Sensitivity of Forming Process to Selection of Variable Restraining Force Trajectory

Robust operating window and subsequent quality of part are major concerns during sheet metal stamping. For a given part geometry, material, and lubrication conditions, the sheet restraining force is the key parameter controlling metal flow, thus influencing formability and quality of the resulting part. Recent advances in press and die building provide capability of the restraining force (RF) variation during a stamping stroke. In this study, a laboratory and numerical experiments were performed in an effort to better understand the effect of various VRF trajectories on stamping performance. The working numerical model using explicit LS-Dyna 3D code was successfully developed for time effective simulation of complex parts with variable binder force. Several trajectories are proposed and tested, showing strong nonlinear influence. This indicates the need for predictive approaches capable of establishing robust and optimal trajectories for individual complex industrial stamping designs.