Simulation and Experimental Study on Improving Wall Thickness Uniformity for Incremental Forming of Ellipsoidal Parts Using Equal Arc Length Helical Toolpaths

Incremental forming has great potential for flexible manufacturing of thin-walled parts. However, for ellipsoidal parts with varying curvatures, conventional constant layer spacing toolpaths easily cause local dents, excessive thinning and other defects. Existing helical toolpaths are designed for flat blanks and are poorly adaptable to curved blanks. An equal arc length spiral toolpath model for ellipsoidal parts was established, and simulations and experiments on flat and curved blanks were conducted to analyze wall thickness distribution and material flow behaviors. Results show that compared with two conventional toolpaths, the proposed toolpath achieves more balanced plastic flow, increasing the minimum wall thickness by 11.37% and reducing the maximum equivalent plastic strain by 7.03%, effectively alleviating forming defects at the ellipsoid bottom. This study verifies that the proposed toolpath and its composite forms adapt well to curved blanks, providing references for toolpath design of complex varying curvature parts.