JPH06198376A - Metallic tube with fin for heat exchanger and its manufacture - Google Patents

Abstract

PURPOSE:To prevent the increase of the thickness of the boundary layer and to improve the heat exchanging performance by forming on spiral fins a plurality of slits from the peripheral side in a twisted manner as a whole. CONSTITUTION:A plurality of recessed grooves 12 which extend in the longitudinal direction are formed on the outer circumferential surface of the external tube material 11 made of aluminum with intervals in the circumferential direction. An internal tube material 10 made of copper is loosely fitted around a mandrel 13, and at the same time, the external tube material 11 is loosely fitted around the internal tube material 10. Then, three form rolling round dies 14 are rotated, both materials are moved and inserted between these dies. The spiral fins 4 having a plurality of slits 5 are formed on the outer circumferential surface of the external tube material. The slits 5 become twisted as a whole due to friction during the form rolling. This constitution allows easy manufacture of a metallic tube l provided with spiral fins 4 having a plurality of slits 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pipe type heat exchanger, a finned metal tube used in a fin tube type heat exchanger, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as finned metal tubes used in this type of heat exchanger, spiral fins are provided on the outer peripheral surface.
One that is integrally formed by a rolling process using a rolling round die is widely known.

[0003]

However, when this finned metal tube is used in the heat exchanger as described above, a thick boundary layer is generated on the surface of the fin, so that the heat exchange performance is not sufficient. was there.

An object of the present invention is to provide a finned metal tube for a heat exchanger and a method for manufacturing the same, which solves the above problems.

[0005]

DISCLOSURE OF THE INVENTION In a metal tube with fins for a heat exchanger according to the present invention, a spiral fin is integrally formed on the outer peripheral surface, and the spiral fin has a plurality of slits from the peripheral side thereof as a whole. Is formed to have a twisted shape.

In the method for manufacturing a finned metal pipe for a heat exchanger according to the present invention, a plurality of concave grooves extending in the length direction are formed at intervals in the circumferential direction on the outer peripheral surface of the metal pipe material.
This metal tube material is characterized by forming a spiral fin having a plurality of slits by performing a rolling process using a rolling round die.

[0007]

When the spiral fin integrally formed on the outer peripheral surface is formed with a plurality of slits in a spiral shape from the peripheral side, the boundary generated when used in the heat exchanger The layer will break at the slit, thus preventing an increase in its thickness.

Further, concave grooves extending in the length direction are integrally formed on the outer peripheral surface of the metal tube material at intervals in the circumferential direction, and the metal tube material is rolled using a rolling round die. When processed, a plurality of slits can be formed simultaneously with the formation of the spiral fin.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is a finned metal 2
It is applied to heavy pipes.

1 and 2 show a metal double tube with fins, and FIGS. 3 and 4 show a manufacturing method thereof.

In FIGS. 1 and 2, a metal double tube with fins (1) is an inner tube made of copper (including copper alloy; the same applies hereinafter).
(2) and an outer tube made of aluminum (including an aluminum alloy; the same applies hereinafter) that is tightly fitted around the inner tube (2) and has spiral fins (4) integrally formed on the outer peripheral surface.
It consists of (3). On the spiral fin (4) formed on the outer peripheral surface of the outer tube (3), multiple slits are provided from the peripheral side.
(5) is formed to have a twisted shape as a whole. The number of slits (5) is not limited to that shown in the figure.

Next, a method of manufacturing the finned metal double tube (1) will be described with reference to FIGS.

First, a copper inner tube material (10) and an aluminum outer tube material (11) are prepared. On the outer peripheral surface of the outer tube material (11), a plurality of concave grooves (12) extending in the length direction are formed at intervals in the circumferential direction. Outer tube material (11) with groove (12)
Is molded, for example, by extrusion. The number of grooves (12) is
The number is the same as the number of slits (5) to be formed.

Then, the inner tube material (10) is loosely fitted around the mandrel (13), and the outer tube material (11) is loosely fitted around the inner tube material (10). Then, the three rolled round dies (14) are rotated, and both materials (10) and (11) are moved so as to enter between these dies (14). Then, a spiral fin (4) having a plurality of slits (5) is formed on the outer peripheral surface of the outer tube material (11). During the rolling process, the slit (5) becomes twisted as a whole due to friction. When passing through the rolled round die (14), the inner pipe material (10) is brought into close contact with the outer peripheral surface of the mandrel (13), and the outer pipe material (11) is brought into close contact with the inner pipe material (10). To be made. In this way, the finned metal double tube (1) is manufactured.

In the above, during the rolling process, the concave groove (1
A crack may occur at the bottom of 2) and the crack may extend to the peripheral wall of the outer tube (3) of the finned double tube (1), but since it is a double tube type, The leakage of fluid in the inner pipe (2) can be prevented.

In the above embodiment, the inner pipe (2) is made of copper and the outer pipe (3) is made of aluminum. However, the present invention is not limited to this and can be changed as appropriate. The material of the inner pipe (2) is determined in consideration of corrosion resistance and strength, and the inner pipe (3) may be made of synthetic resin. Further, in the above embodiment, the case where the present invention is applied to a metal double tube with fins is shown, but the present invention is not limited to this, and can be applied to a single metal tube or a metal tube having three or more layers. Is.

[0017]

According to the finned metal tube of the present invention,
As described above, the boundary layer generated when used in the heat exchanger is broken at the slit portion, and therefore the increase in the thickness thereof is prevented, so that the heat exchange performance is improved.

Further, according to the method of the present invention, it is possible to easily manufacture a metal tube having a spiral fin having a plurality of slits.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a double tube with fins according to the present invention.

FIG. 2 is a transverse sectional view of the same.

FIG. 3 is a transverse cross-sectional view showing a method of manufacturing a double tube with fins according to the present invention when an outer tube material is fitted around an inner tube material.

FIG. 4 is a perspective view showing a method of manufacturing a double tube with fins according to the present invention at a stage of forming spiral fins.

[Explanation of symbols]

 1 Double tube with fin 4 Spiral fin 5 Slit

Claims (2)

[Claims] 1. A fin for a heat exchanger, wherein a spiral fin is integrally formed on an outer peripheral surface, and a plurality of slits are formed in a spiral shape from the peripheral side of the spiral fin as a whole. Metal tube. 2. A rolling process using a rolling round die for the metal pipe material, wherein a plurality of concave grooves extending in the length direction are formed at intervals in the circumferential direction on the outer peripheral surface of the metal pipe material. The method for producing a metal tube with a fin for a heat exchanger, characterized in that a spiral fin having a plurality of slits is formed by applying.