Optimisation of spiral forging process design for ensuring dimensional precision of forged round billets by three-dimensional rigid–plastic finite element analysis

Abstract

Focusing on the spiral forging stage of the hot free forging process, which is the final stage to finish round billets from ingots, the optimisation of the operational conditions for ensuring dimensional precision of the final round billet has been carried out mainly by numerical analysis. In the analysis, a three-dimensional rigid-plastic finite element method was used and the validity of the analysis was examined by laboratory experiments using lead billets. The independent influence of each chosen major operational parameter, i.e. the rotational angle and the feed, has been clarified and critical and suitable ranges of the operational parameters for ensuring dimensional precision have been specified. As a result, the optimum combination of rotational angle and feed has been clarified and a fundamental scheme to optimise spiral forging process design has been suggested taking account of not only dimensional precision but also productivity. Moreover, it is suggested that the optimum rotational angle can be determined independently of the anvil geometry.