Abstract: Hydroforming is an effective method for manufacturing thin-walled parts. In order to develop a forming process of complicated thin-walled circular superalloy parts with irregular section, a technology scheme is proposed consisting of hydroforming with axial feeding by using moving dies. Meanwhile, an analysis is made of stress characteristic and strain state based on plasticity method and incremental theory, and its finite element models are built. The effect of the key process parameters, including the height of forming area for cylinder blank and loading paths of cavity pressure on the quality of the parts, is explored with the assistance of numerical simulations and verification experiments. Furthermore, the failure modes during the forming process, including excessive wall thinning, accumulation folding and configurational asymmetry are discussed, and the technological parameters are optimized. The results indicate that the proposed technological method is feasible for the accurate integral forming of complicated thin-walled circular parts with irregular section; moreover, the parts with uniform thickness distribution and high quality can be successfully formed by using optimal height of forming area and loading path of cavity pressure.

Key words: hydroforming, moving dies, thin-walled circular part, irregular section, loading path, wall thickness, integral forming