Method of manufacture of a piston for an internal combustion engine, and piston thus obtained

• US 7,472,674 B2
• Filed: 12/04/2003
• Issued: 01/06/2009
• Est. Priority Date: 12/05/2002
• Status: Expired due to Fees

• Current Assignee: ASCO Industries
• Original Assignee: Ascometal (Ascométal SA /Private Group/)
• Inventors: Robelet, Marc
• Primary Examiner(s): MCMAHON, MARGUERITE J
• Application Number:
  US10/726,651
• Publication Number:
  US 20040129243A1
• Time in Patent Office: 1,860 Days
• Field of Search: 123/193.6, 164/900, 148/500, 723/64, 723/77, 723/59, 298/880.4
• US Class Current: 123/193.6
• CPC Class Codes: B21J 5/00 Methods for forging, hammering, or pressing for working sheet-metal or metal tubes, rods, or profiles B21D; for working wire B21F; Special equipment or accessories therefor
• CPC Class Codes: B21J 5/004 Thixotropic process, i.e. forging at semi-solid state
• CPC Class Codes: B21K 1/18 pistons or plungers
• CPC Class Codes: Y10S 164/90 Rheo-casting
• CPC Class Codes: Y10T 29/49249 Piston making

Abstract

A piston for an internal combustion engine is formed from a metal part cast in one piece. Heating of a billet is carried out so as to bring it to an intermediate temperature between its solidus temperature and its liquidus temperature, and shaping thereof by thixoforging is carried out.

Claims

1. Method of manufacture of a piston for an internal combustion engine, the said piston being formed from a steel part cast in one piece, wherein heating of a billet is carried out so as to bring it to an intermediate temperature between its solidus temperature and its liquidus temperature, and that shaping thereof by thixoforging is carried out, wherein the steel piston has a composition, in percentages by weight, of:

0.35%≦

C≦

1.2%

0.10%≦

Mn≦

2.00%

0.10%≦

Is≦

1.0%

traces≦

Cr≦

4.5%

traces≦

Mo≦

2.0%

traces≦

Ni≦

4.5%

traces≦

V≦

0.5%

traces≦

Cu≦

3.5%

traces≦

Al≦

0.060%

traces≦

Ca≦

0.050%

traces≦

B≦

100 ppm

traces≦

Ti≦

0.050%

traces≦

Nb≦

0.050%

the other elements being iron and conventional impurities resulting from the manufacture.

2. The method of claim 1, wherein the steel piston includes up to 0.180% of S and one at least of the elements chosen from amongst up to 0.080% of Bi, up to 0.020% of Te, up to 0.040% of Se, up to 0.070% of Pb.