IC engine ferrous piston ring flank hardening - is carried out in two stages separated by tool cutting operation for distortion correction

摘要

Pistons consist of several parts and are made of ferrous material hardened by local heat treatment, pref. by an electron beam method, along the flanks of the annular piston ring grooves. The flanks are subdivided into a radially inner part and an outer (much smaller) part which are heat-treated separately. Any distortion caused by the hardening of the radially inner part of the flanks can now be rectified by a metal-cutting tool. The subsequent hardening of the narrow (under 1mm.) outer flank part does not cause any distortion. This saves the expensive copy grinding which is needed if the flanks are hardened in one operation.