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

磨削在多晶氮化硼PCBN可转位刀片制造工艺链中起着关键作用。因此，优化磨削工艺为提高PCBN刀具的生产效率提供了巨大的潜力。研究了磨削参数对磨削比的影响，以及PCBN规格对后刀面和前刀面的刃口粗糙度和表面粗糙度的影响。此外，还建立了砂轮磨损和材料去除机理的描述模型。然而，对热和机械加工负荷与材料去除和砂轮磨损机制之间的潜在因果关系的解释并不是最先进的。因此，本研究项目的目的是建立不同规格PCBN磨削过程中材料去除和砂轮磨损机理的解释模型。在摩擦试验的基础上，根据销-盘原理，建立了一个经验分析摩擦模型，用于预测单个金刚石颗粒与PCBN工件接触区的热载荷和机械载荷。然后通过磨削实验将该模型推广到磨削过程。基于该模型的有限元模拟可以预测单个磨粒与PCBN外区接触区的微观热载荷和机械载荷。最后，用透射电子显微镜观察了PCBN磨削后的外区，用激光扫描显微镜对砂轮形貌进行了分析，得到了材料去除和砂轮磨损随热载荷和机械载荷变化的解释模型。

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.