complementary machining - simulation based analysis of a mechanical surface treatment integrated in a machining process for the intended formation of nanocrystalline surface layers

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The aim of the research project is the application of the process strategy Complementary Machining on the technically relevant production process turning. Rotationally symmetric components like shafts made of the quenched and tempered steel AISI 4140 (42CrMo4) often represent highly stressed components whose surfaces are treated in a further process step after machining in order to ensure the desired properties. Component characteristics like the topography to optimize the tribological behavior or the service life of the parts are technically relevant target values. The component characteristics are usually achieved by expensive post production processes like deep rolling or hammer peening. With Complementary Machining the surface treatment is proceeded after machining without changing tools, by reversing the cutting direction and treating the surface of the component with the machining tool. Due to an extremely negative rake angle plastic deformation in the surface layer of the component is induced. In this way surface hardening as well as changes in microstructure can be achieved.Applying the process strategy Complementary Machining on the technically relevant production process turning leads to significantly more complex contact conditions. Thereof new challenges in terms of tool geometry and the demand for a robust process control result.Due to a suitable micro- and macroscopic design of cutting edges and an adaptable tool holder contact conditions are to be optimized since component conditions can be specifically adjusted and tool wear can be reduced to an economically acceptable level. For this purpose investigations of the tool material (WC-Co) with different grain sizes are planned. In order to increase tool life and precisely control component conditions in the surface layer the influence of cryogenically cooled Complementary Machining is to be analyzed. Using cryogenic cooling the potential of strain hardening is supposed to be significantly improved. Based on these findings a process guideline for producing shafts made of the quenched and tempered steel AISI 4140 (42CrMo4) will be derived.The planned investigations are intended to make significant contributions to a better understanding of interactions between the micro- and macroscopic design of cutting edges, their microstructure and component conditions that are achieved with Complementary Machining. Based on these findings considering a process with an ideal cryogenic cooling system the industrial relevance of Complementary Machining is to be demonstrated.