The key technology of crankshaft heat treatment is surface strengthening treatment. Nodular cast iron crankshafts are generally normalized to prepare the organization for surface treatment, and surface strengthening is generally treated by induction hardening or nitriding. The forged steel crankshaft adopts the journal and rounded quenching process. The imported equipments are AEG automatic crankshaft quenching machine, EMA quenching machine and so on.
According to foreign information, the composite strengthening of nodular cast iron crankshaft by the combination of rounded rolling process and ion nitriding can increase the fatigue strength of the whole crankshaft by more than 130%. Some domestic manufacturers have also carried out this practice in recent years, and achieved good results.
Crankshaft corner rolling processing, Germany HEGENSCHEIDT-MFD AUTOMATIC machine tools produced by the application of variable pressure rolling and correction patented technology, is a better corner rolling equipment, but the price is expensive. At present, the domestic research in this area has also had some results, Dongfeng Motor Co., LTD. Technology research institute "crankshaft corner rolling strengthening and rolling straightening technology research and development and application" to solve the problem of domestic enterprises to introduce foreign technology with huge amounts of money, the subject won the former State Bureau of Machinery Industry science and Technology progress award.