Development of Cam Ring Gear Parts of Large Diameter for Truck Clutch Using Hot–Cold Complex Forging Technology of Small Bar

Hot forging is a processing of plastic deformation for the metal at recrystallization temperature or higher. It is possible to decrease the flow stress and energy required to form the material at elevated temperature. But cold forging can improve mechanical properties, excellent dimensional accuracy, and surface quality. Main advantage of hot–cold complex forging is that it is able of large deformation with less force, and improved mechanical properties and dimensional accuracy. In general, complex forging for combining cold forging and hot forging of small bar can improve the shape accuracy of forged parts. In this study, the material loss and the production time were high in the conventional cutting process, but cam ring gear parts of large diameter for truck clutch were developed by applying the hot–cold forging technology. The complex forging technology of cam ring gear parts would be very useful to improve dimensional accuracy, reduce manufacturing cost, and increase die life.