Application of RSM in optimization of bi-layered X-type tube hydroforming

In this study, the hydroforming process parameters of a bi-layered X-type tube are designed and optimized by exploring the response surface methodology. First, UG software is used for model setup of the bi-layered X-type tube and mold, which is imported into DYNAFORM software for further numerical simulation and calculation of the hydroforming process. The main parameters of the loading path are selected as experimental factors for the methodology. The maximum thinning ratio of the inner and outer tubes, the maximum clearance between bi-layers, and the limit fillet radius of the top branch tube are used as test evaluation indicators. In accordance with effective evaluation indexes, perturbation plots, optimization evaluation criteria, and contour graphs, the relationship among the main influencing factors is analyzed and the process parameters of the optimal loading path are screened. Finally, a comparison between experimental results and simulation is made and shows that the error is within 6%, which indicates that the optimization method of the hydroforming process parameter in a bi-layered X-type tube has high feasibility.