JPS58153098A - Manufacture of heat exchanging medium - Google Patents

Abstract

PURPOSE:To raise the efficiency of manufacturing a heat exchanging medium considerably as compared with the case in which the heat exchanging medium is manufactured directly from aluminum or an aluminum alloy, by applying a bechmite coating over the surface of aluminum or an aluminum alloy before the process of drawing press working. CONSTITUTION:Bechmite process is applied over the surface of aluminum or an aluminum alloy to form a bechmite coating having a thickness of about 2- 12mg/dm<2>, preferably, about 5-8mg/dm<2>, and fins are formed by applying drawing press working after forming of the bechmite coating layer. By thus forming a heat exchanging medium, the baimite coating can be protected against damages since no cracks or damages are caused at drawn and flared parts. Further, since the bechmite coating is excellent in its corrosion resistance and wetting properties, the efficiency of heat transfer can be also raised.

Description

Detailed Description of the Invention: When aluminum or aluminum alloy is subjected to draw press force [J] to produce a heat exchange medium, a boehmite film is formed on aluminum or aluminum alloy in the previous step of the draw press process. As a result, the production efficiency for producing heat exchange media is further improved compared to aluminum or aluminum alloy systems, and production costs are lowered. In addition, the thickness of the boehmite film formed before the draw press processing process can be reduced to about 2 to 1 2. By setting it to 7n';l/dynj, particularly desirably about 5 to 8mg/dI, damage to the film will not occur during drawpressing even if a film is formed by boehmite treatment before the drawpressing process. It is easy to mold and process, has an extremely high manufacturing yield, and is low cost.The heat exchange medium that is molded and assembled has excellent heat exchange efficiency and is also highly corrosion resistant. The purpose of the present invention is to provide a method for producing a heat exchange medium.

A heat exchange medium made of aluminum or an aluminum alloy (hereinafter simply referred to as aluminum) is made of an aluminum material that is formed into a predetermined shape as a heat exchange medium by tro-pressing. It is made by applying surface treatment to a draw press workpiece. In particular, the film treated with boehmite is more preferable than the one in terms of rust prevention and water resistance, but if the boehmite treatment is performed after tro-pressing, Since oil adhering during pressing cannot be completely removed, uneven surface treatment occurs, and the features of the boehmite film, namely rust prevention and water wettability, are not fully demonstrated, and corrosion resistance and heat exchange efficiency are also poor. It becomes something.

Therefore, while researching how to prevent the characteristics of the boehmite film from deteriorating, the inventor performed boehmite treatment before the draw press processing process, and found that However, we thought that it would be a good idea to create a heat exchange medium by draw-pressing an aluminum material, so we performed draw-pressing after forming a boehmite film to create a heat-exchange medium. If this is done, the boehmite film will be damaged by the draw press process, cracks will occur especially at the drawn part, part of the flare will be damaged, the heat conversion performance of the fin material will deteriorate, and the corrosion resistance will deteriorate. Ta. Therefore, we continued our research and conducted detailed experiments to find out what type of boehmite film should be used to prevent damage to the aluminum material on which the boehmite film was formed during draw press processing.As a result, we determined the thickness of the boehmite film. If the boehmite treatment is applied so that the amount is about 2 to 12 mg/dm, preferably about 5 to 81 ng/di, even if the fin material is formed by draw pressing after the boehmite film is formed, there will be no damage to the drawn part. No cracks occur, no part of the flare is damaged, no damage to the boehmite film occurs, the boehmite film remains well formed, has high corrosion resistance, and has good water wettability. Therefore, it was found that the heat exchange efficiency was also excellent. Furthermore, since boehmite treatment is performed before draw press processing, processing unevenness does not occur, and the amount of processing liquid taken out is extremely small.Furthermore, processing efficiency is greatly improved, resulting in excellent manufacturing efficiency and low cost. It was possible to do this.

Examples of the method for producing a heat exchange medium according to the present invention will be described below.

Example 1 Thin wrought material made of aluminum alloy of JIS 050-0 material (width 500 mm, length 3000 mm, thickness Q
, 120 mm) *, hypochlorous acid) IJium aqueous solution CClO concentration 200 ppm, PH 10.6-10
．． 8) at a temperature of about 80 to 85°C for about 3 minutes to form a film on the surface of the wrought material, then washed with water, and then soaked in a water glass solution with a concentration of 05% and a pH of 11.2 for about 90 minutes. °
The treatment is carried out under the conditions of C for about 30 seconds, followed by showering, immersion washing, and drying treatment at about 100″G for 3 () seconds. The thickness of the boehmite film thus formed on the surface of the expanded material is It was approximately 5”i/dynj.

Next, the wrought material on which the film has been formed is subjected to a predetermined draw press process as described in 1 above to form a fin material.

Example 2 The same aluminum alloy wrought material as in Example 1 was heated to pH 6,
A boehmite film having a thickness of about 6.57 ny/di'' was formed on the surface of the wrought material by immersion in the demineralized water of No. 5 at a temperature of about 95° C. for about 5 minutes, and then dried.

Next, the wrought material on which the film has been formed as described above is subjected to a predetermined draw press process to form a fin material having a desired shape.

Example 3 The same aluminum alloy wrought material as in Example 1 was prepared at a pH of 10
, 6 to 108 sodium hypochlorite aqueous solution (ClO concentration 2 oppm) at a temperature of about 80 to 85°C for about 5 minutes to form a boehmite film of about 8"V (brt thickness) on the surface of the wrought material. After forming, it is washed with water and then dried.

Next, the stretched material on which the film has been formed as described above is draw-pressed to form a fin material having a desired shape.

Comparative Example A wrought aluminum alloy material similar to that of Example V above was
After forming a boehmite film on the surface of the wrought material by immersing it in an ammonia aqueous solution with a concentration of 19's and a pH of 11,2 for about 4 minutes at a temperature of about 95°C, it was soaked in a water glass solution with a concentration of 19' s and a pH of 11,2 for about 4 minutes. It is immersed for about 45 seconds at a temperature of .degree. C., then showered, rinsed with water, and dried. The thickness of the boehmite film thus formed was approximately 14 .mu./d77Lt.

Next, the wrought material on which the film has been formed as described above is subjected to a draw press process similar to that of the above embodiment to form a fin material.

In Examples 1 and Comparative Examples, even when the fin materials made by draw pressing after forming the boehmite film were closely observed, no abnormalities due to the rope pressing were observed in the fin materials of Examples 1 to 3. In other words, there were no defects such as cracks in the drawing part due to draw press processing or damage to part of the flare, and the fin material was free of defects. In other words, the boehmite film will not be damaged even if draw press processing is performed after forming the boehmite film, and therefore the features of the boehmite film, such as rust prevention and water wettability, will be maximized. This is done before the draw press process, so the boehmite treatment is done evenly and well.
There is no unevenness in processing and the processing efficiency is extremely high.

In contrast, although the fin material used as a comparative example has been successfully treated with boehmite, cracks occur in part of the flare due to the draw press processing, making it a defective fin material. The corrosion resistance as a material was insufficient, the heat exchange efficiency was also not very good, and furthermore, the moldability at the time of trow pressure n processing was not so good, and the physiological properties were poor.

In addition, the thickness of the boehmite film formed on the light surface of the wrought material is approximately 2
~12 mfl/dm2, about 5-8 mg/6.
J, when draw-pressing an aluminum material on which a boehmite film of such thickness is formed, it not only has good draw-press workability but also has excellent heat exchange efficiency and corrosion resistance. Met.

In addition, if the boehmite film is treated with a silicate solution after forming the boehmite film and before draw pressing, the surface of the fin material will not become wet even if it is degreased with Triclean liquid after draw pressing. There is almost no deterioration in the characteristics, or even if degreasing is performed with a medium alkaline degreasing agent such as Pt4+2, the water wettability of the fin material surface is hardly decreased, and it is no longer attacked by the degreasing solution, and the heat exchange efficiency is reduced. Highly preferred.

As described above, the method for producing a heat exchange medium according to the present invention is applied to aluminum or aluminum alloy material with a film thickness of about 2 to 12 r.
ug/ (1, After forming the boehmite film in a, the heat exchange medium is manufactured by draw pressing the material. Therefore, the heat exchange medium can be efficiently manufactured by draw pressing, and the manufacturing process is easy. The cost is low, and even though a boehmite film is formed before the draw press process, no defects occur during the draw press process, and for example, the product has excellent corrosion resistance and heat exchange efficiency. It also has features such as good draw press workability.

Claims (1)

[Claims] Aluminum or aluminum alloy phase with a film thickness of approximately 2 to 1
After forming a boehmite film of 2my/d71”,
A method for manufacturing a heat exchange medium, characterized in that the heat exchange medium is manufactured by draw-pressing the accumulated moon.