Papers by Keyword: Chatter Stability

Abstract: The increasing of vibration stability for the technological system is always the vital task for different material processing. Vibration stability increasing methods are divided into constructive and technological. It’s necessary to take into consideration different factors such as vibration whence, vibration parameters, immediate changing of processing mode possibility while choosing the method of vibration decreasing for the technological systems. The present article is reviewing the research methods of milling technology elements as one of the basis of technological methods for increasing of vibration stability.

Abstract: Dynamic vibration and static deformation are two main factors that affect the machining quality in a long slender shaft turning operation. By simplifying the turning system of a slender shaft into a one-section beam with a clamped-pinned constraint condition, the direct receptance at any arbitrary cutting point is derived. On the basis, the regenerative stability lobes diagram (SLD) for a long slender shaft turing operation is achieved. With the proposed modeling methodology and simulation algorithm, the effect of cutting position on the direct frequency response function (FRF) and the predicated SLD, as well as the effect of the cutting conditions on the predicated SLD are investigated. The predicated direct FRF at the cutting point is validated by hammer tests.

Abstract: In this paper, a new experiment procedure is proposed to study the influence of cutter parameters and clamping methods on the stability of the milling process of thin-walled blade. A dedicated fixture is designed to carry out the experiment. Simulation results show that the new clamping system can enhance the rigidity of thin-walled blade to reduce cutting deformation and chatter vibration phenomenon. Then, cutter and cutting parameters can be optimized properly to make the system obtain high rigidity and high performance stable milling process. Industrial application indicates that the new system can improve the cutting performance and ensure the cutting quality.

Abstract: Chatter is one of the major problems in machining and can be avoided by stability diagrams which are generated using frequency response functions (FRF) at the tool tip. During cutting operations, discrepancies between the stability diagrams obtained by using FRFs measured at the idle state and the actual stability of the process are frequently observed. These deviations can be attributed to the changes of machine dynamics under cutting conditions. In this paper, the effects of the cutting process on the spindle dynamics are investigated both experimentally and analytically. The variations in the spindle dynamics are attributed to the changes in the bearing parameters. FRFs under cutting conditions are obtained through the input-output relations of the cutting forces and the vibration response which are measured simultaneously. Experimentally and analytically obtained FRFs are then used in the identification of the bearing parameters under cutting conditions. Thus, bearing properties obtained at idle and cutting conditions are compared and variations in their values are obtained.

Abstract: In this paper the chatter stability of turning and full-immersion milling operations with spindle speed variation is studied. We present a method to calculate the stability lobes in the limit of very low and very high frequencies of the delay modulation. These approximations help to classify the results of numerically exact methods, as for example semi-discretization or multi-frequency approaches. For slowly time-varying delay, the position of the stability lobes is understandable from a simple connection between the lobes for constant and time-varying delay. Furthermore, this method can be used to estimate the efficiency of an application of spindle speed variation and helps to find optimal parameters for it.

Abstract: During milling operation, the cutting forces will induce vibrations on both the cutting tool and the workpiece, which will affect the topography of the machined surface. Based on the Z-map representation of the workpiece, an improved model is presented to predicate the 3D surface topography along with the dynamic cutting forces during an end milling operation. A numerical approach is employed to solve the differential equations governing the dynamics of the milling system. The impact of cutting parameters such as the feedrate, the axial depth of cut and the dynamic characteristic of milling system on the surface topography is investigated by simulation. The all above can provide some instructive directions to the manufacturing engineers in determining the optimal cutting conditions of an end milling operation.