The bumper reinforcement looks simple, but it needs to be both lightweight and meet the requirements of impact resistance tests. The problem is: thin-walled high-strength steel is most prone to springback during forming.
Why does it springback?
High-strength steel has a large elastic recovery force after being stressed;
When the bending angle is large, the stress distribution on the inner and outer layers of the sheet is uneven;
An overly hard or soft mold can cause unstable dimensions.
Solutions:
Multiple passes with small angles of bending: Reduce the single deformation amount to allow stress to be released gradually;
Local heating or roller coating: Reduce the friction on the metal surface to improve the forming stability;
CAE simulation optimization: Estimate the springback amount in the design stage and correct the mold angle.