Trajectory Optimization And Numerical Simulation On Metal Sheet Single Point Incremental Forming

Single Point Incremental Forming Process (SPIF) is a novel, flexible and dieless sheet forming process. This technique is based on "layered manufacturing" the idea of the rapid prototype technology. According to the shape of the parts, the NC program is designed to control the tool in accordance with a certain trajectory gradually forming in the sheet metal, eventually to be the needed shape. The process does not depend on the mold, so the time and money requirements is much lower than the traditional stamping technology, having a great advantage in the individual part or low batch parts to overcome the market growing demands of highly customized products.During SPIF process, a reasonable forming trajectory of a given part is the key to that the given part can be quickly manufactured whether or not. So effects of forming trajectory and process parameters on SPIF was studied in this thesis. By conventional incremental forming experiments, detailed information such as stress distribution, strain and other mechanical parameters couldn’t achieved directly. Finite element method (FEM) adopted by the numerical simulation can be direct, convenient and intuitive access to these valuable data used in the analysis of forming process.This paper established the finite element model of the cone and analysed the strain distribution based on simulation experiment, confirmed that the incremental forming strain state is approximated as plane strain. And the results of studied processing parameter showed that: the equivalent strain and stress increases with increasing amount of step size. The step size is more small, the wall thickness is more uniform, the time required for process is longer. So the step size should be a moderate value. Tool’s diameter is larger, the maximum equivalent strain and stress is smaller, and the strain and stress concentration phenomenon eased.Moreover, the traditional contour line trajectory is optimized. By inverse alternating trajectory, the thickness in one direction rapidly thinning and twisting deformation of the bottom is solved. By two pass forming trajectory optimization on the corner of part, the sheet thickness thinning concentration on both sides of corner is solved. By two pass forming trajectory optimization on the part wall’s forming angle, the sheet thickness thinning along the depth direction eased.