An investigation of mandrel-free spinning

Spinning is a sheet metal forming technique conventionally used to form axisymmetric shapes. Recently a flexible mandrel-free spinning process was successfully used to form non-axisymmetric geometries. In this mandrel-free spinning process, numerically controlled rollers are used instead of a mandrel, allowing for savings in the lead-time, cost and the material required for mandrel. The deformation behavior of this process has not been previously analyzed numerically, although it is critical to designing toolpaths and achieving successful parts. In this work, an FEA model is constructed and is used to study the stress distribution and the strain path. Validation of the numerical model is carried out by comparing forces with measureable experimental results. The model shows that the stress distribution while forming is different to that observed in the conventional spinning while the wrinkling mechanism is similar to that observed in conventional spinning.