Influence of Linear Loading Paths on the Formability of a Tube in Hydroforming

A loading path plays a paramount important role in hydroforming. The Influence of three types of linear loading paths on the behaviors and formability of a tube in hydroforming is investigated by experiments on a self-developed tube hydroforming apparatus and finite element simulation. Focuses are placed on the formability such as wall thickness distribution, the bulged profile shapes and the obtainable maximum diameters. The results show that an axial feeding is unreasonable before the bulging deformation in forming zone is large enough. The way to hold a proper internal hydraulic pressure for a while and then augment it linearly while keeping the axial feeding increasing in a linear way is a desirable loading path.