Effects of upper platen configuration in the rotary forging process and rotary forging into a contoured lower platen

Abstract

The rotary forging process is affected by general geometrical features of the upper rotary conical platen which include, for example, the angle of inclination of the upper conical platen geometric axis to the forging head axis (θ) and the angle (γ) referred to as the “angle of tilt”. The effects of variation in these parameters on the performance of an experimental rotary forging machine in terms of the forging load, number of revolutions of the upper platen etc., have been studied with a view to rotary forging die design. Presentation of the experimental results is, generally, restricted to the sample upsetting of cylindrical specimens using pure lead as a model material to simulate the hot forging of steels. Comparison is made between the axial force required to rotary forge into a contoured lower platen and conventionally upset identical pure lead cylinders into the die. It is shown that the axial force required for rotary forging can be a small fraction of that required for conventional die forging. An analysis is also presented which predicts the relationship between the area of contact at the upper conical platen-specimen interface and the reduction in specimen height, for simple specimen and upper conical platen configurations. Theoretical and experimental results are compared and the analysis is used to establish mean die pressures during rotary forging.