Study of the effects of die geometry on deformation in the radial forging process

Radial forging is an open forging process used for reducing the diameters of shafts, tubes, stepped shafts and axels, and creating internal profiles for tubes such as rifling of gun barrels. Usually a mandrel is used inside a tubular workpiece to create internal profile and/or size the internal diameter, but the process can also be performed without a mandrel when workpiece geometry does not allow utilizing it or the internal surface quality is not critical. Moreover, in stepped shafts and tubes, often there is a fillet connecting two different sections. If it is possible to produce that fillet during the forging process, the process could be more cost effective. So, in this paper, four different shapes for the die inlet zone including linear, convex, concave and hybrid surfaces are considered and the effects of die shape on the deformation pattern and quality of radially forged products are studied. In this study, slab method analysis is used to obtain the deformation pattern, pressure distribution and the position of neutral plane in both cases; with mandrel and without it.