When performing scanning hardening on large rings, traditional methods (fixed-area hardening) cause seams between the start and end points of the process. DKK has achieved seamless hardening by simultaneously using two coils to perform scanning hardening in opposite directions. Moving the two coils closer to each other at the start and end of the hardening process makes it possible to eliminate gaps in the hardened layer.
(Patent Nos. 5903455, 6146916, 6403960, 6671830)