JPH0299229A - Manufacture of thin-walled, flat tube - Google Patents

Abstract

PURPOSE:To easily and surely manufacture a thin-walled, flat tube by rolling a tube stock such as an extruded tube, first, to form a thinner-walled, flat, belt-like, squeezed, intermediate material, then, expanding it. CONSTITUTION:The tube stock 1 for the extruded tube or a resistance welded tube having a circular or flat section, etc., is rolled to form a thinner-walled, flat, belt-like, squeezed, intermediate material 2. Then, the intermediate material 2 obtained is expanded to a fixed sectional shape by supplying compressed fluid between forming dies 3 between which a prescribed forming clearance is given. Consequently, a thin-walled flat tube, too, can be manufactured easily and surely. Besides, when a suitable forming clearance is set, a flat tube having a desired shape and wall-thickness can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing flat tubes, particularly thin-walled flat tubes, used as tubes for radiators, tubes for car heaters, tubes for parallel flow condensers, and the like.

BACKGROUND OF THE INVENTION Conventionally, flat tubes of this type have been manufactured by extrusion processing, or by forming a band-shaped plate material into a flat tube shape and welding opposite edges together.

Incidentally, in recent years, with the demand for lighter weight and higher performance for heat exchangers and the like that use this type of flat tube, there has been a demand for further thinning of the flat tube. Ta.

Problems to be Solved by the Invention However, when trying to manufacture a flat tube with a very thin wall thickness, for example, about 0.3# or less,
In the former manufacturing method, not only is the strength of the male mold of the porthole die used for extrusion molding insufficient, but it is also difficult to form a rad layer because it is necessary for corrosion protection on the inner circumferential surface and in combination with brazing on the outer circumferential surface. In addition, the latter manufacturing method makes it difficult to perform good welding, so it is difficult to manufacture by any of the methods.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for easily and reliably manufacturing thin-walled flat tubes, particularly thin-walled flat tubes with a wall thickness of about 0.3 mta or less. The purpose is to

As a means for solving the problems, the method for manufacturing a thin-walled flat tube according to the present invention is to produce a flat belt-shaped crushed intermediate tube whose wall thickness is reduced by rolling a blank tube such as an extruded tube or an electric resistance welded tube. The method is characterized in that a material is formed, and then the intermediate material is expanded into a predetermined cross-sectional shape by feeding compressed fluid between molding molds having a predetermined molding gap.

As the raw tube, an extruded tube or an electric resistance welded tube made of aluminum alloy and having a circular or flat cross section manufactured by a conventional method may be used.

Then, by rolling this raw pipe, a flat belt-shaped crushed intermediate material with a reduced wall thickness is formed.

This invention is particularly suitable for manufacturing thin-walled flat tubes with a wall thickness of about 0°311 In or less,
For example, when manufacturing a material with a wall thickness of about 0.3 m, the thickness of the intermediate material (total of two sheets) may be set to 0.6 m and rolling is performed.

Next, the intermediate material obtained as described above is expanded to a predetermined cross-sectional shape between molding molds having a predetermined molding gap. A method may suitably be employed in which the expansion tube is sealed at one end by, for example, bending one end of the intermediate material, and a compressed fluid such as compressed air is supplied from the other end.

Example The present invention will be explained in detail below.

The base tube (1) is made of A3003 alloy, with a cladding layer made of A7072 alloy with a cladding rate of 10% on the inner circumferential side, and a cladding layer made of A4045 alloy with a cladding rate of 10% on the outer circumferential side. Each has a wall thickness of 0
．． 4nyn flat electric resistance welded tube with a width of 16#III+
A shoe with a thickness of 1.9 mm and a length of 400 mm was prepared.

Then, by cold-rolling the raw pipe (1) according to a conventional method, as shown in FIG. 2, the thickness is 0. An intermediate material (2) crushed into a flat strip having a thickness of 2# (each wall thickness: 0.1 m) and a length of 1,600 m was obtained.

Next, as shown in FIG. 3, one end (2a) of this intermediate material (2) is bent by about 10 to 2C1m to seal one end, while the other end (2b) is bent in the length direction from the end surface. It was formed by expanding an air inlet (2C) having a diameter of about 7IIvn and extending 30 to 50InIn toward the tube.

Then, as shown in FIG.
Insert the iron air introduction pipe (4) with an outer diameter of 7 m into the air introduction port (2c), and
A rubber packing member (5) was interposed around 2c).

After that, 30 to 50 Ky/
By supplying aA of compressed air for 5 seconds,
The intermediate material (2) was expanded into a tube to obtain a thin flat tube (6) with a wall thickness of 0.1# as shown in FIG.

In addition, after the above rolling process and before forming the air introduction pipe, the temperature was
Annealing treatment for about 2 hours may be performed. If the same treatment is not performed, the tempering of the obtained flat tube will be approximately Hl 8, which will prevent deformation during subsequent handling.

Effects of the Invention As described above, the method for manufacturing a thin-walled flat tube according to the present invention involves first rolling a raw tube such as an extruded tube or an electric resistance welded tube to form a flattened intermediate material in the form of a flat band with a reduced wall thickness. After that, it is made into an expanded tube, so even thin flat tubes with a wall thickness of about 0.3 # or less, which are difficult to manufacture using conventional manufacturing methods, can be manufactured easily and reliably. I can do it.

Furthermore, since the above-mentioned expansion tube treatment is performed by feeding compressed fluid between molding dies having a predetermined molding gap, flat tubes of any shape and thickness can be formed by appropriately setting the molding gap. can be manufactured.

[Brief explanation of drawings]

The drawings show embodiments of the invention in the order of steps,
Figure 1 is a perspective view of a raw pipe, Figure 2 is a perspective view of a crushed intermediate material obtained by rolling the raw pipe, and Figure 3 is a perspective view of a crushed intermediate material obtained by rolling the raw pipe. FIG. 4 is a longitudinal sectional view showing the swelling tube treatment process, and FIG. 5 is a perspective view of the final product, the thin-walled flat tube. (1)...Made pipe, (2)...Crushed intermediate material, (3)...
...Forming mold, (6)...Thin wall flat tube material. Above 1 Figure 2 Figure 3

Claims (1)

[Claims] After rolling a raw pipe such as an extruded pipe or an electric resistance welded pipe to form a crushed intermediate material in the shape of a flat band with a reduced wall thickness, the intermediate material is heated with compressed fluid between molding dies having a predetermined forming gap. 1. A method for manufacturing a thin-walled flat tube, which comprises expanding the tube into a predetermined cross-sectional shape by feeding.