Design of Rotary Extrusion Process Using Simulation Techniques to Save Raw Material in Hollow Components

The forging process plays an important role in the automotive industry thanks to the good mechanical properties of the forged parts. Nowadays, due to the European policy of increasing efficiency in raw material and energy usage, the metal forming sector is demanding new innovative technologies. In this context, rotary extrusion technology is a very promising metal forming alternative to the drilling techniques after forging processes. The presented work is focused on hollow shafts that are usually manufactured using a combination of forming and metal cutting techniques. Deep drilling is the most common technique to obtain internal holes in the automotive hollow parts, but it is an expensive process in terms of material usage. In this framework, rotary extrusion appears as an alternative technology that leads to the reduction of material usage and process time. The tubular shape is formed with the combination of two forming processes: flow forming and backward extrusion. This paper presents the development of a simulation methodology, the process design for a hollow part, the specifications of the experimental unit, and the manufactured prototypes in order to validate the simulation model. Also the incremental process is improved thanks to a sensitivity study of the rollers geometry. Rotary extrusion experiments are done using a modified flow forming machine and 20% material saving is achieved when obtaining the deep hole in comparison to the current deep drilling technology. The process design and numerical model tasks carried out try to provide the industry manufacturers an alternative technology to drilled parts considering the advantages of rotary extrusion parts.