Fixture layout optimization for deformable sheet metal workpiece

摘要

The purpose of the fixture layout design is to ensure the fixture positioning accuracy, which affects the resultant geometric variation of the positioned workpiece directly. The N-2-1 locating principle is widely applied in the fixture design for deformable sheet metal workpiece, not only for locating the workpiece, but also for restraining the excessive workpiece deformation. This paper proposes an approach to optimizing fixture layout for the sheet metal workpiece based on the 4-2-1 locating scheme. Firstly, three fixture locating points on the primary datum surface are optimized with genetic algorithm based on the rigid model considering the robustness and the geometry stability. Then based on finite element analysis, a back propagation neural network model is built to predict the deformation of the sheet metal workpiece under different fixture layouts and different fixture locator errors, and a genetic algorithm is used to find the optimal position of the fourth fixture locator based on the neural network prediction model. Finally, a case study is given to verify the proposed approach.