Analysis of material removal mechanisms in grinding of super hard cutting materials regarding polycrystalline cubic boron nitride (PCBN)

点击翻译按钮获取中文摘要

Grinding plays a key role in the process chain of manufacturing indexable inserts made of polycrystalline boron nitride PCBN. Optimizing the grinding process thus offers great potential for increasing the efficiency of PCBN cutting tool production. The influences of the grinding parameters on the grinding ratio and on the process result variables cutting edge roughness and surface roughness of the flank and rake faces depending on the PCBN specification have been extensively investigated. Furthermore, description models exist for the grinding wheel wear and material removal mechanisms. However, the explanation of the underlying cause-effect relationships between thermal and mechanical process loads and the material removal and grinding wheel wear mechanisms is not state of the art. The aim of this research project is therefore to establish an explanatory model for the material removal and grinding wheel wear mechanisms in grinding of different PCBN-specifications. Basing on friction tests according to the pin-on-disk principle an empirical analytical friction model is derived to predict the thermal and mechanical loads in the contact zone between a single diamond grain and a PCBN workpiece. This model will then be extended to a grinding process by means of grinding experiments. A finite element simulation based on this model allows the prediction of microscopic thermal and mechanical loads at the contact zones between individual abrasive grains and the PCBN external zone. Finally, the external zones of ground PCBN workpieces are examined by transmission electron microscopy and the grinding wheel topography is analyzed by laser scanning microscopy and an explanatory model for the material removal and grinding wheel wear mechanisms as a function of the thermal and mechanical loads is derived.