Calculation method of the press force in a round shaped closed-die forging based on similarities to indirect extrusion

摘要

The forging of a round shaped close-die forging with flash has similarities with backward can extrusion. In both cases, the material under the punch is upset, whereas the remaining rises along the die-walls. With this in view, the authors have calculated the required press force by separating the forged piece fictitiously into upset and extruded areas. Conventional upset slab method of analysis is applied to the material under the punch and the flash area, while the analytical formulation given for the extrusion is adopted for the rising material along the annular ring area between the punch and the die-walls. Die-wall angles are also included in the calculation. The results fit remarkably well with the values measured in the experiments carried out with lead and AISI 1020 steel samples. The size of the punches used in the experiments were changed to give three different shape difficulty factors.