In situ strain measurement in the chip formation zone during orthogonal cutting

The in situ strain measurements during orthogonal cutting were performed to get information about the local stress state in the chip formation zone. These results will be used to verify and extend existing chip formation models. Until now the existing chip formation models, e.g. [1-3] are relying on a number of restricting preconditions, because the strain and stress fields in the chip formation zone during chip formation are extremely difficult to measure. However, the development of very brilliant synchrotron light sources like PETRA III provides the opportunity to get this information by means of 2D diffraction. First results of in situ cutting experiments at DORIS III are presented in [4]. During first in situ measurements at the HEMS beamline/PETRA III in August 2011, the measuring field could be reduced from 100μm x 100μm to 20μm x 20μm due to the high photon flux of PETRA III. This high local resolution is necessary in order to resolve the steep stress gradients around the cutting edge. For a complete understanding of the chip formation behaviour the experiments were conducted with C45E samples with bcc structure as well as Aluminium samples with fcc structure, because the different structure results in different deformation mechanisms and hardening behaviour and hence a different chip formation. This time, cutting experiments on the two phase brass alloy CuZn40 were performed to transfer the developed cutting mechanisms on multiphase materials, whereby industrial relevant materials usually are multi-phase. The stress distribution on the α-phase (fcc-structure) and on the β-phase (bcc-structure) and therewith their deformation behaviour during cutting will be analyzed. The central task of cutting research is the investigation of the chip formation process and its correlation with influencing parameters such as the tool geometry, the material and the cutting conditions.