Producing piston rings - with the TOP side marked after production of the asymmetric running face

摘要

Piston rings are finish worked by having the top, bottom and inner dies (2,3,4) following by producing an asymmetric ball shaped running surface (8) with the point (8) of highest curvature slightly off centre and towards one of the sides (2,3). The rings are then sorted so that the point (8) is more than half the height (h) below the top side (2) which can then be marked as TOP. ADVANTAGE - The reject rate is considerably reduced by marking the TOP side after producing the asymmetric running surface as compared with the prior art when the TOP side is marked prior to production of the running surface.