An Analytical Model and Numerical Simulations to Predict Process Parameters in the Tube Bending Under Internal Fluid Pressure

Nowadays, thin-walled tube bending at small bending ratios (equal to R/D, R: bending radios, D: tubes outer diameter) is a production process widely used in advanced industries. Despite extensive studies into the field of rotary draw bending area, few of them have implemented this process with internal fluid, and they have not reported the exact location of bend defects and the effects of bending ratio on the defects of Hydro-rotary draw bending either. This research has been carried out to obtain the smallest bending ratio, and maximum applicable internal pressure in Hydro-rotary draw bending of thin-walled AA6063 alloy tube using analytical model. In addition, some effective parameters in Hydro-rotary draw bending are simulated with ABAQUS-software. Maximum thinning and critical ovality regions were investigated in addition to the effects of bending ratio and internal fluid pressure on the distribution of thickness and ovality, using simulation, analytical and experimental tests. The results showed that the selected necking criterion would be able to successfully determine the onset of rupture in bending. In order to validate FE-simulation, the effects of bending ratio and internal pressure on defects, such as cross-section ovality and thickness changing have also been investigated through simulation in ABAQUS-software and experiments.