Multi-scale modeling of the thermal workpiece load in the turning process considering the cutting fluid

• Applicants: Professor Dr.-Ing. Thomas Bergs; Professor Dr.-Ing. Reinhold Kneer
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering ; Technical Thermodynamics
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 439919433

The use of cutting fluid is beneficial in the machining technology in order to transport the process heat generated from the tool-workpiece interface and to reduce the frictional heat due to its lubricating effect. The thermo-mechanical load induced in this context has a considerable influence on the surface integrity and the associated functionality of the component. However, the thermal and mechanical load of the workpiece has been modeled separately in previous work. For a comprehensive understanding of the process, the investigation of the interaction between mechanical and thermal phenomena is necessary. Therefore, the main objective of the proposed research project is the multi-scale modeling of the thermal workpiece load in the turning process, considering the supply of cutting fluid and the tool wear condition. In the first funding period, a coupling approach between Computational Fluid Dynamics (CFD) and Finite Element Method (FEM) is developed. The coupling approach is based on the iterative exchange of mechanical and thermal parameters between FEM and CFD. Based on FEM simulations and experiments, the chip geometry is calculated and used as the input for CFD mesh generation. In the CFD simulation, the heat transfer coefficients are then quantified and transferred to the FEM simulation, which then calculates the modified chip geometry. In addition, further sub-models are developed and validated for the description of the friction behavior as well as the contact heat transfer under consideration of cutting fluid. Overall, this iterative coupling approach can be used to determine the temperature distribution and gradients in the boundary layer of complex components during machining. By enhancing the FEM chip formation simulation to the actual tribological conditions considering friction and heat transfer models, a major scientific gap in modeling approaches is closed, and thus a comprehensive virtual image of the machining process under real conditions can be achieved.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2231: Efficient cooling, lubrication and transportation – coupled mechanical and fluid-dynamical simulation methods for efficient production processes (FLUSIMPRO)