JPH0297797A - Heat insulating pipe and manufacture thereof - Google Patents

Abstract

PURPOSE:To easily obtain a heat insulating pipe by forming an inner pipe and a spacer with a plastic profile material by simultaneous batch extrusion, in case of the heat insulating pipe of double-pipe type with the rib-shaped spacer existing between the inner and outer pipes. CONSTITUTION:This invention is related to a heat insulating pipe of double-pipe type in which an air heat insulating layer 30 is formed between an inner pipe 12 and an outer pipe 20 by providing a rib-shaped spacer 14 existing between the inner and outer pipes 12 and 20 made by, for instance, plastic of polyethylene, polypropylene, etc. having flexibility. The inner pipe 12 and the spacer 14 are formed by a plastic profile material 1 by simultaneous batch extrusion. As the result, a manufacture process is reduced, and the low-priced heat insulating pipe of double-pipe type, forming the air heat-insulating layer; can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is used, for example, to transfer cooling water. The present invention relates to a double-pipe type plastic insulated pipe having an air-thermal insulation layer, and a method for manufacturing the same.

[Prior Art] Conventional double-tube plastic insulated pipes are made by attaching a separately manufactured rib-shaped spacer to the previously manufactured inner tube, and then applying a process such as extrusion on top of the rib-shaped spacer. An outer tube is provided to form an air-thermal insulation layer.

[Problem B to be Solved by the Invention] As described above, since the inner tube, spacer, and outer tube are manufactured and assembled separately, the manufacturing process becomes complicated and the cost increases.

[Object of the invention] To obtain a double-pipe type plastic insulated pipe having an air-thermal insulation layer at a low cost by reducing the number of manufacturing steps compared to the conventional method.

[Means for Solving the Problems] Figure 51a and Figure 1b: The inner tube 12 and the spacer 14 are formed of a co-extruded plastic profile 10.

[Description thereof] Figures 1a and tb show an example of the insulated pipe of the present invention.

12 is an inner tube. The material is flexible.

Made of polyethylene, polypropylene, etc.

14 is a spacer. This is, for example, a rib-like member with a semicircular cross section, and is formed in a spiral shape on the surface of the inner tube 12.

As for this material, polyethylene, polypropylene, etc. are used as in the case of the inner tube.

These inner tube 12 and spacer 14 are made of a profiled material 10 that is extruded at the same time.

The term "deformed material" is used to mean "extruded product J (JIS term) with an irregular cross-sectional shape."

20 is an outer tube. This material is also flexible and is made of polyethylene, polypropylene, etc.

The outer tube 20 is maintained at a distance from the inner tube 12 by the spacer 14, and forms an air-thermal insulation layer 30 between the outer tube 20 and the inner tube 12.

The outer tube 20 is formed in tandem with the molding of the profiled material 10 or separately.
Made by extrusion.

- Regarding the die for extruding a profile: FIG. 2 schematically shows a die for extruding the profile 10.

40 is the die body, 42 is the mandrel, and 44 is the air hole.

46 is an extruder for inner tubes, 48 is its material passage, 50 is an extruder for spacers, and 52 is its material passage.

54 is a rotary die, and its material passage 56 communicates with the material passage 52 via a spacer extrusion part notch 58 of the rotary die.

Note that if the inner tube 12 and the spacer 14 are made of the same material,
They can also be extruded in the same extruder.

- Function: While sending high-pressure air through the air hole 44, the inner tube 12 is extruded by the inner tube extruder 46.

At the same time, while slowly rotating the die 54 once.

The spacer 14 is extruded in a spiral manner onto the extruded inner tube 12 by the spacer extrusion 41150, and the profiled material 10 is extruded into the profile at once.

After cooling the profiled material 10 to an appropriate level (below the melting point), the outer tube 20 is extruded in tandem and coated thereon as described above, or alternatively, the profiled material 10 is wound up and the outer tube 20 is formed in a separate process. Perform extrusion coating.

Separation of the profiled material 10: As mentioned above, the spacer 14 of the profiled material 10 is not limited to a spiral shape, but may be any material that can form a gap between the inner tube 12 and the outer tube 20. However, A shape that can be easily extruded at once is good.

Examples are shown in Figures 3a and 3b.

- In the case of FIG. 3a: For example, four spacers 14 are parallel to the axis of the inner tube 12.

・In the case of Figure 3b, in the 0th drawing where the varnish spacer 14 is in the SZ shape, only one
Although only the articles are shown, in reality it would be better to have more (about 3 to 4 articles).

Note that the outer tube 20 is covered over these profiled members 10, as in the case of FIGS. 1a and 1b.

[Effects of the invention] Since the inner tube and spacer are formed at the same time by extruding plastic into different shapes, the number of manufacturing steps is reduced compared to manufacturing them separately, and an air-thermal insulation layer can be formed at a lower cost than before. A double-pipe insulated pipe is provided.

[Brief explanation of drawings]

All the drawings relate to embodiments of the present invention, and FIG. 1a is an explanatory diagram of an example of a heat-insulated pipe. FIG. 1b is a sectional view taken along line BB in FIG. 1a, and FIG. 2 is a schematic illustration of a die for extruding a profiled material 10. FIGS. 3a and 3b are explanatory diagrams of another example of the profiled material 10. 10: Profiled material 12: Inner tube 14 varnish spacer 20: Outer tube 30: Air heat insulation layer 40: Gui body 42: Mandrel 44: Air hole 46: Inner tube extruder 48: Material passage (for inner tube) 50 Varnish spacer extruder 52: Material passage (for spacer) 54: Rotating goo 56: Material passage (for spacer inside rotating gou) 58 Spacer extrusion part notch

Claims (2)

[Claims] (1) In a double-tube type insulated pipe in which an air-thermal insulation layer is formed between the inner tube and the outer tube by providing a rib-shaped spacer between the inner tube and the outer tube, the inner tube An insulated pipe in which the spacer and the spacer are made of deformed plastic material extruded at the same time. (2) When manufacturing a double-tube type insulated pipe in which an air-thermal insulation layer is formed between the inner tube and the outer tube by providing a rib-shaped spacer between the inner tube and the outer tube, A method for manufacturing an insulated pipe, in which the inner tube and the spacer are simultaneously formed by profile extrusion molding of plastic.