Abstract
Hollow blades with honeycomb structures are increasingly used in the turbine engines for reducing weight and saving costs. The hollow blade is a typical thin-walled structural part with low stiffness, the machining system of which is often unstable and likely to chatter. The most effective solution to avoid the machining chatter is to guide the hollow blade to be machined in a stable machining zone. This paper proposes a measurement-based approach for modal analysis and stability prediction of turn-milling hollow blade. The impact test was carried out to achieve the FRF curves on the hollow blade and the milling tool. An extremum method was employed to obtain an equivalent FRF curve, from which the modal parameters involving the natural frequency, damping ratio, and stiffness were computed. Afterwards, the semidiscretization method was used to draw a stability lobe diagram to predict the stability when turn-milling hollow blades. The experimental results confirm the feasibility of the predicted stability lobe diagram.
Highlights
Hollow blades with honeycomb structures (HCSs) are increasingly employed in the advanced turbine engines for lightweight and cost saving [1,2,3]
The hollow blade with HCSs is often made of difficult-to-manufacturing titanium alloy, large cutting forces of which would intensify the vibration of the machining system
Self-excited vibration is well-known as the machining chatter, which is majorly caused by the unstable machining process. e machining chatter always results in some undesirable consequences such as poor surface finish and increased levels of tool wear [6,7,8,9]. e chatter occurring in the processing of the turbine blades with HCSs can even deteriorate the performance and life of the turbine engines
Summary
Hollow blades with honeycomb structures (HCSs) are increasingly employed in the advanced turbine engines for lightweight and cost saving [1,2,3]. Sun and Altintas [15] and Song et al [16] build FRF of the cutting tool by impact test and identified the modal parameters using the fitting method. Us, the computed modal parameters from the fitting FRF curve are incorrect which would result in a poor prediction of the machining system. For the purpose of improving the system stability and avoiding the chatter in machining hollow blade with HCSs, this paper proposes a measurement-based approach for modal analysis and stability prediction of turn-milling hollow blade with HCSs. e impact test is carried out to achieve the FRF curves on the hollow blade and the cutting tool. An extremum method was employed to obtain an equivalent FRF curve, from which the modal parameters involving the natural frequency, damping ratio, and stiffness were computed.
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