Browsing by Author "Baumann, Andreas"

Now showing 1 - 4 of 4

Open Access
Geometry modifications of single-lip drills to improve cutting fluid flow
(2022) Baumann, Andreas; Oezkaya, Ekrem; Biermann, Dirk; Eberhard, Peter
For single-lip drills with small diameters, the cutting fluid is supplied through a kidney-shaped cooling channel inside the tool. In addition to reducing friction, the cutting fluid is also important for the dissipation of heat at the cutting edge and for the chip removal. However, in previous investigations of single-lip drills, it was observed that the fluid remains on the back side of the cutting edge, and accordingly, the cutting edge is insufficiently cooled. In this paper, a simulation-based investigation of an introduced additional drainage flute and flank surface modifications is carried out using smoothed particle hydrodynamics as well as computational fluid dynamics. It is determined that the additionally introduced drainages lead to a slightly changed flow situation, but a significant flow behind the cutting edge and into the drainage flute cannot be achieved due to reasons explained in this paper. Accordingly, not even a much larger drainage flute with unwanted side-effect of a decrease tool strength is able to archive a significant improvement of the flow around the cutting edge. Therefore, major changes to the cooling channel, like the use of two separate channels, the modification of their positions, or modified flank surfaces, are necessary in order to achieve an improvement in lubrication of the cutting edge and heat dissipation.
Open Access
Investigation of chip jamming and drill breakage in deep-hole drilling using Smoothed Particle Hydrodynamics
(2024) Baumann, Andreas; Eberhard, Peter
Single-lip deep hole drilling is characterized by a high-quality hole and a high level of productivity achieved. It is performed using high feed rates in a single pass, and, therefore, chips must be removed by the cooling liquid. However, chip jamming is a significant problem when chips wrap around the tool, leading to marks on the borehole wall and an increased drilling torque, potentially causing sudden tool failure. The Smoothed Particle Hydrodynamics method is applied to simulate the challenging fluid flow and elastic bodies. A first approach is developed to model the effects of chip jamming and the possible consequence of drill breakage for a deeper understanding of the process behavior.
Open Access
Investigation of chip jamming in deep-hole drilling
(2023) Baumann, Andreas; Eberhard, Peter
In this paper, we show the recent progress and first insights in modeling chip jamming in the deep-hole drilling process. Chip jamming is a significant problem when chips wrap around the tool, leading to marks on the borehole wall and an increased drilling torque causing sudden tool failure. Recent investigations focused on chip evacuation and fluid distribution along the cutting edge. This work extends the existing models by adding an artificial barrier in the chip flute. This barrier approximates a chip jammed between the drill shaft and the borehole wall. In the first approach, this barrier blocks the complete chip flute but allows fluid to pass, only blocking the chips from their evacuation. In the second approach presented, a non-permeable artificial barrier partially blocks the chip flute. Furthermore, we show the validation of the model and evaluate the assumption of rigid chips for the chip evacuation as they are applied in earlier investigations. Finally, we show the deformation of the chip as it blocks the fluid from its evacuation and the impact on the fluid flow during the process.
Open Access
Modeling and mitigation of vortex formation in ejector deep hole drilling with smoothed particle hydrodynamics
(2024) Baumann, Andreas; Gerken, Julian Frederic; Sollich, Daniel; Rupasinghe, Nuwan; Biermann, Dirk; Eberhard, Peter
Ejector deep hole drilling achieves high-quality boreholes in production processes. High feed rates are applied to ensure a high productivity level, requiring reliable chip removal from the cutting zone for a stable process. Therefore, a constant metalworking fluid flow under high volume flow rates or high pressure is required. Experimental results show a vortex formation at the outer cutting edge. This vortex can lead to delayed chip removal from the cutting zone, and ultimately, it can lead to chip clogging and result in drill breakage due to increased torque. This paper investigates modified drill head designs using the smoothed particle hydrodynamics method. The investigated modifications include various designs of the chip mouth covering. Besides graphical analysis based on flow visualizations, flow meters are placed at the tool’s head to evaluate the impact of the modifications on the flow rate and possible increased resistance and relocation of the fluid flow from the outer cutting edge to other parts of the tool. The simulation results for the reference design show the experimentally observed vortex formation, validating the simulation model. By adding the tool’s rotation in the SPH simulation, which is not included in the experiments for observation reasons, the vortex formation is positively influenced. In addition, some designs show promising results to further mitigate the vortex formation while maintaining a sufficient fluid flow around the cutting edges.