An approach for the forming of large-thickness-flange components by injection forging

Injection forging has advantages for the nett-forming of flange-typed components. Research, however, has identified that folds occurred on material free-surfaces during the injection upsetting of flanges when the billet-diameter/flange-thickness ratio was beyond 1.2. These occurred at lower aspect ratios than that defined with reference to the stability of the billets. FE simulation and experiments were conducted to identify approaches by which the initiation of folds could be prevented and, hence, the process range of injection forging could be improved. It was recognised that, since the folds develop for conditions under which the billets are stable (no buckling or lateral sliding), it is possible to design a forming route of more than one stage to prevent the development of the flaws and, hence, to extend formability. Through the research, a preforming procedure was developed by means of which the process range of injection forging of solid components can be extended to flange-thickness/billet-diameter ratios of 1.4–1.5 using machined preforms, and to 1.50–1.64 using preformed billets. The proposed preform enabled the forming of several flange-typed components without folds.