JPH0724900B2 - Method for manufacturing fins of heat exchanger for automobile - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing fins of a heat exchanger for an automobile, which improves the heat exchange function of the heat exchanger for an automobile by improving salt corrosion resistance. The present invention relates to a fin manufacturing method that can be maintained for a long period of time.

[Conventional technology]

Generally, an automobile has a radiator for cooling an engine and a heater for air conditioning. In each of these heat exchangers, fins are attached between a plurality of tubes through which a heat exchange medium (hereinafter abbreviated as medium) flows. To form a core, and seat plates are provided at both ends of the tube of the core to attach a tank.

For example, in a radiator, as shown in FIG. 1, a plurality of vertical tubes (1) for circulating a medium are arranged in parallel, and corrugated fins (2) are mounted between the tubes (1) to form a core (3). To form. Seat plates (4a) and (4b) are provided at both ends of the tube (1) of the core (3), and the tank (5
A) and (5b) are attached.

A brass tube is usually used for the tube (1), and the fin (2) is made of Cu or Cu alloy having high thermal conductivity.
A thin strip of 02 to 0.06 mm is processed into a corrugated shape or a looper shape, and fins (2) are attached to the tube (1) by soldering to form a copper core (3).
In the figure, (6) and (7) are entrances and exits of the medium, (8),
(9) shows a medium pouring / discharging port.

The fins are the most important part that directly determines the heat exchange characteristics, and the Cu or Cu alloy strip (hereinafter abbreviated as Cu series strip) as the fin material can withstand the heating conditions such as soldering in the radiator assembly process and is constant. In order to maintain the strength of, a dilute alloy containing a small amount of Sn, Cd, Ag, Pb, etc. within a range that does not significantly lower the thermal conductivity is used. The most widely used is Cu-0.15% Sn-0.01% P alloy with a tensile strength of 35kg / m.
It has the characteristics of m ² , semi-softening temperature of 135 ℃, and electric conductivity of 85% IACS.

[Problems to be solved by the invention]

In recent years, a large amount of salt such as salt has been widely sprayed as a snow-melting agent in a snowfall area, and a decrease in heat radiation due to corrosion and wear of fins due to such salt has become a problem, especially in radiators. Has been done. On the other hand, there is a strong demand for weight reduction of automobiles, and weight reduction is also required for heat exchangers for automobiles. In order to comply with this, the strength and heat conductivity of the fins are maintained and the wall thickness is made as thin as possible. Therefore, the countermeasures against salt damage have become more serious problems.

In order to solve this, it was attempted to form a corrosion-resistant coating film by means such as painting, but in order to prevent salt damage, 10 μm
The above thick film is indispensable, which is a serious inconvenience for heat dissipation and weight reduction. Attempts have also been made to improve the corrosion resistance by improving the copper alloy for fins, but in order to improve the corrosion resistance,
Since 10% or more of Ni is required, the thermal conductivity is remarkably reduced, and particularly in the case of Cu-10% Ni alloy, the electric conductivity is about 9% IACS, which cannot be used for fins.

[Means for solving problems]

As a result of various studies in view of the above, the present invention has developed a method for manufacturing a fin for a heat exchanger for an automobile, which can withstand the salt damage condition, and can satisfy the conditions of weight reduction and economy. That is, the present invention is
A plurality of tubes made of a copper alloy in which the heat exchanger medium flows, and arranged between the plurality of tubes, and a copper-based fin that is thermally coupled to the tubes to form a core together with the tubes, In manufacturing the copper-based fin of an automobile heat exchanger having tanks attached to both ends of the tube of the core, a non-copper alloy is provided on at least one surface of a fin base material forming the fin. To form a salt-damage-resistant coating layer consisting of
It is characterized in that it is formed into a thickness of ˜3 μm, and the coating layer and the fin base material are heat-treated.

According to the present invention, as shown in FIG. 1, fins (2) are attached between tubes (1) to form a copper core (3), and seat plates (4a) are provided at both ends of the tube (1) of the core (3). , (4b) are provided to form a heat exchanger to which the tanks (5a) and (5b) are attached. In such a heat exchanger, the fin (2) is a non-copper alloy such as Ni, Co or alloys thereof (hereinafter referred to as Ni, etc.) on the surface of the fin base material (10) made of Cu-based strip as shown in FIG. Abbreviated) to form a salt damage-resistant coating layer (11) having a thickness of 0.05 to 3 μm. Examples of Ni and the like include Ni, Co, Ni-Co, Ni-P, Co-B, Ni-Co-P, Ni-Cu, and Ni.
-Sn, Ni-Zn, Ni-Cd and other alloys, both Ni or Co 50
% Or more is used.

Since the coating of Ni or the like on the surface of the fin base material (10) can be pretreated, the productivity is not impaired. For example, a rolled Cu strip is coated with Ni or the like by a method such as electroplating, chemical plating or vapor deposition. By subjecting this to rolling finish, the thickness of the salt damage-resistant coating layer is adjusted to 0.05 to 3 μm, and heat treatment is performed. In this way, the Cu-based strip coated with Ni or the like is subjected to corrugation or looper processing to form fins. A copper core may be formed by combining this with a tube that circulates a medium and soldering or the like.

The Cu strip coated with Ni or the like is rolled by a two-stage or multi-stage rolling mill having a work roll diameter of 200 to 400 mm, the rolling speed is about 300 to 500 m / min, and the area reduction rate is 40 to 50%, cooling is done with a mineral rolling oil spray.

[Action]

In the present invention, the surface of the Cu-based strip is coated with Ni, which is a non-copper alloy, in order to improve the corrosion resistance as a fin, in particular, the salt damage corrosion resistance, and the coating thickness of Ni or the like is set to 0.05 to 3 μ. Is less than 0.05μ, sufficient corrosion resistance cannot be obtained, and 3
If it exceeds μ, the heat conductivity of the fin as a whole will be reduced, and in order to obtain a certain heat dissipation characteristic, the fin will be thicker, which is uneconomical and also against the requirement for weight reduction of the heat exchanger. This is because The coating layer of Ni, etc. has higher mechanical strength and heat resistance than Cu-based strips, and when thinning the fin for the purpose of weight reduction and high performance, it strengthens the fin by the skin effect and especially improves bending strength. It is possible to prevent abnormal softening during high-temperature work such as soldering.

Next, examples of the present invention will be described.

〔Example〕

Using a tough-pitch Cu strip having a thickness of 0.038 mm, the following bath was used for plating with Ni or the like to produce the fin material for a heat exchanger shown in Table 1. With respect to this, the strength, the electric conductivity, and the corrosion resistance were investigated after heat-treating at a temperature of 320 ° C. for 3 minutes in the atmosphere by imitating the radiator assembling process. These results are also shown in Table 1 in comparison with the fin material of the conventional heat exchanger.

In addition, the corrosion resistance is based on JIS Z3721 and sprayed with 5% salt water for 2 hours.
After leaving it to stand in the air for 22 hours for one month, the corrosion weight was measured by removing corrosive substances by ultrasonic treatment in a 10% H ₂ SO ₄ solution.

Ni plating bath Ni (SO ₃ NH ₂ ) ₂ 500g / NiCl 20g / H ₃ BO ₃ 30g / bath temperature 45 ℃ Current density 5A / dm ² Ni-10% Co plating bath NiSO ₄ 240g / CoSO ₄ 15g / NiCl 30g / H ₃ BO ₃ 30g / PH 3.2 Bath temperature 45 ° C Current density 3.5A / dm ² Ni-7% P plating bath NiSO ₄ 200g / NiCl ₂ 15g / H ₃ PO ₃ 25g / H ₃ BO ₃ 30g / PH 3.2 Bath temperature 30 ℃ Current density 3A / dm ² As is clear from Table 1, the fin material No. 2 for the heat exchanger according to the present invention having the surface coated with Ni or the like in a thickness of 0.05 to 3 μ
It can be seen that in all of Nos. 8 and 9, a large corrosion resistance effect can be obtained when the electrical conductivity is lowered.

On the other hand, the comparative fin material No. 1 and the conventional fin material No. 9, No. 11, and No. 12, which have a coating thickness of less than 0.05 μm such as Ni, have significantly poor corrosion resistance, while the conventional fin material. It can be seen that No. 10 has excellent corrosion resistance, but has low electric conductivity and inappropriate thermal conductivity.

〔The invention's effect〕

As described above, in the present invention, the surface of the fin base material is coated with a non-copper alloy, and the coating layer is rolled to have a thickness of 0.05 to 3 μm, and then the fin is formed by heat treatment. In particular, the salt corrosion and corrosion resistance is greatly improved, the weight and cost efficiency of the heat exchanger for automobiles are satisfied, and good heat exchange characteristics can be maintained for a long period of time. .

[Brief description of drawings]

FIG. 1 is a front view showing an example of an automobile radiator, and FIG. 2 is a sectional view showing an example of a fin for a heat exchanger according to the present invention. 1 …… Tube 2 …… Fin 3 …… Core 4a, 4b …… Seat plate 5a, 5b …… Tank 10 …… Cu-based strip 11 …… Ni coating layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nobuyuki Shibata 500 Kiyotaki Town, Nikko City, Tochigi Prefecture Furukawa Electric Co., Ltd. Nikko Denki Copper Works (56) Reference JP-A-58-123097 (JP, A) Kai 56-119497 (JP, A) JP 63-213797 (JP, A) Actually open Sho 60-95485 (JP, U) Actual public Sho 58-23117 (JP, Y2)

Claims (2)

[Claims] 1. A plurality of tubes made of a copper alloy in which a heat exchanger medium flows, and arranged between the plurality of tubes, and thermally coupled to the tubes to form a core together with the tubes. In manufacturing the copper-based fin of an automobile heat exchanger including a copper-based fin and tanks attached to both ends of the tube of the core, at least one of fin base materials constituting the fin is manufactured. A salt-corrosion-resistant coating layer made of a non-copper alloy is formed on the surface, the coating layer is formed into a thickness of 0.05 to 3 microns by rolling, and the coating layer and the fin base material are heat-treated. A method for manufacturing a fin of a heat exchanger for an automobile. 2. The method for manufacturing fins of a heat exchanger for an automobile according to claim 1, wherein the salt damage-resistant coating layer is made of nickel (Ni), cobalt (Co), or an alloy thereof. .