JP2003080366A - Fabricating method of heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fabricating method of heat exchanger which is excellent in durable strength and is excellent in production efficiency. SOLUTION: In this method, a heat exchanger 1 composed of a core part 11 having a tube 13 through which a heating medium flows and a radiating fin 14 which is connected to the surface of the tube 13 and a tank part 12 communicating with the tube 13 is fabricated. By performing successively a preheating process, a brazing process, an annealing process and a cooling process, the brazing between the tank part 12 and the tube 13, and between the tube 13 and the radiating fin 14 is performed. In the preheating process, the tank part 12 which has a larger heat capacity in the heat exchanger 1 is elevated in temperature earlier than the core part 11 which has a smaller heat capacity.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention comprises, for example, a core part having a tube through which a heat medium flows and a heat radiation fin joined to the surface of the tube, and a tank part communicating with the tube, and the heat capacity is partially It relates to a method of manufacturing different heat exchangers.

[0002]

2. Description of the Related Art Conventionally, there is a heat exchanger including a core part having a tube through which a heat medium flows and a heat radiation fin joined to the surface of the tube, and a tank part communicating with the tube (see FIG. 1). ). In manufacturing the heat exchanger, the tank portion and the tube, and the tube and the radiation fin are joined by brazing. That is, the above-mentioned members are brazed to each other by sequentially performing the preheating process, the brazing process, the slow cooling process, and the cooling process.

Specifically, a brazing material containing flux is arranged at the joint of each member and the above members are assembled. The assembly of this heat exchanger is heated in the above preheating step until the flux is melted. Subsequently, in the brazing process, heating is performed until the brazing material melts. Next, in the slow cooling step, the brazing material is cooled until it solidifies. Subsequently, in the cooling process, the heat exchanger is cooled to normal temperature.

[0004]

However, the above conventional method of manufacturing a heat exchanger has the following problems. That is, the heat exchanger includes a small heat capacity part having a relatively small plate thickness such as a core part and a small heat capacity, and a large heat capacity having a large heat capacity composed of a member having a relatively large plate thickness such as a tank part. And a department. Therefore, it is difficult to uniformly raise the temperature of the entire assembly when heating the assembly in the preheating step. Therefore, in the preheating process, it is necessary to continue heating until the large heat capacity part reaches the brazing temperature even after the small heat capacity part reaches the brazing temperature. This prolongs the heating time in the preheating process, making it difficult to improve the production efficiency of the heat exchanger.

Further, if the heating time becomes long, the brazing material (especially Si) may diffuse into the thin member such as the heat radiation fin, and erosion may occur in the member. In some cases, the heat radiation fins may be melted or the product may not have sufficient durability due to the reduction in plate thickness.

Further, in manufacturing the heat exchanger, a means for suppressing the progress of corrosion in the plate thickness direction is adopted by a cathodic protection method in order to ensure corrosion resistance. However,
If each member is made thin, it is difficult to ensure sufficient corrosion resistance even by such means.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a method for manufacturing a heat exchanger having excellent durability and production efficiency.

[0008]

According to the present invention, there is manufactured a heat exchanger comprising a core portion having a tube through which a heat medium flows and a heat radiation fin joined to the surface of the tube, and a tank portion communicating with the tube. In the method, when the tank portion and the tube, and the tube and the radiation fin are brazed by sequentially performing a preheating step, a brazing step, a slow cooling step, and a cooling step, in the preheating step, Of the above heat exchanger, the large heat capacity part with large heat capacity is
A heat exchanger manufacturing method is characterized in that the temperature is raised before the small heat capacity portion having a smaller heat capacity than the large heat capacity portion (claim 1).

As described above, in the preheating step, the large heat capacity part is heated before the small heat capacity part. That is, the large heat capacity part, which is difficult to heat up, is heated first. As a result, due to the radiation, hot air circulation, or heat transfer, the small heat capacity part also follows the large heat capacity part to rise in temperature, so that the entire heat exchanger is soaked. Since the small heat capacity part easily heats up, it is possible to follow the temperature of the large heat capacity part. As a result, the temperature rising time of the entire heat exchanger is shortened, and the production efficiency can be improved. Further, this shortens the heating time, so that it is possible to prevent the occurrence of problems such as diffusion of the brazing material into the small heat capacity portion and erosion. As a result, a heat exchanger having excellent durability can be obtained. Further, this makes it possible to sufficiently cope with the reduction in the plate thickness of the members constituting the heat exchanger.

As described above, according to the present invention, it is possible to provide a method of manufacturing a heat exchanger having excellent durability and production efficiency.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention (Claim 1), the preheating step means, for example, that the flux contained in the brazing filler metal, which is arranged at the joint portion of each member such as a tube or a radiation fin, is melted. The process of heating to. The brazing process is, for example, a process of heating until the brazing material melts after the preheating process is completed. The gradual cooling step means, for example, a step of cooling until the brazing material is solidified after the brazing step is completed. The cooling step means, for example, a step of cooling the heat exchanger until it reaches room temperature after the slow cooling step.

Further, the heat exchanger can be used, for example, in various heaters, vehicle radiators, condensers (condensers) constituting vehicle air conditioners, evaporators (evaporators), compressors (compressors) and the like. .

It is preferable that the large heat capacity part is the tank part and the small heat capacity part is the core part. In this case, in manufacturing a heat exchanger having a tank part having a large heat capacity and a core part having a small heat capacity, it is possible to provide a manufacturing method of a heat exchanger having excellent durability strength and production efficiency. it can.

Further, in the preheating step, it is preferable to blow a high temperature gas onto the large heat capacity portion (claim 3). In this case, the large heat capacity portion can be heated first easily and reliably.

The high-temperature gas may be a gas obtained by burning a combustion gas in the atmosphere (claim 4).
In this case, the large heat capacity part can be heated easily and reliably.

The high temperature gas may be nitrogen gas (claim 5). Even in this case, easily and surely
The large heat capacity part can be heated. In addition, it is possible to reliably prevent oxidation of the heat exchanger.

Further, it is preferable that the high temperature gas has a temperature of 450 ° C. or higher. In this case, the heating time of the large heat capacity part can be shortened sufficiently.

The high temperature gas preferably has a wind velocity of 5 m / sec or more (claim 7). In this case, the heating time of the large heat capacity part can be shortened sufficiently.

The high temperature gas has a temperature of 450 to 65.
More preferably, it is 0 ° C. (claim 8). In this case, the heating time of the large heat capacity part can be sufficiently shortened, and brazing can be reliably performed without lowering the durability strength of the heat exchanger.

If the temperature of the high temperature gas is less than 450 ° C., the temperature rise time of the heat exchanger may not be sufficiently shortened. In addition, it may be difficult to reliably perform brazing. On the other hand, if the temperature is higher than 650 ° C., the brazing material may be diffused or eroded, which may lower the durability of the heat exchanger.

The high temperature gas has a wind velocity of 5 to 15 m /
More preferably, it is second (claim 9). In this case, the heating time of the large heat capacity part can be sufficiently shortened, and brazing can be reliably performed without lowering the durability strength of the heat exchanger.

Further, when the wind speed is less than 5 m / sec, it may be difficult to raise the temperature of the large heat capacity part before the small heat capacity part. On the other hand, if the wind speed exceeds 15 m / sec, the large heat capacity part may locally cause diffusion or erosion of the brazing material, which may reduce the durability of the heat exchanger.

[0023]

EXAMPLES Example 1 A method for manufacturing a heat exchanger according to an example of the present invention will be described with reference to FIGS. As shown in FIG. 1, the method of manufacturing the heat exchanger of the present example is as follows.
1 and a pair of tank parts 12 is a method for manufacturing a heat exchanger 1. The core portion 11 has a tube 13 through which a heat medium flows and a radiation fin 14 joined to the surface of the tube 13 (FIGS. 1 and 4). The tank part 12
Communicate with the tube 13 (FIG. 5).

By performing the preheating step, the brazing step, the slow cooling step and the cooling step in this order, the tank portion 12 and the tube 13, and the tube 13 and the radiation fin 1
Braze 4 and. In the preheating step, as shown in FIG. 3, the tank portion 12 which is a large heat capacity portion of the heat exchanger 1 has a large heat capacity, and the core portion which is a small heat capacity portion of which has a heat capacity smaller than that of the tank portion 12. The temperature is raised before 11. In FIG. 3, the solid line (symbol E) represents the temperature change of the tank portion 12, and the broken line (symbol F) represents the temperature change of the core portion 11.

As a means for raising the temperature of the tank portion 12 first, in the preheating step, as shown in FIGS. 1 and 2, the high temperature gas 2 is blown to the tank portion 12 which is the large heat capacity portion. Specifically, the heat exchanger 1 having the upper and lower tank portions 12 as shown in FIG. 1 is arranged in the heat treatment furnace 3 as shown in FIG. On the upper surface 31 and the lower surface 32 of the heat treatment furnace 3, jet ports 33 for jetting the high temperature gas 2 are provided. The hot gas 2 is blown from the jet port 31 toward the tank portion 12 of the heat exchanger 1. In addition,
The hot gas 2 is supplied to the tank portion 1 at the position where the jet port 33 is arranged.
It suffices that it is a position that can be preferentially sprayed onto the upper surface 2 and is not limited to the upper surface 31 and the lower surface 32 of the heat treatment furnace 3.

The high temperature gas 2 is obtained by burning a combustion gas in the atmosphere. The high temperature gas 2 may be nitrogen gas. In this case, oxidation of the heat exchanger 1 can be reliably prevented. In addition, the high temperature gas 2
Is a temperature of 450 to 650 ° C. and a wind speed of 5 to 15 m / sec.

The metal plate forming the tank portion 12 has a large plate thickness of, for example, about 0.6 to 1.0 mm. Therefore, the tank portion 12 has a large heat capacity and it is difficult to raise the temperature. On the other hand, the metal plate forming the core portion 11 has a small plate thickness of, for example, about 0.05 to 0.15 mm. for that reason,
The core portion 11 has a small heat capacity and easily heats up.

The preheating step (reference numeral A in FIG. 3) is a step of heating the high temperature gas 2 to a temperature below the temperature at which the flux described later melts. The brazing step (reference B) is a step of heating until the brazing material 4 is melted after the preheating step is completed. The slow cooling step (reference C) is a step of cooling until the brazing material 4 is solidified after the brazing step is completed. The cooling step (reference D) is a step of cooling the heat exchanger 1 to room temperature after the slow cooling step.

That is, when brazing the heat exchanger 1, the tank portion 12 and the tube 13 and the joint portion of the tube 13 and the radiation fin 14 (FIGS. 4 and 5) are The brazing material 4 containing the flux is arranged and each member is assembled. The assembly of this heat exchanger 1
In the preheating step, the high temperature gas 2 heats the flux to a temperature below the melting temperature. Subsequently, in the brazing process, heating is performed until the brazing material 4 melts. Then,
In the slow cooling step, the brazing material 4 is cooled until it solidifies. Subsequently, in the cooling step, the heat exchanger 1 is cooled to normal temperature. Thereby, the heat exchanger 1 in which the respective members are brazed and joined can be manufactured.

Next, the function and effect of this example will be described. As described above, in the preheating step, the temperature of the tank portion 12 which is the large heat capacity portion is raised before the temperature of the core portion 11 which is the small heat capacity portion (FIG. 3). That is, the temperature of the tank portion 12 that is hard to heat up is first raised. As a result, the core part 11 also rises in temperature by following the tank part 12 by radiation, hot air circulation, or heat transfer (reference numeral 21 in FIG. 2), and the entire heat exchanger 1 is soaked (FIG. 3). Since the temperature of the core portion 11 which is a small heat capacity portion easily rises, quick followability to the temperature of the tank portion 12 can be obtained.

As a result, the temperature rising time of the heat exchanger 1 as a whole is shortened, and the production efficiency can be improved. Further, this shortens the heating time, so that the core portion 11
It is possible to prevent the occurrence of defects such as diffusion of the brazing material 4 and erosion. As a result, the heat exchanger 1 having excellent durability strength can be obtained. Further, this makes it possible to sufficiently cope with the reduction of the plate thickness of the members constituting the heat exchanger 1.

Further, in the preheating step, since the high temperature gas 2 is blown to the tank portion 12, it is possible to easily and reliably raise the temperature of the tank portion 12 first.
Further, since the temperature of the high temperature gas 2 is 450 to 650 ° C. and the wind speed is 5 to 15 m / sec, the temperature rising time of the tank portion 12 can be sufficiently shortened and the durability strength of the heat exchanger 1 is reduced. Brazing can be reliably performed without causing any problems.

As described above, according to this example, it is possible to provide a method for manufacturing a heat exchanger having excellent durability and production efficiency.

(Embodiment 2) In this embodiment, as shown in FIG.
It is an example of a method for manufacturing the heat exchanger 1 having the tank portions 12 on both left and right ends of the core portion 11. In this case, the jet ports 33 for the high temperature gas 2 are arranged on the left and right of the heat exchanger 1, and the high temperature gas 2 is blown onto the tank portion 12. Others,
This is the same as in the first embodiment. Also in this case, the same effect as that of the first embodiment can be obtained.

(Embodiment 3) This embodiment is an example in which the method for manufacturing the heat exchanger of the present invention shown in Embodiment 1 was evaluated as shown in FIGS. The configuration of the heat exchanger evaluated in this example is as shown in Example 1. And
The core part and the tank part were composed of a metal plate made of A3003, and the brazing material was made of A4045.

First, as shown in FIG. 7, the temperature change of the tank part and the temperature change of the core part of the heat exchanger from the preheating step to the cooling step in the manufacturing method of the present invention were measured. Here, the wind velocity of the hot gas is 12 m / sec and the temperature is 60
It was set to 0 ° C. In FIG. 7, the solid line (symbol E) represents the temperature change of the tank portion, and the broken line (symbol F) represents the temperature change of the core portion.

Next, as shown in FIG.
The relationship between the time T held at 0 ° C. or higher and the Zn diffusion depth was measured. The measurement was performed by paying attention to the holding time of 450 ° C or higher in the core part and the tank part. Zn diffusion due to brazing was about 450 ° C in the core part and the tank part of the heat exchanger.
This is because it is very active in the above areas.

The Zn diffusion was measured by measuring the total plate thickness of 0.2.
The measurement was performed on a portion near the center of the core of a tube made of a metal plate of mm. Also, the metal plate of this part is A300
0.15 mm of a core material made of 3 and Al-10Si-2.
It is a clad material composed of 0.03 mm of a sacrificial material made of 7Zn and 0.02 mm of a brazing material made of A4045. The sacrificial material is made of a metal having a lower electric potential than the core material, corrodes preferentially over the core material, and the progress direction of the corrosion is perpendicular to the thickness direction of the metal plate.
This is a layer for suppressing penetration of the metal plate.

Next, as shown in Table 1, the corrosion test of the heat exchanger and the presence or absence of erosion during brazing and melting of the radiation fins were evaluated.

[0040]

[Table 1]

That is, the corrosion depth of the above metal plate was measured when the sulfate ion added salt water combined cycle test was conducted for 500 hours. In addition, it was confirmed whether or not erosion was generated during brazing and that the heat radiation fins were melted. The evaluation was carried out in the manufacturing method of the present invention in which the holding time at 450 ° C. or higher was 8 minutes, 12 minutes, and the conventional manufacturing method.

As can be seen from FIG. 7, in the preheating step, the temperature of the tank portion is raised first, and the temperature of the core portion is raised following the temperature of the tank portion. In the brazing process, both temperatures reach the brazing temperature. The time required to complete the brazing process was about 7 minutes. This is the time until the end of the brazing process by the conventional manufacturing method (about 20 minutes)
About one-third of that.

The above conventional manufacturing method is different from the manufacturing method of the present invention in which the temperature of the tank portion is raised first, and the temperature of the core portion rises quickly, and the temperature of the tank portion catches up with the temperature of the core portion, or It is a method of heating gradually until it shrinks.

Further, according to the manufacturing method of the present invention, as shown in FIG. 7, the holding time T of 450 ° C. or higher is as short as about 8 minutes, and the influence of Zn diffusion on the metal plate forming the core portion and the tank portion is almost eliminated. Never give.

That is, when the holding time T is about 8 minutes, the depth of Zn diffusion is smaller than the thickness of the core material of the metal plate as shown in FIG. 8 (reference numeral G in FIG. 8). In this case, as shown in Table 1, the resulting heat exchanger does not have defects such as penetration due to corrosion, generation of erosion, and melting of heat radiation fins. Further, even when the holding time is set to about 12 minutes, the depth of Zn diffusion is smaller than the thickness of the core material of the metal plate (reference numeral H in FIG. 8),
Problems such as penetration, erosion, and melting of heat radiation fins due to corrosion of the obtained heat exchanger do not occur (Table 1).

On the other hand, according to the conventional manufacturing method, since the holding time T is about 19 minutes, it can be seen from FIG. 8 that the Zn diffusion depth reaches the core material thickness (reference numeral in FIG. 8). I). Then, in this case, as shown in Table 1, problems such as penetration due to corrosion of the obtained heat exchanger, erosion, and melting of the radiation fin occurred. That is, according to the present invention, it can be seen that the durability strength can be secured even if the members constituting the heat exchanger are made thin. As described above, the evaluation results of this example show that the heat exchanger manufacturing method of the present invention makes it possible to obtain a heat exchanger having excellent durability strength with high production efficiency.

[Brief description of drawings]

FIG. 1 is a perspective explanatory view showing a flow of a heat exchanger and a high temperature gas according to a first embodiment.

FIG. 2 is a cross-sectional explanatory view showing the flow of a heat exchanger and a high temperature gas in the first embodiment.

FIG. 3 is a diagram showing an outline of temperature changes of a core portion and a tank portion in the first embodiment.

FIG. 4 is a perspective view of a joined state of the tube and the radiation fin in the first embodiment.

FIG. 5 is a cross-sectional view of a joined state of the tank portion, the tube, and the radiation fin in the first embodiment.

FIG. 6 is a perspective explanatory view showing the flow of a heat exchanger and a high temperature gas in the second embodiment.

FIG. 7 is a diagram showing temperature changes of a core portion and a tank portion in Example 3.

FIG. 8 is a graph showing the relationship between the Zn diffusion depth and the holding time in which the heat exchanger is kept at 450 ° C. or higher in Example 3.

[Explanation of symbols]

1. ． ． Heat exchanger, 11. ． ． Core part, 12. ． ． Tank part, 13. ． ． tube, 14. ． ． Radiating fins, 2. ． ． Hot gas, 3. ． ． Heat treatment furnace, 33. ． ． Spout, 4. ． ． Brazing material,

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Ogawa             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Takanori Takeda             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Hiroyuki Nishikawa             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Satoshi Nohira             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO F-term (reference) 3L065 CA17

Claims (9)

[Claims] 1. A method for manufacturing a heat exchanger comprising a core part having a tube through which a heat medium flows, a heat radiation fin joined to the surface of the tube, and a tank part communicating with the tube, in a preheating step. The brazing process, the slow cooling process, and the cooling process are sequentially performed to braze the tank portion and the tube, and the tube and the heat radiation fin. In the preheating process, the heat exchanger A method for manufacturing a heat exchanger, characterized in that the large heat capacity part having a large heat capacity is heated before the small heat capacity part having a small heat capacity as compared with the large heat capacity part. 2. The method of manufacturing a heat exchanger according to claim 1, wherein the large heat capacity part is the tank part and the small heat capacity part is the core part. 3. The method of manufacturing a heat exchanger according to claim 1, wherein in the preheating step, a high temperature gas is blown to the large heat capacity portion. 4. The method for manufacturing a heat exchanger according to claim 3, wherein the high temperature gas is a combustion gas burned in the atmosphere. 5. The method of manufacturing a heat exchanger according to claim 3, wherein the high temperature gas is nitrogen gas. 6. The method according to any one of claims 3 to 5,
The method for manufacturing a heat exchanger, wherein the high temperature gas has a temperature of 450 ° C. or higher. 7. The method according to any one of claims 3 to 6,
The method for manufacturing a heat exchanger, wherein the high temperature gas has a wind velocity of 5 m / sec or more. 8. The method for manufacturing a heat exchanger according to claim 6, wherein the high temperature gas has a temperature of 450 to 650 ° C. 9. The method for manufacturing a heat exchanger according to claim 7, wherein the high temperature gas has a wind velocity of 5 to 15 m / sec.