Restriction of the chip thickness deviations for stabilizing the chip formation of high strength metals

• Applicant: Professor Dr.-Ing. Dirk Biermann
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 421463266

In the previous DFG project entitled: "Restriction of the chip thickness deviations for stabilizing the chip formation of high strength metals", the fundamental research of the constraint principle for suppression of segmented chip formation was the focus of the work. Within the framework of this, a limitation of the chip thickness deviations could be achieved in principle, but the high mechanical loads as well as varying chip thicknesses of the segments led to a partly complete suppression of the chip segmentation. In order to deal with this problem and at the same time to reduce the experimental effort, one of the aims of this project is to considerably deepen the fundamental knowledge gained in the first project on the simulative design and experimental implementation of a constraint and then to further develop it in the direction of practical applicability. In this context, the research results of the initial project have shown that there is a need for research and development in the area of damage modelling in the simulation of free segmented chip formation of titianium alloy Ti6Al4V in order to improve the prediction of the mechanical tool loads and the chip morphology. This is necessary in order to simulate the filigree process of restricted chip formation by using a constraint that is always dependent on the specific application. The planned analyses of material damage also contribute to further research into the mechanisms of segmented chip formation. The subsequent parameterisation of a suitable damage model is intended to improve the prediction accuracy of the chip morphology and the mechanical tool load. The 2D FEM chip formation simulation will be validated on the basis of the experimental results of the initial. In addition, if the segmentation was successfully suppressed, there was no chip breakage in the resulting chip. Therefore, an analysis of the chip flow during the free chip formation as well as a targeted chip guidance through the alignment of the tool and the use of a constraint is subsequently carried out on the basis of 3D FEM chip formation simulations using the improved material model. By influencing the chip flow direction, it is possible to guide the chip specifically against interfering contours, so that the bending load in the chip increases and tertiary chip breakage begins. The results of the simulation will be validated within the scope of the planned transfer to a turning process in which the tool engagement time is considerably longer. Finally, a transferability to the steel material 51CrV4 will be examined, as this also tends to segmented chip formation.

• DFG Programme: Research Grants