Process for manufacturing a light alloy piston having an annular cooling passage in its head portion

Abstract

A light alloy piston having an annular cooling passage in its head portion is prepared by a process wherein a permanent mold, preferably having a steel shell and a water cooled bottom, is filled with the molten piston alloy. Thereafter, core elements, particularly a salt core for forming the cooling passage are introduced into the molten material by means of a holder and the permanent mold is held at an elevated temperature by external heating. The permanent mold is then lowered into a water bath for a given period of time. The soluble core, which has a specific gravity lower than that of the molten light alloy, is forced into the molten material to the desired position and depth using a holding device. The holding device is withdrawn from the remaining molten material when the solidification of the molten material has proceeded to the underside of the core. Preferably, the holding device is withdrawn during the lowering of the permanent mold into the water bath when the water level has reached the top level of the core.

Dependencies are inferred from the claim text.