On-line autonomous path optimization for multi-pass incremental forming using model predictive control.

Model predictive control (MPC) is an advanced control algorithm that has been successfully implemented in the on-line path optimization of computer-numerical-control (CNC) machines for performing single-pass incremental sheet forming (ISF) processes, aiming at precision enhancements of products. Multi-pass ISF technique is usually employed to manufacture parts with extremely large wall angles which cannot be achieved without failure using the single-pass ISF. However, existing studies show that the geometric precision of the products of multi-pass ISF is usually very poor, which has significantly hampered the widespread application of this technique in industry. In the present study, two control algorithms based on the MPC framework were proposed, targeting at achieving a more precise geometry of multi-pass ISF products. MPC-1 was an extension of the control algorithm for the single-pass ISF process reported in our previous work, and MPC-2 was developed for the first time. The developed MPCs were comparatively validated by a group of physical benchmark test. Compared to MPC-1, MPC-2 reduced the maximum geometric error in the wall, conjunction, and base zones on the same part by 26%, 51%, and 73%, respectively. The test results show that MPC-2 had a better performance in multi-pass ISF processes. [ABSTRACT FROM AUTHOR]