Machining Process for a Thin-Walled Workpiece Using On-Machine Measurement of the Workpiece Compliance

摘要

Demand for highly productive machining of thin-walled workpieces has been growing in the aerospace industry. Workpiece vibration is a critical issue that could limit the productivity of such machining pro-cesses. This study proposes a machining process for thin-walled workpieces that aims to reduce the workpiece vibration during the machining process. The workpiece compliance is measured using an on-machine measurement system to obtain the cutting conditions and utilize the same for suppressing the vi-bration. The on-machine measurement system con-sists of a shaker with a force sensor attached on the machine tool spindle, and an excitation control sys-tem which is incorporated within the machine tool's numerical control (NC). A separate sensor to obtain the workpiece displacement is not required for the es-timation of the displacement. The system is also ca-pable of automatic measurement at various measure-ment points because the NC controls the positioning and the preloading of the shaker. The amplitude of the workpiece vibration is simulated using the measured compliance to obtain the cutting conditions for sup-pressing the vibration. An end milling experiment was conducted to verify the validity of the proposed pro-cess. The simulations with the compliance measure-ment using the developed system were compared to the results of a conventional impact test. The comparison showed that the spindle rotation speed for suppressing the vibration could be successfully determined; but, the axial depth of cut was difficult to be determined because the simulated vibration amplitude was larger than that found in the experimental result. However, this can be achieved if the amplitude is calibrated by one machining trial.