Experimental study of springback behavior in incremental bending process

Abstract

Manufacturing complicated and thick ship-hull plates at reasonable price and efficiency has always been a challenge in shipbuilding industry. One widely used method is line heating process, which is not only labor intensive but also ineffective. Recently many flexible forming processes have been developed while they all have avoidable disadvantages. In order to reduce the forming force, our group proposed one flexible incremental bending technology, during which the flat blank was bended into the required shape by gradually stamping at various positions. During the incremental bending process, the minimum energy method is used to determine the proper loading path. However, there is huge springback phenomenon after each bending. The shape change after each springback process should be considered in the loading path determination to make sure the accurate shape can be obtained.Here in this paper, the springback behavior of the carbon steel Q235 during the incremental bending process was investigated by experiments. In the first stage, the flat plates were bended several times at the same position while the final bending depth is the same, the final bending shapes after springback were compared to each other to investigate the influence of loading path on the springback behavior of the material. In the second stage, the flat plates were bended once at various positions and bending depths to study the springback behavior in one step bending process. It was found that loading path has little influence on the springback behavior, so during the incremental bending process, the springback law obtained from each single bending process can be used to combine with the minimum energy method to obtain the proper punch moving trajectory.