| 摘要 |
A piston is formed in two parts. The main part is formed by gravity die casting from aluminum or aluminum alloy and a second part of the piston is formed by a squeeze casting process to produce a material which is stronger and more resistant than the gravity die cast aluminum or aluminum alloy. At least one piston ring groove is formed in the second part. The two parts are then electron beam welded together to form the complete piston. The squeeze cast portion may be reinforced with whiskers or fibres to further improve its properties. This method of construction has the benefit that only the minimum amount of the piston is formed by the more expensive and time-consuming squeeze casting process so that parts of the piston which do not require the improved properties given by squeeze casting are simply gravity die cast. This is of particular benefit in large diesel pistons. |
