Machining of thin blade using vibration prediction and continuous spindle speed control

Abstract

The paper focuses on the issue of controlling the cutting conditions in finishing machining of compliant workpieces, such as typically thin blades, in order to eliminate undesirable vibration and achieve high quality machined surfaces while also increasing productivity in machining processes. Workpiece vibration along the toolpath results from excitation of the workpiece by cutting forces. A strategy of calculating the overall level of workpiece vibration excited by cutting forces at different spindle speed levels as a multifrequency problem was proposed for specific use with long thin blades. The proposed strategy allows for very efficient identification of blade sections with critical increase of vibration level at different spindle speed values. This enables determination of the optimized spindle speed levels and feed rate along the blade to avoid increased workpiece vibration. A method for continuous control of the spindle speed and feed rate during finishing machining was proposed and successfully tested and verified through real machining tests. The machined surface quality improvement was proven.