Classified induction quenching method and device for core rod

The invention discloses a staged induction quenching method and device for a core rod. The staged induction quenching method comprises the following steps: sequentially arranging n stages of induction heating current loops on a conveying roller way along the conveying direction of the core rod; the induction heating frequencies f of the n stages of induction heating current loops are increased stage by stage in the conveying direction of the core rod; the power P of the n stages of induction heating current loops is gradually reduced along the conveying direction of the core rod; and the heating temperature rise delta T of the n stages of induction heating current loops is gradually reduced along the conveying direction of the core rod. According to the invention, the core rod can conveniently select all or part of induction heating on line according to the diameter change of the core rod, so that the optimal quenching depth target can be accurately realized, the matching relationship between the surface wear