Numerical multiscale modelling and optimization of cooling concepts in gear skiving

• Applicants: Professor Dr.-Ing. Hans-Jörg Bauer; Professor Dr. Michael Moseler; Professor Dr.-Ing. Volker Schulze
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering ; Fluid Mechanics ; Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 439954775

The aim of the project is to model the cooling lubrication and chip formation in the kinematically complex and difficult-to-access machining process of gear skiving. In gear skiving, the machining conditions vary along the cutting edge and during machining. This results in chips consisting of multiple parts that repeatedly disrupt the process by sticking to the workpiece and tool surfaces or getting caught between the workpiece and the flank face. This results in effects such as chip jamming, which leads to surface defects and tool wear. Only by modeling chip formation under the influence of the cooling lubricant is it possible to understand chip jamming. The dominant factors for chip formation are the process parameters and the cooling lubricant effect between the chip and the cutting edge. In practice, the cooling lubricant supply is optimized iteratively and based on experience. A model-based process optimization requires the consideration of the cooling lubricant supply and distribution as well as the representation of the influences on the friction conditions between the chip and chip surface and the effects on chip formation and chip flow. The entire process is too complex to be represented in a single model. Therefore, a simulation is to be developed in which a fluid flow model is coupled with a chip formation model and a friction model. The aim of the third funding phase is to use the coupled simulation methods developed for gear skiving with compressed air and oil flooding for the process and flooding effect. The process under consideration is to be optimized across scales in the sub-areas of tribology, chip formation and fluid dynamics, considering the complex mechanisms that lead to chip jamming. Chip formation is modeled using FEM simulation. The cooling lubricant concept is modeled using the SPH method. The effect of the fluid in the process is considered by molecular dynamic simulations. Based on the generated understanding of chip jamming, suitable cooling lubricant strategies are to be developed in the first step of the project, considering the main mechanisms of the investigated scales. Subsequently, the process kinematics are to be optimized with regard to chip formation, considering pre-wetting and the contact line, in order to ensure longer tool life and the avoidance of 2nd order chip jamming. Finally, the effectiveness of the changes will be verified by means of tests.

• 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)
• Co-Investigator: Dr.-Ing. Corina Schwitzke