Consideration of functionally relevant geometric deviations in the design of metal forming processes for the production of gears by extrusion

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The overall objective of the research group is to achieve an integrated, process-oriented tolerance management. Within this framework, it is necessary to consider not only the process-related causes for geometric component deviations, when assigning tolerances, but also the deviations resulting from operation. The aim of the proposed subproject is to identify influencing variables on the operational behaviour of cold-forged gears in the metal-plastic material pairing and to derive functional correlations between the process-related component properties and the resulting wear behaviour. Based on this, an operationally optimized design of the extrusion process for the production of ready-to-use gears is to be carried out in order so ensure compliance with the function-relevant tolerances over the lifetime.The knowledge gained in the first funding period forms an essential basis for the planned work. In the first funding period the influence of process-related control levers as well as process variations on the geometric and mechanical properties of cold-forged steel gears were determined. In the second funding period, the effects of the component properties of extruded gears on geometric deviations due to the characteristic wear behaviour of the metal-plastic material pairing in operation will be investigated. Based on the derived data, the subproject partners create metamodels to describe the wear behaviour and apply them for tolerance analysis. The occurring tooth wear limits the compliance with the function-relevant tolerances as well as the lifetime of the pairing. Preliminary investigations of the first phase show that a targeted influence of the application-relevant component properties in the extrusion process has the potential to significantly improve the operating behaviour of the pairing.With the achievement of the objective of the subproject, the research association disposes of decisive findings for process-oriented tolerance allocation. The knowledge of functional correlations between the production-related component properties and the operational behaviour enables a more efficient product and process design. In addition, the process-oriented tolerance optimization of the gear supports both the design and the measurement technology in the definition of the respective requirements. In cooperation with the other subprojects, this contributes to reduce development and evaluation costs and shorten product launch times.