JP2001200327A - High capacity aluminum alloy for piston and method for producing piston - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy excellent in thermal conductivity while maintaining the various characteristics of the conventional aluminum alloy. SOLUTION: This aluminum alloy has a composition composed of, by weight, 9.0 to 15.0% Si, 0.5 to 1.1% Cu, 0.5 to 1.5% Mg, 0.5 to 1.5% Ni, 0.01 to 0.05% Ti, <=0.3% Mn, and the balance Al.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy suitable as a piston material used at a high temperature and a method for manufacturing a piston using the same.

[0002]

2. Description of the Related Art Conventionally, aluminum alloys such as JISAC8A, AC8B, and AC8C have been mainly used as materials for pistons for internal combustion engines. In recent years, the development of internal combustion engines has been to increase the combustion temperature, improve the combustion efficiency, achieve high fuel efficiency and high output, and the functions required of aluminum alloys as piston materials have become severe.

[0003]

At present, development of an engine with high combustion efficiency and high fuel efficiency and high output is progressing. As a result, engine parts have been used at higher temperatures than ever, and JIS-aluminum alloys cannot be used. That is, the conventional aluminum alloy has problems in heat resistance, high strength, dimensional change during hot operation, and the like, and cannot cope with current energy saving and high performance of internal combustion engines.

An object of the present invention is to provide a piston aluminum alloy having excellent thermal conductivity while maintaining various characteristics of a conventional piston aluminum alloy, and a method of manufacturing a piston using the same. Things.

[0005]

In order to achieve the above object, the present invention employs an aluminum alloy having the following composition. That is, Si 9.0-15.0 wt%, Cu 0.5
To 1.1 wt%, Mg 0.5 to 1.5 wt%, Ni0.
5 to 1.5 wt%, Ti 0.01 to 0.05 wt%, M
This is an aluminum alloy for high-performance pistons with n being 0.3 wt% or less and the balance being Al.

As a method of manufacturing a piston, Si is used.
9.0-15.0 wt%, Cu 0.5-1.1 wt%,
Mg 0.5-1.5wt%, Ni 0.5-1.5wt
%, Ti 0.01-0.05 wt%, Mn 0.3 wt%
Hereinafter, a piston is formed by casting an aluminum alloy having a balance of Al by a melt forging method and performing heat treatment and machining.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The reasons for limiting the composition of each component of the aluminum alloy according to the present invention will be described below for the understanding of the present invention. Si is a chemical component necessary for improving wear resistance and strength, but its content is 9.0 wt%.
If less, sufficient wear resistance and strength cannot be obtained,
On the other hand, if the content exceeds 15.0 wt%, the amount of hard primary crystal Si crystallized out becomes excessive, and there arises a problem that toughness, impact resistance and machinability deteriorate. Therefore, the content of Si is set in the range of 9.0 to 15.0 wt%.

[0008] Cu is a chemical component that contributes to solid solution hardening and aging precipitation hardening, and its content is 0.5 wt%.
If it is less than 1, sufficient high-temperature strength cannot be obtained. On the other hand, if the content exceeds 1.1 wt%, the thermal conductivity is significantly reduced. Therefore, the Cu content is in the range of 0.5 to 1.1 wt%. .

[0009] Mg is a chemical component that contributes to age hardening in an Al-Si alloy, but its content is 0.5%.
If the amount is less than 1.5% by weight, the strength and hardness are slowly improved, and sufficient age hardening cannot be obtained. There is a problem. Therefore, the content of Mg is 0.5
To 1.5 wt%.

[0010] Ni is a chemical component contributing to the improvement of high-temperature strength. However, if its content is less than 0.5 wt%, sufficient high-temperature strength cannot be obtained.
If the content exceeds t%, the crystallization of NiAl ₃ (Y compound) increases, and there is a problem that the thermal fatigue characteristics deteriorate. Therefore, N
The content of i is in the range of 0.5 to 1.5 wt%.

[0011] Ti is a chemical component necessary for refining macro crystal grains and improving tensile strength. If the content is less than 0.01 wt%, the effect of refining crystal grains is small. If the content exceeds 0.05% by weight, there is a problem that the thermal conductivity decreases and the effect of improving the tensile strength decreases. Therefore, the content of Ti is 0.01 to
The range is 0.05 wt%.

Mn is a chemical component required to combine with Fe in the impurities to form granules and reduce a decrease in toughness and abrasion resistance. If its content exceeds 0.3 wt%, Mn is Fe. -There is a problem that the crystallization amount of the Mn compound increases, and conversely, the toughness decreases. Therefore, the content of Mn is 0.3w
t% or less. In addition, Fe, which is a chemical component in the impurities,
Is crystallized as an acicular Al-Si-Fe intermetallic compound,
Since the toughness and impact resistance are reduced, the Fe content needs to be 0.3 wt% or less.

[0013]

The present invention will be described below with reference to examples and comparative examples. (Example 1) Aluminum alloys shown in Table 1 below were melted and cast materials were cast using a boat shape. After subjecting those castings to a solution treatment at 510 ° C. for 4 hours, they were cooled with water,
Next, an artificial aging treatment was performed at 170 ° C. for 10 hours.
Then, a test piece was cut out from the casting material, and the hardness, strength, and thermal conductivity were measured at room temperature. The results are shown in Table 1.

[0014]

[Table 1]

From Table 1 above, No. 1, No. It can be seen that both Samples 2 show the same hardness, strength and heat conductivity. No.
1 is a commonly used piston material, and
o. Evaluate based on 1.

Example 2 The hardness, strength and thermal conductivity of the aluminum alloys shown in Table 2 below were measured in the same manner as in Example 1, and the results are also shown in Table 2.

[0017]

[Table 2]

No. No. 3 is a reference alloy No. No. 1 was made 0.00% by weight of the Cu component. It can be seen that the thermal conductivity is higher than that of No. 1, but the hardness and strength are inferior. No. 4 is No. 4. It can be seen that although the Fe component value of No. 3 was increased to 1.2 wt%, the strength and the thermal conductivity were significantly reduced. No. No. 5 is No. It can be seen that although the Cu component value of No. 4 was increased to 0.5 wt%, the hardness and strength were increased.

Example 3 The hardness, strength and thermal conductivity of the aluminum alloys shown in Table 3 below were measured in the same manner as in Example 1, and the results are also shown in Table 3.

[0020]

[Table 3]

No. 6, No. 7, No. No. 8 is the reference alloy No. irrespective of the Ni component value. The thermal conductivity is significantly improved as compared with No. 1. The hardness and the strength are almost the same.

Example 4 The hardness and thermal conductivity of the aluminum alloys shown in Table 4 below were measured in the same manner as in Example 1, and the results are also shown in Table 4.

[0023]

[Table 4]

No. 9, No. 10, No. Comparing No. 11, No. 11 having the smallest Ti component value 9 has high thermal conductivity. The hardness of these three types of test pieces is almost the same.

Example 5 The hardness and thermal conductivity of the aluminum alloys shown in Table 5 below were measured in the same manner as in Example 1, and the results are also shown in Table 5.

[0026]

[Table 5]

Even when the amount of Si is about 14 wt%, N
o. 12, No. Comparing No. 13 with No. 13 having a small Ti component value It can be seen that 12 has higher thermal conductivity and the same hardness.

Example 6 The hardness and thermal conductivity of the aluminum alloys shown in Table 6 below were measured in the same manner as in Example 1, and the results are also shown in Table 6.

[0029]

[Table 6]

No. 14, No. 15 and reference alloy N
o. Although the hardness is high due to the large amount of Cu compared to No. 1,
It can be seen that the thermal conductivity is low.

(Embodiment 7)
No. 1 (reference), No. 9, No. Table 7 below shows the relationship between the Ti component value and the thermal conductivity from the data of No. 11.

[0032]

[Table 7]

FIG. 1 is a graph showing the relationship between the Ti content and the thermal conductivity. As can be seen from this graph, the thermal conductivity decreases as the content of the Ti component value increases. You can see that it is.

(Embodiment 8) Using the aluminum alloy of the present invention (alloy No. 8), an output test was performed using a piston obtained by a melt forging method (the test condition was a diameter of 6).
It was carried out with a 1-cylinder, 2-cycle engine with a 0 mm piston). The results are shown in the graph of FIG. 3. As can be seen from FIG. 3, an improvement in the output of 1 PS was recognized.

Next, a description will be given of a melt forging method in a method of manufacturing a piston using an aluminum alloy according to the present invention. That is, first, as shown in FIG.
The molten aluminum 5 held at 700 to 750 ° C. is poured into the mold composed of the lower mold 3, the side mold 2, and the upper mold 1, which has been preheated by the pouring ladle 4. Next, the upper mold 1 is lowered at a lowering speed of 5.0 to 10.0 cm / s, and pressurized at a casting pressure of 600 to 1000 kgf / cm ² . Next, after the solidification is completed, the mold is opened and the piston material is taken out. In order to further increase the strength, the piston material thus manufactured is subjected to a heat treatment, and then machined into a final shape of the piston. After that, if necessary, in order to improve the sliding characteristics and abrasion resistance of the piston main body, the side surfaces of the skirt portion and the inner surfaces of the pin holes are subjected to a surface treatment such as plating and anodizing.

Crystallizes in piston obtained by gravity casting
The size of Si is 100 μm or more when a hypereutectic aluminum alloy is used. For this reason, a molten aluminum treatment is usually performed by adding P to reduce the size of primary crystal Si. However, in the present invention, since the casting is performed at a high pressure by die casting, the solidification speed of the molten aluminum is 30 to 60 ° C. /
s, and the size of the crystallized Si is fine and uniformly dispersed as 50 μm or less. Therefore, it is not necessary to perform a molten aluminum treatment by adding P, mechanical properties such as wear resistance, elongation, and strength are improved as a piston material, and tool life can be significantly improved.

[0037]

As described above, according to the aluminum alloy of the present invention, the thermal conductivity is high and the mechanical properties such as abrasion resistance, elongation and strength are improved. By using such an aluminum alloy to form a piston by molten metal forging, the piston can withstand high temperatures even under severer combustion conditions, and can be made thinner and lighter without causing erosion, etc. This has the effect that improvement can be achieved.

[Brief description of the drawings]

FIG. 1 is a graph comparing the Ti component value and the thermal conductivity of an aluminum alloy of the present invention and a conventional aluminum alloy.

FIG. 2 is a schematic view illustrating a method for manufacturing a piston by a melt forging method.

FIG. 3 is a graph comparing the engine output of a piston obtained by a molten metal forging method using an aluminum alloy of the present invention and a conventional aluminum alloy.

[Explanation of symbols]

 1: Upper mold 2: Side mold 3: Lower mold 4: Pouring ladle 5: Aluminum melt

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiro Takahashi 300, Takatsukacho, Hamamatsu-shi, Shizuoka Suzuki Co., Ltd. (72) Inventor Fumitaka 300, Takatsukacho, Hamamatsu-shi, Shizuoka Suzuki Co., Ltd. (72) Inventor Shogo Komura 300, Takatsuka-cho, Hamamatsu-shi, Shizuoka Suzuki Co., Ltd. BC01 CA21 DA09 EA01

Claims (2)

[Claims] The present invention relates to: 9.0-15.0% by weight of Si;
5 to 1.1 wt%, Mg 0.5 to 1.5 wt%, Ni
0.5-1.5wt%, Ti0.01-0.05wt
%, An Mn of 0.3 wt% or less and a balance of Al. 2. The composition according to claim 1, wherein the content of Si is 9.0 to 15.0% by weight,
5 to 1.1 wt%, Mg 0.5 to 1.5 wt%, Ni
0.5-1.5wt%, Ti0.01-0.05wt
%. An aluminum alloy having a composition of 0.3% by weight or less and Mn of 0.3% by weight or less, with the balance being Al, is cast by a melt forging method, and is subjected to heat treatment and machining to form a piston.