Closed Die Forging Preform Shape Design Using Isothermal Surfaces Method

Preform design is a key step in the development of hot forging processes. Optimal preform shape must ensure complete die fill with minimal flash and reduced forming load while avoiding flow defects like laps. Despite numerous works in this field, preform design is still often based on the trial-and-error method. There is an approach to preform design based on equipotential or isothermal surfaces obtained from a Laplace equation in the domain between two shapes representing the workpiece and the final forging. This method has not been widely applied to practical implementation. It requires proper, but not obvious, selection of the most suitable equipotential surface to be converted to a CAD model to create a preform shape and then creating a die block design based on this shape to perform further optimisation of the technological process by means of simulation. This routine requires several geometrical transformations between simulation and design programs that can be difficult to accomplish using general-purpose CAD programs. In the presented work the authors have integrated QForm metal forming simulation software with a specially developed variant of. CAD system to automate the data transition from finding of the isothermal surfaces used as prototypes of the preform shape with subsequent die blocks creation and further verification of the technology by simulation. The method is illustrated by industrial cases. (C) 2020 The Authors. Published by Elsevier Ltd.