Enhancement of forming accuracy in bionic egg-shaped thin-walled components under multi-parameter coupling effects

Abstract

To address the challenges of process complexity and precision control in forming bionic egg-shaped head with small thickness-to-diameter ratio, this study proposes a synergistic forming strategy integrating punch speed regulation and interfacial lubrication optimization. Through precise regulation of punch speed gradient distribution and establishment of a multi-scale lubrication system, this approach significantly enhances sheet metal plasticity and forming accuracy. By integrating structural feature characterization with mechanistic investigation of forming defects, this study systematically uncovers the root causes of insufficient mold conformity during the forming process of egg-shaped tip head. Through an integrated numerical-experimental verification framework, this study elucidates the coupling effects of critical process parameters on forming accuracy under thick-directional loading conditions. The experimental results demonstrate that adopting grease with a 20 Hz punch speed achieves a maximum mold conformity gap of merely 0.37 mm in the egg-shaped tip head, which improved the forming accuracy by 63% compared to the worst formed parts, while exhibiting optimal gap distribution uniformity. The strong consistency between numerical simulation results and experimental data validates the reliability of the proposed process solution, providing an innovative approach for precision forming of complex components in deep-sea pressure hull applications.