Influence of blank profile on the V-die bending camber process of sheet metal

Abstract

The finite element simulation is now widely used in the design of stamping tools. A trial and error procedure has been replaced by a simulation in which defects associated with sheet forming processes are predicted and evaluated. This paper aims to clarify the process conditions of the V-die bending of a sheet metal. It provides a model that predicts not only the correct punch load for bending, but also the precise final shape of the products after unloading. An incremental elastic-plastic finite element computer code, based on an updated Lagrangian formulation, was developed to simulate the V-die bending of sheet metal. In particular, the assumed strain field (ASF) element was used to formulate the stiffness matrix. The r-minimum technique was used to deal with the elastic-plastic state and solve contact problems at the tool-metal interface. A series of experiments were performed to validate the formulation in the theory, leading to the development of the computer codes. The predicted punch load in the finite element model agrees closely with the experimental results. The whole history of deformation and the distribution of stress and strain during the forming process were obtained by carefully considering the moving boundary condition in the finite element method . A unique feature of this V-die bending process is the camber after unloading. The computer code successfully simulates this camber. The simulation was performed to evaluate the effects of the size of the blank on the camber process. The results in this study clearly demonstrate that the computer code efficiently simulated the camber process .