OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. 4 No. 4 2022 frequency range. This is strongly manifested during grinding in harder modes (St2, St3). The amplitude of the sound level also increases for small values of St (St1), albeit to a lesser extent. For the final processing stage with GW 1, the most characteristic frequency ranges containing significant increases in the amplitude of the sound level are: 2,150 ± 150 Hz; 3,500 ± 300 Hz; 4,900–5500 Hz; and 6,750 ± 200 Hz. We can similarly list the frequency ranges inherent in the final processing stage with GW 2: 2,070 ± 200 Hz; 2,750 ± 250 Hz; and 5,500–6,150 Hz. Thus, due to the differences in the spectral composition of acoustic vibrations and the absence of other factors able to change it significantly, we can affirm that the shape of the grinding wheel significantly affects the spectral composition of acoustic vibrations during processing. Moreover, changes in the cutting capacity during grinding are also reflected in the spectrograms of the process acoustics. We then compare the frequency distributions of acoustic signals obtained when studying the NVF of wheels and the grinding process. To this end, we place the graphs of the NVF (Fig. 5, 6) and the spectrograms of the grinding process at the final processing stage (Fig. 9, 11) in a single coordinate system in a simplified form and make a visual comparison (Fig. 12). Let us single out the main frequency intervals containing significant excess kurtoses which develop in the course of processing. In order to do this, we need to take into account the noise accompanying the operation of the experimental setup units. Figure 12 schematically shows a comparison of the NVF of the grinding wheels and the acoustic signal frequencies recorded during grinding. The dominant natural vibration frequencies of the grinding wheels are 2,062 Hz and 2,337 Hz for GW 1 and GW 2, respectively. These vibration frequencies were used to calculate the propagation speed of the sound wave CL, and to determine the sound index. The graph in Figure 12 shows that there is no complete coincidence of the natural vibration frequencies of the grinding wheel with the frequencies of acoustic signals during grinding, as stated by V.S. Yuganov [23]. However, there are fairly close values of Fig. 12. Comparison scheme of grinding wheels natural vibrations frequencies and frequencies of acoustic grinding signal
RkJQdWJsaXNoZXIy MTk0ODM1