Numerical Simulation Research On Formability Of Discrete Blank-holder Stamping Process

Stamping is the most widely used type of sheet metal forming, having advantages of high surface quality, stable dimension and high productivity, etc. For most of the parts on the market,the blank-holder is usually need to cooperate with the mold to finish forming process and the blank-holder device and BHF affect the formability significantly. The whole blank-holder process can guarantee the forming performance of simple shape parts. But the complex material flow and deformation degree of complex-shaped parts can lead to forming defects such as wrinkling and cracking. With the introduction of complex-shaped parts and high strength materials, whole blank-holder process has been difficult to guarantee its formability.Refer to the discretization idea of the Multi-Point Forming(MPF), the whole blank-holder is discretized into independent discrete blank blocks as the blank-holder device. By adjusting the BHF according to different deformation areas, the defects can be effectively restrained and the formability can be enhanced.The main contents and conclusions are summarized as follows:1. Established finite element numerical simulation model.The finite element models of the box-shaped parts by two kinds of blank-holder process and multi-curvature complex surface parts by the discrete blank-holder process were established. The setting of boundary condition, contact setting and mesh division which have a significant impact on the simulation results was discussed in detail.2. The comparative analysis on the formability of the whole blank-holder and the discrete blank-holder for box-shaped parts.The formability of two kinds of blank-holder process from two angles of thickness distribution and deforming depth was analyzed by numerical simulation methods. The difference of the thickness distribution under the same forming depth was not obvious. Besides, the forming depth of the discrete blank-holder process can reach 80 mm, which is doubled compared with the whole blank-holder process. It was proved that the formability can be improved effectively by adjusting the BHF distribution.3. Analysis of impact of process parameters on the formability of deep drawing box-shaped parts by discrete blank-holder process.In the case of the forming depth of box-shaped parts by discrete blank-holder process was 70 mm, the influence of the shape and size of the blank, the friction coefficient between the blank and the flexible blank-holder and the thickness of the flexible blank-holder on the forming properties were studied.4. Numerical simulation research on the formability of multi curvature complex surface parts by discrete blank-holder process.The influential factors and rules of stamping formability of multi-curvature complex surface parts by discrete blank-holder process were studied though numerical simulation method. The optimized numerical simulation result of the parts was obtained through a comprehensive consideration of the forming results of the various specific parameters and adjusting them. And the numerical simulation results were verified by another numerical simulation software. That proved that the discrete blank-holder technology can effectively improve the formability of the complex surface parts.