Modelling of the coolant lubrication distribution during single-lip deep hole drilling under consideration of the chip transport by means of CFD and SPH/DEM simulations for tool and process optimization

在DFG项目成功的第一阶段继续：“利用CFD和SPH/DEM模拟工具和工艺优化的方法，在考虑切屑传输的情况下，对单唇深孔钻削过程中的冷却剂润滑分布进行建模”，重点将放在进一步优化单唇钻头和扩展所开发的模拟模型上。在第一阶段，冷却通道的几何形状对瞬时切屑去除有显著影响，这产生了基本的优化潜力。由于微型单唇钻头体积小，改装的可能性有限，因此在第二阶段考虑改装直径较大、有两个冷却通道的单唇钻头。基于开发的SPH/DEM/CFD模拟方法，将对内冷却通道的横截面面积和位置、插入排水槽和改善油室间隙角进行几何优化。对仿真模型进行扩展，考虑了瞬时切屑去除过程中的摩擦条件。在单唇钻头的情况下，在不受干扰的情况下，切屑随冷却润滑剂沿着切屑槽流出钻孔，而不会与钻头和井壁有主要接触。然而，如果切屑与井壁反复发生碰撞，则案例摩阻模型起着重要作用。此外，灵活的切屑建模将提高模拟质量，以便对这些非最佳条件下的切屑运输有新的见解，在最坏的情况下，这可能会导致钻头堵塞。

In the continuation of the successful first phase of the DFG project entitled: "Modelling of the coolant lubrication distribution during single-lip deep hole drilling under consideration of the chip transport by means of CFD and SPH/DEM simulations for tool and process optimization", the focus will be on further optimization of the single-lip drill and extensions to the developed simulation model. In the first phase, it was shown that the geometry of the cooling channel has a significant influence on the transient chip removal and that this yields a fundamental potential for optimization. Since the possibilities to modify a micro single-lip drill are limited due to its small size, a single-lip drill with a larger diameter and two cooling channels is considered instead in the second phase. Based on the developed SPH/DEM/CFD modelling approach, a geometric optimization of the cross-sectional area and the position of the internal cooling channels, the insertion of a drainage groove and the improvement of the oil chamber clearance angle will be carried out. Extending the simulation model, the friction conditions during transient chip removal are to be taken into account. In the case of the single-lip drill, the chips flow out of the bore hole with the cooling lubricant along the chip groove under undisturbed conditions without major contact with the drill and the borehole wall. However, if repeated collisions of the chips with the borehole wall occur, case friction modelling plays an important role. Furthermore, flexible modelling of the chips will improve the simulation quality in order to gain new insights into chip transport under these non-optimal conditions, which in the worst case can lead to a jamming of the drill.