Experimental Investigation of Chatter Dynamics in Thin-walled Tubular Parts Turning

Abstract

Chatter prediction is nowadays frequently carried out for machining operations involving deformable parts or tools. These analyses are commonly based on the uncoupled elements of the system: frequency response of the deformable parts under non-rotating conditions and cutting law. The present investigation puts forward the dynamics of a thin-walled tubular part during straight axial turning undergoing chatter instability. Studied system’s peculiarities include quasi-static nominal cutting conditions and twin flexural modes featuring strong variation of modal characteristics along the pass. The measurement records, based mainly on fixed-frame non-contact eddy-current displacement probes, are performed during the machining operation. Additional hammer modal analysis tests are also carried out. As can be observed from time and spectral analysis of the records, the system's response features several characteristic phenomena as, for example, twin mode separation. The influence of different factors, such as the additional stiffness due to the tool presence, gyroscopic effects and the fixed sensors measurement on rotating part is investigated.