Identification of bearing dynamics under operational conditions for chatter stability prediction in high speed machining operations

2015-10-01
Özşahin, Orkun
Özgüven, Hasan Nevzat
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Chatter is a major problem causing poor surface finish, low material removal rate, machine tool failure, increased tool wear, excessive noise and thus increased cost for machining applications. Chatter vibrations can be avoided using stability diagrams for which tool point frequency response function (FRF) must be determined accurately. During cutting operations, due to gyroscopic moments, centrifugal forces and thermal expansions bearing dynamics change resulting in tool point FRF variations. In addition, gyroscopic moments on spindle holder tool assembly cause separation of modes in tool point FRF into backward and forward modes which will lead to variations in tool point FRF. Therefore, for accurate stability predictions of machining operations, effects of operational conditions on machine tool dynamics should be considered in calculations. In this study, spindle bearing dynamics are identified for various spindle rotational speeds and cutting forces. Then, for a real machining center, tool point FRFs under operating conditions are determined using the identified speed dependent bearing dynamics and the mathematical model proposed. Moreover, effects of gyroscopic moments and bearing dynamics variations on tool point FRF are examined separately. Finally, computationally determined tool point FRFs using revised bearing parameters are verified through chatter tests.
Bearing dynamics identification, Machine tool dynamics, TOOL POINT FRF, SPINDLE, MODEL, SYSTEMS
https://hdl.handle.net/11511/34450
PRECISION ENGINEERING-JOURNAL OF THE INTERNATIONAL SOCIETIES FOR PRECISION ENGINEERING AND NANOTECHNOLOGY
Department of Mechanical Engineering, Article

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Citation Formats
O. Özşahin and H. N. Özgüven, “Identification of bearing dynamics under operational conditions for chatter stability prediction in high speed machining operations,” PRECISION ENGINEERING-JOURNAL OF THE INTERNATIONAL SOCIETIES FOR PRECISION ENGINEERING AND NANOTECHNOLOGY, pp. 53–65, 2015, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/34450.
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