Aplicação da distribuição de weibull no monitoramento da operação de torneamento

Abstract

The objective of this work is to determine the ideal moment to exchange the cutting tool in the machining process, using a predictive maintenance procedure, by calculating the vibration values limits through the Weibull statistical method. The experimental procedure was the machining of a stainless steel without cutting fluid and keeping constant all cutting conditions, in which were evaluated the wear of five cutting tools. Where the stop criteria was the cutting tool breaking. During the experiments, signals of vibrations were collected in the tool holder in two channels and also the superficial roughness showed in two points of the machined sample, the vibration symptoms were estimated and constituted by the power levels of acceleration in 26 frequency bands of 1/3 of eighth centered between 10 Hz and 3160 Hz and five statistical symptoms in the domain of the time. 32 roughness parameters had been studied for definition of the criteria of tool end-of-life. After the choice of eight roughness parameters, it was searched, by correlation analysis, the determination of the best correlated vibratory symptoms with the roughness evolution and the time spent. The best vibration signals had been 2500 Hz for canal 1 and 800 Hz for canal 2. After the roughness parameters and the frequencies bands were chosen, the vibrations limit values were determined. The tests carried out within a controlled trial showed that the monitoring of the vibration correlated with the roughness parameters is the adequate method to evaluate the wearing of the cutting tool in a turning process and to establish the end-of-life end life of the tool.