Investigação das vibrações regenerativas no torneamento interno de furos profundos da liga de alumínio 6351-T6

Abstract

The objective of the present study is to understand the influence of vibrations in the internal turning process of an aluminum 6351-T6 test workpiece with a large length-todiameter ratio, combined with the use of a tool also with a large length-to-diameter ratio. Large length-to-diameter ratios can cause regenerative vibrations, which decrease the quality of the machined part. The frequency response functions are identified using an accelerometer, an impact hammer and a smartphone acting as a microphone. With the collected data, analyses of the system’s dynamic characteristics are performed for each combination of overhang lengths, as the practical tests. In addition to the analysis, process simulations are conducted to obtain stability charts, enabling comparison of experimental results with simulations. Regarding the results, the influence of varying the length-to-diameter ratio of both the workpiece and the tool during internal turning is understood. Analyses of the vibrations are conducted, including the frequencies and amplitudes detected during the tests, identifying the unstable component in each case. It is also observed that at low rotational speeds, a damping effect ensures process stability and better surface quality of the workpieces. The practical results were closer to the simulations as the length-to-diameter ratio increased, as evidenced by the stability charts.