• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.261-264
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• 2000

This paper presents a method to identify the on-set of chatter by using the chatter frequency-spindle speed diagram for a milling spindle-workpiece system in face milling process. To this purpose, the eigenvalue problem approach using frequency response function is adopted for predicting both the chatter condition and chatter frequency. The chatter frequency -spindle speed diagram for various conditions is investigated throughout simulation and experiment to diagnose the chatter. The simulation and experimental results show that the chatter frequency-spindle speed diagram is useful for diagnosis of the on-set of chatter vibration.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.977-981
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• 1997

Because the chatter vibration is a main factor to damage on the quality, The cure is require peticually in cylinderical plunge grinding. The chatter vibration is with wheel speed, workpiece speed and infreed rate. Therefore, in this study, we expressed more credible chatter frequency in accordiance with wheel speed by FFT after accereleration sensing.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.1
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• pp.70-78
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• 2004

This paper presents study of efficiency of wavelet transformation for on-line chatter detection during hard fuming process. From comparison with other time series and statistical methods such as fast fourier transformation (FFT), Kurtosis and standard deviation (STD), wavelet transform is better than others in on-line chatter detection. With using wavelet function with pseudo frequency corresponding to chatter frequency, chatter could be detected more sensitively. And for both force signal from dynamometer and displacement signal from capacitance type cylindrical sensor (CCS), wavelet transform with DB2 function on level 4 could be well used for chatter detection in hard turning process.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.3
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• pp.12-18
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• 2001

Frequency domain has been used to detect chatter vibration and to decide commencing point of chatter for the milling processes. For this, power spectrum of accelerations signal is analyzed in the frequency domain. Also, the power spectrum and surface roughness are measured, compared, and evaluated according to the depth of cut by experimental works. As a results, it is known that the commencing point of chatter can be decided the behavior of the maximum amplitude of the power spectrum of acceleration signal and there is a correlation between the power spectrum of acceleration signal and the surface roughness. In conclusion, the power spectrum of acceleration signal can be used as a useful information for detec-tion and estimation of chatter vibration in machining.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1618-1631
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• 1994

In this paper, in-process chatter detection methodology which utilizes nondimensional characteristic variables is introduced. To obtain nondimensional chatter detection indexes which are constant regardless of the cutting conditions during machining with the same tool and workpiece material, both the cutting forces and accelerations are measured and processed in time and frequency domain. The indexes are calculated from the present and past value of the acceleration and cutting force signals in time and frequency domain. The chatter is identified when these chatter detection indexes are bigger than the threshold which is decided by preliminary experiments. The experiment shows that these indexes works very well in-process chatter detection.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.6
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• pp.706-713
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• 1985

It is clear that when the amplitude of grinding chatter increases enough the contact between grinding wheel and workpiece cannot be sustained and the loss of contact occurs during a period of grinding chatter. In this paper the behavior of nonlinear grinding chatter due to the loss of contact has been studied. A nonlinear grinding chatter loop is developed where the loss of contact is considered as a nonlinear element of asymmetrical gain. The analysis is carried out in the time domain by numerical simulation and also in the complex domain by use of describing function method. The results show that two typical patterns of nonlinear grinding chatter can originate from the nonlinearity. One is an irregular chatter frequency at starting stage decreases to the natural frequency of grinding structure while the chatter amplitude increases and decreases repeatedly. The other is a limit cycle chatter of which the amplitude and frequency converge to constant and remain. This nonlinear behavior of grinding chatter has been well analyzed by the describing function method and confirmed by the numerical simulation.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.4
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• pp.76-83
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• 2001

In this study, the static and dynamic characteristics of turning process was modelled and the analytic realization of regen-erative chatter mechanism was discussed. In this regard, we have discussed on the comparative assessment of recursive times series modeling algorithms that can represent the machining process and detect the abnormal machining behaviors in precision turning operation. In this study, simulation and experimental work were performed to show the malfunction behaviors. For this purpose, new Recursive Extended Instrument Variable Method(REIVM) was adopted for the on-line system identification and monitoring of a machining process. Also, we can apply REIVE algorithms in real process for the detection of chatter frequency and dynamic property and analyze the stability lobe of the system by changing a parameter of cutting dynamics in regenerative chatter mechanics, if it is stable or unstable, Also, The stability lobe of chatter was analysed.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.3
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• pp.117-121
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• 1992

There have been many studies on chatter vibration in machining but there seems to be no regulations to decide the commencing point of chatter objectively. The development of an objective method which can estimate and detect chatter commencement is very much in need for automatic manufacturing systems, dynamic performance tests for machine tools, and so on. In this study, an approach for in-process monitoring and for deciding commencing point of the chatter vibration using the frequency band-energy method was proposed. From this method, in-process monitoring system for detection the chatter vibration was developed, and investigated its practical possibility. As a result, it is shown by experiments that the chatter vibtation can be detected accurately. Since the changing pattern of the signal energy in certain frequency band during chattering is seldom affected by the variation of cutting conditions, if adequate pre-measures are taken, this method can be widely used in most machining processes.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.3
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• pp.340-345
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• 2010

This paper presents the chatter stability lobes of high speed spindle of five-axis machine tools. Using a FEM, we obtained the frequency response function of a spindle and the stability lobes for evaluation of chatter. In addition, this paper suggest FRF using by FEM for the prediction of chatter stable region and critical cutting depth. Therefore, critical cutting depth of is 1.3586mm and X, Y direction's chatter frequency is 901Hz and 900Hz, respectively.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.10a
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• pp.85-90
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• 1996

In order to detect and suppress chatter in turning processes a stability control methodology was studied through manipulation of spindle speeds regarding to chatter frequencies. The chatter frequency was identified by monitoring and signal processing of sound pressure during turning on a lathe. The stability control methodology can select stable spindle speeds without knowing a prior knowledge of machine compliances and cutting dynamics. Teliability of the developed stability control methodology was verified through turning experiments on an engine lathe. Experimental results show that a microphone is an excellent sensor for chatter detection and control