JPH0583798B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing a heat insulating tube.

(Prior Art) Conventional heat-insulating pipes are constructed by attaching a heat insulating material to the outer surface of an inner pipe for fluid circulation in a copper pipe, and inserting and fixing this into an outer pipe for protection.

(Problem to be Solved by the Invention) However, in such a heat-insulated pipe, not only does it take time and effort to install the heat-insulating material, but it also requires work to insert it into the outer pipe and fix it, which is very time-consuming and difficult to configure. There are also problems in that the process becomes complicated and costs increase. In addition, since the outer tube is usually a cylindrical tube, it is necessary to use a thick-walled tube to withstand external forces.Furthermore, since such an outer tube is used, it is not necessary to bend the piping. It was possible.

(Means for Solving the Problems) In order to solve these problems, the present invention provides an uncured cylindrical body made of synthetic resin in a tunnel-like movable molding space having a bellows-like inner peripheral surface. Provided is a method for producing a heat insulating tube, in which the inner tube is inserted into the cylindrical body at the same speed as the moving speed of the moving molding space, and the heat insulating material is injected into the space between the cylindrical body and the inner tube. do.

(Function) According to the manufacturing method of the present invention, the bellows tube is formed by pressing the cylindrical body against the bellows-shaped inner circumferential surface of the movable molding space using the injected heat insulating material, and the heat insulating tube is thus formed at the same time as the bellows tube is manufactured. This makes it possible to manufacture insulated pipes extremely efficiently.

The thus obtained heat-insulated tube has an outer tube made of a bellows tube, so it has sufficient strength against external forces even if it is made of synthetic resin and does not have a particularly thick wall. Since the heat insulating material is injected into the space between the inner pipe and the inner pipe, the space is completely filled with the heat insulating material, the inner pipe is held and fixed by the heat insulating material, and the heat insulation effect is large.

(Example) Next, an example of the present invention will be described based on the drawings. In FIGS. 1 and 2, reference numeral 1 denotes an inner tube made of a metal tube such as a copper tube, through which a fluid such as a heat medium or a refrigerant flows. Reference numeral 2 denotes a bellows tube made of synthetic resin that is fitted onto the outside of the inner tube 1 with a gap in between. 3 is a foamed synthetic resin heat insulating material formed by injecting foamed synthetic resin into the space between the inner pipe 1 and the bellows pipe 2; tube 2
The bellows tube 2 protects the heat insulating material 3 and the inner tube 1.

The manufacturing method and apparatus for this heat-insulating pipe will be explained with reference to FIGS. 3 and 4. 5a and 5b are an upper mold and a lower mold formed by connecting a large number of split molds 4 in an endless manner and moving them in circulation. , these upper mold 5a and lower mold 5b
A tunnel-shaped movable molding space 6 having a bellows-shaped inner peripheral surface is formed in a part of those circulation paths. Reference numeral 7 denotes a nozzle of an extruder, which is disposed so as to concentrically supply an uncured synthetic resin cylindrical body 8 to one end of the movable molding space 6 from its tip. A through hole 9 is bored at the axial center of the nozzle 7, and the inner tube 1 can be supplied to the inside of the cylindrical body 8 through the through hole 9. After the inner tube 1 is straightened by a leveler (not shown), it can be fed by a feeding device (not shown) at the same speed as the moving speed of the movable molding space 6. Further, the nozzle 7 is provided with an injection passage 10 around the through hole 9 for injecting the foamable synthetic resin under pressure into the inside of the cylindrical body 8. The inner cylinder 1 communicates with an injection header 11 through which the injection header 11 is sealed, and an injection nozzle 12 for foamable synthetic resin A is attached to the injection header 11.
The injection passage 10 may be formed independently of the through hole 9, or may be formed in the shape of a groove on the peripheral wall of the through hole 9.

In the nozzle 7, reference numeral 13 denotes a hollow nozzle body, which is bent in an L-shape and gradually tapers in diameter toward the tip.
a is attached to the extruder main body 14. 15 is a screw of the extruder main body 14. A core 16 is arranged inside the nozzle body 13, and the nozzle body 13
A synthetic resin passage 17 whose cross-sectional area and diameter gradually decrease is formed between the inner surface and the outer surface of the core 16, and the synthetic resin passing through this passage forms the cylindrical body. A support block 18 is formed at the base of the core 16, and this support block 18 is tightly fitted and held in the hollow portion of the bent portion of the nozzle body 13. Reference numeral 19 designates a resin passage hole bored in this support block 18.

In the above configuration, the upper mold 5a and the lower mold 5b are circulated to form a movable molding space 6, the extruder main body 14 is operated to extrude and form the cylindrical body 8, and the inner tube 1 is passed through the through hole 9. is delivered to the moving molding space. Next, the foamable synthetic resin A is gradually pumped through the injection port 12 to form the cylindrical body 8 and the inner tube 1.
When the first injected foamable synthetic resin A foams and solidifies, the injection pressure is increased and a fixed amount is injected. Then, the injected foamable synthetic resin A
The uncured cylindrical body 8 is pushed radially outward by the injection pressure and the foaming expansion pressure and is pressed against the bellows-shaped inner peripheral surface of the movable molding space 6, forming the bellows tube 2. The space between the bellows pipe 2 and the inner pipe 1 is filled with a heat insulating material 3 made of a foamable synthetic resin that has been foamed and solidified, thereby forming a heat insulating pipe consisting of the inner pipe 1, the bellows pipe 2, and the heat insulating material 3. In addition, if the foaming and solidifying time of the foamable synthetic resin A to be injected is long and the insulating material 3 formed by foaming and solidifying cannot receive the injection pressure of the foamable synthetic resin at the initial stage of production, transfer molding is performed. It is preferable that the space between the tip of the bellows tube 2 coming out of the space 6 and the inner tube 1 can be appropriately sealed with a plug (not shown).

In the above embodiment, the heat insulating material 3 is made of foamable synthetic resin, but various inorganic heat insulating materials may be mixed with the synthetic resin to give it fluidity and then injected. In addition, in the above example, in order to accelerate the foaming and solidification of the foamable synthetic resin A,
The inner tube 1 may be heated by passing a high-temperature fluid such as pressurized steam or combustion gas through the inner tube 1. On the other hand, the upper mold 5a and the lower mold 5b are preferably cooled so that the cylindrical body 8 is quickly cooled and solidified when it comes into contact with the inner peripheral surface of the movable molding space 6, and the bellows tube 2 is formed.

(Effects of the Invention) As described above, according to the method for manufacturing a heat insulating pipe of the present invention, an uncured cylindrical body made of synthetic resin is supplied into a tunnel-shaped movable molding space having a bellows-shaped inner peripheral surface,
The inner tube is inserted into the cylindrical body at the same speed as the moving speed of the moving molding space, and a heat insulating material is injected into the space between the cylindrical body and the inner tube. A bellows pipe is formed from an uncured cylindrical body by injecting heat insulating material, and the heat insulating pipe is manufactured using the bellows pipe as the outer tube, so the heat insulating pipe can be manufactured extremely efficiently and the manufacturing process is simplified. This makes it possible to provide an inexpensive insulated pipe.

Furthermore, since the outer tube is formed into a bellows tube, even if the tube is made of synthetic resin, it is possible to obtain an insulated tube that can sufficiently withstand external forces and has good flexibility without increasing the wall thickness. Moreover, since the obtained heat-insulating pipe consists only of the bellows pipe, the inner pipe, and the heat insulating material injected into the space between the two pipes, it has a simple structure and can be manufactured at low cost. Since the entire space between the bellows pipe and the inner pipe is filled with insulation material,
Even if it is a small-diameter pipe, it is possible to manufacture a heat-insulating pipe with a large heat-insulating effect.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a partial vertical cross-sectional view of a heat-insulated pipe, Fig. 2 is a partially omitted overall front view, Fig. 3 is a schematic configuration diagram of the manufacturing equipment, and Fig. 4 is a manufacturing process. FIG. 3 is a detailed partial cross-sectional view of the main parts of the device. 1... Inner pipe, 2... Bellows pipe, 3... Insulation material, 6
...Moving molding space, 8... Cylindrical body, A... Foaming synthetic resin.

Claims (1)

[Claims] 1. Supplying an uncured cylindrical body made of synthetic resin into a tunnel-shaped movable molding space having a bellows-shaped inner peripheral surface,
A method for producing a heat-insulating tube, comprising inserting an inner tube into the cylindrical body at the same speed as the moving speed of the moving molding space, and injecting a heat insulating material into the space between the cylindrical body and the inner tube. .