JPH0347936B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a method for manufacturing a finned double tube for a heat exchanger, and more specifically, to an air-temperature evaporator for vaporizing, for example, liquefied oxygen, liquefied nitrogen, liquefied argon, etc. This article relates to a method for manufacturing double pipes used in heat exchangers such as the above.

Conventional technology Generally, this type of double tube is composed of an outer tube with fins made of extruded aluminum and an inner tube made of stainless steel, and the outer tube improves heat exchange efficiency. The inner tube provides sufficient strength, as well as pressure resistance, corrosion resistance, and excellent low-temperature properties.

Conventionally, the manufacturing method of such double tubes with fins for heat exchangers has been as follows: First, the entire outer tube is heated and then fitted onto the inner tube by shrink fitting, and second, the outer tube and inner tube are loosely connected. The roll forming method, in which the outer tube is pressurized and crimped after fitting together, and the third tube expansion method, in which the inner tube is expanded after loosely fitting the outer tube and the inner tube together, are known. According to the first and third methods, both require large equipment and a large amount of energy, and as a result, there is a problem in that the manufacturing cost of the finned double tube for the heat exchanger is extremely high. Further, in the second method, since the outer tube is provided with fins, the tube cannot be sufficiently pressurized from the outside, and there is a problem in that it is difficult to manufacture a double tube with fins.

Purpose of the Invention The purpose of the present invention is to solve the above-mentioned problems of the prior art and to manufacture a finned double tube for a heat exchanger with excellent performance very easily and at low cost without the need for special equipment. I'm trying to provide a way that can be done.

Composition of the Invention In order to achieve the above-mentioned object, the present invention includes a stainless steel inner tube whose inner diameter is slightly smaller than the inner diameter of the outer tube, which is fitted into a finned outer tube made of an aluminum extruded material, and which is then externalized in this state. A portion of the peripheral wall of the tube between the fins is heated along the tube axis direction without using a filler metal to melt the portion, and then the molten portion is solidified to form an outer tube with fins. The gist of the present invention is a method for manufacturing a double-walled finned tube for a heat exchanger, which is characterized in that an outer finned tube is joined to an inner tube by shrinkage.

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

In the drawings, the method for manufacturing a double tube with fins for a heat exchanger according to the present invention is shown in FIG.
and an inner tube 2 made of stainless steel are prepared. The inner diameter of the outer tube is slightly larger than the outer diameter of the inner tube 2. Then, the inner tube 2 is fitted into the outer tube 1, and in this state, the part 3 between the fins 4 of the peripheral wall 1a of the outer tube 1 is inserted along the tube axis direction and into the outer tube 1, as shown in FIG. The finned outer tube 1 is heated over the entire length of the finned outer tube 1 to melt and solidify the portion 3 without using a filler metal.
The outer tube 1 is tightly connected to the inner tube 2 by contraction of the tube.

As shown in FIG.
However, this may be one or more locations.

It is desirable to heat and melt the part 3 between the fins 4 of the peripheral wall 1a of the outer tube 1 over the entire length in the tube axis direction, since the outer tube 1 and the inner tube 2 will be in complete contact with each other after solidification. Even if a portion 3 of the peripheral wall 1 is partially heated and melted in the tube axis direction and solidified, the outer tube 1 can be firmly connected to the inner tube 2, and therefore, the portion 3 of the peripheral wall 1a It is not necessarily necessary to heat and melt 3 over the entire length in the tube axis direction.

The outer tube 1 is heated and melted completely automatically using a heating torch 5 used for welding as shown in FIG.
Alternatively, it can be easily done manually.

When partially heating and melting the peripheral wall 1a of the outer tube 1, no filler material is used at all. Therefore, heating and melting work is very simple.

In addition, in the above, the cross-sectional shape of the outer tube 1 and the inner tube 2 is not limited to a perfect circle, but may be any other suitable shape such as a square shape or an ellipse shape.

Effects of the Invention As described above, the method for manufacturing a double tube with fins for a heat exchanger according to the present invention is as follows. Insert the inner pipe 2, and in this state, tighten the fins 4 on the peripheral wall 1a of the outer pipe 1.
A portion 3 between the comrades is heated along the tube axis direction without using a filler metal to melt the portion 3, and then the molten portion is solidified, and the finned outer tube 1 shrinks during solidification. Since the outer tube 1 with fins is connected to the inner tube 2 with Pipes can be manufactured easily and with good workability.
Furthermore, since the circumferential wall 1a of the outer tube 1 is only partially heated and melted without using a filler metal, the work is extremely easy, and less materials and energy are used, resulting in extremely low manufacturing costs. . According to the method of the present invention, the finned outer tube 1 and the inner tube 2 are firmly and reliably connected, and the obtained finned double tube for a heat exchanger has extremely excellent performance and is easy to manufacture. Since the work is simple, even a small lot of finned double tubes for heat exchangers can be easily manufactured.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a double tube with fins for heat exchangers manufactured by the method of the present invention, FIG. 2 is an enlarged cross-sectional view of the double tube of FIG. 1 with parts omitted, and FIG. 3 is a method of the present invention. FIG. 1...Outer tube, 1a...Peripheral wall, 2...Inner tube, 3...
...Part of the peripheral wall, 4...Radial fins, 5...Heating torch.

Claims (1)

[Claims] 1 Insert the stainless steel inner tube 2, whose inner diameter is slightly smaller than the inner diameter of the outer tube 1, into the outer tube 1 with fins 4 made of extruded aluminum, and in this state between the fins 4 on the peripheral wall 1a of the outer tube 1. After heating the portion 3 along the tube axis direction without using a filler metal to melt the portion 3, the molten portion is solidified, and the finned outer tube 1 shrinks during solidification to form the finned outer tube 1. A method for manufacturing a double tube with fins for a heat exchanger, characterized in that an outer tube 1 is joined to an inner tube 2.