JP3345839B2 - Method of manufacturing high strength aluminum alloy fin material for forming - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a draw molding, a drawless molding or a composite molding of both, that is, an overhanging process.
The present invention relates to a method for producing a high-strength aluminum alloy fin material for forming, which is formed by performing all or a part of drawing, burring, ironing, and flaring, and is used as a fin for a room air conditioner.

[0002]

2. Description of the Related Art Generally, an aluminum alloy fin of a heat exchanger for air conditioning has a collar portion for mounting a heat exchange tube on a plate portion (1) as shown in FIGS. 1 (a) to 1 (d).
(2) is formed and is classified into a flat type (a), a louver type (b), a slit type (c), and a corrugated type (d) according to the shape of the plate portion. Draw molding (forming mainly by overhanging) is shown in Fig. 2 (a) to (f).
As shown in the figure, it consists of the process of overhanging (a), squeezing (b)-(d), punching, burring (e), and flaring (f),
Overhang processing is central. Therefore, in the case of this draw molding, excellent elongation is required for the fin material, and it is generally a thick material having a thickness of 0.12 mm or more, and a fining material such as O material or H22 is applied. It is.
In addition, when draw-forming a thin material having a thickness of 0.115 mm or less, problems such as deterioration of formability and insufficient strength may occur, so it is very difficult to reduce the thickness of the fins or to form a high color height of the thin material with the current material. Met. In order to improve the above problem, drawless molding (forming mainly by ironing) has been the mainstream of fin molding for several years. As shown in FIGS. 3 (a) to 3 (d), the drawless molding comprises the steps of punching-hole expansion (b), burring (b), ironing (c), and flaring (d). Since it is used for molding thin fins, it is possible to reduce the thickness of fins (0.115 to 0.105) in low color height molding.
mm). Since drawless molding is excellent in ironing workability and requires some strength, semi-hard materials of H24 to H26 are used. However, high color height molding of a thin material having a thickness of 0.12 mm or less is still difficult, and a thick material is used at present. In addition, molding defects due to mold tool wear of pre-coated (surface treated) fins in long-term press working in drawless molding cause increased mold and tool maintenance costs and lower the viscosity of lubricating oil ( The use of volatile oil) causes serious deterioration such as deterioration of moldability. Therefore, it is strongly desired to maintain the molding performance and to reduce the mold and tool maintenance costs.

Recently, composite molding (hereinafter simply referred to as composite molding) combining the above draw molding and drawless molding has also been performed. As shown in FIG. 4, composite molding includes the steps of overhang (a), drawing (b), punching, burring (c), ironing (d) (e), and flaring (f). This is a molding method in which ironing is performed after a certain color height is obtained, and the ironing rate can be made smaller than in the case of drawless molding. However, in the currently used aluminum alloy fin material, maintenance of sufficient molding performance and reduction of maintenance cost of molds and tools have not been realized by using any of the molding methods.

[0004]

Means for Solving the Problems The present inventors have made various studies to solve the above problems, and have obtained the following findings. In the soft fin material used for conventional draw molding,
When the thickness is reduced to 0.12 mm or less, there is a problem in that, due to insufficient strength, buckling occurs when the copper tube is inserted into the collar portion, the adhesion between the collar and the heat exchange tube is impaired, and the heat exchange performance is reduced. Get up. Further, the rigid fin material used in the conventional drawless molding can be reduced in thickness because of its high strength, but has a low elongation value, so that high color height molding by draw molding is difficult. In drawless molding, since ironing is mainly performed, it is difficult to significantly reduce problems such as lowering the viscosity of a lubricating oil, deterioration of moldability due to a play coat film, and tool wear in a long-term press. As a means to solve the above, by draw molding,
If a hard pre-coated fin of 0.12 mm or less can be formed, it is possible to suppress the deterioration of the formability due to the decrease in lubricity and to reduce the maintenance cost due to tool wear. However, with a thin material having a thickness of 0.105 mm or less, a good molded product by draw molding cannot be obtained. In addition, with the use of volatile oil to omit cleaning after molding, recently, draw molding and drawless molding are combined, and after a certain color height is obtained by overhanging and drawing, ironing is performed. Since composite molding with a reduced ironing rate has also appeared, it is possible to mold hard pre-coated fins of 0.12 mm or less by composite molding. Although the reduction can be achieved, a conventional hard material has a low elongation value, and particularly a thin material having a thickness of 0.105 mm or less cannot obtain a good molded product by composite molding. If a material having both the strength and moldability required for drawless molding, and the elongation value and moldability required for draw molding can be obtained, draw molding as thin fins of 0.12 mm or less,
Molding by drawless molding or composite molding becomes possible. By controlling the added amounts of Si, Fe, Mn, and Ti, and the manufacturing process and conditions, a metallographic state within the scope of the present invention can be obtained, and a material corresponding to the above can be obtained.

The present invention has been made based on the above findings.
Si 0.1 wt% or less, Fe 0.10-1.0 wt%, Mn
0.10 to 0.50 wt%, Ti 0.01 to 0.15 wt%
After the homogenization treatment of holding the Al alloy ingot consisting of Al and unavoidable impurities at a temperature of 400 to 500 ° C. for 1 to 30 hours, hot rolling is immediately performed, and the hot rolling is performed. Rolling from a thickness of 100 mm to the thickness after hot rolling is performed at a rolling reduction of 7 passes or more, and then cold rolling is performed so that the rolling reduction of the final cold rolling is 80% or more. , resulting thin plate subjected to temper annealing at a temperature of 250 to 320 ° C., 10 pieces in number density below intermetallic compounds diameter 0.1μm in metallographic / [mu] m ³ to more distributed, final thickness
Method for producing a molding aluminum alloy fin material, characterized in the following and to Rukoto 0.12mm to.

[0006]

The reasons for limiting the alloy composition and the manufacturing conditions in the present invention as described above will be explained. First, the reason why the alloy composition is limited as in the present invention will be described. The aluminum alloy fin material of the present invention has an Si content of 0.1 wt% or less (hereinafter simply abbreviated as%), Fe 0.10 to 1.0%, Mn 0.10 to 0.50.
%, And 0.01 to 0.15% of Ti, the balance being Al and unavoidable impurities, and having an intermetallic compound having a diameter of 0.1 μm or less in the metal structure before forming by number density of 1 μm.
0 / μm ³ or more. S
i, Fe, and Mn are partially dissolved in aluminum and have an effect of increasing the strength of the fin material. In particular, Mn has the effect of improving the elongation value. Ti partially forms a solid solution in aluminum and has a function of refining the structure. In particular, at the time of temper annealing, it has the effect of promoting the recovery uniformly and making the sub-grains uniform and fine, and thus has the effect of improving the overhang and drawing workability. It is said that Ti has a function of improving the local elongation of the material. Among the fin forming processes, particularly in the case of performing flange forming such as flares, the higher the local elongation, the higher the forming performance tends to be. Therefore, the present invention specifies the amount of Ti added. Here, if the addition amounts of Fe and Mn are less than 0.10%, desired strength and elongation due to elemental solid solution cannot be obtained,
The fine intermetallic compound having a diameter of 0.1 μm or less is also reduced, and the effect of suppressing the growth of the recovery subgrain during the temper annealing of the processed structure of the final sheet is reduced. The strength must be reduced, and the ironing property and the flaring property in the composite molding are also reduced. Furthermore, the subgrain distribution tends to be uneven,
For this reason, the drawability, drawability, etc. are actually reduced during draw molding, and the molded product is defective due to insufficient strength. On the other hand, the addition amount of Si is more than 0.1%, the addition amount of Fe is more than 1.00%, and the addition amount of Mn is 0.5%.
If it is more than 0%, the intermetallic compound becomes coarse due to coarsening.
The amount of fine intermetallic compounds of 1 μm or less is reduced, and the crystallized material during casting is also coarse. Therefore, during molding, the overhanging property, drawability, etc. are reduced with uneven deformation near the coarse crystallized material. As a result, the molded article becomes defective. Therefore, the addition amount of Si is 0.1% or less, the addition amount of Fe is 0.10 to 1.0%,
It is necessary that the amount of added Mn be 0.10 to 0.50%. If the added amount of Ti is less than 0.01%, not only the effect of making the sub-grains uniform and fine cannot be obtained, but also the moldability, especially the overhang property, the drawability, and the flaring property cannot be further improved. On the other hand, when the amount of Ti added is 0.1
If it exceeds 5%, coarse Ti-based compounds are distributed, and it is difficult to form uniform and fine sub-grains. Therefore, the amount of Ti added is 0.01 to 0.15.
%. As other elements, Zr, Cu, Y, Hf, and the like are added for the purpose of improving the balance between strength and elongation or improving formability without any problem.

In the present invention, the fine intermetallic compound in the metal structure before forming is defined to have a diameter of 0.1 μm or less. If the diameter is larger than 0.1 μm, the processed structure of the final sheet is recovered during temper annealing. The effect of delaying the subgrain movement at the grain boundary is reduced, and as a result, the strength must be reduced in order to secure the elongation value, and the subgrain distribution tends to be non-uniform, so it is actually drawn molding or composite At the time of molding, overhanging property, drawability, flaring property and the like are reduced, and molded articles are liable to be defective due to insufficient strength. Further, the distribution of the intermetallic compound having a diameter of 0.1 μm or less
The reason why the number is defined as 0 / μm ³ or more is that if the number is less than 10 / μm ³ , the above-mentioned effects are hardly obtained, and therefore, there is no effect of improving the overhanging property, drawability, flaring property, strength and the like.

Next, the manufacturing method of the present invention will be described.
The method for producing an aluminum alloy fin material of the present invention suppresses coarse precipitation in the homogenization treatment, and promotes precipitation of fine intermetallic compounds having a diameter of 0.1 μm or less during hot rolling or temper annealing. For this purpose, first, an ingot having the above alloy composition is subjected to a homogenization treatment at a temperature of 400 to 500 ° C. for 1 to 30 hours. If the homogenization temperature is lower than 400 ° C, the ingot structure is not sufficiently homogenized, and the solid solution amount of the additional element forcibly dissolved during casting cannot be reduced. It is easy to crack and mold cracks occur frequently. In addition, the structure after hot rolling becomes non-uniform, and the stretchability, drawability, and flaring properties during draw molding or composite molding are deteriorated. On the other hand, when the homogenization treatment temperature exceeds 500 ° C., a sufficient solid solubility is obtained, but the crystallized product is coarsely spherical and adversely affects the moldability, which is not preferable. In particular, it is difficult to sufficiently precipitate a fine intermetallic compound having a diameter of 0.1 μm or less, which suppresses the occurrence of recrystallization and improves the elongation value. Actually, at the time of draw molding, composite molding, overhanging property, drawability, It is not preferable because the flaring property and the like deteriorate. If the holding time is less than 1 hour, many fine intermetallic compounds can be formed, but the amount of elemental solid solution cannot be reduced, and ironing workability is deteriorated. On the other hand, when held for more than 30 hours, the amount of elemental solid solution is considerably reduced, but the precipitates are coarsened and many recrystallization nuclei are easily formed during temper annealing, so that the formability is rather deteriorated. Is not preferred.

Immediately after the homogenization treatment, hot rolling is performed.
In this hot rolling, it is necessary to perform rolling from a thickness of 100 mm to a thickness after hot rolling at a rolling reduction of 7 passes or more. If the number of passes is less than 7 passes, the amount of reduction in each pass becomes large, and as a result of repeated recovery and recrystallization between passes, old grains that are likely to become recrystallization nuclei during temper annealing in the hot-rolled sheet after the final pass are completed. As a result, a large number of fields are generated, and the drawability, drawability, and flaring property are remarkably deteriorated during draw molding or composite molding.

[0010] The rolling reduction of the final cold rolling is 80%.
When less than 80% is applied, 0.12 is applied.
This is because when draw-forming or composite-forming a thin fin material having a thickness of 0 mm or less, strength is insufficient and problems such as buckling occur.

[0011] The fin material obtained by cold rolling has 25
By performing the temper annealing at a temperature of 0 to 320 ° C., the fin material secures an elongation value required for draw molding and a strength required for composite molding, and good stretchability, drawability, and flaring properties can be obtained. Further, the corrugating property is also improved. If the tempering temperature is less than 250 ° C., sufficient moldability cannot be obtained,
If the temperature exceeds 320 ° C., not only the strength is reduced, but also the elongation is reduced, and recrystallized grains are formed, which serves as a starting point to deteriorate the formability.

[0012]

The present invention will be described below in more detail with reference to examples. Example 1 An Al alloy having an alloy composition shown in Table 1 was produced by water-cooled casting. Ingot by water cooling casting method (400m thick)
m) was subjected to homogenization treatment and hot rolling under the conditions shown in Table 2 by 10 mm on each side, and a hot-rolled sheet having a thickness of 6 mm was obtained. Cold rolled hot rolled sheet, 0.115mm thick, 0.10mm
After forming the sheet to a thickness of 0 mm, it was subjected to temper annealing at a temperature of 250 to 320 ° C. to obtain a forming fin material having a tensile strength of 10.0 to 15.0 kgf / mm ² . Table 3 shows the distribution state of the intermetallic compound of the fin material thus obtained and the results of the evaluation of the formability. Here, regarding the distribution state of the intermetallic compound, the particle diameter of the compound and the number of particles present in a certain volume were measured using a transmission electron microscope. The particle diameter was the diameter of a circle having an area equal to the projected area of the particles. Regarding the moldability test, the result of measuring the limit value of the color molding height by draw molding at a plate thickness of 0.100 mm and 0.115 mm is shown. Next, according to the evaluation by actual molding, a fin material having a thickness of 0.105 mm was used and a color height of 1.6 was used.
The copper tube fixing hole of mm is stretched using a draw molding die, continuously formed by drawing, and performed until the final processing of flaring, and after obtaining 960 collars, a crack is generated at the tip of the flaring (curling) part. The percentage of defective cracks was calculated from the measurement of the number of holes, and the evaluation was performed by comparing the percentage of defective defects with the percentage of defective flare cracks when a 0.130 mm thick fin material of the current material was similarly molded. Similarly, using a composite molding die, continuous overhanging, drawing, ironing, and flaring were performed, and after obtaining 960 colors, the number of holes that had cracks at the tip of the flaring (curling) portion was measured. An evaluation was made by calculating the percentage defective and comparing this with the current material.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

[Table 3]

As is clear from Table 3, the sample N of the present invention
o. Nos. 1 to 11 are conventional material sample Nos. Compared to 22 and 23, draw molding or composite molding is possible with a thinner plate thickness. In particular, stretch forming and flaring moldability by draw molding with a plate thickness of 0.100 mm are superior to conventional materials. Also, the material of the present invention is superior to the conventional material in the limit value of the color molding height at a plate thickness of 0.115 mm. Compared to the conventional material, the material of the present invention has a larger distribution of intermetallic compounds having a diameter of 0.1 μm or less. It acts to delay the movement of the recovery subgrain at the grain boundary, thereby suppressing the generation of recrystallization nuclei, thereby maintaining the strength necessary for composite molding of thin fins, and Overhang, draw formability, and ironing flaring formability are also excellent. Therefore, even if the thickness of the material of the present invention is reduced from 0.130 mm to 0.115 mm, as shown in Table 3, the current sheet thickness (0.130 mm)
The same or higher critical color height level can be secured. Further, even in the composite molding, it is possible to maintain the flared moldability equal to or higher than that of the current material. On the other hand, the comparative material sample no. Nos. 12 to 21 are inferior in drawability, drawability, and flaring property in draw molding, and flaring property in composite molding as compared with the material of the present invention, and the critical collar height is at a level lower than that of the material of the present invention. That is, the comparative material sample No. in which any of Si, Fe, Mn, and the content exceeded the upper limit. Nos. 12, 15, 16, and 20 show that the intermetallic compound is coarsened, the number of fine intermetallic compounds having a diameter of 0.1 μm or less is reduced, and the crystallized product during casting is also coarsened. In addition, the drawability and the flaring property are reduced, resulting in defective molded products. In addition, the comparative material sample No. In Nos. 17 and 18, since the Ti content exceeds the upper limit, a coarse Ti-based compound is distributed, and it is difficult to form a uniform and fine sub-grain. Sex is reduced.

The comparative material sample No. whose production conditions are out of the range of the present invention. 12, 13, 14, 15, 18, 19, 2,
In Nos. 0 and 21, when the draw molding and the composite molding were performed with a plate thickness of 0.105 mm, the overhang property, the drawability, and the flaring property were deteriorated. In addition, even if the homogenization treatment conditions are appropriate, the comparative material sample No. In No. 19, a large number of old grain boundaries are generated, and a sufficient overhang property and an effect of improving the flaring property are not obtained, and the moldability is significantly deteriorated. In addition, even if the hot rolling conditions were appropriate, the homogenization temperature was too low. In No. 21, the structure of the ingot is not sufficiently homogenized, the structure after hot rolling becomes uneven, the work hardens easily, and the ironability deteriorates. Comparative material sample No. with too high homogenization temperature 1
In No. 8, the amount of solid-solution elements is greatly reduced, and in fact, a large amount of coarse intermetallic compounds having a diameter of 0.1 μm or more precipitate in the aluminum matrix. Therefore, when the thin fin is formed, the overhang property and the flaring property are deteriorated.

[Example 2] With respect to some samples of the material of the present invention and the comparative material shown in Table 3, the performance of the base plate for each temper annealing, specifically, tensile strength, elongation, Erichsen value, critical hole The expansion rate was measured, and the results are shown in Table 4. As for the moldability evaluation, as in the case of the molding in Table 3, using a fin material having a thickness of 0.105 mm, using a draw-drawing die of a draw-drawing type and a composite forming die, drawing, drawing, hole-expanding, ironing, and flaring. The evaluation was performed by comparing with the defect rate of the flare crack of the 0.130 mm thick fin material of the current material.

[0019]

[Table 4]

As is clear from Table 4, the material of the present invention has higher elongation value, Erichsen value and critical hole expansion ratio without lowering the strength as compared with the comparative material. Excellent overhang drawing performance in molding,
The ironing performance and the flare performance are maintained.

[0021]

As described above, the fin material obtained by the present invention is excellent in stretchability, drawability, ironing property and flaring property in draw molding and composite molding, and significantly reduces the molding cracking defect rate. It has a remarkable effect of obtaining. Of course, the fin material of the present invention can be applied to drawless molding. In particular, even a thin plate such as 0.100 mm can be color-molded to a height of 1.8 to 2.2 mm with a mold for draw molding, so that it has become possible to significantly reduce equipment and material costs.

[Brief description of the drawings]

FIGS. 1 (a) to 1 (d) each show a form of an aluminum fin of a heat exchanger. (A) is a flat type, (B) is a louver type, (C) is a slit type,
(D) Corrugated type.

FIGS. 2A to 2F are cross-sectional views illustrating a method of forming a fin by draw molding.

FIGS. 3A to 3D are cross-sectional views illustrating a method of forming a fin by drawless molding.

FIGS. 4A to 4F are cross-sectional views illustrating a method of forming a fin by composite molding.

[Description of Signs] 1 Plate part 2 Color part

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C22F 1/00 C22F 1/00 630K 651 651A 683 683 685 685 691 691B 691C 694 694A 694Z (56) Reference JP-A-4-313403 (JP, A) JP-A-3-197652 (JP, A) JP-A-1-234542 (JP, A) JP-A-5-9676 (JP, A) JP-A-5-179382 (JP, A) Japanese Unexamined Patent Application Publication No. Hei 5-9673 (JP, A) Japanese Unexamined Patent Application Publication No. 5-8087 (JP, A) Japanese Unexamined Patent Application Publication No. 5-9674 (JP, A) Japanese Unexamined Patent Application Publication No. 5-9675 (JP, A) JP, A) JP-A-5-104287 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22F 1/04-1/057 C22C 21/00-21/18

Claims (1)

(57) [Claims] 1. Si 0.1 wt% or less, Fe 0.10
1.0 wt%, Mn 0.10-0.50 wt%, Ti0.0
An Al alloy ingot containing 1 to 0.15 wt%, the balance being Al and unavoidable impurities,
Immediately after performing the homogenization treatment of holding for up to 30 hours, hot rolling is performed, and the hot rolling is performed at a rolling reduction such that the rolling from the thickness of 100 mm to the thickness after hot rolling becomes 7 passes or more. Then, cold rolling is performed so that the rolling reduction of the final cold rolling is 80% or more, and the obtained thin plate is subjected to 250-320.
Temper annealing at a temperature of ℃, 0.1μ diameter in the metal structure
10 by the number density less intermetallic compound m / [mu] m ³ to more distributed method of molding a high-strength aluminum alloy fin material for a final sheet thickness characterized by the following and to Rukoto 0.12 mm.