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

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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.