In-process tool point FRF identification under operational conditions using inverse stability solution

2015-02-01
Self-excited vibrations of machine tools during cutting result in process instability, poor surface finish and reduced material removal rate. In order to obtain stability lobe diagrams to avoid chatter vibrations, tool point frequency response function (FRF) must be determined. In classical machine tool studies, tool point FRF is obtained experimentally or analytically for the idle state of the machine. However, during cutting operations, discrepancies are frequently observed between the stability diagrams predicted by using the FRFs measured at the idle state and the actual stability of the process. These deviations can be attributed to the changes in machine tool dynamics under cutting conditions which are difficult to measure. In this study, a new identification method is proposed for the identification of in-process tool point FRFs. In this method, experimentally determined chatter frequency and corresponding axial depth of cut are used in order to identify tool point FRF. The proposed method is applied to a real machining center and by using chatter tests it is demonstrated that the tool point FRF can be accurately identified under operational conditions.
INTERNATIONAL JOURNAL OF MACHINE TOOLS & MANUFACTURE

Suggestions

Identification of bearing dynamics under operational conditions for chatter stability prediction in high speed machining operations
Özşahin, Orkun; Özgüven, Hasan Nevzat (2015-10-01)
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, ...
Analysis and modelling of machine tool dynamics and cutting stability during operation
Özşahin, Orkun; Özgüven, Hasan Nevzat; Budak, Erhan; Department of Mechanical Engineering (2014)
Self-excited vibrations of machine tools during cutting result in process instability, poor surface finish and reduced material removal rate. In order to obtain stability lobe diagrams to avoid chatter vibration, tool point frequency response function (FRF) must be determined. In classical machine tool studies, tool point FRF is obtained experimentally or analytically for the idle state of the machine. However, during cutting operations, discrepancies are frequently observed between the stability diagrams o...
Analytical modeling of spindle-tool dynamics on machine tools using Timoshenko beam model and receptance coupling for the prediction of tool point FRF
Erturk, A.; Özgüven, Hasan Nevzat; Budak, E. (2006-12-01)
Regenerative chatter is a well-known machining problem that results in unstable cutting process, poor surface quality and reduced material removal rate. This undesired self-excited vibration problem is one of the main obstacles in utilizing the total capacity of a machine tool in production. In order to obtain a chatter-free process on a machining center, stability diagrams can be used. Numerically or analytically, constructing the stability lobe diagram for a certain spindle-holder-tool combination implies...
Dynamic modeling of spindle-tool assemblies in machining centers
Ertürk, Alper; Özgüven, Hasan Nevzat; Department of Mechanical Engineering (2006)
Regenerative chatter is a well-known machining problem that results in unstable cutting process, poor surface quality, reduced material removal rate and damage on the machine tool itself. Stability lobe diagrams supply stable depth of cut ا spindle speed combinations and they can be used to avoid chatter. The main requirement for generating the stability lobe diagrams is the system dynamics information at the tool tip in the form of point frequency response function (FRF). In this work, an analytical model ...
Application of Multivariate Adaptive Regression Splines to Sheet Metal Bending Process for Springback Compensation
Dilan, Rasim Askin; Balkan, Raif Tuna; Platin, Bülent Emre (EDP Sciences; 2016-07-07)
An intelligent regression technique is applied for sheet metal bending processes to improve bending performance. This study is a part of another extensive study, automated sheet bending assistance for press brakes. Data related to material properties of sheet metal is collected in an online manner and fed to an intelligent system for determining the most accurate punch displacement without any offline iteration or calibration. The overall system aims to reduce the production time while increasing the perfor...
Citation Formats
O. Özşahin and H. N. Özgüven, “In-process tool point FRF identification under operational conditions using inverse stability solution,” INTERNATIONAL JOURNAL OF MACHINE TOOLS & MANUFACTURE, pp. 64–73, 2015, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/41507.