JP2002001511A - Method for manufacturing heat sink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat sink having a wide heat exchange area in a simple method, by using a number of wide and thin plate fins having large area. SOLUTION: Metal plate fins are held at given intervals in a mold cavity into which the same kind of molten metal as the material of the fins is poured to form a base on the end of the fins. Thin members rolled beforehand can be used as the material of the fins, and there is no limit to a dimension in height. For these reasons fins having an optional area can be used. Further, the fins and the base are composed of the same kind of metal and the fins are cast-deposited with the molten metal of the base so that the fins and the base are integrally formed and firmly joined. This enables a heat sink having a wide heat exchange area to be obtained easily. As the fins and the base are composed of the same kind of material there is almost no potential difference whereby the heat sink having excellent corrosion resistance can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a heat sink used to increase a heat exchange area in various heat exchangers, and more particularly to a method of manufacturing a heat sink made of an aluminum alloy.

[0002]

2. Description of the Related Art It is well known that a heat sink having a large heat radiation or heat absorption area is used in various heat exchangers in order to enhance the heat exchange capacity. One example is shown in FIG. The heat sink 1 shown in FIG. 1 has a structure in which a plurality of fins 2 parallel to each other are erected vertically on the upper surface of a flat base 3. As a method of obtaining such a heat sink, first, a groove is provided in the base 3 and one end of a plate material serving as a main body of the fin 2 is inserted into this groove to caulk. Third, a method of simultaneously molding two parts by a die casting method. Third, a brazing sheet material provided with a brazing material layer on a plate material serving as the main body of the fin 2 is used, and the base 3 and the plate material serving as the fin 2 are brazed and joined. There is known a method or a method in which the fin 2 and the base 3 are integrally formed by an extrusion molding method made of an aluminum alloy.

[0003] In the first method, productivity is not improved because a machining process for forming a groove in the base 3 is required, and work for caulking a narrow gap between the fins 2 is required. There is a disadvantage that it becomes complicated. In the second method, there is a limit in casting a large number of thin fins 2 densely by die casting, and it is difficult to obtain a heat sink 1 having a high heat exchange capacity. In the third method, a brazing sheet material having a brazing material layer provided on the surface of a plate material must be prepared as a fin material, and it is difficult to mass-produce at low cost.

[0004]

In this respect, the fourth extrusion molding method is widely used as a method for manufacturing a heat sink made of an aluminum alloy as a rational method because the base and the fin can be integrally formed from a billet. I have. When the heat sink is obtained by the extrusion molding method, the thickness (t) of the fin 2 main body is a minimum of about 2 mm, and the height of the fin 2 main body when the thickness (t) of the fin 2 main body is set to 2 mm. The maximum height (h) is about 20 mm. Therefore, when a heat sink is obtained by a conventional extrusion molding method, it is difficult to obtain a heat sink in which the fin body is thin and the height is increased to increase the heat exchange area. Further, since the number (number of fins) 2 of the fins 2 that can be installed with respect to the surface area of the base 3 is small, there is a problem that the heat exchange area cannot be increased.

[0005]

Therefore, in the present invention, as a means for solving the above-mentioned problems, a plate-like metal fin material is held at predetermined intervals in a cavity of a mold, and the same kind of fin material as the fin material is provided in the cavity. And a method of pouring the molten metal into a base at the end of the fin material. By adopting this method, it is possible to use a pre-rolled thin member having a small thickness as the fin material, and there is no limitation on the dimension in the height direction, so that a fin having an arbitrary area can be used. . In addition, the fin material and the base material are made of the same kind of metal, and the fins are manufactured by casting the molten metal in the base part, so that the fins and the base are molded integrally, and a strong joint is obtained, so a heat sink with a large heat exchange area can be used. It can be easily obtained. Also, since the fin and the base are made of the same material, there is almost no potential difference,
A heat sink having excellent corrosion resistance can be obtained.

In the present invention, it is preferable that the molten metal poured into the cavity is a molten metal having a melting point lower than that of the fin material metal. Since the melting point of the molten metal is lower than the melting point of the fin material metal, there is no damage to the fin body.Moreover, the fin and the base are integrated and diffusion bonded, so a heat sink with good heat conduction and strong bonding can be used. It is possible to obtain. A preferable material of the present invention is, for example, a material in which the fin material is made of pure aluminum and the molten metal for the base to be poured into the cavity is an Al-Si alloy. If the fin material is made of pure aluminum, a plate material having good thermal conductivity and a thin and large area can be easily obtained at low cost. Also, if an Al-Si alloy is used as the base metal, the melting point is lower than that of pure aluminum and the flow of the molten metal is good, and at the junction between the fin and the base, silicon in the molten metal diffuses into the pure aluminum of the fin material. And a strong integral joint can be obtained.

In the present invention, the fin material is JI
Any of S1000 series aluminum alloy, 3000 series aluminum alloy, 6000 series aluminum alloy or the like can be used. The 1000th series aluminum alloy is close to pure aluminum and contains a small amount of alloy components. The 3000th aluminum alloy is an al-Mn aluminum alloy. The No. 6000 series aluminum alloy is an Al-Mg-Si series aluminum alloy. These aluminum alloys are widely and commonly used as extenders and are readily available.

In the present invention, a fin material having a thickness of 0.8 to 8 mm is provided in the cavity of the mold at a fin pitch of 4 to 8 mm.
After holding at 20 mm, it is appropriate to pour molten metal to form a base portion. This is for securing the heat exchange area by making the fin area as large as possible and ensuring the joint with the base. Further, in the present invention, the fin material,
Suitably, after holding the mold at a length of 10% to 100% of the cavity depth, the molten metal is poured to form a base portion. This is for ensuring the bonding between the fin and the base to form a strong structure.

Further, in the present invention, the molten metal can be poured into the cavity of the mold by a mold casting method or a pressure casting method, in addition to the usual sand casting method. According to the pressure casting method, mass production can be efficiently performed using a mold.

[0010]

Next, one embodiment of a method of manufacturing a heat sink according to the present invention will be described with reference to the drawings. Figure 1
FIG. 1 is an external view of a heat sink manufactured by the present invention, which is the same as a conventional heat sink. Flat fins 2 are provided at regular intervals on the surface of a base 3. A feature of the heat sink manufactured by the present invention is that the fin 2 and the base 3 of the heat sink are made of the same kind of metal, and the fin 2 is made of a rolled material and has a structure extending in the rolling direction. Is made of cast material and has an amorphous metal structure along the solidification direction. The thickness of the fin 2 is approximately 0.8 to 5 mm, and the height (h) of the fin 2 is not particularly determined. Such a fin 2 is 4 to 15 mm
Are provided in parallel at intervals of. Such a heat sink is manufactured by the following method.

(First Embodiment) FIG. 2 is a view for explaining a first embodiment of a method of manufacturing a heat sink according to the present invention by sand casting. In FIG. 2, a lower mold 5 made of a sand mold is provided in a lower mold frame 4, and a cavity 6 for injecting a molten metal serving as a base 3 of a heat sink 1 is provided in the lower mold 5.
Is provided. In the cavity 6, a fin material 2a made of, for example, a thin plate of pure aluminum is provided at one end 2a of the plate.
Are protruded into the cavity 6 and are held at regular intervals at a predetermined fin pitch. An upper mold 9 also made of a sand mold is covered on the lower mold 5, and a gate 8 is provided on the upper mold 9. Reference numeral 7 denotes an upper mold frame. The thickness of the fin material 2a is 0.8 to 8 mm, and the fin pitch is 4 to 2.
It is about 0 mm. After assembling the mold while holding the fin material 2a in the cavity 6 as shown in FIG. . The molten metal injected into the cavity 6 is a metal having a lower melting point than pure aluminum which is a fin material.
Al-Si alloys such as C are preferred. If the melting point of the molten metal is lower than the melting point of the fin material 2a, the fin 2 and the base 3 are integrally formed in a state where the fin material 2a is cast without melting. FIG. 4 shows this state. As shown in FIG. 4, the fin material 2a and the base 3 are diffusion-bonded at the bonding portion 10.

The fin material 2a is not particularly limited as long as it has good thermal conductivity, and aluminum, an aluminum alloy or copper can be used. In particular, aluminum or an aluminum alloy is preferably used because it has a high thermal conductivity and a high malleability, so that it is easy to obtain a thin plate, and it is lightweight. Pure aluminum for industrial use has a melting point of 6
At 50 ° C., the thermal conductivity is 0.225 (W / m · ° C.). As the fin material 2a, in addition to pure aluminum, JI
Any of S1000 series aluminum alloy, 3000 series aluminum alloy, 6000 series aluminum alloy or the like can be used. The 1000th aluminum alloy is close to pure aluminum and contains a trace amount of alloy components. Industrial pure aluminum is
Although it is inferior in strength to aluminum alloys, it is widely used for small heat sinks that do not require strength because it has good malleability and good workability when thinned, and has excellent corrosion resistance. The JIS No. 1000 series aluminum alloy is obtained by adding a small amount of additional elements such as Cu, Mg, Mn, and Zn in order to increase the strength.

JIS 3000 series aluminum alloy is A
l-Mn based aluminum alloy.
This is a wrought alloy to which n is added in a range of 1.5%. Mn
In addition, 1.3% or less of Mg may be added. JI
S6000 series aluminum alloy is Al-Mg-Si
This is an aluminum alloy that exhibits excellent mechanical properties by heat treatment. This alloy is very rich in toughness and is excellent in forging, extrusion and other workability. In order to increase the strength, Cr is limited to 0.35%.
The addition of is also used. These aluminum alloys are widely and generally available as extenders,
Melting point is 560 ℃ ～ 660 ℃, thermal conductivity is about 0.1
5 to 0.23 (W / m · ° C.).

The fin material 2a is a plate material of the above-described pure aluminum or aluminum alloy and has a thickness of 0.8 to 8 m.
Preferably, a square or rectangular sheet of m is used.
The fin material 2a is held in the cavity 6 of the mold at a fin pitch of 4 to 20 mm. The finer the fin pitch, the more fins 2 can be provided, but the ventilation becomes worse and the heat conduction becomes worse. Therefore, the pin pitch may be determined by appropriately combining forced ventilation means and the like. Fin material 2
a is completely cast by the molten metal 30 and the fin 2
The tip 2a 'of the fin material 2a is inserted into the cavity 6 of the mold by a length corresponding to a length of 10% to 100% of the depth of the cavity 6 so that the base 3 and the base 3 can be firmly joined. It is preferable to hold it by protruding only.

The fin material 2a is placed in the cavity 6 of the mold.
In order to hold the fins 2a at equal intervals, the fins 2a may be buried and held in a sand mold as shown in FIG. 2 or, alternatively, as shown in FIG. 2a may be supported and held using the fin support 13. This is economical because a large heat sink can be manufactured using a small sand mold.

The molten metal 30 serving as the base 3 to be poured into the cavity 6 of the sand mold may be the same kind of metal as the fin material 2a. For example, when pure aluminum or an aluminum alloy is used as the fin material 2a, the molten metal 30 is also made of an aluminum alloy. In this case, among the aluminum alloys, it is preferable to use an aluminum alloy having a melting point lower than the melting point of the fin material 2a. Then, the fin 2 and the base 3 can be firmly joined by utilizing the mutual diffusion of atoms without dissolving the fin material 2a at the time of pouring. As the aluminum alloy having a lower melting point than the fin material 2a, an Al-Si casting alloy is preferable. For example, JIS
AC4C alloy is Al-S containing 6.5% to 7.5% of Si.
An i-type casting alloy having a melting point of about 590 ° C. and a good flow of molten metal.
In addition, alloys for Al-Si casting containing 4 to 13% of Si, and alloys for die casting can be used. The casting temperature is preferably about 1 to 20 ° C. higher than the melting point.

(Second Embodiment) The first embodiment shows a method of forming a base portion by casting using a sand mold, but the sand casting method is used when a relatively large heat sink is manufactured. . If the heat sink is small, it can also be manufactured by die casting. As a second embodiment, a method for manufacturing the heat sink of the present invention by die casting is shown in FIG. FIG. 5 is a view for explaining a second embodiment of the method for manufacturing a heat sink according to the present invention by die casting. In the figure, reference numeral 15 denotes a lower mold, and reference numeral 17 denotes a lower mold.
Is an upper mold. As in the first embodiment, the lower mold 15 is provided with a cavity 16 for injecting the molten metal 30 for the base 3. In the same manner as in the first embodiment, the fin material 2a penetrates through the lower mold 15 in the cavity 16, and the tip 2
a 'is projected and held. The fin material 2 a is held by the fin support 23 outside the lower mold 15.
The molten metal 30 is poured into the cavity 16 from the gate 18. The fin material 2a and the molten metal 30 used are the same as those in the first embodiment. When the molten metal 30 is solidified by cooling, the fin 2 and the base 3 are joined together as shown in FIG.
Is obtained.

As means for supporting the fin material 2a, FIG.
As shown in (1), a method in which the tip 2a 'of the fin material 2a is processed into a T-shape and inserted into the slit 15a of the lower mold 15 to support it. In this way, no special support is needed.

When the high-temperature molten metal 30 is poured into the mold, the upper mold 17 is gradually deformed by heat. In order to prevent this deformation, as shown in FIG.
It is an effective means to place the upper mold 17 or press and hold the upper mold 17.

(Third Embodiment) Next, as a third embodiment, a method of manufacturing a heat sink of the present invention by a pressure casting method using a mold will be described with reference to FIGS. . The fin material 2a and the molten metal 30 used are the same as those in the first embodiment. As shown in FIG.
A plurality of fin materials 2a of 8 to 5 mm are held in parallel by a lower mold (movable mold) 25 while maintaining a predetermined fin pitch. In that case, the tip 2a 'of each fin material 2a is held so as to protrude into the cavity 26 by a length of 10 to 100% of the depth of the cavity 26 of the mold. On the other hand, the upper surface of the cavity 26 provided in the upper mold (fixed mold) 27 is processed into a flat surface. In addition, the upper mold 27 is provided with a gate 28 and a pressure punch 31 for pressing a molten metal 30, which is a material of the base 3 in the cavity 26, from above to below in the direction of the arrow. Have been. Then, as shown in FIG. 9, the pressure punch 31 is moved downward from the state of FIG.
Pressure is applied to the molten metal 30 in the cavity 26. As a result, the molten metal 30 is completely filled in the narrow gap between the fin members 2a held in parallel,
Each tip 2a 'of a is to be cast by the molten metal 30.

When each tip 2a 'of the fin material 2a is wrapped in the molten metal 30, the melting point of the fin material 2a is higher than the melting point of the metal serving as the base 3, so that the fin material 2a
Are joined together with the solidification of the molten metal 30 without melting. At this time, the fin material 2a and the molten metal 30
Are the same kind of metal, the atoms mutually interdiffuse on the surface, and the fin 2 and the base 3 are easily joined together.

In order to strengthen the joint between the fin material 2a and the base 3, the shape of the tip 2a 'of the fin material 2a cast by the molten metal 30 is changed as shown in FIGS.
(D) is also effective. (A) of FIG.
Fig. 10 (b) shows the tip 2a 'of the fin material 2a bent at 90 degrees in an L-shape, and Fig. 10 (b) shows the tip 2a' bent at less than 90 degrees. 2
It can be obtained by bending the tip 2a 'of a with a press machine. FIG. 10 (c) shows the tip 2a 'forged into a T-shape, and FIG. 10 (d) shows the tip 2a' provided with a depression 2b, all of which can be obtained by simple forging. .

[0023]

As is apparent from the above description, according to the present invention, one end of the plate-shaped fin body is projected and held in the cavity of the mold, and thereafter has a melting point higher than that of the fin material. By pouring molten metal of the same kind as the low fin material into the cavity of the mold, the fin and the base are integrally formed without melting the fin body, so that a large heat exchange area is secured. It is possible to realize a strong joint between the fin and the base.
Moreover, since the fin and the base are made of the same kind of metal, there is almost no potential difference, and a heat sink having excellent corrosion resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing the appearance of a heat sink.

FIG. 2 is a diagram illustrating a method for manufacturing a heat sink according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating another example of the method of manufacturing the heat sink according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating the structure of a heat sink obtained by the present invention.

FIG. 5 is a diagram illustrating a method for manufacturing a heat sink according to a second embodiment of the present invention.

FIG. 6 is a view illustrating another example of the method of manufacturing the heat sink according to the second embodiment of the present invention.

FIG. 7 is a view illustrating still another example of the method of manufacturing the heat sink according to the second embodiment of the present invention.

FIG. 8 is a diagram illustrating an example of a method for manufacturing a heat sink according to a third embodiment of the present invention.

FIG. 9 is a diagram illustrating an example of a method for manufacturing a heat sink according to the third embodiment of the present invention, following FIG.

FIG. 10 is a view for explaining the shape of a tip of a fin material used in the present invention.

[Explanation of symbols]

1, heat sink, 2 fin, 3 base, 4 lower mold, 5 lower mold, 6, 16, 26・ ・
・ Cavity, 7 ・ ・ ・ ・ ・ ・ ・ Upper mold, 8, 18, 28 ・ ・ ・ ・ ・
Gate, 9 ····· Upper die, 10 ····· Joint, 13, 23 ···
・ Fin support, 15, 25 ... Lower mold, 17, 27 ...
... upper mold, 28 ... weight, 30 ... molten metal, 31
.... Pressure punch, 32 ... Piston

Claims (7)

[Claims] 1. A fin material of a plate-like metal is held at a predetermined interval in a cavity of a mold, a molten metal of the same kind as the fin material is poured into the cavity, and a base is formed at an end of the fin material. A method for manufacturing a heat sink. 2. The method according to claim 1, wherein the melting point of the molten metal poured into the cavity is lower than the melting point of the fin material metal. 3. The fin material is made of pure aluminum, and the molten metal poured into the cavity is Al-Si.
3. The method according to claim 1, wherein the alloy is made of an alloy.
3. The method for manufacturing a heat sink according to claim 1. 4. The fin material is a No. 1000 series aluminum alloy, a No. 3000 series aluminum alloy or 600
The method for manufacturing a heat sink according to any one of claims 1 to 3, wherein the heat sink is made of any one of a No. 0 series aluminum alloy. 5. The method for manufacturing a heat sink according to claim 1, wherein a fin material having a thickness of 0.8 to 5 mm is held at a fin pitch of 4 to 15 mm in the cavity of the mold. 6. The method according to claim 1, wherein the fin material is maintained at a length of 10% to 100% of a depth of a cavity of the mold. 7. The method for manufacturing a heat sink according to claim 5, wherein the molten metal is poured into the cavity of the mold by a pressure casting method.