Incremental Forging of Balls from Cylindrical Specimens and of Rollers from Rectangular Solids

An experimental investigation was made of the incremental forging of balls and rollers of nominal diameter ¾ in. from cylindrical bar stock of commercial pure aluminium, hard aluminium, tellurium lead, copper and mild steel. Cylindrical and rectangular specimens with different shape factors—that is, height to base dimensions—were compressed quasistatically between suitably prepared hemispherical dies in the case of ball forging and between semicircular dies for roller forging under both dry and lubricated conditions. Results of specific forging load versus die movements are given and they are compared with those predicted by a simple axisymmetric upper bound analysis for ball forging and plane strain upper bounds for roller forging. Observations about the deformation during the incremental forging of ball and roller were made and are discussed.