Tool Wear Prediction in Broaching Based on Tool Geometry

Abstract

The aircraft engine is a safety-critical part of an aircraft. Constructive modifications resulting in ecological and economic improvements of the engine lead to necessary changes in manufacturing processes. The turbine disks in the low-pressure section are made of temperature resistant nickel-based superalloys. For the connection of the turbine blades with the disk, fir-tree slots are machined by broaching. The broaching process achieves high geometrical accuracy as well as process reliable rim zone properties. Alternative manufacturing processes such as milling or wire electrical discharge machining are still the subject of research in many applications and do not yet achieve the required process reliability. Especially in finishing operations, tool geometry is complex. In previous research work, the local rake angle and, as a result, the acting cutting force were determined analytically and empirically. Based on these results, the relationship between tool geometry, cutting force, and tool wear will be investigated in this work to enable a cutting length dependent prediction of tool wear. The aim of this work is a model-based prediction of tool wear for a given cutting length and a previously unknown tool geometry. For this purpose, a method was developed to predict tool wear using empirical test data and internal machine data. With these results, it is not only possible to identify critical points on newly developed broaching tools by maxima of the cutting force but also to predict wear locally, depending on the cutting length. Thus, tools can be optimized, and efficiency of the broaching process is increased.