Investigation of springback behavior and process control for stamping of ring-shaped workpiece

Due to the elastic deformation of metal stamping, springback is a serious problem to cause shape deviation and thus reduce precision. The springback behavior of ring-shaped workpiece is investigated in this paper and an auxiliary boss device is proposed to control the springback deformation. A finite element model is developed. The characteristic parameters including boss height, boss angle and boss gap are discussed systematically. It can be concluded that the gap has a positive linear correlation with springback percentage, and the boss angle has an optimal interval of 30 ? —60 ? to reduce springback. When the boss height increases, the springback decreases, but the effect weakens when the boss height is larger than 1.0 mm. Then, a response surface analysis is conducted with Design Expert 8.0.5 software and an optimal parameter process window (i.e., boss height from 2.1 to 3.0mm, boss angle from 53? to 60? and the gap from 0 to 1.2mm) is obtained. Finally, a set of molds are fabricated and the stamping experiments are conducted. The springback behavior is well controlled. The springback percentage can be decreased from 33% to 6% by using the auxiliary boss device of ring-shaped workpiece.