Load-optimised design of cutting edge microgeometries for industrial processes
Final Report Abstract
The application behavior of cutting tools is significantly influenced by the cutting edge microgeometry and adapting this offers considerable potential for increasing productivity and process reliability. For this purpose, it is essential to adapt the cutting edge micro-geometry to the material to be machined and the existing loads during use. The transfer of basic knowledge to the application of internal longitudinal turning and kinematically identical boring offers considerable potential for increasing tool performance through the use of load-optimised cutting edge microgeometries. For a broad industrial coverage, knowledge of the relevant influencing variables (e.g. brushing time tB, depth of cut aB and brushing angle φB) on the brushing process for cutting edge microgeometry was first determined. Based on this, a design model for the preparation of the cutting edge micro-geometry by means of brush cutting was subsequently developed and tested. The availability of an extended understanding of the brushing process enables the efficient and flexible production of any cutting edge micro-geometries. Furthermore, the load limits of the coating-substrate systems were analyzed for coatings for indexable inserts. The mechanical loads in the cutting wedge were determined as a function of the process parameters during machining by means of in-situ force measurements on the planing test rig. From this, the failure-relevant tangential stresses in the cutting wedge and the limit shear stress τα,grenz = 320 MPa, which lead to micro-chipping of the cutting edge, can be determined. In combination with the knowledge gained regarding the thermal loads on the cutting wedge during internal turning, a simulation model of the loads in the cutting wedge was developed. Thanks to the exact knowledge of the thermo-mechanical load collective during internal turning and the newly developed model for the targeted adjustment of the cutting edge micro-geometry by means of brush chipping, the tools can now be optimally designed. Further investigations under near-industrial operating conditions demonstrated the positive effect of the load-optimised design of the cutting edge microgeometries on both the failure criterion of the indexable inserts (chipping on the cutting edge) and the wear behaviour. Increases in tool life and a significant reduction in cutting edge chipping were determined across all materials and processes. Nevertheless, there is a need for further research into chip breaking behavior during internal turning, as this can lead to stochastically occurring load peaks in the case of long-chipping materials and long tool path lengths and therefore tool engagement times. This is due to the limited space available during internal turning and the resulting challenges when removing the chips. The accumulation of chips in the cutting zone can damage the coating of the tools and lead to spontaneous chipping of the cutting edges.
Publications
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Produktivitätssteigerung durch belastungsoptimierte Schneidkantenmikrogeometrien. VDI-Z, Band 164 (2022), Nr. 6, 24-26
Denkena, B.; Bergmann, B. & Kraeft, M.
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Modeling of stresses at the cutting wedge in the interrupted cut for the design of the cutting edge microgeometry. Procedia CIRP, 117, 299-304.
Denkena, Berend; Bergmann, Benjamin; Picker, Tobias & Kraeft, Malte
