Optimization of die parameters for titanium ring pipe formation

A computer simulation system of the ring pipe bending process of titanium alloys was established using MSC/Superform finite element simulation software on the basis of elastic-plastic finite element theory. The Archimedes spiral was selected as the center axis of the ox-horn die with small bending radius for maintaining the continuity of the curvature radius. Optimization simulation of die parameters such as Archimedes constant, expanding diameter ratio and bending angle was carried out by mid-frequency induction heating method. The conclusions are as follows: (1) the reasonable Archimedes constant can ensure the sound uniformity of the wall thickness and the optimized constant was 1.0 according to the simulation; (2) the too higher expanding diameter ratio would induce easily some defects such as crinkles and thickness-decrease, while the too lower ratio would induce thickness-increase of the abdomen and uniformity-decrease of the wall-thickness; thus the preferred ratio value was 1.33 for the process; (3) if the bending angle was too small, the pipe bending progress was severe and the mechanical properties of the obtained pipe could not satisfy the requirements well; if the angle was too large, the bending progress was stable, but the thrust became difficult as the increase of the thrust resistance; therefore, the preferred bending angle was 40° for the process. The titanium ring pipe with uniform wall thickness, high-voltage-resistance and equal strength was obtained using the above mentioned parameters, detected by the orthogonal test.