Finite element analysis of a multi-stage axisymmetric forging process having a spring-attached die for controlling metal flow lines

In this paper, a computer simulation technique for the forging process having a spring-attached die is presented. A penalty rigid-viscoplastic finite element method is employed together with an iterative force-balancing method, in which convergence is achieved when the forming load and the spring reaction force are in equilibrium within the user-specified allowable accuracy. The force balancing is controlled by adjusting the velocity of the spring-attached die. To minimize the number of iterations, a velocity estimating scheme is proposed. Two application examples found in the related company are given in order to emphasize the significance of metal flow lines for quality control and to investigate the effects of spring-attached dies on the metal flow lines as well as the decrease in forming load.