Deformation analysis of springback in L-bending of sheet metal

Purpose: In the present study, the deformation mechanics of the springback phenomenon in the L-bending of sheet-metal was examined and a new method that could efficiently reduce springback in the L-bending of sheet- metal was proposed. Design/methodology/approach: Both the finite element analysis and experiments were performed to analyze the deformation mechanics and the effects of process parameters on the formation of springback. Findings: The axial stress distribution in the bent sheet obtained by the finite element simulations was classified into three zones: the bending zone under the punch corner (zone I), unbending zone next to the bending zone (zone II), and the stress-free zone (zone III). It is found that the stress distribution in zone I is quite uniform and hence has little influence on the springback. While the stress distribution in zone II results in a positive springback, whereas the stress distribution in zone III produces a negative springback. The total springback therefore depends on the combined effect of those produced by zone II and zone III. A reverse bend approach that can efficiently reduce springback was also proposed to reduce the springback in the L-bending process. The finite element analysis performed in the present study was validated by experiments as well. Research limitations/implications: Although the reverse bend approach can reduce springback efficiently, it may cause uneven surface at the die corner area. Hence, the use of reverse bend approach must be cautious if high surface quality is required. Practical implications: The proposed reverse bend approach provides the die design engineer with a novel idea to reduce the springback occurred in the L-bending of sheet metals. Originality/value: In addition to the reverse bend approach, the analysis of defomation mechanics of springback performed in the present study also provides researchers with a better understanding of the formation of springback.