A novel combined extrusion process of thin-walled tubular part with protrusion

Manufacturing of thin-walled components with protrusions holds importance for the advancement of extrusion technology, expanding the application scope of extrusion processes and achieving lightweight equipment. To accomplish these objectives, a novel two-step combined extrusion process is proposed, drawing on numerous research achievements and theories in flange forming. Detailed analysis of metal flow characteristics during extrusion is conducted using finite element simulation, and the strain heterogeneity index is introduced to quantitatively evaluate the influence of different process parameters and die cavity dimensions on the forming results. The results indicate that the forming quality of the protrusions depends on lower extrusion speeds, appropriate friction coefficients, and rounded die inlet corners. Furthermore, the generation mechanism of defects during the forming process is investigated through the analysis of billet and die cavity dimensions, leading to the establishment of a 3D forming limit diagram. Finally, multiple sets of physical experiments are designed and conducted to validate the feasibility of the forming process and simulation results.