November 2020 Volume 2

FORGING RESEARCH AND TECHNOLOGY

Fig. 5 Conventional Die Set, Heading Stage

Fig 6. Proposed Tapered Die Design

To determine the potential energy stored in the die assemblies for the conventional and the proposed die architecture, static stress analysis was carried out using ANSYS software package. For the proposed new die, a taper angle of 7° was introduced on the die that allows it to slide over the stress ring under friction. The workpiece was modeled as a rigid plastic body, while the die was modelled as elastic body. A frictional contact of μ = 0.1 was used. The bottom surface of the die was fixed, while each of the inner surfaces of the die was prescribed with an averaged pressure imported fromDEFORM 2D software package which was used to model plastic deformation of

the pinion gear. The contact pressure profiles for conventional and proposed die are shown in Fig. 7. The effective stress for the conventional and the tapered die are shown in Fig. 8. For the conventional die, higher stresses are concentrated along the first reduction corner where the die supports the workpiece and the forging pressure acts. On the other hand, the tapered die slides down the stress ring by 0.4 mm, under frictional forces. During this motion, the insert contracts radially, gripping the workpiece tightly towards the end. This explains the higher stresses in the bottom of the die insert [Fig. 8(b)].

Fig. 7. Pressure profiles fromDEFORM 2D (a) Conventional die (b) Tapered die design

FIA MAGAZINE | NOVEMBER 2020 36

Fig. 7. Pressure profiles from DEFORM 2D (a) Conventional die (b) Tapered die design