Design for stiffness reinforcement in backward extrusion die

The dimensional accuracy of the cold extruded products is highly dependent on the elastic characteristics, diameter ratios and interferences of the dies. In this research, sintered carbide is considered as the materials of the first stress ring to increase the stiffness of the prestressed die. In order to evaluate the validation of this method, FE-analysis has been performed according to the arrangement of die configurations. Diameter ratios and interferences have been determined by using Lamé’s equation with the condition of maximum inner pressure without yielding of materials after shrink fitting and during forming. The radial displacements on the inner surface of the die insert for several die configurations were analyzed by the elastic FE-analysis. The analysis shows that the backward extrusion die prestressed with the high stiffness material could be more strengthened than the conventional die construction.