Research on the forming forces during the 3D non-axisymmetric thin-walled tubes neck-spinning

3D non-axisymmetric thin-walled tubes can be divided into two categories, the offset and the oblique. The theoretical calculation formulas of the spinning forces for the 3D non-axisymmetric thin-walled tubes based on the Slab Method are presented. The effects of the rotational angle γ of roller, the offset amount δ of blank per path and the position S of roller revolution plane on the spinning force are analyzed theoretically. It shows that during the 3D non-axisymmetric thin-walled tubes spinning, the spinning forces vary periodically with γ, the variation period is one revolution of roller around workpiece. The maximum and minimum spinning forces occur at the position corresponding to the instantaneous maximum and minimum reductions. The effects of main forming parameters, such as offset amount δ and oblique angle α of blank per path on maximum spinning forces are analyzed experimentally and theoretically. The calculation results conform well to the experiment one. The error is less than 20%. It indicates that the spinning forces for 3D non-axisymmetric thin-walled tubes can be obtained by the slab method.