Obvious formulas of the optimum semi-coning and accuracy compared with conical die under the minimum necking pressure

One more rational calculation formulas of necking deformation pressure is constructed based on the theory of plasticity forming, and used the formulas for the objective function, the relationship of the optimum semi-coning with conical die α^* and friction coefficient μ is solved under the minimum necking deformation pressure, one new obvious formula is derived to simplify the calculation of the optimum necking semi-coning, through the idea of approximate function processing in direct search numerical method. The accuracy is compared with the other two obvious formulas related literature. The results show that precision calculating under the new obvious formulas α^* =arcsin(0.76 3√μ) is more full correctly to reflect essential characteristic of necking deformation, and is most consistent with the corresponding process experimental data. This study provides a reference and a basis for the progress of stamping processing technology combining the development of optimization techniques.