Process design of the cold forging of a billet by forward and backward extrusion

The process design of a forward and backward extruded axi-symmetric part has been studied. The important factors in the cold forging of an intricate part are the shape of the initial billet, possibility produced as a single-stage operation, as well as the shape of the pre-form. On the basis of theoretical knowledge on process design, numerical simulation of the cold forging operation has been carried out using the commercial finite element software, DEFORM. The design criteria on the operation are the forming load, defect-free geometrical filling of the dies and sound distribution of strain in the final product. It was found that the shape of the pre-form with 12.5 mm of lower extrusion was favorable. The optimum process for the final product was that final forming has to be carried out with an annealed pre-form. The numerical simulation result to be was confirmed to be good in agreement with experimental results. (C) 2002 Elsevier Science B.V. All rights reserved.