Warm air bending of AZ31B sheets based on an online local contact heating method

Warm forming holds significant potential in shaping difficult-to-form materials due to the comprehensive advantages compared to the cold and hot forming. Effective heating is essential for specific warm forming processes. This paper investigated a novel warm air bending technique using an online local contact heating method. Preheating stage heat transfer and air bending of AZ31B sheets were examined at temperatures ranging from room temperature to 300 °C by experiments and finite element analysis considering the thermomechanical coupling effect. A noteworthy augmentation in the bending center angle, progressing from 86° to 133°, was obtained as the heating temperature ascends from room temperature to 250 °C. Fractures were successfully eliminated when the heating temperatures of the sheets exceed 150 °C. As the heating temperature increases, a concurrent decrease in the rebound angle is observed, diminishing from 10.6° to 2.3°. The results confirm the feasibility of warm air bending using the online local contact heating in the application in industrial environment, in terms of forming quality and production efficiency. Keywords: warm forming, air bending; contact heating, thermomechanical coupling analysis, AZ31B