Influence of the tool on the stress state in precision cutting

• Applicant: Professorin Dr.-Ing. Verena Kräusel
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 415999781

The aim of the project is a fundamental study on the interaction of modifications of the cutting edge or face geometry of tools for single-stroke shearing and the amount of load on the punch. This investigation will especially deal with the results regarding changes of horizontal and vertical force components concerning the stress state at the moment of tool contact as well as additional radially acting pressure superposition. The radial superposition during the cutting process supports the plastic formation and the improvement of the cutting surface quality of the on the one hand, but leads also to an increase of the stress state within the punch on the other. In the project this disadvantage should be compensated by variation of the face geometry. The findings will be used to derive optimised punch geometries with regard to internal stress distribution. Further findings are expected regarding the optimum of necessary loads on the active tool parts under stress by an additional radial pre-load and the highest achievable qualities of the cut surface at the components. This combination of face and radial compressive stress and their effect on the tool load is only achievable by numerical simulation. The simulation will play a major role in the project. Preliminary studies have shown that, for example, a convex shape on the punch face form leads to a reduction in axial and radial stress in components, in comparison to the planar punch geometry. Furthermore, a more homogeneous distribution of the stresses over the cross-section of the punch was noted.In the experiments it is planned to cut at first holes with a diameter of 30 mm by using the steel material S500MC with thicknesses between 3 mm and 10 mm. After development and implementation of a cutting tool for conventional shear cutting and precision cutting, with integrated measuring devices, it is planned to vary the punch face geometry, the cutting gap and the magnitude of the pre-load in relation to the yield strength of the test material.The second geometry will be a sqare with a corner radius of 2 mm and with the same length of the cutting line like the hole. This geometry will be examined only via FE simulation. From this geometry the transferability to application specific geometries will be investigated.

• DFG Programme: Research Grants