Effect of size of the cylindrical workpiece on the cold rotary-forging process

Cold rotary forging is an advanced but much complex incremental metal forming process with multi-factors coupling interactive effects. The size of the workpiece has a significant effect on the cold rotary-forging process. In the current work, a reliable 3D elastic–plastic dynamic explicit FE model of cold rotary forging of a cylindrical workpiece is established under the ABAQUS software environment. Based on the valid 3D FE model, the effect laws of size of the cylindrical workpiece on metal flow, degree of inhomogeneous deformation of workpiece and force and power parameters in the cold rotary-forging process have been investigated. The research results show the following: (1) With increasing the initial diameter of the cylindrical workpiece D0, the “mushroom” effect of the deformed cylindrical workpiece becomes less obvious and the deformation becomes more homogeneous, while the maximum axial forging force and forging moment gradually increase. (2) With increasing the initial height of the cylindrical workpiece H0, the “mushroom” effect of the deformed cylindrical workpiece becomes more obvious and the deformation becomes more inhomogeneous. Meanwhile, the maximum axial forging force and forging moment increase slowly. (3) The effect of the height to diameter ratio H0/D0 by changing D0 on the cold rotary-forging process is different from that by changing H0. The above results have been explained by the critical parameter affecting the cold rotary-forging process significantly, namely the length to height ratio of the plastic deformation zone K¯ .