Optimization of springback for AZ31 magnesium alloy sheets in the L-bending process based on the Taguchi method

Abstract

Springback is a primary issue which is encountered during most sheet metal bending processes. Using the Taguchi method, this study investigates the springback of L-bending with a step in the die through simulation and experiments for AZ31 magnesium alloy sheets at different temperatures. The process parameters for bending springback in this study include: lower punch radius, die clearance, step height, and step distance; we use a Taguchi L9 orthogonal array to design the combinations for the experiments. The results of ANOVA analysis show that, for each bending temperature, the process parameters that affect springback occur in the following order: step height (greatest), lower punch radius (next), die clearance (smaller), and step distance (smallest). In addition, with the increase of the bending temperature, the angle of springback decreases. The optimal parameter combinations at each bending temperature from the signal-to-noise response are all the same, namely, a die radius of 2 mm, die clearance of 0.5 mm, step height of 0.1 mm, and step distance of 2 mm. When the bending temperatures are 100°C, 150°C, and 200°C, the angles after springback of the optimal experimental parameter combination are 91.06°, 90.63°, and 89.84°, respectively.