GEGOSSENER ALUMINIUMKOLBEN FUER VERBRENNUNGSMOTOREN MIT OBERFLAECHLICH MECHANISCH VERDICHTETEN NABENBOHRUNGEN.

摘要

The hub bore on an Al piston is hardened by producing a fibre structure circumferencially around the bore to a depth of at least 0.1mn, pref. 0.2mm. A hub bore is produced of diameter less than the final diameter by drilling. The piston is then rolled at at least 350 deg.C. (pref. over 400 deg.C.) to widen the bore by 0.2-0.5mm. After rolling, the final diameter is produced by removing metal in the deformed area. This also ensures uniform dimensions of the bore cross-section.