US 7,069,897 B2 · Forged piston for internal combustion engine and manufacturing method thereof

Abstract

A forged piston for an internal combustion engine formed from an aluminum alloy containing silicon in an amount of 6 to 25 mass %, includes an oil ring groove section (12) and a skirt section (13). The ratio (A/B) of the average size (A) of eutectic silicon grains contained in the oil ring groove section to the average size (B) of eutectic silicon grains contained in the frontal end portion (18) of the skirt section is at least 1.5. The average size (A) is at least 4 μm. With the configuration such that the average size (B) is small and that the average size (A) is large, the skirt section exhibits excellent forgeability and the oil ring groove section exhibits reliable mechanical workability and improved wear resistance.

Claims8

Dependent claims

A forged piston for an internal combustion engine formed from an aluminum alloy containing silicon in an amount of 6 to 25 mass %, the piston comprising an oil ring groove section and a skirt section, wherein a ratio (A/B) of an average size (A) of eutectic silicon grains contained in the oil ring groove section to an average size (B) of eutectic silicon grains contained in a frontal end portion of the skirt section, is at least 1.5, and the average size (A) is at least 4 μm.

A method for manufacturing a forged piston for an internal combustion engine, comprising the steps of:

subjecting to unidirectional solidification casting molten aluminum alloy containing silicon in an amount of 6 to 25 mass % to thereby produce a cast ingot which serves as a forging material having a first surface and a second surface which are opposed to each other, an average size of silicon grains contained in the first surface differing from that of silicon grains contained in the second surface;
subjecting the forging material to preliminary heating;
placing the forging material in a forging die, with the surface containing silicon grains of larger average size facing a surface of the die that corresponds to a piston head, to thereby forge the forging material into a piston preform;
subjecting the piston preform to intentional aging treatment;
and
subjecting the resultant piston preform to mechanical working to thereby manufacture a forged piston for an internal combustion engine.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application

10/484,503Filed 23 Jul 2002 · us provisional application

Priority

JP 2001-22100523 Jul 2001

Published

US 2004/0261615 A130 Dec 2004

Granted

4 Jul 2006

Term ends

Not estimatedThe source records don’t support an estimate.

Classification15 codes

C22F 1/043
Of aluminium or alloys based thereon: of alloys with silicon as the next major constituent
B21K 1/18
Making machine elements: pistons or plungers
B22D 27/045
Influencing the temperature of the metal, e.g. by heating or cooling the mould: directionally solidified castings
C22C 21/02
Alloys based on aluminium: with silicon as the next major constituent

Forged piston for internal combustion engine and manufacturing method thereof

Life of this patent

Forged piston for internal combustion engine and manufacturing method thereof

Life of this patent

Abstract

Claims8