A design method for cold backward extrusion using FE analysis
The dimensional accuracy of the cold forged products is strongly dependent on the elastic characteristics of the die. Therefore, a design method that makes the elastic deformation of the prestressed die as small as possible has been proposed for precision cold forging. For the purpose, applying the hard materials such as sintered carbide to the first stress ring is considered in die construction. For the design, Lam's equation is used and the diameter ratios and interferences are determined by using the maximum inner pressure without yielding of rings after shrink fitting and during cold forging. The rigid-plastic FE analysis of backward extrusion process using DEFORM has been performed and the analysis of elastic deformation of the dies has been done by using ANSYS with non-linear contact. In the simulation results, it has been found that the use of high stiffness materials to the first stress ring of forging dies can reduce the elastic deformation of die insert without failure.
dimensional accuracy elastic deformation first stress ring diameter ratio interference