A new schedule-free mandrel-less bending method for straight/pre-shaped long tubes

The objective is to propose a new schedule-free mandrel-less draw-bending method to achieve high cross-sectional precision for straight and pre-shaped long tube, for which conventional methods lacking innovation are useless. The proposed method applies side compression on the tube. Analyses and experiments verified excellence of the method and the new method successfully reduced the error index of circularity under the severe conditions of conventional methods. The method would bring significant flexibility in manufacturing as the method is able to bend arbitrary portions of tubes and be placed in arbitrary positions of the process line.