JP2000169926A - Fin material for mechanical caulking type heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fin material for a mechanical caulking type heat exchanger having the strength not to deform the fin material at the time of high-speed transportation and the elongation rate to obviate the occurrence of crack at the time of caulking and joining to tubes. SOLUTION: The fin material is composed of a cold rolled material having the elongation rate of >=3% of an Al alloy containing over 0.1 wt.% and below 1.0 wt.% Si, over 0.1 wt.% and below 1.0 wt.% Fe, over 0.1 wt.% and below 2.0 wt.% Mn, over 0.05 wt.% and below 0.5 wt.% Cu and over 0.1 wt.% and below 5.0 wt.% Zn and consisting of the balance Al and inevitable impurities. This fin material is composed of the cold rolled material of the Al alloy having the prescribed component and, therefore, has the high strength and the elongation rate of >=3%. Then, the deformation of the fins does not occur in spite of the high-speed transportation in automatic assembly of the heat exchangers and the crack hardly occurs at the time of caulking and joining to the tubes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fin material for a mechanical caulking type heat exchanger having strength (rigidity) that does not deform during high-speed conveyance and elongation that does not cause cracking when caulking with a tube.

[0002]

2. Description of the Related Art There are two types of heat exchangers for automobiles: a type in which fins and tubes are joined by brazing, and a type in which fins and tubes are joined by mechanical caulking. As shown in FIG. 1, the mechanical caulking type heat exchanger comprises a core 3 in which a fin 1 and a tube 2 are joined by mechanical caulking, a header plate 4 attached above the core 3, and a header. A header 5 that forms a coolant passage between the plate 4 and the main component is constituted as a main member, and an aluminum alloy is usually used for these members. The mechanical staking of the fin 1 and the tube 2 is performed by punching a hole 6 (b) in the fin material 11 (a) as shown in FIG. The piercing hole 6 is subjected to burring, and a flange (collar) 7 is set up around the piercing hole (c). The tube 2 is inserted into the burring hole 8 (d). 1 and the tube 2 are joined (e).

As shown in FIG. 3, the interval (pitch) between the fins constituting the core portion is defined by the height h of a flange 7 formed by burring, so that the fin pitch p is narrow. In the case of a heat exchanger for automobiles, the height h of the flange 7 may be low, so that cracks are unlikely to occur in burring. However, when the diameter of the tube is expanded, the processing deformation concentrates on a portion of the fin 1 which is in contact with the tube 2, and a crack may be generated. For this reason, a certain degree of elongation is required for the fin material of the heat exchanger for automobiles.

[0004] Further, heat exchangers for automobiles and the like are manufactured by automatic assembly. For this reason, the fin material is required to have rigidity that does not deform even when conveyed at a high speed during automatic assembly. On the other hand, in the mechanical caulking type heat exchanger, the crimping of the tube and the fin is performed by expanding the tube. Sometimes. For this reason, the fin material of the heat exchanger for automobiles has a final cold rolling reduction ratio of 90% after annealing during cold rolling.
A semi-hard material such as H1x material was used.

[0005]

However, in a normal aluminum alloy, the strength (rigidity) that does not deform during high-speed conveyance is increased because the strength increases and the elongation decreases with processing.
In order to obtain fins having an elongation rate that does not cause cracks during crimping, it is necessary to strictly control cold rolling conditions and annealing conditions in the production of fin materials, and it is difficult to control the production conditions. Was.

[0006] In view of the above, the present inventors have conducted various studies on a method for producing a fin material for a mechanical caulking type heat exchanger. As a result, an alloy having a predetermined composition was
When cold rolling is carried out at a remarkably high working ratio to a thickness of about m (fin thickness), high strength is maintained and elongation is found to be increased. Reached. An object of the present invention is to provide a fin material for a mechanical caulking type heat exchanger having a strength (rigidity) that does not deform during high-speed conveyance and an elongation percentage that does not cause cracks when caulking with a tube.

[0007]

According to the first aspect of the present invention,
More than 0.1 wt% of Si and less than 1.0 wt%, 0.1 wt% of Fe
% And 1.0 wt% or less, Mn over 0.1 wt% and 2.0 wt%
%, Cu over 0.05 wt% and 0.5 wt% or less, Zn
Elongation of aluminum alloy containing 0.1 wt% to 5.0 wt% or less, with the balance being Al and unavoidable impurities, 3%
It is a fin material for a machine caulking type heat exchanger constituted by the above cold rolled finished material.

According to a second aspect of the present invention, the content of Si is 0.1 wt%.
Over 1.0 wt%, Fe over 0.1 wt% and 1.0 wt%
Hereinafter, Mn is more than 0.1 wt% to 2.0 wt%, Cu is more than 0.05 wt% to 0.5 wt%, Zn is more than 0.1 wt% to 5.0 wt%, and Zr is more than 0.01 wt% to 0.1 wt%. 2wt%
It is a fin material for a machine caulking type heat exchanger constituted by a cold rolled finished material having an elongation of 3% or more of an aluminum alloy containing the following and the balance of Al and inevitable impurities.

According to a third aspect of the present invention, there is provided a fin material for a mechanical caulking type heat exchanger according to the first aspect, wherein the final cold-rolling reduction rate of the cold-rolled material is 93% or more. .

According to a fourth aspect of the present invention, there is provided the fin material for a mechanical caulking type heat exchanger according to the second aspect, wherein a final cold rolling rate of the cold rolled finished material is 93% or more. .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The fin material of the present invention is a cold rolled material of an aluminum (Al) alloy having a predetermined composition,
A fin material having an elongation of 3% or more. The elongation is such that the final cold-rolling reduction rate is 93% or more and the cold-rolled sheet thickness is 0.
It can be obtained stably when it is as thin as about 1 mm (fin thickness). In the present invention, the final cold rolling work ratio has the most influence on the characteristics.

The fin material of the present invention is manufactured by an ordinary method in which hot rolling and cold rolling are sequentially performed. As described above, the fin material has a sufficiently high strength and a large elongation of 3% or more. The reason for this is considered to be that the rolling texture develops due to the cold rolling process, and when the rolling texture develops, local deformation such as breakage such as constriction observed in a tensile test hardly occurs. This phenomenon is different from the work softening phenomenon in which the strength decreases and the elongation increases as the cold working rate increases.

The alloying elements of the fin material of the present invention will be described below. Si contributes to strength improvement by forming a solid solution in the Al matrix or forming an Al-Mn-Si-based compound. If the content of Si is less than 0.1% by weight, the effect cannot be sufficiently obtained. If the content exceeds 1.0% by weight, a large number of crystallized substances containing Si are generated, and the formability of the fin material is impaired.

Fe precipitates as an Al-Fe compound and suppresses the softening of the work and the occurrence of dynamic recrystallization in the strong working region, thereby contributing to the maintenance of strength. Further, Fe is Al of Mn.
It suppresses solid solution in the matrix and precipitates Mn as a compound to improve the strength. If Fe is less than 0.1% by weight, its effect cannot be sufficiently obtained, and if it exceeds 1.0% by weight, coarse crystallization is generated at the time of casting, thereby reducing workability and making fin production difficult.

[0015] Cu improves the strength and the spring property. If the content of Cu is less than 0.05% by weight, the effect cannot be sufficiently obtained.
If it exceeds 5 wt%, the potential of the fin material becomes noble, and the sacrificial corrosion protection effect on the tube material is reduced.

Mn forms a solid solution in an Al matrix or precipitates as an Al—Mn compound or an Al—Mn—Si compound, thereby contributing to an improvement in strength. These compounds
It suppresses the occurrence of work softening and dynamic recrystallization in the strong working region, and contributes to strength retention. If the content of Mn is less than 0.1% by weight, the effect cannot be sufficiently obtained. If the content is more than 2.0% by weight, coarse crystals are formed at the time of casting, whereby the workability is reduced and the production of fins becomes difficult.

Zn renders the sacrificial anticorrosion effect of the fin on the tube material with a low potential. When the content of Zn is 0.
If it is less than 5 wt%, the effect cannot be obtained sufficiently, and 5.0 wt%
If it exceeds 300, the self-corrosion of the fins becomes high, and a long-term sacrificial anticorrosion effect cannot be expected.

When importance is placed on the strength, Zr is further added. Zr precipitates as a fine Al-Zr-based intermetallic compound, suppresses the softening of the work and the occurrence of dynamic recrystallization in the strong working region, and contributes to the strength retention. When the content of Zr is 0.02
If the amount is less than wt%, the effect cannot be sufficiently obtained. If the amount is more than 0.2% by weight, the workability is reduced and the production of the fin becomes difficult.

In the present invention, inevitable impurities contained in the Al alloy impair the formability of the fin material, so that Mg is less than 0.15 wt%, Na, Cd, Pb, Bi, Ca, C
It is desirable that each of r, V, and K is regulated to 0.03 wt% or less. Ti and B, which refine the casting structure, and Sn and In, which enhance the sacrificial corrosion protection effect, are each 0.05 wt%.
If it is below, it may be added.

[0020]

EXAMPLES (Example 1) A of the composition specified in the present invention shown in Table 1
The alloy is cast in a mold, the resulting ingot is chamfered to remove an oxide film, and then heated at 600 ° C. for 3 hours to perform homogenization treatment, thereby securing a predetermined cold rolling rate. Hot-rolled to various thicknesses of 1.43 to 10.00 mm, and then the hot-rolled sheet is cold-rolled from the above-mentioned thickness to a thickness of 100 μm for any material. Various fin materials were produced. The final cold rolling rate was 93% or more. No annealing was performed during the cold rolling.

Comparative Example 1 The same method as in Example 1 except that the thickness of the sheet material after hot rolling was reduced to 0.71 mm or 1.25 mm and the final cold rolling reduction ratio was less than 93%. To produce a fin material.

Comparative Example 2 A fin material was manufactured in the same manner as in Example 1 except that an Al alloy having a comparative composition shown in Table 1 was used.

Each of the fin materials manufactured in Example 1 and Comparative Example 1 was subjected to punching, burring, tube insertion, and tube expansion as shown in FIG. 2, and then punching, burring, and tube expansion. The number of cracks generated in the fin material was examined for each of the steps. In the tube,
A flat tube having an external dimension of 2.0 mm × 20 mm manufactured by extruding a JIS-3003 alloy was used, and was expanded so that the external dimension became 2.2 mm × 20.4 mm. The fin material was formed into a predetermined number of pieces so that 1,000 forming portions could be secured for each of the punching, burring, and tube expansion processing steps. The results are shown in Tables 2 and 3.

[0024]

[Table 1] (Note) Unit: wt%.

[0025]

[Table 2] (Note) Final cold rolling rate. Number of cracks generated, n = 1000.

[0026]

[Table 3] (Note) Final cold rolling rate. Number of cracks generated, n = 1000.

As is clear from Table 1, No. 1 of the present invention example
Nos. To 14 each had an elongation of 3% or more, and no crack was generated in the fin material in each of the steps of punching, burring, and pipe expansion. In contrast, Nos. 15 to 18 of Comparative Example 1 had low final cold-rolling reduction rates.
In the cases of o.19 to 22, the alloy composition was out of the range specified in the present invention, so that the elongation was less than 3% and cracks occurred in each of the burring and pipe expansion processes. In addition, although the heat exchanger for vehicles was automatically assembled using the fin material of the present invention, the fins did not deform even when conveyed at high speed.

Although the fin material cold-rolled after the hot-rolled sheet has been described above, the fin material which has been subjected to intermediate annealing during the cold rolling or the fin material which has been annealed after the completion of the hot rolling can be used. The same effect can be obtained if the cold rolling reduction after annealing falls within a predetermined range. Further, the fin material of the present invention can be widely applied to applications in which the H1x material has been conventionally used.

[0029]

As described above, since the fin material of the present invention is made of a cold-rolled material of an Al alloy having a predetermined composition, it has high strength and an elongation of 3% or more. Have. Therefore, even when the heat exchanger is automatically assembled and transported at a high speed, the fins are not deformed, and cracks are unlikely to occur at the time of caulking with the tube. Therefore, an industrially remarkable effect is achieved.

[Brief description of the drawings]

FIG. 1 is a partially cutaway explanatory view showing an example of an automobile heat exchanger.

FIG. 2 is a process explanatory view showing an example of mechanically caulking and joining a fin and a tube.

FIG. 3 is an enlarged view of a flange portion of a fin of an automobile heat exchanger.

[Explanation of symbols]

 Reference Signs List 1 fin 2 tube 3 core 4 header plate 5 header 6 punched hole 7 flange 8 header processed hole 11 fin material p fin pitch h flange height

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // C22F 1/00 630 C22F 1/00 630K 630A 651 651A 685 685Z 694 694A (72) Inventor Akio Niikura Chiyoda-ku, Tokyo 2-6-1 Marunouchi Furukawa Electric Co., Ltd. (72) Inventor Seiichi Kato 1-1-1 Showa-cho, Kariya-shi, Aichi Prefecture Denso Corporation (72) Inventor Tetsuya Yamamoto Showa-cho, Kariya-shi, Aichi Prefecture 1-1-1, DENSO Corporation (72) Inventor Kenji Nekura 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture DENSO Corporation

Claims (4)

[Claims] Claims 1. An Si content exceeding 0.1% by weight and 1.0% by weight or less,
Fe over 0.1 wt% and 1.0 wt% or less, Mn 0.1 wt%
% To 2.0 wt% or less, Cu exceeds 0.05 wt% to 0.5
Mechanical caulking type heat exchange made of cold rolled finished material containing 3% or more of aluminum alloy consisting of less than 0.1% by weight, more than 0.1% by weight of Zn and less than 5.0% by weight, and the balance of Al and unavoidable impurities. Dexterous fin material. 2. The method according to claim 1, wherein the content of Si is more than 0.1 wt% and 1.0 wt% or less;
Fe over 0.1 wt% and 1.0 wt% or less, Mn 0.1 wt%
% To 2.0 wt% or less, Cu exceeds 0.05 wt% to 0.5
wt% or less, more than 0.1 wt% Zn to 5.0 wt% or less, Zr
Of aluminum alloy containing 0.01% by weight or more and 0.2% by weight or less and the balance being Al and unavoidable impurities
% Of fin material for machine caulking type heat exchangers composed of cold rolled finished material of more than 10%. 3. The fin material for a mechanically caulked heat exchanger according to claim 1, wherein the final cold-rolling reduction ratio of the cold-rolled material is 93% or more. 4. The fin material for a mechanically caulked heat exchanger according to claim 2, wherein the final cold-rolling reduction ratio of the cold-rolled material is 93% or more.