Development of a simulative model for analysis of the effect of cooling lubricants in deep hole drilling with small diameters with respect to chip formation

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In the previous DFG project, a fluid-structure interaction (FSI) simulation model was developed to analyze the influence of the cooling lubricant during spiral deep hole drilling. It was possible, to model the interaction between tool, workpiece and chip formation by coupling the Finite Element (FE) and Computational Fluid Dynamics (CFD) simulation. Instead of water, deep hole drilling oil with a specified, temperature dependent kinematic center viscosity was used for the first time in the CFD simulation. However, the temperature changes that occur during the machin-ing process depending on the material to be machined and the machining time were not taken into account for the viscosity of the oil in the CFD simulation of the coolant flow. In order to apply the FSI simulation model to optimize tools and processes, it is necessary to consider in detail the cool-ing lubricant viscous properties, which are strongly dependent on temperature and pressure. The objective in the focus of this follow-up project is therefore to extend the existing FSI simulation model accordingly, in order to include the changing properties of the coolant due to pressure and temperature changes in the machining process. Using mathematical equations, the dynamic cool-ing lubricant properties, can be defined and implemented by corresponding variables in the FSI simulation model. Deep hole drilling experiments using spiral deep hole drills and the workpiece ma-terial Ti-6Al-4V provide the input data for the simulation. After determining the tool temperature with the simulation for different feeds and cutting speeds, a numerical calculation of the fluid flow at dif-ferent cooling lubricant pressures is performed. The aim is to maximize the coolant flow velocity and the coolant flow pressure in order to provide a better coolant supply in the cutting edge area. With these simulatively determined parameter combinations, experimental tool life investigations will be carried out to determine the influence of the improved coolant supply on tool wear.