OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. 7 No. 3 2025 At the initial stage of running-in, the dispersion of oscillations decreases, and then increases. This trend holds true regardless of whether the equilibrium point is stable or whether various attracting sets of deformations form in its vicinity. The analysis allows us to create an ISS system. The first assessment Π1 is based on an analysis of changes in relative amplitude Ai,s, i, s = 1, 2, 3 increments in the direction s: − = δ − δ δ 1 1 Ï ( ) (0) (0) A A A w , (5) where δ = 3,1 2,1 ( ) ( ) / ( ) A w A w A w , s = 1. The second Π2 assessment is based on determining the ω (C) displacement as w wear increases. However, calculating the average frequency requires significant computing resources. Therefore, an equivalent assessment of two signals passing through low- and high-frequency filters can be considered. In this case, it is not necessary for the cutoff frequencies of the filters to coincide exactly with the frequency ω(C). Then, σ − σ = σ Í 2 ( ) ( ) Ï ( ) Â w w w , (6) where σ ( ) Í w is the dispersion of the VAE signal in the low-frequency range; σ ( ) Â w is the dispersion of the VAE signal in the high-frequency range; σ( ) w is the general dispersion. The signal processing is such that when w = 0, the assessment Π2 = 0. Then, the assessment of Π3 based on (4) is also informative: σ − σ = σ 1 1 1 1 1 1 , , 3 , ( ) (0) Ï (0) X X X X X X w , (7) where σ 1 1 , ( ) X X w is the dispersion assessment calculated using the algorithm in Eq. (4). Parameters of the high-frequency range information space. In the high-frequency range, it is not possible to analytically determine the response of vibration sequences to changes in wear, since the dynamic model has a limited frequency range of validity. However, the cutting process is a source of waves in the frequency range reaching hundreds of kilohertz [5, 15]. We interpret the measured signal in the highfrequency range as an acoustic emission (AE) signal. The source of this signal is the force interactions in the regions (Fig. 6, a) of primary (1) and secondary (2) plastic deformation, as well as in the contact area between the flank face of the tool and the workpiece (3). When measuring this signal, the wave properties of the channel connecting the cutting zone with the AE measurement point are of fundamental importance. It is necessary to take into account not only the dissipative properties of the channel, but also its geometry, as well as joints that introduce nonlinear distortions and an insensitivity zone caused by butt joints [50, 51]. a b Fig. 5. Sensitivity of average frequency ω(C) (a) and relative dispersion σ X1,X2 (b) during variation at different cutting depths (0) P t
RkJQdWJsaXNoZXIy MTk0ODM1