Analysis of internal material loads and resulting modifications for grinding with mechanical main impact

Abstract

Mechanical impact in grinding processes can improve the properties of the workpiece surface and subsurface layer and therefore have a positive effect on the functional performance of the finished component. Although changes in the surface integrity in grinding are mostly temperature-induced, the present work implies that for grinding with flattened coarse grains the mechanical strains can be dominant. By conducting experiments with differently dressed coarse grained grinding wheels, the influence of the grain size and the cutting speed on mechanically induced material modifications could be confirmed. Furthermore, to systematically adjust the material modifications in the workpiece surface layer within the process, these findings were used to get a more detailed understanding of the mechanical modification mechanisms. A finite element approach for the mechanical impact of a single flattened grain is proposed, where the contact with the workpiece is modelled as a moving normal and tangential pressure source, calibrated by measured process forces. With the internal material loads, calculated in the presented modelling concept, a correlation between the local strains and local residual stresses can be shown. According to the experiments, the simulations indicate a positive effect on the mechanical impact, e.g. for lower cutting speeds.