Research Progress of Springback in Multi-Point Forming of Sheet Metal

In the manufacturing of sheet metal, multi-point forming replaces the traditional integral die with discrete basic body groups to adjust the height of each basic body and form the required three-dimensional curved surface, thereby facilitating flexible processing. Multi-point forming is the most common approaches for the manufacturing of sheet metal but can cause serious shape distortion due to springback phenomena. In this paper, key research on springback is categorized and analyzed from three aspects: springback theory, springback numerical simulation analysis, and springback control, followed by summary of the current research status and outlook on promising future research directions of springback in multi-point forming springback. And the conclusion is drawn: in the future, multi-point forming of sheet metal using high-frequency ultrasonic excitation for springback control during the forming process coupled with artificial intelligence for springback compensation control will be a promising research direction for controlling springback in the multi-point forming of sheet metal.

Springback Prediction of Dieless Forming of AZM120 Sheet Metal Based on Constitutive Model

Springback control is a key issue of the sheet-metal-forming process. In this paper, the mechanism of sheet-metal-forming along the folding trajectory of the computer numerical control (CNC) four-side automatic panel bender was studied, based on the bend-forming springback compensation theory of the power function material model. Firstly, the mechanical property of AZM120 sheet metal standard samples was tested. Then, a theoretical model of springback compensation under plane strain conditions was built, based on the constitutive relationship of the elastic or the elastic-plastic power hardening material. In addition, a sheet-metal-forming trajectory model was designed for sheet metal bending using the vector method. Finally, a laser tracker was used to acquire the folding trajectory, and then the reliability of the trajectory model was verified. On this basis, the influences of geometric and process parameters, such as sheet thickness, forming angle, and bending radius in springback control, were studied according to the theoretical formula and verified by experiments. The proposed method is generally applicable to operation conditions where the bending radius ranges between 1.5 and 6.0 mm and plate thickness ranges from 0.8 to 2.5 mm, and the achieved overall accuracy was more than 89%.