Experimental analysis of bent electric heaters using tube freeform bending

Abstract

Design of a bending die for electric heaters is time-consuming work that is done largely by skilled experienced engineers. The goal of this study is to provide an easy, low-cost experimental solution for bent electric heaters with arbitrary curvatures, instead of complicated theoretical analyses. An in-plane tube freeform-bending process with pneumatic power is used to bend the electric heater without defects. Experimental results show that the proposed bending tool is workable, although different defects may be present for Cu and Al electric heaters. To avoid bending defects, the size of the bending-roll is recommended to be more than 5.8 times greater than the diameter of the electric heater. An empirical relationship between bending curvatures and process parameters is provided for manufacturers. The applicability of the bending tool is limited to very small bending angles for hollow metal tubes.