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Illumination for chatter mark detection using machine vision

Szydłowski M., Powałka B., Berczyński S.

Journal of Machine Engineering

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2014

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Vol. 14, No. 2

38--46

EN

Authors of this research present a new method for image acquisition using special illumination for milled surfaces. The presented method uses special light and camera setup to reveal chatter marks on processed surfaces. After the acquisition the images are digitally processed using a method based on Continuous Wavelet Transform. A milling experiment has been preformed for validation of the methods. The biggest advantage of this method is that it doesn't have to be manually set like other image processing methods used in chatter detection.

2

Achievements of the Institute of Manufactur Engineering, in the Field of Machine Dynamics

Bodnar A., Marchelek K.

Machine Dynamics Problems

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2009

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Vol. 33, No. 1

5-15

EN

Selected achievements of the Institute of Manufacturing Engineering in the field of machine tool dynamics are presented. In the first part of the paper the structure of the institute is described. In the main part, the analysis of problems concerning modeling of machine guideways, a method of searching for weak points in the machine tool construction and chatter damping are analysed. The method of modeling guideways, developed in the Institute, is based on original external loads correction concept. The weak points detection method can be applied when modeling a machine tool, at the design stage, or after the experimental examination of the machine. The former employs the sensitivity analysis, the latter includes a study of the influence of machine tool subassemblies relative vibration on the dynamic displacement of the tool relative to the workpiece. Chatter monitoring is based on measurements of generated noise and vibration. Different methods of signal processing were tested, including STFT, WT and Prony's decomposition. The major problem here is the determination of limit values for the analyzed chatter symptoms. Directions of future investigations are sketched.

3

Evaluation of machine tool chatter detection methods based on experimental data

Bodnar A., Bienias-Gębski R.

Vibrations in Physical Systems

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2002

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Vol. 20

108--109

4

Faculty Of Mechanical Engineering, University of Ljubljana, Slovenia

Gradisek J., Govekar E., Grabec I.

Prace Naukowe Instytutu Technologii Maszyn i Automatyzacji Politechniki Wrocławskiej. Konferencje

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1998

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Vol. 69, nr 31

163-172

EN

A method for chatter detection in turning is presented. It utilizes significant differences in dynamics of chatter - free cutting and chatter. Experimentally, chatter was achieved by a change of the cutting depth. The measured time series of cutting forces were characterized by the coarse - grained entropy rate. A high value of the entropy rate is typical of chatter - free cutting, while a low value is typical of chatter. For the purpose of chatter detection, the normalized entropy rate is used and a characteristic threshold is defined. The value of the threshold is independent of cutting conditions.

PL

Przedstawiono nową metodę detekcji drgań narzędzia w skrawaniu. Podstawą metody są duże różnice w dynamice procesu skrawania zależne od tego czy towarzyszą mu, czy też nie, drgania. Niekorzystną dynamikę procesu osiągano przez zmianę głębokości skrawania. Zmierzone szeregi czasowe sił skrawania opisano zmianą entropii. Duża prędkość zmiany entropii jest typowa dla skrawania bezdrganiowego, z drganiami narzędzia natomiast wiąże się mała prędkość zmian entropii. Na potrzeby detekcji wprowadzono prędkość znormalizowaną entropii i zdefiniowano jej wartość progową. Stwierdzono, że wartość progowa nie zależy od warunków skrawania.