Optimization for the forming process parameters of thin-walled valve shell

Ball valves are widely used in industry, and the valve shell, a key component, is conventionally produced by casting and forging. A new technique, tube hydroforming, is introduced to overcome limitation of the conventional techniques. In order to obtain the optimal forming parameters of hydroforming, a new method combining genetic algorithm with finite element simulation is proposed in this paper. On the basis of plastic theory, the internal pressure and axial feed are expressed as a function of the stress ratios, respectively. Then, finite element method is used as a solver of the objective function, and genetic algorithm is employed to search the optimal stress ratios. Finally, the optimal internal pressure and axial feed are calculated by using their computation expressions. Verified experiments are carried out in the plant. The experiment results show that the proposed method can effectively obtain the optimal loading paths of tube hydroforming and remarkably improve quality of the ball valve shell.