Study On The Springback Of High Strength Steel Sheet After Bending And Its Control

The high-strength steel is widely used in the field of automotive manufacturingindustry for the sake of safety, environmental protection, economic considerations et al.But in the forming process, compared with ordinary steel, the high-strength steel isprone to have the problem of wrinkling, cracking and springback. The springbackproblem is particularly complex. When the forming unloads, the shape and size of theparts don’t match the working surfaces of the stamping dies because of the elasticrecovery. Then the product accuracy will be affected. Although there are urgent needs tosolve the springback problem in engineering, up to now in theory there are still manyproblems unsolved. So the effective guidance can’t be provided.In this paper, the design of a U/V-shaped general bending springback testing deviceis used to investigate the main factors which influence the springback experimentally.Combined with the finite element numerical simulation, the material springback law isanalyzed in order to provide the basis for the reduction and controlment of thespringback.①The key technologies, such as the material yield criteria, hardening rule,nonlinear elastic recovery, finite element numerical calculation methods and so on, inthe numerical simulation are discussed.②The basic mechanical parameter test is implemented on the high-strength steelB210P1, B280VK and ordinary steel DC03. Their differences in formability arecontrasted.③Using the design of U/V-shaped general bending springback testing device, themain factors affecting the U-shaped parts bending, such as the the fillet radius of thepunch, the die clearance are experimented. In the U-shaped parts bending, the effect ofthe protruding material below the punch on the springback and the factors influencingitself are also studied. In addition, the U-shaped parts bending are experimented andanalyzed in the use of punch with different shape at the bottom.④The V-shaped parts bending process with different transition at the bottom ofthe die are analyzed by using the physical experiments and finite element numericalsimulation. And the effect of the over-pressure quantity on the tangential stress along the thickness direction in the main deformation zone is observed. According to theconclusions, the guiding idea of springback control is proposed.