Basic research and determination of process limitations in bulk forming processes of microgears from sheet metal

• Applicant: Professorin Dr.-Ing. Marion Merklein
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 421783424

In many industries, there is a trend towards miniaturization of technical systems. This trend is characterized by the minimization of geometrical dimensions with a simultaneous increase in functionality and quality. These products include miniaturized drive systems with toothed micro components. Every year, more than 10 billion toothed components are produced in the module range m < 0.3 mm. In view of the increasing demand for micro gears, research into efficient manufacturing processes that enable the economical and precise production of metal micro gears is necessary. Cold forming processes offer technological as well as economical and environmental advantages compared to other manufacturing processes. However, at the current state of the art, the production of microgears by cold forming processes for modules of m < 0.2 mm is not possible due to high tool stresses, occurring size effects and handling problems. The objective of the second project phase is the fundamental analysis of an extended process chain for the manufacturing of microgears with a module of 0.1 mm. This includes the investigation of functional interactions of single process steps as well as the forming-related properties on the application behavior of the microgears. Based on the findings of the first project phase with regard to the three-stage process chain, the process chain will be extended in the second phase by an additional VFP stage and by the extrusion of a cup as a gear holder. The aim of the process extension by a multi-stage VFP is to identify effects and interactions between the influencing variables punch diameter and penetration depth in order to analyze the effects on the material flow and the homogeneity of the deformation on the basis of the effect mechanism determined in the first phase. The process understanding gained will subsequently be used to adjust required pin properties through targeted material flow control for subsequent forming of the gear holder, as well as to reduce the process forces identified as critical in the first phase. Another sub-objective is to develop a substantial process understanding for multi-stage microforming process chains through the integration of cup forming as well as through the final separation from the sheet metal strip. For this purpose, a suitable forming strategy for the integration of a cup extrusion is developed and interactions between the forming stages are identified, resulting in a fundamental process knowledge. In addition, the forming possibilities of the process chain and the component spectrum will be significantly expanded. A further sub-objective is to evaluate the application behavior of the impact extruded microgears on the basis of the analysis of runnability in a practical laboratory test on a gear test rig. Finally, functional relationships are determined and the findings from both phases are evaluated to derive a process window and develop a detailed understanding of the process.

• DFG Programme: Research Grants