Project Details
Projekt
Simulation and optimization of the coolant flow to reduce the thermal tool load during discontinuous drilling of Inconel 718
Subject Area
Metal-Cutting and Abrasive Manufacturing Engineering
Term
since 2020
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 439920593
Drilling of the difficult-to-machine nickel-base alloy Inconel 718 is associated with high thermomechanical tool and workpiece loads, which result in reduced tool life and affected microstructure. The optimisation of the cooling lubricant supply is a central scientific research approach to counteract the described process characteristics. In this context, machining with twist drills is being adapted to a discontinuous process strategy, which represents a potentially efficiency-increasing further development. By implementing a brief retraction movement against the feed direction, chip formation is interrupted and the cutting edges are rewetted with cooling lubricant, which allows the fluid to flow freely around the cutting edges and cools them down. The first exemplary applications of the innovative drilling process have demonstrated a reduction in wear phenomena on the tool flank as well as positive effects on the edge zone integrity of the bore holes. Through the simultaneous generation of input variables, the development of the FEM chip formation simulation could be initiated and the CFD flow simulation for the drilling process elaborated, so that detailed insights into the flow-mechanical processes within the closed chip formation zone of the process are enabled. The simulated flows at the bottom of the bore hole were successfully validated via experimental high-speed analysis.The central objective of the second funding phase is derived from this preliminary work, namely to complete the development of a simulation model that enables a realistic and complete mapping of the bidirectional heat transfer and can thus calculate precise temperatures at the cutting edge, taking chip formation and coolant flow into account. The quality of this simulation is to be further increased by incorporating experimentally developed material parameters of the nickel-based alloy and an experimental friction characterisation, and is also to benefit from increases in the complexity of the CFD simulation environment. This approach enables the development of a discontinuous process strategy, which is accompanied by reduced thermomechanical tool and workpiece loads and can thus be applied under increased cutting parameters. Thus, in addition to increased component properties, increased productivity can also be achieved. Finally, the developed simulation model is used to make flow-optimised adjustments to the tool design and to identify application-specific cutting materials and coatings by simulation.
DFG Programme
Priority Programmes
