ProKomb - Process combination of cross wedge rolling with multi-directional forming

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High-duty complicated long parts made of steel are usually forged with flash in several stages. The potential of flashless forging of these parts to increase the resource efficiency in production has been demonstrated in recently completed research projects using crankshafts as example. A defect-free, four-stage sequence has been developed for a two-cylinder crankshaft with secondary form elements pin and flange. The stages are cross-wedge rolling, lateral extrusion, multi-directional forging and precision forging. The multi-directional forging has been identified as an essential step in order to realize an offset between pin bearings and main bearings in a flashless forging operation. The shortening of the process steps to three steps without the lateral extrusion partially caused a formation of folds and flash. The causes of these defects have not been identified, yet. The absence of knowledge about the causes prevents a reliable design of the appropriate processes. To identify the dependency between the geometry of the cross wedge rolling and the multi-directional forging concerning the development of folds and flash is therefore essential in order to forge complicated forgings flashlessly. This is necessary for a shortened forging sequence.In order to forge complicated forgings flashlessly in a shortened process chain, the aim of the project is to investigate the relationship between cross-wedge rolling and multi-directional forging. The main focus lies on the geometrical aspects. A universal mathematical model shall facilitate the design of the geometry of cross-wedge rolling preforms and the forming elements of the multi-directional forging tool. The boundary conditions of the model shall be determined using finite element simulations of the forming processes and shall be verified in forging trials. Shafts without an offset of the main bearing and crankshafts (with the offset) are taken into account to be able to transfer the application to a wider variety of complicated long parts.