A THEORETICAL AND EXPERIMENTAL ANALYSIS OF ROTARY COMPRESSION OF HOLLOW FORGINGS FORMED OVER A MANDREL

摘要

The paper presents selected results of studies of the process of forming hollow stepped shaft forgings by rotary compression with rotary tools. The aim of the study was to determine whether rotary compression could be performed using an additional tool - a mandrel, which, when positioned in the cavity of the workpiece, could be used to shape the surface of the cavity. A theoretical analysis was based on finite element modeling using Simufact Forming software. During the simulations, distributions of deformation intensity, temperature, and the Cockroft-Latham fracture criterion were determined. Predictions were also made regarding phenomena such as slippage and deformation of forging pieces and material cracking, as potential impediments to the investigated process. Additionally, force parameters were determined during the forming of forgings. Numerical results were verified experimentally. Rotary compression tests for hollow forgings were carried out in a special forging machine designed by the present authors. The results were validated on the basis of the geometric parameters of formed forgings and the force parameters of the process. The results confirm that hollow stepped shaft forgings can be formed in the process of rotary compression using a mandrel. Forgings formed over a mandrel are characterized by greater precision and quality compared to freely formed blanks (without a mandrel).