Embedding of internal fluid pressure investigation in mandrel through tube rotary draw bending of thin-walled tubes with critical bend radius

Nowadays, thin-walled tube bending (D/t≥20, D-tube diameter and t-tube thickness) in the critical bend ratio (R/D≤2, R bend radius) is a widely used manufacturing process in the aerospace industry, automotive, and other industries. During tube bending, considerable cross-sectional distortion and thickness variation occurs. The thickness increases at the intrados and reduces at the extrados. Also in some cases, when the bend die radius is small, wrinkling occurs at the intrados. In the industry, the mandrel is used to eliminate wrinkling and reduce cross-sectional distortion, which the choice of the mandrel depends on, tube material, bending angle, radius tube and bending radius. However, in the case of a close bend die radius, using the mandrel avoided. Because the mandrel, in addition to the cost of the process, the thinning of the wall increases at the extrados and this is undesirable in the manufacturing operation. So, in the present study regarding to development of tube hydroforming, internal fluid pressure is used instead of the mandrel. Therefore, the purpose of the feasibility study, observation and analysis of the formation of tube bending process, the tube rotary draw bending process with two of the mandrel and the internal fluid pressure is simulated by software ABAQUS.