JP2005193264A - Production method of heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the production method of a heat exchanger having durable strength and whose production efficiency can be remarkably improved. <P>SOLUTION: In the production method of a heat exchanger 1 by performing a preheating stage where a core part 4 and tank parts 5 and 6 are assembled, and the assembled core part 4 and tank parts 5 and 6 are beforehand heated; a brazing stage wherein the core part 4 and tank parts 5 and 6 are brazed; an annealing stage wherein heat in the brazed core part 4 and tank parts 5 and 6 is gently removed; and a cooling stage wherein the core part 4 and tank parts 5 and 6 subjected to the annealing stage are cooled to ordinary temperature in succession, low temperature gas 12 is spouted to the tank parts 5 and 6 in the annealing stage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a heat exchanger such as an evaporator or a condenser, and more particularly to a technique for improving a brazing method between a core portion and a tank portion in an aluminum heat exchanger.

  Generally, heat exchangers made of aluminum include an evaporator, a condenser, a radiator, and the like, and these are generally manufactured by a brazing method. This manufacturing method is performed by assembling various parts of a heat exchanger such as a core part made of tubes, fins, etc., a tank part made of a header plate, a tank cover member, etc. It brazes integrally through the brazing material previously provided in the junction part between various components.

  Various parts of such an aluminum heat exchanger are materials (hereinafter referred to as a core material) based on an aluminum alloy mainly containing pure aluminum and an element such as Mn. Therefore, in order to join the parts to each other, a material obtained by clad a brazing material of an Al-Si alloy having a melting point lower than that of the core material containing Si or the like in aluminum is used on the surface of the core material at the joining portion. . Then, instead of assembling these parts or clad the brazing material, put the brazing material foil at the joint with the core part and assemble these parts, and then apply the flux to the brazed joint Then, brazing is performed in a predetermined furnace, or brazing is performed in a vacuum furnace without applying a flux.

  Specifically, such a brazing operation includes a preheating process in which the assembled core part and the tank part are heated in advance, a brazing process in which the core part and the tank part are brazed, and a brazed core. It consists of a gradual cooling process that gently removes heat from the tank part and the tank part, and a cooling process that cools the core part and tank part that have undergone the gradual cooling process to room temperature. These preheating process, brazing process, gradual cooling process and cooling By sequentially performing the steps, the core part and the tank part are joined to form a heat exchanger.

  However, in such a heat exchanger, since the thickness of the tank portion is larger than the thickness of the core portion, the heat capacity of the tank portion increases, and thus the relationship between the temperature change and the accompanying time is shown. As can be seen from FIG. 6, it takes time for the core portion to reach the brazing step from the preheating step to the core portion, and until the solid phase temperature is reached in the slow cooling step during cooling. It takes time (indicated by a bold line in the figure).

  For this reason, in some cases, during cooling, the brazing material flows from the tank portion to the core portion in the slow cooling step, and erosion may occur in the core portion (particularly, in the tube). Here, erosion means that Si in the brazing material diffuses into the core material, and if the amount of diffusion is excessive, the original melting point of the core material (in this case, 640 [° C.] to 650 [° C.]). This is a phenomenon of lowering and melting near the brazing temperature (in this case, about 590 [° C.]). When the core material is melted due to the occurrence of erosion, there is a possibility that a through hole is generated in the core portion (in this case, a tube).

As one of the techniques for solving such a problem, as shown in FIG. 7, by spraying a high-temperature nitrogen gas into the tank part which is a large heat capacity part in the preheating step and actively heating the tank part, A technique has been proposed in which the temperature of the tank part is increased before the core part, which is a small heat capacity part (indicated by a thick line in the figure), and the preheating process is shortened (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 2003-80366 (pages 3 and 4; FIGS. 1 and 3)

  However, in the manufacturing method of the heat exchanger described in Patent Document 1, it is possible to improve the production efficiency by spraying high-temperature nitrogen gas to the tank portion in the preheating step and shortening the heating time in the preheating step. At the same time, it is possible to prevent the diffusion of brazing material to the core part and the accompanying troubles such as erosion, but it still takes time for the tank part to reach the solid phase temperature in the slow cooling process compared to the core part during cooling. (Indicated by a thick line in FIG. 7), there is still an inadequate problem that may cause problems such as the flow of brazing material to the core and the erosion associated therewith.

  Therefore, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method of manufacturing a heat exchanger that is excellent in durability and can significantly improve production efficiency.

  The invention according to claim 1 is a preheating step in which the core portion and the tank portion are preliminarily heated after the core portion and the tank portion are assembled, and a brazing step in which the core portion and the tank portion are brazed. And a slow cooling process for gently removing the heat of the brazed core part and the tank part, and a cooling process for cooling the core part and the tank part that have undergone the slow cooling process to room temperature in order. In the manufacturing method for manufacturing a low temperature gas in the slow cooling step, a low temperature gas is sprayed onto the tank portion.

  The invention described in claim 2 is the method for manufacturing the heat exchanger according to claim 1, wherein the low-temperature gas is an inert gas.

  The invention described in claim 3 is the method for manufacturing the heat exchanger according to claim 1 or 2, wherein the temperature of the low-temperature gas is 25 [° C.].

  Invention of Claim 4 is a manufacturing method of the heat exchanger as described in any one of Claim 1 to Claim 3, Comprising: The wind speed which injects the said low temperature gas is 3 [m / sec]. It is characterized by consisting of ˜20 [m / sec].

  According to the first aspect of the present invention, the low temperature gas is sprayed onto the tank portion in the slow cooling step, so that the tank portion having a large heat capacity compared to the core portion can be easily and reliably connected to the core portion. Equivalent or faster cooling than the core part, so that erosion caused by the flow of brazing material from the tank part to the core part can be avoided and the brazing time can be shortened. Therefore, it is excellent in strength resistance, and production efficiency can be remarkably improved.

  According to the second aspect of the present invention, since the low temperature gas is an inert gas, the heat exchanger can be reliably prevented from being oxidized.

  According to the invention of claim 3, since the temperature of the low temperature gas is 25 [° C.], it is possible to cool at a temperature of about room temperature. In comparison, the cooling time of the tank portion having a large heat capacity can be sufficiently shortened practically.

  According to the fourth aspect of the present invention, the cooling speed of the tank portion having a larger heat capacity than that of the core portion is obtained when the wind speed at which the low temperature gas is injected is 3 [m / sec] to 20 [m / sec]. The time can be reduced sufficiently in practical use.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. In addition, this Embodiment is an example which applied the heat exchanger of this invention to the radiator for motor vehicles.

"Configuration of Radiator"
FIG. 1 is an external view showing a schematic configuration of a radiator according to the present invention, FIG. 2 is a perspective view for explaining brazing in the manufacturing process of the radiator, and FIG. FIG. 4 is a graph showing the relationship, and FIG. 4 is a diagram showing the constituent materials of the radiator used in the brazing process of FIG.

  As shown in FIG. 1, a radiator 1 that is a heat exchanger of the present embodiment includes a core composed of a plurality of stacked tubes 2 and a plurality of corrugated fins 3 disposed between the adjacent tubes 2 and 2. Connected to the upper header tank portion 5 and the upper header tank portion 5 and the lower header tank portion 6 as tank portions to which the upper end portions and lower end portions of the plurality of tubes 2 in the core portion 4 are respectively connected. An inlet pipe 7 and an outlet pipe 8 are provided.

  The upper and lower header tank portions 5 and 6 are each composed of a header plate 9 and a tank cover member 10 joined to the header plate 9, and a tank chamber (not shown) is formed inside.

  At this time, the radiator 1 is manufactured by the following brazing method. That is, in this manufacturing method, after assembling various parts of the radiator 1 such as the core portion 4 including the tube 2 and the fin 3 and the upper and lower header tank portions 5 and 6 including the header plate 9 and the tank cover member 10, By heating in a furnace (not shown), brazing is integrally performed via a brazing material (not shown) provided in advance at the joint between these various components.

[Experimental considerations]
Here, it investigated about the brazing construction method at the time of manufacturing the radiator 1 actually.

  In the case of the present embodiment, the radiator 1 is formed using aluminum parts, and these various parts mainly have an aluminum alloy containing pure aluminum and an element such as Mn as a core material.

  Therefore, in order to join components together, a brazing material of an Al—Si alloy having a melting point lower than that of the core material containing Si or the like in aluminum is clad on the surface of the core material at the joining portion.

  Then, various parts clad with the brazing material (core part 4, upper and lower header tank parts 5, 6) are assembled, or instead of clad the brazing material, various parts in the core material state (core part 4, After the brazing material foil is placed on the joints of the upper and lower header tank parts 5, 6) and these parts are assembled, flux is applied to the brazed joints and brazed in a predetermined furnace. Brazing in a vacuum furnace without coating.

  Specifically, such a brazing operation includes a preheating process in which the assembled core portion 4 and the upper and lower header tank portions 5 and 6 are heated in advance, and the core portion 4 and the upper and lower header tank portions 5 and 6. A brazing step of brazing 6, a gradually cooling step of gently removing heat from the brazed core portion 4 and the upper and lower header tank portions 5, 6; It consists of a cooling process for cooling the lower header tank parts 5 and 6 to room temperature. By sequentially performing these preheating process, brazing process, slow cooling process and cooling process, the core part 4 and the upper and lower header tank parts 5 , 6 are joined together to form the radiator 1.

  The preheating process melts the flux, the brazing process melts the brazing material, the cooling process solidifies the brazing material, and the cooling process cools the heat exchanger to room temperature.

  And in this Embodiment, as shown in FIG. 2 in the said slow cooling process, among the assembled | attached core part 4 and upper and lower header tank parts 5 and 6, the header plate in upper and lower header tank parts 5 and 6 The low temperature gas 12 is sprayed from the ejection hole of the gas ejection member 11 to the 9 portion.

  At this time, this low temperature gas 12 consists of inert gas, such as nitrogen gas, The temperature shall be 0-35 [degreeC] which is general room temperature, Preferably it shall be about 25 [degreeC]. From the experimental results, it is preferable to blow the low-temperature gas 12 at a wind speed of 3 [m / sec] to 20 [m / sec], aiming at the header plate 9 from the ejection port of the gas ejection member 11. all right. In winter, the outside air temperature is close to 0 ° C, so the wind speed can be small, and it is effective at 3 [m / sec]. In the summer, the outside air temperature is close to 35 ° C, so the wind speed is increased to a maximum of 20 [ m / sec].

  Incidentally, the thicknesses of the tube 2, the fin 3 and the header plate 9 at this time are 0.15 [mm] to 0.30 [mm], 0.06 [mm] to 0.10 [mm], 0. It set in the range of 8 [mm]-1.5 [mm].

  As shown in FIG. 4, the fin 3 is made of 0.08 [mm] aluminum alloy (JIS standard A3003), and the tube 2 is a core material and 0.23 [mm] aluminum alloy (JIS standard A3003). The sacrificial material is 0.03 [mm] aluminum alloy (JIS standard A7072), the brazing material is 0.03 [mm] aluminum alloy (JIS standard A4343), and the header plate 9 is the core material. .04 [mm] aluminum alloy (JIS standard A3003), 0.13 [mm] aluminum alloy (JIS standard A7072) as sacrificial material, 0.13 [mm] aluminum alloy (JIS standard A4343) as brazing material Each of these components was assembled and subjected to brazing addition heat treatment. The relationship between the temperature change of the core part 4 and the header plate 9 in that case, and the time accompanying it is shown in FIG. In FIG. 3, the header plate 9 is abbreviated as a tank portion for convenience.

  As can be seen from FIG. 3, in the slow cooling process at the time of cooling, by spraying low temperature gas 12 onto the assembled core portion 4 and the header plate 9 portions in the upper and lower header tank portions 5 and 6, The header plate 9 is cooled at substantially the same speed as the core part 4 and reaches the solid phase temperature in substantially the same time as compared with the core part 4 (indicated by a one-dot chain line in FIG. 3) before improvement (see FIG. The cooling time can be remarkably shortened as compared with 3).

  As a result, as shown in FIG. 5, no erosion was observed in any of the brazed tube 2 and the joined portion between the tube 2 and the fin 3, and the brazed portion was healthy. In this case, one tube 2 is formed by bending both sides of a flat aluminum plate 2A clad with a brazing material on the surface to approximately 90 ° in the same direction by a method such as a roll homing method. A so-called B-type tube was used, which was bent into a flat tube shape and a middle column formed by abutting the both side portions was erected inside.

  Therefore, in the case of the radiator 1 manufactured using this brazing heat treatment, it is possible to avoid the occurrence of problems such as diffusion of brazing material into the core portion 4 and erosion associated therewith in the brazing heat treatment. In addition, the strength resistance can be improved and the brazing time can be shortened, so that the production efficiency can be significantly improved.

  As described above, according to the method for manufacturing a radiator of the present embodiment, the low temperature gas 12 is sprayed onto the upper and lower header tank parts 5 and 6 in the slow cooling process, so that compared with the core part 4. Since the upper and lower header tank portions 5 and 6 having a large heat capacity can be cooled easily and reliably as fast as the core portion 4 or faster than the core portion 4, the upper and lower header tank portions 5 and 6 can be cooled by the core. The occurrence of erosion due to the flow of the brazing material to the part 4 can be avoided in advance and the brazing time can be shortened, so that the strength is excellent and the production efficiency is remarkably improved. be able to.

  Further, since the low temperature gas 12 is an inert gas such as nitrogen gas, the oxidation of the radiator 1 can be reliably prevented.

  Furthermore, since the temperature of the low-temperature gas 12 is about 25 [° C.], it is possible to cool at a temperature of about room temperature, so that the heat capacity is larger than that of the core portion 4 without excessive cooling. The cooling time for the upper and lower header tank portions 5 and 6 can be shortened practically.

  In addition, since the wind velocity at which the low temperature gas 12 is sprayed is 3 [m / sec] to 20 [m / sec], the upper and lower header tank sections 5 having a larger heat capacity than the core section 4, The cooling time of 6 can be sufficiently shortened practically.

"Other embodiments"
Although specific embodiments to which the present invention is applied have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made.

  In the above-described embodiment, the case where a so-called B-type tube is used as the tube 2 has been described. However, the present invention is not limited to this, and the tube 2 may be a general flat type, an internal Various shapes of tubes such as those having fins can be widely applied, and even in this case, the same effects as those of the above-described embodiment can be obtained.

It is an external view which shows schematic structure of the radiator which concerns on this invention. It is a perspective view with which it uses for description of the brazing in the manufacturing process of a radiator. It is a graph which shows the relationship between the temperature change in the time of brazing process, and the time accompanying it. It is a figure which shows the structural material of the radiator used in the case of the brazing process of FIG. It is a schematic diagram which shows the brazing state in the radiator manufactured by the manufacturing method to which this invention is applied. It is a graph which shows the relationship between the temperature change in the time of the brazing process in the conventional heat exchanger, and the time accompanying it. It is a graph which shows the relationship between the temperature change in the time of the brazing process in the other conventional heat exchanger, and the time accompanying it.

Explanation of symbols

1. Radiator (heat exchanger)
2 ... Tube 3 ... Fin 4 ... Core part 5 ... Upper header tank part (tank part)
6 ... Lower header tank (tank)
DESCRIPTION OF SYMBOLS 9 ... Header plate 10 ... Tank cover member 11 ... Gas ejection member 12 ... Low-temperature gas

Claims (4)

After assembling the core part (4) and the tank part (5, 6), a preheating step of heating the assembled core part (4) and the tank part (5, 6) in advance, and the core part (4) A brazing step for brazing the tank portions (5, 6), a slow cooling step for gently removing heat from the brazed core portion (4) and the tank portions (5, 6), and this slow cooling step In the manufacturing method for manufacturing the heat exchanger (1) by sequentially performing the cooling step of cooling the core part (4) and the tank part (5, 6) to normal temperature through
In the slow cooling step, the low temperature gas (12) is sprayed onto the tank parts (5, 6). It is a manufacturing method of the heat exchanger (1) of Claim 1, Comprising:
The method for producing a heat exchanger, wherein the low-temperature gas (12) is an inert gas. It is a manufacturing method of the heat exchanger (1) of Claim 1 or Claim 2, Comprising:
The method of manufacturing a heat exchanger, wherein the temperature of the low-temperature gas (12) is 25 [° C]. A method for producing a heat exchanger (1) according to any one of claims 1 to 3, comprising:
The method of manufacturing a heat exchanger, wherein the wind velocity at which the low temperature gas (12) is sprayed is 3 [m / sec] to 20 [m / sec].