Numerical process analysis of tool load and part ejection of helical lightweight gears manufactured by sheet-bulk metal forming

Abstract The increasing demand for resource-efficient production processes is bringing sheet-bulk metal forming (SBMF) into focus as an innovative process technology for the production of complex, thin-walled lightweight components with integrated functions. In particular, its potential to reduce material usage while maintaining high functional integration makes SBMF highly relevant for modern manufacturing industries. While scientific interest in SBMF has grown over the past decades, a research gap remains regarding the forming of helical gears, which are widely used in industry due to their high load capacity and beneficial running properties. This paper presents a numerical investigation of SBMF for manufacturing involute gears with a 20° helix angle via transverse extrusion. The investigations are conducted for DC04 steel, a commonly used deep-drawing steel with good formability and high industrial relevance. A finite element model is employed to analyze the effects of increasing die filling and component ejection on key process and component characteristics. The results reveal asymmetrical compressive and tensile stresses on the tooth flanks due to axially downward material flow, leading to increased tensile stress at the contact point of the left tooth flank. Additionally, the influence of friction on ejection force and component deformation is examined, showing that higher friction values result in increased ejection forces and greater deformation. In contrast, varying the degree of die filling up to 80% has only a minor effect on deformation during ejection. The study concludes with recommendations for process optimization and highlights the need for further research, particularly experimental validation, investigation of different gear modules, and improvements in the ejection process