Longitudinal strain development in Chain-die forming AHSS products: Analytical modelling, finite element analysis and experimental verification

Chain-die forming is a new sheet metal forming technology which has been developed as a supplement to roll forming in fabricating Advanced High-Strength Steel (AHSS) products. It has an advantage by reducing redundant plastic deformation during the forming process. The implementation is achieved through increasing the deformation length, via increasing the virtual roll radii. The rolls with large radii are assemblies of shaped die-blocks through chains and therefore it is called “Chain-die Forming”. In this paper, a simplified analytical model, purely based on the geometric relationships of forming parameters is established to estimate the longitudinal strain development in Chain-die forming. The analytical model is verified successfully by finite element analysis (FEA) and experimental work. The factors affecting the peak longitudinal strain are also investigated. The study is expected to be useful to tooling designers to quickly assess the severity of a Chain-die forming process in the tooling design stage in order to shorten the tooling development time.