Experimental investigation of different parameters at a combined cross wedge rolling and multi-directional forging process

To forge a flashless crankshaft within few steps and with low energy consumption innovative forging processes are necessary, such as cross wedge rolling and multi-directional forging. The direct combination of the two forming processes normally leads to flash at the bottom of the crankweb preform after the multi-directional forging. The reason for the flash generation is the rotation-symmetric cross wedge rolled billet, which is formed laterally to the main axis during multi-directional forging. In this paper, a parameter field in which flashless crankshaft preforms can be forged is presented. The parameters varied within the experimental research are the forming angle and the cross section area reduction at cross wedge rolling as well as the axis offset, the billet temperature and the forming velocity at the multi-directional forging. The limits of this flashless parameter field are shown in several diagrams. For a flashless combination of two forming process low values for all parameters such as a forming angle α = 30°, a cross section area reduction ΔA = 30%, and a billet temperature T = 1050 °C are recommended. Furthermore, the intensity of the influence of the significant parameters are shown. The cross section area reduction ΔA thereby caused the highest range at flash generation with 0.4 mm.