Tool and Process Optimization for efficient Ejector Deep-Hole Drilling-Processes using Smoothed Particle Hydrodynamics (SPH)

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Ejector deep hole drilling allows to exploit the process-typical advantages of deep hole drilling, such as high metal removal rates as well as low straightness deviations, on conventional machining centers for industrial applications at relatively low cost, because no expensive special machines with complex sealing for the cooling lubricant supply are required for the process. Another advantages of ejector deep hole drilling lie in the excellent surface qualities and bore quality that can be achieved compared to conventional drilling methods. The guide pads on the drill head generate a smoothing of the roughness peaks on the bore surface by plastic deformation of the bore wall, so that typically no reworking of the bores, e.g. by reaming, is required. In addition, the removal of chips through the inner tube of the tool prevents damage to the bore wall produced. Ejector deep hole drilling offers great potential for making the use of cooling lubricant (coolant) more energy- and resource-efficient with regard to the main functions of cooling, lubricating, and transporting chips, thus contributing to an increase in efficiency and a shortening of the process chain in production. In the first stage of the research project, the grid-free simulation approach of Smoothed Particle Hydrodynamics (SPH) in combination with current experimental and measurement analysis methods was used to develop an in-depth understanding of the interactions of the flow conditions and to implement it in a physical simulation model. The results of the successful interdisciplinary collaboration of the research institutes have already been published in various scientific publications. An essential goal of the second phase of this project is to extend the simulation model by a parallel Incompressible Smoothed Particle Hydrodynamics (ISPH) algorithm in order to realize a coupling with the thermal tool and workpiece loads. With the aid of the simulation model and a static load analysis based on the tool load determined experimentally during the drilling process, the design of the drill head is adapted to allow an improved coolant supply to the cutting edge and the occurrence of the ejector effect at lower coolant volume flows, as well as to improve chip removal. Finally, the flow-optimized ejector tools are additively manufactured and used.