Suppressing boring bar vibrations by parametric excitation

Abstract

Abstract:Machine tool chatter causes an instability that can occur in tool-workpiece-machine system. Hence surface roughness and tool wear in metal cutting processes. This instability caused by interaction between current tool positions and surface left by previous tool passes. Many methods have been developed to minimize the effects of regenerative chatter in machine tools and to enhance the damping capability minimizing the loss in static stiffness through implementation of device uses PZT actuators or MR fluid. The possibility of suppressing selfexcited vibrations of boring process using parametric excitation is discussed. We consider a two-mass system of which the main mass is excited by a self excited force (cutting force). A single mass which acts as a dynamic absorber is attached to the main mass and, by varying the stiffness between the main mass and the absorber mass, represents a parametric excitation. Cutting experiments with an excitation current of different waveforms and diverse frequencies show that chatter can be significantly suppressed by the effect of parametric excitation.

On the self-excitation of vibrations of a boring bar in the process of deep boring

“…5, 6 that the maximal cutting depth grows with the feeding and cutting velocity (the stability region increases), whereas when the boring bar length increases the maximal cutting depth decreases (the stability region decreases). It is to be noted that the obtained results of numerical studies using the developed mathematical model are in good agreement with the experimental data from [8][9][10][11][12][13][14][15][16].…”

“…It is known [1] that console boring bars, being highly effective in boring deep orifices at specialized and general-purpose machines, possess low stiffness, reducing their vibration stability. As a result, a considerable number of works (see [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] and the related references) are dedicated to the numerical-analytical and experimental study of vibrations of console boring bars. This fact, undoubtedly, predetermined further priority of the issue of vibrostability in investigating the dynamics of machines.…”

“…Works on deep drilling and boring are currently widely used in machine-tool industry and mechanical engineering [1][2][3][4][5][6][7], aircraft industry [8], in deep oil-well drilling etc. [8][9][10][11][12][13][14][15][16][17]. They review the main ways of deep boring, systematize the results of the studies and, based on it, present methodologies for designing highly productive tools and technologies.…”

“…Here, it is also found that cutting velocity affects vibrostability less than feeding velocity. In [14][15][16], the possibility of suppressing self-exciting vibrations in the drilling process, using parametric excitation and a specialized tool, is discussed. A two-mass system is considered, of which the main mass is excited by a self-exciting force (cutting force).…”

Theoretical and Experimental Study of a Cement Finish Mill

“…This work is accompanied by a vibration behavior study of the system. The results of theoretical simulation are confronted with experimental measures in order to determine the severity of mechanical faults and to establish an adequate vibratory prognosis [3,4].…”