Statistical properties of acoustic emission signals from metal cutting processes

Acoustic Emission (AE) data from single point turning machining are analysed in this paper in order to gain a greater insight of the signal statistical properties for Tool Condition Monitoring (TCM) applications. A statistical analysis of the time series data amplitude and root mean square (RMS) value at various tool wear levels are performed, �nding that ageing features can be revealed in all cases from the observed experimental histograms. In particular, AE data amplitudes are shown to be distributed with a power-law behaviour above a cross-over value. An analytic model for the RMS values probability density function (pdf) is obtained resorting to the Jaynes' maximum entropy principle (MEp); novel technique of constraining the modelling function under few fractional moments, instead of a greater amount of ordinary moments, leads to well-tailored functions for experimental histograms.Comment: 16 pages, 7 figure

Development and validation of the Multi-dimensional University Research Workplace Inventory (MDURWI)

WOS:000454839600005This study describes the development and validation of an instrument aimed toward measuring organizational features of an academic research workplace. The question pool was developed based on data from a pilot study (N = 43). The survey was deployed to academic researchers in the field of higher education research worldwide (N = 850). An exploratory factor analysis conducted on 36 questions, followed by confirmatory factor analysis, which lead to a final pool of 27 questions in five subscales, one of which divided into three lower-order factors. The final model exhibited very good fit (X2/df = 2.561; CFI = 0.972; PCFI = 0.784; RMSEA = 0.043; P[rmsea ? 0.05] < 0.001; AIC = 891.018; BCC = 987.839) and psychometric properties, in the form of factorial, convergent, and discriminant validity, as well as reliability and sensitivity. Implications of this instrument for research and policymaking are discussed, as well as future research directions.info:eu-repo/semantics/acceptedVersio

Automatic tool condition monitoring

W artykule przedstawiono zasady budowy układów diagnostyki stanu narzędzia i procesu skrawania począwszy od ich struktury logicznej przez omówienie wykorzystywanych wielkości fizycznych i czujników, obróbki sygnałów, do sposobów ich integracji w ostateczną diagnozę. Posłużono się przy tym przykładami zaczerpniętymi z budowanych w Zakładzie Automatyzacji i Obróbki skrawaniem układów Automatycznej Diagnostyki Ostrzy Narzędzi Skrawających (ADONiS). W ten sposób przedstawiono główne elementy dorobku naukowego Zakładu w zakresie diagnostyki stanu narzędzia i procesu (DNiPS).This paper presents principles of tool condition monitoring systems development, beginning from their logical scheme, through employing physical phenomena and sensors, signal processing up to signal feature integration into the final tool condition estimation. Tool condition monitoring systems ADONiS built in the Chair of Automation, Machine Tool and Metal Cutting were taken as an example. Thus main achievements of the Chair in TCM were presented

Spindle Error Movements Measurement Algorithm and a New Method of Results Analysis

Machining accuracy depends not only on geometric precision, but also on machine tool spindle error motions. This is particularly important for machining with high rotational speed. Spindle error movements are precisely defined and the method of their measurement methodology is standardized (ISO 230-7 and B89.3.4). Also devices for measuring the error movements are generally known. The main problem is the development of algorithms to ensure the proper measurement, interpretation accordingly to the standards, especially considering so called sensitive and non-sensitive directions. This paper presents an approach and algorithms of spindle errors movements measurement. The proposed methodology is more reliable than commercial solutions

Insert rotational speed of self-propelled rotary tools during turning process

W niniejszym artykule omówiono badania prędkości obrotowej płytki w narzędziach SPRT. W ramach badań opracowano metodę pomiaru prędkości obrotowej płytki. Pomiary prędkości porównano z teoretyczną prędkością, wykazywaną w literaturze. W wyniku badań stwierdzono, że otrzymana prędkość różni się zasadniczo od teoretycznej i zależy nie tylko od prędkości skrawania, ale również od posuwu i głębokości skrawania. Zauważono również, że płytka potrzebuje określonego czasu na uzyskanie stabilnej prędkości, a czas ten zależny jest od parametrów skrawania.The paper presents an investigation of the insert rotational speed dependence on cutting parameters. Original method of measurement of this speed was developed. Obtained results showed that the speed is lower than theoretical, reported in literature and depends not only from the velocity of cutting, but also from a feed and depth of cutting. Finally, the formula on insert speed depended on cutting parameters was investigated. The investigations show also, that the insert needs time for stabilization rotational speed. This time is depend on cutting parameters