| Single Point Incremental Forming Process (SPIF) is an innovative sheet metal forming technology without dedicated dies used to improve the traditional sheet metal process. By this method, complex shell parts could be manufactured with flexibility, cost reduction and convenient. Traditional stamping processes require the manufacture of large bathches in order to ensure economy of production. But SPIF is suitable to produce very small lot of batches economically and quickly to overcome the market growing demands of highly customized products.In the application, SPIF still exist some of the pressing need to address the question of how to select the correct technical parameters and how to avoid cracking in the forming. To solve these problems, the deformation mechanism of SPIF should be studied seriously. By conventional physics experiments, detailed information such as stress distrubution, strain and other mechanical parameters could't achieved directly. And it's not objective and comprehensive to understand the deformation mechanism of SPIF by indirect measurement of the partial data. Finite element method (FEM) adopted by the numerical simulation can be direct, convenient and intuitive access to these valuable data used in the studing of forming mechanism. In the conventional sheet metal forming technology research, FEM has played an important role.In SPIF process, the loading trajectory is complex and long, the thinning of the sheet thickness is dramatic, and the local deformations are accumulated. So, there are some difficutis in the numeriacla simulation of SPIF. For example, the modeling of SPIF is difficult and the computational efficiency is low.Based on the nonlinear, elastic-plastic finite element method theory, the modeling approach of the numerical simulatioin of SPIF was studied firstly in this project. Through the establishment of the eight-node hexahedral elements describing continuous variation of the thickness of adjacent elements, the involved nonlinear anisotropic elasto-plastic material model, the control strategies of the dynamic load of trajectories and so on, the FEM model of SPIF was reasonable planed. According to modeling planning, the most representative parts as the truncated cone and the truncated pyramid were used to modling, and each has been established two types of finite element analysis model, that is, the whole part FEM analysis model (WM-Model) and selected partical part FEM analysis model (SM-Model). WM-Model is established based on the realy situation of SPIF process, but SM-mdoel is established throuth adding suppositional bundary conditions. Through the comparative study of the four model simulation results and experimental results, it showed that the two types of models are applicable to the incremental forming the numerical simulation analysis, in which the cone-of the local finite element analysis model with the highest efficiency.Based on the WM-model, the various stages of SPIF process was studied and the forming characters have been realized. Based on the SM-model of the truncated cone, the blank thickness element was sub-meshed into three levels. And through the forming simulation of the process, access to the plate stress and strain of the different regions in forming, and proposed the establishment of a sub-regional mechanism to explain the incremental forming, that is, in different regions, sheet deformation is different. In the main region which reflects the major character of SPIF, the deformation pattern is the composition of bending and extrusion.Based on the SM-model of the truncated pyramid, the SPIF processes with different parameters were simulated. And the process parameters on changes in the thickness, plastic deformation region, forming force and so on were reseached. Thus, provide a reasonable basis for the selection of process parameters.Finally, the numerical simulation approach of tool wear was studid on the basis of numerical simulation of SPIF, and the process parameters on the impact of the tool wear were researched. |
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