JPH01143764A - Tubular body for aluminum made heat exchanger - Google Patents

Abstract

PURPOSE:To extend the life of a product by making an Al alloy made specified brazing filler metal as a core bar, forming a clad thin sheet of specified dimension having Al made sheath stock son both faces and composing the tubular body for a heat exchanger by press-fitting to an Al or Al alloy made tubular body. CONSTITUTION:An Al alloy thin sheet clad stock is formed in advance by cladding an Al thin sheet on both faces as a sheath stock with an Al-Si or Al-Si-Mg based Al alloy made brazing filler metal being taken as a core bar. In this case, the whole thickness of the sheet is taken in 8-100mum and one side thickness of the sheath stock is regulated to 5-20% of the whole body. Then, the tubular body for a heat exchanger is formed by press-fitting clad thin sheets 4, 4' to a flat Al alloy made tubular body 1 manufactured by hot extrusion by rolls 3, 3'. When this tubular body and a fin stock are brazed by heating, the clad stock becomes a brazing filler metal, so the deformation of the fin is prevented and the corrosion resistance is improved. Consequently the service life of a product heat exchanger is extended.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an aluminum tube for a heat exchanger having fins attached to its outer surface by brazing.

[Conventional technology]

For example, aluminum heat exchangers are used in automatic heavy-duty radiators, cooler condensers, and evaporators.

Such a heat exchanger has a fin material made of a pre-song sheet clad with Al-Si aluminum alloy brazing material on the surface of an extruded flat and porous aluminum tube. tacking to form an assembly, heating the assembly to a temperature of about 600° C. in a vacuum or an inert gas-filled furnace, and brazing the fin material onto the surface of the tube. Yoshishi was manufactured.

[Problem that the invention seeks to solve]

However, the heat exchanger manufactured by the above method has the following problems.

(1) When heating the assembly and brazing the fin material made of pre-song sheets onto the surface of the pipe body, the high temperature sag resistance of the fins is deteriorated due to the metal brazing material melted by heating. sagging and deforming due to its own weight. As a result, the adhesion of the fins deteriorates, and the problem arises that the original shape of the assembled body cannot be maintained.

(2) Pitting corrosion easily occurs in the tube during use, resulting in a short product life.

As a means to solve the above problem (1),
No. 204169 discloses that a coating of a brazing metal made of an Al-Si alloy is formed on the surface of an aluminum tube by thermal spraying, and a coating of brazing metal is applied to the tube on which such a coating of brazing metal is formed. A method of manufacturing a heat exchanger by brazing fins without fins is disclosed.

However, in the above-mentioned method, since the brazing metal film on the tube surface is formed by thermal spraying, a thick oxide film is formed on the surface of the brazing metal, and this oxidation film deteriorates the brazing properties. In addition, there is a problem that the dimensional accuracy of the product is low.

In addition, as a means to solve the problem (2) above, attempts have been made to galvanize the pipe body and coat its surface with zinc to prevent pitting corrosion, but this method does not include the following: There is a problem in that it causes a significant increase in product cost and requires many steps for the galvanizing process.

Therefore, an object of the present invention is to provide an aluminum heat exchanger tube body that can reliably bond fins by brazing without causing sagging or deformation due to heating at high temperatures, and that has excellent corrosion resistance. It's about doing.

[Means for solving problems]

The aluminum tube for a heat exchanger of the present invention includes a tube made of aluminum or an aluminum alloy, and an Al-Si, Al-Si-Mg, or 0.5 to 0.5 4. The core material is an Al-3i-based or Al-Si-Mg-based aluminum alloy brazing material containing % of zinc, and aluminum is clad as a skin material on both sides of the core material, and the overall thickness is 8~100μ
The invention is characterized in that it consists of an aluminum alloy clad thin plate having a thickness of 5 to 20% of the total thickness of the aluminum as the clad skin material per side.

Since the tube body for a heat exchanger of the present invention is constructed as described above, when fins are brazed to the surface of the tube body, a pre-song sheet clad with a conventional metal brazing material is used as the fin. There is no need to use it. That is, the aluminum alloy clad thin plate, which has the above-mentioned aluminum alloy brazing material as a core material and aluminum cladding as a skin material, is crimped onto the surface of the tubular body. When fins without material are temporarily attached to form an assembly and this assembly is heated, the aluminum alloy clad thin plate should be brazed with the brazing material, and the fins that have been temporarily attached should be brazed at -degrees. Can be done.

In this way, since the fins do not have brazing material, unlike fins made of conventional pre-song sheets, the brazing material deteriorates the high temperature sag resistance of the fins due to the melting of the brazing material due to heating, which causes the fins to deteriorate. It will not sag and become deformed due to its own weight.

The reason why we use all of the aluminum alloy clad thin plates mentioned above as the brazing material to be formed on the surface of the tube is that the aluminum cladding on the surface prevents the formation of an acid f arsenal film on the surface of the brazing material. However, the purpose of brazing with an oxide film is to prevent deterioration of properties.

The thickness of the aluminum alloy clad thin plate that is crimped onto the surface of the tube should be 8 to 100 μm1, and the thickness of the aluminum cladding material on one side should be 5 to 20% of the total thickness. .

If the thickness of the aluminum alloy clad thin plate is less than 8 μm, there will be insufficient brazing material, and the fins cannot be well brazed. On the other hand, when the thickness exceeds 100 μm, the amount of brazing material is too large, and brazing is sometimes difficult due to the S content in the brazing material.
i diffuses into the tube, reducing the corrosion resistance of the tube.

If the thickness per side of aluminum as a cladding material is less than 5% of the total thickness, the effect of preventing the formation of an oxide film on the surface of the brazing material will be weak and cladding will become difficult. On the other hand, if the thickness exceeds 20% of the total thickness, the amount of brazing material that is the core material will be small and the composition of the brazing material will change, making it impossible to properly braze the fins.

As the brazing material which becomes the core material of the aluminum alloy clad thin plate, the well-known A with the chemical composition shown in Table 1 below is used.
l-Si alloy or Al-Si-Mg alloy is used.

The above AL-Si alloy or AlAl-5 as a brazing material
0.5 to 4.0 wt. to t-alloy. % of zinc, the aluminum alloy clad thin plate is made electrochemically base, giving it a sacrificial anode effect and increasing the corrosion resistance of the tube. However, when the zinc content is less than 0.5 wt.%, the desired effect cannot be obtained in the above action; on the other hand, when the zinc content is less than 4.0 wt.%. Even if it exceeds %, no better effect can be obtained, and on the contrary, the material becomes harder and more difficult to bend, and workability deteriorates.

In this invention, the above-mentioned aluminum alloy clad thin plate is crimped onto the surface of the aluminum or aluminum alloy tube body in the following manner. That is, as shown in a schematic perspective view in FIG. 1 and a schematic side view in FIG.
A flat and porous aluminum or aluminum alloy tube 1 is manufactured by hot extrusion from an extrusion die 2.

In this way, the upper and lower surfaces of the flat tube body 1 extruded from the extrusion die 2 are provided with rolls 3.3 extending in the width direction.
' is provided. The rolls 3.3' are pressed against both sides of the tubular body 1 with a predetermined pressure by a pressure mechanism (not shown). The above-mentioned strip-shaped aluminum alloy clad thin plate 4.4' is hung on the roll 3.3', and the strip-shaped thin plate 4.4''i is sent toward both sides of the tube body 1 by the roll 3.3'. It is designed to be supplied and crimped.

The tube body 1 immediately after hot extrusion from the extrusion die 2 has a diameter of about 4
Since the residual heat of about 50° C. is maintained, the strip-shaped aluminum alloy clad thin plates 4, 4' are fed and pressed by the rolls 3, 3' toward the upper and lower surfaces of the tube body 1, which is at such a high temperature. are crimped onto the upper and lower surfaces of the tubular body 1. FIG. 3 is a sectional view of a flat tubular body 1a of the present invention having five holes 1a, to which the thin aluminum alloy clad plate 4.4' is crimped as described above.

The tube body 1 is made of pure Al (for example, JIS 1100) or AL-Mn alloy (for example, JIS 3003).
)' to be used.

〔Example〕

Next, the present invention will be explained using examples.

The brazing material Nal~4t having the chemical composition shown in Table 2 was cracked. Table 2 also shows the chemical compositions of the skin material, tube body, and fin material.

The brazing material and the skin material are obtained by casting a slab having the chemical composition shown in Table 2 using a normal melting and casting method, and the brazing material is obtained by hot rolling the cast slab to a thickness of 8 cm. The skin material is made into a thin plate by hot-rolling the slab to obtain a hot-rolled thin plate with a thickness of 5 mm, and then cold-rolling this into a cold-rolled thin plate with a thickness of III+. I prepared it well.

The skin material K was superimposed on both sides of each of the brazing materials N[11 to 4 obtained as described above, and this was hot rolled to a thickness of 3
Then, the obtained clad plates were cold-rolled at different rolling reduction rates to prepare four types of aluminum alloy clad thin plates having different thicknesses and chemical compositions.

Next, by the method shown in FIGS. 1 and 2, the above-mentioned aluminum alloy is applied to the upper and lower surfaces of the tube body 1 extruded from the extrusion die 2 and having the chemical composition of A or B in Table 2. The clad thin plate was crimped. At this time, the extrusion speed of the tube extruded from the extrusion die 2 was 30 m/min.
Yes, the temperature was 4 ℃. Thus,
Test specimens of tube bodies of the present invention (hereinafter referred to as the specimens of the present invention) shown in Table 3 were prepared. Each of floors 1 to 4 of the present invention specimen has five holes 1a as shown in FIG. 3, and the dimensions thereof are 40 m5. Height h is 7
．． 0m, and the wall thickness t was 0.5mm.

For comparison, as shown in Table 3, comparative specimen Nl11 is made of a thick tube whose aluminum alloy clad thin plate is out of the range of the present invention, and a comparative specimen Nl11 where the aluminum alloy clad thin plate is crimped. Comparative specimen floor 2 was prepared consisting of a pipe body that had not been used.

The tubes of the present invention specimens 1 to 4 and comparison specimens Nal and 2 prepared as described above were bent into a meandering shape as shown in FIG. were temporarily attached to form an assembly.

Fin material F without brazing filler metal having the chemical composition shown in Table 2 was temporarily attached to the present invention specimens N111 to 4 and the comparative specimen 1, and to the comparative specimen N12, A thin plate having the chemical composition shown as fin material F is used as a core material,
A gray song sheet fin clad with wax Attachment 1 in Table 2 was temporarily attached to the surface thereof.

The dimensions of the assembly thus formed are as shown in FIG. 4, with a width t of 200 m and a height h of 300 m.

The distance a between the tubes bent in a meandering shape is 30 m.

The fins were temporarily attached with a spacing of 5 m.

The joints of the assembly were then coated with 7 lux, and the assembly was heated at a temperature of 600° C. for 10 minutes in a vacuum furnace maintained at 10 Torr or in a nitrogen gas atmosphere maintained at 760 Torr. The waxing was done by heating.

Next, high-temperature sag resistance, corrosion resistance, and brazing resistance were measured for each of the present invention specimens N111 to 4 and comparative specimens N11 and 2 to which the above-mentioned Yoshifin was brazed by the methods described below. .

(a) High-temperature sag resistance The deformation width S of the fin shown by the dotted line in FIG. 4 was measured, and the high-temperature sag resistance was evaluated based on the obtained measurement value.

(bJ Corrosion resistant dispersible salt water was sprayed for 500 hours, and the resulting maximum depth of pitting corrosion was evaluated.

(C) For brazing, the condition of the brazing of the fins to the sex tube body was examined and evaluated according to the following.

○: Good brazing. ×: Poor brazing. The above measurement results are also shown in Table 3. As is clear from Table 3, the thickness of the aluminum alloy clad thin plate is outside the range of the present invention, and the comparison specimen 1 is made of a thick tube body.
has poor high-temperature sag resistance, corrosion resistance, and brazing properties. Comparative specimen N12, which is a tube to which an aluminum alloy clad thin plate is not crimped, uses gray song sheet as a fin material, and therefore has extremely poor high-temperature sag resistance and corrosion resistance.

On the other hand, specimens 1 to 4 of the present invention had good high-temperature sag resistance, corrosion resistance, and brazing properties, and in particular,
Invention specimens Nα3 and No.4, in which zinc is contained in the brazing material of the aluminum alloy clad thin plate, have even better corrosion resistance.

〔Effect of the invention〕

As described above, according to the present invention, a heat exchanger can be obtained in which fins can be reliably bonded by brazing without causing sagging or deformation due to heating at high temperatures, and which has excellent corrosion resistance. This provides excellent industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an example of the method for manufacturing the tube body of the present invention, FIG. 2 is a schematic side view, FIG. 3 is a sectional view of the tube body of the present invention, and FIG. FIG. 3 is a schematic side view of the attached assembly; In the drawings, l... tube body, 2... extrusion die, 3.
3'...roll, 4.4'...aluminum alloy clad thin plate, 5...
·fin. Applicant Mitsubishi Aluminum Co., Ltd. Agent Natsuo Shioya (and 1 other person) Figure 1 Figure 2

Claims (2)

[Claims] (1) A tube made of aluminum or aluminum alloy, and an Al-Si or A
A l-Si-Mg based aluminum alloy brazing material is used as a core material, and aluminum is clad as a skin material on both sides of the core material, the total thickness is 8 to 100 μm, and the clad skin material is An aluminum heat exchanger tube body comprising an aluminum alloy clad thin plate whose thickness on one side D is 5 to 20% of the total thickness. (2) A tubular body made of aluminum or an aluminum alloy, and a 0.5 to 4.0 wt.
Al-Si system or Al-Si-M containing % zinc
G-based aluminum alloy brazing material is used as a core material, and aluminum is clad as a skin material on both sides of the core material, and the total thickness is 8 to 100 μm, and each side of the aluminum as the clad skin material is 8 to 100 μm. and an aluminum alloy clad thin plate having a thickness of 5 to 20% of the total thickness.