22 of the inner tube 2 is heated and softened and turned over in the outer circumferential direction, and the outer circumferential surface of the spout 12 is integrally covered with the inner tube 2.

Embodiment 1 FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the present invention, in which reference numeral 1 indicates an outer pipe such as a hume pipe, metal pipe, asbestos pipe, etc., and 2 indicates a vinyl chloride resin, polyethylene resin, polypropylene resin, etc. This is a synthetic resin inner tube made of resin or the like.

The outer tube 1 has an enlarged diameter socket 11 at one end, and a stepped opening 12 having a reduced diameter at the other end. An inner tube 2 having an enlarged diameter portion 21 at one end is inserted into the outer tube 1, and the outer tube 1 and the inner tube 2 are tightly bonded with a foam adhesive 3 interposed between the outer tube 1 and the inner tube 2. ing. Further, the outer circumferential surface of the spout 12 is integrally covered with the end 22 of the inner tube 2 that is reversed from the spout end.

The gap between the outer tube 1 and the inner tube 2, that is, the thickness of the foam adhesive 3, can be selected appropriately depending on the material of the outer tube 1, its inner diameter, etc., but is generally set appropriately in the range of 0.5 to 5 mm. good.

Next, the manufacturing process of this composite pipe will be explained based on the longitudinal sectional view shown in FIG.

First, an outer tube 1 is prepared which has an enlarged-diameter socket 11 at one end and a spigot 12 whose diameter is reduced with a step on the outer periphery of the other end.

On the other hand, the inner tube 2 lining the outer tube 1 has an outer diameter slightly smaller than the inner diameter of the outer tube 1, and has an outer diameter slightly smaller than the inner diameter of the outer tube 1.
One end of the inner tube 2 is enlarged to form an enlarged diameter portion 21 having an outer diameter slightly smaller than the inner diameter of the socket 12. The enlarged diameter portion 21 may be formed by any conventionally known method or means.

Next, after applying the foaming adhesive 3 to a uniform thickness on either one or both sides of the inner peripheral surface of the outer tube 1 or the outer peripheral surface of the inner tube 2, the outer tube is Insert inner tube 2 into 1.

As the foamable adhesive used in the present invention, a two-component adhesive in which a polyester resin and an isocyanate resin are bonded to each other to form a polyurethane resin is suitable, and this adhesive is foamed at room temperature. to fill the space between the outer tube 1 and the inner tube 2 (upper half of FIG. 4).

Thus, after lining the inner peripheral surface of the outer tube 1 with the inner tube 2 or simultaneously with the foam bonding, the end 2 of the inner tube 2 protruding from the end of the spout 12 of the outer tube 1
2 is heated and softened and turned over.

In this reversal process, pressing dies 5 and 6 are used,
As shown in the lower half of FIG. 4, first, a pressing die 5 is applied to the end portion 22 to form a flange. Next, the pressing mold 6 is moved in the axial direction to invert the end portion 22 and bring it into close contact with the outer circumferential surface of the spout 12 .

At this time, it is preferable to apply an adhesive to the outer peripheral surface of the spout 12 in advance.

The composite tube thus obtained is one in which the spigot of one tube is inserted into the socket of the other tube, and the spigot of the other tube is inserted and joined sequentially via adhesive, and the spigot is inserted into the tip of one of the sockets. It is chamfered for ease of use, and the other spout is formed to have an outer diameter approximately equal to the inner diameter of the socket.

Embodiment 2 FIG. 2 is a sectional view of a main part showing another embodiment of the present invention, in which a rubber ring type socket is adopted as the expansion socket. An annular groove 211 is provided in the inner tube 2 that covers the inner peripheral surface of the socket 12, and a packing P is attached to the groove 211, and a spigot similar to that shown in FIG. 1 is provided at the other end. .

In the case of the composite pipe of this embodiment, the socket of one pipe is inserted into the socket of the other pipe, and the pipes are connected via packing P so as to be expandable and retractable.

Embodiment 3 FIG. 3 is a sectional view of a main part showing another embodiment of the present invention, in which a socket similar to that shown in FIG. 1 is provided at one end of the composite pipe, and the difference between the other end is An annular groove 221 is provided on the outer periphery of the mouth, and a packing P is attached to the groove 221.

In this embodiment as well, the pipes are telescopically connected via packing P, as in the previous embodiment.

(Operations and Effects of the Invention) The method for manufacturing a composite pipe of the present invention includes preparing an outer pipe and an inner pipe that matches the shape of the inner circumference of the outer pipe, Since it is only necessary to apply an adhesive having a .

Therefore, the cost of the product can be significantly reduced.

Since the composite pipe manufactured in this way has a foaming adhesive between the outer pipe and the inner pipe, even when this composite pipe is used as a high-temperature fluid transport pipe, the diameter of the inner pipe Directional thermal expansion is absorbed by the foam adhesive so that neither the outer tube nor the inner tube is damaged.

In addition, composite pipes that simply have a foam material interposed between the outer pipe and the inner pipe are susceptible to damage due to the inner pipe slipping during transport or storage, or when used as vertical piping in high-rise buildings. When connecting the outer tube and the inner tube, the outer tube and the inner tube may become misaligned, making it impossible to connect them. However, since the composite tube of the present invention has the outer tube and the inner tube bonded together, such inconveniences can be avoided. will not occur.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a composite pipe showing one embodiment of the present invention, FIGS. 2 and 3 are sectional views of essential parts showing other embodiments of the present invention, and FIG. 4 is a composite pipe of the present invention. FIGS. 5 and 6 are longitudinal sectional views showing the manufacturing process of a conventional composite pipe. 1... Outer tube, 11... Socket, 12... Socket, 2
... Synthetic resin inner tube, 21 ... Expanded diameter section, 22 ...
End portion, 3... Foaming adhesive, 4... Pressing tool, 5,
6...Press type, P...Passing type.

Claims (1)

[Scope of Claims] 1. A composite tube characterized in that an inner tube made of synthetic resin is inserted into an outer tube, and a foaming adhesive is interposed between the outer tube and the inner tube. 2.Inside an outer tube having an enlarged diameter socket at one end and a spigot at the other end, an outer diameter slightly smaller than the inner diameter of the outer tube and an outer diameter slightly smaller than the inner diameter of the socket at one end. A synthetic resin inner tube having an enlarged diameter portion is inserted, a foaming adhesive is interposed between the outer tube and the inner tube, and the outer circumferential surface of the spout is reversed from the spout end. A composite pipe characterized by being integrally coated. 3. An outer tube having an enlarged diameter socket at one end and a spigot at the other end, and an outer tube having an outer diameter slightly smaller than the inner diameter of the socket at one end. A synthetic resin inner tube with an enlarged diameter portion is prepared, and a foaming adhesive is applied to the inner circumferential surface of the outer tube or the outer circumferential surface of the inner tube, and then the inner tube is inserted into the outer tube and the adhesive is foamed. The outer tube and the inner tube are closely joined together, and then, or at the same time as the foam bonding, the end of the inner tube protruding from the spout end of the outer tube is heated and softened and turned over in the outer circumferential direction, and the outer circumferential surface of the spout is heated and softened. A method for manufacturing a composite pipe, characterized in that the inner pipe is integrally covered with an inner pipe.