Cutting edge preparation of ultra-hard cutting materials

刀具的性能在很大程度上取决于刀具刃口的微观几何形状。为了生产特定的尖端微细几何图形，工业上大多采用机械加工。对于聚晶金刚石(PCD)和聚晶立方氮化硼(PCBN)等超硬切削材料，这些机械加工在生产率、磨损和相关工艺可靠性方面日益达到极限。出于这个原因，在DFG项目“Schneidkantensikropräparation hochharter Schneidstoffe”的范围内，正在研究激光烧蚀在PCBN刀具上生成尖端微几何形状的适宜性。该项目的范围是了解激光能量输入引起的切割材料性能随工艺参数以及切割材料成分(PCBN含量和粘结剂)的变化，并为生产对称和不对称的刀具微观几何图形制定适当的工艺策略。在正在进行的工作过程中已经证明，激光加工对切割材料的性能(表面质量、化学成分、硬度、残余应力)有很大影响。初步研究结果还表明，刀具的切割性能在很大程度上受到激光加工引起的切割材料性能变化的影响。拟议延续项目的目的是了解PCBN工具的激光加工对其操作行为的影响。首先，采用实验和模拟相结合的方法，确定了圆角PCBN刀具切削楔内的机械应力。这为评价激光刃口微加工对PCBN刀具承载能力和耐磨性的影响提供了依据。特别是，在不同的应用中，对刀具的初始失效(刀刃破裂)和连续磨损形式(后刀面磨损、凹坑磨损)的机理进行了实验研究。本研究的目的是将产生的磨损机制与激光加工引起的刀具性能联系起来。最后，通过采用优化调整的激光加工策略进行激光制备，证明了PCBN刀具性能的提高。

The performance of cutting tools is largely determined by the cutting edge microgeometry. For the production of specific cutting edge microgeometries, mechanical processes are mostly used in industry. Regarding super hard cutting materials such as polycrystalline diamond (PCD) and polycrystalline cubic boron nitride (PCBN), these mechanical processes increasingly reach their limits with regard to productivity, occurring wear and the associated process reliability. For this reason, within the scope of the DFG project "Schneidkantenmikropräparation hochharter Schneidstoffe", laser ablation is being investigated concerning the suitability for the generation of cutting edge micro-geometries on PCBN tools. The scope of the project is to understand the changes in the properties of the cutting material induced by the laser energy input in dependence of the process parameters as well as the cutting material composition (PCBN content and binder) and to derive suitable process strategies for producing symmetrical and asymmetrical cutting edge microgeometries. It has already been proven in the course of the ongoing work that the cutting material properties (surface quality, chemical composition, hardness, residual stress) are significantly influenced by the laser process. Initial findings also show that the tool cutting performance is largely influenced by the changes in the properties of the cutting material resulting from the laser process. The aim of the proposed continuation project is the knowledge of the influence of laser processing of PCBN tools on their operational behavior. First, the mechanical stresses in the cutting wedge of rounded PCBN tools are determined by a combined approach of experiment and simulation. This serves as a basis for evaluating the impact of laser cutting edge micro-preparation on the load capacity and wear resistance of PCBN tools. In particular, mechanisms of initial tool failure (cutting edge breakouts) and continuous wear forms (flank wear, crater wear) are experimentally investigated in various applications. The aim of this research is to link the resulting wear mechanism to the cutting tool properties induced by laser machining. Finally, the performance increase of PCBN tools is demonstrated by laser preparation using optimally adjusted laser process strategies.