Emre Özlü

Analytical Modeling of Chatter Stability in Turning and Boring Operations—Part I: Model Development

In this paper an analytical model for stability limit predictions in turning and boring operations is proposed. The multidimensional model includes the three-dimensional geometry of the processes resulting in an eigenvalue problem. In addition, a model for the chip thickness at the insert nose is proposed to observe the effect of the insert nose radius on the chatter stability limit. The model represents a development over existing ones due to accurate treatment of the multidimensional process dynamics and geometry, and resulting practical formulas for stability limit predictions. Chatter experiments are conducted for both turning and boring in order to verify the model predictions, and overall, an acceptable agreement is observed.

Analytical modeling of chatter stability in turning and boring operations-Part II: Experimental verification

In this part of the paper series, chatter experiments are conducted in order to verify the proposed stability models presented in the first part (Ozlu, E., and Budak, E., 2007, ASME J. Manuf. Sci. Eng., 129(4), pp. 726-732). Turning and boring chatter experiments are conducted for the cases where the tool or the workpiece is the most flexible component of the cutting system. In addition, chatter experiments demonstrating the effect of the insert nose radius on the stability limit are presented. Satisfactory agreement is observed between the analytical predictions and the experimental results.

TWO-ZONE ANALYTICAL CONTACT MODEL APPLIED TO ORTHOGONAL CUTTING

In this study, the contact on the rake face is modeled analytically using a dual zone contact model at the tool-chip interface. The contact at the rake face comprises a sticking zone near the tool tip and a sliding zone where a Coulomb friction law is assumed. The model provides the values of global quantities (cutting force components, overall friction coefficient, and contact length) and of local variables (stress distribution along the rake face, lengths of the sticking and sliding zones) in terms of physical parameters (sliding friction coefficient, workpiece material parameters) and cutting conditions. The model can be used to characterize the sliding friction coefficient of the Coulomb law from few orthogonal cutting tests. Theoretical results are compared with experimental data in terms of contact lengths and cutting force predictions, and a good agreement is observed.

Feasibility study of a smart motion generator utilizing electromagnetic microactuator arrays

We present a smart rigid body motion generator based on arrays of electromagnetically driven micromembrane actuators. Unlike previous motion generators, this architecture employs a large number of micro-sized (100?200??m) membrane actuators to simultaneously generate the displacement of a large rigid optical mirror. Thus the actuation structure bridges the gap between the micro and macro worlds as well as the incompatibility between MEMS fabrication and traditional optical manufacturing. In order to estimate the feasibility of the architecture, a systematic study was performed on the design and simulation of the individual micromembrane actuator. Each membrane actuator consists of a high magnetization permanent magnet post structure supported by a thin membrane and a planar coil to generate magnetic field. A 3D analytical model is utilized to analyze the actuation performance of an individual actuator cell. The 3D analytical model is proved to be accurate by finite element modeling. It is suitable for fast prototyping design of magnetic actuators. Results show that the presented rigid body motion generator has many advantages including the capabilities of generating large displacement while maintaining fast frequency response and easy manufacturability.