Three Dimensional Finite Element Analysis of Staggered Backward Flow Forming Process

Flow forming is one of the cold forming processes which is mainly used to produce thin-walled high-precision tubular components. A three dimensional coupled-field thermo-mechanical finite element model for staggered three-roller backward flow forming of a cylindrical workpiece of MDN-250 maraging steel has been developed using Abaqus/Explicit. In this model, the effect of tip radius of the rollers and friction between the rollers and the workpiece has been considered. The bottom of the workpiece is fixed in the axial direction so that diametral reduction and the axial elongation can be studied. Simulations have been carried out at different process conditions to study the state variables, such as stresses and strains obtained during the deformation. The model has been benchmarked with the experimental results for thickness reduction and the error in the thickness prediction is limited to 4%. The roll forces have been benchmarked against analytical formulation and a difference of 13–20% has been observed. The effect of flow forming process variables, such as feed rate and reduction ratio on the stress/strain distribution and roll forces have been studied. The results show that the roll forces increase at higher feed rates and higher reduction ratios whereas the equivalent strains increase at lower feed rates and higher reduction ratios. In addition, a parametric study has been conducted to study ovality, diametral growth, roll forces, stresses and strains as a function of process parameters.