Abstract:A ‘bone-like’ hollow component with curved axis and complicated cross-sectional geometry was used as the object. The experimental setup for the hollow component by welded double sheet hydroforming was designed and used for the forming of the part. The formability influenced by blank shape and size, loading path combined by the clamping force and liquid pressure was explored, then the reasonable process parameters avoiding defects were obtained. The results show that the reasonable blank shape can not only save materials and reduce costs but also avoid fracture at the corner caused by the large expansion rate and wrinkle in the transition zone of different cross sections. The loading path has a serious effect on the material flow in the pre-forming stage. The complex hollow shell structure with curved axis and varied cross sections can be fabricated by double sheet hydroforming process more easily and efficiently than traditional stamping and welding method. The process can also solve the problem of the limitation of expansion rate by tube hydroforming for the structure with a large difference of cross sections.

Key words: hydroforming; hollow component; varied cross sections; curved axis; clamping force; liquid pressure; loading path