Characterization and simulation of the fracture behavior of CBN grain types as a function of crystal structure, grain orientation and dressing parameters

磨削过程是众多增值链的末端，对部件的应用行为起着决定性的作用。在磨削过程中，这些部件的边缘区域受到热-机械和材料-冶金应力集体的影响。这决定了组件的边缘区域属性。这些性能取决于磨削过程中砂轮与工件之间的接触条件。因此，磨削工具形貌的变化对载荷集体产生重大影响，从而影响磨削过程的结果。为了预测地形，最近开发了数学通用的磨削工具模型，以一种真实的方式描述了磨削工具体积组成的组件颗粒，结合物和孔隙的空间排列。借助该软件模型，可以在不测量砂轮形貌的情况下实现对砂轮形貌的预测。除此之外，基于软件的模型允许预测砂轮和工件之间的运动接触条件，这决定了应用行为以及加工结果。运动接触比在很大程度上取决于晶粒材料的断裂行为。然而，对商业上高度相关的晶粒材料（如立方氮化硼（CBN））的断裂行为研究不够。因此，本研究项目的目的是建立一个考虑晶粒类型的晶体形状、晶体取向和修整参数的CBN晶粒材料断裂行为表征的解释模型。为此，首先提出了一种定量分析和描述CBN晶粒材料断裂行为的方法。此外，还研究了CBN晶粒材料在单晶修整过程中的断裂机制与晶体形状和修整参数的关系。基于实验研究结果，对CBN晶粒修整过程中的应力进行了数值模拟，并将研究结果转化为现有的基于软件的刀具形貌模拟模型。在未来，根据所使用的磨削工具的规格，将使用经验结果和模拟结果来模拟磨削过程。这提供了通过模拟替代成本密集的经验系列实验的潜力，从而确定所得到的与颗粒破碎相关的砂轮形貌对作为砂轮体积组成和修整过程的函数的过程行为的影响。

The grinding process is at the end of a multitude of value-added chains and contributes decisively to the application behavior of components. During the grinding process, the edge zone of these components is influenced by a thermo-mechanical and material-metallurgical stress collective. This determines the components edge zone properties. These properties depend on the contact conditions between the grinding wheel and the workpiece acting in the grinding process. A change in the grinding tools topography therefore has a significant influence on the load collective and thus on the grinding process result. In order to predict topographies, recently developed mathematical-generic grinding tool models exist that depict the spatial arrangement of the components grains, binding and pores in a realistic manner as a function of the volumetric composition of a grinding tool. With the aid of this software-based model, grinding wheel topography will be predicted in the future without having to measure the grinding wheel topographies. Out of this, software-based models allow a prediction of the kinematic contact conditions between the grinding wheel and the workpiece, which determine the application behavior as well as the process result. The kinematic contact ratios depend to a large extent on the used breaking behavior of the grain material. However, the fracture behavior of commercially highly relevant grain materials, such as the cubic boron nitride (CBN), is investigated insufficiently.Therefore, the aim of the present research project is an explanation model for the characterization of the fracture behavior of CBN grain materials taking into account the crystal shape of the grain type, the crystal orientation and the dressing parameters.To this end, a method for the quantitative analysis and description of the fracture behavior of CBN grain materials is developed first. Furthermore, the fracture mechanisms of CBN grain materials are investigated in a single-grain dressing process as a function of the crystal shape and the dressing parameters. Based on the findings of the empirical investigations, a numerical modeling of the stresses during the dressing process in CBN grains is carried out and a transfer of the findings to the existing software-based models for the simulation of the grinding tool topography is done. In the future the empirical findings and simulation results are used to simulate grinding processes depending on the specification of the used grinding tool. This offers the potential to substitute cost-intensive empirical series of experiments by simulations, and thus to determine the effects of the resulting grain-breakage-dependent grinding wheel topography on the process behavior as a function of the volumetric composition of the grinding wheel and the dressing process.